Heating device, fixing device, image forming apparatus

Abstract

To sufficiently heat portion of a rotary member corresponding to division areas of resistance heating elements.SOLUTION: A fixing device 9 comprises: a fixing belt 20; a plane heater 22 that has a substrate 30 and resistance heating elements 31; and one or more thermistors 25 that each have a temperature detection element 25a. The resistance heating elements 31 are divided into more than one and arranged on the substrate 30. The temperature detection elements 25a are provided at positions corresponding to division areas B of the resistance heating elements 31 in the direction of arrangement of the plurality of resistance heating elements 31.SELECTED DRAWING: Figure 11

Description

Technical Field

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

Background Art

[0002] In a fixing device, a planar heater having a resistive heating element provided on a base material is provided as a heating member for heating a fixing belt as a rotating member. In such a fixing device, it is important to equalize the temperature of the fixing belt in its longitudinal direction (the arrangement direction of a plurality of resistive heating elements) and uniformly heat the toner on the recording medium.

[0003] For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2019-164328), a plurality of divided resistive heating elements are provided on a base material.

[0004] In a heating device, in a divided region between resistive heating elements, the amount of heat generated by the heating member becomes smaller than that in other portions. Therefore, there has been a problem that the fixing member (rotating member) is not sufficiently heated at a position corresponding to the divided region.

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to sufficiently heat a portion of the rotating member corresponding to a divided region between resistive heating elements.

Means for Solving the Problems

[0006] To solve the above problems, the present invention provides a heating device including a rotating member, a planar heating member having a base material and a plurality of resistive heating elements, and one or more temperature detection members having temperature detection elements, wherein the plurality of resistive heating elements are arranged on the base material at intervals, and the temperature detection element and a divided region between the resistive heating elements are provided at the same position in the arrangement direction of the plurality of resistive heating elements , further comprising a cutoff device having a thermally deformable member, wherein energization of the heating member is cut off by deformation of the thermally deformable member, and the cutoff device is provided at a position corresponding to the outside of the divided region of one of the resistance heating elements on both sides sandwiching the divided region where the temperature detection member is disposed in the arrangement direction of the plurality of resistance heating elements characterized in that.

Effects of the Invention

[0007] According to the heating device of the present invention, a portion of the rotating member corresponding to the divided region between the resistance heating elements can be sufficiently heated.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described based on the accompanying drawings. In each drawing for explaining the present invention, components such as members and constituent parts having the same function or shape are given the same reference numerals as much as possible, and the description thereof will be omitted after being described once. In the following description, as an example of a heating device, a fixing device for thermally fixing a toner image is exemplified.

[0010] FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

[0011] The image forming apparatus 100 shown in Fig. 1 includes four image forming units 1Y, 1M, 1C, and 1Bk that are detachable from the image forming apparatus main body. Each of the image forming units 1Y, 1M, 1C, and 1Bk has the same configuration except that they contain different color developers of yellow, magenta, cyan, and black. These color developers correspond to the color separation components of the color image. Each of the image forming units 1Y, 1M, 1C, and 1Bk includes a drum-shaped photoreceptor 2 as an image carrier, a charging device 3, a developing device 4, and a cleaning device 5. The charging device 3 charges the surface of the photoreceptor 2. The developing device 4 supplies toner as a developer to the surface of the photoreceptor 2 to form a toner image. The cleaning device 5 cleans the surface of the photoreceptor 2.

[0012] Further, the image forming apparatus 100 includes an exposure device 6, a paper feeding device 7, a transfer device 8, a fixing device 9, and a paper discharging device 10. The exposure device 6 exposes the surface of each photoreceptor 2 to form an electrostatic latent image on the surface. The paper feeding device 7 supplies a sheet of paper P as a recording medium to the paper conveyance path 14. The transfer device 8 transfers the toner image formed on each photoreceptor 2 to the sheet of paper P. The fixing device 9 fixes the toner image transferred to the sheet of paper P onto the surface of the sheet of paper P. The paper discharging device 10 discharges the sheet of paper P outside the apparatus. Each of the image forming units 1, the photoreceptor 2, the charging device 3, the exposure device 6, the transfer device 8, etc. constitutes an image forming means for forming an image on the paper.

[0013] The transfer device 8 includes an endless intermediate transfer belt 11 as an intermediate transfer member, four primary transfer rollers 12 as primary transfer members, and a secondary transfer roller 13 as a secondary transfer member. The intermediate transfer belt 11 is stretched by a plurality of rollers. The primary transfer roller 12 transfers the toner image on each photoreceptor 2 to the intermediate transfer belt 11. The secondary transfer roller 13 transfers the toner image transferred onto the intermediate transfer belt 11 to the paper P. The plurality of primary transfer rollers 12 are each in contact with the photoreceptor 2 via the intermediate transfer belt 11. As a result, the intermediate transfer belt 11 and each photoreceptor 2 are in contact with each other, and a primary transfer nip is formed therebetween. On the other hand, the secondary transfer roller 13 is in contact with one of the rollers that stretch the intermediate transfer belt 11 via the intermediate transfer belt 11. As a result, a secondary transfer nip is formed between the secondary transfer roller 13 and the intermediate transfer belt 11.

[0014] Also, a pair of timing rollers 15 are provided midway from the paper feeding device 7 to the secondary transfer nip (secondary transfer roller 13) in the paper conveyance path 14.

[0015] Next, the printing operation of the above image forming apparatus will be described with reference to FIG. 1.

[0016] When an instruction to start the printing operation is given, in each image forming unit 1Y, 1M, 1C, 1Bk, the photoreceptor 2 is rotationally driven clockwise in FIG. 1, and the surface of the photoreceptor 2 is charged to a uniform high potential by the charging device 3. Next, based on the image information of the document read by the document reading device or the print information instructed from the terminal for printing, the exposure device 6 exposes the surface of each photoreceptor 2. As a result, the potential of the exposed portion decreases and an electrostatic latent image is formed. Then, toner is supplied from the developing device 4 to this electrostatic latent image, and a toner image is formed on each photoreceptor 2.

[0017] The toner images formed on each photoreceptor 2 rotate as the photoreceptors 2 rotate and reach the primary transfer nip (the position of the primary transfer roller 12). Then, the toner images are sequentially transferred so as to overlap on the intermediate transfer belt 11 that is rotationally driven counterclockwise in FIG. 1. Then, the toner images transferred onto the intermediate transfer belt 11 are conveyed to the secondary transfer nip (the position of the secondary transfer roller 13) as the intermediate transfer belt 11 rotates. The toner images are transferred onto the sheet P conveyed to the secondary transfer nip. This sheet P is supplied from the paper feeder 7. The sheet P supplied from the paper feeder 7 is temporarily stopped by the timing roller 15 and then conveyed to the secondary transfer nip in accordance with the timing when the toner image on the intermediate transfer belt 11 reaches the secondary transfer nip. Thus, a full-color toner image is carried on the sheet P. Also, after the toner images are transferred, the toner remaining on each photoreceptor 2 is removed by each cleaning device 5.

