EP0121772A1 - Roll fusing unit - Google Patents

Roll fusing unit Download PDF

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Publication number
EP0121772A1
EP0121772A1 EP84102432A EP84102432A EP0121772A1 EP 0121772 A1 EP0121772 A1 EP 0121772A1 EP 84102432 A EP84102432 A EP 84102432A EP 84102432 A EP84102432 A EP 84102432A EP 0121772 A1 EP0121772 A1 EP 0121772A1
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EP
European Patent Office
Prior art keywords
roller
heating
temperature
heating roller
fixing device
Prior art date
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Granted
Application number
EP84102432A
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German (de)
French (fr)
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EP0121772B1 (en
Inventor
Reinhold Euler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hoechst AG
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Hoechst AG
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Publication date
Application filed by Hoechst AG filed Critical Hoechst AG
Priority to AT84102432T priority Critical patent/ATE23229T1/en
Publication of EP0121772A1 publication Critical patent/EP0121772A1/en
Application granted granted Critical
Publication of EP0121772B1 publication Critical patent/EP0121772B1/en
Expired legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
    • G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
    • G03G15/2014—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat
    • G03G15/2039—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat with means for controlling the fixing temperature
    • G03G15/2042—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat with means for controlling the fixing temperature specially for the axial heat partition

Definitions

  • the invention relates to a roller fixing device with a pressure roller and an internally heated heating roller as a fixing roller for fixing a toner image on copy material, with at least one electric heating element arranged inside the heating roller parallel to the roller axis, the surface of the heating roller having an uneven temperature distribution in the axial direction at least one temperature sensor opposite the surface of the heating roller, which is connected to a control for the power supply to the heating element.
  • Such a heating roller fixing device is known from DE-PS 29 49 996, in which the heating element has a non-uniform radiation density in the axial direction in the switched-on state, such that a temperature distribution results in the axial direction on the surface of the fixing roller, which is in the middle and at has a minimum in the two axial ends and a maximum in between.
  • the only temperature sensor of this heating roller fixing device is arranged close to its surface at the level of the maxima of the surface temperature of the fixing roller.
  • An infrared radiator is provided as the heating element, which has a higher radiation density in the axial direction at its two ends than in the middle.
  • this heating roller fixing device With this heating roller fixing device, a poss Lich uniform temperature distribution can be achieved on the surface of the fuser roller to improve the fixing of a toner image on copy paper and to achieve good adhesion of the toner to the paper.
  • too low a fixing temperature results in inadequate fixing, so that the toner image can be easily wiped off the copy paper.
  • an excessively high fixing temperature leads to the so-called offset effect, in which a part of the toner image is removed from the copy paper and adheres to the fixing roller and is then transferred to other areas of the copy paper.
  • a roller arrangement of a heating and a pressure roller for thermal fixing is known, between which a copy paper with a toner image on it is transported forward.
  • the heating roller there is a heating element with which the surface temperature of the heating roller is kept at a predetermined temperature.
  • the heating roller and the printing roller are rotated before the surface temperature of the heating roller reaches the predetermined temperature.
  • the motor that rotates the heating and printing rollers is switched off.
  • the heating element in the heating roller is controlled via a temperature sensor which is arranged at one point in such a way that it determines the surface temperature of the heating roller.
  • a toner image fixing device comprising a heating and printing roller
  • a temperature sensor measures the surface temperature of the heating roller and the size of the pressure force of the printing roller on the heating roller is regulated as a function of the measured surface temperature.
  • the roller fixing station according to European patent application 0017092 is equipped with a pair of rotatable rollers, one of which has end portions that taper outwards.
  • the roller includes an outer sleeve which is centrally secured on an axis.
  • the main parts of the inner surface of the sleeve have stepped sections with increasing diameter at each tapered end of the sleeve.
  • Screw-in plugs are fastened to parts of the axle in the tapered end sections of the sleeve.
  • the main body of each plug has a smaller diameter than the surface part of the inner sleeve.
  • the plugs are rotatable on the axis and move linearly from a retracted position, in which there is play between the plugs and the sleeve of the roller, in an engagement position, in which end flanges of the plugs are engaged with the stepped parts of the sleeve. Is done in the retracted position no mechanical support of the end sections of the sleeve by the flanges of the plugs, so that the pressure of the counter roller presses the tapered end sections of the sleeve against the plugs.
  • the degree of taper and the size of the gap between the stopper and the sleeve are coordinated with one another in such a way that the behavior of the roller corresponds to an essentially flat, ie non-tapering roller.
  • the tapered formation of the roll is maintained when the end plugs are screwed inward in the axial direction, and this prevents wrinkling of the copy paper, which usually occurs in the fusing station at high humidity.
  • the roller works like an essentially flat cylindrical roller which has no taper.
  • the tapered configuration of the roller is flattened.
  • the plugs can be adjusted manually when the two rollers are separated from one another or by means of a motor controlled by a moisture sensor.
  • the jogging achieves a higher peripheral speed near the edge of the roll so that a copy paper that passes through the nip between two rolls experiences a higher peripheral speed along the edges compared to the speed in the middle. As a result, the copy paper stretches and does not wrinkle in the fixing station even at high relative humidity.
  • the copy paper tends to curl or form small waves, so that when the copy paper enters the fixing device, it comes into premature contact with the fixing roller, causing the image to be smeared.
  • a temperature distribution that is as uniform as possible over the length of the fixing roller while compensating for the temperature drop near the roller ends is sought in order to maintain constant copy quality, or the contact pressure between the fixing roller and the pressure roller is regulated in accordance with the respective measured temperature so that a predetermined pressure / Temperature relationship is maintained, or a roller tapering outward in the end sections is used, which flattens under the pressure of another roller, so as to obtain a uniform pressure over the length of the roller to avoid wrinkling.
  • the object of the invention is to improve a fixing device of the type described in the introduction such that wrinkles or corrugations or pinch folds both in the case of the usual copies such as DIN-A4 and DIN-A3 and in the case of large-format copies such as DIN-A2 or DIN-A1 with impairment of the copy image and that different copy materials such as opaque or transparent papers or foils can be used.
  • This object is achieved in that in the interior of the heating roller another electric heating element which is connected to the control via a further temperature sensor runs parallel to the roller axis in that one heating element consists of a coil in the central zone of the heating roller and the other heating element There are two coils in the edge zones of the heating roller adjoining the central zone on the left and right that the coil in the central zone overlaps with each of the two coils in each edge zone so that the current supply to the heating elements is controlled in such a way that the surface of the heating roller is controlled results in a temperature distribution in the axial direction, which has an extremum in the central zone and maxima close to the two end faces, and that one temperature sensor is located at the extremum of the surface temperature in the middle of the roll and the other temperature sensor is located at the middle of one of the peripheral zones of the heating roll is.
  • the advantages are achieved that large-format copies can be made wrinkle and wave-free, regardless of the nature of the copy material and that the shape of the fusing roller at the time of contact with the pressure roller through the adjustable temperature curve over the fusing roller length with little effort in comparison to the conical design of the known fixing roller with screwable plugs, which are adjustable in the axial direction of the roller, is achieved.
  • a fixing device 1 shown in Fig. 1 comprises a heating roller 10 and a pressure roller 2.
  • the upper heating roller 10 or fixing roller is in bearings 5 and 6, for example ball bearings, and the lower pressure roller 2 is mounted in bearings 23, 24, each inside the rollers are arranged.
  • the storage within the rollers takes place approximately at a distance of 20 mm from the respective end faces of the rollers.
  • the upper heat roller 10 has a length of about 670 mm and is usually made of an aluminum tube with a wall thickness of 7 to 9 mm, and a silicone rubber coating 25 having a thickness of about 1 - 1.2 mm to.
  • the coating with silicone rubber ends about 30 to 32 mm in front of the end faces 17, 18 of the heating roller 10.
  • the pressure roller 2 also consists of an aluminum cylinder with a wall thickness of about 6 mm and a coating of silicone rubber and a tube made of a shrink film, the thicknesses the silicone rubber coating and the hose is approximately 3 mm. This coating extends from face to face.
  • the pressure roller 2 interacts with the heating roller 10 in order to grasp the copying material and to transport it through the gap between the two rollers.
  • the shaft section projecting from the end face 17 of the roller 10 carries a clutch 3 with a toothed wheel 26 which is driven by a toothed belt 4 or a roller chain.
  • a temperature sensor 19 for example a thermistor or a thermocouple, is arranged near the surface of the heating roller 10 opposite the center of the roller, the two connecting wires of which are connected to a controller 21, which is schematically indicated in FIG. 1 and which controls the copying program sequence.
  • a further temperature sensor 20 Near the surface and the one end face 17 of the heating roller 10 there is a further temperature sensor 20, namely a thermistor or a thermocouple, which is connected to the controller 21 with its two connecting wires.
  • the two temperature sensors ensure that the energy supply to heating elements which are arranged inside the heating roller is interrupted when predetermined temperatures are reached at the measuring points.
  • Connection wires 7, 8 or 7 ', 8' lead from the interior of the heating roller 10 to the controller 21, which has a control circuit for actuating relays which remove the connection to the mains supply of the heating elements when predetermined setpoint values of the temperature are reached.
  • the two electrical heating elements 11 and 13 run parallel to a roller axis 12.
  • the heating element 11 is enclosed by a glass cylinder 9 in which a coil 14 extends, which extends over a central zone b of the heating roller 10.
  • the length of this central zone b is approximately 310 mm.
  • From the two ends of the helix 14 lead wires 7,7 'from Glass cylinder 9 out.
  • the other heating element 13 has two coils 15 and 16, which are located in the edge zones a, c of the heating roller 10 adjoining the central zone b on the left and right.
  • the two coils 15 and 16 are connected to one another in the middle by a heating wire and melted into a glass cylinder 22, through the end walls of which the two connecting wires 8, 8 ′ of the heating element 13 are passed.
  • the individual helix 15, 16 has a length of approximately 150 mm.
  • the length of the helix 14 in the central zone b corresponds at least to the width of the A3 format and is generally 300 to 305 mm.
  • the helix 14 in the central zone b overlaps in an area g with each of the two helices 15, 16 in each of the peripheral zones a, c.
  • the current supply to the heating elements 11, 13 is controlled in such a way that a temperature distribution shown in FIG. 3 results in the axial direction on the surface of the heating roller 10, which has a minimum in the central zone b and 10 maxima near the two end faces 17, 18 of the heating roller has e and f.
  • the temperature sensor 19 is located at the level of the minimum d of the surface temperature in the middle of the roller and the other temperature sensor 20 is at the level of the maximum of the surface temperature of the heating roller 10 near one of the end faces 17 and 18, respectively. Due to the overlap of the coils 14, 15, 16 a uniform temperature profile is achieved at the transition points from the central zone to the peripheral zones.
  • the heating elements 11, 13 are controlled by the temperature sensors 19, 20 in such a way that a temperature difference ⁇ of 2 ° to 10 ° C. occurs between the center of the heating roller 10 and the edge zones a and c of the heating roller. This temperature difference arises as soon as the two heating elements 11 and 13 are heated.
  • the size of the temperature difference .DELTA..phi. is determined as a function of the copying material, a smaller temperature difference being generally chosen for opaque paper than for transparent paper.
  • the heating of the two heating elements is carried out in such a way that in the case of formats of the copying material of A4 and A3, only the heating element 11 with the coil 14 in the central zone b of the heating roller 10 is switched on.
  • the heating element 13 with the two coils 15 and 16 is automatically switched on by the controller 21. This is to avoid that the temperature difference is greater than 10 ° C, since otherwise the waiting times become too large if formats A4 switched after prolonged operation of the fixing station for fixing A3 and DI N to larger formats such as DIN A2 and DIN Al becomes.
  • both heating elements 11 and 13 are switched on at the same time.
  • Narrow web papers are to be understood as papers that are cut to formats along the direction of the paper tape. As a result of the production of these papers, they shrink only in the transverse direction when moisture is removed, but hardly in the longitudinal direction.
  • the narrow web papers whether opaque or transparent papers, show great dimensional stability in the longitudinal direction, the maxima le shrinkage when the relative humidity is reduced by 57% and the temperature drops from 30 ° C to 20 ° C is 2.8 mm with an average length of 500 mm, while in the transverse direction the maximum shrinkage is up to 15 mm with an average width of Can be 500 mm.
  • the table shows that tracing paper shrinks more than opaque paper or expands when the relative humidity increases, while plastic film as copying material, such as Hostaphan ( R ), is largely dimensionally stable in both the transverse and longitudinal directions.
  • the heating roller Due to the zone control of the temperature of the heating roller, it has a slightly larger diameter in the edge zones, so that the roller pressures in the edge zones and in the middle are aligned with one another and the throughput speed of the copy paper is approximately the same across the entire roller width.
  • the temperature difference ⁇ between the individual edge zone and the center of the roller arrangement should not exceed 10 ° C, since otherwise the roller pressure in the edge zones will be greater than in the middle, so that the throughput speed of the copy paper at the edges will be higher than in the middle.
  • the copy image is then duplicated, the cause of which is the accumulation of the slower paper zones in the middle of the bow wave mentioned above.
  • the temperature in the minimum d is 180 ° C., in the maxima e and f 193 ° C. and in the peripheral zones of the heating roller over the entire peripheral zone region 186 ° C. .
  • the constant temperature which arises in the peripheral zones is the highest temperature within the temperature zones of the heating roller which are effective for fixing, while the temperature maxima e and f lie outside the silicone coating and thus the roller region which is effective for fixing.
  • Fig. 4 shows a temperature curve over the heating roller length, which is set after long operation of the fuser by appropriate control of the power supply to the heating elements 11 and 13. It can be seen that the central zone b of the heating roller is subjected to greater stress than the edge zones a, c during longer operation, with the result that the diameter in the center of the heating roller is about 0.1 mm per 10,000 copies in comparison to the Diameters of the edge zones a and c decreases. A conceivable explanation for this could be a stronger mechanical abrasion and / or a greater discharge of silicone oil from the silicone rubber coating in the middle of the heating roller. This process requires an adjustment of the temperature profile in such a way that the temperature of the central zone is raised in relation to that of the peripheral zones in order to continue to ensure a uniform mutual pressure of the rollers over their entire length.
  • the characteristic temperature in the maximum d 'in the central zone is, for example, 182 ° C, in the maxima e' and f 'approximately 181 ° C and in the peripheral zones on average 175 ° C for the temperature profile according to FIG. 4.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fixing For Electrophotography (AREA)
  • Massaging Devices (AREA)
  • Control And Other Processes For Unpacking Of Materials (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)
  • General Induction Heating (AREA)

