Heater, heating device, and image forming apparatus

Abstract

The present invention relates to a heater including a substrate, an insulating layer provided on the substrate, and a heat generating element provided on the insulating layer, in a case where a region including a center of the substrate is defined as a first region, a region closer to one end portion side than the first region is defined as a second region, and a region closer to the other end portion side than the first region is defined as a third region along a lateral direction orthogonal to a longitudinal direction of a surface of the substrate on which the insulating layer is provided, the first region is a flat surface, and the second region and the third region are curved from the first region along a thickness direction of the substrate orthogonal to the longitudinal direction and the lateral direction. The present disclosure also relates to a heating device and an image forming apparatus.

Description

Technical Field

[0001] This invention relates to heaters used in image forming apparatuses such as copiers and printers that employ electrophotographic or electrostatic recording systems. Furthermore, this invention relates to heating devices for fixing units on which heaters are mounted, and gloss-imparting devices for improving the gloss of toner images by reheating the toner image on the recording material. Additionally, this invention relates to image forming apparatuses that include heating devices. Background Technology

[0002] As a heating device installed on a printer or copier based on an electrophotographic system, a typical configuration includes a heater, a film, and a pressure roller. The heater includes a heating resistor on a substrate, the film moves while in contact with the heater, and the pressure roller forms a clamping portion with the heater through the film. As for the substrate used in the heater of such a device, as described in Japanese Patent Application Publication No. 10-275671, a substrate made of metal can be used to withstand thermal stress. Summary of the Invention

[0003] The aim is to improve the heater, which includes a substrate made of metal.

[0004] To achieve the above objectives, the heater according to the present invention comprises:

[0005] A slender substrate made of metal;

[0006] An insulating layer disposed on the substrate; and

[0007] Heating element disposed on the insulating layer

[0008] Wherein, in the case that the region including the center of the substrate is defined as the first region, along the lateral direction, a region closer to one end side than the first region is defined as the second region, and a region closer to another end side than the first region is defined as the third region, the lateral direction being orthogonal to the longitudinal direction of the surface of the substrate on which the insulating layer is provided, the first region being planar, and

[0009] The second region and the third region are bent from the first region along the thickness direction of the substrate, which is orthogonal to the longitudinal direction and the transverse direction.

[0010] Further features of the invention will become apparent from the following description of exemplary embodiments, with reference to the accompanying drawings. Attached Figure Description

[0011] Figure 1 The overall configuration diagram of the device is formed based on the image in Example 1.

[0012] Figure 2 It is a cross-sectional view of the fixing device according to Example 1.

[0013] Figure 3 It is an exploded perspective view of the membrane unit based on Example 1.

[0014] Figure 4 This is a front view of the fixing device according to Example 1.

[0015] Figure 5 It is a cross-sectional perspective view of the fixing device according to Example 1.

[0016] Figure 6A and 6B These are, respectively, a perspective view of the substrate according to Example 1 and a cross-sectional view of the fixing device.

[0017] Figure 7A and 7B This is a schematic diagram of the heater based on the comparative example.

[0018] Figure 8 This is a cross-sectional perspective view of the fixing device according to Variation Example 1.

[0019] Figure 9A and 9B These are, respectively, a perspective view of the heater and a cross-sectional view of the fixing device according to Variation Example 1.

[0020] Figure 10 This is a cross-sectional perspective view of the fixing device according to Variation Example 2.

[0021] Figure 11A and 11B These are, respectively, a perspective view of the heater and a cross-sectional view of the fixing device according to Variation Example 2.

[0022] Figure 12 It is a cross-sectional perspective view of the fixing device according to Example 2.

[0023] Figure 13A and 13B These are, respectively, a perspective view of the substrate and a cross-sectional view of the fixing device according to Example 2.

[0024] Figure 14A and 14B These are, respectively, a perspective view of the heater and a cross-sectional view of the fixing device according to Variation Example 3.

[0025] Figure 15A and 15B These are, respectively, a perspective view of the heater and a cross-sectional view of the fixing device according to Variation Example 4.

[0026] Figure 16 It is a cross-sectional perspective view of the fixing device according to Example 3.

[0027] Figure 17A and 17B These are a schematic diagram of the heater based on Example 3 and a cross-sectional view of the fixing device near the heater, respectively.

[0028] Figure 18 This is a cross-sectional view of the fixing device near the heater according to variant example 5.

[0029] Figure 19 It is a cross-sectional perspective view of the fixing device according to Example 4.

[0030] Figure 20 It is a cross-sectional view of the fixing device according to Example 4.

[0031] Figure 21 This is a cross-sectional view of the fixing device based on variant example 6.

[0032] Figure 22 The overall configuration diagram of the device is formed based on the image in Example 5.

[0033] Figure 23 It is a cross-sectional view of the fixing device according to Example 5.

[0034] Figure 24A and 24B This is a perspective view of the membrane unit and thermally conductive component based on Example 5.

[0035] Figure 25 This is a front view of the fixing device according to Example 5.

[0036] Figure 26A and 26B These are the cross-sectional and plan views of the heater based on Example 5, respectively.

[0037] Figure 27A and 27B This is a variation of the heat-conducting component in Example 5.

[0038] Figure 28A and 28B This is a schematic diagram showing staples and record materials bound with staples.

[0039] Figure 29 This is a perspective view showing the state of a fixing device in an example of prior art, where recording material is being conveyed.

[0040] Figures 30A to 30C This is a diagram illustrating the state of a heater warped in the conveying direction in an example of the prior art.

[0041] Figure 31A and 31B This is a cross-sectional view of a fixing device in an example of prior art.

[0042] Figure 32 It is a cross-sectional view of the fixing device according to Example 6.

[0043] Figure 33A and 33B This is a perspective view of the membrane unit and heater based on Example 6.

[0044] Figure 34A and 34B These are the cross-sectional and plan views of the heater based on Example 6, respectively.

[0045] Figure 35A and 35B This is a variation of the heater in Example 6.

[0046] Figure 36 This is a cross-sectional view of the fixing device based on a variant example.

[0047] Figure 37A and 37B These are the cross-sectional and plan views of the heater based on the variant example.

[0048] Figure 38 It is a cross-sectional view of the fixing device according to Example 7.

[0049] Figures 39A to 39C This is a schematic diagram showing the heat-conducting component according to Example 7 and its variant.

[0050] Figure 40 It is a cross-sectional view of the fixing device according to Example 8.

[0051] Figures 41A to 41C This is a schematic diagram showing the heater according to Example 8 and its variant.

[0052] Figure 42 The overall configuration diagram of the device is formed based on the image in Example 9.

[0053] Figure 43 It is a cross-sectional view of the fixing device according to Example 9.

[0054] Figure 44 This is an exploded perspective view of the heater support unit and surrounding components based on Example 9.

[0055] Figure 45 This is a front view of the fixing device according to Example 9.

[0056] Figure 46 It is based on the cross-sectional view of the heater in Example 9.

[0057] Figure 47 It is a perspective view of the heater based on Example 9.

[0058] Figure 48This is a perspective view of the heater and power supply unit based on Example 9.

[0059] Figure 49 This is a perspective view of the heater support unit based on Example 9.

[0060] Figure 50 This is a perspective view of a heater support unit in an example of prior art.

[0061] Figure 51 This is a perspective view of the heater support unit and power supply device according to Example 10.

[0062] Figure 52A and 52B It is a perspective view of the heater based on Example 11.

[0063] Figure 53 This is a perspective view of the heater bracket and power supply unit based on Example 11.

[0064] Figure 54A and 54B This is a perspective view of the heater support unit based on Example 11.

[0065] Figure 55 This is a perspective view of the heater support unit and power supply device according to Example 12.

[0066] Figure 56 This is a perspective view of a heater based on a variant example.

[0067] Figure 57 This is a perspective view of a heater based on a variant example.

[0068] Figure 58 This is a perspective view of the heater support unit and power supply device according to a variant example.

[0069] Figure 59 This is a general configuration example of an image forming device based on Example 13.

[0070] Figure 60 It is a cross-sectional view of the fixing device according to Example 13.

[0071] Figure 61 This is an exploded perspective view of the membrane unit of the fixing device according to Example 13.

[0072] Figure 62 This is a front view of the fixing device according to Example 13.

[0073] Figure 63 This is a cross-sectional view of the heater based on the comparative example.

[0074] Figure 64 This is a perspective view of the heater based on the comparative example.

[0075] Figure 65 It is a cross-sectional view of the heater based on Example 13.

[0076] Figure 66 It is a cross-sectional view of the heater based on Example 14.

[0077] Figure 67 It is a cross-sectional view of the heater based on Example 15.

[0078] Figure 68 It is a cross-sectional view of the heater based on Example 16.

[0079] Figure 69 The overall cross-sectional view of the device is formed based on the image in Example 17.

[0080] Figure 70 It is a general cross-sectional view of the fixing device according to Example 17.

[0081] Figure 71 It is an exploded view of the heater and surrounding components based on Example 17.

[0082] Figure 72 It is an exploded view of the heater and heater bracket based on Example 17.

[0083] Figure 73 It is a completed drawing of the heater and heater bracket based on Example 17.

[0084] Figure 74A and 74B These are schematic diagrams showing the thermal expansion states of the heaters according to Example 17 and the comparative example, respectively.

[0085] Figure 75A and 75B This is a schematic diagram showing the off-center configuration of the heater protrusion according to Example 17.

[0086] Figure 76 It is an exploded view of the heater, heat spreader and heater support according to Example 18.

[0087] Figure 77 It is a completed drawing of the heater, heat spreader and heater support based on Example 18.

[0088] Figure 78 It is an exploded view of the heater, heat spreader, and heater support according to Example 19.

[0089] Figure 79 It is a completed drawing of the heater, heat spreader, and heater support based on Example 19.

[0090] Figure 80 It is an exploded view of the heater, heat spreader, and heater support according to Example 20.

[0091] Figure 81 This is a completed drawing of the heater, heat spreader, and heater support based on Example 20. Detailed Implementation

[0092] In the following description, embodiments (examples) of the invention will be given with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the constituent components described in the embodiments may be appropriately varied depending on the configuration of the device to which the invention is applied, various conditions, etc. Therefore, the dimensions, materials, shapes, and relative arrangements of the constituent components described in the embodiments are not intended to limit the scope of the invention to the following embodiments. Examples of image forming apparatus to which the invention can be applied include printers, copiers, etc., using electrophotographic systems or electrostatic recording systems, and the application of the invention to laser printers will be described herein.

[0093] Example 1

[0094] (1) Image forming apparatus 100

[0095] Figure 1 This is a general configuration diagram of the image forming apparatus 100 using electrophotographic recording technology in Example 1. First, the configuration and operation of the image forming apparatus 100 will be described.

[0096] The image forming operation of the image forming unit of the image forming apparatus 100 will be described. If the image forming apparatus 100 receives a print command from an external device, the scanner unit 3 emits a laser L to the photosensitive member 1 based on image information. The photosensitive member 1, charged with a predetermined polarity by the charging roller 2, is scanned by the laser L, and an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive member 1. Subsequently, the developing apparatus 4 supplies toner to the photosensitive member 1, and a toner image corresponding to the image information is formed on the photosensitive member 1. As the photosensitive member 1 rotates in the direction of arrow R, the toner image on the photosensitive member 1 moves to the transfer position formed by the photosensitive member 1 and the transfer roller 5, and is transferred to the recording material P supplied from the cartridge 6 by the pickup roller 7. The surface of the photosensitive member 1 that has passed the transfer position is cleaned using a cleaner 8.

[0097] The fixing device 9, which serves as the fixing section, performs fixing treatment on the recording material P on which a toner image has been transferred, using heat and pressure. Subsequently, the recording material P is discharged by the discharge roller 10 to the discharge tray 11.

[0098] (2) Fixing device 9

[0099] Next, the configuration and operation of the fixing device 9 will be described. In this example, the fixing device 9 of the tensionless film heating system is used as an example of a heating device. The fixing device 9 in this example is a device in which an annular strip (or cylindrical) film is used as a heat-resistant film, at least a portion of the periphery of the film is always kept tensionless (in a state where no tension is applied to it), and the film is driven to rotate by the rotational driving force of the pressure member.

[0100] Figure 2 This is a general cross-sectional view of the fixing device 9 in this example, showing the state in which recording material P, on which a toner image is formed, is conveyed to the fixing device 9. Furthermore, Figure 3 This is an exploded perspective view of the membrane unit 20 used in the fixing device 9. Figure 4 This is a schematic diagram of the fixing device 9, in which a portion of the membrane 23 is not shown, so as to show the internal structure of the membrane unit 20.

[0101] Reference Figure 2 The configuration of the fixing device 9 is described. In this example, the fixing device 9 includes a tubular membrane 23 serving as a first rotating body, a heater 22 heating the membrane 23 within its internal space, and a pressure roller 30 serving as a second rotating body, which forms a clamping portion N with the heater 22 across the membrane 23. The fixing device 9 also includes a heater support 21 supporting the heater 22 and guiding the rotation of the membrane 23, and a reinforcing member 24 reinforcing the heater support 21. The membrane 23 is driven to rotate in the direction of arrow a by receiving power from a motor (not shown) and rotating in the direction of arrow b via the pressure roller 30.

[0102] Membrane 23 is a tubular rotating body. The thickness of membrane 23 is preferably at least about 20 μm and not more than 100 μm to ensure satisfactory thermal conductivity. When membrane 23 is a single-layer membrane, a material such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), or PPS is preferably used as the base layer. When using a composite membrane, a material such as polyimide (PI), polyamide-imide (PAI), polyether ether ketone (PEEK), or polyether sulfone (PES) is preferably used as the substrate. Furthermore, it is suitable to use a material such as PTFE, PFA, or tetrafluoroethylene-perfluoroalkyl vinyl ether (FEP) as the release layer for configuring the composite membrane as a release layer coated on the surface of the base layer. Additionally, it is also suitable to use a membrane obtained by using a pure metal or alloy with high thermal conductivity such as SUS, Al, Ni, Cu, Zn, etc., in the base layer, performing the aforementioned coating treatment on the release layer, and coating with a fluoropolymer tube.

[0103] In this example, membrane 23 is a composite membrane, wherein the base layer is made of PI with a thickness of 60 μm and coated with a release layer made of PFA with a thickness of 12 μm to achieve a balance between release layer wear and thermal conductivity due to paper feeding. The length of membrane 23 in the longitudinal direction is set to 240 mm. The axial direction of the cylindrical shape of membrane 23 will be referred to below as the longitudinal direction.

[0104] The heater support 21 is a support member disposed within the internal space of the membrane 23 and supporting the heater 22. The membrane 23 is loosely fitted onto the heater support 21, and the heater support 21 also has a guiding function that guides the rotation of the membrane 23 while maintaining sliding contact with the inner circumferential surface of the membrane 23. Since the heater support 21 needs to have heat resistance and rigidity, it is preferable to use a liquid crystal polymer resin or the like with high heat resistance and excellent strength as the material for the heater support 21. For example, a molded part made of a heat-resistant resin such as polyphenylene sulfide (PPS) or a liquid crystal polymer can be used as the heater support 21.

[0105] The heater 22 includes at least an elongated plate-shaped substrate made primarily of metal, a resistance heating element that heats up in response to an electric current, an insulating layer that insulates the resistance heating element from the substrate, and a glass coating that protects the heating element. The detailed configuration of the heater 22 will be described later.

[0106] The thermistor 25, serving as a temperature detection unit, abuts against the second surface of the substrate on the side opposite to the first side where the resistive heating element is located, in a thickness direction orthogonal to the longitudinal and transverse directions of the heater 22. The energization of the heating resistor is controlled based on the temperature detected by the thermistor 25, thereby managing the temperatures of the heater 22 and the film 23. In other words, in this example, the temperature change of the film 23 via the heater 22 is detected by the thermistor 25.

[0107] The pressure roller 30 includes a core metal made of a material such as iron or aluminum, an elastic layer made of a material such as silicone rubber, and a release layer made of a material such as PFA. Drive gear 33 (see...) Figure 4 The pressure roller 30 is attached to one end of the core metal in the longitudinal direction, and the drive gear 33 receives the rotational driving force from the drive device (not shown) and causes the pressure roller 30 to rotate.

[0108] The reinforcing member 24 is made of a metal such as iron, and maintains its strength to prevent significant deformation even under pressure applied to the heater support 21 towards the pressure roller 30 side (the second rotating body side). The heater 22 is pressurized towards the pressure roller 30 side by a pressurizing device described below via the heater support 21 and the reinforcing member 24. The area where the pressure roller 30 and the membrane 23 come into close contact under pressure is the clamping portion N (as a pressing area).

[0109] Next, we will refer to Figure 3 The perspective view depicts details of the membrane unit 20, which is composed of components such as membrane 23. First, the heater support 21 has a generally groove-shaped cross-section orthogonal to the longitudinal direction, and a reinforcing member 24 is fitted into the interior of the groove. A heater receiving groove is provided in the heater support 21 on the side facing the pressure roller 30, and the heater 22 is fitted into the heater receiving groove and positioned as desired. The membrane 23 is fitted with a certain allowance onto the outer periphery of the heater support 21, on which the aforementioned components are assembled.

[0110] The reinforcing member 24 extends from both ends of the membrane 23 in the longitudinal direction, and the membrane unit 20 is assembled by flanges 26 fitted to each end of the reinforcing member 24.

[0111] The power supply terminal of heater 22 also extends from one end of membrane 23 in the longitudinal direction, and power supply connector 27 is fitted to the power supply terminal. Power supply connector 27 contacts the electrode portion of heater 22 with abutting pressure and forms a power supply path. In addition, heater clip 28 is formed of a metal plate bent into a C shape, and its elasticity is used to hold the end of heater 22 at heater support 21.

[0112] Next, we will refer to Figure 4 The configuration of the fixing unit 9 is described in further detail. Figure 4 In the diagram, a portion of the membrane 23 is not shown, so that the heater support 21 and heater 22 disposed within the interior space of the membrane 23 can be seen. Flanges 26 located at both ends of the membrane 23 restrict the longitudinal movement of the rotating membrane 23.

[0113] The film unit 20 is positioned facing the pressure roller 30 and supported by the top plate side housing 41. The film unit 20, supported by the top plate side housing 41, is able to move freely in the pressure direction, but its movement in the longitudinal direction is restricted. A pressure spring 45 is attached to the top plate side housing 41 of the fixing device 9 in a compressed state. The pressure of the pressure spring 45 is received by the reinforcing member 24 at both ends in the longitudinal direction via the flange 26. The pressure of the pressure spring 45 pushes the reinforcing member 24 towards the pressure roller 30, pressing the entire film unit 20 towards the pressure roller 30, thereby forming the clamping portion N.

[0114] The bearing member 31 is configured to axially support the core metal of the pressure roller 30 and receive pressure from the membrane unit 20 via the pressure roller 30. To rotatably support the core metal of the pressure roller 30, which is heated to a relatively high temperature, the bearing member 31 is made of a material with heat resistance and excellent sliding properties. The bearing member 31 is attached to the bottom housing 43 of the fixing unit 9.

[0115] (3) Heater 22

[0116] Next, we will use Figure 5 as well as Figure 6A and 6B Describe the materials, manufacturing methods, etc. used to configure heater 22 in this example. Figure 5 This is a perspective view showing a cross-section of the fixing device 9 equipped with a heater 22 in this example. Figure 6A This is a perspective view showing the substrate 221 of the heater 22. Figure 6B This is a cross-sectional view showing the fixing device 9 in the vicinity of the heater 22.

[0117] The heater 22 includes an elongated plate-shaped substrate 221 mainly made of metal, a heating element 223 that heats up in response to electricity, an insulating layer 222 that insulates the heating element 223 from the substrate 221, and a protective layer 224 that protects the heating element 223. For convenience, the surface of the substrate 221 that includes the insulating layer 222 and the heating element 223 disposed thereon and faces the pressure roller 30 through the membrane 23 is defined as the first surface 221g (front surface, front side), and the surface opposite to the first surface is defined as the second surface 221h (rear surface, back side).

[0118] (3-1)Substrate 221

[0119] As the material for the substrate 221, stainless steel, nickel, copper, aluminum, or alloys containing such materials as the main material are suitable. Among these, stainless steel is most preferably used considering strength, heat resistance, and corrosion resistance. There are no particular limitations on the type of stainless steel, and it can be appropriately selected considering factors such as the necessary mechanical strength, the coefficient of linear expansion corresponding to the formation of the insulation layer 222 and the heating element 223, and the ease of obtaining sheet metal from the market. In one example, martensitic and ferritic stainless steels from the chromium-based stainless steel (400 series) are suitable because they have relatively low coefficients of linear expansion among stainless steels, and are therefore easy to use to form the insulation layer and the heating element.

[0120] The thickness of the substrate 221 can be determined by considering strength, heat capacity, and heat dissipation performance. While a thinner substrate 221 results in a smaller heat capacity, thus facilitating rapid start-up, excessive thickness may lead to problems such as deformation during the thermoforming of the heating element. Specifically, due to the elongated plate shape of the heater, deformation into an arc shape (where the central portion in the longitudinal direction included on the side forming the heating element becomes a convex apex) may occur. Conversely, while a thicker substrate 221 is advantageous in terms of deformation during the thermoforming of the heating element, excessive thickness is detrimental to rapid start-up due to its larger heat capacity. Considering the balance between mass production, cost, and performance, the preferred substrate thickness is approximately 0.1 mm to 2.0 mm.

[0121] For the substrate 221 in this example, the material used is a ferritic stainless steel plate (SUS430:18Cr stainless steel) with a width of 10 mm, a length of 300 mm, and a thickness of 0.1 mm. The characteristic shape and forming method of the substrate 221 according to the present invention will be described in detail later.

[0122] (3-2) Insulation layer 222

[0123] Although there are no particular restrictions on the material of the insulating layer 222, it is necessary to select a material with heat resistance considering the temperature in actual use. As a material, glass or polyimide (PI) is preferred considering heat resistance, and in the case of glass, a specific powder material can be appropriately selected, as long as it does not impair the characteristics of the invention. Thermally conductive fillers with insulating properties can be added as needed.

[0124] Typically, it is preferred that the heater used in the image forming apparatus has a dielectric strength of approximately 1.5 kV. Therefore, the layer thickness of the insulating layer 222 can be ensured according to the material to achieve a dielectric strength performance of 1.5 kV between the heating element 223 and the substrate 221.

[0125] While there are no particular limitations on the molding method of the insulating layer 222, in one example, the insulating layer 222 can be smoothly molded using methods such as screen printing. When an insulating layer of glass or polyimide (PI) is formed on a substrate, it is necessary to appropriately adjust the linear expansion coefficients of the substrate and the insulating layer materials so that cracking or peeling does not occur in the insulating layer due to the difference between the linear expansion coefficients of the materials. In this example, an insulating layer glass paste is applied to a substrate 221 made of stainless steel by screen printing, the resulting article is dried at 180°C, and then sintered at 850°C to form the insulating layer 222. In this example, an insulating layer 222 with a layer thickness of 50 μm is formed on the first surface 221g of the substrate 221.

[0126] (3-3) Heating element 223

[0127] The heating element 223 is connected to a power supply electrode (not shown). Power is supplied to the power supply electrode via a power supply connector 27, thereby energizing the heating element 223, which then heats up in response to the energization. The heating element 223 is obtained by printing a heating resistance paste, which is a mixture of conductive component (A), glass component (B), and organic binder component (C), onto an insulating layer 222 and then sintering the heating resistance paste. When the heating resistance paste is sintered, the organic binder component (C) burns and disappears, while components (A) and (B) remain, thus forming a heating element 223 containing conductive and glass components. Here, silver-palladium (Ag·Pd), ruthenium oxide (RuO2), etc., are used alone or in combination as conductive component (A), and a sheet resistance value of 0.1 [Ω / □] to 100 [kΩ / □] is preferably obtained. Furthermore, if other materials are included in addition to the above-mentioned components (A) to (C), there is no problem as long as the content is very small and does not impair the performance of the present invention. Here, for the heating resistor paste mentioned above, it is necessary to select a material that softens and melts at a temperature lower than the melting point of the substrate 221, and considering the temperature in actual use, it is necessary to select a material with heat resistance.

[0128] In this example, the heating element 223 is formed from a heating element paste, which is obtained by using silver-palladium (Ag·Pd) as a conductive component and combining it with glass and organic binder components. After the heating element paste is applied to a substrate 221 on which an insulating layer 222 is provided by screen printing, the resulting article is dried at 180°C and then sintered at 850°C, and the heating element 223 is formed on the first surface 221g side of the substrate 221. The sintered heating element 223 has a thickness of 15 μm, a length of 220 mm, and a width of 1.1 mm.

[0129] (3-4) Power supply electrode and conductive pattern

[0130] Power supply electrodes and conductive patterns are provided for supplying power to the heating element 223. The power supply electrodes and conductive patterns, not shown, contain silver (Ag), platinum (Pt), gold (Au), silver-platinum (Ag·Pt) alloys, silver-palladium (Ag·Pd) alloys, etc., as main components. Similar to the heating element paste, the power supply electrodes and conductive patterns are formed by printing a paste obtained by mixing conductive components (A), glass components (B), and organic binder components (C) onto a substrate 221 on which an insulating layer 222 is provided, and then sintering the paste.

[0131] (3-5) Protective layer 224

[0132] The protective layer 224 is disposed on the insulating layer 222 to cover the heating element 223, thereby protecting the heating element 223 and ensuring its sliding ability with the film 23. As a material, glass or polyimide (PI) is preferred in consideration of heat resistance, and thermally conductive fillers with insulating properties may be added as needed.

[0133] A protective layer 224 is formed on the insulating layer by applying a protective glass paste to the heating element 223 via screen printing, drying the resulting article at 180°C, and sintering at 850°C. In this example, the thickness of the protective layer 224 is 50 μm.

[0134] (4) Shape of substrate 221

[0135] like Figure 6A As shown, in this example, the substrate 221 is a metal component that is longer in the longitudinal direction, and the insulating layer 222 and the heating element 223 are disposed at the central side plane portion 221a. In this example, the substrate 221 is longer in the same direction as the longitudinal direction of the film 23. Furthermore, the substrate 221 has a shape that is curved over the entire area in the longitudinal direction. The shape of the substrate 221 of the heater 22 will be described in detail below.

[0136] The substrate 221 is bent such that at the central side plane 221a of the substrate 221, the end side in the transverse direction orthogonal to the longitudinal direction is close to the pressure roller 30 side in the thickness direction. Furthermore, end side planes 221b, substantially parallel to the central side plane 221a, are provided at both ends of the substrate 221 in the transverse direction, such that they are located closer to the pressure roller 30 (closer to the heating element 223) than the central side plane 221a. In this example, the substrate 221 is formed by stretch-pressing, and the stretching depth d1 of the substrate 221, corresponding to the magnitude of the height difference (step difference) between the central side plane 221a and the end side planes 221b, is 50 μm.

[0137] The shape of substrate 221 will be described in more detail. Substrate 221 includes four bends that bend over the entire longitudinal direction. Substrate 221 includes a first bend 221c and a second bend 221d. The first bend 221c bends towards the pressure roller 30 at one end in the transverse direction upstream of the transport direction of the recording material P. The second bend 221d bends towards the upstream side of the transport direction at a side closer to the first bend than the first bend. Substrate 221 also includes a third bend 221e and a fourth bend 221f. The third bend 221e bends towards the pressure roller 30 at the other end (opposite to the first end) in the transport direction of the recording material P. The fourth bend 221f bends towards the downstream side of the transport direction at a side closer to the third bend than the third bend. In this example, the end-side planar portion 221b includes a second curved portion 221d and a fourth curved portion 221f, and the second curved portion 221d and the fourth curved portion 221f have planes parallel to the central-side planar portion 221a. In other words, since the substrate is formed by bending the flat plate material multiple times, the central-side planar portion 221a and the end-side planar portion 221b are arranged substantially parallel to each other with a certain amount of height difference.

[0138] In the transverse direction of the substrate 221, the region on the central side, including the central side planar portion 221a of the first surface 221g where the insulating layer 222 is provided, is defined as a first region R1; the region on one end side relative to the first region R1 is defined as a second region R2; and the region on the other end side relative to the first region R1 is defined as a third region R3. In this example, the second region R2 can be said to include a first bend 221c and a second bend 222d, and the third region R3 includes a third bend 221e and a fourth bend 221f. In other words, the first region R1 of the substrate 221 is planar, and the second region R2 and the third region R3 are bent from the first region R1. Furthermore, both the second region R2 and the third region R3 include a portion of the end planar portion 221b. By providing such multiple bends, the bending strength of the substrate 221 in the thickness direction is improved compared to a simple flat plate shape.

[0139] It should be noted that the aforementioned bending does not always mean forming the substrate by performing a bending process (e.g., stretch pressing) on ​​the sheet material. For example, even when a similar shape is provided by means such as casting or cutting to provide the substrate configuration, the effect of improving the reduction of warpage and the responsiveness to temperature changes in the film can be obtained, as will be described below. In other words, although stretch pressing is used as a processing method to form the substrate in this example, thereby expecting ease of processing and the effect of increasing the strength of the substrate due to plastic processing, the substrate forming method is not limited to plastic processing.

[0140] (5) Effects and advantages

[0141] To verify the effects and advantages of the present invention, evaluation tests, including comparative examples, were conducted. Under the conditions of this example and the comparative examples, the warpage of the heater, the adjustable temperature at which fixing can be achieved, and the loading capacity were evaluated.

