US3561354A - Print hammer selection circuit in endless belt line printers - Google Patents

Print hammer selection circuit in endless belt line printers Download PDF

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Publication number
US3561354A
US3561354A US752063A US3561354DA US3561354A US 3561354 A US3561354 A US 3561354A US 752063 A US752063 A US 752063A US 3561354D A US3561354D A US 3561354DA US 3561354 A US3561354 A US 3561354A
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Prior art keywords
carrier
coupled
outputs
pulse
successive
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Expired - Lifetime
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US752063A
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Jaroslav Mrkvicka
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Vyzkumny Ustav Matematickych Stroju
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Vyzkumny Ustav Matematickych Stroju
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K15/00—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers
    • G06K15/02—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers
    • G06K15/08—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers by flight printing with type font moving in the direction of the printed line, e.g. chain printers

Definitions

  • One form of digitally controlled line printer employs an endless belt on which rows of successive type characters are suitably embossed.
  • the belt moves periodically past a succession of aligned printing hammers whose spacing determines the column spacing of the printed line.
  • the hammers are selectively actuated to press a pressure-sensitive paper tape against the oppositely disposed type character on the belt and thus provide a corresponding impression on the tape.
  • Each hammer is associated with a predetermined time slot in a recurrent frame of incoming data defined by a plurality of information character codes.
  • the code occurring in each time slot determines the type character that is to be printed in the column defined by the corresponding hammer.
  • Actuation of the printing hammer associated with each time slot occurs in response to a detected identity, in such time slot, of the then occurring information character code and one of a plurality of reference character codes which are respectively representative of the successive type characters on the belt.
  • the latter are generated by a suitable selection circuit actuated in synchronism with the periodic movement of the successive type characters on the belt past a fixed point.
  • selection circuits for moving-belt line printers have been complicated, particularly where the spacing between successive ones of the type characters on each row of the belt is different from the spacing between successive ones of the printing hammers.
  • the present invention provides a relatively simple selection circuit for moving-belt line printers having a type spacing on the belt that is greater than the column spacing of the printed line by a factor K /Q where '70 is a rational number greater than 1 and where P and Q have no common factors.
  • a character generator operating in MODULO-P fashion is coupled to the moving belt for generating P staggered but otherwise identical successions of the reference character codes corresponding to the successive typed characters on the belt.
  • the successions of reference codes are sequentially sampled in successive ones of the frames.
  • a shifting circuit routes each sample through an associated set of time slots of the corresponding frame; a separate set of time slots is assigned to each of the staggered successions of reference character codes.
  • Each identity between a shifted sample and the simultaneously occurring information character code actuates the printing hammer assigned to the time slot in which the identity occurs.
  • FIG. 1 is a block and schematic diagram of a selection circuit for a digitally controlled line printer in accordance with the invention
  • FIG. 2 is a set of waveform diagrams illustrating a frame of time slots coincident with those containing coded information for controlling the line printer of FIG. 1;
  • FIG. 3 is a pictorial diagram of one form of MODULO-P character generator suitable for use in the selection circuit of FIG. 1;
  • FIG. 4 is a set of waveform diagrams for the MODULO-3 character generator of FIG. 3;
  • FIG. 5 is a set of waveform diagrams for a shifting-pulse generator suitable for use with the selection circuit of FIG. 1, illustrating the time relation among the shifting pulses, the frame duration, and the waveforms of FIG. 4;
  • FIG. 6 is a pictorial diagram of an alternative form of character generator for producing the waveforms of FIG. 4.
  • FIG. I illustrates a digitally controlled line printer 10 for printing a line of N type characters (not shown) on a pressure-sensitive paper web 2A.
  • the printing of the line is accomplished with the use of N aligned. solenoid-actuated printing hammers 12-1. 12-2.
  • IZ-N which selectively press the web 2 against an endless moving belt 11 on which axially disposed rows of typed characters -110 to be printed are embossed.
  • the belt 11 is suitably driven by a pair of drive rolls 2IA-21A at constant speed for translational movement parallel to the hammers 12 to periodically move each successive type character through positions directly opposite each of the hammers l2.
  • the solenoids (not shown) of selected hammers 12 are actuated by energizing associated ones of a plurality of individual power supplies 9-1, 9-2, 9-N.
  • the N power supplies 9, in turn, are energized by the application thereto of N command bits which are outpulsed over N channels 14-1, 14-2, l4-N of a serial-to-parallel converter 8.
  • a predetermined state of each command bit eg a binary 1 applied to the associated one of the power supplies 9 will actuate the hammer 12 associated therewith to print the type character on the then-opposed portion of the belt 11.
  • the incoming information which controls the generation of the command bits for each line to be printed may be contained in successive recurrent frames each having a predetermined number of time slots of duration T.
  • Each frame of information is generated by a suitable external source (represented by a computer I00) and stored in serial form in a suitable buffer memory 7 of conventional construction.
