JP5164495B2 - Sheet conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus, and more particularly to an apparatus in which a sheet on which an image is formed is conveyed again to an image forming unit.

  Conventionally, in image forming apparatuses such as printers, copiers, and fax machines, in addition to a mode in which an image is formed on one side (first side) of a sheet, an image is formed on the back side (second side) of a sheet on which an image is formed on one side. Some have a double-sided mode to form Further, such an image forming apparatus includes a sheet conveying device, and in the double-sided mode, the sheet conveying device forms an image on the back surface of the sheet on which an image is formed on one side by the image forming unit. Is reversed and conveyed again to the image forming unit.

  FIG. 13 is a diagram showing a schematic configuration of such a conventional image forming apparatus. In this image forming apparatus, in the duplex mode, first, the sheet P is conveyed from the paper feed cassette 17 or the manual feed tray 20 to the secondary transfer unit 34. Then, in the secondary transfer unit 34, the toner image formed by the image forming unit 1 and then primary-transferred onto the intermediate transfer belt 8 is transferred to the sheet P. The sheet on which the toner image has been transferred in this manner is then pressed and heated by the fixing device 16 to fix the toner image.

  Next, the sheet P on which the toner image is fixed on one side is conveyed to the sheet discharge tray 22 side by the normal rotation of the discharge roller 21 driven by a motor M capable of forward and reverse rotation. Thereafter, before the trailing edge of the sheet P passes through the discharge roller 21, the sheet P is sent to the double-sided conveyance path 24 by rotating the discharge roller 21 in the reverse direction by rotating the motor M in the reverse direction.

  Next, the sheet P joins from the double-sided conveyance path 24 to the conveyance path 18 located upstream of the sheet feeding cassette 17 and the manual feed tray 20 in the sheet conveyance direction. Thereafter, the sheet P is conveyed to the secondary transfer unit 34 by the registration roller 19 in accordance with the timing when the leading edge of the toner image on the intermediate transfer belt reaches the secondary transfer unit 34, and the toner image is transferred to the back surface. . Then, the sheet P having the toner image transferred to the back surface in this way is fixed again by the fixing device 16 and then discharged to the discharge tray 22 by the discharge roller 21 that rotates forward.

  By the way, in the conventional image forming apparatus, when the image is formed on both sides of the sheet, the discharge roller 21 is reversely driven by the reverse drive device including the motor M such as a stepping motor capable of forward and reverse rotation. I am doing so. However, in recent years, a cheaper reversal drive device that does not use a dedicated motor such as a stepping motor has been proposed due to cost reduction demands required for the device (see Patent Document 1).

  FIG. 14 is a diagram showing an example of a reversing drive device that reversibly drives the discharge roller 21 without using such a stepping motor or the like. As shown in FIGS. 14A and 14B, this reverse drive device is composed of two planetary gear clutch mechanisms 70 (70A, 70B), a drive input gear 72, a drive output gear 73, and a switching lever 74. ing.

  Here, the planetary gear clutch mechanism 70 includes a sun gear member 81, two planetary gears 82 (82a, 82b), a planetary gear holding member 83, an internal gear, as shown in FIGS. It is comprised from the attached member 84 grade | etc.,.

  The sun gear member 81 has a gear portion 81a and a restraining portion 81b for restricting the rotation of the sun gear member 81 on the same axis. The two planetary gears 82a and 82b are rotatably held by boss portions 83a and 83b provided on the planetary gear holding member 83. Further, the outer peripheral surface of the planetary gear holding member 83 that holds the planetary gears 82 a and 82 b is provided with a gear tooth surface 83 c coaxial with the sun gear member 81.

  The internal gear member 84 is provided so as to be rotatable coaxially with the planetary gear holding member 83, and includes an internal gear 84 a that meshes with the planetary gears 82 a and 82 b, and a gear tooth surface 84 b on the outer peripheral surface.

  Next, the operation of the planetary gear clutch mechanism 70 having such a configuration will be described.

  For example, when the planetary gear holding member 83 rotates in a state where the restraining portion 81b of the sun gear member 81 is restrained by a restraining means (not shown), the planetary gear 82 that is rotatably held by the planetary gear holding member 83 also rotates. To do. In this case, since the sun gear member 81 does not rotate, the rotation of the planetary gears 82a and 82b is transmitted to the internal gear 84a of the internal gear member 84, thereby rotating the internal gear member 84. To do.

  On the other hand, when the rotation restriction of the restricting portion 81 b is released and the sun gear member 81 is rotatable, in this case, the rotation of the planetary gear holding member 83 is transmitted only to the sun gear member 81 via the planetary gear 82. As a result, the sun gear member 81 rotates and the internal geared member 84 is rotatable with respect to the planetary gear member 81.

  In other words, when the sun gear member 81 is restricted in rotation and in the stopped state, the planetary gear holding member 83 and the internal geared member 84 are in a driving connection state, and when the sun gear member 81 is rotatable, the planetary gear is The drive connection between the holding member 83 and the internal geared member 84 is released.

  Here, in the reverse drive device shown in FIG. 14, the outer peripheral gear surfaces 83c of the planetary gear holding members 83 (83A, 83B) of the two planetary gear clutch mechanisms 70 (70A, 70B) are engaged with each other.

  The switching lever 74 is connected to the solenoid 71, and can be locked to the restraining portions 81a of the sun gear members 81A and 81B of the planetary gear clutch mechanisms 70A and 70B by energization control of the solenoid 71. The clutching operation of the planetary gear clutch mechanisms 70A and 70B can be selectively performed by the position of the switching lever 74.

  In FIG. 14, the driving input gear 72 is driven from a driving source (not shown) in a constant rotational direction (in the direction of arrow A), and the driving output gear 73 is a member with internal gears of both the planetary clutch mechanisms 70A and 70B. The state which has meshed | engaged with the outer periphery gear part of 84A and 84B is shown. Moreover, the switching lever 74 has shown the state which has controlled rotation of the sun gear member 81A of the planetary gear clutch mechanism 70A.

  In this case, the driving force input from the drive input gear 72 is transmitted to the planetary gear holding member 83B, the planetary gear holding member 83A, and the internal geared member 84B, and the drive output gear 73 rotates in the direction of arrow B in the figure. . At this time, the member 84B with the internal gear meshing with the drive output gear 73 is rotatable, and therefore does not participate in the rotation of the drive output gear 73.

  On the other hand, when the switching lever 74 connected to the solenoid 71 regulates the rotation of the sun gear member 81B, the driving force input from the drive input gear 72 is the planetary gear holding member 83B, the internal geared member. 84B is transmitted, and the drive output gear 73 rotates in the direction of arrow C. At this time, the internal geared member 84 </ b> A meshing with the drive output gear 73 is rotatable, and therefore does not participate in the rotation of the drive output gear 73.

