JP2010286503A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably supply power to a shaft section of a heat roller that is rotated in a fixing device. <P>SOLUTION: Voltage application to a film state heater 32 is stable since the state of contact in other sets of outer shafts 40 of power supplying shafts 38, conductive spherical bodies 42 and electrode plates 44 is maintained even when a contact failure occurs due to unevenness in rotation or oscillation in one set of the outer shaft 40 of the power supplying shaft 38, the conductive spherical body 42 and the electrode plate 44 since there are four sets of the outer shafts 40 of the power supplying shafts 38, the conductive spherical bodies 42 and the electrode plates 44. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fixing device that fixes a toner image on a recording sheet by heating while feeding the recording sheet, and more particularly to a power feeding structure for applying a voltage to a heater of a heat roller.

  Patent Document 1 discloses a power feeding structure 103 for applying a voltage to a heat generating layer of a film-like heater 102 that is wound around and fixed to the outer peripheral surface of a base body 1 in a heat roller 104 of a fixing device. FIG. 10 shows the power feeding structure 103. In this power supply structure 103, a film-like heater 102 is wound around the outer periphery of a cylindrical base body 1, and a conductive flange portion 106 having a shaft portion 107 is attached to an opening end portion of the base body 1. The contact portion of the heating layer of the film heater 102 is in contact with the flange portion 106, and the movable terminal 108 pressed by the compression coil spring 109 is in contact with the side end surface of the shaft portion 107. Thus, a voltage can be applied from the DC power source 110 to the heat generating layer of the film heater 102 via the compression coil spring 109, the movable terminal 108, and the flange portion 106.

JP 2008-112052 A

  In the power supply structure 103 shown in FIG. 10, since the power supply contact is only at one place on the side end surface of the shaft portion 107, the movable terminal 108 and the shaft portion 107 are intermittently caused by uneven rotation and vibration of the heat roller 104. It has been experimentally confirmed by the inventor of the present application that temperature unevenness occurs in the rotational direction away from the toner, and as a result, fixing unevenness occurs in the toner image on the recording paper. Further, in the power supply structure 103, the movable terminal 108 and the shaft portion 107 are always in contact with each other in a surface contact state, so the movable terminal 108 is worn, which also prevents stable power supply and causes noise. It was.

  Accordingly, an object of the present invention is to stably supply power to a shaft portion of a heat roller that rotates in a fixing device.

  A preferred embodiment of the present invention relates to a fixing device that rotates about an axis and fixes a toner image on a recording sheet by heating while feeding the recording sheet. The fixing device includes a cylindrical body, a pair of bearings, a power feeding shaft, an annular holder, two or more conductive spheres, and two or more electrode plates. The cylindrical body opens at least at one end in the axial direction. At each end in the axial direction, the bearings of the pair of bearings abut against the outer peripheral surface of the cylindrical body, whereby the cylindrical body is rotatably supported about the axial line. The power feeding shaft has conductivity, is fixed to the opening end of the cylindrical body, and has a cylindrical outer shaft that protrudes outward in the axial direction from the end surface of the opening end. The heater is connected to the power supply shaft so as to be able to supply power, and heats the outer peripheral surface of the cylindrical body. The holder is disposed so as to surround the outer periphery of the outer shaft. Each of the two or more conductive spheres abuts on the outer peripheral surface of the outer shaft and is disposed at a predetermined interval in the circumferential direction. One end of each of the two or more electrode plates is disposed so as to protrude outward from the outer peripheral surface of the holder, and the other end is disposed within the annular ring of the holder, and each of the electrode plates is in contact with the conductive sphere. Thus, the conductive spheres are pressed against the outer periphery of the outer shaft.

  According to the preferred embodiment described above, the bearings are in contact with the outer peripheral surfaces of the axial ends of the cylindrical body, and the cylindrical body is firmly supported so as to be rotatable about the axial line. Is suppressed. In addition, each of the two or more conductive spheres arranged in the ring of the holder is arranged in the circumferential direction on the outer periphery of the conductive power supply shaft electrically connected to the heater. The electrode plates press the conductive spheres against the outer periphery of the outer shaft of the power supply shaft. Therefore, even if contact failure due to uneven rotation or vibration occurs in the outer shaft of one power supply shaft, conductive sphere, and electrode plate, the combination of the outer shaft of another power supply shaft, conductive sphere, and electrode plate Since the contact state is maintained, the power supply to the heater is stable. The conductive sphere is in contact with the outer shaft and the electrode plate, but rolls as the cylindrical body rotates, so that the wear of the outer shaft and the electrode plate is suppressed, and the noise is small.

