EP0541064A2 - Module de tête d'impression thermique - Google Patents

Module de tête d'impression thermique Download PDF

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Publication number
EP0541064A2
EP0541064A2 EP92118896A EP92118896A EP0541064A2 EP 0541064 A2 EP0541064 A2 EP 0541064A2 EP 92118896 A EP92118896 A EP 92118896A EP 92118896 A EP92118896 A EP 92118896A EP 0541064 A2 EP0541064 A2 EP 0541064A2
Authority
EP
European Patent Office
Prior art keywords
printer
print
print head
head unit
correction
Prior art date
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.)
Withdrawn
Application number
EP92118896A
Other languages
German (de)
English (en)
Other versions
EP0541064A3 (en
Inventor
Steven J. c/o EASTMAN KODAK COMPANY Sasson
Donald J. c/o EASTMAN KODAK COMPANY Hodge
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Kodak Co
Original Assignee
Eastman Kodak Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
Publication of EP0541064A2 publication Critical patent/EP0541064A2/fr
Publication of EP0541064A3 publication Critical patent/EP0541064A3/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/315—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material
    • B41J2/32—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads
    • B41J2/35—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of heat to a heat sensitive printing or impression-transfer material using thermal heads providing current or voltage to the thermal head
    • B41J2/355—Control circuits for heating-element selection
    • B41J2/36—Print density control
    • 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
    • B41J25/00—Actions or mechanisms not otherwise provided for
    • B41J25/34—Bodily-changeable print heads or carriages

