Image formation device

Abstract

To prevent an inversion roller from deviating in an axial direction at normal rotation and at reverse rotation to reduce a positional deviation of a sheet caused by a deviation in the axial direction of the inversion roller.SOLUTION: An image formation device includes: an image formation part; a re-feed part configured to feed a sheet with an image formed by the image formation part again to the image formation part; and an inversion part configured to invert the sheet with the image formed by the image formation part and convey the sheet to the re-feed part. The inversion part includes: an inversion roller configured to rotate normally or rotate reversely to convey a sheet; a helical gear provided on an axis of the inversion roller and driven to rotate the inversion roller normally or reversely integrally to rotation; and a pressing member configured to press the inversion roller in the axial direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] In an electrophotographic image forming apparatus, a latent image formed on an image carrier is developed in an image forming section to form a visible image. The visible image is then transferred to a sheet fed to the image forming section, and the transferred image is fixed by applying heat and pressure in a fixing unit, forming an image on the sheet. The sheet with the fixed image is then ejected from the machine by a paper ejection roller.

[0003] Furthermore, Patent Document 1 describes that when printing on both sides of a sheet, the sheet, which has an image fixed on one side through a fixing device, is reversed and conveyed by a reversing roller and re-fed to the image forming unit via a double-sided conveyance path. Then, through a transfer and fixing process, the image is fixed on the other side. The sheet, with images formed on both sides, is then ejected outside the machine by a paper ejection roller. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-200437 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, when performing double-sided printing, the reversing roller rotates forward to transport the sheet a certain distance toward the outside of the printer, and then rotates reverse to transport the sheet to the double-sided transport path. During this process, a force acts on the reversing roller in an axial direction (thrust direction) perpendicular to the sheet transport direction due to the reaction force of the sheet and the reaction force of the gears, causing the thrust position of the reversing roller to change between forward and reverse rotation. The difference in the amount of movement of the reversing roller in the thrust direction during forward and reverse rotation manifests as a relative positional deviation in the main scanning direction between the first and second sides of the sheet, degrading the quality of the finished product. [Means for solving the problem]

[0006] A typical configuration of the present invention is an image forming apparatus comprising an image forming unit, a re-feeding unit that feeds the sheet on which an image has been formed by the image forming unit back to the image forming unit, and an inversion unit that inverts the sheet on which an image has been formed by the image forming unit and transports it to the re-feeding unit, wherein the inversion unit has a reversing roller that rotates forward or backward to transport the sheet, a helical gear that is provided on the axis of the reversing roller and drives it to rotate forward or backward in unison with the rotation of the reversing roller, and a pressing member that presses the reversing roller in the axial direction. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress axial misalignment of the reversing roller during forward and reverse rotation, and to reduce positional misalignment of the sheet caused by axial misalignment of the reversing roller. [Brief explanation of the drawings]

[0008] [Figure 1] Cross-sectional view of an image forming apparatus [Figure 2] Top view of the reversing roller during forward rotation [Figure 3] Top view of the reversing sheet during reverse rotation [Figure 4] Top view of the reversing roller [Figure 5] Top view of the reversing roller [Figure 6] Top view of the reversing roller [Figure 7] (a)(b)(c) Perspective view of the reversing roller DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the following embodiments may be changed as appropriate depending on the configuration of the device to which the present invention is applied and various conditions, and are not intended to limit the scope of the present invention to those alone.

[0010] (Image forming device) The schematic configuration of an image forming apparatus will be described using Figure 1. Figure 1 is a cross-sectional view of the image forming apparatus. The image forming apparatus 100 shown in Figure 1 is an example of an intermediate transfer tandem type image forming apparatus in which four color image forming units 140 are arranged side by side on an intermediate transfer belt 145.

[0011] The image forming apparatus includes an image forming section 140, a re-feeding section 180 that feeds the sheet S on which an image has been formed by the image forming section 140 back to the image forming section 140, and an inversion section 190 that inverts the sheet S on which an image has been formed by the image forming section 140 and transports it to the re-feeding section 180.