[0142] In this example and the two comparative examples, three types of heaters were used for evaluation testing. Figure 7A This is a schematic diagram showing the configuration of heater 52 in Comparative Example 1. Figure 7B This is a schematic diagram showing the configuration of the heater 62 in Comparative Example 2. Comparative Example 1 includes a flat substrate 521 that has not yet undergone molding, an insulating layer 522, a heating element 523, and a protective layer 524 disposed on the front surface side of the substrate 521, and an insulating layer 525 made of the same material as the insulating layer 522 is also disposed on the rear surface side. Similar to Comparative Example 1, Comparative Example 2 includes a flat substrate 621 that has not yet undergone molding. In Comparative Example 2, similar to this example, the insulating layer 622 is disposed only on the front surface side of the substrate, and the heating element 623 and the protective layer 624 are disposed thereon. Other configurations of the substrates in Comparative Examples 1 and 2 (e.g., thickness and length in the longitudinal direction) are similar to those in Example 1.

[0143] To measure the warpage of the heater, the heater is placed on a horizontal platform with the front surface of the substrate on which the heating element is located becoming the upper surface. The height of the convex apex at the center of the longitudinal direction on the rear surface side of the heater relative to the platform is defined as the warpage. Since satisfactory operability is achieved when assembling the heater and heater support along the heater support as long as the warpage does not exceed 3 mm, a warpage within the range of 0 to 3 mm is considered to pass the test (OK).

[0144] As a test to evaluate temperature regulation, the heater was left in a stopped state for approximately one hour without standby temperature adjustment, and then 250 sheets of paper were fed in a single-sided feed mode starting from a cold state. Xerox Vitality (75g / m²) was used. 2 The toner (LTR) was used as the recording material in this test. A full-black pattern printed across the entire surface was used as the print rate pattern to calculate the conditioning temperature. Considering energy saving and power conservation, a lower conditioning temperature is better for the fixing unit.

[0145] As a test to evaluate loading capacity, the heater was left in a stopped state for approximately one hour without standby temperature adjustment, and then 250 sheets of paper were fed in a double-sided feed mode starting from a cold state. Xerox Vitality (75g / m²) was used. 2The recording material (LTR) was used in this test. Loading capacity was evaluated based on the number of sheets of recording material that could be loaded after the paper was fed into the discharge tray 11. The number of sheets that could be loaded was affected by the degree of curvature of the recording material, and in heaters or fixing devices that provide excessive heat to the recording material, the curvature of the recording material increased, and the number of sheets that could be loaded decreased.

[0146] Table 1 shows the main configurations in this example and comparative example, as well as the evaluation results of warpage and assemblability, fixing ability, and loading capacity during heater molding. Assemblability is shown as OK when the warpage does not exceed 3 mm, and other cases are described as NG.

[0147] [Table 1]

[0148]

[0149] In Example 1, the warpage of heater 22 is 2.8 mm, and there are no assembly issues. Furthermore, the set temperature is 190°C, and the number of sheets of recording material that can be loaded is 200.

[0150] In Comparative Example 1, the warpage of heater 52 was 0.1 mm. As a result, it was found that warpage could also be suppressed by providing an insulating layer 525 on the surface opposite to the surface on which the heating element 223 is formed.

[0151] However, the settling temperature in Comparative Example 1 was 200°C, which is higher than the temperature in Example 1; and the number of sheets of recording material that could be loaded was 50, which is also less than the result in Example 1. Compared with Example 1, due to the influence of the thermal resistance of the insulating layer 525 in Comparative Example 1, the sensitivity of the thermistor 25 to detect temperature changes in the film 23 is reduced, thus increasing the settling temperature, further increasing the curling of the recording material, and reducing the number of sheets that can be loaded. In other words, in Comparative Example 1, a balance cannot be achieved between suppressing heater warping and detecting film temperature changes with satisfactory responsiveness.

[0152] In Comparative Example 2, the warpage of heater 62 was 11 mm, and assembly was found to be difficult. Since the bending strength of the substrate in the thickness direction was enhanced by substrate bending in Example 1, the warpage in Example 1 was significantly reduced compared to Comparative Example 2, which included the same layer configuration.

[0153] Furthermore, the conditioning temperature in Comparative Example 2 was 195°C, and the number of sheets of recording material that could be loaded was 100. Although the insulating layer was only provided on one surface of the substrate in both Comparative Example 2 and Example 1, a stretching depth d1 of 50 μm was formed in the substrate of Example 1, and compared with the substrate of Comparative Example 2, the end of the substrate in the lateral direction was closer to the inner peripheral surface of the film. In other words, in Example 1, the heat of the film 23 was transferred not only to the substrate 221 via the protective layer 224, but also easily transferred directly from the film 23 to the substrate 221. Therefore, since Example 1 can sense the temperature change of the film 23 more sensitively than Comparative Example 2, the conditioning temperature of Example 1 is lower than that of Comparative Example 2, and the number of sheets that can be loaded is increased.

[0154] As described above, according to the present invention, while the heater is shaped to the point where warpage is suppressed to the point where it does not cause problems during assembly, the decrease in regulating temperature and the curling of the recording material can be suppressed by detecting the temperature change of the film with satisfactory responsiveness, and the number of sheets that can be loaded can be increased. In other words, by bending the substrate so that the end side of the substrate in the lateral direction is close to the pressure roller side (heating element side) in the thickness direction, the warpage of the heater can be suppressed without providing an insulating layer on both surfaces of the substrate. Furthermore, since no insulating layer is provided on one side of the substrate, the temperature change of the film can be detected with satisfactory responsiveness.

[0155] The aforementioned effects and advantages of the present invention are particularly useful in high-speed machines. For example, when the toner printing rate for graphics or patterns is high, the film temperature drops significantly as the recording material passes through the clamping section. If the response to film temperature changes is poor at this time, the recording material will detach from the clamping section N before the temperature drop is fed back to the heater's energization control. Therefore, in cases of poor response to film temperature changes, it is necessary to set a high settling temperature that satisfies the fixing capability under conditions of large film temperature drops. On the other hand, in duplex printing, when the paper passes through the clamping section and the clamping section has been heated during the first side printing before the second side printing is performed, the film temperature drop is relatively small compared to the first side. Therefore, if the settling temperature is high, there is concern that the loading capacity may decrease due to an excessive increase in heat applied to the recording material through the clamping section (excessive heating of the recording medium) and an increase in the amount of recording material curling. According to the present invention, film temperature changes can be detected with satisfactory responsiveness, thereby achieving a reduction in settling temperature and suppression of recording material curling.

[0156] Next, we will refer to Figure 8 as well as Figure 9A and 9B The following describes variant example 1 as a variant example of example 1. Figure 8 This is a perspective view showing a cross-section of a fixing device 39 equipped with a heater 32 according to variant example 1. Figure 9A This is a perspective view showing the substrate 321 of the heater 32. Figure 9B This is a cross-sectional view showing the fixing device 39 near the heater 32. The same reference numerals will be applied to configurations similar to Example 1, and their description will be omitted in Variation 1. As a configuration where an insulating layer 325 is provided on the second surface 321h side of the substrate 321 without compromising the temperature responsiveness of the thermistor 25, Variation 1 is characterized by suppressing the warpage of the heater 32 compared to the configuration in Example 1. In other words, in Variation 1, the insulating layer 322 is provided as a first insulating layer on the first surface 321g of the substrate 321, and the insulating layer 325 is provided as a second insulating layer on the second surface 321h.

[0157] In Variation 1, the thickness of the insulating layer 325 on the second surface 321h side is 50 μm, and the stretching depth d3 of the substrate 321, corresponding to the height difference between the central side planar portion 321a and the end side planar portion 321b, is 50 μm. Similar to Example 1, the total thickness of the insulating layer 322 and the protective layer 324 formed on the first surface 321g side is set to 100 μm.

[0158] Table 2 shows the main configurations in this example, comparative example, and variant example 1, as well as the evaluation results of warpage, assemblability, fixing ability, and loading capacity during molding heater operation. Regarding assemblability, in the table below, warpage of no more than 3 mm is described as OK, and other cases are described as NG.

[0159] [Table 2]

[0160]

[0161] As shown in Table 2, the set temperature is 195°C because, in this variant, the insulating layer 325 is provided on the second surface 321h side, and since the fixing capability is reduced by an amount corresponding to 5°C from the configuration in Example 1, the number of sheets of recording material loaded is reduced from 200 to 100. On the other hand, the warpage of the heater 32 in Variant 1 is 1.4 mm, and the warpage during heater forming is reduced compared to Example 1. This is because, in Example 1, the insulating layer is provided on only one surface of the substrate, while in Variant 1, the insulating layer 325 is provided on the second surface 321h side, and the insulating layer is provided on both the first surface 321g and the second surface 321h of the substrate 321. In other words, particularly from the perspective of achieving both fixing capability and heater warpage with the configuration required for assembly accuracy, the configuration of providing insulating layers on both surfaces of the substrate as described in Variant 1 is advantageous.

[0162] Furthermore, although in this example the substrate is bent on both the upstream and downstream sides in the transport direction to approach the inner circumferential surface of the film, even in another variation, the effect of suppressing the warping of the flat substrate in the prior art can be achieved by using a configuration in which either side of the substrate is bent. Moreover, although in this example the end-side planar portions are provided at both ends of the substrate in the transverse direction, it is also conceivable that in such a variation the substrate includes only two bent portions so that the two ends of the substrate in the transverse direction extend substantially parallel to the thickness direction without having end-side planar portions, in order to save equipment space.

[0163] Next, we will refer to Figure 10 as well as Figure 11A and 11B Describe variant example 2, which is a variant of example 1. Figure 10 This is a perspective view showing a cross-section of a fixing device 49 equipped with a heater 42 according to variant example 2. Figure 11A This is a perspective view showing the substrate 421 of the heater 42. Figure 11B This is a cross-sectional view showing the fixing device 49 near the heater 42. The same reference numerals will be applied to the configuration similar to Example 1 in Variant 2, and its description will be omitted. The difference between the fixing device 49 in Variant 2 and Example 1 is that the folding direction in the short side direction orthogonal to the longitudinal direction of the substrate 421 of the heater is opposite to that in Example 1, and the substrate 421 is configured to be folded on the thermistor 25 side. In other words, in Variant 2, the substrate 421 is folded such that the end of the substrate 421 in the transverse direction separates from the pressure roller 30.

[0164] like Figure 11A As shown, the end of substrate 421 in the transverse direction is bent in the thickness direction of substrate 421 in a direction opposite to the surface on which the heating element 423 is provided. In other words, the end of substrate 421 in the transverse direction is bent away from the insulating layer 422 and the protective layer 424. Furthermore, substrate 421 is configured such that it does not include the end-side planar portion and includes only two bent portions, so that the two ends of substrate in the transverse direction extend substantially parallel to the thickness direction, and space saving of the fixing device 49 is achieved. The bent portions extend over the entire range of substrate 421 in the longitudinal direction, and in this example, substrate 421 is formed by stretch pressing. For variant example 2, the assemblability, fixing capability, and loading capacity of the heater are evaluated in each of the cases where the folding depth d4 of substrate 421 is set to 50 μm and the cases where the folding depth d4 of substrate 421 is set to 150 μm.

[0165] In addition, such as Figure 11BAs shown, the bent portion of the substrate 421 on the thermistor 25 side is provided in a groove 211 provided in the heater support 21. The groove 211 of the heater support 21 is formed over the entire longitudinal direction, and the groove depth d4h is set taking into account tolerances and the thermal expansion of the folded portion of the substrate 421. Specifically, when the folding depth d4 of the substrate 421 is 50 μm, the groove depth d4h is set to 150 μm; when the folding depth d4 is 150 μm, the groove depth d4h is set to 250 μm. Taking into account manufacturing tolerances, the groove depth d4h is set to ensure that the groove depth d4h is greater than the folding depth d4 and that the heater 42 abuts against the holding surface of the heater support 21. Furthermore, the groove depth d4h is set within a range that does not cause effects such as deflection when the heater support 21 is pressed by the pressure roller 30.

[0166] Table 3 shows the main configurations in this example, comparative example, and variant example 2, as well as the evaluation results of warpage, assemblability, fixing ability, and loading capacity during molding heater operation. Regarding assemblability, in the table below, warpage of no more than 3 mm is described as OK, and other cases are described as NG.

[0167] [Table 3]

[0168]

[0169] As shown in Table 3, in Variation Example 2, when the folding depth d4 of substrate 421 is 50 μm, the warpage of the heater is 2.8 mm, while when the folding depth d4 of substrate 421 is 150 μm, the warpage of the heater is 0.8 mm. In other words, the result is that the warpage of the heater decreases as the folding depth d4 of substrate 421 increases. Furthermore, regarding the evaluation results of fixing capability and loading capability, regardless of the folding depth d4 of substrate 421, the settling temperature is 195°C, and the number of sheets of recording material loaded is 100, which is an improvement of 5°C compared to Comparative Example 1. On the other hand, the reason why the settling temperature in Variation Example 2 is increased by 5°C compared to the configuration in Example 1 is that, because the folding direction of substrate 321 towards the thermistor 25 is changed, the effect that the temperature change of film 23 may be directly transmitted to substrate 421 is reduced.

[0170] As described above, the warpage of the heater 42 during molding can be reduced by increasing the folding depth d4 of the substrate 421, and improved assemblability can be expected. Furthermore, similar to Example 1, by not providing an insulating glass layer on the opposite side of the surface where the heating element 423 is located, temperature changes in the film can be detected with satisfactory responsiveness, thereby reducing the temperature regulation and suppressing curling of the recording material.

[0171] Example 2

[0172] Next, Example 2 according to the present invention will be described. The difference between the fixing device 79 in Example 2 and the fixing device in Example 1 is that the two ends of the substrate of the heater in the transverse direction abut against the inner peripheral surface of the film. Since a similar configuration to that in Example 1 is used in other configurations in the image forming apparatus and fixing device in Example 2, similar reference numerals will be applied and their descriptions will be omitted. The characteristic configuration in Example 2 will be described in detail below.

[0173] Figure 12 This is a perspective view showing a cross-section of the fixing device 79, which is equipped with a heater 72 in this example. Figure 13A This is a perspective view showing the substrate 721 of the heater 72. Figure 13B This is a cross-sectional view showing the fixing device 79 in the vicinity of the heater 72.

[0174] In this example, heater 72 also includes an elongated plate-shaped substrate 721 (which contains metal as the main material), a heating element 723 that heats up in response to energization, an insulating layer 722 that insulates the heating element 723 from the substrate 721, and a protective layer 724 that protects the heating element 723.

[0175] like Figure 13A As shown, the substrate 721 in this example is a relatively long member in the longitudinal direction, made of metal, and includes an insulating layer 722 and a heating element 723 disposed at the central side plane portion 721a. The substrate 721 is bent at its end sides in the transverse direction orthogonal to the longitudinal direction, so as to be close to the pressure roller 30 side in the thickness direction of the substrate 721. In addition, the end side plane portions 721b, which are substantially parallel to the central side plane portion 721a, are disposed at both ends of the substrate 721 in the transverse direction and are located on the side of the pressure roller 30 (the side of the heating element 723). Furthermore, the substrate 721 also includes a plurality of bent portions 721c to 721f formed over the entire range in the longitudinal direction. In this example, the substrate 721 is formed by stretch pressing, and the stretching depth d2 of the substrate 721 (i.e., the magnitude of the height difference between the central side plane portion 721a and the end side plane portion 721b) is 150 μm.

[0176] In the lateral direction of the substrate 721, the central side region of the central side planar portion 721a, which includes the first surface 721g on which the insulating layer 722 is provided, is defined as the first region R1; the region relative to one end of the first region R1 is defined as the second region R2; and the region relative to the other end of the first region R1 is defined as the third region R3. In this example, the second region R2 can also be described as including a first bend 721c and a second bend 722d, while the third region R3 includes a third bend 721e and a fourth bend 721f. In other words, the first region R1 of the substrate 721 is planar, and the second region R2 and the third region R3 are bent from the first region R1. Furthermore, both the second region R2 and the third region R3 include a portion of the end planar portion 721b.

[0177] As described above, the stretching depth in this example is set to be greater than that in Example 1, and the stretching depth d2 is greater than the total thickness of the insulating layer 722 and the protective layer 724. Therefore, compared to the protective layer 724, the end-side planar portion 721b of the substrate 721 of the heater 72 is configured to protrude closer to the pressure roller 30 in the thickness direction. In other words, the difference between the fixing device 79 in this example and the fixing device in Example 1 is that the end-side planar portion 721b provided at the end of the substrate 721 in the lateral direction abuts against the inner surface of the film 23. In the fixing device 79, the film 23 slides against the protective layer 724 and the substrate 721 of the heater 72, as well as the heater support 21.

[0178] The tests performed in Example 1 and the Comparative Example to evaluate the heater warpage, fixing capability, and loading capacity were also performed in this example. Furthermore, to compare Example 1 and Example 2, the lifespan of the fixing unit was evaluated. For the lifespan of the fixing unit, Xerox Vitality (75 g / m³) was tested in an environment with an atmospheric temperature of 33°C and a humidity of 80%. 2 The LTR performs paper feed durability tests and evaluates the paper based on the number of sheets fed in the case of intermittent paper feed until a paper jam occurs due to a feed failure.

[0179] Table 4 shows the main configurations in this example and Example 1, and illustrates the evaluation results for warpage and assemblability during heater molding, fixing and loading capacity, and the lifespan of the fixing unit. Regarding assemblability, in the table below, warpage not exceeding 3 mm is described as OK, and other cases are described as NG.

[0180] [Table 4]

[0181]

[0182] In Example 2, the warpage of heater 72 is 0.8 mm, and there are no assembly issues. Furthermore, the temperature is set to 180°C, the capacity for recording material is 250 sheets, and the lifespan of the fixing unit is 100,000 prints.

[0183] In Example 2, the warpage of the heater is significantly reduced compared to Example 1. This is because, in Example 2, the substrate has a greater stretch depth and superior bending strength. In other words, the greater the stretch depth of the substrate, the better, in order to suppress heater warpage.

[0184] Furthermore, compared to Example 1, in Example 2, the set temperature is lowered and the number of recording sheets that can be loaded is increased. This is because, in Example 2, the substrate 721 abuts against the inner peripheral surface of the film 23 at the end-side planar portion 721b, so the temperature change of the film 23 can be sensed more sensitively compared to Example 1. In other words, in order to reduce the set temperature and increase the number of recording sheets that can be loaded, the closer the heater substrate is to the inner peripheral surface of the film, the better.

[0185] On the other hand, the lifespan of the fixing device in Example 2 is inferior to that in Example 1. This is because, in the fixing device 79 of Example 2, the film 23 rotates while sliding against the substrate 721. If paper feeding is repeatedly performed while the film is sliding against the substrate, the inner circumferential surface of the film is gradually worn away, and the rotational resistance of the film increases due to the wear of the inner circumferential surface. In other words, since the rotational resistance of the film 23 increases and the ability to transport recording material decreases in Example 2, paper jams will occur due to transport failures when the number of sheets of recording material is small, compared to Example 1, and the lifespan of the fixing device is shortened. In other words, to improve the lifespan of the fixing device, it is preferable to adopt a configuration in which the substrate of the heater does not contact the film.

[0186] Compared to a configuration where the substrate does not contact the inner peripheral surface of the film, if the configuration described above, as in Example 2, involves the heater substrate contacting the inner peripheral surface of the film, it is expected to result in improved heater warping suppression, reduced temperature regulation, and an increased number of recording sheets that can be loaded. However, this configuration shortens the lifespan of the fixing unit. This configuration of the fixing unit is suitable, for example, for personal printers where product lifespan is less critical.

[0187] Reference Figure 14A and 14B The following describes variant example 3, which is a variant of example 2. Figure 14A This is a perspective view showing the substrate 821 of the heater 82 according to variant example 3. Figure 14B This is a cross-sectional view showing the fixing device 89 in the vicinity of the heater 82. The same reference numerals will be applied to the configuration in Variation 3 that is similar to that in Example 2, and its description will be omitted.

[0188] In Variation 3, the stretching depth d5 ​​of the substrate 821 (i.e., the height difference between the central side plane portion 821a and the end side plane portion 821b) is set to 100 μm. Furthermore, the sliding properties of the heater 82 and the film 23 are improved by forming the protective layer 824 to cover not only the central side plane portion 821a of the substrate 821 but also the end side plane portion 821b. At the end side plane portion 821b of the substrate 821, the protective layer 824 is directly disposed on the substrate 821, and there is no insulating layer 822 between the substrate 821 and the protective layer 824. In other words, the central portion 824a of the protective layer 824 contacts the insulating layer 822, and the end portion 824b contacts the substrate 821. In the configuration of variant example 3, the thickness of the end 824b of the protective layer 824 covering the end side plane portion 821b of the substrate 821 is set to 50 μm, and the height from the central side plane portion 821a to the end 824b is set to the same value as the substrate stretching depth in example 2.

[0189] Table 5 shows the main configurations in Examples 1 and 2 and Variation 3, and presents the evaluation results for warpage and assemblability during molding, fixing and loading capacity, and the lifespan of the fixing unit. Regarding assemblability, in the table below, warpage not exceeding 3 mm is described as OK, and other cases are described as NG.

[0190] [Table 5]

[0191]

[0192] The warpage of the heater in Variation Example 3 is 1.4 mm. Although the warpage is slightly increased compared to the configuration in Example 2 because the stretching depth d5 ​​in Variation Example 3 is 100 μm and is 50 μm smaller than that in Example 2, the results show that there are no problems with assembly. In addition, the protective layer 824 is also provided at the end-side plane portion 821b of the substrate 821, and due to the effect of improving the sliding between the heater 82 and the film 23, the life of the fixing device is increased from 100,000 prints in Example 2 to 200,000 prints. On the other hand, since the protective layer 824 on the end-side plane portion 821b suppresses heat transfer, the set temperature is 185°C, which is 5°C higher than 180°C in Example 2, and the number of recording material sheets that can be loaded is slightly reduced from 250 sheets to 225 sheets.

[0193] As described above, compared to Example 2, by adopting a heater configuration as in Variant Example 3, it is possible to suppress heater warping and expect to improve the lifespan of the fixing unit, but the number of recording sheets that can be loaded will be slightly reduced.

[0194] Next, we will refer to Figure 15A and 15B The following describes variant example 4, which is a variant of example 2. Figure 15A This is a perspective view showing the substrate 921 of the heater 92 according to variant example 4. Figure 15B This is a cross-sectional view showing the fixing device 99 in the vicinity of the heater 92. The same reference numerals will be applied to the configuration in Variation 4 that is similar to that of Example 2, and its description will be omitted. Variation 4 is configured by changing the thickness of the insulating layer 922 and the protective layer 924 of Variation 3.

[0195] Variation 4 is configured such that the thicknesses of the insulating layer 922 and the protective layer 924 formed on the central side plane portion 921a and the end side plane portion 921b of the substrate 921 are adjusted so that the surface shape of the protective layer 924 abutting the inner surface of the film 23 is a plane. In other words, in Variation 4, the thickness of the protective layer 924 is substantially the same at the central portion 924a and the end portion 924b. By employing a heater shape with the protective layer 924 substantially in a plane, the present invention can be applied to fixing configurations requiring a wider clamping width (e.g., high-speed machines).

[0196] In another variation of the configuration in which the substrate of the heater abuts the inner peripheral surface of the film, in order to extend the life of the fixing device, a process to improve sliding properties (e.g., anti-corrosion aluminum treatment or mold release agent coating) can be performed on the surface of the substrate.

[0197] Example 3

[0198] Next, we will refer to Figure 16 as well as Figure 17A and 17B Example 3 according to the present invention is described. This example is characterized in that a heat dissipation member 81 is disposed between the heater 102 and the film 23 to diffuse and homogenize the temperature distribution of the heat generated by the heating element of the heater 102. Since a similar configuration to that in Example 1 is used in other configurations of the image forming apparatus and fixing device in Example 3, its description will be omitted. The characteristic configuration of Example 3 will be described in detail below.

[0199] Figure 16 This is a perspective view showing a cross-section of the fixing device 109 equipped with a heater 102 in this example. Figure 17A This is a schematic diagram showing the configuration of heater 102. Figure 17B This is a cross-sectional view showing the fixing device 109 in the vicinity of the heater 102. In this example, a longer heat dissipation member 81 in the same direction as the heater 102 is disposed between the heater 102 and the membrane 23.

[0200] In this example, heater 102 also includes an elongated plate-shaped substrate 1021 (which contains metal as the main material), a heating element 1023 that heats up in response to energization, an insulating layer 1022 that insulates the heating element 1023 from the substrate 1021, and a protective layer 1024 that protects the heating element 1023.

[0201] like Figure 17A As shown, the substrate 1021 in this example is a relatively long member in the longitudinal direction, made of metal, and has an insulating layer 1022 and a heating element 1023 provided at the central side planar portion 1021a. The substrate 1021 is bent at its end in the transverse direction orthogonal to the longitudinal direction, so as to be close to the pressure roller 30 side in the thickness direction of the substrate 1021. Furthermore, the end planar portions 1021b, which are substantially parallel to the central side planar portion 1021a, are provided at both ends of the substrate 1021 in the transverse direction such that the end planar portions 1021b are located on the pressure roller 30 side (heating element 1023 side). In addition, the substrate 1021 also includes a plurality of bends formed over the entire range in the longitudinal direction.

[0202] In the transverse direction of the substrate 1021, the central region of the surface on which the insulating layer 1022 is provided is defined as a first region R1, the region relative to one end of the first region R1 is defined as a second region R2, and the region relative to the other end of the first region R1 is defined as a third region R3. In this example, both the second region R2 and the third region R3 include two bends. In other words, the first region R1 of the substrate 1021 is planar, and the second region R2 and the third region R3 are bent from the first region R1.

[0203] In this example, the substrate 1021 is formed by stretch pressing, and the stretching depth d6 of the substrate 1021 (i.e., the height difference between the central side plane portion 1021a and the end side plane portion 1021b) is 100 μm. The thickness of the substrate 1021 is 0.5 mm, the length L1 of the central side plane portion in the lateral direction is 6 mm, and the length L2 of the heater 102 in the lateral direction is 8 mm.

[0204] In this example, the heater 102 is configured such that the stretching depth d6 of the substrate 1021 is substantially the same as the total thickness of the insulating layer 1022 and the protective layer 1024 on the central side plane portion 1021a, and the surface of the protective layer 1024 and the end side plane portion 1021b are substantially on the same plane. With this configuration, both the end side plane portion 1021b and the protective layer 1024 are in contact with the heat dissipation member 81, such as... Figure 17B As shown.

[0205] The heat dissipation member 81 is a metal plate with its two ends folded towards the thermistor 25 in the lateral direction and has a generally C-shaped cross-section. Ideally, the heat dissipation member 81 is a metal plate with a thickness in the range of 0.2 mm to 1.0 mm. For example, thin metal sheets made of stainless steel, aluminum alloy, or iron can be used as the heat dissipation member 81. Furthermore, it is ideal to perform a treatment (e.g., glass coating or hard chrome coating) on ​​the sliding surface of the heat dissipation member 81 that abuts against the film 23 to reduce the coefficient of friction and enhance wear resistance.

[0206] In this example, a 0.5 mm thick stainless steel sheet is used as the heat dissipation member 81. The heat dissipation member 81 is formed by performing a folding process at the end position of the stainless steel sheet in the transverse direction to have a length of 0.6 mm at the fold. After the folding process, the length of the heat dissipation member 81 in the transverse direction is 9.0 mm, and a glass coating with a thickness of 50 μm is applied to the sliding portion abutting the membrane 23.

[0207] Furthermore, the portion between the heater 102 and the heat dissipation member 81 is coated with grease to enhance heat transfer performance. In this example, thermally conductive grease is applied as grease, and the heater 102 is held in place by the heater support 21 while the heater 102 and the heat dissipation member 81 are in close contact with each other.

[0208] The generally C-shaped cross-section of the heat dissipation member 81, as described above, prevents some of the grease applied between the heater 102 and the heat dissipation member 81 from being expelled from the heat dissipation member 81 and adhered to the membrane 23 due to the pressure and heating achieved by the fuser.

[0209] The thermistor 25, serving as a temperature detection unit, abuts against the second surface of the substrate on the side opposite to the first side where the resistive heating element is located, along a thickness direction orthogonal to the longitudinal and transverse directions of the heater 102. The thermistor 25 controls the energization of the heating resistor and manages the temperatures of the heater 102 and the film 23 based on the temperature detected by it. In other words, in this example, the thermistor 25 detects temperature changes in the film 23 via the heat dissipation member 81 and the heater 102.

[0210] To verify the effects and advantages of the present invention, evaluation tests including comparative examples were conducted. In these evaluation tests, similar to those of Example 1, the warpage of the heaters in this example and Comparative Examples 3 and 4, the adjustable temperature for fixing, and the loading capacity were evaluated.

[0211] In this example and the two comparative examples, three types of heaters were used for evaluation testing. The heater configuration in Comparative Example 3 is the same as that of heater 52 in Comparative Example 1, which was used for comparison with Example 1. Furthermore, the heater configuration in Comparative Example 4 is the same as that of heater 62 in Comparative Example 2, which was used for comparison with Example 1. Other configurations in Comparative Examples 3 and 4 are similar to those in Example 3, and heat dissipation components similar to those in Example 3 are also provided in Comparative Examples 3 and 4.

[0212] Table 6 shows the main configurations in this example and Comparative Examples 3 and 4, along with the evaluation results of warpage, assemblability, fixing capability, and loading capability during molding. Regarding assemblability, in the table below, warpage not exceeding 3 mm is described as OK, and other cases are described as NG.

[0213] [Table 6]

[0214]

[0215] In Example 3, the warpage of heater 22 is 2.8 mm, and there are no assembly issues. Furthermore, the temperature is set to 190°C, and it can hold 200 sheets of recording material.

