Fixing device and image forming apparatus

Abstract

To prevent temperature unevenness of a pressure member in an axial direction, compared with a case where a cross section of the pressure member in the axial direction is in the same state from one end to the other end.SOLUTION: A fixing device comprises: a heating member that, while rotating, applies heat to a recording medium onto which an image has been transferred; and a pressure member having a cylindrical body part that sandwiches the recording medium together with the heating member and, while rotating, applies pressure toward the heating member, and a plurality of projections that project from peripheral surfaces at end portions of the body part in an axial direction of the body part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a fixing device and an image forming apparatus. [Background technology]

[0002] The cooling device of Patent Document 1 comprises a cooling roller consisting of a hollow tubular member and a cooling medium transport means for transporting a cooling medium into the tubular member, and in the cooling device which cools a sheet-like member by bringing the sheet-like member into contact with the cooling roller, a turbulence generating means for generating turbulence in the cooling medium is provided on the inner wall of the tubular member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-227315 Summary of the Invention [Problem to be solved by the invention]

[0004] A fixing device that fixes an image onto a recording medium to which the image has been transferred includes a heating member that rotates and comes into contact with the recording medium to heat the image, and a pressure member that rotates and presses the recording medium against the heating member while sandwiching the recording medium between the heating member and the pressure member. The cross section of the pressure member in the axial direction of the pressure member is the same from one end to the other.

[0005] In this configuration, the recording medium is not sandwiched between the pressure member and the heating member at the end portions of the pressure member in the axial direction, so the end portions of the pressure member are always in direct contact with the heating member. This causes the temperature at the end portions of the pressure member to be higher than the temperature at the center portion of the pressure member. In other words, temperature unevenness occurs in the pressure member in the axial direction.

[0006] An object of the present disclosure is to suppress temperature unevenness of the pressing member in the axial direction compared to when the cross section of the pressing member in the axial direction is the same from one end to the other. [Means for solving the problem]

[0007] The fixing device according to the first aspect of the present disclosure is characterized by comprising a heating member that heats a recording medium onto which an image has been transferred while rotating, a cylindrical main body that sandwiches the recording medium between itself and the heating member and presses the recording medium toward the heating member while rotating, and a pressure member having a plurality of protrusions that protrude from the peripheral surface of the end portion of the main body in the axial direction of the main body.

[0008] A fixing device according to a second aspect of the present disclosure is characterized in that, in the fixing device described in the first aspect, the main body portion has an opposing portion facing the heating member and an extension portion extending outward in the axial direction from the opposing portion, and the protrusion protrudes from the outer peripheral surface of the extension portion.

[0009] A fixing device according to a third aspect of the present disclosure is characterized in that, in the fixing device described in the first aspect, the protrusions are arranged in multiple rows in the axial direction and in multiple columns in the circumferential direction of the pressure member.

[0010] A fixing device according to a fourth aspect of the present disclosure is the fixing device according to the third aspect, characterized in that the protrusions are arranged in a direction inclined with respect to the axial direction.

[0011] A fixing device according to a fifth aspect of the present disclosure is the fixing device according to the third aspect, characterized in that the protrusions are arranged in a staggered pattern with respect to the axial direction.

[0012] A fixing device according to a sixth aspect of the present disclosure is the fixing device according to the first aspect, characterized in that the protrusion is formed with a flat surface portion facing in the rotation direction of the pressure member.

[0013] A fixing device according to a seventh aspect of the present disclosure is the fixing device according to the sixth aspect, characterized in that the flat portion extends in the axial direction.

[0014] An image forming apparatus according to an eighth aspect of the present disclosure is characterized by comprising an image forming unit that forms an image on a recording medium, and a fixing device described in any one of the first to seventh aspects that fixes the image on the recording medium. [Effects of the Invention]

[0015] The fixing device according to the first aspect of the present disclosure can suppress temperature unevenness of the pressure member in the axial direction compared to when the cross section of the pressure member in the axial direction is the same from one end to the other.

