Fixing device

Abstract

To provide a fixing device that prevents lubricant from reaching an outer surface of a fixing belt to prevent a reduction in image quality.SOLUTION: A fixing device comprises a rotatable fixing belt, a heating roller, a steering roller, a pressure rotating body, and a slide member, and the pressure rotating body forms a nip part with the fixing belt. The fixing device fixes a toner image to a recording material at the nip part. Lubricant is applied to an inner peripheral surface of the fixing device. The slide member has a plurality of projections that slide with the fixing belt. In a state in which the nip part is formed, both ends in a width direction of the fixing belt are located outside an area where the projections are formed.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a fixing device for fixing a toner image on a recording material.

Background Art

[0002] An image forming apparatus has a fixing device for fixing an unfixed toner image on a recording material to the recording material.

[0003] A fixing device having a heating roller with a heat source for heating an unfixed toner image, an endless rotatable fixing belt to which heat is applied from the heating roller, and a pressure roller for pressing the fixing belt is known (Patent Document 1). The heating roller is disposed on the inner peripheral surface of the fixing belt and suspends the fixing belt. The pressure roller is positioned on the outer peripheral surface of the fixing belt and forms a nip portion together with the fixing belt by pressing a pad member through the fixing belt. A recording material carrying an unfixed toner image is conveyed to this nip portion, and when it is sandwiched and conveyed in the nip portion, heat and pressure are applied, and the toner on the recording material is fixed.

[0004] In the fixing device using the above-described fixing belt, it is known that steering control for adjusting the position in the width direction of the fixing belt is performed. By performing the steering control, scratches due to the edge portion of the recording material are suppressed. Also, it prevents the fixing belt from coming off the member that suspends the fixing belt.

[0005] With the increase in the printing speed of an image forming apparatus, a fixing device having a wider fixing nip width in the conveyance direction of the recording material has been proposed. By widening the fixing nip width, it is advantageous to cope with the increase in speed. On the other hand, widening the nip width increases the sliding resistance between the pad member and the fixing belt. Therefore, a configuration is known in which a lubricant is applied to the inner peripheral surface of the fixing belt and a sliding member is used to increase the slidability between the fixing belt and the pad member to reduce the sliding resistance.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2003-195671 [Overview of the project] [Problems that the invention aims to solve]

[0007] The fixing belt was shorter than the sliding member in the width direction. As a result, oil leaking from the inner surface of the belt would adhere to the sliding member on the outside of the fixing belt. Then, when steering control was performed, there was a risk that the oil adhering to the sliding member would adhere to the outer surface of the fixing belt. Subsequently, the oil adhering to the outer surface of the fixing belt would be transferred to the recording material, resulting in a decrease in image quality.

[0008] Therefore, the fixing device according to the present invention aims to suppress the deterioration of image quality that occurs when oil is transferred to the recording material. [Means for solving the problem]

[0009] In view of the above problems, the fixing device according to the present invention comprises a rotatable endless fixing belt, a heating roller that contacts the inner circumferential surface of the fixing belt and heats the fixing belt, a steering roller that contacts the inner circumferential surface of the fixing belt together with the heating roller and changes the position of the fixing belt in the width direction of the fixing belt, a pressurizing rotating body that pressurizes the fixing belt and forms a nip portion together with the fixing belt, a sliding member that contacts the inner circumferential surface of the fixing belt and is slidable with the inner circumferential surface of the fixing belt, and a fixing device that clamps and transports a recording material carrying unfixed toner in the nip portion and fixes the unfixed toner image to the recording material, wherein a lubricant is applied to the inner circumferential surface of the fixing belt, the sliding member has a first region having a plurality of protrusions that slide with the fixing belt, and a second region located outside the first region in the width direction and adjacent to the first region, and the second region is This is the region where the aforementioned protrusion is not provided.Regardless of the operation of the steering roller, when the nip portion is formed, both ends of the fixing belt in the width direction are located outside the first region. [Effects of the Invention]

