Fixing device

Abstract

This invention provides a fixing device that is an advanced version of the conventional design. [Solution] A protective member made of resin is provided between the portion of the regulating member that is pressed by the pressure arm and the pressure arm, and the pressure arm presses the regulating member through the protective member.

Description

Technical Field

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[0001] The present invention relates to a fixing device provided in an image forming apparatus using an electrophotographic method.

Background Art

[0002] In an image forming apparatus using an electrophotographic method, a fixing device adopting an on-demand fixing method as disclosed in Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0006] Furthermore, in order to achieve the above objective, another fixing device of the present invention includes a belt unit having a cylindrical belt, a heater disposed in the internal space of the belt, a holder for holding the heater, and a restricting member disposed at a position opposite to the end of the belt in the longitudinal direction of the belt and restricting the movement of the belt in the longitudinal direction of the belt; a pressure roller that contacts the outer surface of the belt and, together with the heater, sandwiches the belt and forms a fixing nip portion between itself and the belt; a frame that rotatably holds the pressure roller and the restricting member, thereby holding the belt unit; and a pressure roller rotatably provided on the frame for forming the fixing nip portion. A fixing device having a metal pressure arm for applying force to the regulating member, fixing a toner image formed on the recording material while gripping and transporting the recording material with the fixing nip, wherein the frame is made of resin, and when viewed in the longitudinal direction of the belt, the pivot axis of the pressure arm is located upstream in the recording material transport direction and between the pivot center of the pressure roller and the end of the holder on the side where the pressure arm is located in a direction perpendicular to the longitudinal direction of the belt and the recording material transport direction, and a lubricant is applied as a lubricant between the portion of the regulating member that is pressed by the pressure arm and the pressure arm, and the pressure arm presses the regulating member via the lubricant. [Effects of the Invention]

[0007] This invention provides a fixing device that is an advanced version of the conventional design. [Brief explanation of the drawing]

[0008] [Figure 1] (a) A perspective view of the fixing device. (b) A perspective view of the fixing device. [Figure 2] This is a cross-sectional view of an image forming apparatus. [Figure 3] This is a cross-sectional view of the heating unit and pressure roller. [Figure 4] This is a cross-sectional view of the fixing device. [Figure 5] This is a disassembled perspective view of the fixing device. [Figure 6] This is a top view of the holder. [Figure 7] This is a disassembled perspective view of the heating unit. [Figure 8] This is a top view of the heating unit. [Figure 9] Front view and cross-sectional view of the fixing device in Example 1. [Figure 10] Top view and enlarged view of the lower frame and pressure roller in Example 1. [Figure 11] Cross-sectional views of the pressurizing mechanism and the pressure release mechanism in the pressurized and pressure release states in Example 1. [Figure 12] Exploded perspective view of the lower frame, upper frame, camshaft, and cam in Example 1. [Figure 13] A diagram showing the mounting state of the anti-abrasion member in Example 1. [Figure 14] Cross-sectional views of the pressurizing mechanism and the pressure release mechanism in the pressurized and pressure release states in Comparative Example 1. [Figure 15] A diagram showing the mounting state of the pressure arm support in Example 2. [Figure 16] Cross-sectional views of the pressurizing mechanism and the depressurizing mechanism in the pressurized and depressurized states in Example 3. [Modes for carrying out the invention]

[0009] [Example 1] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0010] [Image forming apparatus] Figure 2 is a cross-sectional view of the electrophotographic image forming apparatus 1 in the present embodiment. However, dimensions, materials, shapes, relative arrangements, etc. of the components described in the present embodiment may be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless specifically specified, the scope of the present invention is not limited thereto. In the following description, the left side in FIG. 2 is defined as the front side of the image forming apparatus 1, the right side as the rear side of the image forming apparatus 1, the front side of the paper surface as the right side of the image forming apparatus 1, and the back side of the paper surface as the left side of the image forming apparatus 1. Also, the upper side and the lower side in FIG. 2 are defined as the upper side and the lower side of the image forming apparatus 1, respectively.