[0016] In the fixing device according to the second aspect of the present disclosure, it is possible to suppress temperature unevenness of the pressure member in the axial direction, compared to when the protrusions protrude from the inner circumferential surface.

[0017] The fixing device according to the third aspect of the present disclosure can suppress temperature unevenness of the pressure member in the axial direction compared to when the protrusions are arranged in only one row in the axial direction and one column in the circumferential direction.

[0018] In the fixing device according to the fourth aspect of the present disclosure, it is possible to suppress temperature unevenness of the pressure member in the axial direction, compared to when the protrusions are arranged in a grid pattern.

[0019] In the fixing device according to the fifth aspect of the present disclosure, it is possible to suppress temperature unevenness of the pressure member in the axial direction, compared to when the protrusions are arranged in a grid pattern.

[0020] In the fixing device according to the sixth aspect of the present disclosure, it is possible to suppress temperature unevenness of the pressure member in the axial direction, compared to when the protrusions are hemispherical.

[0021] In the fixing device according to the seventh aspect of the present disclosure, temperature unevenness of the pressure member in the axial direction can be suppressed compared to when the flat portion extends in the radial direction of the rotating pressure member.

[0022] The image forming apparatus according to the eighth aspect of the present disclosure can suppress the occurrence of wrinkles on the output recording medium compared to a case where the image forming apparatus is equipped with a fixing device in which the cross section of the pressure member in the axial direction is the same from one end to the other. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic configuration diagram showing an image forming apparatus according to a first embodiment of the present disclosure. [Figure 2] 1 is a schematic configuration diagram showing an image forming unit provided in an image forming apparatus according to a first embodiment of the present disclosure. [Figure 3] 1 is a configuration diagram illustrating an entire fixing device and the like according to a first embodiment of the present disclosure. [Figure 4] FIG. 2 is a perspective view showing a pressure roll of the fixing device according to the first embodiment of the present disclosure. [Figure 5] 3A and 3B are schematic diagrams used to explain the flow of air generated around protrusions formed on the pressure roll of the fixing device according to the first embodiment of the present disclosure. [Figure 6] FIG. 10 is a perspective view showing a protrusion formed on an extension portion of a pressure roller of a fixing device according to a second embodiment of the present disclosure. [Figure 7] FIG. 11 is a perspective view showing a protrusion formed on an extension portion of a pressure roller of a fixing device according to a third embodiment of the present disclosure. [Figure 8] FIG. 10 is a perspective view showing a protrusion formed on an extension portion of a pressure roller of a fixing device according to a fourth embodiment of the present disclosure. [Figure 9] FIG. 11 is a front view showing protrusions formed on a pressure roller of a fixing device according to a fifth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0024] First Embodiment An example of a fixing device and an image forming apparatus according to an embodiment of the present disclosure will be described with reference to Figures 1 to 5. Note that arrow H shown in each figure indicates the vertical direction, i.e., the up-down direction of the device, arrow W is perpendicular to arrow H and is horizontal, i.e., the width direction of the device, and arrow D is perpendicular to arrows H and W and is horizontal, i.e., the depth direction of the device.

[0025] (Overall configuration of image forming apparatus) 1, the image forming apparatus 10 includes a housing 10a that houses various components. Inside the housing 10a, there are provided a plurality of storage sections 12 that store sheet-like recording media P, an image forming section 14 that forms an image on the recording media P, a transport section 16 that transports the recording media P from the storage sections 12 to the image forming sections 14, and a control section 20 that controls the operation of each section of the image forming apparatus 10.

