EP0805021B1 - Process for the regulation of the temperature within a device for the inscription of printing plates using a laser radiation particularly for an offset printing machine - Google Patents

Process for the regulation of the temperature within a device for the inscription of printing plates using a laser radiation particularly for an offset printing machine Download PDF

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Publication number
EP0805021B1
EP0805021B1 EP97105896A EP97105896A EP0805021B1 EP 0805021 B1 EP0805021 B1 EP 0805021B1 EP 97105896 A EP97105896 A EP 97105896A EP 97105896 A EP97105896 A EP 97105896A EP 0805021 B1 EP0805021 B1 EP 0805021B1
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EP
European Patent Office
Prior art keywords
laser diode
diode unit
switched
heat quantity
heat
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EP97105896A
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German (de)
French (fr)
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EP0805021A3 (en
EP0805021A2 (en
Inventor
Helmut Meyer
Johann Schunn
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Presstek LLC
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Heidelberger Druckmaschinen AG
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41CPROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C1/00Forme preparation
    • B41C1/10Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
    • B41C1/1083Mechanical aspects of off-press plate preparation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J29/00Details of, or accessories for, typewriters or selective printing mechanisms not otherwise provided for
    • B41J29/377Cooling or ventilating arrangements

Definitions

  • the invention relates to a method and a device for regulating the temperature in a printing plate labeling unit working with laser light, in particular one Offset printing machine according to the preamble of claims 1 and 8.
  • the labeling units have a light source, the light of which comes from a optical lens system is focused on the respective point of the printing plate and the depending on whether an image point is generated on the printing plate at the corresponding point should be switched on or off.
  • DE 36 03 548 A1 describes a method for determining and regulating the Temperature of a laser diode operated in pulse mode in a xerographic Printer in which a constant current is passed through during the exposure period of the laser radiation the diode is conducted, which is smaller than the minimum current which is used to generate the Laser radiation is needed. Depending on one with the constant current through the voltage associated with the laser diode is then controlled by the laser diode feeding current. Furthermore, a heating-cooling unit is provided, which for one for the laser diode is activated to cool the laser diode and dangerous temperature hereby set the current of the laser diode back to a basic value.
  • the font gives no indication of a heat source alternating with the laser diode unit in to operate in such a way that the temperature of the laser diode unit is as constant as possible is held.
  • US 5,351,617 also shows a device in which several optical focusing units that use optical Fiber optic cables to corresponding laser light sources connected, can be moved over a flat pressure plate and expose them in the appropriate places.
  • the loss of quality results from the fact that at a fluctuating light intensity of the laser light leading to a low or too high temperature of the respective laser diode is due to be generated on the printing plate Pixels vary greatly, so that with the printing plate generated print image has errors related to the above perceptible loss of quality described.
  • the temperature fluctuations of the laser diodes are in the Inscription of a printing plate generated in particular by that the laser diodes in the on state a large part the electrical energy supplied to them in Joule heat convert, and when switched off, i.e. to the Places where there is no imaging from the Laser diodes generate no heat.
  • Step into practice hereby in particular in the areas of the pressure plate, in those of the corresponding laser diode unit only individual pixels are set, high quality losses on, because the switched off for a longer period
  • the laser diode unit cools down and as a result when switching on again, due to the heating of the Laser diode necessary time, a shorter one Light intensity generated.
  • the object of the invention is to solve a problem Process for regulating the temperature in a laser light creating working printing plate labeling unit, with which the temperature of the laser light generating Laser light source, especially a laser diode, in high Dimensions and can be kept constant with simple means.
  • the invention has the particular advantage that even with labeling units with a larger one Number of individual laser diode units and associated ones Focusing optics a high consistency and associated with it high quality in the generation of the individual pixels on the printing plate across the entire image leaves.
  • the device according to the invention has the Advantage that they are simple and inexpensive with existing printing plate labeling units, both for flat printing plates as well as for one Retrofit printing plate cylinders with mounted printing plates leaves.
  • the device 1 for labeling shown in FIG. 1 one on a printing plate cylinder 2 of a printing press clamped printing plate 4 has one or more, for example 16 individual Printing plate labeling units 5, of which in Fig. 1 overall for technical reasons only two units are shown.
  • Labeling units 5 also for labeling flat pressure plates can be used.
  • Each of the Labeling units 5 includes a near the Pressure plate 4 arranged focusing optics 6, which an optical light guide 8 to a laser diode unit 10 connected.
  • the optical focusing optics 6 focuses what is generated by the laser diode unit 10 Laser light on one to be generated on the printing plate 4 Pixel where there is an area corresponding to the pixel removed from the surface layer of the pressure plate 4, so that an underlying ink accepting layer is exposed.
  • the structure and composition of a such printing plate are for example from US 5,351,617 are known and are not described further here.
  • the laser diode unit 10 is controlled via a Control device 12, which the laser diode unit in Dependence on one to be set or not to be set Pixel corresponding to one generated in the prepress Turns bit pattern on or off.
  • the laser diode units 10 are in one Housing 14 housed, which on a basic or Carrier body 16 is attached. Near the Laser diode unit 10, preferably within the Housing 14, a heating element 18 is arranged, which by the control device 12 is actuated. The actuation of the heating element 18 takes place through the Control device 12 alternately or in push-pull with the Laser diode unit 10 in such a way that when switched off Laser diode unit 10, the heating element 18 is actuated and this heats the switched-off laser diode unit 10. At the Turning on the laser diode unit 10, i.e.
  • the heating element 18 when labeling the printing plate 4 with a pixel, that is Heating element 18 turned off, so that during the Time in which the laser diode unit 10 is switched on, no thermal energy is generated.
  • the heating element 18 by an ohmic resistance which alternates with the Laser diode unit 10 corresponding to a high or a low electrical voltage is connected.
  • the heating element 18 by any other Joule heat-generating electronic component is formed be that in push-pull to the laser diode unit 10 to a appropriate current and / or voltage source connected becomes.
  • a component can be, for example, a transistor, a diode or a so-called Peltier element etc.
  • the heating element 18 in the housing 14 of the laser diode unit 10 can also be outside the housing 14 for example on this or on the base body 16 be arranged.
  • the Inscription unit 5 supporting body 16 of the To constantly cool or heat device 1 for example in that the base body 16 inside is hollow and the interior of one appropriate cooling or heat transport medium desired Temperature, as indicated by arrows 20, 22, is flowed through.
  • the base body 16 inside is hollow and the interior of one appropriate cooling or heat transport medium desired Temperature, as indicated by arrows 20, 22, is flowed through.
  • one from a cooling or Heat medium flowing through the base body 16 can in be heated electrically in the same way.
  • the regulation of the temperature of the laser diode unit 10 by the heating element 18 can be, for example, with one in FIG. 2 Electronic circuit arrangement 30 shown be made.
  • the circuit arrangement 30 has one Current and / or voltage source 32, at one pole, for example the plus pole, the control device 12 and the heating element 18 and, in parallel, the Laser diode unit 10 are connected.
  • the heating element 18 and the laser diode unit 10 are still above each associated power transistors 34 and 36 with the second Pol of the current and / or voltage source 32 connected.
  • the Base of the power transistor 34 of the heating element 18 is preferably via a fixed or adjustable resistor 35 connected to the control device 12.
  • the basis of the Power transistor 36 of the laser diode unit 10 is preferably via a second fixed or adjustable Resistor 37 and an inverting Schmitt trigger circuit 38 with the control device 12 connected.
  • the control device 12 controls the bases of the Power transistors 34 and 36 in push-pull operation, so that with the laser diode unit 10 switched off, the heating element 18 a current flows through it, the size of which exceeds Resistor 35 for the respective heating element 18 Printing plate labeling unit 5 set accordingly can be.
  • the inverting Schmitt trigger 38 at the base of the Power transistor 36 of the laser diode unit 10 is applied Signal inverted so that the power transistor 36 blocks and the laser diode unit 10 remains switched off.
  • the Control device 12 To the Switching on the laser diode unit 10 is done by the Control device 12 a signal of reverse polarity generated and corresponding to the power transistor 34 of the Heating element 18 blocked and the power transistor 36 due to the inverting effect of the Schmitt trigger circuit 38 switched through, so that the A current flows through the laser diode unit 10, whose size is adjustable via the resistor 37.
  • the Generating the signals by the control device 12 takes place depending on one to be set Pixel on the printing plate 4.
  • FIG. 3 The course of the voltage U R applied to the heating element 18 and the voltage U LD applied to the laser diode unit 10 at the same time are shown in FIG. 3 in an idealized form.
  • the heating element 18 is connected to the voltage source 32 during the preheating phase V or, in an equivalent manner, to a corresponding current source and emits a certain amount of heat Q R , the size of which is preferably regulated in this way via the adjustable resistor 35 becomes that the temperature of the laser diode unit 10 switched off at this time adjusts to a desired working temperature.
  • the voltage U LD applied to the laser diode unit 10 during the preheating phase V in this embodiment of the invention is preferably 0 volts, so that the amount of heat generated by the laser diode unit 10 is also corresponding to 0 J (joules) per unit time.
  • the laser diode unit 10 is switched on by applying the voltage U LD and the heating element 18 is switched off at the same time, that is to say alternately or in push-pull.
  • the amount of heat emitted by the laser diode unit 10 per unit of time Q LD and the amount of heat emitted by the heating element 18 per unit of time Q R are preferably essentially the same, depending on the arrangement of the heating element 18 or the preheating of the base body 16 or total radiated thermal power, the heat quantity Q R radiated by the heating element 18 can also be smaller or larger than the heat quantity Q LD radiated by the laser diode unit 10.
  • the amounts of heat can be adjusted, for example, via the adjustable resistors 35, 37 of the circuit arrangement shown in FIG. 2, the adjustment preferably being carried out in such a way that the temperature fluctuations between switching the laser diode unit on and off are as small as possible.
  • the heating element 18, as shown in FIG. 4 is supplied with a preferably adjustable basic voltage U R1 , or a corresponding basic current, even when the laser diode unit 10 is switched on, and emits a first basic heat quantity Q R1 , which is shown in the upper diagram 4 is shown as a dashed line.
  • the heating element 18 is connected to a second higher voltage U R2 , as a result of which it generates the amount of heat Q R2 per unit of time.
  • the difference between the amounts of heat Q R1 and Q R2 emitted by the heating element 18 in this embodiment of the invention is preferably selected such that the temperature fluctuations or the temperature difference of the laser diode unit 10 between the switched-off and switched-on state is minimal.
  • the heat quantities Q R1, Q R2 and Q LD as well as the corresponding voltages U R1 , U R2 and U LD , in particular the difference between Q R2 and Q R1 can also have a different value, depending on the radiation emitted to the environment Amount of heat per unit of time, the thermal conductivity of the individual components, the arrangement and design of the heating element 18, the preheating of the carrier body 16 or housing 14 etc. preferably empirically by adjusting the voltage and / or the current via the adjustable resistors 35, 37 in the manner it is determined that the temperature differences of the laser diode unit 10 become as small as possible.
  • the heating element 18 is switched off accordingly preferably at the same time.
  • the heating element 18 can then be a short one Time span over the time when the Laser diode unit 10 remain switched on.
  • Embodiment of the invention may also be provided the base body 16 and the Laser diode units 10 and / or their housing with a To provide a layer of thermal insulation material, so that fluctuations in ambient temperature are less or almost no influence on the temperature of the Have laser diode units 10.