  • the buffer 7 may take the form of a delay line having a storage capacity of IT time slots as depicted in FIG. 2, wherein successive frames of the incoming information stored in the buffer may recur at intervals of length Z. Not all of the time slots in the buffer need be employed for information storage; as shown in FIG. 2, for example, the seventh time slot in each frame may be inactive for information storage purposes and may be used to store suitable error checking codes if desired.
  • the identification of an information character code occurring in a particular time slot by the line printer selection circuit will provide the command bit for the associated hammer 12 to print the required type character.
  • the converter 8 is employed to relate the respective time slots to separate the ones of the channels 14 for individually exciting the associated hammer power supplies 9 in the manner described, e.g., in applicants copending application Ser. No. 729,825, filed May 16, I968, and entitled ERROR CHECKING CIRCUIT FOR DIGITALLY CONTROLLED PRINTERS.”
  • the belt 11 is mechanically coupled, as by a link 11A, to a character generator 1.
  • the generator I may illustratively comprise a rotatable disc 15 which makes one revolution for each increment of belt movement equal to the spacing between successive type characters thereon.
  • the disc 15 has a first track 151 that cooperates with a first pickup 161 to provide, during each revolution, an output pulse having a duration proportional to one-third of the spacing between successive type characters on the moving belt 11.
  • Each pulse from the pickup 161 is applied to the input of a MODULO 3-counter 16 having three outputs in the form of staggered but otherwise identical first pulse trains at, B and 7 (FIG. 4).
  • Each of the trains (1,3, 'y has a period T- ⁇ proportional to the belt type spacing, and a pulse duration corresponding to onethird of such spacing.
  • the first pulse trains 01.13, and which appear on output lines 101, I02. and 103 of the counter 16, are applied to separate inputs of a triggcrable character register 17 which provides three staggered but otherwise identi cal successions Da, DB. and D-y (FIG. 4) of reference character codes in respective. synchronism with the pulse trains 'y, B, and a.
  • Each of the reference codes in the successions Da, DB, and D7, which are individually outpulsed over lines 111, 112, and 113 of the register 17, corresponds to (and is represented in FIG. 4 by a line labeled as) one of the successive type characters on the belt 11.
  • the respective successions of reference character codes outpulsed by the generator 1 over the lines 111, 112, and 113 are sampled at the beginning of each frame of information stored on the buffer 7 by means of pulses from a sampling pulse generator 2.
  • the frame length Z may be taken to coincide with the pulse length T 2/3 of each of the trains at, B, and y in the manner shown in FIG. 5.
  • the generator 2 (FIG. 1) may be a MODULO-3 counter of the same general type as the counter 16 of FIG. 3, except that the generator 2 is triggered at time slot intervals T rather than at intervals proportional to T 2/3, as was the case with the counter 16.
  • the generator 2 provides, on output lines 21, 22, and 23, three staggered second pulse trains a, b, and c (FIG. 2) each of which has a pulse length T.
  • the triggering pulses for the generator 2 are obtained from the computer 100 over a line 20.
  • the generator 2 also provides a timing pulse over an output line 24 to define a sampling interval equal to 3T at the beginning of each frame in the manner shown in FIG. 2.
  • the reference code successions Da, DB, and D-y on the lines 111, 112, and 113 are respectively applied to first inputs 411, 421, and 431 of a plurality of sampling gates 41, 42, and 43.
  • the second pulse trains c, b, and a are respectively applied to second inputs 413, 423, and 433 of the gates 41-43.
  • the timing pulse Q is applied in common to third inputs 412, 422, and 432 of the gates 41-43.
  • the samples of the sequences Du, DB, and By are applied, via lines 414, 424, and 434 to inputs 441, 442, and 443 of an OR gate 44.
  • the successive samples at the output of the OR gate 44 are applied to an input 51 of a suitable shift register 5.
  • the register is adapted, in a conventional manner, to store each of the successive samples applied thereto from the OR gate 44 and thereafter, in response to a succession of pulses S (FIG. 5) applied thereto over an integral number of time slots, to shift the stored sample through the number of time slots occupied by the coincident pulse S.
  • the timing of the pulses S shown in FIG. 5 is chosen to suecessively shift each sample through a set of predetermined time slots uniquely assigned to the corresponding one of the reference code successions Dot, DB, and Dy. Such timing is effectively obtained with the use of a shifting pulse generator 3.
  • the latter operates, in the manner described below, on the first and second staggered sets of trains at, B, and 'y and a, b, and 0 applied to inputs 34-36 and 31-33, respectively, of the generator 3.
  • the generator 3 also provides a succession of gating pulses T.
  • the pulses T result from the performance, in the generator 3, of the operation T at: Bh yc and so are complementary to the pulses S,
  • the pulses T are used to selectively open a second gate 55 (FIG. 1) through a control input 552. During each open period of the gate 55, the then-occurring shifted sample in the register 5 is transmitted to a first input 61 of a conventional coincidence decoder 6.
  • the first time slot in the first depicted frame i.e., that corresponding to the pulse duration of the first train a, manifests the absence of a pulse S and the presence of a pulse T.
  • the sample of the reference code sequence Da applied to and stored in the register 5 (FIG. 1) remains unshifted and is directly applied in the first time slot to the coincidence decoder 6 through the now-enabled gate 55. Because of the presence of the pulse S (FIG.
  • samples of the reference code sequence DB are applied, in synchronism with the pulses T, to the input of the coincidence decoder 6 during the second, fifth, eighth etc., active time slots of the frame corresponding to the pulse duration of the sequence DB.
  • samples of the reference sequence D-y are applied to the input of the coincidence decoder during the third, sixth, ninth, etc., active time slots of the frame corresponding to each pulse duration of the sequence D.
