Fixing device and image forming apparatus

Abstract

A fixing device and an image forming apparatus, the fixing device including: a heating member that rotates and heats a recording medium to which an image is transferred; and a pressurizing member having: a cylindrical main body portion that sandwiches the recording medium between the heating member and the pressurizing member, and that pressurizes the recording medium toward the heating member while rotating; and a plurality of protrusions protruding from the circumferential surface of the end portion of the main body portion in the axial direction of the main body portion.

Description

Technical Field

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

[0002] The cooling device of Patent Document 1 includes a cooling roller composed of a hollow tubular member and a cooling medium conveying member that conveys a cooling medium into the tubular member. In the cooling device that cools a sheet member by bringing the sheet member into contact with the cooling roller, a turbulence generating member that causes turbulence in the cooling medium is provided on the inner wall of the tubular member.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-227315

[0004] A fixing device for fixing an image onto a recording medium to which the image has been transferred comprises: a heating member that rotates while contacting the recording medium to heat the image; and a pressing member that holds the recording medium between the heating member and the heating member and presses the recording medium against the heating member while rotating. The cross-section of the pressing member in the axial direction is uniform from one end to the other.

[0005] In this configuration, the ends of the pressure member in the axial direction do not sandwich the recording medium between them and the heating member, so they are always in direct contact with the heating member. Consequently, the temperature of the ends of the pressure member becomes higher than that of the central portion of the pressure member. In other words, temperature unevenness occurs within the pressure member in the axial direction. Summary of the Invention

[0006] An object of the present invention is to suppress temperature unevenness of a pressurizing member in the axial direction, compared to a case where the cross section of the pressurizing member in the axial direction is uniform from one end to the other end.

[0007] A fixing device according to a first aspect of the present invention is characterized by comprising:

[0008] a heating member that rotates while heating the recording medium to which the image is transferred; and

[0009] The pressurizing member comprises: a cylindrical main body portion that clamps the recording medium between the main body portion and the heating member and pressurizes the recording medium toward the heating member while rotating; and a plurality of protrusions that protrude from the peripheral surface of the end portion of the main body portion in the axial direction of the main body portion.

[0010] A fixing device according to a second aspect of the present invention is characterized in that, in the fixing device according to the first aspect,

[0011] The main body includes an opposing portion opposing the heating member and an extension portion extending outward from the opposing portion in the axial direction.

[0012] The protrusion protrudes from the outer peripheral surface of the extension portion.

[0013] A fixing device according to a third aspect of the present invention is the fixing device according to the first aspect, characterized in that:

[0014] The protrusions are arranged in a plurality of rows in the axial direction and in a plurality of columns in the circumferential direction of the pressurizing member.

[0015] A fixing device according to a fourth aspect of the present invention is the fixing device according to any one of the first to third aspects, characterized in that:

[0016] The protrusions are arranged in a direction inclined with respect to the axial direction.

[0017] A fixing device according to a fifth aspect of the present invention is the fixing device according to any one of the first to third aspects, characterized in that:

[0018] The protrusions are arranged in a staggered pattern with respect to the axial direction.

[0019] A fixing device according to a sixth aspect of the present invention is the fixing device according to any one of the first to fifth aspects, characterized in that:

[0020] The protrusion is formed with a flat surface portion facing the rotation direction of the pressing member.

[0021] A fixing device according to a seventh aspect of the present invention is the fixing device according to the sixth aspect, characterized in that:

[0022] The planar portion extends along the axial direction.

[0023] An image forming apparatus according to an eighth aspect of the present invention is characterized by comprising:

[0024] an image forming unit that forms an image on a recording medium; and

[0025] The fixing device according to any one of the first to seventh aspects fixes an image on a recording medium.

[0026] Effects of the Invention

[0027] The fixing device according to the first aspect of the present invention can suppress temperature variations of the pressure member in the axial direction, compared to a case where the cross section of the pressure member in the axial direction is uniform from one end to the other end.

