JP5150816B2 - Heat roller, fixing device and image forming apparatus - Google Patents

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 has a columnar shape or a cylindrical shape, and at least one outer peripheral surface thereof has a base body having an electrical insulating property, an electrical insulating layer, and a pattern shape composed of a plurality of lines. A sheet heating element including a heating layer formed on the surface and generating heat upon application of a voltage; and a heat transfer layer formed in a sheet shape on the other surface of the electrical insulating layer; A release layer having high releasability, a shaft portion fixedly attached to the axial end portion of the base body on the same axis, a first electrode provided on the shaft portion, and an outer periphery of the first electrode And an annular second electrode disposed on the side, and an annular body interposed between the first electrode and the second electrode and having electrical insulation. The planar heating element is interposed between the outer peripheral surface of the base body and the release layer, and the base body, the heating layer, the electrical insulating layer, the heat transfer layer, and the separation layer. The mold layers are laminated in this order outward in the radial direction. The heat generating layer includes at least a first region and a second region adjacent to the first region in the axial direction of the heat roller. The first region and the second region are not in electrical contact. The first electrode is electrically connected to the first region of the heat generating layer. The second electrode is electrically connected to the second region of the heat generating layer. The planar heating element is formed by a method in which the heat transfer layer is formed on the other surface of the electrical insulating layer, and then the heat generating layer is formed on the one surface of the electrical insulating layer. The The planar heating element thus obtained is wound around the money base body.

Thereby, since a heat source, that is, a 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 remarkably 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. Further, since the planar heat transfer layer is disposed outside the heat generating layer, the recording medium in contact with the surface of the heat roller can be heated uniformly, and uniform toner fixing can be realized. In addition, since only the heat generating layer in a necessary region can generate heat, further power saving can be realized. In addition, the power feeding portions for the two regions can be compactly arranged around the shaft portion at the axial end portion of the heat roller. Accordingly, the configuration for supplying power can be simplified, and the fixing device and the image forming apparatus can be made compact.

  In the heat roller, the base body is preferably configured to have a thermal conductivity smaller than that of the heat transfer layer.

  Thereby, it is possible to suppress the heat generated in the heat generating layer from escaping to the base body on the inner peripheral side, so that the recording medium in contact with the surface of the heat roller can be efficiently heated and power saving can be realized.

  In the heat roller, the base body is preferably made of a synthetic resin.

  Thereby, the base body which has the above thermal characteristics can be shape | molded easily and manufactured. It is also easy to provide electrical insulation.

  The heat roller preferably further includes an elastic layer interposed between the outer peripheral surface of the base body and the planar heating element.

  As a result, the elastic layer absorbs the step between the portion having the pattern of the heat generating layer and the portion having no pattern by the elasticity, so that the surface of the heat roller can be prevented from being uneven. Accordingly, toner fixing unevenness can be avoided.

  The heat roller preferably further includes a heat insulating layer interposed between the outer peripheral surface of the base body and the planar heating element.

  Thereby, the heat generated by the heat generation layer can be prevented from escaping to the base body side by the heat insulating layer, and the recording medium can be heated more efficiently. As a result, power saving can be improved.

  In the heat roller, it is preferable that the planar heating element is formed in an elongated sheet shape, and the planar heating element is spirally wound around the base body.

  Thereby, the unevenness | corrugation of the joint of the edge parts of a planar heating element can be made small. Accordingly, it is possible to provide a heat roller having a small surface unevenness and little fixing unevenness.

In the heat roller, the planar heating element is configured in a sheet shape, the planar heating element is wound around the outside of the base body, and the edges are melt-bonded to each other by solder. preferable.

  Thereby, the edge parts of a planar heating element can be reliably joined at the joint.

