Fixing device and image forming apparatus

Abstract

To prevent the positional displacement of a heating body of a fixation device, and maintain the travel stability of a film until the end of the life of the device before a lubricant for maintaining the sliding performance of the film runs out.SOLUTION: The fixation device includes a coil spring B1 for biasing a heater 11 held in a groove hole 12a of a holding member 12 to the downstream side in the conveyance direction. The coil spring B1 is provided on the upstream side in the conveyance direction of the holding member 12 and is provided outside a paper passage region as a region in the direction of the axis of rotation in which the recording medium which is the longest in the direction of the axis of rotation of recording mediums which can be conveyed by the fixation device 100 is conveyed.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a fixing device and an image forming apparatus, and more particularly to a heat fixing device mounted in an image forming apparatus such as an electrophotographic or electrostatic recording copying machine or a laser printer. [Background technology]

[0002] Film-heating type fixing devices are known as heat fixing devices installed in image forming apparatuses. Film-heating type fixing devices typically include a cylindrical film, a heating element that contacts the inner surface of the film, a holding member with a groove that holds the heating element, and a pressure roller that forms a fixing nip with the heating element via the film. Film-heating type fixing devices heat-fix a toner image while transporting a recording material bearing a toner image through the fixing nip. The heating element is held by being fitted into a groove provided in an insulating holder, which serves as the holding member. The width of the groove in the holding member is designed to be larger than the width of the heating element to ensure dimensional accuracy and stress relief due to differential thermal expansion during the heating process. The heating element moves downstream in the groove in the direction of film rotation due to frictional forces with the film, and the downstream end of the heating element abuts and is held against the downstream end (wall) of the groove in the holding member.

[0003] In film-heating fixing devices, the heater is assembled by abutting it against the downstream end of the groove in the holding member. However, the heater may shift upstream during subsequent work processes. Furthermore, when clearing a jam in the fixing device, the film may be rotated in the opposite direction to the fixing operation, which could cause the heater to shift upstream. If the heater shifts upstream, the heating area for the recording material in the fixing nip shifts from its predetermined position, potentially resulting in poor fixability. To address this issue, Patent Document 1, for example, discloses a configuration in which an elastic member is provided between the heater as the heater and the groove in the holding member. Patent Document 2, for example, discloses a configuration in which an elastic member is used to bias a gap filler member located adjacent to the heater.

[0004] In a film-heating fixing device, a lubricant is applied between the heater and the film to allow the film to slide and rotate. Typically, in the initial state of a film-heating fixing device, there is a sufficient amount of lubricant for the minimum amount needed between the heater and the film for lubrication. Therefore, the excess lubricant is temporarily stored in the gap between the heater and the groove of the holding member. Then, toward the end of the device's life, when the lubricant gradually runs out, the lubricant stored in the gap between the heater and the groove of the holding member is gradually supplied, thereby maintaining sliding performance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-123329 [Patent Document 2] Japanese Patent Application Publication No. 2019-179143 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional configuration, because a member is disposed between the heater and the groove of the holding member in the longitudinal paper passage area, it is difficult to retain sufficient lubricant in this gap, which can lead to a decrease in sliding properties toward the end of the device's life, and slippage can occur between the film and the recording material bearing the toner image.

[0007] The present invention was made under these circumstances, and aims to prevent the position of the heating element of the fixing device from shifting, while maintaining the running stability of the film so that the lubricant for maintaining the sliding performance of the film does not run out until the end of the device's life. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention has the following configuration.

[0009] (1) A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, the fixing device comprising: a flexible cylindrical rotating body; a heating body that is disposed inside the rotating body and extends in a direction of the rotation axis of the rotating body perpendicular to the transport direction, the heating body contacting the inner circumferential surface of the rotating body to supply heat to the rotating body; a holding member that has a groove that extends in the direction of the rotation axis longer than the heating body in the transport direction and holds the heating body in the groove; and a fixing member that is in pressure contact with the heating body via the rotating body and presses the heating body against the front surface of the rotating body. a pressure member that forms the fixing nip portion between itself and the outer surface of the rotating body; a lubricant that is applied between the rotating body and the heating body and that is held in the groove; and a biasing means that biases the heating body held in the groove toward the downstream side in the conveying direction, the biasing means being provided on the upstream side of the holding member in the conveying direction and outside a paper passing region that is a region in the rotation axis direction through which a recording material that has the longest length in the rotation axis direction among recording materials that can be conveyed by the fixing device is conveyed. The biasing means is a coil spring, and the holding member has a housing portion that houses the coil spring. A fixing device characterized by: (2) A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, the fixing device comprising: a flexible cylindrical rotating body; a heating body that is disposed inside the rotating body and extends in a direction of the rotation axis of the rotating body perpendicular to the transport direction, the heating body contacting the inner circumferential surface of the rotating body to supply heat to the rotating body; a holding member that has a groove that extends in the direction of the rotation axis longer than the heating body in the transport direction, the holding member holding the heating body in the groove; and a pressure unit that presses the heating body through the rotating body to form the fixing nip portion between the heating body and the outer surface of the rotating body. a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; and a biasing means for biasing the heating body held in the groove toward the downstream side in the conveying direction, wherein the biasing means is provided upstream of the holding member in the conveying direction and is provided outside a paper passing area, which is an area in the rotation axis direction through which recording materials that can be conveyed by the fixing device and have the longest length in the rotation axis direction are conveyed, and the biasing means is a leaf spring, and the holding member has a holding portion that holds the leaf spring. (3) A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting it in a transport direction, the fixing device comprising: a flexible cylindrical rotating body; a heating body that is arranged inside the rotating body and extends in a rotation axis direction of the rotating body perpendicular to the transport direction, the heating body being in contact with the inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member that has a groove that extends in the rotation axis direction longer than the heating body in the transport direction and holds the heating body in the groove; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between the rotating body and the outer surface of the rotating body; and a lubricant that is applied between the rotating body and the heating body, the lubricant being applied to the groove. a lubricant held in the groove portion, and a biasing means for biasing the heating element held in the groove portion toward the downstream side in the conveying direction, wherein the biasing means is provided on the upstream side of the holding member in the conveying direction and outside a paper passing area, which is an area in the rotation axis direction through which a recording material that has the longest length in the rotation axis direction among recording materials that can be conveyed by the fixing device is conveyed, the heating element having a heater and a sliding plate that covers the heater and transmits the heat of the heater to the rotating element while uniformly heating it, the sliding plate having an elastic bent portion outside the paper passing area in the rotation axis direction, and the biasing means being the bent portion. (4) A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting it in a transport direction, the fixing device comprising: a flexible cylindrical rotating body; a heating body that is arranged inside the rotating body and extends in a direction of the rotation axis of the rotating body perpendicular to the transport direction, the heating body being in contact with the inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member that has a groove that extends in the direction of the rotation axis longer than the heating body in the transport direction and holds the heating body in the groove; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between the rotating body and the outer surface of the rotating body; a lubricant that is applied between the rotating body and the heating body, the lubricant being held in the groove; and a biasing means that biases the heating body held in the groove toward the downstream side in the transport direction, the biasing means being provided upstream of the holding member in the transport direction and biasing the rotating axis of the recording material that can be transported by the fixing device. a fixing device provided outside a paper passage area in the direction of the rotation axis through which a recording material having a maximum length in the linear direction is transported, the groove having a first side surface against which the heating element abuts on the downstream side in the transport direction, a second side surface facing the heating element on the upstream side in the transport direction and forming a gap, and a bottom surface that forms the groove together with the first side surface and the second side surface; the holding member having a surface opposite to the surface on which the groove is provided in a direction perpendicular to the transport direction and the rotation axis direction, and one end and the other end in the transport direction on the opposite surface; the biasing means having a first hook portion hooked onto the one end portion and a second hook portion hooked onto the other end portion, and a protrusion having a triangular shape in a cross section perpendicular to the rotation axis direction and protruding toward the gap, the protrusion biasing the heating element toward the downstream side in the transport direction and toward the bottom surface. (5) A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting it in a transport direction, the fixing device comprising: a flexible cylindrical rotating body; a heating body that is arranged inside the rotating body and extends in a rotational axis direction of the rotating body perpendicular to the transport direction, the heating body being in contact with the inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member that has a groove that extends in the rotational axis direction longer than the heating body in the transport direction and holds the heating body in the groove; a pressure member that comes into pressure contact with the heating body via the rotating body and forms the fixing nip portion between the rotating body and the outer surface of the rotating body; a lubricant that is applied between the rotating body and the heating body, the lubricant being held in the groove; and a biasing means that biases the heating body held in the groove toward the downstream side in the transport direction, the biasing means being provided upstream of the holding member in the transport direction and biasing the heating body toward the downstream side in the transport direction in the rotational axis direction along which a recording material that has the longest length in the rotational axis direction among recording materials that can be transported by the fixing device is transported. the groove has a first side surface against which the heating element abuts on the downstream side in the transport direction, a second side surface facing the heating element on the upstream side in the transport direction to form a gap, and a bottom surface that forms the groove together with the first side surface and the second side surface; the holding member has a first surface opposite to the surface on which the groove is provided in a direction perpendicular to the transport direction and the rotation axis direction, and an end portion of the first surface on the downstream side in the transport direction; the urging means has a hook portion that is hooked onto the downstream end portion, a protrusion portion that has a triangular shape in a cross section perpendicular to the rotation axis direction and protrudes toward the gap, and a second surface on which the protrusion is provided; when the urging means is not urging the heating element, the second surface is inclined in a direction toward the hook portion compared to when the urging means is urging the heating element; and the protrusion urges the heating element toward the downstream side in the transport direction and toward the bottom surface. (6) A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, the fixing device comprising: a flexible cylindrical rotating body; a heating body that is disposed inside the rotating body and extends in a direction of the rotation axis of the rotating body perpendicular to the transport direction, the heating body being in contact with the inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member that has a groove that extends in the direction of the rotation axis longer than the heating body in the transport direction and holds the heating body in the groove; and a holding member that is in pressure contact with the heating body via the rotating body and is between the outer surface of the rotating body and the heating body. a pressure member that forms the fixing nip portion by applying a lubricant between the rotating body and the heating body, the lubricant being held in the groove portion; and a biasing means that biases the heating body held in the groove portion toward the downstream side in the conveying direction, the biasing means being provided on the upstream side of the holding member in the conveying direction and outside a paper passing region that is a region in the rotation axis direction through which a recording material that has the longest length in the rotation axis direction among recording materials that can be conveyed by the fixing device is conveyed, and the groove portion is provided on the downstream side in the conveying direction. the holding member has a first side surface against which the heating element abuts on the upstream side in the conveying direction, a second side surface facing the heating element on the upstream side in the conveying direction and forming a gap, and a bottom surface forming the groove portion together with the first side surface and the second side surface, the holding member has a first surface opposite to the surface on which the groove portion is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and an end portion of the first surface on the downstream side in the conveying direction, the heating element has a second surface parallel to the bottom surface and not in contact with the bottom surface, a third surface facing the second side surface, and a corner formed by the second surface and the third surface the biasing means has a hook portion that is hooked onto the downstream end portion, a first pressing portion that presses the second surface, and a second pressing portion that presses the corner portion, the first pressing portion and the second pressing portion being inclined in a direction toward the hook portion when the biasing means is not biasing the heating body compared to when the biasing means is biasing the heating body, the first pressing portion biases the heating body toward the bottom surface, and the second pressing portion biases the heating body downstream in the transport direction and toward the bottom surface. (7) A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting it in a transport direction, the fixing device comprising: a flexible cylindrical rotating body; a heating body that is arranged inside the rotating body and extends in a rotation axis direction of the rotating body perpendicular to the transport direction, the heating body contacting the inner circumferential surface of the rotating body to supply heat to the rotating body; a holding member that has a groove that extends in the rotation axis direction longer than the heating body in the transport direction and holds the heating body in the groove; and a fixing device that is in pressure contact with the heating body via the rotating body and that holds the heating body. a pressure member that forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant that is applied between the rotating body and the heating body, the lubricant being held in the groove; and a biasing means that biases the heating body held in the groove toward the downstream side in the conveying direction, the biasing means being provided on the upstream side of the holding member in the conveying direction and outside a paper passing region that is a region in the rotation axis direction through which a recording material that has the longest length in the rotation axis direction among recording materials that can be conveyed by the fixing device is conveyed, and the biasing means is provided on the upstream side of the holding member in the conveying direction and outside the paper passing region that is a region in the rotation axis direction through which a recording material that has the longest length in the rotation axis direction is conveyed, and the groove The holding member has a first side surface on the downstream side in the conveying direction against which the heating element abuts, a second side surface on the upstream side in the conveying direction facing the heating element to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, the holding member has a first surface on the opposite side to the surface on which the groove portion is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and a downstream end of the first surface in the conveying direction, the heating element has a second surface that is parallel to the bottom surface and does not contact the bottom surface, and a third side surface that faces the second side surface. the biasing means has a hook portion that is hooked onto the downstream end portion, a first pressing portion that presses the second surface, and a second pressing portion that presses the third surface, the first pressing portion and the second pressing portion being inclined in a direction toward the hook portion when the biasing means is not biasing the heating body compared to when the biasing means is biasing the heating body, the first pressing portion biases the heating body toward the bottom surface, and the second pressing portion biases the heating body toward the downstream side in the transport direction. (8) A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting it in a transport direction, the fixing device comprising: a flexible cylindrical rotating body; a heating body that is arranged inside the rotating body and extends in a direction of the rotation axis of the rotating body perpendicular to the transport direction, the heating body being in contact with the inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member that has a groove that extends in the direction of the rotation axis longer than the heating body in the transport direction and holds the heating body in the groove; a pressure member that comes into pressure contact with the heating body via the rotating body and forms the fixing nip portion between the rotating body and the outer surface of the rotating body; a lubricant that is applied between the rotating body and the heating body, the lubricant being held in the groove; and a biasing means that biases the heating body held in the groove toward the downstream side in the transport direction, the biasing means being provided upstream of the holding member in the transport direction and configured to bias a recording material that can be transported by the fixing device, the length in the direction of the rotation axis being longer than the length in the direction of the rotation axis of the recording material that can be transported by the fixing device. a fixing device provided with a connector having a cable, a contact portion connected to the cable and contacting the contact, the biasing means, and a housing portion containing the contact portion and the biasing means; wherein the biasing means continues from the contact portion toward the upstream side in the conveying direction, has a triangular shape in a cross section perpendicular to the rotational axis direction, and has a protrusion protruding toward the gap, and the protrusion biases the heating element toward the downstream side in the conveying direction and toward the bottom surface. (9) A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting it in a transport direction, the fixing device comprising: a flexible cylindrical rotating body; a heating body that is arranged inside the rotating body and extends in a direction of the rotation axis of the rotating body perpendicular to the transport direction, the heating body being in contact with the inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member that has a groove that extends in the direction of the rotation axis longer than the heating body in the transport direction and holds the heating body in the groove; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between the rotating body and the outer surface of the rotating body; a lubricant that is applied between the rotating body and the heating body, the lubricant being held in the groove; and a biasing means that biases the heating body held in the groove toward the downstream side in the transport direction, the biasing means being provided upstream of the holding member in the transport direction and transporting the recording material by the fixing device. the fixing device is provided outside a paper passage area in the rotational axis direction, which is an area through which recording materials that can be conveyed that have the longest length in the rotational axis direction are conveyed, the heating element has a heater and a contact that is provided outside the paper passage area in the rotational axis direction and supplies power to the heater, the groove portion has a first side that is abutted by the heating element on the downstream side in the conveying direction, a second side that faces the heating element on the upstream side in the conveying direction and forms a gap, and a bottom surface that forms the groove portion together with the first side and the second side surfaces, and is provided with a connector having a cable, a contact portion that is connected to the cable and makes contact with the contact portion, the biasing means, and a housing portion that contains the contact portion, the biasing means being provided in a part of the housing portion and having a protrusion that protrudes toward the gap, and the protrusion biases the heating element toward the downstream side in the conveying direction and toward the bottom surface. (10) An image forming apparatus comprising an image forming means for forming an unfixed image on a recording material, and a fixing device according to any one of (1) to (9) for fixing the unfixed image on the recording material. [Effects of the Invention]

