Fixation device and image formation device

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] As a heat fixing device mounted on an image forming apparatus, a film heating type fixing device is known. A film heating type fixing device generally has a cylindrical film, a heating body that contacts the inner surface of the film, a holding member having a groove for holding the heating body, and a pressure roller that forms a fixing nip with the heating body through the film. The film heating type fixing device heats and fixes the toner image while conveying the recording material carrying the toner image in the fixing nip. The heating body is fitted and held in a groove provided in a heat insulating holder that is a holding member. From the viewpoint of the dimensional accuracy of the member and stress relaxation caused by the thermal expansion difference accompanying the heating process, the width of the groove of the holding member is designed to be larger than the width of the heating body. The heating body moves downstream in the rotation direction of the film in the groove due to the frictional force with the film, so that the downstream end surface of the heating body is held in a state where it abuts against the downstream end surface (wall surface) of the groove of the holding member.

[0003] In the film heating type fixing device, the heating body is assembled by butting it against the downstream end face of the groove of the holding member during assembly, but the heating body may shift upstream in the subsequent work process. In addition, when a jam is cleared in the fixing device, the film may be rotated in the opposite direction to the fixing operation, and at this time, the heating body may shift upstream. If the heating body shifts upstream, the heating area for the recording material in the fixing nip part shifts from a predetermined position, and the fixing performance may decrease. To address this issue, for example, Patent Document 1 discloses a configuration in which an elastic body is provided between a heater as a heating body and a groove of the holding member. In addition, for example, Patent Document 2 discloses a configuration in which a gap filling member arranged adjacent to the heater is biased by an elastic member.

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

[0005] [Patent Document 1] JP 2012-123329 A [Patent Document 2] JP 2019-179143 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional configuration, since a member is disposed between the heater and the groove of the holding member in the longitudinal paper passing area, it becomes difficult to retain a sufficient amount of lubricant in this gap, and as a result, the sliding property decreases toward the end of the device's life, and there is a possibility that slippage occurs between the film and the recording material carrying the toner image.

[0007] The present invention has been 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 without the lubricant for maintaining the sliding performance of the film running 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 holds a recording material carrying an unfixed toner image in a fixing nip 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 an 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 that holds the heating body on an outer surface of the rotating body. a pressure member which forms the fixing nip between the rotating body and the heating body, a lubricant which is applied between the rotating body and the heating body, the lubricant being held in the groove portion, and a biasing means which biases the heating body held in the groove portion downstream in the transport direction, wherein the biasing means is provided on the upstream side of the holding member in the transport direction and outside a paper passing area which is an area in the rotation axis direction through which recording material which has the longest length in the rotation axis direction among recording materials which can be transported by the fixing device is transported.

[0010] (2) An image forming apparatus comprising: an image forming means for forming an unfixed image on a recording material; and the fixing device according to (1) above for fixing the unfixed image on the recording material. Effect 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 life of the device. [Brief description 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; [Diagram 2] Schematic and cross-sectional views of a heater according to a first embodiment [Diagram 3] Schematic and cross-sectional views showing the fitting state of the heater and the holding member in the first embodiment. [Figure 4] 1 is a schematic diagram showing a state in which a heater and a holding member are fitted together in a first embodiment, a cross-sectional view, an enlarged view of a biasing member, and a perspective view. [Diagram 5] FIG. 1 is an enlarged view showing a fitting state of a modified example of the urging member of the first embodiment; [Figure 6] 1 is a schematic diagram and a cross-sectional view of a heating body and a holding member according to a first embodiment, as viewed from the pressure roller side. [Figure 7] 1 is a schematic diagram and a cross-sectional view of a heating body and a holding member according to a first embodiment, as viewed 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 modified example of the first embodiment; [Figure 10] Schematic and cross-sectional views of a heater and a holding member according to a second embodiment, as viewed from the pressure roller side. [Figure 11] FIG. 11 is a cross-sectional view of a biasing member according to a modified example of the second embodiment. [Figure 12] Schematic and cross-sectional views of a heating body and a holding member according to a third embodiment [Figure 13] 10 is a cross-sectional view of a power supply portion of a fixing device according to a conventional example of the third embodiment, and FIG. 11 is a cross-sectional view of a power supply portion of a fixing device according to a modification of the third embodiment. [Figure 14] FIG. 11 is a schematic cross-sectional view showing an image forming apparatus according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[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 which is a heating body, a holding member 12 which holds the heater 11, a fixing film 13, and a metal stay 14 which receives a pressure from a pressure spring 15 and presses the holding member 12 against the pressure roller 20. 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 cylindrical rotating body having flexibility. 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, FEP, etc., formed on the conductive primer layer. In the first embodiment, 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 is added with a thickness of 10 μm. The fixing film 13 has a total thickness of about 70 μm and a diameter of 18 mm, and the base layer is mixed with highly thermally conductive powder to achieve high thermal conductivity.

