JP2020038352A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can reduce a situation where a sheet is attached to a reversal guide to reduce conveyance failure.SOLUTION: An image forming apparatus comprises: a reversal roller pair 230 that conveys a sheet having a toner image fixed thereto in a first direction A, and subsequently performs a reversal conveying operation of conveying the sheet in a second direction B opposite to the first direction A; a reversal guide 190 that guides the sheet in the reversal conveying operation; a conveyance guide pair 210 that forms a double-side conveyance path 202 through which the sheet to which the reversal conveying operation is performed passes, and guides the sheet conveyed through the double-side conveyance path 202; a fan 232 that blows air toward the double-side conveyance path 202; and a ventilation unit 235 through which the air blown from the fan 232 and directed toward the reversal guide 190 passes. The air passing through the ventilation unit 235 flows along the reversal guide 190.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus that forms a toner image on a sheet.

  2. Description of the Related Art Conventionally, an image forming apparatus that transfers a toner image to a sheet in an image transfer unit and fixes the toner image to the sheet in a fixing unit is known (see Patent Document 1). When an image is formed on both sides of a sheet, the image forming apparatus guides a sheet having a toner image formed on the first surface to a retreat conveyance path, and the sheet is switch-back conveyed on the retreat conveyance path. Then, the sheet is guided again to the image transfer unit, and a toner image is formed on the second surface in the image transfer unit.

JP 2015-25911 A

  However, in the image forming apparatus described in Patent Literature 1, the surface of the sheet conveyed along the evacuation conveyance path on which the toner image is formed is in sliding contact with the evacuation conveyance path. At this time, the sheet may stick to the evacuation conveyance path, causing the sheet to buckle, which may cause a conveyance failure such as a jam.

  Therefore, an object of the present invention is to provide an image forming apparatus which reduces the sticking of a sheet to a reversing guide and solves the above-mentioned problem.

  The present invention provides, in an image forming apparatus, a transfer unit that transfers a toner image to a sheet, a fixing unit that fixes the toner image transferred by the transfer unit to the sheet, and a sheet that fixes the toner image in a first direction. After the sheet is conveyed to the second direction, a reverse conveying section that performs a reverse conveying operation for conveying the sheet in the second direction opposite to the first direction, a reverse guide that guides the sheet during the reverse conveying operation, and the reverse conveying operation are performed. Forming a conveying path through which the sheet passes, and a pair of conveying guides for guiding the sheet conveyed through the conveying path toward the transfer section; a blowing section for blowing air toward the conveying path; And a ventilation section through which the wind directed to the reversing guide passes. The wind passing through the ventilation section flows along the reversing guide.

  ADVANTAGE OF THE INVENTION According to this invention, sticking of a sheet to a reversing guide can be reduced, and conveyance failure can be reduced.

FIG. 1 is an overall schematic diagram illustrating a printer according to a first embodiment. The schematic diagram which shows a reversing unit. FIG. 2A is a diagram illustrating a sheet conveyed in a first direction, and FIG. 2B is a diagram illustrating a sheet conveyed in a second direction. (A) is a figure which shows the mode that the wind sent from the fan was interrupted by the preceding sheet, (b) is a figure which shows the mode that the wind sent from the fan is not interrupted by the sheet. FIG. 3 is a schematic view showing a step formed on a reversing guide. The figure which shows the reversing unit which concerns on 2nd Embodiment. FIG. 10 is a control block diagram according to a second embodiment. 5 is a flowchart illustrating processing by a control unit. FIG. 3 is a side view showing the configuration of the duct. FIG. 2 is a perspective view showing a configuration of a duct.

<First embodiment>
〔overall structure〕
First, a first embodiment will be described. The printer 100 as an image forming apparatus is an electrophotographic full-color laser beam printer. The printer 100 can use various sheets from widely used plain paper, paper called recycled paper to glossy paper, coated paper, and thin paper to thick paper. As shown in FIG. 1, the printer 100 includes a feeding unit 103, an image forming unit 104, a fixing unit 160, a discharge roller pair 167, and an operation unit 180. The operation unit 180 has a plurality of physical keys and a liquid crystal panel, and can set the basis weight and the size of the sheet P to be used.

