EP0458691A1 - Verbesserung für thermische Druckknöpfe - Google Patents

Verbesserung für thermische Druckknöpfe Download PDF

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Publication number
EP0458691A1
EP0458691A1 EP91401300A EP91401300A EP0458691A1 EP 0458691 A1 EP0458691 A1 EP 0458691A1 EP 91401300 A EP91401300 A EP 91401300A EP 91401300 A EP91401300 A EP 91401300A EP 0458691 A1 EP0458691 A1 EP 0458691A1
Authority
EP
European Patent Office
Prior art keywords
line
points
heating
film
substrate
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Withdrawn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
EP91401300A
Other languages
English (en)
French (fr)
Inventor
Claude Morelle
Bernard Mouchet
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.)
Axiohm SA
Original Assignee
Axiohm SA
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 Axiohm SA filed Critical Axiohm SA
Publication of EP0458691A1 publication Critical patent/EP0458691A1/de
Withdrawn legal-status Critical Current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
    • B41J2/335—Structure of thermal heads
    • B41J2/33555—Structure of thermal heads characterised by type
    • B41J2/3357—Surface type resistors
    • 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
    • B41J2/375—Protection arrangements against overheating

Definitions

  • the present invention relates to thermal printers.
  • a thermal printer head comprises, on a support plate, a line of heating points, each of them consisting of an electrically resistant element capable of heating by Joule effect, inserted in a supply conductor in current which includes an electronic switch.
  • the operating principle of such a device is simple. On the one hand, it involves scrolling under the line of points, in contact with it, a ribbon of paper sensitive to temperature and successively supplying series of heating points so as to bring their temperature for a short time to a value greater than that of the paper reaction.
  • Each point thus heated will create a trace on the paper whose dimensions depend on a number of factors such as the width of the heating point (taken transversely to the direction of travel of the paper), the speed of the paper, the holding time at the prescribed point temperature ....
  • other points are heated while the previous ones cool, the trace resulting from the succession of these sequences forming the desired impression.
  • a temperature sensor which is in the form of a component of the thermistor type. This component is placed on the substrate relatively far from the line of points so that the response time of this component is of an order of magnitude (ten seconds) which is not acceptable, taking into account the rates of change d thermal state of a line of points resulting from the increasingly high rates of excitation.
  • values of the order of a millisecond will be given with regard to the period of the pulses to be compared to ten or twenty seconds of response time from the temperature sensor, which leads to regulation with 10 or 20 000 lines of delay printing dots.
  • the object of the present invention is to remedy this drawback by proposing a thermal printer head comprising means for having a temperature measurement of the heating points in an extremely short response time allowing fine regulation of the quantity of energy to bring to each heating point guaranteeing the constant quality of the print on the one hand along the line and on the other hand over time.
  • the invention relates to a thermal printer head comprising on an insulating substrate, a layer of glass having an upper support surface the line of heating points and their supply conductors, the conductors being oriented perpendicular to the line of points, a protective layer covering the upper surface of glass provided with the line of points and conductors, which thermal head comprising at the plumb with the line of heating points and under the latter, a film of heat-resistant material electrically insulated from the line of heating points.
  • Heat dissipation from the heating points takes place on the one hand towards the paper and on the other hand towards the substrate.
  • the substrate is equipped on its rear face with a heat dissipation radiator, the heat flow flows in the substrate in a preferred manner transversely thereto. It is therefore optimal to place the thermo-resistive material directly above this line of points because it is in this zone that it is subjected to the most intense heat flow.
  • the primary function of this film is therefore that of temperature sensor by measuring its resistance.
  • the reaction time of this sensor will be all the faster as it is close to the line of points.
  • thermoresistive in between. It is not outside the scope of the invention to have this sensor, directly above the line of points on the other face of the substrate. This solution, although less efficient, is however much more interesting than the devices known to date.
  • Another characteristic arrangement of the invention resides in the fact that the heat dissipation radiator is attached to the face of the substrate opposite to that provided with the heating points, by means of a layer of a thermally conductive material.
  • This arrangement has a double advantage. Firstly, it establishes a thermal bridge which distributes the heat received, through the substrate through the heated points of the line. There is therefore a certain distribution of heat at this bridge which promotes the exchange of heat between the hot spots and the cold spots. The homogenization of the point line temperature is favored.