  That is, the rotation direction of the drive output gear 73 (arrow B in the figure) is switched by switching the switching lever 74 by turning the solenoid 71 on and off with respect to the drive input gear 72 to which the drive in the constant rotation direction (arrow A direction in the figure) is applied. Direction, C direction) can be selected. By providing the reversing drive device with such a configuration, if the rotation in a certain direction is given to the drive input gear 72 from the other drive system in the device, the discharge roller does not have a dedicated motor. Thus, the forward / reverse rotation control 21 can be performed.

JP 2000-199610 A

  Incidentally, in recent years, sheet conveying apparatuses and image forming apparatuses are required to further reduce the size of the apparatus, reduce costs, improve reliability, and improve the variety of usable sheet sizes. Here, when a sheet having a long length in the sheet conveyance direction is used, the length of the sheet conveyance path becomes long. However, the length of the sheet conveyance path inevitably becomes short due to a demand for downsizing of the apparatus.

  However, when the toner image is transferred to the sheet P in the image forming apparatus shown in FIG. 13, the toner image on the intermediate transfer belt 8 is moved to the secondary transfer portion 34 as described above in accordance with the timing. The sheet P must be fed by the registration roller 19. For this reason, after the registration roller 19 is temporarily stopped, the sheet P is restarted at the same timing to match the image.

  Here, when the double-sided image is formed and the sheet length is longer than the distance from the discharge roller 21 to the registration roller 19, when the registration roller 19 is temporarily stopped, the discharge roller 21 is stopped synchronously, or It is necessary to turn off the driving of the discharge roller 21.

  However, in the reverse drive device using the planetary gear clutch mechanism having the configuration shown in FIGS. 14 and 15 described above, the rotation direction of the discharge roller 21 can be changed, but the discharge roller 21 cannot be stopped. The stop of the registration roller 19 cannot be followed.

  Therefore, in order to stop the discharge roller 21 following the stop of the registration roller 19, it is necessary to stop the other drive system. Certain drive switching cannot be performed.

  In other words, the conventional image forming apparatus including the reversing drive device that drives the discharge roller 21 forward and backward by the planetary gear clutch mechanism cannot perform high-speed and reliable drive switching, and the variety of usable sheet sizes is increased. Cannot be achieved.

  Accordingly, the present invention has been made in view of such a current situation, and provides a sheet conveying apparatus and an image forming apparatus that can perform high-speed and reliable drive switching while suppressing an increase in size and cost of the apparatus. It is intended to provide.

The present invention relates to an image forming unit, a reverse conveying roller capable of normal / reverse rotation that reverses a sheet on which an image is formed and conveys the image to the image forming unit again, and the reverse conveying roller is moved forward by a driving force from a driving unit. In the image forming apparatus including a forward / reverse drive unit that performs reverse drive, the forward / reverse drive unit is disposed between the drive unit and the reverse conveyance roller, and the normal rotation drive force and reverse drive are applied to the reverse conveyance roller. A clutch mechanism for selectively transmitting force, a first switching means for switching a state of the clutch mechanism to a state of transmitting a normal driving force to the reverse conveying roller and a state of not transmitting a driving force, Second switching means for switching the state between a state in which a reverse driving force is transmitted to the reverse conveying roller and a state in which the driving force is not transmitted, the first switching unit and the second switching unit A control unit that controls a switching operation, and the control unit reverses the sheet and conveys the sheet to the image forming unit again, and the state of the clutch mechanism is set to the reverse conveyance roller to apply a normal rotation driving force. The state of transmission is changed from the state of transmission to the state of transmitting the reverse rotation driving force to the reverse conveyance roller, and the driving of the reverse conveyance roller is performed until the trailing edge of the reversed sheet reaches the reverse conveyance roller after the transmission of the reverse rotation driving force. The switching operation of the first and second switching means is controlled so as to stop the transmission of force. Further, the present invention provides an image forming unit, a reversible conveying roller capable of reversing the sheet on which an image is formed and conveyed again to the image forming unit, and the reverse conveying roller by a driving force from a driving unit. A forward / reverse drive unit for driving the forward / reverse drive, wherein the forward / reverse drive unit is disposed between the drive unit and the reverse conveying roller, and includes a first sun gear member, A first planetary gear clutch mechanism having a plurality of planetary gears meshed with one sun gear member, a second sun gear member, and a second planetary gear having a plurality of planetary gears meshed with the second sun gear member A clutch mechanism that selectively transmits a forward driving force and a reverse driving force to the reverse conveying roller; and restricts one rotation of the first sun gear member and the second sun gear member. By The driving force is transmitted to the reverse conveying roller, and the rotation restriction of both the first sun gear member and the second sun gear member is released to stop the transmission of the driving force to the reverse conveying roller. Switching means for switching the state of the clutch mechanism to a state in which a forward driving force is transmitted to the reverse conveying roller, a state in which a reverse driving force is transmitted, and a state in which the driving force is not transmitted, And a control unit for controlling the switching operation .

In addition, the present invention provides a sheet transport comprising a reverse transport roller capable of forward / reverse transport so as to reverse the sheet, and a forward / reverse drive unit for driving the reverse transport roller forward / reversely by a driving force from the drive unit. In the apparatus, a first planetary gear clutch mechanism that is disposed between the drive unit and the reverse conveying roller and has a first sun gear member and a plurality of planetary gears that mesh with the first sun gear member; A second planetary gear clutch mechanism having two sun gear members and a plurality of planetary gears meshing with the second sun gear member, and selectively transmitting a forward drive force and a reverse drive force to the reverse conveying roller. performs a clutch mechanism, the transmission of driving force to the reversing conveyance roller by regulating one rotation of said first sun gear member and said second sun gear member, said first sun The transmission of the driving force to the reverse conveying roller is stopped by canceling the rotation restriction of both the member A and the second sun gear member, so that the state of the clutch mechanism is rotated forward to the reverse conveying roller. state for transmitting the driving force, and the state, and the switching Ru switching Rikae means a state that does not transmit the driving force to transmit the reverse drive force, and a control unit for controlling the switching operation of said switching Rikae means, and kite comprising a It is characterized by.

  In the present invention, the state of the clutch mechanism is changed from a state in which the normal driving force is transmitted to the reverse conveying roller to a state in which the reverse driving force is transmitted to the reverse conveying roller, and further, the transmission of the driving force to the reverse conveying roller is stopped. It can be in a state to do. Thereby, high-speed and reliable drive switching can be performed while suppressing an increase in size and cost of the apparatus.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a full-color image forming apparatus (full-color printer) having an inline-type intermediate transfer belt (intermediate transfer means) in an electrophotographic system according to the first embodiment of the present invention.

  The image forming apparatus 100 includes four image forming stations 1Y, 1M, 1C, and 1Bk that are arranged in a line at regular intervals to form toner images of yellow, magenta, cyan, and black colors. A forming unit 1 is provided.

