US3834306A - Print density control - Google Patents

Print density control Download PDF

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Publication number
US3834306A
US3834306A US00344666A US34466673A US3834306A US 3834306 A US3834306 A US 3834306A US 00344666 A US00344666 A US 00344666A US 34466673 A US34466673 A US 34466673A US 3834306 A US3834306 A US 3834306A
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United States
Prior art keywords
print
pulses
subscan
pulse
hammer
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00344666A
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English (en)
Inventor
R Gilbert
M Hryck
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International Business Machines Corp
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International Business Machines Corp
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Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Priority to US00344666A priority Critical patent/US3834306A/en
Priority to IT19660/74A priority patent/IT1003481B/it
Priority to DE2405315A priority patent/DE2405315C2/de
Priority to FR7405841A priority patent/FR2223194B1/fr
Priority to CA193,591A priority patent/CA1019249A/en
Priority to JP2244874A priority patent/JPS5330573B2/ja
Priority to GB1086874A priority patent/GB1436992A/en
Application granted granted Critical
Publication of US3834306A publication Critical patent/US3834306A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J9/00—Hammer-impression mechanisms
    • B41J9/44—Control for hammer-impression mechanisms
    • B41J9/48—Control for hammer-impression mechanisms for deciding or adjusting hammer-drive energy

