JP2016075793A - Image forming apparatus and guide member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of image formation failures.SOLUTION: A laser printer 1 comprises: a photosensitive drum 61; a transfer roller 64 that forms a transfer nip N1 by contacting with the photosensitive drum 61; a heating roller 71 having a heater; a pressure roller 72 that forms a fixation nip N2 by contacting with the heating roller 71; and a guide member 100 having a guide surface 110 for guiding a sheet from the fixation nip N1 to the fixation nip N2. The guide surface 110 of the guide member 100 includes a first guide surface 120 and a second guide surface 130. The second guide surface 130 forms a recess 150, which dents toward the downstream side in a guide direction X, between the second guide surface 130 and the first guide surface 120. The size of the recess 150 in the sheet width direction decreases toward the downstream side in the guide direction X so that the area of the guide surface 110 increases toward the downstream side in the guide direction X.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus including a guide member for guiding paper and a guide member.

  Conventionally, an electrophotographic image forming apparatus includes a photosensitive drum, a transfer roller that forms a transfer nip between the photosensitive drum, a heating roller, and a pressure roller that forms a fixing nip between the heating roller, It has. The image forming apparatus further includes a guide member for guiding the sheet from the transfer nip toward the fixing nip.

  The guide member includes a plurality of ribs for guiding the paper, and a flat portion disposed on the downstream side of the plurality of ribs in the paper guiding direction. The plurality of ribs are disposed only in a range from the upstream end of the guide member in the paper guide direction to ½ of the size of the guide member.

Japanese Patent Application Laid-Open No. 2004-117992

  However, according to such a configuration, when the sheet passes through the boundary between the plurality of ribs and the flat portion, the contact area between the sheet and the guide member increases rapidly.

  For this reason, the sheet conveyance resistance increases rapidly at the boundary between the plurality of ribs and the flat portion. As a result, the conveyance of the paper is temporarily stopped or the conveyance speed of the paper is temporarily reduced while the paper is sandwiched between the transfer nips. Then, when the image is transferred to the sheet at the transfer nip, a part of the image is extended or contracted, and an image formation defect occurs.

  Accordingly, the present invention has been made in view of the above problems, and an object thereof is to suppress the occurrence of image formation defects.

  (1) To achieve the above object, an image forming apparatus according to the present invention includes a photosensitive member, a transfer roller that forms a transfer nip for transferring a developer image to a sheet between the photosensitive member, and a heater. A heating member having a pressure member for forming a fixing nip for fixing the developer image on the paper between the heating member, and a predetermined direction perpendicular to the paper width direction from the transfer nip to the fixing nip. And a guide member having a guide surface for guiding in the guide direction.

  The guide surface of the guide member is opposite to the first guide surface extending from the upstream end of the guide surface in the guide direction toward the downstream side of the guide direction and the first guide surface across the center in the paper width direction of the paper. A second guide that is disposed on the side and extends from the upstream end of the guide surface in the guide direction toward the downstream side of the guide direction, and is recessed between the first guide surface and the downstream side in the guide direction. And a surface.

  Further, the size of the concave portion in the paper width direction becomes smaller as it goes toward the downstream side in the guiding direction so that the area of the guiding surface becomes larger toward the downstream side in the guiding direction.

  According to such a configuration, the contact area between the sheet and the guide surface of the guide member gradually increases toward the downstream side in the guide direction. Therefore, when the sheet is guided by the guide member, the sheet conveyance resistance increases rapidly, and the sheet conveyance temporarily stops, or the sheet conveyance speed temporarily decreases. This can be suppressed. As a result, the occurrence of defective image formation can be suppressed.

  (2) The concave portion may include the center of the guide surface in the paper width direction.

  According to such a configuration, the sheet passing over the guide surface is gradually supported by the guide surface from both ends in the sheet width direction toward the center as it goes downstream in the guide direction. For this reason, when the sheet is guided on the guide surface, the sheet is unlikely to tilt with respect to the guide direction. As a result, the behavior of the paper is stabilized and the paper can be stably conveyed toward the fixing nip.

  (3) The concave portion may have an inclination.

  According to such a configuration, the contact area between the sheet and the guide member gradually increases along the inclination. Therefore, when the sheet is guided by the guide member, the sheet conveyance resistance increases rapidly, and the sheet conveyance temporarily stops, or the sheet conveyance speed temporarily decreases. This can be further suppressed. As a result, the occurrence of defective image formation can be suppressed.