[0011] According to the present invention, it is possible to prevent the position of the heating element of the fixing device from shifting, while maintaining the running stability of the film without the lubricant for maintaining the sliding performance of the film running stability being depleted until the end of the device's life. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view and an exploded perspective view of a fixing device according to a first embodiment of the present invention; [Figure 2] Schematic and cross-sectional views of the heater of Example 1 [Figure 3] Schematic and cross-sectional views showing the fitting state of the heater and the holding member in Example 1. [Figure 4] 1 is a schematic diagram showing a state in which a heater and a holding member are fitted together in Example 1, a cross-sectional view, an enlarged view of a biasing member, and a perspective view. [Figure 5] 1 is a diagram showing a modified example of the biasing member of the first embodiment, and an enlarged view showing the fitted state. [Figure 6] 1 is a schematic diagram and cross-sectional view of the heating element and the holding member of Example 1 as seen from the pressure roller side. [Figure 7] 1 is a schematic diagram and cross-sectional view of the heating element and the holding member of Example 1 as seen from the pressure roller side. [Figure 8] Schematic and cross-sectional views of a heater and a holding member according to a modification of the first embodiment. [Figure 9] 1 is a cross-sectional view of a heater and a holding member according to a modification of the first embodiment; [Figure 10] Schematic and cross-sectional views of the heater and the holding member of the second embodiment as viewed from the pressure roller side. [Figure 11] 10 is a cross-sectional view of a biasing member according to a modification of the second embodiment; [Figure 12] Schematic and cross-sectional views of a heating element and a holding member according to Example 3 [Figure 13] 10A and 10B are cross-sectional views of a power supply portion of a fixing device according to a conventional example of the third embodiment and a cross-sectional view of a power supply portion of a fixing device according to a modification of the third embodiment. [Figure 14] Schematic cross-sectional view showing an image forming apparatus according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0013] [Fixing device] 1 is a cross-sectional view and an exploded perspective view showing the configuration of a fixing device of Example 1. The fixing device 100 of Example 1 is a heat fixing device of a film heating type in which a fixing nip portion N is formed by a film unit 10 and a pressure roller 20. The film unit 10 has a heater 11 as a heating element, a holding member 12 that holds the heater 11, a fixing film 13, and a metal stay 14 that presses the holding member 12 against the pressure roller 20 by receiving pressure from a pressure spring 15. In addition, a lubricant is applied between the heater 11 and the inner surface of the fixing film 13 to maintain slidability.

[0014] (fixing film) The fixing film 13 is a flexible cylindrical rotating body. The fixing film 13 has a base made of polyimide resin with a thickness of 20 to 100 μm, a conductive primer layer provided on the base, and a release layer made of fluororesin such as PFA, PTFE, or FEP formed on the conductive primer layer. In Example 1, the base layer is made of polyimide and has a thickness of 60 μm, and the conductive primer layer is provided thereon. The surface layer is coated with PFA to which a conductive material has been added with a thickness of 10 μm. The fixing film 13 has a total thickness of approximately 70 μm and a diameter of 18 mm, and high thermal conductivity is achieved by mixing highly thermally conductive powder into the base layer.

[0015] (heating body) The heating element is disposed inside the fixing film 13 and extends in the direction of the axis of rotation of the fixing film 13, which is perpendicular to the conveying direction. The heating element is a member that comes into contact with the inner peripheral surface of the fixing film 13 and has the function of applying heat to the fixing film 13 to heat it. Therefore, the heating element may either generate heat itself and apply heat to the fixing film 13, or may receive heat from another member and apply it to the fixing film 13. When the heating element receives heat from another member (heat source), it may be heat conduction through contact or radiation without contact.

[0016] The configuration of the heater 11, which is an example of a heating element that applies heat to the fixing film 13, will be described with reference to FIG. 2. FIG. 2(a) is an overall view of the heater 11 as seen from the pressure roller 20 side, and FIG. 2(b) is a cross-sectional view taken along line BB in FIG. 2(a). The heater 11 includes a heat-resistant, insulating substrate 11a, a resistance heating element 11b, contacts 11e, wiring 11d, and a protective layer 11c. The substrate 11a is a highly thermally conductive, elongated rectangular parallelepiped substrate such as an insulating alumina, aluminum nitride, or metal plate coated with a glass coating. The resistance heating element 11b is a heating element having a thickness of approximately 10 μm and made of an electrically resistive material such as Ag / Pd (silver-palladium), which is applied to the surface of the substrate 11a by screen printing or the like. The contacts 11e are used to supply power to the resistance heating element 11b of the heater 11. The wiring 11d is a wiring for electrically connecting each resistance heating element 11b and the contact point 11e on the heater 11. The protective layer 11c is a layer formed of glass, fluororesin, or the like, and coated on the resistance heating element 11b and the wiring 11d. In Example 1, a heater 11 is used in which a 1 mm thick alumina substrate 11a is used, a silver-palladium heating element is formed, and then a 60 μm thick glass is coated as the protective layer 11c.

