EP0575668B1 - Circuit de commande pour système d'impression thermique avec ruban résistif - Google Patents

Circuit de commande pour système d'impression thermique avec ruban résistif Download PDF

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Publication number
EP0575668B1
EP0575668B1 EP92250246A EP92250246A EP0575668B1 EP 0575668 B1 EP0575668 B1 EP 0575668B1 EP 92250246 A EP92250246 A EP 92250246A EP 92250246 A EP92250246 A EP 92250246A EP 0575668 B1 EP0575668 B1 EP 0575668B1
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EP
European Patent Office
Prior art keywords
voltage
electrodes
printing
drive circuit
measuring
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EP92250246A
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German (de)
English (en)
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EP0575668A2 (fr
EP0575668A3 (fr
Inventor
Wolfgang Dr. Thiel
Stephan Günther
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Francotyp Postalia GmbH
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Francotyp Postalia GmbH
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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
    • 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 invention relates to a control circuit for an electrothermal printing device with a resistance band of the type specified in the preamble of claim 1.
  • Such printing devices which print printing patterns on a recording medium which is relatively moved, are to be printed, a likewise relatively moving ink carrier with a defined electrical resistance transmitting the color particles
  • a control circuit for an electrothermal printing device with a resistance band of the type specified in the preamble of claim 1.
  • Postage meters have input, storage and display means and a print control unit for a printing device.
  • the pressure control unit contains a microprocessor control and acts on a switching unit.
  • a serial / parallel shift register loaded with the serial print data transfers the print data to the latches of an intermediate store in a first control phase.
  • each gate controlled by the associated outputs of the latches is switched to continuity during a strobe pulse and a control pulse is emitted to the respective resistance element.
  • the resistance heating elements are preheated directly by a clock frequency which is adapted to the required heating energy in terms of its pulse height and pulse width. Such preheating via energy from a voltage source is in principle not possible in a printer with an electrothermal resistance ribbon (ETR) because the resistance elements are located in the resistance layer of the resistance ribbon and because the resistance ribbon is moved relative to the print head and also to the recording medium to be printed.
  • ETR electrothermal resistance ribbon
  • Such a (ETR) printer which has an electrothermal resistance ribbon, is already known from DE 21 00 611, the pin electrodes of which are encased by a counter electrode.
  • the electrodes are supplied by applying a voltage potential from a constant voltage source.
  • This type of control has the advantage of a simple, cheap power supply, but it is Print resolution too low due to the small number of electrodes. If the jacket is omitted, the number of electrodes in the pressure bar can be increased.
  • a modern ETR printer includes an electronic head control, an ETR printhead with a large number of electrodes and a current collecting electrode which are connected to a power supply unit.
  • the expansion of the application area of thermal printing technology has increased the need for print heads with a larger print width (1 inch and more) and a higher geometric resolution (200 dots per inch and more). This can only be achieved with print heads with a large number of selectively controllable electrodes. While 25 to 50 electrodes were originally sufficient for the conventional line printer, the number of electrodes increases to 150 to 250 in the above-mentioned applications. Since under certain operating conditions (pressure of a continuous pressure column) all electrodes are to be supplied with current at the same time, considerable effort has to be expended for the potential provision of this electrical power.
  • the control circuit for an ETR printhead control has a common voltage source and series resistors for the electrodes in each partial current path.
  • the ETR printhead contains a multiplicity of electrodes which are arranged insulated from one another, each of which can produce a pixel of the printed image. The energy supplied via these electrodes is converted into current heat in the area of the resistance layer assigned to each pixel, which leads to the melting of the color of the color layer located in the area and thus to the printing of a dot.
  • the ETR printhead acts on the recording medium, preferably paper, via a resistance ink ribbon that is moved with the recording medium.
  • the resistance ink ribbon has an upper resistance layer in contact with the ETR print head, a middle current return layer and a lower ink layer in contact with the recording medium (EP 88 156 B1).
  • these fixed resistors dominate the variable resistances that are on the way of the print head-ribbon-back electrode and relatively reduce the influence of these variances on the total resistance.
  • the series resistors used have the task of keeping the current for the electrodes as constant as possible. This happens the better, the relatively larger these resistances are to the sum of all resistances of the actual pressure current path (tape resistance, resistance of the returning metal layer, contact resistances).
  • These series resistors are currently selected to be 3 to 4 times larger, i.e. of course also that only about a quarter of the energy used is used for printing, the rest is converted into heat loss.
  • Such a solution is used, for example, in the Hermes printer 820 equipped with an ETR printing unit.
  • the additional loss of electrical energy in the series resistors is disadvantageous.
  • An ETR printer with two back electrodes is known from EP 0 301 891 A1. Although this leads to a current distribution in the return of the total current, it does not yet improve the overall power balance.
  • the energy to be supplied depends on the resistance of each current path assigned to a pixel, on the melting temperature of the color, the intended contrast of the printed image and on the speed of the moving resistance ribbon and is non-linear with the surface roughness of the recording medium (Paper type) increases.
