WO1988008656A1 - Imprimante thermique - Google Patents

Imprimante thermique Download PDF

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Publication number
WO1988008656A1
WO1988008656A1 PCT/US1988/001274 US8801274W WO8808656A1 WO 1988008656 A1 WO1988008656 A1 WO 1988008656A1 US 8801274 W US8801274 W US 8801274W WO 8808656 A1 WO8808656 A1 WO 8808656A1
Authority
WO
WIPO (PCT)
Prior art keywords
data
voltage
image
printing
text
Prior art date
Application number
PCT/US1988/001274
Other languages
English (en)
Inventor
Masamichi Yumino
Original Assignee
Eastman Kodak Company
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 Company filed Critical Eastman Kodak Company
Publication of WO1988008656A1 publication Critical patent/WO1988008656A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/40025—Circuits exciting or modulating particular heads for reproducing continuous tone value scales
    • H04N1/40031—Circuits exciting or modulating particular heads for reproducing continuous tone value scales for a plurality of reproducing elements simultaneously
    • 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

Definitions

  • the present invention relates to a thermal printer suitable for printing different types of data such as image and character data (text) on a recording medium.
  • Background Art
  • a conventional thermal printer is schematically shown.
  • video signals obtained by scanning photos, documents and the like are transmitted to an image input unit 1, where the signals are A/D—converted.
  • Digital data output from the image input unit 1 are supplied to an image storage device 2.
  • the data pertaining to character data such as the depicted Chinese characters are created by a text input unit 3 such as a personal computer, a word processor and the like, and are then stored in a text storage device 4 such as a text memory.
  • the image memory 2 or the text memory 4 supplies a thermal head driver 6 with the data read therefrom through a color converter 5 for correcting the properties of an ink donor film when making a color print.
  • a thermal head 7 is equipped with a plurality of heating elements (not illustrated); and the thermal head driver 6 is capable of causing the heating elements to produce the heat by selectively energizing a group of the heating elements in accordance with the data supplied thereto.
  • the color dye is transferred from the ink donor film 8 to a recording medium 9 by heat produced by the heating elements.
  • a desired image is formed on the recording medium 9.
  • the reference numeral 10 represents a platen drum on which the recording medium 9 is wound; 11 denotes a constant—voltage power supply for supplying a constant voltage whereby the heating elements generate heat; and 12 refers to a control circuit which selects one of the memories 2 and 4 and permits the data to be read from the selected memory, viz., the .image memory 2 or the text memory 4.
  • the video signals output from a video signal generating device such as a-video camera and the like are A/D—converted by the image input unit 1 and are then stored in the image memory 2.
  • the text data input from the text 3 are stored in the text memory 4.
  • the image memory 2 or the text memory 4 is selected by the control circuit 12 depending upon the data to be printed, and the data read from the selected memory are supplied through the color converter 5 to the thermal head driver 6.
  • Thermal head driver 6 controls the conduction time of the heating elements provided within the thermal head 7. A constant voltage is applied from the constant—voltage power supply 11 to the thermal head 7; a desired heating element is driven by the thermal head driver 6 in accordance with the data received from the color converter 5. Sinc the conduction time of the heating elements is controlled, image pixels having desired density are printed in the recording medium 9 by means o"f the thermal head 1.
  • the thermal printer includes a plurality of devices for respectively storing different types of print data and a thermal head for printing such data on a record medium.
  • the thermal printer also comprises voltage supply means for generating and supplying one of a plurality of D.C. voltages to the thermal head at a time, said different D.C. voltages being suitable for printing the different types of print data, respectively.
  • Control means selects one of said storage devices to cause said selected storage device to read out the print data stored there in and supplied such data to said thermal head, and for causing said voltage supply means to generate and supply one of said different D.C. voltages to said thermal head in accordance with the type of the print data to be printed on the recording medium.
  • Fig. 1 shows a conventional thermal printer
  • Fig. 2 is a schematic diagram showing one embodiment of a thermal printer according to the present invention.
  • Fig. 3 is a view showing a printing process by the thermal printer illustrated in Fig. 1;
  • Fig. 4 is a view showing one example of power supply which can be used in the thermal printer of Fig. 2.;
  • Fig. 5 is a " block diagram of the principal portion of another thermal printer according to the present invention.
  • Fig. 6 is a view showing a print produced by the thermal printer of Fig. 5.
  • Modes of Carrying Out the Invention The Fig. 2 schematically shows a thermal printer according to the present invention; and the same components as those in Fig. 1 are marked with the same reference numerals.
  • variable voltage power supply 13 is provided instead of the prior art constant—voltage power supply, and that a control signal is transmitted from the control circuit 12 to the variable voltage power supply 13.
  • the variable voltage power supply 13 comprises a voltage supply unit 14 for supplying a voltage to the heating elements of the thermal head 7 and a voltage setting unit 15 for changing the output voltage of the voltage supply unit 14 in response to a control signal from the control circuit 12.
  • the control circuit 12 permits the data to be read from the image memory 2 or the text memory 4 in conformity with the types of data to be printed on the recording medium 9.
  • control circuit 12 sends to the voltage setting unit 15, the control signal indicating which of the image data or the text data is to be read out.
  • the voltage setting unit 15 sets the output voltage of the voltage supply unit 14. More specifically, when the control signal indicates that image data are to be read from the image memory 2, the voltage setting unit 15 sets the output voltage of the voltage supply unit 14 to a voltage V. suitable for the image print density.
