Fixation device and image forming apparatus

Abstract

To solve the problem of reduction in the durability of an annular belt in the case of providing a cleaning roller for cleaning the annular belt in order to suppress stains on the annular belt.SOLUTION: A fixation device includes: a fixation belt 104; guide members 111 including a regulation part 112 provided opposite the ends of the belt for regulating the ends of the fixation belt 104, and a guide surface 114 supporting an inner peripheral surface of the fixation belt 104; a cleaning roller 121 which makes contact with an outer peripheral surface of the fixation belt 104; and an opposing member 123 provided between a pair of the guide members 111 and facing the cleaning roller 121 across the fixation belt 104 at a position at which the fixation belt 104 makes contact with the cleaning roller 121. When the cleaning roller 121 is viewed from an axial direction, a first distance d1 from the axial center of the cleaning roller 121 to the opposing member 123 is the same as or smaller than a second distance d2 also from the axial center to the guide surface 114.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fixing device of an image forming apparatus, and more particularly to the configuration of a fixing device equipped with a circular belt. [Background technology]

[0002] BACKGROUND ART Conventionally, a fixing device has been known in which an end of a circular belt is rotatably supported by a flange member (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-56822 A (page 7, Figures 4 and 5) Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a cleaning roller is further provided to clean the circular belt in order to prevent the circular belt from becoming dirty, a decrease in the durability of the circular belt becomes a problem. An object of the present invention is to provide a fixing device that can prevent a decrease in the durability of the circular belt even when a cleaning roller for cleaning the circular belt is added. [Means for solving the problem]

[0005] The fixing device according to the present invention comprises: a pair of flange members provided opposite both ends of the circular belt and including flange portions for restricting the ends of the circular belt and support surfaces for supporting the inner peripheral surface of the circular belt; a cleaning roller that contacts the outer peripheral surface of the circular belt; and an opposing member provided between the pair of flange members and facing the cleaning roller across the circular belt at a position where the circular belt and the cleaning roller contact each other, When viewed in the axial direction of the cleaning roller, a first distance from the axial center of the cleaning roller to the opposing member is equal to or smaller than a second distance from the axial center of the cleaning roller to the support surface. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a fixing device that can prevent a decrease in the durability of the circular belt even when a cleaning roller for cleaning the circular belt is added. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing a configuration of a main part of an image forming apparatus according to a first embodiment of the present invention; [Figure 2] 1 is a diagram showing the configuration of a main part of a fixing device according to a first embodiment of the present invention; [Figure 3] FIG. 2 is a perspective view of the fixing belt unit as seen obliquely from above. [Figure 4] 4 is a cross-sectional view of a main part of the fixing belt unit shown in FIG. 3, taken at the center in the longitudinal direction (arrow Y direction) of the fixing belt unit, as viewed from the left side. [Figure 5] 10A and 10B are diagrams showing the configuration of the right guide member 111R alone, in which (a) is a rear view and (b) is an external perspective view seen from diagonally above. [Figure 6] 5 is a diagram illustrating the configuration of the opposing member shown in FIG. 4 and the positional relationship between the right guide member and the heater unit. FIG. [Figure 7] 7 is a diagram showing the configuration of both ends of the fixing belt unit as seen from approximately above, and therefore the fixing belt and its center are omitted from FIG. [Figure 8] FIG. 8 is a partially enlarged view of the periphery of the right guide member shown in FIG. 7. [Figure 9] This figure is used to explain the positional relationship between the opposing member, the right guide member, and the cleaning roller, where (a) is a schematic diagram of the main parts as seen from the left side of the longitudinal direction of the fixing belt unit, and (b) is an oblique view as seen from diagonally above. [Figure 10]10A and 10B are diagrams showing the configuration of the right guide member alone employed in the fixing device of embodiment 2 based on the present invention, in which (a) is an oblique view of the exterior, and (b) is a schematic diagram of the main parts viewed from the positive side of the arrow Y direction, with the right guide member, heater unit, cleaning roller, and opposing member each arranged in their predetermined positions. [Figure 11] FIG. 11 is a perspective view of the components in the state shown in FIG. 10(b) as seen obliquely from above. DETAILED DESCRIPTION OF THE INVENTION

[0008] Embodiment 1 FIG. 1 is a diagram showing the configuration of a main part of an image forming apparatus 11 according to a first embodiment of the present invention.

