Heating device, fixing device, and image formation apparatus

Abstract

To suppress inclination of a first holding member.SOLUTION: A heating device comprises a contact-type thermistor having a heat-sensitive element 271, a thermistor holder 29, a heater holder 25 that holds the thermistor holder 29, and a harness 270 that extends in a direction X. The thermistor holder 29 has a support portion 29b that extends in a direction Z, a supported portion 29c that extends in a direction Y, and contact ribs 29a1, 29a2 that contact the heater holder 25 in the direction Y. The support portion 29b supports one side in the direction Y of the supported portion 29c. The thermistor holder 29 has a wiring space 29d that opens toward the other side in the direction Y and is used to route the harness 270 in the direction X on the side of the support portion 29b relative to the supported portion 29c. When a distance in the direction Z toward the side of the supported portion 29c from a reference surface 29h on which an end on the opposite side to the supported portion 29c in the direction Z of the support portion 29b is provided is defined as a height, a contact height A2 between the ribs 29a1, 29a2 and the heater holder 25 is higher than a height A1 of the wiring space 29d.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a heating device, a fixing device, and an image forming apparatus.

Background Art

[0002] In a fixing device as a heating device, in order to appropriately control the temperature of a fixing belt (rotating member), a temperature detection member is provided that contacts a temperature detection element with a heating element or the like in the fixing device to detect the temperature.

[0003] As such a fixing device, for example, the fixing device of Patent Document 1 (Japanese Patent Application Laid-Open No. 2014-186308) has a sensor holding member 501 that holds a temperature sensor 500. The biasing force of a biasing member 503 provided between the sensor holding member 501 and the temperature sensor 500 biases the temperature sensor 500 via the sensor holding member 501 and presses it against a heater 504. Thereby, the temperature sensor 500 detects the temperature of the heater 504. Further, the heater holding member 505 that holds the heater 504 has plate-like protrusions 505a and 505b provided with groove-shaped positioning portions 505a1 and 505b1. The sensor holding member 501 is positioned in the vertical direction in FIG. 40 by engaging the engaging portions 501a and 501b with the positioning portions 505a1 and 505b1. The cable of the temperature sensor 500 is passed between the plate-like protrusions 505a and 505b in a direction perpendicular to the paper surface of FIG. 40.

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a configuration in which a wiring space for passing an electric wire is provided in a first holding member that holds a contact type temperature detection member, in order to pass the electric wire through the wiring space, it has a cantilever structure in which one side in the third direction of the wiring space is opened. However, in such a configuration, when a force is applied to the first holding member, the first holding member is likely to tilt in the third direction. As a result, the temperature detection member also tilts and the temperature detection member does not appropriately contact the member to be abutted, which causes a problem of adversely affecting the detection accuracy.

[0005] In the present invention, an object is to suppress the inclination of a first holding member.

Means for Solving the Problem

[0006] To solve the above problems, the present invention provides a heating device including a rotating member, a contact-type temperature detecting member having a temperature detecting portion, a first holding member that holds the temperature detecting member, a second holding member that holds the first holding member, and an electric wire extending in a first direction. The temperature detecting member is biased toward the detected member. When a direction intersecting the first direction in the direction in which the temperature detecting member is biased and the opposite direction is defined as a second direction, and a direction intersecting the second direction in a direction orthogonal to the first direction is defined as a third direction, the first holding member includes a support portion extending in the second direction, a supported portion extending in the third direction, and a contact portion that contacts the second holding member from one side or the other side in the third direction. The support portion supports one side of the supported portion in the third direction. The first holding member has a wiring space for wiring the electric wire in the first direction, and is open to the other side in the third direction on the side of the support portion in the second direction rather than the supported portion. When a surface on which an end portion on the opposite side of the supported portion in the second direction of the support portion is provided is defined as a reference surface, and a distance in the second direction from the reference surface toward the supported portion is defined as a height, the contact height between the contact portion and the second holding member is provided higher than the height of the wiring space.

Effect of the Invention

[0007] In the present invention, the inclination of the first holding member can be suppressed.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and the redundant description thereof will be simplified or omitted as appropriate. Hereinafter, as a heating device according to an embodiment of the present invention, a fixing device provided in an image forming apparatus will be described.

[0010] <Overall Configuration of Image Forming Apparatus> FIG. 1 is a schematic configuration diagram of an image forming apparatus 1000 according to a first embodiment of the present invention. Here, the "image forming apparatus" in this specification includes a printer, a copier, a facsimile machine, a printing machine, or a multifunction machine that combines two or more of these. Further, the "image formation" used in the following description means not only forming an image having meanings such as characters and figures, but also forming an image having no meaning such as a pattern. First, with reference to FIG. 1, the overall configuration and operation of the image forming apparatus according to the first embodiment of the present invention will be described.

[0011] As shown in FIG. 1, the image forming apparatus 1000 according to the first embodiment of the present invention includes an image forming unit 100, a fixing unit 200, a sheet feeding unit 300, and a sheet discharging unit 400.

[0012] (Image Forming Unit) The image forming unit 100 is a part that forms an image on a sheet as a recording medium. The image forming unit 100 includes four image forming units 1Y, 1M, 1C, 1Bk, an exposure device 6, and a transfer device 8.

[0013] The four image forming units 1Y, 1M, 1C, 1Bk each include an electrostatic latent image carrier 2, a charging member 3, a developing device 4, and a cleaning member 5.

[0014] The electrostatic latent image carrier 2 is a rotating body that carries an electrostatic latent image on its surface. As the electrostatic latent image carrier 2, for example, in addition to a photosensitive drum, an endless photosensitive belt or the like is used.

[0015] The charging member 3 is a member that charges the surface of the electrostatic latent image carrier 2. The charging member 3 is not particularly limited as long as it can apply a voltage to the surface of the electrostatic latent image carrier 2 to uniformly charge it, and can be appropriately selected according to the purpose. Specifically, in addition to contact charging members such as conductive or semiconductive charging rollers, magnetic brushes, fur brushes, films, and rubber blades, non-contact charging members using corona discharge are included.

[0016] The developing device 4 is a device that supplies toner as a developer to the electrostatic latent image on the electrostatic latent image carrier 2 to form a toner image. The developing device 4 accommodates different color toners (developers) such as yellow, magenta, cyan, and black corresponding to the color separation components of the color image for each image forming unit 1Y, 1M, 1C, 1Bk.

[0017] The cleaning member 5 is a member that removes toner and other foreign substances remaining on the electrostatic latent image carrier 2. As the cleaning member 5, a cleaning blade arranged to contact the surface of the electrostatic latent image carrier 2 is used.

[0018] The exposure device 6 is a device that exposes the charged surface of the electrostatic latent image carrier 2 to form an electrostatic latent image. The exposure device 6 is not particularly limited as long as it can expose the charged surface of the electrostatic latent image carrier 2, and can be appropriately selected according to the purpose. Specifically, various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, a liquid crystal shutter optical system, and an LED optical system are included.

[0019] The transfer device 8 is a device that transfers an image onto a sheet. The transfer device 8 includes an intermediate transfer belt 11, a primary transfer roller 12, and a secondary transfer roller 13. The intermediate transfer belt 11 is an endless belt member and is stretched by a plurality of support rollers. Four primary transfer rollers 12 are provided inside the intermediate transfer belt 11. When each primary transfer roller 12 contacts each electrostatic latent image carrier 2 via the intermediate transfer belt 11, a primary transfer nip is formed between the intermediate transfer belt 11 and each electrostatic latent image carrier 2. On the other hand, the secondary transfer roller 13 contacts the outer peripheral surface of the intermediate transfer belt 11. Thereby, a secondary transfer nip is formed between the secondary transfer roller 13 and the intermediate transfer belt 11.

[0020] (Fixing unit) The fixing unit 200 has a fixing device 20 that heats the sheet to fix the image on the sheet. The fixing device 20 includes a pair of rotating bodies 19A, 19B that contact each other, and a heater or the like that heats at least one of the pair of rotating bodies 19A, 19B.

[0021] (Sheet supply unit) The sheet supply unit 300 is a part that supplies the sheet to the image forming unit 100. The sheet supply unit 300 includes a paper feed cassette 14 that houses the paper P as a sheet, and a paper feed roller 15 that feeds out the paper P from the paper feed cassette 14. Note that the "sheet" includes, in addition to paper, OHP sheets, cloth, metal sheets, plastic films, or prepreg sheets in which carbon fibers are impregnated with resin in advance. Also, the "paper" includes, in addition to plain paper, cardboard, postcards, envelopes, thin paper, coated paper (such as coated paper and art paper), tracing paper, and the like.

[0022] (Sheet discharge unit) The sheet discharge unit 400 is a part that discharges the paper P outside the apparatus. The sheet discharge unit 400 includes a pair of paper discharge rollers 17 that discharge the paper P, and a paper discharge tray 18 on which the paper P discharged by the paper discharge rollers 17 is placed.

[0023] <Image forming operation> Next, while referring to FIG. 1, the operation of the image forming apparatus 1000 according to the first embodiment of the present invention will be described.

[0024] When the image forming operation is started according to an instruction from the operation panel or an external terminal, the rotation of the electrostatic latent image carriers 2 is started in each image forming unit 1Y, 1M, 1C, 1Bk. Next, each charging member 3 charges the surface of each electrostatic latent image carrier 2 to a uniform high potential. Subsequently, based on the image information of the document read by the document reading apparatus or the print image information instructed from an external terminal, the exposure device 6 exposes the surface (charged surface) of each electrostatic latent image carrier 2. As a result, the potential of the exposed portion decreases and an electrostatic latent image is formed on the surface of each electrostatic latent image carrier 2. Thereafter, toner is supplied from each developing device 4 to each electrostatic latent image carrier 2, whereby toner images of different colors are formed on each electrostatic latent image carrier 2.

[0025] The toner images on each electrostatic latent image carrier 2 reach the primary transfer nip (the position of the primary transfer roller 12) as the electrostatic latent image carrier 2 rotates. Then, at the primary transfer nip, the toner images are sequentially transferred onto the intermediate transfer belt 11 that is rotationally driven from each electrostatic latent image carrier 2 so as to overlap. Thus, a full-color toner image is formed on the intermediate transfer belt 11. Note that the image formation is not limited to the case of forming a full-color image using all four image forming units 1Y, 1M, 1C, 1Bk. It is also possible to form a monochromatic image using any one of the image forming units 1Y, 1M, 1C, 1Bk, or to form a two-color or three-color image using any two or three of the image forming units. Further, after the toner image is transferred to the intermediate transfer belt 11, a cleaning operation of the electrostatic latent image carrier 2 by the cleaning member 5 is performed. As a result, foreign substances such as residual toner are removed from the surface of each electrostatic latent image carrier 2.