  In a further preferred aspect of the present invention, each of the electrode plates has a hemispherical recess, and the conductive sphere is accommodated in the recess.

  According to the further preferable aspect described above, since the conductive sphere is accommodated in the hemispherical recess formed in the electrode plate, the conductive sphere rolls in the recess as the cylindrical body rotates. Therefore, wear of the outer shaft and the electrode plate is suppressed, and noise is also suppressed.

  In a further preferred aspect of the present invention, the heater is formed on one surface of the electrical insulation layer so as to have a heat-resistant electrical insulation layer and a pattern shape composed of a plurality of wires, and generates heat by being powered. And a heat generating layer.

  According to the further preferable aspect described above, since the film heater is employed as the heater, for example, the heater can be disposed on the outer peripheral surface or the inner peripheral surface of the cylindrical body, and the temperature of the outer peripheral surface of the cylindrical body is rapidly increased. Can be made.

  In a further preferred aspect of the present invention, the film heater is housed in an annular shape inside the cylindrical body with the electrical insulating layer disposed on the outer peripheral side. Then, the pressing member is housed inside the cylindrical body, and presses the film-shaped heater against the circumferential surface of the cylindrical body.

  According to the further preferable aspect described above, since the film heater is accommodated inside the cylindrical body, the pressing of the pressing member inside the cylindrical body is performed without adhering the film heater to the cylindrical body using an adhesive. The film heater can be pressed against the cylindrical body by pressure alone. And since the electrical insulation layer is arrange | positioned at the outer peripheral side, since a cylindrical body and a heat generating layer do not contact directly, aluminum and copper with good electrothermal efficiency can be employ | adopted as a raw material of a cylindrical body.

  In a further preferred aspect of the present invention, the power feeding shaft has an inner shaft that protrudes inward in the axial direction from the end surface of the opening end, and a power feeding portion of the heat generating layer of the film heater can feed power to the inner shaft. Fixed to.

  According to the above-mentioned more preferable aspect, since the power feeding portion of the heat generating layer of the film heater is connected to the inner shaft of the power feeding shaft, the connection portion that becomes hot when power is supplied is not exposed to the outside.

  In a further preferred aspect of the present invention, circumferential distances between the adjacent conductive spheres are equal to each other.

  According to the further preferable aspect described above, there is a set of an electrode plate, a conductive sphere, and a feed shaft that are always in contact with each other even if the cylindrical body is deviated from the axis in any direction in a plane area perpendicular to the axis direction. Therefore, stable power feeding is realized.

  According to the present invention, even if a contact failure occurs in the outer shaft of one power supply shaft, the conductive sphere, and the electrode plate, the contact between the outer shaft of the other power supply shaft, the conductive sphere, and the electrode plate is maintained. Therefore, the power supply to the heater is stable. The conductive sphere rolls as the cylindrical body rotates while in contact with the outer shaft and the electrode plate, so that wear of the outer shaft and the electrode plate is suppressed, and noise is also suppressed.

It is a disassembled perspective view of the heat roller of the fixing device of preferable embodiment of this invention. 1 is an external perspective view of an image forming apparatus including a fixing device according to a preferred embodiment of the present invention. 1 is a cross-sectional view of an image forming apparatus including a fixing device according to a preferred embodiment of the present invention. 1 is a cross-sectional view of a fixing device according to a preferred embodiment of the present invention. 1 is an external perspective view of a heat roller of a fixing device according to a preferred embodiment of the present invention. It is an axial sectional view of a heat roller of a fixing device of a preferred embodiment of the present invention. It is a side view of the heat roller of the fixing device of a preferred embodiment of the present invention. It is sectional drawing of a film-like heater. It is a top view of a film-like heater. FIG. 10 is a side sectional view of a heat roller of a conventional fixing device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a diagram showing an appearance of an image forming apparatus in which the fixing device according to each embodiment of the present invention is preferably provided, and FIG. 3 is a front sectional view of the image forming apparatus. FIG. 4 is a cross-sectional view showing only a common configuration in the fixing device of each embodiment of the present invention.

