Image forming apparatus

Abstract

Disclosed is an image forming apparatus including: an image forming portion for forming an image on a sheet; a re-feeding section for re-feeding the sheet on which the image is formed by the image forming section to the image forming section; and a reversing portion for reversing the sheet on which the image is formed by the image forming portion and for conveying the reversed sheet to the refeeding portion. The reversing portion includes: a reversing roller for conveying the sheet while rotating in a forward direction, and thereafter conveying the sheet while rotating in a reverse direction by reversing a conveying direction of the sheet; a helical gear provided on a shaft of the reversing roller, the helical gear rotating together with the reversing roller to transmit the driving force to the reversing roller; and a pressing member for pressing the reversing roller in the axial direction.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus for forming an image on a sheet. Background Art

[0002] In an electrophotographic image forming apparatus, a latent image formed on an image bearing member in an image forming section is developed to visualize it. The visualized image is then transferred to a sheet fed into the image forming section. The transferred image is then fixed using heat and pressure in a fixing device. As a result, an image is formed on the sheet. The sheet, to which the image has been fixed in the fixing device, is discharged to the outside of the apparatus via discharge rollers.

[0003] Japanese Patent Application Laid-Open No. 2018-200437 discloses an image forming apparatus in which, when duplex printing is performed on a sheet, a sheet having an image formed on one surface by a fixing device is reversely conveyed by a reverse roller via a duplex conveyance path to an image forming portion. An image is then formed on the other surface of the sheet through a transfer process and a fixing process. The sheet, with images formed on both sides, is discharged to the outside of the apparatus by discharge rollers.

[0004] However, in the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2018-200437, when performing duplex printing, the reversing roller rotates forward to convey the sheet a constant distance toward the outside of the apparatus, and then rotates reversely to convey the sheet through the duplex conveying path. Summary of the Invention

[0005] An object of the present invention is to provide an image forming apparatus capable of suppressing displacement of a reversing roller in the axial direction between cases of forward rotation and reverse rotation.

[0006] Representative configurations of image forming apparatuses include:

[0007] an image forming portion configured to form an image on a sheet;

[0008] a re-feeding portion configured to feed the sheet on which the image has been formed by the image forming portion again to the image forming portion; and

[0009] a reversing portion configured to reverse the sheet on which the image has been formed by the image forming portion and convey the reversed sheet to the re-feeding portion,

[0010] The reversal part includes:

[0011] a reversing roller configured to convey the sheet while rotating in a forward direction and thereafter convey the sheet by reversing the conveying direction of the sheet while rotating in a reverse direction;

[0012] a helical gear provided on a shaft of the counter roller, the helical gear being configured to rotate together with the counter roller to transmit a driving force to the counter roller; and

[0013] A pressing member is configured to press the reverse roller in an axial direction.

[0014] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a diagram showing a cross-sectional view of the image forming apparatus.

[0016] Figure 2 is a diagram showing a plan view of the reverse roller during forward rotation.

[0017] Figure 3 is a diagram showing a plan view of the reversing roller during reverse rotation.

[0018] Figure 4 It is a diagram showing a plan view of the reverse roller.

[0019] Figure 5 It is a diagram showing a plan view of the reverse roller.

[0020] Figure 6 It is a diagram showing a plan view of the reverse roller.

[0021] Figure 7A 、 Figure 7B and Figure 7C It is a diagram showing a perspective view of the reverse roller. DETAILED DESCRIPTION

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the sizes, materials, shapes, and relative positions of the components of the image forming apparatus described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions, and the following description is not intended to limit the scope of the present invention only thereto.

[0023] <Image Forming Apparatus>

[0024] Will refer to Figure 1 An image forming apparatus according to an embodiment of the present invention is described. Figure 1 is a schematic diagram illustrating a cross-sectional view of the image forming apparatus. Figure 1The illustrated image forming apparatus 100 is exemplified as an image forming apparatus of an intermediate transfer tandem system in which four image forming portions 140 for four colors are arranged side by side on an intermediate transfer belt 145 .