  • the intimacy of the contact between the substrate and the radiator is very significantly improved, which makes it possible to improve the heat flow from the line of points to the radiator. This heat flow, previously, presented a certain heterogeneity since with the plumb of a heated point could be a point of bad contact between substrate and radiator. Under these conditions, the flow had to take a longer path to circumvent this discontinuity.
  • This arrangement of the invention is particularly advantageous when the heating points of the line are not physically separated from each other as it is now more and more the case, because it makes it possible to equalize the cooling conditions for each heating point of a line.
  • the thermal printer head shown conventionally comprises an insulating ceramic substrate (based on alumina) which constitutes the structure of the head in the form of a plate about half a millimeter thick, its width being of the order of ten centimeters.
  • an insulating ceramic substrate based on alumina
  • thermoresistive material such as platinum is deposited on this substrate.
  • the deposition techniques are known. This is, for example, a screen printing of an organometallic paste which undergoes cooking at around 1000 ° C.
  • the shape of this film 2 is determined by experience as a function of the ohmic values required. It can be either a simple rectangle over the entire width of the substrate, or a frieze of a longer conductor.
  • This film can be electrically continuous or comprise several sections.
  • thermo-resistive material The upper surface of the substrate comprising this film of thermo-resistive material is then covered, in a known manner, with a layer of glass 3 (coating), also by screen printing and baking, with the necessary reserves to allow access to suitable locations, film 2 for electrical interconnections.
  • a resistant material 5 is deposited which forms the line of heating points.
  • this material arranged in a line is either physically divided into separate points, each of them being inserted in a supply circuit (conductors 4), or continuous and is heated in sections according to the connections made electronically. between conductors 4 and a power source.
  • a layer of protective material 6 covers at least the zone of the line of heating points to electrically isolate the circuits thus produced from the outside and to constitute a lining for protecting the line of heating points against abrasion of the paper. who walks past her.
  • the resistance of the film 2 which is made of a material whose resistance varies with temperature, is a variable directly proportional to its temperature
  • the measurement of this resistance gives an indication of its temperature and consequently an indication of the temperature of the line of heating points. Given the very short distance between them, the temperature variations of the heating points immediately influence the temperature of the sensor film.
  • the resistance of the film therefore varies very quickly and a signal relating to it can be used as a control parameter for controlling the energy to be supplied to the heating points, for example to keep the maximum temperature at which each is brought substantially constant. heating point.
  • the measurement readings which will necessarily be average values, concern several points which, in reality, are at different temperatures.
  • the data collected can be processed in conjunction with the parameters relating to the frequency of supply of the dots which can be extracted from the print management unit. it will then be possible to refine the regulation.
  • Another arrangement consists in seeking to reduce the thermal gradient which may exist between each point so as to reduce the temperature range in which the regulation must be exerted. To do this, it is necessary to favor on the one hand the speed of cooling of the hot spots and on the other hand the heat exchange along the line of points.
  • the invention proposes to have between the substrate 1 and a radiator 7 which is known in itself and present on the other face of the ceramic plate 1, a layer 8 of a material which is very thermally conductive (for example silver) which has the effect, on the one hand, of improving the contact between radiator 7 and plate 1 therefore of promoting the transfer of heat in the thickness of the head towards the dissipation radiator and, d 'on the other hand to form a heat distributor under the line of heating points and thus to promote a heat exchange between hot and cold points.
  • a radiator 7 which is known in itself and present on the other face of the ceramic plate 1
  • a layer 8 of a material which is very thermally conductive (for example silver) which has the effect, on the one hand, of improving the contact between radiator 7 and plate 1 therefore of promoting the transfer of heat in the thickness of the head towards the dissipation radiator and, d 'on the other hand to form a heat distributor under the line of heating points and thus to promote a heat exchange between hot and cold points.
  • the print head according to the invention thus equipped with this heat-resistant film (in any suitable material) has an additional advantage. It is indeed possible to use this film as a heating resistor of the line of points. It should indeed be noted that such thermal printers are subject to extremely severe conditions of use because they can be fitted to external devices subjected to the most severe climates.
  • this film 2 It is therefore possible to connect to this film 2 a source of electrical energy, for determined time spaces (prior to editing, and during editing) in the form of pulses or train of pulses, interspersed between the times. monitoring and measurement, the film then being connected to another energy source.
  • the interconnections of the film to the measurement supply or to that of the power supply (heating) can be managed by a control device of the kind comprising a multiplexing function if necessary.