[0026] [Image forming unit 14] The image forming section 14 includes image forming units 22Y, 22M, 22C, and 22K (hereinafter referred to as "22Y-22K") that form toner images of the respective colors of yellow (Y), magenta (M), cyan (C), and black (K), an intermediate transfer belt 24 onto which the toner images formed by the image forming units 22Y-22K are transferred, a primary transfer roll 26 that transfers the toner images formed by each of the image forming units 22Y-22K onto the intermediate transfer belt 24, and a secondary transfer roll 28 that transfers the toner images transferred onto the intermediate transfer belt 24 by the primary transfer roll 26 from the intermediate transfer belt 24 to a recording medium P. In the following description, when yellow, magenta, cyan, and black are not particularly distinguished from each other, the suffixes Y, M, C, and K will be omitted.

[0027] The image forming units 22 for each color are arranged above the intermediate transfer belt 24 and are aligned in the width direction. As shown in FIG. 2, each image forming unit has an image carrier 32 that rotates in the direction of the arrow in the figure.

[0028] Around the image holder 32, in order from the upstream side in the rotation direction of the image holder 32, there are provided a charging device 23 that charges the image holder 32, an exposure device 36 that exposes the image holder 32 charged by the charging device 23 to light to form an electrostatic latent image on the image holder 32, a developing device 38 that develops the electrostatic latent image formed on the image holder 32 by the exposure device 36 to form a toner image, and a removal device 40 that contacts the image holder 32 to remove toner remaining on the image holder 32.

[0029] The exposure devices 36 form electrostatic latent images based on image signals sent from the control unit 20 (see FIG. 1). As shown in FIG. 1, above the exposure devices 36 for each color, there are disposed toner storage units 39 that store toner to be supplied to the developing devices 38 of the image forming units 22.

[0030] The intermediate transfer belt 24 is formed in a triangular shape with its apex pointing downward. Winding rolls 41, 42, 43, 44, and 45, around which the intermediate transfer belt 24 is wound, are provided on the inner circumferential side of the intermediate transfer belt 24. As an example, the winding roll 43 is driven to rotate, causing the intermediate transfer belt 24 to circulate (rotate) in one direction (for example, counterclockwise in FIG. 1 ) while in contact with the image carrier 32.

[0031] The primary transfer rolls 26 of each color face the image carriers 32 with the intermediate transfer belt 24 sandwiched therebetween. The secondary transfer rolls 28 face the winding roll 42 with the intermediate transfer belt 24 sandwiched therebetween. A second transfer position is defined between the secondary transfer rolls 28 and the winding roll 42, where the toner image transferred to the intermediate transfer belt 24 is transferred to the recording medium P.

[0032] The conveying section 16 includes a feed roll 46 that feeds out the recording medium P stored in each storage section 12, and a plurality of conveying rolls 50 that convey the recording medium P sent out by the feed roll 46 along a conveying path 48 along which the recording medium P is conveyed to a second transfer position.

[0033] A belt conveying section 59 is provided downstream of the second transfer position in the conveying direction of the recording medium P (hereinafter referred to as the "medium conveying direction") to convey the recording medium P onto which the toner image has been transferred by the secondary transfer roll 28. Furthermore, a fixing device 60 is provided downstream of the belt conveying section 59 in the medium conveying direction to fix the toner image transferred to the recording medium P onto the recording medium P.

[0034] Furthermore, on the downstream side in the medium transport direction of the fixing device 60, there are provided discharge rolls 52 that discharge the recording medium P on which the toner image has been fixed from the housing 10a. The fixing device 60 will be described in detail later.

[0035] (Image formation operation) Next, an image forming operation for forming an image on the recording medium P in the image forming apparatus 10 according to this embodiment will be described.

[0036] In the image forming apparatus 10, the recording medium P is sent out from the storage unit 12 by a sending roll 46, and is sent to a second transfer position by a plurality of transport rolls 50 (see FIG. 1).

[0037] Meanwhile, in the image forming units 22 for each color, the image carrier 32 charged by the charging device 23 is exposed by the exposure device 36 to form an electrostatic latent image on the image carrier 32 (see FIG. 2). The electrostatic latent image is then developed by the developing device 38 to form a toner image on the image carrier 32.