Description

Die Erfindung betrifft ein Verfahren und eine Vorrichtung zur Regelung der Temperatur in einer mit Laserlicht arbeitenden Druckplatten-Beschriftungseinheit, insbesondere einer Offset-Druckmaschine, gemäß dem Oberbegriff von Anspruch 1 und 8.The invention relates to a method and a device for regulating the temperature in a printing plate labeling unit working with laser light, in particular one Offset printing machine according to the preamble of claims 1 and 8.

Für die Beschriftung von Druckplatten, die in Druckmaschinen Verwendung finden, werden heutzutage neben der herkömmlichen Methode einer Belichtung mittels Filmen in verstärktem Maße digital arbeitende Beschriftungseinheiten eingesetzt, denen die Bildinformation in Form von digitalen, in der Druckvorstufe erzeugten Bit-Mustern zugeführt wird, die von den Beschriftungseinheiten auf die Druckplatte übertragen werden. Die Beschriftungseinheiten besitzen hierfür eine Lichtquelle, deren Licht durch ein optisches Linsensystem auf die jeweilige Stelle der Druckplatte fokussiert wird und die je nach dem, ob auf der Druckplatte an der entsprechenden Stelle ein Bildpunkt erzeugt werden soll, ein- oder ausgeschaltet wird.For labeling printing plates that are used in printing machines, are nowadays used in addition to the conventional method of exposure using films in Digitally working labeling units are increasingly used, which the image information in the form of digital bit patterns generated in the prepress is supplied, which are transferred from the labeling units to the printing plate become. For this purpose, the labeling units have a light source, the light of which comes from a optical lens system is focused on the respective point of the printing plate and the depending on whether an image point is generated on the printing plate at the corresponding point should be switched on or off.