  Each of the image forming stations 1Y, 1M, 1C, and 1Bk is provided with a photosensitive drum 2 (2a to 2d) that is a drum type electrophotographic photosensitive member as an image carrier. Around each photosensitive drum 2, a primary charger 3 (3a to 3d), a developing device 4 (4a to 4d), a transfer roller 5 (5a to 5d), and a drum cleaner device 6 (6a to 6d) are provided. A laser exposure device 7 is installed below the primary charger 3 and the developing device 4.

  Here, the photosensitive drum 2 is a negatively charged OPC photosensitive member, and has a photoconductive layer on an aluminum drum base. A predetermined driving device (not shown) in the arrow direction (clockwise direction in FIG. 1) is used. Driven at process speed. A primary charger 3 as primary charging means uniformly charges the surface of each photosensitive drum 2 to a predetermined negative potential by a charging bias applied from a charging bias power source (not shown).

  The developing device 4 contains yellow, cyan, magenta and black color toners, and the built-in color toners are attached to the electrostatic latent images formed on the photosensitive drum 2 to develop (possible toner). Visualize). The transfer roller 5 as a primary transfer unit is disposed so as to be in contact with each photosensitive drum 2 via an intermediate transfer belt 8. The drum cleaner device 6 has a cleaning blade or the like for removing from the photosensitive drum 2 residual toner remaining after the primary transfer on the photosensitive drum 2.

  The intermediate transfer belt 8 is stretched between the secondary transfer counter roller 10, the support roller 9, and the tension roller 11, and is rotated in the arrow A direction by a drive input to the secondary transfer counter roller 10. The intermediate transfer belt 8 is made of a dielectric resin such as polycarbonate, polyethylene terephthalate resin film, polyvinylidene fluoride resin film, or the like.

  The secondary transfer counter roller 10 is disposed so as to be in contact with the secondary transfer roller 12 via the intermediate transfer belt 8, and the secondary transfer unit 34 is configured by the secondary transfer counter roller 10 and the secondary transfer roller 12. Is configured. In addition, a belt cleaning device 13 that removes and collects transfer residual toner remaining on the surface of the intermediate transfer belt 8 is installed outside the endless intermediate transfer belt 8 and in the vicinity of the tension roller 11. Further, a fixing device 16 having a fixing roller 16a and a pressure roller 16b is installed on the downstream side and the upper side in the conveyance direction of the sheet P from the secondary transfer unit 34, thereby forming a substantially vertical conveyance path.

  The exposure device 7 includes laser light emitting means for emitting light corresponding to given image information, a polygon lens, a reflection mirror, and the like. Each photosensitive drum charged by the primary charger 3 by exposing the photosensitive drum 2 to the exposure device 7. An electrostatic latent image of each color corresponding to image information is formed on the surface of 2.

  Next, an image forming operation in the image forming apparatus 100 having such a configuration will be described.

  When an image formation start signal is issued, the photosensitive drums 2 of the image forming stations 1Y, 1M, 1C, and 1Bk that are rotationally driven at a predetermined process speed are uniformly charged to the negative polarity by the primary charger 3, respectively. The Then, the exposure device 7 irradiates an externally input color-separated image signal from the laser light emitting element, and forms an electrostatic latent image of each color on the photosensitive drum via a polygon lens, a reflection mirror, and the like. .

  First, yellow toner is adhered to the electrostatic latent image formed on the photosensitive drum 2a by the developing device 4a to which a developing bias having the same polarity as the charging polarity (negative polarity) of the photosensitive drum 2a is applied. Visualize as an image. This yellow toner image is driven by a transfer roller 5a to which a primary transfer bias (positive polarity) opposite in polarity to the toner is applied in a primary transfer portion between the photosensitive drum 2a and the transfer roller 5a. Primary transfer is performed on the intermediate transfer belt 8.

  The intermediate transfer belt 8 onto which the yellow toner image has been transferred is moved to the image forming station 1M side. In the image forming station 1M, similarly to the image forming station 1Y, the magenta toner image formed on the photosensitive drum 2b is superimposed on the yellow toner image on the intermediate transfer belt 8 to perform primary transfer. It is transcribed at the part.

  In the same manner, cyan and black toner images formed on the photosensitive drums 2c and 2d of the image forming stations 1C and 1Bk on the yellow and magenta toner images superimposed and transferred on the intermediate transfer belt 8 are respectively primary. Superimpose sequentially at the transfer section. As a result, a full-color toner image is formed on the intermediate transfer belt 8. When each color toner is transferred to the intermediate transfer belt 8, the transfer residual toner remaining on each photosensitive drum 2 is scraped off and collected by a cleaner blade or the like provided in the drum cleaner devices 6a to 6d. .

  Next, in accordance with the timing at which the front end of the full-color toner image formed on the intermediate transfer belt 8 reaches the secondary transfer unit 34, for example, the sheet P fed from the paper feed cassette 17 through the transport path 18 is registered with the registration rollers. 19 is conveyed to the secondary transfer section 34. Then, a full-color toner image is collectively collected by the secondary transfer roller 12 to which a secondary transfer bias (positive polarity) opposite in polarity to the toner is applied to the sheet P conveyed to the secondary transfer unit 34. Transcribed.

  The sheet P on which the full-color toner image is formed is conveyed to the fixing device 16, and the full-color toner image is heated and pressed at the fixing nip portion between the fixing roller 16 a and the pressure roller 16 b, and the surface of the sheet P Heat-fixed. Thereafter, the sheet on which the image is formed on one side in this manner is discharged onto the discharge tray 22 on the upper surface of the main body by the discharge roller 21, and a series of image forming operations is completed. The secondary transfer residual toner remaining on the intermediate transfer belt 8 is removed and collected by the belt cleaning device 13.

  The image forming apparatus 100 is capable of double-sided image formation, and includes a double-sided conveyance path 24 for conveying a sheet having an image formed on one side to the image forming unit 1 again. When a double-sided image is formed, the sheet on which the image is formed on one side is temporarily conveyed to the sheet discharge tray side by the normal rotation of the discharge roller 21 which is a reverse conveyance roller capable of forward and reverse rotation. That is, in this embodiment, the reverse conveying roller also serves as the discharge roller 21. Thereafter, the switching member (not shown) is switched, and the discharge roller 21 is rotated in the reverse direction before the trailing edge of the sheet P passes through the discharge roller 21, thereby conveying the sheet P to the double-sided conveyance path 24.

  Next, the sheet P merges from the double-sided conveyance path 24 to the conveyance path 18, and thereafter, the secondary transfer is performed by the registration roller 19 in accordance with the timing when the leading edge of the toner image on the intermediate transfer belt reaches the secondary transfer unit 34. The toner image is transferred to the back surface and transferred to the back surface. The sheet P having the toner image transferred to the back surface in this way is fixed again by the fixing device 16 and then discharged to the paper discharge tray 22 by the discharge roller 21.

