Fixing device and image forming apparatus

Abstract

To suppress the adhesion of a lubricant to a recording material and to suppress the deterioration of image quality by suppressing the adhesion of the lubricant to the surface of a belt member abutting on the recording material.SOLUTION: The fixing device 200 includes the oil recovery member 240 that is provided at a position across at least each of both end portions 201a of the fixing belt 201 in the widthwise direction, is disposed to face the 201b portion of the inner peripheral surface of the fixing belt 201, and comes into contact with or separates from the 201b portion of the inner peripheral surface of the fixing belt 201 according to the steering angle when the steering roller 205 rotates about the center portion Q in the widthwise direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fixing device that fixes a toner image on a recording material and an image forming apparatus that includes the fixing device. [Background technology]

[0002] Conventionally, image forming apparatuses have a fixing device that fixes an unfixed toner image on a recording material to the recording material. The fixing device includes a heating roller having a heat source for heating the unfixed toner image, an endless rotatable fixing belt that receives heat from the heating roller, and a pressure roller that applies pressure to the fixing belt (for example, see Patent Document 1).

[0003] In such a fixing device, the heating roller is disposed inside the fixing belt and suspends the fixing belt. The pressure roller is disposed outside the fixing belt and presses a pad member disposed inside the fixing belt through the fixing belt, thereby forming a fixing nip with the fixing belt. The recording material carrying an unfixed toner image is conveyed to the fixing nip and is subjected to heat and pressure as it is sandwiched and conveyed in the fixing nip. This fixes the toner image on the recording material to the recording material.

[0004] Furthermore, in the past, as the printing speed of image forming devices has increased, fixing devices have been proposed that have a wider fixing nip in the recording material transport direction. By widening the fixing nip in the recording material transport direction, the time during which heat and pressure are applied to the recording material at the fixing nip can be increased, and the toner image on the recording material can be reliably fixed to the recording material even at higher speeds.

[0005] On the other hand, if the width of the fixing nip portion in the recording material conveyance direction is increased, the contact area between the pad member and the fixing belt becomes larger, resulting in increased sliding resistance. Therefore, a fixing device having a configuration in which a lubricant is applied to the inner peripheral surface of the fixing belt to reduce the sliding resistance between the fixing belt and the pad member is known. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-195671 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in a conventional fixing device in which a lubricant is applied to the inner peripheral surface of the fixing belt, when the pressure roller presses the pad member, the lubricant applied to the inner peripheral surface of the fixing belt is pushed outward from the inner peripheral surface of the fixing belt. The lubricant pushed outward from the inner peripheral surface of the fixing belt flows around the end surfaces of the fixing belt and the outer side of the end surfaces, and adheres to the surfaces of rotating members, such as a heating roller, that contact the fixing belt. The lubricant that has adhered to the surfaces of the rotating members in this way gradually accumulates as the fixing device operates, and eventually adheres to the outer peripheral surface of the fixing belt that contacts the recording material. This creates a problem in that the lubricant that has adhered to the outer peripheral surface of the fixing belt may further adhere to the recording material passing through the nip, potentially reducing image quality.

[0008] The object of the present invention is to provide a fixing device and an image forming device that can prevent a lubricant from adhering to the surface of a belt member that contacts the recording material, thereby preventing the lubricant from adhering to the recording material and preventing a deterioration in image quality. [Means for solving the problem]

[0009] The fixing device of the present invention is a fixing device that fixes a toner image to a recording material, and is characterized by having a rotatable endless belt member having a first surface that contacts the recording material and a second surface opposite the first surface that is coated with a lubricant, a nip forming member provided inside the belt member, a pressure rotating body that forms a fixing nip portion that sandwiches and transports the recording material together with the belt member by pressing the nip forming member through the belt member, a rotating member that contacts the second surface of the belt member and rotates around a center portion in a width direction perpendicular to the transport direction of the recording material, and a lubricant recovery member that is provided at a position spanning at least both end portions of the belt member in the width direction, is positioned opposite the second surface of the belt member, and abuts or moves away from the second surface of the belt member depending on the rotation angle when rotating around the center portion of the rotating member. [Effects of the Invention]

[0010] According to the present invention, by preventing the adhesion of lubricant to the surface of the belt member that contacts the recording material, it is possible to prevent the adhesion of lubricant to the recording material and also to prevent a decrease in image quality. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to a first embodiment of the present invention. [Figure 2] 1 is a cross-sectional view of a fixing device according to a first embodiment of the present invention. [Figure 3] 1 is a perspective view of a part of a fixing device according to a first embodiment of the present invention. [Figure 4] 1 is a schematic diagram of a part of a fixing device according to a first embodiment of the present invention. [Figure 5] 5 is a diagram showing the relationship between the shift speed and the amount of exposed oil in the fixing device according to the first exemplary embodiment of the present invention. FIG. [Figure 6] FIG. 4 is a diagram showing setting conditions of the fixing device according to the first embodiment of the present invention. [Figure 7]4 is a schematic diagram of a fixing device according to the first embodiment of the present invention when a steering angle is small in part. FIG. [Figure 8] 4 is a schematic diagram of the fixing device according to the first embodiment of the present invention when a steering angle is large in part. FIG. [Figure 9] FIG. 2 is a cross-sectional view of a fixing device of a comparative example to be compared with the fixing device according to the first embodiment of the present invention. [Figure 10] 5 is a diagram showing the relationship between the amount of oil adhesion and the amount of wear in the fixing device according to the first embodiment of the present invention. FIG. [Figure 11] FIG. 6 is a cross-sectional view of a fixing device according to a second embodiment of the present invention. [Figure 12] FIG. 10 is a perspective view of a part of a fixing device according to a second embodiment of the present invention. [Figure 13] 10 is an enlarged schematic view of a part of a fixing device according to a second embodiment of the present invention. FIG. [Figure 14] FIG. 10 is a cross-sectional view of a fixing device of a comparative example to be compared with the fixing device according to the second embodiment of the present invention. [Figure 15] 10 is a diagram showing the relationship between the amount of oil adhesion and the amount of wear in a fixing device according to the second embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the drawings.

[0013] (Embodiment 1) <Configuration of image forming device> The configuration of an image forming apparatus 100 according to the first embodiment of the present invention will be described in detail with reference to FIG.

[0014] Here, a full-color image forming apparatus is exemplified as the image forming apparatus 100. Specifically, the image forming apparatus 100 includes a recording material cassette 103, an intermediate transfer belt 115, a secondary transfer roller 116, a primary transfer roller 117, image forming units 120a, 120b, 120c, and 120d. The image forming apparatus 100 also includes a flapper 132, a flapper 133, a reversal sensor 135, a control board 150, an operation unit 180, and a fixing device 200.

[0015] The intermediate transfer belt 115, the secondary transfer roller 116, the primary transfer roller 117 and the image forming units 120a, 120b, 120c, and 120d constitute an image forming means that forms a toner image on the recording material P and transports the recording material P with the toner image formed thereon to the fixing device 200.

