Fixing unit and image forming apparatus

Abstract

This suppresses deformation of the side plate when the rotation axis of the second rotating body undergoes thermal expansion in the axial direction. [Solution] The fixing unit 100 comprises a heating section 10, a first rotating body 20 heated by the heating section 10 and rotating about an axis extending in a first direction, a second rotating body 30 having a rotating shaft 31 extending in a first direction and positioned opposite the outer circumferential surface of the first rotating body 20, forming a fixing nip section 110 through which the recording medium passes between it and the outer circumferential surface of the first rotating body, bearings 40A, 40B that rotatably support the rotating shaft of the second rotating body, bearing holding members 50A, 50B that hold the bearings, and a pair of side plates 60 that are spaced apart in a first direction and hold the bearing holding members. The bearing holding member 50B has a first position adjustment section 121 that can adjust the position of the bearing 40B in a first direction.

Description

Technical Field

[0001] The present disclosure relates to a fixing unit and an image forming apparatus.

Background Art

[0002] For example, a fixing device includes a fixing member, a pressing member that presses against the fixing member, and a holding structure that holds at least one of the fixing member and the pressing member. The fixing device forms a fixing nip between the fixing member and the pressing member. The fixing device fixes a toner image on a recording medium (see, for example, Patent Document 1). The pressing member has a core metal and an elastic rubber layer provided on the outer periphery of the core metal.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In the prior art, the core metal of the pressing member is press-fitted into the bearing so that the core metal and the bearing do not hit each other and no abnormal noise occurs. The bearing is fixed to the side plate of the fixing device. However, when the pressing member becomes hot and extends in the axial direction, the side plate deforms outward in the axial direction.

[0004] An object of the present disclosure is to provide a fixing device capable of suppressing deformation of a side plate when the rotation axis of a second rotating body thermally expands in the axial direction.

Means for Solving the Problems

[0005] The fixing unit according to the present disclosure includes a heating unit, a first rotating body that is heated by the heating unit and rotates around an axis extending in a first direction, a second rotating body that has a rotation axis extending in the first direction and is disposed opposite to the outer peripheral surface of the first rotating body, and forms a fixing nip portion through which a recording medium passes between the outer peripheral surface of the first rotating body, a bearing that rotatably supports the rotation axis of the second rotating body, a bearing holding member that holds the bearing, and a pair of side plates that are disposed apart from each other in the first direction and hold the bearing holding member. The bearing holding member has a first position adjusting portion capable of adjusting the position of the bearing in the first direction.

Effects of the Invention

[0006] This disclosure provides a fixing unit that can suppress deformation of the side plate when the rotation axis of the second rotating body undergoes thermal expansion in the axial direction. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram illustrating a fixing device according to the first embodiment. [Figure 2] This is a schematic diagram illustrating the pressure roller, bearing, bearing cover, and side plate of the fixing device according to the first embodiment. [Figure 3] This is a side view illustrating a fixing device according to the first embodiment. [Figure 4] This is a cross-sectional view showing a section along the line IV-IV in Figure 3, illustrating the fixing belt, fixing belt holding member, and side plate. [Figure 5] This is a cross-sectional view showing a cross-section along the VV line in Figure 3, illustrating the end of the core metal, the bearing, the bearing cover, and the side plate. [Figure 6] This is a side view illustrating the side plate of a fixing device according to the first embodiment. [Figure 7] This figure illustrates the end of the core metal, bearing, bearing cover, and side plate of the fixing device according to the third embodiment. [Figure 8] This figure illustrates the end of the core metal, the bearing, the bearing cover, and the bent portion of the side plate of the fixing device according to the fifth embodiment. [Figure 9] This is a schematic diagram illustrating an image forming apparatus equipped with a fixing device according to an embodiment. [Modes for carrying out the invention]

[0008] The fixing unit and image forming apparatus according to the embodiment will be described below with reference to the drawings.

[0009] [Fixing device 100 according to the first embodiment] Figure 1 is a schematic diagram illustrating the fixing device 100 according to the first embodiment. Figure 2 is a schematic diagram illustrating the pressure roller 30, bearing 40, bearing cover 50, and side plate 60 of the fixing device 100 according to the first embodiment. Figure 3 is a side view illustrating the fixing device 100 according to the first embodiment. Figure 4 is a cross-sectional view showing a cross-section along the line IV-IV in Figure 3, illustrating the side plate 60, fixing belt holding member 22, and fixing belt 20. Figure 5 is a cross-sectional view showing a cross-section along the line VV in Figure 3, illustrating the end 31b of the core metal 31, bearing 40B, bearing cover 50B, and side plate 60. Figure 5 is a side view illustrating the side plate 60 of the fixing device 100 according to the first embodiment. As shown in Figure 1, the fixing device 100 includes a heater 10, a fixing belt 20, and a pressure roller 30. As shown in Figure 2, the fixing device 100 comprises bearings 40A, 40B, bearing covers 50A, 50B, and a side plate 60. Note that the fixing device 100 is an example of a fixing unit.

