JP2020095174A - Fixing device - Google Patents

Abstract

To prevent deformation of a slide sheet at a nip part.SOLUTION: A fixing device 8 comprises: a heater 82; a rotating body (heating roller 81) that is heated by the heater 82; an endless belt 83; a nip forming member (pressure pad 85) that forms a nip part NP with the rotating body with the endless belt 83 therebetween; and a slide sheet 87 that is sandwiched between an inner peripheral surface 83A of the endless belt 83 and the nip forming member at the nip part NP. The slide sheet 87 has a first portion A1 corresponding to the nip part NP, a second portion A21 located separately from the first portion A1 in the direction of rotation of the endless belt 83 and fixing the slide sheet 87, and a third portion A31 located between the first portion A1 and second portion A21. The third portion A31 has a plurality of troughs C3 that form a wave shape for increasing elasticity in a width direction of the endless belt 83 compared with that of the first portion A1.SELECTED DRAWING: Figure 4

Description

The present invention relates to a fixing device including an endless belt.

Conventionally, a heating roller, a nip forming member that sandwiches an endless belt between the heating roller to form a nip portion, and a sliding sheet that is arranged between the inner peripheral surface of the endless belt and the nip forming member are provided. A fixing device is known (Patent Document 1). The sliding sheet reduces the sliding resistance between the endless belt and the sliding sheet at the nip portion. An end portion of the sliding sheet is fixed to a holder that holds the nip forming member.

JP, 2008-310225, A

By the way, the sliding sheet and the fixing member for fixing the sliding sheet repeatedly expand and contract under the influence of heat from the fixing device. At this time, the fixed portion of the sliding sheet may be deformed due to the difference in coefficient of thermal expansion between the sliding sheet and the fixing member. If the deformation of the fixed portion is transmitted to the nip portion, the sliding resistance may increase or the movement of the endless belt may become unstable.

Then, this invention aims at suppressing the deformation|transformation of the sliding sheet in a nip part.

In order to solve the above problems, a fixing device according to the present invention is a nip forming member that forms a nip portion with a heater, a rotating body heated by the heater, an endless belt, and the endless belt sandwiched between the rotating body. And a sliding sheet sandwiched between the inner peripheral surface of the endless belt and the nip forming member in the nip portion. The sliding sheet includes a first portion corresponding to the nip portion, a second portion which is located away from the first portion in the rotation direction of the endless belt, and which fixes the sliding sheet, and between the first portion and the second portion. And a third portion located at. The third portion has a plurality of troughs forming a wavy shape for making the endless belt more elastic in the width direction than the first portion.

According to this configuration, even if the second portion of the sliding sheet is deformed by heat, the third portion forms a plurality of corrugated shapes for making the stretchability of the endless belt in the width direction larger than that of the first portion. Since it has a trough, it is possible to prevent the deformation generated in the second portion from being transmitted to the first portion. Therefore, it is possible to suppress the deformation of the sliding sheet in the nip portion, and it is possible to suppress the increase of sliding resistance and the unstable movement of the endless belt.

In the fixing device described above, the plurality of troughs may be provided only in a region of the third portion that is not in contact with the inner peripheral surface of the endless belt.

According to this, the deformation in the contact area between the sliding sheet and the inner peripheral surface of the endless belt can be suppressed. Therefore, it is possible to suppress an increase in sliding resistance and an unstable movement of the endless belt.

In the fixing device described above, the plurality of valleys may be arranged in the width direction.

According to this, the elasticity of the third portion in the width direction can be effectively increased.

In the fixing device described above, the plurality of troughs may be arranged at a constant pitch in the width direction.

According to this, the elasticity of the third portion in the width direction can be made constant in the width direction.

In the fixing device described above, the first portion may have a plurality of concave portions on the surface that contacts the inner peripheral surface of the endless belt, and the depth of the valley portions may be larger than the depth of the concave portions.

According to this, the elasticity of the third portion can be increased.

In the above-described fixing device, the valley portion may have a structure in which the depth becomes smaller and the dimension in the width direction becomes smaller as it gets closer to the first portion.

According to this, the deformation of the sliding sheet generated in the second portion can be reduced in the third portion as it approaches the first portion.

In the above-described fixing device, the valley portion may extend to the end of the sliding sheet in the rotation direction.

According to this, since the plurality of valleys continuously extend from the third portion to the second portion, the deformation generated in the third portion is transmitted to the first portion in both the second portion and the third portion. It can be suppressed.

In the fixing device described above, the depth of the valley may be 300 μm or more.

