JP4946392B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which uniformly cools paper after fixing by a minimum number of fans and correcting or dissolving curling of the paper after fixing. <P>SOLUTION: The image forming apparatus equipped with the fans 71 for blowing air to the paper and cooling it after passing through a fixing apparatus 37, is characterized in that the fans 71 are fitted to a blowing duct 70, and that the blowing duct 70 has: a blowing opening part 72 opposing a paper conveying path 44 so as to blow the air blown from the fans 71 onto the paper; a first guiding wall part 74 to which the air blown from the fans 71 collides and which refracts its flow direction to guide it to the blowing opening part 72; and a second guiding wall part 76 to which the air flowing along the first guiding wall part 74 collides and which refracts its flow direction to guide it to the blowing opening part 72. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus such as, for example, a copying machine, a printer, a facsimile, or a complex machine of these.

  Conventionally, for example, in Patent Document 1 below, immediately after a sheet passes through a nip portion of a roller-pair type fixing device, air is blown onto a toner image fixing surface of the sheet by a cooling fan to cool the sheet and the fixed toner image. Thus, there is disclosed a fixing device that prevents the toner on the lower surface of the paper from adhering to the back surface of the paper that is sequentially stacked and accommodated on the paper discharge tray.

  In general, it is known that paper that has passed through a fixing device that melts and fixes a toner image adhering to the paper by heat and pressure is likely to curl due to factors such as water content of the paper and fixing temperature. ing.

Japanese Patent Laid-Open No. 5-150677

  As described above, when cooling is performed by blowing air onto a sheet after fixing with a fan, it is preferable that the blown air is uniformly blown over the entire surface of the sheet to be cooled uniformly. For this purpose, the width of the air flow to be blown needs to be formed wider than the width in the longitudinal direction of the paper to be used. This can be realized by using a plurality of fans or line flow fans. However, if a plurality of fans are provided or a line flow fan is used, the cost increases. It is therefore desirable to be able to achieve the objective with a minimum number (preferably one) of fans.

  Further, as in the fixing device disclosed in Patent Document 1, if the paper is cooled immediately after passing through the fixing device, the curl state generated on the paper is fixed. If a large number of papers curled in this way are continuously discharged onto the paper discharge tray, the papers cannot be stacked in a well-aligned state and the stacking capacity deteriorates, or the curled state When the value is large, there is a possibility that the sheets are curled up and not stacked in the discharge order but scattered on the discharge tray.

  Therefore, in order to solve the above-described problems, the present invention can uniformly cool the paper after fixing with a minimum number of fans, and can correct or eliminate the curling of the paper after fixing. It is an object to provide a forming apparatus.

In order to solve the above-described problem, a first invention of the present application is a first transport unit that transports a sheet immediately after passing through a fixing device, and a sheet transport path that extends from the first transport unit along a sheet transport direction. A second transport unit provided in the paper transport path for transporting the paper downstream of the first transport unit in the paper transport direction, the first transport unit, and the second transport unit An image forming apparatus comprising: a fan for blowing the sheet air to a sheet conveyed along the sheet conveyance path between
The fan is attached to a blowing duct, and the blowing duct has a blowing opening facing the paper conveyance path so as to blow the air blown from the fan onto the paper, and the air blown from the fan. The first guide wall part that refracts and refracts the flow direction and leads to the blowing opening side, and the air that flows along the first guide wall part collides and further refracts the flow direction and the blowing opening. It has the 2nd guide wall part led to a part, It is characterized by the above-mentioned.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the sheet conveyance path between the first conveyance unit and the second conveyance unit passes through the fixing device. It is formed by a curved guide member that is curved in a direction opposite to the curling direction of the generated paper, and the blowing opening is opposed so that the air blown from the blowing opening hits the paper against the curved guide member. It is characterized by being.

  According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the air blown from the blowing opening extends to the blowing opening so as to flow toward the second transport unit after colliding with a sheet. The second guide wall is oriented.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, a sheet reversing path is branched from the sheet conveying path between the first conveying unit and the second conveying unit. A switching guide capable of rotating in a predetermined angle range is disposed at the branch position, and a third transport unit that switches back the paper introduced from the paper transport path to the paper reversing path by the switching guide is the paper reversing path. The spray opening is arranged to face the switching guide member configured to allow an air flow to pass therethrough.