  • the print quality in the ETR process depends crucially on the fact that the electrical power, which is converted into thermal energy per electrode in the resistance band, is the same for all electrodes and all times.
  • a too low electrical power leads to an insufficient heating of the corresponding pixel area in the ink layer of the resistance band. This then results in a smaller volume of melted-out color and ultimately an insufficient contrast of the corresponding pixel on the substrate to be printed.
  • too much electrical power leads to strong heating of the ETR band, which also affects the support layer of the band and reduces its strength.
  • excessive electrical power continues to overload the power supply assembly. In any case, differences in the contrast of the imprint would be visible with changing electrical power.
  • the main influence on the fluctuation of the voltage drop arises in addition to the above-mentioned factors but by printing variable data, a number between 0 and the number n of the electrodes present being generally controlled per printing column.
  • the voltage drop across the resistors c) to e) in the unselective (return) current path depends on the current flowing through. This in turn is equal to the sum of the individual currents in the selective part of the current path with the resistors a) + b) and thus depends on the number of electrodes of the print head that are controlled.
  • EP-A-0 067 969 proposes a driver circuit for supplying power to an ETR printer, which has a measuring circuit for a high impedance at the first input to which the measuring voltage is applied, and an additional circuit 208 at the second input in order to provide a reference potential , as a necessary means.
  • the measuring circuit S FBK is output inverted by the matching circuit 200 to the signal processing means 216 of the driver circuit.
  • the number of electrodes temporarily connected to the controllable energy source is predefined by the microprocessor control, which outputs a control signal corresponding to the dependence on the number of activated electrodes delivers the controllable energy source.
  • the latter applies a current or a voltage to the electrodes which are temporarily connected via a switching unit, the height of which has such a dependency on the temporarily different number of controlled electrodes that a larger number of electrodes are supplied with a higher current or voltage, than a smaller number.
  • a control voltage which is preferably generated via a D / A converter, is passed to an amplifier input of an amplifier, which outputs the required target voltage for the controllable voltage source.
  • the total current flowing in the resistance ribbon is dissipated to ground using a current collecting electrode.
  • the total current also flows through an external measuring resistor, from which a measuring voltage is tapped and fed to a second input of the amplifier.
  • This combination of control and regulation is circuit-intensive. With a higher (lower) measuring voltage, the nominal voltage and thus the supply voltage of the printhead are reduced (increased). However, this means that only the fluctuations in the total resistance caused by the strip quality can be compensated for, but no errors can be detected.
  • the measuring voltage drops with a higher total resistance, in particular to compensate for contact problems of the electrodes, the supply voltage is increased. However, the failure of an electrode cannot be detected. The measuring voltage then drops and the remaining electrodes are supplied with a somewhat too high supply voltage, which leads to a somewhat higher contrast in the printed image.
  • the invention is based on the fact that, with a larger number n of existing electrodes to be controlled simultaneously, supplying the individual electrodes with the previous control circuits is too expensive and too complex.
  • the circuit arrangement should be usable for ETR high-performance printers with a large number of electrodes, with a drastic reduction in power loss and consistently good print quality. Protection of the printing device against destruction should also be ensured.
  • the invention is based on the consideration, taking into account the total resistance, with a regulation of the supply voltage in accordance with the constantly changing power requirement, a cost-effective alternative to the solution with a control of the supply voltage, as proposed in EP-A-0 568 162 create.
  • an adjustable constant voltage source is used which, compared to ground potential, supplies a supply voltage consisting of a constant adjustable print voltage which is increased by a variable reference voltage.
  • the reference voltage in relation to ground potential can be changed in accordance with the number n of electrodes activated simultaneously and in accordance with the variance of certain resistances in the resistance band.
  • the invention is based on the fact that a compensation of the occurring variance of the voltage drop across the heating resistors can be carried out in the resistance ribbon.
  • the voltage drop caused by the total current is measured via the unselective (return) current path in the resistance ink ribbon by means of one or more additional or existing electrodes which are arranged on the printhead.
  • This measured value forms the reference voltage, preferably at the same level. It is added to the set print voltage.
  • the supply voltage of the activated electrodes of the printhead then results in such a way that an increase in the measured value leads to an increase and a decrease leads to a reduction in the supply voltage, the print voltage remaining constant.
  • the level of the supply voltage on the one hand has such a dependency on the temporarily different number n of activated electrodes that a larger number of activated electrodes are supplied with a higher supply voltage but per dot with a lower pressure energy , than a smaller number of activated electrodes, which are supplied with a higher pressure energy with a lower supply voltage per dot.
  • the measuring electrode is a separately arranged and / or just not activated normal printhead electrode.
  • the ETR print head can advantageously be equipped with edge electrodes which are located at the ends of the electrodes of the print head arranged in line in the print bar, but which are not used for the franking imprint.