The fixing device may further include a holder for holding the nip forming member, and the second portion may be fixed to the holder.

In the fixing device described above, the second portion and the third portion are respectively arranged on the upstream side and the downstream side in the rotation direction of the first portion, each third portion has a corrugated shape, and the sliding sheet is It may be configured to be fixed at both the second portion located on the upstream side and the second portion located on the downstream side.

In the fixing device described above, the sliding sheet may be made of a plastic sheet.

According to this, the manufacturing cost of the sliding sheet can be suppressed.

In the fixing device described above, the plastic sheet may include polyimide.

According to this, the sliding sheet can have high strength and high heat resistance.

According to the present invention, it is possible to suppress the deformation of the sliding sheet in the nip portion.

1 is a cross-sectional view showing a laser printer according to an embodiment of the present invention. FIG. 3A is a sectional view showing the fixing device and FIG. 3B is an enlarged view showing the periphery of the nip portion in an enlarged manner. It is a figure explaining the fixed structure of a sliding sheet. It is a figure showing a plurality of convex parts and a plurality of valleys formed in a sliding sheet. It is a YY sectional view (a) and a ZZ sectional view (b) of a sliding sheet. It is a perspective view which shows the sliding sheet in the state which is not deformed by heat. It is a perspective view which shows the sliding sheet in the state deformed by heat. It is a perspective view which shows the sliding sheet which concerns on a 1st modification. It is sectional drawing (a), (b), (c) which shows the sliding sheet which concerns on a 2nd modification, a 3rd modification, and a 4th modification.

Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, the direction is "front" on the left side of the drawing in FIG. 1, "right" on the right side of the drawing, "left" on the back side of the drawing, and front of the drawing. The side is "right". In addition, the up-down direction is referred to as “up-down” toward the paper surface.

As shown in FIG. 1, the monochrome laser printer 1 mainly includes a paper feed unit 3, an exposure device 4, a process cartridge 5, and a fixing device 8 in a housing 2.

The paper feeding unit 3 is provided in the lower portion of the housing 2, and mainly includes a paper feeding tray 31 that stores a paper S as an example of a recording medium, a paper pressing plate 32, and a paper feeding mechanism 33. There is. The paper S stored in the paper feed tray 31 is moved upward by the paper pressing plate 32 and is supplied to the process cartridge 5 by the paper feed mechanism 33.

The exposure device 4 is arranged in the upper part of the housing 2 and includes a light source device (not shown), a polygon mirror, a lens, a reflecting mirror and the like, which are omitted from the reference numerals. In the exposure device 4, the light beam based on the image data emitted from the light source device scans the surface of the photoconductor drum 61 at high speed to expose the surface of the photoconductor drum 61.

The process cartridge 5 is arranged below the exposure device 4, and is attachable to and detachable from the housing 2 through an opening formed when the front cover 21 provided on the housing 2 is opened. The process cartridge 5 includes a drum unit 6 and a developing unit 7. The drum unit 6 mainly includes a photosensitive drum 61, a charger 62, and a transfer roller 63. Further, the developing unit 7 is attachable to and detachable from the drum unit 6, and mainly includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, and a storage portion 74 that stores toner. ..

In the process cartridge 5, the surface of the photoconductor drum 61 is uniformly charged by the charger 62 and then exposed by the light beam from the exposure device 4, so that the photoconductor drum 61 is statically charged based on the image data. A latent image is formed. Further, the toner in the containing portion 74 is supplied to the developing roller 71 via the supply roller 72 and enters between the developing roller 71 and the layer thickness regulating blade 73 to form a thin layer having a constant thickness on the developing roller 71. Carried. The toner carried on the developing roller 71 is supplied from the developing roller 71 to the electrostatic latent image formed on the photosensitive drum 61. As a result, the electrostatic latent image is visualized and a toner image is formed on the photoconductor drum 61. After that, the sheet S is conveyed between the photosensitive drum 61 and the transfer roller 63, so that the toner image on the photosensitive drum 61 is transferred onto the sheet S.

The fixing device 8 is arranged behind the process cartridge 5. The sheet S onto which the toner image has been transferred passes through the fixing device 8 so that the toner image is fixed. The paper S on which the toner image is fixed is discharged onto the paper discharge tray 22 by the transport rollers 23 and 24.

As shown in FIG. 2A, the fixing device 8 includes a heating roller 81 as an example of a rotating body, a heater 82, an endless belt 83, and a pressure unit 84. Then, one of the heating roller 81 and the pressure unit 84 is urged toward the other, so that a nip portion NP is formed between the heating roller 81 and the endless belt 83.

