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 has an oil regulating member 240 which abuts on the 204b part of the heat roller 204, is provided at a position across at least the 201a parts of both end parts of the fixing belt 201 in the cross direction orthogonal to the carrying direction of the recording material P, and inclines to the downstream side in the rotating direction of the heat roller 204 toward the center part of the fixing belt 201 in the cross direction.SELECTED DRAWING: Figure 4

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 rotatable rotating member having a third surface that contacts the second surface of the belt member, and a lubricant regulating member that contacts the third surface of the rotating member and is provided at a position that spans at least both end portions of the belt member in a width direction perpendicular to the direction of transport of the recording material, and that inclines downstream in the rotation direction of the rotating member as it approaches the center of the width direction of the belt 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 idling time and the amount of oil adhesion in the fixing device according to the first embodiment of the present invention. FIG. [Figure 6] FIG. 6 is a cross-sectional view of a fixing device according to a second embodiment of the present invention. [Figure 7] 10 is a schematic diagram of a part of a fixing device according to a second embodiment of the present invention. FIG. [Figure 8] 10 is a diagram showing the relationship between the idling time and the amount of oil adhesion of the 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] The fixing device 200 includes a pressure roller 202 , a stay 206 , a heating unit 210 , a spring 211 , a steering frame 213 , a recovery mechanism 220 , an oil regulating member 240 , and a steering mounting member 250 .

[0044] 4 is a view of the fixing device 200 as seen from the right side of FIG. 2. The central portion of the heating roller 204 in the width direction is covered by the fixing belt 201, but for ease of explanation, the portion of the fixing belt 201 that covers the heating roller 204 is omitted in FIG. 4. The fixing belt 201 is essentially a belt-like member as shown in FIG. 2, but in FIG. 4, it is depicted as a roller-like member for ease of explanation. In FIG. 4, positions other than the widthwise positions of the oil regulating member 240 relative to the fixing belt 201 and heating roller 204 are depicted differently from their actual positions for ease of explanation. Furthermore, in FIG. 4, the fixing belt 201 and heating roller 204 rotate from the back to the front of the paper.

[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 together with the fixing belt 201 to sandwich and transport the recording material P.

[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. Stay 206 prevents deflection of pad member 203 when pad member 203 is pressed by pressure roller 202, thereby ensuring the pressure at fixing nip N1.

[0048] The stay 206 is made of 3 mm thick SUS304 drawn material, and is hollow inside and has a square cross section to ensure strength. Note that 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, which serves as a rotating member, 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 fixes fixing belt 201 thereon. Heating roller 204 is a rotatable heating member that heats fixing belt 201. Surface 204b, which serves as a third surface of heating roller 204, abuts against inner circumferential surface 201b of 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 as 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. A surface 205b of the steering roller 205 abuts against an inner peripheral surface 201b of the fixing belt 201 as a result of the steering roller 205 being biased toward the fixing belt 201 by the spring 211.

[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 ends in the width direction swing up and down (up and down in FIG. 2). By performing the steering operation, the steering roller 205 swings so as to move the fixing belt 201 in the width direction.

[0058] The width of the steering roller 205 is greater than the width of the fixing belt 201 and is the same as the width of the heating roller 204. An end 205a of the steering roller 205 in the width direction 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 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 recovery mechanisms 220 are disposed at both widthwise ends of the fixing belt 201, and recover the oil S adhering to the outer circumferential surfaces 201c of the both end portions 201a of the fixing belt 201. The recovery mechanisms 220 include a scraping member 221, a dripping member 222, and a support member 223.

[0066] The scraping member 221 abuts against the end 201a of the fixing belt 201. The scraping member 221 is disposed between the heating roller 204 and the steering roller 205 in the rotation direction of the fixing belt 201. The scraping member 221 scrapes off the oil S adhering to the outer peripheral surface 201c of the fixing belt 201 near the end 201a.

[0067] Dripping member 222 drips oil S scraped off by scraping member 221. Dripping member 222 is disposed between heating roller 204 and steering roller 205 in the rotation direction of fixing belt 201.

[0068] The support member 223 supports the scraping member 221 so that the scraping member 221 can follow the reciprocating movement of the fixing belt 201 in the width direction.

[0069] The oil regulating member 240 serving as a lubricant regulating member is a sheet-like member such as a fluororubber sheet. The oil regulating member 240 is attached to a positioning member (not shown) that is fixed to the steering mounting member 250. The oil regulating member 240 abuts against the surface 204b of the heating roller 204.