Die DE 36 03 548 Al beschreibt ein Verfahren zur Bestimmung und Regelung der Temperatur von einer im Impulsbetrieb betriebenen Laserdiode in einem xerographischen Drucker, bei dem während der Aussetzdauer der Laserstrahlung ein konstanter Strom durch die Diode geleitet wird, der kleiner ist als der Minimalstrom, welcher zur Erzeugung der Laserstrahlung benötigt wird. In Abhängigkeit von einer mit dem konstanten Strom durch die Laserdiode einhergehenden Spannung erfolgt dann eine Steuerung des die Laserdiode speisenden Stromes. Weiterhin ist eine Heiz-Kühl-Einheit vorgesehen, welche bei einer für die Laserdiode gefährlichen Temperatur aktiviert wird, um die Laserdiode zu kühlen und hierdurch den Strom der Laserdiode wieder auf einen Grundwert einzustellen. Die Schrift gibt keinen Hinweis darauf, eine Wärmequelle im Wechsel mit der Laserdiodeneinheit in der Weise zu betreiben, daß die Temperatur der Laserdiodeneinheit möglichst konstant gehalten wird.DE 36 03 548 A1 describes a method for determining and regulating the Temperature of a laser diode operated in pulse mode in a xerographic Printer in which a constant current is passed through during the exposure period of the laser radiation the diode is conducted, which is smaller than the minimum current which is used to generate the Laser radiation is needed. Depending on one with the constant current through the voltage associated with the laser diode is then controlled by the laser diode feeding current. Furthermore, a heating-cooling unit is provided, which for one for the laser diode is activated to cool the laser diode and dangerous temperature hereby set the current of the laser diode back to a basic value. The font gives no indication of a heat source alternating with the laser diode unit in to operate in such a way that the temperature of the laser diode unit is as constant as possible is held.

Aus der US 5,351,617 ist eine mit Laserlicht arbeitende Beschriftungseinheit für die mit einer speziellen Beschichtung versehene und auf den Druckplattenzylinder einer Offset-Druckmaschine aufgespannte Druckplatte bekannt, bei der das Laserlicht durch eine Laserdiodeneinheit erzeugt wird und anschließend über ein optisches Lichtleiterkabel einer nahe dem Druckplattenzylinder angeordneten optischen Fokussierungseinheit zugeführt wird, die motorisch parallel zur Druckplattenzylinderlängsachse über die Oberfläche des Druckplattenzylinders bewegt wird und die das Laserlicht auf die entsprechenden Stellen der Druckplatte fokussiert. Durch entsprechendes Drehen des Druckplattenzylinders erfolgt eine Bebilderung der auf den Zylinder aufgespannten Druckplatte auf deren gesamter Fläche.From US 5,351,617 is a labeling unit working with laser light for the a special coating and one on the printing plate cylinder Offset printing machine clamped printing plate known in which the laser light through a Laser diode unit is generated and then an optical fiber cable optical arranged near the printing plate cylinder Focusing unit is fed, the motor parallel to the longitudinal axis of the printing plate cylinder over the surface of the Printing plate cylinder is moved and the laser light on the corresponding areas of the printing plate are focused. By the printing plate cylinder is rotated accordingly Illustration of the printing plate clamped on the cylinder over their entire area.

Die US 5,351,617 zeigt weiterhin eine Vorrichtung, bei der mehrere optische Fokussierungseinheiten, die über optische Lichtleiterkabel an entsprechende Laserlichtquellen angeschlossen sind, über eine ebene Druckplatte bewegt werden und diese an den entsprechenden Stellen belichten.US 5,351,617 also shows a device in which several optical focusing units that use optical Fiber optic cables to corresponding laser light sources connected, can be moved over a flat pressure plate and expose them in the appropriate places.

Bei den beschriebenen, mit Laserdioden arbeitenden Beschriftungs- oder Bebilderungseinheiten tritt das Problem auf, daß die Intensität des Laserlichts in hohem Maße von der Temperatur der jeweiligen Laserlichtquelle, in diesem Falle einer Laserdiode, beeinflußt wird. So sind aufgrund der bekannterweise im wesentlichen exponentiellen Abhängigkeit der Intensität des erzeugten Laserlichts von der Temperatur bei einer Laserdiode bereits Temperaturschwankungen im Bereich von 0,5° bis 2°C ausreichend, um das Beschriftungsergebnis derart nachteilig zu beeinflussen, daß die dadurch hervorgerufenen Qualitätseinbußen im fertigen Druckbild ohne weiteres durch das menschliche Auge wahrgenommen werden können.In the described, working with laser diodes Labeling or imaging units experience the problem on that the intensity of the laser light to a large extent from the Temperature of the respective laser light source, in this case a laser diode is influenced. So are due to the known to be essentially exponential dependence the intensity of the laser light generated from the temperature with a laser diode, temperature fluctuations in the Range from 0.5 ° to 2 ° C is sufficient to achieve this To influence the labeling result so disadvantageously that the resulting loss of quality in the finished Print image easily by the human eye can be perceived.

Die Qualitätseinbußen ergeben sich dadurch, daß bei einer schwankenden Lichtintensität des Laserlichts, die auf eine zu geringe oder zu hohe Temperatur der jeweiligen Laserdiode zurückzuführen ist, auf der Druckplatte zu erzeugende Bildpunkte stark variieren, so daß das mit der Druckplatte erzeugte Druckbild Fehler aufweist, die zu den oben beschriebenen wahrnehmbaren Qualitätseinbußen führen. The loss of quality results from the fact that at a fluctuating light intensity of the laser light leading to a low or too high temperature of the respective laser diode is due to be generated on the printing plate Pixels vary greatly, so that with the printing plate generated print image has errors related to the above perceptible loss of quality described.

Die Temperaturschwankungen der Laserdioden werden bei der Beschriftung einer Druckplatte insbesondere dadurch erzeugt, daß die Laserdioden im eingeschalteten Zustand einen Großteil der ihnen zugeführten elektrischen Energie in Joulsche-Wärme umwandeln, und im ausgeschalteten Zustand, d.h. an den Stellen, an denen keine Bebilderung erfolgt, von den Laserdioden keine Wärme erzeugt wird. In der Praxis treten hierdurch insbesondere in den Bereichen der Druckplatte, in denen von der entsprechenden Laserdiodeneinheit nur vereinzelte Bildpunkte gesetzt werden, hohe Qualitätseinbußen auf, da die über einen längeren Zeitraum ausgeschaltete Laserdiodeneinheit zwischenzeitlich abkühlt und hierdurch beim Wiedereinschalten, bedingt durch die zum Aufheizen der Laserdiode notwendige Zeitdauer, eine geringere Lichtintensität erzeugt.The temperature fluctuations of the laser diodes are in the Inscription of a printing plate generated in particular by that the laser diodes in the on state a large part the electrical energy supplied to them in Joule heat convert, and when switched off, i.e. to the Places where there is no imaging from the Laser diodes generate no heat. Step into practice hereby in particular in the areas of the pressure plate, in those of the corresponding laser diode unit only individual pixels are set, high quality losses on, because the switched off for a longer period In the meantime, the laser diode unit cools down and as a result when switching on again, due to the heating of the Laser diode necessary time, a shorter one Light intensity generated.