[0028] The fixing device according to the second aspect of the present invention can suppress temperature variations of the pressure member in the axial direction, compared to a case where the protrusion protrudes from the inner peripheral surface.

[0029] The fixing device according to the third aspect of the present invention can suppress temperature variations of the pressure member in the axial direction, compared to a case where the protrusions are provided in only one row in the axial direction and in only one column in the circumferential direction.

[0030] The fixing device according to the fourth aspect of the present invention can suppress temperature variations of the pressure member in the axial direction, compared to a case where the protrusions are arranged in a grid pattern.

[0031] The fixing device according to the fifth aspect of the present invention can suppress temperature variations of the pressure member in the axial direction, compared to a case where the projections are arranged in a grid pattern.

[0032] The fixing device according to the sixth aspect of the present invention can suppress temperature variations of the pressure member in the axial direction, compared to a case where the protrusion is hemispherical.

[0033] The fixing device according to the seventh aspect of the present invention can suppress temperature variations of the pressure member in the axial direction, compared to a case where the flat surface portion extends in the radial direction of the rotating pressure member.

[0034] The image forming apparatus according to the eighth aspect of the present invention can suppress the occurrence of wrinkles in the output recording medium, compared to a fixing device including a pressure member having a uniform cross-section from one end to the other in the axial direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0036] Figure 1 is a schematic structural diagram showing an image forming apparatus according to a first embodiment of the present invention;

[0037] Figure 2 is a schematic structural diagram showing an image forming unit included in an image forming apparatus according to a first embodiment of the present invention;

[0038] Figure 3 1 is a diagram showing the overall structure of a fixing device and the like according to a first embodiment of the present invention;

[0039] Figure 4 is a perspective view showing a pressure roller of the fixing device according to the first embodiment of the present invention;

[0040] Figure 5 Schematic diagram for explaining air flow generated around a protrusion formed on a pressure roller of a fixing device according to a first embodiment of the present invention;

[0041] Figure 6is a perspective view showing a protrusion formed on an extended portion of a pressure roller in a fixing device according to a second embodiment of the present invention;

[0042] Figure 7 is a perspective view showing a protrusion formed on an extended portion of a pressure roller in a fixing device according to a third embodiment of the present invention;

[0043] Figure 8 1 is a perspective view showing a protrusion formed on an extended portion of a pressure roller in a fixing device according to a fourth embodiment of the present invention;

[0044] Figure 9 This is a front view showing a protrusion formed on a pressure roller of a fixing device according to a fifth embodiment of the present invention.

[0045] Explanation of symbols

[0046] 10-image forming device, 14-image forming portion, 60-fixing device, 62-heating component, 65-pressure roller (an example of a pressure component), 66-main body, 66a-opposing portion, 66b-extension portion, 70-protrusion, 70a-flat surface portion, 160-fixing device, 165-pressure roller (an example of a pressure component), 260-fixing device, 265-pressure roller (an example of a pressure component), 270-protrusion, 360-fixing device, 365-pressure roller (an example of a pressure component), 370-protrusion, 460-fixing device, 465-pressure roller (an example of a pressure component), 470-protrusion. DETAILED DESCRIPTION

[0047] <First embodiment>

[0048] according to Figures 1 to 5 An example of a fixing device and an image forming apparatus according to an embodiment of the present invention will be described. In each figure, arrow H is a vertical direction indicating the vertical direction of the apparatus, arrow W is a horizontal direction perpendicular to arrow H and indicating the width direction of the apparatus, and arrow D is a horizontal direction perpendicular to arrows H and W and indicating the depth direction of the apparatus.

[0049] (Overall Structure of Image Forming Apparatus)

[0050] like Figure 1 As shown, the image forming apparatus 10 includes a housing 10a that houses various components. Disposed within the housing 10a are a plurality of storage sections 12 for storing sheet-like recording media P, an image forming section 14 for forming images on the recording media P, a transport section 16 for transporting the recording media P from the storage sections 12 to the image forming section 14, and a control section 20 for controlling the operation of various components of the image forming apparatus 10.