  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 heat-resistant and heat-insulating layer 32, a film heater (planar heating element) 33, 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 heat conductivity of the base body 31 is smaller than the heat conductivity of the film heater 33 (the heat conductivity of the heat transfer layer 36 described later), and the heat capacity of the base body 31 is the heat capacity of the film heater 33 (heat transfer). The heat capacity of the layer 36).

  The film heater 33 disposed outside the base body 31 includes a heat-resistant insulating layer 34, a heating element (heating layer) 35, and a heat transfer layer (soaking layer) 36.

  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 heat transfer layer 36 of the film heater 33 is configured to have a thickness of, for example, 1 μm to 50 μm, preferably 10 μm to 30 μm. The heat transfer layer 36 is preferably formed using a material having a higher thermal conductivity than any of the base body 31, the heat generating body 35, the heat resistant insulating layer 34, and the heat resistant heat insulating layer 32 described later. Moreover, it is preferable that the heat conductivity of the heat transfer layer 36 is, for example, 10 W / m · K or more. Examples of the material for the heat transfer layer 36 include metals such as copper and aluminum, and ceramics such as aluminum nitride (AlN) and silicon carbide (SiC).

  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.

  A heat-resistant and heat-insulating layer 32 is interposed between the film heater 33 and the base body 31. The heat resistant heat insulating layer 32 is configured to have a thickness of 0.1 mm to 0.5 mm, for example. The material of the heat-resistant and heat-insulating layer 32 is preferably a material having a lower thermal conductivity than any of the heat generating body 35, the heat-resistant insulating layer 34, the heat transfer layer 36, and the base body 31, for example, a mat mainly composed of ceramic fibers. It is conceivable to use glass fiber, foamed resin, porous ceramics and the like.

  The film heater 33 can be formed by the following method, for example. That is, the thing which bonded copper foil to the surface of one side of the polyimide film as a base material is prepared. This polyimide film corresponds to the heat-resistant insulating layer 34, and the copper foil corresponds to the heat transfer layer 36. Then, a stainless steel foil having a thickness of 25 μm is heat-pressed with a heat-resistant adhesive such as polyimide or silicone on the surface of the polyimide film opposite to the copper foil. 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.

  As a method for forming the heat transfer layer 36, a copper foil may be separately attached to a single polyimide film with a heat-resistant adhesive such as polyimide or silicone. Further, as a method of forming the heating element 35, the foil-shaped material may be processed in advance into a predetermined heater pattern shape by a method such as wet etching, dry etching, or blasting and then attached to 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, as shown in FIG. 5, the shaft components 41 are respectively attached to the openings at both ends in the axial direction of the base body 31. The shaft part 41 includes a disc-shaped flange portion 42, a ring-shaped insertion portion 43 projecting from one surface of the flange portion 42, and a projecting surface from one surface of the flange portion 42. And a cylindrical shaft portion 44.

  The shaft component 41 is integrally formed of a material having electrical conductivity, and can be formed using, for example, brass, copper, zinc, stainless steel, or an alloy thereof. The shaft part 41 can be fixed to both shaft ends of the base body 31 by inserting and inserting the insertion portion 43 into the cylindrical hole of the base body 31.

  Next, a ceramic mat mainly composed of alumina-silica is heat-pressed to the outer peripheral surface of the base body 31 with a heat-resistant adhesive such as polyimide or silicone. Thereby, the heat-resistant and heat-insulating layer 32 is formed on the surface of the base body 31. The heat-resistant adhesive can be applied by a known method such as screen printing.

  Thereafter, the film heater 33 obtained by the above procedure is arranged so that the surface on the side of the heating element 35 faces the outer peripheral surface of the base body 31 (the heat-resistant and heat-insulating layer 32), and heat resistant such as silicone and polyimide. Heat-press with an adhesive. The heat-resistant adhesive can be applied by a known method such as screen printing. As a result, the adhesive layer 38 is interposed between the film heater 33 and the base body 31 (between the film heater 33 and the heat-resistant heat insulating layer 32).

