JP2008112050A - Heat roller, fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat roller which achieves shortening of warm-up time, excels in power saving and imparting proper gloss to toner after fixing, thereby forming a glossy image, in the fixing device of an image forming apparatus. <P>SOLUTION: The heat roller 52 used for the fixing device is composed of synthetic resin having electric insulating property, and is equipped with a base body 31 having cylindrical shape. A heat resistant insulating layer 34 is formed on the outer periphery of the base body 31, and a heating element 35 is formed on the heat resistant insulating layer 34 so as to have pattern shape comprising a plurality of lines. The heating element 35 is constituted to generate heat by application of voltage, and the film type heater 33 is constituted of the heat resistant insulating layer 34 and the heating element 35. An elastic layer 38 is layered on the film type heater 33, and further a releasing layer 37 having high releasing property to toner is layered thereon. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a configuration of a heat roller used in a fixing device for fixing toner on a recording medium. Furthermore, the present invention relates to a fixing device and an image forming apparatus using the heat roller.

Patent Document 1 discloses a heat roller fixing type fixing device used in an electrophotographic image forming apparatus. The fixing device of Patent Document 1 has a configuration in which a heat roller and a press roller are pressed against each other to form a nip portion, and the paper passing through the nip portion is heated and pressed to fix the toner onto the paper. . In the configuration of Patent Document 1, the heat roller is formed in a cylindrical shape, and a halogen lamp as a heat source is disposed inside the heat roller.
Japanese Patent Laying-Open No. 2005-257852

  However, the halogen lamp built-in heat roller disclosed in Patent Document 1 has a configuration in which the roller is heated from the inside, and therefore, the time from the start of heating until the roller surface rises to the required temperature. There is room for improvement in terms of shortening the warm-up time. Further, since the heat source is arranged on the inner peripheral side of the cylindrical roller, the roller surface cannot be efficiently heated, and there is room for improvement from the viewpoint of energy saving.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a heat roller, a fixing device, and an image forming apparatus capable of reducing the warm-up time and saving power.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

  According to a first aspect of the present invention, there is provided the following configuration of a heat roller used in a fixing device for fixing toner on a recording medium. That is, it is made of a synthetic resin having electrical insulating properties, and has a base body having a columnar shape or a cylindrical shape, an electrical insulating layer laminated on the outer periphery of the base body, and a plurality of wires on the electrical insulating layer. A sheet heating element including a heating layer formed to have a pattern shape and generating heat upon application of a voltage, an elastic layer stacked on the sheet heating element, and stacked on the elastic body, And a release layer having a high releasability with respect to the toner.

  Thereby, since the heat source, that is, the planar heating element is arranged near the roller surface, the temperature of the roller surface can be rapidly increased, and the warm-up time can be shortened. In addition, since the planar heating element is disposed outside the base body, useless heating of the center portion of the heat roller can be prevented, and power saving is excellent. Furthermore, since the heat generating layer of the planar heat generating element has a pattern shape composed of a plurality of lines, uneven heat generation can be reduced. In addition, since the elastic layer is disposed between the sheet heating element and the release layer, the toner after fixing can be imparted with appropriate gloss and a glossy image can be formed.

  In the heat roller, the elastic layer is preferably a silicone rubber layer, and more preferably, the silicone rubber layer is a foamed silicone layer.

  As a result, a good gloss can be imparted to the toner after fixing, and a higher image quality can be achieved.

  According to a second aspect of the present invention, there is provided a fixing device including the heat roller and a press roller that elastically contacts the outer peripheral surface of the heat roller.

  Thereby, it is possible to provide an image forming apparatus having a short warm-up time, power saving, and excellent image quality of the formed image.

  In the fixing device, the press roller is preferably a sponge press roller.

  Thereby, it is possible to prevent the heat of the heat roller from escaping by the heat insulating effect of the sponge, so that further power saving can be achieved. In addition, since a large area of the nip portion between the heat roller and the press roller can be ensured, the toner can be reliably fixed to the recording medium.

  According to a third aspect of the present invention, there is provided an image forming apparatus including an image forming unit for forming an unfixed toner image on a recording medium by electrophotography and the fixing device.

  As a result, the first print time can be shortened, and an image forming apparatus with excellent power saving and good image quality can be provided.

