Keyboard Mechanism And Associated Code Converting Circuitry

Abstract

This invention relates generally to code conversion and more particularly to the production of electrical signals from a keyboard, the keys of which are operatively connected to one or more individual current control devices, such as reed switches, whose activation to conducting or nonconducting operating conditions is determined by the presence or absence of an influencing magnetic field. The disclosure illustrates a compact assembly of dry reed switches and associated magnets and magnetic shields or shunts, each shunt normally being interposed between its associated magnet and switch and movable to a withdrawn position by activating a key of the keyboard. Means is provided for electrically strobing the reed switches and for performing this operation only after assurance that all reed switches are stabilized in their prescribed code positions as the result of the actuation of a selected key. Means is also provided for substantially lessening the number of switch closures necessary for converting the keyboard operation to electrical signals in binary code form. As a result of the mounting arrangement of the magnetic transducing elements an efficient utilization of the field shunting operation is obtained and an improved key touch is achieved.

Description

BACKGROUND OF THE INVENTION

This invention is directed to that field of art pertaining to code converting apparatus and particularly to keyboard mechanism in which key actuated entries in one notation, such as decimal, are converted and transduced into electrical signals in another notation, such as binary.

Attempts have been made in the past for operating electrical signaling elements from keyboard mechanisms in order to provide a coded output in the form of electrical signals for entering data into business machines and data processing systems. One such endeavor is represented by the subject matter of the British Pat. No. 935,474 in which movable permanent magnets are operated permutatively from a keyboard for opening and closing reed switches. Another proposed keyboard mechanism is that illustrated in U.S. Pat. No. 3,189,153 wherein code bars and code bails operate in horizontal planes to mechanically move switches for providing the electrical output. A further improvement in such mechanisms is that disclosed in the copending application for U.S. Pat. of common ownership herewith filed in the name of Flavius A. Mathamel, Ser. No. 433,359, filed Feb. 17, 1965, which is abandoned in favor of continuation application Ser. No. 816,643, filed Apr. 16, 1969 now U.S. Pat. No. 3,495,236. Contrary to the aforesaid patents, the above identified copending patent application suggests a transducing assembly in which a movable magnetic shunt is operatively associated with each code bar for movement into and out of the space between two closely spaced stationary elements, one a permanent magnet and the other a magnetic core which is subjected to the magnetic field of the magnet. In its interposed position between these two elements, the shunt lessens or diverts the magnetic field from the core permitting the latter to assume one of its two operating conditions and when the shunt is withdrawn from such space the magnetic field is free to influence the core to its other operating condition. In the transducing apparatus, of this related case, the magnetic core functions as a switching element either transmitting or not transmitting an electrical current signal depending upon the strength of the magnetic field to which it is subjected.

SUMMARY OF THE INVENTION

An important object of the invention is to provide an improved keyboard mechanism particularly designed to provide an efficient and reliable usage of the operating elements for converting the displacement of keys on a keyboard to electrical signals coded for entry into data processing equipment.

Another important object of the invention is to provide an improved transducing assembly for converting the actuation of each key of a keyboard into an electrical signal which utilizes a magnetic field force not only to provide the desired production of the electrical result but also to contribute to improving the mechanical operation involved including the return of the actuated key and code bar and the key touch sensed by the operator.

A further important object of the invention is to provide improved means for electrically reading out the keyboard transducing devices which performs its function only after assurance that the transducing devices are stabilized in read-out positions and also in a manner which substantially reduces the number of switch closures required for the code conversion.

In carrying out the objects of this invention, a preferred embodiment of the invention will comprise a plural number of improved magnetic transducing assemblies each composed of two closely spaced-apart stationary operating elements, specifically a magnet and a reed switch contact with responsive to the magnetic field, and further including a movable magnetic shunt member mounted to swing into and out of the space between the magnet and switch to vary the magnetic field affect on the switch. Each assembly is mechanically coupled to one or more of the keys of the keyboard in an improved manner such that utilization is made of the transducer's magnetic field for assisting in the return of the actuated key as well as in improving the operator's feel or touch of each individual key. In a machine employing the keyboard mechanism of this invention, it is preferred that the several operating elements for performing the code conversion and transducing cations be mounted in parallel planes preferably substantially vertically disposed along the rear side of the keyboard mechanism.

In such a preferred arrangement, a row of code bars individually operated from the keys from the keyboard are movable in the same direction in a common plane and are disposed opposite to a plurality of reed switches likewise mounted in a common plane extending parallel to but spaced from the plane of the code bars. INtermediate the code bars and reed switches are two further parallel planes of operating elements. In one, a plurality of permanent magnets, one for each reed switch, are mounted adjacent to their respective reed switches, so as to influence their operation. In the other plane, a plurality of code bails are pivotally mounted adjacent to the code bars but extending crosswise thereto. The code bails are provided with wing-like extensions on opposite sides of their respective pivotal axes, those on the side adjacent to the code bars being individually engaged and rocked thereby and on the opposite side facing the magnets each bail carries a generally L-shaped magnetic shunt disposed so as to closely hug two sides of the magnet when in interposing position between the magnet and the associated reed switch.

In further carrying out the objects of the invention, a pulse strobe source is provided which is operatively associated with the circuits of the reed switches and is initiated by at least one reed switch after all other reed switches which are actuated by the depression of a key have obtained a bounce or chatter free condition. This is accomplished in the illustrated embodiment of the invention by modifying one of the elements of the transducer assembly associated with the particular switch so as to delay its action after all other switches have attained a firmly closed condition. Additionally, the invention contemplates an electrical interconnection between the outputs of the magnetically influenced switches which substantially reduces the number of switch closures required for performing the code conversion from the decimal to binary coded decimal notation. In carrying out this object, the illustrated embodiment of this invention employs two separate switches for initiating the strobe read out pulse, one such switch being operatively associated with the even numbered keys of the keyboard and the other with odd numbered keys thereof.

