Photocomposing Apparatus And Method For Varying Character Magnification

Abstract

This disclosure depicts apparatus and method for selectively varying character magnification during photocomposition. Photocomposing apparatus is shown as including means for displaying a character to be recorded and a plurality of lenses of different focal length mounted upon a rotatable lens turret. Novel turret indexing means is disclosed as comprising turret monitoring means for determining coarsely when a selected one of the lenses is approaching an axis along which the characters are projected, switch means actuated by cam means on the turret for determining when the selected lens is substantially on the projection axis, and extremely accurate turret locking means which is responsive to inputs from the turret-monitoring means and the switch means for locking the turret with the selected lens located precisely on the projection axis.

Description

BACKGROUND OF THE INVENTION

For many applications the capability of a photocomposing system to vary the magnification of the recorded characters is essential. In the past, this expedient has been achieved either by manual interchange of projection lenses of different focal length, or by automatic interchange of lenses with complex and relatively costly structures.

There has been recognized a very great need for a photocomposing system which has the requisite high performance, yet which is priced within reach of the thousands of medium and small-sized printing operations. To be of optimum usefulness in such printing operations, such low cost apparatus must have a variable character magnification capability.

OBJECTS OF THE INVENTION

It is an object of this invention to meet the above-stated needs in photocomposing systems with apparatus providing for the selection of different character magnifications over a wide range of magnification values, and yet which is of low cost and uncompromised performance.

To this end, it is an object to provide apparatus in a photocomposing machine for varying character magnification including novel means for indexing a lens turret, which utilizes a unique combination of low-cost components cooperating in a novel way to give the said high performance.

Further objects and advantages of the invention will in part be obvious and will in part become apparent as the following description proceeds.

The features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference may be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIG. 1 is a partially schematic perspective view of apparatus implementing the principles of this invention; and

FIG. 2 is a perspective view of the apparatus shown in FIG. 1 taken from a different viewpoint and showing in more detail character display means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drawings illustrate photocomposing apparatus implementing the principles of this invention which, as stated above, involve novel means and methods for precisely indexing a lens turret carrying a plurality of lenses of different focal length for providing a range of selectable character magnifications.

The drawings illustrate a portion of a photocomposing machine according to a preferred embodiment of the invention, including generally, a character display device 10 in which a selected character is flash-illuminated, an optical projection system 11 for projecting an image of the selected character, and a flexible fiber optic bundle 12 for transferring the projected character image to a recording station (not shown).

The character display device 10 is illustrated as comprising a character display drum 15 rotatably mounted on an axle 16. The drum 15 is transparent and may be constructed from materials such as glass or certain of the transparent plastic materials. On the periphery of the drum 15 is formed a channel 17 which receives film strips 21 acting as character storage members.

The sides of the channel 17 are defined by a pair of accurately machined flanges 19, 20.

Positioned around the circumference of the drum 15 and associated with the film strip receiving channel 17 are a plurality of fasteners 22, 24 adapted to penetrate holes 23 in the ends of the film strips 21. The fasteners have threads 25 for engaging the hub 36. Insert holes 26 in the drum 15 permit finger access to the fasteners 22, 24.

A light source 28 and a photocell 30, arranged on opposite sides of the drum 15, cooperate with a row of timing lines 45 on the film strips 21 to generate a train of pulses useful in monitoring the locations of a row of alphanumeric characters 44 on the film strips 21. The light source 28 is mounted within the character display drum 15 and positioned behind film strip receiving channel 17. The light source 28 is shown as being mounted on a support member 29 secured to the frame of the machine. The photocell 30 is mounted on a support 31 opposite light source 28.

A stroboscopic flash lamp 33 is positioned within the character display drum 15 and mounted on a suitable support 34 also secured to the frame of the machine. The lamp 33 is capable of being flashed for an extremely short duration, such as, for example, a few microseconds.