[0026] The toner image transferred onto the intermediate transfer belt 11 is conveyed to the secondary transfer nip (position of the secondary transfer roller 13) as the intermediate transfer belt 11 rotates. Then, at the secondary transfer nip, the toner image is transferred from the intermediate transfer belt 11 onto the sheet P. This sheet P is supplied from the sheet supply unit 300. After the start of the image forming operation, the sheet P is fed out from the paper feed cassette 14 by the rotation of the paper feed roller 15. The fed-out sheet P contacts the timing roller pair 16 on the way to the secondary transfer nip, and the conveyance is temporarily stopped. Then, when the timing roller pair 16 rotates at a predetermined timing, the sheet P is conveyed to the secondary transfer nip in synchronization with the toner image on the intermediate transfer belt 11, and the toner image is transferred onto the sheet P.

[0027] The sheet P onto which the toner image has been transferred is conveyed to the fixing unit 200. In the fixing unit 200, as the sheet P passes between the pair of rotating members 19A and 19B, the toner image on the sheet P is heated and pressed, and the toner image is fixed to the sheet P. Then, the sheet P is conveyed to the sheet discharge unit 400 and discharged to the paper discharge tray 18 by the paper discharge roller 17. Thereby, a series of image forming operations is completed.

[0028] <Configuration of the fixing device> FIG. 2 is a schematic configuration diagram of the fixing device 20 according to the first embodiment of the present invention. In FIG. 2, the thermistor holder 29 and the structure around it are described in a simplified manner.

[0029] As shown in FIG. 2, the fixing device 20 includes, in addition to the pair of rotating members 19A and 19B, a heater 23 as a heating body, a heat sink plate 24 as a high heat conduction member, a heater holder 25 as a second holding member, a stay 26 as a support member, a thermistor 27 as a temperature detecting member, a thermistor holder 29 as a first holding member, and the like.

[0030] Of the pair of rotators 19A and 19B, one first rotator 19A is a fixing belt 21 disposed on the unfixed image-carrying surface side of the sheet P. The other second rotator 19B is a pressure roller 22 disposed to face the fixing belt 21. The fixing belt 21 and the pressure roller 22 are pressed against each other by a pressing member such as a spring so as to be in contact with each other. Thereby, a nip portion N is formed between the fixing belt 21 and the pressure roller 22.

[0031] The direction orthogonal to the plane of FIG. 2 (direction X in FIG. 3) is the longitudinal direction of the fixing belt 21, the pressure roller 22, the heater 23, the soaking plate 24, the heater holder 25, the stay 26, the thermistor 27, the thermistor holder 29, and the fixing device 20, and is also the first direction of the present embodiment. Hereinafter, this direction will also be simply referred to as the longitudinal direction. Note that this longitudinal direction is also the belt width direction of the fixing belt 21 or the axial direction of the pressure roller 22, and is also the width direction of the conveyed sheet. The width direction of the sheet is the direction orthogonal to the sheet conveyance direction and the thickness direction. The direction Y in FIG. 2 is the short-side direction of the heater 23, the soaking plate 24, the thermistor 27, the thermistor holder 29, etc., the sheet conveyance direction, and the opposite direction thereof, and is the third direction of the present embodiment. The direction Z in FIG. 2 is the thickness direction of the heater 23, the soaking plate 24, etc., or the direction in which the thermistor 27 is biased, and is the second direction of the present embodiment. The directions X, Y, and Z are orthogonal to each other.

[0032] The fixing belt 21 is composed of a cylindrical base material and an endless belt member having a release layer provided on the outer peripheral surface of the base material. The base material is formed of, for example, a metal material such as nickel or stainless steel, or a resin material such as polyimide. The release layer is formed of, for example, a material such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PTFE (polytetrafluoroethylene), polyimide, polyetherimide, or PES (polyether sulfide). By having the release layer, the separability of the toner image with respect to the fixing belt 21 is improved, and the winding of the paper P around the fixing belt 21 is suppressed. Further, the fixing belt 21 may have an elastic layer between the base material and the release layer. As the material of the elastic layer, for example, rubber materials such as silicone rubber, foamed silicone rubber, and fluororubber are used. When the fixing belt 21 has an elastic layer, it becomes difficult to form minute irregularities on the surface of the fixing belt 21, so that heat is easily transmitted uniformly to the toner image on the paper P, and the fixing quality is improved.

[0033] The pressure roller 22 is composed of a hollow or solid core material, an elastic layer provided on the outer peripheral surface of the core material, and a roller having a release layer provided on the outer peripheral surface of the elastic layer. The core material is formed of a metal material such as iron. As the material of the elastic layer, silicone rubber, foamed silicone rubber, fluororubber, etc. are used. The release layer is formed of a fluororesin such as PFA or PTFE.

[0034] The heater 23 is arranged so as to contact the inner peripheral surface of the fixing belt 21 at the nip portion N. Further, by sandwiching the fixing belt 21 between the heater 23 and the pressure roller 22, the fixing belt 21 is pressurized, and a nip portion N is formed between the fixing belt 21 and the pressure roller 22. Further, in addition to the case where the heater 23 directly contacts the inner peripheral surface of the fixing belt 21, the heater 23 may contact via a low-friction sliding sheet. In the present specification, "contact" includes not only direct contact in which contact is made without passing through other members, but also indirect contact in which contact is made through other members, unless otherwise specified.

[0035] The heater 23 has a base material 50, a resistance heating element 51, an insulating layer 52, etc. The resistance heating element 51 is provided on the base material 50 and is covered by the insulating layer 52. When the resistance heating element 51 generates heat by energization, the heat is transmitted to the inner peripheral surface of the fixing belt 21 through the insulating layer 52, and the fixing belt 21 is heated. Also, the orientation of the heater 23 may be changed so that the base material 50 is arranged to contact the inner peripheral surface of the fixing belt 21. In that case, since the heat of the resistance heating element 51 is transmitted to the fixing belt 21 through the base material 50, the base material 50 is preferably formed of a material having a high thermal conductivity.

[0036] The base material 50 is formed of a non-metallic material such as ceramic, glass, or mica, such as alumina or aluminum nitride, which is excellent in heat resistance and insulation. Also, by interposing a separate insulating layer between the base material 50 and the resistance heating element 51, it is possible to form the base material 50 of a conductive material such as metal. As the metal material, aluminum or stainless steel, etc. are preferable in terms of low cost. Also, in order to suppress temperature unevenness of the heater 23 and improve image quality, the base material 50 may be formed of a material having a high thermal conductivity, such as copper, graphite, or graphene. Graphene is a sheet-like substance formed by bonding carbon atoms.

[0037] The resistance heating element 51 is formed by a method such as screen printing. For example, a paste prepared by mixing silver palladium (AgPd) and glass powder, etc. is applied to the base material 50 by screen printing, and then the base material 50 is fired to form the resistance heating element 51. Also, as the material of the resistance heating element 51, in addition to silver palladium, a resistance material such as a silver alloy (AgPt) or ruthenium oxide (RuO2) may be used. The insulating layer 52 is formed of, for example, heat-resistant glass or the like.

[0038] The heat spreader 24 is a member that assists in the transfer of heat emitted from the heater 23. The heat spreader 24 is formed of a material having a higher thermal conductivity than that of the heater holder 25 or the like. The material of the heat spreader 24 is copper, aluminum, graphene, or the like. As an example, an aluminum plate having a thickness of 0.3 mm can be mentioned. The heat spreader 24 is arranged to contact the surface 23b on the side opposite to the rotating body contact surface 23a that contacts the inner peripheral surface of the fixing belt 21 of the heater 23. Note that the heat spreader 24 is not limited to a single-layer member and may be constituted by a plurality of layers of members.

[0039] In particular, in the first embodiment of the present invention, since the heat spreader 24 is arranged to be in direct contact with the heater 23, the heat of the heater 23 can be effectively dispersed by the heat spreader 24. Generally, in a non-passing region where the sheet P does not pass, the heat of the nip portion N is hardly consumed. Therefore, when a sheet P having a width smaller than the heat generating region of the heater 23 is continuously passed, there is a risk that the temperatures of the fixing belt 21 and the heater 23 in the non-passing region will rise excessively. However, in the first embodiment of the present invention, since the heat spreader 24 is provided, the heat of the nip portion N in the non-passing region can be dispersed to the surroundings via the heat spreader 24. Thereby, a local temperature rise of the fixing belt 21 and the heater 23 can be suppressed. In addition, since the heat of the nip portion N in the non-passing region can be moved to the passing region through which the sheet P passes, it can be effectively utilized as the heat for the fixing process, and an improvement in energy saving can also be expected.

[0040] The heater holder 25 is a member that holds the heater 23 and the heat sink 24. The heater holder 25 has a recess 25a for accommodating the heater 23 and the heat sink 24. When the heater 23 and the heat sink 24 are accommodated in the recess 25a of the heater holder 25, the movement of the heater 23 and the heat sink 24 in the vertical direction and the direction perpendicular to the paper surface in FIG. 2 is restricted. Since the heater holder 25 tends to become hot due to the heat of the heater 23, it is preferably formed of a heat-resistant material. In particular, when the heater holder 25 is formed of a heat-resistant resin with low thermal conductivity such as LCP, unnecessary heat transfer from the heater 23 to the heater holder 25 is suppressed, and the heating efficiency of the heater 23 is increased.

[0041] Also, a through hole 25b penetrating to the back side is provided in a partial region of the recess 25a of the heater holder 25. The thermistor 27 contacts the back surface 24b of the heat sink 24 through the through hole 25b.

[0042] The stay 26 is a support member that supports the heater holder 25. By the stay 26 supporting the heater holder 25 from the side opposite to the pressure roller 22 side, the deflection of the heater 23 due to the pressing force of the pressure roller 22 is suppressed, and a nip portion N with a uniform width can be obtained. As the material of the stay 26, in order to ensure rigidity, an iron-based metal material such as SUS or SECC is preferable.

