JP5755613B2 - Transport device - Google Patents

Description

  The embodiment described in this specification relates to a technique for holding a sheet having a leading end against a nip of a registration roller in a state where the leading end is in contact with the nip.

  Conventionally, an image forming apparatus such as an MFP (Multi Function Peripheral) that forms an image on a sheet is known (for example, Patent Document 1). The image forming apparatus includes a registration roller that adjusts the timing of feeding the sheet to the image forming unit and corrects the skew of the fed sheet.

  The sheet is conveyed from the upstream conveying roller to the registration roller. When the leading edge of the sheet hits the nip of the registration roller, the inclination of the leading edge in the conveying direction is corrected and the skew is corrected. At this time, the sheet is bent when the conveyance direction rear side is sent out by the conveyance roller while the conveyance direction front end abuts against the nip of the registration roller.

  For this reason, if the sheet is thick due to its thickness, the sheet is stretched by the stiffness, and a returning force is applied to the conveying roller so as to rotate the conveying roller in a direction to return the sheet upstream in the conveying direction. When the conveyance roller is directly connected to the motor or when the pressure between the conveyance rollers is strong, the conveyance roller does not rotate reversely even if it receives a return force from the sheet.

  However, if the conveying roller is connected to the motor via a clutch and the clutch is disconnected immediately after the conveying roller sends the sheet to the registration roller side, or if the pressure between the conveying rollers is weak, the conveying roller It may reversely rotate due to the return force received from the rear end side. If the conveying roller rotates in the reverse direction, the sheet is returned to the upstream side by the conveying roller, and the leading end in the conveying direction is separated from the nip of the registration roller. Such a phenomenon contributes to variations in the front end position of the sheet and poor conveyance.

  An object of this specification is to provide a technique for holding a sheet that has hit the nip of a registration roller in a state in which the leading end hits the nip.

In general, according to the embodiment, the transport device includes a registration roller, a transport roller, and a rotation restriction mechanism. The registration rollers convey the sheet downstream in the conveyance direction with the nip interposed therebetween. The conveyance roller corrects the skew of the sheet by conveying the sheet to the registration roller side and abutting the leading end in the conveyance direction of the sheet against the nip to bend the sheet. The conveying roller includes a driving roller driven by a driving source, and a driven roller that is opposed to the driving roller and is driven by a sheet conveyed in the conveying direction. The rotation restricting mechanism is a force applied to the conveying roller at the trailing end in the conveying direction of the sheet that is bent due to the leading end of the conveying direction being abutted against the nip, and the conveying roller is moved in the returning direction to return the sheet upstream in the conveying direction. The rotation of the transport roller in the return direction is restricted by the force to be rotated. The rotation regulating mechanism is provided on the shaft of the driven roller that is rotatably held by the frame of the conveying device , provided between the driven roller and the frame and at a position away from the frame, meshes only with the second gear, and has an outer shape. Includes a first gear having a substantially circular shape, and a second gear that engages with the first gear by incorporating a one-way clutch that restricts rotation of the shaft in the direction in which the driven roller rotates in the return direction.

1 is a diagram illustrating an internal configuration of an image forming apparatus according to a first embodiment. It is a side view which shows a conveying apparatus. It is a perspective view which shows the structure for driving a drive roller. It is a top view which shows the transmission path | route of the driving force from a motor. It is sectional drawing which shows the structure of a 2nd gear typically. It is sectional drawing which shows the effect | action of a 2nd gear and a one-way clutch. It is a figure which shows the reverse rotation control mechanism of 2nd Embodiment.

Each embodiment will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating an internal configuration of the image forming apparatus 1. In FIG. 1, the vertical direction is the + −Z direction, the right / left direction is the + −X direction, and the direction toward the near side and the direction toward the far side in the paper vertical direction are the + −Y direction.

  The image forming apparatus 1 is an MFP. When the image forming apparatus 1 receives a user operation input from the touch panel 11, the image reading unit 13 reads a sheet set on the ADF 12 (Auto Document Feeder) or the document table 131 by a CCD (Charge Coupled Device) 132. A print job including commands such as image data and the number of prints is generated.

  Subsequently, the image forming apparatus 1 takes out the sheet from the sheet feeding cassette 14 by the pickup roller 211 or the like, then conveys the sheet to the registration roller 3 by the conveyance roller 212, and corrects the skew of the sheet by the registration roller 3. The image forming apparatus 1 sends a sheet whose skew has been corrected from the registration roller 3 to the image forming unit 22 at a predetermined timing, and the image forming unit 22 forms an image on the sheet based on the print job. Of the conveyance rollers 212, a conveyance roller 212 that is one upstream of the registration rollers 3 and that feeds a sheet to the registration rollers 3 is referred to as a conveyance roller 4.