[0015] (heating body) The heating element is disposed inside the fixing film 13 and extends in the direction of the rotation axis of the fixing film 13 perpendicular to the conveying direction. The heating element is a member that has the function of contacting the inner peripheral surface of the fixing film 13 and applying heat to the fixing film 13 to heat it. Therefore, the heating element may generate heat by 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 by contact or radiation without contact.

[0016] Here, the configuration of the heater 11 as an example of a heating body 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 has 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 a substrate made of alumina, aluminum nitride, or a metal plate that is glass-coated to provide insulation. The resistance heating element 11b is a heating element having a thickness of about 10 μm and made of an electrical resistance material such as Ag / Pd (silver-palladium) that is applied to the surface of the substrate 11a by screen printing or the like. The contacts 11e are for supplying 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 11e on the heater 11. The protective layer 11c is a layer formed of glass, fluororesin, or the like, coated on the resistance heating element 11b and the wiring 11d portion. In the first embodiment, alumina having a thickness of 1 mm is used as the substrate 11a, a silver-palladium heating element is formed, and then a heater 11 having a thickness of 60 μm coated with glass as the protective layer 11c is used.

[0017] (holding member) The holding member 12 has a groove that extends in the rotation axis direction longer than the heating body 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 thermal 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 the pressure spring 15 via the 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 (rotation axis direction) between the heater 11, the fixing film 13 fitted around 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)) which 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 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 a surface against which the heater 11 abuts on the downstream side in the conveying direction of the recording material. The upstream end surface 12us is a surface which faces the heater 11 on the upstream side in the conveying direction and forms a gap Su. The bottom surface 12ab is a surface which 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. In addition, 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 a gap Su is formed on the upstream side.

[0020] The heater 11 thermally expands as it is heated, and the holding member 12 also thermally expands as the temperature rises, but there is a difference in thermal expansion between the two. In addition, since dimensional accuracy in manufacturing must also be taken into consideration, the width of the slot 12a of the holding member 12 is necessarily designed to be wider than the width of the heater 11 when they are fitted together. Note that the width of the slot 12a refers to the length in the direction (which is also the conveying direction of the recording material) 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 of 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 in pressure contact with the heater 11 via the fixing film 13, and forms a fixing nip N between the heater 11 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 a metal core such as SUS or Al. The elastic layer 22 is an elastic roller, and is an elastic layer such as an elastic solid rubber layer, an elastic sponge rubber layer, or an elastic foam rubber layer formed on the outside of the core 21. Here, the elastic solid rubber layer is a layer formed 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 a better heat insulating effect. The elastic foam rubber layer is a layer in which hollow fillers (microballoons, etc.) are dispersed in the silicone rubber layer, and a gas portion is provided in the cured product to enhance the heat insulating effect. The release layer 23 is formed of PFA, PTFE, etc. on the elastic layer 22. In Example 1, the silicone balloon rubber layer has a thickness of 3.5 mm and a diameter of 18 mm, the surface layer is made of PFA with a thickness of 30 μm, and the product hardness is 40 degrees on the Asker C hardness scale.

[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 portion N between the metal stay 14 and the pressure roller 20 via the fixing film 13 .

[0023] (Pressure spring) As described above, the pressure springs 15 are disposed at both longitudinal ends of the film unit 10, and the spring bearing portions 14a at both longitudinal ends of the metal stay 14 are pressurized by the pressure springs 15 via the 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 portion N, the fixing film 13 is sandwiched between the heater 11 and the pressure roller 20 by the pressure force, and is deflected, so that the fixing film 13 is in 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 obtains a driving force to rotate in the direction of the arrow in FIG. 1(a) from a driving gear (not shown) provided at the end of the core metal 21. The driving force is transmitted from a motor (not shown) according to commands from a CPU (not shown) which is a 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 appropriately controlled 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 rear 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, and is heated and fixed while being sandwiched and transported in the fixing nip N. 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 mounted.

[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 conveying direction Dr of the recording material is the x direction, and the direction from the side where there is no contact point 11e to the side where there is contact point 11e in the longitudinal direction of the heater 11 is the y direction. Furthermore, the direction toward the heater 11 surface 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 in particular 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 surface of the holding member 12. The abutment surface 12ds is the surface against which the heater 11 abuts and makes contact.