[0025] The image forming apparatus 100 is provided with an image forming portion 140, a re-feeding portion 180 that feeds the sheet S on which the image has been formed by the image forming portion 140 to the image forming portion 140 again, and a reversing portion 190 that reverses and conveys the sheet S on which the image has been formed by the image forming portion 140 to the re-feeding portion 180.

[0026] The sheets S are stacked and accommodated in an accommodating portion such as a box, which is provided at the lower portion of the image forming apparatus. The sheets S accommodated in the accommodating portion are fed by the sheet feeding portion 110 in synchronization with image formation by the image forming apparatus. The sheets S fed by the sheet feeding portion 110 are conveyed to the skew feed correction device 120. After the skew feed correction and timing correction are performed on the sheets S by the skew feed correction device 120, the sheets S are conveyed to the secondary transfer portion 130. The secondary transfer portion 130 is composed of a secondary transfer inner roller 131 and a secondary transfer outer roller 132, which are opposed to each other with the intermediate transfer belt 145 interposed therebetween. The secondary transfer portion 130 transfers the toner image formed on the intermediate transfer belt 145 onto the sheet S by applying a predetermined pressure and an electrostatic load bias to the sheet S while clamping and conveying the sheet S.

[0027] Next, we will describe the process of forming an image sent to the secondary transfer section 130 while the sheet S is being conveyed to the secondary transfer section 130 through the aforementioned conveying process. The image forming section 140 primarily comprises a photoreceptor 141, an exposure device 142, a developing device 143, and a primary transfer device 144. The surface of the photoreceptor 141 has been uniformly charged in advance by a charging unit (not shown). Light emitted by the exposure device 142 in accordance with an image information signal forms an electrostatic latent image on the charged photoreceptor 141. This light reaches the photoreceptor 141 via an appropriate diffraction element. The electrostatic latent image formed on the photoreceptor 141 in this manner is developed by the developing device 143, forming a toner image on the photoreceptor 141. At the primary transfer section, where the photoreceptor 141 and the primary transfer device 144 face each other, the primary transfer device 144 applies a predetermined pressure and electrostatic charge bias to the toner image formed on the photoreceptor 141, and the toner image is transferred to the intermediate transfer belt 145.

[0028] Provides four colors: yellow Y, magenta M, cyan C, and black Bk Figure 1The image forming apparatus shown has an image forming portion 140. The image forming portions 140 for four colors are arranged side by side on an intermediate transfer belt 145.

[0029] Next, the intermediate transfer belt 145 will be described. The intermediate transfer belt 145 is wound around a plurality of rollers and is driven to move along the Figure 1 The image forming section 140 rotates in the direction indicated by the arrow in the middle. Consequently, parallel processing is performed by the image forming section 140 for the four colors: yellow Y, magenta M, cyan C, and black Bk. While the toner images are superimposed on the upstream toner images that have been primarily transferred to the intermediate transfer belt 145, the image forming process for the corresponding colors is performed in the primary transfer section of the image forming section 140. Consequently, a full-color toner image is ultimately formed on the intermediate transfer belt 145 and then conveyed to the secondary transfer section 130.

[0030] Through the above-described process of conveying the sheet S and the above-described process of forming an image, the full-color toner image is secondarily transferred onto the sheet S at the secondary transfer portion 130. Thereafter, the sheet S is conveyed to the fixing device 150. The fixing device 150 fixes the toner image on the sheet S by applying a predetermined pressure with opposing rollers or belts and by applying a heating effect, typically caused by a heat source such as a heater, to the sheet S.

[0031] The sheet S having the fixed image obtained in this manner is placed in Figure 1 The first switching flapper 151 in the position shown by the solid line is guided toward the first eject roller 161 and ejected by the first eject roller 161 onto the first stacking portion 171. Alternatively, the sheet S is switched to Figure 1 The first switching flapper 151 in the position shown by the middle dashed line is guided upward and is conveyed toward the second eject roller 162 .

[0032] The sheet S conveyed toward the second eject roller 162 is in Figure 1 The second switching flapper 152 at the position indicated by the middle dashed line is guided toward the second eject roller 162 and ejected by the second eject roller 162 onto the second stacking portion 172 provided above the first stacking portion 171 .