[0017] (holding member) The holding member 12 has a groove that extends in the rotation axis direction longer than the heating element in the conveying direction, and is a member that holds the heater 11, etc., and is made of heat-resistant resin such as liquid crystal polymer, phenolic resin, PPS, PEEK, etc. The lower the thermal conductivity, the better the heat conduction to the pressure roller 20, so a filler such as glass balloons or silica balloons may be included in the resin layer.

[0018] The holding member 12 receives the biasing force of a pressure spring 15 via a metal stay 14, and biases the heater 11 toward the pressure roller 20. As a result, a uniform fixing nip portion N is formed in the longitudinal direction (direction of the rotation axis) between the heater 11, the fixing film 13 fitted on the holding member 12, and the pressure roller 20. The holding member 12 also serves to guide the rotation of the fixing film 13.

[0019] Furthermore, as shown in FIG. 3 (described later), the holding member 12 is provided with a slot 12a (see FIG. 1(b)) that is a groove portion for holding the heater 11, and the heater 11 is held by being fitted into the slot 12a. The slot 12a has an abutment surface 12ds that is a first side surface, an upstream end surface 12us that is a second side surface, and a bottom surface 12ab. The abutment surface 12ds is a surface that the heater 11 abuts on the downstream side in the conveyance direction of the recording material. The upstream end surface 12us is a surface that faces the heater 11 on the upstream side in the conveyance direction and forms a gap Su. The bottom surface 12ab is a surface that forms a U-shaped cross section together with the abutment surface 12ds and the upstream end surface 12us in a cross section perpendicular to the rotation axis direction. The cross-sectional shape formed by the abutment surface 12ds, the upstream end surface 12us, and the bottom surface 12ab does not have to be U-shaped as long as it is capable of holding the heater 11 and has a shape that forms a gap Su on the upstream side.

[0020] The heater 11 thermally expands as it is heated, and the holding member 12 also thermally expands as its temperature rises, resulting in a difference in thermal expansion between the two. Furthermore, since dimensional accuracy and other factors must be taken into consideration in manufacturing, the width of the slot 12a in the holding member 12 is necessarily designed to be wider than the width of the heater 11 when they are fitted together. The width of the slot 12a refers to the length in the direction (which is also the recording material conveyance direction) perpendicular to the longitudinal direction (rotation axis direction) of the fixing film 13 and the pressure roller 20. The same applies to the width of the heater 11. Details of the fitting state between the heater 11 and the holding member 12 will be described later.

[0021] (Pressure roller) The pressure roller 20, which is a pressure member, is pressed against the heater 11 via the fixing film 13, forming a fixing nip N between the pressure roller 20 and the outer surface of the fixing film 13. The pressure roller 20 has a core 21, an elastic layer 22, and a release layer 23. The core 21 is made of a metal such as SUS or Al. The elastic layer 22 is an elastic roller and is formed on the outside of the core 21. The elastic layer 22 is an elastic layer such as an elastic solid rubber layer, an elastic sponge rubber layer, or an elastic foam rubber layer. Here, the elastic solid rubber layer is a layer made of heat-resistant rubber such as silicone rubber or fluororubber. The elastic sponge rubber layer is a layer formed by foaming silicone rubber to provide better heat insulation. The elastic foam rubber layer is a layer in which hollow fillers (such as microballoons) are dispersed within the silicone rubber layer, creating a gaseous portion within the cured product, thereby enhancing the heat insulation effect. The release layer 23 is formed on the elastic layer 22 from PFA, PTFE, or the like. In Example 1, the silicone balloon rubber layer is 3.5 mm thick and 18 mm in diameter, the surface layer is PFA with a thickness of 30 μm, and the product hardness is 40 degrees in Asker C hardness.

[0022] (Metal stay) The metal stay 14 transmits the biasing force from the pressure spring 15 to the holding member 12 and the heater 11, and forms a fixing nip N between the metal stay 14 and the pressure roller 20 via the fixing film 13.

[0023] (Compression spring) As described above, pressure springs 15 are disposed at both longitudinal ends of the film unit 10, and spring bearing portions 14a at both ends of the metal stay 14 are pressed by the pressure springs 15 via spring bearing members 14b. The load of the pressure springs 15 is transmitted uniformly along the longitudinal direction of the holding member 12. In the fixing nip N, the fixing film 13 is sandwiched between the heater 11 and the pressure roller 20 by the applied pressure, causing it to bend and come into close contact with the heating surface of the heater 11. The heating surface of the heater 11 refers to the surface of the substrate 11a on which the resistance heating element 11b is provided.

[0024] (heat fixing operation) The pressure roller 20 receives a driving force to rotate in the direction of the arrow in FIG. 1(a) from a drive gear (not shown) provided at the end of the core metal 21. The driving force is transmitted from a motor (not shown) in accordance with commands from a CPU (not shown) which serves as control means. As the pressure roller 20 is driven to rotate, the fixing film 13 is rotated by the frictional force with the pressure roller 20. By interposing a lubricant such as a fluorine-based or silicone-based heat-resistant grease between the fixing film 13 and the heater 11, frictional resistance is kept low, allowing the fixing film 13 to rotate smoothly.

[0025] Furthermore, the temperature of the heater 11 is controlled appropriately by the CPU determining the duty ratio of the power supplied to the resistance heating element 11b in response to a signal from a temperature detection element such as a thermistor (not shown) provided on the back surface of the substrate 11a. This maintains the temperature in the fixing nip N at the desired set temperature required for fixing. The recording material carrying an unfixed toner image is transported into the fixing nip N at a predetermined timing, where it is heated and fixed while being sandwiched and transported. The recording material discharged from the fixing nip N is guided by a discharge guide (not shown) and discharged outside the image forming apparatus in which the fixing device 100 is installed.

[0026] [Mated state] (Heater positioning status) An example of the fitted state of the heater 11 and the holding member 12 is shown in Fig. 3(a). In Fig. 3, the direction from the upstream side to the downstream side in the conveyance direction Dr of the recording material is the x direction, and the direction from the side without the contact point 11e to the side with the contact point 11e in the longitudinal direction of the heater 11 is the y direction. Furthermore, the direction toward the surface of the heater 11 as viewed from the pressure roller 20 side is the z direction (see notation in the figure).

[0027] FIG. 3(a) shows the heater 11 fitted into the holding member 12 as viewed from the pressure roller 20 side, and particularly shows an enlarged view of the slot 12a into which the heater 11 is fitted in the holding member 12. FIG. 3(b) is a cross-sectional view taken along line CC in FIG. 3(a) showing the heater 11 fitted into the holding member 12. First, the positioning of the heater 11 will be described. The slot 12a has an abutment surface 12ds, which is the downstream end face of the holding member 12. The abutment surface 12ds is the surface against which the heater 11 abuts and makes contact.

[0028] In the film heating type fixing device 100, in order to maintain stable fixing performance, it is preferable to set the position of the heater 11 as follows. That is, it is preferable to set the state during the fixing operation as designed, in which the heater 11 abuts against the abutment surface 12ds of the slot 12a of the holding member 12 and does not move further downstream. This is for the following reason. Even if the position of the heater 11 shifts within the slot 12a of the holding member 12, the frictional force caused by the rotation of the fixing film 13 during the fixing operation will eventually return the heater 11 to the abutment surface 12ds of the slot 12a of the holding member 12. For this reason, the heater 11 is positioned by abutting against the abutment surface 12ds, which is the downstream end face of the slot 12a of the holding member 12.

[0029] (Gap between heater and holding member) We will now explain the gap Su, which is the gap between the heater 11 and the upstream end surface 12us of the slot 12a of the holding member 12. The gap Su is the difference between the width Wh of the heater 11 (hereinafter referred to as the heater width) and the width Ws of the slot 12a of the holding member 12, and as shown in Figure 3(b), Ws - Wh = Su. This gap Su is an air gap that is intentionally secured for the following two reasons.

[0030] One reason is that the heater 11 and the holding member 12 are affected by manufacturing tolerances and thermal expansion. Because the heater 11 and the holding member 12 each have their own manufacturing tolerances, their dimensions must be designed to allow for a sufficient fit even when the heater 11 width Wh is at the upper tolerance limit and the slot 12a width Ws in the holding member 12 is at the lower tolerance limit. Furthermore, due to differences in thermal expansion between the components during heating, particularly during the temperature rise process from room temperature, the heater 11 thermally expands before the holding member 12. Therefore, if sufficient clearance is not provided, stress will be generated due to interference, which will cause cracks due to the brittle nature of the alumina substrate 11a of the heater 11. Therefore, to fit the heater 11 into the slot 12a in the holding member 12, the width Ws of the slot 12a in the holding member 12 must be designed to be wider than the width Wh of the heater 11 (Ws > Wh).

[0031] Another reason is to secure a space for temporarily retaining lubricant. A lubricant is applied between the heater 11 and the fixing film 13 to allow the fixing film 13 to slide and rotate. However, part of the lubricant applied during assembly is scraped off by the heater 11 as the fixing film 13 rotates and is temporarily retained in this gap Su. The lubricant retained in the gap Su is gradually supplied as use progresses (through durability), making it possible to maintain sliding performance over the life of the device. The gap Su is positioned so that the fixing nip N is immediately downstream in the rotation direction of the fixing film 13. Therefore, when lubricant is needed in the fixing nip N, the lubricant can be quickly supplied to the fixing nip N.

[0032] For the above reasons, a gap Su is provided between the heater 11 and the upstream end face 12us of the slot 12a of the holding member 12. In addition, a gap St is provided in the rotation axis direction between the heater 11 and the end face 12s (see FIG. 3(a)) of the slot 12a of the holding member 12 on the side where the contact point 11e is not provided. Note that, as shown in FIG. 3(a), the end face 12s is the surface at one end of the slot 12a in the longitudinal direction. Like the gap Su described above, this gap is necessarily provided in consideration of the manufacturing tolerances and the effects of thermal expansion of the heater 11 and the holding member 12.