The above listed objects, advantages, and other aspects of the invention will be further explained in the following detailed description. For a more complete understanding of the invention reference made be had to the following detailed description in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a keyboard code converting and transducing mechanism of a machine embodying the invention and showing the major operating elements of the mechanism;

FIG. 2 is a perspective view of the keyboard of the machine showing the disposition of the keys thereon and their respective identifying markings thereon;

FIG. 3 is an interior view of the machine directed rearwardly thereof and particularly showing the relation of the vertical extending key stems and code bars to the horizontal extending code bails;

FIG. 4 is a view of the machine as shown from the rear thereof and being partly broken away to illustrate the last two rearmost panels and operating elements associated therewith;

FIg. 5 is an enlarged detail view partly broken away in section and illustration one of the several magnetic transducing assemblies incorporated in the machine;

FIG. 6 is a fragmentary view of the inside surface of the rear panel of the machine and illustrating the printed wiring and reed switch elements carried thereon; and

FIG. 7 is a graph illustrating the key touch resistance encountered in the use of the machine embodying this invention as sensed by the operator thereof.

An embodiment of the invention as applied to electronic desk calculator type of business machine is illustrated in the various accompanying FIGS. With reference to FIGS. 1 and 2, the calculator includes a keyboard generally indicated as 10 comprising a plurality of keys 12 conventionally actuated by application of finger pressure on their respective key buttons. As shown in FIG. 2, the keyboard is subdivided into three groups of keys, a small mode select group 14 at the left end of the keyboard has general control of the machine, a larger group 16 serves to enter numeric data into the machine, and a similar size group 18 serves to provide operator control over the various functions of the machine. The keys 12 of the keyboard rise above a platform 20 serving as a cover plate for the machine which as illustrated herein lies in a horizontal plane. The cover plate together with the keyboard could be slightly slanted toward the operator, a design practice frequently adopted in business machines of this character.

Each key 12 is depressible in response to finger pressure moving, as illustrated by the full and dotted line positions of the left key in FIG. 1, from a normal raised position to a fully depressed condition. Although the keys 12 are arranged in columns and rows as illustrated in FIG. 2, their respective code converting elements 22, hereinafter referred to as code bars, are all arranged to move in response to key actuation in a common substantially vertical plane extending transversely of the machine. To provide this arrangement, the key stems 24 are each so constructed below the cover plate 20 as to dispose their respective code bars 22 in this vertical plane. Downward movement of the keys is yieldingly resisted by the provision of leaf spring members herein shown at 26 and 28 each of which act on extensions 25 and 25' of alternatively positioned key stems 24 and 24' This provision is a common practice in the art and no further comment is deemed necessary except to mention that a feature of the invention will be discussed hereinafter, concerning the improved key touch resistance characteristics derived from the mounting arrangement of the magnetic transducing devices. It is apparent that once finger pressure is removed from a key, either one of the springs 26 or 28 will exert force to return the key to its normal raised position on the keyboard.

The key members 12 and their respective key stems 24 and 24' and code bars are illustrated in FIG. 1, it being understood that additional keys and their respective stems and code bars are stacked in side by side relation with their code bars 22 all being in a common vertical plane extending generally parallel to the rear side of the machine. On each code bar 22 there are one or more projections 30 formed integrally therewith which, as shown in FIG. 1, extend in the direction of the rear side of the machine. The number and position of these projections 30 differ for each code bar so that each code bar is individually distinguished from all others in the machine. FIG. 3 is a view of the machine looking rearwardly thereof and showing the key stems 24 and particularly their grouping with respect to the several columns of keys on the keyboard 10. The key stems and associated code bars of each column are shown grouped together in a close side by side relationship leaving relatively large spaces between the column groupings. Moreover, as shown in FIG. 3, the key stems are usually offset to the central part of each key 12, a physical displacement having no affect on the operation thereof and usually being invisible from the exterior of the machine.

Along the rear side of the machine, and spaced from the plane of the code bars 22, is a provision for mounting a plurality of magnetic transducing assemblies for converting the mechanical positions of any depressed key to electrical signals representative of such selected key. Seven of such transducing assemblies 32 are employed in the illustrated embodiment of the invention for the keyboard 10, and they appear in the diagrammatic view of FIG. 1 as if arranged in a single vertical column. Actually, as illustrated in FIG. 4 these seven assemblies 32 are spread laterally apart in stepped relation along the rear of the machine. Each transducing assembly includes an electrical switch element herein taking the form of a magnetically influenced dry read contact unit 33. For ease in assembly and accessibility thereafter, the reed switch units are all mounted on a panel 34 and although partially recessed in the panel they are disposed on the side thereof facing toward the front end of the machine. Each reed switch unit is of conventional construction including an elongated glass envelope enclosing a pair of flexible contacts lying approximately along the longitudinally axis of the envelope with their adjacent ends in overlapping relationship. Details of the mounting provision for these reed switch units will be described hereinafter.

Disposed between the reed switches on the rear panel 34 and the code bars 22, and closer to the latter, is a vertical assembly of individually rockable members 36 pivotally mounted for rotation about individual axes extending parallel to one another in a common vertical plane and horizontally crosswise to the code bars 22. The rockable members 36, hereinafter referred to as code bails, extend completely across the machine from one side to the other side as shown in FIG. 3. Each code bail has a provision 38 extending toward the code bars 22 and into the path of travel of the projections 30 on the latter. As evident in FIG. 1, the projections 30, when their code bar is depressed, will abut certain of these extensions 38 and cause the associated bails to rock about their axes to positions corresponding to positions shown in dashed lines for two of the bails in FIG. 1. In this manner, it is evident that the code bars can permutatively operate one or more of the code bails to provide an encoded pattern representative of each key of the keyboard. In the illustrated embodiment of the invention, seven such code bails are provided, one associated with each reed switch 33 on the panel 34 and each on same general level therewith as illustrated in FIG. 1.