  • FIG. 1 shows a block diagram of the electrothermal printing device according to the invention with a control circuit, consisting of a constant voltage source 1, a switching unit 2, an ETR printing unit 3, a pressure control unit 5, a current collecting electrode 6 and with a storage means 7 which is connected to the pressure control unit 5 for controlling the ETR printing unit 3.
  • the storage means 7 contains at least the graphic data for a print image.
  • the print control unit (DS) 5 of the control circuit acts on the switching unit 2, with the electrodes being supplied with energy from a controllable constant voltage source 1 for the individual pixels of the print image in order to control a print head 30, and a print pattern being printed on a record carrier which is relatively moved and to be printed by the resistance ribbon 10, which is also relatively moved, transfers the color particles from the color layer 9 when the associated heating resistor is heated in the resistance layer 100 in areas 101, 102, 103,...
  • the switching unit 2 acted upon by the pressure control unit 5 transmits the power to an ETR print head 30 of the ETR printing unit 3, which is in contact with an ETR resistance ink ribbon 10 via electrodes 31, 32, 33,..
  • Relevant print information is loaded into the switching unit 2 at the correspondingly correct time t 1 , which in the activated state from t 2 ensures that the pixels to be printed are energized for a defined time t j so that the heat required for the printing process is contacted in the briefly activated ones Areas 101, 102, ..., 105, ..., the resistance layer 100 of the resistance ribbon 10 is generated.
  • the energy for the electrodes of the ETR printing unit 3 is provided by an adjustable constant voltage source 1, those temporarily being connected to the controllable voltage source 1 standing electrodes 31, 32, 33, ..., are specified by the pressure control unit 5.
  • electrodes 31, 32, 33, 34 and 35 are connected via the switching unit 2 to the positive pole + U s of the constant voltage source 1, each partial current causes heating in the respectively contacted areas of the resistance layer 100.
  • the current collects in the return layer 8, which is preferably made of aluminum, and which has a current return resistance R r — not shown in FIG. 1.
  • the current flows through the resistance layer 100 to the current collecting electrode 6 which is connected to ground (or to the negative pole -U s ) and thereby generates a voltage drop. This can be tapped with a measuring electrode 29.
  • the voltage drop caused by the total current I g and by the variance of the resistances across the unselective (return) current path in the resistance ribbon is measured and the constant voltage source 1 is triggered, which with it via the switching unit 2 temporarily connected electrodes 31, 32, 33, ... to be supplied with a supply voltage U s , the level of the supply voltage of the activated electrodes of the print head being controlled in such a way that an increase in the measured value leads to an increase in the supply voltage of the electrodes leads and a drop to lower the supply voltage. This compensates for the existing variance in the voltage drop across the heating resistors in the resistance ribbon.
  • the constant voltage source 1 has a reference voltage input for the measuring voltage emitted by at least one measuring electrode, that of the Number n of the controlled electrodes and the residual resistance R r is dependent.
  • the measuring electrode 29 at least one additional printhead electrode which is present due to the manufacturing process but is not used during printing can advantageously be used.
  • FIG. 2 shows an electrical equivalent circuit diagram with a constant voltage source having an input for the reference voltage U B and with the switching unit 2.
  • the gates G 1 to G 4 of the switching unit 2 are shown in FIG. 2 as switches with associated series resistors R v .
  • the switches are shown in the closed state during the energization time t j , ie when a strobe pulse is applied to the switching unit.
  • the value of the series resistors R v and R k is significantly smaller than the value of the heating resistors R h .
  • the required pulse height U p is provided by the adjustable constant voltage source 1 which, for this purpose, applies a voltage U s to the electrodes 31, 32, 33, ... which are temporarily connected to it via the switching unit 2, the height of which is such Depending on the temporarily different number n of activated electrodes, a larger number of electrodes are supplied with a higher current or with a higher voltage than a smaller number.
  • R G (R p / n) + R rest
  • the value of the series resistor R v is 1/10 to 1/100 of the value of the effective heating resistor R h . This further minimizes the losses of the system compared to the prior art mentioned above.
  • the reference potential for the constant voltage source 1 is preferably formed by impedance conversion.
  • the switching unit 2 six pieces of the control circuits SN 75518, each with 32 bit shift registers, 32 latches of the buffer memory and 32 AND gates, can advantageously be used for the control of 192 electrodes in a pressure bar.
  • the "data out" output of the first control circuit is connected to the "data in” input of the second control circuit.
  • the inputs / outputs are also interconnected in order to load all print data for one print column. After a defined time, the new print data are provided by the print control unit 5 and can be stored in the latches of the buffer.
  • Each serial / parallel shift register of the switching unit 2 which is loaded with the serial print data directly at the "data in” input, transfers the print data in a first control phase from t 1 on to the latches of an associated buffer store which has a control input "latch enable".
  • the current printing information is therefore available in the switching unit 2 sufficiently long before the actual printing process.
  • each gate G 1 , G 2 , ..., driven by the associated outputs of the latches, of a driver on the output side is switched to continuity during a strobe pulse and a control pulse of pulse width t j to the current path with the associated resistances R p and R rest .
  • the adjustable constant voltage source is in particular a linear regulator 11, which contains, for example, a parallel connection of the circuit type LM 317, to which the first DC voltage U g is supplied and which outputs a regulated voltage U s on the output side for supplying the drivers in the switching unit 2.