In the following description, the width direction of the endless belt 83 is also simply referred to as “width direction”, and the rotation direction of the endless belt 83 is also simply referred to as “rotation direction”. In the present embodiment, the width direction is a direction parallel to the rotation axis of the heating roller 81 and is along the left-right direction. Further, the rotation direction is a direction orthogonal to the width direction.

The heating roller 81 is a roller having a cylindrical substrate, and is formed by forming a release layer made of fluororesin or the like on the outer peripheral surface of a raw tube made of metal such as aluminum as an example. The heating roller 81 is rotationally driven counterclockwise in FIG. 2 when a driving force is input from a motor (not shown). The heating roller 81 is in contact with the outer peripheral surface of the endless belt 83.

The heater 82 is a heater that heats the heating roller 81, and is arranged inside the heating roller 81 in the radial direction. As the heater 82, for example, a halogen lamp that emits light when energized and heats the heating roller 81 by radiant heat can be used.

The endless belt 83 is a tubular member and has flexibility. The endless belt 83 is, for example, configured by forming a release layer made of fluororesin or the like on the outer peripheral surface of a base material made of metal such as stainless steel or resin such as polyimide resin. The endless belt 83 is provided so as to be driven to rotate clockwise in FIG. 2 by the rotation of the heating roller 81. As a result, the endless belt 83 conveys the paper S with the heating roller 81.

A lubricant such as grease is applied to the inner peripheral surface 83A of the endless belt 83. As a result, the slidability between the inner peripheral surface 83A of the endless belt 83 and the pressure unit 84 can be improved, and the endless belt 83 can be rotated well.

The pressure unit 84 supports a pressure pad 85 as an example of a nip forming member, a holder 86 that supports the pressure pad 85, a sliding sheet 87, a fixing plate 88, a screw 89, and a holder 86. And a stay 90.

The pressure pad 85 is located inside the endless belt 83 in the radial direction and is covered with the endless belt 83. The pressure pad 85 is made of an elastic material such as rubber and has a rectangular parallelepiped shape (see FIG. 3 ). The pressure pad 85 forms the nip portion NP between the heating roller 81 and the endless belt 83 by sandwiching the endless belt 83 with the heating roller 81. By thus forming the nip portion NP by the pressure pad 85, the sheet S is heated and pressed while passing through the nip portion NP, and the toner image is fixed on the sheet S.

In the present embodiment, a region where the endless belt 83 is sandwiched between the pressure pad 85 and the heating roller 81, that is, a region where a nip pressure is applied is referred to as a nip portion NP. More specifically, in the portion where the outer peripheral surface of the endless belt 83 and the heating roller 81 are in contact with each other, it is in the range from the upstream end to the downstream end of the pressure pad 85 in the transport direction of the paper S and in the width direction. A range from one end to the other end of the pressure pad 85 is referred to as a nip portion NP.

The sliding sheet 87 is a rectangular sheet for reducing the frictional resistance between the pressure pad 85 and the endless belt 83. The sliding sheet 87 is sandwiched between the inner peripheral surface 83A of the endless belt 83 and the pressure pad 85 at the nip portion NP.

The sliding sheet 87 is wound around the holder 86 so as to cover the upper surface of the holder 86, and one end and the other end of the endless belt 83 in the rotation direction are fixed to the holder 86. As shown in FIG. 3, each end of the sliding sheet 87 is fixed by being sandwiched between the holder 86 and the fixing plate 88. The fixing plate 88 is fixed to the holder 86 with screws 89.

The sliding sheet 87 is made of a plastic sheet. The material of the plastic sheet is not particularly limited, but for example, PI (polyimide), PEEK (polyether ether ketone), PES (polyether sulfone), PET (polyethylene terephthalate), etc. can be adopted. In this embodiment, the sliding sheet 87 is a plastic sheet containing polyimide.

As shown in FIG. 4, the sliding sheet 87 is located apart from the first portion A1 corresponding to the nip portion NP in the rotation direction of the endless belt 83, and fixes the sliding sheet 87. It has two parts A21, A22 and third parts A31, A32 located between the first part A1 and the second parts A21, A22. The first portion A1, the second portions A21 and A22, and the third portions A31 and A32 are arranged in the rotation direction.