A plurality of sources of magnetic fields in the form permanent magnets 40 are arranged in a vertical plane between the code bails 36 and the panel 34 carrying the reed switches 33 as indicated in FIG. 1. In the present embodiment of the invention, seven such magnets are employed one associated with each reed switch in each transducing assembly. Each magnet is preferably in the form of a rectangularly shaped bar having a dimension approximating that of the reed switch with which it is associated and is mounted in closely spaced opposed relation to its associated reed switch with its long dimension parallel to the axis of the switch. The magnetic field created by each bar 40 is sufficient to affect its associated reed switch causing the switch elements therein to engage one another and place the switch in closed circuit condition. Although each magnet may be individually supported in adjacent relation to its respective reed switch, it is preferred to mount all of the magnets in a common plane and employ for this purpose a panel 42 formed of non-magnetic material such as molded plastic. Panel 42, as will be later described in detail herein, is located forwardly of and parallel to the panel 34 carrying the reed switches.

The magnetic influence of each magnet on its respective reed switch is modified by a magnetic shunt or shield member 44 which forms part of each transducing assembly and is carried by the code bail 36 thereof. In the manner generally shown in FIG. 1, and in detail in FIG. 5, each magnetic shunt 44 exhibits a L-shaped configuration including a horizontal portion 46 overlying its associated magnet 40 and a substantially vertical rear portion 48 capable of extending vertical downward between the magnet and the reed switch 33 with which it is paired. The opposite or forward end of each shunt member 44 is secured to its code bail 36 on the side thereof facing rearwardly of the machine. It is evident from FIG. 1 that when a code bail 36 is rocked about its axis by a projection 30 on one of the code bars, it will swing its shunt member 44 upwardly to the dotted position shown for two of the shunts in FIG. 1, in which attitude the vertical portion 48 of the shunt is completely withdrawn from the space between its associated magnet and reed switch. In one operating condition of the transducing assembly, the presence of the shunt portion 48 between the magnet and reed switch acts to inhibit the magnetic field from affecting the latter thereby allowing the contact elements of the reed switch to assume a spaced apart opened circuit condition, and in the other operating condition the shunt portion is swung out of this space enabling the magnetic field to influence the reed switch bringing its contact elements into engagement thus closing the circuit. It is understood, however, that the action of the reed switch elements may be reversed with respect to the position of the shunt portion 48, engaging one another to close the circuit when the shunt is swung into inhibiting position between the magnet and the lead switch; and springing into circuit opened condition when the shunt is swung out of the way.

The general relationship of the operating parts of the mechanism and certain structural features have now been described. Other features of the physical structure of the illustrated embodiment of the invention include side plates 50--50 which, as shown in FIGS. 3 and 4, cover the sides of the machine and serve as supports for various elements of the assembly. For example, as illustrated in FIG. 3, the ends of the rocking bails 36 are cylindrical shaped as at 52 and extend through circular openings 54 (FIG. 5) in the side plates. In this manner, each bail is pivotally journaled for at least the extent of movement illustrated in FIG. 1. THe code bails are formed of non-magnetic material and preferably of molded plastic material each providing a light weight slightly flexible structure extending across the space between the side plates. The very slightly yieldable nature of each bail provides a certain degree of tolerance in the event of overthrow by any key operation. The extension 38 of each code bail facing the code bars preferably takes the form of an elongated ridge or flange running the full length of the bail between the opposite side plates of the machine as shown in FIG. 3.

THe rear side of each code bail 36 is shaped to provide a detachable support for its magnetic shunt 44. With reference particularly to FIG. 5, the inner end of each shunt is provided with one or two apertures as indicated at 56 into each of which an integral button-shaped part 58 of the code bail fits with a snap action. The part 58 is opposed by a ledge 60 also formed integrally with the code bail, the space therebetween normally being less than the thickness of the inner end of the shunt so that the latter is releasably tightly gripped by the clamping action of these opposed parts of the bail.

The magnets 40 are recessly mounted as previously mentioned within the panel 42 which is preferably also formed of molded plastic material. Under each shunt 44 the panel is shaped with a recess 64 for receiving and fully seating 42 the associated magnet 40 of each transducer assembly as shown in FIG. 5. Immediately above each magnet there is provided an opening or window 66 in the panel 42 through which the horizontal portion 46 of the shunt extends in order to dispose the vertical portion 48 between the magnet and associated reed switch. The opening is provided at its upper end with an inclined wall 68 against which the shunt abuts in its fully raised position. To cushion the abutment of the shunt on the upper and lower walls of the opening 66, pads 70--70 are attached to the opposite sides of the horizontal portion 46 of each shunt thus softening the inpact and reducing the noise of the operation of the machine.

As a result of this particular mounting arrangement of each transducing assembly, each shunt 44 is magnetically attracted by its respective magnet 40 in the downward direction thereby urging its code bail to rock in the direction to assist the leaf springs 26 and 28 in returning the keys 12 to their normally raised positions. Moreover, this magnetic attraction is sufficiently strong enough to hold the shunts adjacent to their respective magnets regardless of whatever position the machine may assume, such as on its side or upside down. The L-shaped formation of each shunt increases the efficiency of the interaction with the magnetic field of its associated magnet. Both the horizontal portion 46 and the vertical portion 48 of each shunt are disposed in planes at approximately right angles to one another and in shunting position closely hug two adjacent sides of the magnet thus disturbing its magnetic field in two different planes. The partial enclosure of each magnet by its shunt, amounting to about 180.degree.around the longitudinal axis of the magnet, substantially increases the effective force of the magnetic field enabling it to assist in the return of the keys to their normal raised condition and to hold the shunt against accidental displacement.