Abstract

A fixing roller device having a pressure roller and a heating roller as the fixing roller. Heating elements sealed into glass cylinders are located inside the heating roller, parallel to a roller axis. One heating element consists of a coil in a middle zone of the heating roller, while the other heating element has two coils in edge zones of the heating roll. Two temperature sensors are arranged respectively in the middle of the heating roller and near one of the end faces of the heating roller, at a small distance from the heating roller surface, and are connected to a control system which controls the current supply to the heating elements and cuts this supply as soon as the temperatures measured by the temperature sensors reach predetermined intended values.

Description

Die Erfindung betrifft eine Walzenfixiervorrichtung mit einer Andruckwalze und einer von innen beheizten Heizwalze als Fixierwalze zum Fixieren eines Tonerbildes auf Kopiermaterial, mit zumindest einem im Inneren der Heizwalze parallel zur Walzenachse angeordneten elektrischen Heizelement, wobei die Oberfläche der Heizwalze in Achsenrichtung eine ungleichmäßige Temperaturverteilung aufweist, mit zumindest einem der Oberfläche der Heizwalze gegenüberliegenden Temperaturfühler, der an eine Steuerung für die Stromzufuhr zum Heizelement angeschlossen ist.The invention relates to a roller fixing device with a pressure roller and an internally heated heating roller as a fixing roller for fixing a toner image on copy material, with at least one electric heating element arranged inside the heating roller parallel to the roller axis, the surface of the heating roller having an uneven temperature distribution in the axial direction at least one temperature sensor opposite the surface of the heating roller, which is connected to a control for the power supply to the heating element.

Eine derartige Heizwalzenfixiervorrichtung ist aus der DE-PS 29 49 996 bekannt, bei der das Heizelement im eingeschalteten Zustand in axialer Richtung eine ungleichmäßige Strahlungsdichte aufweist, derart, daß sich auf der Oberfläche der Fixierwalze in Axialrichtung eine Temperaturverteilung ergibt, die in der Mitte und an den beiden axialen Enden ein Minimum und dazwischen jeweils ein Maximum aufweist. Der einzige Temperaturfühler dieser Heizwalzenfixiervorrichtung ist auf der Höhe der Maxima der Oberflächentemperatur der Fixierwalze dicht an ihrer Oberfläche angeordnet. Als Heizelement ist ein Infrarotstrahler vorgesehen, der in axialer Richtung an seinen beiden Enden eine höhere Strahlungsdichte aufweist als in der Mitte.Such a heating roller fixing device is known from DE-PS 29 49 996, in which the heating element has a non-uniform radiation density in the axial direction in the switched-on state, such that a temperature distribution results in the axial direction on the surface of the fixing roller, which is in the middle and at has a minimum in the two axial ends and a maximum in between. The only temperature sensor of this heating roller fixing device is arranged close to its surface at the level of the maxima of the surface temperature of the fixing roller. An infrared radiator is provided as the heating element, which has a higher radiation density in the axial direction at its two ends than in the middle.