  As shown in the external perspective view of FIG. 2, a copy facsimile multifunction peripheral (hereinafter, multifunction peripheral) 75 as an image forming apparatus includes an image reading unit 76, an operation panel 77, a main body 78, and a paper feed cassette 79. The image reading unit 76 functions as a flat bed scanner and an auto document feed scanner. The operation panel 77 is used to instruct the number of copies, a facsimile transmission destination, and the like. The main body 78 includes an image forming unit that forms an image on a sheet as a recording medium, and includes a transmission / reception unit (not shown) for transmitting image data via a communication line. The paper feed cassette 79 sequentially supplies paper.

  FIG. 3 is a front sectional view of the multi-function device 75. A platen glass 82 is provided on the upper surface of the main body 78, and a document to be read is placed on the platen glass 82. Further, a document table cover 83 is provided above the main body 78, and the document table cover 83 presses the document on the platen glass 82 in a closed state.

  An automatic document feeder (auto document feeder, ADF) 84 is provided on the side of the document table cover 83, and the ADF 84 is connected to the document tray 85 and the discharge tray 86. The document tray 85 is provided above the document table cover 83, and the discharge tray 86 is provided below the document tray.

  A curved document transport path 87 that connects the document tray 85 and the discharge tray 86 is formed inside the ADF 84. A separation roller 88 and a plurality of transport rollers 89 are disposed on the document transport path 87. In this configuration, one sheet is separated from the bundle of documents set on the document tray 85, and the separated sheet is conveyed on the document conveyance path 87 and passes the document reading position with the small platen, and then the discharge tray 86. Discharged to the top.

  A scanner unit 90 is provided on the upper portion of the main body 78. The scanner unit 90 includes a light source 91, reflection mirrors 92, 93, 94, a condenser lens 95, and a charge coupled device (CCD) 96. The light source 91 irradiates light to the original reading position of the platen glass 82 or the ADF 84, and the reflection mirrors 92, 93, 94 reflect the reflected light from the original. The condensing lens 95 converges the reflected light, and the converged light is incident on the CCD 96 to form an image. The charge coupled device (CCD) 96 converts it into an electrical signal and outputs it. This electrical 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.

  A paper feed cassette 79 for supplying the paper 100 is provided at the lower part of the main body 78, and the paper feed cassette 79 can be pulled out to the front side of the apparatus (the front side in FIG. 2). Above the paper feed cassette 79, an image forming unit 11, a fixing device 51 and a paper discharge tray 80 according to a preferred embodiment of the present invention to be described later are provided.

  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 reaches on the paper tray 80.

  The paper feed roller 21 is disposed above the paper feed cassette 79, and this paper feed roller 21 contacts the uppermost paper 100 stacked in the paper feed cassette 79. In this state, when the paper feed roller 21 is driven, the uppermost sheet 100 is separated and picked up and sent out toward the transport path 24.

  In the transport path 24, transport rollers 22 and 23 are disposed immediately downstream of the paper feed roller 21. 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. 3, the image forming unit 11 includes a photosensitive drum 12 and a charger 13, an LED head 14, a developing device 15, and a transfer roller 16 disposed around the photosensitive drum 12.

  The photosensitive drum 12 has a photoconductive film formed of an organic photoreceptor on the surface, and is driven to rotate by an electric motor (not shown). The charger 13 employs 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 in the rotation direction of the photosensitive drum 12 and includes a large number of light emitting diodes (LEDs) 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 charge energy of the exposed portion disappears, whereby an electrostatic latent image is formed on the surface of the photosensitive drum 12.

  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 non-magnetic one-component toner. A stirring blade 27 that is rotationally driven is provided inside the toner container 26, and the stirring blade 27 stirs the toner. Further, the developing device 15 includes a supply roller 28, a developing roller 29, and a regulating blade 30. The supply roller 28, the development roller 20, and the regulation blade 30 are disposed inside the toner container 26, the development roller 29 contacts the supply roller 28, and the regulation blade 30 contacts the outer peripheral surface of the development roller 29.