[0216] In Comparative Example 3, the warpage of heater 52 was 0.1 mm. This result shows that warpage can also be suppressed by providing an insulating layer 525 on the surface opposite to the surface on which the heating element 523 is formed.

[0217] However, the set temperature in Comparative Example 3 is 200°C, which is higher than the temperature in Example 3; and the number of sheets of recording material that can be loaded is 50, which is also less than the number of sheets in Example 3. Compared with Example 3, in Comparative Example 3, because the sensitivity of the thermistor 25 to detect temperature changes in the film 23 is reduced due to the thermal resistance of the insulating layer 525, the set temperature is increased, the warping of the recording material is further increased, and the number of sheets of recording material that can be loaded is reduced. In other words, in Comparative Example 3, a balance cannot be achieved between suppressing heater warping and detecting temperature changes in the heat dissipation member 81 with satisfactory responsiveness.

[0218] In Comparative Example 4, the warpage of heater 62 was 11 mm, and there were difficulties in assembly. Since the bending strength of the substrate in the thickness direction was enhanced by bending the substrate in Example 3, the warpage of the heater in Example 3 was significantly reduced compared to Comparative Example 4, which had the same layer configuration.

[0219] Furthermore, in Comparative Example 4, the set temperature was 195°C, and the number of sheets of recording material that could be loaded was 100. Although the insulating layer was only provided on one surface of the substrate in both Comparative Example 4 and Example 3, the substrate 1021 in Example 3 was formed with a stretching depth d6 of 100 μm, and the end of the substrate 1021 in the lateral direction was in contact with the heat dissipation member 81. In other words, compared to Comparative Example 4, in Example 3, the heat from the heat dissipation member 81 was transferred to the substrate 1021 not only via the protective layer 1024, but also directly from the heat dissipation member 81 to the substrate 1021, making it easier for the heat to be transferred to the substrate 1021. Therefore, since the temperature change of the heat dissipation member 81 could be sensed more sensitively in Example 3 compared to Comparative Example 4, the set temperature in the configuration of Example 3 was lower, and the number of sheets of recording material that could be loaded was increased compared to Comparative Example 4.

[0220] As described above, according to the present invention, heater warpage caused during heater molding can be suppressed to a level where no problems arise during assembly. Furthermore, since the conditioning temperature is reduced and the curling of the recording material is suppressed by detecting temperature changes in the heat dissipation member 81 with satisfactory responsiveness, the number of sheets of recording material that can be loaded can be increased. In other words, by bending the substrate so that the end side of the substrate in the lateral direction approaches the pressure roller side (heating element side) in the thickness direction, heater warpage can be suppressed without providing insulating layers on both surfaces of the substrate. Furthermore, since heat from the heat dissipation member is also transferred to the end side of the substrate in the lateral direction, temperature changes in the heat dissipation member can be detected with satisfactory responsiveness. Moreover, since no insulating layer is provided on one surface of the substrate, temperature changes in the film can be detected with satisfactory responsiveness.

[0221] It should be noted that although in this example, the stretching depth d6 of the folded portion of the substrate is set to 100 μm to achieve a height substantially flush with the protective layer 1024, the present invention is not limited thereto, and the depth of the folded portion of the substrate can be set to a value less than the total thickness of the insulating layer and the protective layer. Even with this configuration, temperature changes in the film 23 and the heat dissipation member 81 can be sensitively sensed, compared to a configuration where the substrate does not include any folded portions.

[0222] As a variation of Example 3, refer to Figure 18 Describe variant example 5. Figure 18 This is a cross-sectional view of the fixing device near the heater 112, according to Variation 5. The same reference numerals will be applied to the configuration in Variation 5 that is similar to that in Example 3, and its description will be omitted.

[0223] like Figure 18As shown, in Variation 5, the substrate of the heater 112 is configured such that it does not include the end-side planar portion, the substrate is formed such that both ends of the substrate extend substantially parallel to the thickness direction in the transverse direction, and the substrate includes only two bends. Furthermore, the end of the substrate in the transverse direction contacts the folded portion at the end of the heat dissipation portion in the transverse direction. Even with this configuration, warping of the heater can be suppressed by the substrate having the bends, and since the bends of the substrate contact the heat dissipation member 81, temperature changes in the heat dissipation member 81 can be sensitively sensed. Therefore, similar to Example 3, a balance between suppressing heater warping and detecting temperature changes in the heat dissipation member 81 with satisfactory responsiveness can also be achieved in Variation 5.

[0224] Furthermore, in another variation, a configuration can be adopted in which the heater does not include the end-side planar portion, the two ends of the substrate in the transverse direction are folded in the direction of the surface opposite to the surface where the heating element is located, and the substrate includes only two curved portions, such that the two ends of the substrate extend substantially parallel to the thickness direction. Even with this configuration, an effect similar to Example 3 can be obtained by contacting the two ends of the substrate in the transverse direction with the folded portions at the ends of the heat dissipation member in the transverse direction.

[0225] Example 4

[0226] Next, we will refer to Figure 19 and 20 Example 4 is described according to the present invention. Figure 19 This is a perspective view showing a cross-section of the fixing device 129 equipped with a heater 122 according to Example 4. Figure 20 This is a cross-sectional view of the fixing device 129. The fixing configuration in this example is characterized in that a heat transfer member 85, located at a position other than the clamping portion N (i.e., the area where the film 83 and the pressure roller 90 are in close contact with each other), is heated by a heater 122, and the film 83 is heated via the heat transfer member 85. Because there is no heater in the clamping portion N, the design freedom of the clamping portion is increased, and the size of the clamping portion N can be increased. Therefore, the advantage of this fixing configuration lies in achieving a high throughput.

[0227] In this example, the heater according to the invention is used as a heating device for heating the heat transfer member 85 described above. Other feature configurations of the image forming apparatus and fixing device in Example 4 will be described in detail. Furthermore, the same reference numerals will be applied to configurations in Example 4 similar to those in Example 1, and their descriptions will be omitted.

[0228] Reference Figure 20The configuration of the fixing device 129 in this example is described. The fixing device 129 in this example includes a tubular membrane 83 serving as a first rotating body and a pressure roller 90 serving as a second rotating body for transporting recording material. The fixing device 129 also includes: a clamping roller 86 and a clamping forming member 87, which are disposed within the internal space of the membrane and form a clamping portion N with the pressure roller 90 across the membrane 83; and a heater 122, which is disposed within the internal space of the membrane 83 at a location other than the clamping portion N. The fixing device 129 also includes a heater support member 84 and a heat transfer member 85, which holds the heater 122 and is disposed within the internal space of the membrane, and the heat transfer member 85 abuts against the membrane 83 within the internal space of the membrane 83 and uniformly diffuses and transfers the heat generated by the heater 122. Furthermore, the clamping forming member 87 and the heater support member 84 are pressurized by a pressure spring (not shown), which is located at the end of the strut 91 in the longitudinal direction, and the strut 91 is located in the internal space of the membrane 83.

[0229] In this example, the heat transfer member 85, the clamping roller 86, and the clamping forming member 87, which are disposed in the internal space of the membrane 83, are arranged to abut against the inner surface of the membrane 83. In the adjacent direction of the membrane 83 and the pressure roller 90, the clamping roller 86 and the clamping forming member 87 abut against the membrane 83 on the side closer to the pressure roller 90, and the heat transfer member 85 abuts against the membrane 83 on the side away from the pressure roller 90.

[0230] Membrane 83 is a composite layer membrane in which the base layer is made of PI with a thickness of 100 μm and coated with a release layer made of PFA with a thickness of 12 μm to achieve a balance between release layer wear and thermal conductivity due to paper feeding, and a composite layer membrane with an outer diameter of Φ45 mm is used.

[0231] The pressure roller 90 is composed of a core metal and an elastic layer. The elastic layer is made of 1.5 mm thick silicone rubber, and the release layer is made of 30 μm thick PFA tube. The outer diameter of the pressure roller 90 is set to Φ36 mm to ensure the clamping width.

[0232] The clamping roller 86, located within the internal space of the membrane 83, is composed of a core metal and an elastic layer. A 2.0 mm thick silicone rubber layer is used for the elastic layer of the clamping roller 86, with an outer diameter of Φ25 mm.

[0233] The clamping forming member 87 is pressed into close contact with the membrane 83 by a pressure spring disposed on the inner surface of the membrane. Compared to the configuration where the heater and pressure roller form the clamping portion, in this example, the clamping roller 86 and the clamping forming member 87 form a clamping portion with the pressure roller 90 across the membrane 83, thus increasing the clamping width. The shape of the portion of the clamping forming member 87 that contacts the membrane 83 and also guides the rotation of the membrane is a composite curve including a generally planar portion and a generally curved portion, and aluminum drawing material is used as the material of the clamping forming member 87 to improve dimensional accuracy. The generally planar portion of the clamping forming member 87 forms a clamping portion with the pressure roller 90 across the membrane 83.

[0234] The thermistor 25, serving as a temperature detection unit, abuts against the second surface of the substrate on the side opposite to the first surface where the resistance heating element is located via a through hole provided in the heater support member 84 in a thickness direction orthogonal to the longitudinal and transverse directions of the heater 122. The energization of the heating resistor is controlled based on the temperature detected by the thermistor 25, thereby managing the temperature of the heater 122 and the film 83. In other words, in this example, the thermistor 25 detects temperature changes in the film 83 via the heat transfer member 85 and the heater 122.

[0235] The heater support member 84 is made of PPS with high heat resistance and high thermal insulation performance, and the surface opposite to the surface supporting the heater 122 is configured to receive pressure from a pressure spring, which is located at two positions at the ends of the strut 91 in the longitudinal direction and is not shown in the figure.

[0236] Aluminum, which has high thermal conductivity, is used as the material for the heat transfer member 85 to effectively transfer heat from the heater 122 to the membrane 83, and the contact surface with the membrane 83 has a generally arcuate shape to ensure a wide contact area with the membrane 83. Furthermore, to enhance the tight contact between the heater 122 and the heat transfer member 85 and ensure heat transfer performance, the portion between the heater 122 and the heat transfer member 85 is coated with a grease (not shown).

[0237] In this example, heater 122 also includes an elongated plate-shaped substrate 1221 (containing metal as the main material), a heating element 1223 that heats up in response to electricity, an insulating layer 1222 that insulates the heating element 1223 from the substrate 1121, and a protective layer 1224 that protects the heating element 1223. Since the shape of heater 122 in this example is the same as that of heater 102 in Example 3, its description will be omitted.

[0238] The heater 122 is configured such that the stretching depth of the substrate 1221 is substantially the same as the total thickness of the insulating layer 1222 and the protective layer 1224 on the central plane portion 1221a, and the surface of the protective layer 1224 and the end-side plane portion 1221b are substantially on the same plane. With this configuration, as... Figure 20 As shown, the end-side planar portion 1221b and the protective layer 1224 are in contact with the heat transfer member 85, so the thermistor 25 can detect the temperature change of the film 83 and the heat transfer member 85 with satisfactory responsiveness.

[0239] The evaluation tests, including comparative examples, were conducted to verify the effects and advantages of the present invention. Similar to the evaluation tests in Example 1, the warpage of the heaters in this example and Comparative Examples 5 and 6, the adjustable temperature for fixing, and the loading capacity were evaluated.

[0240] In this example and the two comparative examples, three types of heaters were used for evaluation testing. The heater configuration in Comparative Example 5 is the same as that of heater 52 in Comparative Example 1, which was used for comparison with Example 1. Furthermore, the heater configuration in Comparative Example 6 is the same as that of heater 62 in Comparative Example 2, which was used for comparison with Example 1. Other configurations in Comparative Examples 5 and 6 are similar to those in Example 4, and the heat transfer member 85, clamping forming member 87, etc., are also provided in Comparative Examples 5 and 6 in a manner similar to that in Example 4.

[0241] Table 7 shows the main configurations in this example and Comparative Examples 5 and 6, along with the evaluation results of warpage and assemblability, fixing ability, and loading capacity during molding heater operation. Regarding assemblability, in the table below, warpage not exceeding 3 mm is described as OK, and other cases are described as NG.

[0242] [Table 7]

[0243]

[0244] In Example 4, the warpage of heater 22 is 1.4 mm, and there are no assembly issues. Furthermore, the temperature is set to 190°C, and it can hold 200 sheets of recording material.

[0245] In Comparative Example 5, the warpage of heater 52 was 0.1 mm. This result shows that warpage can also be suppressed by providing an insulating layer 525 on the surface opposite to the surface on which the heating element 523 is formed.

[0246] However, the set temperature in Comparative Example 5 is 200°C, which is higher than the set temperature in Example 4, and the number of recording sheets that can be loaded is 50, which is less than the result in Example 4. Since the sensitivity of the thermistor 25 to detect temperature changes in the film 83 is reduced in Comparative Example 5 compared to Example 4 due to the thermal resistance of the insulating layer 525, the increased set temperature further increases the curling of the recording material, and reduces the number of recording sheets that can be loaded. In other words, in Comparative Example 5, a balance cannot be achieved between suppressing heater warping and detecting temperature changes in the heat transfer member 85 with satisfactory responsiveness.

[0247] In Comparative Example 6, the warpage of heater 62 was 11 mm, and assembly was difficult. Compared to Comparative Example 6, which had the same layer configuration, in Example 4, the bending strength of the substrate in the thickness direction was enhanced by bending the substrate, and the warpage of the heater in Example 4 was significantly reduced.

[0248] Furthermore, in Comparative Example 6, the set temperature was 195°C, and the number of sheets of recording material that could be loaded was 100. Although the insulating layer was only provided on one surface of the substrate in both Comparative Example 6 and Example 4, in Example 4, the substrate 1221 was formed with a stretch depth of 100 μm, and the end of the substrate 1221 in the lateral direction was in contact with the heat transfer member 85. In other words, since the heat from the heat transfer member 85 was transferred to the substrate 1221 not only via the protective layer 1224, but also directly from the heat transfer member 85 to the substrate 1221 in Example 4, the heat from the heat transfer member 85 was more easily transferred to the substrate 1221 compared to Comparative Example 6. Therefore, since the temperature change of the heat transfer member 85 could be sensed more sensitively in Example 4 compared to Comparative Example 6, the set temperature in Example 4 was lower, and the number of sheets of recording material that could be loaded was increased.

[0249] As described above, according to the present invention, heater warpage that occurs during heater molding can be suppressed to the point that no problems arise during assembly. Furthermore, by detecting temperature changes in the heat transfer member 85 with satisfactory responsiveness, the set temperature is reduced and curling of the recording material is suppressed, thus increasing the number of sheets of recording material that can be loaded. In other words, by bending the substrate so that the end side of the substrate in the lateral direction approaches the side opposite to the heater support member in the thickness direction (the heat transfer member side), heater warpage can be suppressed without providing insulating layers on both surfaces of the substrate. Furthermore, since heat from the heat transfer member is also transferred to the end side of the substrate in the lateral direction, temperature changes in the heat dissipation member can be detected with satisfactory responsiveness. Moreover, since no insulating layer is provided on one surface of the substrate, temperature changes in the film can be detected with satisfactory responsiveness.

[0250] Furthermore, although the depth of the folded portion of the substrate is set to 100 μm in this example to achieve a height that makes the protective layer 1224 substantially flat, the present invention is not limited thereto, and the depth of the folded portion of the substrate can be less than the total thickness of the insulating layer and the protective layer. Even with this configuration, temperature changes in the film 83 and the heat transfer member 85 can be sensed.

[0251] Reference Figure 21 The following describes variant example 6, which is a variant of example 4. Figure 21 This is a cross-sectional view showing the fixing device near the heater 132 according to Variation 6. The same reference numerals will be applied to the configuration in Variation 6 that is similar to that in Example 4, and its description will be omitted.

[0252] like Figure 21 As shown, in Variation 6, the substrate of heater 132 is configured such that it does not include end-side planar portions, the substrate is formed such that its two ends in the transverse direction extend substantially parallel to the thickness direction, and the substrate has only two bends. Furthermore, the ends of the substrate in the transverse direction contact the heat transfer member. Even with this configuration, heater warping can be suppressed by the substrate with the bends, and because the bends of the substrate contact the heat transfer member 85, temperature changes in the heat transfer member 85 are sensitively sensed. Therefore, similar to Example 4, in Variation 6, a balance can be achieved between suppressing heater warping and detecting temperature changes in the heat transfer member 85 with satisfactory responsiveness.

[0253] Furthermore, in another variation, the heater may not include the end-side planar portion, both ends of the substrate in the transverse direction may be folded in the direction opposite to the surface where the heating element is located, the substrate may have only two bends such that both ends of the substrate extend substantially parallel to the thickness direction, and the substrate may be porous. Even with this configuration, similar effects to Example 4 can be obtained by bringing the two ends of the substrate in the transverse direction into contact with the heat transfer member.

[0254] Examples of configurations or concepts disclosed in the foregoing embodiments will be described below. However, these are merely examples, and the disclosure of the foregoing embodiments is not limited to the configurations or concepts described below.

[0255] Configure A1

[0256] A heater, comprising:

[0257] A slender substrate made of metal;

[0258] An insulating layer disposed on a substrate; and

[0259] Heating elements are mounted on the insulation layer.

[0260] Wherein, in the case that the region including the center of the substrate is defined as the first region, along the lateral direction, a region closer to one end side than the first region is defined as the second region, and a region closer to another end side than the first region is defined as the third region, the lateral direction being orthogonal to the longitudinal direction of the surface of the substrate on which the insulating layer is provided, the first region being planar, and

[0261] The second and third regions are bent from the first region along the thickness direction of the substrate, which is orthogonal to the longitudinal and transverse directions.

[0262] Configuration A2

[0263] In the heater according to configuration A1, the second region includes a first bend that is bent to approach the heating element from the first region along the thickness direction.

[0264] Configuration A3

[0265] In the heater according to configuration A2, the second region includes a second curved portion that bends laterally from the first curved portion.

[0266] Configuration A4

[0267] In the heater according to configuration A3, the second curved portion includes a plane parallel to the first region.

[0268] Configuration A5

[0269] In the heater according to configuration A4, the distance from the plane of the first region to the plane of the second bend in the thickness direction is greater than the thickness of the insulating layer.

[0270] Configuration A6

[0271] In the heater according to configuration A2, the third region includes a third bend that is bent to approach the heating element from the first region along the thickness direction.

[0272] Configuration A7

[0273] In the heater according to configuration A6, the third region includes a fourth bend that bends laterally from the third bend.

[0274] Configuration A8

[0275] In the heater according to configuration A7, the fourth bend includes a plane parallel to the first region.

[0276] Configure A9

[0277] In the heater according to configuration A8, the distance from the plane of the first region to the plane of the fourth bend in the thickness direction is greater than the thickness of the insulating layer.

[0278] Configure A10

[0279] In the heater described according to any of the configurations A1 to A9, no insulating layer is provided on the substrate in the second and third regions.

[0280] Configure A11

[0281] In the heater according to any of the configurations A1 to A10, the second region and the third region are bent from the first region throughout the longitudinal direction of the substrate.

[0282] Configure A12

[0283] In the heater described according to any of the configurations A1 to A11, when the surface on which the insulating layer is provided is defined as the first surface, no insulating layer is provided on the second surface of the substrate opposite to the first surface in the thickness direction.

[0284] Configure A13

[0285] In the heater described according to any one of configurations A1 to A11, when the insulating layer with heating element is defined as the first insulating layer and the surface with the first insulating layer is defined as the first surface, the substrate has a second insulating layer without heating element on a second surface opposite to the first surface in the thickness direction, and the first insulating layer is thicker than the second insulating layer in the thickness direction.

[0286] Configure A14

[0287] A heating device, comprising:

[0288] First body of revolution;

[0289] The heater described according to any one of configurations A1 to A13 is disposed in the internal space of the first rotating body;

[0290] A second rotating body, the second rotating body forming a clamping portion with the heater via the first rotating body; and

[0291] Temperature detection unit for detecting the temperature of the heater.

[0292] The temperature detection unit is located on the surface opposite to the surface of the insulating layer containing the heating element along the thickness direction.

[0293] Configure A15

[0294] In the heating device according to configuration A14, the second region and the third region abut against the first rotating body.

[0295] Configure A16

[0296] In the heating device described according to configuration A14 or A15

[0297] The first rotating body is a tubular membrane, and

[0298] The second rotating body is a roller.

[0299] Configuration A17

[0300] A heating device, comprising:

[0301] First body of revolution;

[0302] The heater includes an elongated metal substrate, an insulating layer disposed on the substrate, and a heating element disposed on the insulating layer, the heater being disposed within the internal space of the first rotating body; and

[0303] The second rotating body forms a clamping part with the heater via the first rotating body.

[0304] Wherein, in the case that the area including the center of the substrate is defined as the first region, along the transverse direction, the region that is closer to one end side than the first region is defined as the second region, and the region that is closer to the other end side than the first region is defined as the third region, the transverse direction being orthogonal to the longitudinal direction of the surface of the substrate having an insulating layer, the second region and the third region are bent to be positioned in the thickness direction of the substrate, which is orthogonal to the longitudinal direction and the transverse direction, so as to be closer to the clamping part side than the first region.

[0305] Configuration A18

[0306] In the heating device according to configuration A17, the second region includes a first curved portion that is bent to approach the clamping portion side from the first region along the thickness direction.

[0307] Configure A19

[0308] In the heating device according to configuration A18, the second region includes a second curved portion that bends laterally from the first curved portion.

[0309] Configure A20

[0310] In the heating device according to configuration A19

[0311] The first region includes a plane, and

[0312] The second curved portion includes a plane parallel to the first region.

[0313] Configuration A21

[0314] In the heating device according to configuration A20, the distance from the plane of the first region to the plane of the second curved portion in the thickness direction is greater than the thickness of the insulating layer.

[0315] Configure A22

[0316] In the heating device described according to any of the configurations A18 to A21

[0317] The third region includes a third bend that is bent to approach the heating element from the first region along the thickness direction.

[0318] Configuration A23

[0319] In the heating device according to configuration A22, the third region includes a fourth bend that bends laterally from the third bend.

[0320] Configuration A24

[0321] In the heating device according to configuration A23

[0322] The first region includes a plane, and

[0323] The fourth bend includes a plane parallel to the first region.

[0324] Configuration A25

[0325] In the heating device according to configuration A24, in the thickness direction, the distance from the plane of the first region to the plane of the fourth bend is greater than the thickness of the insulating layer.

[0326] Configuration A26

[0327] In the heating device described according to any of the configurations A17 to A25, no insulating layer is provided on the substrate in the second and third regions.

[0328] Configuration A27

[0329] In the heating device according to any of the configurations A17 to A26, the second region and the third region are bent from the first region throughout the longitudinal direction of the substrate.

[0330] Configuration A28

[0331] In the heating device described according to any of the configurations A17 to A27, when the surface on which the insulating layer is provided is defined as the first surface, no insulating layer is provided on the second surface of the substrate opposite to the first surface in the thickness direction.

[0332] Configuration A29

[0333] In the heating device described according to any of the configurations A17 to A27

[0334] When the insulating layer containing the heating element is defined as the first insulating layer and the surface containing the first insulating layer is defined as the first surface, the substrate has a second insulating layer without a heating element on a second surface opposite to the first surface in the thickness direction, and

[0335] The first insulating layer is thicker than the second insulating layer in the thickness direction.

[0336] Configuration A30

[0337] An image forming apparatus, comprising:

[0338] An image forming unit that forms an image on a recording material; and

[0339] According to any of the configurations A14 to A29, the heating device fixes the image formed on the recording material onto the recording material.

[0340] In heating apparatuses consisting of heaters, membranes, pressure rollers, etc., when recording material with protrusions (such as staples or accidental adhesions) is fed into the heating apparatus, openings may occur in the membrane, etc. If openings occur in the membrane, the toner image cannot be sufficiently heated at the opening portion, and fixing failure may occur. Therefore, a heating apparatus and image forming device capable of suppressing openings in the membrane will be described below.

[0341] Example 5

[0342] (1) Image forming equipment

[0343] Figure 22 This is an overall configuration diagram of the image forming apparatus 2100 using electrophotographic recording technology in Example 5. First, the configuration and operation of the image forming apparatus 2100 will be described.

[0344] The image forming operation performed by the image forming unit of the image forming apparatus 2100 will be described. If the image forming apparatus 2100 receives a print command from an external device, the scanner unit 2003 emits a laser Z towards the photosensitive member 2001 based on image information. The laser Z scans the photosensitive member 2001, which is charged by the charging roller 2002 with a predetermined polarity, and an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive member 2001. Subsequently, the developing apparatus 2004 supplies toner to the photosensitive member 2001, and a toner image corresponding to the image information is formed on the photosensitive member 2001. By rotating the photosensitive member 2001 in the direction of arrow R, the toner image on the photosensitive member 2001 moves to the transfer position formed by the photosensitive member 2001 and the transfer roller 2005, and is transferred to the recording material P fed from the cartridge 2006 by the pickup roller 2007. The surface of the photosensitive member 2001 that has passed the transfer position is cleaned by the cleaner 2008.

[0345] The fixing device 2009, which serves as the fixing unit, performs fixing processing on the recording material P on which the toner image has been transferred, using heat and pressure. Subsequently, the recording material P is discharged by the discharge roller 2010 to the discharge tray 2011.

[0346] (2) Fixing device

[0347] Next, the configuration and operation of the fixing device 2009 will be described. In this example, the tensionless film heating system fixing device 2009 is used as an example of a heating device. The fixing device 2009 in this example is a device in which an annular strip (or cylindrical) heat-resistant film is used, at least a portion of the periphery of which is always kept tensionless (in a state where no tension is applied to it), and the film is driven to rotate by the rotational driving force of the pressure member.

[0348] Figure 23 This is a general cross-sectional view of the fixing device 2009 in this example, showing two sheets of recording material P, bound with staples H, having toner images T, and being fed into the fixing device 2009. Furthermore, Figure 24A This is an exploded perspective view of the membrane unit 2020 used in the fixing device 2009. Figure 24B This is a perspective view of the heat-conducting component 2051. Figure 25 This is a front view of the fixing device 2009 when viewed from the direction of the recording material transport.

[0349] Reference Figure 23The configuration of the fixing apparatus 2009 is described. The fixing apparatus 2009 in this example includes a rotating tubular membrane 2023 and a heating unit 2050 that heats the membrane 2023 within its internal space. The heating unit 2050 consists of a heater 2022 serving as a heating element and a heat-conducting member 2051. The heat-conducting member 2051 is engaged with the heater 2022, contacts the inner surface of the membrane 2023, and transfers heat from the heater 2022 to the membrane 2023. The fixing apparatus 2009 also includes a membrane guide 2021 that supports the heater 2022 and guides the rotation of the membrane 2023, a reinforcing member 2024 that strengthens the membrane guide 2021, and a pressure roller 2030 that forms a clamping portion N with the heating unit 2050 and the membrane guide 2021 across the membrane 2023.

[0350] The heater 2022 includes an elongated plate-shaped substrate 2022a made of ceramic, a heating element 2022b that heats up in response to electricity, and a protective layer 2022c that protects the surface of the heating element 2022b. The detailed configuration of the heater 2022 will be described later.

[0351] A thermistor 2025, serving as a temperature sensing component, abuts against the surface of the abutment membrane guide 2021 of the heater 2022. The energization of the heating element 2022b is controlled based on the temperature detected by the thermistor 2025, thereby managing the temperatures of the heater 2022 and the membrane 2023.

[0352] Membrane 2023 is a tubular rotating body. The thickness of membrane 2023 is preferably at least 20 μm and not more than 100 μm to ensure satisfactory thermal conductivity. In the case of a single-layer membrane 2023, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), PPS, etc., are preferably used as the membrane base layer 2023a. In the case of a composite membrane, materials such as polyimide (PI), polyamide-imide (PAI), polyether ether ketone (PEEK), and polyether sulfone (PES) are preferably used as the membrane base layer 2023a. Furthermore, as the release layer 2023b to be coated on its surface, the composite membrane is preferably configured to use materials such as PTFE, PFA, tetrafluoroethylene-perfluoroalkyl vinyl ether (FEP). Additionally, membranes obtained by using pure metals or alloys with high thermal conductivity such as SUS, Al, Ni, Cu, Zn, etc., in the base layer, and performing the aforementioned coating treatment on the release layer, or by coating with a fluoropolymer tube, are also suitable.

[0353] In this example, membrane 2023 is a composite membrane, wherein the base layer 2023a is made of PI with a thickness of 60 μm and coated with a membrane release layer 2023b made of PFA with a thickness of 12 μm to achieve a balance between wear and thermal conductivity of the membrane release layer 2023b due to paper feeding. The length of membrane 2023 in the longitudinal direction is 240 mm. The axial direction of the cylindrical shape of membrane 2023 will be referred to below as the longitudinal direction.

[0354] The membrane guide 2021 is a support member disposed within the internal space of the membrane 2023 and supported by the heater support 2021a for the heater 2022. The membrane guide 2021 has a recess 2021b that engages with a protrusion 2051a of the heat-conducting member 2051, as will be described below. The membrane guide 2021 has a membrane 2023 loosely fitted thereon and also has a guiding function that guides the membrane 2023 to rotate while maintaining sliding contact with the inner circumferential surface of the membrane 2023. Since the membrane guide 2021 needs to have heat resistance and rigidity, it is preferable to use a liquid crystal polymer resin or similar material with high heat resistance and excellent strength as the material for the membrane guide 2021. For example, a molded article made of a heat-resistant resin such as polyphenylene sulfide (PPS) or a liquid crystal polymer can be used as the membrane guide 2021.