[0016] The recording material cassette 103 accommodates the recording material P.

[0017] A full-color toner image is formed on the intermediate transfer belt 115 by sequentially performing primary transfer of toner images from the photosensitive drums 111 of the image forming units 120a, 120b, 120c, and 120d by primary transfer rollers 117. The intermediate transfer belt 115 transports the formed toner images to secondary transfer rollers 116.

[0018] A pair of secondary transfer rollers 116 are provided. The secondary transfer rollers 116 contact each other via the intermediate transfer belt 115 to form a secondary transfer portion N2. The secondary transfer rollers 116 perform a second transfer of the toner image formed on the intermediate transfer belt 115 onto the recording material P that is taken out one by one from the recording material cassette 103 and fed in accordance with the transport timing of the toner image transported by the intermediate transfer belt 115.

[0019] The secondary transfer roller 116 performs second transfer of the toner image formed on the intermediate transfer belt 115 onto the recording material P conveyed by the reversing path 137 in accordance with the conveyance timing of the toner image conveyed by the intermediate transfer belt 115. The secondary transfer roller 116 conveys the recording material P onto which the toner image has been secondarily transferred to the fixing device 200.

[0020] Image forming units 120a, 120b, 120c, and 120d are arranged along the direction of movement of intermediate transfer belt 115, and form full-color toner images.

[0021] The image forming unit 120 a forms a yellow toner image and transfers the formed yellow toner image onto the intermediate transfer belt 115 .

[0022] The image forming unit 120 b forms a magenta toner image and transfers the formed magenta toner image onto the intermediate transfer belt 115 .

[0023] The image forming unit 120 c forms a cyan toner image and transfers the formed cyan toner image onto the intermediate transfer belt 115 .

[0024] The image forming unit 120d forms a black toner image and transfers the formed black toner image onto the intermediate transfer belt 115.

[0025] Each of the image forming units 120a, 120b, 120c, and 120d includes a photosensitive drum 111, a charger 112, an exposure device 113, and a developing device 114.

[0026] The photosensitive drum 111 is rotated by a drive motor (not shown).

[0027] The charger 112 uniformly charges the surface of the photosensitive drum 111 .

[0028] The exposure device 113 forms an electrostatic latent image on the surface of the photosensitive drum 111 by irradiating the surface of the photosensitive drum 111, which has been charged by the charger 112, with a laser in accordance with image data input from the control unit 151 (described later) of the control board 150.

[0029] The developing device 114 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 111 by the exposure device 113 , thereby forming a toner image on the surface of the photosensitive drum 111 .

[0030] Each of the image forming units 120a, 120b, 120c, and 120d is equipped with a toner cleaner (not shown) that scrapes off and removes toner remaining on the surface of the photosensitive drum 111 without being transferred.

[0031] The primary transfer roller 117 applies a voltage having a potential polarity opposite to that of the toner image to the intermediate transfer belt 115 , thereby primarily transferring the toner image on the photosensitive drum 111 onto the intermediate transfer belt 115 .

[0032] When images are to be formed on both sides of the recording material P, the flapper 132, under the control of the control section 151 of the control board 150, guides the recording material P, on which the toner image has been transferred and fixed onto the first image forming surface (first side) of the recording material P, to a conveying path 134 and conveys it to a reversing section 136. The flapper 132 guides the recording material P, on which an image is to be formed on only one side, or the recording material P, on which the toner image has been transferred and fixed onto the second image forming surface (second side) of the recording material P, to a discharge path 139 when images are to be formed on both sides of the recording material P.

[0033] The flapper 133 is controlled by a control unit 151 on a control board 150 to switch the conveyance of the recording material P from the reversing unit 136 to a reversing path 137 .

[0034] The reversal sensor 135 detects the trailing edge in the conveying direction of the recording material P conveyed to the reversing section 136 by the fixing device 200, and outputs an electric signal according to the detection result to the control section 151 of the control board 150.

[0035] The control board 150 controls the overall operation of the image forming apparatus 100 based on an electrical signal input from the operation unit 180. The control board 150 includes a control unit 151 and a memory 152.

[0036] The control unit 151 controls the operation of the image forming apparatus 100 based on electrical signals input from a selection key 180b (described later) of the operation unit 180 and information data stored in the memory 152. The control unit 151 performs control to display the status of the image forming apparatus 100 on a display screen 180a of the operation unit 180. When the electrical signal input from the reversing sensor 135 indicates a detection result that the trailing edge of the recording material P in the conveying direction has been detected, the control unit 151 performs control to switch the flapper 133 so that the recording material P is conveyed from the reversing unit 136 to a reversing path 137. The control unit 151 writes the information data to the memory 152.

[0037] The memory 152 stores information data necessary for control by the control unit 151 .

[0038] The operation unit 180 includes a display screen 180a that displays the status of the image forming apparatus 100, and a selection key 180b that accepts operation instructions from an operator such as a user and outputs an electrical signal corresponding to the accepted instruction to the control board 150.

[0039] The fixing device 200 applies heat and pressure to the recording material P being conveyed by the secondary transfer roller 116, thereby fixing the toner image secondarily transferred onto the recording material P by the secondary transfer roller 116 to the recording material P. The fixing device 200 conveys the recording material P with the fixed toner image to a discharge path 139 and discharges it onto a discharge tray (not shown). The configuration of the fixing device 200 will be described in detail later.

[0040] In the image forming apparatus 100 having the above configuration, the process from charging the photosensitive drum 111 to discharging the recording material P with the fixed toner image is called an image forming process (print job). The image forming apparatus 100 is in the middle of an image forming process (print job) during the period when image formation is being performed.

[0041] The image forming apparatus 100 is not limited to full-color image formation, but can also form monochrome images. When monochrome image formation is performed, only the image forming unit 120d that forms a black toner image is driven.

[0042] <Configuration of fixing device> The configuration of the fixing device 200 according to the first embodiment of the present invention will be described in detail with reference to Fig. 2 to Fig. 4. The recording material P is transported to the left in Fig. 2. Here, the width direction perpendicular to the transport direction of the recording material P (hereinafter simply referred to as "width direction") is the direction perpendicular to the paper surface in Fig. 2, and is the left-right direction in Fig. 4.

[0043] 4 is a view of the fixing device 200 shown in FIG. 2 as seen from diagonally above to the right. In FIG. 4, the central portion of the steering roller 205 in the width direction is normally covered by the fixing belt 201, but for ease of explanation, the entire steering roller 205 is exposed from the fixing belt 201. In FIG. 4, the central portion of the heating roller 204 in the width direction is normally covered by the fixing belt 201, but for ease of explanation, the entire heating roller 204 is exposed from the fixing belt 201. In FIG. 4, the fixing belt 201, the heating roller 204, and the steering roller 205 rotate from the back to the front of the page.