[0051] [Image Forming Unit 14]

[0052] 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 yellow (Y), magenta (M), cyan (C), and black (K); an intermediate transfer belt 24 to which the toner images formed by the image forming units 22Y-22K are transferred; a primary transfer roller 26 that transfers the toner images formed by the image forming units 22Y-22K onto the intermediate transfer belt 24; and a secondary transfer roller 28 that transfers the toner images transferred to the intermediate transfer belt 24 by the primary transfer roller 26 from the intermediate transfer belt 24 to a recording medium P. In the following description, the suffixes Y, M, C, and K are omitted unless they are specifically distinguished between yellow, magenta, cyan, and black.

[0053] The image forming units 22 of each color are arranged on the upper side of the intermediate transfer belt 24 and arranged in the width direction. Figure 2 As shown, each image forming unit includes an image holding member 32 that rotates in the direction of the arrow in the figure.

[0054] Around the image retainer 32, there are arranged in sequence from the upstream side in the rotation direction of the image retainer 32 a charging device 23 for charging the image retainer 32, an exposure device 36 for exposing the image retainer 32 charged by the charging device 23 to form an electrostatic latent image on the image retainer 32, a developing device 38 for developing the electrostatic latent image formed on the image retainer 32 by the exposure device 36 to form a toner image, and a removal device 40 for contacting the image retainer 32 to remove the toner remaining on the image retainer 32.

[0055] The exposure device 36 is operated according to the control unit 20 (reference Figure 1 ) to form an electrostatic latent image. Figure 1 As shown, above the exposure device 36 of each color, a toner container 39 for storing toner to be supplied to the developing device 38 of the image forming unit 22 is arranged.

[0056] The intermediate transfer belt 24 is formed into a triangular shape with its apex facing downward. Winding rollers 41, 42, 43, 44, and 45 are provided on the inner circumference of the intermediate transfer belt 24 to wind up the intermediate transfer belt 24. For example, the intermediate transfer belt 24 is rotated by the winding roller 43, and is moved in one direction (for example, Figure 1 Circular movement (rotation) in the counterclockwise direction.

[0057] The primary transfer rollers 26 for each color are positioned opposite to the image holders 32 with the intermediate transfer belt 24 interposed therebetween. The secondary transfer roller 28 is positioned opposite to the take-up roller 42 with the intermediate transfer belt 24 interposed therebetween. A second transfer position is provided between the secondary transfer roller 28 and the take-up roller 42, where the toner image transferred onto the intermediate transfer belt 24 is transferred onto the recording medium P.

[0058] The transport section 16 includes a feed roller 46 for feeding out the recording medium P accommodated in each accommodation section 12 and a plurality of transport rollers 50 for transporting the recording medium P fed out by the feed roller 46 to the second transfer position along a transport path 48 for transporting the recording medium P.

[0059] A belt conveyor 59 is provided downstream of the second transfer position in the conveyance direction of the recording medium P (hereinafter referred to as the "medium conveyance direction") for conveying the recording medium P to which the toner image has been transferred by the secondary transfer roller 28. Furthermore, a fixing device 60 is provided downstream of the belt conveyor 59 in the medium conveyance direction for fixing the toner image transferred to the recording medium P to the recording medium P.

[0060] Furthermore, a discharge roller 52 for discharging the recording medium P with the toner image fixed thereon from the housing 10a is provided downstream of the fixing device 60 in the medium conveying direction. The fixing device 60 will be described in detail later.

[0061] (Image Formation Operation)

[0062] Next, an image forming operation of forming an image on the recording medium P in the image forming apparatus 10 according to the present embodiment will be described.

[0063] In the image forming apparatus 10, the recording medium P fed out from the storage portion 12 by the feed roller 46 is fed to the second transfer position (see FIG. 1 ) by the plurality of conveying rollers 50. Figure 1 ).

[0064] On the other hand, in the image forming unit 22 of each color, the image holding member 32 charged by the charging device 23 is exposed by the exposure device 36, and an electrostatic latent image is formed on the image holding member 32 (refer to FIG. Figure 2 ). Then, the electrostatic latent image is developed by the developing device 38 and forms a toner image on the image holding member 32.