  (4) The concave portion may have an arc shape.

  According to such a configuration, when the paper passes through the downstream end of the concave portion in the guide direction, the contact area between the paper and the guide member gradually increases along the arc shape. For this reason, when the paper is being guided by the guide member, it is possible to further suppress the paper transport resistance from rapidly increasing and temporarily stopping the paper transport. As a result, the occurrence of defective image formation can be suppressed.

  (5) The guide surface of the guide member may include a third guide surface between the first guide surface and the second guide surface. Further, the upstream end of the third guide surface in the guide direction may be arranged away from the first guide surface and the second guide surface in the sheet thickness direction. Further, the downstream end of the third guide surface in the guide direction may be continuous with the first guide surface and the second guide surface in the sheet thickness direction. Moreover, the 3rd guide surface may incline so that it may approach a 1st guide surface and a 2nd guide surface as it goes to the downstream of a guide direction.

  According to such a configuration, it is possible to guide a sheet having a size smaller than the interval between the first guide surface and the second guide surface onto the guide surface. As a result, sheets of a plurality of sizes can be guided.

  Further, the small size paper is guided on the first guide surface and the second guide surface on the downstream side in the guide direction. Therefore, on the downstream side of the guide surface in the guide direction, sheets of different sizes are guided on the same guide surface. As a result, a plurality of sizes of paper can be stably guided toward the fixing nip.

  (6) The third guide surface may be inclined linearly so as to approach the first guide surface and the second guide surface.

  According to such a configuration, a small-sized sheet guided on the third guide surface is guided linearly toward the first guide surface and the second guide surface. As a result, a small-sized sheet can be stably guided toward the fixing nip.

  (7) In order to achieve the above object, a fixing device of the present invention is detachably provided in a main body casing including a photosensitive member cartridge having a photosensitive member and a transfer member, and a heating member having a heater. A pressure member that forms a fixing nip in contact with the heating member, and a guide member having a guide surface for guiding the paper from the transfer nip formed between the photosensitive member and the transfer member toward the fixing nip. And. The guide surface of the guide member is opposite to the first guide surface extending from the upstream end of the guide surface in the guide direction toward the downstream side of the guide direction and the first guide surface across the center in the paper width direction of the paper. A second guide that is disposed on the side and extends from the upstream end of the guide surface in the guide direction toward the downstream side of the guide direction, and is recessed between the first guide surface and the downstream side in the guide direction. And a surface. Further, the size of the concave portion in the paper width direction becomes smaller as it goes toward the downstream side in the guiding direction so that the area of the guiding surface becomes larger toward the downstream side in the guiding direction.

  According to such a configuration, the contact area between the sheet and the guide surface of the guide member gradually increases toward the downstream side in the guide direction. Therefore, when the sheet is guided by the guide member, the sheet conveyance resistance increases rapidly, and the sheet conveyance temporarily stops, or the sheet conveyance speed temporarily decreases. This can be suppressed. As a result, the occurrence of defective image formation can be suppressed.

The schematic diagram of the cross section of a laser printer. FIG. 3 is an enlarged view of a photosensitive drum, a transfer roller, and a fixing device. The perspective view of a guide member. FIG. 4 is a cross-sectional view taken along line A-A ′ of FIG. 3. 5A is a cross-sectional view of the guide member, FIG. 5A is a cross-sectional view taken along the line BB ′ of FIG. 3, FIG. 5B is a cross-sectional view taken along the CC ′ line of FIG. ) Is a sectional view taken along the line DD ′ of FIG. 6A is a cross-sectional view taken along the line BB ′ of FIG. 3, FIG. 6B is a cross-sectional view taken along the line CC ′ of FIG. 3, and FIG. c) is a sectional view taken along the line DD 'of FIG. Explanatory drawing for demonstrating the modification of a guide member.

<Embodiment 1>
Embodiment 1 of the present invention will be described in detail with reference to the drawings as appropriate.

1. First, the overall configuration of the laser printer 1 will be described with reference to FIG. The laser printer 1 includes a main body frame 10, a paper feeding unit 20 for feeding paper, an image forming unit 30 for forming an image on paper fed by the paper feeding unit 20, and an image forming unit 30. And a paper discharge unit 40 for discharging the paper on which the image is formed to the outside of the main body frame 10.