The first portion A1 has a plurality of recesses C1 on the surface that contacts the inner peripheral surface 83A of the endless belt 83. The plurality of recesses C1 have a hexagonal pyramid shape, and the shape of the opening is a regular hexagon (see also FIG. 3 ). The plurality of recesses C1 are arranged in a honeycomb shape. The depth D1 of the plurality of recesses C1 is 100 μm or more and less than 300 μm (see FIG. 5A). The plurality of recesses C1 reduce sliding resistance at the nip portion NP.

The second portions A21 and A22 are respectively arranged on the upstream side and the downstream side in the rotation direction of the first portion A1. The sliding sheet 87 is fixed to the holder 86 by both the second portion A21 located on the upstream side in the rotation direction and the second portion A22 located on the downstream side in the rotation direction.

A hole H1 and an elongated hole H2 through which the above-described screw 89 passes are formed in the second portions A21 and A22. The hole H1 is located at the center in the width direction. The long hole H2 is located at the end of the sliding sheet 87 in the width direction. The long hole H2 is a long hole that is longer in the width direction than in the rotation direction.

The third portions A31 and A32 are respectively arranged on the upstream side and the downstream side in the rotation direction of the first portion A1. The third portions A31 and A32 have a plurality of valleys C3.

The third portions A31 and A32 have a region R1 that contacts the inner peripheral surface 83A of the endless belt and a region R2 that does not contact the inner peripheral surface 83A of the endless belt. The plurality of valleys C3 are provided only in a region R2 of the third portions A31 and A32 that is not in contact with the inner peripheral surface 83A of the endless belt 83.

The plurality of valleys C3 have a valley shape that is recessed from the surface that contacts the inner peripheral surface 83A of the endless belt 83. The plurality of valleys C3 are arranged in the width direction. The plurality of valleys C3 are arranged at a constant pitch in the width direction. The valley portion C3 has a smaller depth and a smaller dimension in the width direction as it approaches the first portion A1. The valley portion C3 is formed by embossing.

FIG. 5A is a YY cross-sectional view of the sliding sheet 87 shown in FIG. As shown in FIG. 5A, the depth D2 of the valley C3 is larger than the depth D1 of the recess C1. Specifically, the depth D2 of the valley portion C3 is preferably 300 μm or more and 500 μm or less.

FIG. 5B is a ZZ sectional view of the sliding sheet 87 shown in FIG. As shown in FIG. 5(b), the plurality of valleys C3 form a wave shape. The plurality of valleys C3 have a triangular cross section. Due to the corrugated shape formed by the plurality of valleys C3, the elasticity of the third portion A3 in the width direction is greater than the elasticity of the first portion A1 in the width direction. It is preferable that all of the plurality of valleys have the same shape and depth, but a plurality of valleys having different shapes and depths may be arranged side by side in the width direction to form a wave shape.

According to the above, the following effects can be obtained in the present embodiment.
In the unused state of the laser printer 1, as shown in FIGS. 6A and 6B, the end portion of the sliding sheet 87 is not deformed, and wrinkles are generated or the sheet is wavy. Absent.
When the laser printer 1 is used to some extent, the holder 86, the sliding sheet 87, and the fixing plate 88 repeatedly expand and contract due to the influence of heat from the heating roller 81 of the fixing device 8. Since the holder 86, the sliding sheet 87, and the fixing plate 88 have different coefficients of thermal expansion, as shown in FIGS. 7A and 7B, the second portions A21 and A22 of the sliding sheet 87 are deformed in a wavy manner. I may end up doing it. If this deformation is transmitted to the nip portion NP, sliding resistance may increase or the movement of the endless belt 83 may become unstable.

However, according to the fixing device 8, even if the second portions A21 and A22 of the sliding sheet 87 are deformed by heat, the third portions A31 and A32 are more elastic than the first portion A1 in the width direction of the endless belt 83. Since it has a plurality of troughs C3 forming a corrugated shape for increasing, it is possible to suppress the deformation generated in the second portions A21 and A22 from being transmitted to the first portion A1. Therefore, the deformation of the sliding sheet 87 at the nip portion NP can be suppressed.

In addition, since the plurality of valleys C3 are provided only in the region R2 of the third portions A31 and A32 that is not in contact with the inner peripheral surface 83A of the endless belt 83, the inside of the sliding sheet 87 and the endless belt 83 is not provided. It is possible to suppress deformation in the contact region R1 with the peripheral surface 83A. Therefore, it is possible to suppress an increase in sliding resistance and an unstable movement of the endless belt.

In addition, since the plurality of valleys C3 are arranged side by side in the width direction, the elasticity of the third portions A31 and A32 in the width direction can be effectively increased.

