JP2017102210A - Fixing device and image forming apparatus including the fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent, when a recording sheet having a width size smaller than a predetermined size is used, an excessive increase in temperature of portions of a fixing member 41 and a pressure member 42 through which the recording sheet does not pass without causing a reduction in fixing temperature.SOLUTION: First ribs 431b perpendicular to a recording sheet width direction are formed respectively on the inside in the recording sheet width direction of a pair of first variable closing parts 442 in a first housing part 431, and second ribs 432b perpendicular to the recording sheet width direction are formed respectively on the inside in the recording sheet width direction of a pair of second variable closing parts 452 in a second housing part 432.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a fixing device and an image forming apparatus including the fixing device.

  In general, an electrophotographic image forming apparatus includes a fixing device that fixes a toner image on a recording sheet by heating and pressing. The fixing device includes a rotatable fixing member, a pressure member pressed against the fixing member, and a housing that houses the fixing member and the pressure member. The fixing member is heated by heating means such as a halogen lamp. Then, the recording paper passes between the fixing member and the pressure member, so that the toner image on the recording paper is heated and pressurized and fixed on the recording paper.

  The housing includes a first housing portion that houses the fixing member therein and a second housing portion that houses the pressure member inside. A first opening that opens to the pressure member side is formed in the first casing, and the fixing member is exposed from the first opening. A second opening that opens toward the fixing member is formed in the second casing, and the pressure member is exposed from the second opening and is in contact with the fixing member.

  In this type of fixing device, various techniques have been proposed in order to improve the heat retaining properties in the first and second housing portions. For example, in Patent Document 1, a portion of the first opening that occupies the downstream side in the recording paper conveyance direction with respect to the fixing member is covered by the first closing member, and the recording paper is conveyed more than the pressure member in the second opening. A portion occupying the downstream side in the direction is covered with the second closing member.

  Both end portions of the first closing member are separated from the intermediate portion to form a first variable closing portion. Similarly, both end portions of the second closing member are separated from the intermediate portion to form a second variable closing portion. Each of the first and second variable closing portions can be switched from a closed state to an open state by a switching mechanism. When the width size of the recording paper is smaller than the predetermined size, the first and second variable closing portions are respectively switched from the closed state to the opened state by the switching mechanism. As a result, air permeability is secured to the portion of the surface of the fixing member and the pressure member where the recording paper does not pass (that is, both ends of the fixing member and the pressure member) to prevent an excessive temperature rise in the portion. Yes.

JP 2012-8206 A

  However, in the conventional fixing device disclosed in Patent Document 1, when the first variable blocking portion is switched from the closed state to the open state by the switching mechanism, the opening portion of the first variable blocking portion is directed toward the center of the fixing member. Outside air flows in. Similarly, when the second variable blocking portion is switched from the closed state to the open state by the switching mechanism, outside air flows from the open portion by the second variable blocking portion toward the center of the pressurizing member. As a result, not only the area where the recording paper does not pass but also the area where the recording paper passes on the surface of the fixing member and the heating member are cooled by the air flow. As a result, there is a problem that the fixing temperature by the fixing member and the pressure member is lowered, resulting in poor fixing of the toner.

  The present invention has been made in view of the above points, and an object of the present invention is to prevent a decrease in fixing temperature when a recording sheet having a width size smaller than a predetermined size is used, and a fixing member and The object is to prevent overheating of the portion of the pressure member where the recording paper does not pass.

  The fixing device according to the present invention includes a rotatable fixing member that is heated by a heating unit, a pressure member that is pressed against the fixing member and sandwiches and conveys recording paper between the fixing member, and the fixing member. A first housing part that is accommodated inside and has an opening that opens to the pressure member side, and a first housing part that accommodates the pressure member and opens to the fixing member side. Two housing portions, a first closing member that closes a portion of the opening portion of the first housing portion that occupies the downstream side of the fixing member in the recording paper conveyance direction, and the opening portion of the second housing portion And a second closing member that closes a portion occupying the downstream side of the pressure member in the recording paper conveyance direction.

