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Publication numberUS3553676 A
Publication typeGrant
Publication dateJan 5, 1971
Filing dateJan 30, 1968
Priority dateJan 30, 1968
Also published asDE1904621A1
Publication numberUS 3553676 A, US 3553676A, US-A-3553676, US3553676 A, US3553676A
InventorsRaciti Salvatore A
Original AssigneeRca Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electro-optical composition system
US 3553676 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Jan. 5, 1971 s. A. RAclTl 3,553,675

' ELECTRO-OPTICAL COMPOSITION SYSTEM Filed Jan. 30, 1968 2 Sheets-Sheet 2 v POINT SIZE 76 35 nlln M IN VEN TOR SALVAToes A. RAe/'n MTU/JMW ATTORNEY United States Patent Oice 3,553,676 Patented Jan. 5, 1971 U.S. Cl. 340-324 11 Claims ABSTRACT OF THE DISCLOSURE An electro-optical composition system includes an electro-optical imaging device, such as a cathode ray tube, that forms patterns, such as characters of given point sizes, by a plurality of successive scanlines that create character slices. Characters of a high graphic quality are created by utilizing a predetermined number of scanlines at predetermined spacings from each other. Proof copies of text material are printed by reducing the number of scanlines utilized to form the individual proofing characters so as to increase the speed at which such proof copies are formed. To insure that characters of a proofing quality occupy the same areas as corresponding characters of a high graphic quality of the same point size, the spacing between adjacent scanlines in the proofing characters is increased.

BACKGROUND OF THE INVENTION Mechanical and photographic techniques of composing type are relatively slow and the probability of increasing the speech of such type composition systems, by a significant amount, appears to be small. The successful transformation of type composition into an electronic art promises to increase greatly the speed of type composition. Recently, electronic photocomposition systems have become commercially available. One such system utilizes an imaging device, such as a cathode ray tube, to create characters by a plurality of adjacent scanlines that form slices of the characters. A memory is incorporated into such electronic photocomposition systems to store instructions as to when the cathode ray tube should be blanked and unblanked to provide the character slices at the right times. The characters so formed on the cathode ray tube are imaged onto photographic film for later processing into printing plates.

To provide characters ofa high graphic quality eX- hibiting uniform density, a relatively large number of overlapping scanlines may be utilized. The formation of such characters takes a relatively long time. Frequently, material is desired to be obtained at a much faster rate, as for example in proofreading, in page makeup, etc. In such operations, characters of a lower graphic quality may be perfectly satisfactory so long as they can be obtained relatively fast.

SUMMARY OF THE INVENTION An electro-optical composition system embodying the invention includes an imaging device for creating patterns, such as characters of given point sizes, by a plurality of adjacent scanlines that form slices of the patterns. Character patterns of a high graphic quality are formed by a predetermined number of scanlines at predetermined spacings. Means are coupled to the imaging device for reducing the number of scanlines to provide characters of a proofing quality. Means are also provided for increasing the spacing between adjacent scanlines in said proofing characters so that corresponding characters of the same point size of both graphic and proofing qualities occupy the same area.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic block diagram of an electronic composition system embodying the invention,

FIG. 2 is an illustration of the formation of a character by the system of FIG. 1, and

FIG. 3 is an illustration of the formation of a character of a proofing quality.

DETAILED DESCRIPTION Referring now to FIG. l there is shown a system 10 embodying the invention. The photocomposition system 10 includes an imaging device 12, such as a cathode ray tube, that creates patterns, such as the characters 14 on the face 16 thereof. yIt is to be noted that the cathode ray tube 12 may also create other patterns such as line drawings, and the invention described herein is also applicable to such patterns. The cathode ray tube 12 includes an electronic scanning beam 18 that emanates from the cathode 20 in the electronic gun section (not shown) of the tube 12. The scanning beam 18 is deflected by horizontal and vertical deflection coils 22 and 24 that surround the neck of the tube 12. The scanning beam 18 creates a scanning spot 26 that forms the patterns in the phosphor on the face 16 ofthe tube 12. The light emanating from the phosphor in the tube 12 is focused by a lens system, shown as a single convex lens 28, in FIG. 1, onto a photosensitive recording surface such as high gamma photographic film 30. The photographic film 30 is supported in the focal plane of the lens 28 between a pair of reels 32. The reels 32 are coupled to be driven by a drive motor 34 to a new line after each line of character patterns has been formed on the film 30. The cathode ray tube 12 and the other components in the light sensitive portion of the system 10 are enclosed in the light-tight compartment (shown dashed in FIG. 1) having access doors (not shown) for changing and removing the film 30.