[0018] The sheet P onto which the toner image has been transferred is conveyed to the fixing device 9, and the toner image is fixed to the sheet P by the fixing device 9. Thereafter, the sheet P is discharged outside the apparatus by the paper discharge device 10, and a series of printing operations is completed.

[0019] Subsequently, the configuration of the fixing device will be described.

[0020] As shown in FIG. 2, the fixing device 9 according to this embodiment includes a fixing belt 20 as a rotating member or a fixing member, a pressure roller 21 as an opposing rotating member or a pressing member, a heater 22 as a heating member, a heater holder 23 as a holding member, a stay 24 as a support member, a thermistor 25, and the like. The fixing belt 20 is formed of an endless belt. The pressure roller 21 contacts the outer peripheral surface of the fixing belt 20 and forms a fixing nip N therebetween. The heater 22 heats the fixing belt 20. The heater holder 23 holds the heater 22. The stay 24 supports the heater holder 23. The thermistor 25 contacts the back surface (the left surface in FIG. 2) of the base material 30 and detects the temperature of the base material 30. The direction orthogonal to the plane of FIG. 2 is the longitudinal direction of the fixing belt 20, the pressure roller 21, the heater 22, the heater holder 23, the stay 24, etc. Hereinafter, this direction will be simply referred to as the longitudinal direction. Note that this longitudinal direction is also the width direction of the conveyed paper, the belt width direction of the fixing belt 20, and the axial direction of the pressure roller 21.

[0021] The fixing belt 20 has, for example, a cylindrical base made of polyimide (PI) with an outer diameter of 25 mm and a thickness of 40 to 120 μm. On the outermost layer of the fixing belt 20, in order to enhance durability and ensure releasability, a release layer with a thickness of 5 to 50 μm made of a fluororesin such as PFA or PTFE is formed. An elastic layer made of rubber or the like with a thickness of 50 to 500 μm may be provided between the base and the release layer. Further, the base of the fixing belt 20 is not limited to polyimide, and may be a heat-resistant resin such as PEEK or a metal base such as nickel (Ni) or SUS. The inner peripheral surface of the fixing belt 20 may be coated with polyimide, PTFE, or the like as a sliding layer.

[0022] The pressure roller 21 has, for example, an outer diameter of 25 mm and is composed of a solid iron core 21a, an elastic layer 21b formed on the surface of the core 21a, and a release layer 21c formed outside the elastic layer 21b. The elastic layer 21b is formed of silicone rubber and has a thickness of, for example, 3.5 mm. On the surface of the elastic layer 21b, it is desirable to form a release layer 21c made of a fluororesin layer with a thickness of about 40 μm in order to enhance releasability.

[0023] The pressing roller 21 is biased toward the fixing belt 20 by the biasing means, so that the pressing roller 21 is pressed against the heater 22 via the fixing belt 20. Thereby, a fixing nip N is formed between the fixing belt 20 and the pressing roller 21. Further, the pressing roller 21 is configured to be rotationally driven by the driving means. When the pressing roller 21 rotates in the direction of the arrow in FIG. 2, the fixing belt 20 is driven to rotate accordingly.

[0024] The heater 22 is a planar heating member provided longitudinally across the width direction of the fixing belt 20. The heater 22 includes a plate-like base material 30, a resistance heating element 31 provided on the base material 30, an insulating layer 32 covering the resistance heating element 31, and the like. Further, the heater 22 is in contact with the inner peripheral surface of the fixing belt 20 on the insulating layer 32 side, and the heat generated from the resistance heating element 31 is transmitted to the fixing belt 20 through the insulating layer 32. In the present embodiment, the resistance heating element 31 and the insulating layer 32 are provided on the fixing belt 20 side (fixing nip N side) of the base material 30. Conversely, the resistance heating element 31 and the insulating layer 32 may be provided on the heater holder 23 side of the base material 30. In that case, since the heat of the resistance heating element 31 is transmitted to the fixing belt 20 through the base material 30, it is desirable that the base material 30 be made of a material having a high thermal conductivity such as aluminum nitride. Further, by forming the base material 30 of a material having a high thermal conductivity, even if the resistance heating element 31 is disposed on the side opposite to the fixing belt 20 side of the base material 30, it is possible to sufficiently heat the fixing belt 20.

[0025] The heater holder 23 and the stay 24 are disposed on the inner peripheral side of the fixing belt 20. The stay 24 is made of a metal channel material, and both end portions thereof are supported by both side plates of the fixing device 9. By supporting the heater holder 23 and the heater 22 by the stay 24, the heater 22 can surely receive the pressing force of the pressing roller 21 in a state where the pressing roller 21 is pressed against the fixing belt 20. Thereby, a fixing nip N is stably formed between the fixing belt 20 and the pressing roller 21. In the present embodiment, the thermal conductivity of the heater holder 23 is provided to be smaller than that of the base material 30.

[0026] Note that when the stay 24 supports the heater holder 23, it means that a portion of the stay 24 extending in the pressing direction (left - right direction in the figure) of the pressing roller 21, or a stay 24 having a thickness portion, abuts on the heater holder 23 from the side opposite to the pressing roller 21 (left side in the figure). Thereby, the deflection (in the longitudinal direction in particular in this embodiment) of the heater holder 23 due to the pressing force from the pressing roller 21 can be suppressed. However, the above - mentioned abutment is not limited to the case where the stay 24 directly abuts on the heater holder 23, but also includes the case where it abuts through other members. "Abutment through other members" means that in the left - right direction of the figure, another member is sandwiched between the stay 24 and the heater holder 23, and at least a part of it abuts on the other member at the corresponding position, and the other member abuts on the heater holder 23. Also, the above - mentioned extending in the pressing direction means not only the same direction as the pressing direction of the pressing roller 21, but also includes the case where it extends in a direction having a certain angle from the pressing direction of the pressing roller 21. Even in these cases, of course, the stay 24 can suppress the deflection of the heater holder 23 against the pressing force from the pressing roller 21.

[0027] Next, the above - mentioned method for calculating the thermal conductivity will be described. When calculating the thermal conductivity, first, the thermal diffusivity of the target object is measured, and the thermal conductivity is calculated using this thermal diffusivity.

