Sheet conveyance device and image formation device

Abstract

To suppress turning up and flapping of a sheet in an inversion retreat part.SOLUTION: A sheet conveyance part 5 for conveying a sheet includes: an inversion mechanism 200 for conveying the sheet in a conveyance direction CD, and then conveying the sheet in an inversion conveyance direction RD opposite to the conveyance direction; an inversion retreat part 300 provided on the inversion mechanism, and temporarily retreating the sheet conveyed in the conveyance direction by the inversion mechanism; a double-sided conveyance part 220 for conveying the sheet conveyed in an inversion conveyance direction by the inversion mechanism; a first fan 221 provided on the double-sided conveyance part; and an inversion retreat guide member 310 provided on the inversion retreat part and guiding only one surface of the sheet, wherein the fan is arranged so as to blow air led from the double-sided conveyance part in the conveyance direction toward the inversion retreat part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sheet conveying device that conveys a sheet and an image forming apparatus that forms an image on a sheet. [Background technology]

[0002] Image forming devices such as printers, copiers, and multifunction peripherals form images on sheets used as recording materials. In face-down ejection, where the sheet is ejected with the image-formed side facing downward, or in duplex printing, where images are formed on both sides of the sheet, a reversing mechanism is used to reverse the sheet. Patent Document 1 discloses a reversing mechanism that includes a reversing conveyance mechanism having a pair of reversing rollers that performs switchback conveyance of the sheet, and a reversing retraction section through which the sheet is guided for switchback. In the case of duplex printing, a sheet with an image formed on its first side by an image forming unit is switched back by the pair of reversing rollers, passes through a duplex conveyance path, and is re-fed to the image forming unit in a state where the first side and the second side on which an image will be formed are reversed.

[0003] Some image forming devices discharge unjammed sheets from the conveyance path to a reversing / retracting section when a jam (paper jam) occurs. This allows multiple sheets stuck in the conveyance path inside the image forming device to be collected in the reversing / retracting section, improving jam clearance. In image forming devices equipped with such a sheet discharge mechanism, the reversing / retracting section has a guide member provided only below the sheets being conveyed.

[0004] On the other hand, when double-sided printing is performed, water vapor is released from the sheet that is switched back and conveyed to the double-sided conveying path, causing condensation on the guide member of the double-sided conveying path, which can cause the sheet to stick to the guide member and result in a jam.Patent Document 2 discloses an image forming apparatus that uses a fan to blow air into the double-sided conveying path to suppress the formation of condensation and prevent jams. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-66560 [Patent Document 2] Japanese Patent Publication No. 2020-38352 Summary of the Invention [Problem to be solved by the invention]

[0006] Recently, there has been a demand for faster printing in image forming devices. To increase printing speed, it is necessary to increase the sheet transport speed of the entire image forming device, and the speed of the switchback transport must also be increased. However, if the guide member of the reversing and retracting section is only on the lower side, increasing the switchback transport speed can cause the sheet to curl up due to air resistance, which can damage the sheet or cause a jam. [Means for solving the problem]

[0007] In order to solve the above problem, a sheet transporting device for transporting a sheet according to one embodiment of the present invention comprises: an inversion unit that conveys the sheet in a first direction and then conveys the sheet in a second direction opposite to the first direction; a reversing / evacuating section provided in the reversing section, into which the sheet conveyed in the first direction by the reversing section is temporarily evacuated; a conveying unit to which the sheet conveyed in the second direction by the reversing unit is conveyed; a fan provided in the transport section; a guide member provided in the reversing and retracting section and configured to guide only one surface of the sheet; Equipped with The fan is arranged to blow air drawn from the transport section in the first direction toward the reversing and retracting section. [Effects of the Invention]

