Heating device, fixing device, and image forming apparatus

Abstract

To suppress inclination of a holding member.SOLUTION: A fixing device 20 comprises: a fixing belt 21; a contact-type thermistor 27; a thermistor holder 29 that holds the thermistor 27; a harness 270 that extends in a direction X; and an urging spring 31 that urges the thermistor 27 toward a soaking plate 24 with the thermistor holder 29 therebetween. The thermistor holder 29 has: a pair of support parts 29b that are provided side by side in a direction Y and provided over a direction Z; a pair of supported parts 29c that are supported by the respective support parts 29b and provided over the direction Y; and a wiring space 29d that is surrounded by the pair of support parts 29b and the pair of supported parts 29c for wiring the harness 270. The fixing device includes a slit 29h that is provided over the direction X between the pair of supported parts 29c and communicates with the wiring space 29d.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] In a fixing device as a heating device, in order to appropriately control the temperature of the fixing belt (rotating member), a temperature detection member is provided that detects the temperature by bringing a temperature detection element into contact with a heating element or the like in the fixing device, a holding member that holds the temperature detection member, and a biasing member that biases the temperature detection member toward the detected member via the holding member.

[0003] The holding member is provided with a wiring space for passing electric wires attached to other temperature detecting members in the fixing device.

[0004] As an example of such a fixing device, the fixing device disclosed in Patent Document 1 (JP 2014-186308 A) has a sensor holding member 501 that holds a temperature sensor 500, as shown in FIG. 43. A 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, pressing the temperature sensor 500 against a heater 504. This allows the temperature sensor 500 to detect the temperature of the heater 504. A heater holding member 505 that holds the heater 504 has plate-shaped protrusions 505a and 505b that are provided with groove-shaped positioning portions 505a1 and 505b1. The sensor holding member 501 is positioned in the up-down direction in FIG. 43 by engaging engagement portions 501a and 501b with positioning portions 505a1 and 505b1. The cable of the temperature sensor 500 is passed between the plate-like protrusions 505a and 505b in the direction perpendicular to the plane of the paper in FIG. Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the structure of the holding member that provides the wiring space, the biasing force of the biasing member may cause the holding member to tilt, which may result in the temperature detection member being unable to properly abut against the detected member, resulting in a problem of reduced detection accuracy of the temperature detection member.

[0006] An object of the present invention is to suppress tilting of the holding member. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a heating device comprising a rotating member, a contact-type temperature detection member, a holding member that holds the temperature detection member, an electric wire extending in a first direction, and a biasing member that biases the temperature detection member toward a detected member via the holding member, wherein if the direction in which the temperature detection member is biased and the opposite direction, and a direction that intersects with the first direction, are defined as a second direction, and a direction that is perpendicular to the first direction and intersects with the second direction, are defined as a third direction, the holding member is arranged side by side in the third direction and has a pair of supporting parts that are arranged across the second direction, a pair of supported parts that are supported by the respective supporting parts and are arranged across the third direction, and a wiring space that is surrounded by the pair of supporting parts and the pair of supported parts and in which the electric wire is wired, and is provided with a slit that is arranged between the pair of supported parts and that communicates with the wiring space, [Effects of the Invention]

[0008] In the present invention, tilting of the holding member can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. [Figure 2] 1 is a schematic configuration diagram of a fixing device according to a first embodiment of the present invention. [Figure 3] FIG. 1 is a plan view of a heater according to a first embodiment of the present invention. [Figure 4]FIG. 2 is a block diagram of a temperature control mechanism for a heater according to the first embodiment of the present invention. [Figure 5] 1(a) to 1(c) are views showing the part of the thermistor holder that holds the thermistor, where 1(a) is a plan view, 1(b) is a side view, and 1(c) is a cross-sectional view taken along line AA in 1(a). [Figure 6] FIG. 2 is a cross-sectional view showing a thermistor, a thermistor holder, and a heater holder of the embodiment. [Figure 7] 2A to 2C are diagrams showing the thermistor of the embodiment, in which FIG. 2A is a plan view, FIG. 2B is a rear view, and FIG. 2C is a side view. [Figure 8] FIG. 2 is a perspective view showing the rear side of the heater holder. [Figure 9] FIG. 10 is a rear view of the heater holder with the thermistor attached thereto. [Figure 10] FIG. [Figure 11] FIG. 10 is a perspective view showing a state in which the thermistor holder is attached to the heater holder. [Figure 12] FIG. 10 is a rear view showing the state in which the thermistor holder is attached to the heater holder. [Figure 13] FIG. 4 is a cross-sectional view showing a thermistor holder and a biasing spring. [Figure 14] FIG. 10 is a plan view showing a modified example of the slit. [Figure 15] FIG. 10 is a plan view showing another modified example of the slit. [Figure 16] 10A and 10B are diagrams showing modified examples of the resistance heating element; [Figure 17] 10A and 10B are diagrams showing other modified examples of the resistance heating element. [Figure 18] FIG. 2 is a cross-sectional view of a fixing belt that does not have an elastic layer. [Figure 19] FIG. 10 is a diagram showing the configuration of another fixing device to which the present invention can be applied. [Figure 20] FIG. 10 is a diagram showing the configuration of another fixing device to which the present invention can be applied. [Figure 21] FIG. 10 is a diagram showing the configuration of yet another fixing device to which the present invention can be applied. [Figure 22]FIG. 10 is a diagram showing the configuration of yet another fixing device to which the present invention can be applied. [Figure 23] FIG. 10 is a diagram showing the configuration of yet another fixing device to which the present invention can be applied. [Figure 24] FIG. 10 is a diagram showing the configuration of another image forming apparatus to which the present invention can be applied. [Figure 25] 25 is a diagram showing the configuration of the fixing device shown in FIG. 24. FIG. [Figure 26] FIG. 26 is a plan view of the heater shown in FIG. 25. [Figure 27] FIG. 26 is a perspective view of the heater, the heat equalizer plate, and the heater holder shown in FIG. 25. [Figure 28] 26 is a diagram showing a method of attaching a connector to the heater holder shown in FIG. 25. [Figure 29] FIG. 26 is a diagram showing the arrangement of the temperature sensors shown in FIG. 25. [Figure 30] FIG. 29 is a view showing a groove portion of the flange shown in FIG. 28. [Figure 31] 10A and 10B are diagrams showing other examples of arrangement of heat equalizing plates. [Figure 32] FIG. 10 is a diagram showing yet another example of the arrangement of the heat equalizing plate. [Figure 33] FIG. 10 is a diagram showing an enlarged divided region of a heater. [Figure 34] FIG. 10 is a diagram showing the configuration of yet another fixing device to which the present invention can be applied. [Figure 35] FIG. 35 is a perspective view of the heater, the first heat equalizer plate, the second heat equalizer plate, and the heater holder shown in FIG. 34. [Figure 36] FIG. 2 is a diagram showing the arrangement of a first heat equalizer plate and a second heat equalizer plate. [Figure 37] 10A and 10B are diagrams showing other examples of the arrangement of the first and second heat equalizing plates. [Figure 38] FIG. 10 is a diagram showing yet another example of the arrangement of the second heat equalizing plate. [Figure 39] 10 is a diagram showing an example in which a gap is provided between the first heat equalizer plate and the heater holder. FIG. [Figure 40] FIG. 1 illustrates the atomic crystal structure of graphene. [Figure 41] FIG. 1 illustrates the atomic crystal structure of graphite. [Figure 42] FIG. 10 is a diagram showing the configuration of yet another fixing device to which the present invention can be applied. [Figure 43] FIG. 10 is a cross-sectional view of a conventional fixing device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted. Below, a fixing device provided in an image forming apparatus will be described as a heating device according to one embodiment of the present invention.