  By the way, in the present embodiment, when images are formed on both sides of the sheet, the discharge roller 21 is rotated in the forward and backward directions by a reverse drive device as shown in FIG.

  As shown in FIGS. 2 (a) and 2 (b), the reverse drive device 28 includes a clutch mechanism including two planetary gear clutch mechanisms 30 (30A, 30B), two solenoids 31 (31a, 31b), and a drive input gear. 32, a drive output gear 33 and an idler gear 35. The reverse driving device 28 constitutes the sheet conveying device 100A shown in FIG. 1 together with the motor M and the discharge roller 21 shown in FIG.

  Here, the planetary gear clutch mechanism 30 includes a sun gear member 41, two (plural) planetary gears 42 (42a, 42b), a planetary gear holding member 43, and a member 44 with an internal gear as shown in FIG. Has been. The sun gear member 41 has a gear part 41a and a restricting part 41b for restricting rotation on the same axis.

  The two planetary gears 42 a and 42 b are rotatably held by a boss portion 43 a provided on the planetary gear holding member 43, and a gear tooth surface coaxial with the sun gear member 41 is provided on the outer peripheral surface of the planetary gear holding member 43. 43b is formed. The internal geared member 44 is provided so as to be rotatable coaxially with the planetary gear holding member 43, and includes an internal gear 44 a that meshes with the planetary gear 42, and a gear tooth surface 44 b is formed on the outer peripheral surface.

  Next, the operation of the planetary gear clutch mechanism 30 will be described.

  First, driving is input from a driving source (not shown) to a gear tooth surface 44b provided on the outer peripheral surface of the member 44 with an internal gear in a state where the restraining portion 41b of the sun gear member 41 is restrained by a restraining means (not shown). The case will be described.

  In this case, the rotation of the member 44 with the internal gear is transmitted to the planetary gear 42 that is rotatably held by the planetary gear holding member 43 via the internal gear 44a of the member 44 with the internal gear, and the planetary gear 42 is rotated. Rotate. Here, since the sun gear member 41 is restrained, the rotation of the planetary gear 42 is transmitted to the planetary gear holding member 43, and the planetary gear holding member 43 rotates.

  Next, a case where driving is input from a driving source (not shown) to the gear tooth surface 44b provided on the outer peripheral surface of the member 44 with the internal gear in a state where the restraint of the sun gear member 41 is released will be described.

  In this case, the rotation of the member 44 with the internal gear is transmitted to the planetary gear 42 via the internal gear 44 a of the member 44 with the internal gear, and the rotation of the planetary gear 42 is transmitted to the gear portion 41 a of the sun gear member 41. Thereby, only the sun gear member 41 rotates, and the rotation of the planetary gear 42 is not transmitted to the planetary gear holding member 43, so that the planetary gear holding member 43 is rotatable with respect to the member 44 with the internal gear.

  In other words, when the sun gear member 41 is restricted in rotation and in a stopped state, the planetary gear holding member 43 and the internal geared member 44 are in a driving connection state, and when the rotation restriction of the sun gear member 41 is released, the planetary gear is released. The drive connection between the holding member 43 and the internal geared member 44 is released.

  2, the two planetary gear clutch mechanisms 30 (30A, 30B) are configured such that the outer peripheral gear 44b of the internal geared member 44 (44A, 44B) is engaged via the idler gear 35. ing. Further, the outer peripheral gear 43b of the planetary gear holding members 43A and 43B is directly engaged.

  Further, a solenoid (hereinafter referred to as a first solenoid) 31a, which is the first switching means on the first planetary gear clutch mechanism 30A side, can be locked to the restraining portion 41b of the sun gear member 41A when not energized (OFF state). . Further, when energized (ON state), the locking of the sun gear member 41A to the restraining portion 41b is released, and the sun gear member 41A becomes rotatable.

  Similarly, the solenoid (hereinafter referred to as the second solenoid) 31b that is the second switching means on the second planetary gear clutch mechanism 30B side is not energized (OFF state), so that the sun gear member 41B of the planetary gear clutch mechanism 30B is restrained. It can be locked to the portion 41b. Further, when energized (ON state), the locking of the sun gear member 41B to the restraining portion 41b is released, and the sun gear member 41B becomes rotatable.

  In the present embodiment, energization control to the first and second solenoids 31a and 31b is performed independently, whereby the clutching operation of the first and second planetary gear clutch mechanisms 30A and 30B is performed. Can be selectively performed.

  Next, the operation of the inversion driving device 28 having such a configuration will be described.

  Normally, as shown in FIG. 2, a constant rotational direction (in the direction of the arrow A in the figure), that is, driving in one direction is applied from a drive source (not shown) to the drive input gear 32 as a drive input unit. Further, the drive output gear 33 that is a drive output portion meshes with the outer peripheral gear surface 43b of the planetary gear holding member 43B of the second planetary clutch mechanism 30B.

  In this state, as shown in FIG. 4A, the first solenoid 31a on the first planetary gear clutch mechanism 30A side is turned off. Then, the rotation of the sun gear member 41A is restricted by setting the first solenoid 31a in a non-energized state in this way. At the same time, the second solenoid 31b on the second planetary gear clutch mechanism 30B side is energized. And the rotation regulation of the sun gear member 41B is cancelled | released by energizing the 2nd solenoid 31b in this way.

  In this case, as shown in FIG. 2, the driving force input from the drive input gear 32 is transmitted to the internal geared member 44A, the planetary gear holding member 43A, and the planetary gear holding member 43B, and the drive output gear 33 is shown in the figure. It rotates in the direction of arrow B.

  At this time, the rotation restriction of the sun gear 41B is released in the second planetary gear clutch mechanism 30B connected to the member 44B with the internal gear engaged with the member 44A with the internal gear via the idler gear 35. Therefore, the drive connection between the planetary gear holding member 43B and the internal geared member 44B is in a released state, and the internal geared member 44B is not involved in the rotation of the planetary gear holding member 43B.

  On the other hand, as shown in FIG. 4B, the first solenoid 31a is energized to release the rotation restriction of the sun gear member 41A, and the second solenoid 31b is deenergized to restrict the rotation of the sun gear member 41B. Do.

  In this case, as shown in FIG. 2, the driving force input from the drive input gear 32 is transmitted to the internal geared member 44A, the idler gear 35, the internal geared member 44B, and the planetary gear holding member 43B, and the drive output The gear 33 rotates in the direction of the arrow C shown in the figure.

  At this time, the rotation restriction of the sun gear 41A is released in the first planetary gear clutch mechanism 30A connected to the internal geared member 44A. For this reason, the drive connection between the planetary gear holding member 43A and the internal geared member 44A is in a released state, and the internal geared member 44A is not involved in the rotation of the planetary gear holding member 43A.

