High Speed Printer

Abstract

A control system for printers in which an elongated paper document is moved at a substantially constant speed. A plurality of reciprocally mounted solenoid operated print wires are mounted at spaced intervals upon a movable assembly arranged to move along a line transverse to the direction of movement of the paper document. The print wires are selectively operated by electronic and electromechanical means to impact an inked ribbon against the paper document for printing and/or plotting. The movable assembly is designed to fully compensate for the movement of the document to assure that all dots printed along a single row will form a straight line. While only selected ones of the print wires need be operated at any given instant, those selected for operation are all driven against the inked ribbon simultaneously to provide high speed printing and/or plotting of the dot matrix type. Means are provided, in one preferred embodiment, for paper movement of one, five and twelve "dot" feeds to respectively provide for dot row spacing, character line spacing and line feed.

Description

BACKGROUND OF THE INVENTION

The present invention relates to printers and more particularly to high speed impact printers of the dot matrix type in which linear movement of the components comprising the printer is significantly reduced to provide print operating speeds not heretofore obtainable.

Dot matrix printers are well known in the art and are typically comprised of a matrix of print wires (usually arranged in an ordered matrix of seven rows and five columns) in which the print wires are selectively impacted against an inked ribbon which, in turn, is driven against the paper document to form any desired character. The print wires are then physically shifted or moved, in unison, relative to the paper document to the next position to print the next character or symbol. Upon completion of a single line of characters or symbols, the print wire bundle making up the 5.times.7 matrix is rapidly shifted back to the starting position, the document is advanced and the next line of characters is printed in a similar fashion.

In order to reduce the amount of mass required to be moved at high speed during the printing operation, an improved version of the aforementioned technique has been developed, and is set forth in detail in copending applications Ser. No. 35,405, filed May 7, 1970 and Ser. No. 179,457, filed Sept. 10, 1971 and assigned to the assignee of the present invention, wherein the 5.times.7 matrix of print wires is replaced by a set of seven substantially vertically aligned print wires which are advanced in stepwise fashion five times per character to form substantially the same 5.times.7 dot matrix as that described hereinabove. This arrangement still, nevertheless, requires the acceleration, movement and deceleration of the print wires at a very high repetitive rate, thereby severely limiting the print speed and increasing down time due to wearing of the moving components. Also, the distance traveled by the print head is double the width of a line of print.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is characterized by providing a high speed impact printer of the dot matrix type in which the print wires undergo significantly reduced linear movement transverse to their longitudinal axes, and wherein the paper document is moved at a cooperating speed during the printing operation so as to greatly enhance overall operating speed, print capabilities and simplicity of the device.

The present invention is comprised of a plurality of solenoids, each being provided to drive a slender print wire. All of the solenoids are mounted upon a movable mounting assembly with each of the print wires being guided by suitable guide means so as to be arranged along a substantially horizontal line with their forward ends being positioned to reciprocate within a small diameter opening formed in a jewel bearing whose forward face is in close proximity to the printer platen. An elongated inked ribbon is positioned between the forward surface of the platen and the jewel bearing so as to be driven into a paper document riding over the platen when impacted by the print wires. The ribbon is preferably drawn between a pair of reversibly movable spools so as to continuously move the ribbon in either the forward or reverse direction during the printing operation to provide for even wearing of the ribbon.

The paper document may be perforated along either or both of its marginal edges so as to cooperate with drive means capable of advancing the paper document at high speeds, or may be moved by a conventional rotatable roller type platen.

The printer electronics is comprised of input means for receiving data in either serial or parallel fashion and feeding the data in parallel fashion into a multistage shift register capable of storing a multiplicity of binary words, each representing a particular character or symbol.

Once the register is fully loaded, or is loaded to the desired amount (i.e., to respectively print a full line or less than a full line) the contents of selected stages of the register (containing the binary bits representing a character or symbol) are applied to conversion means for each character which may (for example) be a character generator adapted to provide output signals in binary form at selected ones (or all) of its plurality of output terminals representing the first or top line of the five by seven matrix for the associated characters. These signals are, in turn, employed to selectively trigger the operation of the print wire solenoids to form "dots" at spaced intervals along the top line of the characters to be printed. The mounting assembly, which is continuously advanced, is operated at discrete small intervals to print each dot group. Suitable stepping means, such as, for example, a counter, is employed for triggering the character generators to provide binary output signals at the appropriate output terminal of the character generator representative of the next dot in the top-most row of the five by seven matrix. These signals are then employed to selectively operate the associated print wire solenoids. The stepping operation continues until all dots along the top row of the five by seven matrix have been printed, at which time the entire top row (i.e., first dot row) of 80 characters (for example) have been printed. The mounting assembly is then returned to the start position while the paper document continues to move so that, upon return to the start position, the dot spacing between rows is automatically obtained. The second row of dots of the five by seven matrices are then formed in a similar manner.

Upon completion of the seventh dot row the document feed device is caused to operate to separate the completed line of characters from the next line to be printed. During this stepping operation, hereinafter referred to as a "five dot skip," binary code groups for the next line of characters are shifted into the register, and as soon as the register is loaded (either completely or to the extent desired) the operation is continued for the next line of characters. Each line of characters is printed in a similar fashion.

A line of characters of double width may be printed by causing each column of the 5.times.7 matrix forming a character to be printed twice, thus creating a character of double width, if desired. As a further alternative, characters of a single row may be both double and single width if desired.

As a further alternative, the high speed impact printer may be adpated to print or plot curves by selective energization of the print wire solenoids to cause one or more than one of the dots on any given line to be printed whereby those dots, in cooperation with the dots of other lines, are caused to form a curve or a plurality of curves useful in graphic presentation of data. The printer thereby provides a capability of printing characters at rates faster than those conventionally available thorugh the above described features and techniques.

By moving the horizontally aligned solenoid mounting assembly at a slight angle relative to the horizontal direction, the paper document may be moved continuously, and formation of a perfectly horizontal straight row of dots is assured, thus significantly reducing the complexity of the mechanism for moving the paper document.

The spacing of the solenoids over a distance slightly less than the width of the paper document enables an entire row of dots to be printed while the mounting assembly physically moves only a fraction of the width of a full line of characters.

Perfect registration of the dot patterns formed is assured through the use of a registration means which also serves to identify the location of the print solenoids at any given instant.

The electromechanical system for controlling and synchronizing all of the printer operations provides for one, five and 12 "dot feeds" to respectively perform dot row spacing, character line spacing and high speed line feed(s).

The printer solenoid carriage assembly is preferably a "split" arrangement to accommodate ledger type entries or other applications in which two printer solenoid assembly halves may be operated to the exclusion of the other.

The printer head assembly is further designed in one alternative embodiment, to provide for rapid reversal of the print wire positions to assure even wearing of the print wires through long continued use.

Whereas the description of the preferred embodiments teaches a printer capable of providing a five by seven matrix for each character position, embodiments having up to a nine by nine matrix per character position in the line printing mode are also contemplated. Such an arrangement requires a modification whereby the print head is shuttled nine times per line of characters, where a three-dot skip is provided between lines of characters. The nine by nine matrix provides for printing of both upper and lower case characters as well as "below the line" symbols such as cursors, commas, colons and the like. The nine by nine matrix also may be adapted to print complex special characters, and foreign language characters, such as ideographs.

OBJECTS OF THE INVENTION

It is therefore one object of the printer invention to provide a novel high speed impact printer in which printing of characters is undertaken partially serially and partially parallel for each line of characters, and serially line by line to form characters and/or symbols to plot curves.

Another object of the present invention is to provide a novel high speed impact printer in which the number of moving parts employed is significantly reduced, so as to reduce the amount of mass otherwise required in conventional impact printers of the dot matrix type.

A still further object of the present invention is to provide a novel high speed impact printer of the dot matrix type in which the double width characters may be printed in a simple manner.

Another object of this invention is to provide a novel feed mechanism for dot matrix printers to perform both character printing and curve plotting.

Still another object of the present invention is to provide a novel "split printer solenoid" assembly for mutually exclusive operation of the solenoid assembly halves to perform ledger entries and the like.

BRIEF DESCRIPTION OF THE FIGURES

These as well as other objects of the present invention will become apparent when reading the accompanying description and drawings in which:

FIG. 1 is a perspective view showing an array of print wires and operating solenoids which are employed in the apparatus of the present invention and incorporating the principles thereof.

FIG. 2 is a diagrammatic view showing the pertinent mechanical components of the paper feed system and its associated optical and electronic circuitry for controlling dot registration and identifying solenoid location.

FIG. 2a is a detailed perspective view of one planetary gear assembly of FIG. 2.

FIGS. 2b-2d are left end, sectional and right end views, respectively, of one clutch assembly of FIG. 2.

FIG. 3 is a block diagram showing the electronics employed in the printer of FIGS. 1 and 2.

FIGS. 4a-4c are top, front and end views respectively, of a split printer solenoid assembly.

FIG. 5 shows some of the characters generated by the printer of FIG. 1.

FIGS. 6a-6n are detailed schematic diagrams of the diagrammatic blocks shown in FIG. 3.

FIG. 7a is an elevational view, partially sectionalized, showing another print head embodiment of the present invention.

FIG. 7b is a front view of the assembly of FIG. 7a looking in the direction of arrows 7b--7b.

FIG. 7c is a top plan view showing a portion of the assembly of FIG. 7a looking in the direction of arrows 7c--7c.

DETAILED DESCRIPTION OF THE INVENTION

The printer of the present invention is an impact printer utilizing a five by seven dot matrix to produce each character when in the printing mode or, alternatively, utilizing any one of a plurality of the print wires when operating in the curve plotting mode. The unit, in one preferred embodiment, prints an array of 80 characters per second. The printer in this embodiment, is capable of printing 80 characters per line with a varying paper width dependent only upon the needs of the user. The device utilizes an elongated paper document or any other suitable paper feed device, and generates of the order of 12 dot lines to the inch including the space between the lines with 10 characters per inch horizontally. The printer requires no special paper and can produce an original plus seven copies, with the seventh copy being very readable. It should be understood that a greater or lesser number of print wires may be employed, dependent only upon the particular application.

PRINTING METHOD

The printing of characters is accomplished by moving the paper document at a substantially constant speed upon the platen by mechanical movement. The top row of dots of all characters are formed in the following manner:

The movable mounting assembly, in one preferred embodiment, has eight solenoids mounted at uniformly spaced intervals. In the case where each line comprises 80 characters, the solenoid print wires are spaced at one inch intervals. In the case of 10 characters to the inch, and five dot columns per character and a dot space between characters, the solenoids are selectively operated up to a maximum of 59 times during movement, or a total distance of approximately one inch in the "print" direction to complete each row of a line of characters. The mounting assembly is then returned to the start (i.e., left-hand-most) position in readiness to print the next dot row of a line of characters. Seven rows of dots are printed to form a line of (up to 80) characters, each defined by a five by seven matrix pattern. Obviously, any other arrangement may be employed to print a greater or lesser number of characters.

Each individual solenoid independently forms up to ten characters in a fashion which is most analogous to the manner in which an electron beam scans the face of a cathode ray tube (i.e., in the line-by-line fashion employed in television receivers).

Accurate spacing of the dots in each row, and hence the time of printing is initiated by a strobe pulse derived from an optical pick-up head which cooperates with a stationary slotted Mylar strip having a slot provided for each dot position along the horizontal row of dots. A spacing of one dot size between characters is provided. Alternatively, the optical pickup head and light source may be stationary and the slotted strip may move with the print head.

The printing of the characters is accomplished by the print wires which are solenoid driven to move the print wires against an inked ribbon to produce dots on the original copy. The firing of the solenoids occurs only during the presence of the strobe pulse derived from the optical pick-up head. This pulse is of a duration of 450 microseconds with a relax time of 550 microseconds. The characters are printed such that one "slice" (i.e., "dot row") of each of the characters in a line (which may, for example, be 80 characters) is printed along each row of dots. Seven closely spaced rows of dots are printed, thereby forming a five by seven matrix for each character printed within a line of characters. Spacing between horizontal rows of dots is of the order of 0.015 inches and between character lines is of the order of the spacing between five horizontal rows of dots.