[0010] The fixing device of the present invention reduces the amount of oil adhering to the outer surface of the fixing belt, thereby suppressing a decrease in image quality. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view of the image forming apparatus in this embodiment. [Figure 2] This is a schematic cross-sectional view of the fixing device in this embodiment. [Figure 3] This is a perspective view of the fixing device in this embodiment. [Figure 4] This is a view of the fixing device in this embodiment, as seen from the transport direction. [Figure 5] This is a schematic diagram of the sliding member in this embodiment. [Figure 6] This is a schematic diagram of the nip portion including the sliding member in this embodiment. [Figure 7] This is a schematic diagram of the nip portion including the sliding member in this embodiment. [Figure 8] This is a schematic diagram of the nip portion including the sliding member in a modified example. [Modes for carrying out the invention]

[0012] The embodiments of the image forming apparatus in this embodiment will be described below with reference to the drawings. While the following description will focus on the application of the present invention to a full-color electrophotographic image forming apparatus having multiple photosensitive drums, the present invention is not limited to this and can also be applied to monochrome image forming apparatuses and the like.

[0013] <Image forming apparatus> The schematic configuration of the image forming apparatus 100 of this embodiment will be explained with reference to Figure 1.

[0014] FIG. 1 is a diagram showing a full-color image forming apparatus according to the present embodiment. Along the moving direction of the intermediate transfer belt 115, four types of image forming units 110, namely a yellow image forming unit 120a, a magenta image forming unit 120b, a cyan image forming unit 120c, and a black image forming unit 120d, are arranged. First, the process of forming a toner image on the intermediate transfer belt 115 will be described taking the yellow image forming unit 120a as an example.

[0015] In FIG. 1, the surface of the photosensitive drum 111 driven to rotate is uniformly charged (charging) by the charger 112. Thereafter, the surface of the photosensitive drum 111 is irradiated with a laser according to the image data input to the exposure device 113, and an electrostatic latent image is formed on the surface of the photosensitive drum 111 (exposure). Thereafter, a yellow toner image is formed on the photosensitive drum 111 by the developing device 114. The primary transfer roller 117 applies a voltage having a polarity opposite to the potential polarity of the yellow toner image to the intermediate transfer belt 115. As a result, the yellow toner on the photosensitive drum 111 is transferred to the intermediate transfer belt 115 (primary transfer). Incidentally, the yellow toner remaining on the surface of the photosensitive drum 111 without being transferred is scraped off by the toner cleaner and removed from the surface of the photosensitive drum 111. This series of processes is similarly performed in the magenta image forming unit 120b, the cyan image forming unit 120c, and the black image forming unit 120d. As a result, a full-color toner image is formed on the intermediate transfer belt.

[0016] The toner image on the intermediate transfer belt 115 is conveyed to the secondary transfer portion N2 formed by the secondary transfer roller 116. The recording material P is taken out one by one from the recording material cassette 103 and fed to the secondary transfer portion N2 in accordance with the timing of conveyance of the toner image. Then, the toner image on the intermediate transfer belt 115 is transferred to the recording material P (secondary transfer).

[0017] The recording material P onto which the toner image has been transferred is conveyed to the fixing device 200, where it is fixed by receiving heat and pressure (fixing). The recording material P on which the toner image has been fixed is discharged to the paper discharge tray.

[0018] The image forming apparatus 100 can also perform monochrome image formation. During monochrome image formation, only the black image forming unit 120d among the plurality of image forming units 110 is driven.

[0019] When performing image formation on both sides of the recording material P, after the transfer and fixing of the toner on the first side of image formation (the first side) are completed, the recording material P is guided to the conveyance path 134 by the flapper 132 provided inside the image forming apparatus after fixing. Then, the recording material P is conveyed to the reversing unit 136. When the reversing sensor 135 detects the trailing edge of the recording material P, the flapper 133 switches the conveyance direction of the recording material P to the reversing path 137. The image forming apparatus 100 conveys the reversed recording material P through the reversing path 137 to the image forming unit 110 again and further to the fixing device 200. The recording material P that has completed double-sided printing is guided to the discharge path 139 by the flapper 132 and discharged to the outside.

[0020] This process from charging to the recording material P on which the toner image has been fixed being discharged to the paper discharge tray is defined as the image forming process (print job). Also, the period during which image formation is being performed is defined as the period during image formation processing (during the print job).