  The main body frame 10 supports the paper feed unit 20, the image forming unit 30, and the paper discharge unit 40. The paper feed unit 20 includes a paper feed cassette 21 for storing paper therein, and a paper feed roller 22 for transporting paper picked up from the paper feed cassette 21 toward the image forming unit 30. . The paper feed cassette 21 is configured to be detachable from the main body frame 10 and is disposed at the bottom of the main body frame 10.

  The image forming unit 30 includes an exposure device 50 disposed on the rear side of the main body frame 10, a photoreceptor cartridge 60 disposed on the front side of the exposure device 50, and a fixing device 70 disposed on the upper side of the photoreceptor cartridge 60. It is equipped with.

  The exposure device 50 is configured to form an electrostatic latent image on the outer peripheral surface of the photosensitive drum 61. The photosensitive cartridge 60 is configured to be detachable from the main body frame 10, and includes a photosensitive drum 61 for forming an electrostatic latent image on the outer peripheral surface, and charging for uniformly charging the outer peripheral surface of the photosensitive drum 61. A transfer nip N1 is formed between the photosensitive drum 61 and the developing roller 63 that contacts the photosensitive drum 61 in contact with the photosensitive drum 61 and the photosensitive drum 61, and transfers the developer image to the sheet. A transfer roller 64. The photosensitive drum 61 is an example of a photoconductor, and the transfer roller 64 is an example of a transfer member.

  The fixing device 70 is arranged to fix the developer image formed on the paper, and includes a heating roller 71 having a heater and a pressure roller 72 that forms a fixing nip N2 between the heating roller 71 and the heating roller 71. It is equipped with. The heating roller 71 is an example of a heating member, and the pressure roller 72 is an example of a pressure member.

  The paper discharge unit 40 is configured to discharge the paper that has passed through the fixing nip N2 to the outside of the main body frame 10.

2. Configuration of Fixing Device 70 Next, the configuration of the fixing device 70 will be described with reference to FIGS. As illustrated in FIG. 2, the fixing device 70 includes a heating roller 71, a pressure roller 72, a fixing frame 73, and a guide member 100.

  The heating roller 71 is heated to a predetermined temperature (a temperature within a range of 170 ° C. to 200 ° C.) by a heater provided therein. The pressure roller 72 is urged toward the heating roller 71 by a spring. As a result, the pressure roller 72 forms a fixing nip N <b> 2 with the heating roller 71. The fixing frame 73 accommodates a heating roller 71 and a pressure roller 72. The guide member 100 is disposed on the upstream side of the transfer nip N1 in the guide direction X and on the downstream side of the fixing nip N2 in the guide direction X. It has a guide surface 110 that guides to.

  Further, as shown in FIG. 3, the guide surface 110 includes a first guide surface 120, a second guide surface 130, and a third guide surface 140.

  The first guide surface 120 is configured to support one side of the first paper P1 in the paper width direction, and extends from the center Y of the guide surface 110 in the paper width direction to one end of the guide member 100 in the paper width direction. Has been placed. The first sheet P1 is an A4 size sheet, and the center Y of the guide surface 110 is the center of the first sheet P1 conveyed on the guide surface 110 in the sheet width direction. .

  The first guide surface 120 extends from the upstream end 111 of the guide surface 110 in the guide direction X toward the downstream side in the guide direction X. Further, the size of the first guide surface 120 in the paper width direction increases as it goes downstream in the guide direction X. Specifically, the size of the downstream end 122 of the first guide surface 120 in the guide direction X is larger than the size of the upstream end 121 of the first guide surface 120 in the guide direction X. Therefore, the area of the first guide surface 120 becomes larger toward the downstream side in the guide direction X.

  The second guide surface 130 is configured to support the other side of the first sheet P1 in the sheet width direction, and extends from the center Y of the guide surface 110 in the sheet width direction to the other end of the guide member 100 in the sheet width direction. Are arranged. In other words, the second guide surface 130 is disposed on the opposite side of the first guide surface 120 across the center Y of the guide surface 110 in the paper width direction.