In addition, since the plurality of valleys C3 are arranged at a constant pitch in the width direction, the elasticity of the third portions A31 and A32 in the width direction can be made constant in the width direction.

The first portion A1 of the sliding sheet 87 has a plurality of concave portions C1 on the surface that contacts the inner peripheral surface 83A of the endless belt 83, and the depth D2 of the valley portion C3 of the third portions A31 and A32 is Since it is larger than the depth of the concave portion C1 of the first portion A1, the elasticity of the third portions A31 and A32 can be increased.

Further, the valley portion C3 of the third portion A31, A32 has a smaller depth and a smaller widthwise dimension as it gets closer to the first portion A1, so that the sliding generated in the second portion A21, A22. The deformation of the seat 87 can be reduced in the third portions A31 and A32 as the sheet 87 approaches the first portion A1.

Further, since the sliding sheet 87 is made of a plastic sheet, the manufacturing cost of the sliding sheet 87 can be suppressed.

Further, since the plastic sheet contains polyimide, the sliding sheet 87 can have high strength and high heat resistance.

Further, since the valley portions C3 of the third portions A31 and A32 are formed by embossing, it is possible to manufacture the sliding sheet 87 of constant quality.

The present invention is not limited to the above-mentioned embodiment, but can be used in various forms as exemplified below. In the following description, members having substantially the same structure as those in the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In the above embodiment, the valley portion C3 is formed only in the third portion A3 of the sliding sheet 87, but the valley portion C3 may extend to the second portion A2. For example, as shown in FIG. 8, the valley portion C3 of the sliding sheet 187 according to the first modification extends to the end of the sliding sheet 187 in the rotation direction.

Also with this sliding sheet 187, since the plurality of valleys C3 continuously extend from the third portion A31 to the second portion A21, the deformation generated in the second portion A21 is caused by the second portion A21 and the third portion A31. In both cases, it is possible to suppress the transmission to the first portion A1.

In the above-described embodiment, as shown in FIG. 5B, the third portions A31 and A32 have the corrugations formed by the valleys C3 recessed from the endless belt 83 side, but the convex portions form the corrugations. May be. For example, as shown in FIG. 9A, the sliding sheet 287 of the second modification has a plurality of convex portions T3 protruding toward the endless belt 83 side in the third portion A3, and the plurality of convex portions T3. Form a wave shape.

In the above embodiment, as shown in FIG. 5B, the valley C3 of the third portions A31 and A32 has a triangular cross section, but the shape is not limited to this.
For example, as shown in FIG. 9B, the valley C3 may have a trapezoidal cross section like a sliding sheet 387 according to the third modification.
Further, for example, as shown in FIG. 9C, the valley C3 may have a semicircular cross section, as in a sliding sheet 487 according to the fourth modification.

In the embodiment, the plurality of valleys C3 are provided only in the region R2 of the third portions A31 and A32 that is not in contact with the inner peripheral surface 83A of the endless belt 83, but the plurality of valleys C3 are Of the third portions A31 and A32, it may extend to a region R1 that contacts the inner peripheral surface 83A of the endless belt 83.

Although the sliding sheet 87 is fixed to the holder 86 in the embodiment, the sliding sheet 87 may be fixed to a member other than the holder 86. For example, it may be fixed to the stay 90 that supports the holder.

In the above-described embodiment, both ends of the sliding sheet 87 in the rotation direction are fixed, but the present invention is not limited to this, and the downstream end in the rotation direction may be fixed and free.

Although the sliding sheet is made of a plastic sheet in the above embodiment, it may be a sheet other than the plastic sheet. For example, it may be a metal sheet or a sheet made of cloth.

In the above embodiment, the plurality of recesses C1 have a hexagonal pyramid shape, but they may have other shapes. Further, the size, arrangement, and number of the concave portions C1 can be changed as appropriate.

In the above embodiment, the second portions A21, A22 and the third portions A31, A32 are arranged both upstream and downstream of the nip portion NP, but the present invention is not limited to this, and the second portion and the third portion are It should be located at least one of the upstream side and the downstream side of the nip portion.

In the above embodiment, the halogen lamp is illustrated as the heater 82, but the present invention is not limited to this, and the heater may be, for example, a carbon heater.