Definitions

  • This invention relates to a thermal printer, and more particularly to a removable thermal print head unit with integral compensation to correct for non-uniformity in the multiple resistance heating elements of the head unit by means of a low cost, easily programmable permanent memory device.
  • thermal printer employs a thermal head assembly comprising a multitude of closely spaced resistance heating elements which are separately energized to print very small dots or pixels from a thermally reactive dye element onto a print medium or page, in accordance with input data.
  • the data is in the form of binary words (e.g., 8-bit words) which define each of the positions and densities of the respective pixels being printed, and the characters or image so defined.
  • the printed pixels should be very small and have a nearly uniform tone scale over a wide range of densities.
  • a thermal head assembly is typically a linear, one-dimensional array of thick (or thin) film resistance heating elements individually formed on a ceramic substrate which is then mounted on a heat sink, such as a metal bar.
  • print heads with 300 miniature heating elements per lateral inch (2400 elements for an 8 inch wide page) are commonly used. These elements are small enough to give a good degree of visual sharpness. However, minor variations in the printing action of these individual print elements give rise to visually objectionable non-uniformity (for a supposed equal density) in the pixels across a line on a page being printed. This non-uniformity manifests itself in visible lines, streaks and bands in a direction parallel to page motion past the thermal head.
  • the present invention provides a simple and cost effective solution to this problem.
  • the invention provides for permanent and unique calibration of each print head assembly unit so that any calibrated head unit may readily be used with any printer. There is no need for further calibration of a particular head unit when it is installed in a given printer.
  • the invention also simplifies and makes more efficient the head unit manufacturing and testing operation in the first place, as well as the final assembly of a complete printer.
  • a physically separable print head unit for a thermal printer comprising a multi-element resistance print head, a mounting base, and an electronically erasable programmable read only memory (EEPROM) device. These members are put together as an integral but separable unit of an overall printer.
  • the head unit is tested and the individual heating elements of the head are energized to determine the respective printing characteristic of each element.
  • Actual print data thus acquired are fed into a computer which in turn calculates the compensation data (correction numbers) corresponding to each heating element so that each and every element prints with a uniform density when energized by the same data word calling for such density.
  • each print head unit is made identical, for all intents and purposes, to all other such head units being produced.
  • the EEPROM device incorporated into each print head unit can be a relatively slow, hence inexpensive, device.
  • the correction numbers permanently stored in the EEPROM device are outputted to the high-speed correction circuitry of an associated thermal printer when it is powered-up. This process which may take a number of seconds.
  • the correction numbers in the EEPROM device can be serially fed at very slow speed into the memory portion of the high speed printing correction circuitry of the printer.
  • the cost of the EEPROM device used in accordance with the present invention is relatively low because such a device is not directly in the high-speed data path of the thermal printer and hence need not have high speed capability.
  • the correction numbers from the EEPROM unit can be serially outputted at very slow speed, this being done when power to the printer is first turned on (the various other elements and circuits of the printer take some time to reach equilibrium).
  • the EEPROM device itself is in the form of a simple 8-pin dual-in-line (DIP) package which in turn occupies only a minimum of circuit board space.
  • DIP dual-in-line
  • the correction numbers stored in the EEPROM device need only a limited range of numbers to achieve nearly exactly uniform compensation.
  • a data word to be printed as a pixel by the thermal printer may have a range of 0 to 255 (8-bits)
  • the range of compensation for the individual heating elements of the print head may require only numbers with a range of 0 to 63 (6-bits).
  • a single, low cost EEPROM with 2048 "byte" positions (8-bit) has more than enough single-bit positions to store the necessary 6-bit correction numbers (6x2400 or 14,400) when read out serially by appropriate circuitry.
  • FIG. 1 there is shown in schematic form, partly in phantom, a thermal printer 10.
  • the printer 10 comprises a drum 12 adapted to support a thermal print medium (not shown) and to move the medium past a print head unit, indicated at 14.
  • the drum 12 is mounted within a housing and frame 16 (shown in dashed outline) for rotation as indicated by a curved arrow 18.
  • the print head unit 14 is mounted on the frame 16 by means (not shown) in fixed relation closely adjacent to the drum 12.
  • the print head unit 14, which will be described in more detail in connection with FIG. 2, is shown here in FIG. 1 electrically connected by a cable-connector 20 to a circuit module 22.
  • Mounted within the module 22 (but not shown here) are various data and control circuits (to be described shortly) of printer 10.
  • the print head unit 14 is easily separated physically and electrically from the other elements of the printer 10.
  • the print head unit 14 is schematically shown here as being physically and electrically separated from the remainder of the printer 10.
  • the print head unit 14 is shown upside down here for the sake of illustration.
  • An end 20a of the electrical cable-connector 20 (shown here in dashed outline) is a permanent part of the print head unit 14.
  • Another end 20b of the cable-connector 20 is a permanent part of the circuit module 22.
  • the print head unit 14 comprises a mounting board (base) 30 to which a multi-element thermal print head 32 is affixed.