[0028] The measurement of the thermal diffusivity was performed using a thermal diffusivity / thermal conductivity measuring device (trade name: ai - Phase Mobile 1u, manufactured by EyePhase Co., Ltd.).

[0029] In order to convert the above thermal diffusivity into thermal conductivity, the values of density and specific heat capacity are required. For the measurement of density, a dry automatic densitometer (trade name: Accupyc 1330, manufactured by Shimadzu Corporation) was used. Also, for the measurement of specific heat capacity, a differential scanning calorimeter (trade name: DSC-60, manufactured by Shimadzu Corporation) was used, and sapphire was used as a reference substance with a known specific heat capacity for the measurement. In this example, the specific heat capacity was measured 5 times, and the average value at 50 °C was used. If the density and specific heat capacity are denoted as ρ and C respectively, the thermal conductivity λ can be obtained from the thermal diffusivity α obtained in the above thermal diffusivity measurement by the following formula (1).

[0030]

Equation

[0031] Since the heater holder 23 is likely to become hot due to the heat of the heater 22, it is preferably formed of a heat-resistant material. For example, when the heater holder 23 is formed of a low-thermal-conductivity heat-resistant resin such as LCP, heat transfer from the heater 22 to the heater holder 23 is suppressed. Thereby, the heater 22 can efficiently heat the fixing belt 20.

[0032] Further, the heater holder 23 is provided with guide portions 26 for guiding the fixing belt 20. The guide portions 26 are provided on the upstream side (the lower side of the heater 22 in FIG. 2) and the downstream side (the upper side of the heater 22 in FIG. 2) in the belt rotation direction of the heater 22 respectively. Also, a plurality of guide portions 26 on the upstream side and the downstream side are arranged at intervals over the longitudinal direction of the heater 22. Each guide portion 26 is formed in a substantially fan shape and has an arcuate or convex curved surface-shaped belt facing surface 260 that extends in the belt circumferential direction so as to face the inner circumferential surface of the fixing belt 20.

[0033] The heater holder 23 has a plurality of openings 23a in the longitudinal direction. The openings 23a are openings that penetrate in the thickness direction of the heater holder 23. A thermistor 25 and a thermostat described later are provided in the openings 23a. These thermistor 25 and thermostat are pressed by a spring 29 and pressed against the back surface of the base material 30.

[0034] In the fixing device 9 according to the present embodiment, when the printing operation is started, the pressure roller 21 is rotationally driven, and the fixing belt 20 starts to rotate passively. At this time, the inner peripheral surface of the fixing belt 20 contacts the belt opposing surface 260 of the guide portion 26 and is guided, so that the fixing belt 20 rotates stably and smoothly. Further, the fixing belt 20 is heated by supplying power to the resistance heating element 31 of the heater 22. Then, in a state where the temperature of the fixing belt 20 reaches a predetermined target temperature (fixing temperature), as shown in FIG. 2, the sheet P carrying the unfixed toner image is conveyed between the fixing belt 20 and the pressure roller 21 (fixing nip N), so that the unfixed toner image is heated and pressed and fixed to the sheet P. The fixing belt 20 is a member to be heated that is heated by the heater 22.

[0035] FIG. 3 is a plan view of the heater according to the present embodiment.

[0036] As shown in FIG. 3, a plurality (four) of resistance heating elements 31, power supply lines 33A and 33B as conductors, a first electrode portion 34A, and a second electrode portion 34B are provided on the surface of the plate-shaped base material 30. However, the number of the resistance heating elements 31 is not limited to the present embodiment.

[0037] Incidentally, in this embodiment, the longitudinal direction of the heater 22 (the direction perpendicular to the plane of FIG. 2) is also the array direction X of the plurality of resistive heating elements 31 as shown in FIG. 3. Hereinafter, this direction will also be simply referred to as the array direction. Further, the vertical direction Y in FIG. 3, which is the direction intersecting the array direction (perpendicular in this embodiment) and different from the thickness direction of the base material 30, is referred to as the direction intersecting the array direction of the plurality of resistive heating elements 31, or simply as the array intersection direction. The array intersection direction Y is the direction along the surface of the base material 30 where the resistive heating elements 31 are provided, and is also the short-side direction of the heater 22 or the conveyance direction of the paper passed through the fixing device 9.

[0038] A plurality of resistive heating elements 31 constitute a heat generating portion 35 that is divided into a plurality in the array direction. Each resistive heating element 31 is electrically connected in parallel via power supply lines 33A and 33B to a pair of electrode portions 34A and 34B provided at one end of the base material 30 in the array direction (the left end in FIG. 3). The power supply lines 33A and 33B are made of a conductor having a resistance value smaller than that of the resistive heating element 31. From the viewpoint of ensuring the insulation between the resistive heating elements 31, the gap between adjacent resistive heating elements 31 is preferably 0.2 mm or more, and more preferably 0.4 mm or more. Also, if the gap between adjacent resistive heating elements 31 is too large, temperature drop is likely to occur in the gap portion. Therefore, from the viewpoint of suppressing temperature unevenness across the array direction, the gap is preferably 5 mm or less, and more preferably 1 mm or less.

[0039] The resistive heating element 31 is made of a material having PTC (positive temperature coefficient) characteristics, and has the feature that the resistance value increases (the heater output decreases) as the temperature rises.

[0040] Since the resistance heating element 31 has PTC characteristics and due to the configuration of the heating section 35 divided in the array direction, it is possible to suppress a phenomenon (hereinafter referred to as non-paper-passing section temperature rise) in which the temperature becomes higher in the heat generation region and non-paper-passing region by the heating section 35 than in the paper-passing region. This occurs when passing a sheet of paper with a paper-passing width shorter than the length of the heating section 35 (hereinafter referred to as a small-size sheet). That is, when passing a sheet of paper with a width smaller than the overall width of the heating section 35, the heat of the fixing belt 20 is not taken away by the sheet in the region outside the paper width, so the temperature of the resistance heating element 31 corresponding to that portion rises. That is, since the voltage applied to the resistance heating element 31 is constant, the temperature of the resistance heating element 31 outside the paper width rises, and its resistance value increases. At this time, if the resistance heating element 31 has PTC characteristics, the output (heat generation amount) of the resistance heating element 31 outside the paper width relatively decreases, and the end temperature rise is suppressed. Also, since a plurality of resistance heating elements 31 are electrically connected in parallel, it is possible to suppress the non-paper-passing section temperature rise while maintaining the printing speed. Note that the heating element constituting the heating section 35 may be other than a resistance heating element having PTC characteristics. Also, the resistance heating elements may be arranged in a plurality of rows in the direction intersecting the arrangement of the heaters 22. Here, the heating section 35 is set to a length corresponding to the maximum paper-passing width or an appropriate length corresponding to the width of a predetermined paper type. The predetermined paper type is, for example, a standard sheet such as A4 or B4.