  Next, embodiments of the invention will be described. FIG. 1 is an external perspective view of a copy facsimile multifunction peripheral according to an embodiment of the present invention, and FIG. 2 is a front sectional view showing the inside of the main body of the multifunction peripheral.

  As shown in the external perspective view of FIG. 1, a copy facsimile multifunction machine 75 as an image forming apparatus instructs an image reading unit 76 functioning as a flatbed scanner and an auto document feed scanner, the number of copies, a facsimile transmission destination, and the like. An operation panel 77, a main body 78 including an image forming unit for forming an image on a sheet as a recording medium, and a sheet feeding cassette 79 for sequentially supplying the sheet. The main body 78 includes a transmission / reception unit (not shown) for transmitting image data via a communication line.

  The inside of the copy facsimile multifunction machine 75 is shown in FIG. As shown in FIG. 2, a platen glass 82 on which a document to be read is placed is provided on the upper surface of the main body 78. A document table cover 83 is provided above the main body 78, and the document table cover 83 can press and fix the document on the platen glass 82.

  The document table cover 83 is provided with an automatic document feeder (auto document feeder, ADF) 84. The ADF 84 includes a document tray 85 provided above the document table cover 83, and a discharge tray 86 provided below the document tray.

  As shown in FIG. 2, a curved document transport path 87 that connects the document tray 85 and the discharge tray 86 is formed inside the document table cover 83. A separation roller 88 and a plurality of transport rollers 89 are arranged in the document transport path 87. With this configuration, the documents set on the document tray 85 are separated one by one and conveyed along the curved document conveyance path 87, and after passing through the document reading position, are discharged to the discharge tray 86. The

  As shown in FIG. 2, a scanner unit 90 is provided on the upper portion of the main body 78. The scanner unit 90 includes a light source 91 that irradiates light to the original reading position of the platen glass 82 or the ADF 84, reflection mirrors 92, 93, and 94 that reflect light reflected from the original, and converges the reflected light. A condensing lens 95 and a charge coupled device (CCD) 96 that converts the convergent light into an electric signal and outputs the electric signal are provided.

  The light source 91 and the reflecting mirror 92 of the scanner unit 90 are configured to be appropriately movable. The original placed on the platen glass 82 is scanned while moving, or moved to the original reading position of the ADF 84, It is possible to scan a document conveyed through the document conveyance path 87.

  The reflected light from the original is guided to the CCD 96 to form an image, and the CCD 96 outputs an electrical signal corresponding to the original. This signal is sent to an image forming unit 11 (to be described later) for printing after appropriate conversion processing, or transmitted to another facsimile apparatus via a communication line by the transmission / reception unit.

  As shown in FIG. 2, a paper feed cassette 79 for supplying paper 100 is provided at the lower part of the main body 78. The paper feed cassette 79 is configured to be pulled out to the front side of the apparatus (the front side of the paper in FIG. 2). An image forming unit 11, a fixing device 51, and a paper discharge tray 80 are provided above the paper feed cassette 79.

  Inside the main body 78, a transport path 24 for transporting the paper 100 from the paper feed cassette 79 to the paper discharge tray 80 is formed. The conveyance path 24 extends upward from one end side of the paper feed cassette 79, then curves in the horizontal direction to reach the image forming unit 11, further extends in the horizontal direction, passes through the fixing device 51, and then is discharged. It is configured to reach the paper tray 80.

  A paper feed roller 21 is disposed above the paper feed cassette 79, and is configured such that the paper feed roller 21 contacts the uppermost paper 100 stacked in the paper feed cassette 79. By driving the paper feed roller 21 in this state, the uppermost sheet 100 is separated and picked up and sent out toward the transport path 24.

  Conveying rollers 22 and 23 are arranged immediately downstream of the paper feed roller 21 in the conveying path 24. The transport rollers 22 and 23 are driven while the paper 100 is nipped between the transport rollers 22 and 23 so as to transport the paper 100 to the image forming unit 11 on the downstream side.

  As shown in FIG. 2, the image forming unit 11 has a configuration in which a charger 13, an LED head 14, a developing device 15, and a transfer roller 16 are arranged around the photosensitive drum 12.

  The photosensitive drum 12 is configured such that a photoconductive film made of an organic photoreceptor is formed on the surface and is rotated by an electric motor (not shown). The charger 13 is configured in a brush charging system, and the charger 13 uniformly charges the surface of the photosensitive drum 12, for example, negatively.