[0355] The reinforcing member 2024 is made of a metal such as iron, receives the force of the pressure spring (described below), and presses the heater 2022 against the pressure roller 2030 side via the membrane guide 2021. Furthermore, the reinforcing member 2024 also maintains strength to prevent significant deformation even under pressure from the clamping portion N formed by the membrane guide 2021.

[0356] The thermally conductive member 2051 is a relatively long member in the longitudinal direction and is suitable for use with a material such as metal that has excellent thermal conductivity. As described above, the thermally conductive member 2051 constitutes the heating unit 2050 for heating the film 2023 together with the heater 2022. In other words, the heating unit 2050 heats the film 2023 via the already heated heater 2022 and through the thermally conductive member 2051. In this example, the thermally conductive member 2051 is bonded to the heater 2022 by a thermally conductive adhesive 2060 and is in contact with the inner circumferential surface of the film 2023.

[0357] When viewed along the thickness direction of the substrate 2022a, the heat-conducting member 2051 is configured to cover the entire area of ​​the substrate 2022a in the lateral direction. The heat-conducting member 2051 includes a folded L-shaped protrusion 2051a at its lateral end, and the protrusion 2051a protrudes in the thickness direction of the substrate 2022a towards a side further away from the pressure roller 2030 than the heater 2022. When viewed along the thickness direction of the substrate 2022a, the protrusion 2051a is positioned upstream of the heater 2022 in the transport direction at a location where it does not overlap with the substrate 2022a and the heating element 2022b, so as to engage with the recess 2021b. Furthermore, the protrusion 2051a and the recess 2021b are positioned together in the transport direction further upstream of the outlet of the clamping part N and further downstream of the inlet of the clamping part N. The relative movement of the heating unit 2050 with respect to the film guide 2021 in the transport direction is limited by the protrusion 2051a inserted into the recess 2021b provided in the film guide 2021. Note that in this example, the thickness direction of the substrate 2022a is substantially parallel to the pressure direction of the recording material P transported to the fixing device 2009.

[0358] The pressure roller 2030 is a rotating body that includes a core metal 2030a made of a material such as iron or aluminum, an elastic layer 2030b made of a material such as silicone rubber, and a release layer 2030c made of a material such as PFA. The pressure roller 2030 receives power from the motor M via a gear (not shown), rotates in the b direction, and forms a clamping portion N together with the heating unit 2050 and the film guide 2021 through the membrane 2023.

[0359] like Figure 23 As shown, the film 2023 is driven by the movement of the pressure roller 2030 and rotates in the a direction due to the rotation of the pressure roller 2030 in the b direction, and the heating unit 2050 receives force in the direction of arrow c, which is substantially parallel to the transport direction of the recording material P. However, as described above, since the protrusion 2051a of the heat-conducting member 2051 engages with the recess 2021b of the film guide 2021, the heating unit 2050 does not move or warp significantly in the c direction within the heater support 2021a. By clamping and transporting the recording material P by the clamping part N, the toner image T is heated and fixed on the recording material P, and the recording material P that has passed through the clamping part N is transported to the discharge tray 2011.

[0360] Next, we will refer to Figure 24AThe exploded perspective view depicts the membrane unit 2020 of the fixing apparatus 2009. The heater 2022 and the heat-conducting member 2051, bonded together by a thermally conductive adhesive, are held by the membrane guide 2021 to form the heating unit 2050. After the membrane guide 2021 and the reinforcing member 2024 are assembled together, the membrane 2023 is fitted onto the outer periphery of the membrane guide 2021 and the reinforcing member 2024, with a circumferential allowance. The two ends of the reinforcing member 2024 extend beyond the two ends of the membrane 2023, and flanges 2026 are fitted to both ends. In this manner, the membrane unit 2020, including the membrane 2023, the heating unit 2050, the membrane guide 2021, the flanges 2026, etc., is assembled.

[0361] The power supply terminal of heater 2022 protrudes from one end of membrane 2023 in the longitudinal direction, and power supply connector 2027 is fitted to the power supply terminal. Power supply connector 2027 contacts the electrode portion of heater 2022 with a predetermined abutment pressure and forms a power supply path. Furthermore, heater clamp 2028 is a C-shaped metal plate that uses its elasticity to hold the end of heater 2022 at membrane guide 2021. In other words, the two ends of heater 2022 located outside the sheet passage area in the longitudinal direction are held by power supply connector 2027 and heater clamp 2028, which serve as holding members.

[0362] like Figure 24B As shown, the heat-conducting member 2051 has a length capable of covering the entire sheet passage area in a width direction orthogonal to the transport direction of the recording material. In this example, the width direction of the recording material is substantially parallel to the longitudinal direction of the film 2023, etc. Furthermore, the protrusion 2051a in this example extends over the entire area in the longitudinal direction of the heat-conducting member 2051. The heat-conducting member 2051 can be formed by folding a sheet member made of metal, or it can be produced by other methods such as cutting.

[0363] Next, we will refer to Figure 25 The configuration of the fixing unit 2009 is described in further detail. When the fixing unit 2009 is activated, the flanges 2026 provided at both ends of the film 2023 restrict the movement of the rotating film 2023 in the longitudinal direction and limit the position of the film 2023.

[0364] The film unit 2020 is positioned facing the pressure roller 2030 and supported by the top plate side housing 2041. The film unit 2020, supported by the top plate side housing 2041, is able to move freely in the pressure direction, but its movement in the longitudinal direction is restricted. A pressure spring 2045 is attached to the top plate side housing 2041 of the fixing device 2009 in a compressed state. The pressure of the pressure spring 2045 is received by the reinforcing member 2024 at both ends in the longitudinal direction via flanges 2026. The pressure of the pressure spring 2045 pushes the reinforcing member 2024 towards the pressure roller 2030, pressing the entire film unit 2020 towards the pressure roller 2030, thereby forming the clamping portion N.

[0365] The bearing member 2031 is configured to axially support the metal core of the pressure roller 2030 and receive pressure from the membrane unit 2020 via the pressure roller 2030. To rotatably support the metal core of the pressure roller 2030, which is heated to a relatively high temperature, the bearing member 2031 is made of a material with heat resistance and excellent sliding properties. The bearing member 2031 is attached to the bottom housing 2043 of the fixing unit 2009.

[0366] (3) Heater 2022

[0367] Next, we will use Figure 26A and Figure 26B Describe the materials, manufacturing methods, etc. that constitute heater 2022 in this example. Figure 26A This is a cross-sectional view of heater 2022 when viewed from the longitudinal direction. Figure 26B This is a plan view when viewed from the thickness direction of substrate 2022a.

[0368] (3-1)Substrate 2022a

[0369] The substrate 2022a in this example is a ceramic substrate. There are no particular restrictions on the type of ceramic; the ceramic should be appropriately selected by considering factors such as the necessary mechanical strength, the coefficient of linear expansion that is compatible with the formation of the heating element, and the availability of the substrate on the market.

[0370] The thickness of substrate 2022a can be determined by considering only strength, heat capacity, and heat dissipation performance. While a thinner substrate 2022a results in a smaller heat capacity, thus facilitating rapid start-up, excessive thickness may lead to problems such as deformation when the heating element is heated. Conversely, while a thicker substrate 2022a is advantageous in terms of deformation when the heating element is heated, excessive thickness is detrimental to rapid start-up due to its larger heat capacity. Considering the balance between mass production, cost, and performance, the preferred thickness of substrate 2022a is approximately 0.3 mm to 2.0 mm. In this example, substrate 2022a is an alumina substrate with a width of 10 mm, a length of 300 mm, and a thickness of 1 mm.

[0371] (3-2) Heating element 2022b

[0372] Heating element 2022b is obtained by printing a heating element paste, which is obtained by mixing a conductive component (A), a glass component (B), and an organic binder component (C), onto a substrate 2022a and sintering the resulting article. When the heating element paste is sintered, the organic binder component (C) burns and disappears, while components (A) and (B) remain, thereby forming a heating element 2022b containing both conductive and glass components. Here, silver-palladium (Ag·Pd), ruthenium oxide (RuO2), etc., are used individually or in combination as the conductive component (A), and a sheet resistance value (surface resistivity) of 0.1 [Ω / □] to 100 [kΩ / □] is preferably obtained. Furthermore, other materials may be included in addition to the aforementioned components (A) to (C), as long as the content is very small and does not impair the performance of the present invention.

[0373] The heating element 2022b in this example is formed from a heating element paste, which is obtained by using silver-palladium (Ag·Pd) as a conductive component and additionally combining glass and organic binder components. After the heating element paste is applied to a ceramic substrate 2022a by screen printing, the resulting article is dried at 180°C and then sintered at 850°C to form the heating element 2022b. The sintered heating element 2022b has a thickness of 15 μm, a length of 220 mm, and a width of 1.1 mm.

[0374] (3-3) Power supply electrode 2022d and conductive pattern 2022e

[0375] Figure 26BThe power supply electrode 2022d and conductive pattern 2022e shown contain silver (Ag), platinum (Pt), gold (Au), silver-platinum (Ag·Pt) alloy, silver-palladium (Ag·Pd) alloy, etc. as main components. Similar to the paste for heating elements, the power supply electrode 2022d and conductive pattern 2022e are formed by printing a paste obtained by mixing conductive component (A), glass component (B), and organic binder component (C) on a substrate 2022a and sintering the paste.

[0376] The power supply electrode 2022d and the conductive pattern 2022e are configured to supply power to the heating element 2022b, and the resistance relative to the heating element 2022b is set to be sufficiently low. For the heating element paste, the power supply electrode, and the conductive pattern paste, it is necessary to select materials that soften and melt at temperatures below the melting point of the substrate 2022a, and considering the temperature in actual use, it is necessary to select materials with heat resistance.

[0377] The power electrode 2022d and conductive pattern 2022e in this example are formed using a paste for power supply electrodes and conductive patterns. The paste is obtained by using silver as the conductive material and additionally combining glass and organic binder components. The paste for power supply electrodes and conductive patterns is applied to a ceramic substrate 2022a by screen printing, and the resulting article is then dried at 180°C and sintered at 850°C to form the power electrode 2022d and conductive pattern 2022e.

[0378] (3-4) Protective layer 2022c

[0379] Figure 26A and Figure 26B The protective layer 2022c shown is provided to protect the heating element 2022b and the conductive pattern 2022e. As a material, glass or polyimide (PI) is preferred considering heat resistance, and thermally conductive fillers with insulating properties may be added as needed.

[0380] In this example, a protective glass paste is prepared and applied to the heating element 2022b and the conductive pattern 2022e by screen printing. The resulting article is dried at 180°C and sintered at 850°C to form a protective layer 2022c with a thickness of 60 μm.

[0381] (4) Effects and advantages

[0382] To illustrate the effects and advantages of the present invention, the opening mechanism of creating holes in the film, which is a plastic component, corresponding to the positions of the staples when the fixing device is feeding recording material bound with staples will be described first.

[0383] Figure 28AThis is a diagram of staple H. Figure 28B This is a schematic diagram showing two sheets of recording material P bound together using staples H. Figure 29 This is a schematic diagram illustrating an example of the prior art where a fixing device 2109, including a film unit 2120, conveys recording material P stapled with staples H and through which paper passes. When using a stapler to staple the recording material P, the staples H are attached along the recording material P on one surface (surface A), and the staples H are folded and form a protruding bend H1 on another surface (surface B). If the fixing device is made as... Figure 28B The recording material P, which is attached by the staples H shown, may have holes W in the membrane 2023, which is a plastic component, corresponding to the positions of the staples. Figure 29 As shown. Specifically, when the recording material is conveyed such that surface B (on...) Figure 28B When the bent side of staple H (the part that is in the middle) comes into contact with membrane 2023, the sharp bent part H1 of staple H pierces membrane 2023, thus creating a noticeable hole in membrane 2023. As a result, heating and fixing of the toner image T cannot be adequately performed on the recording material P corresponding to the hole W in membrane 2023, and defects such as… Figure 29 The offset image U shown may result in poor fixing.

[0384] Will use Figures 30A to 30C as well as Figure 31A and 31B The mechanism by which the staple H makes an opening in the membrane 2023 of the fixing device 2109 in the prior art example is described in more detail. In the following, similar reference numerals will be applied to configurations similar to Example 5 in the prior art examples, and their descriptions will be omitted. Note that, unlike this example, Figures 30A to 30C as well as Figure 31A and 31B The fixing device 2109 in the prior art example shown does not have a heat-conducting member 2051 and does not include a recess provided at the film guide 2121. Therefore, the film 2023 is in direct contact with the heater 2022 and slides along the heater 2022 in the fixing device 2109.

[0385] Figure 30A This is a perspective view, in an example of the prior art, showing the state in which recording material P, bound with staples H, is conveyed to the fixing device 2109 by removing the membrane 2023 and the pressure roller 2030 so that the heater 2022 can be visually identified. Figures 30A to 30C This illustrates the case where the recording material P is conveyed with the surface B of the staple H bent side abutting the membrane 2023 in an orientation. Figure 30B The initial state of the fixing device 2109 is shown, wherein the heater 2022 is in... Figure 30A The heater support 2121a attached to the membrane guide 2121 in region A is not subject to any load. Figure 30B As shown, considering the heat generated and the resulting expansion of the heater 2022, the heater support 2121a is provided wider relative to the heater 2022, thus creating a gap S between the heater support 2121a and the heater 2022. Although both ends of the heater 2022 are held by the power supply connector 2027 and the heater clamp 2028, the heater 2022 is not specifically held in the sheet passage area through which the recording material P passes.

[0386] Figure 30C The diagram illustrates a heater 2022 in contact with the membrane 2023, receiving a force along the c-direction from the membrane 2023 due to the rotation of the membrane 2023, and warping in the transport direction of the recording material p. At this time, a gap G appears between the heater 2022 and the heater support 2121a on the upstream side of the heater 2022 in the transport direction. Since the heater 2022 is held at both ends in its longitudinal direction by the power supply connector 2027 and the heater clamp 2028, the gap G reaches its maximum value near the center in the longitudinal direction of the heater 2022.

[0387] Figure 31A This is a cross-sectional view of the central portion of the fixing device 2109 in the longitudinal direction in an example of the prior art, with the heater 2022 in a non-warped state. Figure 31B This is a cross-sectional view of the central portion of the fixing device 2109 in the longitudinal direction, with the heater 2022 warped due to the rotation of the film 2023. The heater 2022 is disposed in the heater support portion 2121a of the film guide 2121.

[0388] Because the staple H is subjected to pressure from the pressure roller 2030 at the clamping part N, the staple H is pushed into the gap G. At this time, the staple H strongly rubs against the hard and sharp corner of the heater 2022, thereby creating a hole in the portion of the film 2023 that is clamped therebetween. Note that although it is also contemplated that the staple H is pushed into the gap between the heater 2022 and the heater support 2021a and located downstream of the heater 2022 in the transport direction, the possibility of creating a hole in the film 2023 is low because the film guide 2021 is not as hard and sharp as the heater 2022. In the paper feeding evaluation described later, even with a configuration including a gap on the downstream side of the heater 2022 in the transport direction, no hole will be created in the film 2023.

[0389] (4-1) Paper feed assessment

[0390] Next, a paper feeding evaluation conducted to verify the effects and advantages of the present invention will be described. As part of the paper feeding evaluation, the paper was continuously fed at a conveying speed of 200 mm / s, and each stack of two sheets of recording material P was stapled with staples H at three positions at the front end (e.g., ...). Figure 28B Twenty sheets of paper were obtained (as shown), and the perforations in the film 2023 were checked to see if any image defects had occurred. In addition to the fixing device 2009 of this example, a similar paper feeding evaluation was performed on the fixing device 2109, which is the target of comparison in the aforementioned example of the prior art and does not have a heat-conducting member, and the results were compared.

[0391] As a result of the evaluation performed using the fixing device 2009, which is equipped with a heat-conducting member 2051 in this example, there were no openings in the film 2023, and satisfactory fixing images were obtained on all the evaluation papers.

[0392] like Figure 23 As shown, in this example, the protrusion 2051a of the heat-conducting member 2051 is inserted into the recess 2021b of the membrane guide 2021. Therefore, even if a force along the c direction is applied to the heating unit 2050, the relative movement of the heating unit 2050 with respect to the membrane guide 2021 downstream in the conveying direction is restricted. Therefore, according to the present invention, on the upstream side of the heating unit 2050 along the conveying direction, no gap for staple H to enter is generated between the heating unit 2050 and the heater support 2021a, and even when conveying recording material with some kind of protrusion (e.g., staple H), openings in the membrane 2023 can be prevented. It should be noted that when no load is applied to the heating unit 2050, either the protrusion 2051a abuts against the recess 2021b from the beginning or the protrusion 2051a does not abut against the recess 2021b from the beginning can be used, as long as the gap between the heating unit 2050 and the membrane guide 2021 is minimized according to the configuration.

[0393] As described above, the fixing device 2109 in the prior art example is configured to not provide, for example Figure 31A and 31B The heat-conducting component is shown. Since other related configurations in the image forming apparatus and fixing unit employ configurations similar to those in Example 5, their descriptions will be omitted.

[0394] When performing a paper feed test similar to Example 5 using the fixing device 2109 in the prior art example, an opening is made in the film 2023, resulting in... Figure 29 The image shown is offset U, and there is image corruption. This is because the heater 2022 receives a force along the c direction from the membrane 2023 and moves along the conveying direction, as shown. Figure 31BAs shown. In other words, the staple H is subjected to pressure from the pressure roller 2030, and the staple H is pushed into the gap G between the heater 2022 and the heater support 2121a, which is generated on the upstream side of the heater 2022 in the conveying direction. As a result, the corners of the staple H and the heater 2022 rub against each other strongly, thereby creating a hole in the membrane 2023.

[0395] It should be noted that, as described in this example, to prevent openings in the membrane, the protrusion 2051a does not necessarily need to extend over the entire longitudinal direction (width direction of the recording material) of the heat-conducting member 2051. Similar effects to those in this example can be expected simply by arranging the protrusion 2051a of the heat-conducting member 2051 in the area through which the recording material P, through which the staples H are inserted. In particular, if the protrusion 2051a is located at the center of the longitudinal direction where the deformation of the heater 2022 is greatest, the relative movement of the heating unit 2050 with respect to the membrane guide 2021 downstream in the transport direction can be effectively limited.

[0396] As described above, the present invention is not limited to the configuration in Example 5, and variations may employ, such as Figure 27A The configuration shown is similar to that of the heat-conducting member 2052, wherein the protrusion 2052a is disposed throughout the entire sheet passage area, rather than throughout the entire longitudinal direction of the heat-conducting member 2052. In another variation, a configuration such as... Figure 27B The configuration shown is that of the heat-conducting member 2053, in which multiple protrusions 2053a with shorter lengths in the longitudinal direction are provided in the sheet passage area. Since the protrusions 2052a are provided throughout the entire sheet passage area of ​​the heat-conducting member 2052, sufficient strength can be obtained to resist the forces exerted due to the rotation of the film 2023. On the other hand, since the heat-conducting member 2053 includes protrusions 2053a with shorter lengths in the longitudinal direction at three locations in the sheet passage area, the heat-conducting member 2053 is not as strong as the heat-conducting member 2052. However, from the perspective of minimizing the increase in heat capacity, the heat-conducting member 2053, with its smaller volume, is worse than the heat-conducting member 2052. In other words, the required configuration can be appropriately selected by considering factors such as the pressure of the fixing device, the required strength based on the film rotation speed, the preheating time required by the image forming equipment, and the manufacturing cost of the heat-conducting member.

[0397] Although this example uses a configuration where the protrusion 2051a is located upstream of the heater 2022 in the conveying direction, other variations are also conceivable, such as a configuration where the protrusion is located downstream in the conveying direction, or a configuration where protrusions are provided on both the upstream and downstream sides. Alternatively, a variation could be exemplified where the protrusion extends towards the pressure roller in the pressing direction instead of away from it. Furthermore, the protrusion does not necessarily extend perpendicular to the surface of the recording material, and it can extend at a predetermined angle relative to the pressing direction, as long as the movement of the heating unit downstream in the conveying direction is limited by this configuration. In other words, the configuration is not limited to protrusions and recesses; as long as the heating unit and the heater support have a joint and a joined portion to limit the relative movement of the heating unit relative to the heater support in this configuration, a similar effect of preventing openings in the film can be obtained.

[0398] Example 6

[0399] Next, Example 6 of the present invention will be described. The fixing device 2209 in Example 6 does not include a heat-conducting member, and a protrusion engaging with the recess of the film guide is provided on the substrate of the heater. In the following, similar reference numerals will be applied to the configuration of Example 6 that is similar to that of Example 5, and its description will be omitted.

[0400] Figure 32 This is a general cross-sectional view of the fixing device 2209 in this example, showing two sheets of recording material P, stapled with staples H, having toner images T, and being conveyed to the fixing device 2209. Furthermore, Figure 33A This is an exploded perspective view of the membrane unit 2220 used in the fixing device 2209. Figure 33B This is a perspective view of the heater 2222 using the protrusion 2222f.

[0401] The difference between the fixing device 2209 in Example 6 and the fixing device 2009 in Example 5 is that the fixing device 2209 in Example 6 does not include a heat-conducting member, and the heater 2222 includes a protrusion 2222f that engages with the recess 2221b of the film guide 2221. In other words, the heating unit in this example consists only of the heater 2222. Descriptions of other components of the image forming apparatus and fixing device similar to those in Example 5 will be omitted.

[0402] Next, we will use Figure 34A and 34B Describe the materials, manufacturing methods, etc. that constitute heater 2222 in this example. Figure 34A This is a cross-sectional view of heater 2222 when viewed from the longitudinal direction. Figure 34B This is a plan view of substrate 2222a when viewed from the thickness direction.

[0403] In this example, the substrate 2222a of the heater 2222 is made of metal, and the substrate 2222a only needs to contain at least one metal alloy as the main material. The heater 2222 includes an elongated plate-shaped substrate 2222a, a heating element 2222b that heats up in response to energization, an insulating layer 2222g that insulates the heating element 2222b from the substrate 2222a, and a protective layer 2222c that protects the heating element. Furthermore, the insulating layer 2222h is also disposed on the surface of the substrate 2222a opposite to the surface where the heating element 2222b is disposed to prevent warping of the substrate during manufacturing. In this example, the heating element 2222b is disposed on the substrate 2222a through the insulating layer 2222g.

[0404] The substrate 2222a has a protrusion 2222f, which is formed by folding the end of the substrate 2222a upstream in the transport direction. The protrusion 2222f is located upstream of the heating element 2222b and the insulating layer 2222h in the transport direction, and extends in a manner that protrudes further away from the pressure roller 2030 in the thickness direction of the substrate 2222a than the insulating layer 2222h. On the other hand, the recess 2221b provided at the film guide 2221 is recessed in the thickness direction of the substrate 2222a away from the pressure roller 2030 and engages with the protrusion 2222f. Note that in this example, the thickness direction of the substrate 2222a is substantially parallel to the pressure direction of the recording material P transported to the fixing device 2209.

[0405] As the material used in the metal substrate 2222a, stainless steel, nickel, copper, aluminum, or alloys containing such metals as the main material are suitable. Among these, stainless steel is most preferably used considering strength, heat resistance, and corrosion resistance. There are no particular restrictions on the type of stainless steel; it is only necessary to appropriately select the stainless steel by considering the necessary mechanical strength, the coefficient of linear expansion consistent with the formation of the insulation layer and heating element (which will be described below), the ease of obtaining sheet metal from the market, etc. In one example, martensitic and ferritic stainless steels in the chromium-based stainless steel (400 series) have relatively low coefficients of linear expansion among stainless steels and are therefore suitable for use because they are easy to form the insulation layer and heating element.

[0406] The thickness of substrate 2222a can be determined by considering strength, heat capacity, and heat dissipation performance. While a thinner substrate 2222a results in a smaller heat capacity, thus facilitating rapid start-up, excessive thickness may lead to problems such as deformation when the heating element 2222b is heated. Conversely, while a thicker substrate 2222a is advantageous in terms of deformation when the heating element 2222b is heated, excessive thickness is detrimental to rapid start-up due to its larger heat capacity. Considering the balance between mass production, cost, and performance, the preferred thickness of substrate 2222a is approximately 0.3 mm to 2.0 mm. In this example, substrate 2222a is a ferritic stainless steel substrate (SUS430:18Cr stainless steel) with a width of 10 mm, a length of 300 mm, and a thickness of 0.5 mm.

[0407] Next, insulating layers 2222g and 2222h will be described. While there are no particular limitations on the materials of insulating layers 2222g and 2222h, it is necessary to select materials with heat resistance considering the temperatures in actual use. As materials, glass or polyimide (PI) is preferred considering heat resistance, and from the perspective of heat resistance, etc., if glass is used, a powder material can be appropriately selected without compromising the characteristics of the invention. Furthermore, thermally conductive fillers with insulating properties can be added as needed. Insulating layers 2222g and 2222h can be formed from the same or different materials without any problem. Regarding layer thickness, insulating layers 2222g and 2222h can have the same or different thicknesses. Generally, it is preferred that the heater used in the image forming apparatus has a dielectric strength of approximately 1.5 kV, and in order to obtain a dielectric strength performance of 1.5 kV between the heating element 2222b and the substrate 2222a, it is only necessary to ensure the layer thickness of insulating layer 2222g according to the materials. While there are no particular limitations on the methods used to form insulating layers 2222g and 2222h, in one example, insulating layers 2222g and 2222h can be smoothly formed by methods such as screen printing. When forming a glass or polyimide (PI) insulating layer on substrate 2222a, it is necessary to appropriately adjust the linear expansion coefficients of the substrate and insulating layer materials so that cracking or peeling does not occur in the insulating layer due to differences in the linear expansion coefficients of the materials.

[0408] In this example, an insulating glass paste is applied to the aforementioned substrate 2222a made of stainless steel by screen printing. The resulting article is dried at 180°C and sintered at 850°C to form an insulating layer 2222g with a thickness of 60 μm and an insulating layer 2222h with a thickness of 120 μm. Since the method for forming the heating element 2222b, the power supply electrode 2222d, the conductive pattern 2222e, and the protective layer 2222c on the substrate 2222a having insulating layers 2222g and 2222h is similar to the method in Example 5, its description will be omitted.

[0409] Will use Figure 32 The effects and advantages of this example are described below. In this example, the protrusion 2222f of the heater 2222 is inserted into the recess 2221b of the membrane guide 2221. Therefore, even if a force along direction c is applied to the heater 2222, the relative movement of the heater 2222 with respect to the membrane guide 2221 downstream in the conveying direction is restricted. Therefore, on the upstream side of the heater 2222 along the conveying direction, no gap for staple H to enter is generated between the heater 2222 and the heater support 2221a, and even when conveying recording material with some kind of protrusion (e.g., staple H) according to the invention, openings in the membrane 2023 can be prevented.

[0410] As a result of paper feeding tests similar to those in Example 5 using the fixing device 2209 in this example, there were no openings in the film 2023, and satisfactory fixed images were obtained on all evaluated papers. Furthermore, compared to Example 5, since no heat-conducting member 2051 is provided in this example, no additional heat capacity is added, and the preheating time of the fixing device 2209 can be improved.

[0411] It should be noted that the present invention is not limited to the above configuration, and variations may employ, such as Figure 35A The heater 2223 shown is configured such that the protrusion 2223f is disposed throughout the entire sheet passage area, rather than throughout the entire longitudinal direction of the heater 2223. In another variation, a configuration such as... Figure 35BThe heater 2224 shown has a configuration where multiple protrusions 2224f with shorter lengths in the longitudinal direction are provided in the sheet passage area. The heater 2223 includes protrusions 2223f provided throughout the entire sheet passage area, thus providing sufficient strength relative to the forces exerted by the rotation of the film 2023. On the other hand, the heater 2224 includes protrusions 2224f with shorter lengths in the longitudinal direction at three locations in the sheet passage area, therefore the heater 2224 is less strong than the heater 2223. However, from the perspective of minimizing the increase in heat capacity, the heater 2224, with its smaller volume, is worse than the heater 2223. In other words, the necessary configuration can be appropriately selected by considering factors such as the pressure of the fixing device, the required strength based on the film rotation speed, the preheating time required by the image forming equipment, and the manufacturing cost of the heating unit.

[0412] Although this example uses a configuration where the protrusion 2222f is located upstream of the heater 2222 along the conveying direction, other configurations are also conceivable, such as a configuration where the protrusion is located downstream of the conveying direction, or a configuration where protrusions are provided on both the upstream and downstream sides. Alternatively, a variant example could be given where the protrusion extends towards the pressure roller in the pressing direction instead of away from the pressure roller. Furthermore, the protrusion need not extend perpendicular to the surface of the recording material, and the protrusion can extend at a predetermined angle relative to the pressing direction, as long as the movement of the heater downstream of the conveying direction is limited by this configuration.

[0413] Furthermore, in other variations, it is conceivable to have a configuration where a metal substrate has a heat-conducting member including protrusions, or a ceramic substrate has protrusions, etc. Figure 36 and Figure 16 The description describes a variant of a metal substrate 2522a having a heat-conducting member 2551 including a protrusion 2551a. In the following description, similar reference numerals will be applied to configurations similar to Example 5 in the variant, and their descriptions will be omitted.

[0414] Figure 36 This is a general cross-sectional view of the fixing device 2509 according to a variant example. Similar to Example 5, the fixing device 2509 is configured such that a heat-conducting member 2551, including a protrusion 2551a, is engaged with a heater 2522. Once the heater 2522 is attached to the heater attachment portion 2521a of the film guide 2521, the protrusion 2551a of the heat-conducting member 2551 engages with the recess 2521b of the film guide 2521, and the relative movement of the heater 2522 with respect to the film guide 2521 in the transport direction is restricted.