[0033] In the case of duplex printing, after the rear end of the sheet S passes through the second switching flapper 152, the second eject roller 162 rotates in the reverse direction. In this reverse operation of the second eject roller 162, the sheet S is switched to Figure 1 The second switching flapper 152 in the position indicated by the solid line guides toward the re-feeding portion 180. That is, in the case of duplex printing, the sheet S on which an image has been formed by the image forming portion 140 is reversely conveyed by the reversing portion 190 to the re-feeding portion 180, and is conveyed again to the image forming portion 140 by the re-feeding portion 180.

[0034] The sheet S is then conveyed via the re-feeding portion 180 and further conveyed to the image forming portion 140 (second transfer portion 130) by the skew feed correction device 120. An image is formed on the second surface in the same manner as on the first surface. The sheet S, with images formed on both the first and second surfaces, is ejected onto the first stacking portion 171 or the second stacking portion 172.

[0035] The first and second stacking portions 171 and 172 on which the discharged sheets S are stacked have inclined surfaces rising from upstream to downstream in the discharge direction of the sheets S. Therefore, the discharged sheets S can be aligned to the upstream side in the discharge direction due to their own weight.

[0036] <Reversal part>

[0037] Next, the reversing portion 190 will be described in detail. The reversing portion 190 has reversing rollers (second eject rollers 162) that convey the sheet in forward rotation or reverse rotation, and a second switching flapper 152 as a switching member.

[0038] In this embodiment, the second discharge roller 162 that discharges the sheet S to the outside of the apparatus also serves as a reverse roller. However, the present invention is not limited to this configuration. A reverse roller may be provided separately from the discharge roller that discharges the sheet S to the outside of the apparatus.

[0039] Figure 1 The image forming apparatus shown is provided with an image reading portion 300 that reads an image on an original document positioned above the image forming portion 140 via a space 170 formed inside the apparatus. A first stacking portion 171 and a second stacking portion 172 are provided in the space 170 formed between the image forming portion 140 and the image reading portion 300. A second discharge roller 162, which discharges a sheet having an image formed thereon onto the second stacking portion 172, serves as a reverse roller.

[0040] The second switching flapper 152 is provided between the image forming portion 140 and the second discharge roller 162 as a reverse roller. The second switching flapper 152 is a switching member that switches between a first position and a second position different from the first position. In this embodiment, the first position (by Figure 1 The second position (shown by the dashed line) is used to guide the sheet on which the image has been formed by the image forming portion 140 to the second discharge roller 162, and the second position (shown by the dashed line) is used to guide the sheet on which the image has been formed by the image forming portion 140 to the second discharge roller 162. Figure 1 The sheet S (shown by a solid line) is used to guide the sheet S reversely conveyed by the second discharge roller 162 as a reversing roller to the re-feeding portion 180.

[0041] The second discharge roller 162 as the reverse roller receives the driving force from the motor 201 as the driving force for forward rotation or reverse rotation. Figure 2 and Figure 3 The second eject roller 161 is described in detail. Figure 2 and Figure 3 16 is a diagram illustrating the vicinity of second discharge roller 162 of image forming apparatus 100 . Figure 2 16 is a diagram showing how the second discharge roller 162 conveys the sheet S before the sheet S is reversed. Figure 3 16 is a diagram showing how the second discharge roller 162 conveys the sheet S after the sheet S is reversed.

[0042] like Figure 2 and Figure 3 As shown, the second eject roller 162 has a drive gear 204. The drive gear 204 is provided on one end portion of the shaft of the second eject roller 162. The drive gear 204 meshes with the second eject roller 162 in the rotational direction, so that the drive gear 204 and the second eject roller 162 rotate simultaneously. The drive gear 204 is provided with an engaging portion 204a, and the second eject roller 162 is provided with a roller groove 162a for engaging with the engaging portion 204a in the thrust direction. In other words, the engaging portion 204a of the drive gear 204 meshes with the roller groove 162a of the second eject roller 162 in the thrust direction, so that the second eject roller 162 moves synchronously with the drive gear 204 in the thrust direction.