[0038] The toner images of each color formed by the image forming units 22 are superimposed on the intermediate transfer belt 24 at the first transfer position by the primary transfer rolls 26 of each color, forming a color image. Then, the color image formed on the intermediate transfer belt 24 is transferred to the recording medium P by the secondary transfer roll 28.

[0039] The recording medium P onto which the toner image has been transferred is transported by a belt transport unit 59 to a fixing device 60, where the transferred toner image is fixed. The recording medium P onto which the toner image has been fixed is discharged from the housing 10a by a discharge roll 52.

[0040] (Main part configuration) Next, the configuration of the fixing device 60 and other components according to this embodiment will be described. 3, the fixing device 60 includes a heating member 62, a pressure roll 65, a housing 80, and a cooling fan 76. The pressure roll 65 is an example of a pressure member. [Housing 80] 3, the housing 80 has an upper housing 90 that houses the heating member 62 therein, and a lower housing 88 that houses the pressure roll 65. The space between the upper housing 90 and the lower housing 88 forms the transport path 48.

[0041] [Heating member 62] As shown in FIG. 3, the heating member 62 includes a fixing belt 64, a pad member 68 around which the fixing belt 64 is wound, a first heating roll 69, and a second heating roll 67.

[0042] The fixing belt 64 is, for example, an endless loop made of a polyamide base material coated with a fluororesin, and is driven by the pressure roll 65 to move in one direction (counterclockwise in FIG. 3).

[0043] The pad member 68 extends in the depth direction and receives a pressing (nip) load from the pressure roll 65, thereby forming a nip portion N between the fixing belt 64 and the pressure roll 65. A halogen heater 68a is provided inside the pad member 68.

[0044] The first heating roll 69 has its rotation axis direction as its depth direction, and is disposed downstream of the pad member 68 in the rotation direction of the fixing belt 64. The first heating roll 69 is cylindrical, and a halogen heater 69a is provided inside the first heating roll 69.

[0045] The second heating roll 67 has its rotation axis direction as the depth direction, and is disposed downstream of the first heating roll 69 in the rotation direction of the fixing belt 64. The second heating roll 67 is cylindrical, and a heat source such as a halogen heater 67a is provided inside the second heating roll 67.

[0046] [Pressure roll 65] 4, the pressure roll 65 has an axial direction as the depth direction, and includes a cylindrical main body 66 and a shaft 72 that forms a rotation axis and extends in the depth direction. The pressure roll 65 further includes disk-shaped support members 74 provided at both ends of the main body 66 and that support the main body 66 on the shaft 72, and protrusions 70.

[0047] The main body 66 includes a facing portion 66a facing the heating member 62 and an extension portion 66b extending outward in the depth direction from the facing portion 66a, and the protrusion 70 protrudes from the outer circumferential surface of the extension portion 66b. Here, the facing portion 66a is the portion that faces the heating member 62 and overlaps with the heating member 62 in the depth direction.

[0048] -Opposing part 66a, extension part 66b- The facing portion 66a is configured by covering the outer periphery of a cylindrical member made of aluminum alloy with an elastic layer made of silicone rubber, whereas the extension portion 66b is not provided with an elastic layer made of silicone rubber, and the outer periphery of the cylindrical aluminum alloy is exposed to the outside.

[0049] -Protrusion 70- The protrusions 70 are made of an aluminum alloy and are provided in multiple rows in the depth direction (four rows in this embodiment, as an example) and in multiple columns in the circumferential direction of the main body 66 (hereinafter referred to as the "roll circumferential direction"). The protrusions 70 are rectangular parallelepipeds extending in the depth direction, and are formed with rectangular flat portions 70a that face the rotation direction of the pressure roll 65 and extend in the depth direction. Here, in this embodiment, the flat portion is a surface whose edge is in contact with the extension portion 66b and that faces the tangent direction at the contact point between the flat portion and the main body when viewed from the depth direction (axial direction).