  The second guide surface 130 extends from the upstream end 111 of the guide surface 110 in the guide direction X toward the downstream side in the guide direction X. Further, the dimension of the second guide surface 130 in the sheet width direction increases as it goes downstream in the guide direction X. Specifically, the size of the downstream end 132 of the second guide surface 130 in the guide direction X is larger than the size of the upstream end 131 of the second guide surface 130 in the guide direction X. Therefore, the area of the second guide surface 130 becomes larger toward the downstream side in the guide direction X.

  Further, the downstream end 132 of the second guide surface 130 in the guide direction X is continuous with the downstream end 122 of the first guide surface 120 in the guide direction X. The downstream end 112 of the guide surface 110 in the guide direction X is continuous with the downstream end 122 of the first guide surface 120 and the downstream end 132 of the second guide surface 130. Therefore, the size of the downstream end 112 of the guide surface 110 in the paper width direction is larger than the size of the upstream end 111 of the guide surface 110 in the paper width direction.

  Further, the dimension between the upstream end 121 of the first guide surface 120 and the upstream end 131 of the second guide surface 130 in the sheet width direction is smaller than the dimension of the first sheet P1 in the sheet width direction. Further, the dimension between the upstream end 121 of the first guide surface 120 and the upstream end 131 of the second guide surface 130 in the sheet width direction is larger than the dimension of the second sheet P2 in the sheet width direction. The second paper P2 is a postcard.

  Further, the second guide surface 130 forms a recessed portion 150 that is recessed toward the downstream side in the guide direction X between the second guide surface 130 and the first guide surface 120. The size of the concave portion 150 in the sheet width direction is smaller toward the downstream side in the guide direction X so that the area of the guide surface 110 is increased toward the downstream side in the guide direction X.

  Specifically, the recessed portion 150 has an arc shape and is recessed from the upstream end 111 of the guide surface 110 in the guide direction X toward the downstream side. Further, the concave portion 150 is disposed on the upstream side in the guide direction X from the downstream end 112 of the guide surface 110 in the guide direction X so as to include the center Y of the guide surface 110.

  The third guide surface 140 is configured to guide the second sheet P2 toward the fixing nip N2, and is disposed between the first guide surface 120 and the second guide surface 130.

  Further, the upstream end 141 of the third guide surface 140 in the guide direction X is separated from the first guide surface 120 in the sheet thickness direction, as shown in FIG. On the other hand, the downstream end 142 of the third guide surface 140 in the guide direction X is continuous with the first guide surface 120. The third guide surface 140 is inclined with respect to the first guide surface 120 so as to approach the first guide surface 120 as it goes downstream in the guide direction X. Further, the inclination of the third guide surface 140 is linear with respect to the first guide surface 120.

3. Process in which a sheet is guided on the guide surface 110 Next, with reference to FIGS. 5 and 6, a process in which each of the first sheet P1 and the second sheet P2 is guided on the guide surface 110. explain. First, the process in which the first paper P1 is guided on the guide surface 110 will be described with reference to FIGS.

  Both ends in the width direction of the first sheet P1 that have passed through the transfer nip N1 are in contact with the upstream end 121 of the first guide surface 120 and the upstream end 131 of the second guide surface 130, as shown in FIG. To do.

  Thereafter, as the first paper P1 is guided downstream in the guide direction X, the dimensions of the first guide surface 120 and the second guide surface 130 in the paper width direction increase. Therefore, the area of the guide surface 110 increases as shown in FIG.

  Thereafter, as shown in FIG. 5C, the leading edge of the first sheet P1 reaches the downstream end 122 of the first guide surface and the downstream end 132 of the second guide surface. In other words, the leading edge of the first sheet P1 reaches the downstream end 112 of the guide surface 110. Then, the entire area of the first sheet P <b> 1 in the sheet width direction comes into contact with the downstream end 112 of the guide surface 110. Therefore, the first sheet P1 is conveyed along the fixing nip N2.

  Next, a process in which the second paper P2 is guided by the guide member 100 will be described with reference to FIGS. The second sheet P2 that has passed through the transfer nip N1 contacts the upstream end 141 of the third guide surface 140 as shown in FIG. At this time, substantially the entire area of the second sheet P2 in the sheet width direction is in contact with the third guide surface 140.

  Thereafter, as shown in FIG. 6B, as the second paper P2 is guided along the guide direction X, the dimensions of the first guide surface 120 and the second guide surface 130 in the paper width direction increase. The third guide surface 140 approaches the first guide surface 120 and the second guide surface 130. Therefore, the second paper P <b> 2 is conveyed so as to approach the first guide surface 120 and the second guide surface 130.