[0008] According to the present invention, it is possible to increase the sheet conveying speed while suppressing the curling and flapping of the sheet in the reversing and retracting section. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] FIG. 10 is a cross-sectional view of a conventional sheet conveying unit. [Figure 4] FIG. 10 is an explanatory diagram showing the airflow of a fan that prevents the sheet from floating up. [Figure 5] 5 is a diagram showing the double-sided conveying section as viewed in the direction indicated by the arrow V in FIG. 4. [Figure 6] FIG. 10 is a cross-sectional view of a sheet conveying section according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Image forming device) Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of an image forming apparatus. The image forming apparatus 1 is a color printer that forms a color image on a sheet P (recording medium) using an electrophotographic system. However, the image forming apparatus 1 is not limited to this, and may be, for example, an electrophotographic copier (e.g., a digital copier), a color LED printer, an MFP (multifunction peripheral), a facsimile machine, or a printing machine. The image forming apparatus 1 is not limited to an electrophotographic image forming apparatus, and may also be an inkjet image forming apparatus. The image forming apparatus 1 may also be an image forming apparatus that forms a monochrome image.

[0011] The image forming apparatus 1 has four image forming units 2Y, 2M, 2C, and 2K, a secondary transfer unit 3 (transfer unit), a fixing unit 4, and a sheet conveying unit (sheet conveying device) 5. The image forming unit 2Y forms a yellow image using yellow toner. The image forming unit 2M forms a magenta image using magenta toner. The image forming unit 2C forms a cyan image using cyan toner. The image forming unit 2K forms a black image using black toner. The subscripts Y, M, C, and K of the reference symbols represent yellow, magenta, cyan, and black, respectively. In the following description, the subscripts Y, M, C, and K of the reference symbols may be omitted unless particularly necessary. The four image forming units 2Y, 2M, 2C, and 2K have the same structure except for the color of the toner (developer).

[0012] The image forming unit 2 has a photoconductor (image carrier) 11 as a rotating photosensitive drum. Around the photoconductor 11, there are arranged a charging device 12, an exposure device 13 that functions as an image writing unit, a developing device 14, a primary transfer device 35, and a drum cleaning device 15. Below the photoconductor 11, there is arranged an endless intermediate transfer belt (intermediate transfer body) 31.

[0013] The intermediate transfer belt 31 is stretched over an inner secondary transfer roller 32, a drive roller 33, a tension roller 34, and a primary transfer device 35. The intermediate transfer belt 31 rotates in the direction indicated by arrow B in FIG. 1 during image formation. The primary transfer device 35 is disposed opposite the photoconductor 11 with the intermediate transfer belt 31 interposed therebetween. The inner secondary transfer roller 32 is disposed opposite an outer secondary transfer roller 41 with the intermediate transfer belt 31 interposed therebetween, forming a secondary transfer nip between the intermediate transfer belt 31 and the outer secondary transfer roller 41. The inner secondary transfer roller 32 and the outer secondary transfer roller 41 constitute the secondary transfer unit 3. The belt cleaning device 36 is disposed opposite the drive roller 33.

[0014] Feeder cassettes 61, 62, and 63 for storing sheets P are arranged at the bottom of image forming apparatus 1. Feeder cassettes 61, 62, and 63 can store sheets P of different sizes. A manual feed tray 64 is arranged at the side of image forming apparatus 1. Sheets P are fed from feeder cassettes 61, 62, or 63 or manual feed tray 64 by pickup rollers 61a, 62a, 63a, or 64a, respectively.

[0015] The sheet P fed from the feeding cassette 61, 62, or 63 by the pickup roller 61a, 62a, or 63a in the direction indicated by arrow A is conveyed to the registration roller pair 110 by the conveying roller pair 130 and the pre-registration roller pair 120. The sheet P fed from the manual feed tray 64 by the pickup roller 64a is conveyed to the registration roller pair 110 by the pre-registration roller pair 73. In order to correct skew of the sheet P, the pre-registration roller pairs 120 and 73 abut the leading edge of the sheet P against the nip portion of the stopped registration roller pair 110. As a result, the pre-registration roller pairs 120 and 73 loop the sheet P, correcting skew of the sheet P. The registration roller pair 110 conveys the sheet P to the secondary transfer unit 3.