Durch die Erfindung soll die Aufgabe gelöst werden, ein Verfahren zur Regelung der Temperatur in einer mit Laserlicht arbeitenden Druckplatten-Beschriftungseinheit zu schaffen, mit welchem die Temperatur der das Laserlicht erzeugenden Laserlichtquelle, insbesondere einer Laserdiode, in hohem Maße und mit einfachen Mitteln konstant gehalten werden kann.The object of the invention is to solve a problem Process for regulating the temperature in a laser light creating working printing plate labeling unit, with which the temperature of the laser light generating Laser light source, especially a laser diode, in high Dimensions and can be kept constant with simple means.

Weiterhin ist es eine Aufgabe der vorliegenden Erfindung, eine Vorrichtung zu schaffen, mit der sich die Temperatur der Laserlichtquelle einer Druckplatten-Beschriftungseinheit, insbesondere einer Laserdiode, mit einfachen Mitteln in effizienter und kostengünstiger Weise konstant halten läßt.It is also an object of the present invention to create a device with which the temperature of the Laser light source of a printing plate labeling unit, especially a laser diode, with simple means in can be kept constant in an efficient and cost-effective manner.

Diese Aufgabe wird gemäß der Erfindung durch die Merkmale von Anspruch 1 und 8 gelöst.This object is achieved according to the invention by the features of Claims 1 and 8 solved.

Weitere Merkmale der Erfindung sind in den Unteransprüchen enthalten. Further features of the invention are in the subclaims contain.

Durch die Erfindung ergibt sich insbesondere der Vorteil, daß sich auch bei Beschriftungseinheiten mit einer größeren Anzahl von einzelnen Laserdiodeneinheiten und zugehörigen Fokussierungsoptiken eine hohe Konstanz und damit verbunden eine hohe Qualität bei der Erzeugung der einzelnen Bildpunkte auf der Druckplatte über das gesamte Bild hinweg erzielen läßt.The invention has the particular advantage that even with labeling units with a larger one Number of individual laser diode units and associated ones Focusing optics a high consistency and associated with it high quality in the generation of the individual pixels on the printing plate across the entire image leaves.

Weiterhin besitzt die erfindungsgemäße Vorrichtung den Vorteil, daß sie sich in einfacher und kostengünstiger Weise bei bestehenden Druckplatten-Beschriftungseinheiten, sowohl für ebene Druckplatten als auch für auf einen Druckplattenzylinder aufgespannte Druckplatten nachrüsten läßt.Furthermore, the device according to the invention has the Advantage that they are simple and inexpensive with existing printing plate labeling units, both for flat printing plates as well as for one Retrofit printing plate cylinders with mounted printing plates leaves.

Die Erfindung wird im folgenden mit Bezug auf die Zeichnungen anhand bevorzugter Ausführungsformen beschrieben.The invention will now be described with reference to the drawings described using preferred embodiments.

In den Zeichnungen zeigen

Fig. 1
eine schematische Darstellung von zwei an einem Druckplattenzylinder einer Druckmaschine angeordneten Druckplatten-Beschriftungseinheiten mit erfindungsgemäßen Temperaturregelungsvorrichtungen,
Fig. 2
einen elektrischen Schaltplan einer bevorzugten Ausführungsform der erfindungsgemäßen Temperatur-Regelungsvorrichtung,
Fig. 3
einen Verlauf der am Widerstand beziehungsweise an der Laserdiode anliegenden elektrischen Spannung beziehungsweise der vom Widerstand bzw. der Diode abgegebenen Wärmemenge bei einer ersten Ausführungsform der Erfindung, bei der die am Widerstand anliegende Spannung bei Einschalten der Laserdiode auf Null heruntergefahren wird,
Fig. 4
eine weitere Ausführungsform der Erfindung, bei der am Heizelement bei ausgeschalteter Laserdiodeneinheit eine bestimmte Wärmemenge erzeugt wird, die nach Einschalten der Laserdiodeneinheit um eine vorherbestimmten Wert verringert wird.
Show in the drawings
Fig. 1
2 shows a schematic illustration of two printing plate labeling units arranged on a printing plate cylinder of a printing press with temperature control devices according to the invention,
Fig. 2
an electrical circuit diagram of a preferred embodiment of the temperature control device according to the invention,
Fig. 3
a curve of the electrical voltage applied to the resistor or to the laser diode or the amount of heat given off by the resistor or the diode in a first embodiment of the invention, in which the voltage applied to the resistor is reduced to zero when the laser diode is switched on,
Fig. 4
a further embodiment of the invention, in which a certain amount of heat is generated on the heating element when the laser diode unit is switched off and is reduced by a predetermined value after the laser diode unit is switched on.

Die in Fig. 1 dargestellte Vorrichtung 1 zum Beschriften einer auf einen Druckplattenzylinder 2 einer Druckmaschine aufgespannten Druckplatte 4 weist eine oder mehrere, beispielsweise 16 einzelne Druckplatten-Beschriftungseinheiten 5 auf, von denen in Fig. 1 insgesamt aus darstellungstechnischen Gründen lediglich zwei Einheiten gezeigt sind. In gleicher Weise wie zum Beschriften einer auf einen Druckmaschinenzylinder 2 aufgespannten Druckplatte 4 können die Beschriftungseinheiten 5 ebenfalls zur Beschriftung von ebenen Druckplatten eingesetzt werden. Jede der Beschriftungseinheiten 5 umfaßt eine in der Nähe der Druckplatte 4 angeordnete Fokussierungsoptik 6, die über einen optischen Lichtleiter 8 an eine Laserdiodeneinheit 10 angeschlossen ist. Die optische Fokussierungsoptik 6 fokusiert das von der Laserdiodeneinheit 10 erzeugte Laserlicht auf einen, auf der Druckplatte 4 zu erzeugenden Bildpunkt, wo es einen dem Bildpunkt entsprechenden Bereich aus der Oberflächenschicht der Druckplatte 4 entfernt, so daß eine darunterliegende, Druckfarbe annehmende Schicht freigelegt wird. Der Aufbau und die Zusammensetzung einer solchen Druckplatte sind beispielsweise aus der US 5,351,617 bekannt und werden hier nicht weiter beschrieben.The device 1 for labeling shown in FIG. 1 one on a printing plate cylinder 2 of a printing press clamped printing plate 4 has one or more, for example 16 individual Printing plate labeling units 5, of which in Fig. 1 overall for technical reasons only two units are shown. In the same way as for labeling on a printing press cylinder 2 clamped printing plate 4 can Labeling units 5 also for labeling flat pressure plates can be used. Each of the Labeling units 5 includes a near the Pressure plate 4 arranged focusing optics 6, which an optical light guide 8 to a laser diode unit 10 connected. The optical focusing optics 6 focuses what is generated by the laser diode unit 10 Laser light on one to be generated on the printing plate 4 Pixel where there is an area corresponding to the pixel removed from the surface layer of the pressure plate 4, so that an underlying ink accepting layer is exposed. The structure and composition of a such printing plate are for example from US 5,351,617 are known and are not described further here.

