Fixing device

Abstract

This fixing device comprises: a heater; a support member that has a support surface for supporting the heater; a roller that forms a nip portion together with the heater via a belt; a reinforcement member that reinforces the support member; and a regulation member that regulates movement of the belt. The reinforcement member has a first leg portion, a second leg portion, and first and second protruding portions respectively protruding from the first and second leg portions in directions away from the longitudinal center of the reinforcement member, and the first and second protruding portions respectively have first and second abutted surfaces. The regulation member has first and second abutting surfaces that respectively abut on the first and second abutted surfaces. A width of the first abutting surface of the regulation member is larger than that of the first abutted surface of the reinforcement member, and a width of the second abutting surface of the regulation member is larger than a width of the second abutted surface of the reinforcement member.

Description

Fuser

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

[0002] In electrophotographic image forming apparatuses, fixing devices using a belt as a heating element are known (Japanese Patent Publication No. 2025-25116).

[0003] Japanese Patent Publication No. 2025-25116

[0004] One embodiment of the present invention is a fixing device for fixing an image to a sheet, comprising: an endless belt; a plate-shaped heater having a first surface extending in a first direction and a second direction intersecting the first direction, and a second surface on the opposite side of the first surface in a third direction intersecting both the first and second directions, wherein the second surface is on the side facing the inner surface of the belt; a support member having a support surface that supports the first surface of the heater; a roller that forms a nip portion together with the heater via the belt and rotates about a rotation axis extending in the first direction; a metal reinforcing member that reinforces the support member from the side of the supported surface on the opposite side of the support surface in the third direction, wherein the first direction is the longitudinal direction; and a regulating member provided with a regulating surface configured to contact the end face of the belt in the first direction and restrict the movement of the belt in the first direction, wherein the reinforcing member has a cross section perpendicular to the first direction, The reinforcing member has a first leg portion and a second leg portion that extend toward the supported surface of the support member in the third direction and support the supported surface, and are spaced apart in the second direction, and a connecting portion that connects the end of the first leg portion on the side furthest from the supported surface in the third direction and the end of the second leg portion on the side furthest from the supported surface in the third direction, and is configured such that the side of the reinforcing member opposite the connecting portion is an open portion in the third direction, and the reinforcing member has a first convex portion and a second convex portion that project in the first direction toward the longitudinal center of the reinforcing member, respectively from the first end face of the first leg portion and the second end face of the second leg portion on the same side as the first end face in the first direction, the first convex portion has a first contact surface which is the end face in the direction toward the belt from the roller in the third direction, and the second convex portion has a second contact surface which is the end face in the direction toward the belt from the roller in the third direction and is on the same side as the first contact surface,The regulating member has a first contact surface and a second contact surface that respectively contact the first abutted surface and the second abutted surface, a width of the first contact surface of the regulating member in the second direction is wider than a width of the first abutted surface of the reinforcing member in the second direction, and a width of the second contact surface of the regulating member in the second direction is wider than a width of the second abutted surface of the reinforcing member in the second direction.

[0005] It is a cross-sectional view of an image forming apparatus. It is a cross-sectional view of a heating unit and a pressure rotating member. It is a cross-sectional view of a fixing device. It is an exploded perspective view of the fixing device. It is a perspective view and a cross-sectional view of a stay. It is a perspective view and a cross-sectional view of a stay. It is a perspective view and a cross-sectional view of a stay. It is a perspective view and a cross-sectional view of a stay. It is a diagram illustrating the generation mechanism of the belt shifting force. It is a front view and a side view of a fixing flange. It is a front view and a side view of a fixing flange. It is a partial front view of the heating unit and a perspective view of a pressure member. It is a partial front view of the heating unit and a perspective view of a pressure member. It is a cross-sectional view, a front view of the fixing device, and a cross-sectional view of a pressurizing mechanism. It is a cross-sectional view, a front view of the fixing device, and a cross-sectional view of a pressurizing mechanism. It is a cross-sectional view, a front view of the fixing device, and a cross-sectional view of a pressurizing mechanism. It is a partial front view and a cross-sectional view of the heating unit according to Example 1. It is a partial front view and a cross-sectional view of the heating unit according to Example 1. It is a bottom view of the fixing flange according to Example 1. It is a bottom view of the fixing flange according to a modification of Example 1. It is a partial front view and a cross-sectional view of the heating unit according to Example 2. It is a partial front view and a cross-sectional view of the heating unit according to Example 2. It is a partial front view of the fixing flange according to Example 2 (the fixing flange is not shown). It is a bottom view of the fixing flange according to Example 2. It is a partial front view and a cross-sectional view of the heating unit according to Example 3. It is a partial front view and a cross-sectional view of the heating unit according to Example 3. It is a partial front view and a cross-sectional view of the heating unit according to Example 3. It is a partial front view and a cross-sectional view of the heating unit according to Example 3. It is a partial front view and a cross-sectional view of the heating unit according to a modification of Example 3. It is a partial front view and a cross-sectional view of the heating unit according to a modification of Example 3.

[0006] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0007] [Image Forming Apparatus] Figure 1 is a cross-sectional view showing the schematic configuration of a laser beam printer 1, which is an example of an electrophotographic image forming apparatus (image forming apparatus). However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be appropriately changed depending on the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless otherwise specifically stated, the scope of the present invention is not limited thereto. In the following description, the left side in Figure 1 is defined as the front side of the laser beam printer 1, and the right side is defined as the rear side of the laser beam printer 1. The front side of the paper is defined as the right side of the laser beam printer 1, and the back side of the paper is defined as the left side of the laser beam printer 1. Also, the upper and lower sides in Figure 1 are defined as the upper and lower sides of the laser beam printer 1, respectively.

