Heating device, fixing device, and image forming apparatus

Abstract

To achieve a configuration of different types of positioning of a high heat conduction member.SOLUTION: A fixing device 9 comprises a fixing belt 20, a heater 22 that has a base material 30 and a resistance heating element 31, and a soaking plate 28 that has a higher thermal conductivity than the base material 30. The fixing device has locking parts 28a, 28b with which the soaking plate 28 is locked to the heater 22.SELECTED DRAWING: Figure 8

Description

[Technical Field]

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

[0002] The fixing device (heating device) is provided with a planar heater (heating element) located inside the fixing belt (rotating member), a heat equalizing plate (high thermal conductivity member) for promoting heat transfer in the longitudinal direction of the heater and suppressing temperature unevenness in the longitudinal direction, and a heater holder (holding member) for holding the heater.

[0003] There are already fixing devices such as those described above that have a configuration in which a highly heat-conductive member is held by a holding member. For example, in Patent Document 1 (JP 2016-114876 A), a hook provided on the heat-transfer member is inserted into a hole in the heater holder to engage with the heater holder.

[0004] When assembling a high thermal conductivity member to a holding member as in Patent Document 1, depending on the configuration of the heating device, providing a locking portion on the high thermal conductivity member to lock it to the holding member may result in an increase in the size of the device or an increase in the processing cost of the high thermal conductivity member, so the configuration in which the holding member is assembled to the high thermal conductivity member is not necessarily optimal. Thus, there was room for a different assembly configuration for the high thermal conductivity member. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to realize a configuration for different positioning of the high thermal conductivity member. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a heating device comprising a rotating member, a heating element having a base material and a heat generating element, and a high thermal conductivity member having a higher thermal conductivity than the base material, wherein the high thermal conductivity member has a locking portion that locks onto the heating element. [Effects of the Invention]

[0007] According to the present invention, the highly thermally conductive member can be positioned on the heating element. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating the configuration of an image forming apparatus. [Figure 2] 1 is a side cross-sectional view showing a schematic configuration of a fixing device according to an embodiment of the present invention. [Figure 3] FIG. [Figure 4] FIG. 4 is a plan view of a heater having a different resistive heating element shape from that of FIG. 3. [Figure 5] FIG. 5 is a plan view of a heater having a resistance heating element with a different shape from those in FIGS. 3 and 4. [Figure 6] FIG. 2 is a plan view showing a heater in which resistance heating elements are connected in series. [Figure 7] FIG. 10 is a diagram illustrating power supply to a heater. [Figure 8] FIG. 2 is a perspective view showing a heater holder, a heat equalizer plate, a heater, and a thermistor. [Figure 9] FIG. 2 is a perspective view showing a locking portion of a heat equalizing plate and its surrounding area. [Figure 10] FIG. 10 is a perspective view showing a heater holder, a heat equalizer plate, a heater, and a thermistor of a fixing device different from the embodiment described above. [Figure 11] 11 is a cross-sectional view showing an insulation distance between a thermistor and a heat equalizer plate of the fixing device of FIG. 10. [Figure 12] 10A and 10B are perspective views of the locking portion on one side in the longitudinal direction, showing different forms of the locking portion. [Figure 13] 10A and 10B are perspective views showing different forms of the locking portion and the heater. [Figure 14] 10 is a perspective view of the locking portion on the other side in the longitudinal direction, showing a different form of the locking portion. FIG. [Figure 15] 10 is a perspective view showing a small cross-sectional area portion provided on the other longitudinal side of the heat equalizing plate. FIG. [Figure 16]FIG. 4 is a perspective view showing a small cross-sectional area portion provided on one longitudinal side of the heat equalizing plate. [Figure 17] FIG. 10 is a diagram illustrating a case in which a thermistor is disposed inside a maximum paper passing area. [Figure 18] FIG. 10 is a diagram illustrating a case in which the thermistor is disposed outside the maximum paper passing area. [Figure 19] FIG. 1 illustrates the atomic crystal structure of graphene. [Figure 20] FIG. 1 illustrates the atomic crystal structure of graphite. [Figure 21] FIG. 2 is a side cross-sectional view showing a schematic configuration of a fixing device different from the above. [Figure 22] FIG. 2 is a side cross-sectional view showing a schematic configuration of a fixing device different from the above. [Figure 23] FIG. 2 is a side cross-sectional view showing a schematic configuration of a fixing device different from the above. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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 duplicated explanations will be appropriately simplified or omitted. Hereinafter, a fixing device that fixes an image on paper as a recording medium will be described as an example of a heating device of the present invention.

[0010] FIG. 1 is a schematic 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 imaging units 1Y, 1M, 1C, and 1Bk that are detachable from the image forming apparatus main body. Each imaging unit 1Y, 1M, 1C, and 1Bk has the same configuration except that it contains a different color developer: yellow, magenta, cyan, or black. These color developers correspond to the color separation components of a color image. Each imaging unit 1Y, 1M, 1C, and 1Bk includes a drum-shaped photoconductor 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 photoconductor 2. The developing device 4 supplies toner as a developer to the surface of the photoconductor 2 to form a toner image. The cleaning device 5 cleans the surface of the photoconductor 2.

[0012] The photoreceptor 2 can be, for example, an inorganic photoreceptor such as amorphous silicon or selenium, or an organic photoreceptor such as titanyl phthalocyanine. Examples of the organic photoreceptor include a multilayer photoreceptor having a laminated structure in which a layer (charge generation layer) in which a charge generation material such as metal-free phthalocyanine or titanyl phthalocyanine is dispersed in a binder resin and a layer (charge transport layer) in which a charge transport material is dispersed in a binder resin are stacked on a support such as an aluminum drum, and a single-layer photoreceptor having a single-layer photosensitive layer on a support in which both a charge generation material and a charge transport material are dispersed in a binder resin. In a single-layer photoreceptor, a hole transport agent and an electron transport agent can be added to the photosensitive layer as charge transport materials. An undercoat layer may also be provided between the support and the multilayer charge generation layer or the single-layer photosensitive layer.

[0013] The image forming apparatus 100 also includes an exposure device 6, a paper feed device 7 as a recording medium supply unit, a transfer device 8, a fixing device 9 as a heating device, and a paper discharge device 10. The exposure device 6 exposes the surface of each photoconductor 2 to light and forms an electrostatic latent image on that surface. The paper feed device 7 has a paper feed tray 16 and a paper feed roller 17. The paper feed device 7 supplies paper P as a recording medium to a paper transport path 14 as a transport path for the recording medium. The transfer device 8 transfers the toner image formed on each photoconductor 2 to the paper P. The fixing device 9 fixes the toner image transferred to the paper P to the surface of the paper P. The paper discharge device 10 discharges the paper P outside the apparatus. The imaging units 1, photoconductors 2, charging devices 3, exposure device 6, transfer device 8, etc. constitute image forming means for forming an image on paper.