[0043] <Operation of the fixing device> The fixing device 20 according to the first embodiment of the present invention operates as follows.

[0044] When the image forming operation is started, the pressure roller 22 starts to rotate in the direction of the arrow in FIG. 2, and accordingly, the fixing belt 21 rotates in a driven manner. Also, when energization to the heater 23 is started, the fixing belt 21 is heated. Then, when the temperature of the fixing belt 21 reaches a predetermined target temperature, the paper P carrying the unfixed image is conveyed to the nip portion N between the fixing belt 21 and the pressure roller 22. Thereby, the toner image on the paper P is heated and pressed and fixed to the paper P. Thereafter, the paper P is discharged from the nip portion N and conveyed to the sheet discharge portion 400.

[0045] <Configuration of the Heater> FIG. 3 is a plan view of the heater 23 according to the first embodiment of the present invention.

[0046] As shown in FIG. 3, the heater 23 according to the first embodiment of the present invention is a planar or plate-shaped heater that extends long in the X direction in the figure. The heater 23 is disposed within the fixing belt 21 such that its longitudinal direction X is along the longitudinal direction of the fixing belt 21. Here, the "longitudinal direction of the fixing belt 21" means a direction orthogonal to the rotation direction of the fixing belt 21 along the outer peripheral surface of the fixing belt 21. The heater 23 has a longitudinal base material 50, a resistance heating element 51, an insulating layer 52, an electrode portion 53, and a power supply line 54.

[0047] A plurality of resistance heating elements 51 are arranged at intervals along the longitudinal direction of the base material 50. The gap between adjacent resistance heating elements 51 is preferably 0.2 mm or more, more preferably 0.4 mm or more, from the viewpoint of ensuring the insulation between the resistance heating elements 51. However, if the gap between the resistance heating elements 51 is too large, temperature drop is likely to occur in the gap portion. Therefore, from the viewpoint of suppressing temperature unevenness along the longitudinal direction, it is preferably 5 mm or less, more preferably 1 mm or less. Each resistance heating element 51 is connected to a pair of electrode portions 53 via a power supply line 54. In the example shown in FIG. 3, the pair of electrode portions 53 are provided at both ends in the longitudinal direction of the base material 50, and each resistance heating element 51 is electrically connected in parallel to each electrode portion 53. Note that the arrangement, number, shape, etc. of each of the resistance heating element 51, the electrode portion 53, and the power supply line 54 are not limited to the example shown in FIG. 3 and can be changed as appropriate.

[0048] The electrode part 53 and the power supply line 54 are provided on the same surface as the surface on which the resistance heating element 51 of the base material 50 is provided. The power supply line 54 is covered by an insulating layer 52 in the same manner as the resistance heating element 51 in order to ensure insulation and durability. On the other hand, since a connector as a power supply member is connected to the electrode part 53, it is not covered by the insulating layer 52 and is exposed. When a connector is connected to each electrode part 53, each resistance heating element 51 and the power supply are electrically connected, so that power can be supplied from the power supply to each resistance heating element 51.

[0049] <Temperature control mechanism> FIG. 4 is a block diagram of the temperature control mechanism of the heater 23 according to the first embodiment of the present invention.

[0050] As shown in FIG. 4, the fixing device 20 according to the first embodiment of the present invention includes a thermistor 27, a thermostat 28, a triac 10, and a control unit 7 as a temperature control mechanism for controlling the temperature of the heater 23.

[0051] The thermistor 27 is a temperature sensor for temperature control provided to maintain the temperature of the heater 23 at a predetermined temperature. On the other hand, unlike the thermistor 27, the thermostat 28 is a temperature sensor for preventing overheating provided to prevent abnormal temperature rise of the heater 23. In the first embodiment of the present invention, the thermistor 27 is disposed at the longitudinal center and one longitudinal end side of the heating region H of the heater 23, and the thermostat 28 is disposed at the other longitudinal end side opposite to the one longitudinal end side of the heating region H. Note that the arrangement and number of the thermistor 27 and the thermostat 28 are not limited to the example of FIG. 4 and can be changed as appropriate.

[0052] Each thermistor 27 contacts the heat sink 24 and detects the temperature of the heater 23 through the heat sink 24. On the other hand, the thermostat 28 directly contacts the back surface 23a of the heater 23 through the hole 24a of the heat sink 24. Thereby, the responsiveness of the thermostat 28 to the temperature change of the heater 23 can be enhanced. When the thermostat 28 detects an abnormal temperature rise of the heater 23, the thermostat 28 operates and the power supply to the heater 23 is cut off. However, the thermostat 28 may be configured to contact the heat sink 24 in the same manner as the thermistor 27.

[0053] The triac 10 is a power supply control means for controlling the power supply duty from the AC power supply 30 to the heater 23 according to the instruction of the control unit 7. The "power supply duty" means the ratio of the power supply time to the heater 23 per control cycle. The control unit 7 is composed of a microcomputer including a CPU, a ROM, a RAM, an I / O interface, etc. By outputting a control signal for controlling the triac 10 based on the detected temperature of each thermistor 27, the triac 10 controls the power supply duty based on the control signal, and the temperature of the heater 23 is maintained to be a predetermined target temperature.

[0054] Next, the configurations of the heater holder 25, the thermistor 27, and the thermistor holder 29 will be described in more detail.

[0055] FIG. 5 is a cross-sectional view in a cross-section orthogonal to the longitudinal direction, showing a cross-sectional view of the heater holder 25, the thermistor 27, the thermistor holder 29, etc. at the longitudinal position where the heat-sensitive element 271 of the thermistor 27 is arranged, and is a cross-sectional view seen from the right direction of FIG. 8.

[0056] As shown in Fig. 5, the thermistor holder 29 is assembled to the heater holder 25 and holds the thermistor 27 from the side opposite to the heater 23 (the upper side in Fig. 5). The thermistor holder 29 is biased toward the heater 23 by a biasing spring 31 as a biasing member. Due to this biasing force, the thermistor holder 29 presses (biases) the thermistor 27 in the direction of arrow B, and the heat-sensitive element 271 of the thermistor 27 is pressed against the heat sink plate 24 via the insulating sheet 272. The heat sink plate 24 of the present embodiment is a member to be detected that is contacted by the thermistor 27 to detect its temperature. In other words, the thermistor 27 can indirectly detect the temperature of the heater 23 and the fixing belt by contacting the heat sink plate 24 and detecting its temperature. However, the heater 23 and the fixing belt may be members to be detected that are directly contacted by the thermistor 27 to detect their temperatures.

[0057] The heat-sensitive element 271 is attached to the base portion 273 via an elastic body 275. The elastic body 275 has a curved surface shape protruding toward the heater 23 side, and the heat-sensitive element 271 is held at the top portion of this curved surface, that is, the portion that protrudes most toward the heater 23 side of the elastic body 275.

[0058] Fig. 6 is a view showing the thermistor 27, where (a) is a plan view, (b) is a rear view, and (c) is a side view.

[0059] As shown in Fig. 6(a), the thermistor 27 includes a heat-sensitive element 271 as a temperature detection portion, an insulating sheet 272 as an insulating portion, a base portion 273, a harness 274, an elastic body 275, and the like.

[0060] The base portion 273 holds the heat-sensitive element 271 via the elastic body 275. An insulating sheet 272 is wound around the portion of the base portion 273 that holds the heat-sensitive element 271, and the insulating sheet 272 covers the surface of the heat-sensitive element 271. The elastic body 275 of the present embodiment is a sponge.

[0061] As shown in FIG. 6(b), the base portion 273 has a positioning cylinder portion 273a. The positioning cylinder portion 273a has a cylindrical shape with a hole extending in the Z direction inside. One end portion 273b in the longitudinal direction of the thermistor 27 has a substantially T-shaped configuration having a first protruding portion 273b1 and a second protruding portion 273b2 protruding outward in the Y direction on both sides in the Y direction. A harness 274 is connected to the other end portion 273c of the base portion 273. The harness 274 is fixed to the base portion 273 by, for example, soldering.

[0062] As shown in FIG. 6(c), the base portion 273 is pressed in the direction of arrow B via the thermistor holder by the biasing force of the biasing spring. Thereby, the heat-sensitive element 271 is pressed against the heat sink through the insulating sheet 272.

[0063] FIG. 7 is a perspective view showing the back surface of the heater holder 25, that is, the surface on the side where the thermistor 27 is attached. As shown in FIG. 7, the heater holder 25 has a pair of positioning ribs 25c1, 25c2 and a positioning pin 25d. The positioning ribs 25c1, 25c2 and the positioning pin 25d extend to the back surface side in the Z direction (the upper side in FIG. 5).

[0064] FIG. 8 is a view showing a state in which the thermistor 27 is attached to the back surface side of the heater holder 25. As shown in FIG. 8, one end portion 273b of the base portion 273 of the thermistor 27 is inserted and fitted between a pair of positioning ribs 25c1, 25c2 provided on the heater holder 25. Further, the positioning pin 25d (see FIG. 7) is inserted into the hole inside the positioning cylinder portion 273a of the thermistor 27, and the thermistor 27 is positioned on the heater holder 25. The thermistor 27 is positioned with a slight play with respect to the heater holder 25. Thereby, when the thermistor 27 is pressed by the thermistor holder, it can move in the direction of the heat sink, and the heat-sensitive element of the thermistor 27 can be appropriately brought into contact with the heat sink. The width C1 in the short direction between the positioning ribs 25c is provided slightly larger than the width C2 (see FIG. 6b) on the other end side of the base portion 273.

[0065] Next, the configuration of the thermistor holder 29 will be described with reference to the perspective view of FIG. 9. As shown in FIG. 9, at one end 29a of the thermistor holder 29, a pair of abutting ribs 29a1 and 29a2 protruding in the thickness direction are provided. The pair of abutting ribs 29a1 and 29a2 are arranged at intervals in the short side direction.

[0066] The thermistor holder 29 also has a support portion 29b (see FIG. 5) and a supported portion 29c. As shown in FIG. 5, the support portion 29b refers to the portion extending in the Z direction of FIG. 5 among the substantially L-shaped portions of FIG. 5, and the supported portion 29c refers to the portion extending in the Y direction of FIG. 5. In other words, the support portion 29b supports a portion on one side in the Y direction (the right side in FIG. 5) of the supported portion 29c. The one side in the Y direction of the supported portion 29c is, for example, a portion within one side region when the supported portion 29c is bisected in the Y direction. In particular, in this embodiment, the support portion 29b supports one end portion of the supported portion 29c in the Y direction.