  According to a fifth aspect of the present invention, in the fourth aspect, when the switching guide member is rotated so as to introduce a sheet into the sheet reversing path, the sheet reversing path passes through the fixing device. The sheet reversing path is formed by the switching guide member and the reversing path guide member so as to bend in the direction opposite to the curl direction of the sheet generated by the air, and air blown from the spray opening is introduced into the sheet reversing path. The spray openings are opposed to each other so as to collide the printed sheet in a direction in which the sheet is pressed against the switching guide member and the reverse path guide member.

  The sixth invention of the present application is the image forming apparatus according to the fifth invention, wherein the air blown from the blowing opening extends to the blowing opening so as to flow to the third transporting part side after hitting a sheet. The second guide wall is oriented.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the fourth aspect, the switching guide member includes an air passage space so that the air blown from the blowing opening reaches the paper conveyance path. It is characterized by being.

  The eighth invention of the present application is characterized in that the switching guide member is formed in a comb-like shape.

  In the present invention (especially the first invention), the air flow is refracted twice by hitting the air flow blown from the fan against the first guide wall portion and the second guide wall portion, respectively. The air flow collides with the wall portion and becomes an expanded air flow in the blowing duct, and is blown out from the blowing opening portion to the paper conveyance path as a wide air flow. As a result, the toner-fixed sheet conveyed through the sheet conveyance path can be uniformly cooled by the air uniformly blown over the entire sheet. Therefore, according to the present invention, a minimum number of fans (for example, one) are used to cool the toner-fixed paper before discharging in order to prevent toner adhesion between the paper continuously discharged onto the paper discharge tray. The paper can be uniformly cooled, the cost can be suppressed, and the fan noise and power consumption are also advantageous.

  Further, according to the invention of the present application (particularly, the second invention), the curved guide member curved in the direction opposite to the curl direction of the paper is bent by blowing air in the direction of pressing the paper on which the toner image has been fixed. The curl state is corrected or eliminated in the process of being conveyed while being in contact with the guide member, and is cooled and fixed in a state where the curl state is corrected or eliminated. As a result, even when the paper that has passed through the fixing device is curled due to a change in environmental conditions or the like, it is possible to maintain or improve the paper alignment performance and stacking performance on the paper discharge tray.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 schematically shows the overall configuration of an image forming apparatus 10 according to the first embodiment of the present invention. The image forming apparatus 10 includes an intermediate transfer belt 12 in the approximate center inside the apparatus. The intermediate transfer belt 12 in the form of an endless sheet is supported around each of the four rotatable rollers disposed on the inner side, and for example, the roller 14 is rotationally driven by a motor (not shown). As a result, it rotates in the direction of arrow A.

  Below the lower portion of the intermediate transfer belt 12 that extends in the horizontal direction, yellow (Y), magenta (M), cyan (C), and black (K) toners are sequentially arranged from the upstream side in the rotation direction of the intermediate transfer belt 21. The four imaging units 22Y, 22M, 22C, and 22K respectively corresponding to are arranged side by side in the horizontal direction. The black imaging unit 22K is configured to be larger than the other imaging units 22Y, 22M, and 22C in order to provide high durability performance with respect to frequent monochrome printing. An exposure device 23 is disposed below each of the imaging units 22Y, 22M, 22C, and 22K.

  The imaging units 22Y, 22M, 22C, and 22K are respectively a drum-shaped photoreceptor 24, a charger 26 that uniformly charges the surface of the photoreceptor 24, and the surface of the uniformly charged photoreceptor 24 from the exposure device 23. A developing device 28 that develops an electrostatic latent image formed by irradiation of lasers L (Y), L (M), L (C), and L (K) with toner to form a toner image. Yes. The photosensitive members 24 of the imaging units 22Y, 22M, 22C, and 22K are in contact with the intermediate transfer belt 24, respectively. Corresponding to each of the imaging units 22Y, 22M, 22C, and 22K, four primary transfer rollers 30 are rotatably provided so as to sandwich the intermediate transfer belt 12 with the photoreceptor 24.

  Above the intermediate transfer belt 12, four toner bottles 32 respectively corresponding to the four color toners are arranged side by side. The toners of the respective colors are supplied from the toner bottles 32 to the developing units 28 of the corresponding imaging units 22Y, 22M, 22C, and 22K through supply paths (not shown) according to the remaining amount of toner in the developing unit 28. It has become.

  A secondary transfer roller 34 is pressed against a portion of the intermediate transfer belt 12 supported by the roller 14, and a contact portion between the intermediate transfer belt 12 and the secondary transfer roller 34 becomes a secondary transfer nip portion 36. ing. Above the secondary transfer roller 34, a roller pair type fixing device 37 including a fixing roller 37a heated to a temperature equal to or higher than the melting temperature of the toner and a pressure roller 37b pressed against the fixing roller 37a is disposed. A contact portion between the fixing roller 37a and the pressure roller 37b is a fixing nip portion.