[0043] The motor gear 202 connected to the motor 201 meshes with the gear 203, and the gear 203 meshes with the driving gear 204 of the second discharge roller 162. With this configuration, the power of the motor 201 is sequentially transmitted through the gear 202, the gear 203, and the gear 204. The second discharge roller 162 rotates forward or reverse when receiving the driving force of the motor 201.

[0044] The driving gear 204 of the second eject roller 162 is a helical gear. The helical driving gear 204 is provided on the shaft of the second eject roller 162 so that the helical driving gear 204 and the second eject roller 162 can rotate in a forward or reverse direction. Figure 2 As shown, a thrust acts on the second eject roller 162 rotating in the forward direction between the driving gear 204 and the gear 203 in the forward direction in the direction indicated by the arrow C from one end side toward the other end side in the axial direction. Figure 3 As shown, a thrust acts on the second discharge roller 162 that rotates counter-rotating between the drive gear 204 and the gear 203 in the direction indicated by arrow C′ from the other end side toward the one end side in the axial direction.

[0045] In the above description, drive gear 204 is illustrated as a helical gear that generates thrust acting on the roller rotating in the forward direction indicated by arrow C, and generates thrust acting on the roller rotating in the reverse direction indicated by arrow C'. However, the present invention is not limited to this configuration. Depending on the inclination of the gear teeth of the helical gear with respect to the direction of rotation, the directions of the thrust acting on the roller can be opposite.

[0046] Next, a description will be given of a case where the second eject roller 162 rotates in the direction indicated by arrow A and the sheet S is conveyed in the direction indicated by arrow B. The second eject roller 162 rotates forward in the direction indicated by arrow A and conveys the sheet S in the direction indicated by arrow B toward the outside of the apparatus, and stops when the trailing end of the sheet S passes through the second switching flapper 152. In this case, the sheet S is conveyed from the dotted-line position S1 to the solid-line position S2 where it stops.

[0047] The direction and strength of the thrust acting on the second eject roller 162 may vary depending on the configuration of the gears and the shape of the conveyed sheet S. Hereinafter, it is assumed that when the second eject roller 162 rotates forward in the direction indicated by arrow A, a thrust acts on the second eject roller 162 in the direction indicated by arrow C. When the second eject roller 162 moves a distance dx in the axial direction due to the thrust C, the sheet S is conveyed in the direction indicated by arrow B while also moving a distance dx in the axial direction.

[0048] Next, a case will be described where the second eject roller 162 rotates in the direction indicated by the arrow A' opposite to the arrow A and the sheet S is conveyed in the direction indicated by the arrow B' opposite to the arrow B. The second eject roller 162 rotates in the reverse direction indicated by the arrow A' and conveys the sheet S in the direction indicated by the arrow B' toward the re-feeding portion 180. The sheet S is conveyed from Figure 3 The dotted line position S2 in the figure is the position where the sheet S stops ( Figure 2 solid line position) is transferred in the reverse direction to the solid line position S3.

[0049] When the sheet is conveyed in the reverse direction, since the rotation direction of the second eject roller 162 is opposite and the conveying direction of the sheet S is also opposite, Figure 2 A thrust C' opposite to the thrust C in the second ejection roller 162 acts on the second ejection roller 162. During the reverse conveyance of the sheet S, when the second ejection roller 162 moves a distance dx' in the axial direction due to the thrust C', the sheet S moves a distance dx' in the axial direction while being conveyed in the direction indicated by the arrow B'. Figure 2 The amount of movement dx of the sheet S in the axial direction to one side is not equal to Figure 3When the sheet S in the reverse conveyor moves by an amount dx' in the axial direction to the other side, the sheet S shifts by a difference (y = dx' - dx) perpendicular to the conveying direction during reverse conveyance. The reversely conveyed sheet S is re-fed to the image forming section 140, where printing is performed on the second surface. In this case, the image on the second surface is positionally displaced by a difference (y = dx' - dx) in the axial direction relative to the image on the first surface. This image shift of the difference y may degrade the quality of the printed product. In other words, due to the reaction force between the sheet and the gear, a force is applied to the reverse roller, causing it to shift in the axial direction (thrust direction) perpendicular to the sheet conveying direction, causing the reverse roller's thrust position to change between forward and reverse rotation. The difference in the thrust direction movement of the reverse roller between forward and reverse rotation causes the relative position of the first and second surfaces of the sheet to shift in the main scanning direction, resulting in degraded print quality.