  The image forming unit 104 includes four process units 120, 121, 122, and 123 for forming four color toner images of yellow (Y), magenta (M), cyan (C), and black (Bk), and an intermediate transfer unit. 105. The four process units 120, 121, 122, and 123 have the same configuration except that the colors of the images to be formed are different. Therefore, only the configuration of the process unit 120 and the image forming process will be described, and the description of the process units 121, 122, and 123 will be omitted.

  The process unit 120 includes a photoconductor 106 that carries a toner image, a charger 111, a developing unit 112, a cleaning unit 107, a semiconductor laser 108, and a polygon mirror 109. The intermediate transfer unit 105 is disposed in an intermediate transfer belt 152 and an internal space surrounded by the intermediate transfer belt 152, and primary transfer rollers 130, 131, and 132 facing the respective photoconductors of the process units 120, 121, 122, and 123. , 133. The intermediate transfer belt 152 is rotated by the driving roller 150. Further, the intermediate transfer unit 105 has a secondary transfer roller 151 and a facing roller 153, and the secondary transfer roller 151 and the facing roller 153 form a secondary transfer portion T2 as a transfer portion.

  The fixing unit 160 as a fixing unit has a heating roller 161 and a pressure roller 162 for applying predetermined heat and pressure to the sheet. The feeding unit 103 includes a cassette 110 that stores the sheets P, and a feeding belt 155 that feeds the sheets P stored in the cassette 110.

  Next, an image forming operation of the printer 100 configured as described above will be described. When an image signal is input to the semiconductor laser 108 from a personal computer (not shown) or the like, a laser beam corresponding to the image signal is emitted from the semiconductor laser 108 onto the photoconductor 106 of the process unit 120.

  At this time, the surface of the photoconductor 106 is uniformly charged to a predetermined polarity and potential by a charger 111 in advance, and the surface of the photoconductor 106 is electrostatically charged by irradiating a laser beam from a semiconductor laser 108 through a polygon mirror 109. A latent image is formed. The electrostatic latent image formed on the photoconductor 106 is developed by the developing device 112, and a yellow (Y) toner image is formed on the photoconductor 106. Similarly, each of the photoconductors of the process units 121, 122, and 123 is irradiated with laser light from a semiconductor laser, and magenta (M), cyan (C), and black (Bk) toner images are formed on the respective photoconductors. You.

  These toner images are sequentially multiplex-transferred onto the intermediate transfer belt 152 by applying a positive transfer bias voltage to the primary transfer rollers 130, 131, 132, and 133, and full-color is transferred onto the intermediate transfer belt 152. A toner image is formed.

  In parallel with this image forming process, the sheet P stored in the cassette 110 is fed by the feed belt 155 of the feed unit 103. The sheet P is transported toward the secondary transfer portion T2 by a plurality of transport roller pairs. When a positive transfer bias voltage is applied to the secondary transfer roller 151, the toner image carried on the intermediate transfer belt 152 is secondarily transferred to the sheet P in the secondary transfer portion T2. Thus, a full-color toner image is formed on the surface of the sheet P.

  The fixing unit 160 applies predetermined heat and pressure to the sheet P to which the toner image has been transferred, and the toner image is fixed to the sheet P. The sheet P on which the toner image has been fixed passes through a discharge conveyance path 165 and is discharged outside the apparatus by a discharge roller pair 167.

  When images are formed on both sides of the sheet P, the sheet P is guided to the reverse conveyance path 201 after passing through the fixing unit 160. Then, the sheet P is reversely conveyed in the reversing unit 200 and is guided again to the secondary transfer portion T2 by the double-sided conveying path 202. The toner image is formed on the back surface of the sheet P at the secondary transfer portion T2, and the sheet P is discharged outside the apparatus by the discharge roller pair 167. The sheet P discharged out of the apparatus by the discharge roller pair 167 may be received by a sheet processing device (not shown) connected to the printer 100, or may be stacked on a discharge tray (not shown) provided in the printer 100. May be done.