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  • Electronic Switches (AREA)
EP91401300A 1990-05-23 1991-05-21 Verbesserung für thermische Druckknöpfe Withdrawn EP0458691A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9006444 1990-05-23
FR9006444A FR2662395A1 (fr) 1990-05-23 1990-05-23 Perfectionnement aux tetes thermiques d'imprimantes.

Publications (1)

Publication Number Publication Date
EP0458691A1 true EP0458691A1 (de) 1991-11-27

Family

ID=9396888

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91401300A Withdrawn EP0458691A1 (de) 1990-05-23 1991-05-21 Verbesserung für thermische Druckknöpfe

Country Status (3)

Country Link
US (1) US5196865A (de)
EP (1) EP0458691A1 (de)
FR (1) FR2662395A1 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1431045A1 (de) * 2002-12-17 2004-06-23 Agfa-Gevaert Modellierungsverfahren zur Berücksichtigung der Thermokopftemperatur und der Raumtemperatur
CN101730448A (zh) * 2008-10-24 2010-06-09 鸿富锦精密工业（深圳）有限公司 具有监测温度功能的散热装置
JP7093226B2 (ja) * 2018-05-22 2022-06-29 ローム株式会社 サーマルプリントヘッド
JP7228428B2 (ja) * 2019-03-20 2023-02-24 ローム株式会社 サーマルプリントヘッド

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4837586A (en) * 1988-01-28 1989-06-06 Eastman Kodak Company Image contrast by thermal printers

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55144178A (en) * 1979-04-27 1980-11-10 Toshiba Corp Thermal head
JPS56142081A (en) * 1980-04-09 1981-11-06 Ricoh Co Ltd Thermal head
US4449033A (en) * 1982-12-27 1984-05-15 International Business Machines Corporation Thermal print head temperature sensing and control
JP2568492B2 (ja) * 1985-05-09 1997-01-08 松下電器産業株式会社 サ−マルヘツド
JPS61291156A (ja) * 1985-06-19 1986-12-20 Yokogawa Electric Corp サ−マルヘツドの駆動方法
JPS62199471A (ja) * 1986-02-27 1987-09-03 Mitsubishi Electric Corp 熱印刷装置
US5036337A (en) * 1990-06-22 1991-07-30 Xerox Corporation Thermal ink jet printhead with droplet volume control

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4837586A (en) * 1988-01-28 1989-06-06 Eastman Kodak Company Image contrast by thermal printers
US4837586B1 (de) * 1988-01-28 1992-06-30 Eastman Kodak Co

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 11, no. 111 (M-578)(2558), 8 avril 1987; & JP - A - 61255872 (MATSUSHITA ELECTRIC IND. CO. LTD.) 13.11.1986 *
PATENT ABSTRACTS OF JAPAN vol. 12, no. 52 (M-668)(2899), 17 février 1988; & JP - A - 62199471 (MITSUBISHI ELECTRIC CORP.) 03.09.1987 *
PATENT ABSTRACTS OF JAPAN vol. 5, no. 14 (M-52)(686), 28 janvier 1981; & JP - A - 55144178 (TOKYO SHIBAURA DENKI K.K.) 10.11.1980 *
PATENT ABSTRACTS OF JAPAN vol. 6, no. 23 (M-111)(901), 10 février 1982; & JP - A - 56142081 (RICOH K.K.) 06.11.1981 *

Also Published As

Publication number Publication date
FR2662395B1 (de) 1995-01-13
US5196865A (en) 1993-03-23
FR2662395A1 (fr) 1991-11-29

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