CA1099974A - Custom programmable phototypesetter - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A phototypesetter is disclosed having a stepping motor which actuates an escapement carriage coupled to an elongated carriage driving member. A projection lens carriage and a collimating lens carriage are selectively electromagnetically coupled to the elongated driving member, thereby to project images of varying character sizes through a focusing lens coupled to the escapement carriage, which sequentially projects focused character images across a photosensitive film on a line by line basis. A track select mirror is also selectively electromagnetically coupled to the elongated driving member for selectively projecting one of a plurality of tracks bearing characters of differing fonts carried by a rotatable font carrier element. A group of custom-ized lens carriage positioning control codes and customized sizing codes, unique for each phototypesetter as a function of lens parameter variations, are stored within a size dictionary and a particular set, associated with the character size being typeset is read out of the dictionary and is employed to control the customized positioning of the lens carriages and image (film) positioning stepping motors. A novel technique is also disclosed whereby a customized group of the above-mentioned codes is rapidly and easily generated by an iterative image inspection process for each particular phototypesetter during manufacture.

Description

The present applic~tion is a divisional of Canadian Patent application Serial No. 269,230, filed January 6, 1977, and entitled "Inexpensive and Reliable Custom Programmable Phototypesetter".

The present invention relates to the field of phototype-setters.
Most phototypesetters pro~uced over the p~st decades employ rotatable font carriers which bear images of characters to be phototypeset. A flash lamp, under the control oP digital address circuitry, sequentially flashes selected character images upon the font carrier, to produce light images which are projected through an optical system to be focused upon a photosensitive material, such optical systems also employing means for changing the character image sizes. In the phototypesetting industry, such optical character si~e changing devices have employed relatively large quantities of moving parts, have been costly, and have been somewhat unreliable. While optical zoom systems have been em-ployed, relatively tedious manual adjustments of the position of the lenses with respect to their mounting devices have been re-quired during manufacture to compensate for lens parame~er ; variations with respect to the theoretically correct or target values. For example, variations in focal length have been com-pensated for, to maintain accurate focus, by mounting the lenses in a threaded sleeve which is rotated by the operator to produce fine changes in the lens position along the optical axis.
Furthermore, lenses have been mounted in oversi~ed apèrtures and their positions in the x and y directions lying in a plane .:

perpendicular ~o the optical axis (2 axis) have been adjusted by tapping in order to translate the lenses in the plane perpendicular to the optical axis, to reduce base llDe errors (vertical position-ing) and side of character errors (horizontal posit~oning), It is ~hus desirable to eliminate these tedious manual manipulations upon manufacture of the phototypesetters.
It is also desirable to employ a single stepping motor for actuating the scanning or escapement carriage and at the same time to employ th1s motor to actuate the lens carriages which must be moved along the optical axis with changes in character size, and additionally to employ this same motor to actuate a font disc ` track select ~arriage.
`~ It is furthermore desirable to provide a simple and reliable driving system for positioning these carriages with great accuracy and reliability and yet be 1nexpensive to manufacture. Further-more~ it is desirable to reduce manufacturing costs by mounting lenses into the phototypesetter having loose manufacturing toler ances, and which individual tolerance variations may be compen-sated for in the easy and rapid generation of digital positioning command codes which are customized for each particular machine during manufacture to eliminate the effect of such variations.