  • the printing hammers 12 may be grouped in accordance with the time slots through which the samples of the successive reference code sequences are routed.
  • the hammers associated with the first, fourth, and seventh columns of the line to be printed are controlled by the shifted samples of the sequence Dot.
  • the hammers associated with the second, fifth, eighth, etc. columns are controlled by the shifted samples of the pulse sequence DB; and the hammers corresponding to the third, sixth, ninth, etc. columns are controlled by the shifted samples of the pulse sequence D-y.
  • the sequence of shifted code samples applied to the input 61 (FIG. 1) of the decoder 6 is compared with the information codes in the successive frames stored in the buffer 7 and applied to a second input 62 of the decoder 6.
  • comparison is made between the sample and the coincident information character codes in each of the time slots assigned to the corresponding one of the code sequences Da, DB and D
  • the shifted samples of the sequence Da are suitably compared with the contents of the first, fourth, seventh etc., time slots in the coincident frame of incoming information from the buffer 7.
  • Each coincidence of the shifted sample and the information character code in one of the assigned time slots results in the generation of a command bit which is applied, through the associated channel 14 of the serial-to-parallel converter 8, to the power supply 9 of the associated printing hammer 12.
  • the resulting actuation of the hammer solenoid causes a printout of the type character (on the belt 11) disposed opposite the excited hammer 12. It will be evident that excitation of the hammers associated with the code sequences DB and D may be accomplished in an analogous manner.
  • FIG. 6 An alternative embodiment of the character generator 1 is shown in FIG. 6. This embodiment employs a rotatable disc 13 that is encoded, as by suitable apertures (not shown) thereon,
  • the disc 13 is mechanically coupled. via the link 11A, for rotation once during each movement of the belt ll through the spacing between successive type characters
  • Three pickups 141, 142, and 143 are associated with respective points of the periphery of the disc that are spaced at intervals D.
  • the distance D corresponds to 2/3 of the type spacing on the belt.
  • the pickups l4ll43 respectively outpulse both the staggered first trains a, B and 'y and the correspondingly staggered reference code sequences Du, DB and D'y. Details of the construction of the disc 13 and the pickups l4l-l43 are well known in the art and will not be discussed further here.
  • the ratio of the spacing between successive type characters on the belt 11 and the successive hammers is not restricted to the factor 1.5, but may be any rational number P/Q greater than one, where P and Q have no common factor.
  • the generators l6 and 2 which provide the first and second trains at, B, 'y and a, b, c, operate on a MODULOP basis, with P sampling gates being correspondingly required.
  • the character generator embodiment shown in FIG. 6 would have a spacing D equal to Q/P times the type spacing of the belt 11.
  • an improved apparatus for selectively actuating the printing hammers in response to coded information characters grouped in successive incoming data frames of N active time slots each which comprises:
  • a reference character generator having P outputs for separately providing P similar sequences of reference character codes individually corresponding to the successive types on the carrier, the character generator having P inputs respectively associated with the P outputs, each input being operable when excited for triggering the next reference code in the sequence on the associated output;
  • serial-to-parallel converter coupled to the output of the decoder and having N outputs corresponding to the N time slots of each data frame
  • the generating means comprises, in combination, a disc rotatably coupled to the type carrier, the disc having first and second signal tracks; a first pickup device coupled to the first track for producing, during each revolution of the disc, a pulse having a duration corresponding to of the type spacing on the type carrier; a
  • the MODULO-P counter coupled to the output of the first pickup device; and a second pickup device coupled to the second track for generating an impulse once during each revolution of the disc; and in which the first coupling means comprises means for transmitting the outputs of the MODULO-P counter and the second pickup device to the character generator.
  • the generating means comprises, in combination; a coded disc rotatably coupled to the type carrier, and at least a pair of pickup devices coupled to the periphery of the disc, the angular spacing between the pickups corresponding to Q/P times the distance between adjacent types on the type carrier.
  • an improved apparatus for selectively actuating the printing hammers in response to coded information characters grouped in successive incoming data frames of N active time slots each which comprises:
  • a reference character generator having P outputs for separately providing similar sequences of reference character codes individually corresponding to the successive types on the carrier, the character generator having P inputs respectively asspCiated with the P outputs, each input being operable when excited for triggering the next reference code in the sequence on the associated output;
  • first means coupled to the carrier for generating P first pulse trains in MODULO-P fashion at a rate proportional to the spacing of the successive types on the carrier;
  • each second means operative in synchronism with each time slot in a data frame for generating P second pulse trains in MODULO-P fashion, each second pulse train having a pulse length equal to that of a time slot;
  • storage means including a shift register coupled to the output of the OR gate and having a control input, the presence of a pulse in a given time slot at the control input causing the register to shift to the next succeeding time slot;
  • a normally disabled second gate coupled to the output of the storage means and having a control input
  • a coincidence decoder having first and second inputs; 5 2 means for coupling the output of the second gate to the first input of the decoder;

