Fixing device

Abstract

To provide a fixing device with which it is possible to move a lubricant disposed between an endless belt and a slide sheet in a specific direction.SOLUTION: The fixing device comprises a rotor, an endless belt that is in contact with the outer circumferential surface of the rotor, a heater, a pressuring member, a slide sheet 150, and a lubricant. A surface 151 of the slide sheet 150 that faces the inner circumferential surface of the endless belt includes a rib-shaped protrusion 152 that protrudes toward the endless belt and a recess 153 that is recessed with respect to the protrusion 152. The protrusion 152 has a first rib 152A which extends in a first extension direction that is diagonal to the movement direction of the endless belt and a second rib 152B which extends in a second extension direction that intersects the first extension direction and which connects to the first rib 152A. A side surface 152C of the first rib 152A that faces the second extension direction is exposed in a section where the second rib 152B connects to the first rib 152A.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a fixing device equipped with an endless belt. [Background technology]

[0002] Conventionally, some fixing devices using a pressure pad have a sliding sheet between the endless belt and the pressure pad (see Patent Document 1). Lubricating oil is held between the sliding sheet and the endless belt. The sliding sheet has recesses for holding the lubricant. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-015227 Summary of the Invention [Problem to be solved by the invention]

[0004] When the endless belt moves, the lubricant also moves in the width direction of the sliding sheet. However, the configuration of Patent Document 1 does not allow the lubricant to move in a specific direction.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to move lubricating oil disposed between an endless belt and a sliding sheet in a specific direction. [Means for solving the problem]

[0006] In order to solve the above problem, the fixing device of the present invention comprises a rotating body, an endless belt in contact with the outer peripheral surface of the rotating body, a heater that heats at least one of the rotating body and the endless belt, a pressure member that sandwiches the endless belt between the rotating body and the pressure member, a sliding sheet that is sandwiched between the inner peripheral surface of the endless belt and the pressure member, and a lubricant that is arranged between the endless belt and the sliding sheet. The surface of the sliding sheet facing the inner circumferential surface of the endless belt has a rib-shaped convex portion that is convex toward the endless belt and a concave portion that is concave relative to the convex portion. The protrusion includes a first rib extending in a first extension direction oblique to the moving direction of the endless belt; The second rib extends in a second extension direction intersecting the first extension direction and is connected to the first rib. The first rib has a side surface facing the second extension direction exposed at a portion where the second rib is connected to the first rib.

[0007] According to this configuration, when the endless belt moves in the movement direction, the lubricant moves in the first extension direction along the side surface of the first rib, so that the lubricant can be moved in a specific direction.

[0008] In the fixing device, the angle between the moving direction of the endless belt and the first extending direction may be equal to the angle between the moving direction of the endless belt and the second extending direction.

[0009] This can suppress deviation of the endless belt due to the frictional force of the first rib against the endless belt and the frictional force of the second rib against the endless belt.

[0010] In the fixing device, the first rib and the second rib may extend linearly.

[0011] This allows the entire first rib to function to move the lubricant in a specific direction.

[0012] In the fixing device, the first rib and the second rib may be configured to intersect at right angles.

[0013] In addition, in the fixing device described above, the top of the first rib may be higher than the top of the second rib, and at the portion where the second rib connects to the first rib, the side surface may protrude further toward the endless belt than the top of the second rib.

[0014] This allows the lubricating oil to move easily along the first rib.

[0015] In addition, in the fixing device described above, the opposing surface of the sliding sheet may be configured to have a groove located between the first rib and the second rib at the portion where the second rib connects to the first rib, extending in the first extension direction and crossing the second rib.

[0016] This allows the lubricant to move along the grooves.

[0017] In addition, in the fixing device described above, the first rib may extend from one side to the other side in the width direction of the endless belt as it moves downstream in the direction of movement of the endless belt, and may further include a temperature sensor that detects the temperature of the end of the rotating body on the other side in the width direction of the endless belt.