  In the present embodiment, as shown in FIG. 5, the film heater 33 is formed in an elongated sheet shape, and is wound spirally so that its longitudinal direction is oblique to the circumferential direction of the base body 31. It is arranged. Such a spiral winding makes the step of the seam 39 portion of the film heater 33 inconspicuous and prevents unevenness of the surface of the heat roller 52, thereby realizing uniform toner fixing.

  In addition, the spiral winding makes it easy to neatly arrange the pattern (heater pattern) of the heating element 35 inside the film heater 33 across the seam 39. Accordingly, in this respect, it is possible to provide the heat roller 52 which is excellent in heat uniformity and has less toner fixing unevenness.

  However, the method is not limited to the winding method as shown in FIG. 6, and the film heater 33 can be wound so as to be parallel to the circumferential direction of the base body 31 (so-called parallel winding).

  In addition, as shown in FIG. 6, the contact part 40 is provided in the edge part of the pattern of the said heat generating body 35, and when this film-shaped heater 33 is wound around the outer periphery of the said base body 31, this contact part 40 is provided. The shaft component 41 is configured to contact the outer peripheral surface of the flange portion 42. For this reason, when the film heater 33 is wound around the base body 31, the shaft component 41 (shaft portion 44) and the heating element 35 are electrically connected.

  After the film-like heater 33 is wound as described above, the edges of the film-like heater 33 (portions of the joint 39) are melt-bonded using a method such as solder bonding. Accordingly, the film heater 33 can be reliably fixed so as not to be displaced on the base body 31. In addition, as shown in FIG. 7, when the edge part of the film-like heater 33 is processed so that the cross-sectional shape thereof is slanted and melt-bonded so that the edges are diagonally joined together, the strength of the joint part is increased. This is preferable in that the unevenness (step) of the joint 39 can be reduced.

  Further, a fluororesin layer such as a tetrafluoroethylene / perfluoroalkylvinyl copolymer is formed on the outer peripheral surface of the film heater 33 to form a release layer 37. The heat roller 52 can be manufactured by the above process.

  As shown in FIG. 8, the heat roller 52 manufactured in this way supports the shaft portion 44 with the bearing 56 and elastically contacts an appropriate terminal on the outer peripheral surface of the shaft portion 44 to perform contact power feeding. . Further, a gear (not shown) is fixed to the shaft portion 44 located at one end of the heat roller 52, and this gear and an output shaft of an electric motor (not shown) are connected via an appropriate drive transmission mechanism. . In this configuration, the electric motor is driven while applying a predetermined voltage to the heating element 35 of the film heater 33, so that the paper 100 is discharged from the discharge tray 80 at the nip portion between the press roller 53 and the heat roller 52. It can be heated and pressurized while being conveyed to the side.

  As described above, the heat roller 52 of the present embodiment includes the base body 31 having a cylindrical shape and electrical insulation, the film heater 33, and the release layer 37 having a high releasability with respect to the toner. And comprising. The film-like heater 33 is formed on one surface of the heat-resistant insulating layer 34 so as to have a pattern shape composed of a plurality of wires, and a heating element 35 that generates heat upon application of voltage, A heat transfer layer 36 formed in a planar shape on the other surface of the heat-resistant insulating layer 34. A film heater 33 is interposed between the outer peripheral surface of the base body 31 and the release layer 37, and the base body 31, the heating element 35, the heat-resistant insulating layer 34, the heat transfer layer 36, and the release layer 37. The mold layer 37 is laminated in this order outward in the radial direction.

  With the above configuration, since the heat source, that is, the film heater 33 is disposed near the roller surface, the temperature of the roller surface can be rapidly increased as compared with the halogen roller built-in type heat roller disclosed in Patent Document 1, and the warm Uptime can be significantly reduced. 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, since the heat transfer layer 36 is disposed radially outward from the heating element 35, the paper 100 in contact with the surface of the heat roller 52 can be heated uniformly, and uniform toner fixing can be realized and image quality can be improved. It can contribute to improvement.