[0016] In the conveyance direction of the sheet P, an air suction conveying means 42 and a fixing unit 4 are disposed downstream of the secondary transfer unit 3. The air suction conveying means 42 conveys the sheet P from the secondary transfer unit 3 to the fixing unit 4. The fixing unit 4 has a fixing roller pair 50 consisting of a fixing roller 51 and a pressure roller 52. The fixing roller 51 and the pressure roller 52 are disposed opposite each other to form a fixing nip. A discharge tray 65 on which sheets P having images formed thereon are stacked is provided downstream of the fixing unit 4 in the conveyance direction of the sheet P.

[0017] In the case of double-sided printing or face-down discharge, the sheet P transported from the fixing unit 4 by the post-fixing roller pair 53 has its transport path switched to a reversing path 83 by a switching unit 81, and is transported by a first reversing roller pair 90 to a sheet transport unit (sheet transport device) 5. The sheet transport unit 5 has a reversing mechanism 200 (reversing unit) and a double-sided transport unit 220 (transport unit). The reversing mechanism 200 is provided with a reversing retraction unit 300.

[0018] (Image formation process) The image formation process of the image forming apparatus 1 will be described below. The image formation processes in the four image forming units 2Y, 2M, 2C, and 2K are the same, so only the image formation process in image forming unit 2Y, which forms a yellow image, will be described. The charging device 12Y uniformly charges the surface of the rotating photoreceptor 11Y. The exposure device 13Y irradiates the uniformly charged surface of the photoreceptor 11Y with a light beam modulated according to a signal for yellow image information, forming an electrostatic latent image on the surface of the photoreceptor 11Y. The developing device 14Y develops the electrostatic latent image with yellow toner, resulting in a visible yellow toner image. The primary transfer device 35Y is applied with a predetermined pressure and electrostatic bias, transferring the yellow toner image from the photoreceptor 11Y to the intermediate transfer belt 31 (primary transfer). Any toner remaining on the surface of the photoreceptor 11Y after the primary transfer is removed by the drum cleaning device 15Y.

[0019] Similarly, the magenta toner image formed by the image forming unit 11M is transferred onto the yellow toner image on the intermediate transfer belt 31 with high precision, superimposed thereon. Subsequently, a cyan toner image and a black toner image are sequentially transferred onto the magenta toner image on the intermediate transfer belt 31, superimposed thereon. As a result, a full-color toner image is formed on the intermediate transfer belt 31. As the intermediate transfer belt 31 rotates, the toner image on the intermediate transfer belt 31 is transported to the secondary transfer unit 3.

[0020] The sheet P is conveyed from the feed cassette 61, 62, or 63 or the manual feed tray 64 to the registration roller pair 110. The registration roller pair 110 conveys the sheet P to the secondary transfer unit 3 so that the leading edge of the sheet P is aligned with the toner image on the intermediate transfer belt 31 at the secondary transfer unit 3. The secondary transfer unit 3 transfers the toner image on the intermediate transfer belt 31 onto the sheet P by applying a predetermined pressure and electrostatic bias to the secondary transfer nip formed between the inner secondary transfer roller 32 and the outer secondary transfer roller 41 (secondary transfer). Any toner remaining on the surface of the intermediate transfer belt 31 after the secondary transfer is removed by a belt cleaning device 36. The sheet P onto which the toner image has been transferred is conveyed to the fixing unit 4 by an air suction conveying means 42. The fixing unit 4 applies pressure and heat to the sheet P at the fixing nip formed between the fixing roller 51 and the pressure roller 52 to fix the toner image to the sheet P. The sheet P with the fixed toner image is discharged from the fixing unit 4 by a post-fixing roller pair 53. Thereafter, the sheet P is discharged to the outside of the image forming apparatus 1 through a different path according to the paper passing mode.

[0021] When the paper passing mode is single-sided face-down paper passing, the transport path of the sheet P is switched to a reverse path 83 by a switching unit 81, and the sheet P with an image formed on one side is transported to the reverse path 83 by a first reverse roller pair 90. Thereafter, the transport direction of the sheet P is switched to a face-down discharge path 84 by a second reverse roller pair 92 that can switch the transport direction. The sheet P passes through the face-down discharge path 84 and is discharged face-down onto the discharge tray 65 by a discharge roller pair 93.