  The first closing member includes at least a first fixed closing portion provided in a position range corresponding to a passage region of the recording paper whose width size is smaller than a predetermined size, and recording paper conveyance in the first fixed closing portion. Including a pair of first variable closing portions provided adjacent to both ends in the recording paper width direction orthogonal to the direction and configured to be switchable between a closed state and an open state, and the second closing member includes at least A second fixed closing portion provided in a position range corresponding to a passage region of the recording paper whose width size is smaller than the predetermined size, and provided adjacent to both ends in the recording paper width direction in the second fixed closing portion, A pair of second variable blocking portions configured to be switchable between a closed state and an open state, and the inner side in the recording paper width direction than the pair of first variable blocking portions in the first housing unit, Recording paper width direction A first rib perpendicular to the recording paper width direction is formed on the inner side in the recording paper width direction than the pair of second variable closing portions in the second casing portion. Has been.

  According to the present invention, when a recording paper having a width size smaller than a predetermined size is used, the fixing temperature and the pressure member are prevented from overheating at a portion where the recording paper does not pass while preventing the fixing temperature from being lowered. can do.

FIG. 1 is a schematic configuration diagram of an image forming apparatus including a fixing device according to an embodiment. FIG. 2 is a schematic diagram illustrating a fixing device according to the embodiment. 3 is a view in the direction of the arrow III in FIG. FIG. 4 is a view taken in the direction of arrow IV in FIG. 5 is a cross-sectional view taken along the line VV in FIG. FIG. 6 is a table showing a result of a test for confirming energy saving using the fixing device of the embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

<Embodiment>
FIG. 1 shows an image forming apparatus 1 according to the present embodiment. The image forming apparatus 1 is a monochrome laser printer in this embodiment. In the following description, “front side” and “rear side” mean the front side and the rear side of the image forming apparatus 1 (the front side and the rear side in the direction perpendicular to the paper in FIG. 1), and “left side” and “right side” It means “left side” and “right side” when the image forming apparatus 1 is viewed from the front side.

  The image forming apparatus 1 includes a paper feeding unit 10, an image forming unit 20, a fixing unit 40, a paper discharge unit 50, and a housing 60. A plurality of transport roller pairs 11 to 13 that sandwich and transport the recording paper P are disposed in the recording paper transport path T from the paper supply unit 10 to the paper discharge unit 50. The paper feeding unit 10 is disposed in the lower part of the housing 60. The paper feed unit 10 includes a paper feed cassette 10a in which sheet-like recording paper P is accommodated, and a pickup roller 10b for taking out the recording paper P in the paper feed cassette 10a and sending it out of the cassette. Yes. The recording paper P sent out of the cassette from the paper feed cassette 10 a is supplied to the image forming unit 20 through the transport roller pair 11.

  The image forming unit 20 includes a photosensitive drum 21, a charger 23, an exposure device 25, a developing device 27, a transfer device 29, and a toner container (not shown). In the image forming unit 20, the peripheral surface of the photosensitive drum 21 is charged by the charger 23, and then the original image data (for example, image data of the original image received from the external terminal) is applied to the surface of the photosensitive drum 21 by the exposure device 25. ) To form an electrostatic latent image. The electrostatic latent image formed (supported) on the surface of the photosensitive drum 21 is developed with toner charged by the developing device 27. The toner image developed by the developing device 27 is moved and transferred to the recording paper P by the transfer bias applied from the transfer device 29. The recording sheet P after the transfer is supplied to the fixing unit 40 by the transfer roller 29 a of the transfer unit 29 and the photosensitive drum 21.

  The fixing unit 40 includes a fixing roller 41 and a pressure roller 42 that is pressed against the fixing roller 41 with a predetermined pressing load. Inside the fixing roller 41, a halogen lamp (not shown) as a heating unit is arranged. The peripheral surface of the fixing roller 41 is heated by the heat generated from the halogen lamp.

  The fixing unit 40 fixes the toner image on the recording paper P by pressing and heating the recording paper P supplied from the image forming unit 20 between the fixing roller 41 and the pressure roller 42. Then, the recording paper P on which the toner image is fixed by the fixing unit 40 is sent out to the downstream side by the rollers 41 and 42. The fed recording paper P is discharged to a paper discharge unit 50 formed on the upper surface of the housing 60 by a plurality of conveying roller pairs 12 and 13.