COORDINATION BETWEEN PAPER MOVEMENT AND SOLENOID MOVEMENT

The movement of the paper, in one preferred embodiment, is constant regardless of the fact that single line feeds or multiple line feeds are desired. A single motor is used as a source for the power necessary to move the platen at a constant speed. The mounting assembly moves the solenoids at a slight angle to the horizontal direction to synchronize relative vertical movement of the solenoids with vertical movement of the paper to assure printing of a horizontal straight row of dots. During the return stroke, the relative downward movement of the solenoid mounting assembly cooperates with the continuous upward movement of the paper to provide accurate spacing between horizontal rows of dots.

In the preferred embodiment of the USASCII Code is employed. This code is a six-bit code enabling 64 different combinations of characters to be generated. Obviously, a greater or shorter code bit length may be employed in cases where a greater or lesser number of characters are desired for the printer. The timing count pulses derived from the column position counter of character registration control unit are employed to control the firing of the eight solenoids associated with each character generator. The first dot of the first "dot row" for the first, eleventh, twenty-first . . . and seventy-first characters to be printed on that line are formed during column position timing unit No. 1, the second dot of the first dot row for the aforesaid characters to be printed are formed during time unit No. 2, and so forth, until the top row of dots of the aforesaid characters has been completed. Thereupon, the sixth timing unit is used to allow for a space, and thereafter the first dot of the first row of dots for the second, twelfth, twenty-second, . . . and seventy-second characters are printed. This operation continues until the first dot row of the line of characters being printed is completed.

The last timing unit is employed to advance the row counter and return the solenoid carriage to the start position, which provides the proper dot spacing between the top-most row of dots and the next row of dots.

The row counter output, together with the output data from the character register, causes the character generator to develop signals representative of the next row of dots for the line of characters presently being printed. The column position counter again controls the solenoids to print the first through the fifth dots on the second dot row for the first, eleventh, twenty-first . . . and seventy-first characters, then a space, then the first through the fifth dots on the second dot row for the second, twelfth, . . . and seventy-second characters, and so forth, until all dots of the second dot row are completed. The third through the seventh rows of dots are printed in a like fashion. It should be noted that only one character generator (to be more fully described) is provided, with the character generator being sequentially controlled during the examination of each character. Sequential coupling is accomplished by shifting the encoded data in the character register one position to the right upon the occurrence of every sixth count (i.e., space condition) of the row position counter. The first encoded character shifted out of the right-hand end is then shifted into the left-hand end of the register through a feed-back loop. This continues until 10 coded characters have been shifted, at which time the end of line signal resets the solenoid carriage to the start position to begin a new row of dots. As the carriage is returning to the start position, the coded characters are rapidly shifted to the right (and inserted at the left end) by oscillator 19a which is controlled by the end of line signal until a special coded start character arrives in the right-hand-most (i.e., first position) of register 15 so that all coded characters are returned to their original positions within register 15, in readiness for printing the next row of dots.

FIG. 5 shows the dot patterns for some typical characters, with the dot spacing being exaggerated relative to normal spacing to simplify their understanding. The solid circles indicate dots to be printed. In each case the order of printing is row 1, dot positions 1, 2, 3, 4, 5 . . . until row 1 is complete; row 2, positions 1, 2, 3, . . . until row 2 is complete; and so forth, until seven dot rows are completed, thereby completing one line of characters.

The seven output lines of the character generator are selectively coupled through a multiplexer and buffer register, to the inputs of associated solenoid driver circuits where the signals are amplified by suitable amplifiers to produce a current controlled pulse to the solenoids to cause selective firing of the associated print wires.

The printing portion of the system consists of the solenoid and print wires which provide for the impact printing of the characters. The solenoids, when operated, drive the print wires against an inked ribbon to form dots on the paper document which dots are arranged at selected positions along each horizontal dot row. The rearward ends of the print wires are coupled to solenoid armatures as is shown and described in detail in copending applications Ser. No. 37,815, filed May 15, 1970 and Ser. No. 152,598, filed June 14, 1971. The forward ends of the print wires extending from each solenoid are positioned for reciprocal mounting within a jewel bearing provided with openings for each print wire, which openings are arranged along an imaginary horizontal line.

FIG. 1 is a perspective exploded view to facilitate an understanding of the invention and showing the solenoid and print wire carriage assembly 10, which is comprised of a movable platform 11 having solenoid mounting member 12 provided with a plurality of tapped apertures 12a for threadedly engaging the forward threaded portions 13a of solenoids 13. The solenoids are described in detail in copending applications Ser. NO. 37,815, filed May 15, 1970 and Ser. No. 152,598, filed June 14, 1971, which descriptions are incorporated herein by reference thereto. For purposes of the present invention, it is sufficient to understand that the solenoids 13 are each provided with solenoid coils for operating an armature to drive its associated print wire 13b in the impact direction (see arrow A) against the force of a biasing spring. Release of the electrical energy places the print wire under control of the biasing spring which causes the print wire to move in the direction of arrow B to return the print wire to the non-printing or standby position.

Each of the solenoids is provided with a pair of leads 13c for coupling to the system electronics, and more particularly, to the solenoid drivers (see circuit of FIG. 6c) for energization of the solenoid coils.

The forward or impact ends of the print wires 13b impact the inked ribbon 15 and paper document 20 to form dots whereby adjacent dots are spaced apart a distance of the order of 1/60th of an inch. Portion 12a of the mounting member 12 is provided with jewel bearing members 14 to retain the print wires in the desired horizontal alignment. Alternatively, the wires, which are mounted within guide tubes 13d, may each be provided with jewel bearings at their forward ends. The actual dimensions of FIG. 1 have been exaggerated to clarify an understanding of the structure. The jewel members 14 each slidably receive the forward ends of their associated print wires 13b. The front face of each jewel 14 is positioned in close proximity to ribbon 15, substantially aligned with the jewels and extending between feed and take-up reels 16 and 17, respectively. Rollers 18a-18d are spring loaded and act to maintain the ribbon extending between ribbon reel 16 and 17 under tension. Operation of any of the solenoids 13 causes the associated print wire to be impacted against the inked ribbon 15, and thereby drives the ribbon against a paper document 20, positioned between inked ribbon 15 and a backing platen 21, to cause the dots to be formed. The total linear movement in the impact direction of the wires is approximately 0.015 inches. Under normal operation, the end of each print wire is approximately 0.006 inches from the ribbon and paper. This spacing is due to the fact that a great deal of force is absorbed by the ribbon and the paper upon impact.

The solenoids move along a slightly inclined path. A pair of rails 22 and 23 are arranged in spaced parallel fashion, and are inclined at the desired angle relative to the longitudinal axis of platen 21. Movable platform 11 rides between rails 22 and 23. Cylindrical bearings 24 are provided between the grooves 22a and 23a in rails 22 and 23 and grooves 11a and 11b in platform 11. The head 12, upon which the solenoids 13 are mounted is tilted at its left-hand end relative to platform 11 (by a suitable shim, for example) so as to align head 12 in the horizontal direction and parallel to the central axis 21a of platen 21. A pair of projections 11c (see FIG. 2) secured to the underside of platform 11 extend downwardly and receive a shuttle cam 114b formed on cylinder 114a. The cam sits in the space between projections 11c. Shuttle cam 114 is rotated by motor M through a mechanical coupling (to be described in connection with FIG. 2) between motor M and shaft 103. One full revolution of cam 114 moves platform 11 toward the right from the start (left-hand-most) position to the right-hand-most position and returns the platform to its start position (moving right to left).

Although an intermittent type paper feed mechanism becomes more complicated due to its need to advance the paper accurately through such a small distance, the paper may nevertheless be advanced in a row at a time fashion and be held motionless during the printing of each row of dots. This arrangement avoids the need for inclining rails 22 and 23. Operation in all other respects remains substantially the same as described above.

Considering FIG. 1a of copending application Ser. No. 204,024, 60 represents a dot printed at time t.sub.0. Immediately thereafter, solenoid S (solid circle) moves to position S' to print dot 61. During this time, dot 60 has moved upward to location 60' (due to the fact that the paper moves continuously in the direction of arrow A). Thereafter, the solenoid moves from S' to S" to print dot 62. During this time the paper moves upward (arrow A) moving the first dot from location 60' to 60" and moving the second dot from location 61 to 61'. By diagonal movement of solenoid S (through its carriage 40) all three dots lie along a straight line (dotted line 63). It should be noted that the spacing between the dots in FIG. 1a has been exaggerated to facilitate an understanding of the operation, typical center to center spacing between dots being of the order of 0.015 inches. Typical dot diameter is of the order of 0.0145 inches.

The speed of movement of paper 20 and the carriage assembly is further so chosen so that during the time it takes the carriage assembly to move to its right-hand-most position and then return to its left-hand-most position (which limiting positions may be controlled by stops) the paper 20 will have moved a distance equal to the spacing between adjacent dot rows forming a character. This is aided by the fact that whereas the carriage assembly moves upward and to the right during printing, it moves downward and to the left during carriage return. In one preferred embodiment, the paper moves a distance of the radius of a dot during printing so that during a carriage return the movement of both the paper and the carriage through one radius each amounts to a total combined movement of one diameter of a dot.

FIG. 2 shows the major components of the printer utilized to perform the various types of line feed operations required for successful operation of the printer. As was previously described, so far as the preferred embodiment is concerned, the underlying concept is to provide for continuous movement of the indeterminate length paper document when printing and to provide for high speed "skips" or paper movement during non-printing periods. The three modes of operation are as follows:

Mode 1 -- In this mode the paper document is continuously advanced at printing speed while the shuttle head, i.e., the printer movable solenoid assembly shuttles to the right and then to the left to perform the printing and return operations respectively.

Mode 2 -- In the line printing mode, and after a line of characters has been printed, paper is advanced to perform a high speed skip to provide a spacing of five dot lines between the line of characters just completed and the next line of characters to be printed. During this operation the paper moves at more than four times the rate at which the paper is advanced during the normal printing operation.

Mode 3 -- Line Feeds -- In this mode, no printing is performed and the paper is advanced at a rate of speed which is more than 20 times greater the speed of advancement during the normal printing mode. As many line skips as are required may be performed in a consecutive fashion to provide greater than line to line spacing between lines of characters.

Referring specifically to FIG. 2, there is shown therein a printer mechanism 100 comprised of a motor M having an output shaft 101 provided with a gear 102. A second shaft 103 also provided with a gear 104 is mechanically coupled to gear 102 by means of a pulley (timing belt) 105 having protrusions or teeth adapted to engage the teeth of gears 102 and 104.

Gear 104 is free wheelingly mounted upon shaft 103 when clutch C.sub.1 is disengaged. upon the engagement of C.sub.1, shaft 103 is caused to rotate with the rotation of gear 104. Gear 104 is actually a two-part gear having a portion 104a whose gear teeth engage the teeth of timing belt 105 and having a second portion 104b also free wheelingly mounted relative to shaft 103, but always being rotatable in synchronism with portion 104a. The gear teeth of gear portion 104b mesh with the gear teeth of gear 106 which is free wheelingly mounted upon shaft 107 when clutch C.sub.2 is disengaged. However, upon engagement of clutch C.sub.2, shaft 107 will rotate in unison with the rotation of gear 106.

The gear teeth of gear 106 mesh with the gear teeth of gear 108 which is free wheelingly mounted upon shaft 109 so long as clutch mechanism C.sub.3 is deenergized. Upon energization of clutch mechanism C.sub.3 shaft 109 is caused to rotate in unison with gear 108. It should be noted that, so long as motor M is energized, gears 104, 106 and 108 are always rotating. However, as will be more fully described, only one of the clutch mechanisms C.sub.1 -C.sub.3 is normally energized at any given time so that only one of the shafts 103, 107 and 109 will normally be caused to rotate at any given instant.

Each of the clutch mechanisms C.sub.1 -C.sub.3 is provided with an actuating solenoid mechanism 110, 111, and 112, respectively which serves to actuate its associated clutch mechanism. As will be more fully described, each clutch mechanism remains in the actuated state for only one complete revolution or a predetermined portion of one revolution and is adapted to automatically become deactivated upon the completion of one revolution (or a portion thereof).