Die Steuerung der Laserdiodeneinheit 10 erfolgt über eine Steuerungseinrichtung 12, die die Laserdiodeneinheit in Abhängigkeit von einem zu setzenden oder nicht zu setzenden Bildpunkt entsprechend einem in der Druckvorstufe erzeugten Bit-Muster ein- oder ausschaltet. The laser diode unit 10 is controlled via a Control device 12, which the laser diode unit in Dependence on one to be set or not to be set Pixel corresponding to one generated in the prepress Turns bit pattern on or off.

Bei der bevorzugten, in Fig. 1 dargestellten Ausführungsform der Erfindung sind die Laserdiodeneinheiten 10 in einem Gehäuse 14 untergebracht, welches auf einem Grund- oder Trägerkörper 16 befestigt ist. In der Nähe der Laserdiodeneinheit 10, vorzugsweise innerhalb des Gehäuses 14, ist ein Heizelement 18 angeordnet, welches durch die Steuerungseinrichtung 12 betätigt wird. Die Betätigung des Heizelements 18 erfolgt dabei durch die Steuerungseinrichtung 12 im Wechsel oder im Gegentakt mit der Laserdiodeneinheit 10 in der Weise, daß bei ausgeschalteter Laserdiodeneinheit 10 das Heizelement 18 betätigt wird und dies die abgeschaltete Laserdiodeneinheit 10 erwärmt. Beim Einschalten der Laserdiodeneinheit 10, d.h. beim Beschriften der Druckplatte 4 mit einem Bildpunkt, wird das Heizelement 18 ausgeschaltet, so daß von ihm während der Zeit, in der die Laserdiodeneinheit 10 eingeschaltet ist, keine Wärmeenergie erzeugt wird. Bei der bevorzugten Ausführungsform der Erfindung wird das Heizelement 18 durch einen Ohmschen Widerstand gebildet, der im Wechsel mit der Laserdiodeneinheit 10 entsprechend an eine hohe oder an eine niedrige elektrische Spannung angeschlossen wird. In gleicher Weise kann das Heizelement 18 durch ein beliebiges sonstiges Joulsche Wärme erzeugendes elektronisches Bauteil gebildet werden, das im Gegentakt zur Laserdiodeneinheit 10 an eine entsprechende Strom- und/oder Spannungsquelle angeschlossen wird. Ein solches Bauteil kann beispielsweise ein Transistor, eine Diode oder ein sogenanntes Peltier-Element etc. sein.In the preferred embodiment shown in FIG. 1 In the invention, the laser diode units 10 are in one Housing 14 housed, which on a basic or Carrier body 16 is attached. Near the Laser diode unit 10, preferably within the Housing 14, a heating element 18 is arranged, which by the control device 12 is actuated. The actuation of the heating element 18 takes place through the Control device 12 alternately or in push-pull with the Laser diode unit 10 in such a way that when switched off Laser diode unit 10, the heating element 18 is actuated and this heats the switched-off laser diode unit 10. At the Turning on the laser diode unit 10, i.e. when labeling the printing plate 4 with a pixel, that is Heating element 18 turned off, so that during the Time in which the laser diode unit 10 is switched on, no thermal energy is generated. With the preferred Embodiment of the invention, the heating element 18 by an ohmic resistance, which alternates with the Laser diode unit 10 corresponding to a high or a low electrical voltage is connected. In the same Way, the heating element 18 by any other Joule heat-generating electronic component is formed be that in push-pull to the laser diode unit 10 to a appropriate current and / or voltage source connected becomes. Such a component can be, for example, a transistor, a diode or a so-called Peltier element etc.

In gleicher Weise, wie bei der in Fig. 1 gezeigten Anordnung des Heizelements 18 im Gehäuse 14 der Laserdiodeneinheit 10, kann das Heizelement 18 ebenfalls außerhalb des Gehäuses 14 beispielsweise auf diesem oder auf dem Grundkörper 16 angeordnet sein. Bei einer weiteren Ausführungsform der Erfindung kann es ferner vorgesehen sein, den die Beschriftungseinheit 5 tragenden Grundkörper 16 der Vorrichtung 1 konstant zu kühlen oder zu heizen, beispielsweise dadurch, daß der Grundkörper 16 im Inneren hohl ausgebildet ist und der Innenraum von einem entsprechenden Kühl- oder Wärme-Transportmedium gewünschter Temperatur, wie durch die Pfeile 20, 22 angedeutet, durchströmt wird. Anstelle eines von einem Kühl- oder Wärmemedium durchströmten Grundkörpers 16 kann dieser in gleicher Weise auch elektrisch beheizt werden. Hierdurch läßt sich unabhängig von der Regelung der Temperatur durch das Heizelement 18 der Laserdiodeneinheit 10 und/oder dem Heizelement 18 eine unabhängige Vortemperatur aufprägen, so daß beispielsweise der Arbeitspunkt einer aus mehreren, z. B. aus 16 Druckplatten-Beschriftungseinheiten 5 aufgebauten Druckplatten-Beschriftungsvorrichtung 1, beispielsweise in Abhängigkeit von der jeweiligen Umgebungstemperatur für alle Beschriftungseinheiten 5 gemeinsam verändert werden kann.In the same way as in the arrangement shown in FIG. 1 the heating element 18 in the housing 14 of the laser diode unit 10, the heating element 18 can also be outside the housing 14 for example on this or on the base body 16 be arranged. In a further embodiment of the Invention, it can also be provided that the Inscription unit 5 supporting body 16 of the To constantly cool or heat device 1, for example in that the base body 16 inside is hollow and the interior of one appropriate cooling or heat transport medium desired Temperature, as indicated by arrows 20, 22, is flowed through. Instead of one from a cooling or Heat medium flowing through the base body 16 can in be heated electrically in the same way. This leaves independently of the regulation of the temperature by the Heating element 18 of the laser diode unit 10 and / or the Imprint heating element 18 an independent pre-temperature, so that, for example, the working point one of several, for. B. 5 made up of 16 printing plate labeling units Printing plate labeling device 1, for example in Dependence on the respective ambient temperature for everyone Labeling units 5 can be changed together.