[0065] The toner images of each color formed in the image forming unit 22 are superimposed on the intermediate transfer belt 24 at the first transfer position by the primary transfer rollers 26 of each color, thereby forming a color image. The color image formed on the intermediate transfer belt 24 is then transferred to the recording medium P by the secondary transfer rollers 28.

[0066] The recording medium P with the transferred toner image is conveyed to the fixing device 60 by the belt conveyor 59, and the transferred toner image is fixed by the fixing device 60. The recording medium P with the fixed toner image is discharged from the housing 10a by the discharge roller 52.

[0067] (Structure of the main part)

[0068] Next, the structure of the fixing device 60 and the like according to this embodiment will be described.

[0069] like Figure 3 As shown, the fixing device 60 includes a heating member 62, a pressure roller 65, a housing 80, and a cooling fan 76. The pressure roller 65 is an example of a pressure member.

[0070] [Frame 80]

[0071] like Figure 3 As shown, the housing 80 includes an upper housing 90 that houses the heating member 62 and a lower housing 88 that houses the pressure roller 65. A conveying path 48 is defined between the upper housing 90 and the lower housing 88.

[0072] [Heating element 62]

[0073] like Figure 3 As shown, the heating member 62 includes a fixing belt 64 , a pad member 68 around which the fixing belt 64 is wound, a first heating roller 69 , and a second heating roller 67 .

[0074] As an example, the fixing belt 64 is formed by coating a fluororesin on the surface of a base material composed of polyamide, and forming an endless (loop-shaped) shape. Then, the fixing belt 64 is driven by the pressure roller 65 in one direction ( Figure 3 counterclockwise in the circle).

[0075] The pad member 68 extends in the depth direction and forms a nip portion N between the fixing belt 64 and the pressure roller 65 by receiving a pressing (nipping) load from the pressure roller 65 . A halogen heater 68 a is provided inside the pad member 68 .

[0076] The first heating roller 69 is arranged downstream of the pad member 68 in the rotation direction of the fixing belt 64 with its rotation axis in the depth direction. The first heating roller 69 is cylindrical and has a halogen heater 69a provided therein.

[0077] The second heating roller 67 is arranged downstream of the first heating roller 69 in the rotation direction of the fixing belt 64, with its rotation axis in the depth direction. The second heating roller 67 is cylindrical and has a heat source such as a halogen heater 67a provided therein.

[0078] [Pressure roller 65]

[0079] like Figure 4 As shown, the pressure roller 65 includes a main body 66 having a cylindrical shape with the axial direction being the depth direction, and a shaft 72 that serves as a rotation axis and extends in the depth direction. Furthermore, the pressure roller 65 includes disc-shaped support members 74 and protrusions 70 that are provided at both ends of the main body 66 and support the main body 66 on the shaft 72.

[0080] The main body 66 includes an opposing portion 66a that opposes the heating member 62 and an extension portion 66b that extends outward from the opposing portion 66a in the depth direction. The protrusion 70 protrudes from the outer peripheral surface of the extension portion 66b. Here, the opposing portion 66a is the portion that opposes the heating member 62 and overlaps with the heating member 62 in the depth direction.

[0081] [Opposing portion 66a, extended portion 66b]

[0082] The facing portion 66a is formed by coating the outer periphery of an aluminum alloy cylindrical member with a silicone rubber elastic layer. On the other hand, the extended portion 66b is not provided with a silicone rubber elastic layer, and the outer periphery of the aluminum alloy cylindrical member is exposed to the outside.

[0083] [Protrusion 70]

[0084] The protrusions 70 are made of aluminum alloy and are arranged in multiple rows (four rows, as an example, in this embodiment) along the depth direction, and in multiple columns along the circumference of the main body 66 (hereinafter referred to as the "roller circumferential direction"). The protrusions 70 are rectangular parallelepiped-shaped, extending in the depth direction. A rectangular flat surface portion 70a is formed on the protrusion 70, extending in the depth direction and oriented in the direction of rotation of the pressure roller 65. In this embodiment, the flat surface portion refers to the surface whose edge contacts the extension 66b and, when viewed in the depth direction (axial direction), faces a tangent to the point of contact between the flat surface portion and the main body.

