Heating device, fixing device, and image forming apparatus

Abstract

To prevent a reduction in the performance of a static eliminating member.SOLUTION: A fixing device 9 comprises: a rotating fixing belt 20; a heater 22 that has a main heating area D and applies heat to the fixing belt 20; a pressure roller 21 that has a conductive surface and applies pressure to the fixing belt 20; a static eliminating brush 37 that is in contact with the pressure roller 21; and a separation plate 40 that is in contact with the fixing belt 20. The static eliminating brush 37 is in contact with the pressure roller 21 in a contact area E that is outside the main heating area D, in a longitudinal direction of the fixing belt 20. The separation plate 40 is in contact with the fixing belt 20 at a position corresponding to the contact area E in the longitudinal direction.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] As an example of a heating device, a fixing device installed in an image forming device such as a copier or printer transports a recording medium such as paper to a fixing nip between a fixing belt as a fixing member and a pressure roller as a pressure member, pressurizes and heats the recording medium, and fixes an unfixed image on the recording medium to the recording medium.

[0003] In such a fixing device, when the fixing operation is continuously performed on the recording medium carrying the toner image, the pressure roller becomes charged with the polarity opposite to that of the toner, causing problems such as offset phenomenon.

[0004] In response to this, for example, in Patent Document 1 (JP 2010-128298 A), a non-contact static eliminator is disposed relative to the pressure roller to eliminate static electricity from the pressure roller. Summary of the Invention [Problem to be solved by the invention]

[0005] Providing a non-contact type static eliminator as in Patent Document 1 leads to increased costs for the fixing device, as it requires a mechanism for maintaining an appropriate distance from the pressure member, etc. In addition, in the case of a contact type static eliminator, there is a problem that lubricant and impurities that have adhered to the surface of the pressure member due to contact with the pressure member adhere to the static eliminator, reducing the static elimination function of the static eliminator.

[0006] In view of the above circumstances, an object of the present invention is to suppress the deterioration of the performance of the static electricity removing member. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a heating device comprising a rotating member, a heating body having a main heat generation area and heating the rotating member, a pressure member having a conductive surface and pressing the rotating member, an electrostatic elimination member in contact with the pressure member, and a contact member in contact with the rotating member, wherein the electrostatic elimination member contacts the pressure member at a contact area outer than the main heat generation area in the longitudinal direction of the rotating member, and the contact member contacts the rotating member at a position corresponding to the contact area in the longitudinal direction. Effect of the Invention

[0008] According to the present invention, the deterioration of the performance of the static eliminating member can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an image forming apparatus. [Diagram 2] 1 is a side cross-sectional view showing a schematic configuration of a fixing device according to an embodiment of the present invention. [Diagram 3] FIG. [Figure 4] FIG. 4 is a plan view of a heater having a resistive heating element with a different shape from that of FIG. 3. [Diagram 5] FIG. 5 is a plan view of a heater having a resistive heating element with a different shape from those in FIGS. 3 and 4. [Figure 6] FIG. 4 is a diagram showing power supply to a heater. [Figure 7] 5A and 5B are diagrams illustrating the positional relationship between the static electricity removal brush and the heater in the longitudinal direction. [Figure 8] FIG. 2 is a perspective view showing the static elimination brush and its peripheral configuration. [Figure 9] FIG. 4 is a side cross-sectional view of the fixing device showing the separation plate. [Figure 10] FIG. 4 is a front view showing a separation plate, a fixing belt, and a flange. [Figure 11] 13A and 13B are diagrams showing modified examples of the contact portion of the separation plate. [Figure 12] 13A and 13B are diagrams showing another modified example of the contact portion of the separation plate. [Figure 13]4 is a side cross-sectional view of the fixing device, showing a separation plate provided on the pressure roller side. FIG. [Figure 14] 12 is a front view showing the separation plate and the pressure roller in FIG. 11. [Figure 15] 3 is a side cross-sectional view showing a schematic configuration of a fixing device different from that in FIG. 2. [Figure 16] 16 is a front view showing a separation plate, a fixing belt, and a flange of the fixing device in FIG. 15. [Figure 17] 16 is a perspective view showing a separation claw of the fixing device shown in FIG. 15. [Figure 18] 5A and 5B are diagrams showing temperature distribution in the arrangement direction of a fixing belt, in which FIG. 5A is a plan view of a heater, and FIG. 5B is a diagram showing temperature distribution in the fixing belt. [Figure 19] FIG. 6 is a diagram showing divided regions of the heater in FIG. 5. [Figure 20] FIG. 20 is a diagram showing divided regions having a different shape from those in FIG. 19. [Figure 21] FIG. 7 is a diagram showing divided regions of the heater in FIG. 6. [Figure 22] FIG. 2 is a perspective view of a heater, a first high thermal conductive member, and a heater holder. [Diagram 23] FIG. 4 is a plan view of the heater showing the arrangement of the first high thermal conductive member. [Figure 24] 3 is a side cross-sectional view showing a schematic configuration of a fixing device according to an embodiment different from that shown in FIG. 2. [Diagram 25] 2 is a perspective view of a heater, a first highly thermally conductive member, a second highly thermally conductive member, and a heater holder. FIG. [Figure 26] 4 is a plan view of the heater showing the arrangement of the first and second high thermal conductive members. FIG. [Figure 27] FIG. 1 illustrates the atomic crystal structure of graphene. [Figure 28] FIG. 1 illustrates the atomic crystal structure of graphite. [Figure 29] 27 is a plan view showing a heater in which the arrangement of the second high thermal conductive members is different from that in FIG. 26. [Diagram 30] 25 is a side cross-sectional view showing a schematic configuration of a fixing device according to an embodiment different from that shown in FIG. 2 and FIG. 24. [Diagram 31]FIG. 4 is a side cross-sectional view showing a schematic configuration of a fixing device different from the above. [Diagram 32] FIG. 4 is a side cross-sectional view showing a schematic configuration of a fixing device different from the above. [Diagram 33] FIG. 4 is a side cross-sectional view showing a schematic configuration of a fixing device different from the above. [Diagram 34] FIG. 2 is a schematic diagram illustrating a configuration of an image forming apparatus different from that in FIG. [Diagram 35] 1 is a side cross-sectional view showing a schematic configuration of a fixing device according to an embodiment of the present invention. [Diagram 36] 36 is a plan view of a heater in the fixing device of FIG. 35. [Figure 37] FIG. 2 is a perspective view of a heater and a heater holder. [Figure 38] FIG. 4 is a perspective view showing a state in which a connector is attached to a heater. [Figure 39] FIG. 2 is a diagram showing the arrangement of a thermistor and a thermostat. [Diagram 40] FIG. 4 is a diagram showing a groove portion of a flange. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are given the same reference numerals, and the duplicated description will be appropriately simplified or omitted. Hereinafter, as an example of the heating device of the present invention, a fixing device that fixes an image on a sheet of paper as a recording medium will be illustrated.

[0011] FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention.

[0012] 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. The imaging units 1Y, 1M, 1C, and 1Bk have the same configuration except that they contain different color developers, namely, yellow, magenta, cyan, and 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.

[0013] The image forming apparatus 100 also includes an exposure device 6, a paper feeder 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 the surface. The paper feeder 7 has a paper feed tray 16 and a paper feed roller 17. The paper feeder 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 on the surface of the paper P. The paper discharge device 10 discharges the paper P outside the apparatus. The imaging units 1, the photoconductor 2, the charging device 3, the exposure device 6, the transfer device 8, etc. constitute an 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 a plurality of 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 a sheet of paper P. Each of the primary transfer rollers 12 contacts the photoconductors 2 via the intermediate transfer belt 11. As a result, the intermediate transfer belt 11 and each photoconductor 2 come into contact with each other, and a primary transfer nip is formed 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. As a result, a secondary transfer nip is formed between the secondary transfer roller 13 and the intermediate transfer belt 11.

[0015] Further, a pair of timing rollers 15 are 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 are transport members 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 an instruction to start a printing operation is given, in each of the imaging units 1Y, 1M, 1C, and 1Bk, the photoconductor 2 is rotated clockwise in FIG. 1, and the surface of the photoconductor 2 is charged to a uniform high potential by the charging device 3. Next, the exposure device 6 exposes the surface of each photoconductor 2 based on the image information of the original document read by the original reading device or the print information instructed to be printed from the terminal. This reduces the potential of the exposed portion, forming an electrostatic latent image. Then, toner is 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 each 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 as to be superimposed one on the other. 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 transferred to the paper P transported at the secondary transfer nip. This paper P is supplied from the paper supply tray 16. The paper P supplied from the paper supply device 7 is stopped once by the timing roller 15, and then transported to the secondary transfer nip in accordance with the timing at which the toner image on the intermediate transfer belt 11 reaches the secondary transfer nip. Thus, a full-color toner image is carried on the paper P. After the toner images are transferred, the toner remaining on each photoconductor 2 is removed by each cleaning device 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. Thereafter, the paper P is discharged outside the apparatus by a paper discharge device 10, completing a series of printing operations.