Another feature of the invention which also results from this particular arrangement of the parts of each magnetic transducing assembly is the improved key touch. As a selected key is depressed, its motion is resisted by one or the other of the two leaf springs 26 and 28 and by the magnetic attraction exerted on those shunts of the bails which will be rocked by the key. The downward movement of the key is progressively increasingly resisted by its leaf spring but this is offset by the progressively decreasing magnetic resistance. As increasing resistance is provided by the leaf spring, the one or more shunts which are swung by this particular key are moved further away from their respective magnets thereby progressively reducing the magnetic pull or attraction previously exerted thereon. FIG. 7 graphically illustrate the distance versus force relationship occuring during movement of the key to its fully depressed condition. Tests have shown for the keyboard mechanism illustrated herein that as a selected key is depressed, increasing resistance is encountered as indicated by the upward slope 72 on the touch resistance curve which peaks at about two-thirds of the distance of key movement, after which for the remaining third of the movement progressively less resistance is felt as indicated by the downward slope 74 on the curve. This fall off in resistance during the last part of the key movement improves the feel of the keys as they are depressed by the operator.

Another feature of the invention concerns the provision for mounting the reed switches units 33. As earlier mentioned herein, the reed switches are carried on the back panel 34 formed of laminar plastic material, and in order to reduce the overall thickness of this panel assembly as much as possible, the reed switches are partially received in recesses 76 of slightly greater dimension than the switch envelopes. The recesses 76 preferably extend completely through the panel to the rear surface thereof as shown in FIG. 5 and provide windows through which the reed switches may be viewed from the rear while in operation in the mechanism. Also, preferably, the thickness of the panel 34 is slightly greater than the radius of the cylindrical envelopes containing the reed switch contact elements so that the envelopes do not protrude beyond the rear face of the panel 34 when properly mounted thereon with the longitudinal axis of the reed switch envelop in substantially flush relation with the inside or front face of the panel.

Connected to the reed switch contact elements in the envelope and projecting axially from the opposite ends thereof are leads or conductors 78. These leads are secured to the inner face of the panel 34 and serve as the sole means for supporting the reed switches thereon. A feature of the invention is the provision of printed wiring elements on the panel 34 and preferably on the inner face thereof which elements serve to connect the reed switches to one another as hereinafter explained and to equipment external of the machine. In other words, the whole panel 34 may take the form of a printed circuit board having printing wiring conductors 79 on the inner face thereof as shown in FIG. 6 and carrying the reed switches in recessed relation on this face solely by connection of their respective leads to such conductors. Other electronic components may be carried on the outer or back face of the printed circuit board as indicated at 80 in FIG. 4. A preferred form of securement for the reed switches is to solder each lead 78 to a separate printed wiring pad 82 on the panel as shown in FIG. 6 and in the enlarged view of FIG. 5 where a globule of solder 84 is indicated for serving this purpose. As in conventional practice, one or both ends of the printed circuit board may be provided with terminals and be shaped to fit into a connector 86 from which a cable 88 containing a plurality of wire leads for connection to external equipment.

It is apparent from the description thus far that the mechanical elements of the keyboard transducing assemblies cooperate with one another and with other elements of the machine to realize several important advantages and to achieve these advantages in an efficient and economical manner. By disposing the code bails 36 opposite and parallel to the back panel 34 carrying the reed switches and by providing suitable openings 66 in the intermediate panel 42 carrying the permanent magnets 40, a particular advantage is achieved by extending the magnetic shunts 44 through the panel openings 66 and by bending the shunts partially around their respective magnets. A greater magnetic reaction is obtained by conforming the shape of each shunt to that of its magnet, bringing it close to the magnet on two sides thereof thereby to increase the effectiveness of the magnetic attraction on the shunt. Moreover, the mounting relationship of these parts is such that the magnetic attraction applied to the shunt is in the direction which counters or opposes the finger pressure applied to depress the keys. As described in connection with FIG. 7 this mounting arrangement improves the feel of the keys to the operator while at the same time assisting in the return of the keys to their raised positions on the keyboard.

FIG. 1 schematically illustrates the circuitry, which may be constituted by the printed wiring on the panel 34, for reading out the reed switches carried by the back panel of the keyboard mechanism. As heretofore mentioned, improved means is provided for performing this operation only after assurance that the switches are stabilized in read-out condition. Moreover, as earlier pointed out, the circuitry is so designed as to reduce substantially the number of switch closures required for performing the code conversation. With reference to FIG. 1, the first six reed switches counted from the top have inputs connected to a source of voltage "V" by means of a common lead 90 and have their respective outputs marked with the binary digit values "1" , " 2" , " 4" , " 6" , " 8", and "16"as shown circled in FIG. 1. These outputs are connected individually to a series of AND-gates 92A to 92E. The last or seventh reed switch, identified for future reference herein as 33', is also connected to the common lead 90 and has its output 94 connected to a strobe pulse enabler "S" which, when switch 33' is closed, will cause such strobe source to apply pulses by conductor 96 to the series of AND-gates 92A to 92E. It is evident that an output pulse will occur on each AND gate upon concurrent receipt of a strobe pulse from source "S" and a signal from source V signifying the closure of the gate's respective reed switch. Pulses will therefore appear on the outputs of the gates of those reed switches which are closed, and such signals may be conveyed to a keyboard monitor circuit schematically identified at "M" which adapts these signals for use by a computer "C" or other utilization means with which the keyboard mechanism is associated.

In order to be sure that the reed switches which have been closed are stabilized in such condition, provision is made for timing the strobing operation to occur after such switches have reached this state. In the illustrated embodiment of the invention, this is accomplished by the simple expediency of elongating the vertical free end section 48' of the magnetic shunt 44 which is associated with the last or strobe initiating reed switch 33' and its magnet. The elongation of this shunt section is evident by comparing it with the similar end section of the next higher shunt 44 in FIG. 1. The longer extent of this shunt will delay the effect of the magnetic field on the reed switch 33' thereby causing it to assume its closed condition after all other actuated reed switches have attained closed position. It is thus apparent that the last or strobe controlling switch 33' will trigger the logic circuitry to read-out those reed switches which have reached a bounce-free stabilized, closed condition.