  FIG. 5 shows a case where the first and second planetary gear clutch mechanisms 30A, 30B are energized with the first and second solenoids 31a, 31b energized and the rotation restriction of the sun gear members 41A, 41B is released. Yes. In this case, since the first and second planetary gear clutch mechanisms 30A, 30B are both in the drive connection release state, the drive force input from the drive input gear 32 is not transmitted anywhere, and the drive output gear 33 Can rotate freely. That is, when the first and second solenoids 31a and 31b are energized, the drive output gear 33 is in a disconnected state.

  As described above, when the rotation is transmitted from the drive input gear 32 to which the drive in the constant rotation direction is applied to the drive output gear 33 via the reverse drive device 28, the energization states of the first and second solenoids 31a and 31b are changed. I try to control it. As a result, the rotation direction of the drive output gear 33 can be arbitrarily set to three states of normal rotation / reverse rotation and drive disconnection.

  FIG. 6 is a control block diagram of the image forming apparatus 100. The first and second solenoids 31a and 31b are energized by a CPU 39 which is a control unit provided at a predetermined position of the image forming apparatus 100. 40 is controlled. In FIG. 6, reference numeral 50 denotes a paper discharge sensor. The paper discharge sensor 50 is disposed between the discharge roller 21 and the fixing device 16 as shown in FIG. M is a motor which is another drive system, for example, a drive unit of the fixing device 16.

  Next, a sheet conveying operation at the time of double-sided image formation of the image forming apparatus 100 configured as described above will be described with reference to a flowchart shown in FIG.

  First, the power supply of the image forming apparatus 100 is turned on. At this time, each of the first and second solenoids 31a and 31b is off (S100). Next, copying is started (S101). As a result, a toner image is formed in the image forming unit 1 and the sheet P is fed from the paper feed cassette 17 or the manual feed tray 20.

  The sheet P fed from the sheet feeding cassette 17 or the manual feed tray 20 in this way is conveyed to the secondary transfer unit 34 and the fixing device 16 through the conveyance path 18 to form a one-sided (first side) image. Is done. Thereafter, it passes through the paper discharge sensor 50 and reaches the discharge roller 21 connected to the drive output gear 33. The drive input gear 32 of the reversing drive device 28 described above is connected to the motor M that is the drive source of the fixing device 16 and is supplied with a drive force.

  Here, when the sheet discharge sensor 50 is turned on as the sheet P passes (Y in S102), the CPU 39 turns off the first solenoid 31a as shown in FIG. The second solenoid 31b is energized (On) (S103). As a result, the drive output gear 33 rotates in the direction B shown in FIG. 2B, and accordingly, the discharge roller 21 connected to the drive output gear 33 is driven in the forward direction to discharge the sheet P to the outside of the apparatus. Rotate in the direction (positive direction). Then, the sheet P is once conveyed to the sheet discharge tray 22 side by the discharge roller 21 rotating in the forward direction in this way.

  On the other hand, when the rear end of the sheet P passes through the paper discharge sensor 50 and the paper discharge sensor 50 changes from On to Off (Y in S104), the CPU 39 causes the rear end of the reversed sheet to pass through the discharge roller 21. A predetermined time is counted so as to detect the timing before the start (S105).

  Based on this count, the first solenoid 31a is turned on (On) as shown in FIG. 4B before a predetermined time for the trailing edge of the reversed sheet to pass through the discharge roller 21 elapses. Then, the second solenoid 31b is turned off (S106). As a result, the drive output gear 33 rotates in the direction C shown in FIG. 2B, and accordingly, the discharge roller 21 is driven in reverse to rotate in the direction in which the sheet P is fed to the duplex conveyance path 24 (reverse direction). . Then, the sheet P is sent to the double-sided conveyance path 24 by the discharge roller 21 rotating in the reverse direction in this way.

  Note that the CPU 39 counts a predetermined time so that the leading edge of the sheet P sufficiently passes through the duplex conveying roller 25 on the duplex conveying path 24 and detects the timing before the trailing edge of the sheet passes the discharge roller 21 ( S107). Then, based on this count, the CPU 39, as shown in FIG. 5, before the passage of a predetermined time after the reverse driving force is transmitted to the discharge roller 21 and the trailing edge of the sheet passes the discharge roller 21, 2 The solenoids 31a and 31b are energized (On) (S108).

  Thereby, as described above, the driving force input to the drive input gear 32 is not transmitted to the drive output gear 33, the drive output gear 33 becomes rotatable, and the drive of the discharge roller 21 is cut accordingly. The discharge roller 21 is in a freely rotatable state.

  Next, the sheet P is conveyed by the double-sided conveyance rollers 25 and 26 and joins the conveyance path 18. Thereafter, the sheet P is temporarily stopped by the registration roller 19 in order to match the timing at which the front end of the toner image on the intermediate transfer belt is moved to the secondary transfer portion 34 between the secondary transfer counter roller 10 and the secondary transfer roller 12. To do.

  At this time, the registration roller 19 and the double-sided conveyance rollers 25 and 26 are driven and supplied from the same drive source (not shown), so that the double-sided conveyance rollers 25 and 26 stop when the registration roller 19 stops. At this time, as described above, the drive of the discharge roller 21 is cut and freely rotatable. For this reason, when the registration roller 19 is stopped, even if the sheet P is sandwiched between the registration roller 9 and the discharge roller 21, a problem with the sheet P does not occur.

  Next, the sheet P whose registration roller 19 has been restarted at the same timing is conveyed to the secondary transfer unit 34, and the toner image on the second surface is transferred to an appropriate position on the sheet P. Also in this case, since the driving of the discharge roller 21 is cut and freely rotatable, a problem with the sheet P does not occur.

  Thereafter, the sheet P passes through the fixing device 16 again, and when the leading edge of the sheet P is detected by the paper discharge sensor 50, the first solenoid 31a is not energized (Off) and the second solenoid 31b is energized (On). And As a result, the discharge roller 21 rotates (forward rotation) in the direction of discharging the sheet P to the outside of the apparatus, and the sheet P is discharged to the discharge tray 22 by the discharge roller 21.

  This sheet conveying operation is continued until the double-sided image formation for all sheets is completed. When the double-sided image formation for all sheets is completed (Y in S109), the CPU 39 turns off the first and second solenoids 31a and 31b (S110), and the double-sided image forming operation is finished.

  Table 1 below summarizes the solenoid energized state of the reverse drive device 28 and the rotation direction of the output gear 33 in the present embodiment. As shown in Table 1, in this embodiment, the normal control for the discharge roller 21 is performed by the energization control for the first solenoid 31a and the energization control for the second solenoid 31b opposite to the energization control for the first solenoid 31a. Transmission of the rolling drive force and the reverse drive force is performed.