[0033] [Holding member of embodiment] A fixing device 100 of Example 1 is shown in Figure 4. Figure 4(a) is a schematic diagram showing the fitted state of the heater 11 and the holding member 12 in the fixing device 100 of Example 1. Example 1 is characterized in that a step 12c, which is an accommodating portion for accommodating the coil spring B1, is provided on the upstream end surface 12us of the slot 12a of the holding member 12, and the coil spring B1 is disposed in the step 12c. This allows the heater 11 to be biased against the abutment surface 12ds, which is the downstream end surface of the slot 12a of the holding member 12, that is, in the x direction in Figure 4.

[0034] Fig. 4(b) is a cross-sectional view taken along line DD in Fig. 4(a). Fig. 4(c) shows a coil spring B1, which is a biasing means, Fig. 4(d) is an enlarged view of the portion of the holding member 12 where the coil spring B1 of Fig. 4(c) is arranged, and Fig. 4(e) is a perspective view of the step 12c portion of the holding member 12. The coil spring B1 biases the heater 11 held in the slot 12a downstream in the conveyance direction. The coil spring B1 is provided upstream of the holding member 12 in the conveyance direction, and is provided outside the paper passing area (outside the paper passing area), which is the area in the rotational axis direction through which the recording material that is longest in the rotational axis direction among the recording materials that can be conveyed by the fixing device 100 is conveyed.

[0035] When the heater 11 is not being held, the coil springs B1 are provided at two locations in the longitudinal direction in the slot 12a of the holding member 12 outside the paper passage area of ​​the fixing device 100 so as to face the abutment surface 12ds. The paper passage area is the area corresponding to the longest length in the direction perpendicular to the conveying direction (the width of the recording material) of the recording material that can be fixed by the fixing device 100. The coil springs B1 are provided at both ends in the longitudinal direction of the slot 12a of the holding member 12, and urge the heater 11 downstream in the conveying direction Dr.

[0036] Therefore, the heater 11 is constantly biased in the downstream direction of the conveyance direction Dr, so that the heater 11 can always be kept in contact with the contact surface 12ds. This prevents the heater 11 from moving upstream from the time of assembly, and significantly reduces the risk of the heater 11 moving upstream even when the fixing film 13 rotates in reverse due to jam clearance, etc. Furthermore, the gap Su between the heater 11 and the upstream end surface 12us of the slot 12a of the holding member 12 can always be stably maintained. As described above, the fixing device 100 of the first embodiment can maintain both stable fixability and stable lubrication.

[0037] [Modification of the biasing member] In the first embodiment, the coil spring B1 is used as the biasing member that biases the heater 11 downstream in the transport direction Dr. However, the shape of the biasing member is not limited to this. For example, as a modified example of the biasing member, leaf springs B2 and B3, which are biasing means as shown in FIGS. 5(a) and 5(c), can be used with the same effect. The leaf springs B2 and B3 are made of a metal with elasticity, such as SUS. As with the coil spring B1, the position at which they are positioned as biasing members in the longitudinal direction of the holding member 12 is outside the paper passage area of ​​the holding member 12 in the longitudinal direction. The holding member 12 has a holding portion that holds the leaf springs B2 and B3.

[0038] (Leaf spring B2) Fig. 5(a) shows the shape of the leaf spring B2, which is the biasing member, and Fig. 5(b) is an enlarged view of the portion arranged in the holding member 12. As shown in Fig. 5(b), the holding member 12 is provided with a groove 12e, which is a holding portion for holding the leaf spring B2, and the leaf spring B2 is arranged in the groove 12e.

[0039] The leaf spring B2 has a fitting portion B2a and a pressing portion B2b. The fitting portion B2a is a portion that fits into the groove 12e of the holding member 12. The pressing portion B2b is a portion that presses the heater 11. The pressing portion B2b has a "L"-shaped cross section in the longitudinal direction of the leaf spring B2. One end of the pressing portion B2b in the longitudinal direction is continuous with the fitting portion B2a, and the other end is not continuous with the fitting portion B2a and is an open end. This allows the heater 11 to be biased downstream in the conveying direction Dr by the leaf spring B2. Note that in FIG. 5(b), the leaf spring B2 is fitted into the groove 12e so that the longitudinal direction of the leaf spring B2 is parallel to the y direction perpendicular to the conveying direction Dr. However, the leaf spring B2 may also be fitted into the groove 12e so that the longitudinal direction of the leaf spring B2 is parallel to the z direction perpendicular to the conveying direction Dr.

[0040] (Leaf spring B3) Fig. 5(c) shows a leaf spring B3, which is an example of another shape of the biasing member, and Fig. 5(d) is an enlarged view of the portion arranged in the holding member 12. As shown in Fig. 5(d), the holding member 12 is provided with a groove 12f, which is a holding portion for holding the leaf spring C, and the leaf spring B3 is arranged in the groove 12f.

[0041] The leaf spring B3 has a contact portion B3a and a pressing portion B3b. The contact portion B3a is a portion that fits into the groove 12f of the holding member 12. The pressing portion B3b is a portion that presses the heater 11. The pressing portion B3b has an arc-shaped cross section in the longitudinal direction of the leaf spring B3. Both ends of the pressing portion B3b in the longitudinal direction are continuous with the contact portion B3a. In this case, as with the leaf spring B2, the heater 11 is configured to be biased by the leaf spring B3 in the downstream direction of the conveying direction Dr. Note that, in FIG. 5(b), the leaf spring B3 is fitted into the groove 12f so that the longitudinal direction of the leaf spring B3 is parallel to the y direction perpendicular to the conveying direction Dr. However, the leaf spring B3 may be fitted into the groove 12f so that the longitudinal direction of the leaf spring B3 is parallel to the z direction perpendicular to the conveying direction Dr.

[0042] 5(a) and 5(c), the heater 11 can be prevented from moving upstream, and the gap Su between the heater 11 and the upstream end surface 12us of the slot 12a of the holding member 12 can be always stably maintained. This prevents the heater 11 from shifting position to maintain stable fixability, and also stably supplies lubricant within the paper passing area, making it possible to maintain running stability of the fixing film 13 throughout its service life.

[0043] [Modification of heater part] In the above-described embodiment, the heater 11 is used as the heating element. However, the same effect can be achieved when the heating element is composed of multiple components. For example, the heating element 11A includes the heater 11 and a sliding plate 25 that covers the heater 11 and uniformly transfers the heat of the heater 11 to the fixing film 13. FIG. 6 shows an example of a configuration in which the heating element 11A includes the heater 11 and the sliding plate 25. A coil spring B1, which serves as a biasing means, biases the sliding plate 25 downstream in the conveyance direction. The heater 11 can take any form as long as it is a heat supplying member that generates heat through resistance when power is supplied. However, the heater 11 will be described here using the above-described heater 11, which has a silver-palladium heating element formed on an alumina substrate and a glass coating layer as a protective layer.

[0044] Fig. 6(a) is a schematic diagram of the heating element 11A as seen from the pressure roller 20 side, and Fig. 6(b) is a cross-sectional view taken along line EE in Fig. 6(a). As shown in Fig. 6(b), the sliding plate 25 is a metal member having a U-shaped cross section, and is arranged to cover the heater 11. The sliding plate 25 covers the heater 11 at least at the longitudinal position where the coil spring B1 is provided. The coil spring B1, which serves as a biasing member, is arranged on the upstream side of the sliding plate 25 in the conveying direction Dr, and biases the sliding plate 25 downstream in the conveying direction Dr.

[0045] By providing the sliding plate 25, it is possible to uniformly transfer the heat of the heater 11 to the fixing film 13, and it is also possible to improve the sliding properties by applying a fluorine-based coating to the sliding surface of the sliding plate 25 that slides against the fixing film 13. However, even in this case, since the heater 11, sliding plate 25, and holding member 12 each have manufacturing tolerances and differences in thermal expansion coefficients, it is necessary to provide a certain amount of gap between them.

[0046] Therefore, in this configuration, too, biasing the sliding plate 25 covering the heater 11 of the heating element 11A downstream in the transport direction Dr and maintaining the state of abutting against the abutment surface 12ds is effective for stabilizing fixation. Furthermore, this is also effective for retaining lubricant in the gap Su between the sliding plate 25 and the upstream end surface 12us of the slot 12a of the holding member 12.

[0047] (Another modified example of the heater part) Fig. 7 is a diagram showing a further modification of Example 1. Fig. 7 is the same as Fig. 6 in that the heating element 11B has the heater 11 and a sliding plate 25 arranged so as to cover the heater 11, but is configured such that a coil spring B1 as a biasing member biases the heater 11 in the downstream direction of the conveying direction Dr.

[0048] Fig. 7(a) is a schematic diagram of the heating element 11B as seen from the pressure roller 20 side, and Fig. 7(b) is a cross-sectional view taken along line FF in Fig. 7(a), which is within the paper passage area in the longitudinal direction of the heating element 11B and where the sliding plate 25 covers the heater 11. Fig. 7(c) is a cross-sectional view taken along line GG in Fig. 7(a), which is outside the paper passage area and where the sliding plate 25 does not cover the heater 11. In Fig. 7, unlike Fig. 6, the sliding plate 25 does not cover the heater 11 at least at the position in the longitudinal direction where the coil spring B1 is provided.

[0049] As shown in Figure 7(c), the coil spring B1 urges the heater 11, not the sliding plate 25, downstream in the conveying direction Dr. The heater 11 further urges the fitted sliding plate 25 downstream in the conveying direction Dr. As a result, the sliding plate 25 is stabilized in a position where it abuts on the downstream side, and a gap Su is formed between the sliding plate 25 and the upstream end surface 12us of the slot 12a of the holding member 12. Therefore, the effect described in Example 1 can be obtained in this case as well.

[0050] (Another modified example of the heater part) FIG. 8 shows another modified example in which the sliding plate 25 also functions as a biasing member. The heating element 11C includes a heater 11 and a sliding plate 25 that covers the heater 11, uniformly distributing the heat of the heater 11 and transmitting it to the fixing film 13. The sliding plate 25 has an elastic bent portion 25f outside the paper passage area in the rotation axis direction. In FIG. 8, the bent portion 25f functions as a biasing member. FIG. 8(a) is a schematic diagram of the heating element 11C as seen from the pressure roller 20 side, and FIG. 8(b) is a cross-sectional view taken along line HH in FIG. 8(a), which is within the paper passage area in the longitudinal direction and does not include the bent portion 25f. FIG. 8(c) is a cross-sectional view taken along line II in FIG. 8(a), which includes the bent portion 25f outside the paper passage area.