[0008] As shown in Figure 1, the laser beam printer 1 consists of a main unit 2 and a process cartridge 10, the process cartridge 10 being detachably installed in the main unit 2. The main unit 2 is equipped with a paper feed tray 3, a sheet feeding unit 4, a transport path P, an image forming unit 5, a fuser 6, a sheet discharge unit 7, a paper output tray 8, a laser scanner 9, and the like. The cartridge 10, on the other hand, is equipped with a photosensitive drum 11, a developing roller 12 as a developer carrier, and the like.

[0009] The main body of the device 2 is equipped with an opening / closing door 21 to close the opening 2A provided for attaching and detaching the process cartridge 10. The opening / closing door 21 is supported so as to be rotatable around a pivot axis 21a and is configured to move between a closed position that closes the opening 2A and an open position that opens the opening 2A.

[0010] The sheet feeding unit 4 consists of a paper feed roller 41, a separation roller 42, a separation pad 42a, and a transport roller pair 43. Based on the print start signal, the sheet S stored in the paper feed tray 3 is sent to the transport path P by the sheet feeding unit 4 and transported towards the image forming unit 5 via the registration roller pair 44.

[0011] When the sheet S is transported to a predetermined position, an image formation start signal is issued, and the image formation process begins. The photosensitive drum 11, which is rotated 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 by a laser scanner 9 based on image information, and the charge in the exposed area 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, developing the latent image. As a result, the latent image is made visible on the photosensitive drum 11 as a toner image.

[0012] The image forming unit 5 consists of a process cartridge 10 and a transfer roller 51 positioned opposite the photosensitive drum 11 of the process cartridge 10. When the sheet S, transported by the registration roller pair 44, reaches the image forming unit 5 and passes through the nip between the photosensitive drum 11 and the transfer roller 51, a voltage is applied to the transfer roller 51 from the main body 2 of the device, and the toner image on the photosensitive drum 11 is transferred to the sheet S as an unfixed image. Subsequently, the sheet S with the transferred toner image is transported to a fuser 6 equipped with a heating unit 61 and a pressurizing rotating body 62. As the sheet S passes through the nip between the heating unit 61 and the pressurizing rotating body 62, the unfixed image transferred on the sheet S is heated and pressurized and fixed to the surface of the sheet S. The sheet S with the fixed toner image is discharged to the paper output tray 8 via the sheet discharge unit 7.

[0013] [Fuser] Next, the specific configuration of the fuser (fusing device) will be explained using Figure 2. As shown in Figure 2, the heating unit 61 of the fuser 6 includes a heater 611, a holder 612, a stay 70, and a belt 614.

[0014] The heater 611 (heating member) is a flat plate-shaped member having a first surface 611a extending in a first direction D1 and a second direction D2, and a second surface 611b on the opposite side of the first surface 611a in a third direction D3 that is perpendicular to both the first direction D1 and the second direction D2. The first surface 611a of the heater 611 is supported by the support surface 612b1 of the holder 612.

[0015] The holder 612 (support member) is made of a heat-resistant resin such as polyphenylene sulfide (PPS), polyethylene terephthalate (PET), or liquid crystal polymer, and has a guide surface 612a and a support portion 612b. The guide surface 612a contacts the inner circumferential surface 614a of the belt 614 and guides the belt 614 when the belt 614 is rotating. The support portion 612b has a support surface 612b1 that supports the heater 611 and a surface 612b2 that is opposite to the support surface 612b1 in the third direction D3. The support surface 612b1 supports the first surface 611a of the heater 611.

[0016] The stay 70 (reinforcing member) is formed by reinforcing the holder 612 and bending a metal plate (in this embodiment, a steel plate with a thickness of 1.6 mm) which has greater rigidity than the holder 612, so that the cross section perpendicular to the first direction D1 is U-shaped (like a U). The stay 70 reinforces the holder 612 by supporting the supported surface 612b2 of the holder 612.

[0017] The belt 614 (film) 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. A heater 611, a holder 612, and a stay 70 are arranged inside the belt 614, and the belt 614 is configured to rotate around these components. The inner circumferential surface 614a of the belt 614 may be in direct contact with the second surface 611b of the heater 611, or a heat-conductive plate material may be sandwiched between the inner circumferential surface 614a and the heater.

[0018] The pressurized rotating body 62 (roller) has a metal shaft 621 and an elastic part 622 covering the shaft 621, and rotates around the rotation axis R1. The pressurized rotating body 62 forms a nip portion NP together with the heater 611 via a belt 614. The pressurized rotating body 62 is configured to rotate when a driving force is transmitted from the drive source (motor) of the laser beam printer 1. As the pressurized rotating body 62 rotates, the belt 614 rotates passively due to the frictional force between the belt 614 and the sheet S sandwiched between the nip portion NP. As a result, the sheet S on which the toner image has been transferred is transported between the pressurized rotating body 62 and the heated belt 614, and the toner image is heat-fixed.

[0019] As shown in Figure 3, the fuser unit 6 has a main frame 64 that supports the heating unit 61 and the pressurizing rotating body 62, and a cover frame 66 that is located above the main frame 64 and covers the heating unit 61.