[0028] In the fixing device 100 of the film heating type, in order to maintain a 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 in the design 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 is shifted in the slot 12a of the holding member 12, the frictional force caused by the rotation of the fixing film 13 during the fixing operation can finally 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 surface of the slot 12a of the holding member 12.

[0029] (Gap between heater and holding member) We will now explain the gap Su 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 Fig. 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 have manufacturing tolerances and thermal expansion. Since the heater 11 and the holding member 12 each have manufacturing tolerances, even if the width Wh of the heater 11 is at the upper tolerance limit and the width Ws of the slot 12a in the holding member 12 is at the lower tolerance limit, the dimensions must be such that they can be fitted together with a margin. Furthermore, due to the difference in thermal expansion of each member during heating, especially during the temperature rise process from room temperature, the heater 11 thermally expands before the holding member 12. For this reason, if a sufficient gap is not provided, stress is generated due to interference, and the alumina substrate 11a of the heater 11 has brittle characteristics, which causes cracks. Thus, in order to fit the heater 11 into the slot 12a of the holding member 12, it is necessary to design the width Ws of the slot 12a of the holding member 12 to be wider than the width Wh of the heater 11 (Ws>Wh).

[0031] Another reason is to secure a space for temporarily holding a 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 held in this gap Su. The lubricant held in the gap Su is gradually supplied as use progresses (through durability), making it possible to maintain the sliding performance over the life of the device. The gap Su is disposed 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. Also, in the rotation axis direction, a gap St is provided between the heater 11 and an 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 the end face 12s is a surface at one end of the slot 12a in the longitudinal direction, as shown in FIG. 3(a). Like the above-mentioned gap Su, this is a gap that 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] The fixing device 100 of the first embodiment is shown in Fig. 4. Fig. 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 the first embodiment. The first embodiment 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 on 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 Fig. 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 a portion of the holding member 12 where the coil spring B1 in Fig. 4(c) is arranged, and Fig. 4(e) is a perspective view of a step 12c portion of the holding member 12. The coil spring B1 biases the heater 11 held in the slot 12a downstream in the conveying direction. The coil spring B1 is provided upstream of the holding member 12 in the conveying direction, and is provided outside the paper passing area (outside the paper passing area), which is an area in the rotation axis direction where the recording material that has the longest length in the rotation axis direction among the recording materials that can be conveyed by the fixing device 100 is conveyed.

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

[0036] Therefore, the heater 11 is constantly biased in the downstream direction of the conveying direction Dr, so that the heater 11 can always maintain a state of abutting against the abutment surface 12ds. This prevents the heater 11 from moving upstream from the time of assembly, and can significantly reduce the risk of the heater 11 moving upstream even when the fixing film 13 rotates in reverse due to jamming or the like. In addition, the gap Su between the heater 11 and the upstream end surface 12us of the groove hole 12a of the holding member 12 can always be stably maintained. As described above, the fixing device 100 of the first embodiment is capable of maintaining both stable fixability and lubrication stability.

[0037] [Modification of the biasing member] In the first embodiment, the coil spring B1 is used as the biasing member for biasing the heater 11 downstream in the transport direction Dr, but the shape of the biasing member is not limited to this. For example, the same effect can be obtained by using leaf springs B2 and B3 as biasing means as shown in Figs. 5(a) and 5(c) as modified examples of the biasing member. The leaf springs B2 and B3 are made of elastic metal such as SUS. The position where the biasing member is disposed in the longitudinal direction of the holding member 12 is outside the longitudinal paper passing area of ​​the holding member 12, similar to the coil spring B1. The holding member 12 has a holding portion for holding 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 is continuous with the fitting portion B2a in the longitudinal direction, and the other end is not continuous with the fitting portion B2a and is an open end. This results in a configuration in which the heater 11 is biased by the leaf spring B2 in the downstream direction of the conveying direction Dr. 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, but the leaf spring B2 may 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 a portion arranged on 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 a circular arc shape in 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, similar to 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. 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, but 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 makes it possible to prevent the heater 11 from shifting position and maintain stable fixability, and to stably supply lubricant within the paper passing area and maintain running stability of the fixing film 13 throughout its lifespan.

[0043] [Modification of heater part] In the above embodiment, the heater 11 is used as the heating element, but the same effect can be obtained when the heating element is composed of a plurality of members. For example, the heating element 11A has the heater 11 and a sliding plate 25 that covers the heater 11 and uniformly heats the heater 11 and transfers the heat to the fixing film 13. FIG. 6 shows an example of the heating element 11A having the heater 11 and the sliding plate 25. The coil spring B1, which is the biasing means, biases the sliding plate 25 downstream in the conveying direction. The heater 11 can be of any form as long as it is a heat supplying member that is supplied with power and generates heat by resistance. Here, the heater 11 is described using the above-mentioned alumina substrate on which a silver-palladium heating element is formed and which has a glass coating layer as a protective layer.