[0010] In each figure, arrows indicating the X-axis, Y-axis, and Z-axis directions are shown. The X-axis, Y-axis, and Z-axis directions may be mutually orthogonal. The X-axis direction is an example of the first direction.

[0011] [Heater 10] The fixing device 100 may include a plurality of heaters 10, as shown in Figure 1. The heaters 10 are positioned inside the fixing belt 20 and heat the fixing belt 20. The heaters 10 may be, for example, halogen heaters. The heaters 10 are an example of a heating element. The heaters 10 may be, for example, planar heaters.

[0012] [Fixing belt 20] The fixing belt 20 is an endless belt and is rotatable around the X-axis. As described above, the heater 10 is positioned inside the fixing belt 20. The heater 10 heats the fixing belt 20 from the inside by radiant heat.

[0013] As shown in Figures 3 and 4, the fixing device 100 may include a fixing belt holding member 22 for holding the fixing belt 20. The fixing belt holding member 22 includes a base portion 23 that is attached to the side plate 60 and a holding portion 24 for holding the fixing belt 20. The side plate 60 has an opening into which the fixing belt holding member 22 is attached. The base portion 23 is plate-shaped, and the thickness direction of the base portion 23 is the same as the thickness direction of the side plate 60. The base portion 23 may have a groove into which the end portion that forms the opening of the side plate 60 is inserted.

[0014] The retaining portion 24 is formed to protrude inward from the base portion 23 into the fixing device 100. The retaining portion 24 includes an outer circumferential surface that contacts the inner surface of the fixing belt 20. The retaining portion 24 is formed, for example, to be cylindrical. The retaining portion 24 is inserted into the inside of the fixing belt 20 and holds the end of the fixing belt 20 in the width direction. The fixing belt 20 is slidable along the outer circumferential surface of the retaining portion 24.

[0015] [Pressure Roller 30] As shown in Figure 1, the pressure roller 30 is positioned opposite the outer surface of the fixing belt 20. A fixing nip portion 110 is formed between the outer surface of the pressure roller 30 and the outer surface of the fixing belt 20, through which the recording medium passes. The pressure roller 30 and the fixing belt 20 are opposite each other in the Y-axis direction.

[0016] As shown in Figures 1 and 2, the pressure roller 30 has a core metal 31 positioned at the center of the pressure roller 30 and a rubber layer 32 positioned on the outside of the core metal 31 in the radial direction of the pressure roller 30. The rubber layer 32 is formed around the entire circumference of the core metal 31. The outer circumferential surface 30a of the pressure roller 30 is the outer circumferential surface of the rubber layer 32. A release layer may be formed on the surface of the rubber layer 32. The release layer may be, for example, a PFA layer or a PTFE layer.

[0017] A drive motor is connected to the pressure roller 30. The rotational driving force from the drive motor is transmitted, for example, via a gear to the mandrel 31 which is the rotating shaft of the pressure roller 30. The pressure roller 30 rotates by the rotational driving force transmitted from the drive motor. The drive motor may be attached to, for example, the side plate 60.

[0018] The mandrel 31 may be a hollow roller, and a heating part such as a heater may be provided inside the mandrel 31. The rubber layer 32 may be, for example, solid rubber. When there is no heater inside the mandrel 31, the rubber layer 32 may be sponge rubber. The heat insulation property of sponge rubber is higher than that of solid rubber, and the temperature of the fixing belt 20 is less likely to decrease.

[0019] The fixing device 100 may include a pressing mechanism that presses the pressure roller 30 against the fixing belt 20. The pressing mechanism includes a biasing member such as a spring, for example. The pressure roller 30 is pressed against the fixing belt 20 by the biasing member. The pressure roller 30 is pressed against the fixing belt 20 in the Y-axis direction. The rubber layer 32 is crushed and deformed. A predetermined nip width is formed between the pressure roller 30 and the heater 10.

[0020] [Nip forming member 80] As shown in FIG. 1, the fixing device 100 includes a nip forming member 80. The nip forming member 80 is disposed inside the fixing belt 20. The nip forming member 80 is disposed so as to contact the inner peripheral surface of the fixing belt 20. The nip forming member 8 establishes a fixing nip portion 110 with the pressure roller 30 via the heat transfer assisting member 70 and the fixing belt 20. In the fixing nip portion 110, the toner image on the recording medium is fixed by heating and pressing.