Definitions

  • ABSTRACT Print hammers in a printer are energized from a source of electrical energy whose voltage may vary.
  • the motor driving the type carrier is energized from an oscillator whose frequency is caused to vary with the voltage of the print hammer source to prevent misregistration between the print hammers and the type characters on the type carrier.
  • the duration of the pulses energizing the print hammers is controlled by print scan pulses derived from timing marks on the type carrier to provide constant print density.
  • PRINT DENSITY CONTROL BACKGROUND OF THE INVENTION 1.
  • the invention relates generally to printers and it relates in particular to printers having continuously moving type carrying elements and print hammers which are operated by electromagnets from a source whose voltage may vary.
  • Another object of the invention is to utilize print scan pulses derived from an emitter of a type carrier which is driven at varying speeds with source voltage variations for controlling the duration of the pulses firing the print hammers of a printer.
  • Yet another object of the invention is to provide for using subscan pulses which are used to scan predetermined sub groups of print positions in sequence and impression control pulses derived from the same clock pulses as the subscan pulses to provide print hammer firing pulses which are a rational multiple of the subscan pulses.
  • FIG. 1 is a schematic block diagram of a printer control system embodying the invention in one of its forms.
  • FIG. 2 is a schematic circuit diagram of logic circuitry which may be used in the pulse control circuit of FIG. 1.
  • FIG. 3 is a schematic block circuit diagram of the motor control circuit of FIG, 1 and FIG. 4 shows timing curves illustrating the timing relations of the circuitry in FIGS. 1 and 2 for different motor speeds.
  • the reference numeral 10 denotes generally a high-speed printer apparatus of the type generally described in Pat. No. 2,993,437 which issued to F. M. Demer et al. on July 25, 1961 and has been modified for use with the present invention.
  • a type cartridge 11 comprising an endless band 12 having a plurality of type characters 13 thereon is mounted between spaced apart wheels 14 and 15 for movement past a plurality of print positions along a'print line on a document or form 22 upon which a printing operation is to be performed.
  • a plurality of print hammers 20 is positioned one in each position along the print line for impacting the document 22 and a ribbon 24 against selected type characters 13 as they pass the different print positions.
  • Timing marks 16 are provided on the band 12 which are scanned by a transducer 18 and used for producing timing signals for use in the control system.
  • Information to be printed is stored in a print line buffer 26 which is scanned by the usual X drivers 28 and Y drivers 30 under the control of a X ring 32 and a Y ring 33 as described inthe Demer, et al patent.
  • a subcycle gating ring 34 is provided so that the print positions are scanned in a predetermined spaced order as described in the Demer, et al patent.
  • patent stages 2, 3 and 1 of the subcycle gating ring may be used in that order with the stages being shifted one position to gate a pulse control system 40 for controlling the actual firing of selected ones of the print hammers 20 simultaneously for each subcycle, through hammer drivers 21 from a source of electrical energy +V, on the following subcycle.
  • the hammer select circuit 175 is used to set select ones of a plurality of latches 36 which are connected through AND circuits 38 to the different print hammers 20.
  • the AND circuits 38 are gated in subcycle groups by the pulse control circuit 40 under the control of the subcycle gating ring 34 for actually firing the print hammers 20 g which are selected during the previous subcycle.
  • the type belt or band 12 is operated by means of a motor 44 which is connected in driving relation with the pulley 14 and is energized through a motor control circuit 46 also connected to the source +V through conductors 28.
  • the motor 44 may comprise a stepping motor which is operated by means of pulses applied to the operating windings thereof.
  • the stepping motor 44 may be of the type described in the article entitled Characteristics of a Synchronous Conductor Motor by Arthur E. Snowdon and Elmer W. Madsen published in Applications and Industry, March, 1962, being the subject of paper 61-650 recommended by the AIEE Industrial Control Committee and approved by the AIEE Technical Operations Department for presentation at the AIEE Northeastern District Meeting, Hartford, Conn., May 17-19, 1961.
  • Such a motor has a speed proportional to the rate at which pulses are applied to it and is normally substantially unaffected by variations in the value of the source voltage.
  • the motor control circuit 46 comprises a pair of triggers 48A and 483 connected to operate as a binary counter in response to input pulses from an oscillator 50.
  • the oscillator 50 is of a voltage sensitive type so that the frequency of the oscillator varies with the voltage of the energizing source.
  • the outputs of the triggers 42A and 42B are connected to AND circuits 52A, 52A, 52B and 523 which are connected to the terminals A, A, B and B of the motor 44 respectively. Accordingly when the frequency of the oscillator 50 varies with voltage variations, the speed of operation of the triggers 48A and 48B will vary accordingly as will also the speed of the motor 44.
  • a logic circuit is shown for use in the pulse control circuit 40 of FIG. 1.
  • One such logic control circuit is used for each of the three subscans so that the description hereinafter will be limited to one such circuit.
  • a pair of triggers 56 and 58 are shown connected generally in a cascade relation with the trigger 56 being connected for example to stage 2 f the subcycle gating ring 34 at the D input.
  • the same input signal is applied through an inverter 60 to the set terminal S of the trigger 58, and impression control single shot 62, the timing of which is controlled by the potentiometer 42 is connected to the transducer 18 through conductor 185 and the output thereof is applied as clock pulses to the CL terminals of the triggers 56 and 58, the signal being applied through an inverter 64 to the trigger 58.
  • the reset terminals R of the two triggers may be connected to a source of DC reset and the Q output of the trigger 58 being used to fire the print hammers of its subscan group.
  • the triggers 56 and 58 may be of the general type known as D-type edge-triggered flip-flops.
  • the triggers are set by a negative going signal applied to the S set terminal and are reset by the application of-a negative going signal to the R or resetterminal.
  • the state of the D input existing immediately prior to the rising of a clock pulse applied to the CL or clock terminal is transferred to the Q output when the clock signal rises.
  • the configuration of D flip-flops or triggers shown in FIG. 2 will produce an output pulse duration at the Q terminal of flip-flop 58 which is a function of the subscan time applied to the D input and the duration of an impression control single shot pulse applied to the CL clock input from the impression control single shot 62.
  • the hammer fire pulse duration T is equal to 1.5 times the subscan period T, plus the single shot time T