The entire drum assembly, consisting of the character display drum 15 and members mounted thereon is rotatably mounted on the axle 16. This is accomplished for example, by means of a hub 36 mounted on bar 37 which may be connected, for example, with a rotatable sleeve 38. At the lower end of the sleeve 38 is a pulley 39 operatively driven by a drive member or belt 40 which, in turn, is operatively mounted to be driven by pulley 41 on a drive motor (not shown).

The optical projection system, generally designated 11, is illustrated in both FIGS. 1 and 2, but is perhaps more readily understood in the enlarged simplified presentation in FIG. 2. This optical projection system includes a lens support in the form of a turret 46 comprising a plate 47 which is rotatably mounted on a shaft 48.

A plurality of projection lenses 54 is mounted on turret 46, each lens being of a different effective focal length and each being positioned so as to project an image at a predetermined magnification from the film strip 21 along a projection axis 50 to a fixed input end 55 of fiber optic bundle 12.

In accordance with this invention, low-cost but high-performance means are provided for accurately indexing the turret 46 upon command so as to position a selected one of the plurality of lenses precisely on the projection axis 50. To this end, there is provided low-cost turret-monitoring means for coarsely determining when a selected one of the lenses 54 is approaching the projection axis, and inexpensive switching means for determining when the selected lens is substantially on the projection axis. The outputs from the turret-monitoring means and the switching means are fed to an electronic control circuit which effects energization of a turret drive motor and actuates an inexpensive but very accurate locking device to lock the turret 46 with the selected lens precisely on the projection axis 50.

Referring now to the drawings, the structures performing the above-described functions in the illustrated embodiment will be discussed. In the illustrated embodiment the turret 46 is driven by a motor 60 through a pair of speed-reducing spur gears 62, 64.

The motor is preferably a relatively small, slow speed AC motor of the unidirectional friction drive type which are readily available commercially at very modest prices.

The turret monitoring means is shown as taking the form of a rotary switch 66 driven at the same rate as the turret 46 by the motor 60 through a spur gear 67 meshed with the spur gear 64 on the turret shaft 48. The switch 66 is here shown as a 10-position switch corresponding in the number of switch terminals to the number of lenses 54 carried by the turret 46. In accordance with this invention, the rotary switch 66 need have very little accuracy and is therefore obtainable commercially at relatively low cost. Lead 68 connects the rotary switch 66 to a combinational logic circuit 70 which acts to control the operation of the turret-indexing system. The function of the combinational logic circuit 70 will be described in detail hereinafter.

The means for determining when the selected lens is on the optical projection axis is shown as taking the form of a microswitch 72. The switch 72 need have only moderate accuracy and may be of any of a variety of types which are available commercially at low cost. The microswitch 72 has a spring-biased plunger 74 carrying on the end thereof a rotatably mounted wheel 76. The outer periphery of the turret plate 47 has conical recesses 78 machined therein with high positional accuracy, one being located on each of the radials on which the lenses 54 are located. The recesses 78 serve as accurate angular reference points for the lenses 54.

The lens turret 46 is shown as carrying ten lenses arranged in diametrically opposed pairs. The number of lenses which may be employed is arbitrary. The microswitch plunger 74 is precisely located on the diametrically opposite sides of the turret rotational axis from the optical projection axis. Thus, when the wheel 76 on the microswitch plunger 74, acting as a cam follower, descends into a recess 78 in the plate 47, the microswitch 72 is actuated to indicate that a projection lens 54 on the opposed side of the turret 46 from the microswitch 72 is located substantially on the optical projection axis 50. A lead 80 from the microswitch 72 supplies the described turret position information to the combinational logic circuit 70.

In order to lock the turret 46 securely in place with extreme positional accuracy when the selected lens 54 has been indicated to be located on the optical projection axis, a low-cost locking device 84 is provided. The locking device 84 is positioned accurately with respect to said projection axis 50. The locking device 84 is shown as taking the form of a solenoid 86 having a plunger 88 biased outwardly by a coil spring 90. The plunger 88 is shown as having a head 92, which may be composed of Delrin (TM) or the like, having an accurately determined male conical configuration which mates with the conical recesses 78 on the periphery of the turret 46. A switch 94 actuated by movement of the plunger 88 is shown schematically as comprising a pair of contacts 96, 98 connected in a motor energization circuit 100. The motor energization circuit 100 includes a source of AC power, here shown schematically as a generator 102.