[0041] The resistance heating element 31 can be formed, for example, by applying a paste prepared by blending silver palladium (AgPd), glass powder, etc. to the base material 30 by screen printing or the like and then firing the base material 30. In the present embodiment, the resistance value of the resistance heating element 31 is set to 80 Ω at room temperature. As the material of the resistance heating element 31, in addition to those described above, a resistance material such as silver alloy (AgPt) or ruthenium oxide (RuO2) may be used. The materials of the power supply line 33 and the electrode portion 34 can be formed by screen printing or the like using silver (Ag) or silver palladium (AgPd). The power supply line 33 is composed of a conductor having a resistance value smaller than that of the resistance heating element 31.

[0042] As the material of the base material 30, ceramics such as alumina and aluminum nitride, which are excellent in heat resistance and insulation, or non-metallic materials such as glass and mica are preferable. In the present embodiment, an alumina base material having a width of 8 mm in the array intersection direction, a width of 270 mm in the array direction, and a thickness of 1.0 mm is used. Alternatively, a base material 30 may be constituted by laminating an insulating material on a conductive material such as metal. As the metal material of the base material 30, aluminum, stainless steel, etc. are preferable because of their low cost. By configuring the base material 30 with a stainless steel plate, cracks due to thermal stress can be suppressed. Further, in order to improve the heat uniformity of the heater 22 and enhance the image quality, the base material 30 may be made of a material with high thermal conductivity such as copper, graphite, or graphene.

[0043] The insulating layer 32 is made of, for example, heat-resistant glass with a thickness of 75 μm. The insulating layer 32 covers the resistance heating element 31 and the power supply line 33, insulates and protects them, and maintains the slidability with the fixing belt 20.

[0044] FIG. 4 is a diagram showing a power supply circuit for the heater according to the present embodiment.

[0045] As shown in FIG. 4, in the present embodiment, a power supply circuit for supplying power to each resistance heating element 31 is configured by electrically connecting an AC power supply 200 and the electrode portions 34A and 34B of the heater 22. Further, a triac 210 for controlling the supplied power amount is provided in the power supply circuit. The control unit 220 controls the supplied power amount to each resistance heating element 31 via the triac 210 based on the detected temperature of the thermistor 25. The control unit 220 is composed of a microcomputer including a CPU, a ROM, a RAM, an I / O interface, etc. The control unit 220 may be provided in the fixing device 9 or may be provided in the main body of the image forming apparatus.

[0046] FIG. 23 shows an example of a specific configuration of the thermistor. As shown in FIG. 23, the thermistor 25 includes a temperature detection element 25a, a frame 25b, a lead wire 25c, a heat-resistant film 25d, etc.

[0047] The frame 25b is made of an insulating material, and in this embodiment, it is made of a resin material. An opening 25e, which is a hole passing through the frame 25b, is provided in the frame 25b.

[0048] The heat-sensitive element 25a is held at a position substantially in the center in the width direction of the opening 25e by a pair of lead wires extending from the inside of the frame 25b. The outer peripheral surface of the heat-sensitive element 25a is covered with infrared-absorbing glass. As the configuration of the heat-sensitive element, in addition to the configuration of this embodiment, known thermistors such as diode-type thermistors, bead-type thermistors, chip thermistors, and thin-film thermistors can be appropriately applied.

[0049] Two conducting wires 25c for supplying power to the thermistor 25 from the outside extend outward from one end side of the frame 25b. The conducting wires 25c are electrically connected to the heat-sensitive element 25a via a metal plate and lead wires provided inside the frame 25b.

[0050] The heat-resistant film 25d is attached to the bottom surface of the frame 25b (the surface on the back side of the paper in FIG. 23) and closes the bottom surface side of the opening 25e. The heat-resistant film 25d is made of, for example, polyimide resin.

[0051] Also, as shown in FIG. 4, the fixing device 9 has a thermostat 27 as a cutoff device. As shown in FIG. 24, the thermostat 27 includes a bimetal 27a as a heat-deformable member, a first lid member 27b, a base member 27c, a pressing pin 27d, a second lid member 27f, a fixed terminal 27g, and a pressed terminal 27h. The lower side of FIG. 24 is the heater 22 side (the right side in FIG. 2).

[0052] The first lid member 27b is an insulating member. The first lid member 27b is attached to the base member 27c so as to cover the heater-side portion of the base member 27c. A first space 27j is formed between the first lid member 27b and the base member 27c.

[0053] The bimetal 27a is composed of two metal materials with different coefficients of thermal expansion stacked together. However, if materials with different coefficients of thermal expansion are used, it is not necessarily limited to metal materials. For example, two plastic materials with different coefficients of thermal expansion, or a pair of a plastic material and a metal material, may be used to form the bimetal 27a.

[0054] The bimetal 27a is disposed in the first space 27j. As shown in FIG. 24, when the bimetal 27a is at or below a predetermined temperature, the bimetal 27a is convex toward the heater side.

[0055] A second lid member 27f is provided so as to cover a portion of the base member 27c on the side opposite to the heater side. A second space 27k is formed between the base member 27c and the second lid member 27f.

[0056] Inside the base member 27c, a through hole 27e that communicates the first space 27j and the second space 27k is provided. The pressing pin 27d is held by the base member 27c so as to be vertically movable within the through hole 27e.

[0057] A fixed terminal 27g and a pressed terminal 27h are provided in the second space 27k. The pressed terminal 27h can be opened and closed in the direction of the double arrow in FIG. 24 with the fulcrum 27h1 as the fulcrum. As shown in FIG. 24, one end of the pressed terminal 27h is in contact with the fixed terminal 27g, and the two are electrically connected.

[0058] The lower surface 27b1 of the first lid member 27b in FIG. 24 is a heat-sensitive surface and faces the heater. The bimetal 27a is heat-transferred from the heater through the first lid member 27b.

[0059] When excessive heat is generated due to a heater failure or the like, the temperature of the bimetal 27a rises and exceeds the predetermined temperature described above. As a result, the bimetal 27a thermally deforms convexly upward in FIG. 24. Thereby, the bimetal 27a presses one end side of the pressing pin 27d upward in FIG. 24. Then, the other end side of the pressing pin 27d further protrudes toward the second space 27k and presses the pressed terminal 27h. As a result, the pressed terminal 27h rotates with the fulcrum 27h1 as a fulcrum, and the pressed terminal 27h and the fixed terminal 27g are separated from each other. Thereby, the conduction state between the pressed terminal 27h and the fixed terminal 27g is released.