[Reversing unit]
Next, the reversing unit 200 will be described. As shown in FIG. 2, the reversing unit 200 includes a reversing conveyance path 201, a guide member 231, a pair of reversing rollers 230, a reversing guide 190, and a blowing unit 195. The guide member 231 is provided at a branch portion between the reversing conveyance path 201 and the two-sided conveyance path 202, and can switch the conveyance destination of the sheet P conveyed by the reversing roller pair 230 by rotating.

  The reversing roller pair 230 as a reversing conveyance unit is configured to be rotatable in normal and reverse directions, and conveys the sheet P in the first direction A, and then conveys the sheet P in the second direction B opposite to the first direction A. Actions can be taken.

  A reversing guide 190 is arranged downstream of the pair of reversing rollers 230 in the first direction A, and the reversing guide 190 can guide the sheet P during the reversing conveyance operation. At this time, the reversing guide 190 is in sliding contact with a surface of the sheet P on which the toner image has been transferred by the secondary transfer portion T2 (hereinafter, referred to as a transfer surface).

  That is, as shown in FIG. 3A, the sheet P conveyed in the first direction A by the pair of reversing rollers 230 is guided while sliding on the reversing guide 190. When the rear end of the sheet P passes through the guide member 231, the guide member 231 rotates and the pair of reversing rollers 230 reversely rotates. Thus, as shown in FIG. 3B, the sheet P is conveyed in the second direction B, and is guided by the guide member 231 to the double-sided conveyance path 202. The two-sided conveyance path 202 as a conveyance path is formed by a conveyance guide pair 210, and the conveyance guide pair 210 guides the sheet P conveyed on the double-sided conveyance path 202 toward the secondary transfer portion T2. The transport guide pair 210 is formed with a plurality of holes 211 through which air sent from a fan 232 described later can pass.

  The blower unit 195 has a fan 232 as a blower and a duct 233, as shown in FIGS. 2 to 3B, and sends air to the duct 233 by rotation of the fan 232. Can be. The wind sent to the duct 233 is sent from the ventilation part 235 of the duct 233 to the double-sided conveyance path 202. The ventilation part 235 is provided at a distance of 3 mm to 6 mm with respect to the two-sided conveyance path 202, and minimizes leakage of air from a gap between the duct 233 and the two-sided conveyance path 202.

  FIG. 9 is a side view showing the configuration of the duct 233 in more detail, and FIG. 10 is a perspective view of the duct 233, the double-sided conveyance path 202, and the vicinity thereof as viewed obliquely from below. As shown in FIG. 9, the duct 233 includes an introduction member 710 that guides upward by receiving wind from the fan 232, a first duct member 711 having a vertical wall 234, and a second duct member 714. In.

  The transport guide pair 210 forming the double-sided transport path 202 includes an upper guide 210a and a lower guide 210b. The first duct member 711 is arranged on the opposite side of the lower guide 210b from the upper guide 210a. The first duct member 711 and the lower surface of the lower guide 210b form a flow path through which air flows. The second duct member 714 is arranged on the opposite side of the lower guide 210b from the upper guide 210a. A flow path through which air flows is formed by the second duct member 714 and the lower surface of the lower guide 210b. The duct 233 includes a lower guide 210b and a first duct member 711 and a second duct member 714 as duct members arranged on the opposite side of the lower guide 210b from the upper guide 210a. The lower guide 210b is one transport guide of the transport guide pair 210, and the upper guide 210a is the other transport guide of the transport guide pair 210.

  The wind in the duct 233 flows in the sheet conveyance direction in the double-sided conveyance path 202. A gap 713 is provided between the first duct member 711 and the second duct member 714. More specifically, the gap 713 is formed by the connection surface 711a of the first duct member 711 and the connection surface 714a of the second duct member 714 facing the connection surface 711a. The air in the duct 233 flows out of the duct 233 through the gap 713 as an opening of the duct 233. The air that has passed through the gap 713 flows downward between the end of the reversing guide 190 and the side plate 715a of the stay 715 that supports the fan 232, that is, toward the guide surface of the reversing guide 190. The gap 713 and the space between the reversing guide 190 and the side plate 715a of the stay 715 form a ventilation part 235 through which the wind sent from the fan 232 and directed to the reversing guide 190 passes.