[0009] Image forming device 11 has a configuration as, for example, an electrophotographic, direct transfer color printer, and four independent image forming units 12C, 12M, 12Y, and 12K (sometimes referred to as image forming units 12 when no particular distinction is required) are detachably arranged in order from the upstream side along the conveyance direction (direction of arrow A) of recording paper 22. Image forming unit 12C forms a cyan (C) image, image forming unit 12M forms a magenta (M) image, image forming unit 12Y forms a yellow (Y) image, and image forming unit 12K forms a black (K) image.

[0010] In this embodiment, the configurations of these image forming units 12C, 12M, 12Y, and 12K are identical, and only the color of the toner contained therein differs. Therefore, the internal structure of the cyan (C) image forming unit 12C will be described below as an example.

[0011] The image forming unit 12C includes a photosensitive drum 13C (sometimes simply referred to as photosensitive drum 13 when there is no need to distinguish between them), a charging roller 14C (sometimes simply referred to as charging roller 14 when there is no need to distinguish between them) that uniformly charges the surface of the photosensitive drum 13C, and a developing device 16C (sometimes simply referred to as developing device 16 when there is no need to distinguish between them) that forms a toner image by adhering cyan toner to the electrostatic latent image formed on the surface of the photosensitive drum 13C.

[0012] An exposure head 15C (sometimes simply referred to as exposure head 15 when no particular distinction is required) is disposed above photoreceptor drum 13C in a position facing photoreceptor drum 13C. Similarly, corresponding exposure heads 15M, 15Y, and 15K are disposed for the other photoreceptor drums 13M, 13Y, and 13K, respectively. The exposure heads 15 selectively expose the photoreceptor drum 13 to light in accordance with image data for the corresponding color, forming an electrostatic latent image on the surface.

[0013] A transfer unit 21 is disposed below each photosensitive drum 13 of the four image forming units 12. The transfer unit 21 includes transfer rollers 17C, 17M, 17Y, and 17K (which may be simply referred to as transfer rollers 17 when no particular distinction is required), and a transfer belt 20 that is stretched and arranged to be able to run in the direction of arrow A in FIG.

[0014] Each transfer roller 17 is positioned in pressure contact with the corresponding photosensitive drum 13 via the transfer belt 20, and in the nip formed by the pressure, the recording paper 22 transported by the transfer belt 20 is charged to a polarity opposite to that of the toner, and the toner images of each color formed on the corresponding photosensitive drum 13 are transferred sequentially onto the recording paper 22 in layers.

[0015] A paper feed mechanism for feeding recording paper 22 to transfer belt 20 is disposed below transfer unit 21 of image forming device 11. The paper feed mechanism includes a support plate 35 on which recording paper 22 is placed, a hopping roller 24 that picks up recording paper 22 and discharges it onto paper transport path 45, a biasing spring 36 that presses support plate 35 to press the top of recording paper 22 placed on support plate 35 against hopping roller 24, a first transport roller pair 25 and a second transport roller pair 26 that transport the picked-up recording paper 22 along paper transport path 45 to transfer belt 20, etc.

[0016] A fixing device 40 is provided on the discharge side of the recording paper 22 from the transfer belt 20. The fixing device 40 has a fixing belt unit 41 and a pressure roller 42, and fixes the toner transferred onto the recording paper 22 by applying heat and pressure. On the discharge side of the fixing device 40, a pair of discharge rollers 27, 28 are arranged along a paper transport path 45, and the printed recording paper 22 discharged from the fixing device 40 is discharged along the paper transport path 45 to a paper stacker unit 46. The fixing device 40 will be described in detail later.

[0017] The photosensitive drum 13, hopping roller 24, first conveying roller pair 25, second conveying roller pair 26, transfer belt drive roller 18, and discharge roller pair 27, 28 are rotated by a drive means including a motor or the like.