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In accordance with a preferred embodiment of the present invention, a single x stepping motor drives a scanning or .~

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escapement carriage along with a flat elongated driving member .
which in turn is electromagnetically and selectively coupled and decoupled to and from a projection lens carriage, a collima~ing lens carriage, and a track s~lect carriage. The flat upper sur-face of the drivlng member co-acts with flat lower clutch surfaces of the carriages to provide a sirnple and reliable system for accurately positioning such carriages in incremental fashion.
A size dictionary produces, for each partieular machine, sets of customi~ed focus position co~trol codes which position the lens carriages at particular positions along the optical axis to maintain focus regardless of lens tolerance variations. Custom-ized sizing codes alter the theoretically correct image positions to compensate for variations in lens positioning ~ith respect to the optical axis which effect side of character image position variations and character base line image position variations.
The latter two codes are employed to modify the stepping of the x and y motors, thereby to produce images having correct base line placement and side of character placement for all character - sizes. During manufacture, the aforementioned customized codes are generated by selecting tentative codes for initially position-ing the lens carriages and film placement in x and y and observing focus and image placement errors. The errors are eliminated by having the operator alter the positioning codes to shift the aforementioned positioning of film and lens carriages step by step until the errors are reduced to a satisfactory level or 7~L

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eliminated. The finally altered customized focus and sizing : codes are thereafter retained in permanent storaye in the type-setter control system and are thereafter employed to effect the above-mentloned positlonlng functions over the llfe o~ the phototypesetter. In acçordance with a further aspect of the invention, a unlque coupler is employed for positively drivln~
the elongated dr~ving member parallel to its longitudinal axis and which prevents binding of the driving member to the clutches after de-energization of the clutches to prevent the posslbility of unintentional shifting of the carriage pos1tions along the optical axis.

' -In the accompanying drawings, FIG. l illustrates the mechanical aspects of the preferred . embodiment;
FIG. 2 illustrates the electronic and control aspects of the present invention; and FIG. 3 illustrates the key element in the coupling member for lfnk1ng the Flat drive member to the escepement carrlage.

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: The photosensitive medium or film 1, which is to record the light images of the projected characters, is stepped by film feed stepping motor 2 in the Y direction, for each line to be recorded, which stepping is controlled by Y motor drive control circuit 3, . illustrated in Figure 1.
Flash timing trigger circuit~4 causes the illum;nation of a particular character formed upon rotatable font disc 6, which in , turn produces an image which is recorded upon film 1 by means of the optical system comprising stationary mirror 7, C lens 89 B
.~ lens 9, A lens 11, and mirror 12. An X motor drive control cir-cuit 13, controls the stepping of X motor 14, which in turn steps ~ escapement carriage 16 to sequentially record a line o-f ciharac-;~ ters across film ~edium 1. In other words, after a particular 15 character is flashed and recorded, the X motor 14 incre~entally : steps escapement carriage 16 to a displaced position in X to ` properly record the next adjacent character in the line being .~ recorded.
; It is an important feature of the invention to control the initial positioning of lenses 8 and 9, which positioning is d function of the image si7e to be recorded by means of a single X stepping motor, which also functions to step escapement carriage 16 to sequentially record letters in any particular ; line. This cost saving aspect of the invention is made possible .

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by selectively coupling and decoupling lens carriages 18 and 19 to and from drive rod 21, which is mechanically coupled to ~; escapement carriage 16. Drive rod 21 also actuatçs track (font) select carriage 22, which in turn positions font disc 6 in one of two positions to cause the twin concentric tracks containing separate font sets to be selectively illuminated by flasher 23.
Binary codes are also read off of disc 6 to enable selective character flashing as is known in the art. Mirror 7 is station-ary so that no change in the conjugate object distance occurs - 10 with changed tracks. The rotatable spindle, not shown, carrying rotatable font support means 6 is coupled -to track select car-riage 22 to effect the above-mentioned track selections. This coupling is scnematically illustrated by dashed llne 20. The ~ clutch control circuit 26 controls the energization of the B lens carriage clutch while the C clutch control circuit 27 controls the energization of the C lens carriage clutch. Central flux generating windings are positioned about the central legs of the clutches and are represented by the X's as illustrated.
Such a clutching arrangement also is employed in connection with the track select carriage 22. Tne clutch of carriage 22 is con-trolled by track selector circuit 28.
Broadly speaking, energizing the B and C clutches causes them to ~ecome tightly coupled to the drive rod, and the clutch energizing intervals are individually controlled while escapement 9~