[0014] The transfer device 8 has an endless intermediate transfer belt 11 as an intermediate transfer body, 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 multiple rollers. The primary transfer rollers 12 transfer the toner images on the photoconductors 2 to the intermediate transfer belt 11. The secondary transfer rollers 13 transfer the toner images transferred onto the intermediate transfer belt 11 to paper P. Each of the multiple primary transfer rollers 12 contacts the photoconductors 2 via the intermediate transfer belt 11. This brings the intermediate transfer belt 11 and each photoconductor 2 into contact with each other, forming a primary transfer nip between them. Meanwhile, the secondary transfer roller 13 contacts one of the rollers stretching the intermediate transfer belt 11 via the intermediate transfer belt 11. This forms a secondary transfer nip between the secondary transfer roller 13 and the intermediate transfer belt 11. An elastic intermediate transfer belt may also be used as the intermediate transfer body. The elastic intermediate transfer belt may be, for example, a flexible elastic layer laminated on a rigid base layer that provides a relatively flexible property. In addition, a guide member for preventing deviation may be provided on the inner peripheral surface of the intermediate transfer belt 11 to prevent meandering of the intermediate transfer belt 11.

[0015] Further, a pair of timing rollers 15 is provided on the paper transport path 14 between the paper feeder 7 and the secondary transfer nip (secondary transfer roller 13). A pair of rollers such as the timing rollers 15 provided on the paper transport path 14 is a transport member for transporting the paper P on the paper transport path 14.

[0016] Next, the printing operation of the image forming apparatus will be described with reference to FIG.

[0017] When a command to start a printing operation is issued, in each of the imaging units 1Y, 1M, 1C, and 1Bk, the photoconductor 2 is rotated clockwise in FIG. 1, and the charging device 3 charges the surface of the photoconductor 2 to a uniform high potential. Next, the exposure device 6 exposes the surface of each photoconductor 2 based on the image information of the original document read by the document reading device or the print information instructed to be printed from the terminal. This reduces the potential of the exposed area, forming an electrostatic latent image. Toner is then supplied from the developing device 4 to this electrostatic latent image, and a toner image is formed on each photoconductor 2.

[0018] The toner images formed on each photoconductor 2 rotate with the rotation of the photoconductor 2 and reach the primary transfer nip (the position of the primary transfer roller 12). The toner images are then transferred to the intermediate transfer belt 11, which rotates counterclockwise in FIG. 1, so that they overlap one another. The toner images transferred onto the intermediate transfer belt 11 are then transported to the secondary transfer nip (the position of the secondary transfer roller 13) with the rotation of the intermediate transfer belt 11. The toner images are then transferred to the paper P transported at the secondary transfer nip. This paper P is supplied from the paper feed tray 16. The paper P supplied from the paper feed device 7 is temporarily stopped by the timing roller 15 and then transported to the secondary transfer nip in time with the toner image on the intermediate transfer belt 11 reaching the secondary transfer nip. In this way, a full-color toner image is carried on the paper P. After the toner image is transferred, any toner remaining on each photoconductor 2 is removed by the cleaning devices 5.

[0019] The paper P onto which the toner image has been transferred is transported to a fixing device 9, which fixes the toner image onto the paper P. The paper P is then discharged outside the apparatus by a paper discharge device 10, completing the series of printing operations.

[0020] Next, the configuration of the fixing device will be described with reference to FIG.

[0021] As shown in FIG. 2 , the fixing device 9 according to this embodiment includes a fixing belt 20, a pressure roller 21 as a pressure member, a heater 22 as a heating element, a heater holder 23 as a holding member, a stay 24 as a support member, a thermistor 25 as a temperature detection member, a heat equalizer plate 28 as a highly thermally conductive member, and a thermostat. The fixing belt 20 is an endless belt. The pressure roller 21 contacts the outer surface of the fixing belt 20 and forms a fixing nip N between the fixing belt 20 and the pressure roller 21. 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 of the substrate 30 and detects its temperature. The fixing member provided in the fixing device is one example of a rotating member provided in a heating device. The fixing device 9 according to this embodiment includes the fixing belt 20 as a specific example of the fixing member.

[0022] The direction perpendicular to the plane of the paper in FIG. 2 (see direction X in FIG. 3) is the longitudinal direction of the fixing belt 20, pressure roller 21, heater 22, heater holder 23, stay 24, heat equalizer plate 28, and fixing device 9; hereinafter, this direction will be referred to simply as the longitudinal direction. Note that this longitudinal direction also refers to the belt width direction of the fixing belt 20 or the axial direction of the pressure roller 21, as well as the width direction of the paper being conveyed. The width direction of the paper is perpendicular to the paper conveyance direction and thickness direction. The vertical direction Y in FIG. 2 is the short-side direction of the heater 22 and heat equalizer plate 28, and is also the paper conveyance direction and the opposite direction. The horizontal direction Z in FIG. 2 is the thickness direction of the substrate 30 and heater 22, and is also the pressure direction of the pressure roller 21 against the fixing belt 20 and the opposite direction. The heater 22, heat equalizer plate 28, and the thermistor 25 are arranged in a stacked manner in the thickness direction of the substrate 30. The term "arranged in a stacked manner" includes not only the case where two members are directly stacked and abutted in the thickness direction, but also the case where another member or space is interposed between them. In this embodiment, the directions X, Y, and Z are perpendicular to each other.

[0023] The fixing belt 20 has a base layer made of a cylindrical substrate made of polyimide (PI) having an outer diameter of 25 mm and a thickness of 40 to 120 μm. A release layer made of a fluororesin such as PFA or PTFE and having a thickness of 5 to 50 μm is formed on the outermost surface of the fixing belt 20 to enhance durability and ensure releasability. A 50 to 500 μm thick elastic layer made of rubber or the like may be provided between the substrate and the release layer. The fixing belt 20 of this embodiment is a rubberless belt that does not have an elastic layer. The substrate of the fixing belt 20 is not limited to polyimide, and may be a heat-resistant resin such as PEEK or a metal substrate such as nickel (Ni) or SUS. The inner peripheral surface of the fixing belt 20 may be coated with a sliding layer made of polyimide, PTFE, or the like.

[0024] The pressure roller 21 has an outer diameter of, for example, 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 on the outside of the elastic layer 21b. The elastic layer 21b is made of silicone rubber and has a thickness of, for example, 3.5 mm. The release layer 21c is a conductive layer formed by adding a conductive filler such as carbon to PFA.