An enlarged View of a character 14 that is formed by the system 10 is shown in FIG. 2. The character 14 comprises a capital H of a given point size from a sans serif font. The capital H, as well as all of the other characters and patterns created by the photocomposition system 10, are formed by a plurality of black vertical segments 36. The segments 36 are character slices that comprise portions of the scans or scanline when the electron beam 18 in the tube 12 is unblanked. A scan or a scanline is one vertical traversal of the face 16 of the tube 12 by the scanning beam 18, of course horizontal scanning may also be utilized in practicing the invention. Those portions of the scans wherein the electron beam 18 is blanked are white segments 38 and representative ones are shown dashed in FIG. 2. In the cathode ray tube 12 itself, the black segments 36 are actually white on a dark background whereas the segments 36 are shown dark on a light background in FIG. 2 for illustrative purposes. In characters of a high graphic quality, the black segments 36 overlap each other and are selected to be numerous enough such that a character of a substantially uniform density is formed on the photographic film 30. For convenience, only twenty character slices are shown for the character H in FIG. 2, although in actuality eighty character slices may be utilized. The capital H is seated on a character baseline 37 and ascends above this baseline a predetermined amount as determined by the point size of the character. A point size twice as great as the given point size of the character H comprises a character twice as high and twice as wide as the character H in FIG. 2. The inverse is true for a character one half the point size of the character H, etc.

Each character in a font of characters is defined by a set of parameters that includes an EM square 41, shown dashed in FIG. 2. The EM square defines the point size of the character. The body size or the overall set width of the character is equal to the sum of the character Width 43 (CW) and the leading 44 and trailing `45 side bearings of the character. The leading side bearing 44 (LSB) is defined as the distance from the leading or left outer periphery of the character to the leading end of the set width of the character. Similarly, the trailing side bearing 45 (TSB) is defined as the distance from the right edge of the character to the trailing end of the set width of the character. One character is spaced from another character by the sum of the trailing and leading side bearings of the respective successive characters. For characters of a high graphic quality the values of the leading and trailing side bearing for the capital H may compirse seven scans each, with the character width 43 comprising 80 scans.

The parameters of a character as fell as other data to be described below are stored in a memory shown in FIG. 1. The memory 50 may for example comprise a magnetic core random-access memory that is divided into two main portions, a primary portion 52 and a secondary portion 54. The primary portion 52 includes a plurality of successive storage locations that correspond one-toone with the characters and other symbols and marks in a plurality of type fonts. Each multi-bit storage location in the primary position 52 is addressed by a character code which may for example comprise a binary number that is a coded representation of the character. The sequence of the addresses of the storage locations in the primary portion 52 of the memory may begin at capital A and continue through capital Z and then into lower case a, etc. until the end of the first font. Such a font may be termed a high graphic quality font. Immediately thereafter a second font of a proofing quality may be stored in a manner identical to the first font. It is assumed for purposes of this disclosure that only two fonts, a high graphic quality font and a proofing font are stored in the memory 50.

The contents in each one of the primary locations of the memory 50 is actually an address for the location in the secondary portion of the memory which stores the first of the coded parameters that define the corresponding character. Thus when the character code is utilized to address the character in the primary portion of the memory 50, the number read from the memory provides a secondary address for the secondary portion of the memory 50 that begins a block of secondary address locations wherein the coded parameters of the character are stored successively. The advantages derived from such an arrangement in the memory 50 is that identical letters in each font have the same character code. Thus the same character in two different fonts has the same character code but the character code of the character in the second font is incremented by a fixed number to arrive at the address of the character in the primary portion 52 of the memory 50. This is so because the fonts are stored in sequence and in the same progression from A to Z etc. Of course each font has different secondary addresses.

The secondary portion of the memory 50 stores in sequence the blocks of information necessary to create a character pattern on the cathode ray tube 12. The contents of the first memory location for a block of data in the secondary portion y54 is a coded representation of the number of scans in the leading side bearing (LSB) of the character. The contents of the next successive location is a coded representation of the sum of the number of scans in the character width (CW) and the trailing side bearing (TSB) of the character. The next format data stored in the next location is the number of scans in the character width. For the sake of simplicity, it is assumed that all characters begin at the same baseline. The next data stored in the block is not format data but rather the segment data which are the successive coded representations of the lengths of the individual black segments and the individual white segments in each scan of the character. Thus, each of the lengths of the black segments 36 in the left upright strokes of the character H in F-IG. 2 would be stored. For example, one word of binary data may be stored for each black segment 36. The lengths of the White segment 38 and the black segment 36 for each scan in the center portion of the character H are then stored. One word of binary data for each white segment and one word for each black segment 36 may be utilized to store these lengths. Finally, the binary Words representing the right upright strokes of the character H would be stored, completing the entire character.

To attain synchronism between the scanning beam 18 and reading the memory 50, the stored segment words also include data relating to the start and retracing of the scanning beam 18, as well as to blanking and unblanking it. The least significant bit in a binary word for a black segment 36, i.e. the 20 bit, may be selected t0 designate the end of a scan. No white segments terminate a scan because the scanning beam 18 is retraced after finishing the last black segment in a scanline. Thus when a black segment includes a binary l in this 20 bit position, it signifies that this black segment is the last black segment in that particular scan. A binary 0 occurring in the 2 bit position in a black segment indicates that at least one more black segment occurs in the particular scan. The bit in the 20 position not only determines when a scan ends but, as will become more apparent later, also determines when the scan begins. Thus to sum up, the scanning beam is retraced when a binary "l occurs in the 20 bit position of a black segment.