In the printing mode (Mode No. 1) solenoid 110 is energized causing clutch C.sub.1 to become actuated for one complete revolution thereby locking shaft 103 to gear 104 and causing shaft 103 to rotate for a full revolution. A gear 113 is locked to the opposite end of shaft 103 as is a shuttle cam mechanism 114 comprised of a solid cylindrical member 114a having a continuous cam member 114b in the form of a flange. Shuttle cam 114b rides between a pair of projections 11c, 11c extending downwardly from platform member 11 upon which head 12 is mounted. Circles 13 represent the solenoids fixedly secured to head 12 as shown best in FIG. 1.

A full rotation of gear 104 and shaft 103, gear 113 and shuttle cam 114 causes the printer solenoid assembly to move to the right as shown by arrow A a distance of the order of one inch during the first half of a full revolution to perform the printing operation and immediately thereafter causes platform 11 to move to the left as shown by arrow B after completion of the printing operation to return the platform 11 to the rest or ready to print position which is the position occupied by platform 11 in FIG. 2.

At this time the movement of the paper must be synchronized with the shuttling of the platform 11 and hence the solenoids 13. This is accomplished by means of a gear train comprised of gear 113 which meshes with gear 115 mounted upon shaft 116. Gear 115, in turn, meshes with gear 117 mounted upon shaft 118. The opposite end of shaft 118 is provided with a gear 119 which rotates with the rotation of gear 117 and shaft 118 and which meshes with gear 121 which forms part of a planatary gear assembly 120. The planatary gear assembly 120 is shown in FIG. 2a and is comprised of gear 119 mounted upon shaft 118. Gear 119 meshes with a planet gear 121 mounted on a common shaft 122 with planet gear 123. Shaft 122 is mounted within a suitable opening provided in sun gear 124 so as to be capable of being free wheelingly rotated relative to sun gear 124. Both planet gears 121 and 123 are locked to shaft 122 so that any rotation of either gear is imparted to the other.

Planet gear 123 meshes with output gear 125 which is mounted upon shaft 126. Sun gear 124 is mounted upon shaft 127. Whereas shafts 118, 127 and 126 are arranged along a common longitudinal axis 128, it should be noted that these three shafts are independent of one another as can best be seen in FIG. 2.

Sun gear 124 meshes with a gear 130 mounted upon shaft 107 which cooperates with gear 106 (previously described) in a manner to be more fully described. In the printing mode (Mode No. 1) shaft 107 and gear 130 remain stationary causing sun gear 124 to remain stationary. With gear 104 locked to shaft 103, a driving connection between gear 104, shaft 103, gears 113, 115, 117, shaft 118 and gear 119, causes gear 121 to rotate. Shaft 122 thereby rotates causing rotation of planet gear 123 which meshes with and drive gear 125. Rotation of gear 125 causes its shaft 126 to rotate which, in turn, causes rotation of gear 132 which is locked to shaft 126. Gear 132 drives a gear 133 mounted upon and locked to shaft 134. Shaft 134 has provided at its opposite end a gear 135 which is locked thereto and which forms one of the gears of a second planetary gear assembly 136. This planetary gear assembly is substantially identical to the planetary gear assembly shown in FIG. 2a and hence an additional figure therefore will be omitted for purposes of simplicity. It is sufficient to understand that this planetary gear assembly 136 is comprised of a sun gear 137 mounted to selectively rotate about shaft 138. Gear 137 is provided with an opening for free wheelingly receiving shaft 139 upon which is mounted a pair of planet gears 140 and 141 which are locked to shaft 139. Planet gear 140 meshes with gear 135 while planet gear 141 meshes with output gear 142 which is fixedly secured to shaft 143 so as to rotate in unison therewith. A gear 144 is fixedly secured to the opposite end of shaft 143 so as to rotate with the rotation of gear 142 and shaft 143. Gear 144 meshes with a gear 145 locked to shaft 146. The opposite end of shaft 146 is provided with a gear 147 locked thereto. Gear 147 meshes with a gear 148 which is fixedly secured to shaft 149. Also fixedly secured to shaft 149 is a timing gear 150 which cooperates with a timing gear 151 by means of a timing belt 152 which is entrained about timing gears 150 and 151.

Timing gear 151 is mounted upon and locked to an elongated shaft 153 which runs substantially the entire width of the printer mechanism and has mounted thereon a pair of adjustable pin feed mechanisms 154 and 155 for accommodating paper of varying width. Each of the pin feed mechanisms is adapted to rotate in unison with the rotation of shaft 153. These mechanisms are provided with equally spaced pins 154a and 155a, respectively, which cooperate respectively with similarly equispaced openings provided along the opposite parallel sides of the paper document so as to feed the paper document thereby.

As was described hereinabove, actuation of clutch C.sub.1 occurs by means of pulsing the clutch solenoid 110 (for 35 milliseconds in the preferred embodiment) to provide for one full revolution of the shuttle cam 114. One full revolution provides for movement of the printer solenoid platform 11 from the start position (shown in FIG. 2) to the right-handmost position (during the first half revolution) and subsequently returning platform 11 to the start position (i.e., the no-print portion of the revolution). Simultaneously therewith through the gearing connections described hereinabove, the paper document is fed through a distance equivalent to the spacing between adjacent dot rows. In the preferred embodiment the paper is moved at a constant rate of speed which is 0.1 inches per second.

The clutch mechanism which may be employed for the three clutches C.sub.1 -C.sub.3 as shown in FIGS. 2b-2d wherein FIG. 2c shows a side view partially sectionalized, FIG. 2b shows a left-hand end view of the assembly of FIG. 2c and wherein FIG. 2d shows the right-hand end view of the assembly of FIG. 2c. The clutch assembly C.sub.1 (it being understood that the other clutch assemblies are similar) is comprised of a core member 161 having a tapped aperture 161a for receiving a threaded fastener to secure a shaft 103 passing through the central opening 161b in core member 161. Shaft 103 is then locked to core member 161b so as to undergo any rotation imparted to core member 161. The clutch assembly is further comprised of a gear member 162 provided with a central opening 162a. Core member 161 is fitted through this central opening. A ring 163 overlies the hollow annular space between the central opening in gear 162 and the outer periphery 161c of core member 161 and is locked in position by a locking ring 164. Three cylindrical shaped rollers 165a, 165b and 165c are arranged between the outer periphery 161c of core member 161 and the inner periphery of a ring 166 mounted within the central opening 162a in gear 162. Three arcuate shaped portions 167a, 167b and 167c are arranged in a space between ring 166 and the periphery 161c of core 161 and act to maintain a 120.degree. spacing between the central axes of cylindrical rollers 165a-165c.

As can best be seen from FIG. 2d, the periphery 161c of core member 161 is provided with three flat portions 161c-1, 161c-2 and 161c-3 arranged respectively at 120.degree. angles relative to one another about peripheral portion 161c. The inner periphery of ring 166 makes rolling engagement with cylindrical rollers 165a-165c while the flattened portions 161c-1 through 161c-3 make engagement with cylindrical rollers 165a-165c, respectively. With these flat portions arranged at a particular angular orientation, rollers 165a-165c are "pinched" between ring 166 and peripheral portion 161c causing any rotation of gear 162 to be imparted to core member 161 and hence to be imparted to shaft 103 which is fixedly locked to core member 161. The shifting of the roller bearings 165a-165c relative to flat surfaces 161c-1 through 161c-3 is accomplished by means of a lever arm 168 mounted to pivot about a pin 169 secured to a substantially circular shaped disc 170. A second pin extends through lever 168 and plate 170. This pin 171 is provided with an annular groove 171a which receives one end 172a of a biasing spring 172 whose opposite end is secured to a pin 173 which is mounted to plate 170. Spring 172 normally biases lever 168 in the clockwise direction as shown by arrow 174 in FIG. 2a.

Lever 168 is provided with a notched portion 168a having an engaging surface 168b which is arranged to be struck by the actuating pin 110 of clutch solenoid 110.

The operation of the one revolution clutch assembly is as follows:

In the case where the clutch assembly is normally deactivated, solenoid 110 is deenergized at such time causing actuating pin 110a to abut against the engaging surface 168b of lever 168. This causes lever arm 168 to be urged in the counterclockwise direction about its pivot pin 169 against the biasing force of spring 172 resulting in the movement of arcuate section 167b through a coupling provided between head 171b of pin 171 and an arm portion 167b-1 of arcuate section 167b. This arrangement moves the cylindrical bearings 165a-165c to the center portion of the straight surfaces 161c-1 through 161c-3, respectively. In this position rotation of gear 162 is not imparted to core member 161 and hence shaft 103 is prevented from rotating. It should be noted that plate 170 is likewise prevented from rotating at this time.

When it is desired to couple the rotation of gear 162 to core 161 and hence shaft 103, actuating solenoid 110 is energized causing actuating pin 110a to be removed from abutting engagement with surface 168b of lever arm 168. This places lever arm 168 under the control of biasing spring 172 causing lever arm 168 to pivot in the clockwise direction as shown by arrow 174 about pin 169. This causes arcuate section 167b (through its coupling with lever arm 168 and pin 171) to also move in the clockwise direction, as shown by arrow 174 in FIG. 26 to move the cylindrical rollers 165a-165c into wedging relationship between ring 166 and the flat surfaces 161c-1 through 161c-3, respectively. This causes the cylindrical rollers 165a-165c, the arcuate sections 167a-167c, the core 161 and shaft 103 to rotate in unison for one complete revolution. Solenoid 110 remains in the energized state withdrawing actuating pin 110a preferably for a period of 35 milliseconds which is considerably less than the time it takes for gear 162 to complete one revolution. Actuating pin 110a thus is moved away from abutting surface 168b of lever arm 168 for a period sufficient to allow lever arm 168 to clear the retracted actuating pin 110a as it starts through a one revolution turn. However, as was previously described, actuating pin 110a returns after a 35/millisecond interval during which solenoid 110 is energized to the abutting position so as to strike against abutting surface 168b as it is completing its one revolution turn.

The one revolution clutch mechanism shown in FIGS. 2b-2d may be converted to a half revolution clutch mechanism through the provision of a second lever assembly 168' shown as being positioned along a diameter of plate 170. Since this mechanism is substantially identical in design and function to the lever mechanism 168 already described hereinabove a description thereof will be omitted for purposes of simplicity. In the case where it is desired to employ a half revolution actuating mechanism while retaining the same full-revolution shuttle cam operation, it would be obvious to provide the appropriate gear teeth ratios and gear diameters to provide the appropriate operation for the desired paper movement and solenoid platform assembly movement. In such case, actuating pin 110a would strike the engaging surface 168b' of lever arm 168' after a half revolution to resume the free wheeling relationship between gear 162 and shaft 103. Again it should be noted that the 35 millisecond interval in which actuating pin 110a is retracted is of a sufficiently long period of time to permit lever arm 168 to clear the retracted actuating pin but is of a sufficiently short interval so as to place actuating pin 110a back into the abutting position well before a half revolution is completed so that it will abut against the abutting surface 168b' of lever arm 168' (or surface 168b of lever 168). It should further be understood that lever arm 168' is coupled through its movable pin 171' to the arcuate section 167c which is provided with an extending projection 167c-1 having an aperture for receiving the opposite end of pin member 171' as shown best in FIG. 2c.

It should be understood that the clutch mechanisms C.sub.2 and C.sub.3 operate in a manner similar to that described hereinabove with regard to clutch mechanism C.sub.1 and that their associated actuating solenoids 111 and 112, respectively, operate in a similar fashion.