[0044] Fig. 6(a) is a schematic diagram of the heating element 11A as viewed 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 disposed so as to cover the heater 11. The sliding plate 25 covers the heater 11 at least at the position in the longitudinal direction where the coil spring B1 is provided. The coil spring B1, which serves as a biasing member, is disposed on the upstream side of the sliding plate 25 in the transport direction Dr, and biases the sliding plate 25 in the downstream direction of the transport 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 with 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 degree of gap.

[0046] Therefore, even in this configuration, it is effective to stabilize the fixability by 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. Furthermore, it is also effective to hold the 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 modified example of Example 1. Fig. 7 is the same as Fig. 6 in that the heating body 11B has the heater 11 and a sliding plate 25 arranged so as to cover the heater 11, but the coil spring B1 as the biasing member biases the heater 11 in the downstream direction of the transport direction Dr.

[0048] Fig. 7(a) is a schematic diagram of the heating element 11B as viewed 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 Fig. 7(c), the coil spring B1 urges the heater 11, not the sliding plate 25, in the downstream direction of the transport direction Dr. The heater 11 further urges the fitted sliding plate 25 in the downstream direction of the transport direction Dr. As a result, the sliding plate 25 is stabilized at 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 the first embodiment can be obtained in this case as well.

[0050] (Another modified example of the heater part) FIG. 8 shows a further modified example, in which the sliding plate 25 also functions as a biasing member. The heating element 11C has a heater 11 and a sliding plate 25 for covering the heater 11 and uniformly distributing the heat of the heater 11 to the fixing film 13. The sliding plate 25 has an elastic bent portion 25f outside the paper passing area in the rotation axis direction. In FIG. 8, the bent portion 25f functions as a biasing means. FIG. 8(a) is a schematic diagram of the heating element 11C 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 passing area in the longitudinal direction and does not have the bent portion 25f. FIG. 8(c) is a cross-sectional view taken along line II in FIG. 8(a) where the bent portion 25f is outside the paper passing 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 so as to have springiness (elasticity). An open end 25g of the bent portion 25f abuts against the upstream end face 12us of the slot 12a of the holding member 12. This causes a biasing force to be applied from the bent portion 25f of the sliding plate 25 to the upstream end face 12us of the slot 12a of the holding member 12. The sliding plate 25 itself is biased in the downstream direction in the conveying direction Dr by receiving a reaction from the upstream end face 12us of the slot 12a of the holding member 12. In this case, the sliding plate 25 can be brought into a state of abutting against the downstream side, similar to the configuration of FIG. 7 described above.

[0052] (Another modified example of the heater part) As a further modified example of the configuration of the heating body, as shown in FIG. 9, the heating body 11D may have a three-layer configuration in which the heater 11, the sliding plate 25, and a metal heat equalizing plate 26 (or heat insulating plate) are arranged on the back of the heater 11. The heating body 11D has the heat equalizing plate 26 provided between the heater 11 and the slot 12a (bottom surface 12ab) in a direction perpendicular to the conveying direction and the rotation axis direction. The heat equalizing 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 equalizing plate 26. In this case, the heating body 11D can be maintained in a state of abutting against the abutment surface 12ds of the slot 12a of the holding member 12, and the positional deviation of the heating body 11D in the fixing nip portion N can be prevented, and a lubricant holding space can be secured. The leaf spring B2 in FIG. 5(a) and the leaf 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 body toward the downstream side in the transport direction Dr, but the heating body is not limited to the above configuration. As described above, since the heating body itself is a member that has the function of providing heat to the fixing film, it may be that the heating body itself generates heat, or that the heating body receives heat from another member and supplies it to the fixing film. When receiving heat from another member (heat source), it may be heat conduction by contact or radiation without contact.

[0054] As described above, according to the first embodiment, 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 life of the device. EXAMPLES

[0055] [Forced 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 as the biasing means of the second embodiment biases the heating element in a direction perpendicular to the conveying direction and the rotation axis direction.

[0056] A fixing device 100 of the second embodiment is shown in Fig. 10. Fig. 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 Fig. 10(b) is a cross-sectional view taken along line JJ in Fig. 10(a). In the second embodiment, as shown in Fig. 10(a), leaf springs B4 are arranged as urging members at both ends in the longitudinal direction, outside the area where the recording material passes through.