[0022] When the paper passing mode is single-sided face-up paper passing, the conveying path of the sheet P is switched to the face-up discharge path 82 by the switching unit 81, and the sheet P with an image formed on one side is conveyed to the face-up discharge path 82. Thereafter, the sheet P is discharged face-up onto the discharge tray 65 by the conveying roller pair 91 and the discharge roller pair 93.

[0023] When the paper passing mode is double-sided printing, the conveyance path of the sheet P is switched to the reverse path 83 by the switching unit 81, and the sheet P with an image formed on its first side (one side) is conveyed to the reverse path 83 by the first reverse roller pair 90. Thereafter, the sheet P is conveyed to the reversing mechanism 200 by the second reverse roller pair 92. The reversing mechanism 200 performs switchback conveyance to switch back the sheet P. The reversing mechanism 200 conveys the sheet P in the conveyance direction CD (first direction) by the forward rotation of the third reverse roller pair 230, and temporarily retracts the sheet P to the reversing retraction unit 300. Thereafter, the reversing mechanism 200 conveys the sheet P in the reverse conveyance direction RD (second direction) opposite to the conveyance direction CD by the reverse rotation of the third reverse roller pair 230, and conveys the sheet P to the double-sided conveyance unit 220.

[0024] The duplex conveying section 220 is connected to a pair of conveying rollers 130 located upstream of the secondary transfer section 3. The duplex conveying section 220 conveys the sheet P, whose first side and second side (the other side) have been inverted by the reversing mechanism 200, to the pair of conveying rollers 130. In this way, the sheet P switched back by the reversing mechanism 200 is conveyed again toward the pair of conveying rollers 130 by the reversing mechanism 200 and the duplex conveying section 220. The sheet P passes through the secondary transfer section 3 and the fixing section 4, and an image is formed on the second side. The conveying path of the sheet P with images formed on both sides is switched to a face-up discharge path 82 by a switching section 81. The sheet P is conveyed to the face-up discharge path 82 and then discharged to the discharge tray 65 by a pair of discharge rollers 93.

[0025] (sheet transport section) Next, the sheet conveying section (sheet conveying device) 5 will be described with reference to Figure 2. Figure 2 is a cross-sectional view of the sheet conveying section 5. The sheet conveying section 5 has a reversing mechanism 200 and a duplex conveying section 220. First, the reversing mechanism 200 will be described. The reversing mechanism 200 includes a reversing conveying section 201 (first conveying path), a third reversing roller pair 230, a duplex switching flap 231 (switching member), a reversing retreat section 300, and a conveying path 227 (second conveying path) branching off from the reversing conveying section 201. The sheet P guided to the reversing path 83 by the switching section 81 is conveyed from the reversing path 83 to the reversing conveying section 201 by a second reversing roller pair 92.

[0026] The reversing third roller pair 230 serving as a reversing means is provided downstream (vertically below) of a junction JP where the reversing conveyance section 201 and a conveyance path 227 join, in terms of the conveyance direction CD before the switchback in the reversing conveyance section 201. The reversing third roller pair 230 is, for example, driven and connected to a motor capable of forward and reverse rotation, and is configured to be able to switch the sheet conveyance direction between the conveyance direction CD before the switchback and a reverse conveyance direction RD opposite to the conveyance direction CD. The duplex switching flap 231 is provided at the junction JP where the reversing conveyance section 201 and the conveyance path 227 join, and prevents the sheet P conveyed in the reverse conveyance direction RD by the reversing third roller pair 230 from flowing back into the reversing path 83. The conveyance path 227 is in communication with the duplex conveyance path 226 of the duplex conveyance section 220. The sheet P conveyed in the reverse conveying direction RD by the reverse third roller pair 230 is guided by a double-sided switching flap 231 and conveyed to a double-sided conveying path 226 of the double-sided conveying section 220 through a conveying path 227 .