  • the voltage setting unit 15 sets the output voltage of the voltage supply unit 14 to a voltage V suspend ⁇ suitable for text print density.
  • the heat build—up or accumulation effects act on the heating elements of the thermal head 7 in the case of the image printing, whereas the heat radiation effects work on the heating elements in the case of the text printing.
  • the voltage V u ⁇ suitable for the text printing generally should be higher that the voltage V " ⁇ suitable for the image printing.
  • V " ⁇ suitable for the image printing it is feasible to print both high quality image and text on the same recording medium each with its own desired density and to further maintain the desired print density of image and the text throughout the recording medium.
  • Fig. 3 there is schematically shown a concept of the above—described printing according to the present invention.
  • an image is printed on the recording medium 9 by means of the thermal head 7, and then characters are likewise printed thereon.
  • the output voltage of the voltage supply unit is kept at V during the image printing but is kept at V during the text or ⁇ character printing.
  • the variable voltage power supply 13 may be constructed by a wide variety of types of circuits. Fig.
  • the control signal output from the control circuit 12 is input to the base 17 of a switching transistor 16.
  • the emitter of the switching transistor 16 is grounded through a resistor 18, and its collector is connected to a junction point J of two resistors 19 and 20 which are connected in series between an output terminal OUT of a rectifier circuit R and " ground.
  • the junction point J is connected to a switching pulse generator and a drive circuit 21 generating first and second pulse trains for turning on and off a switching transistor S.
  • the switching transistor S is connected to a DC power supply B and to the primary winding of a transformer T.
  • the secondary winding of the transformer T is connected to the rectifier circuit R.
  • the switching transistor 16 stays in the OFF—state while the control circuit 12 supplies the base 17 of the switching transistor 16 with the control signal which indicates the readout of the image data from the image memory 2.
  • the switching transistor S is turned on and off by the first pulse train having pulses of a predetermined short width supplied from the switching pulse generator and drive circuit 21. Pulses are correspondingly generated in the secondary winding of the transformer T. These generated pulses are rectified by the rectifier circuit R, thereby obtaining the desired voltage V at the output terminal "OUT".
  • the switching transistor 16 is changed to the ON—state during the period in which the signal from the control circuit 12 indicates that the text data are. to be read from ' the text memory and to the transistor base 17.
  • the resistor 18 is connected in parallel to the resistor 20. This varies the voltage at the junction point J obtained by dividing the voltage V. at the output terminal OUT. As a result, the switching pulse generator and driver circuit 21 detect this variation, and generates the second pulse trains having pulses of a longer pulse width. Owing to this step, the conduction period of the switching transistor S is extended, and the output voltage of the rectifier circuit R becomes V ⁇ u which is higher than the previous voltage V .
  • the period in which the image is printed is offset in time from the period in which the text is printed.
  • the present invention can, however, be applied to a case where the image and the text concurrently exist on the same line. This case will now be explained with reference to Figs. 5 and 6.
  • the second embodiment shown in Fig. 5 differs from the first embodiment of Fig. 2 in that the control signals transmitted from the control circuit 12 are supplied not only to the variable voltage power supply 13 but also to the thermal head driver 6.
  • the thermal head 7 is capable of enabling the heating elements a group at a time. As illustrated in Fig. 6, where both text and an image are printed on one line, the heating elements can be classified into the first group for printing the text and the second group for printing the image.
  • a group of heating elements of the thermal head in accordance with a width occupied by such a group of the heating elements on the recording medium come under the image data or text data. Desired printing densities are produced by enabling each group of the heating elements on a time—division basis and by causing the variable voltage power supply 13 to supply the thus enabled heating elements with a voltage suitable for printing.
  • the control circuit 12 performs a function to supply the control signals to the variable voltage power supplies 13 and the thermal head driver 6. For example, when printing a line X—X illustrated in Fig. 6, the control signals indicating that the text is to be printed are first supplied to the variable voltage power supply 13 and then thermal head driver 6.
  • variable voltage power supply 13 outputs the voltage vV ⁇ . suitable for printing the text and the thermal head driver 6 outputs an enable signal EN., to enable only the first group of the heating elements used for the text printing.
  • the thermal head driver 6 outputs another enable signal EN_ to enable the second group of the heating elements used for the image printing.
  • EN_ an enable signal
  • the present invention can, however, be applied to other cases wherein printing is effected on the basis of three or more different types of data such as image, text, and graphics.
  • the arrangement of these cases may be such that memories are provided for each t pe of data, and that the variable voltage power supply is capable of outputting voltages suitable for printing each type of data.
  • the voltage suitable for the printing density of the data is supplied to the heating elements of the thermal head, depending on the type of the data to be printed, so it is possible to print all kinds of data on the same recording medium with desired densities. This will remarkably enhance the print—quality.
  • the thermal printer according to the present invention is suitable for printing both an image like a portrait in the identification card and alphabets or Chinese characters showing the personal information.
  • the invention is particularly suitable for use in printing images leaving text and continuous tone images.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Electronic Switches (AREA)