[0020] The cover frame 66 has an upper sheet guide 661 that guides the upper surface of the sheet S being transported along the transport path P, downstream of the heating unit 61 and the pressurizing rotating body 62 in the sheet transport direction. The main frame 64 has a lower sheet guide 645 that guides the lower surface of the sheet S being transported along the transport path P, downstream of the heating unit 61 and the pressurizing rotating body 62 in the sheet transport direction.

[0021] The transport path P in the fuser 6 extends in a direction roughly aligned with the front-to-back direction, and inclined upward as it moves from front to back. In other words, the sheet transport direction in the fuser 6 is roughly aligned with the front-to-back direction.

[0022] In this configuration, the main frame 64 and the cover frame 66 are formed from insulating resin.

[0023] As shown in Figure 4, the main frame 64 supports the heating unit 61 and the pressurizing rotating body 62. The main frame 64 has a pair of rail sections 643L and 643R at its ends in the first direction D1. The rail sections 643L and 643R support the holder 612 so that it can move in the third direction D3 via pressurizing members 615L and 615R that pressurize the stay 70. The pair of rail sections 643L each extend in the third direction D3 and face each other with a gap between them with respect to the second direction D2.

[0024] The pressurized rotating body 62 is rotatably held by the main frame 64 via bearings 642L and 642R at both ends of a metal shaft 621 in a first direction D1. At this time, the position of bearing 642L relative to the main frame 64 is determined by the engagement (fitting) of a protrusion 642L1 on bearing 642L1 with a recess 644L on the main frame 64. Similarly, the position of bearing 642R relative to the main frame 64 is determined by the engagement (fitting) of a protrusion 642R1 on bearing 642R1 with a recess 644R on the main frame 64.

[0025] In this embodiment, the pressurizing rotating body 62 comprises a shaft 621 and an elastic portion 622, but it is not limited to this configuration, and can also be configured with a pressurizing belt that is pressed against a heating roller by an elastic member.

[0026] Furthermore, in this configuration, the bearings 642L and 642R are provided with protrusions, and the main frame 64 is provided with recesses 644L and 644R, but the relationship between protrusions and recesses is not limited to this. Also, the means for fixing the bearings 642L and 642R to the main frame 64 is not limited to a protrusion-recess shape.

[0027] Details of the stay 70 will be described. Figure 5A is a perspective view of the stay 70. Figure 5B is an enlarged view of one end 61L of the stay 70, where the stay 70 is a member with a longitudinal direction in the first direction D1 as shown in Figure 5A and has one end 70L and the other end 70R. Figure 5C is a view of the stay 70 in the direction V (Figure 5A), which is parallel to the first direction D1. Figure 5D is a cross-section of the stay 70 on a virtual plane VR perpendicular to the first direction D1.

[0028] As shown in Figures 2 and 5D, the stay 70 has a first leg portion 70a and a second leg portion 70b. The first leg portion 70a and the second leg portion 70b extend toward the supported surface 612b2 of the holder 612 in the third direction D3, supporting the supported surface 612b2, and are spaced apart in the second direction D2. Furthermore, as shown in Figure 5D, the stay 70 has a connecting portion 70c that connects the end of the first leg portion 70a, which is on the side furthest from the supported surface 612b2 in the third direction D3, and the end of the second leg portion 70b, which is on the side furthest from the supported surface 612b2 in the third direction. The stay 70 is also configured so that the side opposite the connecting portion 70c in the third direction D3 is an open portion 70d.

[0029] As shown in Figures 5A to 5D, the stay 70 has a first protrusion 67a that projects from the first end face 70a1 of the first leg portion 70a in the first direction D1, away from the center CL (longitudinal center) of the stay 70. The stay 70 further has a second protrusion 67b that projects from the second end face 70b1 of the second leg portion 70b, which is on the same side as the first end face 70a1 in the first direction D1, away from the center CL (longitudinal center) of the stay 70. The first protrusion 67a has a first contact surface 67a1, which is the end face in the direction toward the belt 614 from the pressurizing rotating body 62 with respect to the third direction D3. The second protrusion has a second contact surface 67b1, which is the end face in the direction toward the belt 614 from the pressurizing rotating body 62 with respect to the third direction D3, and is on the same side as the first contact surface 67a1.

[0030] As shown in Figure 5D, the portion of the stay 70 composed of a first leg portion 70a, a second leg portion 70b, and a connecting portion 70c is a portion of a metal plate that has been bent so that its cross-section perpendicular to the first direction D1 is U-shaped. As shown in Figure 5B, in the first direction D1, a first recess 67a2 (third recess) is provided between the first contact surface 67a1 of the first protrusion 67a and the first end surface 70a1 of the first leg portion 70a, recessed in the direction toward the pressurizing rotating body 62 from the belt 614. In the first direction D1, a second recess 67b2 (fourth recess) is provided between the second contact surface 67b1 of the second protrusion 67b and the second end surface 70b1 of the second leg portion 70b, recessed in the direction toward the pressurizing rotating body 62 from the belt 614.

[0031] Since the stay 70 is formed by bending a steel plate, as shown in Figure 5C, the width W1 in the second direction D2 of the first protrusion 67a and the second protrusion 67b is equal to the thickness of the steel plate.

[0032] [Position of Belt 614 and Condition of Force Generation] The mechanism of force generation of Belt 614 will be explained.