  The heating method of the fixing roller 37a may be a heater heating type or an induction heating type. Further, for example, a belt-type fixing device other than the roller pair type may be used.

  A cleaning device 38 is disposed in contact with the portion of the intermediate transfer belt supported by the roller 16 so that the toner remaining on the intermediate transfer belt 12 after the secondary transfer of the toner image is collected. Yes.

  A paper feeding unit 40 is provided at the lower part of the image forming apparatus 10. The sheets (not shown) stacked and accommodated in the sheet feeding unit 40 are sent out from the sheet feeding unit 40 one by one from the uppermost one by the rotation of the sheet feeding roller 42.

  From the paper supply unit 40, a paper transport path 44 extends upward. The sheet conveyance path 44 is arranged in order along the sheet conveyance direction, with each nip portion of the conveyance roller pairs 46 and 48, the nip portion between the timing roller pair 50, the secondary transfer nip portion 36, and the fixing nip portion of the fixing device 37. Is going through.

  Further, the sheet conveyance path 44 is formed on the sheet discharge tray 11 provided on the upper surface of the image forming apparatus 10 from the nip portion of the conveyance roller pair (first conveyance unit) 52 that conveys the sheet immediately after passing through the fixing device 37. Are connected to a pair of paper discharge rollers (second transport unit) 54 for discharging the paper. One of the guide members on both sides of the paper transport path 44 between the transport roller 52 and the paper discharge roller 54 is a curved guide member that curves in a direction opposite to the curl direction of the paper generated by passing through the fixing device 37. 45.

  Here, the curl direction of the sheet is assumed to be a curl direction in which the sheet is curved so that when the sheet passes through the fixing device 37, the sheet is convex toward the fixing roller 37a and concave toward the pressure roller 37b. In the present embodiment, the paper discharge roller pair 54 is the second transport unit of the present invention. However, the second transport unit may be another transport means (roller pair or belt) other than the paper discharge roller pair. .

  A paper reversing path 60 branches from the paper transport path 44 above the transport roller pair 52. The sheet reversing path 60 extends downward from the branch position, and joins the sheet conveying path 44 below the timing roller pair 50 via the nip portions of the conveying roller pairs 62, 64, 66, and 68. Yes. The paper reversing path 60 is used for duplex printing. That is, the sheet with the toner image fixed on the surface is switched back by the paper discharge roller pair 54 being driven to reversely rotate after a part of the sheet is sent out of the image forming apparatus, and is introduced into the sheet reversing path 60. The Thereafter, the sheet is conveyed downward along the sheet reversing path 60 by the conveying roller pairs 62, 64, 66, and 68, and is again sent to the secondary transfer nip portion 36 via the sheet conveying path 44 and the timing roller pair 50, As a result, the toner image is transferred to the back side of the sheet.

  The guides (including the curved guide member 45) on both sides forming the paper transport path 44 and the paper reversing path 60 may be configured in any way as long as they function to guide the transported paper. It is composed of a single plate made of resin or resin, or a plurality of rod-like members or strip-like members made of, for example, metal or resin that are arranged parallel to each other at an interval and are elongated along the paper conveyance direction. Also good.

  On the sheet conveyance path 44 between the conveyance roller pair 52 and the paper discharge roller pair 54, for example, a blowing duct 70 having one fan 71 attached to the upper surface is disposed. When the fan 70 is driven, air taken into the apparatus from the suction port 78 is blown into the blowing duct 70. The blowing duct 70 extends in the depth direction (perpendicular to the plane of FIG. 1), and has a duct shape that is closed by each wall portion except for the mounting portion of the fan 71 and the blowing opening 74 described later. Yes.

  The blowing duct 70 has a blowing opening 72 for blowing the air blown from the fan 71 onto the paper in the paper transport path 44 between the transport roller pair 52 and the paper discharge roller pair 54. The spray opening 72 is opposed to the curved guide member 44 that forms the paper transport path 44 at a position closer to the paper discharge roller pair 54 than the transport roller pair 52. The spray opening 72 has a length in the depth direction that is equal to or greater than the sheet width in the direction orthogonal to the sheet conveyance direction.