  Since a plurality of holes 211 are formed in the pair of transport guides 210 as shown in FIG. 2, the wind generated by the fan 232 passes through the two-sided transport path 202 and the plurality of holes 211 of the pair of transport guides 210. And sent to the inside of the printer 100. Generally, water vapor is released from the sheet heated in the fixing unit 160 by evaporating water contained in the sheet. This water vapor is cooled in the transport guide pair 210, and dew condensation may occur on the transport guide pair 210. When dew condensation as water droplets adheres to the sheet P, an image defect or a jam due to the sheet P sticking to the transport guide pair 210 may occur.

  However, in the present embodiment, the wind generated by the fan 232 is sent to the inside of the printer 100 through the two-sided conveyance path 202 and the plurality of holes 211 of the conveyance guide pair 210. For this reason, it is possible to reduce the water vapor released from the sheet P in the double-sided conveyance path 202 and reduce the occurrence of dew condensation in the conveyance guide pair 210. This can reduce the occurrence of image defects and jams.

  Further, at least a part of the wind sent from the fan 232 and flowing in the duct 233 flows through the ventilation part 235 to the reversing guide 190. The fan 232 is arranged on the same side of the two-sided conveyance path 202 as the ventilation section 235 and in a space surrounded by the reversing guide 190 and the pair of conveyance guides 210. Thus, the size of the reversing unit 200 can be reduced.

  The downstream ends of the ventilation section 235 and the reversing guide 190 in the first direction A are provided close to each other. The reversing guide 190 has a first curved portion 203 curved downstream of the reversing roller pair 230 in the first direction A, and a second curved portion curved downstream of the first curved portion 203 in the first direction A toward the ventilation portion 235. And a curved portion 204.

  More specifically, the first curved portion 203 is arranged to intersect the nip line L1 of the reversing roller pair 230, and the second curved portion 204 is arranged in front of the ventilation portion 235 in the opening direction. I have. The reversing guide 190 extends in a substantially horizontal direction on the downstream side of the first curved portion 203 in the first direction A, and an angle θ1 between the nip line L1 and a horizontal plane is an angle of about 40 degrees to 80 degrees. Further, an angle θ2 formed by an extension of the surface of the reversing guide 190 on the upstream side and the downstream side in the first direction A of the second curved portion 204 is set to about 80 to 90 degrees. As described above, the second curved portion 204 is more gradually curved than the first curved portion 203, and has a radius of 70 mm or more. Then, the sheet P that has passed through the second curved portion 204 of the reversing guide 190 is conveyed substantially vertically upward.

  A step portion 206 is provided between the first bending portion 203 and the second bending portion 204 of the reversing guide 190. On the upstream side and the downstream side of the step portion 206 in the first direction A, both the sheets P are guided in a substantially horizontal direction, but the upstream side of the step portion 206 in the first direction A is lower than the downstream side. I have. The angle of the slope of the step portion 206 is set to about 10 degrees to 30 degrees. By providing such a step portion 206 in the reversing guide 190, the leading end of the sheet P floats up from the reversing guide 190 in the process of the sheet P passing through the step portion 206.

  Further, no guide member is provided between the reversing guide 190 and the fan 232. When a guide member is provided above the reversing guide 190, when the sheet P is conveyed in the second direction B by the pair of reversing rollers 230, the sheet P is rubbed by the guide member, and the conveyance resistance of the sheet P is reduced. , And a rub mark remains on the sheet P.

[Sheet conveyance operation and wind flow]
Next, the relationship between the transport operation of the sheet P and the flow of the wind will be described. FIGS. 4A and 4B are diagrams for explaining the flow of the sheet and the flow of the wind. In FIGS. 4A and 4B, the sheet P1 represents the preceding sheet, and the sheet P2 follows the preceding sheet. Represents the next sheet to be processed.