[0050] In this embodiment, the protrusions 70 are provided in four rows in the depth direction. One protrusion 70 is spaced apart from another protrusion 70 in an adjacent row in the depth direction, and they are arranged at equal intervals in the depth direction. Furthermore, the protrusions 70 in each row are arranged at equal intervals in the circumferential direction of the roll. The depth direction is an example of the axial direction.

[0051] Specifically, the Nth row of protrusions 70 are spaced apart in the depth direction from the N±1th rows of protrusions 70 and are arranged in a direction inclined with respect to the depth direction. Here, "the protrusions are arranged in a direction inclined with respect to the depth direction" means that the protrusions are not arranged in the depth direction and are arranged only in a direction inclined with respect to the depth direction.

[0052] -Support member 74- The support member 74 is disk-shaped, and has a plurality of through-holes 74 a that penetrate from the front to the back and surround the shaft 72 .

[0053] [Cooling fan 76] 3 and 4, a plurality of cooling fans 76 are provided lined up in the depth direction and are arranged to face the lower end portion of the main body 66 of the pressure roll 65 when viewed from the depth direction. The cooling fans 76 blow air onto the part of the rotating main body 66 that approaches the cooling fans 76.

[0054] (Function of main components) Next, the fixing operation for fixing the toner image formed on the recording medium P to the recording medium P will be described. 3 receives a driving force from a driving source (not shown) and rotates, whereby the fixing belt 64 provided on the heating member 62 rotates following the rotation of the pressure roll 65, and the first heating roll 69 and the second heating roll 67 rotate following the rotation of the fixing belt 64.

[0055] Furthermore, the halogen heaters 67a, 68a, and 69a are operated, and the rotating fixing belt 64 is heated by the first heating roll 69, the second heating roll 67, and the pad member 68. Furthermore, the cooling fan 76 is operated.

[0056] Then, when the fixing belt 64 is heated to a predetermined temperature, the fixing device 60 conveys the recording medium P, onto which the toner image has been transferred, while applying heat and pressure to the recording medium P in the nip N formed by the pressure roll 65 and the fixing belt 64 of the heating member 62. This fixes the toner image to the recording medium P. Furthermore, the operating cooling fan 76 cools the pressure roll 65.

[0057] In this fixing operation, the facing portion 66a of the rotating main body portion 66 is heated by the rotating fixing belt 64. Here, at both end portions of the facing portion 66a in the depth direction, the recording medium P is not sandwiched between the facing portion 66a and the fixing belt 64, so the temperature of the end portions of the facing portion 66a in the depth direction (axial direction) is higher than the temperature of the central portion of the facing portion 66a in the axial direction. In other words, temperature unevenness occurs in the main body portion 66 of the pressure roll 65. Macroscopically, temperature unevenness occurs in the pressure roll 65. Here, the end portions are the portions of the pressure roll 65 that are always in direct contact with the fixing belt 64 of the heating member 62 when fixing the toner image formed on the recording medium P with the highest usage to the recording medium P.

[0058] Hereinafter, an operation for suppressing temperature unevenness occurring in the main body 66 of the pressure roll 65 (pressure roll 65) will be described. The rotation of the pressure roll 65 also rotates the protrusions 70 provided on the extension portion 66b. As described above, the Nth row of protrusions 70 is spaced apart in the depth direction from the N±1th rows of protrusions 70, and the protrusions 70 adjacent to each other in the depth direction are arranged in a direction inclined with respect to the depth direction.

[0059] For this reason, as the pressure roll 65 rotates, air hits the protrusions 70, generating turbulence (the spiral curves shown in the figure) around the protrusions 70, as shown in Figure 5. For the protrusions 70 arranged in a direction inclined relative to the depth direction, the turbulence intensity of the turbulence generated at the leading protrusion 70 in the circumferential direction of the roll increases as it hits the next protrusion 70 in the circumferential direction of the roll. By repeating this process, the turbulence intensity increases.