  As shown in FIG. 2, the fixing roller 41 and the pressure roller 42 of the fixing unit 40 are accommodated in a housing 43 and unitized. The housing | casing 43 has comprised the hollow case shape extended in the front-back direction in the whole view. A paper feed port 43a is formed on the lower side wall of the housing 43, and a paper discharge port 43b is formed on the upper side wall. The recording paper P supplied from the image forming unit 20 is introduced into the housing 43 from the paper feed port 43a of the housing 43, passes between the rollers 41 and 42, and then is ejected from the paper ejection port 43b to the housing. 43 is discharged outside.

  The housing 43 has a first housing portion 431 and a second housing portion 432 that face each other across the recording paper transport path T. The first housing portion 431 accommodates the fixing roller 41, and the second housing portion 432 accommodates the pressure roller 42.

  A first opening 431 a that opens to the pressure roller 42 side is formed in the first housing portion 431. A part of the fixing roller 41 is exposed in the recording paper conveyance path T from the first opening 431a. A second opening 432 a that opens to the fixing roller 41 side is formed in the second housing portion 432. A part of the pressure roller 42 is exposed in the recording paper conveyance path T from the second opening 432 a and is in contact with the fixing roller 41. The contact portion between the fixing roller 41 and the pressure roller 42 forms a nip portion for nipping and conveying the recording paper P.

  Of the first opening 431a of the first housing portion 431, a portion occupying the downstream side in the recording paper conveyance direction with respect to the exposed portion of the fixing roller 41 (that is, the edge of the first opening 431a on the paper discharge port 43b side and the fixing roller) 41), a first closing member 44 is provided. Similarly, a portion of the second opening 432a of the second housing portion 432 that occupies the downstream side in the recording paper transport direction from the exposed portion of the pressure roller 42 (that is, the end of the second opening 432a on the paper discharge port 43b side). A second closing member 45 is provided at a portion between the edge and the pressure roller 42. The 1st closure member 44 and the 2nd closure member 45 are comprised by the sheet-like member made from resin, for example.

  As shown in FIG. 3, the first closing member 44 is divided into a first fixed closing portion 441 and a pair of first variable closing portions 442. The first fixed closing portion 441 is formed in a rectangular plate shape that is long in the recording paper width direction. The base end side (upper side in FIG. 3) of the first fixed closing portion 441 is fixed in the vicinity of the upper end edge of the first opening 431 a (not shown in FIG. 3) in the first housing portion 431. The edge portion on the tip side (the lower side in FIG. 3) of the first fixed closing portion 441 is in contact with the surface of the fixing roller 41.

  Here, the image forming apparatus 1 uses a plurality of sizes of recording paper (A3, B4, A4, B5, and A5 in this embodiment) having different width sizes (sizes in a direction orthogonal to the recording paper conveyance direction). It is possible, and both end positions of the first fixed blocking portion 441 in the recording sheet width direction are from positions where both ends in the width direction of the recording sheet having a predetermined width size (A5 size which is the minimum size in the present embodiment) pass. It is located slightly outside. Note that both end positions of the first fixed closing portion 441 in the recording sheet width direction may coincide with positions where both ends of the recording sheet P having a predetermined width size pass. In other words, the first fixed blocking portion 441 may be provided at least in the passing range of the recording paper P having a predetermined width size (A5 size in the present embodiment).

  The pair of first variable blocking portions 442 are disposed adjacent to both ends of the first fixed blocking portion 441 in the recording paper width direction. The pair of first variable closing portions 442 is formed in a rectangular plate shape that is long in the recording paper width direction. The base end side edge of each first variable closing portion 442 is fixed to the rotation shaft portion 443, and the tip end is in contact with the surface of the fixing roller 41. The rotation shaft portion 443 is disposed along the upper edge of the first opening 431a of the first housing portion 431. Both end portions of the rotation shaft portion 443 are rotatably supported by bearing portions formed on the first housing portion 431. The rotation shaft portion 443 is rotationally driven by a driving portion 46 made of a motor or the like. The drive unit 46 is controlled by the control unit 47.

  When the rotation shaft portion 443 is rotationally driven by the drive unit 46, the first variable closing portion 442 rotates in the direction perpendicular to the paper surface of FIG. 3 with the rotation shaft portion 443 serving as a fulcrum, thereby the first variable. The blocking part 442 is switched between a closed state and an open state. In the closed state, a portion adjacent to both ends of the first fixed closing portion 441 in the recording paper width direction is closed by the first variable closing portion 442, while in an open state, the portion is opened by the first variable closing portion 442. .