Mit dieser Heizwalzenfixiervorrichtung soll eine möglichst gleichmäßige Temperaturverteilung auf der Oberfläche der Fixierwalze erreicht werden, um das Fixieren eines Tonerbildes auf Kopierpapier zu verbessern und eine gute Haftung des Toners auf dem Papier zu erzielen. Ganz allgemein hat eine zu niedrige Fixiertemperatur ein ungenügendes Fixieren zur Folge, so daß sich das Tonerbild leicht vom Kopierpapier abwischen läßt. Andererseits führt eine zu hohe Fixiertemperatur zu dem sogenannten Offset-Effekt, bei dem ein Teil des Tonerbildes vom Kopierpapier abgenommen wird und auf der Fixierwalze haftet und dann auf andere Bereiche des Kopierpapiers übertragen wird.With this heating roller fixing device, a poss Lich uniform temperature distribution can be achieved on the surface of the fuser roller to improve the fixing of a toner image on copy paper and to achieve good adhesion of the toner to the paper. In general, too low a fixing temperature results in inadequate fixing, so that the toner image can be easily wiped off the copy paper. On the other hand, an excessively high fixing temperature leads to the so-called offset effect, in which a part of the toner image is removed from the copy paper and adheres to the fixing roller and is then transferred to other areas of the copy paper.

Bei der bekannten Heizwalzenfixiervorrichtung wird erreicht, daß in axialer Richtung der Fixierwalze in der Mitte gerade kein Maximum der Temperaturverteilung vorliegt, vielmehr sind derartige Maxima zwischen den beiden Enden und der Mitte der Fixierwalze vorhanden. Zwar wird auch bei einer derartigen Anordnung ein an und für sich nicht erwünschtes Überschwingen der Temperaturwerte über den Sollwert an den Stellen stattfinden, an denen sich die Maxima der Temperaturverteilung befinden, jedoch wird dieser Effekt dadurch kompensiert, daß in axialer Richtung der Fixierwalze in der Mitte und an den beiden Enden Bereiche geringerer Temperaturen vorliegen, so daß sich zwangsläufig ein Temperaturausgleich an der Oberfläche der Fixierwalze über ihre Länge ergibt. Zu dem Überschwingen der Temperaturwerte kommt es dadurch, daß der Temperaturfühler bei Erreichen des Sollwertes einer gewünschten Temperatur die Stromzufuhr zum Heizelement abschaltet, die Fixierwalze jedoch zu diesem Zeitpunkt eine erhebliche Wärmemenge gespeichert hat und infolge der Trägheit des Systems diese zu Temperaturen über dem Sollwert führt.In the known heating roller fixing device it is achieved that in the axial direction of the fixing roller there is just no maximum of the temperature distribution in the middle, rather such maxima are present between the two ends and the center of the fixing roller. Even with such an arrangement, an undesirable overshoot of the temperature values above the setpoint will take place at the points where the maxima of the temperature distribution are located, but this effect is compensated for by the fact that in the axial direction of the fixing roller in the middle and regions of lower temperatures are present at the two ends, so that there is inevitably temperature compensation on the surface of the fixing roller over its length. The temperature values overshoot if the temperature sensor reaches a desired value when the setpoint is reached Temperature switches off the power supply to the heating element, but at this point the fuser roller has stored a considerable amount of heat and, due to the inertia of the system, this leads to temperatures above the setpoint.

Aus der DE-OS 32 24 239 ist eine Walzenanordnung aus einer Heiz- und einer Druckwalze zum thermischen Fixieren bekannt, zwischen denen ein Kopierpapier mit einem darauf befindlichen Tonerbild vorwärtstransportiert wird. In der Heizwalze befindet sich ein Heizelement, mit dem die Oberflächentemperatur der Heizwalze auf einer vorgegebenen Temperatur gehalten wird. Beim Einschalten des Kopiergeräts werden die Heizwalze und die Druckwalze in Drehung versetzt, bevor die Oberflächentemperatur der Heizwalze die vorgegebene Temperatur erreicht. Sobald diese Temperatur erreicht ist, wird der Motor, der die Heiz- und die Druckwalze in Drehung versetzt, ausgeschaltet. Die Steuerung des Heizelements in der Heizwalze erfolgt über einen Temperaturfühler, der an einer Stelle so angeordnet ist, daß er die Oberflächentemperatur der Heizwalze ermittelt.From DE-OS 32 24 239 a roller arrangement of a heating and a pressure roller for thermal fixing is known, between which a copy paper with a toner image on it is transported forward. In the heating roller there is a heating element with which the surface temperature of the heating roller is kept at a predetermined temperature. When the copier is switched on, the heating roller and the printing roller are rotated before the surface temperature of the heating roller reaches the predetermined temperature. As soon as this temperature is reached, the motor that rotates the heating and printing rollers is switched off. The heating element in the heating roller is controlled via a temperature sensor which is arranged at one point in such a way that it determines the surface temperature of the heating roller.

Aus der US-PS 4 232 959 ist eine Tonerbild-Fixiervorrichtung aus Heiz- und Druckwalze bekannt, bei der ein Temperaturfühler die Oberflächentemperatur der Heizwalze mißt und in Abhängigkeit von der gemessenen Oberflächentemperatur die Größe der Andruckkraft der Druckwalze an die Heizwalze geregelt wird. Dadurch soll eine gleichmäßige Fixierqualität des Tonerbilds auf einem Kopierblatt, das zwischen den beiden Walzen hindurchtransportiert wird, erreicht werden, da der Fixiervorgang sowohl über die Tempertur als auch über den Anpreßdruck zwischen den beiden Walzen in der Weise beeinflußt wird, daß beispielsweise bei steigender Oberflächentemperatur der Anpreßdruck verringert und bei sinkender Oberflächentemperatur der Anpreßdruck erhöht wird. Der Zusammenhang zwischen diesen beiden Größen wird dabei aufgrund einer vorgegebenen Oberflächentemperatur/Anpreßdruck-Beziehung geregelt.From US Pat. No. 4,232,959 a toner image fixing device comprising a heating and printing roller is known, in which a temperature sensor measures the surface temperature of the heating roller and the size of the pressure force of the printing roller on the heating roller is regulated as a function of the measured surface temperature. Thereby Uniform fixing quality of the toner image on a copy sheet which is transported between the two rollers is to be achieved, since the fixing process is influenced both by the temperature and by the contact pressure between the two rollers in such a way that, for example, the contact pressure increases with increasing surface temperature is reduced and the contact pressure is increased as the surface temperature falls. The relationship between these two quantities is regulated on the basis of a predetermined surface temperature / contact pressure relationship.

Die Rollen-Fixierstation nach der europäischen Patentanmeldung 0017092 ist mit einem Paar drehbarer Rollen ausgerüstet, von denen eine nach außen sich verjüngende Endabschnitte aufweist. Die Rolle umfaßt eine äußere Hülse, die zentral auf einer Achse befestigt ist. Die Hauptteile der Innenfläche der Hülse besitzen abgestufte Abschnitte mit ansteigendem Durchmesser an jedem sich verjüngenden Ende der Hülse. In den verjüngenden Endabschnitten der Hülse sind verschraubbare Stopfen auf Teilen der Achse befestigt. Der Hauptkörper jedes Stopfens besitzt einen kleineren Durchmesser als der Flächenteil der inneren Hülse. Die Stopfen sind auf der Achse drehbar und bewegen sich linear von einer zurückgezogenen Position, in der ein Spiel zwischen den Stopfen und der Hülse der Rolle besteht, in einer Eingriffsposition, in der Endflansche der Stopfen mit den abgestuften Teilen der Hülse im Eingriff sind. In der zurückgezogenen Position erfolgt keine mechanische Abstützung der Endabschnitte der Hülse durch die Flansche der Stopfen, so daß der Druck der Gegenrolle die sich verjüngenden Endabschnitte der Hülse gegen die Stopfen anpreßt. Der Grad der Verjüngung und die Größe des Spalts zwischen den Stopfen und der Hülse sind so aufeinander abgestimmt, daß das Verhalten der Rolle einer im wesentlichen ebenen, d.h. sich nicht verjüngenden Rolle entspricht.The roller fixing station according to European patent application 0017092 is equipped with a pair of rotatable rollers, one of which has end portions that taper outwards. The roller includes an outer sleeve which is centrally secured on an axis. The main parts of the inner surface of the sleeve have stepped sections with increasing diameter at each tapered end of the sleeve. Screw-in plugs are fastened to parts of the axle in the tapered end sections of the sleeve. The main body of each plug has a smaller diameter than the surface part of the inner sleeve. The plugs are rotatable on the axis and move linearly from a retracted position, in which there is play between the plugs and the sleeve of the roller, in an engagement position, in which end flanges of the plugs are engaged with the stepped parts of the sleeve. Is done in the retracted position no mechanical support of the end sections of the sleeve by the flanges of the plugs, so that the pressure of the counter roller presses the tapered end sections of the sleeve against the plugs. The degree of taper and the size of the gap between the stopper and the sleeve are coordinated with one another in such a way that the behavior of the roller corresponds to an essentially flat, ie non-tapering roller.