The next least significant bit in the segment words, i.e. the 21 bit indicates when the scanning beam should be turned on (i.e. unblanked) and when the beam should be turned off (i.e. blanked). When a binary "1 is stored in this position the beam is turned on and when a binary 0 is stored in this position, the beam is turned off. Thus the black segment words are differentiated from the white segment words by the binary bit stored in this 21 bit position. It is therefore apparent that the segment words themselves control the scanning out or forming the character slices.

The secondary portion of the memory 50 that contains the blocks of data for the font of a high graphic quality requires more storage locations than the portion that contains the blocks of data for the font of a proofing quality. This is apparent from comparing FIG. 2 to FIG. 3 wherein a proofing quality character H is shown. Only ten scans may be required to form the latter character as compared with the twenty scans required to form the character in FIG. 3.

Referring back to FIG. 1, a magnetic tape 60 that contains editorial and text data is read by a tape reader 62. The data on the magnetic tape includes not only the text material to be printed by the system 10, but also the necessary instructions for justifying and hyphenating the material. The data on the magnetic tape 60 also specifies the point size of the characters to be created, the granularity of the characters and the type font to be utilized. Granularity is defined as the number of character scans per EM square. A high granularity species a font of high graphic quality whereas a low .granularity specifies a font of a proofing quality. All the data that relates to a character to be printed is read from the tape 60 by the tape reader 62 and stored in an input buffer register 64. The tape reader 62, after reading data from the tape 60 into the register 64, generates a start pulse to trigger the start of a timing control circuit 70 to start the transfer of data into and through the system 10. The timing control circuits 70 are standard timing circuits for providing the necessary trains of timing signal pulses (TP) for transferring data into and through the system 10. The timing pulses TP are subscripted sequentially in accordance with the time of their generation, i.e. TP1 is first,

TPZ is second, etc. To create the timing pulses, clock pulses from a clock oscillator 128 may, for example, be applied to a plurality of one-shot multivibrators to produce a series of successive timing pulses that are selected to transfer data into and through the system 10. Delay lines are coupled to the multivibrators to delay selected pulses. Additionally, the memory subsystem 51 and all of the remaining circuits to be described are standard circuits and hence will not be described in detail. A first timing pulse TPI causes the buffer register 64 to apply the coded representation of the point size of the characters through transfer gates 71 to a point size or spacing control register 73. It is assumed that all data is transferred in parallel throughout the system and hence there is one transfer gate for each bit in the data transferred. In the drawing all direct timing pulses are labeled TP for convenience and delayed timing pulses are labeled TPD. A second timing pulse TF2 shifts the coded representation of the granularity of the characters into the output stages of the buffer register'64 and a third timing pulse TF3 shifts this data through the transfer gates 75 into a granularity register 77. A fourth timing pulse TF4 shifts the character code into the output stages of the buffer register 64 and a fifth timing pulse TF5 shifts the character code through transfer gates 66 directly to an address register 68 in the memory subsystem 51 when a character of the high graphic quality font is to be printed. When characters from the proofing quality font are to be printed, the buffer register 66 causes an incrementer 67 to increment the address in the register 68 by a fixed amount to the address of the corresponding character in the proofing font. The tape reader 62 also transmits a command to the drive motor 34 to position the film 30 for a line of print. A sixth timing pulse TPG shifts the character code in the address register 68 through transfer gates 72 into an X-Y decoder 74. The contents of the memory 50 location selected by the decoder 74 are read out through read gates 76 by a seventh timing pulse TF7 and into a data register 78. The data register 78 immediately rewrites the data read from the memory 50 back into the same location of the memory 50 by means of write gates 80 under the control of a timing pulse TPqd, which is the delayed timing pulse TPq. In all operations to be described in the disclosure, the timing pulse that creates each read operation is delayed to provide a write operation so as to prevent the destruction of the data read out of the memory 50". The data in the data register 78 is transferred through transfer gates 82 by the action of a timing pulse TPB to the address register 68 because the first data read from the memory 50 in printing a character is the rst address in the secondary portion of the memory 50 of the block of data that defines the character parameters needed to create the character on the imaging device 12. The secondary address is coupled through transfer gates 72 by the timing pulse TPg and a delayed timing pulse rewrites the data back into the memory 50. The data is then read into the data register 78 through read gates 76 by timing pulse TPM). Thus the secondary portion of the memory 50 is addressed and is read successively.

The first data read from the memory 50 in the block of character parameters stored in the secondary portion of the memory 50 is a binary number representing the leading side bearing (LSB) of the character. This data is coupled through the transfer gates 84 by the timing pulse TPH into a binary adder 86. The binary adder 86 adds the contents of the data register 78 to the contents of a register 90. The register 90 stores the sum of the character width (CW) and the trailing side bearing (TSB) from the previous character. The sum of the data in the register 78 and the sum of the data in the register 90 is the horizontal position of the start of the new character to be created on the imaging device 12. The sum derived by the binary adder is added to the contents of an accumulator 87 so that the accumulative position of the beginning of the scans of each character is known, as the characters are printed on the photographic film 30.