Abstract

Une imprimante thermique comprend plusieurs dispositifs de stockage servant respectivement à stocker différents types de données d'impression et une tête thermique servant à l'impression sur un support d'enregistrement en fonction des données d'impression. L'imprimante thermique comprend une source de tension servant à amener plusieurs tensions de courant continu à la tête thermique. Un circuit de commande sélectionne l'un des dispositifs de stockage et permet l'alimentation par la source de tension de l'une des tensions de courant continu en fonction du dispositif de stockage sélectionné.
PCT/US1988/001274 1987-04-27 1988-04-25 Imprimante thermique WO1988008656A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP62/103932 1987-04-27
JP10393287A JPS63268668A (ja) 1987-04-27 1987-04-27 サ−マルプリンタ

Publications (1)

Publication Number Publication Date
WO1988008656A1 true WO1988008656A1 (fr) 1988-11-03

Family

ID=14367208

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1988/001274 WO1988008656A1 (fr) 1987-04-27 1988-04-25 Imprimante thermique

Country Status (3)

Country Link
EP (1) EP0311678A1 (fr)
JP (1) JPS63268668A (fr)
WO (1) WO1988008656A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995001044A1 (fr) * 1993-06-17 1995-01-05 Datametrics Corporation Systeme de commande d'une imprimante thermique

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4366489A (en) * 1980-02-06 1982-12-28 Ricoh Company, Ltd. Thermal recording apparatus
JPS59161968A (ja) * 1983-03-07 1984-09-12 Canon Inc サ−マルプリンタ
EP0122430A2 (fr) * 1983-03-08 1984-10-24 Canon Kabushiki Kaisha Appareil de traitement d'une image
EP0197549A2 (fr) * 1985-04-08 1986-10-15 Kabushiki Kaisha Sato Dispositif pour la commande de la température d'une tête thermique

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4366489A (en) * 1980-02-06 1982-12-28 Ricoh Company, Ltd. Thermal recording apparatus
JPS59161968A (ja) * 1983-03-07 1984-09-12 Canon Inc サ−マルプリンタ
EP0122430A2 (fr) * 1983-03-08 1984-10-24 Canon Kabushiki Kaisha Appareil de traitement d'une image
EP0197549A2 (fr) * 1985-04-08 1986-10-15 Kabushiki Kaisha Sato Dispositif pour la commande de la température d'une tête thermique

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Patent Abstracts of Japan, volume 9, no. 15 (E-291)(1738), 22 January 1985; & JP-A-59161968 (CANON K.K.) 12 September 1984 *
Proceedings of the SID, volume 2, 1980, (Los Angeles, US), K. Saito et al.: "High-speed thermal recording", pages 165-169 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995001044A1 (fr) * 1993-06-17 1995-01-05 Datametrics Corporation Systeme de commande d'une imprimante thermique
US6034705A (en) * 1993-06-17 2000-03-07 Datametrics Corp. Thermal printer control system

Also Published As

Publication number Publication date
EP0311678A1 (fr) 1989-04-19
JPS63268668A (ja) 1988-11-07

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