[0051] As shown in FIG. 8(c), a bent portion 25f is formed at the upstream end of the sliding plate 25 in the conveying direction Dr to provide springiness (elasticity). An open end 25g of the bent portion 25f abuts against the upstream end surface 12us of the slot 12a of the holding member 12. This applies a biasing force from the bent portion 25f of the sliding plate 25 to the upstream end surface 12us of the slot 12a of the holding member 12. The sliding plate 25 itself is biased downstream in the conveying direction Dr by receiving a reaction from the upstream end surface 12us of the slot 12a of the holding member 12. In this case, as with the configuration in FIG. 7 described above, the sliding plate 25 can be brought into a state of abutting against the downstream side.

[0052] (Another modified example of the heater part) As another variation of the heating element configuration, as shown in FIG. 9, a heating element 11D may have a three-layer structure including a heater 11, a sliding plate 25, and a metal heat equalizer plate 26 (or heat insulating plate) disposed behind the heater 11. The heating element 11D has the heat equalizer plate 26 disposed between the heater 11 and the slot 12a (bottom surface 12ab) in a direction perpendicular to the conveyance direction and the rotation axis direction. The heat equalizer plate 26 is sandwiched between the heater 11 and the slot 12a of the holding member 12. The sliding plate 25 covers the heater 11 and the heat equalizer plate 26. In this case, the heating element 11D can be maintained in abutment against the abutment surface 12ds of the slot 12a of the holding member 12, preventing misalignment of the heating element 11D in the fixing nip N and ensuring a lubricant retention space. The plate spring B2 in FIG. 5(a) and the plate spring B3 in FIG. 5(c) may be applied to the heating element 11A in FIG. 6, the heating element 11B in FIG. 7, and the heating element 11D in FIG.

[0053] The above describes the configuration and effect of the biasing member biasing the heating element downstream in the transport direction Dr, but the heating element is not limited to the above configuration. As described above, the heating element itself is a member that has the function of providing heat to the fixing film, so it may generate heat itself or may supply heat received from another member to the fixing film. When receiving heat from another member (heat source), it may be heat conduction through contact or radiation without contact.

[0054] As described above, according to Example 1, it is possible to prevent the position of the heating element of the fixing device from shifting, while maintaining the running stability of the film without the lubricant for maintaining the sliding performance of the film running stability being depleted until the end of the device's life. [Example]

[0055] [Biasing member] The first embodiment is characterized in that the heater 11 as the heating element is biased in the direction of the abutment surface 12ds (x direction in the figure), which is the downstream end surface of the slot 12a of the holding member 12. The biasing member of the second embodiment is configured to apply a biasing force to the heater 11 not only in the direction of the abutment surface 12ds of the slot 12a of the holding member 12, but also in the direction toward the heater 11 surface as viewed from the pressure roller 20 side (z direction in the figure). The leaf spring B4, which is the biasing means of the second embodiment, biases the heating element in a direction perpendicular to the conveyance direction and the rotation axis direction.

[0056] A fixing device 100 of Example 2 is shown in Figure 10. Figure 10(a) is an overall view of the area where the heater 11 is fitted into the groove hole 12a of the holding member 12, as seen from the pressure roller 20 side, and Figure 10(b) is a cross-sectional view taken along line JJ in Figure 10(a). In Example 2, as shown in Figure 10(a), leaf springs B4 are arranged as urging members at both ends in the longitudinal direction, outside the recording material passage area in the longitudinal direction.

[0057] The leaf spring B4 has a flat portion B4a, a bent portion B4b, a flat portion B4c, a hook portion B4d, and a convex portion B4e. When viewed from the pressure roller 20 side, the flat portion B4a is a portion that covers the heater 11 and the holding member 12 from the upstream side to the downstream side in the conveyance direction Dr. The flat portion B4c is a portion that covers the holding member 12 from the pressure roller 20 side toward the fixing film 13 side. More specifically, the flat portion B4c has a flat portion B4cd that covers the holding member 12 on the downstream side, and a flat portion B4cu that covers the holding member 12 on the upstream side. The bent portion B4b is a portion that connects the flat portion B4a and the flat portion B4c and bends the leaf spring B4. More specifically, the bent portion B4b has a bent portion B4bd that connects the flat portion B4a and the downstream flat portion B4cd, and a bent portion B4bu that connects the flat portion B4a and the upstream flat portion B4cu.

[0058] The hook portion B4d is a portion that secures the leaf spring B4 to the holding member 12 by hooking onto a corner 12k of the holding member 12. More specifically, the hook portion B4d has a hook portion B4dd that is hooked onto a downstream corner 12kd of the holding member 12, and a hook portion B4du that is hooked onto an upstream corner 12ku of the holding member 12. The protrusion B4e is formed on the flat portion B4a and is a triangular-shaped protruding portion that protrudes into the gap Su when the leaf spring B4 is secured to the holding member 12.

[0059] 10(b), the leaf spring B4 is fixed by being hooked onto a corner 12k of the holding member 12. The leaf spring B4 has a triangular protrusion B4e formed at a position corresponding to the gap Su between the heater 11 and the upstream end face 12us of the slot 12a of the holding member 12, and is fixed so as to fit into the gap Su. The heater 11 is biased by the inclined surface B4f of the triangular protrusion B4e, and is thereby biased in two directions: downstream in the conveying direction Dr (x direction in the figure) and toward the holding member 12 (z direction in the figure).

[0060] As described above, in the second embodiment, the slot 12a has an abutment surface 12ds, which is a first side surface, an upstream end surface 12us, which is a second side surface, and a bottom surface 12ab. The abutment surface 12ds is abutted against the heater 11 on the downstream side in the conveyance direction. The upstream end surface 12us faces the heater 11 on the upstream side in the conveyance direction, forming a gap Su. The bottom surface 12ab, together with the abutment surface 12ds and the upstream end surface 12us, forms the slot 12a. The holding member 12 also has a surface 12l opposite to the surface on which the slot 12a is provided in a direction perpendicular to the conveyance direction and the rotation axis direction, and a corner 12kd at one end of the opposite surface 12l in the conveyance direction and a corner 12ku at the other end. The leaf spring B4, which is the biasing means, has a hook B4dd, which is a first hook, a hook B4du, which is a second hook, and a protrusion B4e, which is a protruding protrusion. The hook B4dd is hooked onto the corner 12kd. The hook B4du is hooked onto the corner 12ku. The protrusion B4e has a triangular shape in a cross section perpendicular to the rotation axis direction and protrudes toward the gap Su. The protrusion B4e biases the heater 11 downstream in the transport direction and toward the bottom surface 12ab.

[0061] The biasing force toward the downstream side of the transport direction Dr (x direction in the drawing) prevents the heater 11 from shifting toward the upstream side. In addition, the biasing force toward the holding member 12 (z direction in the drawing) prevents the heater 11 from separating from the holding member 12 and increases the frictional force at the contact surface between the heater 11 and the holding member 12 by applying a normal force. This further prevents the heater 11 from moving in the x direction.

[0062] [Modification of the biasing member of the second embodiment] Although the leaf spring B4 shown in FIG. 10 has been described as an example of the configuration of the second embodiment, the same effect can be obtained even with a shape such as that shown in FIG.

[0063] (Leaf spring variation 1) FIG. 11(a) is a cross-sectional view showing the shape of the leaf spring B5, which is the biasing means, and FIG. 11(b) is a schematic cross-sectional view of the state when it is fitted into the holding member 12, and is a simplified cross-sectional view showing the positional relationship between the leaf spring B5 as the biasing member, the heater 11, and the holding member 12.

[0064] The leaf spring B5 has a flat portion B5a, a bent portion B5b, a flat portion B5c, a hook portion B5d, and a convex portion B5e. When viewed from the pressure roller 20 side, the flat portion B5a is a portion that covers at least the heater 11 from the upstream side to the downstream side in the conveyance direction Dr. The flat portion B5c is a portion that covers the holding member 12 on the downstream side from the pressure roller 20 side toward the fixing film 13 side. The bent portion B5b is a portion that connects the flat portion B5a and the flat portion B5c and bends the leaf spring B5.

[0065] The hook portion B5d is a portion that secures the leaf spring B5 to the holding member 12 by hooking onto a corner portion 12k of the holding member 12. The protrusion B5e is formed on the flat portion B5a and is a triangular protruding portion that protrudes into the gap Su when the leaf spring B5 is secured to the holding member 12. The protrusion B5e has a slope B5f that comes into contact with the heater 11.

[0066] As shown in FIG. 11(a), the leaf spring B5 is shaped as shown by the solid line, with the angle α set to less than 90 degrees (α<90 degrees). When this leaf spring B5 is fitted into the holding member 12, it elastically deforms into the shape shown by the dotted line in FIG. 11(a). When the leaf spring B5 attempts to return to its original shape, a biasing force F1 acts in the z direction in the figure. As a result, the heater 11 is biased downstream in the transport direction Dr (the x direction in the figure) and toward the holding member 12 (the z direction in the figure). This provides the same effects as those described for the leaf spring B4.

[0067] As described above, the holding member 12 of the first modification has a surface 12l, which is a first surface opposite the surface on which the slot 12a is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and a corner 12k, which is the end of the surface 12l on the downstream side in the conveying direction. The leaf spring B5 has a hook B5d that hooks onto the corner 12k, a protrusion B5e that is triangular in cross section perpendicular to the rotation axis direction and protrudes toward the gap Su, and a flat portion B5a, which is a second surface on which the protrusion B5e is provided. When the leaf spring B4 is not biasing the heater 11, the flat portion B5a is inclined toward the hook B5d compared to when the leaf spring B5 is biasing the heater 11. The protrusion B5e biases the heater 11 downstream in the conveying direction and toward the bottom surface 12ab.

[0068] (Leaf spring variation 2) 11(c) and 11(d) show the shape of a leaf spring B6 as a modified example of the biasing member. The leaf spring B6, which is the biasing means, has a flat portion B6a, a bent portion B6b, a flat portion B6c, a hook portion B6d, a contact portion B6e, a bent portion B6f, and a contact portion B6g. When viewed from the pressure roller 20 side, the flat portion B6a is a portion that covers the heater 11 from the upstream side to the downstream side in the conveyance direction Dr. The flat portion B6c is a portion that covers the holding member 12 on the downstream side from the pressure roller 20 side toward the fixing film 13 side. The bent portion B6b is a portion that connects the flat portion B6a and the flat portion B6c and bends the leaf spring B6.