  The LED head 14 as an exposure device is disposed downstream of the charger 13 (refers to the downstream side in the rotation direction of the photosensitive drum 12; hereinafter, the same applies to the description of the developing device 15 and the transfer roller 16). In this configuration, a large number of light emitting diodes (LEDs) are arranged in the paper width direction. The LED head 14 selectively emits light corresponding to the image data of the facsimile document received via the telephone line or the image data read by the image reading unit 76. As a result, the surface of the photosensitive drum 12 is selectively exposed, and the electrostatic energy is formed by losing the charge energy of the exposed portion.

  The developing device 15 is disposed on the downstream side of the LED head 14. The developing device 15 includes a toner container 26 that stores nonmagnetic one-component toner, and a stirring blade 27 that is rotationally driven inside the toner container 26 for stirring the toner. Further, the developing device 15 is disposed so as to be in contact with the supply roller 28 disposed in the toner container 26, the development roller 29 disposed in contact with the supply roller 28, and the outer peripheral surface of the development roller 29. And a regulating blade 30 to be operated.

  With this configuration, the supply roller 28 and the developing roller 29 are rotationally driven so as to rub the circumferential surfaces in opposite directions. Further, the tip of the regulating blade 30 rubs against the peripheral surface of the developing roller 29 that is driven to rotate. As a result, the toner in the toner container 26 is frictionally charged and adheres to the surface of the developing roller 29 due to a potential difference. The toner on the surface of the developing roller 29 is adjusted by the regulating blade 30 so that the adhesion thickness is uniform, and is sent to the photosensitive drum 12 side by the rotation of the developing roller 29. Thereafter, in the vicinity of the photosensitive drum 12 and the developing roller 29, the toner on the surface of the developing roller 29 is selectively transferred to the surface of the photosensitive drum 12 only in the portion corresponding to the exposed portion of the photosensitive drum 12 by the LED head 14. Moving. As a result, a toner image is formed on the surface of the photosensitive drum 12.

  The transfer roller 16 is disposed on the downstream side of the developing unit 15 and is disposed on the opposite side of the photosensitive drum 12 with the conveyance path 24 interposed therebetween. A predetermined voltage from a power source is applied to the transfer roller 16. Accordingly, the toner image formed on the surface of the photosensitive drum 12 moves so as to approach the transfer roller 16 side by the rotation of the photosensitive drum 12, and is transferred to the paper 100 by the electric field attraction force. The sheet 100 on which the toner image is transferred is sent to the fixing device 51 on the downstream side of the conveyance path 24 by the rotation of the photosensitive drum 12.

  The fixing device 51 includes a heat roller 52 that is rotationally driven, and a press roller 53 that is disposed to face the heat roller 52. The press roller 53 is pressed against the heat roller 52 by an urging spring. The detailed configuration of the heat roller 52 and the press roller 53 will be described later.

  With this configuration, when the paper 100 passes between the heat roller 52 and the press roller 53, the toner of the toner image is melted and fixed to the paper 100 by the heat of the high-temperature heat roller 52 and the pressure by the press roller 53. The fixing device 51 is provided with a separation claw 54 for preventing the paper 100 from being wrapped around the heat roller 52 while being stuck.

  As shown in FIG. 2, a paper discharge roller 25 is provided on the downstream side of the fixing device 51. With this configuration, the sheet 100 sent from the fixing device 51 is nipped between the sheet discharge roller 25 and a driven roller disposed opposite thereto, and is discharged onto the sheet discharge tray 80.

  Next, a detailed configuration of the fixing device 51 will be described. An enlarged cross-sectional view of the fixing device 51 is shown in FIG. 3, and as shown in FIG. 3, the fixing device 51 includes a housing 55 that houses the heat roller 52 and the press roller 53. A heat roller 52 is rotatably supported on the housing 55 via a bearing 56, and a press roller 53 is rotatably supported via a bearing body 57.

  The bearing body 57 is slidably provided with respect to the housing 55, and an urging spring 58 is interposed between the bearing body 57 and the housing 55. The press roller 53 is pressed against the heat roller 52 by the spring force of the urging spring 58, and both are elastically contacted.

  Next, detailed configurations of the heat roller 52 and the press roller 53 will be described with reference to FIG. 4 is an enlarged cross-sectional view of a region (nip portion) indicated by A in FIG. The heat roller 52 includes a base body (heat-resistant carrier) 31, a film heater (planar heating element) 33, an elastic layer 38, and a release layer 37 as main components.