carriage 16 drives rod 21 to selectively position lenses 8 and 9 at predetermined positions which are a function of the desired size of the character to be recorded on film 1. ~lso, the track select carriage 22 is ~riven, during energization of the carriaye clutch 25, by drive rod 21 for track setection. A low cost means of generating variable size output characters is thus provided by elnploying a ZOOIIl system in which the lenses are positioned by a very simple inexpensive and re~liable technique in contrast with the prior art approaches. A simple and reliable means of selecting a particular track of a multitrack font character also results in the above-mentioned structural arrangement. Besides ; the above-mentioned positioning functions, the single X motor steps the escapement carriage mounted mirror "across" the film to form a line of characters. At the end of a line, the Y film 1~ stepping motor 2 is stepped to feed the fi1m in tne Y direction a predetermined distance and the escapement carriage is reset to set the stage for recordation of a subsequent line. As will be explained in greater detail hereinafter~ the X position of the escapement carriage and the Y position of the stepped film will 2C be modified for varying size changes in the characters to be image positioned on film 1 in order to insure that the charac-ters are FJrojected at the proper position within each character field so that even, aesthetically correct, lines of characters are recorded, regardless of character size changes.
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~ 9~74 An important additional aspect of tlle invention explained below is to individually calibrate the lenses fitted into each machine, for manufacturing to1erance variations, and to modify the "size focus" and "image position" command codes in the dictionary to account for the individual variat~ons, thereby - to save in the cost of manufacturing the phototypesetters.
Figure 2 schemetically illustrates the various electronic control functions, which controi the component actuating devices described above in the description of Figure 1. The control circuit designations of Figure 1 have their counterparts iden-tified with like primed designations in Figure 2. For example, B clutch control circuit 26 of Figure 1 is designated as B
: clutch control circuit 26' of Figure 2.

INITIAL POSITIONIi~G OF THE CARRIAGES

The phototypesetter of the present invention is operated by virtue of a program, which is loaded into an input unit 31 iilustrated at the top of Figure 2 and which may consist of a magnetic tape which contains digital information recorded thereon whicl~ commands the phototypesetter with respect to format, char-acters to be generated~ the particular font of the characters to ~: be generated and their sizes.
A timin~ programmer is schematically represented by block 329 which contains circuitry for carrying out certain sequencing steps . .

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performed in the phototypesetter. Upon commencement of the operation, it is first desired to drive lens carriages 18 and l9 to their extreme left-hand positions against stops lO and lOI, lllustrated in Figure l, to position theln in the home position. This is effected by a command from programmer 32, which causes the X motor drive circuit 13 to step the carriage 16, and hence, drive rod 21 to the left. At the same time, .~ clutch control circuits 26 and ~7 are activated by proyrammer 32, so that the stepping of drive rod 21 transports carriages 18 and l9 against stops 10' and lO respPc-tively. Escapement carriage 16 and hence drive rod ~1 is driven a substantial distance, . whicll is larger th~n the maximum possible displacement of any of the carriages from their stops, to insure carriage positioning against the stops. The flux density induced in the legs of the carriage clutch E cores is of a magnitude to cause the drive rod 21 to be positively "grabbed" by the lens carriage clutches to insure transportation of them parallel to the optical axis 5 - However, the flux intensity is of a magnitude which permits slippage of the drive rod ~1 when the carriages are positioned

2~ against the stop elements. The drive rod 21 is rectangular in .: shape and ha~ a flat machined -top surface 34 slidable withrespect to the flat surfaces of the ends of the c1utcn legs 36.
In the actual phototypesetter constructed by the inventor, . ~our separate pie-shaped font segment carriers were employed as .