  As shown in FIG. 4, the second closing member 45 is divided into a second fixed closing portion 451 and a pair of second variable closing portions 452.

  The second fixed closing portion 451 is formed in a rectangular plate shape that is long in the recording paper width direction. An edge portion on the base end side (upper side in FIG. 3) of the second fixed closing portion is fixed in the vicinity of the upper end edge of the second opening 432a (not shown in FIG. 4) in the second housing portion. The edge portion on the tip side (the lower side in FIG. 3) of the second fixed closing portion 451 is in contact with the surface of the pressure roller 42.

  Both end positions of the second fixed closing portion 451 in the recording paper width direction are located slightly outside the positions where both side ends of the recording paper P having the predetermined width size pass. Note that both end positions of the second fixed closing portion 451 in the recording sheet width direction may coincide with positions where both ends of the recording sheet P having a predetermined width size pass. That is, the second fixed blocking portion 451 may be provided at least in the passage range of the recording paper P having a predetermined width size.

  The pair of second variable blocking portions 452 are disposed adjacent to both ends of the second fixed blocking portion 451 in the recording paper width direction. The pair of second fixed blocking portions 451 are formed in a rectangular plate shape that is long in the recording paper width direction. An edge portion on the base end side (upper side in FIG. 4) of the second variable closing portion 452 is fixed to the rotation shaft portion 453, and a distal end edge is in contact with the surface of the pressure roller 42. The rotation shaft portion 453 is disposed along the upper end edge of the second opening 432 a of the second housing portion 432. Both end portions of the rotation shaft portion 453 are rotatably supported by bearing portions formed on the second housing portion 432. The rotating shaft portion 453 is rotationally driven by the driving portion 46.

  When the rotation shaft portion 453 is driven to rotate by the drive unit 46, the second variable blocking portion 452 rotates in the direction perpendicular to the paper surface of FIG. 4 with the rotation shaft portion 453 serving as a fulcrum. 452 is switched between a closed state and an open state. In the closed state, the portions adjacent to both ends of the second fixed closed portion 451 in the recording paper width direction are closed by the second variable closed portion 452, while in the open state, the portion is opened by the second variable closed portion 452. .

  The control unit 47 includes a microcomputer having a ROM, a RAM, a CPU, and the like. The control unit 47 controls the driving unit 46 to perform opening / closing control of the first variable blocking unit 442 and the second variable blocking unit 452.

  The control unit 47 determines whether or not it exceeds the width size of the recording paper P (the length in the direction orthogonal to the recording paper transport direction) based on the print job data being executed. When the control unit 47 determines that the width size of the recording paper P exceeds the predetermined size, the control unit 47 controls the first variable blocking unit 442 and the second variable blocking unit 452 to be closed. Therefore, when the width size of the recording paper P exceeds a predetermined size, the first variable closing portion 442 and the second variable closing portion 452 are closed, so that the inside of the first casing portion 431 and the second casing portion The heat in 432 can be prevented from escaping from the first opening 431a and the second opening 432a to the outside, and the necessary fixing temperature can be obtained with a small amount of power.

  Here, when the width size of the recording paper P to be printed is equal to or smaller than the predetermined size (A5 size in the present embodiment), both ends of the fixing roller 41 and the pressure roller 42 in the recording paper width direction are the recording paper. Since P does not pass through, the heat at both ends is not transmitted to the recording paper P. For this reason, the temperature of the both ends of the fixing roller 41 and the pressure roller 42 may rise excessively, and the surface coat of each of the rollers 41 and 42 may be worn.

  Therefore, the control unit 47 is configured to control the first variable blocking unit 442 and the second variable blocking unit 452 to the open state when it is determined that the width size of the recording paper P is equal to or smaller than the predetermined size. Yes. According to this, when the width size of the recording paper P is equal to or smaller than the predetermined size, the first variable closing portion 442 and the second variable closing portion 452 are opened, and the first variable closing portion 442 and the second variable closing portion 442 are in the open state. Outside air flows into the first housing part 431 and the second housing part 432 from the part opened by the blocking part 452 (see thick arrows in FIG. 5). Therefore, both ends of the fixing roller 41 and the pressure roller 42 in the recording paper width direction can be cooled by the air that has flowed in. Therefore, it is possible to prevent an excessive temperature increase in a region where the recording paper P does not pass through the fixing roller 41 and the pressure roller 42.