[0085] In this embodiment, the protrusions 70 are arranged in four rows in the depth direction. Each protrusion 70 is separated from the other protrusions 70 in the adjacent row in the depth direction and arranged at equal intervals in the depth direction. Furthermore, the protrusions 70 in each row are arranged at equal intervals in the roller circumferential direction. The depth direction is an example of the axial direction.

[0086] Specifically, the protrusions 70 in the Nth row are separated in the depth direction from the protrusions 70 in the N±1th rows and are arranged in a direction oblique to the depth direction. Here, "the protrusions are arranged in a direction oblique to the depth direction" means that the protrusions are not arranged in the depth direction, but are arranged only in a direction oblique to the depth direction.

[0087] -Supporting member 74-

[0088] The support member 74 is formed in a disk shape, and has a plurality of through holes 74 a penetrating through the front and back surfaces so as to surround the shaft 72 .

[0089] [Cooling fan 76]

[0090] like Figure 3 、 Figure 4 As shown, a plurality of cooling fans 76 are arranged in the depth direction and arranged to face the lower end portion of the main body 66 of the pressure roller 65 when viewed from the depth direction. The cooling fans 76 blow air toward the portion of the rotating main body 66 that is close to the cooling fans 76.

[0091] (Function of the main structure)

[0092] Next, a fixing operation for fixing the toner image formed on the recording medium P to the recording medium P will be described.

[0093] first, Figure 3 The pressure roller 65 shown rotates by receiving a driving force from a driving source (not shown). As a result, the fixing belt 64 provided on the heating member 62 is driven by the rotating pressure roller 65 and is rotated. The first heating roller 69 and the second heating roller 67 are driven by the rotating fixing belt 64 and are rotated.

[0094] Furthermore, the halogen heater 67a, the halogen heater 68a, and the halogen heater 69a operate, and the running fixing belt 64 is heated by the first heating roller 69, the second heating roller 67, and the pad member 68. Furthermore, the cooling fan 76 operates.

[0095] Then, when the fixing belt 64 is heated to a predetermined temperature, the fixing device 60 heats and pressurizes the recording medium P, to which the toner image has been transferred, while sandwiching and conveying the recording medium P in the nip N formed by the pressure roller 65 and the fixing belt 64 of the heating member 62. This fixes the toner image onto the recording medium P. Furthermore, the operating cooling fan 76 cools the pressure roller 65.

[0096] During this fixing operation, the opposing portion 66a of the rotating main body 66 is heated by the circling fixing belt 64. Here, in the depth direction, at both end portions of the opposing portion 66a, since the recording medium P is not sandwiched between the fixing belt 64 and the opposing portion 66a, the temperature of the end portions of the opposing portion 66a in the depth direction (axial direction) is higher than the temperature of the central portion of the opposing portion 66a in the axial direction. In other words, temperature unevenness occurs on the main body 66 of the pressure roller 65. From a macroscopic perspective, temperature unevenness occurs on the pressure roller 65. Here, the end portion refers to the portion of the pressure roller 65 that is in direct contact with the fixing belt 64 of the heating component 62 at all times when the toner image formed on the recording medium P with the largest usage is fixed to the recording medium P.

[0097] Next, an operation for suppressing temperature unevenness generated in the main body portion 66 of the pressure roller 65 (pressure roller 65 ) will be described.

[0098] The protrusions 70 provided on the extension portion 66b rotate as the pressure roller 65 rotates. As described above, the protrusions 70 in the Nth row are separated from the protrusions 70 in the N±1th rows in the depth direction, and protrusions 70 adjacent in the depth direction are arranged in a direction inclined relative to the depth direction.