[0067] A wiring space 29d, which is a space for wiring the harness 270, is provided on the side of the support portion 29b below the supported portion 29c. The wiring space 29d is open toward the other side in the Y direction. In other words, the thermistor holder 29 has a cantilever structure in which the supported portion 29c is supported only by the support portion 29b provided only on one side in the short side direction thereof. The harness 270 extends in the direction X within the wiring space 29d. The harness 270 is, for example, a harness of a thermistor different from the thermistor 27 held by the thermistor holder 29 of FIG. 9.

[0068] As shown in FIG. 9, a biasing member attachment portion 29g is provided on the upper portion of the supported portion 29c. As shown in FIG. 5, one end of the biasing spring 31 is attached to the upper portion of the biasing member attachment portion 29g.

[0069] FIG. 10 is a perspective view of the back side in a state where the thermistor holder 29 is attached to the heater holder 25, and FIG. 11 is a rear view thereof.

[0070] As shown in FIGS. 10 and 11, one longitudinal end portion 29a, which is a fitting portion of the thermistor holder 29, fits between a pair of positioning ribs 25c1 and 25c2 of the heater holder 25. At this time, the contact rib 29a1 of the thermistor holder 29 contacts the positioning rib 25c1 of the heater holder 25, and the contact rib 29a2 contacts the positioning rib 25c2. In this way, the contact rib 29a1 is a first contact portion that contacts one side in the Y direction with respect to the positioning rib 25c1, which is the first contacted portion, and the contact rib 29a2 is a second contact portion that contacts the other side in the Y direction with respect to the positioning rib 25c2, which is the second contacted portion. Note that the contact ribs 29a1 and 29a2 of the present embodiment are substantially L-shaped having a portion extending in the X direction and a portion extending in the Y direction, but it is the portion extending in the X direction that contacts the positioning ribs 25c1 and 25c2 in the Y direction, and the contact ribs 29a1 and 29a2 may be provided only with this portion. In FIG. 5, for convenience, only the portion of the contact ribs 29a1 and 29a2 extending in the X direction is shown.

[0071] Further, the positioning cylinder portion 273a of the thermistor 27 is inserted into the positioning hole 29f of the thermistor holder 29, and the thermistor 27 is positioned with respect to the thermistor holder 29. In this way, the positioning hole 29f and the positioning cylinder portion 273a are positioning portions of the thermistor holder 29 and the thermistor 27.

[0072] As shown in FIG. 11, the width C5 in the short side direction of the positioning hole 29f is provided larger than the outer diameter C4 of the positioning cylinder portion 273a, and the thermistor 27 has a play that allows relative movement in the short side direction with respect to the thermistor holder 29 by a length of C5 - C4. Further, the width C3 of one end portion 29a of the thermistor holder 29 is provided smaller than the distance C1 (see FIG. 8) between the positioning ribs 25c1 and 25c2, and the thermistor holder 29 has a play that allows relative movement in the short side direction with respect to the heater holder 25 by a length of C1 - C3. In this way, one end portion 29a of the thermistor holder 29 and the portions of the positioning ribs 25c1 and 25c2 of the heater holder 25 are positioning portions of the two.

[0073] In this embodiment, C5 - C4 > C3 - C1. As a result, the play in the short - hand direction of the thermistor holder 29 with respect to the heater holder 25 is provided to be smaller than the play in the short - hand direction between the thermistor holder 29 and the thermistor 27. Thus, even if the thermistor holder 29 moves in the short - hand direction with respect to the heater holder 25, the end face forming the positioning hole 29f of the thermistor holder 29 does not interfere with the positioning cylinder portion 273a of the thermistor 27 in the short - hand direction. Therefore, when the thermistor holder 29 presses the thermistor 27 in the direction of arrow B in FIG. 5, it does not prevent the movement of the thermistor 27 in this direction, and the heat - sensitive element can be properly brought into contact with the heat - sink plate.

[0074] Also, the harness 270 is routed in the longitudinal direction and passes through the wiring space below the support portion 29 of the thermistor holder 29 in the X - direction in the middle. Passing through in this X - direction does not mean that the harness 270 is strictly routed parallel to the X - direction. The harness 270 may meander as shown in FIG. 11.

[0075] In such a fixing device, there is a problem that the misalignment of the thermistor holder 29 has an adverse effect on the detection accuracy of the thermistor 27. That is, as shown in FIG. 5, the thermistor holder 29 has a cantilever structure having a wiring space 29d that opens to the other side in the short - hand direction. Also, as described above, the thermistor holder 29 has play in the short - hand direction with respect to the heater holder 25. For this reason, when a force is applied to the thermistor holder 29, the thermistor holder 29 is likely to tilt in the short - hand direction. And since the heat - sensitive element 271 of the thermistor 27 is provided at the top of the curved elastic body 275, when the thermistor 27 tilts due to the tilt of the thermistor holder 29 in the short - hand direction, the tilt of the heat - sensitive element 271 also becomes large. As a result, the thermistor 27 does not properly contact the heat - sink plate 24, and the thermistor 27 cannot properly detect the temperature of the heater 23 through the heat - sink plate 24.

[0076] In contrast, in the present embodiment, in a direction intersecting the short side direction (particularly a perpendicular direction in the present embodiment), contact ribs 29a1 and 29a2 extending in the direction of arrow B in FIG. 5 (hereinafter also simply referred to as the pressing direction), which is the direction in which the thermistor holder 29 presses the thermistor 27, are brought into contact with positioning ribs 25c1 and 25c2 extending in the same direction of the heater holder 25. Thereby, even if the thermistor holder 29 has play in the short side direction with respect to the heater holder 25, the play of the thermistor holder 29 can be minimized, and as a result, the heat-sensitive element 271 of the thermistor 27 can be appropriately brought into contact with the heat sink 24. Thereby, the thermistor 27 can accurately detect the temperature of the heat sink 24. Note that the fact that the contact ribs 29a1 and 29a2 and the positioning ribs 25c1 and 25c2 extend in the direction in which the thermistor holder 29 presses the thermistor 27 does not mean only the case where the contact ribs 29a1 and 29a2 or the positioning ribs 25c1 and 25c2 extend in a direction strictly parallel to this direction, and of course, some error is acceptable.

[0077] Particularly in the present embodiment, as shown in FIG. 5, the contact height A2 between the positioning ribs 25c1 and 25c2 and the contact ribs 29a1 and 29a2 for suppressing play in the short side direction is made higher than the height A1 of the wiring space 29d, which is the space for wiring the harness 270. Thereby, when attempting to wire the harness 270 in the wiring space 29d by routing the harness 270, even if a force is applied from the harness 270 to the thermistor holder 29, the positioning ribs 25c1 and 2 and the contact ribs 29a1 and 29a2 are in contact at a position higher than that, and the inclination of the thermistor holder 29 in the short side direction can be suppressed. Therefore, the heat-sensitive element 271 can be appropriately brought into contact with the heat sink 24, and the thermistor 27 can accurately detect the temperature of the heater 23.

[0078] Note that the above height refers to the distance in the Z direction from the reference plane 29h where the support portion 29b of the thermistor holder 29 is provided, toward the supported portion 29c. The height A1 refers to the distance to the highest position of the wiring space 29d, and in this embodiment, it refers to the height to the lower surface 29c1 of the supported portion 29c. The contact height A2 refers to the height to the highest position among the portions where the positioning ribs 25c1, 25c2 and the contact ribs 29a1, 29a2 are in contact. When there are irregularities on the reference plane 29h, for example, it is the distance from the lowest position of the reference plane 29h (the position farthest from the supported portion 29c in the Z direction). In this case, the height A1 may be set from this position by extending a perpendicular line in the Z direction to the position where it contacts the lower surface 29c1 of the supported portion 29c. Also, it is not limited to the case of using the height from the reference plane 29h. For example, the surface 23a (the heating surface on the fixing belt side) on the side of the heater 23 (heating element) opposite to the thermistor 27 may be used as the reference plane, and the height from this reference plane may be used. Also, when the direction from the support portion 29b in the Z direction toward the supported portion 29c (the direction from the bottom to the top in FIG. 5) is defined as the height in the Z direction, it can be determined whether the contact height is higher than the wiring space by whether the position where the contact portion of the thermistor holder 29 (first holding member) contacts the heater holder 25 (second holding member) is higher than the highest position of the lower surface 29c1 of the supported portion 29c.

[0079] Also, this contact height A2 refers to the contact height of the contact rib 29a1, which is the closest to the support portion 29b in the Y direction among the contact portions of the thermistor holder 29 (first holding member) that contact the heater holder 25 (second holding member) in the Y direction. However, as in this embodiment, a plurality of contact portions may be provided. In this case, it is preferable to provide the second contact portion on the open side of the wiring space 29d, that is, on the side closest to the end portion opposite to the support portion 29b side of the supported portion 29c in the Y direction, and it is more suitable to arrange it like the contact rib 29a2 in this embodiment.

[0080] Also, the thermistor holder 29 is held by the heater holder 25 with play in the Y direction with respect to the heater holder 25. For this reason, the contact ribs 29a1 and 29a2 of the thermistor holder 29 do not necessarily contact the positioning ribs 25c1 and 25c2 in their assembled state. That is, the contact portion of the first holding member is provided so as to be able to contact the second holding member when the first holding member is moved by the amount of play in the Y direction with respect to the second holding member. Also, the contact height of the contact portion is the height at which the contact portion contacts the second holding member when the first holding member is moved toward the second holding member by the amount of play in the Y direction. When the contact portion is not in contact with the second holding member, the first holding member moves by the amount of play in the Y direction with respect to the second holding member, so that the contact portion contacts the second holding member, and further movement of the first holding member with respect to the second holding member can be restricted.

[0081] As in this embodiment, by bringing the contact ribs 29a1 and 29a2 into contact with the positioning ribs 25c1 and 25c2 respectively, that is, by providing a portion that contacts one side in the short side direction and a portion that contacts the other side respectively, it is possible to suppress the inclination of the thermistor holder 29 on both sides in the short side direction, which is preferable. However, a configuration in which the contact portion contacts the contacted portion only in one direction in the short side direction may also be used.