  In the image forming unit 22, the laser unit 221 forms electrostatic latent images on the photoconductors 2221 </ b> Y to 2221 </ b> K for each color of the developing unit 222 with a laser. The developing unit 222 develops the electrostatic latent images on the photoconductors 2221Y to 2221K, and forms toner images for the respective colors on the photoconductors 2221Y to 2221K. The photoconductors 2221Y to 2221K form a single color toner image by superimposing and transferring the toner images of the respective colors on the transfer belt 2231 of the transfer unit 223. The transfer belt 2231 transfers the toner image to the sheet at the transfer position P with respect to the sheet fed by the registration roller 3. The image forming apparatus 1 heats and presses the sheet on which the toner image is transferred in this manner by the fixing unit 23 to fix the image on the sheet, and then discharges the sheet onto the discharge tray 24. When the print job instructs double-sided printing or the like, the image forming apparatus 1 reverses the sheet on which the image is fixed on one side by the fixing unit 23 by the ADU 25 and sends it to the transfer position P. Then, the image forming apparatus 1 forms an image on the other surface at the transfer position P by the image forming unit 22, performs a fixing process, and discharges the sheet onto the discharge tray 232.

FIG. 2 is a side view showing the transport device 5.
A conveyance device 5 is configured including the registration roller 3 and the conveyance roller 4 upstream of the registration roller 3. The conveying device 5 corrects the skew of the sheet and adjusts the timing to send the sheet to the transfer position P by the image forming unit 22.
The transport device 5 includes a transport guide 51, a transport roller 4, and a registration roller 3. Further, the transport device 5 includes a motor 52 (drive source), a drive force transmission mechanism 6, a reverse rotation restriction mechanism 7 (rotation restriction mechanism), and a control unit 8 shown in FIG.

  The conveyance guide 51 guides the sheet conveyed from the sheet feeding cassette 14 side to the registration roller 3 through the conveyance roller 4. In the conveyance guide 51, an open portion 511 that opens to the ADU 25 side is formed between the conveyance roller 4 and the registration roller 3. The ADU 25 sends the sheet into the guide 5 upstream of the registration roller 3 through the opening 511 and conveys the sheet to the registration roller 3 along the guide 5. The space in the opening portion 511 also functions as a space for the sheet that hits the registration roller 3 to bend.

The conveyance roller 4 conveys the sheet conveyed from the sheet feeding cassette 14 side to the registration roller 3 side, and abuts the leading end of the sheet in the conveyance direction against the nip N of the registration roller 3 to bend the sheet. Correct. The conveying roller 4 includes a driving roller 41 and a driven roller 42. The driving roller 41 is disposed inside the image forming apparatus 1 and is driven by a driving force from the motor 52. The driven roller 42 is disposed outside the image forming apparatus 1 and at a position facing the driving roller 41, and rotates following the sheet conveyed in the conveyance direction.
The registration roller 3 includes a pair of rollers 31 and 32 that face each other and sandwich and convey the sheet. A nip N is formed between the pair of rollers 31 and 32.

  When the sheet is sent to the registration roller 3 by the drive roller 41, the leading end in the conveyance direction hits the nip N of the registration roller 3. In this state, the sheet is further fed to the registration roller 3 side by the driving roller 41 on the rear end side in the conveyance direction, so that even when the initial posture is inclined and only a part of the leading edge of the sheet hits the nip N, All the tips in the transport direction are in contact with the nip N extending in the direction orthogonal to the transport direction (the vertical direction in FIG. 2). At this time, the rear end side of the sheet is sent to the driving roller 41, whereby the central portion is bent and the central portion is located in the opening portion 511. Thereby, the skew of the sheet is corrected. The registration roller 3 conveys the skew-corrected sheet between the nips N toward the transfer position P by the image forming unit 22 at a predetermined timing.

FIG. 3 is a perspective view showing a configuration for driving the drive roller 41, and FIG. 4 is a plan view showing a driving force transmission path from the motor 52 to the drive roller 41.
The drive roller 41 is provided on the shaft 411 and rotates integrally with the shaft 411.
The motor 52 is a drive source for the drive roller 41. A driving force transmission mechanism 6 that transmits a driving force to the driving roller 41 is connected to the motor 52. A clutch 64 is provided in the driving force transmission mechanism 6.