  As described above, the reverse driving device 28 according to the present embodiment switches the three modes of the forward rotation driving, the reverse driving, and the drive transmission cutting of the discharge roller 21 necessary for the reverse conveyance of the sheet P when the double-sided image is formed. The first and second solenoids 31a and 31b can be switched.

  That is, in the present embodiment, by switching the first and second solenoids 31a and 31b, the state of the clutch mechanisms 30A and 30B is reversely driven from the state in which the normal rotation driving force is transmitted to the discharge roller 21 to the discharge roller 21. It can be changed to a state where force is transmitted. Further, the transmission of the driving force to the discharge roller 21 can be stopped before a predetermined time has elapsed since the reverse drive force is transmitted to the discharge roller 21. Thereby, high-speed and reliable drive switching can be performed while suppressing an increase in size and cost of the apparatus.

  Next, a second embodiment of the present invention will be described.

  FIG. 8 is a schematic perspective view showing the configuration of the reversal drive device provided in the sheet conveying apparatus according to the present embodiment, and FIG. 9 is a front view thereof. 8 and 9, the same reference numerals as those in FIGS. 2 and 4 described above indicate the same or corresponding parts.

  As shown in FIGS. 8 and 9, the reverse drive device 29 includes planetary gear clutch mechanisms 30 (30A, 30B), first and second solenoids 31a, 31b, a drive input gear 32, and the like, and a second solenoid 31b. The motion conversion link member 36 connected to the.

  Here, the 2nd solenoid 31b performs rotation regulation of the sun gear member 41B via the operation | movement conversion link member 36, or rotation regulation cancellation | release. In this embodiment, the rotation of the sun gear member 41B is restricted when the second solenoid 31b is energized, and the rotation restriction of the sun gear member 41B is released when the second solenoid 31b is not energized. . Depending on the configuration, an operation conversion link member may be provided between the first solenoid 31a and the first planetary gear clutch mechanism 30A.

  Next, the operation of the inversion driving device 29 having such a configuration will be described.

  In the reverse drive device 29, as shown in FIG. 2, the drive input gear 32 is normally driven from a drive source (not shown) in a fixed rotational direction (arrow A direction shown in the figure), and the drive output gear 33 is a planetary clutch mechanism. It meshes with the outer peripheral gear surface 43b of the planetary gear holding member 43B of 30B.

  In this state, as shown in FIG. 9, the first solenoid 31a is turned off, the rotation of the sun gear member 41A is restricted, and the second solenoid 31b is turned off at the same time, thereby rotating the sun gear member 41B. Remove restrictions. In this case, as shown in FIG. 2, the driving force input from the drive input gear 32 is transmitted to the internal geared member 44A, the planetary gear holding member 43A, and the planetary gear holding member 43B, and the drive output gear 33 is illustrated. It rotates in the direction of arrow B.

  At this time, the rotation restriction of the sun gear 41B is released in the planetary gear clutch mechanism 30B connected to the member 44B with the internal gear meshing with the member 44A with the internal gear via the idler gear 35. For this reason, the drive connection between the planetary gear holding member 43B and the internal geared member 44B is in a released state, and the internal geared member 44B is not involved in the rotation of the planetary gear holding member 43B.

  On the other hand, as shown in FIG. 10 (a), the first solenoid 31a is energized to release the rotation restriction of the sun gear member 41A, and the second solenoid 31b is energized at the same time. Restrict rotation.

  In this case, the driving force input from the drive input gear 32 is transmitted to the internal geared member 44A, the idler gear 35, the internal geared member 44B, and the planetary gear holding member 43B as shown in FIG. The gear 33 rotates in the direction of the arrow C shown in the figure.

  At this time, in the planetary gear clutch mechanism 30A connected to the internal geared member 44A, the rotation restriction of the sun gear 41A is released. For this reason, the drive connection between the planetary gear holding member 43A and the internal geared member 44A is in a released state, and the internal geared member 44A is not involved in the rotation of the planetary gear holding member 43A.

  FIG. 10B shows a state in which the rotation restriction of the sun gear member 41B is released with the first solenoid 31a in the energized state to release the rotation restriction of the sun gear member 41A and the second solenoid 31b in the non-energized state. Is shown.

  In this case, since the two planetary gear clutch mechanisms 30A and 30B are both in the drive disengaged state, the drive force input from the drive input gear 32 is not transmitted anywhere, and the drive output gear 33 is rotatable. Become.

  As described above, when the rotation is transmitted from the drive input gear 32 to which the drive in the constant rotation direction is applied to the drive output gear 33 via the reverse drive device 29, the energization states of the first and second solenoids 31a and 31b are changed. I try to control it. As a result, the rotation direction of the drive output gear 33 can be arbitrarily set to three states of normal rotation / reverse rotation and drive disconnection.

  Next, a sheet conveying operation at the time of double-sided image formation of the image forming apparatus 100 configured as described above will be described with reference to a flowchart shown in FIG.

  First, the power supply of the image forming apparatus 100 is turned on. At this time, each of the first and second solenoids 31a and 31b is off (S200). Next, copying is started (S201). As a result, a toner image is formed in the image forming unit, and a sheet is fed from the paper feed cassette 17 or the manual feed tray 20.

  Then, the sheet fed from the sheet feeding cassette 17 or the manual feed tray 20 in this way is conveyed to the secondary transfer unit 34 and the fixing device 16 through the conveyance path 18 to form the first image. Thereafter, it passes through the paper discharge sensor 50 and reaches the discharge roller 21 connected to the drive output gear 33. At this time, the drive input gear 32 (see FIG. 2) is connected to a motor M as a drive source of the fixing device 16 and is supplied with a drive force.

  When the sheet discharge sensor 50 is turned on as the sheet passes (Y in S202), the CPU 39 turns off the first solenoid 31a and turns off the second solenoid 31b as shown in FIG. A non-energized (Off) state is set (S203). As a result, the drive output gear 33 rotates in the direction B shown in FIG. 2B, and accordingly, the discharge roller 21 connected to the drive output gear 33 is driven to rotate forward, and the sheet is moved to the discharge tray 22 side. Once transported.

  On the other hand, after this, when the rear end of the sheet P passes through the paper discharge sensor 50 and the paper discharge sensor 50 changes from On to Off (Y in S204), the CPU 39 detects that the front end of the sheet has not passed through the discharge roller 21. A predetermined time as a timing is counted (S205). Based on the predetermined time count, before the trailing edge of the sheet passes the discharge roller 21, the first solenoid 31a is energized (On) and the second solenoid 31b is energized as shown in FIG. The (On) state is set (S206).

  As a result, the drive output gear 33 rotates in the direction C shown in FIG. 2B, and the discharge roller 21 rotates (reverses) in the reverse direction. Accordingly, the sheet P is sent to the duplex conveyance path 24 by the above operation.