[0021] The operation unit 180 includes a display screen and selection keys. The operation unit 180 displays the state of the image forming apparatus 100 on the display screen and receives operation instructions from the operator (user) using the selection keys.

[0022] The control board 150 has a control unit 151 and a memory 152, and controls each unit in the image forming apparatus 100 described above. The control unit 151 outputs output signals to each electrical component in order to operate the electrical component at the desired timing and with the required control amount, based on detection signals input from each sensor and information stored in the memory 152. Therefore, it is the control unit 151 that actually controls the electrical components. The memory 152 stores information data necessary for controlling each unit, and the control unit 151 reads and writes the information data stored in the memory 152.

[0023] <Fusing device> Next, the details of the fixing device configuration in this embodiment will be described using Figures 2 and 3. Figure 2 is a cross-sectional view of the fixing device in an embodiment of the present invention, and Figure 3 is a partial perspective view of the fixing device 200. Figure 2 shows a schematic diagram of the overall configuration of the belt heating type fixing device 200 according to this embodiment. In Figure 2, the recording material P is conveyed from right to left on the paper. The fixing device 200 has a heating unit 210 having a heat source and a pressurizing rotating body (hereinafter referred to as a pressurizing roller) 202 that forms a nip portion N together with the heating unit 210. The heating unit 210 has a fixing belt (hereinafter referred to as a belt) 201 as an endless and rotatable heating rotating body, a pad member (hereinafter referred to as a pad) 203 as a fixing member, a heating roller 204 and a steering roller 205.

[0024] The belt 201 has thermal conductivity and heat resistance, and is a thin-walled cylindrical shape. In this embodiment, it has a three-layer structure with a base layer, an elastic layer on the outer circumference of the base layer, and a release layer on the outer circumference of the elastic layer. The base layer is 60 μm thick and made of polyimide resin (PI), the elastic layer is 300 μm thick and made of silicone rubber, and the release layer is 30 μm thick and made of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin) as a fluororesin. The belt 201 is stretched by a pad 203, a heating roller 204, and a steering roller 205.

[0025] The pad 203 is a component that presses against the pressure roller 202 via the belt 201 to form a nip portion N of a predetermined width in the recording material transport direction. Its cross-section is approximately rectangular, and it is a long component along the width direction of the belt 201. The material of the pad 203 needs to be heat resistant, and LCP (liquid crystal polymer) resin is used.

[0026] A sliding member 207 and silicone oil S (hereinafter referred to as oil S) are interposed between the pad 203 and the belt 201, so that the belt 201 slides smoothly against the pad 203.

[0027] The oil supply roller 208 is formed by impregnating a roll-shaped member, which is wrapped with a 100 μm thick nonwoven fabric, with silicone oil. The oil supply roller 208 is in contact with the inner surface of the belt 201 with a force of 3.0 N by a compression spring 209 and is supported by the frame of the heating unit 210 so as to be driven and rotatable.

[0028] The oil S applied as a lubricant between the pad 203 and the belt 201 deteriorates with the operation of the fixing device 200 and decreases due to leakage to the outside, etc. If the oil S between the pad 203 and the belt 201 can no longer be retained, the sliding resistance between the pad 203 and the belt 201 will increase, which may cause problems such as poor driven rotation of the belt 201. The oil supply roller 208 makes it possible to supply oil S to the inner circumferential surface of the belt 201 by contact. This makes it possible to maintain the oil S interposed between the belt 201 and the pad 203 (sliding member 207) for a longer period of time and maintain stable operation of the fixing device 200. In this embodiment, the fixing device 200 has an oil supply roller 208, but it is also acceptable for the oil S to be applied to the inner circumferential surface of the belt 201 during the manufacturing process of the fixing device 200. In other words, it is also acceptable for the fixing device 200 to not have an oil supply roller 208.

[0029] A stay 206 is positioned inside the belt 201. The stay 206 is located on the side opposite to the sliding member 207, inside the pad 203. The stay 206 is a rigid reinforcing member that is long in the width direction of the belt 201 and backs up the pad 203. It is made of 3mm thick extruded SUS304 stainless steel, and its strength is ensured by forming the cross-section into a hollow "square" shape. When the pad 203 is pressed against the pressure roller 202, the stay 206 provides strength to the pad 203 and ensures the applied pressure at the nip portion N. Note that the material of the stay 206 is not limited to stainless steel as long as strength can be ensured.

