US3755805A - Character generator for producing characters on the screen of a cathode-ray tube - Google Patents

Character generator for producing characters on the screen of a cathode-ray tube Download PDF

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US3755805A
US3755805A US00120528A US3755805DA US3755805A US 3755805 A US3755805 A US 3755805A US 00120528 A US00120528 A US 00120528A US 3755805D A US3755805D A US 3755805DA US 3755805 A US3755805 A US 3755805A
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character
bits
generator
pulses
transfer register
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P Dandrel
J Moreau
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US Philips Corp
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US Philips Corp
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G1/00—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data
    • G09G1/06—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data using single beam tubes, e.g. three-dimensional or perspective representation, rotation or translation of display pattern, hidden lines, shadows
    • G09G1/08—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data using single beam tubes, e.g. three-dimensional or perspective representation, rotation or translation of display pattern, hidden lines, shadows the beam directly tracing characters, the information to be displayed controlling the deflection and the intensity as a function of time in two spatial co-ordinates, e.g. according to a cartesian co-ordinate system
    • G09G1/10—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data using single beam tubes, e.g. three-dimensional or perspective representation, rotation or translation of display pattern, hidden lines, shadows the beam directly tracing characters, the information to be displayed controlling the deflection and the intensity as a function of time in two spatial co-ordinates, e.g. according to a cartesian co-ordinate system the deflection signals being produced by essentially digital means, e.g. incrementally
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M7/00—Conversion of a code where information is represented by a given sequence or number of digits to a code where the same, similar or subset of information is represented by a different sequence or number of digits

Definitions

  • Ultra-rapid character generator for use with a cathoderay tube operating on straight line segments and equipped with a permanent store from which by means [30] Foreign Application Priority Data Mar. 5, 1970 France 7007946 of a store word address a character codeword is passed to a transfer register, which transfers the relevant character codeword sequentially in a number of relevant groups of 5 bits to a decoder, 3 bits determining 8 line segment directions, 1 bit determining a single or double line segment length and 1 bit determining the display or non-display.
  • the invention relates to a character generator for producing characters on the screen of a cathode-ray tube, said characters being formed by straight line segments, the character generator comprising a permanent memory store with the segment information in a code word of n groups of bits, one group per segment, and a pulse generator for producing phase-shifted pulses having a gating function, by means of which pulses the segment information is supplied sequentially, group after group, on one hand through a transfer register, to a digital-analogue converter for providing deflection signala for the cathode-ray tube and on the other hand to the tube for the display or non-display of the segment.
  • every character or symbol to be displayed may be formed by 16 groups of 15 bits, that is to say, 15 groups for 15 straight line segments of a given length and one group for supplying a signal for indicating the end of the character (characteror symbol-end signal).
  • the permanent store is scanned by consecutive pulses as many times as there are potential segments for the display of each symbol.
  • this method is not appropriate for a quick display of a symbol because the obtainment of all instructions for the formation of a word from the permanent store requires fifteen scans of the store for each symbol, that is to say, one scan for each group of bits, whereas a character may well be formed by considerably fewer segments than 15.
  • the character B formed by 12 segments is given.
  • the known generator involves an access delay time and a scanning time of a vector or line segment of comparatively great length with respect to the time required for the display of the vector.
  • the display rate of a character and the price of the apparatus are two intimated related aspects due to the usually increasing complexity of the electronic equipment required for the simultaneous display of a great number of symbols.
  • the ultra-rapid generator according to the invention provides a simple, economic solution of said problem.
  • the known generator does not permit of magnifying the symbols to be formed in all directions in a simple manner without variation of the brightness of said symbols.
  • the character generator according to the invention avoids these disadvantages.
  • This generator is used for providing a device permitting a high-rate display of symbols to be transmitted, the time required for the transmission being of the order of 0.08 usec per segment instead of 25 ,usec as indicated in said article, so
  • the character generator is characterized in that it comprises a decoder which decodes the segment information given for each character in its own code word by groups of five bits, three hits determining one of eight line segment directions, one bit determining a single or a double line-segment length and one bit determining display or non-display of the line segment on the screen of the cathode-ray tube, said decoder being connected between the transfer register and the digital-analogue converter and the cathode-ray tube.