[0011] As shown in FIG. 2, the image forming apparatus 1 has a device main body 2 and a process cartridge 10, and the process cartridge 10 is detachably installed in the device main body 2. The device main body 2 is provided with a paper feed tray 3, a recording material feeding unit 4, a conveyance path P, an image forming unit 5, a fixing device 6, a recording material discharging unit 7, a paper discharge tray 8, a laser scanner 9, and the like. On the other hand, the cartridge 10 is provided with a photosensitive drum 11, a developing roller 12 as a developer carrier, and the like.

[0012] Note that an opening and closing door 21 is provided to close an opening 2A provided in the device main body 2 for attaching and detaching the process cartridge 10. The opening and closing door 21 is supported so as to be rotatable about a rotation shaft 21a, and is movable between a closed position for closing the opening 2A and an open position for opening the opening 2A.

[0013] The recording material feeding unit 4 includes a paper feed roller 41, a separation roller 42, a separation pad 42a, and a pair of conveyance rollers 43. Based on the print start signal, the recording material S stored in the paper feed tray 3 is sent out to the conveyance path P by the recording material feeding unit 4 and conveyed toward the image forming unit 5 through the registration roller pair 44. When the recording material S is conveyed to a predetermined position, an image forming start signal is issued, and the image forming process is started. The photosensitive drum 11 rotationally driven by a drive source (motor) not shown is uniformly charged to a predetermined potential by a charging means not shown. After charging, the surface of the photosensitive drum 11 is exposed based on image information by the laser scanner 9, and the charge in the exposed portion is removed to form an electrostatic image. The toner in the process cartridge 10 is carried on the developing roller 12 and supplied to the photosensitive drum 11 according to the electrostatic latent image to develop the latent image. As a result, the latent image is visualized as a toner image on the photosensitive drum 11.

[0014] The image forming unit 5 includes a process cartridge 10 and a transfer roller 51 disposed opposite to the photosensitive drum 11 of the process cartridge 10. When the recording material S conveyed by the registration roller pair 44 reaches the image forming unit 5 and passes through the transfer nip portion between the photosensitive drum 11 and the transfer roller 51, a voltage is applied from the apparatus main body 2 to the transfer roller 51, and the toner image on the photosensitive drum 11 is transferred to the recording material S. Thereafter, the recording material S onto which the toner image has been transferred is conveyed to a fixing device 6 including a heating unit 61 and a pressure roller 62 that contacts the outer peripheral surface of the cylindrical belt 614. When the recording material S is sandwiched and conveyed at the fixing nip portion NP1 of the heating unit 61 and the pressure roller 62, the toner image transferred onto the recording material S is heated and pressurized to be fixed on the surface of the recording material S. The recording material S onto which the toner image has been fixed is discharged to the paper discharge tray 8 through the recording material discharge unit 7.

[0015] [Fixing Device] Next, the specific configuration of the fixing device will be described using Figures 3 to 8. As shown in Figure 3, the heating unit (belt unit) 61 of the fixing device 6 comprises a heater 611, a holder 612, a stay 613, a belt 614, and transmission members (regulating members) 651a and 651b. The heater 611, holder 612, and stay 613 are arranged in the internal space of the belt 614. If we define the X, Y, and Z directions as shown in Figure 3, the heater 611 is a flat plate extending in the Y direction, and the Y direction coincides with the longitudinal direction of the belt 614. It also has a first surface 611a and a second surface 611b opposite to the first surface 611a, and the first surface 611a is supported by the holder 612.

[0016] The holder 612 is made of a heat-resistant resin such as PPS or liquid crystal polymer, and has a guide surface 612a and a support wall 612b. The guide surface 612a contacts the inner circumferential surface 614a of the belt 614 to guide the belt 614, and the support wall 612b has a support surface 612b1 that supports the heater 611. The support surface 612b1 of the support wall 612b is in contact with the first surface 611a of the heater 611. The stay 613 is a member that supports the holder 612, and is formed by bending a plate material with greater rigidity than the holder 612, for example, a steel plate with a thickness of 1.6 mm, into a roughly U-shape.

[0017] The belt 614 is an endless belt that is heat-resistant and flexible. For example, it may be made of a metal sleeve such as stainless steel coated with fluororesin, or made of laminated polyimide resin, silicone rubber, fluororesin, etc. Inside the belt 614 are a heater 611, a holder 612, and a stay 613, and the belt 614 rotates around these components. The inner circumferential surface 614a of the belt 614 is in contact with the second surface 611b of the heater 611.