[0025] The pressure roller 21 is urged toward the fixing belt 20 by the urging means, so that the pressure roller 21 is pressed against the heater 22 via the fixing belt 20. As a result, a fixing nip N is formed between the fixing belt 20 and the pressure roller 21. The pressure roller 21 is configured to be rotationally driven by a drive means, and when the pressure roller 21 rotates in the direction of arrow A1 in FIG. 2, the fixing belt 20 is accordingly rotated in the direction of arrow A2. The A1 and A2 directions are the rotation directions of the pressure roller 21 and fixing belt 20 during the image forming operation or the fixing operation.

[0026] The heater 22 is disposed so as to be in contact with the inner circumferential surface of the fixing belt 20. In this embodiment, the heater 22 comes into contact with the pressure roller 21 via the fixing belt 20 and serves as a nip forming member that forms a fixing nip N between the pressure roller 21 and the fixing belt 20. The fixing belt 20 is also a member to be heated by the heater 22. In other words, the heater 22 heats the paper P that is passed through the fixing nip N via the fixing belt 20.

[0027] The heater 22 is a planar heating element provided longitudinally across the width direction of the fixing belt 20. The heater 22 is composed of a plate-shaped substrate 30, a resistance heating element 31 provided on the substrate 30, an insulating layer 32 covering the resistance heating element 31, and the like. The heater 22 is in contact with the inner circumferential surface of the fixing belt 20 on the insulating layer 32 side, and heat generated from the resistance heating element 31 is transferred to the fixing belt 20 via the insulating layer 32. In this embodiment, the resistance heating element 31 and the insulating layer 32 are provided on the fixing belt 20 side (the fixing nip N side) of the substrate 30. However, the resistance heating element 31 and the insulating layer 32 may be provided on the heater holder 23 side of the substrate 30. In this case, the heat from the resistance heating element 31 is transferred to the fixing belt 20 via the substrate 30, so the substrate 30 is preferably made of a material with high thermal conductivity, such as aluminum nitride. Furthermore, by forming the base material 30 from a material with high thermal conductivity, it is possible to heat the fixing belt 20 sufficiently even if the resistance heating element 31 is placed on the opposite side of the base material 30 from the fixing belt 20 side.

[0028] The heater holder 23 and the stay 24 are disposed on the inner circumferential side of the fixing belt 20. The stay 24 is made of a metal channel material, and both longitudinal ends 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 reliably receive the pressing force of the pressure roller 21 when the pressure roller 21 is pressed against the fixing belt 20. This ensures that the fixing nip N is stably formed between the fixing belt 20 and the pressure roller 21. In this embodiment, the thermal conductivity of the heater holder 23 is set to be smaller than that of the base material 30.

[0029] The heater holder 23 is desirably made of a heat-resistant material because it is prone to becoming hot due to the heat from the heater 22. For example, if the heater holder 23 is made of a heat-resistant resin with low thermal conductivity, such as LCP or PEEK, heat transfer from the heater 22 to the heater holder 23 is suppressed. This allows the heater 22 to heat the fixing belt 20 efficiently.

[0030] The heater holder 23 has a holding recess 23b for holding the heater 22.

[0031] 2, the heater holder 23 is integrally provided with guide ribs 26 that guide the fixing belt 20. A plurality of guide ribs 26 are provided in the longitudinal direction on both the upstream and downstream sides of the heater holder 23 in the paper transport direction.

[0032] The guide rib 26 is formed in a generally fan shape. The guide rib 26 is provided along the inner peripheral surface of the fixing belt 20 and has an arc-shaped or convex curved guide surface 260 extending in the circumferential direction of the belt.

[0033] The heater holder 23 has an insertion hole 23a penetrating through the heater holder 23 in the thickness direction within the recess 23b. A thermistor 25 is provided in the insertion hole 23a.

[0034] The heat equalizer 28 is made of a material with a higher thermal conductivity than the base material 30. In this embodiment, the heat equalizer 28 is made of an aluminum alloy, steel, a graphite sheet, or other conductor. By making the heat equalizer 28 plate-shaped, the positional accuracy of the heater 22 relative to the heater holder 23 and the heat equalizer 28 can be improved. By arranging the heat equalizer 28, heat transfer in the longitudinal direction can be promoted, making it possible to uniform the temperature of the heater 22, and ultimately the fixing belt 20, in the longitudinal direction. By forming the heat equalizer 28 from a metal material, it is possible to improve processability and increase its dimensional accuracy.

[0035] Next, a method for calculating the thermal conductivity will be described. When calculating the thermal conductivity, first, the thermal diffusivity of the object is measured, and then the thermal conductivity is calculated using the measured thermal diffusivity.

[0036] The thermal diffusivity was measured using a thermal diffusivity / thermal conductivity measuring device (trade name: ai-Phase Mobile 1u, ai-Phase Corporation).

[0037] To convert the thermal diffusivity to thermal conductivity, the density and specific heat capacity values are required. A dry-type automatic densitometer (product name: Accupyc 1330, manufactured by Shimadzu Corporation) was used to measure the density. A differential scanning calorimeter (product name: DSC-60, manufactured by Shimadzu Corporation) was used to measure the specific heat capacity, using sapphire as a reference material with a known specific heat capacity. In this example, the specific heat capacity was measured five times, and the average value at 50°C was used. When the density and specific heat capacity are ρ and C, respectively, the thermal conductivity λ can be calculated from the thermal diffusivity α obtained from the thermal diffusivity measurement using the following equation (1): λ=ρ×C×α (1)

[0038] In the fixing device 9 according to this embodiment, when a printing operation is started, the pressure roller 21 is driven to rotate, and the fixing belt 20 starts to rotate. At this time, the inner circumferential surface of the fixing belt 20 contacts and is guided by the guide surface 260 of the guide rib 26, thereby allowing the fixing belt 20 to rotate stably and smoothly. Furthermore, power is supplied to the resistance heating element 31 of the heater 22, thereby heating the fixing belt 20. Then, when the temperature of the fixing belt 20 reaches the fixing temperature, which is a predetermined target temperature, as shown in FIG. 2 , the paper P carrying the unfixed toner image is transported in the direction of arrow A3 to the fixing nip N between the fixing belt 20 and the pressure roller 21, whereby the unfixed toner image is heated and pressurized and fixed to the paper P.

[0039] Next, a more detailed configuration of the heater provided in the fixing device will be described with reference to Fig. 3. Fig. 3 is a plan view of the heater according to this embodiment.

[0040] 3, a plurality of (four) resistance heating elements 31, power supply lines 33A and 33B as conductors, and first and second electrode portions 34A and 34B are provided on the surface of a plate-shaped substrate 30. However, the number of resistance heating elements 31 is not limited to that in this embodiment. Hereinafter, the power supply lines 33A and 33B will also be referred to as power supply lines 33, and the first electrode portion 34A or the second electrode portion 34B will also be referred to as electrode portion 34.