[0415] Figure 37A This is a cross-sectional view of heater 2522 when viewed from the longitudinal direction. Figure 37B This is a plan view of the heater 2522 as viewed from the thickness direction of the substrate 2522a. In this example, the substrate 2522a of the heater 2522 only needs to be made of metal and contain at least one metal alloy as the main material. The heater 2522 includes an elongated plate-shaped substrate 2522a, a heating element 2522b that heats up in response to energization, an insulating layer 2522g that insulates the heating element 2522b from the substrate 2522a, and a protective layer 2522c that protects the heating element. Furthermore, to prevent substrate warping during manufacturing, an insulating layer 2522h is also provided on the surface of the substrate 2522a opposite to the surface where the heating element 2522b is located. In this example, the heating element 2522b is disposed on the substrate 2522a through the insulating layer 2522g.

[0416] Example 7

[0417] Next, Example 7 according to the invention will be described. In the fixing device 2309 of Example 7, the film guide 2321 includes a protrusion 2321b, and a recess 2351a provided at the heat-conducting member 2351 of the heating unit 2350 engages with the protrusion 2321b. In the following, similar reference numerals will be applied to the configuration of Example 7 that is similar to that of Example 5, and its description will be omitted.

[0418] Figure 38 This is a general cross-sectional view of the fixing device 2309 in this example, showing two sheets of recording material P with toner images T, stapled by staples H of a stapler, and being conveyed to the fixing device 2309. In this example, the heating unit 2350 consists of a heater 2022 and a heat-conducting member 2351 and has a similar configuration to Example 5.

[0419] The heat-conducting member 2351 in this example includes a recess 2351a. The recess 2351a is located within the heating unit 2350, upstream of the heater 2022 in the conveying direction, and is recessed toward the pressure roller 2030 in the thickness direction of the substrate 2022a. On the other hand, a protrusion 2321b provided at the film guide 2321 extends toward the pressure roller 2030 in the thickness direction of the substrate 2022a and engages with the recess 2351a. In the heat-conducting member 2351 of this example, as... Figure 39A As shown, the recess 2351a is formed over the entire area in the longitudinal direction. Note that in this example, the thickness direction of the substrate 2022a is substantially parallel to the pressure direction of the recording material P delivered to the fixing device 2309.

[0420] Due to the engagement between the recess 2351a and the protrusion 2321b, even when a force along direction c acts on the heating unit 2350, the relative movement of the heating unit 2350 relative to the membrane guide 2321 in the downstream side of the conveying direction is restricted. Therefore, according to the present invention, on the upstream side of the heating unit 2350 along the conveying direction, no gap for staple H to enter is generated between the heating unit 2350 and the heater support 2321a, and even when conveying recording material with some kind of protrusion (e.g., staple H), openings in the membrane 2023 can be prevented.

[0421] As a result of performing a paper feeding test similar to that in Example 5 using the fixing device 2309 in this example, no openings were found in the film 2023, and satisfactory fixed images were obtained on all evaluated papers. Furthermore, compared to the heat-conducting member 2051 in Example 5, the heat-conducting member 2351 in this example has a smaller volume and smaller heat capacity because it has a recess 2351a instead of a protrusion. Therefore, compared to Example 5, the preheating time of the fixing device can be improved due to the reduced heat capacity of the heat-conducting member in this example.

[0422] It should be noted that the present invention is not limited to the above configuration, and in variations, for example, as shown above. Figure 39B The configuration shown is similar to that of the heat-conducting member 2352, wherein the recess 2352a is provided over the entire area through which the sheet passes, rather than over the entire longitudinal region of the heat-conducting member 2352. In another variation, a configuration such as... Figure 39C The heat-conducting member 2353 shown has a configuration in which multiple recesses 2353a with shorter lengths along the longitudinal direction are provided in the sheet passage area. Since the heat-conducting member 2352 includes recesses 2352a provided throughout the entire sheet passage area, it can obtain sufficient strength relative to the forces exerted due to the rotation of the membrane 2023. On the other hand, the heat-conducting member 2353 includes recesses 2353a with shorter lengths along the longitudinal direction at three locations in the sheet passage area, therefore the heat-conducting member 235 is not as strong as the heat-conducting member 2352. However, from the perspective of minimizing the increase in heat capacity, the heat-conducting member 2353 with its smaller volume is worse than the heat-conducting member 2352. Furthermore, when the recesses are machined by cutting, the heat-conducting member 2353 including recesses with shorter lengths is superior to the heat-conducting members 2351 and 2352 in terms of processing cost. In other words, the necessary configuration can be appropriately selected by considering factors such as the pressure of the fixing unit, the required strength based on the rotation speed of the film, the preheating time required for the image forming equipment, and the manufacturing cost of the heating unit.

[0423] As other variations, various configurations can be envisioned, such as a configuration in which the recess is located on the downstream side of the conveying direction relative to the heater, a configuration in which the recess is provided on both the upstream and downstream sides, and a configuration in which the substrate is made of metal instead of ceramic, etc.

[0424] Example 8

[0425] Next, Example 8 according to the present invention will be described. Similar to Example 6, the fixing device 2409 in Example 8 does not include a heat-conducting member. Furthermore, in the fixing device 2409 of Example 8, the film guide 2421 includes a protrusion 2421b, and a recess 2422d provided on the substrate 2422a of the heater 2422 engages with the protrusion 2421b. In the following, similar reference numerals will be applied to the configuration of Example 8 that is similar to that of Example 5, and its description will be omitted.

[0426] Figure 40 This is a general cross-sectional view of the fixing device 2409 in this example, showing two sheets of recording material P with toner images T, stapled by stapler H, and conveyed to the fixing device 2409. In this example, the heating unit does not include heat-conducting components and consists only of heater 2422.

[0427] The heater 2422 in this example includes a metal substrate 2422a, a heating element 2422b, a protective layer 2422c, and insulating layers 2422e and 2422f. Furthermore, a recess 2422d is formed near the upstream end of the substrate 2422a in the transport direction and further upstream of the heating element 2422b and insulating layer 2422f along the transport direction. The recess 2422d is recessed toward the pressure roller 2030 in the pressing direction (thickness direction of the substrate 2422a). On the other hand, a protrusion 2421b provided at the film guide 2421 extends toward the pressure roller 2030 along the pressing direction and engages with the recess 2422d. In the heater 2422 of this example, as... Figure 41A As shown, the recess 2422d is formed over the entire range in the longitudinal direction.

[0428] Due to the engagement between the recess 2422d and the protrusion 2421b, even when a force along direction c acts on the heater 2422, the relative movement of the heater 2422 with respect to the membrane guide 2421 downstream in the conveying direction is restricted. Therefore, according to the present invention, on the upstream side of the heater 2422 along the conveying direction, no gap for staple H to enter is generated between the heater 2422 and the heater support 2421a, and even when conveying recording material with some kind of protrusion (e.g., staple H), openings in the membrane 2023 can be prevented.

[0429] As a result of performing a paper feeding test similar to that in Example 5 using the fixing device 2409 in this example, no openings were found in the film 2023, and satisfactory fixed images were obtained on all evaluated papers. Furthermore, compared to the heater 2222 in Example 6, the heater 2422 in this example has a smaller volume and smaller heat capacity because its substrate 2422a has a recess 2422d instead of a protrusion. Therefore, compared to Example 6, the reduced heat capacity of the heater in this example improves the preheating time of the fixing device.

[0430] It should be noted that the present invention is not limited to the above configuration, and in variations, for example, it may also employ... Figure 41B The heater 2423 shown is configured such that the recess 2423d is provided throughout the entire sheet passage area rather than throughout the entire longitudinal direction of the heater 2423. In another variation, a configuration such as... Figure 41C The heater 2424 shown has a configuration where multiple recesses 2424d with shorter lengths along the longitudinal direction are provided in the sheet passage area. The heater 2423 includes recesses 2423d provided throughout the entire sheet passage area, thus achieving sufficient strength relative to the forces exerted due to the rotation of the film 2023. On the other hand, the heater 2424 includes recesses 2424d with shorter lengths along the longitudinal direction at three locations in the sheet passage area, therefore the heater 2424 is less strong than the heater 2423. However, from the perspective of minimizing the increase in heat capacity, the heater 2424, with its smaller volume, is worse than the heater 2423. Furthermore, when the recesses are machined by cutting, the heater 2424, including recesses with shorter lengths, is superior to the heaters 2422 and 2423 in terms of processing cost. In other words, the necessary configuration can be appropriately selected considering factors such as the pressure of the fixing device, the required strength based on the film rotation speed, the preheating time required by the image forming equipment, and the manufacturing cost of the heating unit.

[0431] Other variations include a configuration where the recess is located downstream of the heating element in the transport direction, a configuration where recesses are provided on both the upstream and downstream sides, and a configuration where the substrate is made of ceramic instead of metal. Furthermore, multiple examples can be combined, and various configurations can be envisioned, such as a configuration where both protrusions and recesses are provided at each of the heating unit and the film guide.

[0432] Examples of configurations or concepts disclosed in the foregoing embodiments will be described below. However, these are merely examples, and the disclosure of the foregoing embodiments is not limited to the configurations or concepts described below.

[0433] Configure B1

[0434] A heating device for heating recording materials using a clamping part, comprising:

[0435] Rotatable tubular membrane;

[0436] A heating unit is disposed within the internal space of the membrane and heats the membrane;

[0437] A support member that holds the heating unit in contact with the inner peripheral surface of the membrane and guides the rotation of the membrane; and

[0438] A clamping portion is formed between the rotating body and the membrane.

[0439] Either the heating unit or the support member includes a joint located in the sheet passage area in the width direction of the recording material orthogonal to the transport direction of the recording material, and the other of the heating unit and the support member includes a joined portion that engages with the joint.

[0440] The position of the heating unit relative to the support member in the conveying direction is determined by the joining of the joint and the joined part.

[0441] In the conveying direction, the joint and the joined part are located further downstream of the inlet of the clamping part and further upstream of the outlet of the clamping part.

[0442] Configure B2

[0443] According to the heating device described in configuration B1, it further includes:

[0444] A retaining member is located outside the sheet passage area and holds the heating unit at both ends in the width direction, thereby restricting the relative movement of the heating unit relative to the supporting member.

[0445] Configure B3

[0446] In the heating device described according to configuration B1 or B2

[0447] The joint is a convex part.

[0448] The joined portion is a recess, and

[0449] The protrusions in a direction orthogonal to the conveying direction, so that when viewed along the conveying direction, the protrusion overlaps with the concave portion.

[0450] Configure B4

[0451] In the heating device according to any of configurations B1 to B3, the joint is located at the center of the sheet passage area along the width direction.

[0452] Configure B5

[0453] In the heating device according to any of the configurations B1 to B4, a plurality of joints are provided in the sheet passage area.

[0454] Configuration B6

[0455] In the heating device according to any of configurations B1 to B5, the heating unit includes a heater and a heat-conducting member, the heat-conducting member being in contact with the inner peripheral surface of the membrane and transferring heat from the heater to the membrane.

[0456] Configure B7

[0457] In the heating device according to configuration B6, when viewed along the pressurization direction orthogonal to the conveying direction and the width direction, the heat-conducting member is joined to the heater to cover the entire area of ​​the heater in the transverse direction.

[0458] Configure B8

[0459] In the heating device according to configuration B6 or B7

[0460] The joint is located in the heat-conducting component, and

[0461] The joint is located in the support member.

[0462] Configure B9

[0463] In the heating device according to configuration B8, the joint is provided at the upstream end of the conveying direction of the heat-conducting member and extends away from the rotating body in a direction orthogonal to the surface of the conveyed recording material.

[0464] Configure B10

[0465] In the heating device according to configuration B8 or B9

[0466] The heat-conducting component is a slender plate component, and

[0467] The joint is formed by a folded plate component.

[0468] Configure B11

[0469] In the heating device according to configuration B10, the heater includes a substrate made of metal.

[0470] Configure B12

[0471] In the heating device according to configuration B6

[0472] The joint is located in the supporting member, and

[0473] The joint is located in the heat-conducting component.

[0474] Configure B13

[0475] In the heating device according to configuration B12

[0476] The joint extends towards the side closer to the rotating body in a direction orthogonal to the surface of the conveyed recording material, and

[0477] The joint is located at the upstream end of the heat-conducting component in the conveying direction.

[0478] Configure B14

[0479] In the heating device according to any of the configurations B1 to B5, the heating unit includes a substrate, a heating element disposed on the substrate, and a protective layer covering the heating element, and the heating unit is a heater in which the heating element heats up in response to energization.

[0480] Configure B15

[0481] In the heating device according to configuration B14

[0482] The joint is located in the heater, and

[0483] The joint is located in the support member.

[0484] Configure B16

[0485] In the heating device according to configuration B15, the joint is provided at the upstream end of the substrate in the transport direction and extends away from the rotating body in a direction orthogonal to the surface of the transported recording material.

[0486] B17 configuration

[0487] In the heating device according to configuration B15 or B16

[0488] The substrate is a slender plate component, and

[0489] The joint is formed by a folded plate component.

[0490] B18 configuration

[0491] In the heating device according to configuration B14

[0492] The joint is located in the supporting member, and

[0493] The joint is located in the heater.

[0494] Configure B19

[0495] In the heating device according to configuration B18

[0496] The joint extends towards the side closer to the rotating body in a direction orthogonal to the surface of the conveyed recording material, and

[0497] The joint is located at the upstream end of the substrate in the transport direction.

[0498] Configure B20

[0499] An image forming apparatus, comprising:

[0500] An image forming unit that forms an image on a recording material; and

[0501] According to any of the configurations B1 to B19, the heating device fixes the image formed on the recording material onto the recording material.

[0502] Furthermore, in heating devices consisting of heaters, films, pressure rollers, etc., there exists a configuration in which the movement of the heater is restricted by bending the metal substrate of the heater and engaging the heater with a heater support, thereby reducing the number of components such as heater clamps. In such a configuration, if the heating element and the electrode for supplying power to the heating element are arranged adjacent to each other in the longitudinal direction on the same plane of the substrate, miniaturization of the heater cannot be achieved, and therefore miniaturization of the heating device and the image forming apparatus is also impossible. Therefore, a heater capable of reducing the size of the heating device will be described below.

[0503] Example 9

[0504] (1) Image forming apparatus 3100

[0505] Figure 42 This is a general configuration diagram of an image forming apparatus 3100 using electrophotographic recording technology according to Example 9. First, the configuration and operation of the image forming apparatus 3100 will be described.

[0506] The image forming operation performed by the image forming unit of the image forming apparatus 3100 will be described. If the image forming apparatus 3100 receives a print command from an external device, the scanner unit 3003 emits a laser L to the photosensitive member 3001 based on image information. The photosensitive member 3001, charged with a predetermined polarity by the charging roller 3002, is scanned by the laser L, and an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive member 3001. Subsequently, the developing apparatus 3004 supplies toner to the photosensitive member 3001, and a toner image corresponding to the image information is formed on the photosensitive member 3001. By rotating the photosensitive member 3001 in the direction of arrow R, the toner image on the photosensitive member 3001 moves to the transfer position formed by the photosensitive member 3001 and the transfer roller 3005, and is transferred to the recording material P fed from the cartridge 3006 by the pickup roller 3007. The surface of the photosensitive member 3001 that has passed the transfer position is cleaned using a cleaner 3008.

[0507] The fixing device 3009, which serves as the fixing unit, performs fixing treatment on the recording material P, to which a toner image is transferred at the image forming unit, using heat and pressure. Subsequently, the recording material P is discharged by the discharge roller 3010 to the discharge tray 3011.

[0508] (2) Fixing device 3009

[0509] Next, the configuration and operation of the fixing device 3009 will be described. In this example, the tensionless film heating system fixing device 3009 is used as an example of a heating device. The fixing device 3009 in this example is a device in which an annular strip (or cylindrical) heat-resistant film is used, at least a portion of the periphery of which is always kept tensionless (in a state where no tension is applied to it), and the film is driven to rotate by the rotational driving force of the pressure member.

[0510] Figure 43 This is a general cross-sectional view of the fixing device 3009 in this example, showing the state in which recording material P, including the toner image, is fed into the fixing device 3009. Furthermore, Figure 44 This is an exploded perspective view of the heater support unit 3020 and its surrounding components. Figure 45 This is a schematic front view of the fixing device 3009, in which a portion of the membrane 3023 is not shown, so as to show the internal space of the membrane 3023.

[0511] Reference Figure 43The configuration of the fixing device 3009 is described. In this example, the fixing device 3009 includes a tubular membrane 3023 serving as a first rotating body, a heater 3022 heating the membrane 3023 within its internal space, and a pressure roller 3030 serving as a second rotating body, which forms a clamping portion N with the heater 3022 across the membrane 3023. The fixing device 3009 also includes a heater support 3021 supporting the heater 3022 and guiding the rotation of the membrane 3023, and a reinforcing member 3024 reinforcing the heater support 3021. The membrane 3023 is driven to rotate in the direction of arrow a by receiving power from a motor (not shown) and rotating in the direction of arrow b via the pressure roller 3030.

[0512] Membrane 3023 is a tubular rotating body. The thickness of membrane 3023 is preferably at least about 20 μm and not more than 100 μm to ensure satisfactory thermal conductivity. When membrane 3023 is a single-layer membrane, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), PPS, etc., are preferably used as the base layer. In the case of a composite membrane, materials such as polyimide (PI), polyamide-imide (PAI), polyether ether ketone (PEEK), or polyether sulfone (PES) are preferably used as the base layer. Furthermore, as a release layer coated on the surface of the base layer, materials such as PTFE, PFA, tetrafluoroethylene-perfluoroalkyl vinyl ether (FEP) are preferably used to configure the composite membrane. Additionally, membranes obtained by using pure metals or alloys with high thermal conductivity such as SUS, Al, Ni, Cu, Zn, etc., in the base layer and performing the aforementioned coating treatment on the release layer, or by coating with a fluoropolymer tube, are also suitable.

[0513] The membrane 3023 in this example is a composite membrane, wherein the base layer is made of PI with a thickness of 60 μm and coated with a release layer made of PFA with a thickness of 12 μm to achieve a balance between release layer wear due to paper feeding and thermal conductivity. The axial direction of the cylindrical shape of membrane 3023 will be referred to as the longitudinal direction below.

[0514] The heater holder 3021 is a support member disposed within the internal space of the membrane 3023 and supporting the heater 3022. The membrane 3023 is loosely fitted onto the heater holder 3021, and the heater holder 3021 also has a guiding function that guides the rotation of the membrane 3023 while maintaining sliding contact with the inner circumferential surface of the membrane 3023. For the heater holder 3021, a high heat-resistant resin, such as polyimide, polyamide-imide, PEEK, PPS, or liquid crystal polymer, or a composite material of such resin and ceramics, metals, glass, etc., can be suitably used. Liquid crystal polymers are particularly preferred due to the following advantages: First, due to their high heat resistance temperature, a high degree of freedom in setting the heater's set temperature is possible. Furthermore, satisfactory productivity is achieved and large-scale production is possible because it can be molded. Additionally, due to its excellent dimensional stability, the pressure on the pressurizing member can be uniformized and the paper feeding performance stabilized. In this example, a composite material obtained by incorporating glass fiber into the liquid crystal polymer is used.

[0515] The heater 3022, used as a heating element, includes an elongated substrate (containing metal as the main material), a heating element that heats up in response to electricity, an insulating layer that insulates the heating element from the substrate, and a glass coating that protects the heating element. The detailed configuration of the heater 3022 will be described later.

[0516] The thermistor 3025, serving as a temperature sensing component, abuts against the surface of the heater 3022, which abuts against the heater support 3021. The energization of the heating resistor is controlled based on the temperature detected by the thermistor 3025, thus managing the temperatures of the heater 3022 and the membrane 3023. In other words, the temperature change of the membrane 3023 via the heater 3022 is detected by the thermistor 3025.

[0517] The pressure roller 3030 includes a core metal made of a material such as iron or aluminum, an elastic layer made of a material such as silicone rubber, and a release layer made of a material such as PFA. Drive gear 3033 (see...) Figure 45 The core metal is attached to one end of the pressure roller 3030 in the longitudinal direction, and the drive gear 3033 receives the rotational driving force from the drive device (not shown), and the pressure roller 3030 rotates.

[0518] The reinforcing member 3024 is made of a metal such as iron and maintains its strength to prevent significant deformation even under pressure when the heater support 3021 is pressed against the pressure roller 3030. The heater 3022 is pressed against the pressure roller 3030 by the pressurizing device described below via the heater support 3021 and the reinforcing member 3024. The area where the pressure roller 3030 and the membrane 3023 come into close contact with each other due to pressure is the clamping part N.

[0519] Next, we will refer to Figure 44 The perspective view depicts details of the heater support unit 3020 and surrounding components, including a heater 3022. The heater 3022 is held by the heater support 3021 and positioned by a heater clamp 3028 located at an end of the heater support 3021 in the longitudinal direction. The heater clamp 3028 is formed of a C-shaped metal plate and utilizes its elasticity to hold the end of the heater 3022 at the heater support 3021. In this example, the heater support unit 3020 consists of the heater support 3021, the heater 3022, and the heater clamp 3028.

[0520] The heater support 3021 has a generally groove-shaped cross-section orthogonal to the longitudinal direction, and the reinforcing member 3024 is fitted into the interior of the groove. A heater receiving groove is located on the side of the heater support 3021 facing the pressure roller 3030, and the heater 3022 is fitted into the heater receiving groove and positioned as desired. A membrane 3023 is fitted onto the outside of the heater support 3021, where the aforementioned components are assembled, with a certain allowance around its perimeter. The reinforcing member 3024 extends outward from both ends of the membrane 3023 in the longitudinal direction, and flanges 3026 are fitted to both ends of the reinforcing member 3024.

[0521] Next, we will refer to Figure 45 The configuration of the fixing unit 3009 is described in further detail. Figure 45 In the diagram, a portion of the membrane 3023 is not shown, so that the heater support 3021 and heater 3022 disposed within the interior space of the membrane 3023 can be seen. Flanges 3026 located at both ends of the membrane 3023 restrict the longitudinal movement of the rotating membrane 3023.

[0522] The heater support unit 3020 is positioned facing the pressure roller 3030 and supported by the top plate side housing 3041 via flanges 3026, etc. The heater support unit 3020 is supported by the top plate side housing 3041 to allow it to move freely in the pressure direction, and its movement in the longitudinal direction is restricted by the side surface side housing 3042. A pressure spring 3045 is attached to the top plate side housing 3041 of the fixing device 3009 in a compressed state. The pressure of the pressure spring 3045 is received at the longitudinal end of the reinforcing member 3024 via flanges 3026. The pressure of the pressure spring 3045 pushes the reinforcing member 3024 towards the pressure roller 3030, presses the heater support unit 3020 towards the pressure roller 3030, and forms a clamping portion N between the film 3023 and the pressure roller 3030.

[0523] The bearing member 3031 is configured to axially support the metal core of the pressure roller 3030 and receive the extrusion force from the heater support unit 3020 via the pressure roller 3030. To rotatably support the metal core of the pressure roller 3030, which is heated to a relatively high temperature, the bearing member 3031 is made of a material with heat resistance and excellent sliding properties. The bearing member 3031 is attached to the bottom housing 3043 of the fixing unit 3009.

[0524] (3) Heater 3022

[0525] Next, the heater 3022 in this example will be described in detail. First, we will use... Figure 46 Describe the materials and manufacturing methods that constitute the heater 3022.

[0526] Figure 46 This is a cross-sectional view of heater 3022. Heater 3022 includes an elongated substrate 3221 (containing metal as the main material), a heating element 3223 that heats up in response to energization, an insulating layer 3222 that insulates the heating element 3223 from the substrate 3221, and a protective layer 3224 that protects the heating element 3223. Furthermore, to prevent warping of the substrate during manufacturing, an insulating layer 3225 is also provided on the surface of substrate 3221 opposite to the surface where the heating element 3223 is located. The heating element 3223 is disposed on the surface of substrate 3221 facing the pressure roller 3030.

[0527] As the metallic material used for the substrate 3221, stainless steel, nickel, copper, aluminum, or alloys containing such metals as the main material are suitable. Among these, stainless steel is most preferably used considering strength, heat resistance, and corrosion resistance. There are no particular restrictions on the type of stainless steel; it is appropriate to select the stainless steel based on factors such as the necessary mechanical strength, the coefficient of linear expansion consistent with the formation of the insulation layer 3222 and the heating element 3223, and the availability of sheet metal in the market. In one example, martensitic and ferritic stainless steels from the chromium-based stainless steel (400 series) are suitable because they have relatively low coefficients of linear expansion and are easy to use to form the insulation layer and heating element.

[0528] The thickness of the substrate 3221 can be determined by considering strength, heat capacity, and heat dissipation performance. While a thinner substrate results in a smaller heat capacity, thus facilitating rapid start-up, excessive thickness may lead to problems such as deformation during the thermoforming of the heating element. Conversely, while a thicker substrate is advantageous in terms of deformation during the thermoforming of the heating element, excessive thickness is detrimental to rapid start-up due to its larger heat capacity. Considering the balance between mass production, cost, and performance, the preferred thickness of the substrate 3221 is between 0.3 mm and 2.0 mm.

[0529] In this example, substrate 3221 is a ferritic stainless steel substrate (SUS430:18Cr stainless steel) with a width of 20 mm, a length of 376 mm, and a thickness of 0.3 mm. The shape of substrate 3221, which constitutes the features of this invention, will be described in detail.

[0530] While there are no particular limitations on the materials of insulating layers 3222 and 3225, it is necessary to select materials with heat resistance considering the temperatures in actual use. As materials, glass or polyimide (PI) is preferred considering heat resistance, and in the case of glass, specific powder materials can be appropriately selected without compromising the properties of the invention. Thermally conductive fillers with insulating properties can be added as needed. The materials and thicknesses of insulating layers 3222 and 3225 can be similar to each other, or they can be changed as needed.

[0531] Typically, the heaters used in image forming apparatus preferably have a dielectric strength of about 1.5 kV. Therefore, in order to obtain a dielectric strength of 1.5 kV between the heating element 3223 and the substrate 3221, it is only necessary to ensure the film thickness of the insulating layer 3222 according to the material.

[0532] While there are no particular limitations on the methods used to form the insulating layers 3222 and 3225 and the heating element 3223 (described below), in one example, they can be smoothly formed by screen printing. They can also be formed by methods such as screen printing, simply by forming them on the curved portion of the heater, which will be described below. When the glass or polyimide (PI) insulating layer is formed on the substrate 3221, the linear expansion coefficients of the substrate and the insulating layer materials need to be appropriately adjusted so that cracking or peeling does not occur in the insulating layer due to differences in the linear expansion coefficients of the materials.

[0533] In this example, an insulating glass paste is applied to a stainless steel substrate 3221 by screen printing. The resulting article is dried at 180°C and sintered at 850°C to form insulating layers 3222 and 3225. The sintered insulating layers have a thickness of 25 μm and are formed on both surfaces of the substrate 3221.

[0534] A heating element 3223 is obtained by printing a thermistor paste, which is a mixture of conductive component (A), glass component (B), and organic binder component (C), onto an insulating layer 3222 and then sintering the resulting article. When the heating resistor paste is sintered, the organic binder component (C) burns and disappears, while components (A) and (B) remain, thus forming a heating element 3223 containing both conductive and glass components. Here, silver-palladium (Ag·Pd), ruthenium oxide (RuO2), etc., are used individually or in combination as the conductive component (A), and a sheet resistance value of 0.1 [Ω / □] to 100 [kΩ / □] is preferably obtained. Furthermore, if other materials are included in addition to the aforementioned components (A) to (C), there is no problem as long as the content is very small and does not impair the performance of the present invention.

[0535] The power supply electrode 3226 and the conductive pattern 3227 contain silver (Ag), platinum (Pt), gold (Au), silver-platinum (Ag·Pt) alloy, silver-palladium (Ag·Pd) alloy, etc., as main components. Similar to the heating resistor paste, the power supply electrode 3226 and the conductive pattern 3227 are formed by printing a paste obtained by mixing conductive component (A), glass component (B), and organic binder component (C) onto the insulating layer 3222 and sintering the paste.

[0536] The power supply electrode 3226 and the conductive pattern 3227, which serves as a conductor, are configured to supply power to the heating element 3223, and the resistance relative to the heating element 3223 is set sufficiently low. Here, for the aforementioned heating resistor paste, power supply electrode, and conductive pattern paste, it is necessary to select materials that soften and melt at a temperature lower than the melting point of the substrate 3221, and considering the temperature in actual use, it is necessary to select materials with heat resistance.

[0537] In this example, a resistance thermal paste obtained by using silver-palladium (Ag·Pd) as a conductive component and additionally combining a glass component and an organic binder component was used, as well as a paste for power supply electrodes and conductive patterns obtained by using silver as a conductive component and additionally combining a glass component and an organic binder component. Each paste was applied to a substrate 3221 made of stainless steel, on which insulating layers 3222 and 3225 were formed by screen printing. The resulting article was then dried at 180°C and sintered at 850°C to form a heating element 3223, a power supply electrode 3226, and a conductive pattern 3227. The sintered heating element 3223 had a thickness of 15 μm, a length of 312 mm, and a width of 1.1 mm.

[0538] A protective layer 3224 is configured to cover the heating element 3223 and the conductive pattern 3227. With the heating elements 3223 positioned on the side in contact with the membrane 3023, the protective layer 3224 is configured to ensure electrical insulation between the heating element 3223 and the membrane 3023, and to ensure the slidability of both. As a material, glass or polyimide (PI) is preferred considering heat resistance, and thermally conductive fillers with insulating properties may be added as needed.