[0018] According to this, the temperature of the lubricant can be measured appropriately by moving the lubricant to the side where the temperature is detected.

[0019] In the fixing device, the first rib may extend continuously from one end to the other end in the width direction.

[0020] Furthermore, in the fixing device described above, the first rib may extend from one end to the center of the sliding sheet in the width direction of the endless belt, and the convex portion may further have a third rib extending in the second extension direction from the other end in the width direction to the center of the sliding sheet in the width direction, and a fourth rib extending in the first extension direction and connected to the third rib, and the third rib may be configured so that the side facing the first extension direction is exposed at the portion where the fourth rib connects to the third rib.

[0021] This allows the lubricant to be concentrated in the center, preventing the lubricant from leaking from the ends. [Effects of the Invention]

[0022] According to the present invention, the lubricating oil disposed between the endless belt and the sliding sheet can be moved in a specific direction. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a cross-sectional view showing a laser printer according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing the fixing device. [Figure 3] 3 is an enlarged view showing a part of the endless belt and the sliding sheet in FIG. 2.

[0023] FIG. [Figure 4] 2A is an enlarged perspective view showing the opposing surface of the sliding sheet, and FIG. 2B is a cross-sectional view taken along the line AA. [Figure 5] 3A is a cross-sectional view taken along the line XX in FIG. 2, and FIG. 3B is a plan view of the opposing surface of the sliding sheet. [Figure 6] 10A and 10B are diagrams illustrating a method for attaching a thermostat to a heating unit. [Figure 7] FIG. 7 is a cross-sectional view of FIG. 6 taken along the line Y-Y. [Figure 8] 10A is a perspective view showing a sliding sheet of a second embodiment, and FIG. 10B is a cross-sectional view taken along line BB. [Figure 9] 10A is a perspective view showing a sliding sheet of a third embodiment, and FIG. 10B is a cross-sectional view taken along line CC. [Figure 10] 10A is a perspective view showing a sliding sheet of a fourth embodiment, and FIG. 10B is a cross-sectional view taken along line DD. [Figure 11] 10(a) is a perspective view showing a sliding sheet of a fifth embodiment, and FIG. 10(b) is a perspective view showing a sliding sheet of a sixth embodiment. [Figure 12] FIG. 13 is a plan view showing a sliding sheet of a seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, a first embodiment of the invention will be described in detail with reference to the drawings as appropriate. 1, a fixing device 8 according to the embodiment is used in an image forming apparatus 1 such as a laser printer. The image forming apparatus 1 includes a main body housing 2, a sheet supply unit 3, an exposure device 4, a developer image forming unit 5, and the fixing device 8.

[0025] The sheet supply unit 3 is provided at the bottom of the main body housing 2, and includes a sheet tray 31 that stores sheets S such as paper, and a sheet supply mechanism 32. The sheets S in the sheet tray 31 are supplied to the developer image forming unit 5 by the sheet supply mechanism 32.

[0026] The exposure device 4 is disposed at the top of the main body housing 2, and includes a light source device (not shown), a polygon mirror (shown without reference numerals), a lens, a reflecting mirror, etc. The exposure device 4 exposes the surface of the photosensitive drum 61 by scanning a light beam (see dashed line) based on image data emitted from the light source device over the surface of the photosensitive drum 61 at high speed.

[0027] The developer image forming unit 5 is disposed below the exposure device 4. The developer image forming unit 5 is configured as a process cartridge, and is detachable from the main body housing 2 through an opening formed when a front cover 21 provided at the front of the main body housing 2 is opened. The developer image forming unit 5 includes a photosensitive drum 61, a charger 62, a transfer roller 63, a developing roller 64, a supply roller 65, and a developer storage unit 66 that stores developer made of dry toner.