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explained in u.~. Patent No. 4,118,711, datea - October 3, 1978, in the names of Peter R. Ebner and Louis E. Griffith assigned to~the same assiynee of record.
However, in order to simplify the explanation of the present invention, it will be assumed that font disc 6 is a unitary disc having two tracks thereon wherein each track contains a particular font although a larger number of tracks may be provided. A font code will be transmitted -from input device 31 to cause track selector 2~' to energize clutch 25 of the track select carriage 22 to cause it to properly position the ~ont disc 6 with respect to the optical axis of the device upon being actuated by drive rod 21. The code transmitted to track selector cantrol circuit 28 in the simplest two track case, causes the track select carriage clutch 25 to be energized together with transmitting a forward or reverse signa1 to X motor drive circuit 13' to simul-taneously step drive rod 21 to the left or right against stop 10" or 10"'-.
A dictionary 42 is addressed by a code transmitted from input unit 31 indicative of a particular desired character size (or in the absence of a desired size an automatically called for standard size) to be projected UpOIl photosensitive film 1. The dictionary, upon being addressed by a code indicative of a particular character size, generates a B lens position code and a C lens position code which is inserted into B lens position ~.
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control circuit 43 and C lens position control circuit 44 respec-tively. Like the remaining components schematically illustrated in Figure 2, the size dictionary could take the form of hardware such as an array or read only memory cores~ or could take the forln of a magnetic tape program, as is understood by those skilled in the data processing art. In a similar manner, the information fed from input unit 31 could all be read off a magnetic tape, or some of the information could be directly encoded by a keyboard matrix.

CUSTOM FOCUS AND SIZING C~RRIAGE POSITIONING
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The next step is to properly position lens carriages 18 and 19 away from their above-mentioned home positions so that a sharp aerial image 46, shown in Figure 1, is produced at the focal length of lens 9 and of the proper size for the called for char-1~ acter size recordation. Programmer 32 commands X motor drive circuit 13' to cause drive rod 21 to be displaced to the right while the comlnands from the lens position control circuit 43 and 44 to clutch control circuits 26' and 27' respectively cause the clutches of lens carriages 19 and 18 to be energized until the count in the control circuits 43 and 44 reach a value indica-tive of the desired position of the carriages. Since the details of circuit operations to produce these results are obvious to the worker in this art, specific explanation will not be given ~ Q ~7 ~

since numerous modes may be employed. For example~ the dictionary produced codes representing the target X positions may be inserted into counters which are counted down by tne pulses which indirectly step escapement carriage 16 until they reach a predetermined value such as zero, which value is detected by a logic circuit, to in turn cause de-energization of the lens carriage clutches. Each lens carriage 18 and l9 is simultaneously stepped until one is properly positioned and the other continues to be stepped until it is properly positioned.
Dictionary 42 also inserts a code into Delta X image position control circuit 46 and a Delta Y "leading" image position control code into control circuit 47. The function of these signals will be explained hereinafter.
A series of codes, each of which is indicative of a desired character to be projected along optical axis 5, is transmitted from input unit 31 to letter select circuit 49, which controls the instance of triggering of the flashing illumination source 23 for character selection. The manner in which the character selection codes cause flashing of the disc track portions for character selection as the font disc is rotated is well known ;~ to those skilled in the art in connection with so-called second generation phototypesetters. Broadly speaking the addressing letter select code is sequentially matched in rapid order against binary letter codes, physically associated with the characters, 7 ~