  Further, since the base body 31 is configured to have a thermal conductivity smaller than that of the heat transfer layer 36, the heat of the heat generating body 35 can be prevented from escaping to the base body 31 on the inner peripheral side, and the heat roller 52. Can be efficiently heated. Furthermore, since the base body 31 is made of a synthetic resin, the base body 31 having the above thermal characteristics and electrical insulation can be easily molded and manufactured.

  In the heat roller 52 of the present embodiment, an adhesive layer 38 is interposed between the outer periphery of the base body 31 and the film heater 33. The adhesive layer 38 is made of silicone or polyimide and is configured to have appropriate elasticity. In other words, the adhesive layer 38 plays a role as an elastic body layer.

  Thus, the difference in thickness of the film heater 33 between the portion where the pattern of the heating element 35 is present and the portion where the pattern is not present can be absorbed by the elasticity of the adhesive layer 38, and unevenness on the surface of the heat roller 52 can be prevented. As a result, the sheet 100 uniformly contacts the surface of the heat roller 52, so that the toner can be fixed uniformly.

  Further, the film heater 33 is formed in an elongated shape as shown in FIG. 6, and the film heater 33 is attached so as to be spirally wound around the outer side of the base body 31.

  Thereby, the unevenness | corrugation (step) of the part of the seam 39 can be made small, and the heat roller 52 with a small unevenness | corrugation on the roller surface and few fixing nonuniformities can be provided.

  Further, the edges of the film heater 33 are melt-bonded to each other by solder.

  Thereby, the edges of the film heater 33 can be reliably joined at the joint 39.

  The effect of the configuration of the heat roller 52 is supported by the following experiment conducted by the inventors of the present application.

  That is, a configuration in which a non-woven fabric made of glass fiber is laminated as a heat-resistant and heat-insulating layer 32 on the outer peripheral surface of a base body 31 formed into a cylindrical shape using polyphenylene sulfide resin, and a film-like heater 33 is spirally wound around it. The heat roller 52 was prepared. In the film heater 33, a nickel chromium alloy was used as the heating element 35, a polyimide film was used as the heat-resistant insulating layer 34, and a copper foil was used as the heat transfer layer 36.

  A predetermined voltage was applied to the heat roller 52 having this configuration, and the time until the surface of the heat roller rose from room temperature to 180 ° C. was measured as a warm-up time. Then, it was found that the warm-up time of the heat roller 52 of this embodiment is shortened to about 1/7 as compared with the heat roller with a built-in halogen heater disclosed in Patent Document 1. Specifically, the warm-up time of the conventional heat roller was about 30 seconds, whereas the warm-up time of the heat roller 52 configured as described above was less than 4 seconds. Even when stainless steel was used as the heating element 35, good results similar to the above were obtained.

  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 in this way, 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.

  Next, the heat roller 52a of a 1st modification is demonstrated with reference to FIG. In the first modification, the same or similar parts as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted. The same applies to a second modification described later.

  In this modification, the base body 131 is formed in a cylindrical shape whose both axial ends are closed. A shaft portion 44 is fixed to each shaft end of the base body 131. The shaft portion 44 is made of a conductive material and is disposed on the same axis as the base body 131. The shaft portion 44 and the contact portion 40 of the film heater 33 are electrically connected by a conductor 45.

  The heat roller 52a according to the first modification has a configuration that does not have a large integrated body (having a large heat capacity) like the shaft component 41 of the above-described embodiment at the shaft end. Therefore, since the heat of the film heater 33 can be prevented from escaping to the shaft end side, uniform fixing and power saving by efficient heating can be realized.