[0028] The developer image forming unit 5 uniformly charges the surface of the photosensitive drum 61 using a charger 62. Thereafter, the surface of the photosensitive drum 61 is exposed to a light beam from an exposure device 4, thereby forming an electrostatic latent image based on image data on the surface. The developer image forming unit 5 also supplies the developer in a developer container 66 to a developing roller 64 via a supply roller 65.

[0029] Then, the developer image forming unit 5 supplies the developer on the developing roller 64 to the electrostatic latent image formed on the photosensitive drum 61. As a result, the electrostatic latent image is visualized, and a developer image is formed on the photosensitive drum 61. Thereafter, the developer image forming unit 5 transfers the developer image on the photosensitive drum 61 to the sheet S by transporting the sheet S supplied from the sheet supply unit 3 between the photosensitive drum 61 and the transfer roller 63.

[0030] The fixing device 8 is disposed behind the developer image forming unit 5. Details of the fixing device 8 will be described later. The fixing device 8 thermally fixes the developer image to the sheet S by passing the sheet S onto which the developer image has been transferred. The image forming apparatus 1 discharges the sheet S onto which the developer image has been thermally fixed, onto a paper discharge tray 22 outside the main body housing 2, by a conveying roller 23 and a discharge roller 24.

[0031] 2, the fixing device 8 includes a heating unit 81 and a pressure unit 82. The pressure unit 82 is urged toward the heating unit 81 by a pressing mechanism (not shown). In the following description, the direction in which the pressure unit 82 is urged toward the heating unit 81 is referred to as a "predetermined direction." In this embodiment, the predetermined direction is a direction perpendicular to the width direction and movement direction (described later), and is a direction in which the heating unit 81 and the pressure unit 82 face each other.

[0032] The heating unit 81 includes a heater 110 and a rotating body 120. The pressure unit 82 includes an endless belt 130, a pressure pad P as an example of a pressure member, a holder 140, a sliding sheet 150, an upstream belt guide 160, a downstream belt guide 170, a stay 180, and grease GR as an example of a lubricant. In the following description, the width direction of the endless belt 130 will be simply referred to as the "width direction." The width direction is the direction in which the rotation axis X1 of the rotating body 120 extends. The width direction is perpendicular to a predetermined direction.

[0033] The heater 110 heats at least one of the rotating body 120 and the endless belt 130. In this embodiment, the heater 110 is disposed inside the rotating body 120 and heats the rotating body 120.

[0034] The rotating body 120 is a cylindrical roller and has a base tube 121 and an elastic layer 122. The base tube 121 is a metal pipe. The elastic layer 122 is rotatable around a rotation axis X1. The rotating body 120 is driven to rotate by a motor (not shown) provided in the image forming apparatus 1. The elastic layer 122 is provided on the outer periphery of the base tube 121. In other words, the rotating body 120 has the elastic layer 122 on its surface. The elastic layer 122 has elasticity.

[0035] The endless belt 130 is an endless belt made of metal or the like. The endless belt 130 has a width greater than the width of the largest sheet S that is transported by the image forming apparatus 1. The endless belt 130 contacts the outer peripheral surface of the rotating body 120. The endless belt 130 transports the sheet S by sandwiching it between itself and the rotating body 120. When the rotating body 120 rotates, the endless belt 130 rotates clockwise in FIG. 2 due to friction with the rotating body 120 or the sheet S.

[0036] The pressure pad P is a member that sandwiches the endless belt 130, the sliding sheet 150, and the sheet S between the pressure pad P and the rotating body 120 to form a nip portion NP. In the following description, the movement direction of the endless belt 130 in the nip portion NP will be simply referred to as the "movement direction." In this embodiment, the movement direction is a direction along the outer circumferential surface of the rotating body 120, but since this direction is roughly perpendicular to the predetermined direction and the width direction, it will be illustrated as a direction perpendicular to the predetermined direction and the width direction. The movement direction is the same as the conveyance direction of the sheet S in the nip portion NP.