[0041] The left-right direction X in FIG. 3, which is the longitudinal direction of the heater 22, etc., is also the arrangement direction of the multiple resistance heating elements 31. Hereinafter, this direction will be simply referred to as the arrangement direction. Furthermore, the direction intersecting the arrangement direction, particularly the vertical direction in this embodiment, and the up-down direction Y in FIG. 3, which is a direction different from the thickness direction of the base material 30, will be referred to as the direction intersecting the arrangement direction of the multiple resistance heating elements 31, or simply as the intersecting arrangement direction. The intersecting arrangement direction Y is the direction along the surface of the base material 30 on which the resistance heating elements 31 are provided, and is also the widthwise direction of the heater 22 or the transport direction of paper passed through the fixing device 9.

[0042] The multiple resistance heating elements 31 form multiple divided heating sections 35 in the arrangement direction. Each resistance heating element 31 is electrically connected in parallel to a pair of electrode sections 34A, 34B via power supply lines 33A, 33B. The pair of electrode sections 34A, 34B are provided at the left end of the substrate 30 in FIG. 3, which is one end of the substrate 30 in the arrangement direction. The power supply lines 33A, 33B are made of a conductor with a lower resistance value than the resistance heating elements 31.

[0043] The resistance heating element 31 is made of a material having a PTC (positive temperature coefficient of resistance) characteristic, and is characterized in that as the temperature rises, the resistance value rises and the heater output decreases.

[0044] The PTC characteristics of the resistance heating element 31 and the divided heating section 35 configuration in the arrangement direction prevent excessive temperature rise of the fixing belt 20 when small-size paper is passed through. In other words, when paper narrower than the overall width of the heating section 35 is passed through, the paper does not absorb heat from the fixing belt 20 in the area outside the paper width, causing the temperature of the resistance heating element 31 corresponding to that area to rise. Because the voltage applied to the resistance heating element 31 is constant, when the temperature of the resistance heating element 31 outside the paper width rises, its resistance value also rises. This results in a relative decrease in heater output, i.e., the amount of heat generated, and suppresses temperature rise at the edge. Furthermore, electrically connecting multiple resistance heating elements 31 in parallel suppresses temperature rise in non-paper passing areas while maintaining printing speed. The heating elements constituting the heating section 35 may be other than resistance heating elements with PTC characteristics. Furthermore, the resistance heating elements may be arranged in multiple rows in the cross-arrangement direction of the heaters 22.

[0045] The resistance heating element 31 can be formed, for example, by applying a paste made of silver palladium (AgPd) and glass powder to the substrate 30 by screen printing or the like, and then firing the substrate 30. In this embodiment, the resistance value of the resistance heating element 31 is set to 80 Ω at room temperature. In addition to the materials mentioned above, the resistance heating element 31 may also be made of resistance materials such as silver alloy (AgPt) or ruthenium oxide (RuO2). The power supply line 33 and the electrode portion 34 can be made of silver (Ag) or silver palladium (AgPd) by screen printing or the like. The power supply line 33 is made of a conductor with a lower resistance value than the resistance heating element 31.

[0046] The material for the substrate 30 is preferably a ceramic such as alumina or aluminum nitride, which has excellent heat resistance and insulation, or a non-metallic material such as glass or mica. In this embodiment, an alumina substrate is used, which is 8 mm wide in the cross-array direction, 270 mm wide in the array direction, and 1.0 mm thick. Alternatively, the substrate 30 may be formed by laminating an insulating material onto a conductive material such as a metal. As a metal material for the substrate 30, aluminum, stainless steel, or the like is preferred because of its low cost.

[0047] The insulating layer 32 is made of heat-resistant glass having a thickness of, for example, 75 μm. The insulating layer 32 covers the resistance heating element 31 and the power supply line 33, insulating and protecting them and maintaining sliding properties with the fixing belt 20.

[0048] The region in which the resistance heating elements 31 are provided in the longitudinal direction is the main heat-generating region D of the heater 22, and the main heat-generating region D also includes the region between the resistance heating elements 31. In other words, the main heat-generating region D of the heater 22 extends from one longitudinal end of the resistance heating element 31 arranged on the most one longitudinal side to the other longitudinal end of the resistance heating element 31 arranged on the most other longitudinal side. The main heat-generating region D is the region where the heater 22 mainly generates heat, and the heater 22 also generates a small amount of heat in regions outside the main heat-generating region D.

[0049] In this 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. The shape of the resistance heating element 31 is not limited to that of this embodiment. For example, as shown in FIG. 4, the resistance heating element 31 may be rectangular, or as shown in FIG. 5, the resistance heating element 31 may be made of a linear portion that is folded back to form a substantially parallelogram shape. As shown in FIG. 4, the portion extending from the block-shaped portion of the resistance heating element 31 toward the power supply line 33 (the portion extending in the arrangement crossing direction) may be part of the resistance heating element 31, or may be made of the same material as the power supply line 33.

[0050] 6, the heater 22 has two resistance heating elements 31 connected in series and extending in the longitudinal direction. The two resistance heating elements 31 are connected to electrodes 34A and 34B via power supply lines 33A and 33B, respectively, on the left side of FIG. 6. The two resistance heating elements 31 are also connected in series via power supply line 33C on the right side of FIG. 6.

[0051] In the heater 22 shown in FIGS. 3 to 6, the length of the substrate 30 is longer on the left side of each figure than on the right side relative to the center position D1 of the main heat-generating region D. This is because the left side of the figure is longer due to the placement of the electrodes 34A and 34B. This asymmetry in the length of the substrate 30 makes it easier for heat from the heater 22 to flow outward in the longitudinal direction on the left side of the substrate 30. Therefore, when viewed alone, the left side of the heater 22 in FIGS. 3 to 6 tends to have a lower temperature than the right side. Furthermore, the thermistor 25 of this embodiment is located on the end side, opposite the electrode portions 34A and 34B, which are the side with higher longitudinal temperatures (see FIG. 13). By detecting the higher-temperature side using the thermistor 25, the rise in end temperature can be effectively suppressed.

[0052] FIG. 7 is a diagram showing a power supply circuit to the heater shown in FIG.

[0053] As shown in FIG. 7 , in this embodiment, a power supply circuit for supplying power to each resistance heating element 31 is configured by electrically connecting an AC power source 200 and electrode portions 34A, 34B of the heater 22. The power supply circuit is also provided with a triac 210 that controls the amount of power supplied. The amount of power supplied to each resistance heating element 31 is controlled by a control unit 220 via the triac 210 based on the temperatures detected by the thermistors 25A, 25B. The control unit 220 is configured by a microcomputer including a CPU, ROM, RAM, I / O interface, etc. The control unit 220 may be provided in the fixing device or in the image forming apparatus main body.