  • a five-bit code can thus comprise one bit providing an additional information, for example, an information relating to the single or the double length of a segment.
  • This particular mode of coding is used in the generator according to the invention so that a greater variety of symbols can be displayed by a smaller number of segments.
  • the particular coding in accordance with the invention permits of utilizing the full capacity of a store of 64 bits of the commercially available type. Such an occupation of the store is an economic advantage, which can be attained by reducing the maximum length of a storage word to 64 bits, instead of 70 bits. This is achieved by connecting six inputs of the transfer register beyond the store through external wiring to two biassed terminals, the first terminal providing the second bit of the first group of each of the characters and the second terminal providing, in a group of five bits, the 14th group which corresponds to the character-end signal if the character is formed by a maximum number of 13 segments.
  • FIG. la shows the character generator according to the invention associated with a position generator providing a sequence of starting points of characters and symbols on the display screen of a cathode-ray tube of a peripheral display system connected to an external control-unit, for example, a computer or the like.
  • FIG. lb illustrates the basic diagram of the ultrarapid character generator embodying the invention.
  • FIG. 2 illustrates the relationship between the direction and the sense of 8 vectors and their coding by 3 bits, which are the first bits of each group of 5 bits, which determine the display of each character segment.
  • FIG. 3 illustrates the rhombis unity pattern having sides of 4 X 4, in which allsymbols are displayed with the aid of the 8 vectors of FIG. 2.
  • the more solid lines form. the capital G and moreover a portion of the next character H.
  • This Figure illustrates clearly the return to the origin after the character-end" signal.
  • FIGS. 4 and 5 show by way of example a few characters that can be displayed without exceeding the limit number 13 of segments per character.
  • FIG. 4 shows the 26 characters of the alphabet in bold letters and, in addition, 4 further symbols.
  • FIG. 4 illustrates the transition from one origin to a next origin, said transition being performed by means of the position generator of FIG. 1 independently of the ultra-rapid character generator embodying the invention.
  • FIG. 5 illustrates the digits 0 to 9 and 21 other characters and symbols.
  • FIG. 6 illustrates the circuit-diagram of one stage of a transfer register of FIG. lb. the transfer register is formed by five of these stages.
  • FIG. 7 illustrates the circuit-diagram of the decoder of FIG. lb.
  • FIG. 8 illustrates a time diagram indicating the time division, on the one hand, of the various operations required for storage in a store, for the analysis of the transfer register and on the other hand, the display and the termination of the display of the characters (shown in FIG. 8 for the display of the character G).
  • FIG. 9 is a diagram of the pulses obtained at the outputs of a clock-pulse generator and of a pulse generator producing shifted pulses for said transfer register with respect to the output pulses of a gate circuit operating as a magnifying member, which determines the size of the displayed character or symbol.
  • FIG. 10 illustrates the principle of a digital-analogous converter employed herein.
  • FIG. la illustrates the independence of the operation of a character generator GS embodying the invention of a position generator GP for positioning the beginning of the symbols.
  • the generators GS and GP controlled by a control-unit l are connected to the deflection signal amplifiers X and Y and to a video-signal amplifier Z of a cathode-ray tube TC.
  • control-unit 1 determines the position of the light spot at the desired starting place on the screen of the cathoderay tube TC through the position generator GP and subsequently supplies to the character generator GS- the code of the symbol and, in addition, the information of the size of said symbol and then supplies the symbol starting pulse.
  • the signals produced by the generator GS are then applied to the inputs of the amplifiers X, Y and Z.
  • FIG. 1b illustrates schematically the principle of an ultra-rapid character generator GS embodying the invention.
  • the clock-pulse generator 2 and the startingending" circuit 3 are connected to the external controlunit 1 via lines 12 and 12, which have to supply to the generator GS the symbol starting signal from the control-unit l.
  • a transmission decoder 4 is provided between the control-unit 1 and a permanent store 7 and ensures that a coded group of bits determining the symbol to be displayed is decoded to a storage word address.
  • a multicore cable 11 connects the control-unit l to the transmission decoder 4. The number of cores of the cable 1 1 depends upon the code used by the control-unit. In the case of the international code ASC ll comprising 7 bits permitting a coding of 128 characters, the cable 11 comprises 7 cores in parallel connection which link the control-unit 1 to the decoder 4.