[0044] The fixing device 200 includes a pressure roller 202 , a stay 206 , a heating unit 210 , a spring 211 , a steering frame 213 , and an oil recovery member 240 .

[0045] The pressure roller 202, which serves as a pressure rotating body, is a roller formed by laminating an elastic layer provided on the outer periphery of a shaft and a release layer provided on the outer periphery of the elastic layer. The shaft is made of stainless steel. The elastic layer is 5 mm thick and made of conductive silicone rubber. The release layer is 50 μm thick and made of PFA, a fluororesin.

[0046] The pressure roller 202 is rotatably supported by a fixing frame (not shown) of the fixing device 200. A gear (not shown) is fixed to one longitudinal end of the pressure roller 202, and the pressure roller 202 is connected to a drive source (not shown) via the gear. The pressure roller 202 is driven to rotate via the gear when driven by the drive source. The pressure roller 202 presses a pad member 203 via a fixing belt 201 (described later) of the heating unit 210, thereby forming a fixing nip N1.

[0047] Stay 206 is disposed inside fixing belt 201 of heating unit 210, and is provided on the opposite side of pad member 203 of heating unit 210 from the side where sliding sheet 207 is provided. Stay 206 is provided to back up pad member 203, and is a reinforcing member having rigidity with the width direction as the longitudinal direction.

[0048] The stay 206 prevents the pad member 203 from bending when the pad member 203 is pressed by the pressure roller 202, thereby ensuring the pressure at the fixing nip N1. The stay 206 is made of a 3 mm thick extruded SUS304 material, and is hollow inside and has a square cross section to ensure strength. The material of the stay 206 is not limited to stainless steel, and can be other materials as long as strength can be ensured.

[0049] The heating unit 210 includes a heat source and heats the recording material P in the fixing nip N1. The heating unit 210 includes a fixing belt 201, a pad member 203, a heating roller 204, a steering roller 205, a sliding sheet 207, an oil application roller 208, and a pressure spring 209.

[0050] The fixing belt 201 as a belt member has a three-layer structure including a base layer, an elastic layer covering the outer periphery of the base layer, and a release layer covering the outer periphery 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. The release layer is 30 μm thick and made of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin), a fluororesin.

[0051] Fixing belt 201 has thermal conductivity, heat resistance, etc., and is a thin-walled cylindrical shape with its width direction as the longitudinal direction. Fixing belt 201 is stretched by pad member 203, heating roller 204, and steering roller 205. Fixing belt 201 stores heat from heating roller 204 when heated by heating roller 204.

[0052] The fixing belt 201 is endless and rotatable, and is sandwiched between the pressure roller 202 and the pad member 203 at the fixing nip N1, so that when the pressure roller 202 rotates, the fixing belt 201 rotates in the direction B in FIG. 2. The fixing belt 201 has an outer peripheral surface 201c as a first surface that contacts the recording material P at the fixing nip N1, and an inner peripheral surface 201b as a second surface opposite the outer peripheral surface 201c. Oil S is applied to the inner peripheral surface 201b of the fixing belt 201 by an oil application roller 208. The force applied to the fixing belt 201 at the fixing nip N1 is illustrated as approximately 2000 N here.

[0053] The pad member 203, which serves as a nip forming member, is provided inside the fixing belt 201 and suspends the fixing belt 201. The pad member 203 is a member that comes into pressure contact with the pressure roller 202 via the fixing belt 201 to form a fixing nip portion N1 of a predetermined width in the conveyance direction of the recording material P. The pad member 203 has a substantially rectangular cross section, and is a member whose longitudinal direction is the width direction. The pad member 203 is made of a heat-resistant material, such as LCP (liquid crystal polymer) resin.

[0054] Heating roller 204 is a stainless steel pipe with a thickness of 1 mm and a longitudinal width. Heating roller 204 is equipped with a halogen heater (not shown) inside, and can generate heat up to a predetermined temperature by the halogen heater. Heating roller 204 is provided inside fixing belt 201 and suspends fixing belt 201.

[0055] The widthwise length of heating roller 204 is greater than the widthwise length of fixing belt 201. Widthwise end 204a of heating roller 204 is located outward in the widthwise direction from widthwise end 201a of fixing belt 201 (see FIG. 4). Note that the widthwise length of heating roller 204 does not necessarily have to be greater than the widthwise length of fixing belt 201, and may be the same length as the widthwise length of fixing belt 201.

[0056] The steering roller 205, which serves as a rotating member and a steering roller, has its longitudinal direction in the width direction, is provided inside the fixing belt 201 to suspend the fixing belt 201, and is rotatably supported by a steering frame 213. The steering roller 205 is biased toward the fixing belt 201 by a spring 211 supported by the steering frame 213, and also serves as a tension roller that applies a predetermined tension to the fixing belt 201. The steering roller 205 is biased toward the fixing belt 201 by the spring 211, and thus comes into contact with an inner peripheral surface 201b of the fixing belt 201.

[0057] The steering roller 205 rotates together with the steering frame 213 around a rotation shaft 212 whose axial direction is the conveyance direction of the recording material P, thereby performing a steering operation in which both end portions 205a in the width direction swing up and down (up and down in FIG. 2). That is, the steering roller 205 performs a steering operation in which it rotates around a central portion Q (see FIG. 4) in the width direction of the steering roller 205.

[0058] The steering roller 205 performs a steering operation to move the fixing belt 201 in the width direction. The length of the steering roller 205 in the width direction is greater than the length of the fixing belt 201 in the width direction and is the same as the length of the heating roller 204 in the width direction. An end 205a of the steering roller 205 is positioned outward of an end 201a of the fixing belt 201 in the width direction.

[0059] The widthwise length of steering roller 205 and the widthwise length of heating roller 204 do not have to be the same, but may be different. Also, the widthwise length of steering roller 205 does not have to be longer than the widthwise length of fixing belt 201, but may be the same as the widthwise length of fixing belt 201.

[0060] Sliding sheet 207 is provided between fixing belt 201 and pad member 203. Sliding sheet 207 is formed by coating the surface of a 70 μm thick polyimide base material with PTFE.

[0061] Oil application roller 208 is formed by impregnating a roll-shaped member wrapped with a 100 μm-thick nonwoven fabric with oil S, such as silicone oil, as a lubricant. Oil application roller 208 is supported by a frame (not shown) of heating unit 210 so as to be rotatable by the heating unit. Oil application roller 208 contacts inner circumferential surface 201b of fixing belt 201 and supplies oil S to inner circumferential surface 201b of fixing belt 201.

[0062] The pressure spring 209 biases the oil application roller 208 so that the oil application roller 208 contacts the inner peripheral surface 201b of the fixing belt 201. The contact force of the oil application roller 208 against the inner peripheral surface 201b of the fixing belt 201 is set to 3.0 N, for example, here.

[0063] The spring 211 is supported by a steering frame 213 and biases the steering roller 205 against the inner peripheral surface 201b of the fixing belt 201 so that the fixing belt 201 has a predetermined tension.