[0060] When the conduction state between the pressed terminal 27h and the fixed terminal 27g is released, the fixing device 9 cuts off the power supply to the heater 22. Thereby, excessive heating by the heater can be stopped.

[0061] In the present embodiment, the first electrode portion 34A and the second electrode portion 34B are provided on the same side in the arrangement direction, but they may be provided on different sides. Further, the resistance heating element 31 is not limited to the shape of the present embodiment. For example, as shown in FIG. 5, the resistance heating element 31 may be rectangular, or as shown in FIG. 6, the resistance heating element 31 may be composed of a linear portion, and this linear portion may be folded back to form a substantially parallelogram shape. Further, as shown in FIG. 5, the portion extending from the block-shaped resistance heating element 31 toward the power supply line 33, that is, the portion extending in the arrangement intersection direction, may be a part of the resistance heating element 31 or may be composed of the same material as the power supply line 33.

[0062] FIG. 7 is a diagram showing the temperature distribution in the arrangement direction of the fixing belt 20. FIG. (a) is a diagram showing the arrangement of the heater 22. FIG. (b) shows the temperature T of the fixing belt 20 on the vertical axis and represents each position in the arrangement direction of the fixing belt 20 on the horizontal axis.

[0063] As shown in FIGS. 7(a) and 7(b), a plurality of resistive heating elements 31 provided in the heater 22 are arranged at intervals. In other words, the plurality of resistive heating elements 31 are divided in the arrangement direction. And in the divided region B which is the portion between the resistive heating elements 31, the area occupied by the resistive heating elements 31 becomes smaller than other portions, and the heat generation amount becomes smaller. As a result, the temperature of the fixing belt 20 in the divided region B becomes lower than other portions, which causes temperature unevenness in the arrangement direction of the fixing belt 20. Also, in the enlarged divided region C including the region around the divided region B, the temperatures of the heater 22 and the fixing belt 20 become lower. Note that the temperature of the heater 22 also becomes lower in the divided region B in the same manner. Here, as shown in the enlarged view of FIG. 7(a), the divided region B means an arrangement direction region including the entire portion where the resistive heating elements 31, which are the main heat generating portions of the heater 22, are divided in the arrangement direction. Also, in addition to the divided region B, a region including a range corresponding to the connection portion 311 of the resistive heating element 31 is defined as the enlarged divided region C. This connection portion 311 refers to the portion of the resistive heating element 31 that extends in the arrangement intersection direction and is connected to each of the power supply lines 33A and 33B.

[0064] As shown in FIG. 8, also in the heater 22 having the rectangular resistive heating element 31 shown in FIG. 5, the temperature of the divided region B becomes lower than other portions. Also in the heater 22 having the resistive heating element 31 of the shape shown in FIG. 9, the temperature of the divided region B becomes lower than other portions. Further, as shown in FIG. 10, also in the heater 22 having the resistive heating element 31 of the shape shown in FIG. 6, the temperature of the divided region B becomes lower than other portions. However, as shown in FIGS. 7, 9, and 10, by overlapping adjacent resistive heating elements 31 in the arrangement direction, the temperature drop of the divided region B with respect to other portions can be suppressed.

[0065] Thus, at the position corresponding to the divided area B in the array direction, the temperature of the fixing belt 20 drops compared to other parts. Therefore, even when the fixing belt 20 reaches the fixing temperature and the fixing operation starts in other parts, the temperature of the fixing belt 20 does not reach the fixing temperature at the position corresponding to the divided area B, and there is a possibility that the toner image on the paper P cannot be sufficiently heated at the position corresponding to the divided area B. Also, this may cause fixing offset.

[0066] Therefore, in this embodiment, as shown in FIG. 11, in the array direction, the temperature detection element 25a of the thermistor 25A as the temperature detection member is provided at the position corresponding to the divided area B. Also, the temperature detection element 25a of the thermistor 25B as another temperature detection member is arranged outside the divided area. More specifically, all of the respective temperature detection elements 25a are arranged at the position corresponding to the divided area B. Note that arranging at the corresponding position means arranging at the same position in the array direction X of the plurality of resistance heating elements.

[0067] In this way, by arranging the temperature detection element 25a of the thermistor 25A at the position corresponding to the divided area, the temperature of the portion where the temperature is particularly low in the heater 22 can be detected. Therefore, by the control unit performing energization control of the heater 22 based on the detection result of the thermistor 25A, heating by the heater 22 can be continued until the divided area B of the heater 22 reaches a sufficient temperature, that is, until the divided area B of the fixing belt 20 reaches the fixing temperature. In this way, in this embodiment, by deliberately arranging the temperature detection element 25a of the thermistor 25A at the position corresponding to the divided area B where the area of the resistance heating element 31 is smaller than other parts in the array direction of the heater 22, the fixing belt 20 in the divided area B can be heated to a sufficient temperature. Therefore, the above-mentioned fixing offset can be prevented.

[0068] Particularly in the present embodiment, the temperature detection element 25a of the thermistor 25A is arranged at a position corresponding to the split region B on the center side in the arrangement direction, which is the middle of the three split regions B. Separately from the thermistor 25A, the temperature detection element 25a of the thermistor 25B is arranged outside the split region B in the arrangement direction. In other words, the temperature detection element 25a of the thermistor 25B is arranged at a position different from the split region B in the arrangement direction. The temperature detection element 25a of the thermistor 25B is provided at a position facing the resistance heating element 31 on the end side in the arrangement direction. In other words, the temperature detection element 25a of the thermistor 25B is arranged on the end side with respect to the central position D0 of the heat generation region D of the heater 22, rather than the temperature detection element 25a of the thermistor 25A. The heat generation region D of the heater 22 is the main heat generation region of the heater 22 and is the region where the resistance heating element 35 in the arrangement direction is arranged. However, this heat generation region D also includes the split region B.

[0069] By providing the thermistor 25B for detecting outside the split region B, the temperature of the relatively high-temperature part of the heater 22 can be detected. Therefore, based on the detection result of the thermistor 25B, by performing energization control of the heater 22, overheating of the fixing belt 20 can be suppressed.

[0070] Also, particularly in the present embodiment, the temperature detection element 25a of the thermistor 25A is arranged at a position corresponding to the split region B on the center side in the arrangement direction. In other words, the temperature detection element 25a of the thermistor 25A is arranged on the center side of the heat generation region D in the arrangement direction, rather than the temperature detection element 25a of the thermistor 25B. Thereby, since the temperature of the region where the temperature becomes low can be detected on the center side, which is particularly important for the image fixing property, it is suitable from the viewpoint of ensuring the fixing property of the fixing device 9. Also, by the thermistor 25B detecting the temperature outside the split region B of the resistance heating element 31 on the end side in the arrangement direction, overheating of the end side in the arrangement direction of the fixing belt 20 during passage of small-size paper can be effectively suppressed.