[0020] Next, the configuration of the fixing device will be described with reference to Fig. 2. In Fig. 2, the illustration of a static elimination brush and a separation plate, which will be described later, is omitted.

[0021] As shown in FIG. 2, the fixing device 9 according to the present embodiment includes a fixing belt 20, a pressure roller 21 as a pressure member, a heater 22 as a heating body, a heater holder 23 as a holding member, a stay 24 as a support member, a thermistor 25 as a temperature detection member, a first heat equalizing plate 28 as a highly heat conductive member, a thermostat, and the like. The fixing belt 20 is an endless belt. The pressure roller 21 contacts the outer peripheral surface of the fixing belt 20 to form 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 base material 30 and detects its temperature. The fixing member provided in the fixing device is one aspect of a rotating member provided in a heating device. The fixing device 9 according to the present embodiment is provided with the fixing belt 20 as a specific example of the fixing member.

[0022] 2 is the longitudinal direction of the fixing belt 20, pressure roller 21, heater 22, heater holder 23, stay 24, first heat equalizing plate 28, separation plate, and fixing device 9, and hereinafter this direction will be simply referred to as the longitudinal direction. Note that this longitudinal direction is also the belt width direction of the fixing belt 20 or the axial direction of the pressure roller 21, and is also the width direction of the paper being transported. The width direction of the paper is the direction perpendicular to the paper transport direction and thickness direction.

[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 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 in order to increase durability and ensure releasability. An elastic layer made of rubber or the like having a thickness of 50 to 500 μm 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 polyimide, PTFE, or the like as a sliding layer.

[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 driving 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 the 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. The heater 22 in this embodiment 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 heater 22. 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 passing 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 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. 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 (fixing nip N side) of the base material 30, but 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 transferred to the fixing belt 20 via the base material 30, it is desirable that the base material 30 be 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, even if the resistance heating element 31 is disposed on the opposite side of the base material 30 from the fixing belt 20 side, it is possible to sufficiently heat the fixing belt 20.

[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 end portions thereof are supported by both side plates of the fixing device 9. The heater holder 23 and the heater 22 are supported by the stay 24, so that the heater 22 can reliably receive the pressing force of the pressure roller 21 in a state in which the pressure roller 21 is pressed against the fixing belt 20. This allows the fixing nip N to be 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 likely to become hot due to the heat of the heater 22. For example, when the heater holder 23 is made of a heat-resistant resin with low thermal conductivity such as LCP or PEEK, the 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 23 b for holding the heater 22 .

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

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

[0033] The heater holder 23 has a detection portion through hole 23a1 penetrating in the thickness direction. A thermistor 25 is provided in the detection portion through hole 23a1 (described in detail later). The fixing device 9 is provided with an end side thermistor 25A and a center side thermistor 25B, which are referred to as thermistors 25.

[0034] The first heat equalizing plate 28 is made of a material having a higher thermal conductivity than the base material 30. In this embodiment, the first heat equalizing plate 28 is made of a 0.3 mm plate-shaped aluminum. The first heat equalizing plate 28 may be made of other materials such as copper, silver, graphene, and graphite. By making the first heat equalizing plate 28 plate-shaped, the positional accuracy of the heater 22 with respect to the heater holder 23 and the first heat equalizing plate 28 can be improved. By arranging the first heat equalizing plate 28, heat transfer in the longitudinal direction can be promoted, and the temperature of the heater 22, and therefore the fixing belt 20, can be made uniform in the longitudinal direction. By forming the first heat equalizing plate 28 from a metal material, the workability is good and the dimensional accuracy can be improved.

[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 (product name: ai-Phase Mobile 1u, ai-Phase Corporation).

[0037] In order to convert the thermal diffusivity to thermal conductivity, the values ​​of density and specific heat capacity are necessary. A dry automatic density meter (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, and sapphire was used as a reference material with a known specific heat capacity. In this embodiment, the specific heat capacity was measured five times, and the average value at 50°C was used. If the density and specific heat capacity are ρ and C, respectively, the thermal conductivity λ can be obtained from the thermal diffusivity α obtained by the thermal diffusivity measurement by the following formula (1). λ = ρ × C × α (1)

[0038] In the fixing device 9 according to the present embodiment, when a printing operation is started, the pressure roller 21 is driven to rotate, and the fixing belt 20 starts to rotate in a driven manner. 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, so that the fixing belt 20 rotates stably and smoothly. In addition, 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 the fixing temperature, which is a predetermined target temperature, as shown in FIG. 2, the paper P carrying the unfixed toner image is conveyed in the direction of the arrow A3 to the fixing nip N between the fixing belt 20 and the pressure roller 21, so that the unfixed toner image is heated and pressurized to be 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 a first electrode portion 34A and a second electrode portion 34B are provided on the surface of a plate-shaped base material 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 are also referred to as power supply lines 33, and the first electrode portion 34A or the second electrode portion 34B is also referred to as electrode portion 34.

[0041] 2, which is the longitudinal direction of the heater 22, etc., and which is perpendicular to the paper surface of FIG. 2, and which is the left-right direction X in FIG. 3, is also the arrangement direction of the multiple resistance heating elements 31. Hereinafter, this direction will also be referred to simply as the arrangement direction. Also, a direction intersecting the arrangement direction, particularly a vertical direction in this embodiment, and a vertical direction Y in FIG. 3 which is a direction different from the thickness direction of the base material 30, will also be referred to as a direction intersecting the arrangement direction of the multiple resistance heating elements 31, or simply as the arrangement intersecting direction. The arrangement intersecting direction Y is a direction along the surface of the base material 30 on which the resistance heating elements 31 are provided, and is also the short-side direction of the heater 22, or the transport direction of the paper passed through the fixing device 9.

[0042] A heating section 35 divided into a plurality of parts in the arrangement direction is formed by a plurality of resistance heating elements 31. Each resistance heating element 31 is electrically connected in parallel to a pair of electrode parts 34A, 34B via power supply lines 33A, 33B. The pair of electrode parts 34A, 34B is provided at the left end of 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 having a smaller resistance value than the resistance heating element 31. From the viewpoint of ensuring insulation between the resistance heating elements 31, the gap between the adjacent resistance heating elements 31 is preferably 0.2 mm or more, and more preferably 0.4 mm or more. In addition, if the gap between the adjacent resistance heating elements 31 is too large, a temperature drop is likely to occur in the gap. For this reason, from the viewpoint of suppressing temperature unevenness across the arrangement direction, the gap is preferably 5 mm or less, and more preferably 1 mm or less.

[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 falls.

[0044] The resistance heating element 31 has a PTC characteristic, and the heating section 35 is divided in the arrangement direction, so that the fixing belt 20 can be prevented from overheating when small-sized paper is passed through. In other words, when paper having a width smaller than the entire width of the heating section 35 is passed through, the paper does not take heat from the fixing belt 20 in the area outside the paper width, so the temperature of the resistance heating element 31 corresponding to that part rises. Since 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 rises. This relatively reduces the output of the heater, that is, the amount of heat generated, and suppresses the rise in the temperature at the end. In addition, by electrically connecting multiple resistance heating elements 31 in parallel, it is possible to suppress the temperature rise in the non-paper passing area while maintaining the printing speed. The heating element constituting the heating section 35 may be other than the resistance heating element having the PTC characteristic. In addition, the resistance heating elements may be arranged in multiple rows in the arrangement crossing direction of the heaters 22.

[0045] The resistance heating element 31 can be formed, for example, by applying a paste prepared by mixing 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 80Ω at room temperature. The material of the resistance heating element 31 may be a resistance material such as silver alloy (AgPt) or ruthenium oxide (RuO2) in addition to the above-mentioned materials. The material of the power supply line 33 and the electrode portion 34 may be silver (Ag) or silver palladium (AgPd) formed by screen printing or the like. The power supply line 33 is made of a conductor having a smaller resistance value than the resistance heating element 31.