[0064] Steering frame 213 as a holding member rotates around pivot shaft 212 relative to the frame of heating unit 210, thereby changing the alignment of steering roller 205 with respect to the other suspension members. By changing the alignment of steering roller 205 with respect to the other suspension members, steering frame 213 generates a tension difference between one end and the other end of fixing belt 201 in the width direction, thereby controlling the position of fixing belt 201 in the width direction.

[0065] The oil recovery member 240 serving as the lubricant recovery member is a sheet member made of felted aramid fiber. The oil recovery member 240 has, for example, a length of 15 mm in the short direction (left-right direction in FIG. 2) and a length of 30 mm in the long direction (direction perpendicular to the paper surface in FIG. 2). The oil recovery member 240 is attached to a positioning member (not shown) fixed to the upper part of the steering frame 213.

[0066] The oil recovery member 240 is disposed opposite the inner circumferential surface 201b of the fixing belt 201. The oil recovery member 240 comes into contact with or moves away from the inner circumferential surface 201b of the fixing belt 201 depending on the rotation angle (hereinafter referred to as the "steering angle") in the width direction when the steering roller 205 rotates around the central portion Q in the width direction. Specifically, the oil recovery member 240 moves away from the inner circumferential surface 201b of the fixing belt 201 when the steering angle is less than a predetermined angle, and comes into contact with the inner circumferential surface 201b of the fixing belt 201 when the steering angle is equal to or greater than the predetermined angle.

[0067] A pair of oil collecting members 240 are provided at positions that straddle both end portions 201a of fixing belt 201 in the width direction. Note that oil collecting members 240 are not limited to a pair, and may be a single member that straddles both end portions 201a of fixing belt 201 in the width direction.

[0068] The oil recovery member 240 is provided so as to be able to come into contact with the fixing belt 201 in a contact region R2 between the start point P1s and the end point P1t. Here, the start point P1s is a position outside the fixing belt 201 in the width direction and corresponds to the end 204a of the heating roller 204. The end point P1t is a position closer to the center of the fixing belt 201 in the width direction than the end 201a of the fixing belt 201. Since the oil recovery member 240 is provided so as to be able to come into contact with the fixing belt 201 in the contact region R2, it is provided at a position that spans the movement range R1 in the width direction of each of the end portions 201a of the fixing belt 201.

[0069] In the fixing device 200 having the above-described configuration, oil S is used as a lubricant, but the present invention is not limited to this, and grease or the like may also be used as a lubricant.

[0070] Furthermore, the sliding sheet 207 is used to improve the sliding property between the pad member 203 and the fixing belt 201, but this is not limiting, and a coating or the like that improves sliding property may be applied to the surface layer of the pad member 203 that comes into contact with the fixing belt 201.

[0071] Furthermore, the heating roller 204 may be configured to be rotationally driven. In this case, by rotating the heating roller 204 at a rotation speed faster than the rotation speed of the pressure roller 202, it is possible to increase the tension of the fixing belt 201 from the fixing nip portion N1 to the heating roller 204 in the rotation direction of the fixing belt 201. This makes it possible to increase the curvature of the outlet of the fixing nip portion N1 in the rotation direction of the fixing belt 201, thereby improving the separation performance of the recording material P.

[0072] <Basic operation of the fixing device> The basic operation of the fixing device 200 according to the first embodiment of the present invention will be described in detail with reference to FIGS.

[0073] The heating roller 204 is controlled so that the fixing belt 201 reaches a predetermined target temperature according to the paper type, based on the temperature of the fixing device 200 detected by a thermistor (not shown), which indicates the temperature of the fixing device 200, as indicated by an electrical signal input from the thermistor to the control unit 151.

[0074] The fixing belt 201 is heated by a heating roller 204 .

[0075] Then, the recording material P bearing the unfixed toner image is given the heat and pressure necessary for fixing when it is nipped and conveyed between the pressure roller 202 and the heated fixing belt 201 in the fixing nip N1. As a result, the unfixed toner image on the recording material P is fixed to the recording material P. At this time, the fixing belt 201 can slide smoothly against the pad member 203 by interposing the sliding sheet 207 and oil S between the fixing belt 201 and the pad member 203.

[0076] Here, the oil S applied between the pad member 203 and the fixing 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 member 203 and the fixing belt 201 can no longer be retained, the sliding resistance between the pad member 203 and the fixing belt 201 increases, which may cause problems such as poor rotation of the fixing belt 201.

[0077] In contrast, by contacting the oil application roller 208 with the inner circumferential surface 201b of the fixing belt 201, it is possible to supply the oil S to the inner circumferential surface 201b of the fixing belt 201. This allows the oil S to be maintained between the fixing belt 201 and the pad member 203 (sliding sheet 207) for a longer period of time, thereby enabling the fixing device 200 to maintain stable operation.

[0078] Furthermore, when an unfixed toner image is fixed to the recording material P, greater stress is applied to the portion of the fixing belt 201 that comes into contact with the edge portion, which is the edge portion of the recording material P in the width direction, than to the portion of the fixing belt 201 that does not come into contact with the edge portion of the recording material P. The area of ​​the fixing belt 201 that the edge portion of the recording material P has repeatedly passed through becomes more recessed than the area of ​​the fixing belt 201 that does not come into contact with the edge portion of the recording material P. Such recesses in the fixing belt 201 caused by the edge portion of the recording material P are called paper edge scratches.

[0079] When pressure and heat are applied to the recording material P in the fixing device 200 to fix the unfixed toner image to the recording material P, the state of the fixing belt 201 is reflected in the gloss of the surface of the image fixed to the recording material P. If the fixing belt 201 has unevenness, the state of the unevenness of the fixing belt 201 is reflected in the gloss of the surface of the image fixed to the recording material P, resulting in gloss unevenness on the surface of the image fixed to the recording material P. Therefore, if the unfixed toner image is fixed to the recording material P with scratches on the edge of the fixing belt 201, gloss unevenness like a straight line will occur on the surface of the image fixed to the recording material P.

[0080] Therefore, in order to prevent scratches on the edge of the fixing belt 201, the fixing belt 201 is moved back and forth in the width direction by the steering roller 205. This reduces the number of times the recording material P passes the same position on the fixing belt 201 repeatedly, and prevents scratches on the edge of the fixing belt 201. In this way, the steering roller 205 also plays a role in preventing uneven gloss caused by the edge of the recording material P.

[0081] The widthwise position of fixing belt 201 is detected by a belt position detection unit (not shown). Specifically, the belt position detection unit has an arm that rotates around a rotation axis whose axis is perpendicular to the widthwise direction and the conveyance direction of fixing belt 201. The arm of the belt position detection unit rotates around the rotation axis, thereby applying a force to end 201a of fixing belt 201 in a direction from the outside to the inside.