[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 conveying 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 fixes the leaf spring B4 to the holding member 12 by being hooked onto a corner portion 12k of the holding member 12. More specifically, the hook portion B4d has a hook portion B4dd that is hooked onto a downstream corner portion 12kd of the holding member 12, and a hook portion B4du that is hooked onto an upstream corner portion 12ku of the holding member 12. The convex portion B4e is formed on the flat portion B4a, and is a portion that protrudes in a triangular shape at a position where the leaf spring B4 enters the gap Su when fixed to the holding member 12.

[0059] 10(b), the leaf spring B4 is hooked and fixed to a corner 12k of the holding member 12. A triangular protrusion B4e is formed in the leaf spring B4 at a position corresponding to a gap Su between the heater 11 and the upstream end surface 12us of the slot 12a of the holding member 12, and the leaf spring B4 is fixed to fit into the gap Su. The heater 11 is biased by the inclined surface B4f of the triangular protrusion B4e, so that the heater 11 is biased in two directions, that is, the downstream side of the transport 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 conveying direction. The upstream end surface 12us faces the heater 11 on the upstream side in the conveying direction and forms a gap Su. The bottom surface 12ab forms the slot 12a together with the abutment surface 12ds and the upstream end surface 12us. The holding member 12 also has a surface 12l on the opposite side to 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 12kd which is one end in the conveying direction on the opposite surface 12l and a corner 12ku which is 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 toward the downstream side 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 figure) prevents the heater 11 from shifting toward the upstream side. In addition, the biasing force toward the holding member 12 (z direction in the figure) prevents the heater 11 from separating from the holding member 12, and increases the frictional force of 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 as shown in FIG.

[0063] (Leaf spring variation 1) FIG. 11(a) is a cross-sectional view showing the shape of the leaf spring B5 as 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 of 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 protruding portion B5e. The flat portion B5a is a portion that covers at least the heater 11 from the upstream side to the downstream side in the transport direction Dr when viewed from the pressure roller 20 side. The flat portion B5c is a portion that covers the holding member 12 from the pressure roller 20 side toward the fixing film 13 side on the downstream 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 fixes the leaf spring B5 to the holding member 12 by being hooked onto a corner portion 12k of the holding member 12. The protrusion portion B5e is a portion that is formed on the flat portion B5a and protrudes in a triangular shape at a position where the leaf spring B5 enters the gap Su in a state where it is fixed to the holding member 12. The protrusion portion B5e has a slope B5f that comes into contact with the heater 11.

[0066] As shown in Fig. 11(a), for example, the angle α of the leaf spring B5 is set in advance to be smaller than 90 degrees (α<90 degrees), and the leaf spring B5 is shaped as shown by the solid line. 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 tries to return to its original shape, a biasing force F1 acts in the z direction in the figure, and as a result, the heater 11 is biased toward the downstream side of the transport direction Dr (x direction in the figure) and toward the holding member 12 (z direction in the figure). As a result, it is possible to obtain the same effect as that 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 to the surface on which the slot 12a is provided in the direction perpendicular to the conveying direction and the rotation axis direction, and a corner portion 12k, which is an end portion on the downstream side in the conveying direction of the surface 12l. The leaf spring B5 has a hook portion B5d that is hooked on the corner portion 12k, a protrusion portion B5e that is a triangular shape in a 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 in a direction toward the hook portion B5d compared to when the leaf spring B5 is biasing the heater 11. The protrusion portion B5e biases the heater 11 toward the downstream side in the conveying direction and toward the bottom surface 12ab.

[0068] (Leaf spring variation 2) 11(c) and (d) show the shape of a leaf spring B6 as a modified example of the biasing member. The leaf spring B6, which is a 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. The flat portion B6a is a portion that covers the heater 11 from the upstream side to the downstream side in the conveying direction Dr when viewed from the pressure roller 20 side. The flat portion B6c is a portion that covers the holding member 12 from the pressure roller 20 side toward the fixing film 13 side on the downstream 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 fixes the leaf spring B6 to the holding member 12 by hooking it onto a corner portion 12k of the holding member 12. The abutment portion B6e is a portion where the flat portion B6a is curved 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 fixed to the holding member 12. The flat portion B6a is bent into a "L" shape at the bent portion B6f and continues to the abutment portion B6g. The abutment portion B6g enters the gap Su when the leaf spring B6 is fixed to the holding member 12, abuts against the corner portion 11f of the heater 11, and urges the heater 11 downstream.