[0069] The hook portion B6d is a portion that hooks onto a corner portion 12k of the holding member 12 to secure the leaf spring B6 to the holding member 12. The abutting portion B6e is a portion of the flat portion B6a that curves toward the hook portion B6d, and is a portion that abuts against the heater 11 and urges the heater 11 in the z direction when the leaf spring B6 is secured to the holding member 12. The flat portion B6a is bent into a dogleg shape at a bent portion B6f and continues to the abutting portion B6g. When the leaf spring B6 is secured to the holding member 12, the abutting portion B6g enters the gap Su and abuts against the corner portion 11f of the heater 11, urging the heater 11 downstream.

[0070] The leaf spring B6 is also configured so that the flat portion B6a bends toward the hook portion B6d compared to when it is in the biased state, as shown in Figure 11(c), giving it the shape shown by the solid line. When this leaf spring B6 is fitted into the holding member 12, it elastically deforms into the shape shown by the dotted line in Figure 11(c). When the leaf spring B6 attempts to return to its original shape, a biasing force F2 acts in the z direction in the figure, which results in biasing the heater 11 downstream in the transport direction Dr (the x direction in the figure) and toward the holding member 12 (the z direction in the figure). In this case, the same effect as that of the leaf spring B5 can be obtained.

[0071] As described above, heater 11 of Modification 2 has surface 11h, which is a second surface parallel to and not in contact with bottom surface 12ab, surface 11g, which is a third surface facing upstream end surface 12us, and corner 11f formed by surfaces 11h and 11g. Leaf spring B6 has hook B6d, which is hooked onto corner 12k, contact portion B6e, which is a first pressing portion that presses surface 11h, and contact portion B6g, which is a second pressing portion that presses corner 11f. When leaf spring B6 is not biasing heater 11, contact portions B6e and B6g are inclined toward hook B6d compared to when leaf spring B6 is biasing heater 11. The contact portion B6e biases the heater 11 toward the bottom surface 12ab, and the contact portion B6g biases the heater 11 toward the downstream side in the transport direction and toward the bottom surface 12ab.

[0072] (Leaf spring variation 3) 11(e) and 11(f) show the shape of a leaf spring B7 as a modified example of the biasing member. The leaf spring B7 has a flat portion B7a, a bent portion B7b, a flat portion B7c, a hook portion B7d, a contact portion B7e, a bent portion B7f, a portion B7g, and a pressing portion B7h. When viewed from the pressure roller 20 side, the flat portion B7a is a portion that covers the heater 11 from the upstream side to the downstream side in the conveyance direction Dr. The flat portion B7c is a portion that covers the holding member 12 on the downstream side from the pressure roller 20 side toward the fixing film 13 side. The bent portion B7b is a portion that connects the flat portion B7a and the flat portion B7c and bends the leaf spring B7.

[0073] The hook portion B7d is a portion that hooks onto a corner portion 12k of the holding member 12 to secure the leaf spring B7 to the holding member 12. The abutting portion B7e is a portion of the flat portion B7a that curves toward the hook portion B7d. When the leaf spring B7 is secured to the holding member 12, the abutting portion B7e abuts against the heater 11 and urges the heater 11 in the z direction. The flat portion B7a bends toward the hook portion B7d at a bent portion B7f and continues to a portion B7g. The portion B7g further bends toward the hook portion B7d and continues to a pressing portion B7h. When the leaf spring B7 is secured to the holding member 12, the pressing portion B7h enters the gap Su and presses a surface 11g of the heater 11 that faces the upstream end surface 12us of the holding member 12, urging the heater 11 downstream.

[0074] The leaf spring B7 is also configured so that the flat portion B7a bends in a direction closer to the hook portion B7d than when it is in the biased state, as shown in Figure 11(e), giving it the shape shown by the solid line. When this leaf spring B7 is fitted into the holding member 12, it elastically deforms into the shape shown by the dotted line in Figure 11(e). When the leaf spring B7 tries to return to its original shape, a biasing force F3 acts in the z direction in the figure, which results in biasing the heater 11 downstream in the transport direction Dr (the x direction in the figure) and toward the holding member 12 (the z direction in the figure). In this case, the same effect as in the case of the leaf spring B5 can be obtained.

[0075] As described above, the holding member 12 of Modification 3 has a surface 12l, which is a first surface opposite the surface on which the slot 12a is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and a corner 12k, which is the downstream end of the surface 12l in the conveying direction. The heater 11 has a surface 11h, which is a second surface parallel to the bottom surface 12ab and not in contact with the bottom surface 12ab, and a surface 11g, which is a third surface facing the upstream end surface 12us. The leaf spring B7 has a hook B7d hooked onto the corner 12k, a contact portion B7e, which is a first pressing portion that presses the surface 11h, and a pressing portion B7h, which is a second pressing portion that presses the surface 11g. The contact portion B7e and the pressing portion B7h are inclined toward the hook portion B7d when the leaf spring B7 is not biasing the heater 11 compared to when the leaf spring B7 is biasing the heater 11. The contact portion B7e biases the heater 11 toward the bottom surface 12ab. The pressing portion B7h biases the heater 11 downstream in the conveyance direction.

[0076] As described above, according to Example 2, it is possible to prevent the position of the heating element of the fixing device from shifting, while maintaining the running stability of the film without the lubricant for maintaining the sliding performance of the film being depleted until the end of the device's life. [Example]

[0077] In the first and second embodiments, a configuration was shown in which members for biasing the heater 11 as a heating element were arranged on both sides of the heater 11 in the longitudinal direction. In the third embodiment, the configuration for biasing the heater 11 also serves as a power supply unit for supplying power to the heater 11, thereby simplifying the configuration of the fixing device 100. This reduces the number of assembly steps, improving ease of assembly and enabling further reduction in parts.

[0078] [Using member of Example 3] Figure 12(a) is a schematic diagram showing the fitted state of the heater 11 and the holding member 12 and the arrangement of the power supply connector 30 in the fixing device 100 of Example 3, with the power supply connector 30 shown as transparent to show the positional relationship with the contact 11e of the heater 11. Also, in Figure 12(a), the urging member on the opposite side of the heater 11 in the longitudinal direction from the side where the power supply connector 30 is provided is not shown. Figure 12(b) is a cross-sectional view of the contact 11e of the heater 11 taken along line KK.

[0079] As shown in the cross-sectional view of FIG. 12(b), the power supply connector 30, which serves as the power supply unit, has a U-shaped housing 31 made of resin and a power supply terminal 32. The heater 11 and holding member 12 are inserted into and fixed in the U-shaped space formed by the housing 31. The power supply terminal 32 is connected to a bundle of wires 33. The power supply terminal 32 has a contact portion 32a that is exposed from the housing 31 and contacts the contact 11e of the heater 11. The power supply terminal 32 is made of a metal such as stainless steel, and its elasticity allows it to contact the contact 11e of the heater 11 with a predetermined contact pressure to maintain electrical connection. The power supply terminal 32 also has a biasing portion 32f that is exposed from the housing 31. The biasing portion 32f is formed on the upstream side of the power supply terminal 32 in the conveying direction Dr. The biasing portion 32f applies a biasing force such that the biasing portion 32f enters the gap Su between the heater 11 and the upstream end face 12us of the slot 12a of the holding member 12 when the power supply connector 30 is fixed to the heater 11 and the holding member 12. The biasing portion 32f has an inclined surface 32g, and presses the corner 11f of the heater 11 with the inclined surface 32g when the power supply connector 30 is fixed to the heater 11 and the holding member 12. As a result, the heater 11 is biased both downstream in the transport direction Dr (x direction in the figure) and toward the holding member 12 (z direction in the figure).

[0080] (Compared to conventional examples) 13(a) is a cross-sectional view of a power supply connector 300 of a conventional fixing device. The power supply connector 300 of the conventional fixing device has only the function of a power supply terminal 320 arranged therein contacting a contact point 11e of the heater 11. The power supply connector 300 has a cable bundle 330 and a housing part 310.

[0081] In contrast to this, in the fixing device 100 of Example 3, by extending the shape of the power supply terminal 32 built into the power supply connector 30, it becomes possible to apply a biasing force to the heater 11 downstream in the conveying direction Dr without adding any new components.

[0082] As described above, the heating element of Example 3 includes the heater 11 and a contact 11e that is provided outside the sheet passage area in the rotation axis direction and that supplies power to the heater 11. The power supply connector 30 (connector) includes a cable 33, a contact portion 32a that is connected to the cable 33 and that contacts the contact 11e, a biasing portion 32f that is a biasing means, and a housing portion 31 that contains the contact portion 32a and the biasing portion 32f. The biasing portion 32f continues from the contact portion 32a toward the upstream side in the conveyance direction, has a triangular shape in a cross section perpendicular to the rotation axis direction, is a protruding portion that protrudes toward the gap Su, and includes a slope 32g. The slope 32g biases the heater 11 toward the downstream side in the conveyance direction and toward the bottom surface 12ab.

[0083] (Modification of power supply connector part) Fig. 13(b) is a diagram showing a power supply connector 30A that is a modification of Example 3. As shown in Fig. 13(b), a biasing portion 31f that biases the heater 11 is formed in a part of a housing portion 31A made of resin. The biasing portion 31f has a protrusion 31g, and the protrusion 31g has a slope 31h.

[0084] When the power supply connector 30A is fixed to the heater 11 and the holding member 12, the biasing portion 31f applies a biasing force such that the biasing portion 31f enters the gap Su between the heater 11 and the upstream end face 12us of the slot 12a of the holding member 12. When the power supply connector 30A is fixed to the heater 11 and the holding member 12, the inclined surface 31h presses the corner 11f of the heater 11. As a result, similar to the biasing portion 32f provided on the power supply terminal 32 described above, the heater 11 is biased both downstream in the conveyance direction Dr (the x direction in the figure) and toward the holding member 12 (the z direction in the figure). In this way, a biasing force can be applied to the heater 11 using part of the housing 31A of the power supply connector 30A.

[0085] As described above, the power supply connector 30A of the modified example includes the cable 33, the contact portion 32a that is connected to the cable 33 and contacts the contact 11e, the biasing portion 31f that is a biasing member, and the housing 31A that contains the contact portion 32a. The biasing portion 31f is provided on a part of the housing 31A and has a protrusion 31g that protrudes toward the gap Su. The protrusion 31g biases the heater 11 downstream in the conveyance direction and toward the bottom surface 12ab.

[0086] As described above, by using the power supply connectors 30, 30A arranged as power supply units and their components, it is possible to configure the heater 11 to be biased downstream in the conveyance direction Dr without adding a new biasing member. Figures 12 and 13(b) show some examples of configurations in which the power supply connectors 30, 30A arranged as power supply units are used to apply a biasing force to the heater 11, and the configuration is not limited to these. Note that the biasing members described in Examples 1 and 2 may be used at the longitudinal ends of the heater 11 and the holding member 12 on the side where the contact point 11e is not provided.