FIVE DOT SKIP

It should be understood from the description set forth hereinabove that seven consecutive dot rows are printed to make up one line of characters and that clutch mechanism C.sub.1 will be operated seven consecutive times to perform this operation. Upon the completion of the seventh dot row, it is desired that the printer go into the Mode 2 operation in wich no printing occurs and in which spacing of the equivalent of five dot rows will be provided for between the seventh dot row of the line of characters just printed and the first dot row of the next line of characters to be printed. This operation is achieved through the clutch actuating solenoid 111 which operates clutch C.sub.2. Immediately prior thereto gear 106 is in free wheeling relationship with shaft 107. Upon energization of solenoid 111 shaft 107 is locked to rotate with gear 106 causing the gear 130 at the opposite end of shaft 107 to rotate. This gear meshes with the sun gear 124 of planetary gear assembly 120 causing gear 124 to rotate about its shaft 127. At this time shaft 103 is prevented from rotating to prevent shuttle cam 114 from rotating. This locked or braking condition is mechanically coupled through shaft 103 and gears 113, 115, 117 and 119. With the rotation of gear 130, sun gear 124 rotates about its shaft 127 causing the shaft 122 upon which planet gears 121 and 123 are mounted, to revolve about shaft 127. With gear 119 in a locked condition, gear 121 "walks around" gear 119 causing it to rotate. This rotation is imparted through shaft 122 to gear 123 which meshes with gear 125 to rotate this gear. This rotation is imparted to pin feed units 154 and 155 through the following gear members:

Gear 132 to gears 133, 135, 140, 141, 142, 144, 145, 147, 148 and 150 which couples its rotation through timing belt 152 to the timing gear 151 mounted upon elongated shaft 153. It should be noted that the power transmission route described hereinabove passes through the second planetary gear assembly 136. At this time clutch actuating solenoid 112 is deenergized to retain shaft 109 in a free wheeling relationship with gear 108. Thus the shaft 109 does not rotate causing its gear 156, which meshes with sun gear 137 to prevent gear 137 from rotating. At this time the power transmission route extends through the planet gears 140 and 141 which become driven and drive gears within the above mentioned power transmission route.

After the completion of one full revolution, clutch mechanism C.sub.2 automatically deactivates itself in the same manner as was described hereinabove in connection with clutch mechanism C.sub.1 shown in detail in FIGS. 2b-2d. This completes one revolution of operation with the gear ratios being provided such as to move the paper document at a rate which is significantly faster than the constant speed movement of the paper document when in the printing mode (Mode No. 1). In the preferred embodiment the paper document is moved at a speed of 0.46 inches per second when in Mode 2 (a five dot skip).

Upon completion of the five dot skip, the printer is now ready to print the next line of characters in which case actuating solenoid 110 will be energized to operate the shuttle cam through one revolution and to advance the paper document at the printing speed which in the preferred embodiment is 0.1 inches per second.

12 DOT SKIP

In the third mode of operation, it may be desired to perform one or more consecutive line feed operations to provide multiple line spacings between adjacent lines of characters. Another obvious function of the line feed skip is in the case where it is desired to print pages of documents wherein certain of the pages may have a very small number of lines of characters. For example, let it be assumed that the paper document of indeterminate length is provided with perforations at spaced intervals, which perforations are aligned parallel to the longitudinal axis of the platen. These perforations permit the paper document of indeterminate length to be separated into individual pages. Let it be assumed that each page is capable of having 30 lines of characters thereon and that it is desired to print only five lines of characters on a particular page. It is thus desirable to provide a high speed line feed operation to skip the remainder of the just completed page and to move to the top of the next page as defined by the next perforation line provided on the paper document.

This operation is accomplished through the use of clutch mechanism C.sub.3 and its actuating solenoid 112 which, when energized, causes gear 108 to be locked to shaft 109 so as to rotate gear 156 provided at the opposite end of shaft 109. At this time, it should again be remembered that clutch mechanisms C.sub.1 and C.sub.2 are in the unactuated state so that their gears 104 and 106 are in a free wheeling relationship with their associated shafts 103 and 107.

Gear 156 meshes with the sun gear 137 of planetary gear assembly 136 causing the planet gears 140 and 141 to "walk around" their associated gears 135 and 142. Since gear 135 (which meshes with planet gear 140) is restrained from rotating, gear 140 rotates as it "walks around" the gear imparting its rotation to gear 141 which, in turn, is coupled to the pin feed elongated shaft 153 by a power transmission route which includes gears 141, 142, 144, 145, 147, 148, 150 and timing belt 152 which is coupled between gears 150 and 151.

The clutch assembly C.sub.3 is, in the preferred embodiment, a one-half revolution clutch which is provided with two lever arms as is shown in FIGS. 2b--2d to provide a line skip operation of twelve dot rows for each half revolution and to reset upon the completion of each half revolution.

At least one permanent magnet member 145a is secured to a selected member in the gear train. For example, the permanent magnet may be affixed to gear 145 or its shaft 146. A reed switch 157 which may be of the normally open type is adapted to have its contacts closed when the permanent magnet member 145a moves past the stationary mounted reed switch 157. This reed switch functions to provide a contact closure which causes the development of a short pulse for each revolution of gear 145 for the purpose of counting the number of lines which the paper document is advanced. If desired, additional permanent magnets and reed switches may be employed in cases where the gear ratios are altered.

The power on PRIME (see FIG. 6h) sets a bistable flip-flop 310 (FIG. 6m) to enable clutch C.sub.1 to be actuated through energization of solenoid 110. After Gear 145 (or shaft 146) completes a full revolution, reed switch 157 is actuated to reset flip-flop 310 turning off the C.sub.1 clutch. This arrangement assures mechanical registration to zero for each operation of the assembly of FIG. 2. If desired, the closure of reed switch 157 may further be applied to a counter (not shown) having a visually readable display to provide an indication of the number of lines which the paper document has been advanced.

Additional reed swithes 158 and 159 are provided at opposite ends of platform 11 and function as limit switches. Permanent magnet members 158a and 159a are imbedded in or otherwise secured to platform 11. Reed switches 158 and 159 function as limit switches to signal the electronic system that the movable printer assembly has reached its respective left and right-hand-most positions. The electrical interface between the reed switches 157-159 and the printer electronics will be described hereinbelow.

PRINTER ELECTRONICS

FIG. 3 shows a block diagram of one preferred electronic scheme 200 for operating the printer of FIG. 2. The apparatus 200 of FIG. 3 is comprised of data entry means 201 which, for example, may be an external source such as a computer adapted to provide the data in the form of input information for operating the printer. The output lines of the data entry block 201 are shown as being coupled into the input of a two phase clock 204 and a divide by 10 counter 205, and to the input of register 214.

The zero backfill circuit 202 provides a capability of "backfilling" a register with "blank" characters in the case where the line of print in issue contains less than 80 printed characters.

The print cycle circuit 203 comprises a settable and resettable flip-flop, for example, to indicate the initiation of a print cycle and thereby indicate that a search for the next group of dots to be printed should be performed during such a print cycle. The solenoids such as, for example, the solenoids 13 of FIG. 1, are operated by a pulse having a time duration of the order of 450 microseconds. The relax time between adjacent solenoid drive pulses is of the order of 550 microseconds and it is during this time interval in which the search for the next group of dots is performed in readiness for the next dot printing operation, as well become obvious upon a description of the circuitry of FIGS. 3 and 6.

Clock pulse source 204 which has its input connected to the outputs of each of the electronic circuits identified by block 201-203 is a clock pulse source which has a capability of generating two lagging clock pulses so as to operate the data register 214. One such suitable two phase clock source may, for example, be a clock pulse source and a one-shot multivibrator triggered by the clock pulse source for developing a first output from the clock pulse source and a second output (lagging the first output) from the one-shot multivibrator. However, any other type of clock pulse source and register may be used, if desired.

The outputs of each of the circuits 201, 202 and 203 are simultaneously coupled to the input of a divide by 10 counter which develops a pulse at its output 205b for each 10 pulses applied to its input 205a. The output of counter 205 is simultaneously applied to the input of a divide by 8 counter 206 and a timing pulse decoder 207. Divide by 8 counter 206 develops a pulse at its output 206b for each group of 8 pulses applied to its input 206a. The outputs of all stages of the divide by 8 counter 206 are also simultaneously applied to one input of timing pulse decoder circuit 207. Timing pulse decoder 207 is comprised of a counter plus logical decoding circuitry for developing an output signal at only one of its 8 outputs at any given instant. Each of its output lines are coupled to associated input lines of an 8 bit buffer register 213 which operates in a manner to be more fully described.

Divide by 10 counter 205 and divide by 8 counter 206 collectively form a counter capable of developing a count of 80, i.e., of generating an output pulse at 206b for every 80 pulses applied at input 205a. The function of this counting operation will be described in detail hereinbelow.

Output line 206b of divide by 8 counter 206 is coupled to the input line 208a of divide by 6 counter 208. Output 208b of counter 208 is coupled to the input 210a of a divide by 10 counter 210 whose output 210b is coupled to the input 211a of a second divide by 10 counter 211 whose output 211b is coupled to the input 212a of multiplexer 212.

Divide by 6 counter 208 is further provided with a plurality of outputs 208c from each of its stages, each of which are coupled to associated inputs of a column decoder 209 having five output lines 209a which are coupled to associated input lines of character generator 215 which has been described hereinabove.

Data register 214 is substantially the same as that described hereinabove and has a capability of storing 80 characters, each character being comprised of six coded bits. The outputs of data register 214 (6 bits) are coupled to 6 associated inputs 215a of character generator 215 and are simultaneously coupled through feedback loop 214b back to associated input lines 214c of data register 214. The shift pulse input 214d of data register 214 is coupled to the output 204b of clock 204 while the data input lines 214a are coupled to the data entry device 201 or any other suitable external source which provides the input data for the printing operation. In desired the input lines 214a may be first coupled to a serial-to-parallel converter such as the converter 13 shown in FIG. 3 of application Ser. No. 204,024 which, in turn, has its input coupled to a computer source or any other facility which outputs the data which is to be printed in serial fashion.

The operation of the electronic circuitry 200 of FIG. 3 is as follows:

Let it first be assumed that data register 15 has been filled with 80 characters, i.e., that each and every character position in a line of characters is to receive a character or other symbol. Once this has occurred, the first character (of 6 data bits) loaded into register 214 will have been shifted 80 positions until it reaches the right-hand most stage of register 214. Thereupon, data entry device 201 will provide a shift pulse which is applied to the input of divide by 10 counter 205 and to clock source 204. The output of counters 205, 206, 208, 210, and 211 will all be binary zero at this time. The 6 data bits in the right-hand most stage of register 214 will be simultaneously applied to the input of character generator 215. At this time column decoder 209 will provide an output pulse at the left-hand-most output line causing the character generator to provide a 7 bit output which represents the seven dot positions in the first column of the first character to be printed in the line of characters (see FIG. 5). These seven bits are simultaneously applied to associated inputs 212b of multiplexer 212. Row couner 211 is provided with 4 output lines 211b which are coupled to associated input lines 212a of multiplexer 212 with the binary code of these lines representing the particular row being printed at any given time. As is noted in FIG. 5, the printing of seven rows constitutes the printing of one line of characters or other symbols. Initially, the row counter 211 is set at zero which is interpreted by multiplexer 212 as an indication that the dot in row one for the first character should be selected. Multiplexer 212 operates as a decoder in which only one of the 7 input lines 212b is coupled to its output line 212c at any given instant. The condition or state of the bit in column 1, row 1 of the first character is coupled to the input of eight-bit buffer register 213 which is comprised of eight bistable flip-flops, each of which is capable of storing one binary bit regardless of its binary state. The correlation can be seen between the eight storage flip-flops and the eight solenoids (13) provided in the printer. The output of timing pulse decoder 207 is comprised of eight output lines only one of which is enabled at any given time. The operation is such that the first or left-hand-most output line is enabled during startup of the printer to indicate that a dot position (i.e., row and column) of the first character will be stored in the bistable flip-flop associated with this position.

Pulses continue to be applied to input 214d of data register 214 until a count of ten is reached, at which time count-by-ten counter 205 provides an output to divide by eight counter 206 and timing pulse decoder 207. This indicates that the 11th character of a line of 80 characters is now in the right-hand-most stage of register 214. The first through tenth characters which have been shifted out of the right-hand-most stage of register 214 are recirculated through feedback line 214b to be reinserted into register 214.