  4A, when the sheet P2 is being conveyed in the first direction A by the pair of reversing rollers 230, the sheet P1 straddles the ventilation section 235, that is, the position where the sheet P1 receives air from the duct 233. Located in. At this time, the wind sent from the fan 232 to the duplex conveying path 202 hits the sheet P1 passing through the duplex conveying path 202 and is blocked. Then, the place through which the wind flows is restricted by the wall surface of the duct 233 and the sheet P1, and the internal pressure of the duct 233 increases.

  For this reason, the air whose escape area is restricted in the duct 233 becomes wind and is sent from the ventilation section 235 to the reversing guide 190. The wind sent to the reversing guide 190 flows from the downstream in the first direction A to the upstream in the first direction A along the reversing guide 190 while being changed in direction by the second bending portion 204 that is relatively gently curved. The wind flowing along the reversing guide 190 enters between the sheet P2 and the reversing guide 190, so that the sheet P2 can float on the reversing guide 190, or the frictional resistance between the sheet P2 and the reversing guide 190 can be reduced. .

  Particularly, as shown in FIG. 5, since the reversing guide 190 is provided with the step portion 206, the leading end of the sheet P <b> 2 is lifted up by the step portion 206, and the wind enters between the sheet P <b> 2 and the reversing guide 190. Can be. Thereby, it is possible to reduce sticking of the sheet P2 to the reversing guide 190, and to reduce conveyance failure such as a jam.

  In the reversing unit 200 as in the present embodiment, the sheet P is usually conveyed in a state where the transfer surface is on the lower side in the vertical direction. Then, when the amount of applied toner on the transfer surface is large or when the temperature of the sheet is high, the sheet P easily sticks to the reversing guide 190. This is because the toner immediately after passing through the fixing unit 160 is heated and softened, and the frictional force between the reversing guide 190 and the toner increases. When the sheet P is conveyed in the first direction A by the pair of reversing rollers 230, the distance between the leading end of the sheet P and the pair of reversing rollers 230 increases, and the leading end of the sheet P hangs down due to its own weight. The frictional force between the rotation guide 190 and the reversing guide 190 increases, and buckling is likely to occur.

  However, in the present embodiment, when the sheet P2 is conveyed in the first direction A, the wind is sent between the sheet P2 and the reversing guide 190, so that the sticking of the sheet P2 to the reversing guide 190 is effective. Can be suppressed. Further, since the transfer surface of the sheet P1 is also cooled by the wind of the fan 232, sticking of the sheet P1 to the transport guide pair 210 can be suppressed. Thereby, it is possible to reduce the possibility that the sheet P buckles and causes a conveyance failure.

  Further, as shown in FIG. 4B, when the sheet P1 passes through the area where the duct 233 is disposed and the sheet P2 starts to be conveyed in the second direction B by the pair of reversing rollers 230, the fan The wind sent to the double-sided conveyance path 202 by 232 is not blocked by the sheet. For this reason, water vapor does not stay in the double-sided conveyance path 202, and the occurrence of dew condensation on the conveyance guide pair 210 can be reduced.

  As described above, in the present embodiment, when the succeeding sheet P2 enters the reversing guide 190, the wind of the fan 232 is applied to the preceding sheet P1, and the air flows between the sheet P2 and the reversing guide 190. Further, when the sheet P2 is being conveyed in the second direction B, the sheet P1 does not obstruct the wind of the fan 232, and the wind passes through the plurality of holes 211 of the conveyance guide pair 210. Thereby, it is possible to reduce the conveyance failure caused by the sheet sticking to the reversing guide 190 and to reduce the image failure caused by the dew condensation.

  In addition, although the form which provided the hole 211 in both the upper guide 210a and the lower guide 210b was illustrated, you may comprise so that the hole 211 may be provided only in the lower guide 210b without providing the hole 211 in the upper guide 210a. In addition, an example has been described in which the opening of the duct 233 through which air toward the reversing guide 190 passes is formed by the gap 713 between the first duct member 711 and the second duct member 714. You may comprise so that a hole may be provided.