[0021] [Heat transfer assisting member 70] The fixing device 100 includes a heat transfer assist member 70. The heat transfer assist member 70 is positioned inside the fixing belt 20. The heat transfer assist member 70 may have a flat surface that contacts the inner surface of the fixing belt 20. The heat transfer assist member 70 is contactable with the inner surface of the fixing belt 20 in the Y-axis direction. The heat transfer assist member 70 has a predetermined width in the X-axis direction. The recording medium is transported in the Z-axis direction. The heat transfer assist member 70 has a length in the X-axis direction corresponding to the width of the recording medium. The surface of the heat transfer assist member 70 that contacts the inner surface of the fixing belt 20 may be a flat surface, a curved surface, or include a recess.

[0022] [Stay 90 and reflective member 92] The fixing device 100 includes a stay 90 and a reflective member 92. The stay 90 and the reflective member 92 are positioned inside the fixing belt 20 and extend in the X-axis direction. Both longitudinal ends of the stay 90 are fixed to, for example, the side plate 60. The stay 90 supports the nip forming member 80.

[0023] The fixing device 100 may include a plurality of reflective members 92. The plurality of reflective members 92 are fixed to the stay 90. The reflective members 92 have reflective surfaces that reflect heat from the heater 10. The reflective members 92 are positioned between the heater 10 and the stay 90. The reflective members 92 can heat the fixing belt 20 by reflecting radiant heat from the heater 10. The reflective members 92 include, for example, surfaces that are inclined with respect to the XY plane.

[0024] [Operation of fixing belt 20] The fixing belt 20 rotates as the rotation of the pressure roller 30 is transmitted to it. The fixing belt 20 rotates in conjunction with the rotation of the pressure roller 30. At the fixing nip section 110, the outer surface of the fixing belt 20 and the outer surface of the pressure roller 30 come into contact, and the rotational force of the pressure roller 30 is transmitted to the fixing belt 20. At the fixing nip section 110, if a recording medium is sandwiched between the fixing belt 20 and the pressure roller 30, the rotational force of the pressure roller 30 is transmitted to the fixing belt 20 via the recording medium.

[0025] The fixing device 100 may be equipped with a guide for guiding the rotation of the fixing belt 20. The guide may be attached to the side plate 60.

[0026] [Linear velocity sensor] The fixing device 100 may be equipped with a linear velocity sensor for detecting the linear velocity of the fixing belt 20.

[0027] [Temperature sensor] The fixing device 100 may be equipped with a temperature sensor for detecting the temperature of the pressure roller 30.

[0028] [Static elimination component] The fixing device 100 may also include a static elimination brush as a static elimination member that contacts the outer surface of the pressure roller 30 to eliminate static electricity from the pressure roller 30.

[0029] [Bearings 40A, 40B] As shown in Figures 2, 3, and 5, the fixing device 100 includes a pair of bearings 40A and 40B that rotatably support the rotating shaft of the pressure roller 30. The rotating shaft may be, for example, a mandrel 31. The mandrel 31 has ends 31a and 31b, which are both ends in the longitudinal direction. The bearings 40A and 40B are spaced apart in the X-axis direction. Bearing 40A supports end 31a, and bearing 40B supports end 31b. The bearings 40A and 40B may be, for example, sliding bearings. The bearings 40A and 40B are fixed to the mandrel 31. The bearings 40A and 40B may be press-fitted to the mandrel 31. This suppresses the generation of abnormal noise in the fixing device 100.

[0030] [Bearing cover 50B] The fixing device 100 includes a bearing cover 50A that holds bearing 40A, and a bearing cover 50B that holds bearing 40B. As shown in Figure 3, the bearing covers 50A and 50B are formed to form a U shape when viewed in the X-axis direction. The openings of the bearing covers 50A and 50B are located on the fixing belt 20 side in the Y-axis direction.

[0031] The bearing covers 50A and 50B have almost identical structures. Bearing cover 50B includes a first position adjustment section 121, while bearing cover 50A does not. The first position adjustment section 121 will be described later. Bearing cover 50B will be described before bearing cover 50A. Note that bearing cover 50A may have a first position adjustment section 121, or it may have the same structure as bearing cover 50B.

[0032] The bearing covers 50A and 50B are formed from, for example, an insulating material. The insulating material may be an insulating resin. This allows the side plate 60 to be insulated from the bearings 40A and 40B.