  • a cable 14 having r parallel cores connects r outputs of the decoder 4 to r inputs of a permanent store 7, that is to say one input for each stored word. The number r thus corresponds to the number of words stored, one for each symbol.
  • the permanent store 7 comprises a number r of words equal to the number of symbols to be displayed.
  • a line 13 connects an output of the beginning-ending circuit 3 to a further input of the transmission decoder 4.
  • the line 13 supplies to this decoder the scan sequence for the store 7 with the corresponding address and provides the control from the beginning of the display of the symbol after thecircuit 3 has received the symbol starting pulse from the control-unit 1.
  • each character segment requires one group of 5 binary information signals and in the case of a character formed by 13 segments an additional group of 5 bits occurs for generating the signal corresponding to the end of the character.
  • a length of bits of the character code word is obtained, which is required for the display of any symbol. This is not desirable because the commercially available apparatus is adapted to standard word lengths of 64 or 128 bits.
  • the cable connects the permanent store 7 to a transfer register 8, whilst in two steps said word length of 70 bits is reduced to a word length of 64 bits, so that the store 7 can be a 64-bit codeword length store.
  • a core 22 connects in the same manner the register 8 to a terminal E located outside the store 7, which terminal has the same voltage as the terminal B.
  • This core 22 permits the formation of the 14th group of 5 bits, which is coded so that it generates the character-end pulse when the number of n-segments forming the symbol is equal to 13. If the number n is lower than 13, which depends upon the character itself, said character-end pulse is produced by the (n I) group of 5 bits in the store 7.
  • the transfer register 8 is connected between the store 7 and a decoder 9 and is connected by cable 17 having 9 cores to a pulse generator 5, which controls the transmission of each group of 5 information bits transmitted by the cables 71, 72, 73, 74 and 75 across the transfer register 8 to said decoder 9, the register 8 being formed by 5 identical stages 8,, 8 8 8 and 8 operating in parallel.
  • each of said stages 8 through 8 is connected via 14 cores, each core providing the transmission of the bit of the same ordinal number in each of the l4-potential groups of 5 bits, the decoder 9 receives the information in a group of 5 bits.
  • the transfer register 8 is connected via double lines 81, 82, 83, 84 and 85 to the decoder 9, whose outputs are connected via lines 91, 92, 93 and 94 to deflection signal generators 10a and 10b of a digital-analogue converter 10 and via a line 95 to the video-signal generator 100.
  • the information supplied by the transfer register 8 via the lines 81 to 85 is transmitted, after conversion in synchronism with one of the synchronizing pulses of a duration t,, t transmitted via one of the lines 15,, connecting the clock-pulse generator 2 to the decoder 9 and after conversion into control-pulses with the value 0 or 1 of the fourth bit of the group of 5 information pulses, to, on the one hand, the generators 10a and 10b of said digital analogue converter 10 for generating an analogue signal for the amplifier X and Y respectively and on the other hand, the generator 100, which supplies to the amplifier Z pulses controlling the ignition of the Wehnelt electrode of the cathode-ray tube TC of FIG. 1a.
  • the decoder 9 comprises, in addition, a device for producing the character-end signal which is transmitted via a line to the control-unit l.
  • the characterend signal sets back to the initial state the assembly of elements of the generator GS via lines 20 and 21., i.e., via the line 20' the circuit 3 and the generators 2 and 5 and via the line 21 the converter 10 across the circuit 3.
  • the pulse generator 5 supplies a release pulse to the decoder 9 for releasing it for the time in which the character information is available via the transfer register 8.
  • the operation of the digital-analogue converter 10 in the character generator GS, the circuit-diagram of which is illustrated in FIG. 10 is based on the charge and discharge of a capacitor C with a constant current value +i or i.
  • Such a converter may be used for generating positive and negative voltages having, in absolute value, the same steepness.
  • a gate circuit 6 provides an omnidirectional enlargement of a character.
  • the circuit 6 is directly controlled via a line 18 by the unit 1 and is connected on the one hand to the clock pulse generator 2 via a line 16 and on the other hand to the generator 5 via a line 19, said generator supplying a sequence of pulses to the transfer register 8.
  • FIG. 2 illustrates the coding of the 8 unity vectors by means of the first 3 bits of each group of 5 bits.