  However, the air flow that flows into the first housing portion 431 and the second housing portion 432 due to the opening of the first variable closing portion 442 and the second variable closing portion 452 is caused by the fixing roller 41 and the pressure roller. 42 flows toward the center of the recording paper in the width direction. For this reason, the recording paper passage area in the fixing roller 41 and the pressure roller 42 is also cooled by this air flow. As a result, the necessary fixing temperature may not be obtained.

  Therefore, in the present embodiment, as shown in FIGS. 2 and 5, the first rib 431b and the second rib 432b are provided in the first and second housing portions 431 and 432, respectively. The first rib 431b is formed so as to close the entire space section in the first housing portion 431 when viewed from the recording paper width direction. Specifically, the first rib 431b is formed of a plate-like portion arranged perpendicular to the recording paper width direction, and a notch 431c (see FIG. 2) is formed in a portion corresponding to the fixing roller 41 in the first rib 431b. Is formed. A slight gap is formed between the inner peripheral surface of the notch 431 c and the outer peripheral surface of the fixing roller 41. Note that the inner peripheral surface of the notch 431 c may be brought into contact with the outer peripheral surface of the fixing roller 41.

  Similarly, the second rib 432b and the first rib 431b are formed so as to close the entire space section in the second housing portion 432 when viewed from the recording paper width direction. Specifically, the second rib 432b is composed of a plate-like portion arranged perpendicular to the recording paper width direction, and a notch 432c (see FIG. 2) is formed in a portion corresponding to the pressure roller 42 in the second rib 432b. ) Is formed. A slight gap is formed between the inner peripheral surface of the notch 432 c and the outer peripheral surface of the pressure roller 42. Note that the inner peripheral surface of the notch 432 c may be brought into contact with the outer peripheral surface of the pressure roller 42.

  The space in the first housing part 431 is divided into three in the recording paper width direction by the first rib 431b, and the space in the second housing part 432 is divided into three in the recording paper width direction by the second rib 432b. Has been. The pair of first ribs 431b are disposed slightly inside (in the present embodiment, 1 mm to 25 mm inside) the inner edge position E1 of the pair of first variable closing portions 442 in the recording paper width direction. The pair of first ribs 431b are formed at positions corresponding to both side edges in the width direction of the recording paper P having a predetermined width size (A5 size in the present embodiment).

  Similarly, the pair of second ribs 432b is disposed slightly inside (in the present embodiment, 1 mm to 25 mm inside) the inner edge E2 of the pair of second variable closing portions 452 in the recording paper width direction. In the present embodiment, the pair of second ribs 432b are formed at positions corresponding to both side edges in the width direction of the recording paper P having the predetermined size.

  Therefore, in the present embodiment, when the width size of the recording paper P is equal to or smaller than the predetermined size, when the first variable closing portion 442 and the second variable closing portion 452 are opened, the first housing portion 431 and The airflow (see the two-dot chain line arrow in FIG. 5) flowing into the second housing portion 432 can be blocked by the pair of first ribs 431b and the pair of second ribs 432b. Therefore, it is possible to prevent the inflowing air flow from reaching the recording paper passage area, thereby preventing an unnecessary decrease in the fixing temperature. Therefore, the necessary fixing temperature can be reliably obtained with less power. Therefore, energy saving can be improved.

  In the present embodiment, the first rib 431b and the second rib 432b are respectively formed at positions corresponding to both side edges in the width direction of the recording paper P having the predetermined size. Therefore, when the width size of the recording paper P is equal to or smaller than the predetermined size, it is possible to reliably prevent the outside air from flowing into the passage region of the recording paper P.

  In the present embodiment, the first rib 431b has a shape in which a portion corresponding to the fixing roller 41 of the plate-like portion arranged perpendicular to the recording paper width direction is cut out, and the second rib 432b is It has a shape in which a portion corresponding to the pressure roller 42 of the plate-like portion arranged perpendicular to the recording paper width direction is cut out. Thereby, the whole space section perpendicular | vertical to the recording paper width direction in the 1st and 2nd housing | casing parts 431 and 432 can be interrupted | blocked by the 1st and 2nd ribs 431b and 432b. Therefore, the blocking effect of the air flow that has flowed in can be further improved. In addition, by providing the first and second ribs 431b and 432b, the strength of the first and second housing portions 431 and 432 can be improved. Therefore, it is possible to improve image quality by suppressing the rotational shake of the fixing roller 41 and the pressure roller 42.