[0046] As the material of the substrate 30, ceramics such as alumina and aluminum nitride, which have excellent heat resistance and insulation, and non-metallic materials such as glass and mica are preferable. In this embodiment, an alumina substrate having a width of 8 mm in the cross direction of the array, a width of 270 mm in the array direction, and a thickness of 1.0 mm is used. Alternatively, the substrate 30 may be formed by laminating an insulating material onto a conductive material such as a metal. As the metal material of the substrate 30, aluminum and stainless steel are preferable because they are low cost. By forming the substrate 30 from a stainless steel plate, cracks due to thermal stress can be suppressed. In addition, the substrate 30 may be formed from a material with high thermal conductivity such as copper, graphite, and graphene in order to improve the thermal uniformity of the heater 22 and increase the image quality.

[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 to insulate and protect them, and maintains the sliding property with the fixing belt 20.

[0048] The region in which the resistance heating elements 31 are provided in the longitudinal direction is the main heating region D of the heater 22, and the main heating region D also includes the region between the resistance heating elements 31. In other words, the main heating region D of the heater 22 is 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 heating region D is the main heating region by the heater 22, and the heater 22 also generates a small amount of heat outside the main heating 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 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, a portion extending from the block-shaped resistance heating element 31 toward the power supply line 33 (a portion extending in the arrangement crossing direction) may be a part of the resistance heating element 31, or may be made of the same material as the power supply line 33.

[0050] FIG. 6 is a diagram showing a power supply circuit to the heater according to this embodiment.

[0051] As shown in Fig. 6, 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 provided with a triac 210 for controlling 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 with a microcomputer including a CPU, a ROM, a RAM, an I / O interface, and the like. The control unit 220 may be provided in the fixing device or in the image forming apparatus body.

[0052] In this embodiment, an end side thermistor 25A as a first temperature detection member is disposed on one longitudinal end side of the heater 22, and a center side thermistor 25B as a second temperature detection member is disposed in a longitudinal central region of the heater 22 within the minimum paper passing width. Furthermore, a thermostat 27 as a power cutoff member that cuts off the power supply to the resistance heating element 31 when the temperature of the heater 22 becomes equal to or higher than a predetermined temperature is disposed on the other longitudinal end side of the heater 22.

[0053] Incidentally, for example, the surface layers of the fixing belt 20 and the pressure roller 21 become charged due to the fact that the charged paper P passes through the fixing nip N2 during the transfer operation. In addition, the surfaces of the fixing belt 20 and the pressure roller 21 become frictionally charged due to the rotation of the fixing belt 20 and the pressure roller 21. Then, when the paper P passes through the fixing nip N2 with the surface layers of the fixing belt 20 and the pressure roller 21 charged, the toner image on the paper P is electrostatically offset, causing an abnormal image. In addition, this charging causes the paper P to get wrapped around the fixing belt 20 or the pressure roller 21. To prevent these, the fixing device 9 of this embodiment is provided with a charge removing brush as a charge removing member.

[0054] The configuration of the static electricity removal brush will be explained using Figures 7 and 8. Figure 7 is a diagram showing the longitudinal positional relationship between the static electricity removal brush and the heater, and Figure 8 is a perspective view showing the configuration around the static electricity removal brush. Figure 7 shows only the static electricity removal brush, pressure roller, and heater, and the heater configuration is shown in a simplified form.

[0055] As shown in FIG. 7, the fixing device has a charge removing brush 37 as a charge removing member. The charge removing brush 37 has a brush portion 37a as a contact portion and a holding portion 37b. The charge removing brush 37 is grounded via a resistor. The brush portion 37a comes into contact with the conductive layer on the surface of the pressure roller 21, thereby removing the charge accumulated on the surface of the pressure roller 21. This makes it possible to prevent problems such as electrostatic offset caused by charging the pressure roller 21 or the fixing belt 20, or paper winding. Hereinafter, the range in which the brush portion 37a in the longitudinal direction comes into contact with the pressure roller 21 is referred to as a contact area E. As shown in FIG. 8, the charge removing brush 37 is attached to a side plate 38 of the fixing device.

[0056] Incidentally, calcium carbonate contained in paper, wax components contained in toner, lubricants such as grease for reducing the sliding resistance of the fixing belt, and the like are attached to the surface of the pressure roller 21, and these are also attached to the brush portion 37a that contacts the pressure roller 21. This reduces the static electricity removal performance of the static electricity removal brush 37. On the other hand, since the brush portion 37a slides against the surface of the pressure roller 21, the adhesion of the brush portion 37a is scraped off by this sliding, and the static electricity removal performance is restored. Therefore, in order to suppress the deterioration of the static electricity removal performance of the brush portion 37a, it is important to make the (speed at which dirt adheres)<(speed at which dirt is removed). However, when the static electricity removal brush 37 is exposed to a high temperature state, calcium carbonate, wax, and the like are fixed to the surface of the brush portion 37a by heat so as to be coated, and it becomes difficult to remove them by the sliding with the pressure roller 21. Therefore, the (speed at which dirt adheres)>(speed at which dirt is removed), and the static electricity removal performance of the static electricity removal brush 37 is reduced.

[0057] Therefore, in this embodiment, as shown in FIG. 7, the brush portion 37a, which is the contact portion of the static electricity removal brush 37, is provided outside the main heat generation area D of the heater 22 in the longitudinal direction. In other words, the contact area E of the brush portion 37a with the pressure roller 21 is provided outside the main heat generation area D in the longitudinal direction. This allows the brush portion 37a to be arranged avoiding the portion in the longitudinal direction where the heater 22 mainly generates heat, and the brush portion 37a is prevented from being exposed to high temperatures, thereby increasing the speed at which dirt is removed by the brush portion 37a. This prevents the static electricity removal performance of the static electricity removal brush 37 with respect to the pressure roller 21 from decreasing. This prevents problems such as electrostatic offset and paper wrapping caused by charging the surface of the pressure roller 21.

[0058] Next, the separation plate provided in the fixing device will be described with reference to the side cross-sectional view of FIG. 9 and the front view of FIG.

[0059] As shown in FIG. 9, a separation plate 40 as a separating member is provided downstream of the fixing nip N and separates the paper from the fixing belt 20. The separation plate 40 has a main body portion 40a, a separation portion 40b, and an abutment portion 40c as a contact portion. The separation portion 40b is a portion that abuts against the paper P that has passed through the fixing nip N and separates the paper P from the fixing belt 20, and in this embodiment, is particularly one end portion including one end of the main body portion 40a on the fixing belt 20 side. The abutment portion 40c is a portion that abuts against the outer circumferential surface of the fixing belt 20 and appropriately maintains a gap between the separation portion 40b and the fixing belt 20.

[0060] The separation plate 40 has a support portion 40e at one end in the longitudinal direction. A support shaft provided on the housing of the fixing device is fitted into a shaft hole provided in the support portion 40e. This allows the separation plate 40 to be rotatably supported with respect to the housing of the fixing device.

[0061] The separation plate 40 is biased by a spring in the direction of the arrow A4 in Fig. 9. As a result, the contact portion 40c comes into contact with the outer circumferential surface of the fixing belt 20.

[0062] 10, the separation plate 40 extends in the longitudinal direction X. The contact portions 40c are provided on both longitudinal sides of the separation plate 40 and contact the fixing belt 20 in non-paper passing regions on both longitudinal sides. A separation portion 40b is provided along the longitudinal direction between the contact portions 40c on both sides, on the longitudinal center side.

[0063] The separation plate 40 of the present embodiment is formed by bending a plate material. Specifically, the separation plate 40 is formed by bending the contact portion 40c and the support portion 40e in different directions relative to the main body portion 40a.

[0064] Flanges 29 serving as holding members for holding the fixing belt 20 are fitted inside both ends of the fixing belt 20 in the longitudinal direction. The flanges 29 slide against the rotating fixing belt 20 and guide the rotation.

[0065] The contact portion 40c on one side in the longitudinal direction is provided so as to overlap a part or the whole of the contact area E described above. The separation plate 40 having the contact portion 40c is the contact member in this embodiment. Thus, in this embodiment, the separation plate 40 (contact member) contacts the fixing belt 20 in the area where the brush portion 37a in the longitudinal direction contacts the pressure roller 21 (see FIG. 7) to eliminate static electricity. As a result, the lubricant and other deposits on the surface of the fixing belt 20 that the contact portion 40c in the longitudinal direction contacts are scraped off by the contact portion 40c. Alternatively, the contact portion 40c can allow the deposits to escape to one side and the other side in the longitudinal direction. This can suppress the amount of dirt that adheres to the brush portion 37a from the surface of the fixing belt 20 via the surface of the pressure roller 21. Therefore, the performance degradation of the static electricity removing brush 37 can be suppressed.

[0066] As described above, in this embodiment, as shown in Fig. 7, the contact area E is provided outside the main heat generation area D to facilitate removal of dirt from the brush portion 37a (contact portion), and as shown in Fig. 10, a separation plate 40 (contact member) is provided that contacts the fixing belt 20 over a part or the entire range of the contact area E, thereby preventing dirt from adhering to the brush portion 37a (contact portion). As a result, deterioration in the performance of the static elimination brush 37 (static elimination member) can be prevented.