[0030] The heating roller 204 is a 1 mm thick stainless steel pipe with a halogen heater (not shown) installed inside, capable of generating heat to a predetermined temperature. The belt 201 is heated by the heating roller 204 and controlled to a predetermined target temperature according to the paper type based on temperature detection by a thermistor. The heating roller 204 may also be configured to rotate. By rotating the heating roller 204, it is possible to increase the tension of the belt 201 from the nip section N to the heating roller 204 in the direction of belt rotation. This allows for an increase in the curvature of the exit of the nip section N in the direction of belt rotation, thereby improving the separation performance of the recording material P.

[0031] The steering roller 205 suspends the belt 201 and is supported by the steering frame 213. As the steering frame 213 rotates relative to the frame of the heating unit 210 with the pivot axis 212 as the pivot point, the steering roller 205 changes its alignment with respect to other suspension members. This creates a tension difference between the front and rear of the belt 201. As shown in Figure 4, this controls the position of the belt 201 by moving it in the U direction in the width direction of the belt 201. The steering roller 205 is biased by a spring 211 supported by the steering frame 213 and also acts as a tension roller that applies a predetermined tension to the belt 201.

[0032] Furthermore, the steering roller 205 also plays a role in suppressing uneven gloss caused by the edge of the recording material P. In this embodiment, a force of approximately 2000 N is applied to the belt 201 at the nip portion N. When fixing unfixed toner to the recording material, the part of the belt 201 that comes into contact with the edge of the recording material P experiences greater stress than the part that does not come into contact with the edge. The area that the edge of the recording material repeatedly passes over becomes concave compared to the area that does not come into contact with the edge. This concavity caused by the edge of the recording material on the surface of the belt 201 is called a paper edge scratch.

[0033] When fixing unfixed toner to the recording material, the fixing device 200 applies pressure and heat to the recording material. At this time, the surface condition of the belt 201 is reflected in the gloss of the image surface after fixing. If there are irregularities on the surface of the belt 201, the state of these irregularities will be reflected in the gloss of the image surface, resulting in uneven gloss (gloss unevenness) on the image surface. Therefore, if unfixed toner is fixed to the recording material with paper edge scratches on the surface of the belt 201, gloss unevenness resembling straight lines will occur on the image surface. In this embodiment, in order to suppress paper edge scratches on the surface of the belt 201, the belt 201 is moved back and forth in the width direction.

[0034] The fixing device 200 in this embodiment has a position detection unit (not shown) that detects the position of the belt 201 in the width direction. An arm is provided at the end of the belt 201 that abuts the belt 201 from the outside to the inside in the width direction. By detecting the position of this arm with a sensor such as a photointerrupter, the position of the belt 201 in the width direction can be determined. In order to accurately detect the position of the belt 201 in the width direction, the direction in which the arm applies force to the belt 201 is from the outside to the inside in the width direction. Also, in order to apply force in this direction, the rotation axis of the arm is perpendicular to the width direction. Therefore, the arm that detects the position of the belt in the width direction rotates in the width direction around the rotation axis mentioned above. By detecting the position of the belt 201 in the width direction, it is possible to suppress the belt 201 from coming off the members that suspend the belt 201 (pad 203, heating roller 204, and steering roller 205). In addition, the belt 201 can be actively moved in the width direction to prevent edge damage.

[0035] The pressure roller 202 is a roller with an elastic layer formed on the outer circumference of its shaft and a release layer formed on the outer circumference of the elastic layer. The shaft is made of stainless steel, the elastic layer is made of conductive silicone rubber with a thickness of 5 mm, and the release layer is made of PFA as a fluororesin with a thickness of 50 μm. The pressure roller 202 is supported by the fixing frame 380 of the fixing device 200, and a gear is fixed to one end of it, which is connected to the drive source M to rotate it. The belt 201 is driven to rotate in the R direction by being sandwiched between the rotating pressure roller 202 and the pad 203.