[0082] In this embodiment, one end portion 29a of the thermistor holder 29 having the contact ribs 29a1 and 29a2 is fitted between the positioning ribs 25c1 and 25c2. That is, the portion of the thermistor holder 29 provided with the contact portion is used as a fitting portion with respect to the heater holder 25. Thereby, the contact portion can be accurately brought into contact with the contacted portion. However, a configuration in which the contact ribs 29a1 and 29a2 simply contact the heater holder 25 in the short side direction to suppress the inclination of the thermistor holder 29 in the short side direction may also be used.

[0083] In the above description, the thermistor holder 29 that holds one thermistor 27 has been described. However, the other thermistor 27 can also adopt a configuration in which it is held by the above thermistor holder 29. At this time, as shown in FIG. 12, in the supported portion 29c provided on one thermistor holder 29A and the supported portion 29c provided on the other thermistor holder 29B, it is preferable that the opening direction in the short side direction of the wiring space 29d at the lower part of the supported portion 29c is in the opposite direction. Thereby, it is possible to suppress the harness 270 from coming off from the wiring space below the supported portion 29c.

[0084] As shown in FIG. 9, on the side opposite to the side having the contact ribs a1 and 29a2 in the longitudinal direction of the thermistor holder 29 of the above embodiment (the left side in FIG. 9), there are a pair of contact ribs 29e1 and 29e2 as contact portions that contact the heater holder 25 in the short side direction. The contact ribs 29e1 and 29e2 extend in the Y direction, similar to the contact ribs 29a1 and 29a2. As shown in FIGS. 10 and 11, the contact ribs 29e1 and 29e2 contact the contacted ribs 25e1 and 25e2 of the heater holder 25 in the X direction. However, the contact ribs 29e1 and 29e2 can also be provided in a shape similar to the contact ribs 29a1 and 29a2 and configured to contact the contacted ribs 25e1 and 25e2 in the Y direction. In this way, by making the portions extending in the pressing direction of the thermistor holder 29 contact the portions extending in the pressing direction of the heater holder 25 on both sides in the longitudinal direction, the inclination of the thermistor holder 29 in the short side direction can be further suppressed. However, it is not always necessary to provide such a contact structure on both sides in the longitudinal direction, and it may be provided only on one side in the longitudinal direction or only at the center in the longitudinal direction. Note that providing the contact ribs 29a1 and 29a2 on one side in the longitudinal direction of the thermistor holder 29 and the contact ribs 29e1 and 29e2 on the other side means, for example, providing the contact ribs 29a1 and 29a2 in one region when the thermistor holder 29 is bisected in the longitudinal direction and providing the contact ribs 29e1 and 29e2 in the other region.

[0085] As described above, the embodiments of the present invention have been explained. However, the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[0086] Note that the resistance heating element 51 is not limited to being rectangular as shown in FIG. 3, and may be parallelogram-shaped as shown in FIG. 13, or a folded shape as shown in FIG. 14. Further, as shown in FIG. 13 or FIG. 14, the pair of electrode portions 53 may be provided at either one end of the base material 50 in the longitudinal direction X of the heater 23.

[0087] Further, the present invention is also suitable for a configuration including a fixing belt 21 having no elastic layer as shown in FIG. 15. The fixing belt 21 shown in FIG. 15 has no elastic layer such as a rubber layer between the surface layer (release layer) 212 and the base material 210. Therefore, compared with a fixing belt having an elastic layer, the heat insulation property is low and the heat conductivity from the heater to the surface (outer peripheral surface) of the fixing belt is good. However, on the other hand, the temperature rise of the fixing belt 21 in the non-paper passing region tends to be remarkable. For this reason, it is important to appropriately perform temperature management of the fixing belt 21 by appropriately detecting the temperature with a thermistor, and it is preferable to apply the heater holder 25, the thermistor 27, and the thermistor holder 29 of the above-described embodiment.

[0088] Further, the present invention is applicable not only to the fixing device 20 shown in FIG. 2 but also to the fixing devices having the respective configurations shown in FIGS. 16 to 18. Hereinafter, the fixing devices having the respective configurations shown in FIGS. 16 to 18 will be described. In FIGS. 16 to 18, portions having the same components as those of the fixing device 20 shown in FIG. 2 are denoted by the same reference numerals as those in FIG. 2, and the description thereof will be omitted.

[0089] In the fixing device 20 shown in FIG. 16, the nip portion N1 for heating and the nip portion N2 for fixing are formed at different positions. Specifically, the large and small pressure rollers 151 and 152 contact the fixing belt 21 from opposite sides, thereby forming the nip portion N1 for heating and the nip portion N2 for fixing. That is, the left pressure roller 151 in FIG. 16 contacts the heater 23 via the fixing belt 21 to form the nip portion N1 for heating, and the right pressure roller 152 in FIG. 16 contacts the nip forming member 150 via the fixing belt 21 to form the nip portion N2 for fixing. In this case, when the heater 23 generates heat, the fixing belt 21 is heated in the nip portion N1 for heating. Further, when the paper P enters the nip portion N2 for fixing, the unfixed image on the paper P is heated and pressed, and the image is fixed on the paper P.

[0090] Subsequently, the example shown in FIG. 17 is an example in which the left pressure roller 151 in FIG. 16 is omitted and the heater 23 is formed in an arc shape according to the curvature of the fixing belt 21. Otherwise, the configuration is the same as that of the fixing device 20 shown in FIG. 16. In this case, since the heater 23 is formed in an arc shape, a long contact area between the fixing belt 21 and the heater 23 in the belt rotation direction is ensured, so that the fixing belt 21 is efficiently heated.

[0091] Subsequently, the example shown in FIG. 18 is an example in which a pair of belts 161 and 162 are arranged on both sides of the central roller 163. In this case, the left belt 161 in FIG. 18 is sandwiched between the heater 23 disposed inside thereof and the central roller 163 to form the nip portion N1 for heating. Further, the right belt 162 in FIG. 18 is sandwiched between the nip forming member 153 disposed inside thereof and the central roller 163 to form the nip portion N2 for fixing. In this case, when the heater 23 generates heat, the central roller 163 is heated in the nip portion N1 for heating. Further, when the paper P enters the nip portion N2 for fixing, the unfixed image on the paper P is heated and pressed, and the image is fixed on the paper P.

[0092] In the fixing device shown in FIGS. 16 to 18 above, the configurations of the heater holder 25, the thermistor 27, and the thermistor holder 29 of the foregoing embodiment can also be applied. Thereby, the inclination of the thermistor holder 29 can be suppressed, and the detection accuracy of the thermistor 27 can be maintained with high precision.

[0093] Subsequently, the fixing device 20 shown in FIG. 19 includes an IH (electromagnetic induction heating) heater 63 as means for heating the fixing belt 21. In addition to the IH heater 63, the fixing device 20 includes a fixing belt 21, a pressure roller 22, a stay 26, a thermistor holder 29, a nip forming member 62, a sliding sheet 61, a thermistor 27, a separation plate 64A and separation claws 64B as separation members 64, and the like.

[0094] The IH heater 63 is disposed outside the fixing belt 21 and fixed to the main body of the image forming apparatus. The IH heater 63 includes a coil 632, cores 633, 634, 635, and a coil holder 631. The coil holder 631 holds the coil 632. When power is supplied to the coil 632, a magnetic field is formed around the coil 632, and eddy currents are generated in the metal belt base material of the fixing belt 21. Then, when eddy currents are generated, Joule heat is generated due to the electrical resistance of the belt base material, and the fixing belt 21 generates heat. The cores 633, 634, 635 are formed of a ferromagnetic material and form a magnetic path through which the magnetic field (magnetic flux) generated from the coil 632 passes.

[0095] The thermistor 27 contacts the inner peripheral surface of the fixing belt 21 and detects the temperature of the fixing belt 21.

[0096] The nip forming member 62 contacts the pressure roller 22 via the fixing belt 21 and forms a fixing nip N between the fixing belt 21 and the pressure roller 22. A sliding sheet 61 containing a lubricant is provided between the fixing belt 21 and the nip forming member 62. By interposing the sliding sheet 61 and the lubricant between the fixing belt 21 and the nip forming member 62, the sliding resistance between the fixing belt 21 and the nip forming member 62 is reduced.

[0097] The stay 26 is a holding member that holds the thermistor 27 and the thermistor holder 29 in addition to the nip forming member 62. The stay 26 has a holder portion 26a that holds the thermistor holder 29 and the thermistor 27.

[0098] In the fixing device shown in FIG. 19 above, the thermistor 27 and the thermistor holder 29 of the above-described embodiment are applied, and the portion (see FIG. 7) of the above-described heater holder that holds the thermistor holder 29 can be applied to the holder portion 26a of the stay 26. Thereby, the inclination of the thermistor holder 29 can be suppressed, and the detection accuracy of the thermistor 27 can be maintained with high precision. However, the thermistor 27 of the present embodiment is different from the above-described embodiment in that it abuts on the inner peripheral surface of the fixing belt 21 via the stay 26 and detects its temperature.

[0099] Subsequently, the fixing device 20 shown in FIG. 20 includes a halogen heater 65 as means for heating the fixing belt 21. Further, the fixing device 20 includes, in addition to the halogen heater 65, a fixing belt 21, a pressure roller 22, a stay 26, a nip forming member 66, a reflecting member 67, a thermistor 27, a thermistor holder 29, and the like.

[0100] The nip forming member 66 contacts the pressure roller 22 via the fixing belt 21 and forms a fixing nip N between the fixing belt 21 and the pressure roller 22. In this case, since the halogen heater 65 is disposed so as to face the nip forming member 66 inside the fixing belt 21, the infrared light emitted from the halogen heater 65 is irradiated onto the nip forming member 66. Thereby, the nip forming member 66 is heated, and the heat of the nip forming member 66 is transmitted to the fixing belt 21 at the position of the nip portion N, and the fixing belt 21 is heated. The nip forming member 66 is preferably formed of a material having a higher thermal conductivity than the stay 26 so that heat can be efficiently transferred to the fixing belt 21. Examples of the material of the nip forming member 66 include copper and aluminum.