[0067] Moreover, the contact area E can be provided outside the area through which the widest paper passes through the fixing device 9. This makes it possible to prevent calcium carbonate and the like contained in the paper from adhering to the brush portion 37a via the fixing belt 20 and the surface layer of the pressure roller 21. This makes it possible to further prevent the performance of the charge removal brush 37 from deteriorating.

[0068] In addition, when paper narrower than the maximum paper width that can be passed through the fixing device 9 is continuously passed through the fixing device 9, the interval at which the paper is sent to the fixing device can be made larger than that for the maximum paper width. In other words, the printing interval in the image forming apparatus can be widened to reduce printing productivity. When paper narrower than the maximum width is passed through the fixing device 9, a non-paper passing area is formed in the main heat generating area D, and the temperature is likely to rise in this non-paper passing area, which ultimately leads to a temperature rise in the brush portion 37a. In response to this, the temperature rise in the non-paper passing area and the brush portion 37a can be suppressed by widening the paper passing interval. This suppresses adhesion of dirt to the brush portion 37a, and further suppresses the performance degradation of the charge removing brush 37.

[0069] In addition, when sheets of paper smaller in width than the maximum width of the sheets of paper that can be passed through the fixing device 9 are passed through the fixing device 9 in succession, the interval between the succeeding sheets of paper can be made wider than that between the preceding sheets of paper, thereby reducing productivity. When sheets of paper with smaller widths are passed through the fixing device 9 in succession, the temperature rise in the non-paper passing area in the fixing device 9 increases as the sheets go back. For this reason, by widening the interval between the succeeding sheets of paper, the productivity can be reduced in accordance with the temperature rise in the fixing device 9. This makes it possible to effectively suppress the temperature rise in the non-paper passing area while suppressing the decrease in productivity in the image forming device and the fixing device 9 as much as possible. Therefore, it is possible to both suppress the decrease in performance of the charge removal brush 37 and ensure the productivity of the image forming device and the fixing device 9. When three or more sheets of paper with smaller widths are passed through the fixing device in succession, the interval between the sheets of paper may be widened for each sheet, or the interval between the sheets of paper may be widened when a certain number of sheets or more are passed through. It is possible to appropriately select the interval between the sheets of paper.

[0070] Furthermore, when image formation is performed continuously on coated paper, that is, when coated paper is passed through the fixing device 9 continuously, the interval between passing papers can be made wider to reduce productivity compared to when printing on other recording media, particularly plain paper. Coated paper, which has a coated surface, is prone to static electricity and requires a greater static elimination capability. For this reason, when coated paper is passed through, the productivity of the image forming device and the fixing device 9 is reduced so that the static elimination brush 37 can sufficiently eliminate static electricity from the pressure roller 21. However, the term "other recording media" as used herein may refer to all recording media compatible with the fixing device 9 except for coated paper, or may refer to some of those recording media.

[0071] Next, a modification of the contact portion 40c shown in FIG. 10 will be described.

[0072] Fig. 11 shows a portion of the contact portion 40c that contacts the surface of the fixing belt 20. In the embodiment shown in Fig. 11, the contact portion 40c has a contact width with the fixing belt 20 that increases from the upstream side to the downstream side in the rotation direction A2 of the fixing belt 20. This allows the deposits 150 flowing on the surface of the fixing belt 20 to flow to one side and the other side in the longitudinal direction along the surface of the contact portion 40c as shown in Fig. 11. This makes it possible to suppress the deposits 150 from adhering to the brush portion 37a.

[0073] 12, the contact portion 40c is inclined outward in the longitudinal direction (left side in FIG. 12) from the upstream side to the downstream side in the rotation direction A2 of the fixing belt 20. This allows the deposits 150 flowing on the surface of the fixing belt 20 to flow outward in the longitudinal direction along the surface of the contact portion 40c as shown in FIG. 12. This makes it possible to suppress the deposits 150 from adhering to the brush portion 37a. However, the contact portion 40c may be configured to be inclined inward in the longitudinal direction (right side in FIG. 12) from the upstream side to the downstream side in the rotation direction A2 of the fixing belt 20.

[0074] In the fixing device shown in FIG. 2, the separation plate 40 is provided on the fixing belt 20 side and the contact portion 40c is brought into contact with the fixing belt 20, but it may be provided on the pressure roller 21 side. For example, in the fixing device 9 of the embodiment shown in FIG. 13, the separation plate 40 as a separating member is biased in the direction of the arrow A5 to bring the contact portion 40c into contact with the surface of the pressure roller 21, and a predetermined gap is provided between the separation portion 40b and the pressure roller 21. As shown in FIG. 14, the contact portion 40c contacts the pressure roller 21 at a position overlapping the contact area E. The other configurations are basically the same as those of the embodiment of FIG. 2. That is, in this embodiment, the brush portion 37a is also provided outside the main heat generating area D (see FIG. 7) of the heater 22. These can suppress the performance degradation of the charge removing brush 37. However, in the embodiment of FIG. 13, another separating member may be provided on the fixing belt 20 side.

[0075] Next, a fixing device having a different configuration from that shown in Fig. 2 will be described with reference to Fig. 15. In the following description, differences from the embodiment shown in Fig. 2 will be mainly described.

[0076] 15 shows a fixing device 9 having an IH heater 63 as a heating element. The fixing device 9 has a fixing belt 61, a pressure roller 62, an IH heater 63, a stay 64, a nip forming member 65, a sliding sheet 66, a heat storage plate 67, a separation plate 40 and a separation claw 68 as separation members, a static elimination needle 70 as a static elimination member, and the like. In addition, on the downstream side of the fixing device 9 in the paper transport direction, an exit roller 71, a paper discharge roller 72, and a paper discharge filler 73 are provided. The paper transported to the nip portion between the exit roller 71 and the paper discharge roller 72 is discharged outside the image forming apparatus.

[0077] The IH heater 63 is fixed to the image forming apparatus main body. The coil 632 is held on the outer surface of a coil holder 631 formed along the outer peripheral surface of the fixing belt 61. At both ends of the coil holder 631 in the longitudinal direction, a fitting protrusion is provided for positioning the fixing belt 61. When power is supplied to the coil 632, a magnetic field is generated, and a current flows in the base layer of the fixing belt 61 due to electromagnetic induction, generating Joule heat in the fixing belt 61. The cores 633, 634, and 635 are formed of a ferromagnetic material and form a magnetic path that passes the magnetic flux generated by the coil 632. The main heat generation region by the IH heater 63 of this embodiment is the region where the longitudinal coil 632 is provided, and is the region from the position where the longitudinal coil 632 is provided on the most one side to the position where the longitudinal coil 632 is provided on the most other side.

[0078] The nip forming member 65 forms a fixing nip N between the pressure roller 62 and the fixing belt 61. The fixing nip N is formed along the surface shape of the nip forming member 65 on the fixing belt 61 side. In this embodiment, the nip forming member 65 is made of a resin material. A sliding sheet 66 is provided between the fixing belt 61 and the nip forming member 65, and the sliding sheet 66 is impregnated with a lubricant. The nip forming member 65 is supported by the stay 64 from its rear side, and is positioned at a position where it contacts the inner circumferential surface of the fixing belt 61 via the sliding sheet 66. The sliding sheet 66 and the lubricant are interposed between the fixing belt 61 and the nip forming member 65, thereby suppressing the sliding resistance between the fixing belt 61 and the nip forming member 65. The heat storage plate 67 contacts the inner circumferential surface of the fixing belt 61 on the IH heater 63 side. The heat storage plate 67 is formed in a semicircular arc shape along the inner circumferential surface of the fixing belt 61.

[0079] The charge elimination needle 70 is grounded. The charge elimination needle 70 brings the charge elimination portion 70a into contact with the surface layer of the fixing belt 61 to eliminate charge from the fixing belt 61. The surface layer of the fixing belt 61 is conductive. The contact position (contact area) where the tip of the charge elimination portion 70a contacts the surface layer of the fixing belt 61 is defined as contact position E'.

[0080] As shown in Fig. 16, both ends of the fixing belt 61 in the longitudinal direction are held by flanges 69. The flanges 69 have gear portions 69a. The flanges 69 are made of a resin material. A buffer material is provided between the flanges 69 and the fixing belt 61. When the fixing belt 61 is depressurized, a driving force is transmitted via the gear portions 69a, and the fixing belt 61 rotates. When the pressure roller 62 presses the fixing belt 61, the pressure roller 62 rotates in response to the rotation of the pressure roller 62.