[0070] A pair of oil regulating members 240 are provided at positions corresponding to positions that straddle both end portions 201a of the fixing belt 201 in the width direction. Note that the oil regulating members 240 are not limited to a pair, and may be a single member that straddles both end portions 201a of the fixing belt 201 in the width direction.

[0071] The oil regulating member 240 is in contact with the heating roller 204 in a contact region R2 between a start point P1s and an end point P1t. The start point P1s is located outside the fixing belt 201 in the width direction and is at the same position as the end 201a of the fixing roller 204. The end point P1t is located closer to the center of the fixing belt 201 in the width direction than the end 201a. The oil regulating member 240 is located so as to be in contact with the surface 204b of the heating roller 204 in the contact region R2, and is therefore located 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.

[0072] The oil regulating member 240 is inclined more downstream in the rotation direction of the heating roller 204 as it approaches the center in the width direction of the heating roller 204, thereby forming a predetermined angle θ1 with respect to the width direction. The oil regulating member 240 is arranged so that the end 240a on the end point P1t side is more downstream in the rotation direction of the heating roller 204 than the end 240b on the start point P1s side, thereby forming the predetermined angle θ1 with respect to the width direction. In this example, the predetermined angle θ1 is 10 degrees.

[0073] Although the starting point P1s is located at a position corresponding to the end 204a of the heating roller 204 in the width direction, the position is not limited to this and may be located outside the end 204a of the heating roller 204 in the width direction. In this case, the end 240b of the oil regulating member 240 is located outside the heating roller 204 in the width direction. It is preferable that the oil regulating member 240 abuts against the surface 204b at least up to the end 204a of the heating roller 204.

[0074] The oil regulating member 240 regulates the movement of the oil S from the heating roller 204 to the fixing belt 201 so that the oil S adhering to the surface 204 b of the heating roller 204 does not adhere to the outer peripheral surface 201 c of the fixing belt 201 .

[0075] The steering frame 213 is attached to the steering attachment member 250 so as to be able to swing up and down, and the oil regulating member 240 is attached to the steering attachment member 250 via a positioning member (not shown).

[0076] 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.

[0077] 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.

[0078] 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.

[0079] <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.

[0080] 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.

[0081] Furthermore, the fixing belt 201 is heated by the heating roller 204 while rotating.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] The widthwise position of the 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 the fixing belt 201. The arm of the belt position detection unit rotates around the rotation axis, thereby applying a force from the outside to the inside to the end 201a of the fixing belt 201 in the widthwise direction.

[0089] The belt position detection unit detects the widthwise position of the arm that contacts widthwise end 201a of fixing belt 201 using a sensor such as a photointerrupter, and outputs an electrical signal according to the detection result to control unit 151. This allows control unit 151 to grasp the widthwise position of fixing belt 201.

[0090] 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.

[0091] <Oil regulation operation of the fixing unit> The oil regulating operation of the fixing device 200 according to the first embodiment of the present invention will be described in detail with reference to FIGS.

[0092] At the fixing nip N1, a pressure is generated by the pad member 203 and the pressure roller 202, and therefore a force acts on the oil S applied to the inner circumferential surface 201b of the fixing belt 201, pushing the oil S out from the inner circumferential surface 201b of the fixing belt 201. As a result, the oil S is exposed to both end portions 201a of the fixing belt 201, the side surfaces, or areas outside the both end portions 201a.

[0093] The oil S exposed on the side surfaces or in the areas outside the both end portions 201a of the fixing belt 201 adheres to the surface 204b of the heating roller 204 near the end portions 204a as the fixing belt 201 rotates. The fixing belt 201 also moves back and forth in the width direction due to the steering action of the steering roller 205.

[0094] As a result, if the oil regulating member 240 is not provided, the oil S adhering near the end 204a of the surface 204b of the heating roller 204 may adhere to the outer surface 201c of the fixing belt 201 as the fixing belt 201 moves back and forth in the width direction.

[0095] 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.

[0096] Furthermore, in order to prevent scratches on the edge of the fixing belt 201, the fixing device 200 actively moves the fixing belt 201 back and forth in the width direction using the steering roller 205, which promotes the exposure of the oil S. Therefore, it is necessary to prevent the oil S from adhering to the area of ​​the fixing belt 201 that comes into contact with the recording material P.

[0097] In this embodiment, oil S adhering from inner circumferential surface 201b of fixing belt 201 to surface 204b of heating roller 204 is moved from end 240b to end 240a of oil regulating member 240, which is in contact with surface 204b at a predetermined angle θ1. This makes it possible to prevent oil S adhering from inner circumferential surface 201b of fixing belt 201 to surface 204b of heating roller 204 from flowing around to outer circumferential surface 201c of fixing belt 201.