[0018] The pressure roller 62 has a metal shaft 62a and a roller 62b made of an elastic material covering the shaft 62a, and is pressed against the heater 611 via a belt 614. The pressure roller 62 sandwiches the belt 614 between itself and the heater 611 to form a fixing nip section NP1 for nipping, heating, and pressurizing the recording material S. In other words, the pressure roller 62 heats and pressurizes the recording material S together with the heater 611 at the fixing nip section NP1.

[0019] The pressure roller 62 is configured to rotate when a driving force is transmitted from a drive source provided by the image forming apparatus 1. As the pressure roller 62 rotates, the belt 614 rotates passively due to the frictional force between the belt 614 and the recording material S held between the fixing nip NP1. As a result, the recording material S on which the toner image has been transferred is transported between the pressure roller 62 and the heated belt 614, and the toner image is heat-fixed.

[0020] As shown in Figures 4 to 8, the fixing device 6 has a lower frame 63 that supports the heating unit 61 and the pressure roller 62, and an upper frame 64 located above the lower frame 63 and covering the heating unit 61. The upper frame 64 has an upper recording material guide 64a that guides the upper surface of the recording material S being transported along the transport path P on the downstream side in the recording material transport direction of the heating unit 61 and the pressure roller 62. The lower frame 63 has a lower recording material guide 63a that guides the lower surface of the recording material S being transported along the transport path P on the downstream side in the recording material transport direction of the heating unit 61 and the pressure roller 62.

[0021] The transport path P in the fixing device 6 extends in the X direction. In this embodiment, the lower frame 63 and the upper frame 64 are formed from, for example, a non-conductive molded material. For example, the material of the molded material may be polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or polyphenylene sulfide (PPS). Furthermore, PET or PBT may be reinforced with glass fibers.

[0022] As shown in Figure 5, the lower frame 63 supports the heating unit 61 and the pressure roller 62. The lower frame 63 has a pair of rails 63b at each end in the Y direction. The rails 63b support the holder 612 so that it can move in the Z direction (first direction) via transmission members (regulating members) 651a and 651b, which are members that transmit pressure to the stay 613 (details will be described later). The transmission members (regulating members) 651a and 651b restrict the movement of the belt 614 in the longitudinal direction of the belt. The rails 63b are columnar parts that extend in the Z direction from the main body 63c of the lower frame 63. The pair of rails 63b face each other in the X direction. The opposing surfaces of the rails 63b engage with grooves 651a1 and 651b1 provided on the transmission members 651a and 651b, respectively. In this embodiment, the rail 63b is a columnar portion extending in the Z direction, but it is not limited to the shape of this embodiment, as long as it has a shape that can support the holder 612 so that it can move in the Z direction.

[0023] Furthermore, the pressure roller 62 is rotatably held by the lower frame 63 via bearings 62c and 62d at both longitudinal ends of a metal shaft 62a. At this time, the position of bearing 62c is determined when a projection 62c1 provided on bearing 62c fits into a groove 63d1 provided on the lower frame 63. Similarly, the position of bearing 62d is determined when a projection 62d1 provided on bearing 62d fits into a groove 63d2 provided on the lower frame 63. Bearing 62c is made of a conductive material. In this embodiment, projections 62c1 and 62d are provided on bearings 62c and 62d, and grooves 63d1 and 63d2 are provided on the lower frame 63, but grooves may be provided on bearings 62c and 62d, and projections may be provided on the lower frame 63.

[0024] As shown in Figure 6, the support wall 612b of the holder 612 has a plurality of holes 612b2, 612b3. As shown in Figure 6, temperature sensors 613a and 613b are provided on the back surface 612b4 of the holder 612, opposite to the support surface 612b1. As shown in Figure 7, the temperature sensors 613a and 613b contact the first surface 611a of the heater 611 through the holes 612b2, 612b3. The temperature sensors 613a and 613b are pressed against the first surface 611a of the heater 611 (see Figure 3) by biasing members 613c and 613d provided between the stay 613 and the temperature sensors 613a and 613b. Temperature sensor 613a is located at one end of the holder 612 in the Y direction. Temperature sensor 613b is located closer to one end than to the center of the holder 612 in the Y direction. The temperature sensors 613a and 613b are thermistors in this case, but other temperature sensors such as thermostats may also be used. The biasing members 613c and 613d are coil springs in this case, but other biasing members may also be used.