and read off of the disc, and when a match occurs, the lamp is flashed at a time corresponding to the instant when the selected character is at the optical axis. The escapement carriage is thereafter stepped in preparation for projection of the next character.
The alignment table stored within size dictionary 42 also produces image position modification codes having values which are a function of the character size to be set. It is well known in the art, that si~e changing of character images sym-metrically about the optical axis is completely unsatisfactory, since the horizontal character base line, for example, would be altered with changes in the image size. Likewise with respect to the position of the side of the character field block. In other words, each character occupies an imaginery character field which can be visualized as a rectangular grid, the lower left-hand corner of which must always assume the same position regardless of changes in grid and hence character size. In accordance with tnis requirement, a change in character size must be accompanied by a Delta X image position control command, : 20 which modifies the X position of the escapement carriage ~6;
likewise with respect to a change in the image position in the Y direction, which may be thought of as a change in "leading,"
analogous to the insertion of horizontal lead strips having various vertical dimensions for various character sizes employed '~
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in first generation typesetters, where the letters are-composed . by the mechanically positioning of lead blocks. Tnus, a signal is generated by Delta X image position control circuit 46, which modifies the escapement carriage X position by altering the number of impulses which would otehrwise be produced by X motor drive control circuit 13', In like manner, the number of impulses produced by Y motor control circuit 3' is modified by the Delta Y
leading image position code retained in control circuit 47 to alter the final film feed positioll in Y. Thus, the size dic-tionary 42 generates two codes for focusing purposes and two codes for alteration of image position to maintain uniforlnity of format with changes in type size.
It is an important feature of the present invention that the particular code values inserted into circuits 43, 44, 46, and 47 discussed above are a function of the particular lens parameters of each particular nlachine. Since these values are preferably stored in a read only memory~ they will not be . altered or erased over the life of the machine. Manufacturing costs are considerably reduced since particular B and C lenses are inserted into a particular machine, and the carriages are thereafter positioned at whatever positions in X which produce sharp images in each of the desired character sizes. These particular positions in X (custorn focus codes) are thereafter inserted into the read only memory of size dictionary 42, which ., .. . . . ...... . , . ~ .. , . . __ .... _ .. .. _.. _ __ . . ....... .

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properly positions the carriages over the liFe of the machine at positions that generally differ somewhat frorn the positions ~ which would be assumed by ideal lenses having theoretically - "correct" focal lengths. In like manner, a CUStOIII CalibratiOIl of the actual lenses inserted into each machine is carried out so that custom sizing code values for the Delta X image position control and the Delta Y "leading" image position control are generated and are also inser-ted ~into the read only memory for each desired character size. The latter two values for each letter size are designated as "custom sizing" values while the former two values for each letter size are designated as "custom focus" values. These customized individual sets of va1ues associated with each letter size comprise the alignment table of dictionary 42. In surnmary, these values wil1 be determined for each machine and stored in a programmable "read only" memory circuit. At the time of manufacture, this technique will permit ~ focusing and si7ing to be properly accomplished rapidly and ;~ accurately on a custom basis taking into account lens parameter variations.
If desired, a variable flash intensity code may be stored within the size dictionary 42 for each character size to maintain exposure at film 1 constant, regardless of variations in the character size. The conversion of the flash intensity codes into varying signals to produce varying flash intensities form no part of the Present inventi~n. As may be seen from perusal L~, o ~
of U . S . Patent No . ~
in the names of Peter R Ebner and Louis E. Grif-fith, dssigned to tlle same assignee of the présent invention, the digital flash s intensity codes may be converted into flash lamp activating charges having energies associated therewith which are a function of the value of the flash intensity codes.
The system of Figure 1, causes lenses 8 and 9 to be positioned so that the aerial image 46, regardless of its size, is always at the focal point of lens 9. Once the positions of lenses ~ and ; 9 are assumed, they remain in those positions until a change is made in the character size. The above-mentioned positioning of aerial image 46 at the focal point of lens 9 means that the light - rays between lens 9 and lens 11, mounted on escapement carriage 16, will be collimated light so that the final projected image will remain in focus as the carriage is stepped along in X to record a line of characters.
- As a result of this mechanical organization, it should now be appreciated that a single stepping motor performs a number of positioning functions with regard to the optical elements of the system, and at the same time, is able to record a sharply imaged line of characters across the width of the recording medluln, At ihe end of the line, the programmer actuates the Y motor control circuit 3' to advance the film in preparation of the recordation ~ g~7g - of the subsequent line of characters and resets the escapement carriage 16. When the input unit 31 instructs the phototype-setter to chanye character size, the carriages may be again actuated to the left against the stop elements, in the home position as described above, and storage elements associated with control circuits 43, 44, 46, and 47, retaining the custom focus values and the custom sizing values, may he cleared in preparation of the receipt of a new set of values from size dictionary 42 corresponding to the new charaçter size, and the entire process explained above is repeated. In the alternative, a running count of these positioning values may be retained and alternated by new sizing data in accordance with techniques well known in the data processing art, tnereby to eliminate the posi-tioning of the carriages back to the initial home positions until the machine is shut down.