[0081] As shown in Fig. 17, a separation plate 40 is provided on the fixing belt 61 side at the exit side of the fixing nip. Also, a separation claw 68 is provided on the pressure roller 62 side. The separation claws 68 are provided at four positions in the longitudinal direction and come into contact with the surface of the pressure roller 62. The separation claws 68 enable the paper that has passed through the fixing nip to be separated from the pressure roller and conveyed to the paper discharge section on the downstream side. The separation plate 40 has the same configuration as in the previously described embodiment.

[0082] As shown in Fig. 16, in the fixing device of this embodiment, the abutting portion 40c (contact portion) of the separation plate 40 contacts the fixing belt 61 at a position corresponding to the contact position E' in the longitudinal direction. This makes it possible to suppress dirt from adhering to the charge removing portion 70a and to suppress performance degradation of the charge removing needle 70. In addition, the contact position E' where the charge removing needle 70 contacts the fixing belt 61 is provided outside the main heat generating region D' of the IH heater 63 in the longitudinal direction. This makes it possible to suppress exposure of the charge removing portion 70a to high temperatures and to suppress performance degradation of the charge removing needle 70. The main heat generating region D' of the IH heater 63 is the region where the longitudinal coil 632 (see Fig. 15) is provided.

[0083] Next, the first heat equalizing plate 28 of the fixing device 9 shown in FIG. 2 will be described, and then modifications of the fixing device 9 having the first heat equalizing plate 28 and fixing devices of other embodiments will be described.

[0084] 18 is a diagram showing the temperature distribution in the arrangement direction of the fixing belt 20. (a) is a diagram showing the arrangement of the heaters 22. (b) shows the temperature T of the fixing belt 20 on the vertical axis and each position in the arrangement direction of the fixing belt 20 on the horizontal axis.

[0085] 18(a) and 18(b), the multiple resistance heating elements 31 provided in the heater 22 are divided in the arrangement direction, and divided regions B are formed between the resistance heating elements 31. In other words, the multiple resistance heating elements 31 provided in the heater 22 are arranged with a gap B therebetween. Hereinafter, the range B as the divided region will be referred to as the gap B.

[0086] In the interval B, the area occupied by the resistance heating element 31 is smaller than the other parts, and the amount of heat generated is smaller. As a result, the temperature of the fixing belt 20 in the interval B is smaller than the other parts, which causes temperature unevenness in the arrangement direction of the fixing belt 20. The temperatures of the heater 22 and the fixing belt 20 are also lower in an expanded divided area C (hereinafter simply referred to as area C) including the area around the interval B, which is a divided area. The temperature of the heater 22 is also lower in the interval B. Here, as shown in the enlarged view of FIG. 18(a), the interval B means an arrangement direction area including the entire part into which the resistance heating element 31, which is the main heat generating part of the heater 22, is divided in the arrangement direction. In addition to the interval B, an area including a range corresponding to the connection part 311 of the resistance heating element 31 is defined as area C. The connection part 311 refers to a part of the resistance heating element 31 that extends in the arrangement crossing direction and is connected to each of the power supply lines 33A and 33B.

[0087] As shown in Fig. 19, the temperature in the interval B is lower than the other portions in the heater 22 having the rectangular resistance heating element 31 shown in Fig. 4. The temperature in the interval B is also lower than the other portions in the heater 22 having the resistance heating element 31 shaped as shown in Fig. 20. Furthermore, as shown in Fig. 21, the temperature in the interval B is also lower than the other portions in the heater 22 having the resistance heating element 31 shaped as shown in Fig. 5. However, by overlapping adjacent resistance heating elements 31 in the arrangement direction as in Figs. 18, 20 and 21, the temperature drop in the other portions of the interval B can be suppressed.

[0088] In this embodiment, the above-mentioned first heat equalizing plate 28 is provided to suppress the temperature drop in the above-mentioned interval and to suppress temperature unevenness in the arrangement direction of the fixing belt 20. The first heat equalizing plate 28 will be described in more detail below.

[0089] 2, the first heat equalizing plate 28 is disposed between the heater 22 and the stay 24 in the left-right direction of Fig. 2, and is particularly sandwiched between the heater 22 and the heater holder 23. That is, the first heat equalizing plate 28 has one surface in contact with the rear surface of the base material 30 and the other surface in contact with the heater holder 23.

[0090] The stay 24 supports the heater holder 23, the first heat equalizing plate 28, and the heater 22 by directly abutting the abutment surfaces of two vertical portions 24a extending in the thickness direction of the heater 22 etc. against the heater holder 23. In the array crossing direction (the up-down direction in FIG. 2), the abutment surfaces are provided outside the range in which the resistance heating element 31 is provided. This makes it possible to suppress heat transfer from the heater 22 to the stay 24, and allows the heater 22 to heat the fixing belt 20 efficiently.

[0091] As shown in Fig. 22, the first heat equalizing plate 28 is made of a plate material having a thickness of 0.3 mm, a length in the arrangement direction of 222 mm, and a width in the arrangement cross direction of 10 mm. In this embodiment, the first heat equalizing plate 28 is made of a single plate material, but it may be made of a plurality of members. Note that the illustration of the guide ribs 26 in Fig. 2 is omitted in Fig. 22.

[0092] The first heat equalizing plate 28 is fitted into the holding recess 23b of the heater holder 23, and the heater 22 is attached from above, so that the first heat equalizing plate 28 is sandwiched and held between the heater holder 23 and the heater 22. The movement of the first heat equalizing plate 28 and the heater 22 in the arrangement direction is restricted by both side walls (arrangement direction restricting parts) 23b1 in the arrangement direction that form the holding recess 23b. In this way, by restricting the positional deviation of the first heat equalizing plate 28 in the arrangement direction within the fixing device 9, it is possible to improve the heat conduction efficiency within a target range in the arrangement direction. In addition, the movement of the first heat equalizing plate 28 and the heater 22 in the arrangement cross direction is restricted by both side walls (arrangement cross direction restricting parts) 23b2 in the arrangement cross direction that form the holding recess 23b.

[0093] The range in the arrangement direction in which the first heat equalizing plate 28 is provided is not limited to the above. For example, as shown in Fig. 23, the first heat equalizing plate 28 may be provided only in the range in the arrangement direction corresponding to the heat generating portion 35 (see the hatched portion in Fig. 23).

[0094] The first heat equalizing plate 28 is sandwiched between the heater 22 and the heater holder 23 by the pressure of the pressure roller 21 and is in close contact with these members. The first heat equalizing plate 28 comes into contact with the heater 22, thereby improving the heat conduction efficiency in the arrangement direction of the heater 22. The first heat equalizing plate 28 is provided at a position corresponding to the interval B of the heater 22 in the arrangement direction, thereby improving the heat conduction efficiency in the interval B. This increases the amount of heat transferred to the area of ​​the interval B in the arrangement direction, and increases the temperature in the area of ​​the interval B in the arrangement direction. This makes it possible to suppress temperature unevenness in the arrangement direction of the heater 22. This makes it possible to suppress temperature unevenness in the arrangement direction of the fixing belt 20. This makes it possible to suppress uneven fixing and uneven gloss of the image fixed on the paper. Alternatively, in order to ensure sufficient fixing performance in the area of ​​the interval B, it is not necessary to apply extra heat by the heater 22, and energy saving of the fixing device 9 can be realized. In addition, by providing the first heat equalizing plate 28 over the entire area of ​​the heat generating section 35 in the arrangement direction, the heat transfer efficiency of the heater 22 can be improved over the entire area that is the main heating area by the heater 22, i.e., the image forming area of ​​the paper being passed through, and temperature unevenness in the arrangement direction of the heater 22 and therefore the fixing belt 20 can be suppressed.

[0095] Particularly in this embodiment, the combination of the configuration of the first heat equalizing plate 28 and the resistance heating element 31 having the PTC characteristic described above can effectively suppress excessive temperature rise in the non-paper passing area when small size paper is passed. In other words, the PTC characteristic suppresses the amount of heat generated by the resistance heating element 31 in the non-paper passing area, and the heat of the non-paper passing area with an increased temperature can be efficiently transferred to the paper passing area, effectively suppressing excessive temperature rise in the non-paper passing area.

[0096] Also, since the temperature around the gap B is low due to the small amount of heat generated in the gap B, it is preferable to place the first heat equalizing plate 28. For example, in this embodiment, the first heat equalizing plate 28 is provided at a position corresponding to the region C (see FIG. 19), thereby particularly improving the heat transfer efficiency in the arrangement direction in the gap B and its periphery, and further suppressing the temperature unevenness in the arrangement direction of the heaters 22. Particularly in this embodiment, the first heat equalizing plate 28 is provided over the entire area of ​​the heat generating section 35 in the arrangement direction. This makes it possible to further suppress the temperature unevenness in the arrangement direction of the heaters 22 (fixing belt 20).