[0070] The leaf spring B6 is also set so that the flat portion B6a bends in a direction closer to the hook portion B6d than when it is in the biased state as shown in Fig. 11(c), and is shaped as 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 Fig. 11(c). When the leaf spring B6 tries to return to its original shape, a biasing force F2 acts in the z direction in the figure, and as a result, the heater 11 is biased downstream in the transport direction Dr (x direction in the figure) and toward the holding member 12 (z direction in the figure). In this case, too, the same effect as in the case of the leaf spring B5 can be obtained.

[0071] As described above, the heater 11 of the second modification has a surface 11h which is a second surface parallel to the bottom surface 12ab and not in contact with the bottom surface 12ab, a surface 11g which is a third surface facing the upstream end surface 12us, and a corner 11f formed by the surfaces 11h and 11g. The leaf spring B6 has a hook B6d which is hooked onto the corner 12k, a contact portion B6e which is a first pressing portion which presses the surface 11h, and a contact portion B6g which is a second pressing portion which presses the corner 11f. When the leaf spring B6 is not biasing the heater 11, the contact portions B6e and B6g are inclined in a direction toward the hook B6d compared to when the leaf spring B6 is biasing the heater 11. The contact portion B6e urges the heater 11 toward the bottom surface 12ab, and the contact portion B6g urges 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 (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. The flat portion B7a is a portion that covers the heater 11 from the upstream side to the downstream side in the conveying direction Dr when viewed from the pressure roller 20 side. The flat portion B7c is a portion that covers the holding member 12 from the pressure roller 20 side toward the fixing film 13 side on the downstream 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 the leaf spring B7 to the holding member 12 by being hooked on a corner portion 12k of the holding member 12. The abutting portion B7e is a portion where the flat portion B7a is curved toward the hook portion B7d, and is a portion that abuts against the heater 11 and urges the heater 11 in the z direction when the leaf spring B7 is fixed to the holding member 12. The flat portion B7a is bent toward the hook portion B7d at the bent portion B7f and continues to the portion B7g. The portion B7g is further bent toward the hook portion B7d and continues to the pressing portion B7h. The pressing portion B7h enters the gap Su when the leaf spring B7 is fixed to the holding member 12, and presses the 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 set 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 Fig. 11(e), and is shaped as shown by the solid line. When this leaf spring B7 is fitted into the holding member 12, it is elastically deformed into the shape shown by the dotted line in Fig. 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, and as a result, the heater 11 is biased downstream in the transport direction Dr (x direction in the figure) and toward the holding member 12 (z direction in the figure). In this case, too, the same effect as in the case of the leaf spring B5 can be obtained.

[0075] As described above, the holding member 12 of the third modified example has a surface 12l, which is a first surface opposite to the surface on which the slot 12a is provided in the direction perpendicular to the conveying direction and the rotation axis direction, and a corner 12k, which is a 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 that is hooked on 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 in a direction 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 toward the downstream side in the conveying direction.

[0076] As described above, according to the second embodiment, 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 life of the device. EXAMPLES

[0077] In the first and second embodiments, a configuration has been shown in which the members for biasing the heater 11 as a heating element are disposed on both sides in the longitudinal direction of the heater 11. 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, and is characterized by a simplification of the configuration of the fixing device 100. This leads to an improvement in ease of assembly by reducing the number of assembly steps, and further reduction in the number of parts is possible.

[0078] [Using member of embodiment 3] Fig. 12(a) is a schematic diagram showing the fitted state of heater 11 and holding member 12 and the arrangement of power supply connector 30 in fixing device 100 of Example 3, with power supply connector 30 shown as transparent to show the positional relationship with contact 11e of heater 11. Also, in Fig. 12(a), the urging member on the opposite side to the side where power supply connector 30 is provided in the longitudinal direction of heater 11 is omitted. Fig. 12(b) is a cross-sectional view of contact 11e of heater 11 taken along line KK.

[0079] As shown in the cross-sectional view of FIG. 12(b), the power supply connector 30, which is a power supply part, has a U-shaped housing part 31 made of resin and a power supply terminal 32. The heater 11 and the holding member 12 are inserted and fixed in the U-shaped space formed by the housing part 31. The power supply terminal 32 is connected to a bundle of wires 33. The power supply terminal 32 has a contact part 32a, which is exposed from the housing part 31 and contacts the contact 11e of the heater 11. The power supply terminal 32 is made of a metal such as SUS, and its elasticity allows it to contact the contact 11e of the heater 11 with a predetermined contact pressure to maintain an electrical connection. In addition, the power supply terminal 32 has an urging part 32f exposed from the housing part 31. The urging part 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 to the heater 11 so as to enter the gap Su between the heater 11 and the upstream end surface 12us of the slot 12a of the holding member 12 in a state in which 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 portion 11f of the heater 11 with the inclined surface 32g in a state in which 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] (Comparison with 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 a function of contacting a power supply terminal 320 arranged therein with a contact point 11e of a heater 11. The power supply connector 300 has a cable bundle 330 and a housing part 310.