  Thereafter, after the second sheet P2 passes over the third guide surface, the leading end of the second sheet P2 is positioned at the downstream end 122 and the second end of the first guide surface 120 as shown in FIG. 6C. It reaches the downstream end 132 of the guide surface 130. That is, the leading edge of the second sheet P2 reaches the downstream end 112 of the guide surface 110. Then, substantially the entire area of the second sheet P2 in the sheet width direction comes into contact with the guide surface 110. Therefore, the second paper P2 is conveyed in a state along the fixing nip N2.

4). Effects of Embodiment 1 (1) The second guide surface 130 forms a concave portion 150 that is recessed toward the downstream side in the guide direction X between the first guide surface 120 and the second guide surface 120. In addition, the size of the concave portion 150 in the paper width direction decreases as the area of the guide surface 110 increases toward the downstream side in the guide direction X and decreases toward the downstream side in the guide direction X.

  According to such a configuration, the area of the guide surface 110 of the guide member 100 gradually increases toward the downstream side in the guide direction X. For this reason, when the paper is guided on the guide member 100, it is possible to suppress the paper transport resistance from rapidly increasing and temporarily stopping the paper transport. As a result, the occurrence of defective image formation can be suppressed.

  (2) The concave portion 150 includes the center Y of the guide surface 110 in the paper width direction.

  According to such a configuration, the sheet passing over the guide surface 110 is gradually supported by the guide surface 110 from both ends in the sheet width direction toward the center as it goes downstream in the guide direction X. . For this reason, when the sheet is guided on the guide surface 110, the sheet is not easily inclined with respect to the guide direction X. As a result, the behavior of the sheet is stabilized, and the sheet can be stably conveyed toward the fixing nip N2.

  (3) The concave portion 150 has an arc shape.

  According to such a configuration, the area of the guide surface 110 increases along the arc shape toward the downstream side in the guide direction X. Therefore, the area of the guide surface 110 gradually increases toward the downstream side in the guide direction X. As a result, it is possible to further suppress the paper transport resistance from rapidly increasing, the paper transport speed from being temporarily reduced, and the paper transport from being temporarily stopped.

  (4) The guide surface 110 of the guide member 100 includes a third guide surface 140 between the first guide surface 120 and the second guide surface 130. Further, the upstream end of the third guide surface 140 in the guide direction X is disposed away from the first guide surface 120 and the second guide surface 130 in the sheet thickness direction. Further, the downstream end of the third guide surface 140 in the guide direction X is continuous with the first guide surface 120 and the second guide surface 130 in the sheet thickness direction. Furthermore, the third guide surface 140 approaches the first guide surface 120 and the second guide surface 130 as it goes downstream in the guide direction X.

  According to such a configuration, it is possible to guide the second sheet P2 smaller than the interval between the first guide surface 120 and the second guide surface 130 toward the fixing nip N2.

  As a result, a plurality of sizes of paper can be stably guided toward the fixing nip N2.

  (5) The third guide surface 140 is configured to incline linearly so as to approach the first guide surface 120.

  According to such a configuration, the second sheet P <b> 2 guided on the third guide surface 140 is guided linearly toward the first guide surface 120. As a result, the second sheet P2 can be stably guided toward the fixing nip N2.

<Modification>
The guide member of the present invention is not limited to the first embodiment. For example, the guide member 200 may include a main body portion 210 and a plurality of ribs 220 as shown in FIG.

  According to such a configuration, the contact area between the sheet and the guide surface 110 of the guide member 200 becomes smaller. As a result, the sheet conveyance resistance can be further reduced.

  In the first embodiment, the arcuate recess 150 is formed by the first guide surface 120 and the second guide surface 130. However, the present invention is not limited to this. For example, the concave portion 150 may have a step shape or a taper.

  In the first embodiment, the size of the downstream end 112 of the guide surface 110 in the guide direction X is configured to be larger than the width of the first sheet P1. However, the present invention is not limited to this. For example, the size of the downstream end 112 of the guide surface 110 may be configured to be smaller than the width of the first sheet P1.