"Example"
Next, the results of energy-saving tests using the fixing unit 40 having the same configuration as that of the fixing unit 40 of the above embodiment will be described. FIG. 6 is a table showing the test conditions and results. In the embodiment, the first and second ribs 431b and 432b are provided in the first and second casing portions 431 and 432, respectively, whereas in the comparative example 1, the first and second ribs 431b and 432b are provided. Is not provided. In Comparative Example 2, the first and second ribs 431 b and 432 b and the first and second closing members 44 and 45 are not provided.

  Compared with Example 1 and Comparative Example 1, Example 1 requires less power to maintain the required fixing temperature than Comparative Example 1 (a 4.6% decrease over Comparative Example 2). I understand that. This is considered to be because in Example 1, by providing the first and second ribs 431b and 432b, the air flow toward the recording paper excess area was blocked, and an unnecessary decrease in the fixing temperature was suppressed. .

<< Other embodiments >>
In the embodiment, a heating unit (halogen lamp in the embodiment) for heating the fixing roller 41 is provided inside the fixing roller 41. However, the invention is not limited to this, and the heating unit is fixed. You may make it provide in the outer side of the roller 41. FIG. Further, the heating means is not limited to the halogen lamp, and may be, for example, induction heating means having an exciting coil and a core.

  As described above, the present invention is useful for a fixing device and an image forming apparatus including the fixing device.

1 Laser printer (image forming device)
40 Fixing part (fixing device)
41 Fixing roller 42 Pressure roller 43 Housing 431 First housing portion 431a First opening
431b First rib 431c Notch 432 Second housing part 432a Second opening 432b Second rib 432c Notch 431b Second opening 44 First closing member 441 First fixed closing part 442 First variable closing part 45 Second closing member 451 Second fixed blocking part 452 Second variable blocking part

Claims (4)

A rotatable fixing member heated by a heating unit, a pressure member that is pressed against the fixing member and sandwiches and conveys recording paper between the fixing member, and the fixing member is housed in the pressure member. A first housing part formed with an opening that opens to a member side; a second housing part that houses the pressure member therein and has an opening that opens to the fixing member side; A first closing member that closes a portion of the opening of one housing portion that occupies the downstream side in the recording paper conveyance direction from the fixing member, and the pressure member of the opening of the second housing portion A second closing member that closes a portion occupying the downstream side in the recording paper transport direction, and a fixing device comprising:
The first closing member includes at least a first fixed blocking portion provided in a position range corresponding to a recording paper passage area having a width size smaller than a predetermined size, and a recording paper conveyance direction in the first fixed blocking portion. A pair of first variable closing portions provided adjacent to both ends of the orthogonal recording paper width direction and configured to be switchable between a closed state and an open state;
The second closing member includes at least a second fixed closing portion provided in a position range corresponding to a passage region of the recording paper having a width size smaller than the predetermined size, and a recording paper width direction in the second fixed closing portion. A pair of second variable blocking portions provided adjacent to both ends and configured to be switchable between a closed state and an open state;
First ribs perpendicular to the recording paper width direction are formed inside the recording paper width direction inside the pair of first variable closing portions in the first casing portion, respectively.
A fixing device in which a second rib perpendicular to the recording paper width direction is formed on the inner side in the recording paper width direction than the pair of second variable closing portions in the second casing. The fixing device according to claim 1.
The fixing member is a cylindrical fixing roller extending in the recording paper width direction,
The pressure member is a cylindrical pressure roller extending in the recording paper width direction,
The first rib has a shape in which a portion corresponding to the fixing roller of a plate-like portion arranged perpendicular to the recording paper width direction is cut out,
The second rib has a shape in which a portion corresponding to the pressure roller of a plate-like portion arranged perpendicular to the recording paper width direction is cut out. The fixing device according to claim 1 or 2,
The pair of first ribs are formed at positions corresponding to both side edges in the width direction of the recording sheet having the predetermined size, and the pair of second ribs are similarly recorded with the width size of the predetermined size. A fixing device formed at positions corresponding to both side edges in the width direction of the paper. An image forming apparatus comprising the fixing device according to claim 1.

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