[0012] Sheets S are stacked and stored in a storage unit such as a cassette located below the image forming apparatus. The sheets S stored in the storage unit are fed by a sheet feeding unit 110 in accordance with the image formation timing of the image forming apparatus. The sheets S fed by the sheet feeding unit 110 are transported to a skew correction device 120. After the skew correction device 120 corrects the sheet S for skew and timing, the sheet S is sent to a secondary transfer unit 130. The secondary transfer unit 130 is formed by a secondary transfer inner roller 131 and a secondary transfer outer roller 132 that face each other across an intermediate transfer belt 145. The secondary transfer unit 130 transfers the toner image formed on the intermediate transfer belt 145 to the sheet S by applying a predetermined pressure force and an electrostatic load bias while nipping and transporting the sheet S.

[0013] The image formation process for the sheet S, which is sent to the secondary transfer unit 130 at the same timing as the transport process of the sheet S to the secondary transfer unit 130 described above, will now be described. The image forming unit 140 is mainly composed of a photoconductor 141, an exposure device 142, a developing device 143, and a primary transfer device 144. The surface of the photoconductor 141 is uniformly charged in advance by a charging unit (not shown). The exposure device 142 emits light onto the charged photoconductor 141 based on a signal of image information, and a latent image is formed via appropriate means such as a diffraction means. The electrostatic latent image thus formed on the photoconductor 141 is developed with toner by the developing device 143, and a toner image is formed on the photoconductor 141. The toner image formed on the photoconductor 141 is transferred to an intermediate transfer belt 145 by the primary transfer device 144 at a primary transfer unit where the photoconductor 141 and the primary transfer device 144 face each other, with a predetermined pressure force and electrostatic load bias applied by the primary transfer device 144.

[0014] 1, four sets of the image forming units 140 are provided, one for yellow Y, one for magenta M, one for cyan C, and one for black Bk. These four image forming units 140 are arranged side by side on the intermediate transfer belt 145.

[0015] Next, the intermediate transfer belt 145 will be described. The intermediate transfer belt 145 is stretched over multiple rollers and driven to be transported in the direction of the arrow in FIG. 1. Therefore, the image forming units 140 for yellow Y, magenta M, cyan C, and black Bk described above process the images in parallel. The image forming process for each color is performed in the primary transfer unit of each image forming unit 140 at a timing that overlaps the upstream toner image that has been primarily transferred onto the intermediate transfer belt 145. As a result, a full-color toner image is finally formed on the intermediate transfer belt 145 and transported to the secondary transfer unit 130.

[0016] Through the sheet S transport process and image formation process described above, a full-color toner image is secondarily transferred onto the sheet S in the secondary transfer unit 130. The sheet S is then transported to the fixing device 150. The fixing device 150 fixes the toner image onto the sheet S by applying a predetermined pressure from opposing rollers or belts, etc., and generally by applying a heating effect from a heat source such as a heater.

[0017] The sheet S having the fixed image thus obtained is guided toward the first discharge rollers 161 by the first switching flapper 151 in the solid line position in Fig. 1, and is discharged onto the first stacking unit 171 by the first discharge rollers 161. Alternatively, the sheet S is guided upward by the first switching flapper 151 switched to the dashed line position in Fig. 1, and is conveyed toward the second discharge rollers 162.

[0018] The sheet S being transported toward the second discharge roller 162 is guided toward the second discharge roller 162 by the second switching flapper 152 at the dashed line position in Figure 1, and is discharged by the second discharge roller 162 onto the second stacking section 172 located above the first stacking section 171.

[0019] In the case of double-sided printing, the second discharge roller 162 is rotated in the reverse direction after the trailing edge of the sheet S passes through the second switching flapper 152. Due to this reversing operation of the second discharge roller 162, the sheet S is guided toward the re-feeding section 180 by the second switching flapper 152, which has been switched to the position indicated by the solid line in FIG. 1. In other words, in the case of double-sided printing, the sheet S on which an image has been formed by the image forming section 140 is reversed and conveyed by the reversing section 190, sent to the re-feeding section 180, and then conveyed again to the image forming section 140 by the re-feeding section 180.

[0020] Then, the sheet S passes through a re-feeding section 180 and is conveyed to the image forming section 140 (secondary transfer section 130) by the skew correction device 120, where an image is formed on the second side in the same manner as on the first side. The sheet S on which double-sided printing has been performed is discharged onto the first stacking section 171 or the second stacking section 172.

[0021] The first stacking section 171 and the second stacking section 172 on which the discharged sheets S are stacked have an upward slope facing from upstream to downstream in the discharge direction of the sheets S. Therefore, the discharged sheets S can be aligned upstream in the discharge direction due to the weight of the sheets themselves.