  According to such a configuration, both ends of the first sheet P1 in the sheet width direction do not contact the downstream end 112 of the guide surface 110. Therefore, the central portion of the first paper P1 in the paper width direction enters the fixing nip N2 before both end portions of the first paper P1 in the paper width direction. As a result, it is possible to suppress the occurrence of wrinkles on the first sheet P1 after the first sheet P1 has passed through the fixing nip N2.

  In the first embodiment, the photoconductor cartridge 60 includes the photoconductive drum 61 and the transfer roller 64. However, the present invention is not limited to this. For example, the photosensitive drum 61 may be a photosensitive belt, a secondary transfer belt, or the like. The transfer roller 64 may be a transfer belt, a transfer brush, or the like.

  In the first exemplary embodiment, the fixing device 70 includes the heating roller 71 and the pressure roller 72. However, the present invention is not limited to this. For example, the heating roller 71 may be a heating belt. Note that the heating belt may include a base layer made of SUS, nickel, polyimide, or the like. The pressure roller 72 may be a pressure belt. Note that the pressure belt may include a base layer made of SUS, nickel, polyimide, or the like.

DESCRIPTION OF SYMBOLS 1 Laser printer 60 Photoconductor cartridge 61 Photosensitive drum 64 Transfer roller 70 Fixing device 71 Heating roller 72 Pressure roller 73 Fixing frame 100 Guide member 110 Guide surface 120 First guide surface 130 Second guide surface 140 Third guide surface 150 Concavity N1 Transfer nip N2 Fixing nip

Claims (7)

A photoreceptor,
A transfer member that forms a transfer nip for transferring a developer image to a sheet with the photoreceptor;
A heating member having a heater;
A pressure member that forms a fixing nip between the heating member and the developer image for fixing to the paper;
A guide member having a guide surface that guides a sheet from the transfer nip to the fixing nip in a predetermined guide direction orthogonal to the sheet width direction,
The guide surface of the guide member is
A first guide surface extending from an upstream end of the guide surface in the guide direction toward a downstream side of the guide direction;
The first guide is disposed on the opposite side of the first guide surface across the center in the paper width direction of the paper and extends from the upstream end of the guide surface in the guide direction toward the downstream side of the guide direction. A second guide surface that forms a recessed portion that is recessed toward the downstream side of the guide direction between the surface and the surface,
2. An image forming apparatus according to claim 1, wherein the size of the concave portion in the paper width direction is reduced as the area of the guide surface is increased toward the downstream side of the guide direction, and is decreased toward the downstream side of the guide direction.   The image forming apparatus, wherein the concave portion is arranged so as to include the center of the guide surface in the paper width direction.   The image forming apparatus according to claim 1, wherein the concave portion has an inclination.   The image forming apparatus according to claim 3, wherein the concave portion has an arc shape. The guide surface of the guide member includes a third guide surface between the first guide surface and the second guide surface,
An upstream end of the third guide surface in the guide direction is disposed away from the first guide surface and the second guide surface in the sheet thickness direction,
The downstream end of the third guide surface in the guide direction is connected to the first guide surface and the second guide surface in the sheet thickness direction,
The said 3rd guide surface inclines so that it may approach the said 1st guide surface and the said 2nd guide surface as it goes to the downstream of the said guide direction, The any one of Claim 1 to 4 characterized by the above-mentioned. The image forming apparatus described.   The image forming apparatus according to claim 5, wherein the third guide surface is linearly inclined so as to approach the first guide surface and the second guide surface. A main body casing having a photosensitive member cartridge having a photosensitive member and a transfer member is detachably provided, a heating member having a heater, a pressure member that contacts the heating member to form a fixing nip, and a sheet of paper A guide member having a guide surface for guiding from a transfer nip formed between a photoconductor and the transfer member toward the fixing nip, and a fixing device comprising:
The guide surface of the guide member is
A first guide surface extending from an upstream end of the guide surface in the guide direction toward a downstream side of the guide direction;
The first guide is disposed on the opposite side of the first guide surface across the center in the paper width direction of the paper and extends from the upstream end of the guide surface in the guide direction toward the downstream side of the guide direction. A second guide surface that forms a recessed portion that is recessed toward the downstream side of the guide direction between the surface and the surface,
The fixing device according to claim 1, wherein the size of the concave portion in the paper width direction decreases as the area of the guide surface increases toward the downstream side of the guide direction and decreases toward the downstream side of the guide direction.