  • a subscan time (n) is produced which is equal in duration to the period of the subscan pulses T from the printer emitter l8.
  • Subscan n time is the D input to flip-flop 56.
  • the inversion of subscan n is the set input to flip-flop 58.
  • the impression control single shot 62 is fired at the center of each subscan period (/2 p), being fired on the negative going edge of each subscan pulse.
  • the print line buffer 26 of FIG. 1 is scanned by the X drivers and the Y drivers under the control of the subcycle gating ring 34 to provide three separate subscans of all print positions with print positions 1, 4, 7, 10, etc. being scanned in the first subscan, and print positions 2, 5, 8, 11, etc. being scanned in the second subscan, while print positions 3, 6, 9, and 12, etc. are scanned in the third or last subscan.
  • the hammer select circuit sets the different hammer latches 36 in response to a compare between a character contained in the print line buffer 26 for a given print position and a character on the type chain 12 in that position.
  • the pulse control circuit 40 operates to gate the output of the selected latches 36 through the ANDs 38 to fire the selected print hammers 20.
  • the pulse generation of the gating pulses applied to the ANDs 38 by the pulse control circuit 40 will be a function of the length of the individual print subscans and the duration of the impression control single shot pulse.
  • curves a-i illustrate respectively, d-c reset, subscan pulse from the transducer 18, impression control single shot pulse from single shot 62, subscan n or 2 stage pulse from the subscan ring 34, the subscan n+1 pulse or 3 stage pulse from the ring 34, the inverted subscan n pulse, from inverter 60, the inverted single shot pulse from inverter 64, the fire n output from flip-flop 58 and the Q, output of flip-flop 56 with the motor 44 driving the type belt 13 at normal speed.
  • the voltage of the source +V from which the print hammer drivers 21 are energized drops, the time required for the print hammer to impact the document 22 is increased.
  • the frequency of the oscillator 50 is reduced and the triggers 48A and 48B drive the stepping motor at a slower rate.
  • the subscan pulses from transducer 18 are stretched out as shown at b and the pulses C from the impression control single shot 62 commence later (their length is a function of the setting of the potentiometer 42 in accordance with the thickness of the form or document).
  • the subscan n pulse d, from ring 34 is stretched, and accordingly the duration of the fire n pulse h is increased so that the product of the reduced voltage applied to the print hammers and the pulse width remains substantially constant, thereby regulating the print hammer force and the print intensity.
  • the pulse control circuit 40 will supply the printer with the correct hammer fire pulse width which is derived from the two basic signals provided by the printed electronics.
  • the first of these signals is the print subscan pulse which is derived from the timing marks 16 on the print element 12.
  • the period of these pulses is proportional to the velocity of the print element 12.
  • the second signal is the output of the impression con- 2 trol single shot 62.
  • This single shot is fired during every subscan time and its pulse width is porportional to the forms thickness.
  • the using system must process these signals to develop separate but equal firing times T, with pulse width equal to the impression control single shot time T, 1 /2 subscans T,,.
  • the single shot duration is fixed for a given form thickness but the subscan period varies with print element velocity. This results in a fire pulse width duration consistent with maintaining print density.
  • Nominal subscan time T is 710 microseconds.
  • Nominal hammer fire pulse width equals 1,200 microseconds for one and two part, 1,300 microseconds for three part and 1,450 microseconds for 4 and 6 part.
  • the velocity of the print element is varied plus or minus 5% for a power supply variation of plus or minus 10%. Therefore, the variation of pulse duration to maintain constant print force is between plus or minus 4.4% for one part and plus or minus 4.0% for six part forms. This has been successfully demonstrated to maintain nearly constant print density over the allowable range of power supply voltage variation.
  • a new and novel printer control circuit is provided utilizing a variation in the speed of the driving motor for the type cartridge with changes of voltage applied to the print hammers to maintain registration between the type characters and the print hammers.
  • the variable length of subscan pulses produced by the variation in speed of the type carrier is utilized to vary the duration of the pulses applied to the print hammers so that the product of voltage and time tends to remain constant thus maintaining a substantially constant hammer print force to minimize print density variations.
  • a printer having a plurality of print hammers with firing means disposed to be energized from a source of electrical energy and a type carrier with a plurality of type characters movable past said print hammers, means for storing data to be printed in each of a plurality of print positions corresponding to said print hammers, means'for determining the character at a particular hammer position, and means for addressing said storage means and comparing the data in storage for the particular hammer position with the character on the carrier at said particular position and generating a print compare signal when they are the same to effect operation of a selected one of said print hammers, the improvement in hammer timing logic comprising:
  • means including a variable speed motor driving said type carrier to move said type characters past said print hammers,
  • pulse means including a transducer connected in operating relation with said type carrier to produce subscan pulses which vary in duration in response to changes in the speed of said type carrier and connected to address said storage means and effect energization of said print hammers in response to said print compare signal said variable duration subscan pulses thus controlling the duration of energization of said print hammer firing means in response to variations in the voltage of saidsource.
  • pulse means including an impression control single shot connected to said transducer and controlled by pulses from said transducer with said impression control single shot being connected so that its output pulse is cumulative with said subscan pulses.
  • pulse means including a multi-stage counter producing said subscan pulses and bistable means connected to both said subscan counter and said print hammers to provide a print hammer firing pulse which is a rational multiple of said subscan pulses.
  • the invention as defined in claim 4 characterized by a thickness control circuit connected to said impression control single shot whereby said single shot has a duration controlled in accordance with the thickness of the document being printed on.
  • bistable means comprising a pair of flip-flops connected in cascade to said multi-stage counter and said impression control single shot so as to be selectively controlled by said subscan pulses and said impression control pulses to provide a print hammer energizing pulse which'is a rational multiple of said subscan pulses and said impression control single shot having a controlled duration additive with respect to said rational multiple.