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US752063A 1967-08-10 1968-08-12 Print hammer selection circuit in endless belt line printers Expired - Lifetime US3561354A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3691947A (en) * 1971-05-13 1972-09-19 Ibm Hammer control for chain printer
US3728684A (en) * 1970-08-05 1973-04-17 Honeywell Inc Dynamic scanning algorithm for a buffered printer
US3810195A (en) * 1970-05-21 1974-05-07 Potter Instrument Co Inc Helical bar printer logic circuitry
US3936802A (en) * 1972-09-05 1976-02-03 Societe Industrielle Honeywell Bull Control device for recording elements

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3066601A (en) * 1959-12-29 1962-12-04 Ibm Error checking devices
US3289576A (en) * 1964-12-02 1966-12-06 Ibm High speed printer with variable cycle control
US3303775A (en) * 1963-09-20 1967-02-14 Ibm Variable speed printer apparatus and type carrier device therefor
US3312174A (en) * 1965-12-23 1967-04-04 Ibm Variable cycle control system for a high speed printer
US3443514A (en) * 1967-05-17 1969-05-13 Potter Instrument Co Inc Print hammer timing and energizing means in high speed printers

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3066601A (en) * 1959-12-29 1962-12-04 Ibm Error checking devices
US3303775A (en) * 1963-09-20 1967-02-14 Ibm Variable speed printer apparatus and type carrier device therefor
US3289576A (en) * 1964-12-02 1966-12-06 Ibm High speed printer with variable cycle control
US3312174A (en) * 1965-12-23 1967-04-04 Ibm Variable cycle control system for a high speed printer
US3443514A (en) * 1967-05-17 1969-05-13 Potter Instrument Co Inc Print hammer timing and energizing means in high speed printers

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3810195A (en) * 1970-05-21 1974-05-07 Potter Instrument Co Inc Helical bar printer logic circuitry
US3728684A (en) * 1970-08-05 1973-04-17 Honeywell Inc Dynamic scanning algorithm for a buffered printer
US3691947A (en) * 1971-05-13 1972-09-19 Ibm Hammer control for chain printer
US3936802A (en) * 1972-09-05 1976-02-03 Societe Industrielle Honeywell Bull Control device for recording elements

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