[0050] In view of this, if Figure 4 As shown, the second eject roller 162 is pressed in the axial direction (thrust direction) by the pressing member 207. That is, the reversing portion 190 has the pressing member 207 that presses the second eject roller 162 as the reversing roller in the axial direction. Figure 4 1 is a diagram showing a plan view of the second discharge roller 162 serving as a reverse roller.

[0051] The pressing member 207 abuts on one end portion of the shaft of the second discharge roller 162 as the reverse roller, and presses the second discharge roller 162 from one end side to the other end side in the axial direction. Figure 4 As shown, the pressing member 207 is illustrated as a pressing member pressed from one side to the other side in the axial direction by the urging member 208 such as a coil spring. However, the configuration of the pressing member is not limited to this configuration.

[0052] The second eject roller 162 is rotatably supported by bearings 205 a and 205 b located on both sides in the axial direction outside a conveying area for the sheet S, wherein the roller portion that comes into contact with the sheet S is provided in the conveying area. The bearings 205 a and 205 b are attached to a guide member 206 that serves as a supporting member supporting the second eject roller 162 .

[0053] The pressing member 207 that presses the second eject roller 162 in the axial direction (thrust direction) is configured so that the pressing force R in the axial direction is greater than the thrust C. That is, the pressing force R of the pressing member 207 is set to be greater than the moving force (thrust C) that acts on the second eject roller 162 in the axial direction during the forward rotation of the second eject roller 162. Due to this pressing force R, the drive gear 204 abuts against the bearing 205 a, thereby restricting the movement of the second eject roller 162 in the axial direction and positioning the second eject roller 162 in the thrust direction.

[0054] The second discharge roller 162 as the reverse roller has a contact member that contacts the guide member 206 (bearing 205 a ) by the pressing force R of the pressing member 207 . Figure 4 In the illustrated configuration, the driving gear 204 provided on one end portion of the shaft of the second discharge roller 162 serves as an abutting member that abuts against the guide member 206 (bearing 205 a ) as a supporting member.

[0055] In addition, if Figure 4 As shown, the drive gear 204, serving as an abutting member, abuts against the bearing 205a, serving as a support member (which supports the second discharge roller 162, serving as the counter roller), through the pressing force of the pressing member 207. This restricts axial movement of the second discharge roller 162 and positions the second discharge roller 162 in the axial direction. The bearing 205a is provided on the guide member 206, serving as the support member for the second discharge roller 162, to rotatably support the shaft of the second discharge roller 162. The guide member 206, serving as the support member, and the bearing 205a provided on the guide member 206 do not move in the axial direction. Therefore, the second discharge roller 162, serving as the counter roller, is positioned in the axial direction due to the abutment of the drive gear 204, serving as the abutting member, against the bearing 205a, serving as the support member, through the pressing force of the pressing member 207.

[0056] like Figure 4 As shown, since the drive gear 204 abuts against the bearing 205 a, even if the second discharge roller 162 rotates forward in the direction indicated by arrow A to convey the sheet S in the direction indicated by arrow B, the movement of the second discharge roller 162 in the axial direction is restricted. Therefore, during the conveyance of the sheet S in the direction indicated by arrow B, the movement amount dx of the second discharge roller 162 in the axial direction becomes zero, and the movement amount (displacement amount) of the sheet S in the axial direction also becomes zero.

[0057] The configuration of the abutment member is not limited to Figure 4 One configuration shown, and for example, the abutment member may be as Figure 5 Configuration shown.