[0060] The heat from the heated end portion of the facing portion 66a is dissipated by the protrusions 70 provided on the extension portion 66b, thereby suppressing temperature unevenness in the depth direction of the pressure roll 65. In this way, the protrusions 70 function as heat dissipation fins.

[0061] (summary) As described above, in the fixing device 60, a plurality of protrusions 70 are formed on the extension portion 66b of the pressure roll 65. This reduces temperature unevenness in the depth direction of the pressure roll 65 compared to when the cross section of the pressure roll in the depth direction is the same from one end to the other. In other words, compared to when the pressure roll does not have any protrusions, temperature unevenness in the depth direction of the pressure roll 65 is reduced.

[0062] In the fixing device 60, the protrusions 70 protrude from the outer peripheral surface of the extension portion 66b. Compared to when the protrusions protrude from the inner peripheral surface of the pressure roll, the peripheral speed of the protrusions is faster, thereby suppressing temperature unevenness in the depth direction of the pressure roll 65.

[0063] In the fixing device 60, the protrusions 70 are provided in multiple rows in the depth direction and in multiple columns in the circumferential direction of the pressure roll 65. This reduces temperature unevenness in the depth direction of the pressure roll 65 compared to when only one row of protrusions is provided in the depth direction.

[0064] In the fixing device 60, the protrusions 70 are arranged in a direction inclined with respect to the depth direction. Compared to when the protrusions are arranged in the depth direction (axial direction), the air flowing on the outer peripheral surface of the extension portion 66b becomes turbulent, and the turbulence strength is improved, thereby suppressing temperature unevenness in the depth direction of the pressure roll 65.

[0065] In the fixing device 60, the protrusions 70 are arranged in a direction inclined with respect to the depth direction. Compared to when the protrusions are arranged in a grid pattern, the air flowing on the outer peripheral surface of the extension 66b becomes turbulent, and the turbulence strength is improved, thereby suppressing temperature unevenness in the depth direction of the pressure roll 65.

[0066] Furthermore, in the fixing device 60, the protrusions 70 are formed with flat portions 70a facing the rotation direction of the pressure roll 65. As a result, compared to when the protrusions are hemispherical, the air resistance experienced by the protrusions 70 is greater, improving the heat dissipation effect and suppressing temperature unevenness occurring in the depth direction of the pressure roll 65.

[0067] Furthermore, in the fixing device 60, the flat surface 70a of the protrusion 70 extends in the depth direction. As a result, the length of contact between the flat surface 70a and the extension 66b is longer than when the flat surface extends in the radial direction of the rotating pressure roll, which improves the heat dissipation effect and suppresses temperature unevenness in the depth direction that occurs in the main body 66 of the pressure roll 65.

[0068] Furthermore, in the fixing device 60, the temperature unevenness occurring in the depth direction of the main body 66 of the pressure roll 65 is suppressed, and the output of the cooling fan 76 is weakened.

[0069] Furthermore, in the image forming apparatus 10, by providing the fixing device 60, the temperature unevenness in the depth direction that occurs in the pressure roll 65 is suppressed compared to when the cross section of the pressure roll in the depth direction is provided with the same fixing device from one end to the other, thereby suppressing wrinkles that occur in the output recording medium P.

[0070] Second Embodiment Next, an example of a fixing device 160 and an image forming apparatus according to a second embodiment will be described with reference to Fig. 6. Note that, with regard to the second embodiment, differences from the first embodiment will be mainly described.

[0071] As shown in Fig. 6, protrusions 70 are formed on the extension portion 66b of the pressure roll 165 of the fixing device 160 according to the second embodiment. The protrusions 70 are arranged in a staggered pattern in the depth direction. The operation of the second embodiment is the same as that of the first embodiment.

[0072] Third Embodiment Next, an example of a fixing device 260 and an image forming apparatus according to a third embodiment will be described with reference to Fig. 7. Note that, with regard to the third embodiment, differences from the first embodiment will be mainly described.