[0081] In contrast, in the fixing device 100 of the third embodiment, 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 the third embodiment includes the heater 11 and the contact 11e that is provided outside the paper passage area in the rotation axis direction and supplies power to the heater 11. The power supply connector 30 (connector) includes the cable 33, the contact portion 32a that is a contact portion connected to the cable 33 and contacts the contact 11e, the biasing portion 32f that is a biasing means, and the housing portion 31 that contains the contact portion 32a and the biasing portion 32f. The biasing portion 32f is a protruding portion that continues from the contact portion 32a toward the upstream side in the conveying direction, has a triangular shape in a cross section perpendicular to the rotation axis direction, protrudes toward the gap Su, and has a slope 32g. The slope 32g biases the heater 11 toward the downstream side in the conveying 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 which is a modified example of the embodiment 3. As shown in Fig. 13(b), a biasing portion 31f for biasing 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 an inclined surface 31h.

[0084] The biasing portion 31f applies a biasing force to the power supply connector 30A so as to enter the gap Su between the heater 11 and the upstream end surface 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. 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, the heater 11 is biased both downstream in the conveying direction Dr (x direction in the figure) and toward the holding member 12 (z direction in the figure), similar to the biasing portion 32f provided on the power supply terminal 32 described above. In this way, a biasing force can be applied to the heater 11 even by using a part of the housing portion 31A of the power supply connector 30A.

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

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

[0087] As described above, according to the third embodiment, 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 life of the device. EXAMPLES

[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-mentioned fixing device 100 can be applied. The laser beam printer 1000 (hereinafter referred to as the printer 1000) includes a photosensitive drum 1010, a charging section 1020, and a developing section 1030. The photosensitive drum 1010 is an image carrier on which an electrostatic latent image is formed. The charging section 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 section 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 the transfer section 1050 onto a sheet P (recording material) as a recording material supplied from a cassette 1040, and the unfixed toner image transferred onto the sheet P is fixed by the fixing device 100 and discharged onto a tray 1070. The photosensitive drum 1010, the charging section 1020, the developing section 1030, and the transfer section 1050 constitute an image forming section (image forming means). The printer 1000 also includes a power supply device 1080, which supplies power to a drive section such as a motor and a control section 5000. The control section 5000 has a CPU (not shown) and controls the image forming operation by the image forming section, the conveying operation of the sheet P, the temperature of the heater 11 of the fixing device 100, and the like. When the printer 1000 finishes the printing operation, a predetermined time elapses, and the printer 1000 transitions to a standby state in which the printer 1000 can immediately execute the printing operation. After a further predetermined time has elapsed, the 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. The 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 the control unit 5000 transitions the printer to each state. Note that the image forming apparatus to which the fixing device 100 of the present invention can be applied is not limited to the configuration exemplified in FIG.

[0090] As described above, according to the fourth embodiment, 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 life of the device.