[0058] like Figure 5As shown, the second ejection roller 162 serving as a reversing roller may be configured to have a coupling member 210 separated from the driving gear 204 as an abutting member. A roller groove 162b is provided on the second ejection roller 162 that engages with the coupling member 210 in the thrust direction. That is, the coupling member 210 engages with the roller groove 162b of the second ejection roller 162 in the thrust direction, so that the coupling member 210 and the second ejection roller 162 move in conjunction with each other in the thrust direction. The coupling member 210 is provided on the other end side of the shaft of the second ejection roller 162. The coupling member 210 abuts against the guide member 206 serving as a supporting member by the pressing force of the pressing member 207, and engages with the guide member 206 in the axial direction.

[0059] like Figure 5 As shown, engaging member 210, serving as an abutting member, abuts guide member 206, serving as a supporting member (which supports second eject roller 162, serving as a reverse roller), by the pressing force of pressing member 207, thereby restricting axial movement of second eject roller 162 and positioning second eject roller 162 in the axial direction. As described above, as long as engaging member 210, which engages with second eject roller 162 in the thrust direction, abuts guide member 206, drive gear 204 does not need to abut bearing 205a.

[0060] Next, refer to Figure 6 , a case where the second discharge roller 162 rotates in the direction indicated by arrow A′ and the sheet S is conveyed in the reverse direction indicated by arrow B′ will be described. Figure 6 1 is a diagram showing a plan view of the second discharge roller 162 serving as a reverse roller.

[0061] and Figure 4 Similar to the case shown, the second eject roller 162 is pressed in the axial direction (thrust direction) by the pressing member 207. Figure 4 Similar to the case shown, the pressing member 207 that presses the second ejection roller 162 in the axial direction (thrust direction) is configured so that the pressing force R in the axial direction is greater than the thrust C'. That is, the pressing force R of the pressing member 207 is set to be greater than the moving force (thrust C') acting on the second ejection roller 162 in the axial direction during the reverse rotation of the second ejection roller 162. Figure 6 In the illustrated case, the direction of the pressing force R of the pressing member 207 is opposite to the direction of the moving force (thrust force C′) acting on the second discharge roller 162 in the axial direction.

[0062] like Figure 6As shown, even when second eject roller 162 rotates in the reverse direction indicated by arrow A' to reversely convey sheet S in the direction indicated by arrow B', pressing force R is greater than thrust force C', thus restricting axial movement of second eject roller 162 and positioning it in the axial direction. Therefore, during reverse conveyance of sheet S in the direction indicated by arrow B', the axial movement amount dx' of second eject roller 162 becomes zero, and the axial movement amount (displacement) of sheet S also becomes zero. This configuration suppresses displacement between the first and second surfaces of sheet S in the axial direction (thrust direction) even during duplex printing.

[0063] As described above, in this embodiment, the displacement in the axial direction between the forward rotation and the reverse rotation of the second eject roller 162 as the reversing roller can be suppressed, thereby reducing the position displacement of the sheet S caused by the displacement of the second eject roller 162 in the axial direction.

[0064] Figure 7A 、 Figure 7B and Figure 7C 1 is a diagram showing a perspective view of the second discharge roller as a reverse roller. Next, a pressing configuration of the second discharge roller 162 (reverse roller) using the pressing member 207 will be described.

[0065] Figure 7A It shows Figure 4 and Figure 6 FIG. 1 is a diagram of the pressing configuration of the reverse roller shown in FIG. Figure 7A As shown, the pressing member 207 is pressed by the pushing member 208, so that the pressing member 207 presses the shaft end portion of the second discharge roller 162 as the reverse roller from one side to the other side in the axial direction. However, the pressing configuration of the reverse roller is not limited to this configuration. The pressing configuration of the reverse roller may be Figure 7B A configuration shown can also be Figure 7C One configuration shown.

[0066] exist Figure 7B In the illustrated case, the pressing member 207 presses the thrust end surface of the driving gear 204 from one side to the other side in the axial direction. In this way, the pressing member 207 applies a pressing force R to the second discharge roller 162 as the reverse roller.

[0067] Alternatively, in Figure 7C In the illustrated case, the second discharge roller 162 as the reverse roller is provided with a pressing force receiving member 209 at the other axial end portion opposite to the one axial end portion provided with the drive gear 204. The pressing member 207 presses the pressing force receiving member 209 from one side to the other side in the axial direction.