Die sich verjüngende Ausbildung der Rolle wird beibehalten, wenn die Endstopfen in axialer Richtung nach innen geschraubt werden und dadurch wird eine Faltenbildung des Kopierpapiers, die üblicherweise bei hoher Feuchtigkeit in der Fixierstation auftritt, verhindert.The tapered formation of the roll is maintained when the end plugs are screwed inward in the axial direction, and this prevents wrinkling of the copy paper, which usually occurs in the fusing station at high humidity.

Werden die Endstopfen in axialer Richtung nach außen geschraubt, so arbeitet die Rolle wie eine im wesentlichen ebene zylindrische Rolle, die keine Verjüngung besitzt. Infolge des Anpreßdruckes der Gegenrolle wird die sich verjüngende Konfiguration der Rolle abgeflacht. Der Einsatz dieser Rolle unter dieser Bedingung verhindert den sogenannten Verschmierungseffekt auf der Kopie bei trockenen Bedingungen, d.h. sehr geringer Luftfeuchtigkeit in der-Fixierstation. Die Einstellung der Stopfen kann manuell vorgenommen werden, wenn die beiden Rollen voneinander getrennt sind oder mittels eines Motors, der über einen Feuchtigkeitsfühler gesteuert wird.If the end plugs are screwed outward in the axial direction, the roller works like an essentially flat cylindrical roller which has no taper. As a result of the contact pressure of the counter roller, the tapered configuration of the roller is flattened. Using this roll under this condition prevents the so-called smear effect on the copy in dry conditions, i.e. very low humidity in the fuser. The plugs can be adjusted manually when the two rollers are separated from one another or by means of a motor controlled by a moisture sensor.

Durch die Verjiingung wird eine höhere Umfangsgeschwindigkeit nahe der Kante der Rolle erzielt, so daß ein Kopierpapier, das den Spalt zwischen zwei Rollen durchläuft, eine höhere periphere Geschwindigkeit längs den Kanten im Vergleich zu der Geschwindigkeit in der Mitte erfährt. Daraus resultiert, daß das Kopierpapier sich streckt und keine Falten selbst bei hoher relativer Feuchtigkeit in der Fixierstation bildet.The jogging achieves a higher peripheral speed near the edge of the roll so that a copy paper that passes through the nip between two rolls experiences a higher peripheral speed along the edges compared to the speed in the middle. As a result, the copy paper stretches and does not wrinkle in the fixing station even at high relative humidity.

Bei sehr trockenen Bedingungen neigt das Kopierpapier dazu, sich zu kräuseln oder kleine Wellen zu bilden, so daß es, sobald das Kopierpapier in die Fixiervorrichtung eintritt, zu einem vorzeitigen Kontakt mit der Fixierrolle kommt, wodurch eine Verschmierung des Bildes verursacht wird.In very dry conditions, the copy paper tends to curl or form small waves, so that when the copy paper enters the fixing device, it comes into premature contact with the fixing roller, causing the image to be smeared.

Bei den bekannten Fixiervorrichtungen wird eine möglichst gleichmäßige Temperaturverteilung über die Länge der Fixierwalze unter Kompensation des Temperaturabfalls nahe der Walzenenden angestrebt, um gleichbleibende Kopienqualität zu erhalten, oder der Anpreßdruck zwischen Fixier- und Druckwalze entsprechend der jeweiligen gemessenen Temperatur so geregelt, daß eine vorgegebene Druck/Temperatur-Beziehung eingehalten wird, oder eine sich in den Endabschnitten nach außen verjüngende Rolle eingesetzt, die sich unter dem Anpreßdruck einer weiteren Rolle abflacht, um so einen gleichmäßigen Andruck über die Rollenlänge zur Vermeidung von Faltenbildung zu erhalten.In the known fixing devices, a temperature distribution that is as uniform as possible over the length of the fixing roller while compensating for the temperature drop near the roller ends is sought in order to maintain constant copy quality, or the contact pressure between the fixing roller and the pressure roller is regulated in accordance with the respective measured temperature so that a predetermined pressure / Temperature relationship is maintained, or a roller tapering outward in the end sections is used, which flattens under the pressure of another roller, so as to obtain a uniform pressure over the length of the roller to avoid wrinkling.

Aufgabe der Erfindung ist es, eine Fixiervorrichtung der eingangs beschriebenen Art so zu verbessern, daß sowohl bei den üblichen Kopien wie DIN-A4 und DIN-A3 als auch bei großformatigen Kopien wie DIN-A2 oder DIN-A1 eine Falten- oder Wellenbildung oder Quetschfalten mit Beeinträchtigung des Kopienbildes ausgeschlossen werden und daß unterschiedliche Kopiermaterialien wie opake oder transparente Papiere oder Folien verwendet werden können.The object of the invention is to improve a fixing device of the type described in the introduction such that wrinkles or corrugations or pinch folds both in the case of the usual copies such as DIN-A4 and DIN-A3 and in the case of large-format copies such as DIN-A2 or DIN-A1 with impairment of the copy image and that different copy materials such as opaque or transparent papers or foils can be used.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß im Inneren der Heizwalze ein weiteres elektrisches Heizelement das mit der Steuerung über einen weiteren Temperaturfühler verbunden ist, parallel zu der Walzenachse verläuft, daß das eine Heizelement aus einem Wendel in der Mittelzone der Heizwalze und das andere Heizelement aus zwei Wendeln in den an die Mittelzone links und rechts anschließenden Randzonen der Heizwalze besteht, daß sich der Wendel in der Mittelzone mit jedem der beiden Wendeln in jeder Randzone überlappt, daß die Stromzufuhr zu den Heizelementen derart gesteuert ist, daß sich auf der Oberfläche der Heizwalze in Axialrichtung eine Temperaturverteilung ergibt, die in der Mittelzone ein Extremum und nahe den beiden Stirnflächen Maxima aufweist, und daß der eine Temperaturfühler auf der Höhe des Extremums der Oberflächentemperatur in der Walzenmitte und der andere Temperaturfühler auf der Höhe der Mitte einer der Randzonen der Heizwalze angeordnet ist.This object is achieved in that in the interior of the heating roller another electric heating element which is connected to the control via a further temperature sensor runs parallel to the roller axis in that one heating element consists of a coil in the central zone of the heating roller and the other heating element There are two coils in the edge zones of the heating roller adjoining the central zone on the left and right that the coil in the central zone overlaps with each of the two coils in each edge zone so that the current supply to the heating elements is controlled in such a way that the surface of the heating roller is controlled results in a temperature distribution in the axial direction, which has an extremum in the central zone and maxima close to the two end faces, and that one temperature sensor is located at the extremum of the surface temperature in the middle of the roll and the other temperature sensor is located at the middle of one of the peripheral zones of the heating roll is.

Die weitere Ausgestaltung der Erfindung ergibt sich aus den Merkmalen der Ansprüche 2 bis 12.The further embodiment of the invention results from the features of claims 2 to 12.

Mit der Erfindung werden die Vorteile erzielt, daß großformatige Kopien falten- und wellenfrei erstellt werden können, unabhängig von der Beschaffenheit des Kopienmaterials und daß die Formgebung der Fixierwalze zum Zeitpunkt des Kontaktes mit der Andruckwalze durch den über die Fixierwalzenlänge einstellbaren Temperaturverlauf mit geringem Aufwand im Vergleich zu der konischen Ausbildung der bekannten Fixierwalze mit verschraubbaren Pfropfen, die in axialer Richtung der Walze verstellbar sind, erreicht wird.With the invention, the advantages are achieved that large-format copies can be made wrinkle and wave-free, regardless of the nature of the copy material and that the shape of the fusing roller at the time of contact with the pressure roller through the adjustable temperature curve over the fusing roller length with little effort in comparison to the conical design of the known fixing roller with screwable plugs, which are adjustable in the axial direction of the roller, is achieved.

Die Erfindung wird im folgenden anhand eines zeichnerisch dargestellten Ausführungsbeispiels näher erläutert.The invention is explained in more detail below with reference to an exemplary embodiment shown in the drawing.

Es zeigen:

  • Fig. 1 eine schematische, perspektivische Darstellung einer Fixiervorrichtung nach der Erfindung,
  • Fig. 2 eine Schnittansicht durch die Heizwalze der in Fig. 1 dargestellten Fixiervorrichtung,
  • Fig. 3 eine grafische Darstellung des Temperaturverlaufs über die Länge der Fixierwalze, und
  • Fig. 4 einen gegenüber Fig. 3 unterschiedlichen Temperaturverlauf über die Länge der Fixierwalze.
Show it:
  • 1 is a schematic perspective view of a fixing device according to the invention,
  • 2 shows a sectional view through the heating roller of the fixing device shown in FIG. 1,
  • Fig. 3 is a graphical representation of the temperature profile over the length of the fixing roller, and
  • FIG. 4 shows a temperature profile that differs from FIG. 3 over the length of the fixing roller.