[0027] The double-sided conveying section 220 is provided with a plurality of double-sided conveying roller pairs 223, a first fan 221, a second fan 225, and a double-sided conveying guide member 224. The double-sided conveying guide member 224 defines a double-sided conveying path 226 for conveying the sheet P to the conveying roller pair 130. The plurality of double-sided conveying roller pairs 223 convey the sheet P, which has been reversed by the reversing third roller pair 230 and conveyed to the double-sided conveying section 220, toward the conveying roller pair 130.

[0028] The reversing and retracting section 300, which serves as a retracting section for the sheet P, is provided downstream of the reversing third roller pair 230 in the conveying direction CD before the switchback in the reversing conveying section 201. The reversing and retracting section 300 forms a retracting area RR for temporarily retracting a portion of the sheet P when the reversing third roller pair 230 switches back the sheet P. The reversing and retracting section 300 is configured by a metal reversing and retracting guide member 310 (guide member) arranged to surround the retracting area RR for retracting the sheet P conveyed by the reversing third roller pair 230. The reversing and retracting guide member 310 has a curved portion 310a. The reversing and retracting guide member 310 forms a retracting conveying path 320 along which the leading edge of the sheet P is guided so as to trace the inner surface of the reversing and retracting guide member 310 when the sheet P is conveyed to retract to the retracting area RR. The reversing and retracting guide member 310 is arranged on only one side of the retracting conveying path 320.

[0029] Next, the use of the reversing and retracting section 300 when a jam occurs will be described. As described above, the reversing and retracting section 300 provides a retraction area RR (space) for temporarily retracting the sheet P when the sheet P is reversed by the reversing third roller pair 230. However, if a jam occurs in the image forming apparatus 1, sheets retained inside the image forming apparatus 1 that can be transported to the reversing and retracting section 300 are transported to the reversing and retracting section 300. This allows the retraction area RR (space) inside the reversing and retracting section 300 to be used as a space for discharging (purging) sheets retained inside the image forming apparatus 1. Because the reversing and retracting guide member 310 of the reversing and retracting section 300 is positioned only below the purged sheet, there is an open space above the purged sheet. Because the reversing and retracting section 300 provides a user-accessible space above the reversing and retracting guide member 310, the user can easily clear the jam when it occurs.

[0030] Because the sheet P heated by the pair of fixing rollers 50 is at a high temperature, water vapor is released from the sheet P during conveyance, which can cause condensation on the cooled reversal / retraction guide member 310. When condensation forms on the reversal / retraction guide member 310, the condensed water can cause the sheet P to stick to the reversal / retraction guide member 310, resulting in a jam. Even if a jam does not occur, the condensed water can leave marks on the sheet P, resulting in poor image quality. As shown in FIG. 2 , the conveyance surface of the duplex conveying guide member 224 of the duplex conveying section 220 is provided with multiple ventilation holes 222 (multiple holes) for air passage. The first fan 221 and the second fan 225 draw air from the duplex conveying section 220 to prevent water vapor from accumulating inside the duplex conveying section 220 and prevent condensation from forming on the duplex conveying guide member 224. This prevents jams and poor image quality at the duplex conveying guide member 224.

[0031] In order to increase the printing speed of the image forming apparatus 1, it is necessary to increase the overall conveyance speed of the sheet P in the image forming apparatus 1. The conveyance speed of the sheet P during the switchback operation in the image forming apparatus 1 is also higher than the conveyance speed of conventional image forming apparatuses. However, increasing the conveyance speed of the sheet P during the switchback operation may cause the sheet P to lift up in the reversing and retracting section 300. FIG. 3 is a cross-sectional view of a conventional sheet conveying section 105. As shown in FIG. 3, a fan 232 provided in the conventional sheet conveying section 105 blows air toward the duplex conveying guide member 224. As shown by the dashed-dotted line in FIG. 3, the leading edge of the sheet P being conveyed to the reversing and retracting section 300 may lift up due to air resistance caused by the movement of the sheet P in the conveying direction CD before the switchback. If the sheet P lifts up, the sheet P may be damaged or the conveyance position of the sheet P may become unstable.