[0033] As shown in Figure 5, the bearing cover 50B has a main plate 51, flanges 52 and 53, and a mounting portion 54. The main plate 51 is formed to cover the outer circumferential surface of the bearing 40B. The main plate 51 is formed to form a U shape when viewed in the X-axis direction. The thickness direction of the main plate 51 is aligned with the radial direction of the bearing 40B.

[0034] The main plate 51 has an inner circumferential surface 51a that abuts against the outer circumferential surface 41 of the bearing 40B. The inner circumferential surface 51a faces the outer circumferential surface 41 of the bearing 40B in the radial direction of the bearing 40B. The width of the inner circumferential surface 51a along the X-axis direction is wider than the width of the outer circumferential surface 41 of the bearing 40B. The bearing cover 50B holds the bearing 40B so that it can slide in the X-axis direction. The bearing 40B is in contact with the inner circumferential surface 51a of the main plate 51 and is slidable in the X-axis direction.

[0035] The flanges 52 and 53 are positioned on both sides of the main plate 51 in the X-axis direction and are formed to protrude radially from the main plate 51 toward the bearing 40B. The flanges 52 and 53 protrude toward the core metal 31 from the main plate 51. The flanges 52 and 53 are formed to face each other in the X-axis direction.

[0036] The bearing 40B is positioned between flange 52 and flange 53 in the X-axis direction. In the X-axis direction, the distance between flange 52 and flange 53 is greater than the width of the bearing 40B. The bearing 40B is movable in the X-axis direction between flange 52 and flange 53. Flange 52 is positioned on the inside of the fixing device 100 in the X-axis direction, and flange 53 is positioned on the outside. As shown in Figure 3, flanges 52 and 53 are formed to form a U-shape when viewed in the X-axis direction.

[0037] As shown in Figure 5, the mounting portion 54 has a groove 55 into which the open end 61 of the side plate 60 is inserted. The groove 55 is formed along the outer circumferential surface of the main plate 51. The mounting portion 54 has side walls 55a and 55b facing each other in the X-axis direction, and the open end 61 is inserted into the groove 55 between the side walls 55a and 55b. The open end 61 is fitted into the groove 55. The side surface of the open end 61 facing each other in the X-axis direction is in contact with the side walls 55a and 55b. As shown in Figure 6, a U-shaped opening is formed in the side plate 60. The open end 61 includes the peripheral edge that forms the U-shaped opening. Note that in Figure 6, the pressure roller 30 and the bearing 40B are shown by dashed lines.

[0038] When mounting the bearing 40B to the side plate 60, the bearing 40B is slid in the Y-axis direction, thereby inserting the open end 61 into the groove 55.

[0039] [First position adjustment section 121] The bearing cover 50B has a first position adjustment section 121 that allows adjustment of the position of the bearing 40B in the X-axis direction, as shown in Figure 5. The first position adjustment section 121 includes a gap in which the bearing 40B can move. The first position adjustment section 121 includes a main plate 51 and flanges 52 and 53. The bearing 40B is displaceable in the X-axis direction between flanges 52 and 53. The anchoring device 100 allows adjustment of the position of the bearing 40B in the X-axis direction. The bearing 40B is movable relative to the side plate 60 in the X-axis direction.

[0040] [Bearing cover 50A] The bearing cover 50A, like the bearing cover 50B, has a main plate 51, flanges 52 and 53, and a mounting portion 54. Unlike the bearing cover 50B, the bearing cover 50A does not have a first position adjustment portion 121. The bearing 40A is sandwiched between the flanges 52 and 53, and its position in the X-axis direction is constrained. The bearing 40A does not displace in the X-axis direction.

[0041] The force transmission member (e.g., a gear) that transmits the driving force to the pressure roller 30 may be positioned close to the bearing 40A, whose movement in the X-axis direction is constrained.

[0042] [Effects of the fixing device 100 according to the first embodiment] The fixing device 100 according to the first embodiment includes a heater (heating unit) 10, a fixing belt (first rotating body) 20 heated by the heater 10 and rotating around an axis extending in the X-axis direction (first direction), a pressure roller (second rotating body) 30 having a core metal (rotating shaft) 31 extending in the X-axis direction, positioned opposite the outer circumferential surface of the fixing belt 20, and forming a fixing nip portion 110 through which a recording medium passes between it and the outer circumferential surface of the fixing belt 20, bearings 40A, 40B that rotatably support the core metal 31 of the pressure roller 30, bearing covers (bearing holding members) 50A, 50B that hold the bearings 40A, 40B, and a pair of side plates 60, 60 that are spaced apart in the X-axis direction and hold the bearing covers 50A, 50B. The bearing cover 50B has a first position adjustment unit 121 that can adjust the position of the bearing 40B in the X-axis direction.