[0037] The pressure pad P has a first pressure pad P1 and a second pressure pad P2. The second pressure pad P2 is located downstream in the movement direction from the first pressure pad P1 and has a durometer hardness higher than that of the first pressure pad P1.

[0038] The holder 140 is a member that holds the pressure pad N.

[0039] The sliding sheet 150 is disposed by being sandwiched between the inner peripheral surface 131 of the endless belt 130 and the pressure pad P. The sliding sheet 150 contacts the inner peripheral surface 131 of the endless belt 130. When the rotating body 120 rotates, the sliding sheet 150 is always in contact with the endless belt 130. In contrast, when the rotating body 120 rotates, each part of the inner peripheral surface of the endless belt 130 alternates between being in contact with the sliding sheet 150 and not being in contact with it.

[0040] The sliding sheet 150 is a sheet-like member. The sliding sheet 150 is made of, for example, a heat-resistant resin. As shown in FIG. 3, the sliding sheet 150 has an opposing surface 151 that faces the inner circumferential surface 131 of the endless belt 130. As shown in FIG. 4(a), the opposing surface 151 has a convex portion 152 and a concave portion 153.

[0041] The protrusions 152 are rib-shaped portions that protrude toward the endless belt 130. In this embodiment, the ratio of the area of ​​the protrusions 152 on the opposing surface 151 to the predetermined area is 50% or less. The protrusions 152 are made up of multiple ribs extending in different directions. Specifically, the protrusions 152 have a first rib 152A and a second rib 152B.

[0042] The first rib 152A extends in a first extension direction that is oblique to the moving direction of the endless belt 130. The first rib 152A extends linearly. In this embodiment, the angle between the moving direction of the endless belt 130 and the first extension direction is 45°.

[0043] 5(b), the first rib 152A extends continuously from an end 150A on one side in the width direction of the sliding sheet 150 to an end 150B on the other side of the sliding sheet 150. In other words, the first rib 152A extends from the end 150A on one side in the width direction of the endless belt 130 toward the end 150B on the other side as it moves downstream in the moving direction of the endless belt 130. In FIG. 5(b), the first ribs 152A and the second ribs 152B are shown enlarged to make the drawing easier to see, so the actual number of first ribs 152A and second ribs 152B is significantly greater than in FIG. 5(b).

[0044] Returning to FIG. 4(a), the second rib 152B extends in a second extension direction that intersects with the first extension direction. The second rib 152B extends linearly. In this embodiment, the angle between the movement direction of the endless belt 130 and the second extension direction is 45°. That is, in this embodiment, the angle between the movement direction of the endless belt 130 and the first extension direction is equal to the angle between the movement direction of the endless belt 130 and the second extension direction. That is, the second rib 152B extends in a direction perpendicular to the first rib 152A.

[0045] Here, the first rib 152A and the second rib 152B are each capable of contacting each other via grease GR (see FIG. 3). If the portions of the first rib 152A and the second rib 152B that are capable of contacting the endless belt 130 are defined as their respective apexes, the apex of the first rib 152A is higher than the apex of the second rib 152B. In other words, the apex of the second rib 152B is located closer to the recess 153 than the apex of the first rib 152A. Therefore, the first rib 152A has a side surface 152C at the portion where the second rib 152B connects to the first rib 152A. The side surface 152C faces in the second extension direction and connects the apex of the first rib 152A to the apex of the second rib 152B. The side surface 152C protrudes toward the endless belt 130 beyond the apex of the second rib 152B.

[0046] The recess 153 is a portion recessed in a direction away from the endless belt 130. In other words, the recess 153 is a portion recessed relative to the protrusion 152. The recess 153 is surrounded by the first rib 152A and the second rib 152B. In this embodiment, the recess 153 is a quadrangular pyramid-shaped depression with the base as the apex.

[0047] In this embodiment, the difference in height between the top of the first rib 152A and the top of the second rib 152B is 0.1 to 0.01 times the depth of the recess 153.