  • the print head 32 has a large number of thermal heating elements 34-1 through 34-n (not shown to scale) which are adapted to print across a page of a print medium a like number of individual closely spaced printed pixels shown schematically as 36-1 through 36-n (not to scale).
  • the construction and operation of the print head 32 and its respective resistive elements 34-1 through 34-n may be as described in the above-mentioned U.S. Patent No. 4,827,279.
  • a memory device 38 which advantageously is an electronically erasable programmable read only memory (EEPROM) device.
  • EEPROM electronically erasable programmable read only memory
  • This memory device 38 installed as an integral part of the print head unit 14, permanently accompanies a particular print head 32 (identified by date and serial number) and provides electrical print compensation data unique to that print head unit 14. If desired, there may also be mounted on the base 30 of the unit 14, head driver circuitry 40 for electrically powering the individual heating elements 34-1 through 34-n of the head 32 in accordance with print data sent from the circuit module 22.
  • a separate computer 44 Shown to the right of print head unit 14, though not part of it, is a separate computer 44 which is employed as follows. Actual head print data derived from density measurements of the printed pixels 36-1 through 36-n are applied to the computer 44 as indicated by the dashed line 46. Based on these actual data, the computer calculates respective print compensating data corresponding to each of the resistance elements 34-1 through 34-n of the head 32. These compensating data, in the form of binary correction numbers are then, as indicated by the dashed line 48, loaded into and permanently stored in the EEPROM device 38 which is an integral part of the head unit 14. The calculation of the correction numbers may be as described in the above mentioned U.S. Patent No. 4,827,279.
  • correction numbers are respective to each of the resistance elements 34-1 through 34-n of the print head 32.
  • This set of correction numbers (unique to a given head unit 14), are subsequently entered automatically into and used in the high speed memory and correction circuits of a printer 10.
  • These correction numbers and the respective circuits substantially eliminate non-uniformity in the printing action of the individual resistance heating elements 34-1 through 34-n irrespective of which one of many print head units 14 is used with a given printer 10. There is no need for subsequent adjustment of the printer when a different print head unit 14 is installed.
  • the print head unit 14 contains the end 20a of the cable- connector 20 shown in FIG. 1.
  • cable-connector 20 shown here in FIG. 2 in dashed outline
  • the head unit 14 mounted for operation in the printer 10 see FIG. 1
  • electrical connections are made to the circuit module 22.
  • the circuit module 22 need not be removed from the printer 10 and is shown in FIG. 2 for the purpose of illustration.
  • the circuit module 22 contains (as shown in FIG. 2 in block diagram form) a correction circuit and data memory (CCDM) unit 50, a data processor 52, an image data unit 54, and a power supply unit 56.
  • CCDM correction circuit and data memory
  • the set of correction numbers from the EEPROM device 38 (when the print head unit 14 is installed in the printer 10), are applied via a buss 57 running from the EEPROM device 38, through the cable-connector 20 (shown in FIG. 2 in dashed outline), to the CCDM unit 50.
  • the loading of the correction numbers into the CCDM unit 50 is initiated when the power to the printer 10 is turned on. This is schematically illustrated by an on-off switch 58 connecting the power supply 56 to an input terminal 60 connected to an external power source (not shown). Another input power terminal 62 is connected to the external power source and directly to the power supply 56.
  • a lead 64 running from the power supply 56, through the cable-connector 20, to the EEPROM device 38 supplies an energizing signal to the device 38 and enables it to load its permanently stored correction numbers into the CCDM unit 50. Circuits in the CCDM unit 50 permit the respective correction numbers from the EEPROM device 38 to be sent serially via the buss 57 at low speed and loaded into appropriate memory positions in the high speed CCDM unit 50. Image data from the image data unit 54 are fed into the data processor unit 52 which in turn sends data to be printed to the CCDM unit 50. The printer 10 then operates with electronic print compensation (i.e., the print head 32 prints with a high degree of print pixel uniformity) in the way described in the above mentioned U.S. Patent No. 4,827,279.
  • FIG. 3 there is shown a graph of print pixel density corresponding to the numbered head elements 34-1 through 34-n.
  • the line 70 is a plot of the actual densities of the print pixels 36-1 through 36-n as printed by the respective head elements 343-1 through 34-n for the same energizations of each of the head elements. It will be seen that the line 70 runs slightly above and below a dashed line 72, which indicates a desired uniform density level. However, actual densities plotted along the line 70 deviate only slightly from the uniform density level line 72 and these deviations are much less than the total density range indicated along the ordinate axis.
  • a correction number for each head element to compensate for the deviation of its printed pixel from the desired density level indicated by the line 72 is much smaller than a data number for the full range of densities.
  • the full range of densities indicated from "0" to maximum in FIG. 3 is represented by an 8-bit number (data word)
  • a correction number may be represented by a 6-bit number for the small magnitudes of the deviations between the values along the line 70 and the level, uniform line 72.
  • the embodiment of the printing apparatus described herein is illustrative of the general principles of the invention. Modifications may readily be devised by those skilled in the art without departing from the spirit and scope of the invention.
  • the invention is not limited to the use of a particular EEPROM device or to just one device.
  • data numbers other than 8-bit words and correction numbers other than 6-bit words may be used.
  • the print head 32 is not limited to a particular number of heating elements per inch or to a particular page width.