[0018] 1, the X-, Y-, and Z-directions are defined as the conveyance direction (direction of arrow A) of the recording paper 22 as it passes through the image forming units 12C, 12M, 12Y, and 12K, the Y-direction is the direction of the rotation axis of each photosensitive drum 13, and the Z-direction is the direction perpendicular to both of these directions. Furthermore, when the X-, Y-, and Z-directions are shown in other figures described later, these directions refer to the same directions. That is, the X-, Y-, and Z-directions in each figure indicate the arrangement direction when the depicted parts of each figure constitute the image forming apparatus 11 shown in FIG. 1. Here, the Z-direction is assumed to be approximately vertical.

[0019] 2 is a diagram showing the essential configuration of fixing device 40 according to the first embodiment of the present invention, and Fig. 3 is an external perspective view of fixing belt unit 41 seen from diagonally above. Note that when viewed from the direction of arrow A (Fig. 1), which is the conveying direction of recording paper 22 by transfer belt 20, top (positive direction of the Z axis), bottom, left, right, front, and rear may be specified.

[0020] As shown in these figures, fixing device 40 is configured such that a pressure roller 42 serving as a rotating member and a fixing belt unit 41 positioned above the pressure roller 42 and equipped with a fixing belt 104 serving as an endless circular belt, both extend in the Y direction. Inside fixing belt unit 41, heater unit 105 extending in the Y direction and heating fixing belt 104 from the inside, is disposed. The Y direction in which fixing belt unit 41 extends may also be referred to as the longitudinal direction or the width direction of recording paper 22.

[0021] The pressure roller 42 has both ends of its rotation shaft 42a rotatably supported by a right side plate 101R and a left side plate 101L (not shown) disposed symmetrically thereto of the frame 100 of the fixing device 40, and is driven to rotate in the direction of the arrow (counterclockwise) by an external rotational driving force. The frame 100 integrally includes the right side plate 101R and the left side plate 101L (not shown), and holds components of the fixing device 40, such as the pressure roller 42 and fixing belt unit 41, in predetermined positions.

[0022] The heater unit 105 has a flat portion 105a at its bottom that transfers heat to the fixing belt 104, and is disposed so as to be in pressure contact with the elastic peripheral surface of the pressure roller 42 via the fixing belt 104, forming a nip portion 150. When the pressure roller 42 rotates in the direction of the arrow in this state, the fixing belt 104 also rotates together.

[0023] At this time, the left and right ends of the fixing belt 104 are guided by left and right belt guide means (flange members) as described below, and the fixing belt 104 rotates clockwise following the rotation of the pressure roller 42. Note that the movement of the fixing belt 104 rotating on its own axis while moving at this time may be referred to as rotational movement.

[0024] As described above, the recording paper 22 after transfer passes through the nip portion 150 in the direction of the dotted arrow B, and the transferred toner image is fixed by the heat and pressure treatment that the recording paper 22 receives while passing through the nip portion 150, and the recording paper 22 is then discharged from the fixing device 40.

[0025] Next, the configuration of the fixing belt unit 41 that rotatably supports the fixing belt 104 and disposes the heater unit 105 inside the fixing belt 104 will be further described.

[0026] 4 is a cross-sectional view of the fixing belt unit 41 shown in FIG. 3, taken at the center in the longitudinal direction (direction of arrow Y), as viewed from the left side. The figure also shows the pressure roller 42 when cut at the same position.

[0027] 4, the fixing belt unit 41 has a right rotation shaft hole 110R formed at the lower end of the right support lever 103R, into which the right rotation fulcrum 107R (FIG. 2) of the right side plate 101R fits, so that the fixing belt unit 41 is rotatably held by the right side plate 101R.

[0028] As will be described later, the right support lever 103R also includes a right guide member 111R that rotatably supports the right end of the fixing belt 104, and further fixedly supports the right end of the heater unit 105 that is disposed inside the fixing belt 104. Therefore, the right support lever 103R, the right guide member 111R, and the right end of the heater unit 105 are integrally configured.

[0029] 5A and 5B are diagrams showing the configuration of the right guide member 111R alone, in which FIG. 5A is a rear view and FIG. 5B is a perspective view of the exterior as seen from diagonally above.