  • the display can start from the beginning of any character only in one of the three directions: the horizontal direction having the code 000, the diagonal direction having the code 100 and the vertical direction having the code 001. It is apparent that in these three code values the second bit is the same, that is to say 0.
  • This mode of coding in accordance with the invention permits of supplying the second bit of the first group of each character beyond the store 7 via an external connection (terminal B).
  • Table I indicates by way of example the coding of a character (letter G of FIG. 3).
  • the numbers 1 to 10 of the left-hand column of this Table indicate the order of succession in time for writing the ten vectors used for the character, whilst the number 11 corresponds to the command character-end.”
  • Table l indicates the value of n of the character to be displayed: for the character G (l 1 groups) the value n is 100.
  • the Table also indicates the (n 1)th group of 5 bits generating the character-end signal, said group of 00000 providing zero-setting of the various circuits of the system; the Table shows the case of the character-end signal for a symbol of n l3 (characters 8 or S).
  • Table also indicates the places of the bits originating from said terminals B and E of FIG. lb.
  • the symbols can be determined independently of each other, so that the number of symbols or characters may exceed 256 (2 the system using this mode being thus changed only as far as the corresponding number of storage codewords is added.
  • the Table illustrating the coding of a character G shows the special nature of the coded sequence transferred by the register 8 to the segment decoder 9 (formed by 00000), which generates the character-end signal.
  • This character-end signal is produced immediately after the transmission of the n groups of 5 bits of the stored word, which corresponds to any symbol, in being any integral number lying between 2 and 13.
  • This (n l)tl1 group of 5 bits either obtained from the permanent store when the stored codeword comprises fewer than 13 groups as in the case of the character 6 or from beyond said store 7 via the additional line 22 with S parallel-connected inputs to the transfer register 8 (FIG. 1b).
  • Bit 1 assumes the value 0, when either X or Y, are zero, whereas it assumes the value 1 when X and Y are equal to each other (inclined vectors).
  • FIGS. 4 and 5 illustrating a few digits, characters and symbols obtainable by the character generator GS embodying the invention, permit a statement of the aesthetical value thereof.
  • the sequence of the straight line segments is given for the first three symbols of FIG. 4.
  • the cable 14 of FIG. lb comprises r 61 cores for the 61 characters and the store 7 comprises 64 word addresses.
  • FIG. 6 illustrates one embodiment (8,) of one of the five stages 8, to 8 of the transfer register 8 for the transfer of the first bit of each group of 5 bits by means of two electronic subassemblies having each 8 Nandgates.
  • 14 inputs oflines 71,, 71,, 71, and terminal E are arranged in two groups of 7 inputs each and are connected to inputs of two groups of 7 Nand-gates, whereas the other inputs of said two groups of gates are connected to 7 lines T, to T-,.
  • the 7 gate outputs of one group are connected to 7 inputs of a Nand-gate 62 or 63, respectively the 8th input of which is connected to a line R, or R respectively.
  • the outputs of the gates 62 and 63 are connected to two inputs of a Nand-gate 61, the output of which directly forms an output S, and an output S, via an inverter.
  • This output S, and its complementary output S indicated by a double line, supply in order of succession the information of the first bit I of each of the 14 groups of 5 bits.
  • FIG. 7 shows one embodiment of the decoder 9 an illustrates the synchronism between the signals X, Y
  • the influence of the length information that is to say, of the fourth bit at the inputs for the synchronizing pulses of durations 1,, t, and at the input$( S,,,), which selects between the durations t, and 1,.
  • FIG. 7 shows for the decoder 9 the main connections in accordance with the invention to the transfer register 8 (lines 81 to 85), to the clock-pulse generator 2 (lines 15, and 15 and to the pulse generator 5 (line 23 of FIG. lb).
  • the input S7 corresponds to one of the lines 81 of FIG. 1b
  • the inputs S,, and S, correspond to the lines 82
  • the inputs S,,, a nd S,, correspond to the lines 83
  • the inputs 8,, and S, correspond to the lines 84 and the input 8
  • the input for the pulses of the duration 1 corresponds to the line 15, of FIG. lb and the input for the pulses of the duration 1, corresponds to the line 15, from the clock-pulse generator 2, which provides the synchronous operation.
  • the pulse generator 5 supplies a release pulse to the decoder 9.