[0082] The belt position detection unit detects the widthwise position of the arm that contacts the end 201a of the fixing belt 201 using a sensor such as a photointerrupter, and outputs an electrical signal according to the detection result to the control unit 151. This allows the control unit 151 to grasp the widthwise position of the fixing belt 201.

[0083] Based on the detection result indicated by the electrical signal input from the belt position detection unit, the control unit 151 performs steering control to cause the steering roller 205 to perform a steering operation of rotating and swinging around the rotation shaft 212. This makes it possible to prevent the fixing belt 201 from coming off the pad member 203, heating roller 204, and steering roller 205 that suspend the fixing belt 201. In addition, the fixing belt 201 can be moved in the width direction to prevent scratches on the edge.

[0084] <Oil recovery operation of the fixing device> The oil recovery operation of fixing device 200 according to the first embodiment of the present invention will be described in detail with reference to FIGS.

[0085] 7 and 8 are views of the fixing device 200 shown in Fig. 2 as viewed from diagonally above to the right. In Fig. 7 and 8, the central portion of the steering roller 205 in the width direction perpendicular to the conveying direction of the recording material P is normally covered by the fixing belt 201, but for the sake of convenience, the entire steering roller 205 is exposed from the fixing belt 201. In Fig. 7 and 8, the central portion of the heating roller 204 in the width direction perpendicular to the conveying direction of the recording material P is normally covered by the fixing belt 201, but for the sake of convenience, the entire heating roller 204 is exposed from the fixing belt 201.

[0086] The oil S applied to the inner circumferential surface 201b of the fixing belt 201 is subjected to a pressing force from the inner circumferential surface 201b in the fixing nip portion N1 due to the pressure generated by the pad member 203 and the pressure roller 202 in the fixing nip portion N1. As a result, if the oil recovery member 240 is not provided, the oil S is exposed at both ends 201a in the width direction of the fixing belt 201, at the end faces, or in areas outside both ends 201a.

[0087] The oil S exposed in the areas outside the both end portions 201a of the fixing belt 201 adheres to the end portions 204a of the heating roller 204 as the fixing belt 201 rotates.

[0088] The oil S adhering to the end 204a of the heating roller 204 may be adhered to the outer peripheral surface 201c of the fixing belt 201 when the fixing belt 201 moves back and forth in the width direction due to the steering operation of the steering roller 205.

[0089] 2, the oil S adhering to the outer peripheral surface 201c of the fixing belt 201 reaches the fixing nip portion N1. The oil S that has reached the fixing nip portion N1 adheres to the recording material P being conveyed to the fixing nip portion N1. In this case, the area of ​​the recording material P to which the oil S has adhered can result in poor fixing, where heat transfer is hindered and the toner does not melt sufficiently, or can result in image defects such as uneven gloss due to changes in glossiness caused by the oil S.

[0090] Furthermore, in the fixing device 200, in order to prevent scratches on the edge of the fixing belt 201, the fixing belt 201 is actively moved back and forth in the width direction by the steering roller 205, which promotes exposure of the oil S.

[0091] Here, an object that comes into contact with the roller and is transported has the characteristic of being transported in a direction perpendicular to the rotation axis of the roller. For example, when the state shown in FIG. 4, in which the direction of the rotation axis G of the steering roller 205 is parallel to the width direction, is changed to the state shown in FIG. 7, in which the left side of the steering roller 205 in FIG. 4 is lifted up, the fixing belt 201 can be moved to the left in FIG. 7. Also, when the state shown in FIG. 4, in which the axial direction of the steering roller 205 is parallel to the width direction, is changed to the state shown in FIG. 4, in which the right side of the steering roller 205 in FIG. 4 is lifted up with respect to the rotation axis 212, the fixing belt 201 can be moved to the right in FIG. 7.

[0092] At this time, the larger the steering angle θ1 (see FIG. 8) of steering roller 205, the greater the force moving fixing belt 201 in the width direction. Furthermore, the larger the steering angle θ1, the greater the speed at which fixing belt 201 moves in the width direction (hereinafter referred to as "shift speed"). As the shift speed of fixing belt 201 increases, the force sweeping oil S on the surface of heating roller 204 increases and the frequency of the sweeping increases, resulting in more oil S being exposed in the regions of both end portions 204a of heating roller 204.

[0093] Fig. 5 shows the results of checking the relationship between the shift speed and the amount of exposed oil for each steering angle θ1. In Fig. 5, the operating speed of the fixing device 200 was set to 630 mm / s with the pressure roller 202 pressing the pad member 203 in the fixing nip N1, and the temperature of the heating roller 204 was set to 190°C, and the roller was allowed to idle for one hour.

[0094] The steering angle θ1 was set to ±1.0°, ±1.5°, ±3.0°, and ±4.0°. Based on the detection results of an arm (not shown) that detects the position of the fixing belt 201 in the width direction, a steering operation was performed so that the fixing belt 201 would reciprocate by the maximum width within the movement range R1. The amount of exposed oil, shown on the vertical axis in Figure 5, represents the amount of oil exposed and dripping from the end of the fixing belt 201 per unit time when the fixing device 200 was running idle.

[0095] Here, the "+" of the steering angle θ1 is the steering angle θ1 when one end 205a of the steering roller 205 moves upward or downward. Also, the "-" of the steering angle θ1 is the steering angle θ1 when one end 205a of the steering roller 205 moves downward or upward.

[0096] From Figure 5, when the steering angle θ1 was ±1.0°, the leaning speed was 0.54 mm / s, and when the steering angle θ1 was ±4.0°, the leaning speed was 1.43 mm / s. This confirms that the leaning speed increases as the steering angle θ1 increases, and the amount of oil exposure increases accordingly.

[0097] Thus, steering is essential to prevent edge damage caused by the passage of the recording material P. However, aggressive steering can result in image defects due to adhesion of oil S to the recording material P. To address this issue, one possible solution is to abut an oil exposure restriction mechanism, which prevents oil S from adhering to the outer peripheral surface 201c of the fixing belt 201, against the inner peripheral surface 201b of the fixing belt 201. However, this can accelerate wear at the contact area between the oil exposure restriction mechanism and the fixing belt 201. Furthermore, excessive oil exposure restriction can hinder the original purpose of reducing sliding resistance of the oil S, resulting in problems such as poor rotation of the fixing belt 201.

[0098] To address the above-mentioned issues, the fixing device 200 of this embodiment can prevent the oil S from getting around the outer surface 201c of the fixing belt 201 while performing a steering operation, and can also prevent wear on the fixing belt 201.

[0099] Specifically, when image forming apparatus 100 is on standby after power-on and before receiving an image formation process (print job) command, as shown in Fig. 7, steering control is performed so that the direction of rotation axis G of steering roller 205 is approximately parallel to the width direction. This makes it possible to prevent fixing belt 201 from coming off the track. For example, when image forming apparatus 100 is on standby, as shown in Fig. 6, by setting steering angle θ1 to ±1.0, the deviation speed becomes 0.5 mm / s.