[0011] <Overall configuration of image forming apparatus> FIG. 1 is a schematic diagram of an image forming apparatus 1000 according to a first embodiment of the present invention. In this specification, the term "image forming apparatus" includes a printer, a copier, a facsimile, a printing machine, or a multifunction machine that combines two or more of these. Furthermore, the term "image formation" used in the following description refers not only to the formation of meaningful images such as characters and figures, but also to the formation of meaningless images such as patterns. First, the overall configuration and operation of the image forming apparatus according to the first embodiment of the present invention will be described with reference to FIG. 1.

[0012] As shown in FIG. 1, an image forming apparatus 1000 according to the first embodiment of the present invention includes an image forming section 100, a fixing section 200, a sheet supply section 300, and a sheet discharge section 400.

[0013] (Image forming section) The image forming section 100 is a section that forms an image on a sheet as a recording medium. The image forming section 100 includes four imaging units 1Y, 1M, 1C, and 1Bk, an exposure device 6, and a transfer device 8.

[0014] Each of the four imaging units 1Y, 1M, 1C, and 1Bk includes an electrostatic latent image carrier 2, a charging member 3, a developing device 4, and a cleaning device 5.

[0015] 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, a photosensitive drum or an endless photosensitive belt can be used.

[0016] The charging member 3 is a member that charges the surface of the electrostatic latent image carrier 2. There are no particular limitations on the charging member 3, and it can be appropriately selected depending on the purpose, as long as it can apply a voltage to the surface of the electrostatic latent image carrier 2 and uniformly charge it. Specific examples include contact-type charging members such as conductive or semi-conductive charging rollers, magnetic brushes, fur brushes, films, and rubber blades, as well as non-contact-type charging members that utilize corona discharge.

[0017] The developing device 4 is a device that forms a toner image by supplying toner as a developer to the electrostatic latent image on the electrostatic latent image carrier 2. The developing device 4 contains toner (developer) of different colors, such as yellow, magenta, cyan, and black, corresponding to the color separation components of the color image, for each of the imaging units 1Y, 1M, 1C, and 1Bk.

[0018] The cleaning device 5 removes toner and other foreign matter remaining on the electrostatic latent image carrier 2. The cleaning device 5 is provided with a cleaning blade that comes into contact with the surface of the electrostatic latent image carrier 2, and the like.

[0019] The exposure device 6 is a device that exposes the charged surface of the electrostatic latent image carrier 2 to light to form an electrostatic latent image. There are no particular limitations on the exposure device 6 as long as it can expose the charged surface of the electrostatic latent image carrier 2, and it can be appropriately selected depending on the purpose. Specific examples include 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.

[0020] Toner bottles 90Y, 90C, 90M, and 90K filled with yellow, cyan, magenta, and black toners are detachably provided on the top of the image forming apparatus 1000. The toner of each color is supplied from the toner bottles 90Y, 90C, 90M, and 90K to the developing devices 4 of the respective colors through supply paths provided between the bottles and the developing devices 4.

[0021] 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 that is stretched by a plurality of support rollers. Four primary transfer rollers 12 are provided inside the intermediate transfer belt 11. Each primary transfer roller 12 contacts a corresponding electrostatic latent image carrier 2 via the intermediate transfer belt 11, thereby forming a primary transfer nip between the intermediate transfer belt 11 and each electrostatic latent image carrier 2. Meanwhile, the secondary transfer roller 13 contacts the outer peripheral surface of the intermediate transfer belt 11. This forms a secondary transfer nip between the secondary transfer roller 13 and the intermediate transfer belt 11.

[0022] The intermediate transfer belt 11 may have a single-layer structure or a multi-layer structure, and in the case of a single-layer structure, it is preferably formed from polyvinylidene fluoride, polycarbonate, polyimide, etc. In the case of a multi-layer structure, it is preferable that the base layer is formed from a fluororesin, polyvinylidene fluoride sheet, or polyimide resin with little elongation, and the surface is covered with a coating layer with good smoothness such as a fluororesin.

[0023] (fixing part) The fixing section 200 has a fixing device 20 that heats the sheet to fix an image on the sheet. The fixing device 20 includes a pair of rotating bodies 19A and 19B that contact each other, and a heater that heats at least one of the pair of rotating bodies 19A and 19B.

[0024] (Sheet supply unit) The sheet supply unit 300 is a part that supplies sheets to the image forming unit 100. The sheet supply unit 300 has a paper feed cassette 14 that stores paper P as sheets, and a paper feed roller 15 that feeds paper P from the paper feed cassette 14. Note that the term "sheet" includes not only paper, but also transparencies or fabrics, metal sheets, plastic films, or prepreg sheets made of carbon fiber pre-impregnated with resin. In addition to plain paper, the term "paper" includes cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, etc.

[0025] (sheet discharge section) The sheet discharge section 400 is a section that discharges the paper P to the outside of the apparatus. The sheet discharge section 400 has 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.

[0026] <Image formation operation> Next, the operation of the image forming apparatus 1000 according to the first embodiment of the present invention will be described with reference to FIG.

[0027] When an image formation operation is initiated in response to an instruction from the operation panel or an external terminal, the electrostatic latent image carrier 2 in each of the imaging units 1Y, 1M, 1C, and 1Bk begins to rotate. Next, each charging member 3 charges the surface of each electrostatic latent image carrier 2 to a uniform high potential. Next, the exposure device 6 exposes the surface (charged surface) of each electrostatic latent image carrier 2 based on image information from the original document read by the original document reader or print image information instructed from the external terminal. This reduces the potential of the exposed area, forming an electrostatic latent image 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, forming a toner image of a different color on each electrostatic latent image carrier 2.

[0028] As the electrostatic latent image carriers 2 rotate, the toner images on each electrostatic latent image carrier 2 reach the primary transfer nip (the position of the primary transfer roller 12). At the primary transfer nip, the toner images are transferred from each electrostatic latent image carrier 2 to the rotating intermediate transfer belt 11, overlapping one another. Thus, a full-color toner image is formed on the intermediate transfer belt 11. Image formation is not limited to forming a full-color image using all four imaging units 1Y, 1M, 1C, and 1Bk. It is also possible to form a monochrome image using any one of the imaging units 1Y, 1M, 1C, and 1Bk, or to form a two- or three-color image using any two or three of the imaging units. After the toner images are transferred to the intermediate transfer belt 11, the cleaning device 5 cleans the electrostatic latent image carriers 2. This removes residual toner and other foreign matter from the surface of each electrostatic latent image carrier 2.

[0029] The toner image transferred onto the intermediate transfer belt 11 is transported to the secondary transfer nip (the 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 a sheet P. This sheet P is supplied from the sheet supply unit 300. After the image forming operation starts, the sheet P is sent out from the sheet feed cassette 14 by the rotation of the sheet feed roller 15. The sent sheet P comes into contact with the timing roller pair 16 on its way to the secondary transfer nip, and its transport is temporarily stopped. Thereafter, the timing roller pair 16 rotates at a predetermined timing, and the sheet P is transported to the secondary transfer nip in synchronization with the toner image on the intermediate transfer belt 11, and the toner image is transferred to the sheet P.

[0030] The paper P onto which the toner image has been transferred is transported to the fixing unit 200. In the fixing unit 200, the paper P passes between a pair of rotating rotors 19A and 19B, whereby the toner image on the paper P is heated and pressurized, and the toner image is fixed to the paper P. The paper P is then transported to the sheet discharge unit 400 and discharged onto the paper discharge tray 18 by the paper discharge rollers 17. This completes the series of image forming operations.

[0031] <Configuration of fixing device> 2 is a schematic diagram of the fixing device 20 according to the first embodiment of the present invention. Note that in FIG. 2, the thermistor holder 29 and the surrounding structure are shown in a simplified form.