[0099] Therefore, as the pressure roller 65 rotates, air contacts the protrusions 70, as shown in FIG. Figure 5 As shown, turbulent flow (the spiral curve shown in the figure) is generated around the protrusions 70. With protrusions 70 arranged in an inclined direction relative to the depth direction, the turbulent flow intensity generated by the first protrusion 70 in the roller circumferential direction increases as it contacts the next protrusion 70 in the roller circumferential direction. This process is repeated, increasing the turbulent flow intensity.

[0100] The heated end portion of the facing portion 66a then dissipates heat via the protrusion 70 provided on the extended portion 66b. This suppresses temperature unevenness in the depth direction of the pressure roller 65. Thus, the protrusion 70 functions as a heat sink.

[0101] (Summarize)

[0102] As described above, in the fixing device 60, a plurality of protrusions 70 are formed on the extension 66b of the pressure roller 65. This reduces the depth-wise temperature variations on the pressure roller 65, compared to a case where the pressure roller has a uniform cross-section from one end to the other. In other words, the depth-wise temperature variations on the pressure roller 65 are reduced, compared to a case where the pressure roller is not provided with protrusions.

[0103] Furthermore, in the fixing device 60 , the protrusions 70 protrude from the outer peripheral surface of the extension 66 b. Compared to a case where the protrusions protrude from the inner peripheral surface of the pressure roller, the peripheral speed of the protrusions is increased, thereby suppressing temperature unevenness in the depth direction of the pressure roller 65 .

[0104] Furthermore, 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 roller 65. This reduces temperature unevenness in the depth direction of the pressure roller 65 compared to a case where the protrusions are provided in only one row in the depth direction.

[0105] Furthermore, in the fixing device 60, the protrusions 70 are arranged in a direction inclined with respect to the depth direction. Compared to a case where 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 turbulent intensity is increased, thereby suppressing temperature unevenness in the depth direction on the pressure roller 65.

[0106] Furthermore, in the fixing device 60, the protrusions 70 are arranged in a direction inclined with respect to the depth direction. Compared to a case where the protrusions are arranged in a grid pattern, the air flowing on the outer peripheral surface of the extension portion 66b becomes turbulent, and the turbulent intensity is increased, thereby suppressing temperature unevenness in the depth direction generated on the pressure roller 65.

[0107] Furthermore, in the fixing device 60, the protrusion 70 is formed with a flat surface portion 70a facing the rotational direction of the pressure roller 65. This increases the air resistance experienced by the protrusion 70 compared to a case where the protrusion is hemispherical, improving the heat dissipation effect and suppressing temperature unevenness in the depth direction of the pressure roller 65.

[0108] Furthermore, in the fixing device 60, the flat surface portion 70a of the protrusion 70 extends in the depth direction. This increases the contact length between the flat surface portion 70a and the extension portion 66b compared to a case where the flat surface portion extends in the radial direction of the rotating pressure roller, thereby improving the heat dissipation effect and suppressing temperature unevenness in the depth direction of the main body portion 66 of the pressure roller 65.

[0109] Furthermore, in the fixing device 60 , the output of the cooling fan 76 is reduced by suppressing the temperature unevenness in the depth direction generated in the main body 66 of the pressure roller 65 .

[0110] Furthermore, in the image forming apparatus 10, by providing the fixing device 60, the temperature unevenness in the depth direction generated on the pressure roller 65 is suppressed compared to the case where the cross-section of the pressure roller in the depth direction is provided with the same fixing device from one end to the other end, thereby suppressing the generation of wrinkles on the output recording medium P.

[0111] <Second embodiment>

[0112] Then, according to Figure 6 , an example of the fixing device 160 and the image forming apparatus according to the second embodiment will be described. In addition, the second embodiment will be described mainly with respect to the parts that are different from the first embodiment.

[0113] like Figure 6 As shown, the extension portion 66b of the pressure roller 165 of the fixing device 160 according to the second embodiment is formed with protrusions 70. 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.

[0114] <Third embodiment>

[0115] Then, according to Figure 7 , an example of the fixing device 260 and the image forming apparatus according to the third embodiment will be described. In addition, the third embodiment will be described mainly with respect to the parts that are different from the first embodiment.