[0036] <Contact / separation mechanism> The contact and separation mechanism of the pressure roller 202 will be described. The pressure roller 202 can move to a position in contact with or separated from the belt 201 by the contact and separation mechanism. The contact and separation mechanism has a pressure frame 202b and a drive motor. The pressure frame 202b supports the pressure roller 202. The pressure frame 202b rotates with the pressure rotation axis 202a as its axis of rotation, driven by the drive motor. When the drive motor rotates the pressure frame 202b clockwise on the plane of the paper with the pressure rotation axis 202a as its axis of rotation, the pressure roller 202 moves in the direction of arrow P. As a result, the pressure roller 202 comes into contact with the belt 201 and the pad 203 in a direction perpendicular to the transport direction of the recording material, i.e., in the pressurizing direction (contact state). This forms the fixing nip portion N. When the pressure frame 202b is rotated counterclockwise on the plane of the paper with the pressure rotation axis 202a as its axis of rotation, the pressure roller 202 is separated from the belt 201 (separated state).

[0037] As described above, a pad 203, a heating roller 204, and a steering roller 205 are arranged on the inner surface of the belt 201, suspending the belt 201. The belt 201 is held between the pressure roller 202 and the pad 203, and rotates as the pressure roller 202 is driven. The belt 201 stores heat from the heating roller 204. When the recording material P carrying the unfixed toner image is held and conveyed by the pressure roller 202 and the belt 201 at the nip section N, the heat and pressure necessary for fixing are applied. As a result, the toner image is fixed onto the recording material P.

[0038] <Sliding member> The pad 203 is pressed against the pressure roller 202 via the belt 201, thereby forming a fixing nip portion N. The pad 203 is made of LCP (liquid crystal polymer) resin. A sliding member 207 is interposed between the pad 203 and the belt 201.

[0039] In this embodiment, the fixing device F has a pressure of 1600N applied to the fixing nip section N and a nip width of 24.5mm, resulting in high sliding resistance between the pad 203 on which the belt 201 is stretched. To reduce this sliding resistance, a sliding member 207 that can slide against the belt 201 is provided on the belt 201 side of the pad 203. Details are described below.

[0040] The detailed configuration of the sliding member 207 is shown in Figure 5. Figure 5a) is a cross-sectional view of the sliding member 207 when the left-right direction on the plane of the paper is the conveying direction (X direction) and the up-down direction is the pressing direction (Z direction). Figure 5b) is a view of the sliding member 207 as seen from the pressurizing roller 202 side, when the left-right direction on the plane of the paper is the width direction (Y direction) and the up-down direction is the conveying direction (X direction). As shown in Figure 3a), the sliding member 207 of this embodiment is composed of a base material portion 207a, an embossed portion 207b which is a projection, and a sliding layer 207c. The base material portion 207a should have sufficient heat resistance and strength. The material should preferably be SUS, copper, aluminum, or engineering plastic (PI, PEEK, LCP, etc.). In this embodiment, the sliding member 207 has embossed portions arranged at equal intervals with a distance d (distance between projections) of 1.4 mm in the width direction. By providing the embossed portion 207b, the contact area with the belt 201 is reduced, thereby lowering sliding resistance. In this embodiment, the base material portion 207a and the embossed portion 207b are made of SUS, which is a metal. It is preferable to use any metal with excellent heat resistance and durability, not limited to SUS.

[0041] In order to achieve low friction, it is preferable to provide a material (such as a fluorine coating, PTFE, or PFA) in the sliding layer 207c. In this embodiment, a PTFE (polytetrafluoroethylene) coating with a thickness of 20 μm was applied. As mentioned above, the frictional force between the inner surface of the belt 201 and the sliding member 207 is very large, so by further applying a lubricant, the belt 201 can slide smoothly against the sliding member 207. Silicone oil was used as the lubricant.

[0042] In this embodiment, the sliding member 207 is configured to cover the pad 203 both inside and outside the nip portion N. Although not shown here, it is acceptable if only a part of the fixing nip portion N is covered by the sliding member 207. In other words, it is also acceptable to have a configuration in which the sliding member 207 is placed only on the nip portion N.