[0071] Also, in the heater 22 having an even number (four in this embodiment) of resistance heating elements 31 as in this embodiment, by providing the temperature detection element 25a of the thermistor 25A at a position corresponding to the central division region B among the odd number (three in this embodiment) of division regions B, it is possible to detect the temperature of the region where the temperature decreases particularly on the central side, which is important for the image fixing property. Therefore, it is preferable from the viewpoint of ensuring the fixing property of the fixing device 9. Further, by providing the temperature detection element 25a of the thermistor 25B at a position corresponding to the two resistance heating elements 35 sandwiching the central division region B, that is, the resistance heating elements 35 other than the two inner resistance heating elements 35 among the four, it is possible to effectively suppress the over-temperature on the end side in the arrangement direction of the fixing belt 20 when passing a small-sized paper.

[0072] Also, in this embodiment, the thermostat 27 is provided at a position corresponding to the second resistance heating element 31 from the right in FIG. 11 in the arrangement direction. That is, at a position corresponding to either one (the second from the right in this embodiment) of the resistance heating elements 31 on both sides sandwiching the division region B where the temperature detection element 25a of the thermistor 25A is arranged, and at a position corresponding to the outside of the division region B, the thermostat 27 is arranged. In this way, by arranging the thermistor 25A at a position corresponding to the division region B, there is a space margin outside the division region B, so it becomes possible to arrange the thermistor 25A and the thermostat 27 corresponding to the same resistance heating element 31 (the second resistance heating element 31 from the right in FIG. 11 in this embodiment). Therefore, when it is desired to arrange a thermistor and a thermostat corresponding to the same resistance heating element 31 for reasons of space or temperature detection, the arrangement of the thermistor 25A in this embodiment is advantageous for arranging the thermostat 27.

[0073] However, the arrangements of the above thermistors 25A and 25B and the thermostat 27 are merely examples, and the number and arrangements thereof are not limited thereto. For example, contrary to FIG. 11, the temperature detection element 25a of the thermistor 25A can be arranged at a position corresponding to the divided region B on the end side in the arrangement direction, and the temperature detection element 25a of the thermistor 25B can be provided at a position corresponding to the resistance heating element 31 on the central side in the arrangement direction. When passing a sheet of large-size paper or the like (for example, a sheet other than A4 paper), since the temperature tends to be lower on the end side in the arrangement direction of the fixing belt 20, by arranging the temperature detection element 25a at a position corresponding to the divided region B on the end side in the arrangement direction, the end side in the arrangement direction of the fixing belt 20 can be sufficiently heated when passing a large-size paper or the like. Therefore, the hot offset on the end side in the arrangement direction can be effectively suppressed. Further, by providing the temperature detection element 25a at a position corresponding to the resistance heating element 31 on the central side in the arrangement direction, the temperature outside the divided region on the central side where the temperature tends to be higher can be detected, which is advantageous from the viewpoint of the safety of the fixing device 9. Further, only the temperature detection member in which the temperature detection element is arranged at a position corresponding to the divided region may be provided, or three or more temperature detection members may be provided. Further, the temperature detection element of the temperature detection member may be arranged at a position corresponding to the divided region B on the end side in the arrangement direction, or the temperature detection element of another temperature detection member may be arranged at a position corresponding to the outside of the divided region B of the resistance heating element 31 on the central side in the arrangement direction. Further, a plurality of cutoff devices may be provided, or from the viewpoint of suppressing the over-temperature rise of the fixing belt 20 due to the end temperature rise during passing of the small-size paper, a cutoff device may be provided on the end side in the arrangement direction.

[0074] Further, the arrangement of the thermistors in the arrangement crossing direction is not limited thereto. For example, as shown in FIG. 12, in the present embodiment, the thermistor 25 is provided on the upstream side in the rotation direction of the fixing belt 20 from the central position NA of the fixing nip N in the arrangement crossing direction, in other words, on the inlet side of the fixing nip N. Since the inlet side of the fixing nip N is a region particularly likely to be deprived of heat by the sheet P, by the thermistor 25 detecting the temperature of this portion, the fixability of the fixing device 9 can be ensured and the above-described fixing offset can be effectively suppressed.

[0075] As described above, embodiments of the present invention have been explained. However, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0076] In addition to the above-described fixing device, the present invention is also applicable to a fixing device as shown in FIGS. 13 to 15. Hereinafter, the configurations of the respective fixing devices shown in FIGS. 13 to 15 will be briefly described.

[0077] First, in the fixing device 9 shown in FIG. 13, a pressing roller 44 is disposed on the side opposite to the pressure roller 21 with respect to the fixing belt 20. The pressing roller 44 is an opposing rotating member that rotates facing the fixing belt 20 as a rotating member. The pressing roller 44 and the heater 22 are configured to heat the fixing belt 20 therebetween. On the other hand, on the pressure roller 21 side, a nip forming member 45 is disposed on the inner circumference of the fixing belt 20. The nip forming member 45 is supported by a stay 24. The nip forming member 45 and the pressure roller 21 form a fixing nip N by sandwiching the fixing belt 20.

[0078] Next, in the fixing device 9 shown in FIG. 14, the above-described pressing roller 44 is omitted, and the heater 22 is formed in an arc shape in accordance with the curvature of the fixing belt 20 in order to secure the circumferential contact length between the fixing belt 20 and the heater 22. Otherwise, the configuration is the same as that of the fixing device 9 shown in FIG. 13.

[0079] Finally, the fixing device 9 shown in FIG. 15 will be described. The fixing device 9 includes a heating assembly 92, a fixing roller 93 as a fixing member, and a pressure assembly 94 as an opposing member. The heating assembly 92 includes a heater 22, a heater holder 23, a stay 24, a heating belt 120 as a rotating member, etc., which were described in the previous embodiment. The fixing roller 93 is an opposing rotating member that rotates facing the heating belt 120 as a rotating member. Further, the fixing roller 93 is composed of a solid iron core 93a, an elastic layer 93b formed on the surface of this core 93a, and a release layer 93c formed outside the elastic layer 93b. Also, a pressure assembly 94 is provided on the side of the fixing roller 93 opposite to the heating assembly 92 side. The pressure assembly 94 arranges a nip forming member 95 and a stay 96, and rotatably arranges a pressure belt 97 so as to enclose these nip forming member 95 and stay 96. Then, the paper P is passed through the fixing nip N2 between the pressure belt 97 and the fixing roller 93 and heated and pressed to fix the image.