[0043] In such a fixing device 100, when the core metal 31 undergoes thermal expansion, the bearing 40B and the bearing cover 50B can be displaced in the X-axis direction. This makes it possible to suppress deformation of the side plate 60 when the core metal 31 of the pressure roller 30 undergoes thermal expansion in the X-axis direction.

[0044] In the fixing device 100, the bearing 40A and the bearing cover 50A are constrained in position in the X-axis direction relative to the side plate 60. This suppresses the displacement of the pressure roller 30 in the X-axis direction and thus suppresses the axial length of the pressure roller 30. In the fixing device 100, by fixing one of the ends of the rotating shaft in the X-axis direction, it is easy to restrict the position of the rubber layer 32 of the pressure roller 30 with respect to the position where the recording medium passes. Therefore, the axial length of the pressure roller 30 can be suppressed.

[0045] [Fixing device 100 according to the second embodiment] Next, the fixing device 100 according to the second embodiment will be described. The difference between the fixing device 100 according to the second embodiment and the fixing device 100 according to the first embodiment is that the bearing cover 50A has a first position adjustment part 121. The first position adjustment part 121 may be provided on both the bearing covers 50A and 50B.

[0046] The fixing device 100 according to this second embodiment also provides the same effects and advantages as the fixing device 100 in the first embodiment described above. In the fixing device 100 according to the second embodiment, both bearings 40A and 40B can be displaced in the X-axis direction.

[0047] [Fixing device 100 according to the third embodiment] Next, the fixing device 100 according to the third embodiment will be described. Figure 7 is a diagram illustrating the end portion 31b of the core metal 31, the bearing 40B, and the side plate 60 of the fixing device 100 according to the third embodiment. The difference between the fixing device 100 according to the third embodiment and the fixing device 100 according to the first embodiment described above is that it is equipped with a bearing cover 50C instead of a bearing cover 50B. In the description of the fixing device 100 according to the third embodiment, the same explanation as that given to the fixing device 100 according to the above embodiment will be omitted.

[0048] The fixing device 100 according to the third embodiment includes a bearing cover 50C. The bearing cover 50C holds the bearing 40B. The bearing cover 50C has a main plate 51, flanges 52, 53, and a mounting portion 54C. The main plate 51 has an inner circumferential surface 51a that abuts against the outer circumferential surface 41 of the bearing 40B. The width of the inner circumferential surface 51a along the X-axis direction is approximately the same as the width of the outer circumferential surface 41 of the bearing 40B.

[0049] The flanges 52 and 53 are positioned on both sides of the main plate 51 in the X-axis direction and are formed to protrude radially from the main plate 51 toward the bearing 40B. The flanges 52 and 53 protrude toward the core metal 31 from the main plate 51. The flanges 52 and 53 are formed to face each other in the X-axis direction.

[0050] The bearing 40B is positioned between the flange 52 and the flange 53 in the X-axis direction. In the X-axis direction, the distance between the flange 52 and the flange 53 is approximately the same as the width of the bearing 40B. The bearing 40B is in contact with the flange 52 and the flange 53 in the X-axis direction. The bearing 40B does not move in the X-axis direction between the flange 52 and the flange 53.

[0051] The mounting portion 54C has a groove 55C into which the open end 61 of the side plate 60 is inserted. The groove 55C is formed along the outer peripheral surface 51b of the main plate 51. The mounting portion 54C has side walls 55a and 55b facing each other in the X-axis direction, and the open end 61 is inserted into the groove 55 between the side walls 55a and 55b.

[0052] The side walls 55a and 55b are opposed to each other in the X-axis direction and are formed to protrude radially outward from the outer circumferential surface 51b of the main plate 51 towards the bearing 40B. The side walls 55a and 55b protrude on the side opposite to the bearing 40B.

[0053] In the X-axis direction, the distance between side wall 55a and side wall 55b is greater than the thickness of the side plate 60. The bearing cover 50C is movable in the X-axis direction relative to the side plate 60. In other words, the bearing 40B held by the bearing cover 50C is movable in the X-axis direction relative to the side plate 60.

[0054] [Second position adjustment section 122] The bearing cover 50C has a second position adjustment section 122 that allows adjustment of the position of the bearing 40B in the X-axis direction. The second position adjustment section 122 includes a gap in which the bearing 40B can move. The second position adjustment section 122 includes a groove 55C in the mounting section 54C. The bearing 40B is movable according to the size of the gap between the side plate 60 and the side walls 55a, 55b. The bearing cover 50C is displaceable in the X-axis direction until the side wall 55a or side wall 55b contacts the side plate 60. The bearing 40B is movable relative to the side plate 60 in the X-axis direction.