Another feature of the invention is that provided for substantially reducing the number of switch closures required for keyboard operation. This is accomplished in part by creating a "six" bit value for one of the reed switches 33, as indicated by the legend "6", and connecting its output through appropriate diodes with the outputs "2" and "4" of the reed switches representing such values. In other words, the six bit decimal representation is OR'd with the two and four bit reed switches. The six bit value can now be produced by closing the "6" reed switch instead of the "2" and "4" reed switches as would be conventional practice. By the creation of this six bit reed switch it is also possible to indicate the seven bit value by simply closing the reed switches representing the "1" and "6" rather than the three reed switches "1" , " 2" and "4" as heretofore in the use of the four binary digit values 1, 2, 4 and 8.

THe reduction in the number of switch closures necessary for the operation of this keyboard mechanism is further achieved by having the "1" reed switch also function as a strobe initiating switch. To attain this end, the output of the "1" reed switch is OR'd with the strobe control input conductor 94 as indicated by the unidirectional current connection 98. Furthermore, to achieve the desired stabilization of those switches actuated to closed condition, the magnetic shunt 44 associated with the "1" reed switch has its free end section 48' also elongated to the same extent as the shunt for the strobe reed switch 33'. As in the case of reed switch 33', the elongated shunt will delay the affect of the magnetic field on the "1" reed switch thereby causing it to close its circuit after those reed switches with shorter shunts have closed. In other words, connected in this fashion for triggering the strobe source "S", the "1" reed switch not only performs its value representing function but also serves as a strobe initiating switch for those reed switches with which it is associated for providing binary coded decimal signals to the utilization equipment with which the keyboard mechanism is associated.

The table following this paragraph indicates the code conversion for the keyboard and the number of switch closures performed by the circuitry illustrated in FIG. 1. In the table, the key symbols illustrated on the keys in FIG. 2 appear in the first column under "key", and their respective assigned decimal equivalents appear in the same rows of the second column under the heading "number". All of the remaining columns and rows contain either zeros or ones, a zero indicating the absence of a switch closure and a one signifying a switch closure. The "ones" in the "S" column indicate the strobe signals triggered by the closure of switch 33', and it evident from the column that this switch will be actuated to closed condition for all even numbered keys. The columns headed by the decimal values "16", "8", "6", "4", "2" and "1" correspond to the similarly designated outputs of the reed switches appearing in FIG. 1, and it is apparent that the binary coded equivalent of the decimal number assigned to each key appears in its row under these six column headings. The last or right most column lists the switch closures for the "1" decimal value switch, and it is evident from the appearance of the "ones" in this column that it closes alternately with respect to the strobe switch 33' and in response to the actuation of all odd numbered keys. For example, to represent the decimal "one" only the "1" reed switch is closed. To represent the odd number "7", it is evident from the table that switches "1" and "6" are closed thereby providing the binary coded representation "001001" . To represent the even number "8" the strobe initiating switch 33' and switch "8" are closed thereby resulting in the binary equivalent code "010000". It is apparent that for all decimal values below ten, such as represented by the keys in key group 16, only two reed switches need by closed. For most higher values on the keyboard only one additional switch closure is required. For example, to represent the decimal value 21 the reed switches designated "16" , "4" and "1" are closed resulting in the binary coded signal "100101". With these understandings it is believed that the following table will be readily understood:

KEY - S 16 8 6 4 2 1 0 0 1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1 2 2 1 0 0 0 0 1 0 3 3 0 0 0 0 0 1 1 4 4 1 0 0 0 1 0 0 5 5 0 0 0 0 1 0 1 6 6 1 0 0 1 0 0 0 7 7 0 0 0 1 0 0 1 8 8 1 0 1 0 0 0 0 9 9 0 0 1 0 0 0 1 D Z 10 1 0 1 0 0 1 0 D.P. 11 0 0 1 0 0 1 1 12 1 0 1 0 1 0 0 13 0 0 1 0 1 0 1 14 1 0 1 1 0 0 0 15 0 0 1 1 0 0 1 < 16 1 1 0 0 0 0 0 K 17 0 1 0 0 0 0 1 =.sup.- 18 1 1 0 0 0 1 0 - 19 0 1 0 0 0 1 1 N.P. 20 1 1 0 0 1 0 0 * 21 0 1 0 0 1 0 1 + 22 1 1 0 1 0 0 0 =.sup.+ 23 0 1 0 1 0 0 1 X 24 1 1 1 0 0 0 0 = 25 0 1 1 0 0 0 1 .div. 26 1 1 1 0 0 1 0 0/0 27 0 1 1 0 0 1 1 0/00 28 1 1 1 0 1 0 0 29 0 1 1 0 1 0 1 30 1 1 1 1 0 0 0 C 31 0 1 1 1 0 0 1

the above table provides a listing for 32 keys, but as it is evident therefrom a gap appears in the symbol "key" column for numbers 12 to 15 inclusive. These four keys are not employed in the illustrated embodiment of the invention. Of the remaining 28 keyboard codes used in the present embodiment, the numeric keys forming group 16 and illustrated in FIG. 2 are therefore covered by the twelve keys "0" to "11" identified in numeric column " " in the above table, including the keys "D.Z." meaning double zero (00 ) and "D.P." meaning decimal point (.). As shown in FIG. 2, the single cipher key is L-shaped around the "1" key for convenient accessibility. A single depression of the double cipher key "00" will enter two consecutive zeros into the mechanism. Physically associated with the numeric group 16 on the keyboard but no considered as a numeric entry key is a clear key "C" which is usually actuated when an alarm condition arises. THe depression of this key will clear any amount indexed into the mechanism and restore operation of the keys.

In order to further separate the remaining two groups of keys from numeric section 16, group 18 of operator control keys commences in the above table with the 16 bit value thereby providing the gap of unused bit values 12 to 15 inclusive in the table. In other words, the 12 operator control keys in group 18 and the three mode select keys in group 14 are all assigned binary codes containing the 16 bit value. Included in this category of keys and appearing at the end of the table is the clear key "C" previously mentioned which is assigned the highest binary value of those listed.