[0080] Also, in the fixing devices of FIGS. 13 to 15 above, the point that the heat generation amount of the heater 22 becomes small in the division region B between the resistance heating elements 31 of the heater 22 is the same. Therefore, similar to the above-described embodiment, by providing the temperature detection element of the temperature detection member at the position corresponding to the division region B of the heater 22, the portion corresponding to the division region of the rotating member can be sufficiently heated. Thereby, the fixability of the image can be sufficiently ensured, and the occurrence of problems such as fixing offset can be prevented.

[0081] Further, the present invention is not limited to the fixing device as described in the above embodiment, and is also applicable to a drying device for drying the ink applied to the paper, and further to a heating device such as a laminator for thermally pressing a film as a covering member onto the surface of a sheet such as paper, or a heat sealer for thermally pressing the seal portion of a packaging material. By applying the present invention to such a device, the portion corresponding to the division region of the rotating member can be sufficiently heated.

[0082] The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIG. 1, and may be a monochrome image forming apparatus, a copying machine, a printer, a facsimile machine, or a multifunction machine thereof.

[0083] For example, as shown in FIG. 16, the image forming apparatus 100 of the present embodiment includes an image forming unit 50 including a photoreceptor drum, a paper conveyance unit including a pair of timing rollers 15, a paper feeding device 7, a fixing device 9, a paper discharging device 10, and a reading unit 51. The paper feeding device 7 includes a plurality of paper feeding trays, and each paper feeding tray accommodates papers of different sizes.

[0084] The reading unit 51 reads the image of the document Q. The reading unit 51 generates image data from the read image. The paper feeding device 7 accommodates a plurality of papers P and sends out the papers P to the conveyance path. The timing roller 15 conveys the paper P on the conveyance path to the image forming unit 50.

[0085] The image forming unit 50 forms a toner image on the paper P. Specifically, the image forming unit 50 includes a photoreceptor drum, a charging roller, an exposure device, a developing device, a replenishing device, a transfer roller, a cleaning device, and a discharging device. The toner image shows, for example, the image of the document Q. The fixing device 9 heats and presses the toner image to fix the toner image on the paper P. The paper P with the fixed toner image is conveyed to the paper discharging device 10 by a conveyance roller or the like. The paper discharging device 10 discharges the paper P to the outside of the image forming apparatus 100.

[0086] Next, the fixing device 9 of the present embodiment will be described. The description of the configuration common to the fixing device of the above-described embodiment will be omitted as appropriate.

[0087] As shown in FIG. 17, the fixing device 9 includes a fixing belt 20, a pressure roller 21, a heater 22, a heater holder 23, a stay 24, a thermistor 25, and the like.

[0088] A fixing nip N is formed between the fixing belt 20 and the pressure roller 21. The nip width of the fixing nip N is 10 mm, and the linear speed of the fixing device 9 is 240 mm / s.

[0089] The fixing belt 20 includes a polyimide substrate and a release layer, and does not have an elastic layer. The release layer is made of a heat-resistant film material made of, for example, a fluororesin. The outer diameter of the fixing belt 20 is about 24 mm.

[0090] The pressure roller 21 includes a core metal 21a, an elastic layer 21b, and a release layer 21c. The outer diameter of the pressure roller 21 is formed to be 24 to 30 mm, and the thickness of the elastic layer 21b is formed to be 3 to 4 mm.

[0091] The heater 22 includes a base material, a heat insulating layer, a conductor layer including a resistance heating element, etc., and an insulating layer, and the overall thickness is formed to be 1 mm. Also, the width Y in the array intersection direction of the heater 22 is 13 mm.

[0092] As shown in FIG. 18, the conductor layer of the heater 22 includes a plurality of resistance heating elements 31, a power supply line 33, and electrode portions 34A to 34C. Also in this embodiment, as shown in the enlarged view of FIG. 18, a divided region B in which a plurality of resistance heating elements 31 are divided in the array direction is formed. However, in FIG. 18, only the divided region B within the range of the enlarged view is shown, but actually a divided region is provided between all the resistance heating elements 31. The resistance heating elements 31 constitute three heating portions 35A to 35C. By energizing the electrode portions 34A and 34B, the heating portions 35A and 35C generate heat. By energizing the electrode portions 34A and 34C, the heating portion 35B generates heat. For example, when performing a fixing operation on small-sized paper, the heating portion 35B can be made to generate heat, and when performing a fixing operation on large-sized paper, all the heating portions can be made to generate heat.

[0093] As shown in FIG. 19, the heater holder 23 holds the heater 22 in its recess 23b. The recess 23b is provided on the heater 22 side of the heater holder 23. The recess 23b includes a surface 23b1 substantially parallel to the base material 30 that is recessed toward the stay 24 side from the other surface of the heater 22, a wall portion 23b2 provided inside the heater holder 23 on both sides in the arrangement direction of the heater holder 23 (either one side is also acceptable), and a wall portion 23b3 provided inside the heater holder 23 on both sides in the arrangement intersection direction. The heater holder 23 has a guide portion 26. The heater holder 23 is formed of LCP (liquid crystal polymer).

[0094] As shown in FIG. 20, the connector 60 includes a resin housing (e.g., LCP) and a plurality of contact terminals provided inside the housing.

[0095] The connector 60 is attached so as to sandwich the heater 22 and the heater holder 23 together from the front side and the back side. In this state, each contact terminal contacts (presses) each electrode portion of the heater 22, so that the heat generating portion 35 and the power supply provided in the image forming apparatus are electrically connected via the connector 60. As a result, power can be supplied from the power supply to the heat generating portion 35. Note that at least a part of each electrode portion 34 is not covered by the insulating layer and is in an exposed state in order to ensure connection with the connector 60.

[0096] The flanges 53 are provided on both sides in the arrangement direction of the fixing belt 20 and hold both ends of the fixing belt 20 from the inside of the belt. The flanges 53 are fixed to the housing of the fixing device 9. The flanges 53 are inserted into both ends of the stay 24 (refer to the arrow direction from the flange 53 in FIG. 20).

[0097] The attachment direction of the heater 22 and the heater holder 23 to the connector 60 is the direction in which the heater arrays intersect. This direction in which the arrays intersect is the direction of the arrow from the connector 60 in FIG. 20. When attaching the heater holder 23 to the connector 60, a convex portion provided on one of the connector 60 and the heater holder 23 may engage with a concave portion provided on the other, and the convex portion may be configured to move relative to the inside of the concave portion. Further, the connector 60 is attached to the heater 22 and the heater holder 23 on one side in the array direction and on the side opposite to the side where the drive motor of the pressure roller 21 is provided.