  • the reference voltage U B at the control input of the Linear regulator 11 results directly from the analog measuring voltage U m or from the amplified measuring voltage via a matching circuit 12.
  • the matching circuit 12 contains for impedance conversion at least one non-inverting amplifier 13 connected as a voltage follower and a protective circuit 17 against an excessively high output. It contains a Zener diode, which limits the reference voltage to U B ⁇ +10 V.
  • FIG. 4 relates to a further variant with a flat measuring electrode 29 arranged on one side of the pressure bar and the current collecting electrode 6 arranged on the other side.
  • the measuring electrodes are each arranged at the two ends of the print bar of the print head 30 at a distance from the printing electrodes.
  • the edge electrodes are also in contact with the resistance ribbon, but are not subjected to drive pulses from the print head drive electronics.
  • the current collecting electrode 6 flatly surrounds the print bar and preferably consists of a piece of sheet metal with a central opening as a recess for the print head 30.
  • the measuring voltage is tapped virtually without power by integrating a non-inverting amplifier 13 - shown in FIG. 6 - into the measuring branch:
  • U B (R n / R d ) * [(R d + R s ) / (R t + R n )] * U m
  • the resistance ratio allows the basic gain to be set.
  • the total energy required when printing a column in which all printing electrodes are applied simultaneously is approximately 80% of the printing energy per dot.
  • a protective circuit 17 contains a Zener diode, which limits the reference voltage to U B + +10 V and is preferably connected in parallel to the negative feedback resistor R s .
  • the protective circuit 17 is intended to prevent the destruction of the print head in the event of a fault and, for this purpose, interacts with the print control unit (DS) and with a switching element S.
  • a measuring device consists of at least one Schmitt trigger, comparator or threshold switch, which can be queried by the pressure control unit 5 in order to interrupt the printing operation if necessary and emit an error message.
  • the linear regulator 11 shown in FIG. 3 has a means 16 for setting the print voltage U p . It is provided that the means 16 is an adjusting resistor.
  • the means 16 for setting the print voltage U p is an actuator which can be controlled electronically via line D ⁇ of the pressure control unit 5 and by means of which a control value ⁇ is set for a specific tape speed V bj depending on the material of the recording medium used, in particular the type of paper becomes.
  • the energization time t j assigned for a defined belt speed V bj is preset by the print control unit 5 via the strobe pulse duration t j in accordance with the desired contrast in the print image.
  • the actuator 16 is controlled by the pressure control unit 5 to a lower actuating value ⁇ , so that the print voltage is set to a harmless value of ⁇ U p ⁇ 1 V.
  • the other fault case when the reference voltage U B is too low values is evaluated by a second one measuring means 19 which can also be queried by the pressure control unit 5.
  • the measuring means 19 also has at least one threshold switch, comparator or Schmitt trigger.
  • the threshold value of each measuring means 18, 19, 20 is preferably set in accordance with a defined number n of electrodes to be activated simultaneously.
  • An error message is then issued by the print control unit 5 when a suitable location in the print image is printed and the correspondingly set threshold value is not reached or exceeded.
  • the protective circuit 17 has a Zener diode ZD and a window comparator 20 which can be queried by the pressure control unit 5 and whose output is present at the D input of a buffer store 21.
  • the measurement takes place at the end of the transient process, since the signal D st triggering the measurement is connected via a delay circuit 22 for the strobe pulse to the clock input of the buffer memory 21, which can be acted upon by a reset pulse (D 1 ) and one for Pressure control unit 5 has leading data output D d .
  • the advantageous variant of the adapter circuit shown in FIG. 6 has at least one window comparator, which can be queried by the pressure control unit 5, the output of which is present at the D input of a D flip-flop 21, that has a strobe pulse at a delay circuit 22 Corresponding signal D st is present and the output is connected to the clock input of the D flip-flop 21, which can be acted upon with a reset pulse by means of a signal enable corresponding L latch and has a data output D d .
  • the electrodes of the printhead 30 that are not currently being driven are used as measuring electrodes together with the measuring electrode 29 for the measurement. All or some of the voltages U 1 to U 4 are tapped at the outputs Q 1 to Q x of the switching unit 2 and in each case to the inputs e 1 to e 4 and the voltage U m tapped at the measuring electrode 29 to the input e 9 of the Matching circuit 12 placed.
  • the matching circuit 12 has a circuit for evaluating a plurality of DC voltages with regard to the lowest DC voltage, consisting of a corresponding number of non-inverting operational amplifiers 15, each with a diode D connected on the output side.
  • the protection circuit 17 also contains a Zener diode, measuring means 18, 19 or 20, buffer store 21 and a pulse delay circuit 22, as has already been explained with reference to FIG.
  • This type of control of the print head with the help of an adjustable constant voltage source 11 has the Advantage that with the help of at least one non-activated printhead electrode a voltage drop U m in the resistance ribbon is measured during the ETR printing or franking process, that the compensation of the variance of the voltage drop U p existing in the resistance ribbon 10 due to the above-mentioned influences by means of the for the activated Pressure electrodes from the supply voltage U s provided by the constant voltage source 11 are carried out and that an evaluation and appropriate control can be carried out by the pressure control unit 5 to ensure the functionality and for a high print quality.
  • the invention is not limited to the present embodiment. Rather, a number of variants are conceivable which make use of the solution shown, even in the case of fundamentally different types.