[0055] The fixing device 100 according to this third embodiment also provides the same effects and advantages as the fixing devices 100 according to the first and second embodiments described above. In the fixing device 100 according to the third embodiment, the bearing 40B and the bearing cover 50B are displaced as a single unit.

[0056] [Fixing device 100 according to the fourth embodiment] Next, the fixing device 100 according to the fourth embodiment will be described. The difference between the fixing device 100 according to the fourth embodiment and the fixing device 100 according to the third embodiment is that, instead of the bearing cover 50A that holds the bearing 40A, it has a bearing cover 50C having a second position adjustment part 122. The second position adjustment part 122 may be provided on both the bearing cover 50C that holds the bearing 40A and the bearing cover 50C that holds the bearing 40B.

[0057] The fixing device 100 according to this fourth embodiment also provides the same effects and advantages as the fixing device 100 in the first to third embodiments described above. In the fixing device 100 according to the fourth embodiment, both bearings 40A and 40B can be displaced in the X-axis direction. The bearing cover 50C that holds the bearings 40A and 40B can be a common part.

[0058] [Fixing device 100 according to the fifth embodiment] Next, the fixing device 100 according to the fifth embodiment will be described. Figure 8 is a diagram illustrating the end portion 31a of the core metal 31, the bearing 40A, the bearing cover 50C, and the bent portion 62 of the side plate 60 of the fixing device according to the fifth embodiment. The difference between the fixing device 100 according to the fifth embodiment and the fixing device 100 according to the fourth embodiment described above is that a bent portion 62 is formed at the open end portion 61 of the side plate 60 which is inserted into the groove 55C of the bearing cover 50C that holds the bearing 40A. In the description of the fixing device 100 according to the fifth embodiment, the same explanation as that given for the fixing devices 100 according to the first to fourth embodiments will be omitted.

[0059] The thickness direction of the open end 61 is aligned with the X-axis direction. The bent portion 62 is bent from the tip of the open end 61 and protrudes in the X-axis direction. The thickness direction of the bent portion 62 is aligned with the radial direction of the bearing 40A. The bent portion 62 is formed to be in contact with the outer circumferential surface 51b of the main plate 51. The width of the bent portion 62 along the X-axis direction corresponds to the distance between the side walls 55a and 55b of the groove 55C. The bent portion 62 is fitted into the groove 55C. Therefore, the bearing cover 50C and the bearing 40A do not displace in the X-axis direction.

[0060] The fixing device 100 according to this fifth embodiment also provides the same effects and advantages as the fixing device 100 in the first to fourth embodiments described above. In the fixing device 100 according to the fifth embodiment, the bearing cover 50C that holds the bearings 40A and 40B can be a common part. Because the bent portion 62 is fitted into the groove 55C of the bearing cover 50C that holds the bearing 40A, the bearing 40A does not displace. This makes it possible to suppress the displacement of the pressure roller 30 in the X-axis direction and to suppress the length of the pressure roller 30 in the axial direction. It is easy to restrict the position of the rubber layer 32 of the pressure roller 30 with respect to the position where the recording medium passes. The fixing device 100 may have, for example, a plate-shaped spacer instead of the bent portion 62. By inserting the spacer into the groove 55C, the movement of the bearing cover 50C and the bearing 40A relative to the side plate 60 can be restricted.

[0061] [Image forming apparatus 300 according to the embodiment] An image forming apparatus 300 equipped with a fixing device 100 according to an embodiment will be described. The image forming apparatus 300 is, for example, an electrophotographic color printer. Figure 9 is a schematic diagram illustrating an image forming apparatus equipped with a fixing device 100 according to an embodiment.

[0062] The image forming apparatus 300 is a tandem-type color printer in which image forming units for forming multiple color images are arranged side by side along the tension direction of a transfer belt 311, which serves as an intermediate transfer body. The image forming apparatus 300 to which the fixing device 100 according to this embodiment can be applied is not limited to this type, and it can also be applied not only to printers but also to image forming apparatuses such as copiers and facsimile machines.

[0063] The image forming apparatus 300 employs a tandem structure in which photoreceptor drums 320Y,C,M,Bk are arranged side by side, each serving as an image carrier capable of forming an image corresponding to the separated colors of yellow, cyan, magenta, and black.