[0098] As shown in FIG. 21, thermistors 25 are provided on the central side and the end side in the array direction of the fixing belt 20, respectively, facing the inner peripheral surface of the fixing belt 20. The heater 22 is controlled based on the temperatures on the central side and the end side in the array direction of the fixing belt 20 detected by the thermistors 25. Note that one of these thermistors 25 is provided at a position corresponding to the divided region between the resistance heating elements of the heater 22, similar to the above-described embodiment.

[0099] Thermostats 27 are provided on the central side and the end side in the array direction of the fixing belt 20, respectively, facing the inner peripheral surface of the fixing belt 20. When the temperature of the fixing belt 20 detected by the thermostat 27 exceeds a predetermined threshold value, the power supply to the heater 22 is stopped.

[0100] Flanges 53 for holding the respective ends of the fixing belt 20 are provided at both ends in the array direction of the fixing belt 20. The flange 53 is formed of LCP (liquid crystal polymer).

[0101] As shown in FIG. 22, a slide groove 53a is provided in the flange 53. The slide groove 53a extends in the direction of approaching and separating from the pressure roller 21 of the fixing belt 20. An engaging portion of the housing of the fixing device 9 engages with the slide groove 53a. By the relative movement of this engaging portion within the slide groove 53a, the fixing belt 20 can move in the direction of approaching and separating from the pressure roller 21.

[0102] Also in the above fixing device 9, by providing the temperature detection element of the thermistor 25 at a position corresponding to the divided region B of the heater 22, the portion corresponding to the divided region of the fixing belt 20 can be sufficiently heated. Thereby, the fixability of the image can be sufficiently ensured, and the occurrence of defects such as fixing offset can be prevented.

[0103] Particularly in the case of an image forming apparatus that performs an image forming operation using a single-color toner, hot offset is less likely to occur compared to an image forming apparatus that performs an image forming operation using a multi-color toner. Therefore, even if the heating member is controlled based on the detection result of the temperature detection element arranged at a position corresponding to the divided region as in the present invention, there is an advantage that hot offset is less likely to occur in an image forming apparatus that uses a single-color toner.

[0104] Examples of the recording medium include paper P (plain paper), cardboard, postcards, envelopes, thin paper, coated paper (such as coated paper and art paper), tracing paper, OHP sheets, plastic films, prepregs, copper foils, etc.

Explanation of Reference Numerals

[0105] 1 Image forming apparatus 9 Fixing device (heating device) 20 Fixing belt (rotating member or fixing member) 21 Pressing roller (opposing rotating member or pressing member) 22 Heater (heating member) 23 Heater holder (holding member) 24 Stay (supporting member) 25A Thermistor (temperature detection member) 25B Thermistor (other temperature detection member) 25a Temperature detection element 27 Thermostat (cut-off device) 30 Base material 31 Resistance heating element 35 Heating portion 220 Control portion B Divided region D Heating region of heater N Fixing nip (nip portion) Array direction of a plurality of resistive heating elements Array intersection direction

Prior Art Documents

Patent Documents

[0106]

Patent Document 1

Claims

1. A rotating member, A planar heating member having a base material and a plurality of resistance heating elements, One or a plurality of temperature detection members having a temperature detection element, and a heating device comprising: The plurality of resistance heating elements are arranged at intervals on the base material, The temperature detection element and the divided region between the resistance heating elements are provided at the same position in the arrangement direction of the plurality of resistance heating elements, Further comprising a cutoff device having a thermal deformation member, The energization to the heating member is cut off by the deformation of the thermal deformation member, The cutoff device is provided at a position corresponding to the outside of the divided region of one of the resistance heating elements on both sides sandwiching the divided region where the temperature detection member is arranged in the arrangement direction of the plurality of resistance heating elements. A heating device characterized by that.

2. The heating device according to claim 1, wherein the thermal deformation member is a bimetal.

3. A rotating member, A planar heating member having a base material and a plurality of resistance heating elements, One or a plurality of temperature detection members having a temperature detection element, and a heating device comprising: The plurality of resistance heating elements are arranged at intervals on the base material, The temperature detection element and the divided region between the resistance heating elements are provided at the same position in the arrangement direction of the plurality of resistance heating elements, Further comprising another temperature detection member having a temperature detection element, The temperature detection element of the other temperature detection member is provided at a position different from the divided region between the resistance heating elements at a position facing the resistance heating element in the arrangement direction of the plurality of resistance heating elements. A heating device characterized by that.

4. The heating device according to claim 3, wherein the temperature detection element of the other temperature detection member is arranged on the end side of the heat generation region of the heating member in the arrangement direction of the plurality of resistance heating elements rather than the temperature detection element of the temperature detection member.

5. A rotating member, A planar heating member having a base material and a plurality of resistance heating elements, One or a plurality of temperature detection members having a temperature detection element, and a heating device comprising: The plurality of resistance heating elements are arranged at intervals on the base material, The temperature detection element and the divided region between the resistance heating elements are provided at the same position in the arrangement direction of the plurality of resistance heating elements, When there are an even number of the resistance heating elements in the arrangement direction of the plurality of resistance heating elements, the temperature detection element of the temperature detection member is arranged at the same position as the central divided region in the arrangement direction of the plurality of resistance heating elements among the plurality of divided regions. Comprising another temperature detection member having a temperature detection element, The temperature detection element of the other temperature detection member is provided at a position facing the resistance heating elements in the arrangement direction of the plurality of resistance heating elements, at a position different from the divided regions between the resistance heating elements, A heating device characterized in that the temperature detection element of the other temperature detection member is arranged at the same position as any one of the resistance heating elements other than the two resistance heating elements sandwiching the central divided region.

6. When the resistance heating elements are even in number in the arrangement direction of the plurality of resistance heating elements, the temperature detection element of the temperature detection member is arranged at the same position as the central divided region in the arrangement direction of the plurality of resistance heating elements among the plurality of divided regions. The heating device according to any one of claims 1 to 4.

7. Further comprising an opposing rotating member that contacts the rotating member and forms a nip portion therebetween, The heating device according to any one of claims 1 to 6, wherein when the upstream side in the rotation direction of the rotating member in the nip portion is defined as the nip inlet side, the temperature detection member is provided on the inlet side with respect to the central position of the nip portion.

8. A fixing device that heats and fixes a toner image on a recording medium by the heating device according to any one of claims 1 to 7.

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

10. The image forming apparatus according to claim 9, which forms an image using only a single color toner.

Images