[0032] 2, fixing device 20 includes, in addition to a pair of rotating bodies 19A and 19B, heater 23 as a heating body, heat equalizing plate 24 as a highly thermally conductive member, heater holder 25 as a heating body holding member, stay 26 as a support member, thermistor 27 as a temperature detection member, and thermistor holder 29 as a holding member. The holding member of the present invention is a member that holds the temperature detection member.

[0033] Of the pair of rotors 19A, 19B, the first rotor 19A is a fixing belt 21 that is disposed on the unfixed image bearing surface of the paper P. The other rotor, the second rotor 19B, is a pressure roller 22 that is disposed opposite the fixing belt 21. The fixing belt 21 and the pressure roller 22 are pressed by a pressure member such as a spring so that they come into contact with each other. As a result, a nip N is formed between the fixing belt 21 and the pressure roller 22.

[0034] The direction perpendicular to the plane of FIG. 2 (direction X in FIG. 3) is the longitudinal direction of the fixing belt 21, pressure roller 22, heater 23, heat equalizer plate 24, heater holder 25, stay 26, thermistor 27, thermistor holder 29, and fixing device 20, and is also referred to as the first direction in this embodiment. Hereinafter, this direction will also be referred to simply as the longitudinal direction. Note that this longitudinal direction also refers to the belt width direction of the fixing belt 21 or the axial direction of the pressure roller 22, and also the width direction of the paper being conveyed. The paper width direction is a direction perpendicular to the paper conveyance direction and thickness direction. Direction Y in FIG. 2 is the short-side direction of the heater 23, heat equalizer plate 24, thermistor 27, thermistor holder 29, etc., the paper conveyance direction and the opposite direction, and is referred to as the third direction in this embodiment. Direction Z in FIG. 2 is the thickness direction of the heater 23, heat equalizer plate 24, etc., the pressure direction of the pressure roller 22 against the fixing belt 21, or the direction in which the thermistor 27 is biased, and is referred to as the second direction in this embodiment. The directions X, Y, and Z are perpendicular to each other.

[0035] The fixing belt 21 is composed of an endless belt member having a cylindrical substrate and a release layer provided on the outer peripheral surface of the substrate. The substrate 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). The fixing belt 21 having the release layer improves the separation of the toner image from the fixing belt 21 and suppresses the wrapping of the paper P around the fixing belt 21. The fixing belt 21 may also have an elastic layer between the substrate and the release layer. Examples of materials for the elastic layer include rubber materials such as silicone rubber, foamed silicone rubber, and fluororubber. The fixing belt 21 having the elastic layer reduces the formation of minute irregularities on the surface of the fixing belt 21, which facilitates uniform heat transfer to the toner image on the paper P and improves fixing quality.

[0036] The pressure roller 22 is composed of a roller having a hollow or solid core, an elastic layer provided on the outer peripheral surface of the core, and a release layer provided on the outer peripheral surface of the elastic layer. The core is made of a metal material such as iron. The elastic layer is made of silicone rubber, foamed silicone rubber, fluororubber, or the like. The release layer is made of a fluororesin such as PFA or PTFE.

[0037] The heater 23 is disposed so as to contact the inner circumferential surface of the fixing belt 21 at the nip portion N. The fixing belt 21 is sandwiched between the heater 23 and the pressure roller 22, whereby the fixing belt 21 is pressed, and the nip portion N is formed between the fixing belt 21 and the pressure roller 22. The heater 23 may directly contact the inner circumferential surface of the fixing belt 21, or may contact the inner circumferential surface of the fixing belt 21 via a low-friction sliding sheet. In this specification, unless otherwise specified, "contact" includes not only direct contact without any other member in between, but also indirect contact via other member.

[0038] The heater 23 includes a substrate 50, a resistance heating element 51, an insulating layer 52, and the like. The resistance heating element 51 is provided on the substrate 50 and is covered with the insulating layer 52. When the resistance heating element 51 generates heat by energizing it, the heat is transferred to the inner circumferential surface of the fixing belt 21 via the insulating layer 52, thereby heating the fixing belt 21. Alternatively, the heater 23 may be oriented differently so that the substrate 50 is in contact with the inner circumferential surface of the fixing belt 21. In this case, since the heat from the resistance heating element 51 is transferred to the fixing belt 21 via the substrate 50, it is preferable that the substrate 50 be made of a material with high thermal conductivity.

[0039] The substrate 50 is formed from a non-metallic material such as ceramics, glass, or mica, which have excellent heat resistance and insulation properties. Alternatively, the substrate 50 can be formed from a conductive material, such as metal, by interposing a separate insulating layer between the substrate 50 and the resistance heating element 51. Aluminum or stainless steel is preferred as a metal material because of its low cost. Furthermore, to suppress temperature variations in the heater 23 and improve image quality, the substrate 50 may be formed from a material with high thermal conductivity, such as copper, graphite, or graphene. Graphene is a sheet-like substance formed by bonding carbon atoms.

[0040] 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 is applied to the substrate 50 by screen printing, and then the substrate 50 is fired to form the resistance heating element 51. In addition to silver palladium, other resistive materials such as silver alloy (AgPt) or ruthenium oxide (RuO2) may also be used as the material for the resistance heating element 51. The insulating layer 52 is formed from, for example, heat-resistant glass.

[0041] The heat equalizer 24 is a member that assists in the transfer of heat generated by the heater 23. The heat equalizer 24 is formed of a material with higher thermal conductivity than the heater holder 25 and the like. The material of the heat equalizer 24 is copper, aluminum, graphene, or the like, and an example is an aluminum plate with a thickness of 0.3 mm. The heat equalizer 24 is arranged so as to contact a surface 23b of the heater 23 opposite to a rotor contact surface 23a that contacts the inner circumferential surface of the fixing belt 21. The heat equalizer 24 is not limited to being a single-layer member, and may be formed of a multi-layer member.

[0042] In particular, in the first embodiment of the present invention, the heat equalizer plate 24 is disposed in direct contact with the heater 23, allowing the heat from the heater 23 to be effectively dispersed by the heat equalizer plate 24. Generally, heat from the nip portion N is not easily consumed in the non-passage area where the paper P does not pass. Therefore, when paper P having a width smaller than the heat generating area of ​​the heater 23 is continuously passed through, there is a risk that the temperatures of the fixing belt 21 and the heater 23 in the non-passage area will rise excessively. However, in the first embodiment of the present invention, the heat equalizer plate 24 is provided, allowing the heat from the nip portion N in the non-passage area to be dispersed to the surrounding area via the heat equalizer plate 24. This prevents localized temperature increases in the fixing belt 21 and the heater 23. Furthermore, the heat from the nip portion N in the non-passage area can be transferred to the pass area where the paper P passes, allowing for effective use of the heat for the fixing process, which is expected to improve energy conservation.

[0043] The heater holder 25 is a member that holds the heater 23 and the heat equalizer plate 24. The heater holder 25 has a recess 25a that accommodates the heater 23 and the heat equalizer plate 24. By accommodating the heater 23 and the heat equalizer plate 24 in the recess 25a of the heater holder 25, movement of the heater 23 and the heat equalizer plate 24 in the vertical direction and the direction perpendicular to the plane of the paper in FIG. 2 is restricted. The heater holder 25 is easily heated to a high temperature by the heat of the heater 23, so it is preferable that the heater holder 25 be made of a heat-resistant material. In particular, when the heater holder 25 is made 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, thereby improving the heating efficiency of the heater 23.

[0044] Furthermore, a through-hole 25b penetrating to the rear surface side is provided in a partial region of the recess 25a of the heater holder 25. The thermistor 27 contacts the rear surface 24b of the heat equalizer plate 24 via the through-hole 25b.