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Claims (20)

  1. Circuit sélecteur pour un dispositif d'impression électrothermique muni de résistances sur bande, connectées électriquement à une électrode de captage et aux électrodes d'une tête d'impression et qui, pour chacun des pixels de l'impression, transfère des particules encrées sur un support d'enregistrement par chauffage sélectif, muni d'un organe de mémorisation et d'une unité de commande de l'impression opérant sur un bloc de commutation de l'unité d'impression, une tension, définie par une source de tension, étant alors mise à disponibilité des électrodes sous excitation d'une tête d'impression, pour chaque élément sélectif de la voie de courant pendant un temps de mise sous tension prédéterminé t j , et de même que muni de dispositifs de mesure pour la détermination de chute de tension dans la bande à résistances,
    caractérisé par le fait
    - que la source de tension présente une source à tension constante (1) munie d'une entrée pour une tension de référence UB , établie à partir de la chute de tension Um mesurée à partir de l'élément non-sélectif de la voie de courant dans la bande à résistances (10),
    - que la source a tension constante (1) soit contactée entre la tension de référence UB et l'unité de commande (2) en addition à la tension de référence UB de telle manière qu'aux électrodes temporairement excitées (31, 32, 33, ...,), face au potentiel de l'électrode de captage, soit présente une tension d'alimentation US égale à la somme d'une tension constante à définition variable αUp et de la tension de référence établie UB.
  2. Circuit sélecteur, selon la revendication 1, caractérisé par le fait que la tension de mesure soit équivalente à une chute de tension provoquée par l'intensité totale Ig et par la variance des résistances, sur la voie de courant non sélective (voie de retour) dans la bande à résistances et qu'elle soit mesurée à l'aide d'une ou plusieurs électrodes placées sur ou près de la tête d'impression, l'électrode de mesure étant alors une électrode non activée contactant la bande à résistances, et caractérisé par le fait que, pendant la durée de mise sous tension t j, les électrodes (31,32,33, . .) reliées temporairement à la source à tension constante (1) par l'intermédiaire du bloc de commutation (2) et les résistances self Rv soient sous une tension dont la valeur présente une dépendance semblable du nombre temporairement variable n d'électrodes activées de manière qu'un nombre supérieur d'électrodes activées soit alimenté avec une tension supérieure plutôt qu'un nombre plus petit.
  3. Circuit sélecteur, selon les revendications 1 et 2, caractérisé par le fait que la source à tension constante (1) soit partie intégrante d'une unité d'alimentation en courant (SVE), comprenant un bloc d'alimentation (14) qui1 délivre une première tension Ug et une seconde tension Uc pour l'alimentation du bloc de commutation (2), caractérisé par le fait qu'un régulateur linéaire (11) soit utilisé en tant que source à tension constante réglable, régulateur qui recevra la première tension Ug et qui délivrera à la sortie la tension Us pour l'alimentation d'un excitateur logé dans le bloc de commutation (2) et par le fait que, entre l'entrée de commande du régulateur linéaire (11) et l'électrode de mesure soit introduit un circuit d'accommodation (12) qui réalise la tension de référence UB à partir de la tension de mesure Um analogique.
  4. Circuit sélecteur pour un dispositif d'impression électrothermique muni de résistances sur bande, connectées électriquement à une électrode de captage et aux électrodes d'une tête d'impression et qui, pour chacun des pixels de l'impression, transfère des particules encrées sur un support d'enregistrement par chauffage sélectif, muni d'un organe de mémorisation et d'une unité de commande de l'impression opérant sur un bloc de commutation de l'unité d'impression, une tension, définie par une source de tension, étant alors mise à disponibilité des électrodes sous excitation d'une tête d'impression, pour chaque élément sélectif de la voie de courant pendant un temps de mise sous tension prédéterminé t j , et de même que muni de dispositifs de mesure pour la détermination de chute de tension dans la bande à résistances,