[0033] Figure 6 shows the comparative example belt 614 (dashed line) and nip portion NP viewed from a direction perpendicular to both the rotation axis direction and the recording material transport direction. The case where the generatrix direction of the belt 614 is inclined with respect to the rotation axis direction of the pressurized rotating body will be explained. The belt 614 is loosely suspended from the holder 612, and the belt 614 rotates in the direction of arrow a due to the rotation of the pressurized rotating body 62. In the state shown in Figure 6, when a driving force F is applied to the belt 614 at the nip portion NP, a rotational force R and a pulling force Y in the direction of the rotation axis act on the belt 614.

[0034] When the inclination of the belt 614 in the direction of the generatrix with respect to the direction of the rotation axis of the pressurized rotating body 62 is α°, the pulling force Y of the belt 614 can be expressed as Fsinα. As the belt 614 rotates, when the pulling force Y acts on the belt 614, an arbitrary point A at the longitudinal end of the belt 614 moves in the direction of the rotation axis, tracing a trajectory as shown in "Trajectory of A" on the right side of the figure. This force that moves the belt 614 in the direction of the rotation axis is the pulling force of the belt 614.

[0035] Thus, the shifting force is caused by the inclination of the belt 614. However, in order to achieve smooth rotation, the belt 614 needs to be guided somewhat loosely by the holder 612, and the inclination of the belt 614 occurs due to the precision of the components and the alignment during assembly. Therefore, it is difficult to completely eliminate this inclination of the belt 614.

[0036] [Fixing flanges] Fixing flanges 616L and 616R (regulating members) are provided at both ends of the belt 614 in the first direction D1. The fixing flanges 616L and 616R are made of a highly heat-resistant resin such as polyphenylene sulfide (PPS), polyethylene terephthalate (PET), or liquid crystal polymer.

[0037] The fixing flange 616L has a shape that is symmetrical with respect to the fixing flange 616R with respect to a virtual plane that passes through the center of the pressurizing rotating body 62 in its first direction and is perpendicular to the direction of its rotation axis R1. Therefore, only the fixing flange 616L will be described.

[0038] Figures 7A and 7B show the shape of the fixing flange 616L. Figure 7A is a view of the surface into which the belt 614 is fitted, viewed from the direction of the rotation axis, and Figure 7B is a side view of it viewed from the upstream side in the conveying direction of the sheet S.

[0039] The anchoring flange 616L has a guide surface 616L1 (first surface) that guides the inner circumferential surface 614a of the belt 614 when the belt 614 rotates. The anchoring flange 616L is also provided with a restricting surface 616L2 (second surface) that restricts the movement of the belt 614 in the first direction D1 by contacting the end face of the belt 614 in the first direction D1 when the belt 614 moves in the first direction D1. The guide surface 616L1 further extends in a direction toward the center of the belt 614 in the first direction D1 with respect to the first direction D1. In addition, the guide surface 616L1 extends in a direction intersecting the restricting surface 616L2. This is to restrict the movement in the first direction D1 even when the belt 614 moves in a direction intersecting the first direction D1.

[0040] Further, as shown in FIGS. 8A and 8B, the fixing flange 616L includes a fulcrum portion 80. The fulcrum portion 80 abuts against a side surface of the pressure member 615L, and the fixing flange 616L is configured to be swingable in the S1 direction and the S2 direction when viewed in the second direction D2 with the fulcrum portion 80 serving as a fulcrum.

[0041] As described above, when the belt 614 is inclined, the belt 614 moves in the first direction D1 by a biasing force. That is, when the belt 614 moves in the first direction D1 and the end face of the belt 614 in the first direction D1 comes into contact with the restriction surface 616L2 to be restricted, the belt 614 may be inclined. In such a case, when the end face of the belt 614 in the first direction D1 comes into contact with the restriction surface 616L2 of the fixing flange 616L, the fixing flange 616L swings so that the restriction surface 616L2 approaches an attitude perpendicular to the first direction D1 of the belt 614. That is, by suppressing local contact between the end face of the belt 614 in the first direction D1 and the restriction surface 616L2, wear and buckling of the end portion of the belt 614 can be suppressed.

[0042] [Pressurizing Mechanism] FIG. 8A is an enlarged view of a holder 612, the flange 616L, the pressure member 615L, and a stay 70 as viewed in the second direction D2. FIG. 8B is an enlarged perspective view of the pressure member 615L. FIG. 9A is an overall view of the fixing device 6 as viewed in the second direction D2. FIG. 9B is a cross-sectional view taken along line A-A of FIG. 9A. FIG. 9C is a cross-sectional view taken along line B-B of FIG. 9A.

[0043] The fixing device 6 includes a pressurizing mechanism 65 that applies pressure to form a nip portion NP between a heating unit 61 and a pressure rotating body 62. The pressurizing mechanisms 65 are respectively provided at both end portions of a main frame 64 in the first direction D1. Since the pressurizing mechanism 65 has substantially the same configuration on one side and the other side in the first direction D1, the structure on one side will be described below.

[0044] As shown in FIGS. 9A to 9C, the pressurizing mechanism 65 includes the pressure member 615L, a pressurizing arm 652L, and a pressurizing spring 653L.