[0022] (reversal part) Here, a detailed description will be given of the reversing section 190. The reversing section 190 has a reversing roller (second discharge roller 162) that rotates forward or backward to convey a sheet, and a second switching flapper 152 as a switching member.

[0023] Here, the reversing roller also serves as the second discharge roller 162, which is a discharge roller that discharges the sheet S outside the apparatus. However, the reversing roller is not limited to this. A configuration in which the reversing roller is provided independently from the discharge roller that discharges the sheet outside the apparatus is also acceptable.

[0024] 1 includes an image reading unit 300 that is provided above the image forming unit 140 across an internal space 170 and that reads images on documents. A first stacking unit 171 and a second stacking unit 172 are disposed in the internal space 170 that is formed between the image forming unit 140 and the image reading unit 300. The reversing rollers also serve as second discharge rollers 162 that discharge sheets on which images have been formed onto the second stacking unit 172.

[0025] The second switching flapper 152 is provided between the image forming unit 140 and the second discharge roller 161, which is a reversing roller. The second switching flapper 152 is a switching member that can be switched to a first position where it guides the sheet S or a second position different from the first position. Here, the first position is a position (position indicated by a broken line in FIG. 1) where it guides the sheet on which an image has been formed by the image forming unit 140 to the second discharge roller 162. The second position is a position (position indicated by a solid line in FIG. 1) where it guides the sheet S, which has been reversed and conveyed by the second discharge roller 162, which is a reversing roller, to the re-feeding unit 180.

[0026] The second discharge roller 161, which is a reversing roller, rotates forward or backward upon receiving a driving force from a motor 201, which is a driving source. This will be explained using Figures 2 and 3. Figures 2 and 3 are diagrams of the periphery of the second discharge roller 162 of the image forming apparatus 100. Figure 2 is a diagram showing how the sheet S before being reversed is being transported by the second discharge roller 162. Figure 3 is a diagram showing how the sheet S after being reversed is being transported by the second discharge roller 162.

[0027] 2 and 3, the second discharge roller 162 has a drive gear 204. The drive gear 204 is provided at one end of the shaft of the second discharge roller 162. The drive gear 204 engages with the second discharge roller 162 in the rotational direction, and the drive gear 204 and the second discharge roller 162 rotate simultaneously. The drive gear 204 is provided with an engagement portion 204a, and the second discharge roller 162 is provided with a roller groove 162a that engages with the engagement portion 204a in the thrust direction. That is, the engagement portion 204a of the drive gear 204 engages with the roller groove 162a of the second discharge roller 162 in the thrust direction, and the drive gear 204 and the second discharge roller 162 move together in the thrust direction as well.

[0028] A motor gear 202 connected to the motor 201 meshes with a gear 203, and the gear 203 meshes with a drive gear 204 of the second discharge roller 162. That is, the power of the motor 201 is transmitted in the order of the gear 202, the gear 203, and the gear 204. The second discharge roller 161 receives the drive force from the motor 201 and rotates forward or backward.

[0029] Here, the drive gear 204 of the second discharge roller 161 is a helical gear. The helical gear is provided on the shaft of the second discharge roller 162 and is driven to rotate forward or backward together with the rotation of the second discharge roller 162. Therefore, for example, as shown in FIG. 2, a thrust force in the direction of arrow C, which extends from one side of the axial direction to the other side, acts on the forward-rotating second discharge roller 162 between the forward-rotating drive gear 204 and gear 203. On the other hand, as shown in FIG. 3, a thrust force in the direction of arrow C', which extends from the other side of the axial direction to one side, acts on the reverse-rotating second discharge roller 161 between the reverse-rotating drive gear 204 and gear 203.

[0030] Note that, here, a helical gear is used as an example of the specifications of drive gear 204, in which a thrust force acts in the direction of arrow C on a roller that rotates forward and in the direction of arrow C' on a roller that rotates backward, but this is not limiting. With a helical gear, the direction of the thrust force acting on the roller can be reversed depending on the inclination of the teeth with respect to the direction of rotation.