[0025] As shown in Figures 5 and 8, the holder 612 extends in the Y direction through the interior of the belt 614, with both ends in the Y direction extending outward from the belt 614. The holder 612 supports the heater 611, and one end of the heater 611 in the Y direction is provided with a first wire spring 615a that holds the heater 611 in the holder 612, and a connector 616 that supplies power to the heater 611 and clamps the heater 611 and the holder 612. The other end of the heater 611 in the Y direction is provided with a second wire spring 615b that holds the heater 611 in the holder 612. The temperature sensors 613a and 613b are located closer to the first wire spring 615a than to the second wire spring 615b in the Y direction. The first wire spring 615a is provided between the belt 614 and the connector 616. The second spring 615b is provided in the region extending outward from the belt 614 on the other end where the first spring 615a is located. In this embodiment, the pressure roller 62 comprises a shaft 62a and a roller 62b, but it is not limited to this and may also include a pressure belt that is pressed against the heating roller by an elastic member.

[0026] [Pressurization mechanism] As shown in Figures 9-10, the fixing device 6 has a pressurizing mechanism 65 that applies pressure to form a fixing nip portion NP1 between the heating unit 61 and the pressure roller 62. The pressurizing mechanism 65 is located at both ends of the lower frame 63 in the Y direction. Since the structure of one side of the pressurizing mechanism 65 in the Y direction and the structure of the other side are substantially the same, the following description will mainly focus on the one side in the Y direction.

[0027] The pressurizing mechanism 65 supports the heating unit 61 at its end in the Y direction and includes a member (transmission member 651) that transmits pressure to a stay supported by rail 63b so as to be movable in the Z direction. The pressurizing mechanism 65 also includes a pressurizing arm 652 for applying pressure to the transmission member 651, which is mounted on the lower frame 63, in order to form the fixing nip portion NP1. In addition, the pressurizing mechanism 65 includes a pressurizing spring 653 stretched between the lower frame 63 and the pressurizing arm 652, which generates pressure to press the pressurizing arm 652 against the transmission member 651. The lower frame 63 has a pressurizing arm support portion 64d that supports the pressurizing arm 652 so as to be rotatable around a pivot axis X1. The pressurizing arm support portion 64d is a substantially cylindrical projection. The pressurizing spring 653 is a tension coil spring that biases the pressurizing arm 652 toward the pressurizing roller 62. The lower frame 63 has a spring attachment portion 63m on which one end of the pressure spring 653 is hooked. For example, the portion of the resin lower frame 63 that supports the pressure arm 64d may be made of metal, or a metal member may be attached only to the portion of the pressure arm support portion 64d that contacts the pressure arm 652. Also, the portion of the resin lower frame 63 that attaches the spring attachment portion 63m may be made of metal.

[0028] At least a portion of the pivot axis X1 on which the pressure arm 652 rotates is located upstream of the fixing nip NP1 in the recording material transport direction when viewed in the Y direction, and within the range T in the Z direction (a direction perpendicular to the longitudinal direction of the belt and the recording material transport direction) as shown in Figure 9(b). Here, the range T in the Z direction shown in Figure 9(b) is between the rotation center of the pressure roller 62 in the Z direction and the Z-direction end of the holder 612 on the pressure arm side (the end of the holder 612 furthest from the rotation center of the pressure roller in the Z direction). Because there is a distance in the Z direction between the point where the pressure arm 652 pressurizes the transmission member 651 and the pivot axis X1, the pressure arm 652 is bent in an L-shape. Furthermore, the upstream side in the recording material transport direction is on the X-direction side of the fixing nip NP1 to the photosensitive drum 11.

[0029] [Pressure release mechanism] As shown in Figure 11, the fixing device 6 further includes a pressure release mechanism 67 for releasing the nip pressure applied to the fixing nip portion NP1 between the heating unit 61 and the pressure roller 62 in Figure 9. The pressure release mechanism 67 comprises a camshaft 671 and a cam 672. The lower frame 63 supports the pressure spring 653 and rotatably supports the pressure arm 652 and the cam 672. The cam 672 is located at the ends of the lower frame 63 in the Y direction. Since the structure of one side of the pressure release mechanism 67 in the Y direction and the structure of the other side are substantially the same, the structure of one side in the Y direction will be mainly described as representative below.