[0097] Next, a different embodiment of the fixing device will be described.

[0098] As shown in Fig. 24, the fixing device 9 of this embodiment has a second heat equalizer plate 36 as a second high thermal conductive member between the heater holder 23 and the first heat equalizer plate 28. The second heat equalizer plate 36 is provided at a position different from that of the first heat equalizer plate 28 in the left-right direction of Fig. 24, which is the stacking direction of members such as the heater holder 23, the stay 24, and the first heat equalizer plate 28. More specifically, the second heat equalizer plate 36 is provided overlapping the first heat equalizer plate 28. Note that Fig. 24 shows a cross section in which the thermistor 25 is not arranged in the arrangement direction, unlike Fig. 2. In other words, Fig. 24 shows a cross section in which the second heat equalizer plate 36 is arranged.

[0099] The second heat equalizer 36 is made of a material having a higher thermal conductivity than the base material 30, such as graphene or graphite. In this embodiment, the second heat equalizer 36 is made of a graphite sheet having a thickness of 1 mm. However, the second heat equalizer 36 may be made of a plate material such as aluminum, copper, or silver.

[0100] As shown in Fig. 25, a plurality of second heat equalizing plates 36 are arranged in the arrangement direction, each of which is partially provided in the arrangement direction. The portion of the holding recess 23b of the heater holder 23 where the second heat equalizing plate 36 is provided is provided one step deeper than the other portion. A gap is provided between the second heat equalizing plate 36 and the heater holder 23 on both sides in the arrangement direction. This suppresses heat transfer from both ends of the second heat equalizing plate 36 in the arrangement direction to the heater holder 23, allowing the heater 22 to efficiently heat the fixing belt 20. Note that the illustration of the guide rib 26 in Fig. 2 is omitted in Fig. 25.

[0101] 26, the second heat equalizing plate 36 (see hatched portion) is provided at a position in the arrangement direction corresponding to the interval B so as to overlap at least a portion of the adjacent resistance heating elements 31, and in this embodiment in particular, is provided over the entire area of ​​the interval B. The second heat equalizing plate 36 is disposed at a position in the longitudinal direction where no thermistor or thermostat is disposed.

[0102] In one embodiment of the present invention different from the above, the first heat equalizer plate 28 and the second heat equalizer plate 36 are formed from the graphene sheet. This makes it possible to form the first heat equalizer plate 28 and the second heat equalizer plate 36 with high thermal conductivity in a predetermined direction along the graphene surface, that is, in the arrangement direction rather than the thickness direction. This makes it possible to effectively suppress temperature unevenness in the arrangement direction of the heater 22 and the fixing belt 20.

[0103] Graphene is a flaky powder. As shown in FIG. 27, graphene is composed of a planar hexagonal lattice structure of carbon atoms. A graphene sheet is a sheet of graphene, and is 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 in which five-membered and six-membered rings are condensed into a cage shape, and examples of such a compound include C 60 , C 70 and C 80 It is a fullerene or other closed cage structure with three coordinated carbon atoms.

[0104] Graphene sheets are man-made and can be produced, for example, by chemical vapor deposition (CVD) techniques.

[0105] 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 below, may be measured, for example, by a transmission electron microscope (TEM).

[0106] Moreover, graphite, which is a multi-layered graphene, has a large thermal conductivity anisotropy. As shown in FIG. 28, graphite has a layer in which the condensed six-membered ring layer plane of carbon atoms spreads in a planar shape, and has a crystal structure in which these layers are stacked on top of each other. In this crystal structure, adjacent carbon atoms in a layer form a covalent bond, and carbon atoms between layers form a van der Waals bond. The covalent bond has a larger bond strength than the van der Waals bond, and has a large anisotropy between the bond within the layer and the bond between the layers. In other words, by forming the first heat equalizer plate 28 or the second heat equalizer plate 36 from graphite, the heat transfer efficiency in the arrangement direction of the first heat equalizer plate 28 or the second heat equalizer plate 36 is larger than that in the thickness direction (i.e., the stacking direction of the members), and the heat transfer to the heater holder 23 can be suppressed. Therefore, the temperature unevenness in the arrangement direction of the heater 22 can be efficiently suppressed, and the heat flowing out to the heater holder 23 side can be minimized. Furthermore, by forming the first heat equalizer plate 28 or the second heat equalizer plate 36 from graphite, the first heat equalizer plate 28 or the second heat equalizer plate 36 can have excellent heat resistance that prevents oxidation up to approximately 700 degrees.

[0107] The physical properties and dimensions of the graphite sheet can be appropriately changed depending on the function required for the first heat equalizer plate 28 or the second heat equalizer plate 36. For example, the anisotropy of the thermal conduction can be increased by using high-purity graphite or single crystal graphite, or by increasing the thickness of the graphite sheet. Also, in order to increase the speed of the fixing device 9, a graphite sheet with a small thickness may be used to reduce the thermal capacity of the fixing device 9. Also, when the width of the fixing nip N or the heater 22 is large, the width of the first heat equalizer plate 28 or the second heat equalizer plate 36 in the arrangement direction may be increased accordingly.

[0108] From the viewpoint of increasing mechanical strength, the number of layers of the graphite sheet is preferably equal to or greater than 11. The graphite sheet may partially include a single layer portion and a multilayer portion.

[0109] The second heat equalizer 36 is provided at a position corresponding to the interval B (and further to the region C) in the arrangement direction so as to overlap at least a portion of the adjacent resistance heating elements 31, and is not limited to the arrangement shown in Fig. 26. For example, as shown in Fig. 29, the second heat equalizer 36A is provided protruding beyond the base material 30 on both sides in the arrangement cross direction. The second heat equalizer 36B is provided in a range in the arrangement cross direction where the resistance heating elements 31 are provided. The second heat equalizer 36C is provided in a portion of the interval B.

[0110] As shown in FIG. 30, in this embodiment, a gap is provided between the first heat equalizing plate 28 and the heater holder 23 in the thickness direction, ie, the left-right direction in FIG. 30. That is, in a part of the holding recess 23b (see FIG. 25) for arranging the heater 22, the first heat equalizing plate 28, and the second heat equalizing plate 36 of the heater holder 23, a relief portion 23c is provided as a heat insulating layer that makes the depth of the holding recess 23b deeper than the other part that receives the first heat equalizing plate 28. This part is a part or the whole of the part other than the part where the second heat equalizing plate 36 is provided in the arrangement direction, and is a part of the arrangement cross direction. This makes it possible to minimize the contact area between the heater holder 23 and the first heat equalizing plate 28. Therefore, the heat transfer from the first heat equalizing plate 28 to the heater holder 23 is suppressed, and the heater 22 can efficiently heat the fixing belt 20. In addition, in the cross section in the arrangement direction where the second heat equalizing plate 36 is provided, the second heat equalizing plate 36 abuts against the heater holder 23 as in FIG. 24 of the above-mentioned embodiment.

[0111] 30, which is the array crossing direction, the relief portion 23c is provided over the entire area where the resistance heating element 31 is provided. This particularly suppresses heat transfer from the first heat equalizing plate 28 to the heater holder 23, allowing the heater 22 to efficiently heat the fixing belt 20. Note that, as the heat insulating layer, in addition to a configuration in which a space is provided like the relief portion 23c, a configuration in which a heat insulating member having a lower thermal conductivity than the heater holder 23 is provided may also be used.

[0112] Furthermore, in the above description, the second heat equalizing plate 36 is provided as a member different from the first heat equalizing plate 28, but this is not limited to the above. For example, the portion of the first heat equalizing plate 28 corresponding to the interval B may be made thicker than the other portions.

[0113] 24 and 30, the above-mentioned configurations of the charge removing member, contact member (separating member), heater, etc. can be adopted, thereby making it possible to suppress the performance degradation of the charge removing member due to adhesion.

[0114] Although an embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0115] Further, in addition to the fixing device described above, the present invention is also applicable to fixing devices as shown in Figures 31 to 33. The configuration of each fixing device shown in Figures 31 to 33 will be briefly described below.

[0116] First, in the fixing device 9 shown in FIG. 31, a pressure roller 39 is disposed on the opposite side of the fixing belt 20 to the pressure roller 21 side. The pressure roller 39 is a counter rotating member that rotates opposite the fixing belt 20 as a rotating member. The pressure roller 39 and the heater 22 are configured to sandwich and heat the fixing belt 20. On the other hand, on the pressure roller 21 side, a nip forming member 41 is disposed 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.