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  • Impact Printers (AREA)
US00344666A 1973-03-26 1973-03-26 Print density control Expired - Lifetime US3834306A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US00344666A US3834306A (en) 1973-03-26 1973-03-26 Print density control
IT19660/74A IT1003481B (it) 1973-03-26 1974-01-23 Stampatrice perfezionata
DE2405315A DE2405315C2 (de) 1973-03-26 1974-02-05 Schaltungsanordnung für die Steuerung der Anschlagstärke von Druckhämmern
FR7405841A FR2223194B1 (enrdf_load_stackoverflow) 1973-03-26 1974-02-13
CA193,591A CA1019249A (en) 1973-03-26 1974-02-27 Print density control
JP2244874A JPS5330573B2 (enrdf_load_stackoverflow) 1973-03-26 1974-02-27
GB1086874A GB1436992A (en) 1973-03-26 1974-03-12 Selective printer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00344666A US3834306A (en) 1973-03-26 1973-03-26 Print density control

Publications (1)

Publication Number Publication Date
US3834306A true US3834306A (en) 1974-09-10

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ID=23351467

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Application Number Title Priority Date Filing Date
US00344666A Expired - Lifetime US3834306A (en) 1973-03-26 1973-03-26 Print density control

Country Status (7)

Country Link
US (1) US3834306A (enrdf_load_stackoverflow)
JP (1) JPS5330573B2 (enrdf_load_stackoverflow)
CA (1) CA1019249A (enrdf_load_stackoverflow)
DE (1) DE2405315C2 (enrdf_load_stackoverflow)
FR (1) FR2223194B1 (enrdf_load_stackoverflow)
GB (1) GB1436992A (enrdf_load_stackoverflow)
IT (1) IT1003481B (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4037208A (en) * 1976-05-03 1977-07-19 Xerox Corporation Hammer intensity selection apparatus for serial printer
US4353656A (en) * 1980-10-14 1982-10-12 Xerox Corporation Moving coil, multiple energy print hammer system including a closed loop servo
US4743821A (en) * 1986-10-14 1988-05-10 International Business Machines Corporation Pulse-width-modulating feedback control of electromagnetic actuators