<Second embodiment>
Next, a second embodiment of the present invention will be described. In the second embodiment, the arrangement of the fans and the peripheral configuration thereof in the first embodiment are changed. Therefore, configurations similar to those of the first embodiment will be described by omitting illustration or by attaching the same reference numerals to the drawings.

  As shown in FIG. 6, the reversing unit 300 according to the second embodiment includes a reversing guide 190, a pair of conveyance guides 210 forming the two-sided conveyance path 202, a fan 332, and a duct 333. I have. The duct 333 has a ventilation portion 335 that guides at least a part of the wind sent from the fan 332 toward the reversing guide 190. The fan 332 is disposed at a position facing the ventilation section 335 with the two-sided conveyance path 202 interposed therebetween, and sends a large amount of air to the ventilation section 335 with the conveyance guide pair 210 interposed therebetween. That is, the opening 332a of the fan 332 faces the ventilation section 335, and the wind sent from the fan 332 is directly sent to the ventilation section 335 without being guided by other members.

  In the present embodiment, the distance between the preceding sheet P1 (see FIG. 4A) and the succeeding sheet P2 (hereinafter referred to as the sheet interval) is longer than in the first embodiment. Therefore, as shown in FIG. 6, when the sheet P2 is being pulled in the first direction A by the reversing roller pair 230, the sheet P1 has already passed through the ventilation section 335. Therefore, the wind sent toward the two-sided conveyance path 202 by the fan 332 is sent to the ventilation unit 335 without being blocked by the sheet P1, and the wind can be efficiently sent to the reversing guide 190. Therefore, the sticking of the sheet P to the reversing guide 190 can be further reduced, and the conveyance failure can be reduced.

  In the present embodiment, the air volume of the fan 332 may be changed according to the basis weight of the conveyed sheet. For example, as shown in FIG. 7, the control unit 400 according to the present embodiment includes a CPU 401, a ROM 402 for storing a program, and a RAM 403 used as a program execution area. The operation unit 180 and the fan 332 are connected to the control unit 400.

  Control processing by the control unit 400 will be described with reference to the flowchart shown in FIG. First, the user inputs the basis weight of the sheet P via the operation unit 180 (Step S1). The input basis weight is stored in the RAM 403, for example. Then, the operation of conveying the input basis weight sheet is started (step S2). At this time, the control unit 400 determines whether to operate the fan 332 according to the basis weight of the sheet P (step S3).

  For example, when the input basis weight is a certain basis weight or more, the fan 332 is operated, and when the input basis weight is less than a certain basis weight, the fan 332 is not operated. This is to avoid a problem such as a sheet having a small basis weight being bent during conveyance due to the influence of the wind when the amount of wind sent to the reversing guide 190 is large as in the present embodiment. Further, since a sheet having a small basis weight receives less heat from the fixing unit 160, there is less risk of sticking to the reversing guide 190 than a sheet having a large basis weight. It should be noted that the rotation speed of the fan 332 may be changed instead of whether or not the fan 332 is operated, and any method may be used as long as the amount of air sent from the fan 332 is changed.

  Then, the control unit 400 operates the fan 332 in accordance with the determined operation of the fan 332, and in this state, the sheet P is reversed and conveyed by the pair of reversing rollers 230 (Steps S4 and S5). Thereafter, the sheet P is conveyed to the double-sided conveyance path 202 by the guide member 231 (Step S6). As described above, by changing the air volume of the fan 332 in accordance with the basis weight of the sheet, various types of sheets can be appropriately conveyed. The air volume of the fan 332 may be changed according to the type of sheet, such as plain paper, coated paper, and envelope, without being limited to the basis weight of the sheet. Further, the control of the fan 332 in accordance with the basis weight of the sheet may be applied to the first embodiment.

  In the first embodiment, the conveyance control is performed such that the wind of the fan 232 hits the preceding sheet P1 when the succeeding sheet P2 is conveyed in the first direction A, but is not limited thereto. . For example, the configuration may be such that the wind of the fan 232 hits the sheet P1 when the sheet P2 is being conveyed in the second direction B.