[0539] In this example, a protective glass paste is prepared and applied to the heating element 3223 and the conductive pattern 3227 by screen printing. The resulting material is dried at 180°C and sintered at 850°C to form a protective layer 3224. The thickness of the sintered protective layer 3224 is 30 μm.

[0540] Next, we will use Figure 47 The shape of the heater 3022, which is a feature of the present invention, is described. Figure 47 This is a perspective view showing the configuration of the heater 3022 in this example. The substrate 3221 of the heater 3022 in this example is formed by bending in the longitudinal direction and folding at 90° at the end in the longitudinal direction. A heating element 3223 and a power supply electrode 3226 are disposed on the substrate 3221, and the substrate 3221 includes a heating element placement portion 3221a, an electrode placement portion 3221b, and a bent portion 3221c.

[0541] The heating element placement section 3221a extends linearly in a direction orthogonal to the transport direction of the recording material P at the clamping section N, and is provided with two heating elements 3223. Furthermore, the heating element placement section 3221a forms the clamping section N with the pressure roller 3030 via the membrane 3023. The bending section 3221c extends in a manner that bends from one end in the longitudinal direction of the heating element placement section 3221a toward the thickness direction of the heating element placement section 3221a. The electrode placement section 3221b extends perpendicular to the heating element placement section 3221a and is provided with a power supply electrode 3226 to supply power for energizing the heating elements 3223. Note that in the fixing apparatus 3009 of this example, the thickness direction of the heating element placement section 3221a is parallel to the pressure direction of the recording material P. Furthermore, the orthogonality, perpendicularity, and parallelism described herein are not necessarily strictly orthogonal, perpendicular, and parallel, as long as the function of the image forming apparatus can be achieved.

[0542] In other words, in this example, the heating element 3223 and the power supply electrode 3226 are not in the same plane, and the conductive pattern 3227 extends from the heating element mounting portion 3221a to the electrode mounting portion 3221b via the bending portion 3221c. In other words, the characteristic of this invention is that the substrate 3221 is bent so that the planar heating element mounting portion 3221a and the electrode mounting portion 3221b extend in a manner that intersects each other perpendicularly.

[0543] It should be noted that the aforementioned bending does not necessarily mean forming the substrate by performing a bending process on the sheet material. For example, even if a configuration of substrates with similar shapes is provided by means such as casting or cutting, the effect of miniaturization of the heating device, which will be described below, can be expected. In other words, although bending is used to form the substrate in this example, the method for forming the substrate in this invention is not limited to plastic processing, as a processing method that can be expected to facilitate processing and achieve the effect of enhancing the strength of the substrate through plastic processing.

[0544] (4) Methods for maintaining heater 3022 and methods for supplying power to it

[0545] Subsequently, will be used Figure 48 and Figure 49 The heater support unit 3020 is described in detail, consisting of heater bracket 3021, heater 3022 and heater clamp 3028. Figure 48 This is a perspective view showing one end of the heater support unit 3020 in this example with a power supply contact 3211 in the longitudinal direction. Figure 49 This is a perspective view showing the heater support unit 3020 in the state where the heater 3022 and the heater support 3021 are engaged.

[0546] In this example, the heater bracket 3021 includes a holding portion 3021a at its longitudinal end (the electrode setting portion 3221b of the heater 3022 is inserted into this holding portion 3021a), and is provided with a power supply contact 3211 serving as a power supply device provided in the holding portion 3021a. The heater 3022 is held by the heater bracket 3021 with the portion including the electrode setting portion 3221b provided with the power supply electrode 3226 inserted into the holding portion 3021a of the heater bracket 3021. In other words, the electrode setting portion 3221b is disposed on the side away from the clamping portion N relative to the heating element setting portion 3221a in the thickness direction. By inserting the electrode setting portion 3221b of the heater 3022 into the holding portion 3021a of the heater bracket 3021, the power supply electrode 3226 on the electrode setting portion 3221b and the power supply contact 3211 in the heater bracket come into contact with each other under abutment pressure.

[0547] The power supply contact 3211 in the heater bracket 3021 is electrically connected to the wiring harness 3029, which serves as the power supply path from the control device. Control, performed by a control device (not shown) based on the temperature detected by the thermistor 3025 (e.g., a power-on and power-off control device based on a triac known in the art), is performed by energizing the heater 3022 via the wiring harness 3029.

[0548] The heater 3022 is positioned and held at one end in the longitudinal direction by an electrode setting part 3221b, which is provided with a power supply electrode 3226 inserted into the holding part 3021a. Furthermore, the heater 3022 is positioned at the other end, opposite to the longitudinal end, by a heater clamp 3028. In this way, even if the heater 3022 elongates due to thermal expansion during heating, the heater 3022 is configured to remain energized by being held in its positioned state at both ends, ensuring that the power supply part does not deviate from its position.

[0549] (5) Effects and advantages

[0550] To verify the effectiveness and advantages of the present invention, this example is compared with a comparative example of a configuration in the prior art. Figure 50 This is a perspective view showing the heater support unit 3050 in the comparative example. The heater support unit 3050 in the comparative example comprises a heater support 3051, a heater 3052, a heater clip 3028, and a power supply connector 3027. The heater 3052 in the comparative example has a heating element 3223 and a power supply electrode 3226 on the same plane of the substrate 3521, including two ends in the longitudinal direction held by the heater clip 3028 and the power supply connector 3027, and is positioned relative to the heater support 3051. Furthermore, a power supply contact is provided in the power supply connector 3027, which serves as a power supply device, and power can be supplied to the heater 3052 by contacting the power supply contact in the power supply connector 3027 with the power supply electrode 3226 of the heater 3052. In other words, it can be said that the prior art configuration is such that the heating element and the power supply electrode are disposed on the same plane of the substrate, and the power supply electrode is disposed along the extension line of the heating element in the longitudinal direction.

[0551] In the comparison between the heater support unit of this example and the comparative example, this example can be configured to be approximately 7 mm smaller in the longitudinal direction. In other words, by configuring the substrate employing the heater to be bent and the electrodes to be placed on a surface different from the surface where the heating element is located, and by supplying power to the heater from power supply contacts provided in the heater support, the size of the heater support unit in the longitudinal direction can be reduced. Furthermore, by eliminating the power supply connector, depending on the device configuration, a reduction in the size in the transport direction can also be expected.

[0552] As described above, according to the present invention, the heater support unit does not need to be equipped with a power supply connector, thus saving space corresponding to the installation of a power supply connector. Furthermore, since the power supply contacts requiring a predetermined width are located on a plane different from the plane where the heating element is located, the heater support unit can be miniaturized, thereby enabling miniaturization of the fixing apparatus and the image forming apparatus.

[0553] Example 10

[0554] Next, Example 10 according to the invention will be described. Example 10 is configured differently from Example 9 in the method of supplying power to the heater. Similar reference numerals will be applied to the configuration of Example 10 that is similar to that of Example 9, and their description will be omitted. Hereinafter, the following will be used... Figure 51 Describe the feature configuration in Example 10.

[0555] Figure 51 This is a schematic perspective view showing the heater support unit 3060 and the power supply device in this example. Similar to Example 9, the heater 3022 provided in the heater support unit 3060 is configured to include a curved portion. The heater support 3061 holds the heater 3022 and does not include a power supply device as in Example 9. In this example, the electrode setting portion 3221b of the power supply electrode 3226 of the heater 3022 is provided at one end of the heater support unit 3060 in the longitudinal direction. Furthermore, once the heater support unit 3060 is added to the image forming apparatus, the electrode setting portion 3221b faces the side surface housing 3042, and the power supply electrode 3226 contacts the power supply contact 3421 provided on the side surface housing 3042 and serving as the power supply device with abutment pressure. In other words, the image forming apparatus in this example supplies power to the heater from the power supply control device via the power supply device provided on the housing.

[0556] Comparing the heater bracket unit in this example with the aforementioned comparative example, which is a configuration in the prior art, this example can be configured to be approximately 12 mm smaller in the longitudinal direction. In other words, compared to Example 1, by placing the power supply device on the housing of the image forming apparatus instead of inside the heater bracket, a further space-saving effect in the longitudinal direction can be achieved.

[0557] Example 11

[0558] Next, Example 11 according to the invention will be described. Example 11 is configured differently from Example 9 in the shape of the heater. Similar reference numerals will be applied to configurations in Example 11 similar to those in Example 9, and their descriptions will be omitted. Hereinafter, the following will be used... Figure 52A and 52B , Figure 53 as well as Figure 54A and 54B Describe the feature configuration in Example 11.

[0559] Figure 52A This is a schematic perspective view of the heater 3072 in this example as viewed from the heating element 3223 side. Figure 52B This is a schematic perspective view as seen from the side of the power supply electrode 3226. In this example, the substrate 3721 of the heater 3072 is bent by two bends 3721c such that the heating element mounting portion 3721a and the electrode mounting portion 3721b extend parallel to each other. In other words, the substrate 3721 is formed by folding its longitudinal end 180°.

[0560] Figure 53 This is a schematic perspective view showing the heater bracket 3071 and the power supply contact 3077 used as a power supply device in this example. In this example, the power supply contact 3077 is arranged near the end of the heater bracket 3071 in the longitudinal direction and on the side opposite to the side facing the clamping part N.

[0561] Figure 54A This is a schematic perspective view of the heater support unit 3070 in this example as viewed from the electrode setting section 3721b side, and Figure 54B This is a schematic perspective view as seen from the heating element mounting section 3721a side. In this example, the heater 3072 is arranged such that the heating element mounting section 3721a and the electrode mounting section 3721b clamp the heater support 3071. In this state, the heater 3072 held by the heater support 3071 is configured such that the power supply electrode 3226 contacts the power supply contact 3077 with abutment pressure in the image forming apparatus. In other words, in the image forming apparatus of this example, the power supply control device supplies power to the heater via a power supply device provided behind the heating element mounting section.

[0562] Comparing the heater support unit of this example with the aforementioned comparative example, which is a configuration in the prior art, this example can be configured to be approximately 13 mm smaller in the longitudinal direction. In other words, by bending the substrate so that the electrode setting portion is parallel to the heating element setting portion rather than perpendicular to the heating element setting portion and establishing a connection with the power supply device located behind the heating element setting portion, a further reduction in longitudinal space can be achieved compared to Example 1.

[0563] Example 12

[0564] Next, Example 12 according to the invention will be described. Example 12 is a configuration of power supply to the heater that differs from that of Example 9. Similar reference numerals will be applied to configurations of Example 12 that are similar to those of Example 9, and their descriptions will be omitted. Hereinafter, the following will be used... Figure 55 Describe the feature configuration of Example 12.

[0565] Figure 55 This is a general diagram showing the configuration for supplying power to the heater 3022 held by the heater bracket 3081 in this example. Similar to Example 9, the heater 3022 in this example has a configuration including a bend 3221c. An electrode setting portion 3221b, in which a power supply electrode 3226 is provided, is provided at one end of the heater bracket unit 3080 in the longitudinal direction. Furthermore, in this example, a power supply connector 3027 is connected to the electrode setting portion 3221b. In this example, because the substrate 3221 is bent in the fixing device, the power supply connector 3027 is attached in a state rotated 90° compared to the configuration in the prior art (see [reference]). Figure 50 The power supply to heater 3022 is performed by the power supply contacts inside power supply connector 3027 (which serves as a power supply device connected to power supply electrode 3226).

[0566] In comparing the heater support unit in this example with the aforementioned comparative example, which is a configuration in the prior art, this example can be configured to be approximately 3mm smaller in the longitudinal direction. In other words, by adopting a configuration in which the power supply connector is rotated 90° to allow it to be connected to the heater, a space-saving effect in the longitudinal direction can be achieved. This example is particularly advantageous for configurations where the difference between the vertical and horizontal widths of the power supply connector is significant.

[0567] Variation Example

[0568] It should be noted that although the invention has been described using monochrome image forming apparatus in each of the above examples, the invention can also be applied to various other apparatuses described at the beginning. Examples of other image forming apparatuses to which the invention applies include a tandem color image forming apparatus using a recording material conveyor belt, a four-cycle intermediate transfer system color image forming apparatus, and a tandem intermediate transfer system color image forming apparatus. Furthermore, other examples include color image forming apparatuses based on intermediate transfer systems using a recording material conveyor belt, and image forming apparatuses using four or more toners. Similar effects can be obtained by applying the invention to the image forming apparatuses described above.

[0569] Furthermore, although each of the above examples has been described using a tension-free membrane heating system that includes a heater on the inner surface side of the membrane, the present invention can also be applied to other systems. Examples of other systems include a fixing device that includes a heating roller (which serves as a roller for heating the toner image on the recording material) and uses a membrane assembly unit on a pressure-heating roller. Similar effects can be obtained by applying the present invention to a fixing device using the above configuration.

[0570] Other variations include configurations where the heating element is not disposed on the surface of the heater that abuts the membrane, but on the opposite surface. Furthermore, the layer configuration of the heater can be modified in various ways depending on the application, size, etc., and similar effects can be achieved by applying this invention.

[0571] Other variations include examples of changing the shape of the substrate by bending it more gently. Figure 56 This is shown in Example 9 (see Example 9) Figure 47 A schematic perspective view of heater 3092 obtained by bending the substrate more gently. Figure 57 This is shown in Example 11 (see Example 11) Figure 52A and 52B This is a schematic perspective view of the heater 3102 obtained by bending the substrate more gently. Since each of substrates 3921 and 3971 includes a heating element placement portion 3921a and 3921a and 3971a, an electrode placement portion 3921b and 3921b and 3971b, a bent portion 3921c and 3921c and 3971c, and has a configuration similar to the aforementioned example, differing only in the shape of the bent portion, its description will be omitted. By applying the present invention, similar effects can be obtained even with this configuration including gently bent portions and with configurations using both steep and gently bent portions.

[0572] Other variations include configurations where the power supply unit and power supply electrodes are welded together and connected to each other. Figure 58 This is shown as example 12 (see Example 12) Figure 55 This is a schematic perspective view showing a variant of the example where the power supply contact 3087 is soldered to the electrode setting portion 3221b of the heater instead of the power supply connector. Since other configurations are similar to those in Example 12, their description will be omitted. The power supply devices are not limited to those used in this example, but various modifications can be made, and similar effects can be obtained by applying the present invention to these configurations.

[0573] Examples of configurations or concepts disclosed in the foregoing embodiments will be described below. However, these are merely examples and the disclosure of the foregoing embodiments is not limited to the configurations or concepts described below.

[0574] Configure C1

[0575] A heater, comprising:

[0576] Heating element;

[0577] Electrodes for supplying power to the heating element; and

[0578] An elongated substrate, the substrate including a heating element and electrodes disposed thereon, wherein the substrate includes:

[0579] The heating element mounting section extending in the longitudinal direction, and

[0580] An electrode mounting section is positioned by bending one end of the heating element mounting section along the longitudinal direction, and

[0581] The heating element is mounted on the heating element mounting section, and the electrode is mounted on the electrode mounting section.

[0582] Configure C2

[0583] The heater according to configuration C1 also includes:

[0584] A conductor that electrically connects a heating element to an electrode and extends from the heating element mounting portion to the electrode mounting portion.

[0585] Configure C3

[0586] In the heater described according to configuration C1 or C2, the heating element mounting section includes a plane on which the heating element is mounted.

[0587] Configure C4

[0588] In the heater according to configuration C3, the electrode setting portion extends perpendicular to the plane.

[0589] Configure C5

[0590] In the heater according to configuration C3, the electrode arrangement extends parallel to the plane.

[0591] Configure C6

[0592] In the heater described according to any of the configurations C1 to C5, the substrate is formed by folding a plate containing metal as the main material.

[0593] Configure C7

[0594] A heating device, comprising:

[0595] First body of revolution;

[0596] The heater, according to any one of configurations C1 to C6, is disposed within the internal space of the first rotating body; and

[0597] The second rotating body forms a clamping part with the heating element mounting part of the heater via the first rotating body.

[0598] Configure C8

[0599] In the heating device according to configuration C7, the electrode setting part is located on the side further away from the clamping part than the heating element setting part in the thickness direction.

[0600] Configure C9

[0601] In the heating device according to configuration C8, the heating element is disposed along the thickness direction on the surface of the substrate facing the second rotating body.

[0602] Configure C10

[0603] In the heating device described according to any of the configurations C7 to C9

[0604] The first rotating body is a tubular membrane, and

[0605] The second rotating body is a roller.

[0606] Configure C11

[0607] The heating device according to any of the configurations C7 to C10 further includes:

[0608] Heater support, which holds the heater and guides the first rotating body to rotate.

[0609] The heater bracket is equipped with a power supply device for supplying power to the electrodes.

[0610] Configure C12

[0611] In the heating device according to configuration C11

[0612] The power supply unit is located in the heater bracket, and

[0613] The heater holder includes a retaining portion that holds the heater by inserting the electrode portion of the heater therein.

[0614] Configure C13

[0615] An image forming apparatus, comprising:

[0616] An image forming unit that forms an image on a recording material; and

[0617] According to any of the configurations C7 to C12, the heating device fixes the image formed on the recording material onto the recording material.

[0618] Configure C14

[0619] An image forming apparatus, comprising:

[0620] An image forming unit that forms an image on a recording material;

[0621] According to any one of configurations C7 to C10, the heating device fixes the image formed on the recording material onto the recording material; and

[0622] The housing, image forming unit, and heating device are disposed within the housing.

[0623] The power supply device for supplying power to the electrodes is disposed on the surface of the housing facing the heater at one end of the substrate along the longitudinal direction.

[0624] Configure C15

[0625] A heater holder for holding a heater, the heater including a heating element, electrodes for supplying power to the heating element, and an elongated substrate having the heating element and electrodes disposed thereon, the heater holder comprising:

[0626] A retaining part, wherein the retaining part holds the heater by inserting a portion therein; and

[0627] A power supply device for supplying power to the electrodes, the power supply device being disposed at the holding part.

[0628] The power supply is connected to the electrodes installed in the heater of the insertion and holding section.

[0629] Furthermore, in heating devices consisting of heaters, films, pressure rollers, etc., there is a configuration where the film unit is offset upstream of the clamping section in the conveying direction in order to fix the toner image onto the recording material with a small amount of heat. This is because, in such a configuration, by applying strong pressure to the toner downstream of the clamping section in the conveying direction, the toner heated and softened from upstream to downstream of the clamping section in the recording material conveying direction can be effectively fixed onto the recording material, thus improving fixing performance. However, in the case of a configuration that offsets the position of the clamping section, if the width of the clamping section decreases due to deviations in the hardness, pressure, etc., of the pressure rollers, the fixing performance may deteriorate because the heating element of the heater is located upstream of the conveying direction. In other words, the fixing performance in the above configuration may change when the width of the clamping section changes. Therefore, a heater capable of suppressing changes in fixing performance will be described next.

[0630] Example 13

[0631] (1) Image forming equipment

[0632] As a general image forming apparatus 4100 in this embodiment, it will use Figure 59 Briefly describe the operation of a laser printer that uses electrophotographic recording technology. Figure 59 It is a cross-sectional view of the general image forming apparatus 4100 in this embodiment.

[0633] The image forming operation performed by the image forming unit of the image forming apparatus 4100 will be described. If the image forming apparatus 4100 receives a print command from an external device, the scanner unit 4003 emits a laser L to the photosensitive member 4001 based on image information. The laser L scans the photosensitive member 4001, which is charged by the charging roller 4002 with a predetermined polarity, and an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive member 4001. Subsequently, the developing apparatus 4004 supplies toner to the photosensitive member 4001, and a toner image corresponding to the image information is formed on the photosensitive member 4001. By rotating the photosensitive member 4001 in the direction of arrow R, the toner image on the photosensitive member 4001 moves to the transfer position formed by the photosensitive member 4001 and the transfer roller 4005, and is then transferred to the recording material P fed from the cartridge 4006 by the pickup roller 4007. The surface of the photosensitive member 4001 that has passed the transfer position is cleaned by the cleaner 4008.

[0634] The fixing device 4009, which serves as the fixing section, performs fixing treatment on the recording material P, which has been transferred with a toner image, using heat and pressure. Subsequently, the recording material P is discharged by the discharge roller 4010 to the discharge tray 4011.

[0635] (2) Fixing device

[0636] Next, the configuration and operation of the fixing device 4009 will be described. In this embodiment, the tensionless film heating system fixing device 4009 is used as an example of a heating device. The fixing device 4009 in this embodiment is a device in which an annular strip (or cylindrical) heat-resistant film is used, at least a portion of the periphery of which is always kept tensionless (in a state where no tension is applied to it), and the film is driven to rotate by the rotational driving force of the pressure member.

[0637] Reference Figure 60 Describe the configuration of the fixing device 4009. Figure 60This is a general cross-sectional view of the fixing device 4009 in this embodiment. The fixing device 4009 in this embodiment includes a rotatable tubular membrane 4023 as a first rotating body, a heater 4022 that heats the membrane 4023 within its internal space, and a heater support 4021 made of heat-resistant resin that supports the heater 4022 and guides the rotation of the membrane 4023. The fixing device 4009 also includes a reinforcing member 4024 and a pressure roller 4030. The reinforcing member 4024 reinforces the heater support 4021, and the pressure roller 4030, as a second rotating body, forms a clamping portion N between the pressure roller 4030 and the membrane 4023. The membrane unit 4020 in this embodiment is composed of components such as the membrane 4023, the heater 4022, the heater support 4021, and the reinforcing member 4024. Here, heater 4022, membrane 4023, heater support 4021, and pressure roller 4030 are all components that extend along the rotational axis of pressure roller 4030. The axial direction of the cylindrical shape of membrane 4023, parallel to the rotational axis of pressure roller 4030, is also considered. Figure 61 The direction of the arrow pointing to the insertion of the fixing film will be referred to as the longitudinal direction below. Furthermore, in this embodiment, the transport direction of the recording material P within the clamping part N is orthogonal to this longitudinal direction.

[0638] If the pressure roller 4030 receives power from the motor and rotates in the direction of arrow b, the film 4023 is driven and rotates in the direction of arrow a. The toner image T on the recording material P is held and conveyed by the clamping part N, heated, and fixed onto the recording material P. The pressure position of the pressure roller 4030 is substantially the same as the central part of the heater 4022 in the conveying direction of the recording material P. In other words, in the fixing device 4009 of this example, similar to the configuration in the prior art, the center of the heater 4022 and the center of the pressure roller 4030 overlap each other in the conveying direction.

[0639] Next, we will use Figure 61 The components constituting the fixing device 4009 are described in detail. Figure 61 This is an exploded perspective view of the membrane unit 4020 used in the fixing device 4009.

[0640] Heater 4022 includes an elongated plate-shaped substrate (containing ceramic or metal alloy as the main material), a heating element that heats up in response to electricity, and a coating that protects the substrate and the heating element. Details of heater 4022 will be described later.

[0641] When membrane 4023 is a single-layer membrane, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), PPS, etc., are preferably used as the membrane base layer. In the case of a composite membrane, materials such as polyimide (PI), polyamide-imide (PAI), polyether ether ketone (PEEK), or polyether sulfone (PES) are preferably used as the membrane base layer. Furthermore, it is preferable to coat the surface with PTFE, PFA, or tetrafluoroethylene-perfluoroalkyl vinyl ether (FEP) as a release layer to form a composite membrane. Additionally, it is also suitable to use pure metals or alloys with high thermal conductivity, such as SUS, Al, Ni, Cu, Zn, etc., in the base layer, and perform the aforementioned coating treatment or coating with fluoropolymer tubes on the release layer. To ensure satisfactory thermal conductivity, the thickness of membrane 4023 is preferably at least 20 μm and not more than 100 μm.

[0642] In this embodiment, a 60 μm thick PI is used as the film base layer, and considering the wear of the film release layer caused by paper feeding and thermal conductivity, the film release layer is coated with a 12 μm thick PFA.

[0643] The heater bracket 4021 is a relatively long component in the longitudinal direction with a generally groove-shaped cross-section. Since the heater bracket 4021 requires heat resistance and rigidity, it is preferable to use materials such as liquid crystal polymer resins with high heat resistance and excellent strength. Molded parts made of heat-resistant resins such as polyphenylene sulfide (PPS) and liquid crystal polymers (LCP) are particularly suitable for the heater bracket 4021.

[0644] The reinforcing member 4024 is made of a metal such as iron, receives the force of the pressure spring (described below), and presses the heater 4022 against the pressure roller 4030 side via the heater support 4021. Furthermore, the reinforcing member 4024 is a member used to maintain strength so that the heater support 4021 does not deform significantly even under the pressure used to form the clamping portion N.

[0645] The reinforcing member 4024 is fitted into the groove-shaped interior of the heater bracket 4021. A heater receiving groove is located on the side of the heater bracket 4021 facing the pressure roller 4030, and the heater 4022 is fitted into the heater receiving groove and positioned as desired. A membrane 4023 is fitted onto the outside of the heater bracket 4021, where the aforementioned components are assembled, with a certain allowance around its perimeter.

[0646] The pressure roller 4030, used as a pressure rotating body, includes a core metal made of a material such as iron or aluminum, an elastic layer made of a material such as silicone rubber, and a release layer made of a material such as PFA.

[0647] Thermistor 4025 is a temperature sensing component and abuts against heater 4022 on the side opposite to the surface of abutment film 4023. The energization of heater 4022 is controlled based on the temperature detected by thermistor 4025.

[0648] Flanges 4026 are disposed at both ends of the reinforcing member 4024 in the longitudinal direction and restrict the movement of the rotating membrane 4023 in the longitudinal direction. The power supply terminals of the heater 4022 also extend from one end of the membrane 4023, and a power supply connector 4027 is fitted to the power supply terminals. The power supply connector 4027 contacts the electrode portion of the heater 4022 with abutting pressure and forms a power supply path. Furthermore, at the end where the power supply connector 4027 is disposed and at the opposite end, a heater clamp 4028 formed of a U-shaped metal plate uses its elasticity to hold one end of the heater 4022 against the heater support 4021. The protrusions of the reinforcing member 4024 extend from both ends of the membrane 4023 in the longitudinal direction, and flanges 4026 are fitted and attached to both ends, thereby assembling the membrane unit 4020 into a single unit.

[0649] Next, we will use Figure 62 Describe the pressurization mechanism of the heating device. Figure 62 This is a front view of the fixing device 4009 as seen from the direction of material transport, and does not show a portion of the membrane 4023 in order to show the interior of the membrane unit 4020.

[0650] The film unit 4020 is positioned facing the pressure roller 4030 and supported by the top plate side housing 4041 of the fixing unit, such that along the longitudinal direction ( Figure 62 Movement in the left and right directions is restricted, while movement in the pressurization direction is permitted. Figure 62 The pressure spring 4045 is attached to the top plate side housing 4041 of the fixing unit in a compressed state. The pressure of the pressure spring 4045 is received by the protrusion of the reinforcing member 4024, which is pressed against the pressure roller 4030 side, and the film unit 4020 is pressed against the pressure roller 4030 side. The bearing member 4031 is configured to axially support the core metal of the pressure roller 4030 and receive pressure from the film unit 4020 via the pressure roller 4030. In order to rotatably support the core metal of the pressure roller, which is heated to a relatively high temperature, a material with heat resistance and excellent sliding properties is used as the material of the bearing member 4031. The bearing member 4031 is attached to the bottom side housing 4043 of the fixing unit. The pressure roller drive gear 4033 is attached to one end of the core metal of the pressure roller 4030 so that it receives the rotational driving force of the drive device (not shown) and rotates the pressure roller 4030.

[0651] (3) Heater

[0652] Before describing the heater in this embodiment, we will first use Figure 63 and 64 The heater 4052, configured as in the prior art, is described as a comparative example. Figure 63 This is a cross-sectional view of heater 4052, which is a comparative example of a configuration in the prior art. Figure 64 It is a perspective view.

[0653] A conventional heater 4052 with a prior art configuration includes an elongated plate-shaped substrate 4521, a strip-shaped heating element 4522 that heats up in response to energization, and a coating 4523 serving as a protective layer for protecting the substrate 4521 and the heating element 4522. The heater 4052 also includes a power supply electrode 4524 and a conductive pattern 4545 for supplying power to the heating element 4522, and the conductive pattern 4545 is also covered by the coating 4523. The heater 4052 is disposed in a fixing apparatus such that the coating 4523 abuts against the inner peripheral surface of the film 4023.

[0654] Depending on the actual operating temperature, a heat-resistant material must be selected for the substrate 4521, primarily ceramic or metal. When metal is used as the substrate 4521, an insulating layer is required between the substrate 4521 and the heating element 4522. The thickness of the substrate 4521 is determined by considering strength, heat capacity, and heat dissipation performance. While a thinner substrate 4521 is advantageous for rapid start-up due to its lower heat capacity, excessive thickness may lead to problems such as deformation during heating and molding of the heating element 4522. Conversely, while a thicker substrate 4521 is advantageous in terms of deformation during heating and molding of the heating element 4522, excessive thickness is detrimental to rapid start-up due to its higher heat capacity. Considering mass production, cost, and performance, the preferred thickness of the substrate 4521 is 0.3 mm to 2.0 mm.

[0655] A heating element 4522 is obtained by applying a heating element paste, obtained by mixing a conductive component (A), a glass component (B), and an organic binder component (C), onto a substrate 4521 and subsequently sintering the resulting article. If the heating element paste is sintered, the organic binder component (C) burns and disappears, while components (A) and (B) remain, thereby forming a heating element 4522 containing both a conductive component and a glass component. Here, silver-palladium (Ag·Pd), ruthenium oxide (RuO2), etc., are used individually or in combination as the conductive component (A), and a sheet resistance value of 0.1 [Ω / □] to 100 [kΩ / □] is preferably obtained. Furthermore, if other materials are included in addition to the aforementioned components (A) to (C), there is no problem as long as the content is very small and does not impair the performance of the present invention.