[0098] 5 compares the amount of oil that has wound its way around and adhered to the outer peripheral surface 201c of the fixing belt 201 in a conventional fixing device that does not have the oil regulating member 240 and in the fixing device 200 of the present embodiment that has the oil regulating member 240. The amount of oil that has wound its way around and adhered to the outer peripheral surface 201c of the fixing belt 201 when the fixing device 200 is idling with the pressure roller 202 pressing the pad member 203.

[0099] The conditions for the idling of the fixing device 200 were that the operating speed of the fixing device 200 was 630 mm / s and the temperature of the heating roller 204 was set to 175° C. The amount of oil that had reached the outer peripheral surface 201c of the fixing belt 201 was also checked 1 hour, 3 hours, 5 hours, and 7 hours after the start of the idling.

[0100] From Figure 5, it can be seen that in the conventional case, as the idle rotation time increases, the oil S on the inner surface of the fixing belt gradually moves to the outer surface of the fixing belt and accumulates on the surface of the heating roller.

[0101] In contrast, the fixing device 200 of this embodiment can control the oil S that tends to accumulate near the end 204a of the surface 204b of the heating roller 204 by using the oil regulating member 240 so that it returns toward the center in the width direction. As a result, in the fixing device 200 of this embodiment, almost no oil S accumulates near the end 204a of the surface 204b of the heating roller 204. Therefore, even if the oil S is exposed to the outside of the end 201a of the fixing belt 201, the fixing device 200 of this embodiment can reduce the amount of oil S adhering to the outer peripheral surface 201c of the fixing belt 201 by using the oil regulating member 240.

[0102] In this way, by providing the oil regulating member 240 on the heating roller 204 that contacts the fixing belt 201, it is possible to prevent the oil S from getting around the outer peripheral surface 201c of the fixing belt 201, thereby preventing a decrease in image quality.

[0103] Furthermore, by bringing oil regulating member 240 into contact with at least end 204a of surface 204b of heating roller 204, fixing device 200 can direct oil S that tends to accumulate near end 204a to the center in the width direction of heating roller 204. This makes it possible to reliably prevent oil S that has adhered near end 204a of heating roller 204 from migrating to outer peripheral surface 201c of fixing belt 201.

[0104] Incidentally, a small amount of oil S adhering to the vicinity of the end 201 a of the outer peripheral surface 201 c of the fixing belt 201 is scraped off by the scraping member 221 of the recovery mechanism 220 and dripped by the dripping member 222 .

[0105] In this embodiment, the oil regulating member 240 is provided in contact with the surface 204b of the heating roller 204 and is positioned across at least both end portions 201a of the fixing belt 201 in the width direction. The oil regulating member 240 is inclined downstream in the rotation direction of the heating roller 204 as it approaches the center of the fixing belt 201 in the width direction. This makes it possible to prevent the oil S from adhering to the surface of the fixing belt 201 that comes into contact with the recording material P, thereby preventing the oil S from adhering to the recording material P and suppressing a deterioration in image quality.

[0106] In this embodiment, a fluororubber sheet is used as the oil regulating member 240, but the oil regulating member 240 is not limited to this, and materials other than a fluororubber sheet may be used as the oil regulating member 240.

[0107] Furthermore, in this embodiment, the contact position of the oil regulating member 240 with the heating roller 204 can be set to any position.

[0108] In addition, in this embodiment, the angle of the oil regulating member 240 relative to the width direction is set to 10 degrees, but this is not limiting, and the angle of the oil regulating member 240 relative to the width direction can be set to an angle other than 10 degrees.

[0109] (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.

[0110] <Configuration of fixing device> The configuration of a fixing device 300 according to a second embodiment of the present invention will be described in detail with reference to Figures 6 and 7. The recording material P is conveyed to the left in Figure 6. In Figures 6 and 7, the same components as those in Figures 2 and 4 are designated by the same reference numerals, and their description will be omitted.

[0111] The fixing device 300 includes a pressure roller 202 , a stay 206 , a heating unit 210 , a spring 211 , a steering frame 213 , an oil regulating member 240 , a steering mounting member 250 , and an oil regulating member 301 .

[0112] 7 is a view of the fixing device 300 as seen from the right side of FIG. 6. Although the central portion of the steering roller 205 in the width direction is covered by the fixing belt 201, the portion of the fixing belt 201 that covers the steering roller 205 is omitted in FIG. 7 for ease of explanation. Similarly to FIG. 4, the fixing belt 201 is depicted as a roller-shaped member in FIG. 7 for ease of explanation. In FIG. 7, positions other than the width direction positions of the oil regulating member 301 relative to the fixing belt 201 and the steering roller 205 are depicted differently from their actual positions for ease of explanation. Furthermore, in FIG. 7, the fixing belt 201 and the steering roller 205 rotate from the back to the front of the paper.