[0045] The stay 26 is a support member that supports the heater holder 25. The stay 26 supports the heater holder 25 from the side opposite to the pressure roller 22, thereby suppressing deflection of the heater 23 due to the pressure force of the pressure roller 22 and obtaining a nip N with a uniform width. The material of the stay 26 is preferably an iron-based metal material such as SUS or SECC to ensure rigidity.

[0046] <Operation of the fixing device> The fixing device 20 according to the first embodiment of the present invention operates as follows.

[0047] When the image forming operation starts, pressure roller 22 starts to rotate in the direction of the arrow in Figure 2, and in response to this, fixing belt 21 is rotated. In addition, electricity is started to be supplied to heater 23, so that fixing belt 21 is heated. Then, when the temperature of fixing belt 21 reaches a predetermined target temperature, paper P carrying an unfixed image is transported to nip portion N between fixing belt 21 and pressure roller 22. As a result, the toner image on paper P is heated and pressurized, and fixed to paper P. Thereafter, paper P is discharged from nip portion N and transported to sheet discharge portion 400.

[0048] <Heater configuration> FIG. 3 is a plan view of the heater 23 according to the first embodiment of the present invention.

[0049] 3, the heater 23 according to the first embodiment of the present invention is a planar or plate-shaped heater extending in the X direction in the drawing. The heater 23 is disposed within the fixing belt 21 so that its longitudinal direction X is aligned with the longitudinal direction of the fixing belt 21. Note that the "longitudinal direction of the fixing belt 21" here refers to a direction along the outer circumferential surface of the fixing belt 21 that is perpendicular to the direction of rotation of the fixing belt 21. The heater 23 includes an elongated substrate 50, a resistance heating element 51, an insulating layer 52, an electrode portion 53, and a power supply line 54.

[0050] The resistance heating elements 51 are arranged at intervals along the longitudinal direction of the substrate 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 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. Therefore, from the viewpoint of suppressing temperature unevenness along the longitudinal direction, the gap is preferably 5 mm or less, more preferably 1 mm or less. Each resistance heating element 51 is connected to a pair of electrodes 53 via a power supply line 54. In the example shown in FIG. 3, the pair of electrodes 53 are provided at both longitudinal ends of the substrate 50, and each resistance heating element 51 is electrically connected in parallel to each electrode 53. The arrangement, number, and shape of the resistance heating elements 51, electrode 53, and power supply line 54 are not limited to the example shown in FIG. 3 and can be changed as appropriate.

[0051] The electrode portions 53 and the power supply lines 54 are provided on the same surface of the substrate 50 as the resistance heating elements 51. The power supply lines 54 are covered with an insulating layer 52, just like the resistance heating elements 51, to ensure insulation and durability. On the other hand, the electrode portions 53 are not covered with the insulating layer 52 and are exposed, as they are connected to connectors that serve as power supply members. When the connectors are connected to the electrode portions 53, the resistance heating elements 51 and the power source are electrically connected, enabling power to be supplied from the power source to each resistance heating element 51.

[0052] <Temperature control mechanism> FIG. 4 is a block diagram of a temperature control mechanism for the heater 23 according to the first embodiment of the present invention.

[0053] 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.

[0054] 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 excessive temperature rise provided to prevent an abnormal temperature rise in the heater 23. In the first embodiment of the present invention, the thermistor 27 is disposed at the longitudinal center and one longitudinal end of the heat generating region H of the heater 23, and the thermostat 28 is disposed at the other longitudinal end opposite the one longitudinal end of the heat generating region H. The arrangement and number of the thermistor 27 and the thermostat 28 are not limited to the example in FIG. 4 and can be changed as appropriate.

[0055] Each thermistor 27 contacts the heat equalizer plate 24 and detects the temperature of the heater 23 via the heat equalizer plate 24. Meanwhile, the thermostat 28 directly contacts the back surface 23a of the heater 23 through the hole 24a in the heat equalizer plate 24. This improves the responsiveness of the thermostat 28 to temperature changes in the heater 23. When the thermostat 28 detects an abnormal temperature rise in the heater 23, the thermostat 28 activates and cuts off power to the heater 23. However, the thermostat 28 may be configured to contact the heat equalizer plate 24, just like the thermistor 27.

[0056] The triac 10 is a current control means that controls the current duty from the AC power supply 30 to the heater 23 in response to instructions from the control unit 7. The "current duty" refers to the percentage of time current is applied to the heater 23 per control cycle. The control unit 7 is composed of a microcomputer that includes a CPU, ROM, RAM, I / O interface, etc. The control unit 7 outputs a control signal that controls the triac 10 based on the temperature detected by each thermistor 27, and the triac 10 controls the current duty based on the control signal, thereby maintaining the temperature of the heater 23 at a predetermined target temperature.

[0057] Next, the detailed configuration of the thermistor holder 29 will be described with reference to Figures 5(a) to 5(c). Figure 5(a) is a plan view of the thermistor holder 29, particularly the portion that holds the thermistor, Figure 5(b) is a side view, and Figure 5(c) is a cross-sectional view taken along line AA in Figure 5(a).

[0058] 5(a) to 5(c), the thermistor holder 29 has a pair of supporting portions 29b provided on both sides of the direction Y and extending across the direction Z, and a pair of supported portions 29c supported by each supporting portion 29b and extending across the direction Y. One end of the supported portion 29c in the direction Y is supported by the supporting portion 29b. The supporting portion 29b being provided across the direction Z or the supported portion 29c being provided across the direction Y means that these portions have a certain length in the direction Z or the direction Y, but this does not necessarily mean that they extend in a direction parallel to the direction Z or the direction Y, and they may be inclined relative to these directions.

[0059] A slit 29h is provided between the pair of supported portions 29c for arranging the harness 270 in the wiring space 29d within the thermistor holder 29. The slit 29h is linearly provided along the longitudinal direction when viewed from the Z direction, extending from one longitudinal end of the thermistor holder 29 to the other. A pair of biasing member mounting portions 29g is provided on both sides of the slit 29h. In other words, continuous gaps are provided between the longitudinal side portions of the pair of supported portions 29c, between the biasing member mounting portions 29g, and between the longitudinal side portions of the pair of supported portions 29c, and these continuous gaps are referred to as the slit 29h. The phrase "the slit 29h is provided along the longitudinal direction" does not necessarily mean that the slit 29h is provided in a direction parallel to the longitudinal direction, but rather means that the extension direction of the slit 29h has a longitudinal component when viewed from the Z direction.

[0060] As shown in FIG. 5(c), the biasing spring 31 is attached to the outer side of the pair of biasing member attachment portions 29g. The thermistor holder 29 is surrounded by the pair of supporting portions 29b and the pair of supported portions 29c and has a wiring space 29d that communicates with the slit 29h. In other words, the wiring space 29d is provided inside the thermistor holder 29 and is surrounded on both sides in the Y and Z directions, and communicates with the outside of the thermistor holder 29 via both sides in the X direction or the slit 29h. The harness 270 is disposed in the wiring space 29d through the slit 29h. In this embodiment, the biasing spring 31 is a coil spring. However, "surrounded" does not necessarily mean that the wiring space 29d is surrounded circumferentially; there may be a portion that is not surrounded by the portion on the Y or Z side other than the slit 29h.

[0061] FIG. 6 is a cross-sectional view showing the heater holder 25, thermistor 27, thermistor holder 29, etc., which corresponds to the cross-section of FIG. 5(c), and is a cross-sectional view seen from the right side of FIG.