[0100] Also, 100g / m 2 When performing an image forming process (print job) on a recording material P that is less than this thickness, there is little risk of damaging the fixing belt 201 even if the edge of the recording material P repeatedly passes the same position on the fixing belt 201. Therefore, in this case as well, as shown in FIG. 7, steering control is performed so that the direction of the rotation axis G of the steering roller 205 is approximately parallel to the width direction.

[0101] When steering control is performed so that the direction of rotation axis G of steering roller 205 is approximately parallel to the width direction, steering angle θ1 is set to ±1.0 to 1.5° so that fixing belt 201 repeatedly moves within a narrow range in the width direction, and the deviation speed is 0.5 to 0.7 mm / s. In addition, end 201a of fixing belt 201 is located approximately in the center of movement range R1 in the width direction.

[0102] When the steering angle θ1 is set to ±1 to 1.5°, the oil recovery member 240 moves up and down by approximately 5 mm but does not come into contact with the inner circumferential surface 201b of the fixing belt 201. For example, when steering control is performed so that the direction of the rotation axis G of the steering roller 205 is approximately parallel to the width direction, the deviation speed becomes 0.7 mm / s by setting the steering angle θ1 to ±1.5°, as shown in FIG.

[0103] Next, 101g / m 2 When performing an image forming process (print job) on the above-described recording material P, it is necessary to prevent damage to the edge of the fixing belt 201. Therefore, in this case, as shown in Fig. 8, steering control is performed so that both end portions 201a of the fixing belt 201 reciprocate within the maximum movement range R1 so that the edge portions of the recording material P do not pass through the same position on the fixing belt 201.

[0104] When steering control is performed so that both end portions 201a of fixing belt 201 reciprocate within the maximum width movement range R1, the steering angle θ1 is set to ±4° and the deviation speed is 1.4 mm / s. For example, when steering control is performed so that both end portions 201a of fixing belt 201 reciprocate within the maximum width movement range R1, as shown in FIG. 6, the deviation speed is 1.4 mm / s by setting the steering angle θ1 to ±4.0°.

[0105] Thus, 101 g / m 2 When performing an image forming process (print job) on the above recording material P, the deviation speed is 100 g / m 2 The deviation speed is faster than the deviation speed when an image forming process (print job) is performed on the following recording material P.

[0106] When the steering angle θ1 is set to ±4°, the oil recovery member 240 moves approximately 12 mm up and down. As a result, the oil recovery member 240 on one end 205a side of the steering roller 205 moves in a direction in which the one end 205a side of the steering roller 205 approaches the fixing belt 201, and thus comes into contact with the inner circumferential surface 201b of the fixing belt 201.

[0107] On the other hand, the oil recovery member 240 on the other end 205a side of the steering roller 205 does not come into contact with the inner circumferential surface 201b of the fixing belt 201 because the other end 205a side of the steering roller 205 moves in a direction away from the fixing belt 201. As a result, the oil recovery member 240 on one end 205a side of the steering roller 205 recovers the oil S adhering to the inner circumferential surface 201b of the fixing belt 201 on one end 201a side.

[0108] Furthermore, the oil recovery member 240 on the other end 205a side of the steering roller 205 comes into contact with the inner circumferential surface 201b of the fixing belt 201 as the other end 205a side of the steering roller 205 moves in a direction approaching the fixing belt 201. On the other hand, the oil recovery member 240 on one end 205a side of the steering roller 205 does not come into contact with the inner circumferential surface 201b of the fixing belt 201 as the one end 205a side of the steering roller 205 moves in a direction away from the fixing belt 201. As a result, the oil recovery member 240 on the other end 205a side of the steering roller 205 recovers the oil S adhering to the inner circumferential surface 201b of the fixing belt 201 on the other end 201a side.

[0109] In this way, each of the oil recovery members 240 recovers the oil S from one end 201a of the fixing belt 201 through the steering action of the steering roller 205, and then recovers the oil S from the other end 201a of the fixing belt 201.

[0110] Figure 10 shows the results of confirming the relationship between the amount of oil S adhering to the outer surface 201c of the fixing belt 201 and the amount of wear on the inner surface 201b of the fixing belt 201 when the fixing device 200 is rotated idly with the pressure roller 202 pressing the pad member 203.

[0111] 10 shows fixing device 1200 having the configuration shown in FIG. 9 as a comparative example for comparison with fixing device 200 of the present embodiment. Comparative fixing device 1200 shown in FIG. 9 has a configuration in which pressing member 1250 constantly abuts oil recovery member 1240 against fixing belt 201. Oil recovery member 240 and oil recovery member 1240 are made of the same material and are attached to inner circumferential surface 201b of fixing belt 201 at approximately the same position in the width direction. Furthermore, the pressing pressure of oil recovery member 1240 of the comparative example against fixing belt 201 was changed, and the pressing pressure of oil recovery member 240 of the present embodiment against fixing belt 201 was set to approximately 7.0 N.

[0112] In addition, in Figure 10, the fixing device 200 and the comparative fixing device 1200 were operated at idling speed of 630 mm / s, the temperature control temperature of the heating roller 204 was set to 175°C, and a steering operation was performed so that the amount of movement of the fixing belt 201 in the width direction was maximized.

[0113] Under the above conditions, the relationship between the amount of oil S adhering to the outer surface 201c of the fixing belt 201 and the amount of wear on the inner surface 201b of the fixing belt 201 was confirmed 1 hour, 10 hours, and 20 hours after the start of idling operation.

[0114] 10, in the comparative example, when the contact pressure of oil recovery member 1240 against fixing belt 201 was set to 10.0 N, the amount of oil adhering to outer peripheral surface 201c of fixing belt 201 was able to be suppressed to 0.1 g or less even after 20 hours had passed. On the other hand, in the comparative example, inner peripheral surface 201b of fixing belt 201 was worn down by 10 μm.

[0115] Furthermore, in the comparative example, as the contact pressure of oil recovery member 1240 against fixing belt 201 was reduced to 3.0 N and then 1.5 N, the amount of wear on inner circumferential surface 201b of fixing belt 201 decreased, while the amount of oil adhering to outer circumferential surface 201c of fixing belt 201 increased. Thus, in the comparative example, there was a trade-off between the amount of wear on inner circumferential surface 201b of fixing belt 201 and the amount of oil adhering to outer circumferential surface 201c of fixing belt 201.

[0116] In contrast, in the present embodiment, even when the steering angle θ1 is large and the deviation speed is fast, which promotes the accumulation of oil S, it is possible to reduce the amount of oil adhering to the outer peripheral surface 201c of the fixing belt 201. Furthermore, in the present embodiment, one of the oil recovery members 240 facing both end portions 201a of the fixing belt 201 is not brought into contact with the inner peripheral surface 201b of the fixing belt 201, which also reduces wear on the inner peripheral surface 201b of the fixing belt 201. Note that in the present embodiment, when the steering angle θ1 is small and the deviation speed is slow, the accumulation of oil S is small, so the oil recovery member 240 is not brought into contact with the fixing belt 201, which further reduces wear on the inner peripheral surface 201b of the fixing belt 201.