[0073] 7, a protrusion 270 is formed on the extension portion 66b of the pressure roll 265 of the fixing device 260 according to the third embodiment. The protrusion 270 has a cylindrical shape and extends in the radial direction of the rotating pressure roll 265.

[0074] The operation of the third embodiment is the same as that of the first embodiment except for the operation achieved by forming a flat surface portion facing the rotation direction on the projection.

[0075] <Fourth embodiment> Next, an example of a fixing device 360 ​​and an image forming apparatus according to a fourth embodiment will be described with reference to Fig. 8. Note that, with regard to the fourth embodiment, differences from the first embodiment will be mainly described.

[0076] 8, a protrusion 370 is formed on the extension portion 66b of the pressure roll 365 of the fixing device 360 ​​according to the fourth embodiment. The protrusion 370 has a hemispherical shape and protrudes in the radial direction of the rotating pressure roll 365.

[0077] The operation of the fourth embodiment is the same as that of the first embodiment except for the operation achieved by forming a flat surface portion facing the rotation direction on the projection.

[0078] Fifth Embodiment Next, an example of a fixing device 460 and an image forming apparatus according to a fifth embodiment will be described with reference to Fig. 9. Note that, with regard to the fifth embodiment, differences from the first embodiment will be mainly described.

[0079] The pressure roll 465 of the fixing device 460 according to the fifth embodiment does not have an extension. As shown in Fig. 9, the protrusion 470 protrudes from the inner circumferential surface of the end portion of the opposing portion 66a of the pressure roll 465. The protrusion 470 directly dissipates heat from the heated end portion of the opposing portion 66a.

[0080] Other functions of the fifth embodiment are the same as those of the first embodiment except for the functions achieved by forming the protrusions on the outer peripheral surface.

[0081] Although the present disclosure has been described in detail with respect to specific embodiments, it will be apparent to those skilled in the art that the present disclosure is not limited to such embodiments and that various other embodiments are possible within the scope of the present disclosure. For example, in the above embodiment, the protrusions 70, 270, 370, and 470 are provided in multiple rows in the depth direction, but they may also be provided in a single row. However, in this case, the effect achieved by providing multiple rows will not be achieved.

[0082] In the above embodiment, the protrusions 70, 270, 370, 470 are provided in multiple rows in the circumferential direction of the pressure roll, but they may be provided in a single row. In this case, however, the effect achieved by providing multiple rows will not be achieved.

[0083] Furthermore, in the above embodiment, the protrusions 70, 270, 370, 470 are provided in multiple rows in the depth direction and in multiple columns in the circumferential direction of the pressure roll, but multiple protrusions may also be provided randomly (without regularity).

[0084] In the above embodiment, the protrusions 70, 370, 470 are arranged in a direction inclined with respect to the depth direction, but the protrusions may be arranged in a grid pattern. In this case, however, the effect achieved by arranging the protrusions in a direction inclined with respect to the depth direction will not be achieved.

[0085] In the above embodiment, the protrusions 70, 270 are rectangular parallelepiped shaped, but they may have other shapes, in which case the effect achieved by the protrusions being rectangular parallelepiped will not be achieved.

[0086] (((1))) a heating member that heats the recording medium onto which the image has been transferred while rotating; a pressure member having a cylindrical main body that sandwiches the recording medium between itself and the heating member and presses the recording medium toward the heating member while rotating, and a plurality of protrusions that protrude from a peripheral surface of an end portion of the main body in the axial direction of the main body; A fixing device comprising:

[0087] (((2))) the main body portion includes a facing portion facing the heating member and an extension portion extending outward in the axial direction from the facing portion; The protrusion protrudes from the outer circumferential surface of the extension portion. The fixing device according to (((1))).

[0088] (((3))) The protrusions are provided in a plurality of rows in the axial direction and in a plurality of columns in the circumferential direction of the pressure member. The fixing device according to (((1))).

[0089] (((4))) The protrusions are arranged in a direction inclined with respect to the axial direction. The fixing device according to any one of (((1))) to (((3))).