[0062] As shown in FIG. 6, the thermistor holder 29 is assembled to the heater holder 25 and positioned relative to the heater holder 25. The thermistor holder 29 holds the thermistor 27 from the opposite side to the heater 23 (the upper side in FIG. 6). The thermistor holder 29 is biased toward the heater 23 by a biasing spring 31 serving as a biasing member. This biasing force causes the thermistor holder 29 to press (bias) the thermistor 27 in the direction of arrow B, and the heat-sensing element 271 of the thermistor 27 is pressed against the heat equalizer plate 24 via the insulating sheet 272. The heat equalizer plate 24 of this embodiment is a member to be detected that comes into contact with the thermistor 27 and whose temperature is detected. In other words, the thermistor 27 comes into contact with the heat equalizer plate 24 and detects its temperature, thereby indirectly detecting the temperatures of the heater 23 and the fixing belt. However, the heater 23 or the fixing belt may be a member to be directly brought into contact with the thermistor 27 so that the temperature thereof can be detected.

[0063] The heat-sensitive element 271 is attached to the base part 273 via an elastic body 275. The elastic body 275 has a curved surface that protrudes toward the heater 23, and the heat-sensitive element 271 is held at the top of this curved surface, that is, at the part of the elastic body 275 that protrudes most toward the heater 23. This allows the heat-sensitive element 271 to be properly abutted against the heat equalizing plate 24.

[0064] 7A to 7C are diagrams showing the thermistor 27, in which (a) is a plan view, (b) is a rear view, and (c) is a side view.

[0065] As shown in FIG. 7(a), the thermistor 27 includes a heat-sensitive element 271 as a temperature detection section, an insulating sheet 272 as an insulating section, a base section 273, a harness 274, an elastic body 275, and the like.

[0066] A base portion 273 holds the heat-sensitive element 271 via an elastic body 275. An insulating sheet 272 is wrapped 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 in this embodiment is a sponge.

[0067] As shown in FIG. 7(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 longitudinal end portion 273b of the thermistor 27 has a substantially T-shape with a first protrusion 273b1 and a second protrusion 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. The harness 270 shown in FIGS. 5 and 7 is a harness for a thermistor different from the thermistor 27 held by the thermistor holder 29 in FIG. 10, for example.

[0068] 7(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. As a result, the heat sensitive element 271 is pressed against the heat equalizing plate via the insulating sheet 272.

[0069] FIG. 8 is a perspective view showing the back side of heater holder 25, that is, the surface on which the thermistor 27 is attached. 8, the heater holder 25 has a pair of positioning ribs 25c1 and 25c2 and a positioning pin 25d. The positioning ribs 25c1 and 25c2 and the positioning pin 25d extend toward the rear surface side in the Z direction (upper side in FIG. 6).

[0070] FIG. 9 is a diagram showing a state in which thermistor 27 is attached to the rear side of heater holder 25. As shown in Fig. 9, one end 273b of base portion 273 of thermistor 27 is inserted and fitted between a pair of positioning ribs 25c1, 25c2 provided on heater holder 25. Furthermore, positioning pin 25d (see Fig. 8) is inserted into the inner hole of positioning cylindrical portion 273a of thermistor 27, and thermistor 27 is positioned in heater holder 25. Thermistor 27 is positioned with some play relative to heater holder 25. This allows thermistor 27 to move toward the heat equalizer plate when pressed by the thermistor holder, allowing the heat-sensitive element of thermistor 27 to properly abut against the heat equalizer plate.

[0071] Next, the structure of the thermistor holder 29 will be described with reference to the perspective view of FIG. 10, a pair of contact ribs 29a1 and 29a2 protruding in the thickness direction are provided on one end 29a of the thermistor holder 29. The pair of contact ribs 29a1 and 29a2 are spaced apart in the lateral direction.

[0072] Fig. 11 is a perspective view of the rear side of the thermistor holder 29 attached to the heater holder 25, and Fig. 12 is a rear view thereof. For convenience, in Figs. 11 and 12, the biasing spring 31 is shown as a cylindrical member.

[0073] 11 and 12, the thermistor holder 29 has a pair of contact ribs 29a1 and 29a2 protruding in the thickness direction at one end 29a. The pair of contact ribs 29a1 and 29a2 are arranged with a gap in the short direction. The thermistor holder 29 also has a pair of contact ribs 29e1 and 29e2 protruding in the thickness direction at the other end. The pair of contact ribs 29e1 and 29e2 are arranged with a gap in the short direction.

[0074] One longitudinal end 29a, which is the fitting portion of the thermistor holder 29, fits between a pair of positioning ribs 25c1, 25c2 of the heater holder 25. At this time, the abutment rib 29a1 of the thermistor holder 29 abuts against the positioning rib 25c1 of the heater holder 25, and the abutment rib 29a2 abuts against the positioning rib 25c2. It is not necessary to provide the abutment ribs 29a1, 29a2 that protrude in direction Z on the thermistor holder 29. Providing the abutment ribs 29a1, 29a2 adjacent to the positioning ribs 25c1, 25c2 is preferable because it further suppresses tilt of the thermistor holder 29 relative to the heater holder 25. Furthermore, the contact ribs 29a1, 29a2 in this embodiment are generally L-shaped with 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 abuts against the positioning ribs 25c1, 25c2 in the Y direction, and the contact ribs 29a1, 29a2 may be provided only in this portion. For convenience, only the portions of the contact ribs 29a1, 29a2 extending in the X direction are shown in Figure 6.

[0075] Furthermore, the positioning cylinder portion 273a of the thermistor 27 is inserted into the positioning hole 29f of the thermistor holder 29, and the positioning cylinder portion 273a is positioned in the positioning hole 29f with some play. In other words, the thermistor 27 is positioned relative to the thermistor holder 29. In this way, the positioning hole 29f and the positioning cylinder portion 273a are positions for the thermistor holder 29 and the thermistor 27.

[0076] Furthermore, the harness 270 is routed in the longitudinal direction, and is passed in the X direction through a wiring space below the support portion 29 of the thermistor holder 29, and the harness 270 penetrates the thermistor holder 29 in the X direction. This "passing in the X direction" does not necessarily mean that the harness 270 is wired strictly parallel to the X direction, but the harness 270 may also meander as shown in FIG.

[0077] When assembling a thermistor holder or the like for a fixing device, as shown in Figure 6, the thermistor holder 29 is attached to the heater holder 25, and then the harness 270 is routed through the slit 29h of the thermistor holder 29 into the wiring space 29d. Then, the biasing spring 31 is attached to the biasing member attachment portion 29g of the thermistor holder 29. This positions the biasing spring 31 above the slit 29h, preventing the harness 270 from slipping out of the slit 29h. The supported portion 29c is the portion where the biasing member attachment portion 29g is provided, and is biased in the direction of arrow B by the biasing spring 31 attached to the biasing member attachment portion 29g.

[0078] In the configuration of this embodiment, the harness 270 is stored (wired) through the slit 29h into the wiring space 29d, so that support portions 29b supporting the supported portion 29c and the biasing member attachment portion 29g can be provided on both sides in the direction Y. As a result, when the thermistor holder 29 is biased downward in FIG. 6 by the biasing spring 31, the support portions 29b support the biasing force on both sides in the direction Y, distributing the load and preventing the thermistor holder 29 from tilting relative to the heater holder 25. For example, in a configuration in which the harness 270 is passed through one side in the direction Y and wired into the wiring space 29d, the support portion 29b cannot be provided on the side where the harness 270 is wired, and the supported portion 29c and the biasing member attachment portion 29g are supported only by the support portion 29b on one side in the direction Y. Compared to such a configuration, in the present embodiment, tilting of the thermistor holder 29 can be prevented, and its posture can be maintained correctly. As a result, the thermistor holder 29 receives the biasing force of the biasing spring 31, and is able to bias the thermistor 27 downward in Figure 7, allowing the thermistor 27 to properly abut against the heat equalizer plate 24. Therefore, the thermistor 27 can properly detect the temperature of the heat equalizer plate 24, which is the member to be detected.