[0113] The oil regulating member 301 serving as a lubricant regulating member is a sheet-like member such as a fluororubber sheet. The oil regulating member 301 is attached to the steering frame 213. The oil regulating member 301 abuts against the surface 205b of the steering roller 205.

[0114] A pair of oil regulating members 301 are provided at positions corresponding to positions that straddle both end portions 201a of the fixing belt 201 in the width direction. Note that the oil regulating members 301 are not limited to a pair, and may be a single member that straddles both end portions 201a of the fixing belt 201 in the width direction.

[0115] The oil regulating member 301 is in contact with the surface 205b, which serves as the third surface of the steering roller 205, which serves as a rotating member, in a contact region R3 between the start point P2s and the end point P2t. The start point P2s is located on the outer side of the fixing belt 201 in the width direction and is at the same position as the end point 205a of the steering roller 205. The end point P2t is located closer to the center of the fixing belt 201 than the end point 201a in the width direction.

[0116] The oil regulating member 301 is inclined more downstream in the rotation direction of the steering roller 205 as it approaches the center in the width direction of the steering roller 205, thereby forming a predetermined angle θ2 with respect to the width direction. The oil regulating member 301 is disposed so that its end 301a on the end point P2t side is more downstream in the rotation direction of the steering roller 205 than its end 301b on the start point P2s side, thereby forming the predetermined angle θ2 with respect to the width direction. In this example, the predetermined angle θ2 is set to 10 degrees.

[0117] Although the start point P2s is located at a position corresponding to the end 205a of the steering roller 205 in the width direction, the start point P2s may be located outside the end 205a of the steering roller 205 in the width direction. In this case, the end 301b of the oil regulating member 301 is located outside the steering roller 205 in the width direction. It is preferable that the oil regulating member 301 abuts against the surface 205b at least up to the end 205a of the steering roller 205.

[0118] The oil regulating member 301 regulates the movement of the oil S from the steering roller 205 to the fixing belt 201 so that the oil S adhering to the steering roller 205 does not adhere to the outer peripheral surface 201 c of the fixing belt 201 .

[0119] The basic operation of the fixing device 300 is the same as the basic operation of the fixing device 200 of the first embodiment, and therefore the description thereof will be omitted.

[0120] <Oil regulation operation of the fixing unit> The oil regulating operation of the fixing device 200 according to the second embodiment of the present invention will be described in detail with reference to FIGS.

[0121] As the fixing belt 201 rotates, the oil S exposed on the side surfaces or in the regions outside the both end portions 201a of the fixing belt 201 adheres to the vicinity of the end portion 205a of the steering roller 205 in addition to the vicinity of the end portion 204a of the surface 204b of the heating roller 204. The fixing belt 201 also moves back and forth in the width direction due to the steering operation of the steering roller 205.

[0122] As a result, if the oil regulating member 301 is not provided, the oil S adhering near the end 205a of the steering roller 205 may end up adhering to the outer surface 201c of the fixing belt 201 as the fixing belt 201 moves back and forth in the width direction.

[0123] 6, 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.

[0124] Furthermore, in order to prevent scratches on the edge of the fixing belt 201, the fixing device 300 actively moves the fixing belt 201 back and forth in the width direction using the steering roller 205, which promotes the exposure of the oil S. Therefore, it is necessary to prevent the oil S from adhering to the area of ​​the fixing belt 201 that comes into contact with the recording material P.

[0125] In this embodiment, oil S adhering to steering roller 205 from inner circumferential surface 201b of fixing belt 201 is moved from end 301b to end 301a of oil regulating member 301, which is in contact with steering roller 205 at a predetermined angle θ2. This makes it possible to prevent oil S adhering to steering roller 205 from inner circumferential surface 201b of fixing belt 201 from flowing around to outer circumferential surface 201c of fixing belt 201.

[0126] 8 compares the amount of oil that wraps around and adheres to the outer peripheral surface 201c of the fixing belt 201 in a conventional fixing device that does not have the oil regulating member 301 and in the fixing device 300 of the present embodiment that has the oil regulating member 301. Note that in FIG. 8, the fixing device 300 is operated under the same conditions as in FIG. 5.

[0127] From Figure 8, it can be seen that in the conventional case, as the idle rotation time increases, the oil S on the inner surface of the fixing belt gradually moves to the outer surface of the fixing belt and accumulates on the surface of the steering roller.