[0048] 2, the upstream belt guide 160 is a member that guides the movement of the endless belt 130 upstream of the nip portion NP in the conveying direction of the sheet S. The upstream belt guide 160 has a curved surface that allows the endless belt 130 to rotate smoothly.

[0049] The downstream belt guide 170 is a member that guides the movement of the endless belt 130 downstream of the nip portion NP in the conveying direction of the sheet S. The upstream belt guide 160 has a curved surface that allows the endless belt 130 to rotate smoothly.

[0050] The stay 180 is a member that supports the holder 140, the upstream belt guide 160, and the downstream belt guide 170. The stay 180 is formed by pressing a metal plate.

[0051] 3, the grease GR is disposed between the endless belt 130 and the sliding sheet 150. The grease GR is intended to reduce friction between the endless belt 130 and the sliding sheet 150. The grease GR is located on the inner circumferential surface 131 of the endless belt 130, and on the convex portions 152 and concave portions 153 of the sliding sheet 150.

[0052] Returning to FIG. 2, the fixing device 8 further includes a first temperature sensor TS1, a second temperature sensor TS2, and a thermostat 190.

[0053] 5(a), the first temperature sensor TS1 is a sensor that detects the temperature of the central portion in the width direction of the heating unit 81. The first temperature sensor TS1 is located in the central portion in the width direction. More specifically, the first temperature sensor TS1 is slightly shifted to one side in the width direction from the center in the width direction of the heating unit 81, that is, the conveyance center FC. The first temperature sensor TS1 is a sensor that does not come into contact with the heating unit 81.

[0054] The second temperature sensor TS2 is an example of a temperature sensor that detects the temperature of the other end portion in the width direction of the heating unit 81. The second temperature sensor TS2 is located at the other end portion in the width direction. The second temperature sensor TS2 is a contact-type sensor that comes into contact with the heating unit 81. The second temperature sensor TS2 is located outside the width of the largest sheet S that can be transported by the image forming apparatus 1.

[0055] As shown in Fig. 6, thermostat 190 is a known disk-type thermostat and has a cylindrical main body 190A and flat terminals 190B. As shown in Fig. 7, thermostat 190 is attached to fixing frame 80 with a spacer SP made of a resin film sandwiched between them. Frame 80 is disposed opposite heating unit 81 and has a thermostat support 80A that supports thermostat 190 and a first temperature sensor support 80B that supports first temperature sensor TS2.

[0056] The main body 190A has a temperature detection surface 190M capable of detecting the temperature of the endless belt 130. The temperature detection surface 190M is disposed opposite the outer circumferential surface of the endless belt 130 with a predetermined gap (a gap large enough to detect the temperature). In this case, the predetermined gap can be accurately determined by appropriately selecting the thickness and number of spacers. For example, when assembling the fixing device 8, spacers SP1, SP2, and SP3 of different thicknesses may be prepared, and the type and number of spacers SP may be determined after measuring the gap between the rotating body 120 and the temperature detection surface 190M.

[0057] Terminal 190B is connected to a circuit that supplies power to heater 110. When main body 190A detects a temperature higher than a predetermined temperature, thermostat 190 cuts off the current flow between main body 190A and terminal 190B, thereby cutting off the current flow to heater 110. This makes it possible to prevent the temperature of fixing device 100 from rising excessively.

[0058] As described above, the following effects can be obtained in this embodiment. The sliding sheet 150 in the fixing device 8 has an opposing surface 151 that faces the inner circumferential surface 131 of the endless belt 130 and has convex portions 152 and concave portions 153. The convex portions 152 have a first rib 152A and a second rib 152B. The first rib 152A extends in a first extension direction that is oblique to the movement direction of the endless belt 130. The first rib 152A has an exposed side surface 152C facing the second extension direction at a portion where the second rib 152B connects to the first rib 152A. Therefore, when the endless belt 130 moves in the movement direction, the grease GR moves in the first extension direction along the side surface 152C of the first rib 152A, allowing the grease GR to move in a specific direction.