[0079] In particular, in this embodiment, as described above, the thermal element 271 is held at the top of the elastic body 275 that protrudes toward the heat equalizer plate 24, and the thermal element 271 is likely to tilt due to the tilt of the thermistor holder 29. Therefore, the configuration of this embodiment is suitable for suppressing the tilt of the thermistor holder 29.

[0080] The width C1 of the slit 29h in the direction Y shown in FIG. 13 can be set larger than the thickness (diameter) C2 of the harness 270. This makes it easier to pass the harness 270 through the slit 29h, improving assembly. Conversely, the width C1 can be set smaller than the thickness C2 of the harness 270. In this case, the thermistor holder 29 is deformed to widen the width C1 of the slit 29h, and the harness 270 is passed through the slit 29h. This configuration makes it difficult for the harness 270 to slip out of the slit 29h after wiring in the wiring space 29d. The above description of the size of the width C1 also applies to the slit 29h of various shapes described below. FIG. 13 shows the thermistor holder 29 before the biasing spring 31 is attached, and the width C1, diameter C3, and other dimensions refer to the width and diameter before the biasing spring 31 is attached.

[0081] Furthermore, the diameter C3 of the outer peripheral surface of the biasing member mounting portion 29g, which is the portion where the biasing spring 31 is mounted, can be set to be larger than the diameter C4 of the inner peripheral surface before the biasing spring 31 is assembled. In this case, by mounting the biasing spring 31 to the biasing member mounting portion 29g, a force acts from the biasing spring 31 on the biasing member mounting portion 29g in the direction of its inner diameter, preventing the biasing spring 31 from falling off the biasing member mounting portion 29g.

[0082] 13, by combining a configuration in which width C1 is larger than diameter C2 with a configuration in which diameter C3 is larger than diameter C4, it is possible to realize a configuration in which width C1 is larger than diameter C2 when harness 270 is passed through slit 29h, and by attaching biasing spring 31 to biasing member attaching portion 29g, the width corresponding to width C1 of slit 29h is narrowed and made smaller than diameter C2. This improves the ease of passing harness 270 through slit 29h and makes it difficult for harness 270 to slip out of slit 29h. However, these configurations do not necessarily have to be combined, and even when they are combined, the width corresponding to width C1 of slit 29h after biasing spring 31 is attached may be larger than diameter C2.

[0083] Next, modifications of the slit 29h will be described in order.

[0084] The slit 29h shown in Fig. 14 is linear when viewed from direction Z, and its extending direction J is inclined with respect to the longitudinal direction, which is the direction in which the harness is wired. This makes it difficult for the harness to come off the slit 29h. The extending direction of the slit 29h is the direction of a line connecting the center positions of the slit 29h in the width direction when viewed from direction Z. Alternatively, as shown in Fig. 15, the slit 29h may be made to meander. This makes it difficult for the harness to come off the slit 29h.

[0085] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0086] The resistance heating element 51 is not limited to a rectangular shape as shown in Fig. 3, but may also be a parallelogram as shown in Fig. 16, or a folded shape as shown in Fig. 17. Furthermore, as shown in Fig. 16 or 17, the pair of electrode portions 53 may be provided at either end of the substrate 50 in the longitudinal direction X of the heater 23.

[0087] The present invention is also suitable for a configuration including a fixing belt 21 that does not have an elastic layer, as shown in FIG. 18. The fixing belt 21 shown in FIG. 18 does not have an elastic layer, such as a rubber layer, between the surface layer (release layer) 212 and the substrate 210. Therefore, compared to fixing belts that have an elastic layer, the fixing belt 21 has lower insulation properties and better thermal conductivity from the heater to the fixing belt surface (outer circumferential surface). However, there is a tendency for the temperature of the fixing belt 21 to rise significantly in non-paper passing areas. For this reason, it is important to properly manage the temperature of the fixing belt 21 by appropriately detecting the temperature using a thermistor, and it is suitable to apply the heater holder 25, thermistor 27, and thermistor holder 29 of the above-described embodiment.

[0088] Furthermore, the present invention is applicable to fixing devices having the respective configurations shown in Figures 19 to 21 in addition to the fixing device 20 shown in Figure 2. The fixing devices having the respective configurations shown in Figures 19 to 21 will be described below. Note that in Figures 19 to 21, the same components as those in the fixing device 20 shown in Figure 2 are denoted by the same reference numerals as in Figure 2, and their description will be omitted.

[0089] In the fixing device 20 shown in FIG. 19, the heating nip N1 and the fixing nip N2 are formed in different positions. Specifically, two pressure rollers, one large and one small, 151 and 152, contact the fixing belt 21 from opposite sides to form the heating nip N1 and the fixing nip N2. That is, the pressure roller 151 on the left side of FIG. 19 contacts the heater 23 via the fixing belt 21 to form the heating nip N1, and the pressure roller 152 on the right side of FIG. 19 contacts the nip forming member 150 via the fixing belt 21 to form the fixing nip N2. In this case, when the heater 23 generates heat, the fixing belt 21 is heated in the heating nip N1. When a sheet of paper P enters the fixing nip N2, the unfixed image on the sheet of paper P is heated and pressurized, and the image is fixed to the sheet of paper P.

[0090] 20 is an example in which the pressure roller 151 on the left side of FIG. 19 is omitted, and the heater 23 is formed in an arc shape to match the curvature of the fixing belt 21. Other than that, it has the same configuration as the fixing device 20 shown in FIG. 19. 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, and therefore the fixing belt 21 is heated efficiently.

[0091] Next, the example shown in FIG. 21 is an example in which a pair of belts 161, 162 are arranged on either side of a central roller 163. In this case, the belt 161 on the left side of FIG. 21 is sandwiched between the heater 23 arranged inside it and the central roller 163, thereby forming a heating nip N1. Furthermore, the belt 162 on the right side of FIG. 21 is sandwiched between the nip forming member 153 arranged inside it and the central roller 163, thereby forming a fixing nip N2. In this case, when the heater 23 generates heat, the central roller 163 is heated in the heating nip N1. Furthermore, when a sheet of paper P enters the fixing nip N2, the unfixed image on the sheet of paper P is heated and pressurized, and the image is fixed to the sheet of paper P.

[0092] 19 to 21, the configurations of heater holder 25, thermistor 27, and thermistor holder 29 of the above-described embodiment can also be applied. This makes it possible to suppress tilting of thermistor holder 29, and maintain high detection accuracy of thermistor 27.

[0093] 22 includes an IH (electromagnetic induction heating) heater 63 as a means for heating the fixing belt 21. In addition to the IH heater 63, the fixing device 20 also includes the fixing belt 21, the pressure roller 22, the stay 26, the thermistor holder 29, a nip forming member 62, a sliding sheet 61, the thermistor 27, and a separating member 64 including a separating plate 64A and a separating claw 64B.

[0094] IH heater 63 is disposed outside fixing belt 21 and fixed to the image forming apparatus main body. IH heater 63 has coil 632, cores 633, 634, and 635, and coil holder 631. Coil holder 631 holds coil 632. When power is supplied to coil 632, a magnetic field is formed around coil 632, generating eddy currents in the metal belt substrate of fixing belt 21. When eddy currents are generated, Joule heat is generated due to the electrical resistance of the belt substrate, causing fixing belt 21 to heat up. Cores 633, 634, and 635 are made of a ferromagnetic material and form a magnetic path that allows the magnetic field (magnetic flux) generated by coil 632 to pass through.

[0095] The thermistor 27 is in contact with the inner circumferential surface of the fixing belt 21 and detects the temperature of the fixing belt 21 .

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

[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 thermistor 27.