  Further, a heat roller 52b of a second modification is shown in FIG. 10, and this heat roller 52b has a configuration in which the heater pattern of the heating element 35 is divided in the roller axial direction in the film heater 133. Specifically, the heater pattern of the heat generating element 35 is divided into two parts by an area (first area) A1 having a predetermined width on the axial center side and a remaining area (second area) A2. The heater patterns in the divided areas A1 and A2 are arranged so as to be electrically non-contact with each other.

  In addition, shaft portions 44 are fixed to both shaft ends of the base body 131, and the shaft portions 44 are disposed on the same axis as the base body 131. In the second modification, the shaft portion 44 is made of an electrically insulating material, for example, a synthetic resin.

  An annular first electrode 46 is provided on the outside (on the outer peripheral surface) of the shaft portion 44. Further, an annular second electrode 47 is also provided outside the first electrode 46, and an annular insulating cylinder (annular body) is provided between the annular portion of the first electrode 46 and the annular portion of the second electrode 47. ) 48 is interposed. The insulating cylinder 48 is made of a material having electrical insulation.

  Further, the heater pattern of the heating element 35 and the first electrode 46 in the first region A1 are electrically connected via the conductor 49, and the heater pattern and the second electrode 47 in the second region A2 are electrically connected. It is electrically connected via the body 50.

  The heat roller 52b of the second modification can control the region where the film heater 133 generates heat by switching the power supply to each of the first electrode 46 and the second electrode 47. As a specific example, when the width of the paper 100 exceeds the width of the first region A1, power is supplied to both the first electrode 46 and the second electrode 47, and both the two regions A1, A2 of the film heater 133 are supplied. Heat up. On the other hand, when the width of the paper 100 is equal to or less than the width of the first area A1, only the first electrode 46 is fed to generate heat, and power saving can be realized.

  As described above, the heat roller 52b of the second modified example is adjacent to the first region A1 and the first region A1 in the axial direction of the heat roller 52b in the heating element 35 of the film heater 133. 2nd area | region A2. And it is comprised so that 1st area | region A1 and 2nd area | region A2 may become electrically non-contact.

  Thereby, the heat_generation | fever area | region of the heat roller 52b can be switched according to a condition. Therefore, it is possible to realize power saving by controlling so as not to generate heat in an area through which the paper 100 does not pass.

  The heat roller 52b has a shaft portion 44 fixedly attached to the axial end of the base body 131 on the same axis, and a first electrode 46 is provided on the shaft portion 44. The heating element 35 is electrically connected to the first region A1. An annular second electrode 47 is disposed on the outer peripheral side of the first electrode 46, and the second electrode 47 is electrically connected to the second region A 2 of the heating element 35. Furthermore, an insulating cylinder 48 having electrical insulation is disposed between the first electrode 46 and the second electrode 47.

  Thereby, the electrodes for supplying power to the two regions of the heating element 35 can be arranged in a compact region around the shaft portion 44. Therefore, the structure for supplying power can be simplified, and the fixing device 51 and the copy facsimile multifunction machine 75 can be downsized.

  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.

  In addition, the base body 31 can be made of a material having high thermal conductivity. For example, a material such as AlN or SiC, or a metal such as aluminum can be used. However, from the viewpoint of power saving, the base body 31 is preferably made of a material having low thermal conductivity. When the base body 31 is made of a material having high heat conductivity as described above, it is extremely preferable to form the heat-resistant and heat-insulating layer 32 on the outer peripheral surface.

  Moreover, the base body 31 is not limited to the case where the whole has electrical insulation, and only the outer peripheral surface may have electrical insulation. For example, when the base body 31 is made of aluminum, it is conceivable that an appropriate electrical insulating layer is formed on the outer peripheral surface and the film heater 33 is disposed outside the electrical insulating layer.

  The pattern of the heating element (heating layer) 35 can be changed to another arbitrary pattern instead of the pattern shown in FIG.

  In the second modification of FIG. 10, the shaft portion 44 can be made of a conductive material, and the shaft portion 44 and the first region A <b> 1 can be electrically connected by a conductor 49. In this case, since the shaft portion 44 itself becomes the first electrode, the configuration can be simplified by omitting the annular first electrode 46.