DRIVE ROD COUPLER
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As mentioned hereinabove, the track select carriage, projection lens carriage, and collimating lens carriage are mechanically coupled and decoupled to a rectangular drive rod 21 having a ~.
2l) smooth flat surface which slides past the flat surfaces of the E
clutches when they are not energized and which are in tight face-to-face contact with the faces of the clutches when they are energized. In the interest of smooth and accurate operation 1 ~

with the employment of reasonat)le quantities of flux to effect ade4uate "grabbing" of the clutches, it is desirable to prevent translation in space of the drive rod to alter the degree of separation or contact ~orces between the drive rod and the clutch faces. In FIG. 1, the drive rod is shown rigidly coupled to the escapement carriage. In practice this is deemed undesirable since shifting of the unitary body including both the carriage and drive rod could produce undesirable shifts in -the position of the lens carriages even though the clutches are deactlvated.
Accordingly, a special coupler has been provided to prevent the possibility of these occurrences.
In FIG. 3, a segment of a piano wire 56 is rigidly coupled between drive rod 21 and a terminal portion of escapement carriage 16. Drive rod 21 is supported by at least one rotatable wheel 57. The piano wire may be detachably coupled to carriage 16 by means of a clamp such as 58. Ordinary piano wire having a free length of 1" and having a diameter of 1/16" has been employed and provides positive driving of drive rod 21 when in both tension in the pulling mode and compression in the puslling 2~ mode. At the same time, the drive rod has two degrees of free-dom perpendicular to its longitudinal axis, which degrees o~
freedom are ~epresented by arrows 61 and 62. As a result oF
this arrangement, inadvertent lens position shifts do not occur during deenergization of the clutches.

CUSTOMIZ~D PVSITI~NING C~D~ ALTE'RATIONS ~RI~G

MANU~C~VR~ ~O~ EACH INDIVID~AL PHOTOTYPESETT~R
_ __ _ _ __ _. . . _._ __ _. _ A .. . ~__ 1 Lens positioning adjustments in accordance with prior art approaches, employ devices and techniques for making minute changes ln the spatial positioning of the lenses with respect to the optical axis manually. For e~ample, adjustments of the lenses along the optical axis in the z direction have been manually accomplished by turning a finely threaded screw associated with a lens mount sleeve, which in turn produces minute changes in the lens position in z to obtain sharp focus for individual lenses having varying focal lengths due to manufacturing tolerances. The manual adjustment of such threaded member is eliminated in accordance with the present .
invention, since the lens carriages are initially positioned at the theoretically correct position along the optical axis by initial position command codes stored within the carriage position command control system which produce such initial carriage positions. The sharpness of the image i9 ; inspected by an operator under a microscope and the initial ~- 20 .. .... _ _ . .. _ _ _ . . . ..