[0656] The power supply electrode 4524 and the conductive pattern 4545 contain silver (Ag), platinum (Pt), gold (Au), silver-platinum (Ag·Pt) alloy, silver-palladium (Ag·Pd) alloy, etc., as main components. Similar to the heating element paste, the power supply electrode 4524 and the conductive pattern 4545 are formed by applying a paste obtained by mixing conductive component (A), glass component (B), and organic binder component (C) onto the substrate 4521 and sintering the paste. In order to supply power to the heating element 4522, the resistance of the power supply electrode 4524 and the conductive pattern 4545 is set to be sufficiently low relative to the heating element 4522. Here, for the aforementioned heating element paste, power supply electrode paste, and conductive pattern paste, it is necessary to select materials that soften and melt at a temperature lower than the melting point of the substrate 4521, and considering the temperature in actual use, it is necessary to select materials with heat resistance.

[0657] Although there are no particular limitations on the material of coating 4523, it is necessary to select a material with heat resistance considering the temperature in actual use. As a material, glass or polyimide (PI) is preferred considering heat resistance, and in the case of glass, a specific powder material can be appropriately selected without compromising the characteristics of the invention. Thermally conductive fillers with insulating properties can be added as needed. When the insulating layer of glass or polyimide (PI) is formed on substrate 4521, the linear expansion coefficients of substrate 4521 and coating 4523 need to be appropriately adjusted so that cracking or peeling does not occur in coating 4523 due to differences in the linear expansion coefficients of the materials. Although there are no particular limitations on the forming methods of heating element 4522, power supply electrode 4524, conductive pattern 4545, and coating 4523, in one example, they can be smoothly formed using a screen printing method. Here, when metal is used as the material of substrate 4521, warping of substrate 4521 can be prevented during manufacturing by forming coating 4523 on both surfaces of substrate 4521.

[0658] Next, a detailed configuration and manufacturing method of heater 4052, as configured in the prior art, will be described. Heater 4052 is the heater used in Comparative Examples 7, 8, and 9, which will be described below in the evaluation tests.

[0659] As substrate 4521, an alumina substrate with a width of 11 mm, a length of 270 mm, and a thickness of 1 mm is used. In addition, a heating element paste obtained by mixing silver-palladium (Ag·Pd) as a conductive component, other glass components, and organic binder components, as well as a power supply electrode paste and a conductive pattern paste obtained by mixing silver (Ag) as a conductive component, other glass components, and organic binder components, are prepared.

[0660] Heating element paste, power supply electrode paste, and conductive pattern paste are applied to substrate 4521 by screen printing. The resulting article is dried at 180°C and sintered at 850°C to form two heating elements 4522, power supply electrode 4524, and conductive pattern 4545. The two sintered heating elements 4522 have a width of 2.5 mm, a length of 230 mm, and a thickness of 15 μm. A folded heating pattern is formed by connecting the two heating elements 4522 to the conductive pattern 4545 at one end in the longitudinal direction of heater 4052.

[0661] Subsequently, a glass paste is prepared and applied to the substrate 4521, heating element 4522, and conductive pattern 4545 by screen printing. The resulting material is dried at 180°C and sintered at 850°C to form a smooth coating 4523. The sintered coating 4523 has a width of 10.5 mm and a length of 260 mm, and the substrate 4521 has a height of 60 μm. The heater 4052 is completed in this manner.

[0662] Next, we will use Figure 65 The description is based on the configuration of heater 4022 in Example 13. Figure 65 This is a cross-sectional view of heater 4022 according to Example 13. The difference between the heater according to this example and the heater in the comparative example of the prior art configuration is that the heat generated by the two heating elements is different, and the area of ​​the surface of the inner circumferential surface of the film on the downstream side along the conveying direction protrudes closer to the pressure roller than the area on the upstream side along the conveying direction.

[0663] The heater 4022 in this embodiment includes an elongated plate-shaped substrate 4221, two heating elements 4222 that heat up in response to energization, and a coating 4223 serving as a protective layer for protecting the substrate 4221 and the heating elements 4222. The heater 4022 also includes power supply electrodes and a conductive pattern for supplying power to the heating elements 4222, and the conductive pattern is covered by the coating 4223. The heater 4022 is disposed in a fixing apparatus such that the coating 4223 abuts against the inner peripheral surface of the film 4023. In this example, the transverse direction orthogonal to the longitudinal direction of the heater 4022 is parallel to the transport direction of the recording material.

[0664] Similar to the comparative example described above, the substrate 4221 according to this embodiment is an alumina substrate with a width of 11 mm, a length of 270 mm, and a thickness of 1 mm. Furthermore, heating element paste, power supply electrode paste, and conductive pattern paste similar to those used in the comparative example are used. The arrangement and formation methods of the power supply electrode and conductive pattern are similar to those in the comparative example, and their descriptions will be omitted. Hereinafter, the arrangement of the heating element 4222 and coating 4223, which are features of the present invention, will be described in detail. In this example, the thickness direction of the substrate 4221 is parallel to the pressure direction at the clamping portion N.

[0665] Heating element paste is applied to substrate 4221 by screen printing, and the resulting article is then dried at 180°C and sintered at 850°C to form two heating elements 4222. After sintering, the first heating element 4222a, located downstream of the recording material P in the transport direction, has a width of 2.2 mm, a length of 230 mm, and a thickness of 15 μm, resulting in a greater heat output than the second heating element 4222b located upstream in the transport direction. Conversely, the second heating element 4222b has a width of 3.0 mm, a length of 230 mm, and a thickness of 15 μm, and a folded heating pattern is formed by connecting the two heating elements 4222a and 4222b to a conductive pattern at one end in the longitudinal direction of heater 4022. In other words, the heater 4022 according to this example has a configuration in which two heating elements with different heat outputs are arranged in the transport direction on the substrate.

[0666] Subsequently, glass paste is applied to substrate 4221, heating elements 4222a and 4222b, and conductive pattern by screen printing. The resulting article is dried at 180°C and sintered at 850°C. Furthermore, glass paste is again applied to the first heating element 4222a by screen printing, and the resulting article is dried at 180°C and sintered at 850°C, thereby forming a coating 4223 with a protruding shape. In other words, the coating 4223 on the first heating element 4222a is formed to be thicker than the coating 4223 on the second heating element 4222b. Here, in order to keep the relationship between the set temperature, power consumption, and heat generation of the fixing device 4009 equivalent to that of the comparative example, and to uniformize the heat transfer changes caused by the protruding shape of the coating 4223, the resistance value and resistance ratio of the heating pattern are adjusted by adjusting the width of each heating element 4222.

[0667] It should be noted that, as the second applied glass slurry, a glass slurry with a lower softening temperature than the first applied glass slurry can be selected, and the sintering temperature for the second applied glass slurry can be set lower than the softening temperature of the first applied glass slurry. Therefore, it is easier to form a coating 4223 with a prominent shape.

[0668] The heater 4022 includes a first region 4223a overlapping the first heating element 4222a and a second region 4223b overlapping the second heating element 4222b when viewed along the thickness direction of the substrate 4221, in the surface of the coating 4223 that abuts against the inner peripheral surface of the film 4023. In the fixing device 4009, along the thickness direction of the substrate 4221, the first region 4223a is positioned to protrude closer to the pressure roller 4030 than the second region 4223b. Furthermore, both the first region 4223a and the second region 4223b extend over the entire area in the longitudinal direction of the heater 4022. It should be noted that the first region need not extend over the entire area of ​​the heater, and the first region only needs to have a length covering the entire width of the recording material to be transported.

[0669] The sintered coating 4223 has a width of 10.5 mm and a length of 260 mm. Furthermore, by varying the thickness of the coating 4223 used for the evaluation tests described below, three types were created in Example 13. In Examples 13-1, 13-2, and 13-3, the height Ha from the substrate 4221 to the surface of the coating 4223 in the first region 4223a is 75 μm, 80 μm, and 85 μm, respectively. Furthermore, the height Hb from the substrate 4221 to the surface of the coating 4223 in the second region 4223b is 65 μm, 60 μm, and 55 μm, respectively. In the thickness direction of the substrate 4221, the protrusion Pt of the surface of the coating 4223 in the first region 4223a relative to the second region 4223b towards the pressure roller 4030 is set to satisfy Pt = Ha - Hb. At this point, the protrusions Pt in Examples 13-1, 13-2, and 13-3 are 10 μm, 20 μm, and 30 μm, respectively.

[0670] Example 14

[0671] Next, we will use Figure 66 The description is based on the configuration of heater 4062 in Example 14. Figure 66 This is a cross-sectional view of heater 4062 according to Example 14. Similar reference numerals will be applied to configurations in Example 14 that are similar to those in Example 13, and their descriptions will be omitted.

[0672] The heater 4062 in this embodiment includes an elongated plate-shaped substrate 4621, four heating elements 4622 that heat up in response to energization, and a coating 4623 serving as a protective layer for protecting the substrate 4621 and the heating elements 4622. The heater 4062 also includes power supply electrodes and a conductive pattern for supplying power to the heating elements 4622, and the conductive pattern is also covered by the coating 4623. The heater 4062 is disposed in the fixing apparatus such that the coating 4623 abuts against the inner peripheral surface of the film 4023.

[0673] Similar to the aforementioned comparative example, the substrate 4621 in this embodiment is an alumina substrate with a width of 11 mm, a length of 270 mm, and a thickness of 1 mm. Furthermore, the heating element paste, power supply electrode paste, and conductive pattern paste are similar to those used in the comparative example. The arrangement and formation method of the power supply electrode and conductive pattern are similar to those in the comparative example, and their description will be omitted. Hereinafter, the arrangement of the heating element 4622 and coating 4623, which are features of the present invention, will be described in detail.

[0674] Heating element paste is applied to substrate 4621 via screen printing, and the resulting article is dried at 180°C and sintered at 850°C to form four heating elements 4622. Of the four heating elements 46222 after sintering, the first heating element 4622a, located on the downstream side in the transport direction of the recording material P, has a width of 0.9 mm, a length of 230 mm, and a thickness of 15 μm, thus exhibiting greater heat generation compared to the other three heating elements 4622b. On the other hand, the other three heating elements 4622b have a thickness of 1.4 mm, a length of 230 mm, and a thickness of 15 μm, and a three-fold folded heating pattern is formed by connecting these four heating elements 4622 to a conductive pattern at the longitudinal end of heater 4062. In other words, heater 4062 in this embodiment is configured such that four heating elements are disposed on the substrate along the transport direction, and the heating element located on the downstream side in the transport direction has the greatest heat generation among the plurality of heating elements.

[0675] Subsequently, a glass paste similar to that used in the comparative example and Example 13 was applied to the substrate 4621, heating elements 4622a and 4622b, and the conductive pattern via screen printing. The resulting article was then dried at 180°C and sintered at 850°C. Furthermore, the glass paste was again applied to the first heating element 4622a via screen printing, and the resulting article was dried at 180°C and sintered at 850°C to form a coating 4623 with a protruding shape. In other words, the coating 4623 on the first heating element 4622a was formed to be thicker than the coating 4623 on the second heating element 4622b. Here, in order to maintain the relationship between the set temperature, power consumption, and heat generation of the fixing device 4009 as in the comparative example, and to homogenize the heat transfer changes caused by the protruding shape of the coating 4223, the resistance value and resistance ratio of the heating pattern were adjusted by adjusting the width of each heating element 4222.

[0676] The heater 4062 includes a first region 4623a that overlaps with the first heating element 4622a when viewed along the thickness direction of the substrate 4621, and a second region 4623b that overlaps with the other three heating elements 4622b, in the surface of the coating 4623 that abuts against the inner peripheral surface of the film 4023. At this time, in the fixing device 4009, along the thickness direction of the substrate 4621, the first region 4623a is positioned to protrude towards the side closer to the pressure roller 4030 compared to the second region 4623b.

[0677] The sintered coating 4623 has a width of 10.5 mm and a length of 260 mm. Furthermore, by varying the thickness of the coating 4623 used for the evaluation tests described below, three types were created in Example 14. In Examples 14-1, 14-2, and 14-3, the height Ha from the substrate 4621 to the surface of the coating 4623 in the first region 4623a is 75 μm, 80 μm, and 85 μm, respectively. Furthermore, the height Hb from the substrate 4621 to the surface of the coating 4623 in the second region 4623b is 65 μm, 60 μm, and 55 μm, respectively. In other words, the protrusion Pt in Examples 14-1, 14-2, and 14-3 is 10 μm, 20 μm, and 30 μm, respectively.

[0678] Example 15

[0679] Next, we will use Figure 67 The description is based on the configuration of heater 4072 in Example 15. Figure 67 This is a cross-sectional view of heater 4072 according to Example 15. Similar reference numerals will be applied to configurations in Example 15 that are similar to those in Example 13, and their descriptions will be omitted.

[0680] The heater 4072 in this embodiment includes an elongated plate-shaped substrate 4721 made of metal, two heating elements 4722 that heat up in response to energization, a coating 4723 serving as a protective layer for the heating elements 4722, and an insulating layer 4724 for maintaining insulation between the heating elements 4722 and the substrate 4721. Furthermore, the heater 4072 includes a coating 4725 disposed on a surface of the substrate 4721 opposite to the surface where the heating elements 4722 and the insulating layer 4724 are disposed, to prevent warping of the substrate 4721. The heater 4072 also includes power supply electrodes and conductive patterns for supplying power to the heating elements 4722, and the conductive patterns are also covered by the coating 4723. The heater 4072 is disposed in a fixing apparatus such that the coating 4723 abuts against the inner peripheral surface of the film 4023. Since the configuration and formation method of the power supply electrodes and conductive patterns are similar to those in the comparative example, their description will be omitted. The configuration of the heating element 4722 and the coating 4723, which are features of the present invention, will be described in detail below.

[0681] In this embodiment, the substrate 4721 is a ferritic stainless steel substrate (SUS430:18Cr stainless steel) with a width of 11 mm, a length of 270 mm, and a thickness of 0.5 mm. Stainless steel, nickel, copper, aluminum, or alloys containing these metals as the main material are suitable as the metal material used in the substrate 4721. Among these, stainless steel is most preferably used considering strength, heat resistance, and corrosion resistance. There are no particular limitations on the type of stainless steel; it is appropriate to select the stainless steel based on considerations such as the necessary mechanical strength, the coefficient of linear expansion corresponding to the formation of the insulation layer 4724 and the heating element 4722, and the availability of sheet metal in the market. In one example, martensitic and ferritic stainless steels from the chromium-based stainless steel (400 series) have relatively low coefficients of linear expansion among stainless steels and are therefore suitable for use because they are easy to form the insulation layer 4724 and the heating element 4722.

[0682] An insulating layer 4724 is provided using an insulating glass paste to establish insulation between the substrate 4721 and the heating element 4722. For the insulating layer 4724, the insulating glass paste is applied to the substrate 4721 by screen printing, the resulting article is dried at 180°C and sintered at 850°C to form the insulating layer 4724. The sintered insulating layer 4724 has a width of 10.5 mm, a length of 260 mm, and a height of 50 μm. Here, relative to the thickness of the insulating layer 4724, the heater used in the image forming apparatus typically preferably has a dielectric strength of about 1.5 kV. Therefore, to obtain a dielectric strength of 1.5 kV between the heating element 4722 and the substrate 4721, it is only necessary to ensure the film thickness of the insulating layer 4724 according to the material.

[0683] Subsequently, heating element paste is applied to the insulating layer 4724 via screen printing, and the resulting article is dried at 180°C and sintered at 850°C to form two heating elements 4722. Of the two sintered heating elements 4722, the first heating element 4722a, located downstream of the conveying direction of the recording material P, has a width of 2.2 mm, a length of 230 mm, and a thickness of 15 μm, thus having a greater heat output compared to the second heating element 4722b located upstream of the conveying direction. On the other hand, the second heating element 4722b has a width of 3.0 mm, a length of 230 mm, and a thickness of 15 μm, and a folded heating pattern is formed by connecting the two heating elements 4722a and 4722b to a conductive pattern at one end in the longitudinal direction of the heater 4072. In other words, the heater 4072 in this embodiment has a configuration in which two heating elements with different heat outputs are disposed on the insulating layer along the conveying direction.

[0684] Subsequently, using a glass paste similar to that used in the comparative example and the foregoing embodiments, the glass paste was applied to the insulating layer 4724, the heating element 4722, and the conductive pattern by screen printing. Furthermore, the glass paste was applied to the surface of the substrate 4721 opposite to the surface where the insulating layer 4724 is located. The resulting article was dried at 180°C and sintered at 850°C, thereby forming a coating on both surface sides of the substrate 4721 to prevent warping of the substrate 4721 during sintering. Furthermore, the glass paste was again applied to the first heating element 4722a by screen printing, and the resulting article was dried at 180°C and sintered at 850°C, thereby forming a coating 4723 with a protruding shape.

[0685] The heater 4072 includes a first region 4723a that overlaps with the first heating element 4722a and a second region 4723b that overlaps with the second heating element 4722b when viewed along the thickness direction of the substrate 4721 in the surface of the coating 4723 that abuts against the inner peripheral surface of the film 4023. At this time, in the fixing device 4009, along the thickness direction of the substrate 4721, the first region 4723a is positioned to protrude towards the side closer to the pressure roller 4030 compared to the second region 4723b.

[0686] The coating 4723, which covers the heating element 4722 using a film 4023 and abuts against the inner peripheral surface of the film 4023, has a width of 10.5 mm and a length of 260 mm. A coating 4725, disposed on the surface of the substrate 4721 opposite to the coating 4723, has a width of 10.5 mm, a length of 260 mm, and a thickness of 110 μm. Furthermore, by varying the thickness of the coating 4723 used for the evaluation tests described below, three types were created in Example 15. In Examples 15-1, 15-2, and 15-3, the height Ha from the substrate 4721 to the coating 4723 in the first region 4723a is 75 μm, 80 μm, and 85 μm, respectively. Furthermore, the height Hb from the substrate 4721 to the surface of the coating 4723 in the second region 4723b is 65 μm, 60 μm, and 55 μm, respectively. In other words, the protrusions Pt in Examples 15-1, 15-2, and 15-3 are 10 μm, 20 μm, and 30 μm, respectively.

[0687] Effects and benefits of Examples 13, 14 and 15

[0688] To verify the advantages of the present invention, fixing performance evaluation tests were performed using a fixing apparatus (which includes the heaters in each of the above embodiments and comparative examples). Examples 13-1, 13-2, and 13-3 include a heater 4022 (see...). Figure 65 Examples 14-1, 14-2, and 14-3 include heater 4062 (see...). Figure 66 Examples 15-1, 15-2, and 15-3 include heater 4072 (see...). Figure 67 ), and comparative examples include heater 4052 (see Figure 63 The results of the evaluation tests and the effects of improved fixing performance on power saving and stable fixing performance will be described below.

[0689] Although heaters with the same configuration were used in Comparative Examples 7, 8, and 9 as described above, the positional relationship between the membrane unit 4020 and the pressure roller 4030 varied. In Comparative Example 7, the center of the heater 4052 was located at the same position as the center of the pressure roller 4030 in the recording material transport direction, similar to the configuration in the prior art and various examples. On the other hand, Comparative Examples 8 and 9 employed a configuration in which the membrane unit 4020 was offset such that the center of the heater 4052 was located upstream of the center of the pressure roller 4030 in the recording material transport direction. The offset was 1 mm in Comparative Example 8 and 2 mm in Comparative Example 9.

[0690] For the fixing performance evaluation test, a completely black pattern obtained by printing toner across the entire surface was used as the evaluation image pattern. The environment was set to a normal temperature and humidity environment of 23°C and 50% RH. As the paper feeding condition, three evaluation image patterns were continuously fed from a cold state. Multiple tests were performed with varying the set temperature of the fixing unit 4009, and the fixing temperature for each configuration was measured by taking the lower limit of the set temperature at which no image pattern defects were observed in each configuration as the fixing temperature. In addition, tests were performed with varying the rubber hardness of the pressure roller 4030 and the spring coefficient of the pressure spring 4045, with the clamping width changed to 10 mm, 8 mm, and 6 mm, to also evaluate the stability of the fixing performance.

[0691] The test results for each example and comparative example are shown in Table 8. Note that in Comparative Example 7, the fixing temperature when the clamping width is 10 mm is considered the baseline value, and the difference between the fixing temperature and the baseline value is shown as the evaluation result in the table. In other words, a smaller (larger in the negative direction) fixing temperature value shown in the table means that the fixing device can achieve fixing at a lower temperature and with lower power consumption. Furthermore, the table shows the difference between the maximum and minimum fixing temperatures when the clamping width changes in fixing devices with the same configuration.

[0692] [Table 8]

[0693]

[0694] In Comparative Example 7, the fixing temperature when the clamping part width is 8 mm is the same as the fixing temperature when the clamping part width is 10 mm (as a reference), and the fixing temperature when the clamping part width is 6 mm is the reference + 5°C. In other words, in Comparative Example 7, when the clamping part width is in the range of 6 mm to 10 mm, the fixing temperature varies by 5°C. The results of other configurations will be described below with reference to these results.

[0695] In Comparative Example 8, the fixing temperature was -10°C when the clamping portion width was 10 mm or 8 mm, and +0°C when the clamping portion width was 6 mm. Compared to the results obtained when the clamping portion width was the same as in Comparative Example 7, the fixing temperature in Comparative Example 8 was lower than that in Comparative Example 7 under all conditions, and the effect of improving fixing performance by shifting the film unit upstream in the conveying direction was observed. On the other hand, in Comparative Example 8, the fixing temperature varied by 10°C when the clamping portion width was in the range of 6 mm to 10 mm, which was inferior to Comparative Example 7 in terms of fixing performance stability. In other words, by shifting the film unit upstream in the conveying direction relative to the pressure roller, stronger pressure was applied downstream of the clamping portion N in the conveying direction than upstream, thus improving fixing performance. However, since the heating element and heater may extend outward from the clamping portion N in the offset film unit configuration, the stability of fixing performance deteriorates with changes in the clamping portion width.

[0696] In Comparative Example 9, the fixing temperature was -15°C when the clamping portion width was 10 mm and 8 mm, and +5°C when the clamping portion width was 6 mm. Comparing the results obtained when the clamping portion width was the same, compared with Comparative Examples 7 and 8, in Comparative Example 9, the fixing temperature was lower when the clamping portion width was 10 mm and 8 mm, and the fixing ability was further improved. On the other hand, compared with Comparative Examples 7 and 8, in Comparative Example 9, when the clamping portion width was in the range of 6 mm to 10 mm, the fixing temperature changed by 15°C, and the stability of the fixing performance further deteriorated. In other words, the offset of the membrane unit to the upstream side in the transport direction led to a decrease in fixing temperature and an improvement in fixing performance, but at the same time, it also reduced the stability of the fixing performance relative to the change in the clamping portion width.

[0697] In Example 13-1, the fixing temperature was reference +0°C when the clamping part width was 10 mm and 8 mm, and the fixing temperature was reference +5°C when the clamping part width was 6 mm. The fixing temperature and the change of fixing temperature were similar to those in Comparative Example 7.

[0698] In Example 13-2, the fixing temperature was -15°C when the clamping part width was 10 mm and 8 mm, and -10°C when the clamping part width was 6 mm. Comparing the results obtained with the same clamping part width, the fixing temperature was lower under all conditions in Example 13-2 compared to Comparative Example 7. An improved fixing performance was observed by changing the heater shape and applying stronger pressure and heating on the downstream side of the clamping part along the conveying direction. Furthermore, the fixing temperature variation was 5°C when the clamping part width was between 6 mm and 10 mm in Example 13-2, similar to Comparative Example 7. In other words, compared to the configuration in the prior art, the configuration of Example 13-2 can reduce the fixing temperature without compromising the stability of the fixing performance.

[0699] In Example 13-3, the fixing temperature is referenced at 10 mm and 8 mm for clamp widths, and at 10 mm for clamp width. These results are similar to those in Example 13-2. In other words, a larger protrusion Pt does not lead to a further reduction in fixing temperature, and only requires the protrusion Pt to be equal to or greater than a specific amount that improves fixing performance. Compared to the configuration in the prior art, in Example 13, by setting the protrusion Pt of heater 4022 to be equal to or greater than 20 μm, the recording material can be stably heated at a lower fixing temperature with lower power consumption.

[0700] Similar results to those in Example 13 were obtained in Example 14 compared to Example 13, which had the same protrusion amount Pt. In other words, even in configurations including three or more heating elements, the fixing temperature can be reduced without compromising the stability of fixing performance, even compared to configurations in the prior art, by making the downstream side of the heater in the conveying direction protrude toward the pressure roller side.

[0701] Compared to Example 13, which has the same protrusion amount Pt, similar results were obtained in Example 15. In other words, even in a configuration where the substrate made of metal has an insulating layer, the fixing temperature can be reduced without compromising the stability of fixing performance, compared to the configuration in the prior art.

[0702] As described above, by providing a heater with a larger heat output on the downstream side of the conveying direction than on the upstream side, and by making the contact surface between the heater and the film protrude towards the pressure roller side (second rotating body side), the fixing temperature can be reduced without compromising the stability of the fixing performance. In other words, by employing a configuration in which heating is performed more concentratedly and pressure is applied more forcefully on the downstream side of the clamping section in the conveying direction than on the upstream side, without shifting the film unit relative to the pressure roller, heating can be performed stably with low power consumption. However, for the configuration where the film unit is shifted relative to the pressure roller, the present invention can be appropriately applied as long as the shift amount is set to a level that stably forms the width of the clamping section.

[0703] It should be noted that although in each of the above embodiments the first and second regions are formed in a planar shape, and the contact surface between the heater and the inner circumferential surface of the membrane is formed in the form of a height difference, the configuration of the present invention is not limited to this. As variations, configurations including a third region between the first and second regions that is lower than the first region and higher than the second region, or configurations in which the first region is formed as a curved surface instead of a planar shape, are conceivable. Furthermore, as variations, configurations in which the coating is not in the form of a height difference (step difference), but rather gradually slopes towards the pressure roller side as it moves downstream in the conveying direction.

[0704] Furthermore, although the heat output of each heating element is made different by changing the width of the heating element in each of the above embodiments, the method of achieving the difference in heat output of the heating elements is not limited to this, and a configuration of individually controlling the power supply to the heating elements can also be used.

[0705] Furthermore, although setting the protrusion amount Pt to be equal to or greater than 20 μm in Examples 13, 14, and 15 can achieve both a reduction in fixing temperature and stable fixing performance, these values ​​can vary depending on the configuration of each component, the material, etc. Since a reduction in fixing temperature cannot be achieved if the protrusion amount Pt is too small, and there is a concern that bending tendencies may occur in the recording material if the protrusion amount Pt is too large, it is important to select an appropriate value under various conditions.

[0706] Example 16

[0707] Next, we will use Figure 68 The description is based on the configuration of heater 4082 in Example 16. Figure 68 This is a cross-sectional view of heater 4082 according to Example 16. Similar reference numerals will be applied to configurations in Example 16 that are similar to those in Example 13, and their descriptions will be omitted.

[0708] The heater 4082 in this embodiment includes an elongated plate-shaped substrate 4821 made of metal, two heating elements 4822 that heat up in response to energizing the substrate, a coating 4823 serving as a protective layer for the heating elements 4822, and an insulating layer 4824 for maintaining insulation between the heating elements 4822 and the substrate 4821. Furthermore, the heater 4082 includes a coating 4825 disposed on a surface of the substrate 4821 opposite to the surface where the heating elements 4822 and the insulating layer 4824 are located, to prevent warping of the substrate 4821. Note that in this embodiment, the surface of the substrate 4821 where the heating elements 4822 and the insulating layer 4824 are located is the surface facing the heater support 4021, rather than the inner peripheral surface of the membrane 4023, which corresponds to the opposite side to each of the above embodiments. Similar to Example 15, the substrate 4821 in this embodiment is a ferritic stainless steel substrate (SUS430:18Cr stainless steel) with a width of 11 mm, a length of 270 mm and a thickness of 0.5 mm.

[0709] The heater 4082 also includes power supply electrodes and conductive patterns for supplying power to the heating element 4822, and the conductive patterns are further covered with a coating 4823. The heater 4082 is disposed inside the fixing device such that the coating 4823 abuts against the inner peripheral surface of the film 4023. Since the configuration and formation method of the power supply electrodes and conductive patterns are similar to those in the comparative example, their description will be omitted. The configuration of the heating element 4822 and the coating 4823, which are features of the present invention, will be described in detail below.

[0710] An insulating layer 4824 is provided using an insulating glass paste to establish insulation between the substrate 4821 and the heating element 4822. For the insulating layer 4824, the insulating glass paste is applied to the substrate 4821 by screen printing, the resulting article is dried at 180°C and sintered at 850°C to form the insulating layer 4824. The sintered insulating layer 4824 has a width of 10.5 mm, a length of 260 mm, and a height of 50 μm. As described above, in this embodiment, the insulating layer 4824 is disposed in the heater 4082 on the surface of the substrate 4821 opposite to the surface facing the film 4023.