The following two tables illustrate the substantial savings in the number of switch closures obtained by incorporating the 6 bit switch output provision and granting the strobe capability to the "1" bit switch. Considering the numeric keys of group 16, the first of the following two tables compares the number of switch closures required to operate in (1 ) binary only, (2 ) binary with strobe "S". (3 ) binary with strobe "S" and digit value "6", and (4 ) binary with strobe "S", digit value "6" and strobe capability for switch "1" .

(1 ) (2) (3) (4 ) KEY Binary Binary With Binary With Binary With Only with Strobe "S" Strobe "S", Strobe and Digit Digit value "6" 37 S" Value "6" and Strobe "1" 0 0 1 1 1 1 1 2 2 1 2 1 2 2 2 3 2 3 3 2 4 1 2 2 2 5 2 3 3 2 6 2 3 2 2 7 3 4 2 2 8 1 2 2 2 9 2 3 3 2 D.Z. 2 3 3 3 D.P. 3 4 4 3 20 32 29 24

in the above table, the first column (1 ) headed by the word "Binary Only" lists the number of switch closures for each key of the keyboard section 16 but without the desired strobing read-out action and therefore is unsatisfactorily for reliable operations. Providing the switch 33' and strobe source gains the benefit of the delayed strobing function for reliable read-out purposes but increases the number of switch closures from 20 to 32 as shown by the summation of column (2 ). If the digit value "6" is added to the read-out circuitry by "OR"ing the "6"output with the "2" and "4" outputs, then the total number of switch closures is reduced from 32 to 28 as shown at the bottom of the third column. If the "1" switch 33 is given the additional function of initiating a strobing action then together with the digit value "6" and its connection to outputs "2" and "4", the number of switch closures provided by the read-out system is reduced to 24 as shown by the last column of the above table. It is apparent that with the two improvements in the read-out system, namely, the addition of the digit value "6" and its output connections and the addition of the strobe for "1" switch, it is possible to reduce the total number of switch closures almost to that which would occur if no strobing action where utilized at all as represented by the first column of the table. Wanting the strobing function for reliable read-out operation, it is apparent from the above table that by combining the two improvements as illustrated by column (4 ) there will result in this instance a figure of merit represented by a reduction ration of from 32 to 24 or a 25 percent reduction in the total number of switch closures necessary to be made by the numeric section 16 of the keyboard.

The second table presented herebelow covers the balance of the keys of the keyboard, namely, sections 14 and 18 of the keyboard. In this table, the columns are arranged and labeled in the same fashion as the preceeding table for convenient comparison. It is evident that because of the higher binary digit values involved that an increased number of switch closures occur for these keyboard sections. However, it is evident that by incorporating the previously mentioned two improvements, namely, the digit value "6" output and the strobe capability for the "1" switch, that the number of switch closures is reduced to almost the number that would be encountered for binary read-out system having no strobing function as the first system having no strobing function as the first column of the table illustrates. Comparing column (2 ) having the single strobing action "S" with column (4 ) which includes the two improvements it is apparent that a reduced ratio of from 96 to 76 switch closures is obtained which represents an approximate 21 percent reduction in the number of switch closing operations for the second and third sections of the keyboard.

(1) (2) (3) (4) KEY Binary Binary Binary With Binary with Only with Strobe "S" Strobe "S", Strobe and Digit Digit Value "6" "S" Value "6" and Strobe "1" < 1 2 2 2 K 2 3 3 2 =.sup.- 2 3 3 3 - 3 4 4 3 N.P. 2 3 3 3 * 3 4 4 3 + 3 4 3 3 =.sup.+ 4 5 4 3 X 2 3 3 3 = 3 4 4 3 .div. 3 4 4 4 0/0 4 5 5 4 0/0 3 4 4 4 4 5 5 4 4 5 4 4 C 5 6 5 4 68 96 89 76

the totals of the columns in the immediate preceding table include the totals of the earlier table for the keys of group 16 of the keyboard.

In the illustrated embodiment of the invention, key symbols are employed, as indicated in the several above tables, which correspond to the keys of the keyboard sections 14, 16 and 18 illustrated in FIG. 2. The numeric keys of section 16 are arranged in accordance with the present standard layout with the exception of the shape and location of the single and double cipher keys. Factors to be added, substracted, multiplied or divided are entered by depressing sequential from left to right the listing keys of section 16 representing the numeric digits of the factors to be operated upon. The mode and functional control keys of sections 14 and 18, as well as their respective symbols signifying their use, may be varied, and the keyboard of FIG. 2 is merely illustrative of one arrangement for which the invention is adapted. Indicator lamps, not shown, may be located on the keyboard, one, for example, for indicating an alarm condition, and others for indicating the selected mode of operation of the mechanism.

While a particular embodiment of the invention has been shown and described, it will be understood, of course, that it is not desired that the invention be limited thereto since modifications may be made. The foregoing explanation is therefore by way of illustration only. It is, therefore, contemplated by the appended claims to cover any such modifications as fall within the true spirit and scope of the invention.

Claims

What is claimed is:

1. Keyboard mechanism comprising, in combination:

a plurality of actuatable keys arranged in rows and columns,

a plurality of electrical switch devices substantially fewer in number than the keys of the keyboard,

each electrical switch device comprising a magnet elongated in one dimension, an elongated reed switch mounted in closely spaced parallel relation to the long dimension of the magnet and including a pair of contact elements movable to assume two functional conditions either in or out of engagement with one another and operable by magnetic flux from said magnet to be moved to assume one of said switch conditions, a bail member pivotally mounted for rocking movement about an axis parallel to the reed switch, and a magnetic shunt carried by the bail bent to extend approximately 180.degree. around the magnet and swingable about the rocking axis of the bail member from a position in which it hugs two adjacent longitudinally extending sides of the magnet for substantially the entire length thereof and is interposed between the magnet and the reed switch to a position which is withdrawn from the magnet, said shunt being operable in its withdrawn position to render the magnetic flux effective to move the reed switch elements to assume said one functional condition and being operable in the hugging interposed position to render the magnetic flux ineffective upon the reed switch contact elements thereby causing the elements to assume the other functional condition,

each said key being operatively connected to one or more but not all of the bail members for pivotally withdrawing their respective shunts when the key is actuated, each key permutatively pivoting a different one or more of the bail members to provide a distinctive coded representation of the keys, and

electrical leads connected to the switch elements of the reed switches for conveying data signals to a utilization device.