[0030] As shown in these figures, the right guide member 111R as a flange member has an outer peripheral surface formed in a substantially arc-shaped cross section, and is located inside the right end portion of the fixing belt 104 as shown in FIG. 4. It is equipped with an inner guide portion 113R that guides the inside of the fixing belt 104, and a right regulating portion 112R as a flange portion that abuts against the right end portion of the fixing belt 104 and regulates its movement in the right direction (-Y direction).

[0031] Fig. 6 is a diagram illustrating the configuration of the opposing member 123 shown in Fig. 4 and its positional relationship with the right guide member 111R and heater unit 105, and Fig. 7 is a diagram illustrating the configuration of both ends of the fixing belt unit 41 viewed from approximately above. For this reason, Fig. 7 omits the fixing belt 104 and its central portion. Fig. 8 is a partially enlarged view of the periphery of the right guide member 111R shown in Fig. 7, but the differences between them are somewhat exaggerated to clarify the relative positional relationships between the cleaning roller 121, opposing member 123, and the right end portions of the right guide member 111R.

[0032] As shown in these figures, the opposing member 123 is attached to the outer casing of the heater unit 105, which extends longitudinally inside the fixing belt 104, and consists of an attachment portion 123a facing the top surface of this outer casing, and a guide portion 123b that continues from the top surface to the back surface and faces the mounting portion 123a, and is formed with a width that covers the area through which the recording paper 22 passes.

[0033] When viewed from the longitudinal direction (Y direction), as shown in Figure 6, the surface of this guide portion 123b has a belt sliding surface 123c which is formed approximately flush with the guide surface 114R as a support surface with an approximately arc-shaped cross section of the inner guide portion 113R of the right guide member 111R and serves as a contact surface against which the fixing belt 104 slides, and a belt introduction surface 123d which is formed continuously with the belt sliding surface 123c and is recessed inward so as to be away from the fixing belt 104.

[0034] As shown in FIGS. 2, 3, 4, etc., the fixing belt unit 41 further includes a cleaning roller 121 and a refreshing roller 122.

[0035] As shown in FIG. 8, the right end of the rotating shaft 121a of the cleaning roller 121 is rotatably held by a right bearing 126R held by a right bearing holding member 125R, and the right end of the rotating shaft 122a of the refreshing roller 122 is rotatably held by a right bearing 127R also held by the right bearing holding member 125R.

[0036] The right support lever 103R, right guide member 111R, right bearing holding member 125R, and right end portions of the heater unit 105 and opposing member 123, including the right side plate 101R, are configured in the same manner as the left end portion of the fixing belt unit 41. That is, these are formed substantially symmetrically with respect to an imaginary center plane that intersects perpendicularly at the center of the fixing belt unit 41 in the longitudinal direction (Y direction) excluding the electrical connector connection portion 160 (FIG. 3).

[0037] Furthermore, to distinguish between left and right, the reference numerals of components arranged symmetrically at the left and right ends are suffixed with (L) and (R), for example, left support lever 103L and right support lever 103R, but when no particular distinction is required, these suffixes may be omitted and the component may be referred to as support lever 103. Furthermore, for the components arranged symmetrically at the left and right ends of fixing belt unit 41, the configuration of the right end will mainly be described, and the left end will also be mentioned as necessary.

[0038] The right bearing holding member 125R (FIG. 8) has a pair of right bearings whose distance is determined so that the cleaning roller 121 and the refreshing roller 122 come into contact with each other and form a predetermined nip portion as shown in FIG. 4. Furthermore, the right bearing holding member 125R is held by the right support lever 103R so that the cleaning roller 121 can slide relative to the opposing member 123 in the direction of the arrow (FIG. 4).

[0039] Furthermore, as shown in FIG. 8, the right bearing holding member 125R is configured such that the cleaning roller 121 is pressed against the belt sliding surface 123c (FIG. 6) of the opposing member 123 via the fixing belt 104 by a right compression spring 129R stretched between its biasing receiving surface 128R and the right support lever 103R.