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position code is sliyhtly alterecl in value by an incremental change code keyboarded into the control command input tape of the carriage position command control system by the operator and the carriage position is accordingly slightly changed. The image is reinspected, and the process is repeated until a sharp character.
is produced. The altered initial theoretically correct position code now becomes the final positioning command code, which has a customized code value for the particular machine have the partic-ular "loose tolerance" lens therein. As discussed hereinabove, customized sizing codes are generated for each particular machine, one of wt)ich is the delta x position control code for altering the theoretical escapement carriage position and thus relative image position in the x direction and the other is the delta y leading image position code which alters the initial. theoretically correct 15 y positioning of the film feed and thus the relati~e image position-ing in y. One typical prior art approach, in order to eliminate base line (y) errors and side of character positioning (x) errors>
which are corrected by the delta y and delta x codes respectively, involves mounting the lenses within oversize apertures and tapping the lenses in x and y directions perpendicular to the optical axis, thereby to translate the lens in space in a plane perpen-dicular to ~he optical axis until the above-mentioned base line errors and side of character errors of the projected image of various character sizes are substantially eliminated. With the .. . .. _ _ _ _ _ .. _ . . . . . . _ . .. .

above-described techniques involving slight alterations of custom sizing codes for altering the positioning of the x and y motors, these tedious manual mdnipulations are eliminated. The procedure is similar to the trial and error Focusing technique descri~ed above in connection with inspection of the characters under the microscope. More specifically, a print-out on the developed film is inspected and the base line errors for each character size are determined by visual inspection.
An incremental code change is keyboarded into the command tape program and the theoretically correct y position code is slightly altered, which sends a signal to the y motor drive con-trol circuit to step the y motor a particular increment and the process is repeated to correct the final base line position.
In like manner, variations in the positions of the sides of the characters for the various character sizes are eliminated by alterin~ the theoretically correct x position code so that the final position of the escapement carriage is altered. This procedure is repeated for each character si~e. Thus, these highly flexible steps may be carried out by an unskilled operator, in contrast to the above-mentioned manual techniques by relatively skilled personnel, thereby to effect considerable savings in the cost of manufacture of the typcsetters. Also, loose lens toler-ances reduce manufacturing costs and very accurate results are attained since each machine increment is defined by a single step ?S of the x and y stepping motors of only .002''.

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Claims (14)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A phototypesetter comprising:
a. an imaging station;
b. an elongated scanning carriage having optical means thereon for sequentially projecting optical images across said imaging station upon the incremental movement thereof;
c. an elongated driving member;
d. coupling means for coupling said elongated driv-ing member to said elongated carriage;
e. an x positioning stepping motor coupled to said first elongated carriage for incrementally driving said first el-ongated carriage and thus said elongated driving member;
f. a movable character generating member having character indicia thereon;
g. illumination means for sequentially illuminating selected character indicia carried by said character generating member;
h. a first lens carriage having a first lens means coupled thereto for producing images of said characters;
i. a second lens carriage having second lens means coupled thereto for relaying said images to said optical means mounted upon said scanning carriage;
j. lens carriage positioning means including clutch means for selectively coupling and decoupling said first and second lens carriages to and from said elongated driving member;
and k. character generating member actuation means for selectively shifting said character generating member for causing indicia tracks associated therewith to be selectively viewed by said first lens means without changing the conjugate object dis-tance of said first lens means, said character generating member actuation means including clutch means for selectively coupling and decoupling said actuation means to and from said elongated driving member so that a single x positioning motor may be em-ployed for selectively positioning a plurality of lens carriages and said character generating member.

2. The combination as set forth in claim 1, wherein said elongated driving member has a flat surface which is slid-able with respect to said lens carriages and said character generator actuating means to provide for selective driving of individual carriages.

3. The combination as set forth in claim 2, wherein said character generating member comprises a radially shiftable rotatable disc bearing character indicia.

4. The combination as set forth in claim 1, further including:
a. a y stepping motor for feeding film in a direction traverse to the longitudinal axis of said escapement carriage;
b. a y motor control circuit for stepping said y motor after the completion of a line of characters;
c. delta x image position control means for causing said x positioning stepping motor to modify the degree of escape-ment movement between characters to command proper custom sizing in x with changes in character sizes; and d. delta y image position control means for causing said y motor to modify the degree of film feed movement between lines of characters typeset, to maintain proper custom sizing in y.