[0030] As shown in Figure 12, the camshaft 671 extends in the Y direction. The camshaft 671 is made of metal, for example. Cams 672 are fixed to each end of the camshaft 671 in the Y direction. In other words, the cam 672 has the camshaft 671. The cam 672 rotates in conjunction with the rotation of the camshaft 671. The lower frame 63 has shaft support portions 63l that rotatably support the camshaft 671. As shown in Figure 12, the shaft support portions 63l are located at one end and the other end of the lower frame 63 in the Y direction. The shaft support portions 63l have holes H that rotatably support the camshaft 671.

[0031] Furthermore, as shown in Figure 12, the upper frame 64 has grooves 64C that rotatably support the camshaft 671. The grooves 64C are located at one end and the other end of the upper frame 64 in the Y direction. The camshaft 671 is held between the upper frame 64 and the lower frame 63. As shown in Figure 11, the camshaft 671 is rotatably supported about axis X2. The cam 672 is capable of pressing the pressure arm 652 against the biasing force of the pressure spring 653. Specifically, the cam 672 is rotatable between a first position shown in Figure 11(a) and a second position shown in Figure 11(b). In this embodiment, as shown in Figure 11, a wear prevention member (protective member) 700 is provided between the pressure arm 652 and the transmission member 651.

[0032] As shown in Figure 13, the anti-abrasion member 700 is a U-shaped member made of resin and is attached to the lower surface of the pressure arm 652, which is made of metal sheet metal, by sandwiching it in a U-shape in the Y direction. In this invention, the lower frame 63 is made of resin, and the pressure arm support part 64d and the spring attachment part 63m, which are provided on the lower frame 63 and support the pressure arm 652 so as to be rotatable around axis X1, are also made of resin. A large force is applied to the pressure arm support part 64d and the spring attachment part 63m as a reaction force when the pressure arm 652 is pressed. Therefore, considering the deformation of the pressure arm support part 64d and its surrounding parts, it is desirable to provide the pressure arm support part 64d in a position close to the bearing 62c that supports the shaft 62a of the pressure roller 62. This is because the shaft 62a of the pressure roller 62 is made of metal and can therefore function as a structure itself. When the position where the pressure arm support part 64d is provided is located close to the bearing 62c, the pressure arm 652 inevitably takes on an L-shape.

[0033] The configuration of Comparative Example 1 is shown in Figure 14. In Comparative Example 1, as shown in Figure 14, no member is provided between the pressurizing arm 652 and the transmission member 651.

[0034] [Effects of this example] In this embodiment, the pressure arm support portion 64d of the pressure arm 652 and the spring attachment portion 63m to which one end of the pressure spring 653 is hooked are made of resin, so their rigidity is lower compared to when they are made of a highly rigid material such as metal. The pressure roller 62 is configured to rotate when a driving force is transmitted from a drive source provided in the image forming apparatus 1, but the fixing device 6 vibrates to a considerable extent due to the vibration of the pressure roller 62 and the vibration of a gear (not shown) that transmits the rotational drive.

[0035] If the anti-abrasion member 700 is not provided, the transmission member 651 made of resin and the pressure arm 652 made of metal will rub against each other due to vibration, causing abrasion mainly to the part of the transmission member 651 that comes into contact with the pressure arm 652. When the transmission member 651 abrades, there is a concern that the resulting abrasion dust may get into the space between the shaft 62a and the bearing 62c of the pressure roller 62, inducing abrasion of the bearing 62c. Furthermore, if the transmission member 651 is severely abraded, there is a concern that the pressing force will decrease.

[0036] In this embodiment, a wear prevention member 700 is provided at the portion of the pressure arm 652 that comes into contact with the transmission member 651. As a result, even if vibrations occur in the fixing device 6 as described above, the transmission member 651 and the pressure arm 652, which is made of metal, will not rub against each other directly, thus suppressing wear of the transmission member 651 compared to Comparative Example 1.