[0064] In the image forming apparatus 300, the visible image, consisting of toner images formed on each photoreceptor drum 320Y,C,M,Bk, is first transferred to a transfer belt 311, which is an intermediate transfer body consisting of an endless belt that can move in the direction of arrow A1 while facing each photoreceptor drum 320. Through this first transfer process, the images of each color are superimposed and transferred, and then a second transfer process is performed on a sheet-like recording material, paper P, to transfer them all at once.

[0065] Around each photoreceptor drum 320, devices for image formation processing are arranged in accordance with the rotation of the photoreceptor drum 320. Taking the photoreceptor drum 320Bk, which performs black image formation, as a representative example, a charging device 330Bk, a developing device 340Bk, a primary transfer roller 312Bk, and a cleaning device 350Bk are arranged in the direction of rotation of the photoreceptor drum 320Bk for image formation processing. After uniform charging by the charging device 330Bk, an optical writing device 8 is used for optical writing using writing light Lb.

[0066] In superimposed transfer onto the transfer belt 311, as the transfer belt 311 moves in the direction A1 in the figure, the toner images formed on each photoreceptor drum 320Y,C,M,Bk are superimposed and transferred to the same position on the transfer belt 311. For this purpose, the primary transfer is performed by applying voltage using primary transfer rollers 312Y,C,M,Bk, which are arranged opposite each photoreceptor drum 320Y,C,M,Bk across the transfer belt 311, with the timing staggered from the upstream side to the downstream side in the direction A1 in the figure.

[0067] Each photoreceptor drum 320Y, C, M, Bk is arranged in this order from the upstream side in the A1 direction in the diagram. Also, each photoreceptor drum 320Y, C, M, Bk contains yellow (Y), cyan (C), Image stations for forming magenta (M) and black (Bk) images respectively It is provided.

[0068] The image forming apparatus 300 includes four image stations that perform image forming processing for each color, and a transfer belt unit 310 disposed opposite to each other above the photoreceptor drums 320Y, C, M, Bk, and equipped with a transfer belt 311 and primary transfer rollers 312Y, C, M, Bk. It also includes a secondary transfer roller 305 disposed opposite to the transfer belt 311 and moving along with it, and a belt cleaning device 313 disposed opposite to the transfer belt 311 and cleaning the transfer belt 311. Furthermore, it includes an optical writing device 308 disposed opposite to the four image stations below.

[0069] The optical writing device 308 is equipped with a semiconductor laser as a light source for writing electrostatic latent images, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, and a rotating polyhedron mirror as a polarization means. This optical writing device 308 is configured to emit writing light Lb corresponding to each color to each photoreceptor drum 320Y,C,M,Bk to form electrostatic latent images on the photoreceptor drums 320Y,C,M,Bk. In Figure 9, for convenience, the writing light Lb is labeled only for the black image station, but the same applies to the other image stations.

[0070] The image forming apparatus 300 is equipped with a paper feed device 361, which serves as a paper feed cassette and holds a recording medium (paper) P that is transported between the transfer belt 311 and the secondary transfer roller 305. It is also equipped with a pair of registration rollers 304 that feeds the paper P transported from the paper feed device 361 towards the secondary transfer section between the transfer belt 311 and the secondary transfer roller 305 at a predetermined timing synchronized with the toner image formation timing by the image station. Furthermore, a sensor is provided to detect when the leading edge of the recording medium P reaches the pair of registration rollers 304.

[0071] Furthermore, the image forming apparatus 300 is equipped with a contact heating type fixing unit 100 for fixing the toner image onto the recording medium P on which the toner image has been transferred, and an discharge roller 307 for discharging the fixed paper P to the outside of the main body of the image forming apparatus 300. In addition, the top of the main body of the image forming apparatus 300 is equipped with a paper output tray 317 for stacking the recording medium P discharged to the outside of the main body of the image forming apparatus 300 by the discharge roller 307. In addition, toner bottles 309Y,C,M,Bk filled with yellow, cyan, magenta, and black toner are provided inside the main body of the apparatus below the paper output tray 317.

[0072] The transfer belt unit 310 includes a transfer belt 311, primary transfer rollers 312Y, C, M, Bk, as well as a drive roller 372 and a driven roller 373 around which the transfer belt 311 is routed.

[0073] The driven roller 373 also functions as a tension biasing means for the transfer belt 311, and the driven roller 373 is equipped with a biasing means such as a spring. The transfer device 371 is composed of such a transfer belt unit 310, primary transfer rollers 312Y, C, M, Bk, secondary transfer roller 305, and belt cleaning device 313.