Eine in Fig. 1 dargestellte Fixiervorrichtung 1 umfaßt eine Heizwalze 10 und eine Andruckwalze 2. Die obere Heizwalze 10 bzw. Fixierwalze ist in Lagern 5 und 6, beispielsweise Kugellagern, und die untere Andruckwalze 2 in Lagern 23,24 gelagert, die jeweils im Inneren der Walzen angeordnet sind. Die Lagerung innerhalb der Walzen erfolgt dabei etwa in einem Abstand von 20 mm von den jeweiligen Stirnflächen der Walzen. Die obere Heizwalze 10 besitzt etwa eine Länge von 670 mm und besteht üblicherweise aus einem Aluminiumrohr mit einer Wandstärke von 7 bis 9 mm sowie einer Silikongummibeschichtung 25 mit einer Dicke von etwa 1-bis 1,2 mm. Die Beschichtung mit Silikongummi endet etwa 30 bis 32 mm vor den Stirnflächen 17,18 der Heizwalze 10. Die Andruckwalze 2 besteht gleichfalls aus einem Aluminiumzylinder mit einer Wandstärke von etwa 6 mm und einer Beschichtung aus Silikongummi und einem Schlauch aus einer Schrumpffolie, wobei die Dicken der Silikongummibeschichtung und des Schlauches ungefähr 3 mm beträgt. Diese Beschichtung erstreckt sich von Stirnfläche zu Stirnfläche.A fixing device 1 shown in Fig. 1 comprises a heating roller 10 and a pressure roller 2. The upper heating roller 10 or fixing roller is in bearings 5 and 6, for example ball bearings, and the lower pressure roller 2 is mounted in bearings 23, 24, each inside the rollers are arranged. The storage within the rollers takes place approximately at a distance of 20 mm from the respective end faces of the rollers. The upper heat roller 10 has a length of about 670 mm and is usually made of an aluminum tube with a wall thickness of 7 to 9 mm, and a silicone rubber coating 25 having a thickness of about 1 - 1.2 mm to. The coating with silicone rubber ends about 30 to 32 mm in front of the end faces 17, 18 of the heating roller 10. The pressure roller 2 also consists of an aluminum cylinder with a wall thickness of about 6 mm and a coating of silicone rubber and a tube made of a shrink film, the thicknesses the silicone rubber coating and the hose is approximately 3 mm. This coating extends from face to face.

Die Andruckwalze 2 wirkt mit der Heizwalze 10 zusammen, um das Kopiermaterial zu erfassen und durch den Spalt zwischen den beiden Walzen hindurchzutransportieren.The pressure roller 2 interacts with the heating roller 10 in order to grasp the copying material and to transport it through the gap between the two rollers.

Der von der Stirnfläche 17 der Walze 10 vorspringende Wellenabschnitt trägt eine Kupplung 3 mit einem Zahnrad 26, das von einem Zahnriemen 4, bzw. einer Rollenkette, angetrieben wird.The shaft section projecting from the end face 17 of the roller 10 carries a clutch 3 with a toothed wheel 26 which is driven by a toothed belt 4 or a roller chain.

Nahe der Oberfläche der Heizwalze 10 ist gegenüber der Mitte der Walze ein Temperaturfühler 19, beispielsweise ein Thermistor oder ein Thermoelement angeordnet, dessen beide Anschlußdrähte mit einer in Fig. 1 schematisch angedeuteten Steuerung 21, die den Kopierprogrammablauf steuert, verbunden sind. Nahe der Oberfläche und der einen Stirnfläche 17 der Heizwalze 10 befindet sich ein weiterer Temperaturfühler 20, nämlich ein Thermistor oder ein Thermoelement, das mit seinen beiden Anschlußdrähten mit der Steuerung 21 in Verbindung steht. Die beiden Temperaturfühler stellen sicher, daß die Energiezufuhr zu Heizelementen, die im Inneren der Heizwalze angeordnet sind, bei Erreichen von vorgegebenen Temperaturen an den Meßstellen unterbrochen wird. Anschlußdrähte 7,8 bzw. 7',8' führen aus dem Inneren der Heizwalze 10 zu der Steuerung 21, die eine Steuerschaltung zur Betätigung von Relais aufweist, welche die Verbindung zur der Netzversorgung der Heizelemente bei Erreichen von vorgegebenen Sollwerten der Temperatur aufheben.A temperature sensor 19, for example a thermistor or a thermocouple, is arranged near the surface of the heating roller 10 opposite the center of the roller, the two connecting wires of which are connected to a controller 21, which is schematically indicated in FIG. 1 and which controls the copying program sequence. Near the surface and the one end face 17 of the heating roller 10 there is a further temperature sensor 20, namely a thermistor or a thermocouple, which is connected to the controller 21 with its two connecting wires. The two temperature sensors ensure that the energy supply to heating elements which are arranged inside the heating roller is interrupted when predetermined temperatures are reached at the measuring points. Connection wires 7, 8 or 7 ', 8' lead from the interior of the heating roller 10 to the controller 21, which has a control circuit for actuating relays which remove the connection to the mains supply of the heating elements when predetermined setpoint values of the temperature are reached.

Aus Fig. 2 sind Einzelheiten des Aufbaus der Heizwalze 10 ersichtlich. Im Inneren der Heizwalze 10 verlaufen die beiden elektrischen Heizelemente 11 und 13 parallel zu einer Walzenachse 12. Das Heizelement 11 wird von einem Glaszylinder 9 eingeschlossen, in dem ein Wendel 14 verläuft, der sich über eine Mittelzone b der Heizwalze 10 erstreckt. Die Länge dieser Mittelzone b ist etwa 310 mm. Von den beiden Enden des Wendels 14 führen die Anschlußdrähte 7,7' aus dem Glaszylinder 9 heraus. Das andere Heizelement 13 weist zwei Wendel 15 und 16 auf, die sich in den an die Mittelzone b links und rechts anschließenden Randzonen a,c der Heizwalze 10 befinden. Die beiden Wendel 15 und 16 sind in der Mitte durch einen Heizdraht miteinander verbunden und in einen Glaszylinder 22 eingeschmolzen, durch dessen Stirnwände die beiden Anschlußdrähte 8,8' des Heizelements 13 hindurchgeführt sind. Der einzelne Wendel 15,16 besitzt eine Länge von ungefähr 150 mm. Die Länge des Wendels 14 in der Mittelzone b entspricht zumindest gleich der Breite des DIN A3-Formats und beträgt im allgemeinen 300 bis 305 mm.2 details of the structure of the heating roller 10 can be seen. In the interior of the heating roller 10, the two electrical heating elements 11 and 13 run parallel to a roller axis 12. The heating element 11 is enclosed by a glass cylinder 9 in which a coil 14 extends, which extends over a central zone b of the heating roller 10. The length of this central zone b is approximately 310 mm. From the two ends of the helix 14 lead wires 7,7 'from Glass cylinder 9 out. The other heating element 13 has two coils 15 and 16, which are located in the edge zones a, c of the heating roller 10 adjoining the central zone b on the left and right. The two coils 15 and 16 are connected to one another in the middle by a heating wire and melted into a glass cylinder 22, through the end walls of which the two connecting wires 8, 8 ′ of the heating element 13 are passed. The individual helix 15, 16 has a length of approximately 150 mm. The length of the helix 14 in the central zone b corresponds at least to the width of the A3 format and is generally 300 to 305 mm.

Der Wendel 14 in der Mittelzone b überlappt sich in einem Bereich g mit jedem der beiden Wendeln 15,16 in jeder der Randzonen a,c. Die Stromzufuhr zu den Heizelementen 11,13 wird derart gesteuert, daß sich auf der Oberfläche der Heizwalze 10 in Axialrichtung eine in Fig. 3 dargestellte Temperaturverteilung ergibt, die in der Mittelzone b ein Minimum und nahe den beiden Stirnflächen 17,18 der Heizwalze 10 Maxima e und f aufweist. Zur genauen Steuerung der Temperaturverteilung befindet sich der Temperaturfühler 19 auf der Höhe des Minimums d der Oberflächentemperatur in der Walzenmitte und der andere Temperaturfühler 20 auf der Höhe des Maximums der Oberflächentemperatur der Heizwalze 10 nahe einer der Stirnflächen 17 bzw. 18. Durch die Überlappung der Wendeln 14,15,16 wird an den Übergangsstellen von der Mittelzone zu den Randzonen ein gleichmäßiger Temperaturverlauf erreicht.The helix 14 in the central zone b overlaps in an area g with each of the two helices 15, 16 in each of the peripheral zones a, c. The current supply to the heating elements 11, 13 is controlled in such a way that a temperature distribution shown in FIG. 3 results in the axial direction on the surface of the heating roller 10, which has a minimum in the central zone b and 10 maxima near the two end faces 17, 18 of the heating roller has e and f. For precise control of the temperature distribution, the temperature sensor 19 is located at the level of the minimum d of the surface temperature in the middle of the roller and the other temperature sensor 20 is at the level of the maximum of the surface temperature of the heating roller 10 near one of the end faces 17 and 18, respectively. Due to the overlap of the coils 14, 15, 16 a uniform temperature profile is achieved at the transition points from the central zone to the peripheral zones.