  The control unit 8 includes a CPU (Central Processing Unit) and a memory that stores various programs read by the CPU. The control unit 8 controls the motor 52, the clutch 64 in the driving force transmission mechanism 6, and the registration roller 3, and also controls the entire image forming apparatus 1. The control unit 8 transmits the driving force from the motor 52 to the driving roller 41 by connecting the clutch 64 in the driving force transmission mechanism 6.

The driving force transmission mechanism 6 transmits the driving force from the motor 52 to the driving roller 41. The driving force transmission mechanism 6 includes gears 61 to 63, a clutch 64, and a shaft 411.
The gears 61 to 63 transmit the driving force from the motor 52 to the clutch 64.
The clutch 64 is provided at one end of the shaft 411 of the driving roller 41, and connects and disconnects transmission of driving force from the motor 52 side to the driving roller 41 side. In this embodiment, an electromagnetic clutch is used as the clutch 64, but other configurations may be used.

  As described above, when the skew correction of the sheet is performed by the registration roller 3, the control unit 8 drives the motor 52 and drives the driving roller 41 by setting the clutch 64 to the connected state. The control unit 8 corrects the skew of the sheet by feeding the trailing end of the sheet in the sheet conveyance direction by the driving roller 41 with the sheet conveyance direction leading end abutting the nip N of the registration roller 3. As a result, the sheet is bent.

  After correcting the skew of the sheet, the control unit 8 drives the registration roller 3 to send the sheet to the transfer position P by the image forming unit 22 at a predetermined timing. At this time, the sheet is stretched when there is stiffness due to its thickness and the like, and a force to rotate the driving roller 41 in the returning direction to return the sheet to the upstream side in the conveying direction is applied to the driving roller 41 by the trailing end side of the sheet. To give. The driving roller 41 has a force in the returning direction from the sheet when the clutch 64 is disengaged or when the pressure applied to the driven roller 42 by the driving roller 41 (the force pressing the driving roller 41 against the driven roller 42) is weak. May rotate in the return direction. As a result, the sheet is returned in the returning direction, and the leading edge of the sheet is separated from the nip N.

The reverse rotation restricting mechanism 7 restricts the rotation of the driving roller 41 in the return direction between the clutch 64 and the driving roller 41 in the driving force transmission mechanism 6. The reverse rotation restricting mechanism 7 includes a first gear 71 and a second gear 72.
The first gear 71 is provided on the shaft 411 of the drive roller 41 and rotates integrally with the shaft 411.

FIG. 5 is a cross-sectional view schematically showing the configuration of the second gear 72.
The second gear 72 meshes with the first gear 71 by a gear formed on the outer peripheral surface. The second gear 72 incorporates the one-way clutch 9. The shaft 721 of the second gear 72 is fixed to the frame 10 (FIG. 4) of the image forming apparatus 1 and does not rotate. A one-way clutch 9 is provided between the shaft 721 and the second gear 72.

  The one-way clutch 9 includes a plurality of wedge-shaped grooves 91 formed on the inner peripheral surface of the second gear 72, and balls 92 and springs 93 between the respective wedge-shaped grooves 91 and the shaft 721 of the second gear 72. Between each wedge-shaped groove 91 and the shaft 721 of the second gear 72, a wedge-shaped space S is formed that becomes narrower in the clockwise direction in FIG. The spring 93 is arranged in the clockwise direction in which the wedge-shaped space S expands more than the ball 92 in the wedge-shaped space S.

When the motor 52 is driven and the shaft 411 and the drive roller 41 rotate in the feed direction, the first gear 71 on the shaft 411 rotates in the A1 direction, which is counterclockwise in FIG. Then, the second gear 72 that meshes with the first gear 71 rotates in the B1 direction, which is the clockwise direction in FIG.
At this time, each ball 92 of the one-way clutch 9 is idled at a position where the space in the wedge-shaped space S is large, so that the second gear 72 is allowed to rotate in the B1 direction (feed direction). Is done.

FIG. 6 is a cross-sectional view showing the operation of the second gear 72 and the one-way clutch 9 when the drive roller 41 rotates in the return direction.
When the driving roller 41 receives a force in the returning direction from the rear end side of the sheet and rotates slightly in the returning direction, the first gear 71 connected to the driving roller 41 via the shaft 411 is in the A2 direction which is the clockwise direction in FIG. Rotate slightly.