[0068] This configuration is suitable for a case where there is not enough space near the drive gear 204 to provide the pressing member 207. In this case, a pressing force receiving member 209 engaged with the second discharge roller 162 as a reverse roller is added, and another pressing member 207 provided near the pressing force receiving member 209 presses the pressing force receiving member 209 to obtain the same effect.

[0069] The pressing member 207 is illustrated as pressing the second discharge roller 162, which serves as the reverse roller, from one side to the other side in the axial direction. However, the configuration of the pressing member 207 is not limited to this configuration. The pressing member 207 may press the second discharge roller 162, which serves as the reverse roller, from the other side to the one side in the axial direction. With this configuration, the same effect can be achieved.

[0070] According to the present invention, the displacement of the reversing roller between during forward rotation and during reverse rotation can be suppressed, so that the positional displacement of the sheet caused by the displacement of the reversing roller in the axial direction can be reduced.

[0071] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

[0072] This application claims the benefit of Japanese Patent Application No. 2024-048093, filed March 25, 2024, which is hereby incorporated by reference herein in its entirety.

Claims

1. An image forming apparatus comprising: an image forming portion configured to form an image on a sheet; a re-feeding portion configured to feed again, to the image forming portion, a sheet on which an image has been formed by the image forming portion; as well as a reversing portion configured to reverse a sheet on which an image has been formed by the image forming portion and convey the reversed sheet to the re-feeding portion, The reversal portion includes: a reversing roller configured to convey the sheet while rotating in a forward direction and then convey the sheet by reversing the conveying direction of the sheet while rotating in a reverse direction; a helical gear provided on the shaft of the reverse roller, the helical gear being configured to rotate together with the reverse roller to transmit a driving force to the reverse roller; and A pressing member is configured to press the reverse roller in an axial direction.

2. The image forming apparatus according to claim 1 , further comprising: a switching member provided between the image forming portion and the reversing roller, the switching member being configured to switch to a first position in which the switching member guides a sheet on which an image has been formed by the image forming portion to the reversing roller, and a second position in which the switching member guides a sheet reversed and conveyed by the reversing roller to the re-feeding portion.

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

4. The image forming apparatus according to claim 1 , further comprising: an image reading portion disposed above the image forming portion across a space in the image forming apparatus, the image reading portion configured to read an image of a document; a stacking portion provided in a space formed between the image forming portion and the image reading portion, the stacking portion configured to stack discharged sheets on which images have been formed; as well as a discharge roller configured to discharge the sheet on which the image has been formed to the stacking portion, The reverse roller serves as the discharge roller.

5. The image forming apparatus according to claim 1, The reverse roller includes a contact member that is brought into contact by the pressing force of the pressing member.

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

7. The image forming apparatus according to claim 5, The abutment member abuts against a support member configured to support the reverse roller by the pressing force of the pressing member, thereby restricting movement of the reverse roller in the axial direction.

8. The image forming apparatus according to claim 7, further comprising: a bearing configured to rotatably support the counter roller, The abutment member abuts against the support member via the bearing by the pressing force of the pressing member, thereby restricting movement of the reverse roller in the axial direction.

9. The image forming apparatus according to claim 1, wherein a pressing force of the pressing member is set to be greater than a moving force in the axial direction acting on the reverse roller during rotation of the reverse roller.

10. The image forming apparatus according to claim 1, wherein the pressing member is configured to press a shaft end portion of the reverse roller in the axial direction.

11. The image forming apparatus according to claim 1, wherein the pressing member is configured to press a surface of the thrust end portion of the helical gear in the axial direction.

12. The image forming apparatus according to claim 1, further comprising: a pressing force receiving member provided on one shaft end portion of the reverse roller, the one shaft end portion being opposite to the other shaft end portion on which the helical gear is provided, wherein the pressing member is configured to press the pressing force receiving member in the axial direction.

13. The image forming apparatus according to claim 1, The pressing member includes a spring.

Images