[0128] In contrast, the fixing device 300 of the present embodiment can control the oil S that tends to accumulate near the end 205a of the surface 205b of the steering roller 205 so that it returns toward the center in the width direction. As a result, in the fixing device 300 of the present embodiment, almost no oil S accumulates near the end 205a of the surface 205b of the steering roller 205. Therefore, even if the oil S is exposed in the outer region of the fixing belt 201, the fixing device 300 of the present embodiment can reduce the amount of oil S adhering to the outer peripheral surface 201c of the fixing belt 201 by the oil regulating member 301.

[0129] In this way, by providing the oil regulating member 301 on the steering roller 205 that contacts the fixing belt 201, it is possible to prevent the oil S from getting around to the outer peripheral surface 201c of the fixing belt 201, thereby preventing a decrease in image quality.

[0130] In the fixing device 300, the oil regulating member 301 is brought into contact with at least the end 205a of the surface 205b of the steering roller 205, so that the oil S that tends to accumulate near the end 205a can be made to flow to the central portion in the width direction of the steering roller 205. This makes it possible to reliably prevent the oil S that has adhered near the end 205a of the steering roller 205 from moving to the outer peripheral surface 201c of the fixing belt 201.

[0131] The oil regulating operation by the oil regulating member 240 of the fixing device 300 according to this embodiment is the same as the oil regulating operation of the fixing device 200, and therefore a description thereof will be omitted.

[0132] In this embodiment, the oil regulating member 301 is provided in contact with the surface 205b of the steering roller 205 and is positioned across at least both end portions 201a of the fixing belt 201 in the width direction. The oil regulating member 301 is inclined downstream in the rotation direction of the steering roller as it approaches the center of the fixing belt 201 in the width direction. This makes it possible to prevent the oil S from adhering to the surface of the fixing belt 201 that is in contact with the recording material P, thereby preventing the oil S from adhering to the recording material P and suppressing a deterioration in image quality.

[0133] In this embodiment, a fluororubber sheet is used as the oil regulating member 301, but the oil regulating member 301 is not limited to this, and materials other than a fluororubber sheet may be used as the oil regulating member 301.

[0134] In this embodiment, the contact position of the oil regulating member 301 with the steering roller 205 can be set to any position.

[0135] In addition, in this embodiment, the angle of the oil regulating member 301 relative to the width direction is set to 10 degrees, but this is not limiting, and the angle of the oil regulating member 301 relative to the width direction can be set to an angle other than 10 degrees.

[0136] In addition, in this embodiment, the starting point of the oil regulating member 301 is located at the end 205a of the steering roller 205, but this is not limited to this, and the starting point of the oil regulating member 240 may be located outside the end 205a of the steering roller 205 in the width direction.

[0137] 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.

[0138] Specifically, in the above-described first and second embodiments, the oil regulating member 240 or the oil regulating member 301 is provided in contact with the heating roller 204 or the steering roller 205. However, the present invention is not limited to this, and the oil regulating member may be provided on a rotating member other than the heating roller 204 and the steering roller 205 that are provided inside the fixing belt 201 and in contact with the inner circumferential surface 201b of the fixing belt 201.

[0139] Furthermore, in the above-described first and second embodiments, the inner circumferential surface 201b of the fixing belt 201 is heated, but the present invention is not limited to this, and the outer circumferential surface 201c of the fixing belt 201 may be heated.

[0140] 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. [Explanation of symbols]

[0141] 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 204b surface 205 Steering roller 205a End 205b surface 207 Sliding Sheet 208 Oil application roller 210 Heating Unit 213 Steering frame 240 Oil control member 300 Fixing device 301 Oil control member

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 rotatable member having a third surface that abuts the second surface of the belt member; a lubricant regulating member that abuts against the third surface of the rotating member, that is provided at a position that straddles at least both end portions of the belt member in a width direction perpendicular to the recording material conveying direction, and that is inclined downstream in the rotation direction of the rotating member as it approaches the center portion of the belt member in the width direction; A fixing device comprising:

2. The rotating member is a heating member that heats the belt member; 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 rotating member is a steering roller that oscillates 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.

4. The belt member is It is movable in the width direction, The lubricant regulating 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, 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.

5. The lubricant is It is oil, 5. The fixing device according to claim 1, wherein the fixing member is a fixing member having a fixing surface.

6. The lubricant regulating member is the third surface of the rotary member is in contact with at least the end of the rotary member in the width direction; 5. The fixing device according to claim 1, wherein the fixing member is a fixing member.

7. The fixing device according to any one of claims 1 to 4, 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