  Further, in any of the above-described embodiments, a fan for reducing condensation on the double-sided conveyance path 202 and a fan for reducing sticking of sheets guided by the reversing guide 190 may be provided separately. Good. Further, a single fan may be used, and the wind sent from the fan may be divided and used by a plurality of ducts.

  Further, in any of the above-described embodiments, the step portion 206 has a slope inclined upward toward the downstream in the first direction A, but is not limited thereto. For example, the step portion 206 may have a slope that is inclined downward toward the downstream in the first direction A.

  160: fixing section (fixing unit) / 190: reversing guide / 202: transport path (double-sided transport path) / 203: first curved section / 204: second curved section / 206: stepped section / 210: transport guide pair / 210b : One transport guide (lower guide) / 230: reversing transport section (reversing roller pair) / 232, 332: blowing section, fan / 233, 333: duct / 235, 335: ventilation section / 400: control section / 7111, 714: duct member (first duct member, second duct member) / 713: opening (gap) / A: first direction / B: second direction / T2: transfer unit (secondary transfer unit)

Claims (16)

A transfer unit for transferring a toner image to a sheet,
A fixing unit for fixing the toner image transferred by the transfer unit to a sheet,
A reverse transport unit that performs a reverse transport operation of transporting the sheet on which the toner image is fixed in a first direction, and then transporting the sheet in a second direction opposite to the first direction;
A reversing guide for guiding the sheet during the reversing conveyance operation,
A conveyance guide pair that forms a conveyance path through which the sheet subjected to the reverse conveyance operation passes, and guides the sheet conveyed through the conveyance path toward the transfer unit,
A blower for blowing air toward the transport path,
And a ventilation unit through which the wind directed to the reversing guide is passed from the ventilation unit.
The wind that has passed through the ventilation section flows along the reversing guide,
An image forming apparatus comprising: The wind that has passed through the ventilation portion flows from the downstream in the first direction to the upstream along the reversing guide,
The image forming apparatus according to claim 1, wherein: The blower is disposed on the same side of the transport path as the blower,
The image forming apparatus according to claim 1, wherein: When the subsequent sheet conveyed in the first direction by the reversing conveyance unit is guided by the reversing guide, the wind sent from the blower hits the preceding sheet passing through the conveyance path,
The image forming apparatus according to claim 1, wherein: The blower is disposed between the reversing guide and the transport guide pair,
The image forming apparatus according to claim 1, wherein: The air blower is disposed at a position facing the air blower with the transport path interposed therebetween,
The wind sent from the blowing unit is sent to the ventilation unit via the transport path.
The image forming apparatus according to claim 1, wherein: The transport guide pair has a hole through which the wind sent from the blower can pass,
The image forming apparatus according to claim 1, wherein: The reversing guide has a first bending portion that curves downstream of the reversing conveyance section in the first direction, and a second bending portion that curves toward the ventilation section downstream of the first bending portion in the first direction. And a part,
The image forming apparatus according to claim 1, wherein: The reverse guide has a step between the first bending portion and the second bending portion.
The image forming apparatus according to claim 8, wherein: According to the basis weight of the sheet to be conveyed, comprising a control unit that changes the amount of air sent from the blowing unit,
The image forming apparatus according to claim 1, wherein: The blower has a fan that rotates to generate wind,
The image forming apparatus according to claim 1, wherein: It is provided with a duct through which the wind sent from the blowing unit passes,
The image forming apparatus according to claim 1, wherein: The ventilation unit includes an opening provided in the duct,
The image forming apparatus according to claim 12, wherein: The duct is configured by one transport guide of the transport guide pair, and a duct member disposed on the opposite side to the other transport guide across the one transport guide,
The image forming apparatus according to claim 12, wherein: The blower, the duct, and the ventilation unit are arranged on the same side with respect to the transport path.
The image forming apparatus according to any one of claims 12 to 14, wherein: The reversing guide slides on a surface of the sheet on which the toner image is transferred by the transfer unit,
The image forming apparatus according to any one of claims 1 to 15, wherein:

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