  The blowing duct further includes a first guide wall portion 74 that is guided by the air blown out from the fan 71 and refracts the flow direction to the blowing opening 72 side, and the air that flows along the first guide wall portion 74. And a second guiding wall portion 76 that refracts the flow direction further and leads to the blowing opening 72. The second guide wall portion 76 having the lower end edge forming the blowing opening 72 flows to the discharge roller pair 54 side after the air blown from the blowing opening 72 to the paper transport path 44 hits the paper. Is oriented. Specifically, the second guide wall portion 76 is lowered to the left along the direction substantially toward the paper discharge roller pair 54 so that air is blown from the blowing opening 72 to the sheet at an angle of, for example, 45 degrees. Inclined.

Next, an image forming operation of the image forming apparatus 10 having the above configuration will be described.
For example, when a print signal and image data are received from an external device such as a personal computer, an image forming operation is started. In the case of a color image, the image data is divided into data for each color by a control unit (not shown) and then input to the exposure device 23.

  In each of the imaging units 22Y, 22M, 22C, and 22K, the surface of the photosensitive member 24 that is rotationally driven in the clockwise direction in FIG. 1 is uniformly charged by the charger 26, and then the exposure device 23 responds to each color image data. An electrostatic latent image is formed by exposure to lasers L (Y), L (M), L (C), and L (K). Thereafter, the electrostatic latent image is developed by the developing device 28 to become a toner image. The toner images formed on the photosensitive member 24 in each of the imaging units 22Y, 22M, 22C, and 22K are sequentially transferred onto the intermediate transfer belt 12 by the electrostatic adsorption action of the primary transfer roller 30 to which the primary transfer bias is applied. Primary transfer is performed in the superimposed state.

  When the image data is a monochrome image, only the black imaging unit 22K operates to form a toner image, which is primarily transferred onto the intermediate transfer belt 12.

  The sheet fed from the sheet feeding unit 40 to the sheet conveyance path 44 by the sheet feeding roller 42 is in a standby state with its leading end nipped by the timing roller pair 50, and transferred 4 onto the intermediate transfer belt 12. The color toner image is introduced into the secondary transfer unit 36 by the timing roller pair 50 in synchronization with the arrival of the color toner image at the secondary transfer unit 36 according to the rotation of the intermediate transfer belt 12. At this time, since the secondary transfer bias is applied to the secondary transfer roller 34, the four-color toner images on the intermediate transfer belt 12 are secondarily transferred collectively onto the sheet by the electrostatic adsorption action.

  When the sheet on which the toner image has been transferred passes through the fixing nip portion of the fixing device 37, the toner image is melted and fixed by the action of heat and pressure. At this time, the paper that has passed through the fixing device 37 is curled with a convex shape on the fixing roller 37a side and a concave shape on the pressure roller 37b side. Thereafter, the paper is transported through the paper transport path 44 by the transport roller pair 52 and the paper discharge roller pair 54 and is discharged onto the paper discharge tray 11.

  In the process in which the paper that has passed through the fixing device 37 is transported through the paper transport path 44 between the transport roller pair 52 and the paper discharge roller pair 54, the air blown from the spray opening 72 by the operation of the fan 71 is Sprayed on top. As a result, the sheet is conveyed along the sheet conveyance path 44 while being pressed against the curved guide member 45. Further, the air blown from the blowing opening 72 and collided with the upper surface of the paper flows toward the paper discharge roller 54 and does not flow in the direction of the conveying roller pair 52.

  As described above, in the image forming apparatus 10 of the present embodiment, the air flow blown from the fan 71 into the blowing duct 70 strikes the first guide wall portion 74 and the second guide wall portion 76, respectively, and is refracted twice. As a result, the air flow collides with each of the guide wall portions 74 and 76 and becomes an air flow expanded in the blowing duct 70 and is blown out from the blowing opening 72 to the paper conveying path 44 as a wide air flow. Is done. As a result, the toner-fixed sheet conveyed through the sheet conveyance path 44 can be uniformly cooled by the air blown uniformly over the entire sheet. Therefore, according to the image forming apparatus 10 of the present exemplary embodiment, a minimum number (when the toner-fixed paper is cooled before discharge in order to prevent toner adhesion between the paper continuously discharged onto the paper discharge tray 11 ( For example, one or two fans 71 can uniformly cool the sheet, and the cost can be reduced, and the fan noise and power consumption are also advantageous.