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  • Electronic Switches (AREA)
EP19920118896 1991-11-04 1992-11-04 Thermal print head unit Withdrawn EP0541064A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US78781091A 1991-11-04 1991-11-04
US787810 1991-11-04

Publications (2)

Publication Number Publication Date
EP0541064A2 true EP0541064A2 (fr) 1993-05-12
EP0541064A3 EP0541064A3 (en) 1993-07-21

Family

ID=25142574

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920118896 Withdrawn EP0541064A3 (en) 1991-11-04 1992-11-04 Thermal print head unit

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EP (1) EP0541064A3 (fr)
JP (1) JPH07186430A (fr)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0626266A2 (fr) * 1993-05-27 1994-11-30 Canon Kabushiki Kaisha Appareil d'enregistrement commandé par les caractéristiques de la tête et méthode d'enregistrement
EP0626268A2 (fr) * 1993-05-27 1994-11-30 Kabushiki Kaisha TEC Imprimante avec unité d'impression détachable
EP0765762A1 (fr) * 1995-09-27 1997-04-02 Lexmark International, Inc. Circuit pour l'identification d'une tête d'imprimante à jet d'encre, avec une connexion sérielle et un registre à décalage dynamique
EP0878305A2 (fr) * 1997-05-14 1998-11-18 Hewlett-Packard Company Cartouche remplaçable pour une imprimante comprenant une mémoire interne avec des données de déclenchement de message mémorisées
US6022094A (en) * 1995-09-27 2000-02-08 Lexmark International, Inc. Memory expansion circuit for ink jet print head identification circuit
EP1017569A4 (fr) * 1997-02-10 2000-07-12 Datacard Corp Module a tete d'impression thermique et son procede d'utilisation
US6382764B1 (en) * 1994-07-29 2002-05-07 Canon Kabushiki Kaisha Printing method and apparatus for counting number of ejected ink droplets for controlling printhead recovery
FR2840559A1 (fr) * 2002-06-05 2003-12-12 A P S Engineering Module d'impression thermique equipe de moyens de securisation a l'encontre d'un raccordement defectueux entre des connecteurs equipant le module et la machine prevue pour etre equipee de ce module
CN100384636C (zh) * 2004-10-28 2008-04-30 三星电子株式会社 热敏打印机
US7948512B2 (en) * 2008-03-05 2011-05-24 Sharp Kabushiki Kaisha Image forming apparatus with separate controllers for independently controlling an irradiating section
US7998294B2 (en) * 2008-02-27 2011-08-16 Seiko Instruments Inc. Label manufacturing method and label manufacturing system
WO2011129881A1 (fr) * 2010-04-12 2011-10-20 Marozzi, John Tête d'impression améliorée à transfert thermique et système d'impression utilisant une telle tête d'impression
EP3150387A4 (fr) * 2014-05-26 2018-01-31 Sato Holdings Kabushiki Kaisha Imprimante

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3820927A1 (de) * 1987-06-22 1989-01-05 Minolta Camera Kk Thermodruck-aufzeichungsgeraet mit mehrtonwiedergabe
EP0421806A2 (fr) * 1989-10-05 1991-04-10 Canon Kabushiki Kaisha Appareil de formation de l'image
WO1991014577A1 (fr) * 1990-03-29 1991-10-03 Dowty Maritime Limited Dispositif d'enregistrement thermique

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3820927A1 (de) * 1987-06-22 1989-01-05 Minolta Camera Kk Thermodruck-aufzeichungsgeraet mit mehrtonwiedergabe
EP0421806A2 (fr) * 1989-10-05 1991-04-10 Canon Kabushiki Kaisha Appareil de formation de l'image
WO1991014577A1 (fr) * 1990-03-29 1991-10-03 Dowty Maritime Limited Dispositif d'enregistrement thermique