[0117] In this way, in this embodiment, it is possible to suppress edge scratches due to the steering operation, and also to suppress a decrease in image quality due to oil S adhering to outer peripheral surface 201c of fixing belt 201. It is also possible to suppress a decrease in durability of fixing belt 201 due to contact with oil recovery member 240.

[0118] In this embodiment, the oil recovery member 240 is provided at a position spanning at least both end portions 201a in the width direction of the fixing belt 201. The oil recovery member 240 is disposed opposite the inner circumferential surface 201b of the fixing belt 201, and comes into contact with or separates from the inner circumferential surface 201b of the fixing belt 201 depending on the steering angle when the steering roller 205 rotates around the central portion Q in the width direction. This makes it possible to prevent the oil S from adhering to the outer circumferential surface 201c of the fixing belt 201, thereby preventing the oil S from adhering to the recording material P and suppressing a deterioration in image quality.

[0119] (Embodiment 2) The configuration of the image forming apparatus according to the second embodiment of the present invention is the same as that shown in FIG. 1, and therefore a description thereof will be omitted.

[0120] <Configuration of fixing device> The configuration of a fixing device 300 according to the second embodiment of the present invention will be described in detail with reference to Figures 11 to 13. The recording material P is conveyed in the left direction in Figure 11.

[0121] 11 to 13, parts having the same configuration as those in FIGS. 2 to 4 are designated by the same reference numerals, and their description will be omitted. FIG. 13 is a view of the fixing device 300 shown in FIG. 11, seen from diagonally above to the right. In FIG. 13, the central portion of the steering roller 205 in the width direction is normally covered by the fixing belt 201, but for the sake of convenience of explanation, the entire steering roller 205 is shown exposed from the fixing belt 201. Furthermore, in FIG. 13, the fixing belt 201 and the steering roller 205 rotate from the back side to the front side of the page.

[0122] The fixing device 300 includes a pressure roller 202 , a stay 206 , a heating unit 210 , a spring 211 , a steering frame 213 , and an oil recovery member 260 .

[0123] The oil collection member 260 is a rubber sheet member such as a fluororubber sheet. For example, the oil collection member 260 has a length of 15 mm in the short-side direction (left-right direction in FIG. 11) and a length of 30 mm in the long-side direction (direction perpendicular to the paper surface in FIG. 11). The oil collection member 260 includes a base portion 2601 and a protruding portion 2602. The base portion 2601 is attached to a positioning member (not shown) that is fixed to the upper part of the steering frame 213. The protruding portion 2602 protrudes upward from one end of the base portion 2601 in the short-side direction and faces the inner circumferential surface 201b of the fixing belt 201. The length of the protruding portion 2602 in the short-side direction is shorter than the length of the base portion 2601 in the short-side direction.

[0124] A pair of oil recovery members 260 are provided at positions that straddle both end portions 201a of fixing belt 201 in the width direction. Note that oil recovery members 260 are not limited to a pair, and may be a single member that straddles both end portions 201a of fixing belt 201 in the width direction.

[0125] The oil recovery member 260 is in contact with the fixing belt 201 in a contact region R3 between the start point P2s and the end point P2t. Here, the start point P2s is located outside the fixing belt 201 in the width direction and is located at the end 204a of the heating roller 204. The end point P2t is located closer to the center of the fixing belt 201 in the width direction than the end 201a of the fixing belt 201. The oil recovery member 260 is provided so as to be in contact with the fixing belt 201 in the contact region R3, and is therefore provided at a position that spans the movement range R1 in the width direction of each of the end portions 201a of the fixing belt 201.

[0126] The protrusion 2602 of the oil recovery member 260 is inclined more downstream in the rotation direction of the fixing belt 201 as it approaches the center in the width direction of the fixing belt 201, thereby forming a predetermined angle θ3 with respect to the width direction. The oil recovery member 260 is arranged so that the end 260a on the end point P2t side is more downstream in the rotation direction of the fixing belt 201 than the end 260b on the start point P2s side, thereby forming the predetermined angle θ3 with respect to the width direction. In this example, the predetermined angle θ3 is 10 degrees.

[0127] Although the starting point P2s is located at a position corresponding to the end 204a of the heating roller 204 in the width direction, it may be located outside the end 204a of the heating roller 204 in the width direction. In this case, the end 260b of the oil recovery member 260 is located outside the heating roller 204 in the width direction.

[0128] The oil recovery member 260 restricts the movement of the oil S from the inner circumferential surface 201b of the fixing belt 201 so that the oil S adhering to the inner circumferential surface 201b of the fixing belt 201 does not adhere to the outer circumferential surface 201c of the fixing belt 201.

[0129] In the fixing device 300 having the above configuration, oil S is used as a lubricant, but the lubricant is not limited to this, and grease or the like may also be used as a lubricant. Furthermore, the basic operation of the fixing device 300 is the same as the basic operation of the fixing device 200 described above, and therefore a description thereof will be omitted.

[0130] <Oil recovery operation of the fixing device> The oil recovery operation of the fixing device 300 according to the second embodiment of the present invention will be described in detail with reference to FIGS.

[0131] When the steering angle θ1 is set to ±1 to 1.5°, the oil recovery member 260 moves up and down by approximately ±5 mm, but does not come into contact with the inner circumferential surface 201b of the fixing belt 201. When the steering angle θ1 is set to ±4°, the oil recovery member 260 moves up and down by approximately ±12 mm.

[0132] When the steering angle θ1 is set to ±4°, the oil collection member 260 on the one end 205a side comes into contact with the inner circumferential surface 201b of the fixing belt 201 as the one end 205a side of the steering roller 205 moves in a direction approaching the fixing belt 201. On the other hand, the oil collection member 260 on the other end 205a side does not come into contact with the inner circumferential surface 201b of the fixing belt 201 as the other end 205a side of the steering roller 205 moves in a direction away from the fixing belt 201. As a result, the oil collection member 260 on the one end 205a side of the steering roller 205 collects the oil S adhering to the inner circumferential surface 201b of the fixing belt 201 on the one end 201a side.

[0133] Next, when the steering angle θ1 is set to ±4°, the oil recovery member 260 on the other end 205a side comes into contact with the inner circumferential surface 201b of the fixing belt 201 as the other end 205a side of the steering roller 205 moves in a direction approaching the fixing belt 201. On the other hand, the oil recovery member 260 on the one end 205a side does not come into contact with the inner circumferential surface 201b of the fixing belt 201 as the one end 205a side of the steering roller 205 moves in a direction away from the fixing belt 201. As a result, the oil recovery member 260 on the other end 205a side of the steering roller 205 recovers the oil S adhering to the inner circumferential surface 201b of the fixing belt 201 on the other end 201a side.