[0031] Now, consider the case where the second discharge rollers 162 rotate in the direction of arrow A and convey the sheet S in the direction of arrow B. The second discharge rollers 162 rotate forward in the direction of arrow A and convey the sheet S in the direction of arrow B towards the outside of the apparatus, and stop at a position where the trailing edge of the sheet S has passed through the second switching flapper 152. Here, the sheet S is conveyed from the dashed line position S1 in FIG. 2 to the solid line position S2 and stops at the solid line position S2.

[0032] At this time, it is assumed that a thrust force acts on the second discharge roller 162 in the direction of arrow C while the second discharge roller 162 is rotating forward in the direction of arrow A. The direction and magnitude of the thrust force acting on the second discharge roller 162 may be reversed depending on the gear specifications, the shape of the sheet during transport, etc. At this time, when the second discharge roller 162 moves a distance dx in the axial direction due to the thrust force C, the amount of axial movement of the sheet S while it is transported in the direction of arrow B is also dx.

[0033] Also, consider the case where the second discharge rollers 162 rotate in the direction of arrow A', which is the opposite direction to the direction of arrow A, and convey the sheet S in the direction of arrow B', which is the opposite direction to the direction of arrow B. The second discharge rollers 162 rotate in the opposite direction to the direction of arrow A' and convey the sheet S in the direction of arrow B' towards the re-feeding section 180. Here, the sheet S is reversed and conveyed from the dashed line position S2 in FIG. 3, which is the stop position (solid line position in FIG. 2) described above, to the solid line position S3.

[0034] During this reverse conveyance of the sheet, the second discharge roller 162 rotates in the opposite direction, and the conveyance direction of the sheet S is also reversed. This causes a thrust force C' in the opposite direction to the thrust force C in FIG. 2 to act on the second discharge roller 162. If the thrust force C' during reverse conveyance of the sheet S causes the second discharge roller 162 to move a distance dx' in the axial direction, the amount of axial movement of the sheet S when conveyed in the direction of arrow B' will also be dx'. In this case, if the amount of axial movement dx of the sheet S toward one side in FIG. 2 is not equal to the amount of axial movement dx' of the sheet S toward the other side in FIG. 3, the sheet S will be displaced by a difference (y = dx' - dx) in the direction perpendicular to the conveyance direction during reverse conveyance. The reversed and conveyed sheet S is then re-fed to the image forming unit 140, where the second side is printed. However, the image on the second side will be displaced axially from the image on the first side by the difference (y = dx' - dx). If this deviation y occurs, it can be a factor that reduces the quality of the deliverables.

[0035] 4, the second discharge roller 162 is pressed in the axial direction (thrust direction) by a pressing member 207. That is, the reversing unit 190 has a pressing member 207 that presses the second discharge roller 162, which is a reversing roller, in the axial direction. Fig. 4 is a view of the second discharge roller 162, which is a reversing roller, as seen from above.

[0036] The pressing member 207 comes into contact with one end of the shaft of the second discharge roller 162, which is a reversing roller, and presses the second discharge roller 162 from one side to the other in the axial direction. Here, as shown in Fig. 4, a pressing member that is pressed from one side to the other in the axial direction by a biasing member 208 such as a coil spring is exemplified as the pressing member 207, but the configuration of the pressing member is not limited to this.

[0037] The second discharge roller 162 is rotatably supported by bearings 205a and 205b on both axial sides thereof that are outside the conveyance area of ​​the sheet S where the roller portion that comes into contact with the sheet S is disposed. The bearings 205a and 205b are each attached to a guide member 206 that is a support member that supports the second discharge roller 162.

[0038] The pressing member 207 that presses the second discharge roller 162 in the axial direction (thrust direction) is set so that the axial pressing force R is greater than the thrust force C. In other words, the pressing force R of the pressing member 207 is set to be greater than the axial moving force (thrust force C) that acts on the second discharge roller 162 when the second discharge roller 162 rotates forward. This pressing force R causes the drive gear 204 to abut against the bearing 205a, restricting the axial movement of the second discharge roller 162 and determining its position in the thrust direction.

[0039] The second discharge roller 161, which is a reversing roller, has an abutting member that is abutted by the pressing force R of the pressing member 207. In the configuration shown in Fig. 4, the drive gear 204 provided at one end of the shaft of the second discharge roller 162 also serves as the abutting member that is abutted against the guide member 206 (bearing 205), which is a support member.