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL177294C (nl) * 1977-11-03 1985-09-02 Philips Nv Drukker, voorzien van een slaginrichting met opnemer.
JPS5910315B2 (ja) * 1978-04-06 1984-03-08 株式会社リコー 衝撃型プリンタの印字ハンマ−駆動制御装置
IT1159898B (it) * 1978-07-13 1987-03-04 Olivetti & Co Spa Dispositivo di stampa per macchina per scrivere o simili macchine per ufficio
US4286516A (en) * 1979-10-15 1981-09-01 Burroughs Corporation Electronic control for timing hammers in impact printers
US4384520A (en) * 1980-09-16 1983-05-24 Hitachi Koki Company, Limited Device for controlling solenoids of high speed printer
DE3414355A1 (de) * 1984-04-16 1985-10-24 Videoton Elektronikai Vállalat, Székesfehérvár Verfahren zur steuerung der druckhaemmer von zeilendruckern sowie schaltungsanordnung zur durchfuehrung des verfahrens

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3172353A (en) * 1963-06-17 1965-03-09 Data Products Corp Variable force hammer high speed printer
US3366044A (en) * 1965-07-22 1968-01-30 Anelex Corp Demand controlled print rate equalizer for high speed printers
US3467005A (en) * 1968-04-29 1969-09-16 Collins Radio Co Printer hammer drive circuit
US3513774A (en) * 1968-07-01 1970-05-26 Ibm Printer hammer compensation
US3573589A (en) * 1969-04-01 1971-04-06 Burroughs Corp Position servo system for a motor including detenting at destination
US3575107A (en) * 1969-06-02 1971-04-13 Gen Electric Underspeed and undervoltage protection for printer
US3636867A (en) * 1969-06-28 1972-01-25 Honeywell Inf Systems Print timing and speed control circuit for high-speed printers

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL135490C (enrdf_load_stackoverflow) * 1959-10-05
US3183830A (en) * 1960-12-27 1965-05-18 Rca Corp Print registration control means in high speed printers
US3866533A (en) * 1972-12-26 1975-02-18 Ibm Electrical print impression control
US3842736A (en) * 1973-03-05 1974-10-22 Ibm Print hammer registration control

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3172353A (en) * 1963-06-17 1965-03-09 Data Products Corp Variable force hammer high speed printer
US3366044A (en) * 1965-07-22 1968-01-30 Anelex Corp Demand controlled print rate equalizer for high speed printers
US3467005A (en) * 1968-04-29 1969-09-16 Collins Radio Co Printer hammer drive circuit
US3513774A (en) * 1968-07-01 1970-05-26 Ibm Printer hammer compensation
US3573589A (en) * 1969-04-01 1971-04-06 Burroughs Corp Position servo system for a motor including detenting at destination
US3575107A (en) * 1969-06-02 1971-04-13 Gen Electric Underspeed and undervoltage protection for printer
US3636867A (en) * 1969-06-28 1972-01-25 Honeywell Inf Systems Print timing and speed control circuit for high-speed printers

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4037208A (en) * 1976-05-03 1977-07-19 Xerox Corporation Hammer intensity selection apparatus for serial printer
US4353656A (en) * 1980-10-14 1982-10-12 Xerox Corporation Moving coil, multiple energy print hammer system including a closed loop servo
US4743821A (en) * 1986-10-14 1988-05-10 International Business Machines Corporation Pulse-width-modulating feedback control of electromagnetic actuators

Also Published As

Publication number Publication date
DE2405315C2 (de) 1982-09-23
IT1003481B (it) 1976-06-10
FR2223194A1 (enrdf_load_stackoverflow) 1974-10-25
GB1436992A (en) 1976-05-26
DE2405315A1 (de) 1974-10-17
JPS5330573B2 (enrdf_load_stackoverflow) 1978-08-28
JPS503230A (enrdf_load_stackoverflow) 1975-01-14
FR2223194B1 (enrdf_load_stackoverflow) 1976-12-03
CA1019249A (en) 1977-10-18

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