[0134] In this way, each of the oil recovery members 260 recovers the oil S from one end 201a of the fixing belt 201 through the steering action of the steering roller 205, and then recovers the oil S from the other end 201a of the fixing belt 201.

[0135] Furthermore, in the above operation, by providing oil recovery member 260 at a predetermined angle θ3 with respect to the width direction, oil S can be caused to flow from end 260b on the start point P2s side toward end 260a on the end point P2t side as fixing belt 201 rotates. This allows oil S adhering near end 201a of inner circumferential surface 201b of fixing belt 201 to flow toward the center of fixing belt 201 in the width direction, preventing oil S from accumulating near end 204a on the surface of heating roller 204.

[0136] Figure 15 shows the results of confirming the relationship between the amount of oil S adhering to the outer surface 201c of the fixing belt 201 and the amount of wear on the inner surface 201b of the fixing belt 201 when the fixing device 300 is rotated idly while the pressure roller 202 is pressing the pad member 203.

[0137] 15 shows fixing device 1300 having the configuration shown in FIG. 14 as a comparative example for comparison with fixing device 300 of the present embodiment. Comparative fixing device 1300 shown in FIG. 14 has a configuration in which pressing member 1250 constantly abuts oil collection member 1260 against fixing belt 201. Oil collection member 260 and oil collection member 1260 are made of the same material and have the same shape, and are also attached to inner circumferential surface 201b of fixing belt 201 at the same position in the width direction. Furthermore, the pressing pressure of oil collection member 1260 of the comparative example against fixing belt 201 was changed, and the pressing pressure of oil collection member 260 of the present embodiment against fixing belt 201 was set to approximately 7.0 N.

[0138] The other conditions were the same as those in Fig. 10. Under these conditions, the relationship between the amount of oil S adhering to outer peripheral surface 201c of fixing belt 201 and the amount of wear on inner peripheral surface 201b of fixing belt 201 was confirmed 1 hour, 10 hours, and 20 hours after the start of idling.

[0139] 15, in the comparative example, as in FIG. 10, there is a trade-off between the amount of wear on inner circumferential surface 201b of fixing belt 201 and the amount of oil adhering to outer circumferential surface 201c of fixing belt 201. In contrast, in the present embodiment, as in FIG. 10, even when the steering angle θ1 is large and the sweeping of oil S is accelerated at a high deviation speed, the amount of oil adhering to outer circumferential surface 201c of fixing belt 201 can be reduced. Furthermore, in the present embodiment, one of oil recovery members 260 facing both end portions 201a of fixing belt 201 is not brought into contact with inner circumferential surface 201b of fixing belt 201, so that wear on inner circumferential surface 201b of fixing belt 201 can also be reduced.

[0140] In this embodiment, when the steering angle θ1 is small and the shifting speed is low, the oil S is not swept up, so the oil recovery member 260 does not come into contact with the fixing belt 201, thereby further suppressing wear on the inner surface 201b of the fixing belt 201.

[0141] According to this embodiment, it is possible to suppress edge scratches caused by steering operations, suppress deterioration of image quality due to exposure of oil S to the outer surface 201c of the fixing belt 201, and suppress deterioration of durability of the fixing belt 201 due to contact with the oil recovery member 240.

[0142] In this embodiment, the oil recovery member 260 is provided at a position spanning at least both end portions 201a in the width direction of the fixing belt 201. The oil recovery member 260 is disposed opposite the inner circumferential surface 201b of the fixing belt 201, and comes into contact with or separates from the inner circumferential surface 201b of the fixing belt 201 depending on the steering angle when the steering roller 205 rotates around the central portion Q in the width direction. This makes it possible to prevent the oil S from adhering to the outer circumferential surface 201c of the fixing belt 201, thereby preventing the oil S from adhering to the recording material P and suppressing a deterioration in image quality.

[0143] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit and scope of the present invention.

[0144] Specifically, in the above-described first and second embodiments, the inner circumferential surface 201b of the fixing belt 201 is heated, but this is not limiting, and the outer circumferential surface 201c of the fixing belt 201 may be heated.

[0145] In addition, in the above-mentioned first and second embodiments, the fixing belt 201 is moved in the width direction, but this is not limited to this, and the fixing belt 201 may not be moved in the width direction when, for example, conveying the maximum size recording material P.

[0146] In the above-described first and second embodiments, the oil recovery member 240 is provided on the steering frame 213 that rotatably supports the steering roller 205. However, the present invention is not limited to this, and the oil recovery member may be provided on a member that rotatably supports a rotating member other than the steering roller 205 that rotates up and down around the center in the width direction. [Explanation of symbols]

[0147] 100 Image forming device 120a Image forming unit 120b Image forming section 120c Image forming section 120d Image forming unit 200 Fixing device 201 Fixing belt 201a End 201b Inner surface 201c Outer surface 202 Pressure roller 203 Pad material 204 Heating roller 204a End 205 Steering roller 205a End 207 Sliding Sheet 208 Oil application roller 210 Heating Unit 213 Steering frame 240 Oil recovery member 260 Oil recovery member 300 Fixing device

Claims

1. A fixing device that fixes a toner image on a recording material, a rotatable endless belt member having a first surface that contacts a recording material and a second surface opposite to the first surface and on which a lubricant is applied; a nip forming member provided inside the belt member; a pressure rotating member that applies pressure to the nip forming member via the belt member to form a fixing nip portion that sandwiches and conveys a recording material together with the belt member; a rotating member that contacts the second surface of the belt member and rotates around a center portion in a width direction perpendicular to a conveying direction of the recording material; a lubricant recovery member that is provided at a position spanning at least both end portions of the belt member in the width direction, that is disposed opposite the second surface of the belt member, and that abuts against or moves away from the second surface of the belt member depending on a rotation angle when the rotating member rotates around the central portion; A fixing device characterized by having:

2. The rotating member is a steering roller that rotates around the central portion to move the belt member in the width direction; 2. The fixing device according to claim 1, wherein the fixing device is a fixing device for fixing a toner image onto a recording medium.

3. The lubricant recovery member is The rotary member is rotatably held by a holding member that rotates together with the rotary member around the central portion.

3. The fixing device according to claim 1, wherein the fixing member is a fixing member having a fixing surface.

4. The belt member is It is movable in the width direction, The lubricant recovery member is the belt member is provided at a position spanning the movement range of each of the end portions of the belt member in the width direction, 3. The fixing device according to claim 1, wherein the fixing member is a fixing member having a fixing surface.

5. The lubricant recovery member is the width direction of the belt member is inclined toward the downstream side in the rotation direction of the rotating member as it approaches the center portion of the belt member in the width direction, 3. The fixing device according to claim 1, wherein the fixing member is a fixing member having a fixing surface.

6. a fixing device according to claim 1 or 2; an image forming means for forming a toner image on a recording material and conveying the recording material on which the toner image has been formed to the fixing device; An image forming apparatus comprising:

Images