[0116] like Figure 7 As shown in FIG. 1 , a protrusion 270 is formed on the extension portion 66 b of the pressure roller 265 of the fixing device 260 according to the third embodiment. The protrusion 270 is formed in a cylindrical shape extending in the radial direction of the rotating pressure roller 265 .

[0117] The effects of the third embodiment are the same as those of the first embodiment except for the effects achieved by forming the flat surface portion facing the rotational direction on the protrusion.

[0118] <Fourth embodiment>

[0119] Then, according to Figure 8 , an example of a fixing device 360 ​​and an image forming apparatus according to a fourth embodiment will be described. In addition, the fourth embodiment will be described mainly with respect to portions that differ from the first embodiment.

[0120] like Figure 8 As shown in FIG. 1 , a protrusion 370 is formed on the extension portion 66 b of the pressure roller 365 of the fixing device 360 ​​according to the fourth embodiment. The protrusion 370 is formed in a hemispherical shape that protrudes in the radial direction of the rotating pressure roller 365 .

[0121] The effects of the fourth embodiment are the same as those of the first embodiment except for the effects achieved by forming the flat surface portion facing the rotational direction on the protrusion.

[0122] <Fifth embodiment>

[0123] Then, according to Figure 9, an example of a fixing device 460 and an image forming apparatus according to a fifth embodiment will be described. The fifth embodiment will be described mainly with respect to portions that differ from the first embodiment.

[0124] The pressure roller 465 of the fixing device 460 according to the fifth embodiment is not provided with an extension portion. Figure 9 As shown, the protrusion 470 protrudes from the inner peripheral surface of the end portion of the facing portion 66a of the pressure roller 465. Then, the heated end portion of the facing portion 66a is directly dissipated by the protrusion 470.

[0125] Furthermore, the effects of the fifth embodiment are the same as those of the first embodiment except for the effects achieved by forming the protrusions on the outer peripheral surface.

[0126] While a specific embodiment of the present invention has been described in detail, the present invention is not limited to this embodiment. It is obvious to those skilled in the art that various other embodiments can be employed within the scope of the present invention. For example, in the above embodiment, the protrusions 70, 270, 370, and 470 are arranged in multiple rows in the depth direction, but they can also be arranged in a single row. However, in this case, the effects of providing multiple rows will not be achieved.

[0127] Furthermore, in the above embodiment, the protrusions 70, 270, 370, and 470 are provided in a plurality of rows in the circumferential direction of the pressure roller, but may be provided in a single row. However, in this case, the effect achieved by providing the protrusions in a plurality of rows is not achieved.

[0128] Furthermore, in the above embodiment, the protrusions 70 , 270 , 370 , and 470 are provided in multiple rows in the depth direction and in multiple columns in the circumferential direction of the pressure roller. However, the protrusions may be provided randomly (not in order) in multiple numbers.

[0129] Furthermore, in the above embodiment, the protrusions 70, 370, 470 are arranged in a direction oblique to the depth direction, but the protrusions may be arranged in a grid pattern. However, in this case, the effect of arranging the protrusions in a direction oblique to the depth direction will not be achieved.

[0130] Furthermore, in the above embodiment, the protrusions 70 and 270 are formed in a rectangular parallelepiped shape, but they may be formed in other shapes. In this case, the effect of the protrusions being in a rectangular parallelepiped shape will not be achieved. (1)

[0132] A fixing device comprising:

[0133] a heating member that rotates while heating the recording medium to which the image is transferred; and

[0134] The pressurizing member comprises: a cylindrical main body portion that clamps the recording medium between the main body portion and the heating member and pressurizes the recording medium toward the heating member while rotating; and a plurality of protrusions that protrude from the peripheral surface of the end portion of the main body portion in the axial direction of the main body portion. (2)

[0136] The fixing device according to (1), wherein

[0137] The main body includes an opposing portion opposing the heating member and an extension portion extending outward from the opposing portion in the axial direction.