Die Steuerung der Heizelemente 11,13 durch die Temperaturfühler 19,20 erfolgt in der Weise, daß sich eine Temperaturdifferenz Δϑ von 2° bis 10 ° C zwischen der Mitte der Heizwalze 10 und den Randzonen a und c der Heizwalze einstellt. Diese Temperaturdifferenz stellt sich ein, sobald die beiden Heizelemente 11 und 13 beheizt werden.The heating elements 11, 13 are controlled by the temperature sensors 19, 20 in such a way that a temperature difference Δϑ of 2 ° to 10 ° C. occurs between the center of the heating roller 10 and the edge zones a and c of the heating roller. This temperature difference arises as soon as the two heating elements 11 and 13 are heated.

Die Größe der Temperaturdifferenz Δϑ wird in Abhängigkeit von dem Kopiermaterial festgelegt, wobei für Opakpapier im allgemeinen eine kleinere Temperaturdifferenz als für Transparentpapier gewählt wird.The size of the temperature difference .DELTA..phi. Is determined as a function of the copying material, a smaller temperature difference being generally chosen for opaque paper than for transparent paper.

Die Beheizung der beiden Heizelemente erfolgt derart, daß bei Formaten des Kopiermaterials von DIN A4 und DIN A3 zunächst nur das Heizelement 11 mit dem Wendel 14 in der Mittelzone b der Heizwalze 10 eingeschaltet ist. Sobald die gemessene Temperaturdifferenz Δϑ größer als 2° bis 10 °C zwischen der Mittelzone b und den Randzonen a und c ist, wird durch die Steuerung 21 das Heizelement 13 mit den beiden Wendeln 15 und 16 automatisch zugeschaltet. Dadurch soll vermieden werden, daß die Temperaturdifferenz größer als 10 °C wird, da ansonsten die Wartezeiten zu groß werden, falls nach längerem Betrieb der Fixierstation zum Fixieren von DIN A3 und DIN A4-Formaten auf größere Formate wie DIN A2 und DIN Al umgeschaltet wird.The heating of the two heating elements is carried out in such a way that in the case of formats of the copying material of A4 and A3, only the heating element 11 with the coil 14 in the central zone b of the heating roller 10 is switched on. As soon as the measured temperature difference Δϑ is greater than 2 ° to 10 ° C between the central zone b and the peripheral zones a and c, the heating element 13 with the two coils 15 and 16 is automatically switched on by the controller 21. This is to avoid that the temperature difference is greater than 10 ° C, since otherwise the waiting times become too large if formats A4 switched after prolonged operation of the fixing station for fixing A3 and DI N to larger formats such as DIN A2 and DIN Al becomes.

Werden von Anfang an große Formate wie DIN Al und DIN A2 entwickelt, so werden beide Heizelemente 11 und 13 zur gleichen Zeit eingeschaltet.If large formats such as DIN Al and DIN A2 are developed from the start, both heating elements 11 and 13 are switched on at the same time.

Mit der Steuerung der Oberflächentemperatur der Heizwalze 10 innerhalb von Temperaturzonen lassen sich die Probleme im Zusammenhang mit der Falten- und Wellenbildung, die vor allem bei großformatigen DIN A-2 und DIN A1-Kopien bei Verwendung von bekannten Fixiervorrichtungen mit herkömmlicher Temperaturregelung auftreten, lösen. Wird bei den bekannten Fixiervorrichtungen eine möglichst gleichförmige Temperatur über die Länge der Fixierwalze eingestellt, so kommt es zu unerwünschter Faltenbildung in der Mitte der Kopie, die, wie genaue Untersuchungen ergaben, dadurch entsteht, daß die Durchtrittsgeschwindigkeit im Walzenspalt in der Mitte der Walzenanordnung größer als an den Rändern ist. Es werden dann die Randzonen zur Mitte des Kopiermaterials zusammengeschoben und es bildet sich eine Längswelle aus, die beim Durchtritt durch den Walzenspalt zu einer Quetschfalte zusammengepreßt wird. Die Faltenbildung tritt überwiegend im mittleren Bereich der zweiten Hälfte einer DIN A1-bzw.By controlling the surface temperature of the heating roller 10 within temperature zones, the problems associated with the formation of wrinkles and waves, which occur especially with large-format DIN A-2 and DIN A1 copies when using known fixing devices with conventional temperature control, can be solved. If, in the known fixing devices, a temperature that is as uniform as possible is set over the length of the fixing roller, undesirable wrinkling occurs in the center of the copy, which, as detailed investigations have shown, is caused by the fact that the passage speed in the roller gap in the center of the roller arrangement is greater than is on the edges. The edge zones are then pushed together towards the center of the copying material and a longitudinal shaft is formed, which is pressed together to form a pinch fold as it passes through the nip. The formation of folds occurs predominantly in the middle area of the second half of a DIN A1 or.

DIN A2-Kopie aus Transparentpapier auf Ein weiteres Problem bei den herkömmlichen Fixiervorrichtungen, mit denen großformatige Kopien erstellt werden sollen, ergibt sich aus der Duplizierung des Kopienbildes durch einen Doppelabdruck, bei dem ein zweites Bild nur wenige Zehntel Millimeter gegenüber dem ersten Bild versetzt in der zweiten Hälfte einer DIN A1- bzw. DIN A2-Kopie, vorwiegend bei Opakpapier, auftritt. Eine mögliche Erklärung für diese Erscheinung ist darin zu sehen, daß sich in der Mitte des Kopiermaterials eine sogenannte Bugwelle ausbildet, wobei es zu einer vorzeitigen Berührung des Tonerbildes auf der Bugwelle mit der Heizwalze kommt, wodurch es zu einem Kaltoffset-Effekt kommt, der das zweite, gegenüber dem ersten Bild versetzte Bild verursacht.DIN A2 copy of tracing paper on Another problem with the conventional fixing devices with which large-format copies are to be made arises from the duplication of the copy image by means of a double impression, in which a second image is offset by only a few tenths of a millimeter in relation to the first image second half of a DIN A1 or DIN A2 copy, mainly with opaque paper. A possible explanation for this phenomenon can be seen in the fact that a so-called bow wave forms in the middle of the copy material, whereby the toner image on the bow wave comes into premature contact with the heating roller, which leads to a cold offset effect which causes the second image, which is offset from the first image.

Um die Faltenbildung und die Duplizierung des Originalbildes zu ergründen, wurden zunächst sogenannte Schmalbahnpapiere in einer Klimakammer untersucht. Unter Schmalbahnpapieren sind solche Papiere zu verstehen, die längs zur Laufrichtung des Papierbandes auf Formate zugeschnitten sind. Aufgrund der Herstellung dieser Papiere schrumpfen diese bei Feuchtigkeitsentzug im wesentlichen nur in Querrichtung, jedoch kaum in Längsrichtung.In order to investigate the formation of folds and the duplication of the original image, so-called narrow web papers were first examined in a climatic chamber. Narrow web papers are to be understood as papers that are cut to formats along the direction of the paper tape. As a result of the production of these papers, they shrink only in the transverse direction when moisture is removed, but hardly in the longitudinal direction.

Die Maße, Beschaffenheit der Kopiermaterialien und die Umgebungsgrößen wie Temperatur, Luftfeuchtigkeit, Verweildauer in der Klimakammer sind nachstehend tabellarisch angeführt:

Figure imgb0001
The dimensions, nature of the copying materials and the environmental parameters such as temperature, air humidity, length of stay in the climatic chamber are listed in the table below:
Figure imgb0001

Wie die Tabellenwerte erkennen lassen, zeigen die Schmalbahnpapiere, ob nun Opak- oder Transparentpapiere, in Längsrichtung große Formstabilität, die maximale Schrumpfung bei Verminderung der relativen Luftfeuchtigkeit um 57 % und bei einer Temperaturabnahme von 30 °C auf 20 °C beträgt 2,8 mm bei einer mittleren Länge von 500 mm, während in Querrichtung die maximale Schrumpfung bis zu 15 mm bei einer mittleren Breite von 500 mm betragen kann.As can be seen from the table values, the narrow web papers, whether opaque or transparent papers, show great dimensional stability in the longitudinal direction, the maxima le shrinkage when the relative humidity is reduced by 57% and the temperature drops from 30 ° C to 20 ° C is 2.8 mm with an average length of 500 mm, while in the transverse direction the maximum shrinkage is up to 15 mm with an average width of Can be 500 mm.