[0098] 22, the thermistor 27 and thermistor holder 29 of the above-described embodiment can be applied, and the portion of the heater holder that holds thermistor holder 29 (see FIG. 8) can be applied to holder portion 26a of stay 26. This makes it possible to prevent thermistor holder 29 from tilting, thereby maintaining high detection accuracy of thermistor 27. However, the thermistor 27 of this embodiment differs from the above-described embodiment in that it detects the temperature of fixing belt 21 by contacting the inner circumferential surface of fixing belt 21 via stay 26.

[0099] 23 includes a halogen heater 65 as a means for heating the fixing belt 21. In addition to the halogen heater 65, the fixing device 20 also includes the fixing belt 21, the pressure roller 22, the stay 26, a nip forming member 66, a reflecting member 67, the 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, forming a fixing nip N between the fixing belt 21 and the pressure roller 22. In this case, because the halogen heater 65 is disposed inside the fixing belt 21 so as to face the nip forming member 66, infrared light emitted from the halogen heater 65 is irradiated onto the nip forming member 66. This heats the nip forming member 66, and the heat from the nip forming member 66 is transferred to the fixing belt 21 at the position of the nip N, thereby heating the fixing belt 21. The nip forming member 66 is preferably formed from a material with a higher thermal conductivity than the stay 26 so as to efficiently transfer heat to the fixing belt 21. Examples of materials for the nip forming member 66 include copper and aluminum.

[0101] Furthermore, a portion of the infrared light emitted from the halogen heater 65 is reflected by a reflecting member 67 disposed inside the fixing belt 21 to the nip forming member 66. This effectively heats the nip forming member 66. Furthermore, since the reflecting member 67 is interposed between the stay 26 and the halogen heater 65, the radiation of infrared light and the transfer of heat from the halogen heater 65 to the stay 26 are suppressed, resulting in an energy saving effect.

[0102] The thermistor 27 is in contact with the inner circumferential 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 thermistor 27.

[0104] 23, the thermistor 27 and thermistor holder 29 of the above-described embodiment can be applied, and the portion of the heater holder that holds thermistor holder 29 (see FIG. 8) can be applied to holder portion 26a of stay 26. This makes it possible to suppress tilting of thermistor holder 29, and maintain high detection accuracy of thermistor 27.

[0105] Furthermore, the image forming apparatus according to the present invention is not limited to the image forming apparatus shown in Fig. 1, but can also be applied to an image forming apparatus 100 as shown in Fig. 24. The configurations of other image forming apparatuses to which the present invention can be applied will be described below.

[0106] 24 includes an image forming means 80 including a photosensitive drum and the like, a paper transport section including a pair of timing rollers 81 and the like, a paper feeder 82, a fixing device 83, a paper discharge device 84, and a reading section 85. The paper feeder 82 includes multiple paper feed trays, each of which stores paper of a different size.

[0107] The reading unit 85 reads an image of the document Q. The reading unit 85 generates image data from the read image. The paper feeder 82 stores a plurality of sheets of paper P and sends the sheets of paper P to a conveyance path. The timing rollers 81 convey the sheets of paper P on the conveyance path to the image forming means 80.

[0108] The image forming means 80 forms a toner image on the paper P. Specifically, the image forming means 80 includes a photosensitive drum, a charging roller, an exposure device, a developing device, a replenishment device, a transfer roller, a cleaning device, and a discharging device. The fixing device 83 applies heat and pressure to the toner image to fix the toner image to the paper P. The paper P with the fixed toner image is transported to the paper discharge device 84 by a transport roller or the like. The paper discharge device 84 discharges the paper P outside the image forming apparatus 100.

[0109] Next, the configuration of the fixing device 83 shown in Fig. 24 will be described with reference to Fig. 25. In Fig. 25, components common to those of the fixing device 20 shown in Fig. 2 are denoted by the same reference numerals and will not be described again.

[0110] The fixing device 83 shown in FIG. 25 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 N is formed between the fixing belt 21 and the pressure roller 22. The nip width of the nip N is 10 mm, and the linear speed of the fixing device 83 is 240 mm / s.

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

[0113] The pressure roller 22 includes a core metal, an elastic layer, and a release layer. The pressure roller 22 has an outer diameter of 24 to 30 mm, and the elastic layer has a thickness of 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] 25, 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] 26, 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 resistance heating elements 51 are referred to as "divided regions," then, as shown in the enlarged view of FIG. 26, divided regions D are formed between the resistance heating elements 51 (although FIG. 26 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. 26, 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. 26, 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] 27, 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 surface 25f that is 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. 27. Furthermore, 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] 28, 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. 28). 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] 28 are belt holding members that are provided at 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. 29 is a diagram showing the arrangement of the temperature sensor 39 shown in FIG.

[0124] 29, 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] 29 and 30 , 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 in which the heat equalizer plate 24 is disposed is not limited to the entire heat generating region in the longitudinal direction X of the heater 23. For example, as shown in the example in FIG. 31 , the heat equalizer plate 24 may be disposed only in the divided region D between the resistance heating elements 51. Note that in FIG. 31 , the divided region D and the heat equalizer plate 24 are offset in the vertical direction in the drawing for convenience, but they are disposed at approximately the same position in the short-side direction Y of the heater 23. The heat equalizer plate 24 may be disposed over a part of the divided region D in the short-side direction Y of the heater 23, or may be disposed over the entire divided region D in the short-side direction Y of the heater 23. Furthermore, as shown in FIG. 32 , the heat equalizer plate 24 may be disposed not only in the divided region D between the resistance heating elements 51 but also across the resistance heating elements 51 on both sides of the divided region D. In other words, the heat equalizer plate 24 may be disposed so as to overlap at least a part of the resistance heating elements 51 on both sides of the divided region D. The heat equalizing plates 24 may be arranged in all divided regions D of the heater 23, or may be arranged in only some divided regions D as in the example shown in FIG.

[0127] By disposing the heat equalizing plate 24 in the divided region D of the heater 23, the heat conduction efficiency in the divided region D where the heat generation amount is small can be improved, and a temperature drop in the divided region D can be suppressed. This suppresses temperature unevenness in the heater 23 in the longitudinal direction, and temperature unevenness in the fixing belt 21 in the longitudinal direction. As a result, it is possible to suppress uneven fixing and glossiness of the image fixed to the paper. Furthermore, it is no longer necessary to increase the heat generation amount of the heater 23 in order to ensure sufficient fixing performance in the divided region D, thereby realizing energy savings in the fixing device. In particular, when the heat equalizing plate 24 is disposed over the entire heat generation region where the resistance heating element 51 is disposed, the heat conduction efficiency of the heater 23 can be improved over the entire region mainly heated by the heater 23 (i.e., the image formation region for the paper being fed), and temperature unevenness in the heater 23 and fixing belt 21 in the longitudinal direction can be suppressed.

[0128] Furthermore, the combination of the heat equalizer plate 24 and the resistance heating element 51 having PTC characteristics makes it possible to more effectively suppress excessive temperature rise in the non-passage areas where paper does not pass. PTC characteristics are a characteristic in which the resistance value increases as the temperature increases (when a constant voltage is applied, the heater output decreases). In other words, since the resistance heating element 51 has PTC characteristics, the amount of heat generated by the resistance heating element 51 in the non-passage areas can be effectively suppressed, and the heat amount in the non-passage areas can be dispersed by the heat equalizer plate 24, so the synergistic effect of these features makes it possible to effectively suppress excessive temperature rise in the non-passage areas.

[0129] Furthermore, since the temperature of the heater 23 tends to be lower not only in the divided region D but also in its surrounding area, the heat equalizer plate 24 may be disposed in the expanded divided region E including the divided region D and its surrounding area shown in Fig. 33. This improves the heat transfer efficiency in the expanded divided region E including the divided region D, and more effectively suppresses temperature unevenness in the longitudinal direction X of the heater 23.

[0130] Next, a further fixing device to which the present invention can be applied will be described.