As the data is read out of the register 78, an incrementer 79 increments by one the address register 68 to the next successive address in the secondary portion of the memory 50. The purpose of the dashed AND gate '69 coupled to the incrementer 79 as well as the other dashed components in FIG. 1 will be described subsequently. The data contained in this next successive secondary address is a binary number representing the sum of the character width (CW) and the trailing side bearing (TSB) and this address is read into the decoder 74 by a timing pulse TP12 applied to the gates 72. This data is read out of the memory by a timing pulse TP13 applied to the read gates 76 and transferred through the gates 88 by a timing pulse TPM to the register 90. The new contents of the register 90 remain therein until the next character is read and then the binary adder 86 adds these contents to the leading side bearing (LSB) of the next character. This sum specifies the position to which the scanning beam must be jumped at the end of scanning one character to the beginning of the scanning of the next successive character.

The accumulated total stored in the accumulator 87 is transferred through transfer gates 92 by a timing pulse TPH, to jam set a horizontal counter 94. The horizontal counter 94 may for example comprise a binary counter having a plurality of fiip-flop stages for stepping the scanning spot 26 in the imaging device 12 across the face 16 thereof as a line of characters is printed on the film 30. Each flip-Hop in the binary horizontal counter 94 is also coupled to a granularity switching circuit 59 which may comprise a plurality of AND gates with each AND gate corresponding to a different granularity that can be produced by the system 10. One input to each of the AND gates in the switch 59 is the different granularity or graphic quality selected for the character to be printed, as derived from the granularity register 77. The other input to each of the AND gates in the switch 59 are clock pulses derived from a clock oscillator 81 and gated through an AND gate 83 to the granularity switch 59. The AND gates in the granularity switch 59 are each coupled to a different one of the flip-flops in the counter 94 and, depending upon which one of the flip-flops is selected by the AND gate activated in the granularity switch 59, the horizontal counter 94 counts by different binary factors. If the granularity switch 59 selects the first or lowest order flip-flop (i.e. the 20 flip-flop), then the count in the counter 94 moves one count higher for each clock pulse gated through the AND gate 83. If the second or 21 position flip-flop is selected, the horizontal counter 94 increases by two counts for each clock pulse. Similarly, if the nth iiip-fiop is selected, the counter 94 is stepped 2n"1 positions for each clock pulse. Since the horizontal counter 94 effectively determines the horizontal position of the scanning spot 26 for each character slice, the counter 94 places the character slices closer together or further apart in accordance with the granularity instructions.

The count in the horizontal counter 94 is transferred through the transfer gates 96 by a timing pulse TPIG, as well as at the end of each scan to the horizontal position register 98. The positional number in the horizontal register 98 is coupled to a horizontal digital-to-analog converter (DACON) 100 where the digital data is transformed to an analog voltage so as to horizontally position the electron scanning beam 18. The analog voltage is converted to a current in a horizontal driver 102 and applied to the horizontal deiiection coils 22 in the cathode ray tube 12.

As the positional number is transferred out of the horizontal counter 94 at the end of a scan, a flip-flop 85 is set by the transfer. The setting of the flip-flop 85 activates the AND gate 83 to position the horizontal counter 94 to the next scanline. In the absence of granularity control, i.e. when no granularity switch 59 is included in the system 10, the next scanline position is controlled by the point size of the character to be printed. A second character of twice the point size of a lirst character of the same granularity, has the center point of its scanning spot 26 jumped a horizontal distance for each scanline that is exactly twice that of the jump for the first character. For characters of high graphic quality, the scanlines overlap even with a narrow aperture scanning spot 26. Thus, what is effectively controlled is the degree of overlap of the scanlines when the point size of the characters is changed.

A binary representation of the point size of the character being printed is stored in the scanline spacing control register 73, and a timing pulse TPU causes the transfer gates 89 to transfer this spacing number to jam set a scanline spacing control counter 91. The clock pulse output of the AND gate 83 is coupled to down count the spacing control counter 91, and a zero decoder 93 signals the arrival of zero in the counter 91 and deactivates the AND gate 83 and prevents further clock pulses from upcounting the horizontal counter 94. The output of the 4zero decoder 93 also activates the transfer gates 89, and resets the ip-op 85. The transfer gates 89 therefore cause the same point size number to jam set the scanline spacing control counter 91 but the counter 91 is not down counted until the horizontal counter 94 sets the ip-op 85 at the end of a scan. The advantage derived from such operation is that during one scanline, the counter 94 is being stepped to the next scanline position and the counter 94 has time to settle down before the next positional number is transferred to the horizontal position register 98. This eliminates any settling time delay since it occurs while the previous scan is occurring.

It is apparent that if the binary representations of point size from the magnetic tape are proportional to point size, the system allows rapid change of point size. For eX- ample, if the binary representation for a character of 6 points is the binary equivalent of one quantity 6 and for 7 points is the binary equivalent of 7, then the horizontal counter 94 moves 6 increments between scans for a 6 point character and 7 increments for a 7 point character. Therefore, the horizontal distance between scans changes in the proper proportion as the point size is changed. In systern 10, the spacing control register 73 also linearly controls the gain of the vertical driver 112 through a DACON 113. The vertical size of the character changes in proper proportion as the point size is changed. Thus when the vertical driver 112 exhibits a high gain the scanning beam 18 traverses a vertical distance during a scan that is longer than when the driver 112 exhibits a low g It is to be noted that the system 10 exhibits the capability of enlarging or reducing characters by changing point sizes. Other patterns such as line drawings may also be enlarged or reduced to ll up the space on the lm wherein the line drawing is to appear. Granularity changes in line drawings extend the range of enlargement of such drawings.