[0054] 8 is a perspective view showing various members such as a heater holder provided inside fixing belt 20. In the following figures, thermistor 25 will be described as thermistor 25A (see FIG. 7) arranged on the longitudinal end side of main heat generation region D, and thermistor 25A will be simply referred to as thermistor 25. Also, thermistor 25B of FIG. 7 is omitted from FIG. 8, and the same applies to the following figures.

[0055] As shown in FIG. 8, an insertion hole 23a is provided in the holding recess 23b of the heater holder 23. An AC connector 29 is attached to the other longitudinal side (the right side in FIG. 8) of the heater holder 23. The AC connector 29 can electrically connect the heater 22 to the power source side by contacting contact terminals in a terminal holder 291 with the first electrode portion 34A and the second electrode portion 34B. The heat equalizer plate 28 also has locking portions 28a and 28b at both longitudinal ends thereof that lock onto the heater 22. The longitudinal side on which the locking portion 28a is provided is the side on which the electrode portion of the heater 22 is not provided, that is, the side on which the base material of the heater 22 is shorter than the center position of the paper. The longitudinal side on which the locking portion 28b is provided is the side on which the electrode portion of the heater 22 is provided and on which the base material of the heater 22 is longer.

[0056] When assembling these components, first, the heat equalizer plate 28 is assembled to the heater 22 by engaging the locking portions 28a, 28b at both ends of the heat equalizer plate 28 with the heater 22. In this state, the heater 22 and the heat equalizer plate 28 are fitted into the holding recess 23b of the heater holder 23. That is, the heater holder 23 holds the heater 22 and the heat equalizer plate 28 in a state where they are stacked in the thickness direction. In this state, the approximately U-shaped terminal holder 291 of the AC connector 29 sandwiches the other longitudinal side of the heater holder 23, the heat equalizer plate 28, and the heater 22, thereby fixing the heat equalizer plate 28 and the heater 22 to the heater holder 23. The thermistor 25 is inserted into the insertion hole 23a from the back side of the heater holder 23, i.e., the side opposite the heater 22, and abuts against the back side of the heat equalizer plate 28. The thermistor 25 detects the temperature of the heater 22 via the heat equalizer plate 28 .

[0057] Next, the locking portions 28a and 28b of the heat equalizing plate 28 will be described with reference to FIGS. 9(a) and 9(b).

[0058] As shown in FIG. 9(a), the locking portion 28a provided on one longitudinal side of the heat equalizer 28 includes a locking piece 28a1 provided on an edge of the heat equalizer 28 on one longitudinal side and locking pieces 28a2 and 28a3 provided on both lateral sides. The locking pieces 28a1 to 28a3 are portions bent 90 degrees in the thickness direction relative to the main body of the heat equalizer 28. The locking piece 28a1 is provided so as to be able to abut against one longitudinal end face of the heater 22 from one longitudinal side. The locking piece 28a1 determines the longitudinal position of the heat equalizer 28 relative to the heater 22. The locking piece 28a2 is provided so as to be able to abut against one lateral end face of the heater 22 from one lateral side. The locking piece 28a3 is provided so as to be able to abut against the other lateral end face of the heater 22 from the other lateral side. The locking pieces 28a2 and 28a3 determine the position of the heat equalizing plate 28 relative to the heater 22 in the lateral direction.

[0059] As shown in FIG. 9(b), locking portion 28b provided on the other longitudinal side of heat equalizer 28 includes locking pieces 28b1 and 28b2 provided on both sides of heat equalizer 28 in the lateral direction. Locking pieces 28b1 and 28b2 are portions bent 90 degrees relative to the main body of heat equalizer 28 and extended in the thickness direction. Locking piece 28b1 is provided so as to be able to abut against one end face of heater 22 in the lateral direction from one side in the lateral direction. Locking piece 28b2 is provided so as to be able to abut against the other end face of heater 22 in the lateral direction from the other side in the lateral direction. Locking pieces 28b1 and 28b2 position heat equalizer 28 relative to heater 22 in the lateral direction.

[0060] The distance between the locking pieces 28a2 and 28a3 is set slightly larger than the width of the heater 22 in the short-side direction. In other words, the locking pieces 28a2 and 28a3 do not always abut against the heater 22 to lock the heat equalizer plate 28 to the heater 22; rather, when the heater 22 moves relative to the heat equalizer plate 28 in the short-side direction, one of the locking pieces 28a2 and 28a3 abuts against the heater 22, thereby restricting misalignment in the short-side direction between the heater 22 and the heat equalizer plate 28. This locks the heat equalizer plate 28 to the heater 22 and positions it in place. However, both the locking pieces 28a2 and 28a3 may abut against the heater 22 to lock it. For example, the distance between the locking pieces 28a2 and 28a3 may be set to be approximately the same as or smaller than the width of the heater 22 in the short-side direction. The heater 22 may be fitted between the locking pieces 28a2, 28a3 while the locking pieces 28a2, 28a3 are bent outward in the short-side direction, thereby locking the heat equalizing plate 28 to the heater 22. Similarly to the locking pieces 28a2, 28a3, the locking pieces 28b1, 28b2 may be configured to restrict and position the heater 22 when the heater 22 moves relative to the locking pieces 28a2, 28a3 in the short-side direction, or may be configured to abut against the heater 22. It is not necessary to provide all of the locking pieces 28a1 to 28a3 and the locking pieces 28b1, 28b2, and only some of them may be provided.

[0061] The above-described locking portions 28a and 28b allow the heat equalizer plate 28 to be locked to the heater 22, and the heat equalizer plate 28 to be positioned relative to the heater 22. This increases the positional accuracy of the heat equalizer plate 28 relative to the heater 22. As a result, the heat equalizer plate 28 can promote heat transfer to the heater 22 within a required range in the longitudinal direction, and the heater 22 can be more uniformly heated in the longitudinal direction.

[0062] Unlike the heat equalizer plate 28 of this embodiment, when the heat equalizer plate is configured to be engaged with the heater holder, the insulation distance between the heat equalizer plate and the thermistor can become an issue. The insulation distance between the heat equalizer plate and the thermistor will be explained using Figures 10 and 11. Figures 10 and 11 show a fixing device having a heat equalizer plate 280 that is different from that of this embodiment. Figure 10 is a perspective view showing each component such as the heater holder, and Figure 11 is a cross-sectional view showing the heat equalizer plate and the recessed portion of the heater holder to which the heater is attached.

[0063] 10 has bent portions 280a and 280b on both sides in the longitudinal direction thereof. Heater holder 23 has insertion holes 23c in recess 23b into which bent portions 280a and 280b are inserted.