[0090] (((5))) The protrusions are arranged in a staggered pattern with respect to the axial direction. The fixing device according to any one of (((1))) to (((3))).

[0091] (((6))) The protrusion has a flat surface formed thereon that faces the rotation direction of the pressure member. The fixing device according to any one of (((1))) to (((5))).

[0092] (((7))) The flat portion extends in the axial direction. The fixing device according to (((6))).

[0093] (((8))) an image forming unit that forms an image on a recording medium; A fixing device according to any one of (((1))) to (((7))) that fixes an image on a recording medium; An image forming apparatus comprising:

[0094] In the fixing device according to (((1))), the temperature unevenness of the pressure member in the axial direction can be suppressed compared to when the cross section of the pressure member in the axial direction is the same from one end to the other.

[0095] In the fixing device according to (((2))), it is possible to suppress temperature unevenness of the pressure member in the axial direction, compared to when the protrusions protrude from the inner circumferential surface.

[0096] In the fixing device according to (((3))), the temperature unevenness of the pressure member in the axial direction can be suppressed compared to when the protrusions are provided in only one row in the axial direction and one row in the circumferential direction.

[0097] In the fixing device according to (((4))), it is possible to suppress temperature unevenness of the pressure member in the axial direction, compared to when the protrusions are arranged in a grid pattern.

[0098] In the fixing device according to (((5))), it is possible to suppress temperature unevenness of the pressure member in the axial direction, compared to when the protrusions are arranged in a grid pattern.

[0099] In the fixing device according to (((6))), the temperature unevenness of the pressure member in the axial direction can be suppressed compared to when the protrusions are hemispherical.

[0100] In the fixing device according to (((7))), the temperature unevenness of the pressure member in the axial direction can be suppressed compared to when the flat portion extends in the radial direction of the rotating pressure member.

[0101] In the image forming apparatus according to (((8))), the occurrence of wrinkles on the output recording medium can be suppressed compared to a case where the image forming apparatus is equipped with a fixing device in which the cross section of the pressure member in the axial direction is the same from one end to the other. [Explanation of symbols]

[0102] 10 Image forming device 14 Image forming unit 60 Fixing device 62 Heating element 65 Pressure roll (an example of a pressure member) 66 Main body 66a Opposite part 66b Extension 70 protrusions 70a flat part 160 Fixing device 165 Pressure roll (an example of a pressure member) 260 Fixing device 265 Pressure roll (an example of a pressure member) 270 Protrusion 360 Fixing device 365 Pressure roll (an example of a pressure member) 370 Protrusion 460 Fixing device 465 Pressure roll (an example of a pressure member) 470 Protrusion

Claims

1. a heating member that heats the recording medium onto which the image has been transferred while rotating; a pressure member having a cylindrical main body that sandwiches the recording medium between itself and the heating member and presses the recording medium toward the heating member while rotating, and a plurality of protrusions that protrude from a peripheral surface of an end portion of the main body in the axial direction of the main body; A fixing device comprising:

2. the main body portion includes a facing portion facing the heating member and an extension portion extending outward in the axial direction from the facing portion; The protrusion protrudes from the outer circumferential surface of the extension portion. The fixing device according to claim 1 .

3. The protrusions are provided in a plurality of rows in the axial direction and in a plurality of columns in the circumferential direction of the pressure member. The fixing device according to claim 1 .

4. The protrusions are arranged in a direction inclined with respect to the axial direction. The fixing device according to claim 3 .

5. The protrusions are arranged in a staggered pattern with respect to the axial direction. The fixing device according to claim 3 .

6. The protrusion has a flat surface formed thereon that faces the rotation direction of the pressure member. The fixing device according to claim 1 .

7. The flat portion extends in the axial direction. The fixing device according to claim 6 .

8. an image forming unit that forms an image on a recording medium; The fixing device according to any one of claims 1 to 7, which fixes an image on a recording medium; An image forming apparatus comprising:

Images