[0087] As described above, according to Example 3, it is possible to prevent the position of the heating element of the fixing device from shifting, while maintaining the running stability of the film without the lubricant for maintaining the sliding performance of the film being depleted until the end of the device's life. [Example]

[0088] [Explanation of laser beam printer] FIG. 14 shows a schematic configuration of a laser beam printer as an example of an image forming apparatus to which the above-described fixing device 100 can be applied. The laser beam printer 1000 (hereinafter referred to as printer 1000) includes a photosensitive drum 1010, a charging unit 1020, and a developing unit 1030. The photosensitive drum 1010 is an image carrier on which an electrostatic latent image is formed. The charging unit 1020 uniformly charges the photosensitive drum 1010. An optical scanning device 1025, which is an exposure means, forms an electrostatic latent image by scanning a laser beam corresponding to image data onto the photosensitive drum 1010. The developing unit 1030 forms a toner image by developing the electrostatic latent image formed on the photosensitive drum 1010 with toner.

[0089] The toner image formed on the photosensitive drum 1010 is transferred by a transfer unit 1050 onto a sheet P (recording material) supplied from a cassette 1040, and the unfixed toner image transferred to the sheet P is fixed by a fixing device 100 and discharged onto a tray 1070. The photosensitive drum 1010, charging unit 1020, developing unit 1030, and transfer unit 1050 constitute an image forming unit (image forming means). The printer 1000 also includes a power supply unit 1080, which supplies power to a drive unit such as a motor and a control unit 5000. The control unit 5000 has a CPU (not shown) and controls the image forming operation by the image forming unit, the conveyance operation of the sheet P, the temperature of the heater 11 of the fixing device 100, etc. When the printer 1000 finishes a printing operation, it transitions to a standby state after a predetermined time has elapsed so that it can immediately perform a printing operation. After a predetermined time has elapsed, printer 1000 transitions from the standby state to a sleep state, which is a low-power consumption mode, in order to reduce power consumption during standby. Printer 1000 has three states: a sleep state and a standby state, which are second modes, and a print state, which is a first mode, and control unit 5000 transitions printer 1000 to each of these states. Note that the image forming apparatus to which fixing device 100 of the present invention can be applied is not limited to the configuration exemplified in FIG. 14.

[0090] As described above, according to Example 4, it is possible to prevent the position of the heating element of the fixing device from shifting, while maintaining the running stability of the film without the lubricant for maintaining the sliding performance of the film being depleted until the end of the device's life.

[0091] The disclosure of this embodiment includes the following configuration. (Configuration 1) A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while conveying the recording material in a conveyance direction, a flexible cylindrical rotor; a heating element disposed inside the rotating body and extending in a rotation axis direction of the rotating body perpendicular to the conveying direction, the heating element being in contact with an inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member having a groove portion extending in the rotation axis direction and longer than the heating body in the conveying direction, the holding member holding the heating body in the groove portion; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; a biasing means for biasing the heating element held in the groove portion toward a downstream side in the conveying direction; Equipped with The fixing device is characterized in that the urging means is provided upstream of the holding member in the conveying direction, and is provided outside the paper passing area, which is the area in the direction of the rotation axis through which the recording material that has the longest length in the direction of the rotation axis is conveyed among the recording materials that can be conveyed by the fixing device. (Configuration 2) the biasing means is a coil spring, The fixing device described above, wherein the holding member has a housing portion that houses the coil spring. (Configuration 3) the biasing means is a leaf spring, The fixing device described above, wherein the holding member has a holding portion that holds the leaf spring. (Configuration 4) the heating body includes a heater and a sliding plate that covers the heater and uniformly transfers the heat of the heater to the rotating body, The fixing device described above, wherein the biasing means biases the sliding plate toward the downstream side. (Configuration 5) The fixing device according to any one of the preceding claims, wherein the heating element has a heat insulating plate provided between the heater and the groove in a direction perpendicular to the transport direction and the rotation axis direction. (Configuration 6) the heating body includes a heater and a sliding plate that covers the heater and uniformly transfers the heat of the heater to the rotating body, the sliding plate has an elastic bent portion outside the paper passing area in the rotation axis direction, The fixing device described above, wherein the biasing means is the bent portion. (Configuration 7) The fixing device described above, wherein the biasing means biases the heating element in a direction perpendicular to the transport direction and the direction of the rotation axis. (Configuration 8) the groove portion has a first side surface against which the heating body abuts on the downstream side in the transport direction, a second side surface facing the heating body on the upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, the holding member has a surface opposite to a surface on which the groove portion is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and one end and the other end in the conveying direction on the opposite surface, the biasing means has a first hook portion hooked onto the one end portion, a second hook portion hooked onto the other end portion, and a protrusion having a triangular shape in a cross section perpendicular to the rotation axis direction and protruding toward the gap, The fixing device according to any one of the preceding claims, wherein the protrusion urges the heating element toward the downstream side in the transport direction and toward the bottom surface. (Configuration 9) the groove portion has a first side surface against which the heating body abuts on the downstream side in the transport direction, a second side surface facing the heating body on the upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, the holding member has a first surface opposite to a surface on which the groove portion is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and an end portion of the first surface on a downstream side in the conveying direction, the biasing means has a hook portion that is hooked onto the downstream end portion, a protrusion portion that has a triangular shape in a cross section perpendicular to the rotation axis direction and protrudes toward the gap, and a second surface on which the protrusion portion is provided, the second surface is inclined in a direction toward the hook portion when the biasing means is not biasing the heating body compared to when the biasing means is biasing the heating body, The fixing device according to any one of the preceding claims, wherein the protrusion urges the heating element toward the downstream side in the transport direction and toward the bottom surface. (Configuration 10) the groove portion has a first side surface against which the heating body abuts on the downstream side in the transport direction, a second side surface facing the heating body on the upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, the holding member has a first surface opposite to a surface on which the groove portion is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and an end portion of the first surface on a downstream side in the conveying direction, the heating element has a second surface parallel to the bottom surface and not in contact with the bottom surface, a third surface facing the second side surface, and a corner portion formed by the second surface and the third surface, the biasing means has a hook portion that is hooked onto the downstream end portion, a first pressing portion that presses the second surface, and a second pressing portion that presses the corner portion, the first pressing portion and the second pressing portion are inclined in a direction toward the hook portion when the biasing means is not biasing the heating body compared to when the biasing means is biasing the heating body, the first pressing portion biases the heating element toward the bottom surface, The fixing device described above, wherein the second pressing portion urges the heating element toward the downstream side in the transport direction and toward the bottom surface. (Configuration 11) the groove portion has a first side surface against which the heating body abuts on the downstream side in the transport direction, a second side surface facing the heating body on the upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, the holding member has a first surface opposite to a surface on which the groove portion is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and an end portion of the first surface on a downstream side in the conveying direction, the heating element has a second surface parallel to the bottom surface and not in contact with the bottom surface, and a third surface facing the second side surface; the biasing means has a hook portion that is hooked onto the downstream end portion, a first pressing portion that presses the second surface, and a second pressing portion that presses the second surface, the first pressing portion and the second pressing portion are inclined in a direction toward the hook portion when the biasing means is not biasing the heating body compared to when the biasing means is biasing the heating body, the first pressing portion biases the heating element toward the bottom surface, The fixing device described above, wherein the second pressing portion urges the heating element toward the downstream side in the transport direction. (Configuration 12) the heating element has a heater and a contact point that is provided outside the paper passing area in the rotation axis direction and that supplies power to the heater; the groove portion has a first side surface against which the heating body abuts on the downstream side in the transport direction, a second side surface facing the heating body on the upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, a connector including a bundle of wires, contact portions connected to the bundle of wires and in contact with the contact points, the biasing means, and a housing portion containing the contact portions and the biasing means; the biasing means is continuous from the contact portion toward the upstream side in the conveying direction, has a triangular shape in a cross section perpendicular to the rotation axis direction, and has a protrusion that protrudes toward the gap, The fixing device according to any one of the preceding claims, wherein the protrusion urges the heating element toward the downstream side in the transport direction and toward the bottom surface. (Configuration 13) the heating element has a heater and a contact point that is provided outside the paper passing area in the rotation axis direction and that supplies power to the heater; the groove portion has a first side surface against which the heating body abuts on the downstream side in the transport direction, a second side surface facing the heating body on the upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, a connector including a bundle of wires, contact portions connected to the bundle of wires and in contact with the contact points, the biasing means, and a housing portion containing the contact portions; the biasing means is provided on a part of the housing portion and has a protrusion that protrudes toward the gap, The fixing device according to any one of the preceding claims, wherein the protrusion urges the heating element toward the downstream side in the transport direction and toward the bottom surface. (Configuration 14) an image forming means for forming an unfixed image on a recording material; the fixing device for fixing an unfixed image on a recording material; An image forming apparatus comprising: [Explanation of symbols]

[0092] 11 Heater 12 Retaining member 12a slot 13 Fixing film 20 Pressure roller B1 Coil spring

Claims

1. A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while conveying the recording material in a conveyance direction, a flexible cylindrical rotor; a heating element disposed inside the rotating body and extending in a rotation axis direction of the rotating body perpendicular to the conveying direction, the heating element being in contact with an inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member having a groove portion extending in the rotation axis direction and longer than the heating body in the conveying direction, the holding member holding the heating body in the groove portion; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; a biasing means for biasing the heating element held in the groove portion toward a downstream side in the conveying direction; Equipped with the urging means is provided on the upstream side of the holding member in the conveying direction, and is provided outside a paper passing area in the rotation axis direction, which is an area through which a recording material having a maximum length in the rotation axis direction is conveyed among recording materials that can be conveyed by the fixing device, the biasing means is a coil spring, The fixing device is characterized in that the holding member has a housing portion that houses the coil spring.

2. A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, a flexible cylindrical rotor; a heating element disposed inside the rotating body and extending in a rotation axis direction of the rotating body perpendicular to the conveying direction, the heating element being in contact with an inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member having a groove portion extending in the rotation axis direction and longer than the heating body in the conveying direction, the holding member holding the heating body in the groove portion; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; a biasing means for biasing the heating element held in the groove portion toward a downstream side in the conveying direction; Equipped with the urging means is provided on the upstream side of the holding member in the conveying direction, and is provided outside a paper passing area in the rotation axis direction, which is an area through which a recording material having a maximum length in the rotation axis direction is conveyed among recording materials that can be conveyed by the fixing device, the biasing means is a leaf spring, The fixing device, wherein the holding member has a holding portion that holds the leaf spring.