[0064] As shown in Fig. 11, the bent portion 280a is inserted into the insertion hole 23c. In this state, when the heat equalizer 280 moves upward in Fig. 11, which is the direction in which the heat equalizer 280 falls off the heater holder 23, the upper surface of the tip 280a1 of the bent portion 280a in Fig. 11 comes into contact with the back surface 23d of the heater holder 23 (see the arrow in Fig. 11). This allows the bent portion 280a to be locked to the heater holder 23, preventing the heat equalizer 280 from falling off the heater holder 23.

[0065] As described above, in a configuration in which the heat equalizer 280 has the bent portion 280a, which is a portion that protrudes toward the heater holder 23, and the bent portion 280a is engaged with the heater holder 23, the insulation distance between the heat equalizer 280 and the thermistor 25 becomes an issue. That is, by providing the bent portion 280a on the heat equalizer 280, the bent portion 280a and the solder portion 255, which is the conductor portion of the thermistor 25, are positioned at a distance of insulation distance H1. If this insulation distance H1 is not sufficiently large, there is a risk of a short circuit between the thermistor 25 side and the heat equalizer 280 side.

[0066] In contrast, the heat equalizer plate 28 of this embodiment shown in Figure 8 and the like does not have a portion corresponding to the bent portion 280a of the heat equalizer plate 280 of Figure 10 and the like, which is the portion that engages with the heater holder 23. In particular, in this embodiment, as shown in Figure 10, the back surface of the heat equalizer plate 28 on the heater holder 23 side (back surface 28c in Figure 2) is the portion of the heat equalizer plate 28 closest to the thermistor 25 in direction Z (left side in Figure 2). Since the heat equalizer plate 28 does not have a portion that protrudes toward the thermistor 25, a sufficient insulation distance can be ensured between the heat equalizer plate 28 and the thermistor 25.

[0067] The heat equalizer plate 28 is preferably made of aluminum alloy, steel, or graphite, which has high thermal conductivity, which effectively suppresses temperature variations in the heater 22 and, ultimately, the fixing belt in the longitudinal direction, thereby suppressing temperature rises and sagging at the edges.

[0068] Next, we will explain in order the modifications of the locking portion of the heat equalizer plate 28. In the following explanation, we will mainly explain the differences from the heat equalizer plate 28 explained above with reference to FIG.

[0069] 12, the locking piece 28a1 provided on one longitudinal edge has a two-stage bent shape. That is, the locking piece 28a1 has a substantially L-shape with a portion bent in the thickness direction relative to the main body of the heat equalizer 28 and a portion 28a11 bent in the longitudinal direction relative to the portion bent in the thickness direction. When viewed from the thickness direction of the heat equalizer 28, this longitudinally extending portion of the heat equalizer 28 overlaps with the heater 22. That is, when the heat equalizer 28 moves relatively in a direction that causes it to fall off the heater 22 (to the left in FIG. 2), the longitudinally bent portion 28a11 of the locking piece 28a1 abuts against the rear surface of the heater 22, preventing the heat equalizer 28 from falling off the heater 22.

[0070] As shown in FIG. 13 , in this embodiment, the heater 22 has a recess 22a at one longitudinal end that is recessed toward the other longitudinal end. The recess 22a is a recessed shape provided in the base material of the heater 22. The recess 22a is provided at a position corresponding to the locking piece 28a1, and the locking piece 28a1 is locked to the recess 22a. This allows the locking piece 28a1 to be located closer to the center in the longitudinal direction, thereby shortening the longitudinal length of the heat equalizer plate 28. Furthermore, the locking piece 28a1 can be configured to abut against the wall surface portion that forms the recess 22a of the heater 22 on both sides in the lateral direction, improving the positioning accuracy of the heater 22 and the heat equalizer plate 28 in the lateral direction.

[0071] 14, recesses 22b and 22c recessed inward in the lateral direction may be formed on the other longitudinal side of heater 22. Recesses 22b and 22c are provided at positions corresponding to locking pieces 28b1 and 28b2, respectively, and locking pieces 28b1 and 28b2 are engaged therewith. Locking pieces 28b1 and 28b2 in FIG. 14 are generally L-shaped with portions bent inward in the lateral direction of heat equalizer 28. By configuring locking pieces 28b1 and 28b2 to lock into recesses 22b and 22c, respectively, the length of heat equalizer 28 in the lateral direction can be reduced. Furthermore, when heat equalizer 28 is positioned relative to heater 22 based on the other longitudinal side, the accuracy of longitudinal positioning of AC connector 29 (see FIG. 10) attached to heater 22 relative to heat equalizer 28 is improved. As in the embodiment of FIG. 8, the locking portions 28a, 28b may be provided on both sides in the longitudinal direction, or a locking portion may be provided on only one side in the longitudinal direction.

[0072] A small cross-sectional area portion having a small cross-sectional area perpendicular to the longitudinal direction of the heat equalizer plate 28 may be provided outside the maximum paper passage area in the longitudinal direction. Specifically, in the embodiment shown in FIG. 15, a small cross-sectional area portion 28d, which is a longitudinal portion having multiple (two in the lateral direction) holes, is provided on the other longitudinal side of the heat equalizer plate 28. The small cross-sectional area portion 28d is provided outside the heat generation area D of the heater 22 (and also outside the paper passage area further inward). Alternatively, the small cross-sectional area portion may be formed by a recess or a thin portion as shown in FIG. 14, or may have only one hole in the lateral direction. The number of small cross-sectional area portions 28d provided in the longitudinal direction is arbitrary. On the other longitudinal side, the length of the substrate is longer due to the provision of an electrode portion than on one longitudinal side, so that the heat of the heater 22 easily flows outward in the longitudinal direction. However, by providing the small cross-sectional area portion 28d, the amount of heat transferred to the other longitudinal side can be reduced, and the temperature drop at the end of the heater 22 on the other longitudinal side can be reduced. Therefore, the temperature of the heater 22 can be made uniform in the longitudinal direction.

[0073] 15 illustrates an embodiment in which the small cross-sectional area portions 28d are provided on the other longitudinal side. However, the small cross-sectional area portions 28d may also be provided on one longitudinal side. For example, as shown in FIG. 16, multiple small cross-sectional area portions 28d are provided on one longitudinal side. The small cross-sectional area portions 28d are provided outside the heat generating region D of the heater 22 (and also outside the paper passing region further inward). This reduces the amount of heat transfer to the outside in the longitudinal direction on the one longitudinal side, and suppresses temperature drop at the end of the heater 22 on the one longitudinal side. Furthermore, since the length of the substrate is shorter on the one longitudinal side than on the other longitudinal side, heat from the heater 22 is less likely to flow outward in the longitudinal direction. Therefore, the number of small cross-sectional area portions 28d is reduced compared to the other longitudinal side (or the area of the holes may be reduced). In this way, by providing the small cross-sectional area portion 28d on one longitudinal side as well, the amount of heat transfer on one longitudinal side and the other longitudinal side can be adjusted, respectively, and the temperature of the heater 22 can be made uniform in the longitudinal direction. Also, the small cross-sectional area portions 28d on one longitudinal side and the other longitudinal side can be provided at positions at different distances from the center position of the heat generating region D. However, it is also possible to provide a small cross-sectional area portion only on one longitudinal side.