The operation of the system is as follows. A series of characters to be set in type are fed into the system in binary code on a perforated paper tape 104. Alternatively, the character information may be supplied from a keyboard. The tape 104 is shown as being read by a tape reader 106. The coded character information is fed from the reader 106 to a sequential logic circuit 108. One of the functions performed by the logic circuit 108 is to decode a signal from the tape 104 which indicates the magnification of the characters. This signal is fed to the combinational logic circuit 70 which compares the coded signal indicating desired magnification with a code indicating the magnification of the lens 54 presently on the optical projection axis. If the information does not correspond, that is, if a different lens is needed, the circuit 70 supplies an energization signal to the solenoid 86 causing the plunger 88 to retract, thereby releasing the turret 46 and closing the switch 94 in the motor energization circuit 100. The motor 60 is thus energized, causing the lens turret 46 to rotate. Simultaneously therewith the wiping contact in the rotary switch 66 is caused to rotate. The combinational logic circuit 70 contains well-known comparing circuits which compare the sequentially derived signals from the rotary switch 66 with the coded magnification signal received from the sequential logic circuit 108. The combinational logic circuit 70 also performs an AND function as will become evident from the ensuing description. When the selected lens 54 is next approaching the optical projection axis, as indicated by a correspondence of the signal from the rotary switch 66 with the coded magnification signal derived from the sequential logic circuit 108 and the microswitch 72 signals the location of the selected lens substantially on the projection axis 50, the combinational logic circuit 70 deenergizes the locking device 84. Deenergization of the locking device 84 causes the coil spring 90 to thrust the plunger 88 into the recess 78 radially registered with the selected lens 54 to thereby lock the selected lens precisely on the projection axis. The projection of the plunger 88 into the recess 78 opens the switch 94 to inactivate the turret drive motor 60.

Throughout this specification and in the claims appended hereto, the switch 72 has been described as signaling when a lens 54 is located substantially on the optical projection axis. This description should be construed to allow for a small lead time since, in practice, the actuation of the plunger 88 is preferably caused to slightly lead the position of the turret 46, that is to say, the locking device 84 is deenergized slightly before the selected lens 54 is on the projection axis. This provision eliminates the possibility that the turret 46, which is preferably driven unidirectionally, might overrun the index position. The mating conical configuration of the plunger 88 and recesses 78 performs an extremely precise positioning function and determines the accuracy of the turret position when locked at an index location.

It is seen then that by this invention a unique combination of commercially abundant, low-cost components cooperate in structure and function to provide a low cost, yet extremely accurate turret-indexing system for a photocomposing machine.

Certain changes may be made in the above-described apparatus and method without departing from the true spirit and scope of the invention herein involved. For example, means other than the motor 60 may be employed to drive the turret 46. The lens support may be a translatable carriage rather than a rotatable turret. The turret monitoring means need not be a rotary switch as described, but may take other forms consistent with its requisite function of coarsely monitoring the turret position. The means for signaling the location of the selected lens substantially on the projection axis need not take the form of a microswitch sensing the location of conical recesses in the turret periphery which cooperate also in the turret-locking function. Other arrangements are within the purview of this invention. It is therefore intended that the above depiction shall be interpreted as being illustrative, and not in a limiting sense.

Claims

What is claimed is:

1. In photocomposing apparatus, the combination comprising:

means for establishing a character to be recorded;

a lens support carrying a plurality of lenses in spaced relationship;

means mounting said lens support for movement such that said lenses are successively brought into position on an optical projection axis when said support is moved; and

lens support indexing means for moving said lens support to successively locate different ones of said plurality of lenses on said projection axis, comprising:

motive means for moving said lens support,

monitoring means for monitoring the position of said lens support to determine coarsely when a selected one of said plurality of lenses is approaching said projection axis,

electrical sensing means responsive to movement of said lens support for determining when said selected lens is located substantially on said projection axis,

electrically operable highly accurate mechanical locking means for locking said lens support, and

control means responsive to said monitoring means and to said sensing means for actuating said locking means when said selected lens is substantially on said projection axis, said locking means upon actuation very precisely fixing the position of said selected lens on said axis.