[0117] 32, the above-mentioned pressure roller 39 is omitted, and in order to ensure the circumferential contact length between the fixing belt 20 and the heater 22, the heater 22 is formed in an arc shape in accordance with 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.

[0118] Finally, the fixing device 9 shown in FIG. 33 will be described. The fixing device 9 is composed of a heating assembly 42, a fixing roller 43 which is a rotating member, and a pressure assembly 44 which is an opposing member. The heating assembly 42 has the heater 22, the first heat equalizer plate 28, the heater holder 23, the stay 24, the heating belt 48, and the like, which have been described in the previous embodiment. The fixing roller 43 is an opposing rotating member which rotates opposite to the heating belt 48 which is 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 outside of the elastic layer 43b. The pressure assembly 44 is provided on the opposite side of the fixing roller 43 from the heating assembly 42 side. The pressure assembly 44 has a nip forming member 45 and a stay 46 arranged therein, and a pressure belt 47 as a pressure member 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, where it is heated and pressurized to fix the image. The fixing roller 43 in this embodiment is heated by contacting with the heating belt 48 heated by the heater 22. In other words, the heater 22 indirectly heats the fixing roller 43 via the heating belt 48.

[0119] 31 to 33, the above-mentioned configurations of the charge removing member, contact member (separating member), heater, etc. can be adopted, thereby making it possible to suppress the performance degradation of the charge removing member due to adhesion.

[0120] The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIG. 1, but may be a monochrome image forming apparatus, a copying machine, a printer, a facsimile, or a combination machine of these.

[0121] 34, for example, image forming apparatus 100 of this embodiment includes image forming means 50 including a photosensitive drum and the like, a paper transport section including a pair of timing rollers 15 and the like, paper feeder 7, fixing device 9, paper discharge device 10, and reading section 51. Paper feeder 7 includes a plurality of paper feed trays 16 and paper feed rollers 17, and each paper feed tray 16 stores paper of a different size.

[0122] The reading unit 51 reads an image of the document Q. The reading unit 51 generates image data from the read image. The paper feeder 7 stores a plurality of sheets P and sends the sheets P to a conveying path. The timing rollers 15 convey the sheets P on the conveying path to the image forming means 50.

[0123] The image forming means 50 forms a toner image on the paper P. Specifically, the image forming means 50 includes a photosensitive drum, a charging roller, an exposure device, a developing device, a replenishing device, a transfer roller, a cleaning device, and a charge removing device. The toner image represents, for example, an image of an original Q. The fixing device 9 applies heat and pressure to the toner image to fix the toner image to the paper P. The paper P on which the toner image has been fixed is transported to the paper discharge device 10 by a transport roller or the like. The paper discharge device 10 discharges the paper P outside the image forming apparatus 100.

[0124] Next, a fixing device 9 of this embodiment will be described. Descriptions of configurations common to the fixing devices of the above-mentioned embodiments will be omitted as appropriate.

[0125] As shown in FIG. 35, 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, a first heat equalizing plate 28, and the like.

[0126] 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.

[0127] The fixing belt 20 has a polyimide base and a release layer, and does not have an elastic layer. The release layer is made of a heat-resistant film material such as fluororesin. The outer diameter of the fixing belt 20 is about 24 mm.

[0128] The pressure roller 21 includes a core metal 21a, an elastic layer 21b, and a release layer 21c. The pressure roller 21 has an outer diameter of 24 to 30 mm, and the elastic layer 21b has a thickness of 3 to 4 mm.

[0129] The heater 22 includes a base material, a heat insulating layer, a conductor layer including a resistance heating element, and an insulating layer, and is formed to have an overall thickness of 1 mm. The width Y of the heater 22 in the array crossing direction is 13 mm.

[0130] As shown in FIG. 36, 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. In this embodiment, as shown in the enlarged view of FIG. 36, the resistance heating elements 31 are divided in the arrangement direction to form intervals B (although the intervals B are only shown in the enlarged view of FIG. 36, the intervals B are actually provided between all of the resistance heating elements 31). The resistance heating elements 31 form three heat generating portions 35A to 35C. By passing a current through the electrode portions 34A and 34B, the heat generating portions 35A and 35C generate heat. By passing a current through the electrode portions 34A and 34C, the heat generating portion 35B generates heat. For example, when performing a fixing operation on a small size paper, the heat generating portion 35B is made to generate heat, and when performing a fixing operation on a large size paper, all of the heat generating portions are made to generate heat.

[0131] As shown in Fig. 37, the heater holder 23 holds the heater 22 and the first heat equalizing plate 28 in the recess 23d. The recess 23d is provided on the heater 22 side of the heater holder 23. The recess 23d is composed of a surface 23d1 that is approximately parallel to the base material 30 and is recessed toward the stay 24 side more than the other surfaces of the heater 22, a wall portion 23d2 provided on the inside of the heater holder 23 on both sides in the arrangement direction of the heater holder 23 (or on one side), and a wall portion 23d3 provided on the inside of the heater holder 23 on both sides in the arrangement crossing direction. The heater holder 23 has a guide rib 26. The heater holder 23 is formed of LCP (liquid crystal polymer).

[0132] As shown in FIG. 38, connector 55 includes a housing made of resin (for example, LCP), and a plurality of contact terminals provided in the housing.

[0133] The connector 55 is attached so as to sandwich the heater 22 and the heater holder 23 from the front and back sides together. In this state, each contact terminal comes into contact (pressure-welded) with each electrode portion of the heater 22, electrically connecting the heat generating portion 35 and the power source provided in the image forming apparatus via the connector 55. This enables power to be supplied from the power source to the heat generating portion 35. Note that in order to ensure connection with the connector 55, at least a portion of each electrode portion 34 is not covered with an insulating layer and is exposed.

[0134] The flanges 53 are provided on both sides of the fixing belt 20 in the arrangement direction, 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 stays 24 (see the arrow directions from the flanges 53 in FIG. 38).

[0135] The attachment direction of the connector 55 to the heater 22 and the heater holder 23 is the direction that crosses the arrangement of the heaters (see the direction of the arrow from the connector 55 in FIG. 38). When the connector 55 is attached to the heater holder 23, a convex portion provided on one of the connector 55 and the heater holder 23 may be engaged with a concave portion provided on the other, and the convex portion may move relatively within the concave portion. The connector 55 is attached to the heater 22 and the heater holder 23 on one side of the arrangement direction, opposite to the side on which the drive motor of the pressure roller 21 is provided.

[0136] 39, thermistors 25 are provided on the center side and end side of the arrangement direction of fixing belt 20, facing the inner circumferential surface of fixing belt 20. Heater 22 is controlled based on the temperatures detected by the thermistors 25 on the center side and end side of the arrangement direction of fixing belt 20.

[0137] Thermostats 27 are provided on the central side and end sides of the arrangement direction of fixing belt 20, facing the inner circumferential surface of fixing belt 20. When the temperature of fixing belt 20 detected by thermostat 27 exceeds a predetermined threshold value, power supply to heater 22 is stopped.

[0138] Flanges 53 are provided on both ends of the fixing belt 20 in the arrangement direction to hold the respective ends of the fixing belt 20. The flanges 53 are made of LCP (liquid crystal polymer).

[0139] 40, a slide groove 53a is provided in the flange 53. The slide groove 53a extends in the direction in which the fixing belt 20 approaches and separates from the pressure roller 21. An engagement portion of the housing of the fixing device 9 engages with the slide groove 53a. The engagement portion moves relatively within the slide groove 53a, so that the fixing belt 20 can move in the direction in which the fixing belt 20 approaches and separates from the pressure roller 21.

[0140] The fixing device 9 may also employ the above-described configurations of the charge removing member, contact member (separating member), heater, etc. This makes it possible to suppress the performance degradation of the charge removing member caused by attached matter.

[0141] Examples of 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, and the like.

[0142] Furthermore, the heating device of the present invention is not limited to the fixing device as described in the above embodiment. In other words, it may be a heating device such as a drying device that dries ink applied to paper, a laminator that thermocompresses a film as a covering member onto the surface of a sheet such as paper, or a thermocompression device such as a heat sealer that thermocompresses the seal portion of a packaging material. Such a heating device may also employ the configuration of the static elimination member, contact member (separation member), heater, etc. described above. This makes it possible to suppress the performance degradation of the static elimination member due to adhesion.

[0143] In the above description, the surface layer of the fixing member or the pressure member is formed as a conductive layer, and the charge removing member is in contact with the conductive layer. However, the present invention is not limited to this, and it is sufficient that a part of the surface of the fixing member or the pressure member is conductive. For example, a part of the conductive layer provided on the inside of the fixing member or the pressure member may be exposed to the outside.