[0138] The protrusion protrudes from the outer peripheral surface of the extension portion. (3)

[0140] The fixing device according to (1), wherein

[0141] The protrusions are arranged in a plurality of rows in the axial direction and in a plurality of columns in the circumferential direction of the pressurizing member. (4)

[0143] The fixing device according to any one of (1) to (3), wherein

[0144] The protrusions are arranged in a direction inclined with respect to the axial direction. (5)

[0146] The fixing device according to any one of (1) to (3), wherein

[0147] The protrusions are arranged in a staggered pattern with respect to the axial direction. (6)

[0149] The fixing device according to any one of (1) to (5), wherein

[0150] The protrusion is formed with a flat surface portion facing the rotation direction of the pressing member. (7)

[0152] The fixing device according to (6), wherein

[0153] The planar portion extends along the axial direction. (8)

[0155] An image forming apparatus comprising:

[0156] an image forming unit that forms an image on a recording medium; and

[0157] The fixing device described in any one of (1) to (7) fixes an image on a recording medium.

[0158] In the fixing device according to (1), temperature variations of the pressure member in the axial direction can be suppressed compared to a case where the cross section of the pressure member in the axial direction is uniform from one end to the other end.

[0159] In the fixing device according to (2), compared with a case where the protrusion protrudes from the inner peripheral surface, it is possible to suppress temperature unevenness of the pressure member in the axial direction.

[0160] The fixing device according to (3) can suppress temperature unevenness of the pressure member in the axial direction, compared to a case where the protrusions are provided in only one row in the axial direction and in only one column in the circumferential direction.

[0161] Regarding the fixing device according to (4), compared with a case where the protrusions are arranged in a grid pattern, it is possible to suppress temperature unevenness of the pressure member in the axial direction.

[0162] Regarding the fixing device according to (5), compared with the case where the protrusions are arranged in a grid pattern, it is possible to suppress temperature unevenness of the pressure member in the axial direction.

[0163] Regarding the fixing device according to (6), compared with the case where the protrusion is hemispherical, it is possible to suppress temperature unevenness of the pressure member in the axial direction.

[0164] In the fixing device according to (7), temperature unevenness of the pressure member in the axial direction can be suppressed compared to a case where the flat surface portion extends in the radial direction of the rotating pressure member.

[0165] The image forming apparatus according to (8) can suppress the generation of wrinkles on the output recording medium, compared with a fixing apparatus including a pressure member having a uniform cross-section from one end to the other in the axial direction.

[0166] The above-described embodiments of the present invention are provided for the purpose of illustration and explanation. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed embodiments. It is obvious that various modifications and variations are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily explain the principles of the present invention and its application. Thus, other technical personnel in this field can understand the present invention through various modifications optimized for specific uses of the assumed various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. A fixing device comprising: a heating member that rotates while heating the recording medium to which the image is transferred; and The pressurizing member comprises: a cylindrical main body portion that clamps the recording medium between the main body portion and the heating member and pressurizes the recording medium toward the heating member while rotating; and a plurality of protrusions that protrude from the peripheral surface of the end portion of the main body portion in the axial direction of the main body portion.

2. The fixing device according to claim 1, wherein The main body includes an opposing portion opposing the heating member and an extension portion extending outward from the opposing portion in the axial direction. The protrusion protrudes from the outer peripheral surface of the extension portion.

3. The fixing device according to claim 1, wherein The protrusions are arranged in a plurality of rows in the axial direction and in a plurality of columns in the circumferential direction of the pressurizing member.

4. The fixing device according to any one of claims 1 to 3, wherein The protrusions are arranged in a direction inclined with respect to the axial direction.

5. The fixing device according to any one of claims 1 to 3, wherein The protrusions are arranged in a staggered pattern with respect to the axial direction.

6. The fixing device according to any one of claims 1 to 5, wherein: The protrusion is formed with a flat surface portion facing the rotation direction of the pressing member.

7. The fixing device according to claim 6, wherein The planar portion extends along the axial direction.

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

Images