2. The invention defined in claim 1 characterized in that the pair of contact elements of each reed switch are normally positioned in spaced apart relationship to assume one of said functional conditions but are capable of being sprung into engagement with one another by the magnetic flux from the associated magnet to assume the other functional condition.

3. Keyboard mechanism comprising, in combination:

a plurality of actuatable keys arranged in rows and columns,

a plurality of electrical switch device substantially fewer in number than the keys of the keyboard,

each electrical switch device comprising a magnet, an elongated reed switch mounted adjacent to the magnet and including a pair of contact elements movable to assume two functional conditions either in or out of engagement with one another and operable by magnetic flux from said magnet to be moved to assume one of said switch conditions, a bail member pivotally mounted for rocking movement about an axis parallel to the reed switch, and a magnetic shunt carried by the bail bent to extend approximately 180.degree. around the magnet and swingable about the rocking axis of the bail member from a position in which it hugs two sides of the magnet and is interposed between the magnet and the reed switch to a position which is withdrawn from the magnet, said shunt being operable in its withdrawn position to render the magnetic flux effective to move the reed switch elements to assume said one functional condition and being operable in the hugging interposed position to render the magnetic flux ineffective upon the reed switch contact elements thereby causing the elements to assume the other functional condition, each said key being operatively connected to one or more but not all of the bail members for pivotally withdrawing their respective shunts when the key is actuated, each key permutatively pivoting a different one or more of the bail members to provide a distinctive coded representation of the keys,

electrical leads connected to the switch elements of the reed switches for conveying data signals to a utilization device,

said pair of contact elements of each reed switch being normally positioned in spaced apart relationship to assume one of said functional conditions, but capable of being sprung into engagement with one another by the magnetic flux from the associated magnet to assume the other functional condition, and

one of the electrical switch devices serving to control the read-out of all of the remaining electrical switch devices and having means for causing the contact elements of said read-out control switch to be sprung into engagement with one another only after all of the contact elements of the remaining switch devices have assumed one or the other of their functional conditions as the result of the actuation of a selected key of the keyboard.

4. A keyboard comprising, in combination:

a plurality of data keys;

a plurality of code bars operable in response to the movement of the corresponding data keys;

a plurality of code bails adapted to be moved by the code bars to one or the other of two positions in predetermined combinations representative of selected data keys;

a plurality of reed switches, one for each code bail, having a magnetic field source adjacent thereto and being influenced by said field to one of either its opened or closed circuit conditions;

a magnetic shunt carried by each of said code bails and operable in one of the two positions of movement of its bail to be interposed between its associated reed switch and magnetic field source thereby to inhibit the influence of the latter on the reed switch and in the other position of movement of its code bail to be withdrawn from interposing relation thereby permitting the magnetic field source to influence its reed switch to said one of said circuit conditions;

means electrically connecting all but one of said reed switches in circuit parallel relation to one another;

means electrically connecting said remaining one of the reed switches in circuit series relation to the parallel circuit in which the remaining reed switches are connected; and

means responding to the movement of each data key of the keyboard for causing the closure of said one remaining reed switch only after all of the remaining reed switches affected by such key movement have assume the circuit condition to which they are influenced by their respective magnetic field sources.

5. Keyboard mechanism comprising in combination:

a plurality of manually operable data keys arranged in rows and columns,

a plurality of code bars arranged in a common plane and each being movable from a first to a second position in response to the actuation of the corresponding data key to which it is connected;

a plurality of code bails arranged in a common plane adjacent and parallel to the plane of the code bars and being capable of being moved by the code bars to one or other of two positions in predetermined combinations representative of selected data keys;

a plurality of reed switches, one for each code bail, each having a magnet adjacent thereto and being influenced thereby to one of either its opened or closed circuit conditions;

a magnetic shunt carried by each of said code bails and operable in one of the two positions of movement of its bail to be interposed between its associated reed switch and magnet thereby to inhibit the influence of the magnet on the switch and in the other position of movement of its bail to be withdrawn from such interposing relation thereby permitting the magnet to influence its switch to said one of said circuit conditions;

means for producing a strobe pulse and applying the same to the reed switches in order to provide electrical signals on the outputs of those reed switches which are closed; and

means responsive to the movement of each of said plurality of code bars to its second position for rendering said strobe pulse producing means operable only immediately after the reed switches have assumed one or the other of their operating conditions as the result of the actuation of a selected data key and only after the completion of the movements of one or more of the code bails affected by such actuation, and

means mounting each shunt with respect to its magnet such that the attractive force of the magnetic field acting on each shunt is in the direction to rock its respective code bail opposite to that applied by the code bars to rock the bail with the result that each key actuation is yieldingly opposed by the magnetic fields of the permanent magnets.