[0045] As shown in Figure 8B, the pressurizing member 615L has a first groove 615L1a and a second groove 615L1b extending in a third direction D3. The first groove 615L1a and the second groove 615L1b are each movably engaged with a pair of rail portions 643L in Figure 4, thereby restricting the movement of the pressurizing member 615L in the first direction D1 relative to the main frame 64. The pressurizing member 615 further has a first recess 615L2a and a second recess 615L2b recessed in the third direction D3, in the direction from the pressurizing rotating body 62 toward the belt 614. The first recess 615L2a and the second recess 615L2b are each engaged with a first protrusion 67a and a second protrusion 67b of the stay 70 in Figure 5B, thereby restricting the movement of the pressurizing member 615L in the second direction D2 relative to the stay 70. The bottom surfaces of both the first recess 615L2a and the second recess 615L2b are pressing surfaces facing the third direction D3, which is the direction from the belt 614 toward the pressurizing rotating body 62, and press the stay 70 in the direction from the belt 614 toward the pressurizing rotating body 62. The pressurizing member 615 has a pressed surface 615L3 facing the third direction D3, which is the direction from the pressurizing rotating body 62 toward the belt 614.

[0046] As shown in Figure 9C, the pressure arm 652L applies pressure to the stay 70 to form a nip portion NP by having its pressure surface 652L1 contact the pressed surface 615L3 of the pressure member 615L. The pressure spring 653L is a tension coil spring, with one end and the other end in the extension and contraction direction engaging with the spring engagement portion 655L of the main frame 64 and the spring engagement portion 652L2 of the pressure arm 652L, respectively. The pressure spring 653L presses the pressure arm 652L toward the pressure member 615L. As shown in Figure 9C, the main frame 64 has a support portion 654L that supports the pressure arm 652L so that it can rotate around the rotation axis X1. The support portion 654L is a substantially cylindrical projection. In this embodiment, the pressure spring 653L is a tension coil spring, but it may also be composed of a compression coil spring.

[0047] The position of the rotation axis X1 about which the pressure arm 652L rotates is located upstream of the nip portion NP in the sheet conveyance direction when viewed in the first direction D1, and is located within the range T of the third direction D3 shown in FIG. 9B. Here, the range T of the third direction D3 shown in FIGS. 9B and 9C is from the rotation center of the pressure rotating body 62 to the pressure surface 652L1 of the pressure arm 652L in the third direction D3. The upstream side in the sheet conveyance direction is the side closer to the photosensitive drum 11 than the nip portion NP in the second direction D2.

[0048] Example 1 of the present invention will be described with reference to FIGS. 10A, 10B and 11. FIG. 10A is an enlarged view of a holder 612, a flange 616L, and a stay 70 viewed in the second direction D2. Illustration of the pressure member 615L is omitted. FIG. 10B is a cross-sectional view taken along line A-A in FIG. 10A. FIG. 11 is a view of fixing flanges 616L and 616R viewed from the direction along the third direction D3, going from the pressure rotating body 62 toward the heating unit 61.

[0049] As shown in FIGS. 10B and 11, the fixing flange 616L includes a first contact portion 68a having a first contact surface 68a1 and a second contact portion 68b having a second contact surface 68b1 on the inner surface which is the surface facing the stay 70. As shown in FIG. 10B, the first contact surface 68a1 and the second contact surface 68b1 are in contact with the first contacted surface 67a1 of the first convex portion 67a and the second contacted surface 67b1 of the second convex portion 67b of the stay 70, respectively. The width W2 of the first contact surface 68a1 in the second direction D2 is wider than the width W1 of the first contacted surface 67a1 in the second direction D2. Similarly, the width W2 of the second contact surface 68b1 in the second direction D2 is wider than the width W1 of the second contacted surface 67b1 in the second direction D2. In the present embodiment, W1 and W2 are 1.6 mm and 2.0 mm, respectively.

[0050] In the present embodiment, the fixing flange 616L is provided with play in the second direction D2 relative to the stay 70 so as to be easily swingable. Note that even when the fixing flange 616L is not swung, a certain amount of play exists.

[0051] Since the fixing flange 616L is located near the heater 611, it may be thermally deformed by the heat from the heater 611. In addition, the first contact portion 68a and the second contact portion 68b of the fixing flange 616 may wear down by sliding against the first protrusion 67a and the second protrusion 67b of the stay 70 when it swings. When the fixing flange 616L is thermally deformed or worn in this way, the play of the fixing flange 616 in the second direction D2 increases. Then, the first contact surface 68a1 and the second contact surface 68b1 may shift in the second direction D2 from the first contact surface 67a1 and the second contact surface 67b1, respectively, and the contact area may decrease. In this case, the posture of the fixing flange 616L becomes unstable, and it may become difficult to stably restrict the belt 614.

[0052] Therefore, in this embodiment, the width W2 in the second direction D2 of the first contact surface 68a1 and the second contact surface 68b1 of the fixing flange 616L is made wider than the width W1 in the second direction D2 of the first contact surface 67a1 and the second contact surface 67b1 of the stay 70. As a result, even when the play described above becomes large, the contact area does not change even if the first contact surface 68a1 and the second contact surface 68b1 rub against the first contact surface 67a1 and the second contact surface 67b1 respectively in the second direction D2. Thus, the movement of the belt 614 can be stably restricted. The bottom surface of the first recess 615L2a and the bottom surface of the second recess 615L2b of the pressurizing member 615 shown in Figure 8B also contact the first contact surface 67a1 of the first protrusion 67a and the second contact surface 67b1 of the second protrusion 67b of the stay 70, respectively. As a result, the pressurizing member 615 presses the heater 611 toward the pressurizing rotating body 62 via the stay 70 and the holder 162. The pressurizing member 615 is positioned in the first direction D1 further from the longitudinal center CL of the stay 70 than the fixing flange 616L.