  The base body 31 has a cylindrical shape, and a film heater 33 is disposed outside the base body 31. The film heater 33 includes a heat-resistant insulating layer 34 and a heating element (heating layer) 35.

  The heating element 35 of the film heater 33 can be made of, for example, stainless steel, nickel alloy such as nickel chrome, nickel, or the like. The heating element 35 has a pattern shape in which a plurality of thin lines are arranged in parallel at equal intervals (heater pattern). The thickness of the heating element 35 is preferably 0.1 μm or more and 100 μm or less, for example, and more preferably about 30 μm. Specifically, sputtering, vapor deposition, metal foil etching, pattern printing, blasting, or the like can be used as a method for creating the heater pattern.

  The thickness of the heat-resistant insulating layer 34 of the film heater 33 is, for example, 1 μm to 200 μm, preferably 10 μm to 70 μm. The material of the heat-resistant insulating layer 34 is preferably a polyimide resin, a silicone resin, or the like, but is not limited thereto.

  The elastic layer 38 is a layer having appropriate elasticity, and in this embodiment, is a silicon rubber layer, specifically, a foamed silicone layer. The thickness of the elastic layer 38 is preferably 0.1 mm or more and 0.5 mm or less.

  A release layer 37 is disposed on the outermost periphery of the heat roller 52. The release layer 37 is made of a material having a high releasability with respect to the toner (a material having a low surface energy and a low intermolecular cohesive force), for example, a fluororesin such as a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, The thickness is, for example, about 30 μm.

  The film heater 33 can be formed by the following method, for example. That is, a stainless steel foil having a thickness of 25 μm is heat-pressed with a heat-resistant adhesive such as polyimide or silicone on one side of a polyimide film (corresponding to the heat-resistant insulating layer 34) as a base material. This heat-resistant adhesive can be applied by a known method such as screen printing. Next, the stainless steel foil is processed into a pattern shape having a plurality of lines by a known method such as wet etching. As a result, a heater pattern-shaped heating element (heating layer) 35 made of stainless steel foil is formed, and a film-like heater 33 having good flexibility is obtained.

  In addition, as the formation method of the said heat generating body 35, after processing the said foil-shaped material into a predetermined heater pattern shape previously by methods, such as wet etching, dry etching, and blasting, you may affix on a polyimide film. Alternatively, a wire-shaped material previously processed into a heater pattern shape may be separately attached to a polyimide film with a heat-resistant adhesive such as polyimide or silicone. Further, the foil body may be formed by using a thin film process such as sputtering or vapor deposition, or the heater pattern may be directly formed by a thin film process.

  Next, a base body 31 is prepared in which a resin having electrical insulating properties, for example, polyphenylene sulfide (PPS) resin is formed into a cylindrical shape. Then, the film-like heater 33 obtained by the above-described procedure is disposed so that the surface on the heat-resistant insulating layer 34 side faces the outer peripheral surface of the base body 31, and is heat-pressed with a heat-resistant adhesive such as silicone or polyimide. . The heat-resistant adhesive can be applied by a known method such as screen printing.

  Thereafter, a foamed silicone layer having a thickness of about 0.5 mm is formed on the outer peripheral surface of the film heater 33 to form an elastic layer 38. Further, a fluororesin layer such as tetrafluoroethylene / perfluoroalkylvinyl copolymer is formed on the outer peripheral surface of the elastic layer 38 to form a release layer 37. The heat roller 52 can be manufactured by the above process.

  As described above, the heat roller 52 of the present embodiment is made of a synthetic resin having electrical insulation, and has a base body 31 having a columnar shape or a cylindrical shape, and a heat resistant insulation laminated on the outer periphery of the base body 31. And a layer 34. On the heat-resistant insulating layer 34, a heating element 35 is formed so as to have a pattern shape composed of a plurality of lines, and the heat-resistant insulating layer 34 and the heating element 35 constitute a film heater 33. Further, an elastic layer 38 is laminated on the film heater 33, and a release layer 37 having a high releasability with respect to the toner is further laminated on the elastic layer 38.