    caractérisé par le fait
    - que la source de tension présente un circuit de commutation à tension constante (1) munie d'une entrée pour une tension de référence UB , établie à partir de la chute de tension Um mesurée à partir de l'élément non-sélectif de la voie de courant dans la bande à résistances (10) ; en cas d'une valeur amoindrie de la tension de référence UB face à la tension de mesure Um , la valeur de la tension d'alimentation US devra présenter d'une part une dépendance semblable du nombre temporairement variable n d'électrodes activées, de manière qu'un nombre supérieur d'électrodes activées simultanément soient sous une tension d'alimentation plus élevée US mais avec une énergie d'impression par dot plus faible, plutôt qu'un nombre inférieur d'électrodes activées simultanément, alimentées en cas d'une tension d'alimentation plus faible avec une énergie d'impression plus forte par dot. Il est caractérisé de même par le fait que la source à tension constante (1) soit contactée entre la tension de référence UB et l'unité de commande (2) en addition à la tension de référence UB de telle manière qu'aux électrodes temporairement excitées (31, 32, 33, ...,), face au potentiel de l'électrode de captage, soit présente une tension d'alimentation US égale à la somme d'une tension constante à définition variable αUp et de la tension de référence établie UB.
  5. Circuit sélecteur, selon la revendication 3, caractérisé par le fait que le régulateur linéaire (11) présente un dispositif (16) pour le réglage de la tension d'impression Up.
  6. Circuit sélecteur, selon la revendication 5, caractérisé par le fait que le dispositif (16) soit un rhéostat de réglage.
  7. Circuit sélecteur, selon la revendication 6, caractérisé par le fait que le dispositif (16) prévu pour le réglage de la tension d'impression Up soit un actionneur, qui puisse être activé de manière électronique par l'unité de commande de l'impression (5),permettant ainsi de régler une valeur α par le biais de circuit Dα, en fonction de la matière du support d'enregistrement, en particulier du type de papier utilisé, pour une vitesse de ruban déterminée Vbj.
  8. Circuit sélecteur, selon l'une des revendications précédentes de 1 à 7, caractérisé par le fait que la durée de mise sous tension Tj affectée à une vitesse de ruban Vbj déterminée soit préréglée par l'unité de commande de l'impression (5) pour correspondre au contraste désiré pour l'objet imprimé.
  9. Circuit sélecteur, selon l'une des revendications précédentes de 1 à 8, caractérisé par le fait que le dispositif d'impression présente une électrode de mesure (29) étendue, placée spécialement sur l'un des côtés de la barre d'impression et une autre, placée de l'autre côté et connectée à une électrode de captage reliée au potentiel de masse.
  10. Circuit sélecteur, selon l'une des revendications de 1 à 8, caractérisé par le fait que le dispositif d'impression présente une unique électrode de captage (6) de grande surface munie d'un orifice pour la tête d'impression(30) et l'électrode de mesure (29).
  11. Circuit sélecteur, selon l'une des revendications précédentes de 1 à 10, caractérisé par le fait que les électrodes d'impression en l'état désactivé de la tête d'impression (30) soient utilisées pour la prise de mesure, en tant qu'électrodes de mesure en liaison avec l'électrode de mesure (29) et par le fait que, aux sorties Q1 jusqu'à Qx du bloc de commutation (2), tout ou une partie des tensions U1, U2, U3, U4, ..., soient saisies et respectivement mises aux entrées e1, e2, e3, e4,..., et que la tension Um à l'électrode de mesure (29) soit mise à l'entrée e9 du circuit d'accommodation (12)