[0053] In this embodiment, a configuration is shown in which the first contact surface 68a1 and the second contact surface 68b1 of the fixing flange 616L are separated in the second direction D2, but the embodiment is not limited to this. A modified example is shown in Figure 12. Figure 12 is a view of the modified fixing flange 617L from the third direction D3, which is the direction from the pressurizing rotating body 62 toward the heating unit 61. As shown in Figure 12, a configuration is also possible in which the first contact surface 68a1 and the second contact surface 68b1 are continuous in the second direction D2. The width W3 of the contact surface 68ab1 in the second direction D2 is wider than the width W1 of the first contact surface 67a1, and is wider than the sum of the width W1 of the first contact surface 67a1 of the stay 70 and the width W1 of the second contact surface 67b1 in the second direction D2. As a result, even when the aforementioned play increases, the contact area of ​​the fixing flange 617L does not change even if the contact surface 68ab1 of the fixing flange 617L rubs against the first contact surface 67a1 and the second contact surface 67b1 in the second direction D2. Therefore, the movement of the belt 614 can be stably restricted.

[0054] Embodiment 2 of the present invention will be described with reference to Figures 13A to 15.

[0055] Since the fixing flanges 716L and 716R have a symmetrical shape, similar to that of Embodiment 1, only the fixing flange 716L will be described. Figure 13A is an enlarged view of the holder 712, fixing flange 716L, and stay 70 as seen in the second direction D2. The pressurizing member 615L is not shown. Figure 13B is a cross-section of Figure 13A along line A-A. Figure 14 is a view of Figure 13A with the fixing flange 716L hidden. Figure 15 is a view of the fixing flange 716L as seen in the third direction D3, from the pressurizing rotating body 62 toward the heating unit 61.

[0056] As shown in Figure 13B, the holder 712 has a guide surface 712a that guides the inner circumferential surface 614a (inner surface) of the belt 614, and a support portion 712b which is provided with a support surface 712b1 that supports the heater 611 and a supported surface 712b2 that is supported by the stay 70. The guide surface 712a and the support portion 712b have the same structure as the guide surface 612a and support portion 612b of the holder 612 of Embodiment 1.

[0057] The structure of the holder 712, which differs from the holder 612 of Example 1, includes a first support portion 712c having a first contact surface 712c1 and a second support portion 712d having a second contact surface 712d1. The first support portion 712c and the second support portion 712d each protrude in the direction from the support surface 712b1 toward the supported surface 712b2 with respect to the third direction D3 (the direction from the pressurizing rotating body 62 toward the belt 614). The first contact surface 712c1 and the second contact surface 712d1 are the end faces of the first support portion 712c and the second support portion 712d, respectively, in the direction from the support surface 712b1 toward the supported surface 712b2.

[0058] As shown in Figures 13B and 15, the fixing flange 716L is provided with a first contact portion 78a having a first contact surface 78a1 on its inner surface facing the holder 712, and a second contact portion 78b having a second contact surface 78b1. The first contact surface 78a1 and the second contact surface 78b1 of the fixing flange 716L abut against the first contact surface 712c1 of the first support portion 712c and the second contact surface 712d1 of the second support portion 712d of the holder 712, respectively, as shown in Figure 13B. The width W2 of the first contact surface 78a1 in the second direction D2 is wider than the width W1 of the first contact surface 712c1 in the second direction D2. Similarly, the width W2 of the second contact surface 78b1 in the second direction D2 is wider than the width W1 of the second contact surface 712d1 in the second direction D2. This allows the movement of the belt 614 to be stably restricted by the fixing flange 716, similar to Example 1.

[0059] In this embodiment, the first contact surface 712c1 and the second contact surface 712d1 are further provided on the holder 712. This allows them to be positioned closer to the center CL of the stay in the first direction D1 (Figures 5A to 5D) than the first contact surface 67a1 and the second contact surface 67b1 of the stay 70 in Embodiment 1. The first contact surface 712c1 of the holder 712 can also be provided in a region of the stay 70 in the first direction D1 that is closer to the center CL of the stay 70 in the first direction D1 than the first recess 67a2 (third recess) of the stay 70. Furthermore, the second contact surface 712d1 of the holder 712 can also be provided in a region of the stay 70 in the first direction D1 that is closer to the center CL of the stay 70 in the first direction D1 than the second recess 67b2 (fourth recess) of the stay 70. The first contact surface 712c1 and the second contact surface 712d1 of the holder 712 can each be provided in a region of the stay 70 closer to the center CL in the first direction D1 than the end face 70c1 of the stay 70 in the first direction D1. As shown in Figure 14, the first contact surface 712c1 and the second contact surface 712d1 of the holder 712 can each be provided in a region of the stay 70 closer to the center CL in the first direction D1 than the first recess 67a2 and the second recess 67b2 of the stay 70. This makes it easier to maintain the orientation of the fixing flange even when the guide surface 712a of the fixing flange 716L receives force from the inner circumferential surface 614a of the belt 614.

[0060] Furthermore, the first contact surface 712c1 and the second contact surface 712d1 of the holder 712 may also be provided in a region of the stay 70 that is further from the center CL in the first direction D1 than the first recess 67a2 and the second recess 67b2 of the stay 70 in the first direction D1. Alternatively, the first contact surface 712c1 and the second contact surface 712d1 of the holder 712 may only be provided in a region of the stay 70 that is further from the center CL in the first direction D1 than the first recess 67a2 and the second recess 67b2 of the stay 70 in the first direction D1.