Although the pressure pad 85 made of an elastic material such as rubber is illustrated as the nip forming member in the above embodiment, the present invention is not limited to this. The nip forming member may be, for example, a plate-shaped member made of a hard material such as resin or metal that does not elastically deform even when pressure is applied. The nip forming member may be formed integrally with the holder 86. However, when a hard material such as resin or metal is used as the nip forming member, the concave portion or the convex portion on the surface of the sliding sheet is crushed due to long-term use to increase sliding resistance, or the endless belt has a sliding sheet with an increased sliding resistance. An uneven pattern may appear and the image quality may deteriorate. For this reason, as the nip forming member, it is preferable to use an elastic body such as rubber, which elastically deforms according to the uneven shape of the sliding sheet when pressure is applied, such as the pressure pad 85.

In the above-described embodiment, the heating roller 81 having the heater 82 built therein as the rotating body is exemplified, but the present invention is not limited to this. Good. Further, an external heating method in which a heater is arranged outside the rotating body to heat the outer peripheral surface of the rotating body, or an IH (Induction Heating) method may be used. In addition, a heater may be arranged inside the endless belt to indirectly heat the rotating body that contacts the outer peripheral surface of the endless belt. Further, the rotating body and the endless belt may each have a built-in heater. Further, the heating roller is not limited to the cylindrical shape, and may have a crown shape or an inverted crown shape.

Further, the configuration for forming the nip portion of the present invention is not limited to the fixing device as in the above embodiment, but can be applied to various fixing devices. For example, a fixing roller, a pressure roller that forms a fixing nip between the fixing roller, and a heating unit that contacts the fixing roller at a predetermined nip pressure to heat the fixing roller are provided. In the fixing device for fixing the toner image to the above, the structure of the present invention may be provided in the heating unit. More specifically, when the heating unit includes an endless belt and a heating member that sandwiches the endless belt between the heating roller and the fixing roller, a sliding sheet may be provided between the heating member and the endless belt.

In the above-described embodiment, the present invention is applied to the monochrome laser printer 1, but the present invention is not limited to this, and may be a color laser printer, and may be applied to other image forming apparatuses such as a copying machine and a multifunction machine. The present invention may be applied.

Moreover, you may implement combining each element demonstrated in the above-mentioned embodiment and a modification arbitrarily.

8 Fixing Device 81 Heating Roller 82 Heater 83 Endless Belt 83A Inner Surface 85 Pressure Pad 86 Holder 87 Sliding Sheet A1 First Part A21 Second Part A22 Second Part A31 Third Part A32 Third Part C1 Recess C3 Valley Part NP nip part

Claims (12)

With a heater,
A rotating body heated by the heater,
An endless belt,
A nip forming member that forms a nip portion by sandwiching the endless belt between the rotating body,
In the nip portion, a sliding sheet sandwiched between the inner peripheral surface of the endless belt and the nip forming member,
The sliding sheet includes a first portion that corresponds to the nip portion, a second portion that is located away from the first portion in the rotation direction of the endless belt, and that fixes the sliding sheet, and the first portion. And a third portion located between the second portion,
The fixing device, wherein the third portion has a plurality of troughs forming a corrugated shape for making the stretchability in the width direction of the endless belt larger than that of the first portion. The fixing device according to claim 1, wherein the plurality of valleys are provided only in a region of the third portion that is not in contact with the inner peripheral surface of the endless belt. The fixing device according to claim 1, wherein the plurality of valleys are arranged in the width direction. The fixing device according to claim 3, wherein the plurality of valleys are arranged at a constant pitch in the width direction. The first portion has a plurality of recesses on a surface that contacts the inner peripheral surface of the endless belt,
The fixing device according to claim 1, wherein the depth of the valley is larger than the depth of the recess. The fixing portion according to any one of claims 1 to 5, wherein the trough portion has a smaller depth and a smaller dimension in the width direction as the trough portion is closer to the first portion. apparatus. The fixing device according to any one of claims 1 to 6, wherein the valley portion extends to an end of the sliding sheet in the rotation direction. The fixing device according to any one of claims 1 to 7, wherein the depth of the valley portion is 300 µm or more. Further comprising a holder for holding the nip forming member,
The fixing device according to any one of claims 1 to 8, wherein the second portion is fixed to the holder. The second portion and the third portion are respectively arranged on the upstream side and the downstream side of the first portion in the rotation direction,
Each said third portion has said corrugation,
10. The sliding sheet is fixed by both the second portion located on the upstream side and the second portion located on the downstream side, according to any one of claims 1 to 9. The fixing device described. The fixing device according to any one of claims 1 to 10, wherein the sliding sheet is made of a plastic sheet. The fixing device according to claim 11, wherein the plastic sheet contains polyimide.

Images