  • Mo eove a 5-input Nand-gate 113 connected to inputs S, Sy forms the device supplying the characterend signal via the line 20.
  • the decoder 9 comprises furthermore l2 Nand-gates 101 to 112, FIG. 7 showing the following input connections:
  • iii m. 109 s ,101, 102,107 1 1 ⁇ is s msfff10s,104,107 104: h iif' iii 111:s,,,103,104, 107 105; s 1s,,23,113 ioezsf' f 15., 23, 113 107; 105, 106 1121s,, 107
  • the gate 108 decodesLhe signal X 0, when S,,, 0, (that is to say, when S,,, l).
  • the gate 109 decodes the signal X 0, when S,,, l.
  • the output signals of the gates 108 and 109 depend upon, and are synchronized by, the output signals of the gate 107.
  • the Nand-gates 103, 104, 110 and 111 have identical functions for Y.
  • the gate 105 passes the pulse of the duration 1, (15,), when S, l and if line 23 and the gate 113 provide the logical 1.
  • n n er gate 106 selects pulse t,, when S,, 0, i.e. when S l.
  • the gate 107 ensures the passage of the pulse emanating from gate 105 or 106.
  • coding of the 3 bits determining the vectorial direction permits of reducing the length of the stored word from 70 to 64 represented bits for normal use.
  • the combination of the meaning of the first three bits of a group of five bits determining the direction and the value of the segment with the length information respresented by the fourth bit provides the possibility of materially reducing the number of the logical integrated circuits required for decoding.
  • the time diagram shown in FIG. 8' illustrates the manner of operation of the various electronic circuits forming the ultra-rapid generator GS embodying the invention as a function of time during the display of a symbol on the display screen.
  • the waveforms of FIG. 8 illustrate in detail the signals appearing at the corresponding cables and lines of FIGS. 1, 6 and 7.
  • the lines 11, 12 and 12 indicate the instants of reception of the code ASC II with 7 bits supplied in parallel by the control-unit l to the transmission decoder 4 (line 1 1) the instant being directly followed by the symbolor character-starting pulse to the clock-pulse generator 2 and the character-starting and -ending circuit 3 (lines 12 and 12').
  • Line 16 indicates the pulse emanating from the clock-pulse generator 2 via the gate circuit 6 to the pulse generator 5, which supplies sequential, i.e., phase-shifted pulses.
  • the line 19 shows the charactersize pulses transmitted by the gate circuit 6 operating as a magnifying member, to the generator 5.
  • clock pulse generator 2 operates, for example, with a frequency of 12.5 MHZ.
  • the lines T, to T, and R, and R show relatively shifted pulses transmitted by said generator 5, operating as a time base, to register 8 via the cable 17 having 9 parallel-connected cores, whilst R, passes the first 7 groups of 5 bits and R, passes the further groups of 5 bits (FIG. 6).
  • the signals S, S corresponding to the lines 81 to 85 provide the simultaneously occurring bits I to V of consecutive groups in accordance withthe foregoing Table indicating the coding of the character G, the order of succession being determined by the transfer register 8.
  • the pulses of the durations t, and I correspond to the single or the double duration of the pulses produced by the clock pulse generator 2, which are separately transmitted in parallel to the segment decoder 9 via the lines 15 and 15,.
  • the time ratio of these pulses corresponds to the length ratio of the various displayed segments of the same symbol (single or double).
  • the line X shows the analogue signal X, which is formed by the signal generator 100 from the digital pulses of the lines 91 and 92, which provide, through the logical circuits in the decoder 9, the decoding of the respective values X O and X 0.
  • the segment decoder 9 selects the pulse of the duration t, or the pulse of the duration t so that the display time depends upon the value of the fourth bit of the group of 5 bits determining one segment.
  • the choice of 1, (S 0) or t (S l) is illustrated on the lines X, Y and Z of the time diagram of FIG. 8.
  • the lines and Z represent the decoded ignition and extinction signals for the Wehnelt electrode (line 95) and the corresponding ignition pulses.
  • Line 20 indicates a character-end pulse and line 23 the decoder release pulse, the leading edge of which corresponds with that of the first pulse on the line T,, whereas the trailing edge is given by the character-end pulse.