The 11th character comprised of a six-bit code is applied to associated inputs 215a of character generator 215. Simultaneously therewith, column decoder 209 remains at zero since data for the first column of dots of the first, 11th, 21st, 31st, 41st, 51st, 61st and 71st characters has yet to be loaded into register 213 and subsequently printed. The output code generated by column decoder 209 therefore represents the fact that the first column (i.e., column 1-- see FIG. 5) of the 11th character is to appear at the output leads 215c of character generator 215. These seven outputs which represent the state of the bits in column 1 of the 11th character are simultaneously applied to the inputs 212b of multiplexer 212. Row counter 211 at this time remains at a zero count indicating that the dot in dot row 1, column 1, is to be selected. Since timing pulse decoder 207 has received one output pulse from divide by ten counter 205, the output signals of decoder 207 appearing at 207a enable only the second flip-flop register to receive one bit which represents the column 1, dot row 1, dot condition of the 11th character.

This operation is continued until the dot condition of row 1, column 1, of the 1st, 11th, 21st, 31st, 41st, 51st, 61st and 71st characters are loaded into register 213. The outputs of each of the eight flip-flop stages are coupled to solenoid drive circuits which, in turn, are coupled to associated outputs of the solenoids (for example, the solenoids 13 of FIG. 1). The print carriage is moving at this time and moves into the first position in which the photocell and light source is in registration with the first slit or transparent opening provided in the registration strip. At this time the optical pickup assembly 374 develops a pulse due to this registration condition to activate a strobe circuit 235 which develops a sharp output pulse sufficient to enable the outputs of buffer register 113 to energize the solenoid drivers. It should be noted that the eight dot position conditions of the aforementioned characters (first-71st) are all loaded within less than 500 microseconds. Since the carriage requires of the order of 550 microseconds to move each registration position to the next, it can be seen that the operation of loading the eight bits occurs well before the time in which these eight bits exert control over the solenoid drivers.

After having shifted all 80 characters out of register 214, the characters are now back in their original position with the first character being in the right-hand-most stage and the last character to be loaded in the register being in the left-hand-most stage. At this time the operation recycles itself except that column decoder 209 has now received an output signal from divide by six counter 208 due to the fact that divide by eight counter 206 has developed a pulse at its output 206b to indicate that 80 shift operations have occurred. At this time, column decoder 209 accepts the pulse to cause its next line to be activated, thereby causing character generator 215 to provide a seven-bit output representative of the dot conditions of the second column of the first character. Counters 210 and 211 have yet to be triggered, causing the output of row counter 211 to continue to condition multiplexer 212 so as to accept the binary state representing the dot condition in dot row 1, column 2, (see FIG. 5) of the first character. This binary bit is singled out to appear at output 212c. Timing pulse decoder 207 develops an output at only it left-hand-most line to loadt the bits appearing at the output of multiplexer 212 in the left-hand-most stage of buffer register 213. This operation continues until the binary bits representing the dot condition of dot row 1, column 2 dot position of the 1st, 11th, 21st, 31st, 41st, 51st, . . . 71st characters are now loaded into register 213. Again it should be noted that this operation occurs in less than 500 microseconds so that these bits are in actuality "waiting" for the carriage assembly to move to the next registration position.

The above operation continues until all dots in row 1 for the 1st, 21st, . . . 71st characters have been printed. It should be noted that the print cycle pulse for shift operation is developed by the print cycle circuit 203 when a print operation is occurring to indicate that the character should be examined. This occurs after the completion of the printing of the dots of the first row of each of the 1st, 11th, . . . 71st characters has been completed. This shift causes the first character (i.e., the character in the right-hand-most stage of register 214) to be shifted out of the right-hand end of the register and into the left-hand end, thereby placing the second character in the right-hand-most stage of register 214. At this time, the operation set forth hereinabove is repeated until the first row of dots of the second, 12th, 22nd, . . . 72nd characters is printed.

Divide by 6 counter 208 counts the number of columns which have been printed. The capability of counting six columns is provided in order to provide a space between the end of a character and the beginning of the next character.

Since each solenoid in the preferred embodiment of the present invention has been designed to print ten characters (there being a capability of 80 characters per line with eight solenoids) divide by 10 counter 210 provides an indication that all of the first dot row positions for all 80 characters have now been printed. At this time, an output pulse is developed to advance row counter 211 so that it may condition multiplexer 212 to select the data bit representing the dot position in the second dot row of the 80 characters of the first line. Since divide by 6 counter 208 will have been reset after the entire first row of the line of 80 characters has been printed, column decoder 209 again causes character generator 215 to be conditioned to provide output information at its output lines 215c which represents the dots to be printed in the first column of any character which is presented at its input lines 215a.

The cycle is then repeated for the second through seventh rows of the first line of characters, at which time an output from row counter 211 may be employed to indicate that the line of characters is completed after the seventh row has been printed and the sixth column of the 10th, 20th, 30th, . . . 80th characters has been reached (which output may be taken from divide by six counter 208) to perform a stepping operation to provide adequate spacing between the line of characters just printed and the next line of characters about to be printed. It can be seen that the above arrangement provides the capability of electronically controlling the solenoids through the provision of only a single character generator.

FIGS. 6a-6n are schematic diagrams showing the major "black boxes" of FIG. 3 in greater detail.

FIG. 6a shows the register 214 of FIG. 3 in greater detail in which six registers 220a-220f are provided so as to be capable of storing 80 six-bit data words to provide a total of 64 character combinations preferably in octal code form. It should be understood however that the register length (i.e,, number of stages and number of registers) may be modified to be either greater or lesser in number than specified hereinabove to accommodate either more complex or simpler applications. Each data word is fed in in parallel at the inputs 214a - 214g, respectively. Whereas the register 214 of FIG. 6a employs phase one and phase two clock pulses for inputting and shifting data, it should be understood that any other type of clock pulses or number of pulses may be employed. Since each of the register stages are substantially identical to one another, some of the stages have been omitted for purposes of simplicity, it being understood that their design and operation is the same. Considering register 220a, feedback line 214b for one bit is fed back to the input of register 220a by means of NAND gates 221 and 222 when the appropriate signals are present. The output of the right-hand-most stage of the register is taken at the output of NAND gate 221 at terminal 221-1. Data from data entry source 201 is inputted through NAND gates 223 and 222. Line 224 is coupled in common to one input of all NAND gates 223-223e which is high when signal RTP is present, indicating that the printer is in a loading phase (i.e., is not ready to print).

Line 225 is coupled in common to one input of each of the gates 221-221e when the shuttle cam is in operation so as to be capable of shifting the data words in the manner previously described for appropriate loading of the buffer register 213 (see FIG. 3) through the character generator 215 and the multiplexer 212.

The phase one and phase two pulses for shifting in of data information are applied to respective inputs 220a-1 and 220-2 of register 220a, which are coupled in common to the .phi.2A and .phi.1A input terminals, respectively.

The outputs of the right-hand-most stages of registers 220a-220f appear at output terminals 221-1 through 221-6 and are applied to the respective inputs 215a-1 through 215a-6 of the character generator 215 shown in detail in FIG. 6b. These inputs pass through inverters 231a - 231f to apply the inputs to character generator 215 at input terminals 232a-232f, respectively. The other inputs to character generator 215, namely inputs 215b-1 through 215b-5 constititute those inputs which represent that dot column of the character stored within character generator 215 which has been called for by the data word applied to the input of the character generator. Only one of the inputs 215b-1 through 215b-5 will be high at any given time so as to provide the appropriate signal for the dot column to be generated at the output terminals 212c-1 through 212c-7 of the character generator. These outputs are respectively coupled to the inputs 212b-1 through 212b-7 of the multiplexer. The remaining set of inputs, namely inputs 212a-1 through 212a-3 are derived from the outputs of row counter 211 (see FIG. 3) to select that one of the seven dot column positions applied to multiplexer 212 at inputs 212b-1 through 212b-7. Any one or more of the inputs 212a-1 through 212a-3 may be high to generate any one of seven possible combinations which represent the seven possible positions in the dot column applied to multiplexer 212.

The register 213 is shown in FIG. 6c and has an input 213a coupled to the output of multiplexer 212, shown in FIG. 6b. Buffer register 213 is provided with eight stages having outputs 213b-1 through 213b-8. Each of these eight outputs are applied to one input of an NAND gate 233a through 233h (some of which have been omitted for purposes of simplicity). The remaining inputs of the NAND gates 233 are coupled in common to lead 234 which, in turn, is coupled to output 235c of a one-shot multivibrator 235 which generates a pulse at 235c having a pulse width which controls the length of time in which the solenoids are fired. When the pulse is generated gates 233a-233h are enabled and those which are called upon to generate dots have their outputs amplified by amplifiers 236a through 236h whose outputs are, in turn, coupled to the inputs of associated solenoids 213 as shown in FIG. 1, for example.

Shifting of characters into buffer register 213 is accomplished through a NAND gate 237 having eight inputs. Inputs 237-1, 237-3, 237-5, 237-7 are coupled through inverters 238-1 through 238-4, respectively, to respective outputs SC8, SC4, SC2, SC1 of divide by ten counter 205, to be described in greater detailed hereinbelow. Input 237-2 and input 237-4 are coupled to the oscillator in a manner to be more fully described. Input 237-6 is coupled to the recirculate control circuit to be more fully described. A clock pulse is developed after each count of ten and before each recirculate operation to shift each bit fed into buffer register 213 to the left while feeding the next bit applied to input 213a into the right-hand-most stage. Buffer register 213 is cleared at its clear input 213c upon the presence of a clear buffer signal CLRB which is developed by the recirculate control circuit to be more fully described.

The frequency source employed as clock 204 is shown in FIG. 6d and is comprised of a free running multivibrator 239 whose output 239a is coupled to inverter 240 to one input 241a of a bistable flip-flop 241 operating as a frequency divider. Output 241b of the frequency divider is coupled to NAND gate 242 and to output 241c to simultaneously provide positive and negative levels of the oscillator pulses for a purpose to be more fully described. The double frequency output 241a is employed in a manner to be more fully described.

FIG. 6e shows the cascaded counters 205, 206, 208, 210 and 211. Divide by ten counter 205 is provided with four outputs SC8-SC1 and is advanced by enablement of NAND gate 243. The inputs of NAND gate 243 are coupled respectively to the outputs of NAND gates 244-246. Gate 245 is enabled when the output of gate 230, shown in FIG. 6a indicates that data six and data seven pulses are presented in synchronism with the termination of a data strobe (DSTB) from data source 201 which functions as the clocking source for shifting data words into register 214 and advancing counter 205, thus enabling NAND gate 245 which, in turn, enables NAND gate 243. Gate 244 is enabled when output S40B of the recirculate control circuit of FIG. 6f (to be more fully described) is high which occurs when a carriage return code has been received. This permits loading of "space" characters into register 214 in cases where the number of characters in a line is less than the capacity of register 214. Gate 244 will be repeatedly driven on and off by oscillator pulses applied to its remaining input. Gate 246 is enabled when the printer is in a recirculate mode which occurs after the loading operation is completed. With the enablement of these gates the oscillator pulses are passed through gate 243 to cause counter 205 to accumulate a count of 10. As soon as the count of 10 is achieved, output SC8 pulses divide by 8 counter 206, each time divide by 10 counter 205 accumulates 10 pulses. The outputs SC10, SC20 and SC40 of counter 206 and outputs SC1 and SC8 are coupled to respective inputs of NAND gates 249 and 250 for the purpose of generating an output pulse SC79 at the output of AND gate 250 upon the accumulation of 79 pulses or counts. Output SC40 upon the accumulation of 79 pulses or counts. Output SC40 of divide by eight counter 206 is coupled to the input of divide by six counter 208 which keeps count of the number of columns in each dot row which have been completed. The outputs 208c-1 through 208c-3 of the divide by six counter 208 are coupled into column decoder 209 which is a BCD to decimal decoder capable of generating a pulse at one of its six outputs 209a-1 through 209a-6 which provide the column control signals applied to the inputs 215b-1 through 215b-5 of character generator 215 shown in FIG. 6b. Each time a count of six is accumulated in counter 208 an output pulse is applied to the input of divide by 10 counter 210 which serves to count the number of characters whose dot position in each dot row have been printed. As soon as the count of 10 has been developed indicating that the dot positions for the 10 characters printed by each solenoid have been completed, an output pulse is applied to the row counter 211 which is a divide by 10 counter of which only three outputs are required since only seven dot rows are printed per line of characters. Thus row counter 211 keeps a record of the number of dot rows which have been printed. The outputs RC1, RC2 and RC4 are coupled to the inputs 212a-1 through 212a-3 of multiplexer 212 shown in FIG. 6b.