[0040] The fixing belt unit 41 configured as described above is rotatably supported by the pivot point 107 formed on the frame body 100 as described above, and is biased in the direction of arrow A by a compression spring (not shown) suspended between the side plate 101 and the spring receiving portion 130.

[0041] This biasing force causes the flat portion 105a of the heater unit 105 to come into pressure contact with the pressure roller 42 via the fixing belt 104, forming a nip portion 150 (FIG. 2). When separating the fixing belt 104 from the pressure roller 42, a cam (not shown) or the like presses the flat contact portion 131 (FIG. 4), rotating the fixing belt unit 41 clockwise to separate them.

[0042] 2, with nip 150 formed, pressure roller 42 rotates in the direction of the arrow (counterclockwise), causing fixing belt 104 to rotate together. In this state, when recording paper 22 on which transfer has been completed passes through nip 150 in the direction of arrow B, the transferred toner image is fixed by the heat (by fixing belt 104 heated to a predetermined temperature) and pressure treatment that it receives during this passage, and the recording paper is discharged from fixing device 40.

[0043] 2, downstream of the nip portion 150 in the rotational movement direction of the fixing belt 104, a cleaning roller 121 is disposed, which is in pressure contact with the belt sliding surface 123c (FIG. 6) of the opposing member 123 via the fixing belt 104. The cleaning roller 121 rotates counterclockwise in accordance with the rotational movement of the fixing belt 104, and the refreshing roller 122, which is in pressure contact with the cleaning roller 121 and rotates clockwise.

[0044] By these rotations, the cleaning roller 121 removes the developer adhering to the fixing belt 104 during fixing, and the refreshing roller 122 removes the developer adhering to the cleaning roller 121. Therefore, the fixing belt 104 heated in the nip portion 150 comes into direct contact with the cleaning roller 121 while still at a high temperature, so that the removal process can be carried out efficiently. Therefore, the opposing member 123 is formed in an area including the position where the outer circumferential surface of the fixing belt 104, which has passed through the nip portion 150, first comes into contact with the cleaning roller 121.

[0045] 2, a temperature detection unit 170 is disposed upstream of the nip portion 150 in the rotational movement direction of the fixing belt 104. This temperature detection unit 170 is disposed near the rotational movement path of the fixing belt 104, and detects the temperature of the fixing belt 104 which passes continuously as it rotates.

[0046] A fixing temperature control unit (not shown) controls the heat generation temperature of heater unit 105 so that the detected temperature is maintained at a desired temperature. Therefore, since the fixing belt 104 passing through temperature detection unit 170 is configured to directly reach nip portion 150, the detected temperature is close to the temperature of fixing belt 104 at nip portion 150, and high-precision temperature control at nip portion 150 is possible despite the presence of cleaning roller 121.

[0047] Figure 9 is a diagram used to explain the positional relationship between the opposing member 123, the right guide member 111R, and the cleaning roller 121, where Figure 9(a) is a schematic diagram of the main parts as seen from the left side of the longitudinal direction of the fixing belt unit 41 (the positive side of the arrow Y direction), and Figure 9(b) is an oblique view as seen from diagonally above.

[0048] As shown in these figures, when the opposing member 123, the right guide member 111R, and the cleaning roller 121 are all positioned at their respective predetermined positions, the cross-sectional shape of the belt sliding surface 123c of the opposing member 123 is formed to match the cross-sectionally substantially arc-shaped guide surface 114R of the inner guide portion 113R of the right guide member 111R. Therefore, no uneven surface or discontinuous curved surface is formed on this inner guide portion 113R.

[0049] Furthermore, when the shortest distance from the rotation shaft 121a of the cleaning roller 121 to the guide surface 114R of the inner guide portion 113R of the right guide member 111R is defined as a second distance d2, and the shortest distance from the rotation shaft 121a of the cleaning roller 121 to the belt sliding surface 123c of the opposing member 123 is defined as a first distance d1, these are 1 [mm] ≧ (d1-d2) ≧ 0 It is formed so that That is, the second distance d2 is equal to or slightly smaller than the first distance d1.