[0074] In this embodiment, the provision of the thermistor 25 as described above allows the temperature of the heater 22 to be appropriately controlled. In particular, as shown in FIG. 7 , by providing the thermistors 25 at the center and end sides of the heater 22, the heat generation of the heater 22 can be controlled based on the detected temperatures at the center and end sides, thereby allowing the temperature of the heater 22, and ultimately the center and end sides of the fixing belt, to be appropriately controlled. For example, excessive temperature rise at the end sides of the heater 22 can be detected. The end sides of the heater 22 in the longitudinal direction refer to, for example, the two end regions when the heat generating region D is divided into three equal parts in the longitudinal direction, and the center side of the heater 22 in the longitudinal direction refers to the central region. However, the end sides may refer to each of the three equal parts when the heater 22 is divided into three equal parts in the longitudinal direction.

[0075] 17, part or all of the thermistor 25 arranged on the longitudinal end side (or in particular the thermal element 251, which is the temperature detection unit) may be provided within the maximum paper passing area E, which is the area where paper P1 with the widest longitudinal width passes. This makes it possible to detect the temperature of the heater 22 at a position on the longitudinal end side of the paper, and to reliably raise the temperature of the heater 22 in this area, i.e., the temperature of the fixing belt, to the temperature required for fixing. This ensures fixability on the longitudinal end side of the paper.

[0076] Conversely, as shown in Figure 18, part or all of the thermistor 25 (or particularly the thermal element 251, which is the temperature detection unit) located on the longitudinal end side may be located outside the paper passage area E, in a position overlapping with the main heat generation area D. This allows the thermistor 25 to detect the temperature of the longitudinal area where heat is not absorbed by the paper and where the temperature is most likely to rise. This prevents abnormal temperature rises in the heater 22 and improves the safety of the fixing device.

[0077] The heat spreader plate 28 can be made of a graphene sheet. This allows the heat spreader plate 28 to have high thermal conductivity in a predetermined direction along the graphene surface, that is, in the arrangement direction rather than the thickness direction. This effectively reduces temperature unevenness in the arrangement direction of the heater 22 and the fixing belt 20.

[0078] Graphene is a flaky powder. Graphene consists of a planar hexagonal lattice structure of carbon atoms, as shown in Figure 19. A graphene sheet is a sheet of graphene, usually a single layer. The single layer of carbon may contain impurities. Graphene may also have a fullerene structure. A fullerene structure is generally recognized as a compound in which the same number of carbon atoms form a polycyclic ring fused with five-membered and six-membered rings in a cage-like structure, such as C60, C70, and C80 fullerenes, or other closed rings with three-coordinated carbon atoms. It has a cage-like structure.

[0079] Graphene sheets are man-made and can be produced, for example, by chemical vapor deposition (CVD).

[0080] 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).

[0081] Furthermore, graphite, which is a multilayered graphene, has a large thermal conductivity anisotropy. As shown in FIG. 20, 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 28 from graphite, the heat transfer efficiency in the arrangement direction of the heat equalizer 28 is greater than in the thickness direction (i.e., the stacking direction of the components), thereby suppressing heat transfer to the heater holder 23. This effectively suppresses temperature unevenness in the arrangement direction of the heater 22 and minimizes heat leakage toward the heater holder 23. Furthermore, by forming the heat equalizing plate 28 from graphite, the heat equalizing plate 28 can have excellent heat resistance, not being oxidized up to about 700 degrees.

[0082] The physical properties and dimensions of the graphite sheet can be changed as appropriate depending on the functions required of the heat equalizer plate 28. 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. Also, to increase the speed of the fixing device 9, a thin graphite sheet can be used to reduce the heat capacity of the fixing device 9. Furthermore, if the width of the fixing nip N or heater 22 is large, the width of the heat equalizer plate 28 in the arrangement direction can be increased accordingly.

[0083] 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.

[0084] 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.

[0085] Furthermore, in addition to the fixing device described above, the present invention can also be applied to fixing devices such as those shown in Figures 21 to 23. The configuration of each fixing device shown in Figures 21 to 23 will be briefly described below.

[0086] First, in the fixing device 9 shown in Figure 21, a pressure roller 39 is arranged on the opposite side of the fixing belt 20 from the pressure roller 21 side. The pressure roller 39 is an opposing rotating member that rotates opposite the fixing belt 20, which is a rotating member. This pressure roller 39 and heater 22 are configured to sandwich and heat the fixing belt 20. Meanwhile, on the pressure roller 21 side, a nip forming member 41 is arranged on the inner periphery of the fixing belt 20. The nip forming member 41 is supported by the stay 24. The nip forming member 41 and the pressure roller 21 sandwich the fixing belt 20 to form a fixing nip N.

[0087] 22 does not include the pressure roller 39, and in order to ensure a circumferential contact length between the fixing belt 20 and the heater 22, the heater 22 is formed in an arc shape to match the curvature of the fixing belt 20. The rest of the configuration is the same as that of the fixing device 9 shown in FIG.

[0088] Finally, the fixing device 9 shown in FIG. 23 will be described. The fixing device 9 comprises a heating assembly 42, a fixing roller 43 as a fixing member, and a pressure assembly 44 as an opposing member. The heating assembly 42 includes the heater 22, the heat equalizer 28, the heater holder 23, the stay 24, and a heating belt 48 as a rotating member, as described in the previous embodiment. The fixing roller 43 is an opposing rotating member that rotates opposite the heating belt 48 as a rotating member. The fixing roller 43 is composed of a solid iron core 43a, an elastic layer 43b formed on the surface of the core 43a, and a release layer 43c formed on the outer surface of the elastic layer 43b. A pressure assembly 44 is provided on the side of the fixing roller 43 opposite the heating assembly 42. The pressure assembly 44 includes a nip forming member 45 and a stay 46, and a pressure belt 47 as a pressure member that is rotatably arranged so as to enclose the nip forming member 45 and the stay 46. Then, the paper P is passed through the fixing nip N2 between the pressure belt 47 and the fixing roller 43, and heat and pressure are applied to fix the image.

[0089] 21 to 23, the configurations of the heat equalizing plate 28 and heater 22 of the above-described embodiment can be adopted.

[0090] Furthermore, the heating device of the present invention is not limited to the fixing device described in the above embodiment. That is, it may be a drying device that dries ink applied to paper, or a heating device such as a laminator that thermocompresses a film as a covering member onto the surface of a sheet such as paper, or a heat sealer that thermocompresses a seal portion of a packaging material. By applying the present invention to such heating devices, it is possible to position a high thermal conductivity member on a heating body.