[0037] [Example 2] In this embodiment, the same reference numerals are used for the same configuration and control as in Embodiment 1, and their explanation is omitted. In Embodiment 1, the pressure arm support 64d was made of resin, but in this embodiment, as shown in Figure 15, it is made of metal, separate from the lower frame 63. The pressure arm support 64d can be attached to the lower frame 63 with screws 64e. Since the pressure arm support 64d is made of metal, its rigidity is higher compared to Embodiment 1. However, since the lower frame 63 is made of resin, even if the pressure arm support 64d is made of metal, the same problems as in Embodiment 2 may occur. Therefore, in this embodiment as in Embodiment 2, the wear prevention member 700 can be provided to suppress wear on the transmission member 651.

[0038] [Example 3] In this embodiment, the same reference numerals are used for the same configuration and control as in Examples 1 and 2, and their descriptions are omitted. As shown in Figure 16, this embodiment is characterized in that, instead of the anti-abrasion member 700 of Example 1, the lubricant 701 is applied to the portion of the pressurizing arm 652 that comes into contact with the transmission member.

[0039] By applying the lubricant 701, the sliding resistance is reduced even when the pressurizing arm 652 and the transmission member 651 rub against each other, thereby suppressing the amount of wear. Since the wear prevention member 700 is not used, the number of components can be reduced compared to Example 1. Regarding the lubricant to be used, it is desirable to use a relatively high viscosity lubricant that has heat resistance appropriate to the operating environment and can remain between the pressurizing arm 652 and the transmission member 651.

[0040] [Note] Furthermore, the disclosure of this embodiment includes the following configuration examples and method examples.

[0041] (Item 1) A belt unit comprising: a cylindrical belt; a heater disposed in the internal space of the belt; a holder for holding the heater; and a restricting member positioned opposite the end of the belt in the longitudinal direction of the belt, which restricts the movement of the belt in the longitudinal direction of the belt. A pressure roller that contacts the outer surface of the belt, the pressure roller together with the heater to sandwich the belt and form a fixing nip portion between itself and the belt, A frame that holds the belt unit by rotatably holding the pressure roller and holding the regulating member, A metal pressure arm is rotatably mounted on the frame and applies pressure to the regulating member to form the fixing nip portion, A fixing device having the fixing nip section, which holds and transports the recording material while fixing a toner image formed on the recording material to the recording material, The material of the aforementioned frame is resin. When viewed in the longitudinal direction of the belt, the pivot axis of the pressure arm is located upstream in the recording material transport direction and between the pivot center of the pressure roller and the end of the holder on the side where the pressure arm is located, in a direction perpendicular to the longitudinal direction of the belt and the recording material transport direction. A fixing device characterized in that a protective member made of resin is provided between the portion of the regulating member that is pressed by the pressure arm and the pressure arm, and the pressure arm presses the regulating member via the protective member.

[0042] (Item 2) The fixing device described in item 1, The fixing device is characterized in that, when viewed in the longitudinal direction of the belt, the pressure arm is bent in an L-shape.

[0043] (Item 3) Fixing device as described in items 1-2, The fixing device is characterized in that the pivot axis of the pressurizing arm is made of metal attached to the frame.

[0044] (Item 4) A belt unit comprising: a cylindrical belt; a heater disposed in the internal space of the belt; a holder for holding the heater; and a restricting member positioned opposite the end of the belt in the longitudinal direction of the belt, which restricts the movement of the belt in the longitudinal direction of the belt. A pressure roller that contacts the outer surface of the belt, the pressure roller together with the heater to sandwich the belt and form a fixing nip portion between itself and the belt, A frame that holds the belt unit by rotatably holding the pressure roller and holding the regulating member, A metal pressure arm is rotatably mounted on the frame and applies pressure to the regulating member to form the fixing nip portion, A fixing device having the fixing nip section, which holds and transports the recording material while fixing a toner image formed on the recording material to the recording material, The material of the aforementioned frame is resin. When viewed in the longitudinal direction of the belt, the pivot axis of the pressure arm is located upstream in the recording material transport direction and between the pivot center of the pressure roller and the end of the holder on the side where the pressure arm is located, in a direction perpendicular to the longitudinal direction of the belt and the recording material transport direction. A fixing device characterized in that a lubricant is applied as a lubricant between the portion of the restricting member that is pressed by the pressurizing arm and the pressurizing arm, and the pressurizing arm presses the restricting member via the lubricant.