[0032] Therefore, in this embodiment, a first fan 221 disposed in the duplex conveying section 220 blows air toward the reversing and retracting section 300 to prevent the sheet P from floating up. FIG. 4 is an explanatory diagram showing the airflow of the first fan 221 that prevents the sheet P from floating up. FIG. 5 is a diagram showing the duplex conveying section 220 as viewed in the direction indicated by arrow V in FIG. 4. The duplex conveying section 220 is provided with multiple fans. The duplex conveying section 220 has the first fan 221 disposed near the duplex switching flap 231. The first fan 221 has three fans 221a, 221b, and 221c arranged side by side in the width direction W, which is perpendicular to the reverse conveying direction RD of the sheet P in the duplex conveying section 220. A second fan 225 is provided downstream of the first fan 221 in the reverse conveying direction RD. The second fan 225 has three fans 225a, 225b, and 225c arranged side by side in the width direction W. The control unit 6 provided in the image forming apparatus 1 controls the driving and stopping of the first fan 221 and the second fan 225.

[0033] The first fan 221 blows air drawn from the duplex conveying section 220 toward the reversing and retracting guide member 310 of the reversing mechanism 200, as indicated by arrow F1. The second fan 225 blows air drawn from the duplex conveying section 220 toward the reversing and retracting section 300, as indicated by arrow F2. The air from the first fan 221 flows toward the reversing and retracting section 300, as indicated by arrow F1, and flows along the reversing and retracting guide member 310 in the same direction as the conveying direction CD of the sheet P before the switchback. The air from the second fan 225 flows toward the reversing and retracting section 300, as indicated by arrow F2. The air flows from the first fan 221 and the second fan 225, reducing the air resistance experienced by the leading edge of the sheet P conveyed in the conveying direction CD, thereby preventing the sheet P from floating up.

[0034] If the sheet P being conveyed to the reversing and retracting section 300 is a long sheet, the air from the second fan 225 may cause the sheet P to flutter. Therefore, if the sheet P is a long sheet, one, two, or three of the three fans 225a, 225b, and 225c of the second fan 225 may be stopped. The control unit 6 controls the driving and stopping of the three fans 225a, 225b, and 225c of the second fan 225 according to the size of the sheet P. For example, if the sheet P is an A3-sized sheet, all three fans 225a, 225b, and 225c of the second fan 225 may be stopped, and air may be blown only from the first fan 221 in the same direction as the conveying direction CD of the sheet P before the switchback. By controlling the driving and stopping of the three fans 225a, 225b, and 225c of the second fan 225 according to the size of the sheet P, flapping of the sheet P can be prevented. On the other hand, the three fans 221a, 221b, and 221c of the first fan 221 may blow air to all paper types regardless of the size of the sheet P in order to prevent the sheet P from floating up in the reversing and retracting section 300.

[0035] The first fan 221 and the second fan 225 draw air from the double-sided conveying section 220, thereby preventing condensation from occurring on the double-sided conveying guide member 224 of the double-sided conveying section 220. According to this embodiment, the first fan 221 and the second fan 225 used to prevent condensation in the double-sided conveying section 220 prevent the sheet P from floating up, so the conveying speed of the sheet P during switchback can be increased.

[0036] In this embodiment, the first fan 221 has three fans 221a, 221b, and 221c, and the second fan 225 has three fans 225a, 225b, and 225c. However, the number of fans included in each of the first fan 221 and the second fan 225 is not limited to three and may be one, two, four, or five or more. Alternatively, the duplex conveying unit 220 may include only the first fan 221 without the second fan 225. FIG. 6 is a cross-sectional view of a modified sheet conveying unit 205. The sheet conveying unit 205 includes only the first fan 221 without the second fan 225. In this case, an additional fan is not required, thereby suppressing increases in cost and power consumption of the image forming apparatus 1 and improving printing speed. According to this embodiment, the sheet conveying speed can be increased while suppressing sheet curling and flapping in the reversing and retracting unit 300. [Explanation of symbols]