  Thereby, since the heat source, that is, the film heater 33 is arranged near the roller surface, the temperature of the roller surface can be rapidly increased as compared with the halogen lamp built-in heat roller of Patent Document 1, and the warm-up time is increased. Can be significantly shortened. In addition, since the film heater 33 is disposed outside the base body 31, unnecessary heating of the center portion of the heat roller 52 can be prevented and power can be saved. Further, the elastic layer 38 can give gloss to the fixing toner, so that an image having a glossy and high-class feeling can be obtained. This effect is particularly effective when images such as photographs are formed.

  In the heat roller 52 of the present embodiment, the elastic layer 38 is configured as a silicon rubber layer (specifically, a foamed silicone layer). Thereby, good gloss can be imparted to the fixing toner.

  Next, the configuration of the press roller 53 elastically contacted with the heat roller 52 in the fixing device 51 will be described. As shown in FIG. 4, the press roller 53 includes a roller shaft 61 formed of a metal such as stainless steel, a cylindrical sponge body 62 fixed around the roller shaft 61, and an outer peripheral surface of the sponge body 62. And a release layer 63 disposed on the surface.

  By using the sponge press roller 53 as described above, it is possible to suppress the heat of the heat roller 52 from escaping to the press roller 53 side due to the heat insulating action of the air contained in the sponge body 62. In particular, in the present embodiment, the sheet 100 is heated by the film heater 33 having a small heat capacity, and the temperature of the surface of the heat roller 52 is likely to be lowered, so that the heat insulation effect as described above is useful. Furthermore, since the sponge body 62 of the press roller 53 is elastically deformed at the nip portion with the heat roller 52, a wide contact area between the paper 100 and the heat roller 52 at the nip portion can be secured. Therefore, the toner can be satisfactorily fixed on the paper 100 passing through the fixing device 51.

  Although the preferred embodiments and modifications of the present invention have been described above, the above configuration can be further modified as follows.

  The base body 31 can be formed in a columnar shape instead of being formed in a hollow cylindrical shape. Further, the material of the base body 31 is not limited to PPS, and heat resistant resins such as glass epoxy, and inorganic materials such as alumina, mullite, zirconia, and glass ceramics can be employed.

  For example, a heat-resistant and heat-insulating layer can be installed between the base body 31 and the film heater 33. As the configuration of the heat-resistant heat insulating layer, for example, a mat using ceramic fiber as a main component, glass fiber, foamed resin, porous ceramics, or the like can be considered.

  The heat roller and the fixing device of the present invention can be applied to various electrophotographic image forming apparatuses such as a copying machine, a facsimile machine, and a printer, as well as a copying facsimile multifunction machine.

1 is an external perspective view of a copy facsimile multifunction peripheral according to an embodiment of the present invention. FIG. 3 is a front cross-sectional view showing the inside of the main body of the multifunction machine. FIG. 3 is an enlarged cross-sectional view showing a state of the fixing device. The cross-sectional enlarged view which shows the part of A of FIG. 3 in detail.

Explanation of symbols

31 Base body 33 Film heater (planar heating element)
34 Heat-resistant insulation layer (electrical insulation layer)
35 Heating element (heating layer)
37 Release layer 38 Elastic layer 51 Fixing device 52 Heat roller 53 Press roller 75 Copy facsimile compound machine (image forming apparatus)
100 paper (recording medium)

Claims (6)

In a heat roller used in a fixing device for fixing toner on a recording medium,
A base body made of a synthetic resin having electrical insulation, and having a columnar shape or a cylindrical shape;
A surface including an electrical insulation layer laminated on the outer periphery of the base body, and a heat generation layer formed on the electrical insulation layer so as to have a pattern shape composed of a plurality of lines and generating heat upon application of voltage. A heating element,
An elastic layer laminated on the planar heating element;
A release layer laminated on the elastic body and having high releasability with respect to the toner;
The heat roller characterized by including. The heat roller according to claim 1,
The heat roller, wherein the elastic layer is a silicon rubber layer. The heat roller according to claim 2,
The heat roller, wherein the silicone rubber layer is a foamed silicone layer.   A fixing device comprising: the heat roller according to any one of claims 1 to 3; and a press roller that elastically contacts the outer peripheral surface of the heat roller.   5. The fixing device according to claim 4, wherein the press roller is a sponge press roller.   An image forming apparatus comprising: an image forming unit for forming an unfixed toner image on a recording medium by an electrophotographic method; and the fixing device according to claim 4.

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