  The supply roller 28 and the developing roller 29 rotate so as to rub the circumferential surfaces in opposite directions. Further, the tip of the regulating blade 30 rubs the peripheral surface of the rotating developing roller 29. 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 by the rotation of the developing roller 29. Thereafter, the toner on the surface of the developing roller 29 selectively moves to the surface of the photosensitive drum 12 only at the contact portion between the photosensitive drum 12 and the developing roller 29 only in the portion corresponding to the exposed portion of the photosensitive drum 12 by the LED head 14. To do. 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 is applied to the transfer roller 16 from a power source. Therefore, the toner image formed on the surface of the photosensitive drum 12 moves so as to approach the transfer roller 16 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, in a housing 55, a heat roller 52 that is powered by a motor (not shown) and is driven to rotate about an axis L1, and a press roller 53 that rotates in contact with the heat roller 52. . The press roller 53 is pressed against the heat roller 52 by an urging spring 58.

  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 on 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, and the separation claw 54 prevents the paper 100 from being wrapped around the heat roller 52.

  A paper discharge roller 25 is provided on the downstream side of the fixing device 51. The sheet 100 that has passed through 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.

  As shown in FIG. 4, the fixing device 51 includes a housing 55 that houses a heat roller 52 and a press roller 53. A heat roller 52 is rotatably supported on the housing 55 via a bearing 56 (see FIG. 1), and a press roller 53 is rotatably supported via a bearing 57.

  Hereinafter, the configuration of the heat roller 52 will be described with reference to FIGS. 1 and 5 to 9. FIG. 1 is an exploded perspective view of the heat roller 52, and FIG. 5 is an external perspective view of the heat roller 52. FIG. 6 is an axial cross-sectional view of the heat roller 52, and FIG. 7 is a side view of the heat roller 52. FIG. 8 is a cross-sectional view of the film heater 32, and FIG. 9 is a plan view of the film heater 32.

  As shown in the exploded perspective view of FIG. 1, the heat roller 52 includes a cylindrical body 31, a film heater 32, a pressing member 33, a flange member 34, a power supply shaft 38, a conductive sphere 42, a holder 43, and four conductive members. A spherical body 42, four electrode plates 44, a screw member 46 and a pair of bearings 56 are included. At each end in the direction of the axis L1, each bearing 56 abuts on the outer peripheral surface of the cylinder 31, so that the cylinder 31 is rotatably supported about the axis L1. As the bearing 56, a molding made of a rigid resin having high slidability and rigidity can be adopted. For example, a bearing made of a liquid crystal polymer is preferable.

  As the cylindrical body 31, a seamless pipe having a thickness of about 0.5 mm and a diameter of about 30 mm is preferably used. A release layer is formed on the outermost periphery of the cylindrical body 31. As the release layer, 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 is suitable.

  The film-like heater 32 is formed of a heat-resistant electric insulation layer 47 and a heat generation layer 48 which is laminated on one surface of the electric insulation layer 47 so as to have a pattern shape composed of a plurality of lines and generates heat when supplied with power. And. The heating element 48 can be made of, for example, stainless steel, a nickel alloy such as nickel chrome, nickel, or the like. The heating element 48 has a pattern shape in which a plurality of thin lines are arranged in parallel at equal intervals (heater pattern). 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 material of the heat-resistant insulating layer 47 is preferably a polyimide resin, a silicone resin, or the like, but is not limited thereto.

  The film-like heater 32 is rolled into an annular shape so that the electric insulating layer 47 is positioned on the outer peripheral side and is accommodated in the cylindrical body 31, and the cylindrical member 31 is accommodated in the cylindrical body 31 by the pressing member 33 accommodated in the cylindrical body 31. Pressed against the inner surface. Thus, it is not necessary to adhere the film heater 32 to the cylindrical body 31 using an adhesive. Since the electrical insulating layer 47 is arranged on the outer peripheral side, the cylindrical body 31 and the heat generating layer 48 are not in direct contact with each other, so that aluminum, stainless steel, or copper having good electrothermal efficiency is adopted as the material of the cylindrical body 31. Therefore, the heat generated in the heat generating layer 48 is quickly transferred to the cylindrical body 31, and the temperature of the outer peripheral surface of the heat roller 52 can be rapidly increased.

  As the pressing member 33, a solid columnar body or a hollow cylindrical body made of silicon rubber having heat resistance characteristics can be suitably employed. In this embodiment, an example adopted by the former is shown. The holding member 33 is prepared so that the outer diameter thereof is the same as or slightly smaller than the inner diameter of the cylindrical body 31, and is pushed into the inside from the open end of the cylindrical body 31. In addition, the pressing member may be one in which an aramid felt having high heat resistance is wound around and fixed to the outer periphery of a hollow pipe made of aluminum or a rigid resin.