  • FIG. 9 illustrates by a pulse diagram the operation of the gate circuit 6, operating as a magnifying member and arranged between the clock pulse generator 2 and the pulse generator 5 producing phase-shifted pulses.
  • line 16 indicates the synchronizing pulses of the system transmitted by the clock pulse generator 2
  • T T T indicate the pulses passed by the gate circuit 6 to the generator 5 (line 19) with the correspondingly produced phase-shifted pulses at the lines T,, T,, etc.
  • the lines 15,, and 15, indicate at d the double duration of the t pulses as compared with the t, pulses, which determine the length of the segment to be displayed.
  • the pulse of duration 1, or the pulse of duration t is chosen in accordance with the value of the fourth bit, of each of said groups for controlling the time required for displaying one segment.
  • the output of the decoder 9 thus provides'the 5 said signals at the lines 91 to 95 for a duration t, or for a duration t, in accordance with the length of the displayed segment.
  • the time 1, corresponds to a unit length and the time t, to twice the length. It follows that the lines drawn at b in FIG. 9 correspond with those of FIG. 8.
  • Readily readable characters and symbols owing to the aesthetical shape of each character, to the constancy of the brightness and to the precision of each character.
  • the character generator permits of displaying an optimum number of characters with the use of a minimum number of electronic elements.
  • Readily controllable a single knob provides the sharpness of the displayed symbols and characters by a phase control in synchronism with the clock pulses.
  • the generator is equipped with an image magnifying member allowing an overall variation from the unit value 1 of the symbol size to a value p X l, the factor p being an integral number at least equal to 2.
  • the unit size of a symbol displayed on the screen is preferably written in a pattern of squares (width 4 mm and height 5 mm). The height and width vary, of course, with the application of the deflection-signal amplifiers X and Y employed.
  • the character generator GS is controlled by the control of the relative values of the times t, and t corresponding to the relation 2 21 and by the control of the time phases for obtaining synchronism with the signals from the transfer register.
  • the synchronism suppresses all errors due to the variations in characteristics of the logical circuits employed in the whole assembly.
  • the signal values X 0 or Y 0 are obtained in the absenceofX 0orX 0andofY 0orY 0.
  • All logical circuits of the generator GS are compatible with DTL integrated circuits (diode-transistorlogics) and the TTL integrated circuits (transistor-transistor-logics).
  • a character generator GS for reducing the characters from the size of a first character occupying approximately the whole available surface of the screen; in this case formed by straight line segments, the unit surfaces of the segments of the configurations being adjacent each other without interstices or with an overlap obtainable by a simple programme of the position generator GP,
  • a character generator for producing characters on the screen of a cathode-ray tube, said characters being formed by straight line segments, the character generator comprising a permanent memory store with the segment information in a codeword of groups of bits, one group per segment, a pulse generator for producing phase-shifted pulses having a gating function, whereby pulses of the segment information are supplied sequentially, group after group, on the one hand through a transfer register to a digital-analogue converter for providing deflection signals for the cathode-ray tube, and on the other hand to said cathode ray tube for the display or non-display of the segment, the character gen- A erator further comprising a decoder for decoding the segment information given for each character in its own codeword with groups of five bits, three bits determining one of eight line segment directions, one bit determining a single or double line segment'length and one bit determining the display or non-display of the line segment on the screen of the cathode-ray tube, said decoder being connected between
  • each of the code-words of the characters supplied by the store have a group of bits for the first segment comprising four bits and all further groups comprise five bits each, two of the bits in the first group of four bits determine the direction of the segment, the transfer register itself supplying beyond the store, by means of a biased terminal, the failing bit which is the same for each codeword, to the decoder.
  • a character generator as claimed in claim 2 wherein between the clock pulse generator and the pulse generator providing the phase-shifted gate pulses for the transfer register, a gate circuit is provided which operates as a character magnifying member in accordance with the passage or nonpassage of consecutive clock pulses.
  • a character generator as claimed in claim 2 wherein the clock pulse generator supplies pulses through two lines to the decoder, pulses having a duration t, in one line thereof and pulses having a duration t, 21 in the other line thereof.
  • a character generator as claimed in claim 5 characterized in that the decoder comprises multi-input gates coupled with the transfer register and connected to each other, the outputs of the decoder being formed by outputs of gates of which one input of each gate is connected to one input on further gates for synchronization purposes, said inputs being coupled with outputs of further gates, to inputs of which are applied the fourth bits information of the transfer register and the pulses of the durations t, and t of the clock pulse generator.