[0059] Furthermore, the angle between the movement direction of the endless belt 130 and the first extension direction is equal to the angle between the movement direction of the endless belt 130 and the second extension direction. Therefore, deviation of the endless belt due to the frictional force of the first rib 152A and the frictional force of the second rib 152B with respect to the endless belt 130 can be suppressed.

[0060] The first rib 152A and the second rib 152B extend linearly, so that the entire first rib 152A can function to move the grease GR in a specific direction, in this embodiment, from one side to the other in the width direction.

[0061] Furthermore, the top of the first rib 152A is higher than the top of the second rib 152B, and at the portion where the second rib 152B connects to the first rib 152A, the side surface 152C protrudes further than the top of the second rib 152B toward the endless belt 130. This allows the grease GR to move easily along the first rib 152A.

[0062] Furthermore, the first rib 152A extends from one side to the other side in the width direction of the endless belt 130 as it moves downstream in the movement direction of the endless belt 130, and is provided with a second temperature sensor TS2 that detects the temperature of the end portion on the other side in the width direction of the rotating body 120. Therefore, the grease GR can be moved to the side where the temperature is detected (the other side in the width direction), and the temperature of the grease GR can be measured appropriately.

[0063] Next, a second embodiment will be described with reference to FIG. In the first embodiment, the top of the first rib 152A is higher than the top of the second rib 152B (see Figures 4(a) and (b)), whereas in the sliding sheet 250 of the second embodiment, the top of the first rib 252A and the top of the second rib 252B are configured to be the same height.

[0064] As shown in FIG. 8 , similar to the first embodiment, the sliding sheet 250 of the second embodiment has an opposing surface 251 with a convex portion 252 and a concave portion 253, and the convex portion 252 has a first rib 252A and a second rib 252B. In the second embodiment, the tops of the first rib 252A and the second rib 252B are at the same height. The opposing surface 251 of the sliding sheet 250 has a groove 252D located between the first rib 252A and the second rib 252B at a portion where the second rib 252B connects to the first rib 252A, the groove 252D extending in the first extension direction and crossing the second rib 252B is located between the first rib 252A and the second rib 252B. The side surface 252C of the first rib 252A facing the second extension direction is exposed at the portion where the groove 252D is formed.

[0065] In the sliding sheet 250 in the second embodiment, the grease GR also moves in the first extension direction through the grooves 252D, so that the grease GR can be moved in a specific direction.

[0066] Next, a third embodiment will be described with reference to FIG. The sliding sheet 350 of the third embodiment differs from the second embodiment in that it has a wall portion between the rib and the groove.

[0067] 9, the opposing surface 351 of the sliding sheet 350 has a protrusion 352 and a recess 353, and the protrusion 352 has a first rib 352A, a second rib 352B, a groove 352D, and a wall 352E. The wall 352E extends continuously from the groove 352D toward the endless belt 130 and protrudes further toward the endless belt 130 than the top of the first rib 352A. The first rib 352A has an exposed side surface 352C facing the second extension direction in the portion where the groove 352D and the wall 352E are formed.

[0068] In the sliding sheet 350 of the third embodiment, the grease GR also moves in the first extension direction through the grooves 352D and along the wall portions 352E, so that the grease GR can be moved in a specific direction.

[0069] Next, a fourth embodiment will be described with reference to FIG. 10, a sliding sheet 450 of the fourth embodiment has the same configuration as the sliding sheet 150 of the first embodiment, but also has a groove 452F in the first rib 152A. The groove 452F is provided at the top of the first rib 152A and extends in the first extension direction. The depth of the groove 452F is 0.1 to 0.01 times the depth of the recess 153.

[0070] In the sliding sheet 450 of the fourth embodiment, the grease GR can be moved in a specific direction by entering the grooves 452F.