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0626268A2 (fr) * 1993-05-27 1994-11-30 Kabushiki Kaisha TEC Imprimante avec unité d'impression détachable
EP0626268A3 (fr) * 1993-05-27 1995-07-26 Tokyo Electric Co Ltd Imprimante avec unité d'impression détachable.
EP0626266A3 (fr) * 1993-05-27 1995-11-22 Canon Kk Appareil d'enregistrement commandé par les caractéristiques de la tête et méthode d'enregistrement.
US5786828A (en) * 1993-05-27 1998-07-28 Tokyo Electric Co., Ltd. Detachable print unit having updatable condition memory and printer using the same
EP0626266A2 (fr) * 1993-05-27 1994-11-30 Canon Kabushiki Kaisha Appareil d'enregistrement commandé par les caractéristiques de la tête et méthode d'enregistrement
US6631969B2 (en) 1993-05-27 2003-10-14 Canon Kabushiki Kaisha Recording apparatus controlled with head characteristics and recording method
US6224182B1 (en) 1993-05-27 2001-05-01 Canon Kabushiki Kaisha Recording apparatus controlled with head characteristics and recording method
US6382764B1 (en) * 1994-07-29 2002-05-07 Canon Kabushiki Kaisha Printing method and apparatus for counting number of ejected ink droplets for controlling printhead recovery
EP0765762A1 (fr) * 1995-09-27 1997-04-02 Lexmark International, Inc. Circuit pour l'identification d'une tête d'imprimante à jet d'encre, avec une connexion sérielle et un registre à décalage dynamique
US5940095A (en) * 1995-09-27 1999-08-17 Lexmark International, Inc. Ink jet print head identification circuit with serial out, dynamic shift registers
US6022094A (en) * 1995-09-27 2000-02-08 Lexmark International, Inc. Memory expansion circuit for ink jet print head identification circuit
US6113208A (en) * 1996-05-22 2000-09-05 Hewlett-Packard Company Replaceable cartridge for a printer including resident memory with stored message triggering data
EP1486342A1 (fr) * 1997-02-10 2004-12-15 Datacard Corporation Module à tete d'impression termique et son procédé d'utilisation
EP1017569A1 (fr) * 1997-02-10 2000-07-12 Datacard Corporation Module a tete d'impression thermique et son procede d'utilisation
EP1017569A4 (fr) * 1997-02-10 2000-07-12 Datacard Corp Module a tete d'impression thermique et son procede d'utilisation
EP0878305A3 (fr) * 1997-05-14 1998-12-02 Hewlett-Packard Company Cartouche remplaçable pour une imprimante comprenant une mémoire interne avec des données de déclenchement de message mémorisées
EP0878305A2 (fr) * 1997-05-14 1998-11-18 Hewlett-Packard Company Cartouche remplaçable pour une imprimante comprenant une mémoire interne avec des données de déclenchement de message mémorisées
FR2840559A1 (fr) * 2002-06-05 2003-12-12 A P S Engineering Module d'impression thermique equipe de moyens de securisation a l'encontre d'un raccordement defectueux entre des connecteurs equipant le module et la machine prevue pour etre equipee de ce module
WO2003103975A1 (fr) * 2002-06-05 2003-12-18 Societe Aps Engineering Sarl Module d'impression tehrmique equipe de moyens de securisation du raccordement entre des connecteurs
CN100384636C (zh) * 2004-10-28 2008-04-30 三星电子株式会社 热敏打印机
US7998294B2 (en) * 2008-02-27 2011-08-16 Seiko Instruments Inc. Label manufacturing method and label manufacturing system
US7948512B2 (en) * 2008-03-05 2011-05-24 Sharp Kabushiki Kaisha Image forming apparatus with separate controllers for independently controlling an irradiating section
WO2011129881A1 (fr) * 2010-04-12 2011-10-20 Marozzi, John Tête d'impression améliorée à transfert thermique et système d'impression utilisant une telle tête d'impression
US8363075B2 (en) 2010-04-12 2013-01-29 John Marozzi Thermal transfer printhead and printing system using such a printhead
EP3150387A4 (fr) * 2014-05-26 2018-01-31 Sato Holdings Kabushiki Kaisha Imprimante

Also Published As

Publication number Publication date
JPH07186430A (ja) 1995-07-25
EP0541064A3 (en) 1993-07-21

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