[0037] 5. Sheet transport section 200....Reversal mechanism 220 Double-sided conveying section 221...First Fan 300....Reverse evacuation section 310 Reverse evacuation guide member CD: Transport direction RD: Reverse transport direction P... Sheet

Claims

1. A sheet conveying device that conveys a sheet, an inversion unit that conveys the sheet in a first direction and then conveys the sheet in a second direction opposite to the first direction; a reversing and evacuation section provided in the reversing section, into which the sheet conveyed in the first direction by the reversing section is temporarily evacuated; a conveying section that has a conveying path through which the sheet conveyed in the second direction by the reversing section passes and conveys the sheet; A guide member provided in the reversing and retracting section and configured to guide one surface of the sheet; a fan provided in the conveying section and configured to blow air toward the sheet guided by the guide member; Equipped with the fan is disposed to blow air in the transport path in the transport section toward the reversing and evacuation section along the first direction of the guide member. A sheet conveying device comprising:

2. The inversion portion is a first conveying path along which a sheet is conveyed in the first direction and the second direction; a second conveying path along which the sheet is conveyed in the second direction from the reversing unit to the conveying unit; a switching member provided at a junction of the first transport path and the second transport path and configured to switch a transport path of a sheet; Equipped with The sheet transport device according to claim 1 , wherein the fan is disposed in the vicinity of the switching member.

3. 3. The sheet transport device according to claim 1, wherein the air from the fan flows along the sheet guided by the guide member.

4. 4. The sheet conveying device according to claim 1, wherein a space accessible to a user is provided above the guide member in the reversing and retracting section.

5. 5. The sheet transport device according to claim 1, wherein the fan includes a plurality of fans arranged side by side along a transport surface of the transport section in a direction perpendicular to the second direction in the transport section.

6. The sheet transport device according to claim 5 , wherein the transport surface of the transport section is provided with a plurality of holes through which the air passes.

7. 7. The sheet transport device according to claim 1, further comprising a second fan provided in the transport section downstream of the first fan in the second direction in the transport section.

8. The method further comprises: a second fan provided in the conveying section downstream of the first fan in the second direction in the conveying section; The sheet transport device according to claim 5 , wherein the second fan includes a plurality of fans arranged side by side along the transport surface of the transport section in a direction perpendicular to the second direction in the transport section.

9. 9. The sheet transport device according to claim 7, wherein the second fan is disposed so as to blow air in the transport path in the transport section toward the reversing and retracting section.

10. A sheet conveying device as described in any one of claims 7 to 9, further comprising a control unit that controls driving and stopping of the first fan and the second fan.

11. The control unit drives the second fan when a first sheet is to be transported, When a second sheet having a length in a sheet transport direction longer than that of the first sheet is transported, the second fan is stopped. The sheet transport device according to claim 10 .

12. The control unit drives the first fan regardless of the size of the sheet. The sheet transport device according to claim 11 .

13. The guide member is a first guide member that contacts one surface of the sheet to guide the sheet, A second guide member that faces the first guide member and contacts the other surface of the sheet opposite to the one surface of the sheet to guide the sheet is not provided. The sheet transport device according to any one of claims 1 to 12.

14. An image forming unit that forms an image on a sheet; A sheet conveying device according to any one of claims 1 to 13, An image forming apparatus comprising:

15. the sheet conveying device conveys the sheet having the image formed on the one side to the first direction by the inversion unit and temporarily retreats the sheet to the inversion retreat unit, then conveys the sheet to the conveying unit in the second direction by the inversion unit, and then conveys the sheet from the conveying unit to the image forming unit; 15. The image forming apparatus according to claim 14, wherein an image is thereby formed on the other surface of the sheet.

16. 16. The image forming apparatus according to claim 15, wherein the reversing section conveys the sheet remaining inside the image forming apparatus to the reversing and retracting section when the sheet jams.

Images