[0043] In this embodiment, the embossed portion 207b of the sliding member is provided over the entire surface of the sliding member 207. Although not shown here, it is acceptable if a portion of the fixing nip portion N is covered by the embossed portion 207b of the sliding member. In other words, it is also acceptable to have a configuration in which the embossed portion 207b of the sliding member is located only on the nip portion N. The embossed portion 207b provided on the nip portion N is in contact with the belt 201 via the sliding layer 207c.

[0044] In this embodiment, a configuration is adopted in which the sliding member 207 is fixed to the stay 206. (Not shown) Although not shown here, the sliding member 207 and the pad 203 may be integrated. Alternatively, the sliding member 207 may be partially fixed to the stay 206 or the pad 203. For example, both ends of the sliding member 207 in the Y direction (width direction) may be fixed to the pad 203 with screws or the like.

[0045] In this embodiment, the pressure applied to the fixing nip section N is 1600N, the length of the fixing nip section N in the transport direction is 24.5mm, and the length in the width direction is 326mm.

[0046] <Degradation of image quality due to lubricant> In this embodiment, a lubricant, oil S, is used in the fixing device 200 using the belt 201. The oil S is applied to the inner circumferential surface of the belt 201. At the nip portion N, pressure is generated by the pad 203 and the pressure roller 202, so a force acts on the oil S applied to the inner circumferential surface of the belt 201, pushing it out from the inner circumferential surface of the belt 201. If the belt 201 is shorter than the sliding member 207 or the pad 203 in the width direction, the pushed-out oil S may travel along the sliding member 207 or the pad 203 and adhere to the outer circumferential surface of the belt 201.

[0047] Furthermore, in this embodiment, a steering roller 205 is used to reciprocate the belt 201 in the width direction. If there is oil S exposed in the outer region of the belt 201, it will be very likely that the oil S will adhere to the outer surface of the belt 201. As the belt 201 rotates in the R direction in Figure 2, the oil S adhering to the outer surface of the belt 201 will reach the nip portion N. If the oil S then adheres to the recording material P conveyed to the nip portion N, the area where the oil S has adhered will result in image defects. Therefore, it is necessary to suppress the adhesion of oil S to the region of the belt 201 that comes into contact with the recording material S.

[0048] The oil S travels along the irregularities provided on the sliding member 207 from the inner circumferential surface of the belt 201 before reaching the outer surface of the belt 201. Therefore, in the fixing device 200 of this embodiment, the length of the belt 201 in the width direction is made longer than the area where the embossed portion 207 is provided. The details are described below.

[0049] <Relationship between the length of the belt and the sliding member> The relationship in the width direction will be explained using Figure 6. Figure 6 shows one end of the fixing device 200, which includes the belt 201, the pad 203, and the sliding member 207. The left-right direction on the plane of Figure 6 is defined as the width direction. The other end has the same relationship, so its explanation is omitted.

[0050] The sliding member 207 has a region in which the embossed portion 207b is provided, and a non-installed region 207e located outside the region in the width direction of the region in which the embossed portion 207b is provided, where the embossed portion 207b is not provided.

[0051] As shown in Figure 6, in the width direction, the belt 201 is longer than the area on the sliding member 207 where the embossed portion 207b is installed.

[0052] The oil S applied between the inner circumferential surface of the belt 201 and the embossed portion 207b leaks out beyond the area where the embossed portion 207b is located. However, because the belt 201 is long in the width direction, the oil S that leaks out beyond the area where the embossed portion 207b is located does not easily reach the outer surface of the belt 201. Therefore, the oil S is more easily retained on the inner circumferential surface of the belt 201, and the adhesion of the oil S to the outer surface of the belt 201 can be suppressed.

[0053] Furthermore, the belt 201 and the pad 203 are in contact at the exit of the nip portion N. Therefore, if oil S adheres to the pad 203, there is a risk that it may travel along the pad 203 and adhere to the outer surface of the belt 201. For this reason, as shown in Figure 6, in this embodiment, the belt 201 is longer than the pad 203 in the width direction.