[0061] Embodiment 3 of the present invention will be described below. The configuration of this embodiment will be shown and explained with reference to Figures 16A and 16B. Figure 16A is a view of the anchoring flange 816 and the stay 70 from the side of the connecting portion 70c of the stay 70 in the third direction D3. Figure 16B is a cross-sectional view taken along line A-A in Figure 16A.

[0062] The anchoring flange 816 has a guide surface 816L1 that guides the inner circumferential surface 614a of the belt 614, similar to the guide surface 616L1 of the anchoring flange 616L in Embodiment 1. The guide surface 816L1 extends in the first direction D1 to a position where it overlaps with the connecting portion 70c of the stay 70 when viewed in the third direction. As a result, the anchoring flange 816 can increase the contact area between the guide surface 816L1 and the inner circumferential surface 614a of the belt 614, thereby enabling more stable guidance of the belt 614.

[0063] Furthermore, in this embodiment, it is preferable that the fixing flange 816 is configured to contact the first contact surface 712c1 and the second contact surface 712d1 of the holder 712, similar to embodiment 2. It is more preferable that the first contact surface 712c1 and the second contact surface 712d1 of the holder 712 are located in a region closer to the center CL in the first direction D1 of the stay 70 than the first recess 67a2 and the second recess 67b2 of the stay 70. Since the guide surface 816L1 extends in a direction toward the center CL of the stay 70 in the first direction D1, the position of the fixing flange 816 is more stable when the contact position between the fixing flange 816 and the holder 712 is closer to the center CL.

[0064] Next, modified examples of Embodiment 3 are shown in Figures 18A and 18B. Figure 18A is a view of the anchoring flange 1016 and the stay 70 from the side of the connecting portion 70c of the stay 70 in the third direction D3. Figure 18B is a cross-sectional view taken along line A-A in Figure 18A.

[0065] As shown in Figure 18B, the guide surface 1016L1 of the anchoring flange 1016L is provided with a protrusion 1016L5 that fits inside the end of the connecting portion 70c of the stay 70 in the first direction D1. This prevents the side of the anchoring flange 1016L closer to the center CL of the stay 70 from tilting away from the connecting portion 70c of the stay 70. Therefore, the anchoring flange 1016L can stably restrict the movement of the belt 614.

[0066] Furthermore, if it is desired to avoid the force being received from the inner circumferential surface 614a of the belt 614 closer to the center CL of the stay 70, as in the case of the guide surface 816L1 of the fixing flange 816 in Example 3, the following configuration can also be used. As shown in Figures 17A and 17B, the fixing flange 916L1 is configured so that the guide surface 916L1 does not overlap with the connecting portion 70c of the stay 70.

[0067] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are attached to make the scope of the invention public.

[0068] This application claims priority based on Japanese Patent Application No. 2025-054681, filed on 28 March 2025, and all of its contents are incorporated herein by reference.

Claims

1. A fixing device for fixing an image to a sheet, comprising: an endless belt; a plate-shaped heater having a first surface extending in a first direction and a second direction intersecting the first direction, and a second surface on the opposite side of the first surface in a third direction intersecting both the first and second directions, wherein the second surface is on the side facing the inner surface of the belt; a support member having a support surface that supports the first surface of the heater; a roller that forms a nip portion together with the heater via the belt and rotates about a rotation axis extending in the first direction; a metal reinforcing member that reinforces the support member from the side of the supported surface on the opposite side of the support surface in the third direction, wherein the first direction is the longitudinal direction; and a regulating member provided with a regulating surface configured to contact the end face of the belt in the first direction and restrict the movement of the belt in the first direction, wherein the reinforcing member has a cross section perpendicular to the first direction, The reinforcing member has: first leg portion and second leg portion that extend toward the supported surface of the support member in the third direction and support the supported surface and are spaced apart in the second direction; a connecting portion that connects the end of the first leg portion on the side furthest from the supported surface in the third direction and the end of the second leg portion on the side furthest from the supported surface in the third direction, and is configured such that the side of the reinforcing member opposite the connecting portion is an open portion in the third direction; the reinforcing member has first convex portion and second convex portion that project in the first direction toward the longitudinal center of the reinforcing member, respectively, from the first end face of the first leg portion and the second end face of the second leg portion on the same side as the first end face in the first direction; the first convex portion has a first contact surface which is the end face in the direction toward the belt from the roller in the third direction; and the second convex portion has a second contact surface which is the end face in the direction toward the belt from the roller in the third direction and on the same side as the first contact surface. The restricting member has a first contact surface and a second contact surface that contact the first contact surface and the second contact surface, respectively, and the width of the first contact surface of the restricting member in the second direction is wider than the width of the first contact surface of the reinforcing member in the second direction.An anchoring device characterized in that the width in the second direction of the second contact surface of the regulating member is wider than the width in the second direction of the second contact surface of the reinforcing member.

2. The fixing device according to claim 1, characterized in that the portion of the reinforcing member, which is composed of the first leg portion, the second leg portion, and the connecting portion, is a portion of a metal plate bent so that the cross section perpendicular to the first direction is U-shaped, and in the first direction, a first recess is provided between the first contact surface of the first convex portion and the first end face of the first leg portion, which is recessed in the direction toward the roller from the belt, and in the first direction, a second recess is provided between the second contact surface of the second convex portion and the second end face of the second leg portion, which is recessed in the direction toward the roller from the belt.