[0131] In the fixing device 70 shown in Fig. 34, the heat equalizer 24 is composed of two layers of heat equalizer plates 48 and 49. That is, a first heat equalizer plate 48 that contacts the heater 23 and a second heat equalizer plate 49 that contacts the first heat equalizer plate 48 are provided. Note that the example shown in Fig. 34 also has a thermostat that contacts the heater 23, but Fig. 34 shows a cross section in which the thermistor and thermistor holder are not arranged.

[0132] The second heat equalizer 49 is made of a material having a higher thermal conductivity than the base material 50 of the heater 23, such as graphene or graphite. One example is a graphite sheet having a thickness of 1 mm. The second heat equalizer 49 may also be made of a plate material such as aluminum, copper, or silver.

[0133] 35, 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] 36, 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. 37 , 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. 37 , 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 short-side 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 short-side direction Y of the heater 23, or over the entire divided region D in the short-side 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 flaky powder. Graphene consists of a planar hexagonal lattice structure of carbon atoms, as shown in Figure 40. A graphene sheet is a sheet of graphene, typically a single layer. Graphene sheets may contain impurities in the single carbon layer, or may have a fullerene structure. Fullerene structures are generally recognized as compounds consisting of polycyclic rings in which the same number of carbon atoms are fused together in a cage-like fashion with five- and six-membered rings, 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. 41, 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. 37 . For example, as in the example shown in FIG. 38 , 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 which the resistance heating elements 51 are provided in the lateral direction Y of the heater 23. The second heat equalizer 49 may also be provided in a portion of the divided region D.

[0144] 39, 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. 39). That is, the gap 38 is provided as a heat insulating layer in a portion of the recess 25a (see FIG. 35) 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. 39) 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, suppressing heat transfer from the first heat equalizer 48 to the heater holder 25 and enabling 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. 39 ). 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] Furthermore, the first heat equalizer 48 and the second heat equalizer 49 do not necessarily have to be formed as separate bodies, but may be integral with each other. That is, the first heat equalizer 48 may also function as the second heat equalizer 49 by forming the portion of the first heat equalizer 48 corresponding to the divided region D to be thicker than the other portions.

[0147] 42 does not have a heat equalizing plate, and the thermistor 27 directly contacts the heater 23 through a through-hole 25b provided in the heater holder 25. The heater 23 is a planar heating element having a resistance heating element provided on a base material. The heater holder 25 is made of heat-resistant resin.

[0148] The above describes the configurations of a fixing device and an image forming apparatus to which the present invention can be applied, but by applying the present invention to such a fixing device and image forming apparatus, the same effects as those of the above embodiment can be obtained. That is, by applying the present invention, tilting of thermistor holder 29 can be suppressed, and the detection accuracy of thermistor 27 can be maintained at a high level.

[0149] Furthermore, the present invention is not limited to being applied to a fixing device, which is an example of a heating device, but can also be applied to heating devices other than fixing devices. For example, the present invention can be applied to heating devices such as a drying device that dries a liquid such as ink applied to paper, a laminator that thermocompresses a film as a covering member onto the surface of a sheet such as paper, and a heat sealer that thermocompresses a seal portion of a packaging material. This makes it possible to suppress tilting of the holding member.

[0150] The aspects of the present invention are as follows, for example. <1> A rotating member; A contact-type temperature detection element; a holding member for holding the temperature detecting member; an electric wire extending in a first direction; a biasing member that biases the temperature detecting member toward a detected member via the holding member, The direction in which the temperature detection member is biased and the opposite direction, which intersect with the first direction, are defined as a second direction, and the direction orthogonal to the first direction and which intersects with the second direction are defined as a third direction. the holding member has a pair of supporting portions that are arranged side by side in the third direction and that are arranged across the second direction, a pair of supported portions that are supported by the respective supporting portions and that are arranged across the third direction, and a wiring space that is surrounded by the pair of supporting portions and the pair of supported portions and that wires the electric wires; The heating device is characterized in that a slit is provided between the pair of supported parts in the first direction and communicates with the wiring space. <2> The extending direction of the slit is inclined with respect to the first direction. <1> The heating device described above. <3> The slit is provided in a serpentine shape. <1> The heating device described above. <4> The biasing member is attached to the holding member, When the biasing member is not attached to the holding member, the width of the slit is larger than the diameter of the electric wire. <1> from <3> The heating device according to any one of the preceding claims. <5> The width of the slit is smaller than the diameter of the electric wire. <1> from <4> The heating device according to any one of the preceding claims. <6> the biasing member is a coil spring, the holding member is provided on the supported portion and has a pair of biasing member mounting portions for mounting the biasing member, When the biasing member is not attached to the biasing member attachment portion, the outer diameter of the biasing member attachment portion is set to be larger than the inner diameter of the biasing member. <1> from <4> The heating device according to any one of the preceding claims. <7> When the biasing member is not attached to the biasing member attachment portion, the width of the slit is larger than the diameter of the electric wire, When the biasing member is attached to the biasing member attachment portion, the width of the slit is smaller than the diameter of the electric wire. <6> The heating device described above. <8> <1> from <7> A fixing device uses any one of the heating devices described above to heat a recording medium and fix an image on the recording medium to the recording medium. <9> <8> An image forming apparatus equipped with the fixing device described above. [Explanation of symbols]

[0151] 20 Fixing device (heating device) 21 Fixing belt (rotating member or fixing member) 22 pressure roller (opposing member or pressure member) 23 Heater (heating element) 24 Heat equalizing plate (high thermal conductivity material) 25 heater holder (heating element holding member) 27 Thermistor (temperature detection element) 271 Thermal element (temperature detection part) 29 Thermistor holder (holding member) 29b Support part 29c Supported part 29d Wiring space 29g Spring member mounting part 29h Slit 270 Harness (electrical wire) 1000 Image forming device B. Direction of biasing spring (direction of biasing member) J Slit extension direction X Longitudinal direction (first direction) Y Short side direction (third direction) Z 2nd direction [Prior art documents] [Patent documents]

[0152] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-186308

Claims

1. A rotating member; A contact-type temperature detection element; a holding member for holding the temperature detecting member; an electric wire extending in a first direction; a biasing member that biases the temperature detecting member toward a detected member via the holding 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 holding member has a pair of supporting portions that are arranged side by side in the third direction and that are arranged across the second direction, a pair of supported portions that are supported by the respective supporting portions and that are arranged across the third direction, and a wiring space that is surrounded by the pair of supporting portions and the pair of supported portions and that wires the electric wires; A heating device comprising a slit provided between the pair of supported portions in the first direction and communicating with the wiring space.

2. The heating device according to claim 1 , wherein the extending direction of the slit is inclined with respect to the first direction.

3. 2. The heating device according to claim 1, wherein the slit is provided in a serpentine pattern.

4. The biasing member is attached to the holding member, 2. The heating device according to claim 1, wherein the width of the slit is larger than the diameter of the electric wire when the biasing member is not attached to the holding member.

5. 2. The heating device according to claim 1, wherein the width of the slit is smaller than the diameter of the electric wire.

6. the biasing member is a coil spring, the holding member is provided on the supported portion and has a pair of biasing member mounting portions for mounting the biasing member, 2. The heating device according to claim 1, wherein the outer diameter of the biasing member mounting portion is larger than the inner diameter of the biasing member when the biasing member is not mounted on the biasing member mounting portion.

7. When the biasing member is not attached to the biasing member attachment portion, the width of the slit is larger than the diameter of the electric wire, 7. The heating device according to claim 6, wherein the width of the slit is smaller than the diameter of the electric wire when the biasing member is attached to the biasing member attachment portion.

8. A fixing device that uses the heating device according to claim 1 to heat a recording medium and fixes an image on the recording medium to the recording medium.

9. An image forming apparatus comprising the fixing device according to claim 8.

Images