[0050] That is, at the contact portion with the cleaning roller 121, the guide surface 114R of the inner guide portion 113R of the right guide member 111R is formed so as to be flush with the belt sliding surface 123c of the opposing member 123 or to protrude slightly toward the cleaning roller 121. By forming it in this manner, deformation or damage to the fixing belt 104 caused by steps on these surfaces can be prevented, and furthermore, the end portion of the fixing belt 104 can be prevented from bending inward.

[0051] 8, in the longitudinal direction (arrow Y direction) of the fixing belt unit 41, the width of the belt sliding surface 123c of the opposing member 123 is wider than the width of the cleaning roller 121, and the cleaning roller 121 is configured to fit within the area of ​​the belt sliding surface 123c of the opposing member 123, so that the area through which the conveyed recording paper 22 passes fits within the area of ​​the cleaning roller 121. Furthermore, the end of the cleaning roller 121 is configured not to reach the area T1 of the guide surface 114R.

[0052] As described above, according to the fixing device of the present embodiment 1, the guide surface 114 of the support lever 103 and the belt sliding surface 123c of the opposing member 123, which are in pressure contact with the cleaning roller 121 and the fixing belt 104 via the cleaning roller 121, are formed and arranged to form a substantially flush curved surface. This prevents damage, deformation such as bending, and the like caused by local loads on the fixing belt 104 due to variations between the two surfaces, improves the durability of the fixing belt 104, and further prevents the ends of the fixing belt 104 from bending inward.

[0053] Furthermore, in the direction of rotational movement of the fixing belt 104, the cleaning roller 121 is arranged downstream of the nip portion 150, and on the upstream side, the fixing belt 104 is configured to pass through the temperature detection unit 170 and reach the nip portion 150 directly, thereby improving the accuracy of temperature detection during fixing.

[0054] Embodiment 2 Figure 10 is a structural diagram showing the configuration of the right guide member 211R alone used in the fixing device of embodiment 2 based on the present invention, where Figure 10(a) is an oblique view of the exterior, Figure 10(b) is a schematic diagram of the main parts viewed from the positive side of the arrow Y direction, with the right guide member 211R, heater unit 105, cleaning roller 121, and opposing member 223 each arranged in a predetermined position, and Figure 11 is an oblique view of each member in the state shown in Figure 10(b), viewed from diagonally above.

[0055] The right guide member 211R and the opposing member 223 of this embodiment shown in Figure 11 differ from, for example, the right guide member 111R and the opposing member 123 of embodiment 1 shown in Figure 9(b) in that a cutout portion 201R that reaches the guide surface 214R is formed in the inner guide portion 213R of the right guide member 211R, and the right end portion of the guide portion 223b of the opposing member 223 fits into the cutout portion 201R.

[0056] Therefore, the parts of the fixing device employing this right guide member 211R and the opposing member 223 that are common to the fixing device 40 (FIG. 2) of the first embodiment described above will be denoted by the same reference numerals or will not be shown in the drawings, and the explanation will be focused on the differences. Note that the essential configuration of the image forming device of this embodiment is common to the essential configuration of the image forming device 11 of the first embodiment shown in FIG. 1, except for the fixing device, so FIG. 1 will be referenced as necessary.

[0057] 11, in this embodiment, the right end of the guide portion 223b of the opposing member 223 reaches the region T1 of the guide surface 214R in the longitudinal direction (direction of arrow Y) of the fixing belt unit 41. Therefore, the guide surface 214R and the belt sliding surface 223c of the opposing member 223 form a continuous curved surface in the longitudinal direction and the circumferential direction, except for a small gap, around the contact portion with the cleaning roller 121.

[0058] 10(b) and 11, when the opposing member 223, the right guide member 211R, and the cleaning roller 121 are arranged in their respective predetermined positions, the cross-sectional shape of the belt sliding surface 223c of the opposing member 223 is formed to match the guide surface 214R, which has an approximately arc-shaped cross section, of the inner guide portion 213R of the right guide member 211R.