3. the heating body includes a heater and a sliding plate that covers the heater and uniformly transfers the heat of the heater to the rotating body, 2. The fixing device according to claim 1, wherein the biasing means biases the sliding plate toward the downstream side.

4. 4. The fixing device according to claim 3, wherein the heating element has a heat insulating plate provided between the heater and the groove in a direction perpendicular to the transport direction and the rotation axis direction.

5. A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, a flexible cylindrical rotor; a heating element disposed inside the rotating body and extending in a rotation axis direction of the rotating body perpendicular to the conveying direction, the heating element being in contact with an inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member having a groove portion extending in the rotation axis direction and longer than the heating body in the conveying direction, the holding member holding the heating body in the groove portion; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; a biasing means for biasing the heating element held in the groove portion toward a downstream side in the conveying direction; Equipped with the urging means is provided on the upstream side of the holding member in the conveying direction, and is provided outside a paper passing area in the rotation axis direction, which is an area through which a recording material having a maximum length in the rotation axis direction is conveyed among recording materials that can be conveyed by the fixing device, the heating body includes a heater and a sliding plate that covers the heater and uniformly transfers the heat of the heater to the rotating body, the sliding plate has an elastic bent portion outside the paper passing area in the rotation axis direction, The fixing device is characterized in that the biasing means is the bent portion.

6. 6. The fixing device according to claim 5, wherein the biasing means biases the heating element in a direction perpendicular to the transport direction and the direction of the rotation axis.

7. A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, a flexible cylindrical rotor; a heating element disposed inside the rotating body and extending in a rotation axis direction of the rotating body perpendicular to the conveying direction, the heating element being in contact with an inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member having a groove portion extending in the rotation axis direction and longer than the heating body in the conveying direction, the holding member holding the heating body in the groove portion; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; a biasing means for biasing the heating element held in the groove portion toward a downstream side in the conveying direction; Equipped with the urging means is provided on the upstream side of the holding member in the conveying direction, and is provided outside a paper passing area in the rotation axis direction, which is an area through which a recording material having a maximum length in the rotation axis direction is conveyed among recording materials that can be conveyed by the fixing device, the groove portion has a first side surface against which the heating body abuts on a downstream side in the transport direction, a second side surface facing the heating body on an upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, the holding member has a surface opposite to a surface on which the groove portion is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and one end and the other end in the conveying direction on the opposite surface, the biasing means has a first hook portion hooked onto the one end portion, a second hook portion hooked onto the other end portion, and a protrusion having a triangular shape in a cross section perpendicular to the rotation axis direction and protruding toward the gap, The fixing device, wherein the protrusion urges the heating element toward the downstream side in the transport direction and toward the bottom surface.

8. A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, a flexible cylindrical rotor; a heating element disposed inside the rotating body and extending in a rotation axis direction of the rotating body perpendicular to the conveying direction, the heating element being in contact with an inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member having a groove portion extending in the rotation axis direction and longer than the heating body in the conveying direction, the holding member holding the heating body in the groove portion; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; a biasing means for biasing the heating element held in the groove portion toward a downstream side in the conveying direction; Equipped with the urging means is provided on the upstream side of the holding member in the conveying direction, and is provided outside a paper passing area in the rotation axis direction, which is an area through which a recording material having a maximum length in the rotation axis direction is conveyed among recording materials that can be conveyed by the fixing device, the groove portion has a first side surface against which the heating body abuts on a downstream side in the transport direction, a second side surface facing the heating body on an upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, the holding member has a first surface opposite to a surface on which the groove portion is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and an end portion of the first surface on a downstream side in the conveying direction, the biasing means has a hook portion that is hooked onto the downstream end portion, a protrusion portion that has a triangular shape in a cross section perpendicular to the rotation axis direction and protrudes toward the gap, and a second surface on which the protrusion portion is provided, the second surface is inclined in a direction toward the hook portion when the biasing means is not biasing the heating body compared to when the biasing means is biasing the heating body, The fixing device, wherein the protrusion urges the heating element toward the downstream side in the transport direction and toward the bottom surface.

9. A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, a flexible cylindrical rotor; a heating element disposed inside the rotating body and extending in a rotation axis direction of the rotating body perpendicular to the conveying direction, the heating element being in contact with an inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member having a groove portion extending in the rotation axis direction and longer than the heating body in the conveying direction, the holding member holding the heating body in the groove portion; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; a biasing means for biasing the heating element held in the groove portion toward a downstream side in the conveying direction; Equipped with the urging means is provided on the upstream side of the holding member in the conveying direction, and is provided outside a paper passing area in the rotation axis direction, which is an area through which a recording material having a maximum length in the rotation axis direction is conveyed among recording materials that can be conveyed by the fixing device, the groove portion has a first side surface against which the heating body abuts on a downstream side in the transport direction, a second side surface facing the heating body on an upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, the holding member has a first surface opposite to a surface on which the groove portion is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and an end portion of the first surface on a downstream side in the conveying direction, the heating element has a second surface parallel to the bottom surface and not in contact with the bottom surface, a third surface facing the second side surface, and a corner portion formed by the second surface and the third surface, the biasing means includes a hook portion that is hooked onto the downstream end portion, a first pressing portion that presses the second surface, and a second pressing portion that presses the corner portion, the first pressing portion and the second pressing portion are inclined in a direction toward the hook portion when the biasing means is not biasing the heating body compared to when the biasing means is biasing the heating body, the first pressing portion biases the heating element toward the bottom surface, The fixing device, wherein the second pressing portion urges the heating element toward the downstream side in the transport direction and toward the bottom surface.

10. A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, a flexible cylindrical rotor; a heating element disposed inside the rotating body and extending in a rotation axis direction of the rotating body perpendicular to the conveying direction, the heating element being in contact with an inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member having a groove portion extending in the rotation axis direction and longer than the heating body in the conveying direction, the holding member holding the heating body in the groove portion; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; a biasing means for biasing the heating element held in the groove portion toward a downstream side in the conveying direction; Equipped with the urging means is provided on the upstream side of the holding member in the conveying direction, and is provided outside a paper passing area in the rotation axis direction, which is an area through which a recording material having a maximum length in the rotation axis direction is conveyed among recording materials that can be conveyed by the fixing device, the groove portion has a first side surface against which the heating body abuts on a downstream side in the transport direction, a second side surface facing the heating body on an upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, the holding member has a first surface opposite to a surface on which the groove portion is provided in a direction perpendicular to the conveying direction and the rotation axis direction, and an end portion of the first surface on a downstream side in the conveying direction, the heating element has a second surface parallel to the bottom surface and not in contact with the bottom surface, and a third surface facing the second side surface, the biasing means has a hook portion that is hooked onto the downstream end portion, a first pressing portion that presses the second surface, and a second pressing portion that presses the third surface, the first pressing portion and the second pressing portion are inclined in a direction toward the hook portion when the biasing means is not biasing the heating body compared to when the biasing means is biasing the heating body, the first pressing portion biases the heating element toward the bottom surface, The fixing device, wherein the second pressing portion urges the heating element toward the downstream side in the transport direction.

11. A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, a flexible cylindrical rotor; a heating element disposed inside the rotating body and extending in a rotation axis direction of the rotating body perpendicular to the conveying direction, the heating element being in contact with an inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member having a groove portion extending in the rotation axis direction and longer than the heating body in the conveying direction, the holding member holding the heating body in the groove portion; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; a biasing means for biasing the heating element held in the groove portion toward a downstream side in the conveying direction; Equipped with the urging means is provided on the upstream side of the holding member in the conveying direction, and is provided outside a paper passing area in the rotation axis direction, which is an area through which a recording material having a maximum length in the rotation axis direction is conveyed among recording materials that can be conveyed by the fixing device, the heating element has a heater and a contact point that is provided outside the paper passing area in the rotation axis direction and that supplies power to the heater; the groove portion has a first side surface against which the heating body abuts on a downstream side in the transport direction, a second side surface facing the heating body on an upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, a connector including a bundle of wires, contact portions connected to the bundle of wires and in contact with the contact points, the biasing means, and a housing portion containing the contact portions and the biasing means; the biasing means is continuous from the contact portion toward the upstream side in the conveying direction, has a triangular shape in a cross section perpendicular to the rotation axis direction, and has a protrusion that protrudes toward the gap, The fixing device, wherein the protrusion urges the heating element toward the downstream side in the transport direction and toward the bottom surface.

12. A fixing device that sandwiches a recording material carrying an unfixed toner image in a fixing nip portion and heats the recording material while transporting the recording material in a transport direction, a flexible cylindrical rotor; a heating element disposed inside the rotating body and extending in a rotation axis direction of the rotating body perpendicular to the conveying direction, the heating element being in contact with an inner peripheral surface of the rotating body to supply heat to the rotating body; a holding member having a groove portion extending in the rotation axis direction and longer than the heating body in the conveying direction, the holding member holding the heating body in the groove portion; a pressure member that is in pressure contact with the heating body via the rotating body and forms the fixing nip portion between itself and an outer surface of the rotating body; a lubricant applied between the rotating body and the heating body, the lubricant being held in the groove; a biasing means for biasing the heating element held in the groove portion toward a downstream side in the conveying direction; Equipped with the urging means is provided on the upstream side of the holding member in the conveying direction, and is provided outside a paper passing area in the rotation axis direction, which is an area through which a recording material having a maximum length in the rotation axis direction is conveyed among recording materials that can be conveyed by the fixing device, the heating element has a heater and a contact point that is provided outside the paper passing area in the rotation axis direction and that supplies power to the heater; the groove portion has a first side surface against which the heating body abuts on a downstream side in the transport direction, a second side surface facing the heating body on an upstream side in the transport direction to form a gap, and a bottom surface that forms the groove portion together with the first side surface and the second side surface, a connector including a bundle of wires, contact portions connected to the bundle of wires and in contact with the contact points, the biasing means, and a housing portion containing the contact portions; the biasing means is provided on a part of the housing portion and has a protrusion that protrudes toward the gap, The fixing device, wherein the protrusion urges the heating element toward the downstream side in the transport direction and toward the bottom surface.

13. an image forming means for forming an unfixed image on a recording material; a fixing device according to any one of claims 1 to 12, which fixes an unfixed image on a recording material; An image forming apparatus comprising:

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