[0101] Also, a part of the infrared light radiated from the halogen heater 65 is reflected by the reflecting member 67 disposed within the fixing belt 21 toward the nip forming member 66. Thereby, the nip forming member 66 is effectively heated. Further, since the reflecting member 67 is interposed between the stay 26 and the halogen heater 65, irradiation of infrared rays and heat transfer from the halogen heater 65 to the stay 26 are suppressed, and thus an energy saving effect is also obtained.

[0102] The thermistor 27 contacts the inner peripheral surface of the fixing belt 21 and detects the temperature of the fixing belt 21.

[0103] The stay 26 is a holding member that holds the thermistor 27 and the thermistor holder 29 in addition to the nip forming member 66 and the reflecting member 67. The stay 26 has a holder portion 26a that holds the thermistor holder 29 and the thermistor 27.

[0104] In the fixing device shown in FIG. 20 above, the thermistor 27 and the thermistor holder 29 of the foregoing embodiment are applied, and the portion (see FIG. 7) of the heater holder that holds the thermistor holder 29 of the foregoing can be applied to the holder portion 26a of the stay 26. Thereby, the inclination of the thermistor holder 29 can be suppressed, and the detection accuracy of the thermistor 27 can be maintained with high precision.

[0105] Further, the image forming apparatus according to the present invention is applicable not only to the image forming apparatus shown in FIG. 1 but also to an image forming apparatus 100 as shown in FIG. 21. Hereinafter, the configuration of another image forming apparatus to which the present invention is applicable will be described.

[0106] The image forming apparatus 100 shown in FIG. 21 includes an image forming unit 80 including a photosensitive drum and the like, a paper conveyance unit including a pair of timing rollers 81 and the like, a paper feeding device 82, a fixing device 83, a paper discharging device 84, and a reading unit 85. The paper feeding device 82 includes a plurality of paper feeding trays, and each paper feeding tray accommodates papers of different sizes.

[0107] The reading unit 85 reads the image of the document Q. The reading unit 85 generates image data from the read image. The paper feeding device 82 accommodates a plurality of sheets P and sends out the sheet P to the conveyance path. The timing roller 81 conveys the sheet P on the conveyance path to the image forming means 80.

[0108] The image forming means 80 forms a toner image on the sheet P. Specifically, the image forming means 80 includes a photosensitive drum, a charging roller, an exposure device, a developing device, a replenishing device, a transfer roller, a cleaning device, and a discharging device. The fixing device 83 heats and presses the toner image to fix the toner image on the sheet P. The sheet P on which the toner image is fixed is conveyed to the paper discharging device 84 by a conveyance roller or the like. The paper discharging device 84 discharges the sheet P to the outside of the image forming apparatus 100.

[0109] Next, based on FIG. 22, the configuration of the fixing device 83 shown in FIG. 21 will be described. In FIG. 22, the parts having the same configuration as those of the fixing device 20 shown in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

[0110] The fixing device 83 shown in FIG. 22 includes a fixing belt 21, a pressure roller 22, a heater 23, a heat equalizing plate 24, a heater holder 25, a stay 26, a thermistor 27, a thermistor holder 29, and the like.

[0111] A nip portion N is formed between the fixing belt 21 and the pressure roller 22. The nip width of the nip portion N is 10 mm, and the linear speed of the fixing device 83 is 240 mm / s.

[0112] The fixing belt 21 includes a polyimide substrate and a release layer, and does not have an elastic layer. The release layer is formed of a heat-resistant film material made of, for example, a fluororesin. The outer diameter of the fixing belt 21 is about 24 mm.

[0113] The pressure roller 22 includes a core metal, an elastic layer, and a release layer. The outer diameter of the pressure roller 22 is 24 to 30 mm, and the thickness of the elastic layer is 3 to 4 mm.

[0114] The heater 23 includes a base material, a heat insulating layer, a conductive layer including a resistance heating element, and an insulating layer, and has an overall thickness of 1 mm. The width of the heater 23 in the paper transport direction is 13 mm.

[0115] A heat equalizing plate 24 made of a highly heat conductive material is disposed so as to come into contact with the surface of the heater 23 opposite to the surface that comes into contact with the inner circumferential surface of the fixing belt 21. The heater 23 and the heat equalizing plate 24 are held by a heater holder 25. The heater holder 25 is supported by a stay 26.

[0116] 22, the configurations of heater holder 25, thermistor 27, and thermistor holder 29 of the above-described embodiment can be applied. This makes it possible to suppress tilting of thermistor holder 29 and maintain high detection accuracy of thermistor 27.

[0117] 23, the conductor layer of the heater 23 includes a plurality of resistance heating elements 51, a power supply line 54, and electrode portions 53A to 53C. The plurality of resistance heating elements 51 are arranged at intervals in the longitudinal direction X of the heater 23. Here, if the portions between the respective resistance heating elements 51 are referred to as "divided regions," then, as shown in the enlarged view of FIG. 23, divided regions D are formed between the respective resistance heating elements 51 (although FIG. 23 only illustrates the divided regions D within the enlarged view, in reality, divided regions D are provided between all of the resistance heating elements 51). Note that in FIG. 23, the direction of arrow Y is the widthwise direction of the heater 23, and is also the direction intersecting the arrangement direction of the plurality of resistance heating elements 51 (arrangement intersecting direction) or the same direction as the transport direction of paper passing through the fixing device.

[0118] Furthermore, the multiple resistance heating elements 51 form a central heating section 60B and heating sections 60A and 60C on both ends that can generate heat independently. For example, of the three electrode sections 53A to 53C, when electricity is applied to the leftmost electrode section 53A and the central electrode section 53B in FIG. 23, the heating sections 60A and 60C on both ends generate heat. When electricity is applied to the electrode sections 53A and 53C on both ends, the central heating section 60B generates heat. For example, when fixing small-size paper, only the central heating section 60B generates heat, and when fixing large-size paper, all of the heating sections 60A to 60C generate heat, allowing heating according to the size of the paper.

[0119] 24, the heater holder 25 has a recess 25a that accommodates and holds the heater 23 and the heat equalizer plate 24. The recess 25a is formed on the heater 23 side of the heater holder 25. The recess 25a is composed of a rectangular bottom 25f of approximately the same size as the heater 23, and four side surfaces 25g, 25h, 25i, and 25j that intersect with the bottom surface 25f along the four sides that form the outline of the bottom surface 25f. Note that the right side surface 25j is not shown in FIG. 24. Alternatively, one of the pair of side surfaces 25g and 25j (left and right) that intersect with the longitudinal direction X of the heater 23 (the direction in which the resistance heating elements 51 are arranged) may be omitted, and the recess 25a may be open at one end of the heater 23 in the longitudinal direction.

[0120] 25, the heater holder 25 that holds the heater 23 and the heat equalizer plate 24 is held by a connector 86. The connector 86 has a housing made of resin (for example, LCP) and a plurality of contact terminals provided inside the housing.

[0121] The connector 86 is attached to the heater holder 25 in a direction intersecting the longitudinal direction X of the heater 23 (the arrangement direction of the resistance heating elements 51) (see the direction of the arrow extending from the connector 86 in FIG. 25). With the connector 86 attached, the heater 23, the heat equalizer plate 24, and the heater holder 25 are held by being sandwiched between them from the front and back sides by the connector 86. In this state, each contact terminal comes into contact (pressure-welded) with each electrode portion of the heater 23, thereby electrically connecting each resistance heating element 51 to a power source provided in the image forming apparatus via the connector 86. This enables power to be supplied from the power source to each resistance heating element 51.

[0122] 25 are belt holding members that are provided on both longitudinal ends of the fixing belt 21 and hold both ends of the fixing belt 21 from the inside. The flanges 87 are inserted into both ends of the stay 26 and fixed to a pair of side plates that are frame members of the fixing device.

[0123] FIG. 26 is a diagram showing the arrangement of the temperature sensor 39 shown in FIG.

[0124] 26, the temperature sensor 39 includes a thermistor 27 for temperature control and a thermostat 28 for preventing excessive temperature rise. Two thermistors 27 are arranged on one end side of the longitudinal center Xm of the fixing belt 21. Meanwhile, two thermostats 28 are arranged on the other end side of the longitudinal center Xm of the fixing belt 21.

[0125] 26 and 31, flanges 87 that hold both ends of fixing belt 21 are provided with slide grooves 87a. Slide grooves 87a extend in the direction in which fixing belt 21 approaches and separates from pressure roller 22. An engagement portion of the housing of the fixing device engages with slide groove 87a. This engagement portion moves relatively within slide groove 87a, allowing fixing belt 21 to move in the direction in which fixing belt 21 approaches and separates from pressure roller 22.

[0126] The range where the heat sink 24 is disposed is not limited to the entire heat generation region in the longitudinal direction X of the heater 23. For example, as in the example shown in FIG. 28, the heat sink 24 may be disposed only in the divided region D between the resistance heating elements 51. In FIG. 28, for the sake of convenience, the divided region D and the heat sink 24 are displaced in the vertical direction of the drawing, but both are disposed at substantially the same position in the short hand direction Y of the heater 23. Further, the heat sink 24 may be disposed across a part of the divided region D in the short hand direction Y of the heater 23, or may be disposed across the entire divided region D in the short hand direction Y of the heater 23. Further, as shown in FIG. 29, the heat sink 24 may be disposed across the resistance heating elements 51 on both sides sandwiching the divided region D in addition to the divided region D between the resistance heating elements 51. That is, the heat sink 24 may be disposed so as to overlap at least a part of the resistance heating elements 51 on both sides sandwiching the divided region D. Further, the heat sink 24 may be disposed in all the divided regions D of the heater 23, or may be disposed only in a part of the divided regions D as in the example shown in FIG. 29.

[0127] By disposing the heat sink 24 in the divided region D of the heater 23, the heat conduction efficiency in the divided region D where the calorific value is small can be improved, and the temperature drop in the divided region D can be suppressed. Thereby, the temperature unevenness in the longitudinal direction of the heater 23 can be suppressed, and the temperature unevenness in the longitudinal direction of the fixing belt 21 can be suppressed. As a result, the fixing unevenness and the gloss unevenness of the image fixed on the paper can be suppressed. Further, in order to ensure sufficient fixing performance in the divided region D, it is not necessary to increase the calorific value of the heater 23, and energy saving of the fixing device can be realized. In particular, when the heat sink 24 is disposed across the entire heat generation region where the resistance heating element 51 is disposed, the heat transfer efficiency of the heater 23 can be improved in the entire main heating region by the heater 23 (that is, the image forming region of the paper through which the paper passes), and the temperature unevenness in the longitudinal direction of the heater 23 and the fixing belt 21 can be suppressed.