After the counter has detected a count of 79, as developed by the timing pulse decoder 207 comprised of gates 249 and 250 and inverter 251, this pulse is employed in the recirculate control logic of FIG. 6f to deveolop the appropriate pulse for clearing the buffer register 213 in a manner to be more fully described.

FIG. 6g shows the circuitry employed for developing the phase one and phase two shift pulses for register 214. As a pulse count is applied by NAND gate 243 to count by 10 counter 205, this pulse is applied to one input of AND gate 252 shown in FIG. 6g (AND gate 243 being shown in FIG. 6e). The other input of AND gate 252 is derived from NAND gate 235 whose inputs are derived from divide by 10 counter 210, divide by six counter 208 and divide by eight counter 206 when counts of nine, six and 70 have respectively been developed by counters 210, 208 and 206. This means that the data words in register 214 have been shifted 70 times, since divide be eight counter 206 is pulsed one time for every count of 10 developed by divide by 10 counter 205. Thus, at a count of seventy developed by counter 206, a count of nine developed by divide by 10 counter 210 and a count of six developed by divide by six counter 208 (indicating that seven shift operations of 10 stages per shift have occurred) enables gate 253. For example, let it be assumed that the first dot row for the first column position of the first, 11th, 21st, . . . 71st characters have been loaded into buffer register 213. Before a new recycling operation can begin, the register must undergo 10 more shifts to replace the first character back in the right-hand-most stage. With gate 253 thus enabled, gate 52 is enabled to pass shift pulses through this gate to NOR gate 254 which also receives a .phi.2 pulse from inverter 264 of FIG. 6e, to be more fully described, to apply oscillator pulses which are passed through NOR gate 254 and inverter 255 to trigger one-shot multivibrator 256 at its input 256a. The output 256b applies square pulses to a second one-shot multivibrator 258 and a NAND gate 257. The output 258a of one-shot multivibrator 258 is applied to a second NAND gate 259. It should be noted that the outputs of one-shot multivibrators 256 and 258 are applied to both input terminals of gates 257 and 259 which function primarily as inverters. The pulses developed by gates 257 and 259 will be delayed relative to one another (the leading pulse of gate 259 lagging the leading pulse of gate 257) due to the one-shot 258 coupled between one-shot 256 and gate 259. These outputs are applied to the base electrodes of transistors T.sub.1 and T.sub.2, respectively which function as amplifiers to respectively develop .phi.2A and a pulses which are applied to similarly marked input terminals shown in FIG. 6a to couple lagging phase shift pulses to register 214 during the recirculation operation as well as shifting the data words one position to the right in the manner set forth below.

After the first dot row to the first, 11th, 21 st, . . . 71st characters have been printed, divide by eight counter 208 will develop an output at 208c-3 which is applied to flip-flop 260, see FIG. 6e, to develop an output pulse at 260a to develop a single shift operation for register 214 to shift the first character in the right-hand-most stage to the left-hand-most stage through the recirculation or feedback path and to place the second character in the right-hand-most stage so that the first dot row for the second, 12th, 22nd, . . . 72nd characters may be loaded into buffer register 213. This output is coupled to one input of NAND gate 263 which is enabled to cause the remaining input coupled to oscillator 204 to pass a .phi.2 pulse through NOR gate 254, FIG. 6g, after the 80th shift step has occurred. The lagging phase shift pulses are generated in the same manner as was previously described in connection with the normal shifting operation.

The output of NAND gate 263 (FIG. 6e) is also coupled to one input of a one-shot multivibrator 262 which develops an output at 262a coupled to one input of NOR gate 261 which resets bistable multivibrator 260 and prevents any further "extra" shift pulses from being developed. The same operation may occur by the application of a PRIME pulse at the remaining input of NOR gate 261. The manner in which the PRIME pulse is developed will be described hereinbelow.

FIG. 6h shows the circuitry utilized for developing a PRIME pulse. The purpose of the PRIME is to clear the printer electronics when power is first turned ON. Upon the development of a DC signal, the input of resistor R.sub.1 shown in FIG. 6h and capacitor C1 develops a charge across its plates causing the input to inverter I to go positive. This causes the negative going impulse to be applied to NAND gate 265 causing its output to go High. This is inverted by inverter 266 to develop a negative going pulse which is applied to the remaining terminal of AND gate 265 to cause the output of NAND gate 265 to go High. This is prevented initially by capacitor C.sub.2 so that a low output is developed at the input to inverter 266 causing its output terminal to go high to develop the PRIME pulse. As soon as a sufficient charge is developed across capacitor C.sub.2 the output of NAND gate 265 goes high causing the output of inverter 266 to go low, which state is retained so long as the printer remains on. The PRIME pulse developed by inverter 266 is applied to NAND gate 267 which functions as an inverter to develop the PRIME pulse which functions in a manner to be more fully described.

The output of divide by ten counter 210 is applied to one input of a bistable flip-flop 268 (see FIG. 6e). After a count of 10 has been accumulated by counter 210, this pulse is applied to the input 268a of bistable 268 causing its outputs terminals/ 268b and 268c to go high and low, respectively. The high pulse of 268b calls for a shuttle return operation which occurs after a dot row of the entire 80 characters in the register has been printed. Reset of the bistable 268 is accomplished when NOR gate 269 is enabled either by a PRIME signal or by the development of a signal by the left-hand limit switch (reed switch) 158 shown in FIG. 2.

FIG. 6i shows the circuitry employed for "remembering" the state of operation of the printer head shuttle. The output of divide by 10 counter 210 (DC8) is coupled simultaneously to the inputs 500a and 501a of bistable flip-flops 500 and 501, respectively. The bistable flip-flop 500 has coupled to its input terminal 500b the output of NAND gate 270 whose inputs are coupled to the outputs of divide by 10 counter 211. When these inputs are all high, this indicates that the seventh row of dots has been printed which calls for a "12 dot skip" described hereinabove. The output of AND gate 270 goes high and together with an output pulse developed by divide by 10 counter 210, causes outputs 500c and 500d of bistable 500 to go low and high, respectively, which pulses are applied as will be described hereinbelow to prevent operation of the shuttle (i.e., to prevent rotation of the shuttle cam until a 12 dot skip has been performed) and to actuate a 12 dot skip.

The output of AND gate 270 is simultaneously coupled to input 501b of bistable 501 causing its outputs 501c and 501d to go low and high respectively, indicating that the printer is not ready to print. Reset of the bistables 268 and 501 may be accomplished either by application of a PRIME pulse at inputs 500e and 501e respectively. The reset of bistable 500 is further provided for by a preset shuttle signal PRSH applied to input 500f which occurs when a signal is developed at the output of gate 282 in FIG. 6f to be more fully described hereinbelow. A reset pulse may be applied at input terminal 501f of bistable 501 when the inputs to NAND gate 271 are both high. The inputs supplied thereto, namely CRFF (carriage not returning) and 80CF which occurs when a count of 80 has been reached to reset the bistable 501 to cause its outputs 501C and 501d to go high and low, respectively, in readiness for printing the next dot row.

FIG. 6f shows the backfill and recirculate control circuitry and is comprised of a NAND gate 272 whose inputs are coupled to the outputs designated at each lead line 272-1 through 272-8 representing an input. Inputs 272-1 to 272-6 are coupled to respective outputs of gates 223 of register 214 shown in FIG. 6a. When these outputs are all high, this indicates that a carriage return operation has been called for. This is typically the first operation called for from the computer or other data source prior to loading data into the register. The input DSTB is a data strobe pulse developed by the data source during the time that it outputs each data word which it is presenting to the printer. The output of gate 272 is coupled to the input 273d of a bistable flip-flop 273 to cause output 273e to go low when the low level developed by NAND gate 272 is applied at 273d. Bistable 273 remains in this state until a count of 79 is developed by timing pulse decoder 207 described in connection with FIG. 6f. The low level at 273e is applied to one input of NOR gate 274 whose opposite input receives the data strobe pulse from the data word source. Output 273e (signal CRFF) is utilized to indicate that a carriage return is not being performed at this time. This signal is applied to gate 271 (FIG. 6i) to develop a ready to print (RTP) signal when CRFF goes high upon application of SC79.

The output of NOR gate 274 is applied to input 275a of bistable 275 which goes high only when both of its inputs are low. When the data strobe pulse is removed the high input is coupled to 275a which, upon the completion of the next oscillator pulse to input 275b causes output terminal 275c to go high which indicates that data is being received. When the 79th character has been shifted into register 214, signal SC79 (from gate 250-FIG. 6e) is developed and after completion of the next oscillator pusle, output 275c is caused to go low indicating that no more characters are to be loaded into register 214.

NAND gate 276 causes bistable 277 to have its output 277e go low when the output from inverter 279 (DSTBEN) of FIG. 6e is high and when the 79 th character shift operation (SC79) has occured. Bistable 277 may also be driven to the low state at 277e when the output 275c of bistable 275 goes low upon the occurrence of the 79th shift operation. Gate 276a causes output 277e to go high when PRIME and 281e is high.

The output 277e is coupled to one input of OR gate 280 whose other input is coupled to the data strobe source for setting the output 281c of bistable 281 high when outputs 277e and the data strobe are low. This develops an oscillator sync (OSC SYNC) output at 281c which is utilized for the purpose of synchronizing the printer with the data source 201 (see FIG. 3).

The printer is capable of printing either a full line of 80 characters or a line of less than 80 characters. For lines which are to be comprised of less than 80 characters, the last character of the line in issue is followed by an "octal 40" code which represents line return. This code appears at the outputs of gates 223 of FIG. 6a which gate outputs are coupled to respective inputs of gate 272 (FIG. 6f). When a carriage return code and DSTB is received from the data source and decoded, gate 272 asynchronously sets flip-flop 273 (i.e. regardless of the state of OSC). Upon the occurrence of the next data strobe (DSTB) from data source 201, gate 274 is caused to synchronously set flip-flop 275 upon the occurrence of the next oscillator pulse (OSC). Output 275c continues to feed "octal 40" signals to register 214 (see FIG. 3) until the register is filled with 80 characters. "SC79" is a pulse generated when counters 205 and 206 collectively reach a count of 79. At the 80th count, pulse "SC79" terminates causing flip-flops 273 and 275 to be reset synchronously with the occurrence of the next oscillator pulse (OSC). The "octal 110" code is interpreted by character generator 215 (FIG. 3) as a "space" code preventing anything from being printed in those positions of a character line in which the space code is received. The S40b output (275c) enables gate 244 (FIG. 6e) to advance counter 205 with each oscillator pulse (OSC).

In those cases where register 214 is to be filled with characters, the termination of "SC79" and the occurrence of DSTBEN at gate 276 asynchronously sets flip-flop 277 (regardless of the state of OSC). The output 277c and the next data strobe (DSTB) causes gate 280 to set flip-flop 281 synchronously with the next oscillator pulse (OSC) enabling gate 282 to generate a preset shuttle pulse PRSH through the output of 281c and OSC. The register 214 is now in synchronism with the system clock 204 of FIG. 6d. The preset shuttle signal PRSH asynchronously sets bistable flip-flop 287 which synchronously sets bistable flip-flop 288 with the next oscillator pulse (OSC) to develop RCL (288e) which enables gate 246 (FIG. 6e) to permit counters 205, 206, 208, 210 and 211 to operate during the loading of buffer register 213 and operation of solenoids 13. Output 277e when high provides an indication that the count of 80 has been developed collectively by counters 205 and 206 of FIG. 6e. The output 281c of bistable 281 is applied to one input of NAND gate 282 and functions to develop the shuttle-On (SHTLON) signal at the output of bistable 268 shown in FIG. 6i. The output of NAND gate 282 is also coupled to one input of AND gate 283 whose remaining input is coupled to the output of NAND gate 284. One input of NAND gate 284 goes high when the left-hand limit switch (reed switch 58 of FIG. 2) closes causing the negative going voltage to be applied to inverter 286 which provides the positive going signal to one input of NAND gate 284. The remaining input of NAND gate 284 is derived from the output 500c of bistable 500 shown in FIG. 6i which is high to initiate shuttle cam operation. When either of these inputs goes low the output of NAND gate 284 goes high to enable AND gate 283 which causes bistable 287 to be reset when its input 287b goes low when the first slit in the registration strip 360 (FIG. 1) is detected to set its output 287c high. This high state together with the termination of the next oscillator pulse applied to terminals 288a and 288b respectively of bistable 288 causes the output terminals 288d and 288e, respectively, to go high and low. The high output is utilized to indicate that the printer is now in a recirculation phase, during which the 80 characters in register 214 (see FIG. 6a) are recirculated in stages of ten shifts per stage to load the dot position information of the appropriate character into buffer register 213 (see FIG. 6c).