[0144] In the above description, the contact member of the present invention is exemplified as a separation member that separates the recording medium from the fixing member or the pressure member, but other members may be used. For example, the contact member may be a contact-type temperature detection member such as a thermistor, or a new contact member may be provided separately. By using the contact member as the separation member, it is not necessary to provide a new member separately, and the number of parts of the fixing device can be reduced. The shape of the separation member is not limited to the above-mentioned separation plate 40 and separation claw 68. The fixing device 9 of FIG. 2 may be provided with the separation claw 68 of FIG. 15, or the static elimination needle 70 may be provided instead of the static elimination brush 37. Conversely, the fixing device 9 of FIG. 15 may be provided with the static elimination brush 37.

[0145] For example, aspects of the present invention are as follows. <1> A rotating member; A heating body having a main heating region and configured to heat the rotating member; a pressing member having a conductive surface for pressing the rotating member; a charge removing member in contact with the pressure member; A heating device comprising: a contact member that contacts the rotating member, the static electricity removing member contacts the pressing member at a contact area that is outer than the main heat generating area in a longitudinal direction of the rotating member, The heating device is characterized in that the contact member contacts the rotating member at a position in the longitudinal direction corresponding to the contact area. <2> The charge removing member contacts the pressure member outside a passage area of ​​the recording medium having the maximum width that the heating device in the longitudinal direction can accommodate. <1> The heating device described herein is <3> the contact member is a separating member that is provided downstream of the rotating member in a recording medium transport direction and separates the recording medium from the rotating member; The contact member has a contact portion and a separation portion, The contact portion comes into contact with the rotating member, thereby providing a predetermined gap between the separating portion and the rotating member. <1> or <2> The heating device described herein is <4> The contact width of the contact member with the rotating member increases from the upstream side to the downstream side in the rotation direction of the rotating member. <1> from <3> The heating device according to any one of the preceding claims. <5> The contact member has a contact portion that contacts the rotating member and is inclined in one direction of the rotating member with respect to the rotation direction of the rotating member. <1> from <3> The heating device according to any one of the preceding claims. <6> a rotating member having a conductive surface; A heating body that heats the rotating member; A pressure member that presses the rotating member; a static eliminator in contact with the rotating member; A heating device comprising: a separating member having a contact portion that contacts the rotating member, This is a heating device characterized in that, when the area in the longitudinal direction of the rotating member where the de-ionizing member contacts the rotating member is defined as a contact area, the contact portion contacts the rotating member at a position corresponding to the contact area. <7> The heater has a main heating area, The separation member is in contact with the rotation member at the contact portions provided on both sides of the rotation member in the longitudinal direction, and faces the rotation member with a gap between the contact portions on both sides, The static electricity removing member is in contact with the rotating member outside the main heat generating region in the longitudinal direction. <6> The heating device described herein is <8> A rotating member; A heating body having a main heating region and configured to heat the rotating member; a pressing member having a conductive surface for pressing the rotating member; a charge removing member in contact with the pressure member; A heating device including: a separating member having a contact portion that contacts the pressing member, the separating member is in contact with the pressing member at the contact portions provided on both sides of the rotating member in the longitudinal direction, and faces the pressing member with a gap between the contact portions on both sides; the static electricity removing member contacts the pressing member at a contact area that is outer than the main heat generating area in a longitudinal direction of the rotating member, The heating device is characterized in that the contact portion contacts the pressure member at a position corresponding to the contact area in the longitudinal direction. <9> <1> from <8> The fixing device includes any one of the heating devices and fixes an image by heat. <10> <9> An image forming apparatus including the fixing device described above. <11> When an image forming apparatus performs successive image forming operations on a recording medium having a width smaller than the maximum recording medium that the image forming apparatus can accommodate, the interval at which the recording medium is fed to a fixing device is made larger than that for the recording medium having the maximum width. <10> The image forming apparatus is as described above. <12> When an image forming apparatus performs successive image forming operations on recording media having a width smaller than the maximum width of the recording media that the image forming apparatus can accommodate, the interval at which the subsequent recording media are fed to the fixing device is made larger than the interval at which the previous recording media are fed to the fixing device. <11> The image forming apparatus is as described above. <13> When performing an image forming operation on coated paper as the recording medium, the interval at which the recording medium is fed to the fixing device is made larger than that in the case of other recording media. <10> from <12> The image forming apparatus according to any one of the preceding claims. [Explanation of symbols]

[0146] 1. Image forming device 9 Fixing device (heating device) 20 Fixing belt (rotating member) 21 Pressure roller (pressure member) 22 Heater (heating element) 31 Resistance heating element 37 Antistatic brush (antistatic material) 37a Brush part (static removal part) 40 Separation plate (contact member) 40b Separation part 40c contact part A2 Rotation direction of the fixing belt (rotation direction of the rotating parts) A3 Paper transport direction (recording medium transport direction) D Main heating area of ​​the heater (main heating area of ​​the heating element) E Brush contact area N Fixing nip (nip part) X Longitudinal direction [Prior art documents] [Patent documents]

[0147] [Patent Document 1] JP 2010-128298 A

Claims

1. A rotating member; A heating body having a main heating region and configured to heat the rotating member; a pressing member having a conductive surface for pressing the rotating member; a charge removing member in contact with the pressure member; A heating device comprising: a contact member that contacts the rotating member, the static electricity removing member contacts the pressing member at a contact area that is outer than the main heat generating area in a longitudinal direction of the rotating member, A heating device, characterized in that the contact member contacts the rotating member at a position in the longitudinal direction corresponding to the contact area.

2. 2. The heating device according to claim 1, wherein the charge removing member contacts the pressure member outside a region in the longitudinal direction through which the heating device passes a maximum width of the recording medium.

3. the contact member is a separating member that is provided downstream of the rotating member in a recording medium transport direction and separates the recording medium from the rotating member; The contact member has a contact portion and a separation portion, The heating device according to claim 1 , wherein the contact portion comes into contact with the rotating member to provide a predetermined gap between the separating portion and the rotating member.

4. 2. The heating device according to claim 1, wherein a contact width of the contact member with the rotating member increases from an upstream side to a downstream side in a rotation direction of the rotating member.

5. 2. The heating device according to claim 1, wherein the contact member has a contact portion that contacts the rotating member and is inclined in one direction of the rotating member with respect to a rotation direction of the rotating member.

6. a rotating member having a conductive surface; A heating body that heats the rotating member; A pressure member that presses the rotating member; a static eliminator in contact with the rotating member; A heating device comprising: a separating member having a contact portion that contacts the rotating member, A heating device characterized in that, when a region in the longitudinal direction of the rotating member where the de-ionizing member contacts the rotating member is defined as a contact region, the contact portion contacts the rotating member at a position corresponding to the contact region.

7. The heater has a main heating area, The separation member is in contact with the rotation member at the contact portions provided on both sides of the rotation member in the longitudinal direction, and faces the rotation member with a gap between the contact portions on both sides, The heating device according to claim 6 , wherein the static electricity removing member is in contact with the rotating member outside the main heat generating region in the longitudinal direction.

8. A rotating member; A heating body having a main heating region and configured to heat the rotating member; a pressing member having a conductive surface for pressing the rotating member; a charge removing member in contact with the pressure member; A heating device including: a separating member having a contact portion that contacts the pressing member, the separating member is in contact with the pressing member at the contact portions provided on both sides of the rotating member in the longitudinal direction, and faces the pressing member with a gap between the contact portions on both sides; the static electricity removing member contacts the pressing member at a contact area that is outer than the main heat generating area in a longitudinal direction of the rotating member, A heating device, characterized in that the contact portion is in contact with the pressure member at a position corresponding to the contact area in the longitudinal direction.

9. A fixing device comprising the heating device according to claim 1 , for fixing an image by heat.

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

11. 11. The image forming apparatus according to claim 10, wherein when the image forming apparatus performs successive image forming operations on a recording medium having a width smaller than the maximum recording medium that the image forming apparatus can accommodate, the interval at which the recording medium is fed to the fixing device is made larger than that for the recording medium of the maximum width.

12. 12. An image forming apparatus according to claim 11, wherein when the image forming apparatus performs successive image forming operations on recording media having a width smaller than the maximum width of the recording media it can handle, the interval at which the subsequent recording media are fed to the fixing device is made larger than the interval at which the previous recording media are fed.

13. 11. The image forming apparatus according to claim 10, wherein when an image is formed on coated paper as the recording medium, an interval at which the recording medium is fed to the fixing device is made larger than that in the case of other recording media.

Images