[0059] Furthermore, when the shortest distance from the rotation shaft 121a of the cleaning roller 121 to the guide surface 214R of the inner guide portion 113R of the right guide member 211R is defined as a second distance d2, and the shortest distance from the rotation shaft 121a of the cleaning roller 121 to the belt sliding surface 223c of the opposing member 223 is defined as a first distance d1, as in the first embodiment, 1 [mm] ≧ (d1-d2) ≧ 0 It is formed so that That is, the second distance d2 is equal to or slightly smaller than the first distance d1.

[0060] That is, at the contact portion with the cleaning roller 121, the guide surface 214R of the inner guide portion 213R of the right guide member 211R is formed so as to be flush with the belt sliding surface 223c of the opposing member 223 or to protrude slightly toward the cleaning roller 121. By forming it in this manner, deformation or damage to the fixing belt 104 caused by steps on these surfaces can be prevented, and furthermore, the end portion of the fixing belt 104 can be prevented from bending inward.

[0061] In addition, in the longitudinal direction (arrow Y direction) of the fixing belt unit 41, the width of the belt sliding surface 223c of the opposing member 223 is wider than the width of the cleaning roller 121, and the cleaning roller 121 is configured to fit within the area of ​​the belt sliding surface 223c of the opposing member 223, and furthermore, the passing area of ​​the transported recording paper 22 is configured to fit within the area of ​​the cleaning roller 121.

[0062] As described above, according to the fixing device of the second embodiment, the same effects as those of the first embodiment can be obtained, and in addition, the guide surface 214R of the opposing member 223 and the belt sliding surface 223c of the opposing member 223 form continuous curved surfaces in the longitudinal and circumferential directions around the contact portion with the cleaning roller 121, except for a small gap, so that the continuity of both curved surfaces can be further improved.

[0063] Furthermore, in the above claims and in the description of the embodiments, terms such as "upper," "lower," "left," "right," "front," and "rear" are used for convenience and do not limit the absolute positional relationship when the fixing device is arranged.

[0064] Various aspects of the present disclosure are summarized below as appendices. (Appendix 1) A circular belt; flange members provided at both ends of the annular belt to face each other and including flange portions for restricting the ends of the annular belt and support surfaces for supporting an inner peripheral surface of the annular belt; a cleaning roller that contacts the outer peripheral surface of the circular belt; an opposing member provided between the pair of flange members and facing the cleaning roller with the circular belt interposed therebetween at a position where the circular belt and the cleaning roller come into contact with each other; and A fixing device characterized in that, when viewed in the axial direction of the cleaning roller, a first distance from the axial center of the cleaning roller to the opposing member is equal to or greater than a second distance from the axial center of the cleaning roller to the support surface. (Appendix 2) a rotating member capable of forming a nip portion with respect to the circular belt; The fixing device described in Appendix 1 is characterized in that the area in which the opposing member is formed in the circumferential direction of the circular belt includes a position downstream of the nip portion in the rotational movement direction of the circular belt where the outer surface of the circular belt that has passed through the nip portion first comes into contact with another member. (Appendix 3) The fixing device described in Appendix 1 or 2, characterized in that the opposing member has an inclined surface that, when viewed from the axial direction of the cleaning roller, becomes more distant from the support surface as it moves away from the contact surface, upstream of the contact surface that contacts the circular belt in the rotational movement direction of the circular belt. (Appendix 4) a temperature detection unit that detects the temperature of the circular belt; The fixing device described in Appendix 2 is characterized in that the temperature detection unit detects the temperature of the circular belt upstream of the nip portion in the direction of rotational movement of the circular belt, and between the nip portion and the position where the circular belt and the cleaning roller contact each other. (Appendix 5) The fixing device according to claim 1 or 2, characterized in that the width of the cleaning roller in the axial direction of the cleaning roller is narrower than the width of the opposing member, and the end of the cleaning roller is configured so as not to reach the area of ​​the support surface. (Appendix 6) 3. The fixing device according to claim 1, wherein the support surface has a cross section that is a curved surface having a substantially arcuate shape and does not include an uneven surface. (Appendix 7) When the first distance is d1 and the second distance is d2, 1 [mm] ≧ (d1-d2) ≧ 0 3. The fixing device according to claim 1, wherein the following relational expression is satisfied: (Appendix 8) 3. An image forming apparatus comprising the fixing device according to claim 1 or 2. [Industrial Applicability]