3. The fixing device according to claim 1, wherein the restricting member has a restricting surface that contacts the end face of the belt in the first direction when the belt moves in the first direction and restricts movement in the first direction, and a guide surface that faces the inner surface of the belt and guides the rotation of the belt, and extends in a direction toward the center of the belt in the first direction with respect to the first direction, and the guide surface of the restricting member overlaps the connecting portion of the reinforcing member when viewed in the third direction.

4. A fixing device for fixing an image to a sheet, comprising: an endless belt; a plate-shaped heater having a first surface extending in a first direction and a second direction intersecting the first direction, and a second surface on the opposite side of the first surface in a third direction intersecting both the first and second directions, wherein the second surface is on the side facing the inner surface of the belt; a support member having a support surface that supports the first surface of the heater; a roller that forms a nip portion together with the heater via the belt and rotates about a rotation axis extending in the first direction; a metal reinforcing member that reinforces the support member from the side of the supported surface on the opposite side of the support surface in the third direction, wherein the first direction is the longitudinal direction; and a regulating member provided with a regulating surface configured to contact the end face of the belt in the first direction and restrict the movement of the belt in the first direction, The fixing device is characterized in that the support member has, in a cross section perpendicular to the first direction, a first support portion and a second support portion that extend in a direction away from the heater with respect to the third direction with respect to the supported surface and are spaced apart in the second direction, the first support portion has a first contact surface which is the end face in the third direction, the second support portion has a second contact surface which is the end face in the third direction and is on the same side as the first contact surface, the regulating member has a first contact surface and a second contact surface which contact the first contact surface and the second contact surface, respectively, the width of the first contact surface of the regulating member in the second direction is wider than the width of the first contact surface in the second direction, and the width of the second contact surface of the regulating member in the second direction is wider than the width of the second contact surface in the second direction.

5. The reinforcing member has, in a cross section perpendicular to the first direction, a first leg portion and a second leg portion that extend toward the supported surface of the support member in the third direction and support the supported surface, and are spaced apart in the second direction, and a connecting portion that connects the end of the first leg portion on the side furthest from the supported surface in the third direction and the end of the second leg portion on the side furthest from the supported surface in the third direction, and is configured such that the side of the reinforcing member opposite the connecting portion is an open portion in the third direction, and the reinforcing member has a first convex portion and a second convex portion that project in the first direction toward the longitudinal center of the reinforcing member, respectively from the first end face of the first leg portion and the second end face of the second leg portion on the same side as the first end face in the first direction, and the first convex portion has a first contact surface which is the end face in the direction toward the belt from the roller in the third direction, The fixing device according to claim 4, wherein the second protrusion has a second contact surface which is an end face in the direction toward the belt from the roller with respect to the third direction and is on the same side as the first contact surface, and a first recess and a second recess are provided, and a pressing member is provided at a position further away from the longitudinal center of the reinforcing member than the regulating member in the first direction, and further comprises a pressing member for pressing the heater toward the roller via the reinforcing member and the support member, and the bottom surface of the first recess and the bottom surface of the second recess of the pressing member abut the first contact surface of the first protrusion and the second contact surface of the second protrusion, respectively.

6. The fixing device according to claim 5, wherein the portion of the reinforcing member composed of the first leg portion, the second leg portion, and the connecting portion is a portion of a metal plate bent so that the cross section perpendicular to the first direction is U-shaped, a third recess is provided in the first direction between the first contact surface of the first convex portion and the first end face of the first leg portion, a fourth recess is provided in the first direction between the second contact surface of the second convex portion and the second end face of the second leg portion, a first recess is provided in the first direction between the second contact surface of the second convex portion and the second end face of the second leg portion, the first contact surface of the first support portion is provided in the first direction closer to the longitudinal center of the reinforcing member than the third recess, and the second contact surface of the second support portion is provided in the first direction closer to the longitudinal center of the reinforcing member than the fourth recess.

7. A fixing device for fixing an image to a sheet, comprising: an endless belt; a plate-shaped heater having a first surface extending in a first direction and a second direction intersecting the first direction, and a second surface on the opposite side of the first surface in a third direction intersecting both the first and second directions, wherein the second surface is on the side facing the inner surface of the belt; a support member having a support surface that supports the first surface of the heater; a roller that forms a nip portion together with the heater via the belt and rotates about a rotation axis extending in the first direction; a metal reinforcing member that reinforces the support member from the side of the supported surface on the opposite side of the support surface in the third direction, wherein the first direction is the longitudinal direction; and a regulating member provided with a regulating surface configured to contact the end face of the belt in the first direction and restrict the movement of the belt in the first direction, The fixing device is characterized in that the restricting member has a restricting surface that contacts the end face of the belt in the first direction when the belt moves in the first direction and restricts movement in the first direction, and a guide surface that faces the inner surface of the belt and guides the rotation of the belt, and extends in a direction toward the center of the belt in the first direction with respect to the first direction, and the guide surface of the restricting member overlaps with the reinforcing member when viewed in the third direction.

8. The fixing device according to claim 7, characterized in that the end of the restricting member in the first direction, which is in the direction approaching the longitudinal center of the reinforcing member, includes a protrusion that extends inward from the end of the reinforcing member in the first direction, which is in the direction approaching the restricting member from the longitudinal center.

9. The fixing device according to claim 8, characterized in that the protrusion at the end of the regulating member overlaps with the guide surface when viewed in the third direction.

Images