The output 288d of bistable 288 is coupled to input 289a of a one-shot multivibrator 289 which develops a pulse at output 289b to clear buffer register 213 (see input terminal 213c of FIG. 6c) in readiness for loading the next group of eight dot conditions therein. Gate 290 resets bistable 287 when RCL and PRIME are generated causing output 287c to go low.

FIG. 6j shows the circuitry employed to enable the performance of a line feed. Switches C.sub.2 and C.sub.3, which are respectively activated by clutches C.sub.2 and C.sub.3, are closed when their respective clutches are deactivated. When either of these switches are closed the output of AND gate 292 goes low to develop a clock pulse input at 293a of bistable 293 causing its output 293b to go high indicating that printing of the next line of characters may be initiated. 293b may also be set high by a negative going PRIME signal applied to 293c. 293b is also set low by NAND gate 294 when either of its inputs go low indicating that either the output of NAND gate 283 (TOSPI), shown in FIG. 6f, or the output of NAND gate 301 (TOSP3) of FIG. 6k goes low to indicate that one of the three clutch actuating solenoids is being called upon to operate.

FIG. 6k shows the circuitry employed for enabling line feed operation. NAND gate 295 has its inputs coupled to respective outputs of gates 223 (FIG. 6a) to receive the code "octal 12" which calls for a line feed operation. This causes its output to go low, which condition is applied to input 296a of bistable 296 causing its output 296b to go high and 296c to go low, respectively. As soon as the data strobe (DSTB) is removed these low conditions, which are applied to the inputs of NOR gate 297 cause its output to go high and which signal is applied to input 298a of bistable 298 to cause its outputs 298c and 298d to go high and low, respectively, upon the completion of the next oscillator pulse at input 298b. Output 298c is coupled to input 299a of bistable 299 while output 298d is coupled to the set input 300b of bistable 300. This causes the output 300c of bistable 300 to go high, to initiate a line feed operation. Upon the completion of the next oscillator pulse applied to input 299b of bistable 299, its output 299d goes high. This condition is applied simultaneously to the inputs of NAND gates 301 and 302 and to input 299c of bistable 299. This causes the enablement of gate 301 which provides for the enablement of the one-shot multivibrator in FIG. 6m to be more fully described, to selectively control one of the three clutches C.sub.1 -C.sub.3 in a manner to be more fully described. The enablement of gate 302 causes bistable 296 to be reset through the output of AND gate 303 coupled between the output of gate 302 and input 296c of bistable 296 thus cancelling the line feed request stored in bistable 296. Bistable 300, however, permits a second line feed request to be stored or buffered while the first line feed is being performed.

Gate 304 develops an output when no line feed request is stored in bistable 296 and when the top of line condition (signal TOL) at output 293b of bistable 293 (see FIG. 6j) is present indicating that a line feed has been completed and we are now at the top row of the next line of characters to be printed. This signal is applied to input 281f of bistable 281 shown in a recirculate control circuitry of FIG. 6f to enable the shuttle to be operated. When the output of NAND gate 282 in FIG. 6f goes low, this condition is applied to input 500f in FIG. 6i causing output 500c of bistable 500 to go high and thereby turn the shuttle on.

Considering FIG. 6m when output 500c of bistable 500 in FIG. 6i goes high, the complementary output appears at 500d applying a low condition to NAND gate 306. This causes a high level to be applied to one input of AND gate 307 whose other input goes high when the output of AND gate 283 in FIG. 6f is enabled to cause one input of AND gate 308 to go high. When the remaining input is high (which input is taken from the output of NAND gate 301 in FIG. 6k) one-shot multivibrator 310 has a high level applied to its 310a causing its output 310b to develop a pulse of 35 milliseconds time duration for simultaneously conditioning the operation of AND gates 311, 312 and 313 which are coupled to the clutch actuating solenoids 110, 111 and 112, shown in FIG. 2.

This one-shot pulse appearing at output 310b is also applied to input 300a of bistable 300 shown in FIG. 6k to cause its output terminals 300c and 300d to go low and high respectively to cancel the stored line feed condition upon the occurrence of the trailing edge of the pulse developed by one-shot multivibrator 310. The remaining input of AND gate 311 is coupled to the output 500c of bistable 500 shown in FIG. 6i which is high when the shuttle is to be actuated. This causes a pulse to be applied to clutch actuating solenoid for clutch C.sub.1 to perform a printing operation for one dot row.

AND gate 313 has its remaining input coupled to the output 300c of bistable 300 which is high only in the presence of a line feed to operate clutch C.sub.3 and perform a "12 dot skip" operation, as was previously described.

AND gate 312 has its remaining input coupled to the output of AND gate 314 which is enabled when the output 300d of bistable 300 is high (indicating that the printer is not in a line feed mode) and when the shuttle is not on indicating that the seventh dot row of a line of characters has been printed and the printer is called upon to perform a "5 dot skip" as was previously described, to provide the appropriate spacing between the last line of characters which has been printed and the next line of characters to be printed.

A line feed request applied to bistable 296, shown in FIG. 6k, causes output 296b of bistable 296 to go high. This level is applied to one input of NOR gate 315 shown in FIG. 6n which causes its output to go low. This condition is applied to one input of inverter 326 causing its output to go high to provide a busy signal for the printer data source to indicate that no data may be shifted in the register 214 since a printing operation is being performed. This condition is likewise obtained when a ready to print signal is developed by bistable 296 at its output 269c as shown in FIG. 6i which occurs when either no carriage return octal code has been received or when the dot line of the 80th character has yet to be printed.

The output 315a of NOR gate 315 is simultaneously employed as the not busy output as well as an input to NAND gate 317. The other input of NAND gate 317 is derived from one-shot multivibrator 318 which develops a negative going pulse upon receipt of a data strobe from the data source feeding data to the printer. When either of these conditions go low, a positive pulse is applied to one-shot multivibrator 319 developing a pulse at output 319b which is employed as an acknowledge signal to acknowledge receipt of a line feed operation from the source feeding data to the printer.

GRAPHIC MODE

In the graphic mode of operation of the printer, the character generator and multiplexer circuits are bypassed and 480 bits of data representing one full dot line is fed into the register. The register is modified so as to be comprised of eight register states of 60 bit length with the eight bits in the right-hand-most stage representing the dot conditions of the first, 61st, 121st, 181st, 241st, 301st, 361st, and 421st dot positions of a line of 480 dot length. Thus, the register serves as the buffer and the right-hand-most stage of the eight registers may be coupled directly to the driver circuits for the eight solenoids 13 (FIG. 1 and 2). Thereafter, the register is shifted one bit position with the next eight bits representing the second, 62nd, 122nd, . . . 422nd dot positions along a dot line. The register is continually shifted one position each time until all 60 bits of each of the eight register stages is sequentially coupled to the solenoid driver circuits to plot a graph, draw a picture or perform any other type of non-printing graphic operation.

FIGS. 4a-4c show an alternative movable solenoid mounting assembly which may be employed in place of the assembly described hereinabove in connection with FIG. 1. Where applicable, like elements have been designated by like numerals.

The solenoids 13 are shown as being mounted to first and second heads 12 and 12' with their print wires 13b extending through suitable apertures provided in the heads 12 and 12'. Each of the "split" solenoid assemblies are free to move in a forward direction toward the platen or in a rearward direction away from the platen independently of one another. The manner in which this is accomplished is attained through the use of a pair of platforms 340 and 341 (only one of which is shown in detail in FIG. 4b for purposes of simplicity). The platform 340 is fixedly secured to platform 11 and is provided with a pair of V-shaped grooves 340a and 340b which cooperate with a pair of grooves 12e and 12f, respectively, in head member 12 to receive cylindrical roller bearings 342 to provide for a very-low friction rolling engagement between the V-shaped grooves of head 12 and platform 340 and roller bearings 342. Each of the head portions 12 and 12' is provided with a recess such as, for example, 12g' shown best in FIG. 4c for receiving a projection 343a which extends into recess 12g' and which is integrally joined to a cylindrical member 343 rotatable about its central axis 344 under control of lever 345 in the direction of arrow 346 to move the head 12' rearwardly as shown by arrow 347 so as to move the head assembly 12' away from the platen. Platform 11 is provided with an opening 11d running nearly its entire length to provide clearance for projection 343a. A similar lever assembly is provided for the head 12 so as to be capable of independently moving either of the head assemblies 12 or 12' either toward or away from the platen independently of one another.

The desired spacing between the forward edges of the head assemblies 12 and 12' and the platen or paper document is provided for by the rollers 349 and 350 which are mounted within recesses 12g and 12g' provided in heads 12 and 12', respectively. A rectangular-shaped block 351 (and 352) act(s) to maintain the roller in position. A fastening member 353 is provided to secure block 351 to head 12 and to permit roller 349 to free wheelingly rotate about its longitudinal axis. A similar fastening member is provided for the roller 350. As can best be seen in FIG. 4a, a small portion of each of the rollers 349 and 450 extend beyond the forward edges 12h and 12h' of heads 12 and 12', respectively, so as to maintain a spacing which, in the preferred embodiment, is of the order of 0.004 inches from the paper document. Rollers 349 and 350 rollingly engage the surface of the paper document as the platform 11 is moved between its left-hand-most and right-hand-most positions. This arrangement is extremely advantageous for applications in which passbooks are desired to be inserted between the paper document and one of the solenoid assemblies wherein the passbook may be thicker than the thickness of the paper document making it possible to simultaneously make entries in a passbook and on the paper document making the device extremely useful in banking and other like accounting applications.

The exact placement of the dots of each dot row on the paper document is assured through the use of the registration assembly which is comprised of a stationary registration strip 360 provided with equispaced transparent slits 360a which are arranged at the appropriate dot intervals. The platform 11 has suspended from its underside an assembly 370 comprising an arm 371 secured to the underside of platform 11 which, in turn, has two arms 372 and 373 suspended therefrom. Arm 372 is provided with a suitable light source (not shown) for passing light through the registration strip 260 as the platform moves from left to right during the printing operation. Arm 373 has mounted therein a light sensitive device such as, for example, a photocell which is pulsed each time light passes through a registration slit 360a to generate a pulse at the exact position which a dot is to be printed. FIG. 3 shows the optical pick-up 374 having its output coupled to strobe 235 which is shown in detail in FIG. 6c as a one-shot multivibrator. Input terminal 35b is coupled to the optical pickup 374 to generate a strobe pulse at output 235c which, from FIG. 6c, can be seen to enable all of the gates 233a-233h to couple the states of the dot positions in a dot row stored in buffer register 213 to the solenoid driver circuits to selectively print dots at the next eight positions such as, for example, the first column positions in the first dot row of the first, eleventh, twenty-first . . . seventy-first characters, as was previously described. The positioning of the registration assembly on platform 11 is preferably aligned with one of the print wires 13b so as to assure proper registration, although any other positioning may be employed if desired. As was previously mentioned the strip 360 may be mounted to move the platform and the light source and light sensitive device may be mounted in a stationary fashion.

An alternative printer head assembly 700 is shown in FIGS. 7a-7c. The printer head assembly 700 is comprised of an elongated member 701 having tapped openings 702 provided at spaced intervals along its length for threadedly engaging the threaded portions 13a of each of the solenoids 13. In one preferred embodiment, eight such threaded openings are provided for threadedly engaging the eight solenoids for use in an 80 column printer (i.e., 80 characters per line). The printer solenoids 13 are firmly maintained within member 701 by means of the lock nuts 13d which likewise threadedly engage threaded portion 13a of the solenoids. Solid member 701 is provided with a recess 701a along its upper surface for receiving the horizontally aligned arm 703a of an elongated L-shaped member 703. The vertically aligned arm 703b of member 703 is provided with eight openings 704 each fitted with a jewel bearing member 705 for receiving the free end of an associated print wire 13b.