[0128] In addition, by combining the heat pipe 24 and the resistive heating element 51 having PTC characteristics, overheating in the non-passing region where the paper does not pass can be more effectively suppressed. The PTC characteristics refer to the characteristics in which the resistance value increases as the temperature rises (when a constant voltage is applied, the heater output decreases). That is, since the resistive heating element 51 has PTC characteristics, the heat generation amount of the resistive heating element 51 in the non-passing region can be effectively suppressed, and the heat amount in the non-passing region can be dispersed by the heat pipe 24. Therefore, overheating due to the non-passing region can be effectively suppressed by these synergistic effects.

[0129] In addition, since the temperature of the heater 23 tends to be low not only in the divided region D but also in its periphery, the heat pipe 24 may be arranged in the enlarged divided region E including the divided region D and its periphery shown in FIG. 30. Thereby, in the enlarged divided region E including the divided region D, the heat transfer efficiency can be improved, and the temperature unevenness in the longitudinal direction X of the heater 23 can be more effectively suppressed.

[0130] Subsequently, yet another fixing device to which the present invention is applicable will be described.

[0131] In the fixing device 70 shown in FIG. 31, the heat pipe 24 is composed of two-layer heat pipes 48 and 49. That is, a first heat pipe 48 in contact with the heater 23 and a second heat pipe 49 in contact with the first heat pipe 48 are provided. In the example shown in FIG. 31 as well, a thermostat in contact with the heater 23 is provided, but in FIG. 31, a cross-section in which a thermistor and a thermistor holder are not arranged is shown.

[0132] The second heat pipe 49 is made of a member having a higher thermal conductivity than the base material 50 of the heater 23, for example, graphene or graphite. As an example, a graphite sheet with a thickness of 1 mm can be mentioned. Further, the second heat pipe 49 may be made of a plate material such as aluminum, copper, or silver.

[0133] 32, a plurality of second heat equalizer plates 49 are arranged in the recess 25a of the heater holder 25. A gap is provided between each of the second heat equalizer plates 49 in the longitudinal direction X of the heater 23. A recess that is one step deeper than the other portions is formed in the portion of the heater holder 25 where the second heat equalizer plates 49 are provided.

[0134] 33, the second heat equalizer 49 (see the hatched area) is arranged so as to overlap at least a portion of each resistance heating element 51 that sandwiches the divided region D in the longitudinal direction X of the heater 23. On the other hand, the first heat equalizer 48 is arranged over the entire heat generating region in which all the resistance heating elements 51 are arranged. However, the arrangement range of the first heat equalizer 48 and the second heat equalizer 49 is not limited to this.

[0135] By arranging the second heat equalizer 49 so as to overlap at least a portion of each resistance heating element 51 that sandwiches the divided region D, the heat transfer efficiency in the divided region D is further improved, and temperature unevenness in the longitudinal direction X of the heater 23 can be more effectively suppressed. Also, as shown in FIG. 34 , the first heat equalizer 48 and the second heat equalizer 49 may be arranged only in an area that overlaps the entire divided region D. In this case, the heat transfer efficiency in the divided region D can be particularly improved. For convenience, in FIG. 34 , the divided region D and the first heat equalizer 48 and the second heat equalizer 49 are offset from each other in the vertical direction of the drawing, but they are actually arranged at approximately the same position in the lateral direction Y of the heater 23. However, this is not a limitation, and the first heat equalizer 48 and the second heat equalizer 49 may be arranged over a portion of the divided region D in the lateral direction Y of the heater 23, or over the entire divided region D in the lateral direction Y of the heater 23.

[0136] Furthermore, both the first heat equalizer plate 48 and the second heat equalizer plate 49 may be made of graphene sheets. In this case, the first heat equalizer plate 48 and the second heat equalizer plate 49 can be formed to have high thermal conductivity in a predetermined direction along the surface of the graphene, that is, in the longitudinal direction rather than the thickness direction, and therefore temperature unevenness in the heater 23 and the fixing belt 21 in the longitudinal direction can be effectively suppressed.

[0137] Graphene is a flake-like powder. Graphene is made up of carbon atoms, as shown in Figure 37. Graphene consists of a planar hexagonal lattice structure. Graphene sheets are sheets of graphene, usually in the form of a single layer. Graphene sheets may contain impurities in the single layer of carbon, or may have a fullerene structure. Fullerene structures are generally recognized as compounds in which the same number of carbon atoms form a polycyclic ring structure in which five- and six-membered rings are fused together in a cage-like fashion, such as C60, C70, and C80 fullerenes, or other closed cage structures with three-coordinate carbon atoms.

[0138] Graphene sheets are man-made and can be produced, for example, by chemical vapor deposition (CVD).

[0139] The graphene sheet may be a commercially available product. The size and thickness of the graphene sheet, or the number of layers of the graphite sheet (described later), may be measured using, for example, a transmission electron microscope (TEM).

[0140] Furthermore, graphite, which is a multilayered graphene, has a large thermal conductivity anisotropy. As shown in FIG. 38, graphite has a crystalline structure in which layers of fused six-membered rings of carbon atoms are laid out in a planar fashion, and these layers are stacked on top of each other. In this crystalline structure, adjacent carbon atoms within a layer form covalent bonds, while carbon atoms between layers form van der Waals bonds. Covalent bonds have a stronger bonding strength than van der Waals bonds, resulting in a large anisotropy between intralayer and interlayer bonds. In other words, by constructing the heat equalizer plate 24, including the first heat equalizer plate 48 and the second heat equalizer plate 49, from graphite, the heat transfer efficiency in the longitudinal direction of the heat equalizer plate 24 is greater than that in the thickness direction (i.e., the stacking direction of the components), thereby suppressing heat transfer to the heater holder 25. This effectively suppresses temperature unevenness in the longitudinal direction X of the heater 23 and minimizes heat leakage toward the heater holder 25. Furthermore, by forming the heat equalizer 24 from graphite, the heat equalizer 24 can have excellent heat resistance, being resistant to oxidation up to about 700 degrees.

[0141] The physical properties and dimensions of the graphite sheet can be appropriately changed depending on the functions required of the heat equalizer plate 24. For example, the anisotropy of heat conduction can be increased by using high-purity graphite or single-crystal graphite, or by increasing the thickness of the graphite sheet. Furthermore, in order to increase the speed of the fixing device, a thin graphite sheet can be used to reduce the heat capacity of the fixing device. Furthermore, if the widths of the nip portion N and the heater 23 are large, the longitudinal width of the heat equalizer plate 24 can be increased accordingly.

[0142] From the viewpoint of increasing the mechanical strength, the number of layers of the graphite sheet is preferably at least 11. The graphite sheet may partially include a single layer portion and a multi-layer portion.

[0143] The second heat equalizer 49 need only be provided in a position in the longitudinal direction X of the heater 23 where it overlaps with the divided region D and at least a portion of the resistance heating elements 51 on both sides of the divided region D, and is not limited to the arrangement shown in Fig. 34 . For example, as in the example shown in Fig. 35 , the second heat equalizer 49 may be provided so as to protrude from the base material 50 of the heater 23 to both sides in the lateral direction Y of the heater 23. The second heat equalizer 49 may also be provided in a range in the lateral direction Y of the heater 23 where the resistance heating elements 51 are provided. The second heat equalizer 49 may also be provided in a portion of the divided region D.

[0144] 36, a gap 38 may be provided between the first heat equalizer 48 and the heater holder 25 in the thickness direction (left-right direction in FIG. 36). That is, the gap 38 is provided as a heat insulating layer in a portion of the recess 25a (see FIG. 32) of the heater holder 25 where the heater 23, the first heat equalizer 48, and the second heat equalizer 49 are disposed. The gap 38 is provided in a portion of the heater holder 25 other than the portion where the second heat equalizer 49 (not shown in FIG. 36) is disposed. The gap 38 is formed by making the recess 25a of the heater holder 25 deeper than the remaining portion. This reduces the contact area between the heater holder 25 and the first heat equalizer 48, suppresses heat transfer from the first heat equalizer 48 to the heater holder 25, and enables efficient heating of the fixing belt 21. At the location where the second heat equalizer 49 is provided, the second heat equalizer 49 is held in contact with the bottom surface of the recess 25a of the heater holder 25, as shown in FIG.

[0145] Furthermore, the gap 38 is provided over the entire area where the resistance heating element 51 is provided in the short-side direction Y of the heater 23 (the vertical direction in FIG. 36 ). This effectively suppresses heat transfer from the first heat equalizer plate 48 to the heater holder 25, improving the heating efficiency of the heater 23 for the fixing belt 21. Note that the gap 38 may be configured to be provided with a heat insulating member having a lower thermal conductivity than the heater holder 25.

[0146] Further, the first heat sink 48 and the second heat sink 49 are not limited to being configured separately from each other, and may be integrated. That is, by forming the portion corresponding to the divided region D of the first heat sink 48 thicker than the other portions, the first heat sink 48 may also function as the second heat sink 49.

[0147] Also, the fixing device 20 shown in FIG. 39 does not have a heat sink, and the thermistor 27 directly contacts the heater 23 through the through hole 25b provided in the heater holder 25. The heater 23 is a planar heating element having a resistive heating element provided on a base material. The heater holder 25 is formed of a heat-resistant resin.

[0148] As described above, the configurations of the fixing device and the image forming device to which the present invention is applicable have been described. However, even in the fixing device and the image forming device having such configurations, by applying the present invention, the same effects as those of the above-described embodiments can be obtained. That is, by applying the present invention, the inclination of the thermistor holder 29 can be suppressed, and the detection accuracy of the thermistor 27 can be maintained at a high level.

[0149] Further, the present invention is not limited to being applied to a fixing device which is an example of a heating device, and can also be applied to heating devices other than the fixing device. For example, the present invention can also be applied to heating devices such as a drying device for drying a liquid such as ink applied to paper, a laminator for thermally pressing a film as a covering member onto the surface of a sheet such as paper, and a heat sealer for thermally pressing a seal portion of a packaging material. Thereby, the inclination of the first holding member can be suppressed.