The incrementer 79 increments the address register 68 to the next data, which is the character width (CW). The timing pulse TP18 causes the decoder 74 to select this data and the timing pulse TP19 causes the data to be read into the data register 78. The binary representation of the number of scanlines in the character width is coupled through the transfer gates 114 by a timing pulse TF2@ into a scan counter 116. The scan counter 116 is decremented by a count of oneV at the end of each scanline so that when a count of zero is reached, a zero decoder 118 coupled to the scan counter 116 signals that the end of a character has been reached. This signal instructs the tape reader 62 to read the next character from the tape 60.

The next data read from the memory is the segment data that actually causes the character slices to be written on the tube 12. This data is read and transferred by appropriate segment data timing pulses generated in a subroutine in the timing and control circuits 70. The segment data is coupled through transfer gates 120` to a buffer register 122. The register 122 stores, at the minimum, the entire number of white and black segments of a complete scan of a character. The register 122 desirably stores the segment data relating to a plurality of scans and may also be operated in a simultaneous readwrite mode, i.e. push-pull, wherein one section of the register 122 is being written into while another section is being read. Such operation prevents delay in forming the segment patterns on the imaging tube 12. A bit detector 123 is coupled to the output of the transfer gates 120 to detect a binary 1 in the 20 bit position of the segments entering the buffer register 122. The bit detector 123 activates a sawtooth generator 134 when this bit is detected to begin the vertical deflection of the scanning beam 18. The bit detector 123 also transfers the segments through transfer gates 124 into a video counter 126. The video counter 126 is jam set by the gates 124 and counted down by a clock oscillator 128. The clock oscillator 128 may comprise the central clock for the timing control circuits 70 to provide the raw timing pulses for these circuits. When the count in the video counter 126 equals zero, a zero decoder 130 transfers a new segment frorn the buffer register 122, into the video counter 126.

Also coupled to the output of the transfer gates 124 is a dual bit detector 132 which functions to detect the bits 21 and 20 in each segment. When the bit 21 in a segment is a 1, the. bit detector 132 sends a signal to the cathode 20 of the tube 12 to bias the cathode 20 to turn on the scanning beam 18. When a "0 is detected in this 21 bit position, the cathode 20 is biased oit. When a binary "1 is detected in the 20 bit position, an output signal is applied to an AND gate where it is gated with the output of the zero decoder 130 to signify the end of a scan. This end of scan signal is coupled to turn off the sawtooth generator 134 when the segment data has been utilized to form the last black segment in the scan.

The sawtooth signal generated in the generator 134 causes the scanning beam 18 to scan upwardly from a beam rest position (eg. line 37, FIG. 2). When the sawtooth generator 134 is reset, the scanning beam is retraced back to the beam rest position line 37 in FIG. 2. The output of the gate 135, which signals the end of a scan, is also coupled to upcount the horizontal counter 94 and to down count the scan counter 116. Since the buffer register 122 may contain scan segments from a variety of scans, there may also be a plurality of video counters 126 so as to insure that there is no delay in reading data from the memory 50.

OPERATION In describing the operation of the photocomposition system 10 it is assumed that a character H of high graphic quality is to be printed first and then a character H of a proofing quality is printed next. It is also assumed that FIGS. 2 and 3 are representations of the relative appearance of these characters in terms of their number of character slices, i.e. the high graphic quality character H in PIG. 2 has twice the number of character slices as the proofing quality character H in FIG. 3.

Of course in neither character do the individual scanlines fail to overlap or touch. In characters of high point size and granularity, the scanning spot 26 may be enlarged by defocusing to cause successive scanlines to touch. The tape reader 62 reads the point size, the granularity, and the font style, of the characters to be printed from the tape 60. The point size of a character is applied through the transfer gates 71 to be stored in the spacing control register 73 due to the initiation of the timing control circuit 70 by the tape reader 62. The character code of the high graphic quality character H, which is a primary address in the memory 50, is then read from the tape 60. The contents of this address specify the secondary address of the first item of the block of data required to form the character H of this font. The character code is coupled directly to the address register 68. The contents of this first primary location is therefore read out of the memory 50 and into the data register 78. Since this data is actually a secondary address, it is transferred into the address register 68 via the transfer gates 82. The address register 68 therefore now addresses the first location in the secondary portion of the memory 50 wherein the format and other data relating to the formation of the character H from the high graphic quality font begins. Consequently, the leading side bearing (LSB) of the character H is read out of the memory 50 and into the data register 78. The leading side bearing data is then coupled through the transfer gates 84 to the binary adder 86 where it is added to the contents'of the register 90. Since the register 90 contains the sum of the character width and the trailing side bearing of the previous character, the contents thereof is zero at this time because it is assumed that the character H is the first character to be printed in a line of print. Consequently, only the leading side bearing data of the character H is applied to the accumulator 87. This value is then transferred through the transfer .gates 92 to jam set the horizontal counter 94, Awhich in turn causes the transfer gates 96 to jam set the horizontal register 98 to this value. The contents of the horizontal register 98 is converted to an analog value in the DACON 100. The analog value is applied through the driver 102 to position the scanning beam 28 to a point equivalent to the point 144 in the line 37 in IFIG. 2. The scanning beam 18 is therefore in the correct horizontal position to begin scanning out the character H.