  • a character generator as claimed in claim 1, wherein the decoder comprises a gate of five inputs, to which five information outputs of the transfer register are connected, said gate supplying a character-end signal in the case of (l-information.
  • a character generator as claimed in claim 7 when using a store having character information in the form of a store codeword having an n number of groups presenting a maximum permissible total number of bits, the transfer register is provided with a group of inputs connected to a biassed terminal supplying the 0- information beyond the store for the (n 1 )th group.
  • a character generator as claimed in claim 8 wherein the store is of the type having a maximum length codeword of 64 bits, whilst the transfer register supplies 14 groups of 5 bits at its 5 outputs.

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US00120528A 1970-03-05 1971-03-03 Character generator for producing characters on the screen of a cathode-ray tube Expired - Lifetime US3755805A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3952297A (en) * 1974-08-01 1976-04-20 Raytheon Company Constant writing rate digital stroke character generator having minimal data storage requirements
US4276602A (en) * 1978-08-07 1981-06-30 Hitachi, Ltd. Electronic engine control apparatus having arrangement for varying fuel injection duration
EP0020980A3 (en) * 1979-06-25 1982-03-17 International Business Machines Corporation Segmented-display device
EP0130245A1 (en) * 1983-06-30 1985-01-09 International Business Machines Corporation Method of storing characters in a display system
US4615012A (en) * 1982-12-09 1986-09-30 Alps Electric Co., Ltd. Method of generating character patterns
US5233335A (en) * 1989-06-22 1993-08-03 Hughes Aircraft Company Symbol/raster generator for CRT display
US20050249387A1 (en) * 2004-05-06 2005-11-10 Akihiro Machida Finger-based identification systems and methods

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4239351A (en) * 1978-09-26 1980-12-16 Baylor College Of Medicine Apparatus for generating and displaying visual acuity targets

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3281831A (en) * 1964-07-02 1966-10-25 Burroughs Corp Character generator apparatus including function generator employing memory matrix
US3329948A (en) * 1963-05-03 1967-07-04 Burroughs Corp Symbol generating apparatus
US3533096A (en) * 1967-09-01 1970-10-06 Sanders Associates Inc Character display system
US3539860A (en) * 1969-04-01 1970-11-10 Adage Inc Vector generator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3329948A (en) * 1963-05-03 1967-07-04 Burroughs Corp Symbol generating apparatus
US3281831A (en) * 1964-07-02 1966-10-25 Burroughs Corp Character generator apparatus including function generator employing memory matrix
US3533096A (en) * 1967-09-01 1970-10-06 Sanders Associates Inc Character display system
US3539860A (en) * 1969-04-01 1970-11-10 Adage Inc Vector generator

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3952297A (en) * 1974-08-01 1976-04-20 Raytheon Company Constant writing rate digital stroke character generator having minimal data storage requirements
US4276602A (en) * 1978-08-07 1981-06-30 Hitachi, Ltd. Electronic engine control apparatus having arrangement for varying fuel injection duration
EP0020980A3 (en) * 1979-06-25 1982-03-17 International Business Machines Corporation Segmented-display device
US4615012A (en) * 1982-12-09 1986-09-30 Alps Electric Co., Ltd. Method of generating character patterns
EP0130245A1 (en) * 1983-06-30 1985-01-09 International Business Machines Corporation Method of storing characters in a display system
US5233335A (en) * 1989-06-22 1993-08-03 Hughes Aircraft Company Symbol/raster generator for CRT display
US20050249387A1 (en) * 2004-05-06 2005-11-10 Akihiro Machida Finger-based identification systems and methods
US8594391B2 (en) * 2004-05-06 2013-11-26 Avago Technologies General Ip (Singapore) Pte. Ltd. Finger-based identification systems and methods

Also Published As

Publication number Publication date
SE358494B (enExample) 1973-07-30
CA923591A (en) 1973-03-27
DE2107005A1 (de) 1971-09-23
FR2044615A5 (enExample) 1971-02-19
GB1350480A (en) 1974-04-18
CH536520A (de) 1973-04-30
NL7102660A (enExample) 1971-09-07

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