[0091] The disclosure of this embodiment includes the following configuration. (Configuration 1) A fixing device that holds 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 conveying direction, A flexible cylindrical rotor; a heating body disposed inside the rotating body, extending in a direction of a rotation axis of the rotating body perpendicular to the conveying direction, the heating body 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 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 the pressure member 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 body held in the groove portion toward a downstream side in the conveying direction; Equipped with A fixing device characterized in that the urging means is provided upstream of the holding member in the transport direction, and is provided outside a paper passing area, which is an area in the rotational axis direction through which the recording material that has the longest length in the rotational axis direction among the recording materials that can be transported by the fixing device is transported. (Configuration 2) The biasing means is a coil spring. The fixing device according to the above, wherein the holding member has a housing portion for housing the coil spring. (Configuration 3) The biasing means is a leaf spring, The fixing device according to the 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 heat from the heater to the rotating body; The fixing device as 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 above, 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 direction of the rotation axis. (Configuration 6) the heating body includes a heater and a sliding plate that covers the heater and uniformly transfers heat from 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 as described above, wherein the biasing means is the bent portion. (Configuration 7) The fixing device according to the above, wherein the biasing means biases the heating body 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 is abutted 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 another 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 the above, wherein the protruding portion 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 is abutted 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 protruding 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 protruding 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 the above, wherein the protruding portion 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 is abutted 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 body 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 according to the 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 is abutted 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 body has a second surface parallel to the bottom surface and not in contact with the bottom surface, and a third surface opposed to 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 according to the above, wherein the second pressing portion urges the heating element toward a downstream side in the transport direction. (Configuration 12) the heating element includes a heater and a contact point that is provided outside the sheet passing area in the direction of the rotation axis and that supplies power to the heater; the groove portion has a first side surface against which the heating body is abutted 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 cable, a contact portion connected to the cable and in contact with the contact point, the biasing means, and a housing portion containing the contact portion and the biasing means, the biasing means includes a protrusion that continues from the contact portion toward an upstream side in the conveying direction, has a triangular shape in a cross section perpendicular to the rotation axis direction, and protrudes toward the gap, The fixing device according to the above, wherein the protruding portion urges the heating element toward the downstream side in the transport direction and toward the bottom surface. (Configuration 13) the heating element includes a heater and a contact point that is provided outside the sheet passing area in the direction of the rotation axis and that supplies power to the heater; the groove portion has a first side surface against which the heating body is abutted 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 cable, a contact portion connected to the cable and in contact with the contact point, the biasing means, and a housing portion containing the contact portion, the biasing means is provided on a part of the housing portion and has a protrusion protruding toward the gap, The fixing device according to the above, wherein the protruding portion 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 described above fixes 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 holds 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 conveying direction, A flexible cylindrical rotor; a heating body disposed inside the rotating body, extending in a direction of a rotation axis of the rotating body perpendicular to the conveying direction, the heating body 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 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 the pressure member 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 body held in the groove portion toward a downstream side in the conveying direction; Equipped with A fixing device characterized in that the urging means is provided upstream of the holding member in the transport direction, and is provided outside a paper passing area, which is an area in the rotational axis direction through which the recording material that has the longest length in the rotational axis direction among the recording materials that can be transported by the fixing device is transported.

2. The biasing means is a coil spring. The fixing device according to claim 1 , wherein the holding member has a housing portion for housing the coil spring.

3. The biasing means is a leaf spring, The fixing device according to claim 1 , wherein the holding member has a holding portion that holds the leaf spring.

4. the heating body includes a heater and a sliding plate that covers the heater and uniformly transfers heat from 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.

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

6. the heating body includes a heater and a sliding plate that covers the heater and uniformly transfers heat from the heater to the rotating body; the sliding plate has an elastic bent portion outside the paper passing area in the rotation axis direction, 2. The fixing device according to claim 1, wherein the biasing means is the bent portion.

7. 2. The fixing device according to claim 1, wherein the biasing means biases the heating body in a direction perpendicular to the transport direction and the direction of the rotation axis.

8. the groove portion has a first side surface against which the heating body is abutted 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 another 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 claim 1 , wherein the protrusion urges the heating element toward a downstream side in the transport direction and toward the bottom surface.

9. the groove portion has a first side surface against which the heating body is abutted 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 protruding 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 protruding 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 claim 1 , wherein the protrusion urges the heating element toward a downstream side in the transport direction and toward the bottom surface.

10. the groove portion has a first side surface against which the heating body is abutted 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 body 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 according to claim 1 , wherein the second pressing portion urges the heating element toward a downstream side in the transport direction and toward the bottom surface.

11. the groove portion has a first side surface against which the heating body is abutted 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 body has a second surface parallel to the bottom surface and not in contact with the bottom surface, and a third surface opposed to 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 according to claim 1 , wherein the second pressing portion urges the heating element toward a downstream side in the transport direction.

12. the heating element includes a heater and a contact point that is provided outside the sheet passing area in the direction of the rotation axis and that supplies power to the heater; the groove portion has a first side surface against which the heating body is abutted 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 cable, a contact portion connected to the cable and in contact with the contact point, the biasing means, and a housing portion containing the contact portion and the biasing means, the biasing means includes a protrusion that continues from the contact portion toward an upstream side in the conveying direction, has a triangular shape in a cross section perpendicular to the rotation axis direction, and protrudes toward the gap, The fixing device according to claim 1 , wherein the protrusion urges the heating element toward a downstream side in the transport direction and toward the bottom surface.

13. the heating element includes a heater and a contact point that is provided outside the sheet passing area in the direction of the rotation axis and that supplies power to the heater; the groove portion has a first side surface against which the heating body is abutted 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 cable, a contact portion connected to the cable and in contact with the contact point, the biasing means, and a housing portion containing the contact portion, the biasing means is provided on a part of the housing portion and has a protrusion protruding toward the gap, The fixing device according to claim 1 , wherein the protrusion urges the heating element toward a downstream side in the transport direction and toward the bottom surface.

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

Images