  The flange member 34 is a substantially cylindrical member, and is integrally formed of a rigid resin (for example, polyphenylene sulfide (PPS)) having excellent heat resistance and high rigidity. The flange member 34 includes a flange main body 34A, an insertion portion 35 projecting a predetermined length from the inner side surface of the flange main body 34A, and an accommodation recess 36 drilled a predetermined length from the outer side surface of the flange main body 34A. And is configured. The flange main body 34 </ b> A has an outer diameter substantially equal to the outer diameter of the cylindrical body 31, and the insertion portion 35 has an outer diameter substantially equal to the inner diameter of the cylindrical body 31. The receiving recess 36 has a diameter substantially equal to the outer diameter of the flange 39 of the power supply shaft 38 to be described later, and is provided with a predetermined distance on the inner side in the axis L1 direction. The flange member 34 is formed with a through hole 37 extending along the axis L1. The insertion portion 35 of the flange member 34 having such a configuration is inserted from the opening end of the cylindrical body 31, and the flange member 34 is fixed to the cylindrical body 31.

  The feeding shaft 38 includes a disk-shaped flange 39, a cylindrical outer shaft 40 projecting outward from the outer surface of the flange 39 in the direction of the axis L1 (to the right in FIG. 6), and the flange 30 And an inner shaft 41 projecting inward (leftward in FIG. 6) from the inner side surface in the axis L1 direction. The flange 39, the outer shaft 40, and the inner shaft 41 are integrally formed of a mold using iron, copper, or brass as a material and the axis L1 as a common axis. The inner shaft 41 of the power supply shaft 38 is inserted into the through hole 37 so that the end surface thereof protrudes slightly from the inner end surface of the flange member 34. The flange portion 36 of the power supply shaft 38 is tightly inserted into the housing recess 36 in the flange portion 34, and the power supply shaft 38 is attached to the flange member 34 so as not to be relatively rotatable.

  Further, a screw hole 59 parallel to the axis L1 is formed in the inner shaft 41 of the power supply shaft 38 from the inner end surface thereof. As shown in FIG. 9, the insulating layer 47 of the film-like heater 32 has an extending portion 60 extending from a part of its end surface, and is continuous with the pattern wiring portion of the heat generating layer 48 on the extending portion 60. A power feeding portion 49 is formed, and a hole 50 is punched in the extending portion 60 and the power feeding portion 49. Then, in a state where the power feeding portion 49 and the inner end surface of the inner shaft 41 are in surface contact, the screw hole 59 of the inner shaft 41 and the hole of the extending portion 60 are aligned, and the screw member 46 as a fixture is screwed into the screw hole 46. The heat generating layer 48 of the film heater 32 and the power supply shaft 38 are connected so as to be able to supply power. And this connection location is arrange | positioned inside the cylindrical body 31, and is not exposed outside.

  Each of the conductive spheres 42 is a sphere having a diameter of about 5 mm, and is made of a conductive metal such as iron, aluminum, copper, or brass.

  The holder 43 is an annular member, and is resin-molded with a highly rigid resin material (for example, polyphenylene sulfide (PPS)). In the annular portion of the holder 43, four through grooves that penetrate in the thickness direction are formed at equal intervals in the circumferential direction.

  In a state where one end of the electrode plate 44 is exposed to the outside of the holder 43, a rectangular plate-like metal electrode plate 44 is inserted into each through groove. The other end of the electrode plate 44 is inserted into an insertion groove formed on the inner peripheral surface of the holder 43, and the electrode plate 44 is held by the holder 43. The outer shaft 40 of the power feeding shaft 38 is inserted into the holder 43 with both axes aligned with L1. A portion of each electrode plate 44 disposed in the holder 43 is formed with a hemispherical storage recess 45 that opens and faces the axis L1, and the conductive sphere 42 is stored in the storage recess 45, and the adjacent conductive portions The circumferential distances between the spheres 42 are arranged equally. The housed conductive sphere 42 is pressed against the outer peripheral surface of the outer shaft 40 by the spring force of the electrode plate 44. The electrode plate 44, the conductive sphere 42, and the power supply shaft 38 are connected so as to be conductive, and one end of the electrode plate 44 is connected to a power source (not shown), so that the electrode plate 44, the conductive sphere 42, and the power supply shaft 38 are connected from the power source. The voltage can be applied to the heat generating layer 48 of the film heater 32 via the. In addition, you may apply | coat conductive grease between the accommodation recessed part 45 and the conductive sphere 42, and may improve both sliding.