Arm 703a of elongated member 703 is fitted into elongated recess 701a and is secured thereto by a plurality of threaded fasteners 707 which pass through openings 706 in arm 703 and which threadedly engage tapped openings 701b in member 701. As can best be seen from FIGS. 7b and 7c, threaded fasteners 707 are positioned between each adjacent pair of solenoids.

The elongated member 701 has its bottom surface 701d positioned upon the respective surfaces 710a-710c of trapezoidal-shaped sections 709a-709c of platform member 709. Member 701 is secured to platform 709 by the elongated threaded fasteners 708 shown best in FIGS. 7b and 7c.

The bottom surface 709d of platform 709 is provided with a slender wedge shaped portion 714 which is fitted to the printer movable platform by fasteners 715 so as to mount the solenoids 13 whereby the imaginary straight line 711 along which the print wires 15 lie is arranged to be parallel to the platen and/or the horizontal direction whereas rails 22 and 23 are inclined at the same angle as wedge 714 so that the movable platform upon which platform 709 is mounted is arranged along a slight incline as was previously described in order to coordinate with constant movement of the paper document so as to print a straight horizontally aligned line of characters.

The uniqueness of the printer head assembly of FIGS. 7a-7c resides in the fact that the entire assembly may be turned upside down so as to place the left-hand-most solenoid (relative to FIG. 7b) at the right-hand end and conversely, to place the right-hand-most solenoid (again, relative to FIG. 7b) at the left-hand-most end. This may be carried out simply be removing the three fastening members 708 and turning the entire assembly upside down so that the platform of member 701 having recess 701a rests upon the upper surfaces 710a-710c of trapezoidal shaped sections 709a-709c, respectively. The advantage of this arrangement resides in the fact that the solenoids at the right-hand end of the assembly relative to FIG. 7b experience the greatest amount of use due to the fact that these solenoids are the only operating ones when short lines of characters are printed (for example, a half-line, a third-line or a quarter-line of characters). The design of member 701 is such that the longitudinal axis 713 of openings 702 is equidistant from the top and bottom surfaces 701c and 701d of member 701. Since the center line of print wire 15 is coincident with center line 713, the member 701 can be turned over in the manner described hereinabove without in any way disturbing the alignment of the print wires. This operation can be repeated as often as may be desired so as to assure substantially uniform wearing and use of the solenoids and their associated print wires.

It can be seen from the foregoing description that the present invention provides a printer capable of character printing or curve plotting wherein a long row of dots are printed while the movement of print wire carriage is reduced to an amount of the order of 1/Nth the total length of the line of print where N represents the number of print wires provided for each row of dots.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only the appended claims.

Claims

The embodiments of the invention in which an exclusive privilege or

1. An impact printer for forming dot patterns upon a movable document in a row by row fashion whereby a regular matrix of A dot rows by B dot columns define each character (A and B being real integers greater than 1) comprising:

a carriage assembly movable in a direction transverse to the direction of movement of said paper document;

a plurality of impact means each mounted upon said carriage assembly;

each of said impact means including a reciprocating print wire and means for driving said wire against said document at high speed;

the ends of said wires being arranged at spaced intervals along said carriage assembly and arranged along an imaginary straight line substantially in alignment with the direction of movement of said carriage assembly;

means for selectively energizing said impact means during movement of said carriage assembly in the printing direction, whereby the distance traveled by said carriage assembly in printing one line of dots is 1/Nth the length of a full line of dots where N represents the number of impact means;

continuously operating drive means;

movable platen means for moving said paper document;

first advancing means coupled to said platen means for moving said paper document at a first velocity in a direction transverse to the movement of said carriage assembly;

shuttle means having a full operating cycle for moving said carriage assembly from a start position across said platen to the end of printing position and for returning said carriage assembly to the start position;

means responsive to a printing operation for coupling said shuttle means and said advancing means to said drive means;

a recirculating register for storing binary coded words representative of the characters to be printed;

characters generating means coupled to said register for generating a plurality of groups of dot column signals representing the dot matrix pattern for the coded character applied to the character generator;

first counter means coupled to said register for applying every Nth coded character to said character generating means;

second counter means coupled to said character generator means for causing only one of said groups of column signals to appear at the output of said character generating means;

buffer register means having a storage stage for each driving means for storing one dot signal for every Nth character;

third counter means for transferring only one of the dot column signals of every Nth character generated by said character generating means to said buffer register means;

registration means for simultaneously energizing the impact means associated with each buffer register means storage stage when the driving means are in the printing position;

fourth means for counting the number of dot rows which have been printed in a line of characters;

said coupling means including means for decoupling said advancing means and said shuttle means from said drive means upon completion of a shuttle means operating cycle;

said fourth counting means being connected to said coupling means for activating said coupling means prior to the completion of printing of each

2. The printer of claim 1 further comprising second advancing means coupled to said platen means for moving said paper document at a second velocity greater than said first velocity;

second coupling means responsive to a line spacing request for coupling said second advancing means to said drive means;

means coupled to said fourth counting means for generating a line spacing

3. The printer of claim 2 further comprising third advancing means coupled to said platen means for moving said paper document at a third velocity greater than said second velocity;

third coupling means responsive to a form feed request for coupling said

4. The printer of claim 2 further comprising first mechanical means having first and second inputs and an output for coupling either said first or second advancing means connected respectively to said first and second

5. The printer of claim 4 further comprising second mechanical means having first and second inputs and an output, said first input being coupled to the output of said first mechanical means, said second input being coupled to said third advancing means and said second mechanical means output being coupled to said platen means for coupling any one of said first,

6. The printer of claim 5 wherein said mechanical means is a planetary gear

7. A high speed dot matrix printer of the impact type comprising:

a platen assembly feeding a paper document;

a shuttle assembly comprising a movable platform;

a plurality of impact means mounted at spaced intervals along said platform;

each of said impact means including a slender reciprocally mounted print wire for impacting said paper document when its impact means is actuated and for retracting from said paper document when its impact means is deactuated;

drive means;

first, second and third driven means constantly rotated by said drive means when said drive means is energized for respectively driving said platen assembly at first, second and third velocities;

a shuttle cam for reciprocating said platform from a start position to an end of print position and back to the start position;

first and second coupling means each having first and second inputs and an output;

first clutch means coupling the first driven means to said shuttle cam and said platen means for driving said shuttle cam and said platen means when said first clutch means is actuated;

said shuttle cam being coupled to the first input of said first coupling means;

second clutch means for coupling said second driven means to the second input of said first coupling means when said second clutch means is actuated;

the first input of said second coupling means being coupled to the output of said first coupling means;

third clutch means for coupling said third driven means to the second input of said second coupling means;

the output of said second coupling means being coupled to said platen means for driving said platen means by any one of said first, second or third driven means while said shuttle cam is driven by only said first driver

8. The printer of claim 7 further comprising means coupled between said shuttle cam and the first input of said first coupling means for driving said platen means to move said paper document at a first constant velocity

9. The printer of claim 8 further comprising means coupled between said second clutch means and the second input of said first coupling means for driving said platen means to move said paper document at a second velocity

10. The printer of claim 8 further comprising means coupled between said third clutch means and the second input of said second coupling means for driving said platen means to move said paper document at a third velocity

11. The printer of claim 7 wherein said first and second coupling means are each comprised of a sun gear rotatable about its central axis;

first and second planet gears mounted to a common shaft;

said shaft being mounted within an opening in said sun gear displaced from said central axis;

said first input comprising a gear meshing with said first planet gear;

said second input comprising a second gear meshing with said sun gear;

said output means comprising a third gear meshing with said second planet

12. The printer of claim 7 wherein at least one of said first, second and third clutch means includes means for automatically deactivating its

13. The printer of claim 7 wherein at least one of said first, second and third clutch means includes means for automatically deactivating its

14. The printer of claim 7 wherein at least one of said first, second and third clutch means includes means for automatically deactivating its associated clutch means after revolving a predetermined portion of a

15. The printer of claim 7 wherein said shuttle cam comprises a rotatable cylinder having a cam in the form of a continuous flange extending outwardly from the periphery of said cylinder;

a pair of projections secured to said platform;

said flange being positioned between said projections to reciprocate said platform in a forward and rearward direction for each revolution of said

16. A head assembly for impact printers and the like comprising:

a platen;

a first platform mounted for reciprocating movement in a direction substantially parallel to said platen;

second and third platforms;

means for movably mounting said second and third platforms on said first platform to enable reciprocating movement of said second and third platforms independently of one another and in a direction transverse to the direction of movement of said first platform;

first and second groups of solenoids respectively mounted on said first and second platforms;

means for independently moving said second and third platforms respectively toward and away from said platen;

each of said solenoids including a reciprocating print wire for impacting a paper document moved by said platen;

means on each of said second and third platforms for reciprocally mounting the forward ends of said print wires;

means for driving said first platform across said platen whereby said

17. The assembly of claim 16 wherein each of said second and third platforms includes means for extending from their associated platforms toward said platen to maintain a predetermined spacing between said platen and the print wires of said second and third platforms when either or both

18. The assembly of claim 17 wherein each of said spacing means comprises

19. Control means for an impact printer of the dot matrix type having

means for moving a paper document;

print means movable in a direction transverse to the movement of said paper document;

a plurality of impact means mounted upon said print means for impacting said paper document;

said control means comprising

a data source for generating binary coded data representing characters to be pringed and control functions to be performed by said control means;

recirculating register means for storing a predetermined number of binary data representing characters to be printed;

counter means for counting the number of binary coded characters applied to said register;

said data source including first clock means for shifting binary coded characters into said register and simultaneously advancing the count of said counter means;

decoding means coupled to said counter means for generating a signal when said register is loaded to capacity;

means coupled to said decoding means for activating said document moving means and said print means when said register is filled to capacity;

second clock means;

means coupled to said counter means for coupling said second clock means to said counter means and said register means when said register means is filled to capacity to step said counter means and shift characters through said register means;

character generator means coupled to the output of said register means for generating M groups of column signals each column group having N signals to represent a different M.times.N dot matrix for each coded character applied to said character generator means;

means coupled between said counter means and said character generator means for selecting one of said M columns dependent upon the count in said counter means;

multi-stage buffer register means for storing one-dot position of selected characters in the line of characters to be printed;

multiplexer means coupled to said counter means for transferring one of the N signals in the selected column to an associated stage of said buffer

20. The control means of claim 19 further comprising means for sensing the position of said print means to generate registration signals at discrete intervals along the path of movement of said print means;

means coupled to said sensing means and said counter means for reading out the contents of said buffer register means when said buffer register means is fully loaded and the next registration signal is generated;

the output of said buffer register means being coupled to said input means for selectively operating said impact means in synchronism with said

21. The control means of claim 20 further comprising means for recirculating characters applied to said character generator means from said register means back into the input of said register means;

said multiplexer means enabling said buffer register to load the desired dot signals of every Kth coded character in said register where K = C/I.sub.N and C equals the capacity of said register means and I.sub.N is

22. A print head assembly for use in dot matrix printers of the impact type comprising an elongated movable platform;

means for guiding said movable platform along an inclined path;

an elongated support member having an inclined mounting surface positioned upon said platform;

a solenoid mounting member secured to said support member and having a plurality of spaced apertures, the center lines of said apertures being defined by an imaginary straight line inclined at an angle to said mounting surface;

a plurality of solenoids each having their forward ends mounted in said apertures;

each of said solenoids having a slender reciprocatable print wire extending from the forward end of each solenoid;

a bracket mounted to said mounting member, said bracket having an arm positioned a spaced distance in front of said mounting member;

said arm having openings each receiving the forward ends of an associated one of said print wires;

the upper and lower surfaces of said mounting member being equidistant from said imaginary straight line enabling said mounting member to be positioned with either the upper or lower surfaces engaging said support member to provide for even wearing of said print wires during long

23. The print head assembly of claim 22 wherein said bracket arm is provided with jewel bearings in each of the openings receiving a print wire to provide a low friction bearing for said print wires.