[0711] Subsequently, heating element paste is applied to the insulating layer 4824 via screen printing, and the resulting article is dried at 180°C and sintered at 850°C to form two heating elements 4822. Of the two sintered heating elements 4822, the first heating element 4822a, located downstream of the conveying direction of the recording material P, has a width of 2.2 mm, a length of 230 mm, and a thickness of 15 μm, thus having a greater heat output compared to the second heating element 4822b located upstream of the conveying direction. On the other hand, the second heating element 4822b has a width of 3.0 mm, a length of 230 mm, and a thickness of 15 μm, and a folded heating pattern is formed by connecting the two heating elements 4822a and 4822b to a conductive pattern at one end in the longitudinal direction of the heater 4082. In other words, the heater 4082 in this example has a configuration in which two heating elements with different heat outputs are disposed on the insulating layer along the conveying direction, and each heating element is disposed on a surface of the substrate opposite to the surface facing the film.

[0712] Subsequently, a glass paste was applied to the insulating layer 4824, the heating element 4822, and the conductive pattern by screen printing using a glass paste similar to that used in the comparative example and the aforementioned examples. Furthermore, the glass paste was applied to the side of the substrate 4821 opposite to the surface where the insulating layer 4824 was applied by screen printing. The resulting article was dried at 180°C and sintered at 850°C, thereby forming a coating on both surface sides of the substrate 4821 to prevent warping of the substrate 4821 after sintering. Furthermore, the glass paste was again applied to the first heating element 4822a by screen printing, and the resulting article was dried at 180°C and sintered at 850°C, thereby forming a coating 4823 with a protruding shape.

[0713] The heater 4082 includes a first region 4823a that overlaps with the first heating element 4822a and a second region 4823b that overlaps with the second heating element 4822b when viewed along the thickness direction of the substrate 4821 in the surface of the coating 4823 that abuts against the inner peripheral surface of the film 4023. At this time, in the fixing device 4009, along the thickness direction of the substrate 4821, the first region 4823a is positioned to protrude towards the side closer to the pressure roller 4030 compared to the second region 4823b.

[0714] The coating 4823 of the contact film 4023 has a width of 10.5 mm and a length of 260 mm, and the coating 4825 covering the heating element 4822 has a width of 10.5 mm, a length of 260 mm, and a thickness of 60 μm. Furthermore, by varying the thickness of the coating 4823 used for the evaluation tests described below, three types were created in Example 16. In Examples 16-1, 16-2, and 16-3, the height Ha from the substrate 4821 to the surface of the coating 4823 in the first region 4823a is 75 μm, 80 μm, and 85 μm, respectively. The height Hb from the substrate 4821 to the surface of the coating 4823 in the second region 4823b is 65 μm, 60 μm, and 55 μm, respectively. In other words, the protrusion Pt in Examples 16-1, 16-2, and 16-3 is 10 μm, 20 μm, and 30 μm, respectively.

[0715] Effects and advantages of Example 16

[0716] To verify the advantages of the present invention, a fixing performance evaluation test was performed using a fixing apparatus including the heater in this embodiment. Examples 16-1, 16-2, and 16-3 include a heater 4082 (see...). Figure 68 The results of the evaluation tests and the effects of improved fixing performance on power saving and stable fixing performance will be described below.

[0717] The fixing performance evaluation test was conducted under conditions similar to those described above. In other words, a completely black pattern obtained by printing toner across the entire surface was used as the evaluation image pattern, and the environment was set to a normal temperature and humidity environment of 23°C and 50% RH. As the paper feeding condition, three evaluation image patterns were continuously fed from a cold state. Multiple tests were performed with varying the set temperature of the fixing unit 4009, and the fixing temperature for each configuration was measured by taking the lower limit of the set temperature at which no image pattern defects were observed in each configuration. Furthermore, tests were performed with varying rubber hardness of the pressure roller 4030 and spring coefficient of the pressure spring 4045, changing the clamping width to 10mm, 8mm, and 6mm, to also evaluate the stability of the fixing performance.

[0718] The test results for each example and the comparative examples used for comparison are shown together in Table 9. Note that in Comparative Example 7, the fixing temperature when the clamping width is 10 mm is considered the baseline value, and the difference between the fixing temperature and the baseline value is shown as the evaluation result. Furthermore, when the clamping width is changed using a fixing device with the same configuration, the difference between the maximum and minimum fixing temperatures is shown as the change in fixing temperature.

[0719] [Table 9]

[0720]

[0721] In Example 16-1, the fixing temperature was base +5°C when the clamping portion width was 10 mm and 8 mm, and base +8°C when the clamping portion width was 6 mm. Compared to Comparative Example 7, the fixing temperature increased at any width of the clamping portion. This is believed to be because: the protrusion amount Pt is small and cannot achieve a sufficient effect in reducing the fixing temperature, and because the heating element is moved away from the inner peripheral surface of the film, the heat from the heating element is difficult to transfer to the film quickly. On the other hand, in Example 16-1, the fixing temperature changed by 3°C in the range of clamping portion width from 6 mm to 10 mm, which is less than the fixing temperature changes in Comparative Example 7 and Examples 13-1, 14-1, and 15-1 above.

[0722] In Example 16-2, the fixing temperature was -10°C when the clamping part width was 10 mm and 8 mm, and -7°C when the clamping part width was 6 mm. Comparing the results obtained with the same clamping part width as Comparative Example 7, the fixing temperature was low under all conditions in Example 16-2, and the improved fixing performance was observed by changing the shape of the heater, applying stronger pressure on the downstream side of the clamping part along the conveying direction, and applying stronger heat. Furthermore, the fixing temperature variation was 3°C when the clamping part width in Example 16-2 was in the range of 6 mm to 10 mm, which is less than the fixing temperature variation in Comparative Example 7. In other words, compared to the configuration in the prior art, the configuration of Example 16-2 can improve the stability of fixing performance and reduce the fixing temperature.

[0723] On the other hand, when comparing the results for the same clamping width between Example 16-2 and Examples 13-2, 14-2, and 15-2, the fixing temperature is higher under all conditions in Example 16-2. However, in Example 16-2, the fixing temperature variation is 3°C when the clamping width is in the range of 6 mm to 10 mm, which is less than the fixing temperature variation in Examples 13-2, 14-2, and 15-2. The reason for these differences is that, compared to Examples 13-2, 14-2, and 15-2, the configuration in Example 16-2, in which the heating element is positioned away from the inner circumferential surface of the film, prolongs the time required for heat transfer from the heating element to the inner circumferential surface of the film.

[0724] In Example 16-3, the fixing temperature is referenced at 10°C when the clamping part width is 10 mm and 8 mm, and at 7°C when the clamping part width is 6 mm. These results are similar to those in Example 16-2.

[0725] As described above, according to the present invention, even in a configuration where the heating element and the insulating layer are disposed on a surface of the substrate opposite to the surface facing the inner peripheral surface of the film, the fixing temperature can be reduced without compromising the stability of the fixing performance relative to the clamping portion. Furthermore, the surface of the substrate on which the heating element is disposed can be appropriately selected based on the priority between the effect of reducing the fixing temperature and the effect of improving the stability of the fixing performance.

[0726] Examples of configurations or concepts disclosed in the foregoing embodiments will be described below. However, these are merely examples, and the disclosure of the foregoing embodiments is not limited to the configurations or concepts described below.

[0727] Configure D1

[0728] A heater, comprising:

[0729] Multiple heating elements;

[0730] Coating; and

[0731] An elongated substrate, the substrate including a heating element and a coating disposed thereon.

[0732] Among the plurality of heating elements, the first heating element, which extends along the longitudinal direction of the substrate, is positioned at a different location from the second heating element in a transverse direction orthogonal to the longitudinal direction of the substrate.

[0733] The heat output of the first heating element is greater than that of the second heating element.

[0734] When the coating is viewed from a surface opposite to the surface of the substrate along the thickness direction of the substrate, which is orthogonal to the longitudinal and transverse directions, the coating includes a first region overlapping the first heating element and a second region overlapping the second heating element.

[0735] The height from the substrate to the first region is greater than the height from the substrate to the second region.

[0736] Configure D2

[0737] In the heater described according to configuration D1

[0738] The plurality of heating elements are disposed on the same surface as the surface of the substrate that has the coating, and

[0739] The coating covers the plurality of heating elements.

[0740] Configure D3

[0741] In the heater according to configuration D1, the plurality of heating elements are disposed on the surface of the substrate opposite to the surface on which the coating is provided.

[0742] Configure D4

[0743] In the heater described according to any of the configurations D1 to D3

[0744] The substrate is made of metal, and

[0745] The heater also includes an insulating layer disposed between the substrate and the plurality of heating elements.

[0746] Configure D5

[0747] A heating device that simultaneously heats and clamps and transports recording material using a clamping part, the heating device comprising:

[0748] First body of revolution;

[0749] The heater, according to any one of configurations D1 to D4, is disposed within the internal space of the first rotating body; and

[0750] The second rotating body forms a clamping part with the heater via the first rotating body.

[0751] Configure D6

[0752] In the heating device according to configuration D5, the first heating element is disposed upstream of the second heating element in the material conveying direction.

[0753] Configure D7

[0754] In the heating device according to configuration D6, the first region and the second region extend in the longitudinal direction in such a way that they cover the entire width of the recording material.

[0755] Configure D8

[0756] In the heating device according to configuration D6 or D7, the first region and the second region are planes parallel to the surface of the recording material.

[0757] Configure D9

[0758] In the heating device according to any of the configurations D6 to D8, the first region is located on a side that is at least 20 μm closer to the second rotating body than the second region in the thickness direction.

[0759] Configure D10

[0760] In the heating device according to any of the configurations D6 to D9, the width of the first heating element in the conveying direction is smaller than the width of the second heating element in the conveying direction.

[0761] Configure D11

[0762] In the heating device according to any of the configurations D6 to D10, the thickness of the coating in the first region is greater than the thickness of the coating in the second region.

[0763] Configure D12

[0764] In the heating device described according to any of the configurations D6 to D11

[0765] The heater comprises three or more heating elements, and

[0766] The first heating element is located on the downstream side of the conveying direction and has the largest heat output among the heating elements.

[0767] Configure D13

[0768] In the heating device described according to any of the configurations D5 to D12

[0769] The first rotating body is a tubular membrane, and

[0770] The second rotating body is a roller.

[0771] Configure D14

[0772] An image forming apparatus, comprising:

[0773] An image forming unit that forms an image on a recording material; and

[0774] According to any of the configurations D5 to D13, the heating device fixes the image formed on the recording material onto the recording material.

[0775] Furthermore, in heating devices consisting of heaters, films, pressure rollers, etc., there are configurations that balance heat transfer efficiency and rigidity by thinning the metal substrate of the heater and bending the cross-sectional shape of the substrate. In such configurations, the metal substrate undergoes thermal expansion when heated, resulting in significant dimensional changes, particularly in the longitudinal direction. In configurations where the heater is located at one end in the longitudinal direction, it is difficult to properly position the two ends of the heating element of the heater relative to the heated material, such as recording material. If the positioning of the heating element in the heater is offset relative to the heated material due to the dimensional changes of the substrate in the longitudinal direction of the heater, a temperature difference may occur at the two ends of the recording material; for example, the temperature may rise significantly at one end of the recording material while the temperature at the other end does not rise sufficiently. Uneven heating of the recording material will lead to poor image quality or degradation of curling performance. Therefore, a heating device capable of uniformly heating both ends of the recording material in the width direction will now be described.

[0776] Example 17

[0777] Example 17 of the invention will be described using the accompanying drawings. The description will proceed in the order of the overall configuration of the image forming apparatus as a color laser beam printer, the configuration of the fixing unit, and the configuration of the heater and peripheral components.

[0778] Overall configuration of image forming equipment

[0779] Will use Figure 69 A general overview of the overall configuration of the image forming apparatus is provided. The recording material 5002, loaded and contained in the supply tray 5001, is supplied to the supply roller 5003, which rotates clockwise in the figure, and then to the transport roller 5004 and the transfer clamping part formed by the in-belt drive roller 5005 and the secondary transfer roller 5006.

[0780] The photosensitive drums 5007Y, 5007M, 5007C, and 5007K, which serve as image carriers constituting the image forming units, rotate counterclockwise in the figure. In each image forming unit, an electrostatic latent image is sequentially formed on the outer peripheral surface of each photosensitive drum by a laser from a laser scanner 5008. The electrostatic latent image is then developed by developing rollers 5009Y, 5009M, 5009C, and 5009K, forming a toner image. The primary transfer units 5010Y, 5010M, 5010C, and 5010K transfer the toner image formed on the photosensitive drums 5007Y, 5007M, 5007C, and 5007K to the intermediate transfer belt 5011 by applying pressure and voltage. The intermediate transfer belt 5011 is a cylindrical and annular strip film tensioned and mounted on the belt drive roller 5005, tension roller 5012, etc. The drive roller 5005 inside the drive belt rotates clockwise in the figure, and the intermediate transfer belt 5011 moves at a speed that is basically the same as the moving speed of the surface of the photosensitive drum 5007.

[0781] In the case of forming a color image, yellow, magenta, cyan, and black toner images are developed on photosensitive drums 5007Y, 5007M, 5007C, and 5007K, respectively. The toner images formed on the photosensitive drums 5007Y, 5007M, 5007C, and 5007K are sequentially transferred to the intermediate transfer belt 5011 by the primary transfer units 5010Y, 5010M, 5010C, and 5010K, respectively. Then, the toner images formed on the intermediate transfer belt 5011 are jointly transferred to the recording material 5002, which is fed to the transfer clamping section of the in-belt drive roller 5005 and the secondary transfer roller 5006.

[0782] Furthermore, the recording material 5002 with the toner image transferred is fed to a fixing device serving as a fixing unit. The recording material is fed into the fixing clamping section F of the heating unit 5013 and pressure roller 5014 within the fixing device, where it is subsequently heated and pressurized, and the toner image is fixed onto the recording material 5002. The recording material 5002 with the fixed toner image is clamped and conveyed by the discharge roller 5015 and discharge feeder 5016, and is subsequently discharged to the discharge placement platform outside the main body of the image forming apparatus.

[0783] Configuration of fixing device

[0784] Next, the configuration and operation of the fixing device will be described. In this example, a tensionless film heating system fixing device is used as an example of a heating device. The fixing device in this example is a device in which an annular strip (or cylindrical) heat-resistant film is used, at least a portion of the periphery of which is always kept tensionless (in a state where no tension is applied to it), and the film is driven to rotate by the rotational driving force of the pressure member. Figure 70 This is a cross-sectional view of the fixing device, which is the main part of this example.

[0785] The heating unit 5013 includes a cylindrical membrane 5017, a heater 5018 that is internally connected to and heats the membrane 5017, a heater support 5019 with excellent heat resistance, and a support rod 5020 with excellent rigidity. The membrane 5017 is, for example, a cylindrical plastic film with high heat resistance and high thermal conductivity. The heater 5018 is a heating element that heats up in response to an electrical source (not shown), and is obtained by applying an insulating coating to a substrate made of a metal substrate and applying a conductor thereto. The heater 5018 is supported in a state where it is assembled and fixed to a groove in the heater support 5019. The membrane 5017 is attached to cover the outer periphery of the heater 5018, the heater support 5019, and the support rod 5020, and is capable of rotational movement.

[0786] The heating unit 5013 is configured such that the membrane 5017, acting as a first rotating body, comes into contact with the pressure roller 5014, acting as a second rotating body, by receiving the force of a pressure spring. The pressure roller 5014 is composed of a core metal 5014a and a heat-resistant elastic material layer 5014b, which is molded into a roller shape on the outer periphery of the core metal 5014a. Because the pressure roller 5014 has an elastic surface, the heating unit 5013 and the pressure roller 5014 form a fixing clamping portion F with a predetermined width and establish pressure contact with a predetermined pressure. Furthermore, the pressure roller 5014 is driven by a drive chain (not shown) to rotate at a predetermined circumferential speed. The rotation of the pressure roller 5014 generates friction between the membrane 5017 and the pressure roller 5014, and the membrane 5017 performs a driven rotational movement relative to the pressure roller 5014.

[0787] With the pressure roller 5014 and membrane 5017 rotating and the heater 5018 energized and heated, the recording material 5002 carrying the unfixed toner image is introduced into the fixing clamping part F between the membrane 5017 and the pressure roller 5014, and is clamped and transported by the fixing clamping part F. During the clamping and transport of the recording material, the heat from the heater 5018 is applied to the recording material 5002 through the membrane 5017, and the unfixed toner image is melted and fixed onto the recording material 5002 by heating and pressurization.

[0788] Configuration of heater and peripheral components

[0789] Will use Figure 71 , 72 Sections 5018 and 73 describe the configuration details of the heater 5018 and its surrounding components. Figure 71 This is an exploded view of the heater 5018, which is the main component in this example, and its surrounding components. Figure 72 It is an exploded view that only extracts heater 5018 and heater bracket 5019. Figure 73 This is a completed view showing the heater 5018 and heater support 5019 engaged with each other. The heater 5018 is a longer member in the direction of the rotation axis of the pressure roller 5014, and its position relative to the heater support 5019 in the transverse direction orthogonal to the longitudinal direction is determined by the heater 5018 being held in a groove within the heater support 5019. Furthermore, the two ends of the heater 5018 in the longitudinal direction are held by a clamping member 5021 and a power supply unit 5022, preventing the heater 5018 from detaching from the heater support 5019. The clamping member 5021 and the power supply unit 5022 are members that hold the heater 5018 so that it does not detach from the heater support 5019 in the thickness direction orthogonal to the longitudinal and transverse directions of the heater 5018, and are not members that strongly inhibit the movement of the heater 5018 relative to the heater support 5019 in the longitudinal direction. The power supply unit 5022 supplies power from a power source (not shown) to a power supply unit located at the longitudinal end of the heater 5018.

[0790] Safety element 5023, used to prevent damage in case of excessive temperature rise in heater 5018, is held in safety element bracket 5024 and pressed against heater 5018 by safety element spring 5025 via spacer 5026. Temperature sensing member 5027, which detects the temperature of heater 5018, is biased against heater 5018 by temperature sensing spring 5028. Heater bracket 5019 is held by strut 5020, and its position in the longitudinal direction relative to the image forming apparatus body is fixed by end retaining members 5030 and 5031 relative to the side plate (which is configured to clamp the two ends of heater bracket 5019 in the longitudinal direction).

[0791] The heater 5018 in this example includes: two heating elements 5181 extending along the longitudinal direction of the heater 5018 as heating portions on a metal substrate 5182; and a heater protrusion 5018c located at the center of the heating elements 5181 in the longitudinal direction. The heater protrusion 5018c is provided at both ends of the substrate 5182 in the transverse direction and protrudes toward the heater support 5019 side perpendicular to the surface of the substrate 5182. Furthermore, in this example, the heater protrusion 5018c is configured to be located at the center in the width direction orthogonal to the transport direction of the recording material transported by the clamping portion. The heater protrusion 5018c can be formed by pre-setting a portion serving as the heater protrusion on a flat substrate and folding that portion, or by another method of joining a component to the substrate. Stainless steel, nickel, copper, aluminum, or alloys containing such materials as the main material are suitable materials for the substrate.

[0792] The heater holder 5019 is a support member disposed within the internal space of the membrane 5017 and supporting the heater 5018. The heater holder 5019 has the membrane 5017 loosely fitted thereto and also has a guiding function that guides the membrane 5017 to rotate while maintaining sliding contact with the inner circumferential surface of the membrane 5017. For the heater holder 5019, a high heat-resistant resin, such as polyimide, polyamide-imide, PEEK, PPS, or liquid crystal polymer, or a composite material of such resin and ceramics, metals, glass, etc., can be suitably used. Furthermore, the heater holder 5019 in this example includes a heater holder hole 5019c that engages with the heater protrusion 5018c of the heater 5018.

[0793] The heater bracket hole 5019c abuts against the heater protrusion 5018c in two directions in the longitudinal direction, thereby restricting the relative movement of the heater protrusion 5018c with respect to the heater bracket hole 5019c in the longitudinal direction. In other words, the longitudinal direction of the heater 5018 is positioned relative to the heater bracket 5019 by the heater protrusion 5018c (which abuts against and is fitted to the heater bracket hole 5019c, which is the positioned part). At this time, one end 5018a of the heater 5018 in the longitudinal direction and the other end 5018b on the opposite side of this end 5018a are provided to have a gap relative to the groove of the heater bracket 5019 in the longitudinal direction. The gap amount is set to the amount by which one end 5018a and the other end 5018b of the heater 5018 do not contact the heater bracket 5019 when the heater 5018 causes thermal expansion.

[0794] Effects and advantages of the present invention

[0795] Will use Figure 74A and 74B Describe the effects and advantages of the present invention. Figure 74A This is a schematic diagram illustrating the state of thermal expansion caused by the heater in this example. Figure 74B This is a schematic diagram illustrating the state of thermal expansion caused by the heater in a comparative example of a prior art configuration. In the various figures, it is assumed that the recording material 5002, which has a length L in the width direction, is fed, and the shape of the heater after deformation, held by the heater support 5019, is shown by dashed lines.

[0796] In this example, the position of heater 5018 relative to heater support 5019 in the longitudinal direction is determined by heater protrusion 5018c. In other words, as Figure 74A As shown, when the heater 5018 causes thermal expansion, the heating element 5181 of length L expands uniformly on the left and right sides of the longitudinal direction relative to the heater protrusion 5018c. Since the heater protrusion 5018c is located at the center in the width direction orthogonal to the transport direction of the recording material 5002, the heating element 5181 expands uniformly on the left and right sides of the center in the width direction of the recording material 5002. In other words, when the deformation of the heating element 5181 at one end 5181a in the longitudinal direction is defined as y1, and the deformation of the heating element 5181 at the other end 5181b opposite to this end 5181a is defined as y2, in this example y1 = y2, that is, the deformation on the left and the deformation on the right become equal, so the two ends of the recording material 5002 are heated uniformly in the width direction.

[0797] Next, we will use Figure 74B The behavior of a heater 5068 in a comparative example of a prior art configuration during thermal expansion is described, where the heater 5068 includes two heat generating elements 5681 each having a length L and positioned at one end 5068a of the heater 5068 in the longitudinal direction relative to a heater holder 5019. In the comparative example of the prior art configuration that does not include a heater protrusion, if the heater 5068 undergoes thermal expansion, deformation occurs relative to the positioned one end 5068a of the heater, and this one end 5068a and the opposite other end 5068b thus deform most significantly. Since the amount of deformation caused by thermal expansion is proportional to the distance from the reference position, when the deformation amount of the heat generating element 5681 at one end 5681a in the longitudinal direction is defined as z1 and the deformation amount at the other end 5681b opposite to this one end 5681a is defined as z2, z1 < z2 in the comparative example. At this time, the one end 5681a of the heat generating element 5681 deforms toward the outer side of the recording material 5002, while the other end 5681b deforms toward the inner side of the recording material 5002. In other words, since the one end 5681a of the heat generating element 5681 is located on the outer side of the recording material 5002 relative to the widthwise end of the recording material 5002, and the other end 5681b is located on the inner side of the recording material 5002 relative to the widthwise end of the recording material 5002, the two widthwise ends of the recording material 5002 are not uniformly heated.

[0798] In the prior art configuration, the one end side and the other end side of the heat generating element in the longitudinal direction behave differently, that is, as described above, when the heater undergoes thermal expansion, they point toward the outer side or the inner side of the recording material, and the manner in which heat is applied may vary at the two widthwise ends of the recording material. In particular, if the end of the heat generating element is placed inside the recording material, the end portion of the recording material is likely to be insufficiently heated. However, in consideration of energy saving and the like, it is not preferable for the heat generating element to extend to an excessively long length in the longitudinal direction. On the other hand, in the present invention, since the two ends of the heat generating element in the longitudinal direction cause thermal expansion toward the outer side of the recording material, heat is uniformly supplied to the two widthwise ends of the recording material. In other words, not only from the difference in the amount of deformation but also from the perspective of the behavior during deformation, the two widthwise ends of the recording material are more easily heated uniformly in the present invention than in the prior art configuration.

[0799] As described above, by providing a positioning portion and a positioned portion for determining the position of the heater relative to the heater holder in the longitudinal direction at the center of the heat generating portion constituted by the heat generating elements and the like, and by assembling the heater to the heater holder, the two widthwise ends of the recording material can be uniformly heated.

[0800] It should be noted that although the heater protrusion 5018c was positioned at the center of the heating element 5181 and the recording material 5002 in the longitudinal direction in the foregoing embodiments, the heater protrusion 5018c need not be strictly centered when applying the present invention. This is because, by positioning the locating portion inside the heating element in the longitudinal dir...

Claims

1. A heater, comprising: A slender substrate made of metal; An insulating layer disposed on the substrate; as well as Heating element disposed on the insulating layer Wherein, in the case that the region including the center of the substrate is defined as the first region, along the lateral direction, a region closer to one end side than the first region is defined as the second region, and a region closer to another end side than the first region is defined as the third region, the lateral direction being orthogonal to the longitudinal direction of the surface of the substrate on which the insulating layer is provided, the first region being planar, and The second region and the third region are bent from the first region along the thickness direction of the substrate, which is orthogonal to the longitudinal and transverse directions. The second region includes: A first curved portion, the first curved portion being bent to approach the heating element side from the first region along the thickness direction; and The second curved portion bends from the first curved portion along the transverse direction. The second curved portion includes a plane parallel to the first region. Wherein, the second region and the third region bend from the first region along the entire substrate in the longitudinal direction. Wherein, the distance from the plane of the first region to the plane of the second curved portion in the thickness direction is greater than the thickness of the insulating layer. The insulating layer is formed directly on the plane of the first region of the substrate made of metal, and The heating element is formed directly on the insulating layer.

2. The heater according to claim 1, wherein, The third region includes a third bend that is bent to approach the heating element side from the first region along the thickness direction.

3. The heater according to claim 2, wherein, The third region includes a fourth bend that bends from the third bend along the lateral direction.

4. The heater according to claim 3, wherein, The fourth curved portion includes a plane parallel to the first region.

5. The heater according to claim 4, wherein, In the thickness direction, the distance from the plane of the first region to the plane of the fourth bend is greater than the thickness of the insulating layer.

6. The heater according to claim 1, wherein, In the second and third regions, no insulating layer is provided on the substrate.

7. The heater according to claim 1, wherein, When the surface on which the insulating layer is provided is defined as the first surface, no insulating layer is provided on the second surface of the substrate on the side opposite to the first surface along the thickness direction.

8. The heater according to claim 1, in, When the insulating layer containing the heating element is defined as the first insulating layer and the surface containing the first insulating layer is defined as the first surface, the substrate has a second insulating layer on a second surface opposite to the first surface along the thickness direction, where no heating element is provided. The first insulating layer is thicker than the second insulating layer in the thickness direction.

9. A heating device, comprising: First body of revolution; The heater according to claim 1, wherein the heater is disposed in the internal space of the first rotating body; A second rotating body, the second rotating body forming a clamping portion with the heater via the first rotating body; and A temperature detection unit that detects the temperature of the heater. The temperature detection unit is disposed on a surface opposite to the surface on which the insulating layer containing the heating element is located along the thickness direction.

10. The heating device according to claim 9, wherein, The second region and the third region abut against the first rotating body.

11. The heating device according to claim 9, in, The first rotating body is a tubular membrane, and The second rotating body is a roller.

12. A heating device, comprising: First body of revolution; The heater includes an elongated substrate made of metal, an insulating layer disposed on the substrate, and a heating element disposed on the insulating layer, the heater being disposed in the internal space of the first rotating body; as well as The second rotating body forms a clamping portion with the heater via the first rotating body. Wherein, in the case that the region including the center of the substrate is defined as the first region, along the transverse direction, a region closer to one end side than the first region is defined as the second region, and a region closer to another end side than the first region is defined as the third region, the transverse direction being orthogonal to the longitudinal direction of the surface of the substrate on which the insulating layer is provided, the first region being planar, and the second and third regions being bent to be positioned closer to the clamping portion side than the first region in the thickness direction of the substrate, which is orthogonal to the longitudinal and transverse directions. The second region includes: A first curved portion, the first curved portion being bent to approach the heating element side from the first region along the thickness direction; and The second curved portion bends from the first curved portion along the transverse direction. The second curved portion includes a plane parallel to the first region. Wherein, the second region and the third region bend from the first region along the entire substrate in the longitudinal direction. Wherein, the distance from the plane of the first region to the plane of the second curved portion in the thickness direction is greater than the thickness of the insulating layer. The insulating layer is formed directly on the plane of the first region of the substrate made of metal, and The heating element is formed directly on the insulating layer.

13. The heating device according to claim 12, wherein, The third region includes a third bend that is bent to approach the heating element side from the first region along the thickness direction.

14. The heating device according to claim 13, wherein, The third region includes a fourth bend that bends from the third bend along the lateral direction.

15. The heating device according to claim 14, in, The first region includes a plane, and The fourth curved portion includes a plane parallel to the first region.

16. The heating device according to claim 15, wherein, In the thickness direction, the distance from the plane of the first region to the plane of the fourth bend is greater than the thickness of the insulating layer.

17. The heating device according to claim 12, wherein, In the second and third regions, no insulating layer is provided on the substrate.

18. The heating device according to claim 12, wherein, When the surface on which the insulating layer is provided is defined as the first surface, no insulating layer is provided on the second surface of the substrate opposite to the first surface in the thickness direction.

19. The heating device according to claim 12, in, When the insulating layer containing the heating element is defined as the first insulating layer and the surface containing the first insulating layer is defined as the first surface, the substrate has a second insulating layer on a second surface opposite to the first surface along the thickness direction, where no heating element is provided. The first insulating layer is thicker than the second insulating layer in the thickness direction.

20. An image forming apparatus, comprising: An image forming unit that forms an image on a recording material; as well as The heating device according to claim 12 fixes the image formed on the recording material onto the recording material.

Images