  Note that the CPU 39 counts a predetermined time when the leading edge of the sheet P sufficiently passes the double-sided conveyance roller 25 on the double-sided conveyance path 24 (S207). At this timing, the CPU 39 sets the first solenoid 31a in the energized (On) state and the second solenoid 31b in the non-energized (Off) state as shown in FIG. 10B (S208). Thereby, as described above, the driving force input to the drive input gear 32 is not transmitted to the drive output gear 33, the drive output gear 33 becomes rotatable, and the drive of the discharge roller 21 is cut accordingly. The discharge roller 21 is in a freely rotatable state.

  Next, the sheet is conveyed by the double-sided conveyance rollers 25 and 26 and joins the conveyance path 18. Thereafter, the sheet is temporarily stopped by the registration roller 19 in order to match the timing at which the leading edge of the toner image on the intermediate transfer belt is moved to the secondary transfer portion 34 between the secondary transfer counter roller 10 and the secondary transfer roller 12. .

  At this time, the registration roller 19 and the double-sided conveyance rollers 25 and 26 are driven and supplied from the same drive source (not shown), so that the double-sided conveyance rollers 25 and 26 stop when the registration roller 19 stops. Here, as described above, since the drive of the discharge roller 21 is cut and rotatable as described above, even if the sheet P is sandwiched from the registration roller 9 to the discharge roller 21, it is transferred to the sheet P. Does not cause any problems.

  Next, the sheet P whose registration roller 19 has been restarted at the same timing is conveyed to the secondary transfer unit 34, and the toner image on the second surface is transferred to an appropriate position on the sheet P. Also in this case, since the driving of the discharge roller 21 is cut and freely rotatable, a problem with the sheet P does not occur.

  Thereafter, the sheet passes through the fixing device 16 again, and when the leading edge of the sheet is detected by the paper discharge sensor 50, the first and second solenoids 31a are turned off. As a result, the discharge roller 21 rotates (forward rotation) in the direction of discharging the sheet P to the outside of the apparatus, and the sheet P is discharged to the discharge tray 22 by the discharge roller 21.

  This sheet conveying operation is continued until the double-sided image formation for all sheets is completed. When the double-sided image formation for all sheets is completed (Y in S209), the CPU 39 turns off the first and second solenoids 31a and 31b (S210), and the double-sided image forming operation is finished.

  Table 2 below summarizes the solenoid energization state of the reverse drive device 29 and the rotation direction of the output gear 33 in the present embodiment.

  Here, as shown in FIG. 9, when the first and second solenoids 31a, 31b are in a non-energized state, the drive output gear 33 is the most frequently used rotational direction indicated by an arrow B in FIG. The sheet is rotated in a direction in which the sheet is discharged out of the image forming apparatus main body. That is, when the first and second solenoids 31a and 31b are in a non-energized state, the drive output gear 33 is rotated in a direction in which the sheet is discharged out of the apparatus main body.

  And by comprising in this way, the 1st and 2nd solenoid 31a, 31b can be made into a non-energized state in the rotation direction with the highest use frequency. As a result, it is possible to save power and to reduce the temperature rise of the solenoid due to the energized state of the solenoids 31a and 31b being continued for a long time during continuous use. Can be avoided.

  Incidentally, as described above, in the reverse drive devices 28 and 29 according to the first and second embodiments, the three states of normal rotation / reverse rotation / drive disconnection can be realized, but the sun gear member 41A is further provided. , 41B, the drive can be locked.

  For example, in the second embodiment, when the first solenoid 31a is set to Off (off) and the second solenoid 31b is set to On (on), both the sun gear members 41A and 41B rotate via the motion conversion link member 36. It becomes a regulated state.

  At this time, both the first and second planetary gear clutch mechanisms 30A and 30B are in a state in which the drive can be transmitted, and the drive of the discharge roller 21 may be locked in order to transmit the drive in different directions. it can. Therefore, for example, in the case of an emergency stop such as when the user opens the door during operation, if the first solenoid 31a is turned off and the second solenoid 31b is turned on, the reversing drive device 29 becomes a drive lock. It can be used.

  On the other hand, if one of the solenoids malfunctions due to an assembly error, such as forgetting to insert the connector, or if the solenoid operation is abnormal due to a wrong connector insertion, the drive locks during operation. May occur.

  For this reason, in the reversal drive device, for example, as shown in FIG. 12, the bundled wires of the first and second solenoids are combined into one connector 55, and up to the connector 55 is set as a reversal drive device unit. As a result, it is possible to prevent forgetting to insert the connector or incorrect insertion during assembly.

  In the description so far, the case where the rotation restricting operation of the sun gear members 41A and 41B of the first and second planetary gear clutch mechanisms 30A and 30B is performed using the first and second solenoids 31a and 31b will be described. did. Here, the reason why the solenoid is used is that the response speed and cost are taken into consideration. In the case of the solenoid, high-speed response (10 to 100 ms) can be secured, and it is sufficiently inexpensive as compared with a motor or the like. However, if there is a margin in the required responsiveness, the same effect can be obtained even if different types of actuators such as a missing gear are used as switching means for switching the states of the first and second clutch mechanisms.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a reversal driving device provided in the image forming apparatus. The figure explaining the structure of the planetary gear clutch mechanism of the said inversion drive device. The 1st figure explaining operation | movement of the said inversion drive device. FIG. 8 is a second diagram illustrating the operation of the inversion driving device. FIG. 2 is a control block diagram of the image forming apparatus. 6 is a flowchart for explaining a sheet conveying operation when the image forming apparatus forms a double-sided image. FIG. 6 is a schematic perspective view illustrating a configuration of a reverse driving device provided in a sheet conveying device according to a second embodiment of the present invention. The front view of the said inversion drive device. The figure explaining operation | movement of the said inversion drive device. 6 is a flowchart for explaining a sheet conveying operation when the image forming apparatus forms a double-sided image. FIG. 4 is another control block diagram of the image forming apparatus. 1 is a diagram illustrating a schematic configuration of a conventional image forming apparatus. FIG. 6 is a diagram illustrating a configuration of a reversal driving device provided in a conventional image forming apparatus. The figure explaining the structure of the planetary gear clutch mechanism of the said inversion drive device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image formation part 21 Discharge roller 24 Double-sided conveyance path 28 Reverse drive device 29 Reverse drive device 30A 1st planetary gear clutch mechanism 30B 2nd planetary gear clutch mechanism 31a 1st solenoid 31b 2nd solenoid 32 Drive input gear 33 Drive output gear 36 Motion conversion link member 39 CPU
41 Sun gear member 42 Planetary gear 50 Paper discharge sensor 100 Image forming apparatus 100A Sheet conveying apparatus M Motor P Sheet

Claims (14)