[0065] In the above embodiment, an example was shown in which the present invention is applied to an image forming apparatus as a color printer, but the present invention is not limited to this and can also be applied to image processing apparatuses such as copiers, facsimiles, MFPs, etc. Also, although a color printer has been described, a monochrome printer may also be used. [Explanation of symbols]

[0066] REFERENCE SIGNS LIST 11 image forming device, 12 image forming unit, 13 photosensitive drum, 14 charging roller, 15 exposure head, 16 developing device, 17 transfer roller, 18 transfer belt drive roller, 19 transfer belt driven roller, 20 transfer belt, 21 transfer unit, 22 recording paper, 24 hopping roller, 25 first conveying roller pair, 26 second conveying roller pair, 27 discharge roller pair, 28 discharge roller pair, 35 support plate, 36 urging spring, 40 fixing device, 41 fixing belt unit, 42 pressure roller, 42a rotating shaft, 45 paper transport path, 46 paper stacker section, 100 frame, 101R right side plate, 103R right support lever, 104 fixing belt, 105 heater unit, 105a Flat portion, 107R right pivot point, 110R right pivot shaft hole, 111R right guide member, 112R right regulating portion, 113R inner guide portion, 114R guide surface, 121 cleaning roller, 121a rotating shaft, 122 refreshing roller, 122a rotating shaft, 123 opposing member, 123a mounting portion, 123b guide portion, 123c belt sliding surface, 123d belt introduction surface, 125R right bearing holding member, 126R right bearing, 127R right bearing, 128R biasing receiving surface, 129R right compression spring, 150 nip portion, 160 electrical connector connection portion, 170 temperature detection portion, 201R notch portion, 211R Right guide member, 213R inner guide portion, 214R guide surface, 223 opposing member, 223b guide portion, 223c belt sliding surface.

Claims

1. A circular belt; flange members provided at both ends of the annular belt to face each other and including flange portions for restricting the ends of the annular belt and support surfaces for supporting an inner peripheral surface of the annular belt; a cleaning roller that contacts the outer peripheral surface of the circular belt; an opposing member provided between the pair of flange members and facing the cleaning roller with the circular belt interposed therebetween at a position where the circular belt and the cleaning roller come into contact with each other; and a fixing device, characterized in that, when viewed in the axial direction of the cleaning roller, a first distance from the axial center of the cleaning roller to the opposing member is equal to or greater than a second distance from the axial center of the cleaning roller to the support surface.

2. a rotating member capable of forming a nip portion with respect to the circular belt; The fixing device described in claim 1, characterized in that the area in which the opposing member is formed in the circumferential direction of the circular belt includes a position downstream of the nip portion in the rotational movement direction of the circular belt where the outer surface of the circular belt that has passed through the nip portion first comes into contact with another member.

3. 3. The fixing device according to claim 1, wherein the opposing member has an inclined surface that, when viewed from the axial direction of the cleaning roller, becomes more distant from the support surface as it moves away from the contact surface that contacts the circular belt, upstream of the contact surface that contacts the circular belt in the rotational movement direction of the circular belt.

4. a temperature detection unit that detects the temperature of the circular belt; 3. The fixing device according to claim 2, wherein the temperature detection unit detects the temperature of the circular belt upstream of the nip portion in the direction of rotation of the circular belt, and between the nip portion and the position where the circular belt and the cleaning roller contact each other.

5. 3. The fixing device according to claim 1, wherein the width of the cleaning roller in the axial direction of the cleaning roller is narrower than the width of the opposing member, and the end of the cleaning roller is configured not to reach the area of ​​the support surface.

6. 3. The fixing device according to claim 1, wherein the support surface has a cross section that is a curved surface having a substantially arc shape and does not include an uneven surface.

7. When the first distance is d1 and the second distance is d2, 1 [mm]≧(d1-d2)≧0 3. The fixing device according to claim 1, wherein the following relational expression is satisfied:

8. 3. An image forming apparatus comprising the fixing device according to claim 1.

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