  12. Circuit sélecteur, selon les revendications 3 et 4, caractérisé par le fait que le circuit d'accommodation (12) présente au moins un amplificateur opérationnel (13) non invertisseur avec une amplification réglable de la tension.
  13. Circuit sélecteur, selon la revendication 12, caractérisé par le fait que l'amplificateur opérationnel (13) non invertisseur soit monté comme amplificateur de tension à facteur 1 ou qu'il présente une amplification de tension telle VU = 1.
  14. Circuit sélecteur, selon l'une des revendications précédentes de 11 à 13, caractérisé par le fait que le circuit prévu pour l'évaluation de plusieurs tensions continues, eu égard à la tension continue la plus basse dans le circuit d'accommodation (12) soit constitué d'un nombre correspondant d'amplificateurs opérationnels non invertisseurs (15) munis chacun d'une diode D connectée à la sortie, chaque diode D étant connectée, directement ou par l'intermédiaire d'un diviseur de tension, avec la sortie de l'amplificateur par la zone de type n de la diode et avec l'entrée invertisseur (-) de l'amplificateur (15) avec la zone de type p.
  15. Circuit sélecteur, selon l'une des revendications précédentes de 1 à 14, caractérisé par le fait que les résistances self RV placées entre la sortie de l'excitateur du bloc de commutation (2) et les électrodes présentent une valeur située entre un huitième et un centième de la valeur de la résistance thermique Rh dans la couche résistive d'une bande à résistances.
  16. Circuit sélecteur, selon l'une des revendications précédentes de 1 à 15, caractérisé par le fait que le circuit d'accommodation (12) comprenne un circuit de protection (17) connecté à la sortie de l'amplificateur muni d'une diode zener et d'un dispositif de mesure (18, 19, 20) qui soit constitué d'au moins un trigger de Schmitt, d'un comparateur, d'un commutateur valeur-seuil et/ou d'un comparateur à fenêtre de sélection, que l'unité de commande de l'impression (5) peut interroger, en vue d'interrompre, le cas échéant, l'impression et de produire un message d'erreur.
  17. Circuit sélecteur, selon la revendication 16, caractérisé par le fait que le circuit de protection (17) soit équipé d'une diode zener et d'un dispositif de mesure (18, 19, 20) et d'une mémoire temporaire (22)que l'unité de commande de l'impression (5) peut interroger, en vue d'interrompre, le cas échéant, l'impression et de produire un message d'erreur.
  18. Circuit sélecteur, selon la revendication 17, caractérisé par le fait que le dispositif de mesure (20) présente au moins un des comparateurs à fenêtre de sélection (20) interrogeables par l'unité de commande de l'impression (5), dont la sortie est reliée à l'entrée D du flip-flop D, et caractérisé par le fait qu'à un circuit de délai (22) soit relié un signal Dst correspondant à une impulsion stroboscopique et que la sortie soit reliée à l'entrée du temporisateur du flip-flop D (21), pouvant admettre une impulsion de remise à l'état initial par l'intermédiaire d'un signal D1 correspondant à un latch activé et qu'il présente une sortie données Dd.
  19. Circuit sélecteur, selon la revendication 18, caractérisé par le fait qu'un élément contacteur S relié au potentiel de masse soit raccordé à l'entrée non invertisseur de l'amplificateur (13, 15), la tension de mesure Um et par conséquent UB étant réglable sur UB = 0 V à l'aide de l'élément contacteur S , en cas d'un signal Du pour interrompre le déroulement de l'impression.
  20. Circuit sélecteur, selon les revendications 7 et 19, caractérisé par le fait que, en cas d'interruption du déroulement de l'impression la valeur de régulation ∝ soit modifiée.
EP92250246A 1992-06-26 1992-09-04 Circuit de commande pour système d'impression thermique avec ruban résistif Expired - Lifetime EP0575668B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4221275A DE4221275C2 (de) 1992-06-26 1992-06-26 Ansteuerschaltung für eine elektrothermische Druckvorrichtung mit Widerstandsband
DE4221275 1992-06-26