An image forming unit, a reverse conveying roller capable of normal / reverse rotation that inverts the sheet on which the image is formed and conveys the image to the image forming unit again, and a forward / reverse drive that forward / reversely drives the reverse conveying roller by the driving force from the driving unit In an image forming apparatus comprising a reverse drive unit,
The forward / reverse drive unit is
A clutch mechanism that is disposed between the driving unit and the reverse conveying roller, and selectively transmits a forward driving force and a reverse driving force to the reverse conveying roller;
First switching means for switching the state of the clutch mechanism to a state of transmitting a normal driving force to the reverse conveying roller and a state of not transmitting the driving force;
Second switching means for switching the state of the clutch mechanism between a state in which a reverse driving force is transmitted to the reverse conveying roller and a state in which the driving force is not transmitted;
A controller that controls the switching operation of the first switching means and the second switching means,
When the control unit reverses the sheet and conveys the sheet again to the image forming unit, the control unit changes the state of the clutch mechanism from the state of transmitting the normal driving force to the reverse conveying roller to the reverse conveying roller. The state is changed so that the transmission of the driving force to the reverse conveying roller is stopped until the trailing edge of the reversed sheet reaches the reverse conveying roller after transmitting the reverse driving force. An image forming apparatus for controlling a switching operation of the first and second switching means. A driving input unit to which driving force in one direction from the driving unit is input;
A drive output unit that outputs the forward driving force or the reverse driving force to the reverse conveying roller,
The image forming apparatus according to claim 1, wherein the clutch mechanism is disposed between the drive input unit and the drive output unit. The first and second switching means are a first solenoid and a second solenoid,
3. The image formation according to claim 1, wherein the control unit stops the transmission of the driving force and the transmission of the driving force to the reverse conveying roller by energization control to the first solenoid and the second solenoid. apparatus.   The forward drive force and the reverse drive force are transmitted to the reverse conveying roller by an energization control for the first solenoid and an energization control for the second solenoid opposite to the energization control for the first solenoid. The image forming apparatus according to claim 3.   Between the first solenoid and the clutch mechanism or the second solenoid and the clutch so as to stop the transmission of the drive to the reverse conveying roller when the energization of the first solenoid and the second solenoid is turned off. The image forming apparatus according to claim 3, wherein an operation conversion link member that converts an operation of the first solenoid or the second solenoid is provided between the mechanism and the mechanism. An image forming unit, a reverse conveying roller capable of normal / reverse rotation that inverts the sheet on which the image is formed and conveys the image to the image forming unit again, and a forward / reverse drive that forward / reversely drives the reverse conveying roller by the driving force from the driving unit. In an image forming apparatus comprising a reverse drive unit,
The forward / reverse drive unit is
A first planetary gear clutch mechanism disposed between the drive unit and the reverse conveying roller, the first planetary gear clutch mechanism having a plurality of planetary gears engaged with the first sun gear member, and the second sun gear; A clutch mechanism comprising a second planetary gear clutch mechanism having a gear member and a plurality of planetary gears meshing with the second sun gear member, and selectively transmitting a forward driving force and a reverse driving force to the reverse conveying roller When,
By restricting rotation of one of the first sun gear member and the second sun gear member, a driving force is transmitted to the reverse conveying roller, and the first sun gear member and the second sun gear are transmitted. By canceling the rotation restriction of both of the members, the transmission of the driving force to the reverse conveying roller is stopped to change the state of the clutch mechanism, the state of transmitting the normal driving force to the reverse conveying roller, the reverse driving Switching means for switching to a state of transmitting force and a state of not transmitting driving force;
An image forming apparatus comprising: a control unit that controls a switching operation of the switching unit . The switching means transmits a first switching means for switching a normal driving force to the reverse conveying roller and a state for not transmitting a driving force, and transmits a reverse driving force and a driving force to the reverse conveying roller. The image forming apparatus according to claim 6, further comprising a second switching unit that switches to a state in which it is not performed. When the control unit reverses the sheet and conveys the sheet again to the image forming unit, the control unit changes the state of the clutch mechanism from the state of transmitting the normal driving force to the reverse conveying roller to the reverse conveying roller. Is switched to a state in which the transmission of the driving force to the reverse conveying roller is stopped before the trailing edge of the reversed sheet reaches the reverse conveying roller after the reverse driving force is transmitted. 8. The image forming apparatus according to claim 6, wherein the switching operation of the means is controlled. The controller controls the switching operation of the first and second switching means to lock the reverse conveying roller by setting both states of the two planetary gear clutch mechanisms to a state in which driving force is transmitted to the reverse conveying roller. The image forming apparatus according to claim 6, wherein the image forming apparatus is an image forming apparatus. The reverse conveying roller, an image forming apparatus according to any one of claims 1 to 9, characterized in that also serves as a discharge roller for discharging the sheet out of the apparatus main body. In a sheet conveying apparatus comprising: a reversible conveying roller capable of normal / reversing conveyance so as to invert the sheet; and a forward / reverse driving unit for driving the reverse conveying roller in the normal / reverse direction by a driving force from a driving unit,
A first planetary gear clutch mechanism disposed between the drive unit and the reverse conveying roller, the first planetary gear clutch mechanism having a plurality of planetary gears engaged with the first sun gear member, and the second sun gear; A clutch mechanism comprising a second planetary gear clutch mechanism having a gear member and a plurality of planetary gears meshing with the second sun gear member, and selectively transmitting a forward driving force and a reverse driving force to the reverse conveying roller When,
By restricting rotation of one of the first sun gear member and the second sun gear member, a driving force is transmitted to the reverse conveying roller, and the first sun gear member and the second sun gear are transmitted. By canceling the rotation restriction of both of the members, the transmission of the driving force to the reverse conveying roller is stopped to change the state of the clutch mechanism, the state of transmitting the normal driving force to the reverse conveying roller, the reverse driving a switching Ru switching Rikae means in a state that does not transmit state, and the driving force transmitting force,
A control unit for controlling the switching operation of said switching Rikae means,
Sheet conveying apparatus characterized by a kite comprising a. The switching means transmits a first switching means for switching a normal driving force to the reverse conveying roller and a state for not transmitting a driving force, and transmits a reverse driving force and a driving force to the reverse conveying roller. The sheet conveying apparatus according to claim 11, further comprising: a second switching unit that switches to a state in which it is not performed. When the control unit reverses the sheet and conveys the sheet again to the image forming unit, the control unit changes the state of the clutch mechanism from the state of transmitting the normal driving force to the reverse conveying roller to the reverse conveying roller. Is switched to a state in which the transmission of the driving force to the reverse conveying roller is stopped before the trailing edge of the reversed sheet reaches the reverse conveying roller after the reverse driving force is transmitted. The sheet conveying apparatus according to claim 11 or 12, which controls a switching operation of the means. The controller controls the switching operation of the first and second switching means to lock the reverse conveying roller by setting both states of the two planetary gear clutch mechanisms to a state in which driving force is transmitted to the reverse conveying roller. The sheet conveying apparatus according to claim 11, wherein the sheet conveying apparatus is a sheet conveying apparatus.

Images