[0045] (Item 5) The fixing device described in item 4, The fixing device is characterized in that, when viewed in the longitudinal direction of the belt, the pressure arm is bent in an L-shape.

[0046] (Item 6) Fixing device as described in items 4-5, The fixing device is characterized in that the pivot axis of the pressurizing arm is made of metal attached to the frame. [Explanation of Symbols]

[0047] 2. Main unit of the device 6. Fixing device 61 Heating Unit 611 Heater 612 Holder 613 Stay 614 Belt 614b surface 62 Pressure rollers 62a shaft 62c bearing 63 Lower frame 636 Torsion spring 64 Upper Frame 65 Pressurization mechanism 66 Static electricity remover 652 Pressure Arm 653 Compression spring 660 brushes 661 Cover 662 1st conduction plate 663 Resistor 664 2nd conduction plate 667 First conductive spring 668 Main body contact spring 669 Second conductive spring 671 Camshaft 672 Cam 700 Anti-scratching component 701 Lubricant 64d Pressure arm support section 64e screw

Claims

1. A belt unit comprising: a cylindrical belt; a heater disposed in the internal space of the belt; a holder for holding the heater; and a restricting member positioned opposite the end of the belt in the longitudinal direction of the belt, which restricts the movement of the belt in the longitudinal direction of the belt. A pressure roller that contacts the outer surface of the belt, the pressure roller together with the heater to sandwich the belt and form a fixing nip portion between itself and the belt, A frame that holds the belt unit by rotatably holding the pressure roller and holding the regulating member, A metal pressure arm is rotatably mounted on the frame and applies pressure to the regulating member to form the fixing nip portion, A fixing device having the fixing nip section, which holds and transports the recording material while fixing a toner image formed on the recording material to the recording material, The material of the aforementioned frame is resin. When viewed in the longitudinal direction of the belt, the pivot axis of the pressure arm is located upstream in the recording material transport direction and between the pivot center of the pressure roller and the end of the holder on the side where the pressure arm is located, in a direction perpendicular to the longitudinal direction of the belt and the recording material transport direction. A fixing device characterized in that a protective member made of resin is provided between the portion of the regulating member that is pressed by the pressure arm and the pressure arm, and the pressure arm presses the regulating member via the protective member.

2. The fixing device according to claim 1, characterized in that the pressure arm is bent in an L-shape when viewed in the longitudinal direction of the belt.

3. The fixing device according to claim 1 or 2, characterized in that the pivot axis of the pressurizing arm is made of metal attached to the frame.

4. A belt unit comprising: a cylindrical belt; a heater disposed in the internal space of the belt; a holder for holding the heater; and a restricting member positioned opposite the end of the belt in the longitudinal direction of the belt, which restricts the movement of the belt in the longitudinal direction of the belt. A pressure roller that contacts the outer surface of the belt, the pressure roller together with the heater to sandwich the belt and form a fixing nip portion between itself and the belt, A frame that holds the belt unit by rotatably holding the pressure roller and holding the regulating member, A metal pressure arm is rotatably mounted on the frame and applies pressure to the regulating member to form the fixing nip portion, A fixing device having the fixing nip section, which holds and transports the recording material while fixing a toner image formed on the recording material to the recording material, The material of the aforementioned frame is resin. When viewed in the longitudinal direction of the belt, the pivot axis of the pressure arm is located upstream in the recording material transport direction and between the pivot center of the pressure roller and the end of the holder on the side where the pressure arm is located, in a direction perpendicular to the longitudinal direction of the belt and the recording material transport direction. A fixing device characterized in that a lubricant is applied as a lubricant between the portion of the restricting member that is pressed by the pressurizing arm and the pressurizing arm, and the pressurizing arm presses the restricting member via the lubricant.

5. The fixing device according to claim 4, characterized in that the pressure arm is bent in an L-shape when viewed in the longitudinal direction of the belt.

6. The fixing device according to claim 4 or 5, characterized in that the pivot axis of the pressurizing arm is made of metal attached to the frame.

Images