Publications (3)

Publication Number Publication Date
EP0575668A2 EP0575668A2 (fr) 1993-12-29
EP0575668A3 EP0575668A3 (fr) 1994-03-16
EP0575668B1 true EP0575668B1 (fr) 1997-03-12

Family

ID=6462061

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92250246A Expired - Lifetime EP0575668B1 (fr) 1992-06-26 1992-09-04 Circuit de commande pour système d'impression thermique avec ruban résistif

Country Status (4)

Country Link
US (1) US5482386A (fr)
EP (1) EP0575668B1 (fr)
CA (1) CA2080427A1 (fr)
DE (4) DE4221275C2 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4221275C2 (de) * 1992-06-26 1994-04-21 Francotyp Postalia Gmbh Ansteuerschaltung für eine elektrothermische Druckvorrichtung mit Widerstandsband
GB9410273D0 (en) * 1994-05-20 1994-07-13 Prestek Ltd Printing apparatus
US5702188A (en) * 1995-07-18 1997-12-30 Graphtec Corporation Thermal head and head drive circuit therefor
SE9702933L (sv) * 1997-08-14 1998-07-06 Intermec Ptc Ab Metod för energistyrning av tryck med transferband och direkttermomaterial i termoskrivare

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0067969A2 (fr) * 1981-06-19 1982-12-29 International Business Machines Corporation Circuit de commande pour imprimante thermique

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Publication number Priority date Publication date Assignee Title
DE2100611C3 (de) * 1970-01-09 1978-05-03 Ing. C. Olivetti & C., S.P.A., Ivrea, Turin (Italien) Elektrothermische Druckvorrichtung
JPS6027577B2 (ja) * 1980-03-12 1985-06-29 株式会社東芝 熱記録装置
US4350449A (en) * 1980-06-23 1982-09-21 International Business Machines Corporation Resistive ribbon printing apparatus and method
JPS5763280A (en) * 1980-10-03 1982-04-16 Ricoh Co Ltd Driving circuit for heat-sensitive recorder
US4470714A (en) * 1982-03-10 1984-09-11 International Business Machines Corporation Metal-semiconductor resistive ribbon for thermal transfer printing and method for using
US4434356A (en) * 1982-12-22 1984-02-28 International Business Machines Corporation Regulated current source for thermal printhead
JPS60143981A (ja) * 1983-12-29 1985-07-30 Konishiroku Photo Ind Co Ltd サ−マルプリンタ
US4531134A (en) * 1984-03-26 1985-07-23 International Business Machines Corporation Regulated voltage and approximate constant power for thermal printhead
JPS60210472A (ja) * 1984-04-03 1985-10-22 Konishiroku Photo Ind Co Ltd サ−マルヘツド保護回路
US4575731A (en) * 1984-10-30 1986-03-11 International Business Machines Corporation Electro resistive printhead drive level sensing and control
GB2169853B (en) * 1985-01-19 1988-11-02 Francotyp Postalia Gmbh Improvements in movement monitoring devices
JPS6246659A (ja) * 1985-08-26 1987-02-28 Toshiba Corp プリンタのサ−マルヘツド駆動制御装置
JPS637952A (ja) * 1986-06-30 1988-01-13 Matsushita Electric Ind Co Ltd 通電記録装置
EP0301891B1 (fr) * 1987-07-31 1992-01-29 Kabushiki Kaisha Toshiba Imprimante électrothermique avec ruban encré à résistance
US5063394A (en) * 1988-07-26 1991-11-05 Kabushiki Kaisha Toshiba Thermal recording apparatus and print head
DE3833746A1 (de) * 1988-09-30 1990-04-05 Siemens Ag Thermodruckverfahren mit vorheizung
JPH074644Y2 (ja) * 1989-11-10 1995-02-01 アルプス電気株式会社 負荷制御回路の自己診断回路
DE4214545C2 (de) * 1992-04-29 1996-08-14 Francotyp Postalia Gmbh Anordnung für eine ETR-Druckkopfansteuerung
DE4221275C2 (de) * 1992-06-26 1994-04-21 Francotyp Postalia Gmbh Ansteuerschaltung für eine elektrothermische Druckvorrichtung mit Widerstandsband

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
EP0067969A2 (fr) * 1981-06-19 1982-12-29 International Business Machines Corporation Circuit de commande pour imprimante thermique

Also Published As

Publication number Publication date
EP0575668A2 (fr) 1993-12-29
DE4221275A1 (de) 1994-01-13
DE4342510C2 (de) 1997-03-20
DE4342508C2 (de) 1997-05-22
US5482386A (en) 1996-01-09
EP0575668A3 (fr) 1994-03-16
CA2080427A1 (fr) 1993-12-27
DE4342510A1 (de) 1995-06-14
DE59208192D1 (de) 1997-04-17
DE4342508A1 (de) 1995-06-14
DE4221275C2 (de) 1994-04-21

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