  In the second modification of FIG. 10, the arrangement of the first area A1 and the second area A2 can be arbitrarily changed according to which part of the heat roller 52b the sheet with a small width passes through. Also, the heater pattern can be divided into three or more.

  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. Explanatory drawing which shows a mode that a shaft component is attached to the edge part of a base body. The perspective view which shows a mode that a film-like heater is wound around the base body. The cross-sectional enlarged view which shows a mode that a film-like heater is wound around the base body. The cross-sectional enlarged view which shows the heat roller of this embodiment. The cross-sectional enlarged view which shows the 1st modification of a heat roller. The cross-sectional enlarged view which shows the 2nd modification of a heat roller.

Explanation of symbols

31 Base body 32 Heat-resistant heat insulation layer (heat insulation layer)
33 Film heater (planar heating element)
34 Heat-resistant insulation layer (electrical insulation layer)
35 Heating element (heating layer)
36 Heat transfer layer 37 Release layer 38 Adhesive layer (elastic layer)
51 Fixing Device 52 Heat Roller 53 Press Roller 75 Copy Facsimile Multifunction Machine (Image Forming Device)
100 paper (recording medium)

Claims (10)

In a heat roller used in a fixing device for fixing toner on a recording medium,
A base body having a columnar shape or a cylindrical shape, at least an outer peripheral surface of which is electrically insulating;
An electric insulating layer, a heat generating layer formed on one surface of the electric insulating layer so as to have a pattern shape composed of a plurality of lines and generating heat upon application of a voltage, and the other surface of the electric insulating layer A sheet heating element including a heat transfer layer formed in a sheet shape;
A release layer having high releasability to the toner;
A shaft portion fixedly attached on the same axis to the axial end of the base body;
A first electrode provided on the shaft,
An annular second electrode disposed on the outer peripheral side of the first electrode;
An annular body interposed between the first electrode and the second electrode and having electrical insulation;
Including
The planar heating element is interposed between the outer peripheral surface of the base body and the release layer, and the base body, the heating layer, the electrical insulating layer, the heat transfer layer, and the separation layer. The mold layers are laminated in this order outward in the radial direction,
The heat generating layer includes at least a first region and a second region adjacent to the first region in the axial direction of the heat roller,
The first region and the second region are electrically non-contacting;
The first electrode is electrically connected to the first region of the heat generating layer;
The second electrode is electrically connected to the second region of the heat generating layer ;
The planar heating element is formed by a method in which the heat transfer layer is formed on the other surface of the electrical insulating layer, and then the heat generating layer is formed on the one surface of the electrical insulating layer. a heat roller in which the planar heating element thereby obtained is characterized Rukoto wound on the base body. The heat roller according to claim 1,
The heat roller, wherein the base body is configured to have a lower thermal conductivity than the heat transfer layer. The heat roller according to claim 2,
The heat roller, wherein the base body is made of synthetic resin. The heat roller according to any one of claims 1 to 3,
The heat roller further comprising an elastic layer interposed between an outer peripheral surface of the base body and the planar heating element. The heat roller according to any one of claims 1 to 4,
The heat roller further comprising a heat insulating layer interposed between the outer peripheral surface of the base body and the planar heating element. The heat roller according to any one of claims 1 to 5,
The sheet heating element is formed in an elongated sheet shape, and the sheet heating element is spirally wound around the outside of the base body. The heat roller according to any one of claims 1 to 6,
The sheet heating element is formed in a sheet shape, the sheet heating element is wound around the outside of the base body, and the edges are melt-bonded to each other by solder . A fixing device comprising: the heat roller according to claim 1; and a press roller that elastically contacts the outer peripheral surface of the heat roller. 9. The fixing device according to claim 8, 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 8 or 9.

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