Die Regelung der Temperatur der Laserdiodeneinheit 10 durch das Heizelement 18 kann beispielsweise mit einer in Fig. 2 dargestellten elektronischen Schaltungsanordnung 30 vorgenommen werden. Die Schaltungsanordnung 30 besitzt eine Strom- und/oder Spannungsquelle 32, an deren einen Pol, beispielsweise den Plus-Pol, die Steuerungseinrichtung 12 sowie das Heizelement 18 und parallel dazu die Laserdiodeneinheit 10 angeschlossen sind. Das Heizelement 18 sowie die Laserdiodeneinheit 10 sind weiterhin über jeweils zugeordnete Leistungstransistoren 34 und 36 mit dem zweiten Pol der Strom- und/oder Spannungsquelle 32 verbunden. Die Basis des Leistungstransistors 34 des Heizelements 18 ist vorzugsweise über einen festen oder regelbaren Widerstand 35 mit der Steuerungseinrichtung 12 verbunden. Die Basis des Leistungstransistors 36 der Laserdiodeneinheit 10 ist vorzugsweise über einen zweiten festen oder regelbaren Widerstand 37 sowie eine invertierende Schmitt-Triggerschaltung 38 mit der Steuerungseinrichtung 12 verbunden. Die Steuerungseinrichtung 12 steuert die Basen der Leistungstransistoren 34 und 36 im Gegentaktbetrieb, so daß bei ausgeschalteter Laserdiodeneinheit 10 das Heizelement 18 von einem Strom durchflossen wird, dessen Größe über den Widerstand 35 für das jeweilige Heizelement 18 einer Druckplatten-Beschriftungseinheit 5 entsprechend eingestellt werden kann. Hierbei wird aufgrund des invertierenden Schmitt-Triggers 38 das an der Basis des Leistungstransistors 36 der Laserdiodeneinheit 10 anliegende Signal invertiert, so daß der Leistungstransistor 36 sperrt und die Laserdiodeneinheit 10 ausgeschaltet bleibt. Zum Einschalten der Laserdiodeneinheit 10 wird von der Steuerungseinrichtung 12 ein Signal umgekehrter Polarität erzeugt und entsprechend der Leistungstransistor 34 des Heizelements 18 gesperrt sowie der Leistungstransistor 36 aufgrund der invertierenden Wirkung der Schmitt-Triggerschaltung 38 durchgeschaltet, so daß die Laserdiodeneinheit 10 von einem Strom durchflossen wird, dessen Größe über den Widerstand 37 einstellbar ist. Das Erzeugen der Signale durch die Steuerungseinrichtung 12 erfolgt dabei in Abhängigkeit von einem zu setzenden Bildpunkt auf der Druckplatte 4.The regulation of the temperature of the laser diode unit 10 by the heating element 18 can be, for example, with one in FIG. 2 Electronic circuit arrangement 30 shown be made. The circuit arrangement 30 has one Current and / or voltage source 32, at one pole, for example the plus pole, the control device 12 and the heating element 18 and, in parallel, the Laser diode unit 10 are connected. The heating element 18 and the laser diode unit 10 are still above each associated power transistors 34 and 36 with the second Pol of the current and / or voltage source 32 connected. The Base of the power transistor 34 of the heating element 18 is preferably via a fixed or adjustable resistor 35 connected to the control device 12. The basis of the Power transistor 36 of the laser diode unit 10 is preferably via a second fixed or adjustable Resistor 37 and an inverting Schmitt trigger circuit 38 with the control device 12 connected. The control device 12 controls the bases of the Power transistors 34 and 36 in push-pull operation, so that with the laser diode unit 10 switched off, the heating element 18 a current flows through it, the size of which exceeds Resistor 35 for the respective heating element 18 Printing plate labeling unit 5 set accordingly can be. Here, due to the inverting Schmitt trigger 38 at the base of the Power transistor 36 of the laser diode unit 10 is applied Signal inverted so that the power transistor 36 blocks and the laser diode unit 10 remains switched off. To the Switching on the laser diode unit 10 is done by the Control device 12 a signal of reverse polarity generated and corresponding to the power transistor 34 of the Heating element 18 blocked and the power transistor 36 due to the inverting effect of the Schmitt trigger circuit 38 switched through, so that the A current flows through the laser diode unit 10, whose size is adjustable via the resistor 37. The Generating the signals by the control device 12 takes place depending on one to be set Pixel on the printing plate 4.

Der Verlauf der am Heizelement 18 anliegenden Spannung UR sowie der zur gleichen Zeit an der Laserdiodeneinheit 10 anliegende Spannung ULD sind in Fig. 3 in idealisierter Form dargestellt. Wie sich aus Fig. 3 erkennen läßt, wird das Heizelement 18 während der Vorwärmphase V mit der Spannungsquelle 32 oder in äquivalenter Weise mit einer entsprechenden Stromquelle verbunden und gibt dabei eine bestimmte Wärmemenge QR ab, deren Größe über den regelbaren Widerstand 35 vorzugsweise so eingeregelt wird, daß sich die Temperatur der zu dieser Zeit abgeschalteten Laserdiodeneinheit 10 auf eine gewünschte Arbeitstemperatur einstellt. Die an der Laserdiodeneinheit 10 während der Vorwärmphase V bei dieser Ausführungsform der Erfindung anliegende Spannung ULD beträgt vorzugsweise 0 Volt, so daß auch die von der Laserdiodeneinheit 10 erzeugte Wärmemenge pro Zeiteinheit entsprechend 0 J (Joule) beträgt. In der sich anschließenden Beschriftungsphase B wird die Laserdiodeneinheit 10 durch Anlegen der Spannung ULD eingeschaltet und zur gleichen Zeit, d.h. im Wechsel oder im Gegentakt dazu das Heizelement 18 ausgeschaltet. Bei dieser Ausführungsform der Erfindung sind die von der Laserdiodeneinheit 10 abgegebene Wärmemenge pro Zeiteinheit QLD und die vom Heizelement 18 abgegebene Wärmemenge pro Zeiteinheit QR vorzugsweise im wesentlichen gleich, wobei in Abhängigkeit von der Anordnung des Heizelements 18 beziehungsweise der Vortemperierung des Grundkörpers 16 oder der insgesamt abgestrahlten thermischen Leistung, die vom Heizelement 18 abgestrahlte Wärmemenge QR auch kleiner oder größer als die von der Laserdiodeneinheit 10 abgestrahlte Wärmemenge QLD sein kann. Ein Abgleich der Wärmemengen kann beispielsweise über die regelbaren Widerstände 35, 37 der in Fig. 2 dargestellten Schaltungsanordnung erfolgen, wobei der Abgleich vorzugsweise so erfolgt, daß die Temperaturschwankungen zwischen Ein- und Ausschalten der Laserdiodeneinheit möglichst klein sind.The course of the voltage U R applied to the heating element 18 and the voltage U LD applied to the laser diode unit 10 at the same time are shown in FIG. 3 in an idealized form. As can be seen from FIG. 3, the heating element 18 is connected to the voltage source 32 during the preheating phase V or, in an equivalent manner, to a corresponding current source and emits a certain amount of heat Q R , the size of which is preferably regulated in this way via the adjustable resistor 35 becomes that the temperature of the laser diode unit 10 switched off at this time adjusts to a desired working temperature. The voltage U LD applied to the laser diode unit 10 during the preheating phase V in this embodiment of the invention is preferably 0 volts, so that the amount of heat generated by the laser diode unit 10 is also corresponding to 0 J (joules) per unit time. In the subsequent labeling phase B, the laser diode unit 10 is switched on by applying the voltage U LD and the heating element 18 is switched off at the same time, that is to say alternately or in push-pull. In this embodiment of the invention, the amount of heat emitted by the laser diode unit 10 per unit of time Q LD and the amount of heat emitted by the heating element 18 per unit of time Q R are preferably essentially the same, depending on the arrangement of the heating element 18 or the preheating of the base body 16 or total radiated thermal power, the heat quantity Q R radiated by the heating element 18 can also be smaller or larger than the heat quantity Q LD radiated by the laser diode unit 10. The amounts of heat can be adjusted, for example, via the adjustable resistors 35, 37 of the circuit arrangement shown in FIG. 2, the adjustment preferably being carried out in such a way that the temperature fluctuations between switching the laser diode unit on and off are as small as possible.