Bei Erhöhung der relativen Luftfeuchtigkeit tritt der umgekehrte Effekt auf, nämlich eine Ausdehnung bzw. eine Quellung in Querrichtung.When the relative air humidity increases, the reverse effect occurs, namely expansion or swelling in the transverse direction.

Der Tabelle ist zu entnehmen, daß Transparentpapier stärker als Opakpapier schrumpft bzw. bei einer Erhöhung der relativen Luftfeuchtigkeit sich ausdehnt, während Kunststoff-Folie als Kopiermaterial, wie beispielsweise Hostaphan (R) sowohl in Quer- als auch in Längsrichtung weitgehend maßstabil ist.The table shows that tracing paper shrinks more than opaque paper or expands when the relative humidity increases, while plastic film as copying material, such as Hostaphan ( R ), is largely dimensionally stable in both the transverse and longitudinal directions.

Werden nun beispielsweise Opak- bzw. Transparentpapiere, die auf der Oberfläche das zu entwickelnde Tonerbild tragen, durch die Fixierstation transportiert, so wird in dieser den Papieren durch die Wärmeentwicklung der Heizelemente Feuchtigkeit entzogen, d.h. es kommt zu einer Schrumpfung der Papiere, vor allem in Querrichtung. Dadurch werden die Randzonen des Kopierpapiers in Richtung Mitte des Kopierblattes geschoben und in der Mitte bildet sich daraufhin eine Längswelle im Kopierpapier aus. Durch den in der Mitte der Walzenanordnung auftretenden Papierstau ergibt sich eine Pressung der Walzen. Es muß eine größere Menge Material im Vergleich zu den Rändern der Walzen durch die Preßstelle hindurchtransportiert werden, was nur möglich ist, wenn die Durchlaufgeschwindigkeit des Kopierpapiers in der Mitte im Vergleich zu den Rändern ansteigt, was jedoch andererseits zu der unerwünschten Faltenbildung, wie voranstehend erörtert wurde, führt. Um dieser zu begegnen, ist es erforderlich, die Durchlaufgeschwindigkeit an den Rändern der Walzenanordnung zu vergrößern, d.h. an die durch das Papierschrumpfen erhöhte Durchlaufgeschwindigkeit in der Walzenmitte anzugleichen. Dies geschieht durch die Ausbildung der Heizwalze 10, wie sie anhand der Zeichnungen erläutert wurde. Durch die Zonenregelung der Temperatur der Heizwalze besitzt diese in den Randzonen einen geringfügig größeren Durchmesser, so daß die Walzenpressungen in den Randzonen und in der Mitte aneinander angeglichen sind und somit die Durchlaufgeschwindigkeit des Kopierpapiers über die gesamte Walzenbreite annähernd gleichgroß ist.If, for example, opaque or transparent papers, which carry the toner image to be developed on the surface, are transported through the fusing station, moisture is removed from the papers in the fusing station due to the heat generated by the heating elements, i.e. the papers shrink, especially in Cross direction. As a result, the edge zones of the copy paper are pushed in the direction of the center of the copy sheet and a longitudinal wave then forms in the center of the copy paper. The paper jam occurring in the middle of the roller arrangement results in the rollers being pressed. It needs a lot of mate rial compared to the edges of the rollers through the press, which is only possible if the throughput speed of the copy paper increases in the middle compared to the edges, but on the other hand leads to the undesirable wrinkling, as discussed above. In order to counteract this, it is necessary to increase the throughput speed at the edges of the roller arrangement, that is, to adjust it to the throughput rate increased in the middle of the roller due to the paper shrinking. This is done by the formation of the heating roller 10, as was explained with reference to the drawings. Due to the zone control of the temperature of the heating roller, it has a slightly larger diameter in the edge zones, so that the roller pressures in the edge zones and in the middle are aligned with one another and the throughput speed of the copy paper is approximately the same across the entire roller width.

Die Temperaturdifferenz Δϑ zwischen der einzelnen Randzone und der Mitte der Walzenanordnung soll 10 °C nicht überschreiten, da anderenfalls die Walzenpressung in den Randzonen größer als in der Mitte wird, so daß die Durchlaufgeschwindigkeit des Kopierpapiers an den Rändern höher als in der Mitte wird. Es kommt dann zu einer Duplizierung des Kopierbildes, deren Ursache die Anhäufung der langsamer transportierten Papierzonen in der Mitte zu der voranstehend erwähnten Bugwelle ist.The temperature difference Δϑ between the individual edge zone and the center of the roller arrangement should not exceed 10 ° C, since otherwise the roller pressure in the edge zones will be greater than in the middle, so that the throughput speed of the copy paper at the edges will be higher than in the middle. The copy image is then duplicated, the cause of which is the accumulation of the slower paper zones in the middle of the bow wave mentioned above.

Bei dem in Fig. 3 schematisch dargestellten, jedoch charakteristischen Temperaturverlauf über die Länge der Heizwalze 10 beträgt die Temperatur im Minimum d 180 °C, in den Maxima e und f 193 °C und in den Randzonen der Heizwalze über den gesamten Randzonenbereich 186 °C. Die sich in den Randzonen einstellende konstante Temperatur ist die höchste Temperatur innerhalb der für die Fixierung wirksamen Temperaturzonen der Heizwalze, während die Temperaturmaxima e und f außerhalb der Silikonbeschichtung und somit des für die Fixierung wirksamen Walzenbereichs liegen.In the case of the characteristic temperature curve shown schematically in FIG. 3 over the length of the heating roller 10, the temperature in the minimum d is 180 ° C., in the maxima e and f 193 ° C. and in the peripheral zones of the heating roller over the entire peripheral zone region 186 ° C. . The constant temperature which arises in the peripheral zones is the highest temperature within the temperature zones of the heating roller which are effective for fixing, while the temperature maxima e and f lie outside the silicone coating and thus the roller region which is effective for fixing.

Fig. 4 gibt einen Temperaturverlauf über die Heizwalzenlänge wieder, der nach längerem Betrieb der Fixierstation durch entsprechende Steuerung der Stromzufuhr zu den Heizelementen 11 und 13 eingestellt wird. Es zeigt sich nämlich, daß die Mittelzone b der Heizwalze bei längerem Betrieb stärker als die Randzonen a, c beansprucht wird, was zur Folge hat, daß der Durchmesser in der Mitte der Heizwalze um etwa 0,1 mm pro 10000 Kopien im Vergleich zu den Durchmessern der Randzonen a und c abnimmt. Eine denkbare Erklärung hierfür könnte ein stärkerer mechanischer Abrieb und/oder ein stärkerer Austrag von Silikonöl aus der Silikongummibeschichtung in der Mitte der Heizwalze sein. Dieser Vorgang erfordert eine Anpassung des Temperaturprofils in der Weise, daß die Temperatur der Mittelzone gegenüber derjenigen der Randzonen angehoben wird, um weiterhin einen gleichmäßigen gegenseitigen Andruck der Walzen über ihre Gesamtlänge zu gewährleisten.Fig. 4 shows a temperature curve over the heating roller length, which is set after long operation of the fuser by appropriate control of the power supply to the heating elements 11 and 13. It can be seen that the central zone b of the heating roller is subjected to greater stress than the edge zones a, c during longer operation, with the result that the diameter in the center of the heating roller is about 0.1 mm per 10,000 copies in comparison to the Diameters of the edge zones a and c decreases. A conceivable explanation for this could be a stronger mechanical abrasion and / or a greater discharge of silicone oil from the silicone rubber coating in the middle of the heating roller. This process requires an adjustment of the temperature profile in such a way that the temperature of the central zone is raised in relation to that of the peripheral zones in order to continue to ensure a uniform mutual pressure of the rollers over their entire length.

Die charakteristische Temperatur im Maximum d' in der Mittelzone beträgt beispielsweise 182 °C, in den Maxima e' und f' etwa 181 °C und in den Randzonen im Mittel 175 °C bei dem Temperaturprofil nach Fig. 4.The characteristic temperature in the maximum d 'in the central zone is, for example, 182 ° C, in the maxima e' and f 'approximately 181 ° C and in the peripheral zones on average 175 ° C for the temperature profile according to FIG. 4.