6. In keyboard mechanism including a plurality of actuatable key members each adapted to be selected and actuated by an operator and further including a plurality of elongated code bars, each operatively associated with an individual key member and each being movable in response to the actuation of its key member, and a plurality of pivotally mounted code bails positioned in juxtaposed crosswise relation to said code bars and operatively associated therewith such that each code bar will rock a distinctive set of one or more of said code bails when a selected key member is actuated;

a plurality of stationary electrical switches each associated with an individual one of said code bails and each having an input and an output, said switches each being capable of assuming one or the other of two functional conditions depending upon the strength or weakness of an applied magnetic field and in one case enabling an electrical signal to be produced on its output in response to the receipt of electrical current on its input and in the other case being prevented from so doing;

a plurality of stationary permanent magnets each placed in close but spaced relation to an individual one of said switches so that the latter may be influenced by the magnetic field of the magnet with which it is paired;

a plurality of magnetic shunts of generally L-shaped configuration each attached at one end to an individual one of said code bails and having its other end bent and terminating freely and each responding to the rocking movement thereof of its code bail by swinging through an arcuate path from one position in which the bent free end of the shunt is interposed between the switch associated with the code bail and the magnet with which it is paired to another position retracted away from the magnet, the generally L-shaped configuration of each shunt and its mounting relationship with its respective magnet and switch enabling the shunt in its interposed position to closely hug two sides of the magnet and divert its magnetic field from the switch thereby causing the switch to assume one of its two said functional conditions and in its retracted position exposing the switch to the magnetic field of the magnet thereby causing the switch to assume the other of its two functional conditions;

means connecting the inputs of each of said switching elements to a source of electrical energy for providing electrical signals on the outputs of those switching elements so conditioned to do so by the positions of their respective magnetic shunts whereby a coded pattern of electrical signals indicative of an actuated key member can be derived, and

means mounting each shunt with respect to its magnet such that the attractive force of the magnetic field acting on each shunt is in the direction to rock its respective code bail opposite to that applied by the code bars to rock the bail with the result that each key actuation is yieldingly opposed by the magnetic fields of the permanent magnets.

7. A code converter assembly comprising, in combination:

a row of code bars linearly movable in the same direction in a common plane and each carrying one or more lateral projections directed outwardly from one side of the row:

a plurality of reed switches mounted in a common plane extending parallel to but spaced from the plane of the code bars and on the side thereof from which the lateral projections extend;

a plurality of magnets, one for each reed switch, and each elongated in a dimerson parallel to its reed switch, and mounted in a common plane disposed intermediate the code bars and the reed switches and each operable to have its magnetic field influencing its associated reed switch to closed position;

a plurality of code bails, one for each reed switch, mounted in a common plane between the code bars and the reed switch magnets and extending parallel thereto, said bails being pivotally supported for rockable movement about individual axes extending parallel to one another and crosswise to the direction of linear movement of the code bars;

each said code bail being provided with a wing-like extension on one side of its pivotal axis projecting into the path of movement of the lateral projections carried by the code bars so that when the code bars are moved the projections engage and rock the bail in one direction about its axis;

each said code bail being further provided with a second wing-like extension on the opposite side of its pivotal axis projecting toward its associated side of its pivotal axis projecting toward its associated reed switch and terminating in material forming a generally right angularly bent magnetic shunt, said shunt being attracted by the magnetic field of the magnet and rocked thereby into interposing position hugging two sides of the magnet for substantially the entire length thereof and extending between the same and the read switch to inhibit the influence of the magnet on the latter, the force exerted by the magnetic field of the magnet to rock the code bail about its axis being in the direction opposite to that exerted by the projections on the code bar whereby each shunt normally assumes its interposed position and yieldingly resists rocking movement of its code bail tending to withdraw the shunt from between its associated magnet and reed switch; and

electrical leads connected to the reed switches for delivering electrical signals to a utilization device.

8. The invention defined in claim 7 characterized in that a panel is provided for mounting the permanent magnets in their common plane and in that the panel is provided with an opening immediately adjacent to each magnet through which its shunt extends so as to dispose the bent extremity of the shunt on the side of the panel opposite to the code bails and in hugging relationship to the magnet.

9. The invention defined in claim 7 characterized in that a panel is provided for mounting the reed switches in their common plane, the panel having printed wiring conductors on at least one side thereof and being recessed adjacent each reed switch to receive the same, the individual leads of each reed switch being secured to the printed wiring conductors of the panel to support the reed switch within its respective recess.

10. Key mechanism comprising, in combination:

a plurality of actuatable odd valued keys and even valued keys numbered from the "one" value to at least the "ten" value and including the "one" value key:

a plurality of electrical switches substantially fewer in number than the total number of odd and even valued keys on the keyboard;

means responsive to the actuation of any selected key of the keyboard for closing one or more of the switches, each actuated key permutatively closing a different one or more of the switches to provide a distinctive coded representation of the key;

means for producing an electrical strobe pulse and applying the same to the switches in order to provide electrical signals on the outputs of those switches which are closed;

one switch being common to each of the even valued keys and serving to initiate the strobe producing means; and

a second switch being common to the odd valued keys and serving to initiate the strobe producing means.

11. The invention defined in claim 10 characterized in that the means for initiating said strobe pulse producing means perform their respective functions immediately following closure of any one or more of said switches as the result of the actuation of a selected key of the keyboard.

12. The invention defined in claim 10 characterized in that one of said strobe initiating means is responsive to the closure of the switch of said plurality of said switches representing the "one" value.

13. In ten key type keyboard mechanism:

a keyboard of consecutively numbered keys from the "one" value to at least the "ten" value;

a plurality of electrical switches;

means responsive to the actuation of any selected key of the keyboard for closing one or more of the switches, each actuated key permutatively closing a different one or more of the switches to provide a distinctive coded representation of the key;

means for producing an electrical strobe pulse and applying the same to the switches in order to provide electrical signals on the outputs of those switches which are closed;

means in common with said even valued keys and operatively associated with the switches closed by the even valued keys for initiating the operation of said strobe producing means; and

separate means in common with said odd valued keys and operatively associated with the switches closed by the odd valued keys for initiating the operation of said strobe producing means, said last means being responsive to the actuation of the "one" valued key of the keyboard.

14. The invention defined in claim 13 characterized in that the "six" valued key of the keyboard has its output connected to the outputs of the "two" and the "four" valued keys of the keyboard.