Bei einer weiteren Ausführungsform der Erfindung wird das Heizelement 18, wie in Fig. 4 gezeigt, auch bei eingeschalteter Laserdiodeneinheit 10 mit einer vorzugsweise einstellbaren Grundspannung UR1, beziehungsweise einem entsprechenden Grundstrom versorgt und gibt dabei eine erste Grundwärmemenge QR1 ab, die im oberen Diagramm von Fig. 4 als gestrichelte Linie dargestellt ist. Bei ausgeschalteter Laserdiodeneinheit 10 ist das Heizelement 18 an eine zweite höhere Spannung UR2 angeschlossen, wodurch es die Wärmemenge QR2 pro Zeiteinheit erzeugt. Die Differenz zwischen den in dieser Ausführungsform der Erfindung vom Heizelement 18 abgegebenen Wärmemengen QR1 und QR2 ist vorzugsweise so gewählt, daß die Temperaturschwankungen beziehungsweise die Temperaturdifferenz der Laserdiodeneinheit 10 zwischen ausgeschaltetem und eingeschaltetem Zustand minimal wird. Bevorzugterweise besitzt die vom Heizelement 18 bei eingeschalteter Laserdiodeneinheit 10 erzeugte Wärmemenge QR1 einen Wert, dessen Größe der Wärmemenge QR2 vermindert um die Differenz aus der von der Laserdiodeneinheit 10 abgegebenen Wärmemenge QLD und der Wärmemenge QR2 entspricht; oder in Formeln ausgedrückt: QR1 = QR2 - (QLD - QR2), wobei vorzugsweise die Wärmemenge QR2 kleiner als die l'ärmemenge QLD ist.In a further embodiment of the invention, the heating element 18, as shown in FIG. 4, is supplied with a preferably adjustable basic voltage U R1 , or a corresponding basic current, even when the laser diode unit 10 is switched on, and emits a first basic heat quantity Q R1 , which is shown in the upper diagram 4 is shown as a dashed line. When the laser diode unit 10 is switched off, the heating element 18 is connected to a second higher voltage U R2 , as a result of which it generates the amount of heat Q R2 per unit of time. The difference between the amounts of heat Q R1 and Q R2 emitted by the heating element 18 in this embodiment of the invention is preferably selected such that the temperature fluctuations or the temperature difference of the laser diode unit 10 between the switched-off and switched-on state is minimal. Preferably, R1 has the amount of heat generated by the heating element 18 is switched on laser diode unit 10 Q a value whose magnitude of the heat quantity Q R2 reduced by the difference between the output from the laser diode unit 10, heat quantity Q LD and the amount of heat Q R2 corresponds; or expressed in formulas: Q R1 = Q R2 - (Q LD - Q R2 ), preferably the amount of heat Q R2 is smaller than the amount of heat Q LD .

Die Wärmemengen QR1, QR2 und QLD sowie die entsprechenden Spannungen UR1, UR2 und ULD, insbesondere die Differenz zwischen QR2 und QR1, können jedoch auch einen anderen Wert besitzen, der in Abhängigkeit von der an die Umgebung abgestrahlten Wärmemenge pro Zeiteinheit, der thermischen Leitfähigkeit der einzelnen Bauelemente, der Anordnung und Ausbildung des Heizelementes 18, der Vortemperierung des Trägerkörpers 16 oder Gehäuses 14 etc. vorzugsweise empirisch durch Einstellen der Spannung und/oder des Stromes über die einstellbaren Widerstände 35, 37 in der Weise bestimmt wird, daß die Temperaturdifferenzen der Laserdiodeneinheit 10 möglichst klein werden.However, the heat quantities Q R1, Q R2 and Q LD as well as the corresponding voltages U R1 , U R2 and U LD , in particular the difference between Q R2 and Q R1 , can also have a different value, depending on the radiation emitted to the environment Amount of heat per unit of time, the thermal conductivity of the individual components, the arrangement and design of the heating element 18, the preheating of the carrier body 16 or housing 14 etc. preferably empirically by adjusting the voltage and / or the current via the adjustable resistors 35, 37 in the manner it is determined that the temperature differences of the laser diode unit 10 become as small as possible.

Das Einschalten der Laserdiodeneinheit 10 und das entsprechende Ausschalten des Heizelements 18 erfolgen vorzugsweise gleichzeitig. Es kann jedoch auch vorgesehen sein, daß sich die Zeitspannen, in denen die Laserdiodeneinheit 10 ein- und das Heizelement 18 ausgeschaltet ist, überschneiden, so daß das Heizelement 18 z. B. schon kurze Zeit vor dem Ausschalten der Laserdiodeneinheit 10 eingeschaltet werden kann. In gleicher Weise kann das Heizelement 18 anschließend eine kurze Zeitspanne über den Zeitpunkt des Einschaltens der Laserdiodeneinheit 10 hinaus eingeschaltet bleiben. Turning on the laser diode unit 10 and that the heating element 18 is switched off accordingly preferably at the same time. However, it can also be provided be that the periods in which the Laser diode unit 10 on and the heating element 18th is switched off, overlap so that the heating element 18th e.g. B. a short time before switching off the Laser diode unit 10 can be turned on. In the same Way, the heating element 18 can then be a short one Time span over the time when the Laser diode unit 10 remain switched on.