The transfer gates 89 are also activated by the timing and control circuit 70 to cause the spacing control counter 91 to be jam set to the binary number representing the spacing between scans for a character of the point size specified for the character H. The horizontal counter 94 also sets the flip-flop 85 when the horizontal position of the scanning beam is transferred into the horizontal register 98. The setting of the flip-flop 85 activates the AND gate `83 because the zero decoder 93 has enabled this gate, due to the absence of a zero signal from the decoder 93 being applied to the inhibit terminal of the AND gate 83. The activation of the AND gate 83 transmits the clock pulses from the clock oscillator 81 to down count the spacing control counter 91. The clock pulses are also gated by the granularity switch 59 into the 20 bit input terminal of the horizontal counter 94 to up count this counter. The input terminal is gated open by the granularity switch 59 because a character of high graphic quality is to be printed. The number of clock pulses gated through the AND gate 83 corresponds to a count of the point size of a character. The clock pulses count down the counter 91 to zero lwhereupon the zero decoder 93 deactivates the AND gate 83, resets the flip-flop 85 and also activates the transfer gates 89 to jam set the spacing control counter 91 back to the binary number it previously contained. While the spacing control counter 91 was counted down, the horizontal counter 94 was counted up an equivalent number of pulses and consequently, effectively stores the position of the scanning beam 18 for the next scan, even though the initial scan has not as yet been completed.

Referring back to the memory 50, as each data word is read out and trnasferred through the data register 78, the incrementer 79 adds on to the binary number contained in the address register 68 and causes the address register 68 to address the next location in the secondary block of data in the memory 50. Therefore, the character width and trailing side bearing data is read into the data register 78. This data is then coupled through the transfer gates 88 to the register 90 where it is stored during the scanning of the entire character H so as to be in position to add to the leading side bearing of the next character so that the scanning beam 18 may be properly positioned to begin scanning the next character. The incrementer 79 then increments the address register 68 to read out the character width, which is a binary number representing the actual number of scans required to form a character. This data is transferred through the transfer gates 114 into the stroke or scan counter 116.

The next data read from the memory is the scan segment data necessary to form the character H. The first word in this data is a binary number that specifies the number of pulses from the clock oscillator 128 that occur while the scanning beam is tracing out the black segment 36 between the points 144 and 146 in FIG. 2. When this number is read through the transfer gates into the buffer register 122, the bit detector 123 detects the binary l appearing in the 20 position of this number and knows that an entire scan or stroke has passed into the Ibuffer register 1'22. The bit detector 123 therefore activates the transfer gates 124 to jam set the video counter 126 with the segment data from the buffer register 122 as well as activates the sawtooth generator 134 to initiate the generation of a sawtooth signal. The bit detector 123 may for example comprise a one-shot multivibrator coupled to the 20 position in the transfer gates 120.

Since the first stroke of the character H is a black segment, the bit detector 132 detects the binary l in the 21 position of the segment data and generates a beam on scanning signal that is coupled to the cathode 20 of the tube 12 to turn on the beam 18. The signal from the sawtooth generator 134 is applied through the vertical driver 112 to cause the unblanked scanning beam 18 to rise vertically from its position 144 to the position 146 as shown in FIG. 2. A black segment 36 is therefore formed on the face 16 of the cathode ray tube 12. The light emitted from phosphor on the face 16 of the tube 12 is focused through the lens 28 onto the high gamma photographic film 30 and one black character slice of the character H is exposed on the lm 30.

lThe bit detector 132 also detects the presence of a binary l in the least significant bit position 20, which is the retrace bit position, and applies a continuous retrace signal to the AND gate 135. The clock oscillator 128 counts down the video counter 126 and when the scanning beam 18 reaches the position 146 in FIG. 2,

the zero decoder 130 detects the end of the count down and the AND gate is activated. The output of the AND gate 135 resets the sawtooth generator 134 whereupon the beam 18 is retraced back to the baseline 37 in FIG. 2. The bit detector 132 may therefore include a fiip-fiop that is set by a binary l in the 21 bit position of a data number to generate a scanning beam on bias signal. The bit detector 132 ip-fiop is then reset by either a binary 0 in this 21 bit position or the end of scan output of the AND gate 135. Additionally, the bit detector 132 also includes a second fiip-fiop that is set by a binary l in the 20 bit position of the data. The flipflop applies a retrace signal to the input of the gate 135. This fiip-fiop is reset by the output of the gate 135 which signifies the end of a scan. The scanning beam 18 is retraced in a blanked condition.

At the end of the segment, the zero decoder 130 generates a transfer signal that is applied to the transfer gates 124 to transfer the next segment into the video counter 126 when the bit detector 123 detects sufficient data for another scan. The end of scan signal from the AND gate 135 is also applied to count down the scan counter 116 as well as to the transfer gates 96 to transfer the position of the next scan into the horizontal register 98. This positional number is converted by the DACON 100 and driver 102 into an analog signal to position the scanning beam 18 at the point 147 in FIG. 2. Thus one black segment, comprising an entire scan, of the character H is photographed on the film 30 and the system 10 is ready to create the next character slice.