  In addition, air is blown in a direction in which the toner image-fixed paper is pressed against the curved guide member 45 curved in the direction opposite to the curl direction of the paper, so that the paper is conveyed while being in contact with the curved guide member 45. Then, the curl is corrected or eliminated, and is cooled and fixed in a state where the curl is corrected or eliminated. As a result, even if the paper that has passed through the fixing device 37 is curled due to a change in environmental conditions or the like, it is possible to maintain or improve the paper alignment performance and stacking performance on the paper discharge tray 11.

  Further, since the air blown from the blowing opening 72 and collided with the upper surface of the paper flows to the paper discharge roller 54 side, the conveying roller pair 52 is not cooled by this air flow. The reason for this is that when the conveyance roller pair 52 is cooled and the temperature is lowered, the curled paper immediately after passing through the fixing device 37 is cooled by the conveyance roller pair 52 to fix the curl. This is because the curl correcting effect by the curved guide member 45 is reduced.

  Next, an image forming apparatus 10a according to a second embodiment of the present invention will be described with reference to FIGS. 2 to 4. The same components as those of the image forming apparatus 10 according to the first embodiment are denoted by the same reference numerals and described above. Here, differences from the image forming apparatus 10 will be mainly described.

  In the image forming apparatus 10a of the present embodiment, the paper transport path 44 is branched above the transport roller pair 52, and a switchback roller pair disposed near the upper portion of the paper discharge roller pair 54 as the branch path. A sheet reversing path 60 leading to the (third transport unit) 82 is formed. A switching guide member 86 is provided at a branch position between the paper transport path 44 and the paper reversing path 60 so as to be rotatable within a predetermined angle range about the support shaft 88. When the switching guide member 86 is in the state shown in FIG. 2, the sheet conveyed upward along the sheet conveying path 44 is guided by the lower surface 86 a of the switching guide member 86 and guided to the paper discharge roller pair 54. It will be.

  On the other hand, when the switching guide member 86 is rotated downward by a predetermined angle from the state shown in FIG. 2 to the state shown in FIG. 3, the sheet conveyed upward in the sheet conveying path 44 is the upper surface 86 b of the switching guide member 86. Are guided to the sheet reversing path 60 and the switchback roller pair 82. In this case, the upper surface 86b of the switching guide member 86 and the reverse path guide 83 perform the same function as the curved guide member 45 in the paper transport path 44.

  In addition, when the paper is switched back by the switchback roller pair 82, a part including the front end portion in the paper transport direction is sent out of the apparatus, and a support tray for supporting a part of the paper from below. 84 may be provided.

  The sheet reversing path 60 is joined from the switchback roller pair 57 to the sheet conveying path 44 below the timing roller pair 50 via the nip portions of the conveying roller pairs 62, 64, 66, and 68.

  The blowing opening 72 of the blowing duct 70 is provided to face the switching guide member 86. The switching guide 88 is configured to include a space through which air can pass so that the air flow blown from the blowing opening 72 reaches the paper transport path 44. Specifically, as shown in FIG. 4, for example, a guide plate 87 having a curved surface at the upper end edge 86a and a linear surface at the lower end edge is arranged at an appropriate interval and configured in a comb shape. As a result, the air flow can pass through the space between the rear end portions of the guide plates 87 (corresponding to the portion indicated by the arrow 86 in FIG. 4). Note that an air-passable space may be secured in the switching guide member 86 by forming a notch or a through hole extending between the adjacent guide plates 87 in the vertical direction.

  Also in the image forming apparatus 10a of the present embodiment, the airflow blown from the blowing opening 72 against the paper introduced into the paper reversing path 60 by the switching guide member 86 during double-sided printing is switched back. It flows to the roller pair 82 side.

  Also in the image forming apparatus 10 of the present embodiment, the same operational effects as the image forming apparatus 10 can be obtained.

  That is, the air flow blown into the blowing duct 70 from the fan 71 is refracted twice by hitting each of the first guide wall portion 74 and the second guide wall portion 76, so that the air flow is refracted by each guide wall portion. The air flow is blown to the paper reversing path 83 and the paper transporting path 44 from the blowing opening 72 as a wide air flow by colliding with 74 and 76 and expanding in the blowing duct 70. As a result, the toner-fixed sheet conveyed through the sheet reversing path 83 or the sheet conveying path 44 can be uniformly cooled by the air blown uniformly over the entire sheet. Therefore, according to the image forming apparatus 10a of the present embodiment, a minimum number (when the toner-fixed sheets are cooled before discharging in order to prevent toner adhesion between sheets continuously discharged onto the discharge tray 11 ( For example, one or two fans 71 can uniformly cool the sheet, and the cost can be reduced, and the fan noise and power consumption are also advantageous.