[0054] In this embodiment, a steering roller 205 is used. In the width direction, the end 207g of the belt 201 is repositioned by the steering roller 205. However, as shown in Figure 7, even when the end 207g of the belt 201 is repositioned by the steering roller 205, in the width direction, the end 207g of the belt 201 is located outside the embossed portion 207b. This makes it possible to suppress the adhesion of oil S to the outer surface of the belt 201 even in a fixing device 200 having a steering roller 205. In this configuration, oil S leaking from the embossed portion 207b accumulates in the non-installed area 207e. However, the oil S accumulated in the non-installed area 207e is pulled back to the inside of the belt 201 in the width direction by surface tension. As a result, oil S is resupplied from the non-installed area 207e, thus suppressing the adhesion of oil S to the outer surface of the belt 201.

[0055] The steering roller 205 changes the position of the end 201g of the belt 201 in the width direction. However, as shown in Figure 8 as a modified example, even when the end 201g of the belt 201 is changed by steering control, the end 201g of the belt 201 may be located outside the end 203g of the pad and the end 207g of the sliding member 207. This prevents the oil S from traveling along the pad 203 and the sliding member 207 and adhering to the outer surface of the belt 201.

[0056] In this embodiment, the sliding member 207 is fixed to the stay 206 by screws or the like. The areas for inserting the screws are provided at both ends of the sliding member 207 in the width direction. Therefore, the length including the sliding member 207 and the areas for inserting the screws in the width direction is longer than the length of the belt 201. However, the areas for inserting the screws are not limited to both ends in the width direction, but may also be at both ends in the conveying direction. In other words, the areas for inserting the screws are not included in the non-installation area 207e. [Explanation of symbols]

[0057] 100 Image forming apparatus 200 Fixing device 201 Fixing belt 202 Pressure Roller 203 pad 204 Heated Rotating Body 205 Steering Roller 206 Stay 207 Sliding member

Claims

1. A rotatable, endless fixing belt and A heating roller that contacts the inner circumferential surface of the fixing belt and heats the fixing belt, A steering roller, which contacts the inner circumferential surface of the fixing belt together with the heating roller and changes the position of the fixing belt in the width direction of the fixing belt, A pressing rotating body pressurizes the fixing belt and forms a nip portion together with the fixing belt, A sliding member that contacts the inner circumferential surface of the fixing belt and is slidable with the inner circumferential surface of the fixing belt, In a fixing device that uses the aforementioned nip section to grip and transport a recording material on which unfixed toner is carried, and fixes the unfixed toner image onto the recording material, A lubricant is applied to the inner circumferential surface of the aforementioned fixing belt. The sliding member has a first region having a plurality of protrusions that slide against the fixing belt, and a second region located outside the first region in the width direction and adjacent to the first region, wherein the second region is a region where no protrusions are provided. A fixing device characterized in that, regardless of the operation of the steering roller, when the nip portion is formed, both ends of the fixing belt in the width direction are located outside the first region.

2. The fixing device according to claim 1, further comprising a pad member that holds the sliding member and forms a nip portion by clamping the fixing belt together with the pressurizing rotating body.

3. The fixing device according to claim 2, characterized in that, when the nip portion is formed, the length of the pad member in the width direction is shorter than the length of the fixing belt in the width direction.

4. The fixing device according to any one of claims 1 to 3, characterized in that, with the nip portion formed, both ends of the fixing belt are located outside the pressurizing rotating body in the width direction.

5. During the operation of the steering roller, The end of the fixing belt on one end in the width direction can be located outside the end of the sliding member on the one end, or inside the second region on the one end. The fixing device according to any one of claims 1 to 4, characterized in that...

6. The lubricant is oil. A fixing device according to any one of claims 1 to 5, characterized by the following:

7. Having an oil application roller for applying the aforementioned oil The fixing device according to feature 6.

8. The height of the second region is the same as the height of the base layer portion of the region in the first region where the multiple protrusions are present but no protrusions are formed. During the operation of the steering roller, The end of the anchoring belt on one end in the width direction can be positioned outside the end of the second region on the one end, or inside the end of the second region on the one end. The fixing device according to any one of claims 1 to 7, characterized by the features described herein.

Images