[0071] Next, the fifth and sixth embodiments will be described with reference to FIGS. In the first embodiment, the opposing surface 151 of the sliding sheet 150 has a convex portion 152 consisting of multiple ribs and a square concave portion 153, but the concave portion is not limited to a square and may be a rectangle, a parallelogram, or any polygon other than a rectangle.

[0072] For example, as shown in FIG. 11(a), the opposing surface 551 of the sliding sheet 550 has a convex portion 552 consisting of multiple ribs and a hexagonal concave portion 553. The convex portion 552 has a first rib 552A and a second rib 552B. The first rib 552A has a zigzag shape and extends in the first extension direction while bending. The second rib 552B extends linearly in the second extension direction. The top of the first rib 552A is higher than the top of the second rib 552B. The first rib 552A has a side surface 552C at the portion where the second rib 552B connects to the first rib 552A. The side surface 552C faces the second extension direction and connects the top of the first rib 552A to the top of the second rib 552B. The side surface 552C protrudes toward the endless belt 130 from the top of the second rib 552B.

[0073] 11(a), for example, opposing surface 651 of sliding sheet 650 has convex portion 652 consisting of multiple ribs and triangular concave portion 653. Convex portion 652 has first rib 652A, second rib 652B, and third rib 652C.

[0074] The first rib 652A extends linearly in a first extension direction. The second rib 652B extends linearly in a second extension direction tilted 60° relative to the first extension direction. The third rib 652C extends linearly in a third extension direction tilted 60° relative to both the first extension direction and the second extension direction. The top of the first rib 652A is higher than the tops of the second rib 652B and the third rib 652C.

[0075] The first rib 652A has a side surface 652D at the portion where the second rib 652B connects to the first rib 652A. The side surface 652D faces the second extension direction and connects the top of the first rib 652A to the top of the second rib 652B. The side surface 652D protrudes toward the endless belt 130 beyond the top of the second rib 652B.

[0076] The first rib 652A has a side surface 652E at the portion where the third rib 652C connects to the first rib 652A. The side surface 652E faces the third extension direction and connects the top of the first rib 652A to the top of the third rib 652C. The side surface 652E protrudes toward the endless belt 130 beyond the top of the third rib 652C.

[0077] The sliding sheets 550 and 650 in the fifth and sixth embodiments also allow the grease GR to move in a specific direction.

[0078] Next, a seventh embodiment will be described with reference to FIG.

[0079] In the first embodiment, the first rib 152A extends continuously from the end 150A on one side of the width of the sliding sheet 150 to the end 150B on the other side (see Figure 5(a)), whereas in the sliding sheet 750 of the seventh embodiment, the first rib 752A extends from the end 750A on one side to the conveying center FC, which is an example of the central portion, which is different from the first embodiment.

[0080] As shown in FIG. 12, the opposing surface 751 of the sliding sheet 750 of the seventh embodiment has a convex portion 752 and a concave portion 753, and the convex portion 752 has a first rib 752A, a second rib 752B, a third rib 752C, and a fourth rib 752D.

[0081] The first rib 752A extends linearly in the first extension direction from one end 750A to the conveyance center FC of the sliding sheet 750 in the width direction of the endless belt .

[0082] The second rib 752B extends linearly in the second extension direction from one end 750A to the transfer center FC. The second rib 752B is connected to the first rib 752A. The first rib 752A has a side surface 752E facing the first extension direction exposed at the portion where the second rib 752B connects to the first rib 752A.

[0083] The third rib 752C extends linearly in the second extension direction from the other end 750B to the transfer center FC.

[0084] The fourth rib 752D extends linearly in the first extension direction from the other end 750B to the transfer center FC. The fourth rib 752D is connected to the third rib 752C. The third rib 752C has a side surface 752F facing the first extension direction exposed at the portion where the fourth rib 752D connects to the third rib 752C.

[0085] According to the seventh embodiment, the grease GR is concentrated in the center, and the lubricant can be prevented from leaking from the ends.