[0150] Aspects of the present invention are as follows, for example. <1> A rotating member, A contact type temperature detecting member having a temperature detecting portion, A first holding member for holding the temperature detecting member, A second holding member for holding the first holding member, A heating device including an electric wire extending in a first direction, wherein the temperature detecting member is biased toward the member to be detected, When the direction in which the temperature detection member is biased and the opposite direction thereof are defined as the second direction which intersects the first direction, and the direction which intersects the second direction in the direction orthogonal to the first direction is defined as the third direction, The first holding member has a support portion extending in the second direction, a supported portion extending in the third direction, and a contact portion that contacts the second holding member in the third direction. The support portion supports one side of the supported portion in the third direction. The first holding member has a wiring space that opens to the other side in the third direction on the side of the support portion in the second direction from the supported portion and routes the electric wire in the first direction. When the surface on which the end portion of the support portion on the side opposite to the supported portion in the second direction is provided is defined as a reference surface, and the distance in the second direction from the reference surface toward the supported portion is defined as the height, A heating device, characterized in that the contact height between the contact portion and the second holding member is provided higher than the height of the wiring space. <2> A rotating member, A heating body having a base material and a heating element, A contact type temperature detection member having a temperature detection portion, A first holding member that holds the temperature detection member, A second holding member that holds the first holding member, A heating device including an electric wire extending in a first direction, wherein The temperature detection member is biased toward the member to be detected, When the direction in which the temperature detection member is biased and the opposite direction thereof are defined as the second direction which intersects the first direction, and the direction which intersects the second direction in the direction orthogonal to the first direction is defined as the third direction, The first holding member has a support portion extending in the second direction, a supported portion extending in the third direction, and a contact portion that contacts the second holding member in the third direction. The support portion supports one side of the supported portion in the third direction. The first holding member has a wiring space that opens to the other side in the third direction on the side of the support portion in the second direction from the supported portion, and wires the electric wire in the first direction. When the distance in the second direction from the reference surface, which is the surface of the heating element on the side of the rotating member, to the side of the supported portion is defined as the height, The heating device is characterized in that the contact height between the contact portion and the second holding member is set higher than the height of the wiring space. <3> A rotating member, A contact type temperature detection member having a temperature detection portion, A first holding member that holds the temperature detection member, A second holding member that holds the first holding member, A heating device including an electric wire extending in a first direction, wherein The temperature detection member is biased toward the detected member, When the direction in which the temperature detection member is biased and the opposite direction thereof are defined as the second direction that intersects the first direction, and the direction that intersects the second direction and is orthogonal to the first direction is defined as the third direction, The first holding member has a support portion extending in the second direction, a supported portion extending in the third direction, and a contact portion that contacts the second holding member in the third direction. The support portion supports one side of the supported portion in the third direction. The first holding member has a wiring space that opens to the other side in the third direction on the side of the support portion in the second direction from the supported portion, and wires the electric wire in the first direction. The heating device is characterized in that when the side from the support portion in the second direction toward the supported portion is defined as the height in the second direction, the contact height between the contact portion and the second holding member is set higher than the surface of the supported portion facing the wiring space. <4> The heating device according to any one of <1> to <3>, wherein the first holding member has a first contact portion that contacts the second holding member on one side in the third direction and a second contact portion that contacts the second holding member on the other side in the third direction as the contact portion. <5> The second holding member has a first abutted portion that abuts against the first abutting portion and a second abutted portion that abuts against the second abutting portion, with a space therebetween in the third direction. The first holding member includes a fitting portion that has the first abutting portion and the second abutting portion on both sides in the third direction. The heating device according to <4>, wherein the first holding member is positioned with respect to the second holding member by fitting the fitting portion between the first abutted portion and the second abutted portion. <6> The heating device according to any one of <1> to <5>, further comprising one or more other first holding members having, on one side or the other side of the first holding member in the first direction, another supporting portion, another supported portion, and another wiring space that opens on one side or the other side in the third direction. The heating device, wherein the wiring spaces provided in the first holding member and the other first holding members or the opening directions of the other wiring spaces are alternately arranged in the first direction, with one on one side of the third direction and the other on the other side opposite to one side of the third direction. <7> The heating device according to any one of <1> to <6>, having the abutting portions on one side and the other side of the first holding member in the first direction. <8> The heating device according to any one of <1> to <7>, wherein the first holding member holds the temperature detection member, and in a state where the second holding member holds the first holding member, a dimensional difference between the two in the third direction at the positioning portion between the first holding member and the second holding member is smaller than a dimensional difference between the two in the third direction at the positioning portion between the first holding member and the temperature detection member. <9> A fixing device that heats a recording medium using the heating device according to any one of <1> to <8> and fixes an image on the recording medium to the recording medium. <10> An image forming apparatus including the fixing device according to <9>.

Description of Reference Numerals

[0151] 20 Fixing device (heating device) 21 Fixing belt (rotating member or fixing member) 22 Pressing roller (opposing member or pressing member) 23 Heater (heating element) 24 Heat sink plate (high heat conductivity member) 25 Heater holder (second holding member) 25c1 Positioning rib (first abutted portion) 25c2 Positioning rib (second abutted portion) 27 Thermistor (temperature detection member) 271 Heat sensing element (temperature detection part) 29 Thermistor holder (first holding member) 29a One end portion (fitting portion) 29a1 Contact rib (first contact portion) 29a2 Contact rib (second contact portion) 29b Support portion 29c Supported portion 29d Wiring space 29e1, 29e2 Contact ribs (contact portions) 29h Reference plane 270 Harness (electric wire) 1000 Image forming apparatus A1 Height of wiring space A2 Contact height X Longitudinal direction (first direction) Y Lateral direction (third direction) Z Direction in which the thermistor is biased (second direction)

Prior art documents

Patent documents

[0152]

Patent Document 1

Claims

1. A rotating member; a contact-type temperature detection member having a temperature detection portion; a first holding member that holds the temperature detection member; a second holding member that holds the first holding member; a heating device including an electric wire extending in a first direction, The temperature sensing member is biased toward the sensing member, A direction in which the temperature detection member is biased and a direction opposite thereto that intersect with the first direction are defined as a second direction, and a direction perpendicular to the first direction that intersects with the second direction are defined as a third direction. the first holding member has a supporting portion extending in the second direction, a supported portion extending in the third direction, and an abutting portion abutting against the second holding member in the third direction, the supporting portion supports one side of the supported portion in the third direction, the first holding member has a wiring space that is open to the other side in the third direction and is closer to the supporting portion in the second direction than the supported portion, and through which the electric wires are wired in the first direction; When a surface on which an end of the supporting portion on the opposite side to the supported portion in the second direction is provided is defined as a reference surface, and the distance in the second direction from the reference surface toward the supported portion is defined as a height, The heating device according to claim 1, wherein the height of the contact between the contact portion and the second holding member is set higher than the height of the wiring space.

2. A rotating member; a heating element having a substrate and a heating element; a contact-type temperature detection member having a temperature detection portion; a first holding member that holds the temperature detection member; a second holding member that holds the first holding member; a heating device including an electric wire extending in a first direction, The temperature sensing member is biased toward the sensing member, A direction in which the temperature detection member is biased and a direction opposite thereto that intersect with the first direction are defined as a second direction, and a direction perpendicular to the first direction that intersects with the second direction are defined as a third direction. the first holding member has a supporting portion extending in the second direction, a supported portion extending in the third direction, and an abutting portion abutting against the second holding member in the third direction, the supporting portion supports one side of the supported portion in the third direction, the first holding member has a wiring space that is open to the other side in the third direction and is closer to the supporting portion in the second direction than the supported portion, and through which the electric wires are wired in the first direction; When the surface of the heating body on the rotating member side is defined as a reference plane and the distance in the second direction from the reference plane toward the supported portion is defined as a height, A heating device, characterized in that a contact height between the contact portion and the second holding member is provided higher than a height of the wiring space.

3. A rotating member, a contact-type temperature detection member having a temperature detection portion, a first holding member for holding the temperature detection member, a second holding member for holding the first holding member, a heating device including an electric wire extending in a first direction, wherein the temperature detection member is biased toward a member to be detected, when a direction intersecting the first direction in a direction in which the temperature detection member is biased and a direction opposite thereto is defined as a second direction, and a direction intersecting the second direction in a direction orthogonal to the first direction is defined as a third direction, the first holding member has a support portion extending in the second direction, a supported portion extending in the third direction, and a contact portion that contacts the second holding member in the third direction, the support portion supports one side of the supported portion in the third direction, the first holding member has a wiring space that opens to the other side in the third direction on a side of the support portion in the second direction with respect to the supported portion and wires the electric wire in the first direction, a heating device, characterized in that when a side from the support portion in the second direction toward the supported portion is defined as a height in the second direction, a contact height between the contact portion and the second holding member is provided higher than a surface of the supported portion facing the wiring space.

4. The heating device according to claim 1, wherein the first holding member has, as the contact portion, a first contact portion that contacts the second holding member on one side in the third direction and a second contact portion that contacts the second holding member on the other side in the third direction.

5. The second holding member has, at intervals in the third direction, a first portion to be contacted that is contacted by the first contact portion and a second portion to be contacted that is contacted by the second contact portion, the first holding member includes a fitting portion having the first contact portion and the second contact portion on both sides in the third direction, The heating device according to claim 2, wherein the first holding member is positioned with respect to the second holding member by fitting the fitting portion between the first portion to be contacted and the second portion to be contacted.

6. The heating device according to claim 1, further comprising one or a plurality of other first holding members having, on one side or the other side of the first holding member in the first direction, another support portion, another supported portion, and another wiring space that opens to one side or the other side in the third direction. A heating device in which the opening directions of the wiring spaces provided in the first holding member and the other first holding member or the other wiring spaces are alternately arranged in the first direction, with one on one side of the third direction and the other on the other side opposite to one side of the third direction.

7. The heating device according to claim 1, further comprising the contact portions on one side and the other side in the first direction of the first holding member.

8. The heating device according to claim 1, wherein the first holding member holds the temperature detection member, and in a state where the second holding member holds the first holding member, a dimensional difference in the third direction between both in the positioning portion between the first holding member and the second holding member is smaller than a dimensional difference in the third direction between both in the positioning portion between the first holding member and the temperature detection member.

9. A fixing device that heats a recording medium using the heating device according to any one of claims 1 to 8 and fixes an image on the recording medium to the recording medium.

10. An image forming apparatus including the fixing device according to claim 9.

Images