  According to the power supply structure described above, there are four sets of the outer shaft 40, the conductive sphere 42, and the electrode plate 44 of the power supply shaft 38. Therefore, even if the outer shaft 40, the conductive sphere 42, and the electrode of one power supply shaft 38 are provided. Even if contact failure occurs due to rotation unevenness or vibration in the set of plates 44, the contact state of the set of the outer shaft 40, the conductive sphere 42 and the electrode plate 44 of the other power supply shaft 38 is maintained. The voltage application to 32 is stable. The conductive sphere 42 is in contact with the outer shaft 40 and the electrode plate 44 but rolls in the hemispherical storage recess 45 as the cylindrical body 31 rotates, so that the outer shaft 40 and the electrode plate 44 are worn away. It is suppressed and noise is low.

  Although the embodiments described above are suitable for carrying out the present invention, the present invention can also be carried out in the embodiments described below. That is, the film heater 32 is changed to a configuration in which the film heater 32 is disposed inside the cylindrical body 31, and the film heater 32 is wound around and fixed to the outer periphery of the cylindrical body 31. In this case, the film heater 32 is wound around the cylindrical body 31 so that the electrical insulating layer 47 is in contact with the outer periphery of the cylindrical body 31, and an electrical insulating layer and a soaking layer are prepared on the outer peripheral side of the heat generating layer 48. A release layer is disposed on the outer peripheral side of the thermal layer. Then, the power feeding portion 49 on the extending portion 60 of the film heater 32 is brought into contact with the outer surface of the flange 39 of the power feeding shaft 38 in the direction of the axis L1 to fix the extending portion 60 to the power feeding shaft 38. Even in this embodiment, although the connecting portion between the heat generating layer 48 and the power supply shaft 38 is exposed to the outside, the effect of suppressing the generation of the stability of voltage application and the generation of wear and noise is achieved.

31 Cylindrical body 32 Film-like heater 33 Holding member 38 Feed shaft 42 Conductive sphere 43 Holder 44 Electrode plate 46 Screw member (fixing tool)
51 Fixing Device 52 Heat Roller 56 Bearing

Claims (6)

A fixing device that rotates about an axis and fixes the toner image on the recording paper by heating while feeding the recording paper,
A cylindrical body that is open at least at one end in the axial direction;
At each end in the axial direction, a pair of bearings that rotatably support the cylindrical body about the axial line by causing each bearing to contact the outer peripheral surface of the cylindrical body;
A feeding shaft having conductivity, having a cylindrical outer shaft that is fixed to the opening end of the cylindrical body and protrudes outward in the axial direction from the end surface of the opening end;
A heater connected to the power supply shaft so as to be able to supply power, and heating the outer peripheral surface of the cylindrical body;
An annular holder disposed around the outer periphery of the outer shaft;
Each of the conductive spheres abuts on the outer peripheral surface of the outer shaft, and two or more conductive spheres arranged in the circumferential direction at a predetermined interval; and
One end of each electrode plate is disposed so as to protrude outward from the outer peripheral surface of the holder, and the other end is disposed in an annular shape of the holder, and each of the electrode plates contacts each of the conductive spheres. A fixing device including two or more electrode plates that press against the outer periphery of the outer shaft. The fixing device according to claim 1,
Each of the electrode plates has a hemispherical recess, and the conductive sphere is accommodated in the recess. The fixing device according to claim 1 or 2,
The heater is composed of a heat-resistant electric insulating layer and a heat generating layer that is formed on one surface of the electric insulating layer so as to have a pattern shape composed of a plurality of lines and generates heat when supplied with power. A fixing device characterized by being a film-like heater. The fixing device according to claim 3.
The film heater is disposed in an annular shape inside the cylindrical body with the electrical insulating layer disposed on the outer peripheral side,
The fixing device further comprising a pressing member that is housed inside the cylindrical body and that presses the film-like heater against a circumferential surface of the cylindrical body. The fixing device according to claim 4.
The power supply shaft has an inner shaft that protrudes inward in the axial direction from the end surface of the opening end,
A fixing device, wherein a power feeding portion of a heat generating layer of the film heater is fixed to the inner shaft so as to be capable of feeding power. In the fixing device according to any one of claims 1 to 5,
A fixing device characterized in that circumferential distances between adjacent conductive spheres are equal to each other.