  Also, air is blown in the direction in which the toner image fixed paper is pressed against the curved guide member 45 curved in the direction opposite to the curl direction of the paper, or the upper surface of the switching guide member 86 and the reverse path guide 83. In the process of being conveyed while being in contact with the curved guide member 45 or the like, the curl of the paper is corrected or eliminated, and the paper is cooled and fixed in a state where the curl is corrected or eliminated. As a result, even if the paper that has passed through the fixing device 37 is curled due to a change in environmental conditions or the like, it is possible to maintain or improve the paper alignment performance and stacking performance on the paper discharge tray 11.

  Further, since the air blown from the blowing opening 72 and collided with the upper surface of the sheet flows to the switchback roller pair 82 and the discharge roller 54 side, the conveying roller pair 52 is cooled by this air flow. There is no. The reason for this is that when the conveyance roller pair 52 is cooled and the temperature is lowered, the curled paper immediately after passing through the fixing device 37 is cooled by the conveyance roller pair 52 to fix the curl. This is because the curl correcting effect by the curved guide member 45 is reduced.

  The present invention is not limited to a tandem type color image forming apparatus, and may be applied to other types (for example, a 4-cycle type) image forming apparatus.

1 is an overall configuration diagram of an image forming apparatus according to a first embodiment. FIG. 9 is an overall configuration diagram of an image forming apparatus according to a second embodiment. The figure which shows the state which rotated the switching guide member of FIG. 2 below. The whole perspective view of a switching guide member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10a ... Image forming device 37 ... Fixing device 44 ... Paper conveyance path 45 ... Curve guide member 52 ... Conveying roller pair (1st conveyance part)
54: Paper discharge roller pair (second transport section)
60 ... Paper reversing path 70 ... Blowing duct 71 ... Fan 72 ... Blowing opening 74 ... First guide wall 76 ... Second guide wall 82 ... Switchback roller pair (third transport unit)
86 ... Switching guide member

Claims (8)

A first conveyance unit that conveys a sheet immediately after passing through the fixing device; a sheet conveyance path that extends from the first conveyance unit along the sheet conveyance direction; and a downstream of the first conveyance unit in the sheet conveyance direction. A second transport section provided in the paper transport path for transporting the paper on the side, and the paper transported on the paper transport path between the first transport section and the second transport section An image forming apparatus comprising a fan for blowing the paper air,
The fan is attached to a blowing duct, and the blowing duct has a blowing opening facing the paper conveyance path so as to blow the air blown from the fan onto the paper, and the air blown from the fan. The first guide wall part that refracts and refracts the flow direction and leads to the blowing opening side, and the air that flows along the first guide wall part collides and further refracts the flow direction and the blowing opening. An image forming apparatus comprising: a second guide wall portion that leads to the portion.   The paper transport path between the first transport unit and the second transport unit is formed by a curved guide member that is curved in a direction opposite to the curl direction of the paper generated by passing through the fixing device. The image forming apparatus according to claim 1, wherein the blowing opening is opposed so that air blown from the opening collides in a direction in which the sheet is pressed against the curved guide member.   3. The second guide wall portion extending to the blowing opening is oriented so that the air blown from the blowing opening collides with a sheet and then flows toward the second conveying portion. The image forming apparatus described in 1.   A sheet reversing path is branched from the sheet transport path between the first transport section and the second transport section, and a switching guide that is rotatable within a predetermined angle range is disposed at the branch position, A third transport unit for switching back the paper introduced from the paper transport path to the paper reversing path by the switching guide is provided in the paper reversing path, and the spray opening is configured to allow airflow to pass therethrough. The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed to face the switching guide member.   When the switching guide member is rotated so as to introduce the paper into the paper reversing path, the paper reversing path is curved in a direction opposite to the curl direction of the paper generated by passing through the fixing device. The sheet reversing path is formed by the switching guide member and the reversing path guide member, and the sheet into which the air blown from the spray opening is introduced into the sheet reversing path is used as the switching guide member and the reversing path guide member. The image forming apparatus according to claim 4, wherein the blowing openings face each other so as to collide with a pressing direction.   6. The second guide wall portion extending to the blowing opening is oriented so that the air blown out from the blowing opening collides with a sheet and flows to the third conveying portion side. The image forming apparatus described.   The image forming apparatus according to claim 4, wherein the switching guide member includes an air passage space so that the air blown from the blowing opening reaches the sheet conveyance path.   The image forming apparatus according to claim 7, wherein the switching guide member is configured in a comb shape.

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