Each black segment of the character H in the left hand portion thereof is imaged onto the photosensitive film in a manner similar to that described above. As each segment is written, the scan counter 116 is counted down by one. When the center of the character H is reached, the first segment to be written is a white segment. The scanning beam is therefore turned off during the time the beam is traversing the portion of the scans that are shown dashed in FIG. 2. Otherwise, the operation of the system 10 is similar to that described previously. When the end of the character H is reached, the scan counter 116 has been down counted to zero and the zero decoder 118 signifies that the next character should be read by the tape reader 62.

It is to be noted that each one of the character slices in the character H of FIG. 2 requires a certain amount of time to be created on the face 16 of the cathode ray tube 16. The more character slices required in a character, the longer it takes. Foi some projects, such as proofreading, page makeup, etc., the graphic quality of the characters printed are not important as long as they can be read and occupy the same area as the final copy characters of a high graphic quality. The system 10 exhibits the capability of printing proofing characters, such as the character H in FIG. 3, in a fraction of the time it takes to print a character of high graphic quality.

It will therefore be assumed now that the proofing character H is to be printed as the second character in a line of print. The tape reader 62 therefore reads the point size, the granularity and the font style, from the tape 60. The coded representations of the point size and granularity are transferred through transfer gates 71 and 75 respectively to jam set the spacing control register 73 and the granularity register 77 to these values. Of course, the point size in the assumed example is the same but the new granularity value in the granularity register 77 causes the granularity switch 59 to couple the AND gate 83 to the input terminal of the 2l bit flip-Hop in the counter 94. It is apparent therefore that each clock pulse from the clock oscillator 81 that is gated through the gate 83 increased the count in the horizontal counter 94 by two counts. This produces a character with twice the spacing between character slices as the input to the 2o bit fiip-tlop in the counter 94. If the 22 bit Hip-flop were the one activated by the granularity switch 59 then the count in the counter 94 would increase by four counts for each clock pulse, further increasing the spacing between character slices. The system 10 therefore provides interscan spaces that increase by binary factors. However,

decimal spacing changes can also be accomplished by l utilizing a decimal counter rather than a binary counter. Of course, the total number of character slices must be correspondingly reduced to maintain the same point size. Thus the number of scans in the character width in a proofing character font is smaller than the number of scans in a corresponding character of the same point size in a high graphic quality font.

The font style read from the tape activates the incrementer 67 and the character code for the proofing quality character H is read into the address register 68 incremented by the fixed amount added by the incrementer 67. Thus the same character code for the letter H can be utilized in the two fonts stored in the memory 50 with the correct primary portion 52 of the memory 50 being addressed by adding known fixed increments to the character code number. It is apparent that if more than two fonts are to be stored in the memory 50, then increments in addition to that supplied by the incrementer 67 would be added to the system 10 to correctly address these fonts. The contents of this primary location is read through to the address register 68 because it comprises the secondary address of the beginning of the block of format and scan data contained in the secondary portion of the memory 50 for the proofing character H. The first format data read out is the leading side bearing of the proofing character H. This data is added to the contents of the register in the binary adder 86 and the sum is then added to the number stored in the accumulator 87, which for the example given is the leading side bearing of the previous character. It is to be recalled that the contents of the register 90 are the character width and the trailing side bearing of the previous character printed. The accumulated total is utilized to jam set the horizontal counter 94 and the horizontal register 98. The accumulated total therein is converted to an analog value in the DACON and applied through the driver 102 to position the scanning beam 18 at the horizontal position 148 in FIG. 3. It is to be noted that the scanning beam 18 has been jumped to the point 148 in FIG. 3 and no time was wasted in scanning the intercharacter space between the characters.

The character width and the trailing side bearing for the proofing character H is then entered into the register 90 and remains there awaiting the next character. The coded representation of the number of scans of the character width is then read into the scan counter 116. It is to be noted that the number of scans in the proofing character H of FIG. 3 is one-half that of the high graphic quality character H in FIG. 2 because adjacent scans are spaced twice as far apart as the adjacent scans in the high graphic quality character H.

The scanning beam 18 is positioned to scan out the proofing character H and the character is created in a manner similar to that described for the character in FIG. 2. At the end of scanning a line of print, the tape reader 62 signals the drive motor 24 to move the photographic lm 30 to the next line and also -resets the horizontal counter 94 to the beginning of a new line of print.

Thus a photocomposition system 10 has been described that is significantly fast when scanning out characters of a proofing quality. The system 10 also exhibits the capability of changing the granularity of characters in steps from high graphic quality to proofing qualities.

It is to be noted that the fonts for the high graphic quality and the proofing quality need not be stored in the memory 50 all the time. Since the proofing quality fonts utilize less storage space and the speed of the system 10 is fast, the proofing quality fonts can be written into the memory 50 very quickly.