2. In photocomposing apparatus, the combination comprising:

means for establishing a character to be recorded;

a lens turret carrying a plurality of lenses in angularly spaced relationship;

means mounting said turret for rotation such that said lenses are successively brought into position on an optical projection axis when said turret is rotated; and

turret indexing means for rotating said turret to selectively locate different ones of said plurality of lenses on said projection axis, comprising:

motive means for rotating said turret,

monitoring means for monitoring the angular position of said turret to determine coarsely when a selected one of said plurality of lenses is approaching said projection axis,

electrical sensing means responsive to movement of said turret for determining when said selected lens is located substantially on said projection axis,

electrically operable highly accurate mechanical locking means for locking said turret, said locking means being positioned accurately with respect to said axis, and

control means responsive to said monitoring means and to said sensing means for actuating said locking means when said selected lens is substantially on said projection axis, said locking means upon actuation very precisely fixing the position of said selected lens on said axis.

3. The apparatus defined by claim 2 wherein said turret defines a plurality of recesses angularly spaced thereon and wherein said locking means includes a solenoid having a plunger adapted to enter one of said recesses to lock said turret when said solenoid is energized.

4. The apparatus defined by claim 3 wherein each of said recesses has a female conical configuration and wherein said plunger has a tip with a male conical configuration mating with said female conical configuration of said recesses.

5. The apparatus defined by claim 2 wherein said turret includes a plurality of sharply defined angularly spaced cam means, and wherein said sensing means comprises a switch having an actuator following said cam means.

6. The apparatus defined by claim 3 wherein said sensing means comprises a switch having an actuator positioned to sense said recesses in said turret.

7. The apparatus defined by claim 6 wherein said monitoring means comprises a rotary switch operatively coupled to said motive means and driven thereby in synchronism with said turret.

8. In a photocomposing machine, the combination comprising:

means for displaying a character to be recorded;

means for forming a real image of said character along a projection axis at a predetermined variable magnification, including a turret carrying a plurality of lenses of different effective focal length angularly spaced at equal radii on said turret and means mounting said turret for rotation such that said lenses are successively brought into position on said axis when said turret is rotated, said turret having a plurality of sharply defined angularly spaced cam means;

motive means for rotating said turret unidirectionally at a constant rate;

electrically operable highly accurate locking means for locking said turret upon actuation thereof;

position-sensing means for sensing the angular position of said turret, comprising:

a rotary switch coupled to and driven by said motive means for determining coarsely when a selected one of said plurality of lenses is approaching said projection axis, and

switch means actuated by a cam follower positioned to sense said cam means when said turret is rotated for determining when said lens is substantially on said axis; and

control circuit means responsive to said rotary switch and to said switch means for actuating said locking means to lock said turret with said selected lens accurately positioned on said projection axis.

9. The apparatus defined by claim 8 wherein said cam means on said turret comprise recesses in the periphery thereof, and wherein said locking means includes a solenoid having a plunger oriented to penetrate a particular recess associated with said selected lens and thereby lock said turret when said solenoid is energized by actuation of said locking means.

10. The apparatus defined by claim 9 wherein said recesses have a female conical configuration and wherein said plunger has a tip with a male conical configuration mating with said recesses.

11. In a photocomposing process, a method comprising:

selecting a character to be recorded and locating said character on a projection axis;

moving a series of lenses of different focal length successively across said projection axis;

electrically sensing coarsely when a selected one of said plurality of lenses is approaching said projection axis;

electrically sensing more accurately when said selected lens is substantially on said axis; and

responsive to the said coarse and more accurate sensing, locking said selected lens precisely on said axis.