  As a result, the second gear 72 that meshes with the first gear 71 also slightly rotates in the B2 direction, which is counterclockwise in FIG. 5, but each ball 92 is located between each wedge-shaped groove 91 and the shaft 721. Since the second gear 72 is slightly rotated in the direction B2, the rotation is restricted by the one-way clutch 9, and the rotation stops.

  As described above, in the present embodiment, the reverse rotation restricting mechanism 7 is directly connected to the shaft 411 of the drive roller 41, so that the sheet that has been abutted against the registration roller 3 and corrected for skew is driven by the stiffness of the drive roller 41. The reverse rotation restricting mechanism 7 can prevent the rotation in the returning direction. Therefore, in the present embodiment, the sheet that hits the nip N of the registration roller 3 can be held in a state where the front end in the conveyance direction hits the nip N.

(Second Embodiment)
FIG. 7 is a view showing the reverse rotation restricting mechanism 7A.
In the first embodiment, the reverse rotation restricting mechanism 7 is directly connected to the shaft 411 of the drive roller 41. However, in this embodiment, the reverse rotation restricting mechanism 7A is directly connected to the shaft 421 of the driven roller 42 as shown in FIG. Is done. The shaft 421 of the driven roller 42 is rotatably held by the frame 10 of the image forming apparatus 1.

  The reverse rotation restricting mechanism 7A includes a first gear 71A provided on the shaft 421 and a second gear 72A that meshes with the first gear 71A. The second gear 72A has a configuration similar to that of the second gear 72 of the first embodiment, and incorporates the one-way clutch 9. The shaft 721 of the second gear 72A is fixedly supported by the frame 10 of the image forming apparatus 1 and does not rotate.

  Also in the present embodiment, the reverse rotation restricting mechanism 7A allows the driven roller 42 to follow and rotate in the feeding direction in which the sheet is sent to the downstream side in the conveyance direction (right direction in FIG. 7), but the sheet is conveyed upstream in the conveyance direction ( Rotation in the return direction returning to the left in FIG. 7 is restricted. Therefore, also in this embodiment, the reverse rotation regulating mechanism 7A can prevent the driven roller 42 from rotating in the returning direction, and the sheet can be held in a state where the leading end in the conveying direction hits the nip N.

The configuration of the one-way clutch 9 is not limited to that of each embodiment, and an appropriate configuration can be adopted as long as the rotation of the conveyance roller 4 in the return direction can be regulated.
The conveying device is not limited to that used in the image forming apparatus, and may be used in, for example, a scanner or a decoloring device.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted by the text of the specification. Further, all modifications, various improvements, alternatives and modifications belonging to the equivalent scope of the claims are all within the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 3 ... Registration roller, 4 ... Conveying roller, 5 ... Conveying apparatus, 6 ... Driving force transmission mechanism, 7 ... Reverse rotation restricting mechanism (rotation restricting mechanism), 22 ... Image forming part, 41 ... Driving roller 42 ... driven roller, 52 ... motor (drive source), 64 ... clutch, 71 ... first gear, 72 ... second gear, 411, 421 ... shaft of the conveying roller.

JP 2009-301045 A

Claims (2)

A conveying device,
A registration roller that conveys the sheet downstream in the conveyance direction with the nip sandwiched therebetween,
A conveying roller that conveys the sheet toward the registration roller, corrects the skew of the sheet by abutting the leading end in the conveying direction of the sheet against the nip and deflecting the sheet, and a driving roller driven by a driving source; A conveying roller provided with a driven roller facing the driving roller and driven by a sheet conveyed in the conveying direction;
The trailing end of the sheet in the conveyance direction is the force applied to the conveyance roller, and the conveyance roller is rotated in the return direction to return the sheet upstream in the conveyance direction. Yo and said conveying roller by a force that rotates in the return direction, a rotation restricting mechanism for restricting a, on the shaft of the driven roller which is rotatably held in the frame of the transport device, the driven roller Between the first and second frames and at a position away from the first frame, meshing only with the second gear and having a substantially circular outer shape, and a direction in which the driven roller rotates in the return direction. conveying apparatus and a rotation regulating mechanism including the second gear, the built-in mesh with the first gear and the one-way clutch for restricting the rotation of said shaft. A transport apparatus according to claim 1;
An image forming unit that forms an image on a sheet conveyed by the conveying device;
An image forming apparatus comprising:

Images