Claims (12)

1. Walzenfixiervorrichtung mit einer Andruckwalze und einer von innen beheizten Heizwalze als Fixierwalze zum Fixieren eines Tonerbildes auf Kopiermaterial, mit zumindest einem im Inneren der Heizwalze parallel zur Walzenachse angeordneten elektrischen Heizelement, wobei die Oberfläche der Heizwalze in Achsenrichtung eine ungleichmäßige Temperaturverteilung aufweist, mit zumindest einem der Oberfläche der Heizwalze gegenüberliegenden Temperaturfühler, der an eine Steuerung für die Stromzufuhr zum Heizelement angeschlossen ist, dadurch gekennzeichnet, daß im Inneren der Heizwalze (10) ein weiteres elektrisches Heizelement (13), das mit der Steuerung (21) über einen weiteren Temperaturfühler (20) verbunden ist, parallel zu der Walzenachse (12) verläuft, daß das eine Heizelement (11) aus einem Wendel (14) in der Mittelzone (b) der Heizwalze (10) und das andere Heizelement (13) aus zwei Wendeln (15,16) in den an die Mittelzone links und rechts anschließenden Randzonen (a,c) der Heizwalze (10) besteht, daß sich der Wendel (14) in der Mittelzone (b) mit jedem der beiden Wendeln (15,16) in jeder Randzone (a,c) überlappt, daß die Stromzufuhr zu den Heizelementen (11,13) derart gesteuert ist, daß sich auf der Oberfläche der Heizwalze (10) in Axialrichtung eine Temperaturverteilung ergibt, die in der Mittelzone ein Extremum (d;d') und nahe den beiden Stirnflächen (17,18) Maxima (e,f;e',f') aufweist, und daß der eine Temperaturfühler (19) auf der Höhe des Extremums (d;d') der Oberflächentemperatur in der Walzenmitte und der andere Temperaturfühler (20) auf der Höhe der Mitte einer der Randzonen (a;c) der Heizwalze (10) angeordnet ist.1. Roller fixing device with a pressure roller and an internally heated heating roller as a fixing roller for fixing a toner image on copying material, with at least one electric heating element arranged inside the heating roller parallel to the roller axis, the surface of the heating roller having an uneven temperature distribution in the axial direction, with at least one The temperature sensor opposite the surface of the heating roller, which is connected to a control for the power supply to the heating element, characterized in that in the interior of the heating roller (10) a further electrical heating element (13), which is connected to the control (21) via a further temperature sensor ( 20) is connected parallel to the roller axis (12) that one heating element (11) consists of a coil (14) in the central zone (b) of the heating roller (10) and the other heating element (13) consists of two coils (15 , 16) in the edge zones (a, c) of the heating roller (left and right) adjoining the central zone ( 10) there is that the coil (14) in the central zone (b) overlaps with each of the two coils (15, 16) in each edge zone (a, c) so that the power supply to the heating elements (11, 13) is controlled in this way is that there is a temperature distribution on the surface of the heating roller (10) in the axial direction, which has an extremum (d; d ') in the central zone and maxima (e, f; e', f near the two end faces (17, 18) '), and that the one temperature sensor (19) at the level of the extremum (d; d ') of the surface temperature in the middle of the roller and the other temperature sensor (20) at the level of the center of one of the edge zones (a; c) of the heating roller (10). 2. Walzenfixiervorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß das Extremum in der Mittelzone ein Minimum (d) ist.2. Roller fixing device according to claim 1, characterized in that the extremum in the central zone is a minimum (d). 3. Walzenfixiervorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß das Extremum in der Mittelzone ein Maximum (d') ist.3. roll fixing device according to claim 1, characterized in that the extremum in the central zone is a maximum (d '). 4. Walzenfixiervorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß die Länge des Wendels (14) in der Mittelzone (b) zumindest gleich der Breite des DIN-Formats A3 ist.4. roller fixing device according to claim 1, characterized in that the length of the helix (14) in the central zone (b) is at least equal to the width of the DIN format A3. 5. Walzenfixiervorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß jeder Wendel (15,16) in den Randzonen (a,c) eine Länge von zumindest 150 mm aufweist.5. roller fixing device according to claim 1, characterized in that each coil (15,16) in the edge zones (a, c) has a length of at least 150 mm. 6. Walzenfixiervorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß die überlappung zwischen dem Wendel (14) in der Mittelzone (b) und den Wendeln (15,16) in den Randzonen (a,c) bis zu 5 mm beträgt.6. roll fixing device according to claim 1, characterized in that the overlap between the helix (14) in the central zone (b) and the helixes (15,16) in the edge zones (a, c) is up to 5 mm. 7. Walzenfixiervorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß die Steuerung der Heizelemente (11,13) durch die Temperaturfühler (19,20) in der Weise erfolgt, daß sich eine Temperaturdifferenz Δϑ von 2° bis 10 °C zwischen der Mitte der Heizwalze (10) und den Randzonen (a,c) der Heizwalze einstellt, sobald beide Heizelemente (11,13) geheizt sind.7. roller fixing device according to claim 1, characterized in that the control of the heating elements (11,13) by the temperature sensor (19,20) in Wei se is that a temperature difference Δϑ of 2 ° to 10 ° C between the center of the heating roller (10) and the peripheral zones (a, c) of the heating roller sets as soon as both heating elements (11,13) are heated. 8. Walzenfixiervorrichtung nach Anspruch 5, dadurch gekennzeichnet, daß die Größe der Temperaturdifferenz Δϑ in Abhängigkeit von dem Kopiermaterial festgelegt wird.8. roller fixing device according to claim 5, characterized in that the size of the temperature difference Δϑ is determined depending on the copying material. 9. Walzenfixiervorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß bei Formaten des Kopiermaterials von DIN A4 und DIN A3 nur das Heizelement (11) mit dem Wendel (14) in der Mittelzone (b) der Heizwalze (10) eingeschaltet ist.9. roller fixing device according to claim 1, characterized in that in formats of the copy material of A4 and A3 only the heating element (11) with the coil (14) in the central zone (b) of the heating roller (10) is switched on. 10. Walzenfixiervorrichtung nach Anspruch 9, dadurch gekennzeichnet, daß das Heizelement (13) mit den beiden Wendeln (15,16) in den Randzonen (a,c) zugeschaltet wird, sobald die gemessene Temperaturdifferenz Δϑ größer als 2° bis 10 °C ist.10. roller fixing device according to claim 9, characterized in that the heating element (13) with the two coils (15,16) in the edge zones (a, c) is switched on as soon as the measured temperature difference Δϑ is greater than 2 ° to 10 ° C. . 11. Walzenfixiervorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß bei Formaten DIN A2 und DIN Al des Kopiermaterials beide Heizelemente (11,13) eingeschaltet sind.11. Roller fixing device according to claim 1, characterized in that both formats heating elements (11, 13) are switched on for formats DIN A2 and DIN Al of the copying material. 12. Walzenfixiervorrichtung nach Anspruch 8, dadurch gekennzeichnet, daß die Temperaturdifferenz Δϑ aus der Temperatur in der Mitte der Randzone (a;c) der Heizwalze (10) und der Temperatur in der Mitte der Heizwalze (10) gebildet ist, daß eine Silikongummibeschichtung (25) der Heizwalze (10) jeweils 30 bis 33 mm von den Stirnflächen (17,18) der Heizwalze (10) endet und daß die Maxima e und f der Temperatur außerhalb der Silikongummibeschichtung (25) der Heizwalze (10) auftreten.12. roll fixing device according to claim 8, characterized in that the temperature difference Δϑ from the temperature in the middle of the edge zone (a; c) of Heating roller (10) and the temperature in the middle of the heating roller (10) is formed so that a silicone rubber coating (25) of the heating roller (10) ends 30 to 33 mm from the end faces (17, 18) of the heating roller (10) and that the maxima e and f of the temperature occur outside the silicone rubber coating (25) of the heating roller (10).
EP84102432A 1983-03-16 1984-03-07 Roll fusing unit Expired EP0121772B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84102432T ATE23229T1 (en) 1983-03-16 1984-03-07 ROLLER FIXING DEVICE.

Applications Claiming Priority (2)

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DE19833309398 DE3309398A1 (en) 1983-03-16 1983-03-16 ROLLER FIXING DEVICE
DE3309398 1983-03-16

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EP0121772A1 true EP0121772A1 (en) 1984-10-17
EP0121772B1 EP0121772B1 (en) 1986-10-29

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US (1) US4585325A (en)
EP (1) EP0121772B1 (en)
JP (1) JPS59177581A (en)
AT (1) ATE23229T1 (en)
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DE (2) DE3309398A1 (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0304803A1 (en) * 1987-08-20 1989-03-01 Canon Kabushiki Kaisha Image forming apparatus
EP0400236A1 (en) * 1988-03-28 1990-12-05 Xerox Corporation Fusing apparatus control system
EP0564420A2 (en) * 1992-03-31 1993-10-06 Canon Kabushiki Kaisha Image heating device capable of controlling activation of plural heaters
EP0564420A3 (en) * 1992-03-31 1993-11-03 Canon Kabushiki Kaisha Image heating device capable of controlling activation of plural heaters
US5512993A (en) * 1992-03-31 1996-04-30 Canon Kabushiki Kaisha Image heating device capable of controlling activation of plural heaters

Also Published As

Publication number Publication date
ATE23229T1 (en) 1986-11-15
JPS59177581A (en) 1984-10-08
EP0121772B1 (en) 1986-10-29
CA1220509A (en) 1987-04-14
DE3461123D1 (en) 1986-12-04
DE3309398A1 (en) 1984-09-20
US4585325A (en) 1986-04-29

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