[0040] 4, the driving gear 204 as an abutting member is abutted against a bearing 205a as a support member that supports the second discharge roller 162, which is a reversing roller, by the pressing force of the pressing member 207, thereby restricting the axial movement of the second discharge roller 162 and determining its axial position. The bearing 205a rotatably supports the shaft of the second discharge roller 162 and is provided in a guide member 206 as a support member that supports the second discharge roller 162. In other words, the guide member 206 as a support member and the bearing 205a provided in the guide member 206 are members that do not move in the axial direction. Therefore, the driving gear 204 as an abutting member is abutted against the bearing 205a as a support member by the pressing force of the pressing member 207, thereby determining the axial position of the second discharge roller 162, which is a reversing roller.

[0041] 4, even if the second discharge roller 162 rotates forward in the direction of arrow A and the sheet S is transported in the direction of arrow B while the drive gear 204 is abutting against the bearing 205a, the axial movement of the second discharge roller 162 is restricted. Therefore, the axial movement amount dx of the second discharge roller 162 when the sheet S is transported in the direction of arrow B is 0, and therefore the axial movement amount (amount of deviation) of the sheet S is also 0.

[0042] The abutment member is not limited to the configuration illustrated in FIG. 4, but may be configured as shown in FIG. 5, for example.

[0043] As shown in FIG. 5, the second discharge roller 162, which is a reversing roller, may have an engaging member 210 as an abutting member in addition to the drive gear 204. The second discharge roller 162 is provided with a roller groove 162b that engages with the engaging member 210 in the thrust direction. That is, the engaging member 210 engages with the roller groove 162b of the second discharge roller 162 in the thrust direction, and the engaging member 210 and the second discharge roller 162 move in conjunction with each other in the thrust direction. The engaging member 210 is provided on the other end side of the shaft of the second discharge roller 161, and is abutted against a guide member 206, which is a support member, by the pressing force of a pressing member 207, and engages with the guide member 206 in the axial direction. This configuration may be used.

[0044] 5, the engaging member 210 as an abutting member is abutted against the guide member 206 as a support member that supports the second discharge roller 162, which is a reversing roller, by the pressing force of the pressing member 207, thereby restricting the axial movement of the second discharge roller 162 and determining its axial position. In this way, as long as there is an engaging member 210 that engages with the second discharge roller 162 in the thrust direction and the engaging member abuts against the guide member 206, it is not necessary for the drive gear 204 and the bearing 205a to abut against each other.

[0045] 6, a case will be described in which the second discharge roller 162 rotates in the direction of arrow A' and the sheet S is reversed and conveyed in the direction of arrow B'. Fig. 6 is a view of the second discharge roller 162, which is a reversing roller, as seen from above.

[0046] 4, the second discharge roller 162 is pressed in the axial direction (thrust direction) by the pressing member 207. As in FIG. 4, the pressing member 207 that presses the second discharge roller 162 in the axial direction (thrust direction) is set so that the axial pressing force R is greater than the thrust force C'. In other words, the pressing force R of the pressing member 207 is set to be greater than the axial moving force (thrust force C') acting on the second discharge roller 162 when the second discharge roller 162 rotates in the reverse direction. In the case shown in FIG. 6, the pressing force R of the pressing member 207 is a force in the opposite direction to the axial moving force (thrust force C') acting on the second discharge roller 162.

[0047] 6, even when the second discharge roller 162 rotates in the reverse direction of arrow A' and reversely conveys the sheet S in the direction of arrow B', the pressing force R is greater than the thrust force C', so the axial movement of the second discharge roller 162 is restricted and the axial position is determined. Therefore, the axial movement amount dx' of the second discharge roller 162 when reversely conveying the sheet S in the direction of arrow B' is 0, and therefore the axial movement amount (misalignment amount) of the sheet S is also 0. This reduces the axial (thrust direction) misalignment between the first and second sides of the sheet S even during double-sided printing.

[0048] Thus, according to this embodiment, the axial misalignment of the second discharge roller 162, which is a reversing roller, can be suppressed when rotating forward and reverse, and the positional misalignment of the sheet S caused by the axial misalignment of the second discharge roller 162 can be reduced.

[0049] 7(a), 7(b), and 7(c) are perspective views of the second discharge roller, which is a reversing roller. The pressing configuration of the pressing member 207 against the reversing roller (second discharge roller 162) will be described.