5. The combination as set forth in claim 1, wherein said character generating member actuating means comprises a track select carriage coupled to said character generating member together with a track select carriage clutch for coupling and decoupling said

6. The combination as set forth in claim 2, wherein said character generating member actuating means comprises a track select carriage coupled to said character generating member to-gether with a track select carriage clutch for coupling and de-coupling said track select carriage to and from said elongated driving member.

7. A phototypesetter comprising:
a. an imaging station;
b. an elongated scanning carriage having an imaging lens and an optical scanning element coupled thereto;
c. an elongated driving member;
d. coupling means coupled between said elongated scann-ing carriage and said elongated driving means;
e. an x position stepping motor for incrementally driving said scanning carriage and thus said elongated driving member;
f. a rotatable character generating disc;
g. flash illumination means for selectively illuminating images of characters upon said disc;
h. a projection lens carriage having a projection lens coupled thereto for producing aerial images of said characters;
i. a collimating lens carriage having a collimating lens coupled thereto for converting said aerial images into colli-mated light directed at said imaging lens coupled to said scanning carriage;
j. character disc actuation means for radially shift-ing said character disc for causing selected tracks upon said disc to be viewed by said projection means without changing the con-jugate object distance of said projection lens;
k. projection lens carriage clutch means for coupling and decoupling said projection lens carriage to and from said elon-gated driving member;
1. collimating lens carriage clutch means for coupling and decoupling said collimating lens carriage to and from said elongated driving member;
m. x motor drive control means for causing said x stepping motor to drive said scanning carriage and said elongated driving member;
n. projection lens positioning control means for actuating said projection lens carriage clutch means for mechan-ically coupling said projection lens carriage to said elongated driving member and for causing said x motor drive control circuit to actuate said x stepping motor to position said projection lens carriage at a position along said optical axis to produce an aerial image of a selected size; and o. collimating lens positioning control means for act-uating said collimating lens carriage clutch for coupling said collimating lens carriage to said elongated driving member and for causing said x motor drive control circuit to actuate said x stepp-ing motor to position said collimating lens at a distance from said aerial image to collimate said aerial images so that said aerial images are focused at the imaging plane of said imaging station by said imaging lens regardless of the varying distances between said collimating lens and said imaging lens.

8. The combination as set forth in claim 7, further including:

a. a y stepping motor for feeding film in a direction traverse to the longitudinal axis of said scanning carriage;
b. a y motor control circuit for stepping said y motor after the completion of a line of characters;
c. delta x image position control means for causing said x positioning stepping motor to modify the degree of escape-ment movement between characters to maintain proper custom sizing in x with changes in character sizes;
d. delta y image position control means for causing said y motor drive circuit to modify the degree of film feed move-ment between lines of characters typeset to maintain proper custom sizing in y.

9. The combination as set forth in claim 7, wherein said elongated driving member has a flat surface which is slidable with respect to said lens carriages and said character generator actuating means to provide for selective driving of individual carriages.

10. The combination as set forth in claim 7, wherein said character generating member comprises a radially shiftable rotatable disc bearing character indicia.

11. The combination as set forth in claim 8 wherein said elongated driving member has a flat surface which is slidable with respect to said lens carriages and said character generator actuating means to provide for selective driving of individual carriages.

12. The combination as set forth in claim 8, wherein said character generating member comprises a radially shiftable rotatable disc bearing character indicia.

13. The combination as set forth in claim 7, wherein character generating member actuating means comprises a track select carriage coupled to said character generating member to-gether with a track select carriage clutch for coupling and de-coupling said track select carriage to and from said elongated driving member.

14. The combination as set forth in claim 8, wherein said character generating member actuating means comprises a track select carriage coupled to said character generating member together with a track select carriage clutch for coupling and decoupling said track select carriage to and from said elongated driving member.