[0091] The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIG. 1, but may also be a monochrome image forming apparatus, a copying machine, a printer, a facsimile, or a combination machine of these.

[0092] Recording media include paper P (plain paper), as well as cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, plastic film, prepreg, copper foil, etc.

[0093] The aspects of the present invention are as follows, for example. <1> A rotating member; a heating element having a substrate and a heating element; a high thermal conductivity member having a thermal conductivity higher than that of the base material, The heating device is characterized in that the highly thermally conductive member has a locking portion that is locked to the heating body. <2> The engaging portion has a portion that abuts against a surface of the heating element opposite to the surface on the high thermal conductivity member side. <1> The heating device described above. <3> The heating element has a recessed portion recessed at a position corresponding to the locking portion. <1> or <2> The heating device described above. <4> If the area in the longitudinal direction of the rotary member through which the recording medium of the maximum width corresponding to the heating device passes is defined as the maximum passing area, The high thermal conductivity member has a small cross-sectional area portion outside the maximum passing area in the longitudinal direction, the small cross-sectional area being smaller than other portions in a direction perpendicular to the longitudinal direction. <1> from <3> The heating device according to any one of the preceding claims. <5> the high thermal conductivity member has the small cross-sectional area portions on both sides in a longitudinal direction, If the region in the longitudinal direction where the heat generating element is provided is defined as a heat generating region, The small cross-sectional area portion on one side in the longitudinal direction and the small cross-sectional area portion on the other side in the longitudinal direction are provided at positions with different distances from the center position of the heat generating region. <1> from <4> The heating device according to any one of the preceding claims. <6> The high thermal conductivity member is made of an aluminum alloy or graphite. <1> from <5> The heating device according to any one of the preceding claims. <7> A temperature detection member for detecting the temperature of the heating element is provided. <1> from <6> The heating device according to any one of the preceding claims. <8> If the region in the longitudinal direction where the heat generating element is provided is defined as a heat generating region, The temperature detection members are provided at the center and end of the heat generating area in the longitudinal direction. <7> The heating device described above. <9> the temperature detection member is provided at an end side of a heat generation region in which the heat generation element is provided in the longitudinal direction, If the area in the longitudinal direction of the rotary member through which the recording medium of the maximum width corresponding to the heating device passes is defined as the maximum passing area, The temperature detection member on the longitudinal end side of the heat generating region is provided within the maximum passing region. <7> The heating device described above. <10> the temperature detection member is provided at an end side of a heat generation region in which the heat generation element is provided in the longitudinal direction, If the area in the longitudinal direction of the rotary member through which the recording medium of the maximum width corresponding to the heating device passes is defined as the maximum passing area, The temperature detection members at the longitudinal end portions of the heat generating region are provided outside the maximum passing region. <7> The heating device described above. <11> The temperature detection member is in contact with the high thermal conductivity member from the side opposite to the heater side. <7> from <10> The heating device according to any one of the preceding claims. <12> <1> from <11> 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. <13> <12> An image forming apparatus including the fixing device described above. [Explanation of symbols]

[0094] 1. Image forming device 9 Fixing device (heating device) 20 Fixing belt (rotating member) 21 Pressure roller (pressure member) 22 Heater (heating element) 22a~22c Recess 23 Heater holder (holding member) 25 Thermistor (temperature detection element) 251 Thermal element (temperature detection part) 28 Heat equalizing plate (high thermal conductivity material) 28a, 28b Locking part 28d Small cross-sectional area 30 Base material 31 Resistive heating element (heating element) D Main heating area of the heater (main heating area of the heating element) D1 Center position of main heating area E Maximum paper passing area (maximum area where recording media can pass) P Paper (recording medium) X: Longitudinal direction of the fixing belt (longitudinal direction of the rotating member) [Prior art documents] [Patent documents]

[0095] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-114876

Claims

1. A rotating member; a heating element having a substrate and a heating element; a high thermal conductivity member having a thermal conductivity higher than that of the base material, The heating device is characterized in that the highly thermally conductive member has a locking portion that is locked to the heating body.

2. 2. The heating device according to claim 1, wherein the engaging portion has a portion that abuts against a surface of the heating element opposite to the surface on the high thermal conductivity member side.

3. The heating device according to claim 1 , wherein the heating element has a recessed portion at a position corresponding to the engaging portion.

4. The heating device according to claim 2 , wherein the heating element has a recessed portion at a position corresponding to the engaging portion.

5. If the area in the longitudinal direction of the rotary member through which the recording medium of the maximum width corresponding to the heating device passes is defined as the maximum passing area, 2. The heating device according to claim 1, wherein the high thermal conductivity member has a small cross-sectional area portion outside the maximum passing area in the longitudinal direction, the small cross-sectional area being smaller in a direction perpendicular to the longitudinal direction than other portions.

6. the high thermal conductivity member has the small cross-sectional area portions on both sides in a longitudinal direction, If the region in the longitudinal direction where the heat generating element is provided is defined as a heat generating region, 2. The heating device according to claim 1, wherein the small cross-sectional area portion on one side in the longitudinal direction and the small cross-sectional area portion on the other side in the longitudinal direction are provided at positions with different distances from a center position of the heat generating region.

7. 2. The heating device according to claim 1, wherein the highly heat-conductive member is made of an aluminum alloy or graphite.

8. 2. The heating device according to claim 1, further comprising a temperature detecting member for detecting the temperature of said heating element.

9. If the region in the longitudinal direction where the heat generating element is provided is defined as a heat generating region, 9. The heating device according to claim 8, wherein the temperature detecting members are provided at both the center and end sides of the heat generating region in the longitudinal direction.

10. the temperature detection member is provided at an end side of a heat generation region in which the heat generation element is provided in the longitudinal direction, If the area in the longitudinal direction of the rotary member through which the recording medium of the maximum width corresponding to the heating device passes is defined as the maximum passing area, 9. The heating device according to claim 8, wherein the temperature detecting members on the longitudinal end sides of the heat generating region are provided within the maximum passing region.

11. the temperature detection member is provided at an end side of a heat generation region in which the heat generation element is provided in the longitudinal direction, If the area in the longitudinal direction of the rotary member through which the recording medium of the maximum width corresponding to the heating device passes is defined as the maximum passing area, 9. The heating device according to claim 8, wherein the temperature detecting members on the longitudinal end sides of the heat generating region are provided outside the maximum passing region.

12. 9. The heating device according to claim 8, wherein the temperature detecting member abuts against the highly thermally conductive member on a side opposite to the heater side.

13. 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.

14. An image forming apparatus comprising the fixing device according to claim 13.

Images