[0050] Fig. 7(a) shows the pressing configuration of the reversing roller shown in Fig. 4 and Fig. 6. As shown in Fig. 7(a), pressing member 207 is urged by urging member 208, thereby pressing the axial end of second discharge roller 162, which is the reversing roller, from one side to the other in the axial direction. However, the pressing configuration of the reversing roller is not limited to this, and may be the configuration shown in Fig. 7(b) or Fig. 7(c).

[0051] 7(b), the pressing member 207 presses the thrust end surface of the drive gear 204 from one side to the other in the axial direction. By pressing in this manner, a pressing force R is applied to the second discharge roller 162, which is a reversing roller.

[0052] 7(c), the second discharge roller 162, which is a reversing roller, has a pressed member 209 at one end of its shaft opposite to the end at which the drive gear 204 is provided. The pressing member 207 presses the pressed member 209 from one side to the other side in the axial direction.

[0053] This is because, when there is no space to provide a pressing member 207 around the drive gear 204, a similar effect can be achieved by adding a pressed member 209 that engages with the second discharge roller 162, which is a reversing roller, and pressing the pressed member 209 with the pressing member 207.

[0054] Furthermore, although the pressing member 207 is configured to press the second discharge roller 162, which is a reversing roller, from one side to the other in the axial direction, the present invention is not limited to this. The pressing member 207 may be configured to press the reversing roller (second discharge roller 162) from the other side to one side in the axial direction. This configuration can provide the same effects as the above-described embodiment. [Explanation of symbols]

[0055] S...Seat 100...Image forming device 130...Secondary transfer unit 140...Image forming unit 151...First switching flapper 152 ... Second switching flapper (switching member) 161 ... First discharge roller 162 ... Second discharge roller (reversal roller) 170...Inner body space 171 ... First loading section 172...Second loading section 180...Refeeding section 190...Inverted section 204 ... Drive gear (butting member) 205a, 205b ... bearings (support members) 206 ... Guide member (support member) 207 ...Pressing member 209 ...Pressed member 210 ... Engagement member (butting member) 300...Image reading unit

Claims

1. An image forming apparatus including: an image forming unit; a re-feeding unit that feeds a sheet on which an image has been formed by the image forming unit again to the image forming unit; and an inverting unit that inverts the sheet on which an image has been formed by the image forming unit and transports it to the re-feeding unit, The inverting section is a reversing roller that rotates forward or backward to convey the sheet; a helical gear provided on the shaft of the reversing roller, which rotates forward or backward together with the rotation of the reversing roller; a pressing member that presses the reversing roller in the axial direction; An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, further comprising a switching member provided between the image forming unit and the reversing roller, the switching member being switchable between a first position where the sheet on which the image has been formed by the image forming unit is guided to the reversing roller, and a second position where the sheet inverted and transported by the reversing roller is guided to the re-feeding unit.

3. 2. The image forming apparatus according to claim 1, wherein the reversing roller also serves as a discharge roller for discharging the sheet to the outside of the apparatus.

4. an image reading unit that is provided above the image forming unit across an internal space and that reads an image of a document; a stacking unit disposed in the internal space formed between the image forming unit and the image reading unit, for stacking sheets on which images have been formed and which have been discharged; a discharge roller for discharging the sheet on which the image is formed to the stacking portion; and 2. The image forming apparatus according to claim 1, wherein the reverse roller also serves as the discharge roller.

5. 2. The image forming apparatus according to claim 1, wherein the reversing roller has an abutting member that is abutted against by the pressing force of the pressing member.

6. 6. The image forming apparatus according to claim 5, wherein the helical gear also serves as the abutting member.

7. 6. The image forming apparatus according to claim 5, wherein the abutting member is abutted against a support member that supports the reversing roller by a pressing force of the pressing member, thereby restricting axial movement of the reversing roller.

8. 2. The image forming apparatus according to claim 1, wherein the pressing force of the pressing member is set to be greater than the axial moving force acting on the reversing roller when the reversing roller rotates.

9. 2. The image forming apparatus according to claim 1, wherein the pressing member presses an end of the shaft of the reversing roller in the axial direction.

10. 2. The image forming apparatus according to claim 1, wherein the pressing member presses a thrust end surface of the helical gear in the axial direction.

11. a pressed member provided on the reversing roller and provided on the other shaft end opposite to the one shaft end on which the helical gear is provided, 2. The image forming apparatus according to claim 1, wherein the pressing member presses the pressed member in an axial direction.

Images