[0074] The paper feed device 361 is located at the bottom of the main body of the image forming apparatus 300 and has a feed roller 303 that contacts the upper surface of the uppermost sheet of paper P. The feed roller 303 is driven to rotate counterclockwise in the figure, thereby feeding the uppermost recording medium P toward the register roller pair 304.

[0075] The belt cleaning device 313, which is equipped in the transfer device 371, has a cleaning brush and a cleaning blade that are positioned opposite and in contact with the transfer belt 311. The belt cleaning device 313 cleans the transfer belt 311 by scraping off and removing foreign matter such as residual toner on the transfer belt 311 using the cleaning brush and cleaning blade.

[0076] Furthermore, the belt cleaning device 313 has a discharge means for removing and disposing of residual toner removed from the transfer belt 311.

[0077] Such an image forming apparatus 300 includes the fixing device 100 according to the above embodiment. With the image forming apparatus 300 equipped with the fixing device 100, deformation of the side plate 60 can be suppressed when the core metal 31 of the pressure roller 30 undergoes thermal expansion in the X-axis direction.

[0078] Although preferred embodiments have been described in detail above, the invention is not limited to the embodiments described above, and various modifications and substitutions can be made to the embodiments described above without departing from the scope of the claims.

[0079] One aspect of the present invention may be as follows. <1> Heating section and A first rotating body that is heated by the heating section and rotates about an axis extending in a first direction, A second rotating body having a rotation axis extending in the first direction, positioned opposite the outer circumferential surface of the first rotating body, and forming a fixing nip portion through which the recording medium passes between it and the outer circumferential surface of the first rotating body, A bearing that rotatably supports the rotation shaft of the second rotating body, A bearing retaining member that holds the bearing, It comprises a pair of side plates that are spaced apart in the first direction and hold the bearing retaining member, The bearing holding member is a fixing unit having a first position adjustment section that can adjust the position of the bearing in the first direction. <2> Heating section and A first rotating body that is heated by the heating section and rotates about an axis extending in a first direction, A second rotating body having a rotation axis extending in the first direction, positioned opposite the outer circumferential surface of the first rotating body, and forming a fixing nip portion through which the recording medium passes between it and the outer circumferential surface of the first rotating body, A bearing that rotatably supports the rotation shaft of the second rotating body, A bearing retaining member that holds the bearing, It comprises a pair of side plates that are spaced apart in the first direction and hold the bearing retaining member, The bearing holding member is a fixing unit that is held so as to be movable in the first direction relative to the side plate. <3> The bearing retaining member is formed from an insulating material. <1> or <2> The fixing unit described above. <4> The above <1> ~ <3> An image forming apparatus comprising a fixing unit as described in any one of the following. [Explanation of symbols]

[0080] 100 Fixing device (fixing unit) 10 Heater (heating section) 20 Fixing belt (first rotating body) 30 Pressure roller (second rotating body) 30a Outer surface 31. Mandrel (rotation axis of the second rotating body) 32. Rubber layer (elastic layer) 40A, 40B bearings 50A, 50B Bearing cover (bearing retaining member) 110 Fixing nip section 121 1st position adjustment section 122 Second position adjustment section XX axis direction (first direction) YY axis direction ZZ axis direction [Prior art documents] [Patent Documents]

[0081] [Patent Document 1] Japanese Patent Publication No. 2007-298829

Claims

1. Heating section and A first rotating body that is heated by the heating unit and rotates about an axis extending in the first direction, A second rotating body having a rotation axis extending in the first direction, positioned opposite the outer circumferential surface of the first rotating body, and forming a fixing nip portion through which the recording medium passes between it and the outer circumferential surface of the first rotating body, A bearing that rotatably supports the rotation shaft of the second rotating body, A bearing retaining member that holds the bearing, It comprises a pair of side plates that are spaced apart in the first direction and hold the bearing retaining member, The bearing holding member is a fixing unit having a first position adjustment section that can adjust the position of the bearing in the first direction.

2. Heating section and A first rotating body that is heated by the heating unit and rotates about an axis extending in the first direction, A second rotating body having a rotation axis extending in the first direction, positioned opposite the outer circumferential surface of the first rotating body, and forming a fixing nip portion through which the recording medium passes between it and the outer circumferential surface of the first rotating body, A bearing that rotatably supports the rotation shaft of the second rotating body, A bearing retaining member that holds the bearing, It comprises a pair of side plates that are spaced apart in the first direction and hold the bearing retaining member, The bearing holding member is a fixing unit that is held so as to be movable in the first direction relative to the side plate.

3. The fixing unit according to claim 1 or 2, wherein the bearing holding member is formed from an insulating material.

4. An image forming apparatus comprising the fixing unit according to claim 1 or 2.

Images