Bei einer weiteren, in den Zeichnungen nicht dargestellten Ausführungsform der Erfindung kann es ferner vorgesehen sein, den Grundkörper 16 beziehungsweise die Laserdiodeneinheiten 10 und/oder deren Gehäuse mit einer Schicht aus thermischem Isollationsmaterial zu versehen, so daß Schwankungen der Umgebungstemperatur einen geringeren oder fast gar keinen Einfluß auf die Temperatur der Laserdiodeneinheiten 10 haben. In another, not shown in the drawings Embodiment of the invention may also be provided the base body 16 and the Laser diode units 10 and / or their housing with a To provide a layer of thermal insulation material, so that fluctuations in ambient temperature are less or almost no influence on the temperature of the Have laser diode units 10.

BezugszeichenlisteReference list

11
Druckplatten-BeschriftungsvorrichtungPrinting plate labeling device
22nd
DruckmaschinenzylinderPrinting press cylinder
44th
Druckplatteprinting plate
55
Druckplatten-BeschriftungseinheitPrinting plate labeling unit
66
optische Fokussierungseinrichtungoptical focusing device
88th
optische Lichtleiteroptical light guide
1010th
LaserdiodeneinheitLaser diode unit
1212th
SteuereinrichtungControl device
1414
Gehäusecasing
1616
TragekörperSupport body
1818th
HeizelementHeating element
2020th
Pfeilarrow
2222
Pfeilarrow
3030th
SchaltungsanordnungCircuit arrangement
3232
Strom/SpannungsquelleCurrent / voltage source
3434
Leistungstransistor für HeizelementPower transistor for heating element
3535
regelbarer Widerstand für Heizelementadjustable resistance for heating element
3636
Leistungstransistor für LaserdiodeneinheitPower transistor for laser diode unit
3737
regelbarer Widerstand für Laserdiodeneinheitadjustable resistance for laser diode unit
3838
invertierende Schmitt-Triggerschaltunginverting Schmitt trigger circuit
VV
VorwärmphasePreheating phase
BB
BeschriftungsphaseLabeling phase

Claims (13)

  1. Method for regulating the temperature in a laser-operated printing-plate imaging unit of a printing press, particularly an offset printing press, the laser light being generated by a laser diode unit which is switched on and off in accordance with an image pattern to be produced on the printing plate,
    characterised in that a heat source arranged near the laser diode unit is operated alternatively with the laser diode unit, so that the temperature of the laser diode unit is maintained as constant as possible.
  2. Method according to Claim 1,
    characterised in that the heat quantity per unit time emitted by the heat source is increased when the laser diode unit is in a switched-off state and is decreased when the laser diode unit is in a switched-on state.
  3. Method according to Claim 1 or 2
    characterised in that the heat quantity per unit time emitted by the heat source is essentially equal to the heat quantity per unit time emitted by the laser diode unit.
  4. Method according to Claim 1 or 2,
    characterised in that the heat source, in the switched-on state of the laser diode unit, emits a given basic heat quantity per unit time which is smaller than the heat quantity per unit time emitted by the laser diode unit; and that the heat source, in the switched-of state of the laser diode unit, emits a second larger heat quantity, the first and the second heat quantities being chosen such, that a temperature difference between the switched-on state and the switched-off state of the laser diode unit is minimal.
  5. Method according to Claim 4,
    characterised in that the difference between the first and the second heat quantities is essentially equal to the difference between the heat quantity emitted by the switched-on laser diode unit and the second heat quantity.
  6. Method according to anyone of the preceding claims,
    characterised in that the laser diode unit and/or the heat source are heated or cooled to a predetermined initial temperature.
  7. Method according to anyone of the preceding claims,
    characterised in that the laser diode unit and/or the heat source are thermally insulated against the environment.
  8. Device for regulating the temperature in a laser-operated printing-plate imaging unit of a printing press, particularly an offset printing press, wherein the laser light is generated by at least one laser diode unit which is switched on and off in accordance with an image pattern to be produced on the printing plate ,
    characterised in that near the laser diode unit (10) there is arranged an electric heating element (18) which, in alternation with the laser diode unit 10, generates a first heat quantity (QR1) when the laser diode unit (10) is in a switched-on state and generates a second larger heat quantity (QR2) when the laser diode unit (10) is in a switched-off state.
  9. Device according to Claim 8,
    characterised in that the second heat quantity (QR2) is essentially equal to the heat quantity (QLD) generated by the laser diode unit (10); and that the first smaller heat quantity (QR1) has a value of zero.
  10. Device according to Claim 8,
    characterised in that the second heat quantity (QR2) generated by the heating element (18) in the switched-off state of the laser diode unit (10) has a value such, that the temperature of the laser diode unit (10) is equal to a predetermined reference value.
  11. Device according to Claim 10,
    characterised in that the first heat quantity (QR1) generated by the heating element (18) in the switched-on state of the laser diode unit (10) has a value which is equal to the second heat quantity (QR2) reduced by the difference between the heat quantity (QLD) generated by the laser diode unit (10) and the second heat quantity (QR2).
  12. Device according to anyone of the Claims 8 to 11,
    characterised in that the heating element (18) is formed of an electrical component for generating joulean heat, said electrical heating element being connected to one of electrical voltage and/or current (32) sources in accordance with the heat quantity to be generated.
  13. Device according to anyone of the Claims 8 to 12,
    characterised in that there is provided an electronic phase opposition circuit (30) having a first power transistor (34) controlled by a control unit (12) for regulating current flow through the heating element (18), as well as a second power transistor (36) controlled by the control unit (12) via an inverting Schmitt trigger switch for regulating current flow through the laser diode unit (10).
EP97105896A 1996-05-02 1997-04-10 Process for the regulation of the temperature within a device for the inscription of printing plates using a laser radiation particularly for an offset printing machine Expired - Lifetime EP0805021B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19617552 1996-05-02
DE19617552A DE19617552A1 (en) 1996-05-02 1996-05-02 Method and device for regulating the temperature in a printing plate labeling unit working with laser light, in particular an offset printing machine

Publications (3)

Publication Number Publication Date
EP0805021A2 EP0805021A2 (en) 1997-11-05
EP0805021A3 EP0805021A3 (en) 1998-01-07
EP0805021B1 true EP0805021B1 (en) 2000-12-27

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US (1) US6043456A (en)
EP (1) EP0805021B1 (en)
JP (1) JPH1071690A (en)
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DE (2) DE19617552A1 (en)

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US6043456A (en) 2000-03-28
EP0805021A3 (en) 1998-01-07
DE19617552A1 (en) 1997-11-06
JPH1071690A (en) 1998-03-17
DE59702800D1 (en) 2001-02-01
EP0805021A2 (en) 1997-11-05
CA2201226A1 (en) 1997-11-02
CA2201226C (en) 2000-02-01

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