It is also apparent that if the fonts stored in the memory 50 are arranged in a particular manner wherein each character has stored therefor words of data that are equal in number for each scan, then every second, fourth, or nth scan can be printed and the necessity of storing a proofing quality font in the memory 50 is avoided. Thus in FIG. 1, an AND gate 69 (shown dashed) is coupled to the incrementer 79 to apply clock pulses from the clock oscillator 81 to increment the incrementer 79 an additional amount as determined by a counter 101. When segment data is read out of the memory 50 and transferred through the data register 78 and AND gate 109, a fiip-op 103 (shown dashed) is set which in turn resets the counter 101 to zero. The AND gate 69 is then activated to pass clock pulses to cause the incrementer 79 to increase the address in the address register 68 by the amount set in the counter 101. Thus if the counter is set to count up to three, the AND gate 69 is disabled, after passing three pulses, by the output signal from the counter 101 which is applied to the inhibit terminal of the AND gate 69. The Hip-flop 103 is also reset by the output of the counter 101. Thus for the segment data in each character slice read from the memory 50, the address register 68 is skipped over three character slices to address the fourth one.

To insure that the scan or character slice count comes out evenly with the skip count,` an AND gate 105 (shown dashed) is coupled between the transfer gates 114 and a divider circuit 107, also shown dashed. The AND gate 10S is activated by a fiip-fiop 111 set by the tape reader 62, to cause the divider 107 to divide the number of scans in the character width by the appropriate amount to compensate for the skipped scanlines. The flip-flop 111 is reset by an end of character signal. The divider 107 divides so as to effectively cancel scans not divisible evenly.

Thus a photocomposition system 10 has been described which is capable of printing both proofing quality characters and high graphic quality characters. The proong quality characters are printed very rapidly permitting page makeup and proofcopying to be done quickly.

What is claimed is:

1. A composition system comprising in combination,

an imaging device for forming characters of given point sizes by a plurality of adjacent scanlines that provide slices of said characters,

characters of a graphic quality being formed of a given number of scanlines of predetermined spacing,

first means coupled to said imaging device for reducing said number of scanlines so as to form characters of a proofing quality, and

second means coupled to said imaging device for increasing the spacing between said scanlines in said proofing characters so that corresponding characters of the same point size in both said graphic and proofing qualities occupy the same area.

2. A system in accordance with claim 1 that further includes, a memory having a plurality of storage locations coupled to said imaging device for storing coded representations of said scanlines.

3. A system in accordance with claim 2 wherein stored coded representations of said character slices for said proofing quality characters require less storage locations than corresponding characters of said gaphic quality.

4. A system in accordance with claim 2 wherein each of said stored coded representations corresponds to one of said character slices.

5. A system in accordance with claim 4 that further includes, means coupled to said memory for selecting nonconsecutive but periodic coded representations of said character slices to reduce the number of character slices so as to form a character of a proofing quality.

6. A system in accordance with claim 1 that further includes, a counter for counting elements between adjacent scanlines of a character to determine the point size of a character.

7. A system in accordance with claim 6 that further includes,

a scanline position control counter having a plurality of input terminals which provide output counts that are of increasing powers of input pulses applied thereto, and

means for converting said output counts into position signals to position adjacent scanlines in said imaging device at interscanline `distances that are determined by said output counts.

8. A system in accordance with claim 7 that further includes means for applying input pulses to an input terminal of said scanline position control counter that provides a low power output count of said input pulses so as to space adjacent scanlines in said imaging device at an interscanline spacing of a high graphic quality.

9. A system in accordance with claim 10 that further includes means for applying input Ipulses to an input terminal of said scanline position control counter that provides a high power output count of said input pulses so as to space adjacent scanlines in said imaging device at at interscanline spacing that provides characters of a proofing quality.

10. A composition system comprising in combination,

an imaging device for forming characters by a plurality of scanlines with each of said scanlines providing a lcharacter slice,

means coupled to said imaging device for changing the sizes of said characters so as to provide characters of a plurality of diierent point sizes, and

means for changing the number of scanlines utilized to `form said characters so as to create characters of dierent granularities in the same and different point s1zes.

11. A composition system comprising in combination,

an imaging device for forming patterns by a plurality of adjacent scanlines with each of said scanlines providing a pattern slice,

means coupled to said imaging device for changing the number of scanlines utilized to form said patterns so as to provide a plurality of granularities for said patterns, and

means for changing the spacing between adjacent scanlines to create patterns that exhibit one of the characteristics of enlargement and reduction so that patterns of desired sizes are created.

References Cited UNITED STATES PATENTS 3,348,229 10/1967 Freas 340-324NX 3,428,751 2/ 1969 `Greellblunl 340-3 24X- 3,437,873 4/ 1969 Eggert 340-324X DONALD I. YUSKO, Primary Examiner D. L. TRAFTON, Assistant Examiner U.S. Cl. X.R. 95-4.5; 315-24

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
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US4393376 *Jun 4, 1981Jul 12, 1983Zenith Radio CorporationTeletext interface for digital storage medium having synthetic video generator
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US4586835 *Jan 29, 1985May 6, 1986International Business Machines CorporationPrinter for printing characters in two alternative print qualities
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Classifications
U.S. Classification345/472, 396/550
International ClassificationB41B27/00, B41B19/01, B41B27/28, B41B19/00
Cooperative ClassificationB41B27/28, B41B19/01
European ClassificationB41B27/28, B41B19/01