[0086] The present invention is not limited to the above-described embodiment, but can be used in various forms as exemplified below.

[0087] In the above embodiment, a cylindrical roller incorporating a heater 110 is exemplified as the rotating body, but the present invention is not limited to this. For example, the rotating body may be an endless belt whose inner peripheral surface is heated by a heater. Alternatively, an external heating method in which a heater is disposed outside the rotating body to heat the outer peripheral surface of the rotating body, or an induction heating method may be used. Alternatively, a heater may be disposed inside the endless belt to indirectly heat the rotating body that contacts the outer peripheral surface of the endless belt. Alternatively, the rotating body and the endless belt may each incorporate a heater.

[0088] In the above embodiment, the sliding sheet 150 is configured such that the area ratio of the convex portions 152 of the opposing surface 151 to the predetermined area is 50% or less, but the area ratio of the convex portions 152 may be greater than 50%.

[0089] In the above embodiment, the angle between the moving direction of the endless belt 130 and the first extension direction is 45°, and the angle between the moving direction of the endless belt 130 and the second extension direction is 45°, but this is not limited to 45° and may be, for example, any angle between 10° and 80°.

[0090] The elements described in the above-described embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0091] 1. Image forming device 2 Main unit housing 8 Fixing device 100 Fixing device 110 Heater 120 Rotating Body 130 endless belt 131 Inner surface 150 Sliding Sheet 150A end 150B end 151 Opposite surface 152 Convex part 152A First Rib 152B 2nd Rib 152C side 153 Recess GR Grease

Claims

1. A rotating body; an endless belt that contacts the outer circumferential surface of the rotating body; a heater for heating at least one of the rotating body and the endless belt; a pressure member that sandwiches the endless belt between itself and the rotating body; a sliding sheet sandwiched between the inner circumferential surface of the endless belt and the pressure member; a lubricant disposed between the endless belt and the sliding sheet, a surface of the sliding sheet facing the inner circumferential surface of the endless belt has a rib-shaped convex portion that is convex toward the endless belt and a concave portion that is concave relative to the convex portion, The convex portion is a first rib extending in a first extension direction that is oblique to a moving direction of the endless belt; a second rib extending in a second extension direction intersecting the first extension direction and connected to the first rib; The fixing device, wherein the first rib has a side surface facing the second extension direction exposed at a portion where the second rib is connected to the first rib.

2. 2. The fixing device according to claim 1, wherein an angle between the moving direction and the first extending direction is equal to an angle between the moving direction and the second extending direction.

3. 3. The fixing device according to claim 1, wherein the first rib and the second rib extend linearly.

4. 4. The fixing device according to claim 1, wherein the first rib and the second rib are perpendicular to each other.

5. The top of the first rib is higher than the top of the second rib, 5. The fixing device according to claim 1, wherein the side surface of the second rib protrudes toward the endless belt from the top of the second rib at a portion where the second rib connects to the first rib.

6. 6. The fixing device according to claim 1, wherein the opposing surface has a groove located between the first rib and the second rib at a portion where the second rib connects to the first rib and extending in the first extension direction.

7. the first rib extends from one side to the other side in a width direction of the endless belt as it moves downstream in the moving direction, 7. The fixing device according to claim 1, further comprising a temperature sensor that detects the temperature of the end portion of the rotating body on the other side in the width direction.

8. 8. The fixing device according to claim 7, wherein the first rib extends continuously from the end on one side to the end on the other side in the width direction.

9. the first rib extends from the end portion on the one side to a center portion of the sliding sheet in the width direction, The convex portion is a third rib extending in the second extension direction from the end portion on the other side in the width direction to a center portion of the sliding sheet in the width direction; a fourth rib extending in the first extension direction and connected to the third rib, The fixing device according to claim 7 , wherein the third rib has a side surface facing the first extension direction exposed at a portion where the fourth rib is connected to the third rib.

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