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CN-116203810-B - Image forming apparatus having a plurality of image forming units

CN116203810BCN 116203810 BCN116203810 BCN 116203810BCN-116203810-B

Abstract

The invention discloses an image forming apparatus. The image forming apparatus includes an image forming unit, a pair of reverse rollers, a moving unit, and an obtaining unit. The image forming unit is configured to pinch the sheet and rotate in a first direction, and then rotate and convey the sheet in a second direction. The moving unit moves the reversing roller pair, and the obtaining unit obtains the length of the sheet. The moving unit moves the pair of reverse rollers that conveys the first sheet by a first movement amount in the width direction in a case where the first sheet is reversed and conveyed, and wherein the moving unit moves the pair of reverse rollers that conveys the second sheet by a second movement amount smaller than the first movement amount in the width direction in a case where the second sheet is reversed and conveyed, a length of the first sheet in the conveying direction being a first length, and a length of the second sheet in the conveying direction being a second length that is greater than the first length.

Inventors

  • LIN YINGHUI

Assignees

  • 佳能株式会社

Dates

Publication Date
20260505
Application Date
20221109
Priority Date
20211130

Claims (13)

  1. 1. An image forming apparatus comprising: An image forming unit configured to form an image on a sheet; a reversing roller pair configured to nip a sheet on which an image is formed by the image forming unit and rotate in a first direction and then rotate in a second direction to reverse and convey the sheet, the second direction being opposite to the first direction; a moving unit configured to move the reversing roller pair in a width direction of a sheet, the width direction being orthogonal to a conveying direction of the sheet, in a state where the sheet is nipped by the reversing roller pair; An obtaining unit configured to obtain information on a length of the sheet in the conveying direction, and A control unit configured to control the moving unit based on the information on the length of the sheet obtained by the obtaining unit, Wherein, in a case where the first sheet is reversed and conveyed, the control unit controls the moving unit to move the reversing roller pair conveying the first sheet by a first movement amount in the width direction, and Wherein, in a case where a second sheet is reversed and conveyed, the control unit controls the moving unit to move the reversing roller pair conveying the second sheet in the width direction by a second movement amount smaller than the first movement amount, a length of the first sheet in the conveying direction being a first length, and a length of the second sheet in the conveying direction being a second length larger than the first length.
  2. 2. The image forming apparatus according to claim 1, wherein in a case where the second sheet is reversed and conveyed, the control unit controls the moving unit so that the moving unit does not move the reversing roller pair that conveys the second sheet in the width direction.
  3. 3. The image forming apparatus according to claim 1, further comprising a skew correction unit configured to correct skew of the sheet after the sheet is conveyed by the reverse roller, Wherein after skew of the sheet is corrected by the skew correction unit, the sheet is conveyed toward the image forming unit.
  4. 4. The image forming apparatus according to claim 1, further comprising: a skew correction unit configured to correct skew of the sheet whose conveying direction has been reversed by the reversing roller pair, and Another moving unit configured to move the sheet whose skew has been corrected by the skew correction unit in the width direction, Wherein, in a case where the first sheet is conveyed, after the image forming unit forms a first side image on a first side of the first sheet and before the image forming unit forms a second side image on a second side of the first sheet, the control unit controls the moving unit to move the pair of reverse rollers conveying the first sheet in the width direction, the skew correction unit corrects skew of the first sheet, and controls the other moving unit to move the first sheet in the width direction, and Wherein, in a case where the second sheet is conveyed, after the image forming unit forms a first-side image on a first side of the second sheet and before the image forming unit forms a second-side image on a second side of the second sheet, the skew correcting unit corrects skew of the second sheet, and the other moving unit moves the second sheet in the width direction.
  5. 5. The image forming apparatus according to any one of claims 1 to 4, further comprising a detection unit configured to detect a position of the sheet conveyed by the pair of reverse rollers in the width direction, Wherein the control unit is configured to control the moving unit to move the reverse roller pair in the width direction based on the position of the sheet in the width direction detected by the detecting unit.
  6. 6. An image forming apparatus comprising: An image forming unit configured to form an image on a sheet; A first moving unit that is located upstream of the image forming unit in a conveying direction of a sheet and is configured to move the sheet in a width direction orthogonal to the conveying direction by moving in the width direction while nipping the sheet; A re-conveying unit configured to reverse back and forth a sheet on which an image has been formed on a first face by the image forming unit and convey the sheet again to the image forming unit, wherein the re-conveying unit includes a second moving unit configured to move the sheet in the width direction by moving in the width direction while nipping the sheet; An obtaining unit configured to obtain information on a length of the sheet in the conveying direction, and A control unit configured to control the second moving unit based on the information on the length of the sheet obtained by the obtaining unit, Wherein the control unit controls the second moving unit to move the first sheet in the width direction in a state where the first sheet is conveyed, and Wherein the control unit controls the second moving unit not to move the second sheet in the width direction in a case where the second sheet is conveyed, the first sheet having a first length, and the second sheet having a second length greater than the first length.
  7. 7. The image forming apparatus according to claim 6, wherein the control unit is configured to control the first moving unit and the second moving unit such that the first moving unit moves the first sheet in the width direction and the second moving unit moves the first sheet in the width direction in a case where the first sheet is conveyed, and the first moving unit moves the second sheet in the width direction and the second moving unit does not move the second sheet in the width direction in a case where the second sheet is conveyed.
  8. 8. The image forming apparatus according to claim 6, Wherein the re-conveying unit includes a reversing unit configured to convey a sheet in a first direction and then in a second direction opposite to the first direction, and a double-sided conveying unit configured to convey the sheet conveyed by the reversing unit toward the image forming unit, and Wherein the second moving unit is included in the reversing unit.
  9. 9. The image forming apparatus according to claim 6, further comprising: A first detection unit configured to detect a position of the sheet in the width direction, and A second detection unit configured to detect a position of a sheet in the width direction, Wherein the first moving unit is configured to move a sheet in the width direction based on a result of the detection by the first detecting unit, and Wherein the second moving unit is configured to move a sheet in the width direction based on a result of the detection by the second detecting unit.
  10. 10. The image forming apparatus according to any one of claims 6 to 9, Wherein the re-conveying unit is configured to perform a skew correction operation for correcting skew of the sheet by abutting against a leading edge of the sheet, and Wherein the re-conveying unit performs the skew correction operation in a case where the sheet has the first length or the second length.
  11. 11. An image forming apparatus comprising: An image forming unit configured to form an image on a sheet; a reversing roller pair configured to nip a sheet on which an image is formed by the image forming unit and rotate in a first direction and then rotate in a second direction to reverse and convey the sheet, the second direction being opposite to the first direction; a moving unit configured to move the reversing roller pair in a width direction of a sheet, the width direction being orthogonal to a conveying direction of the sheet, in a state where the sheet is nipped by the reversing roller pair; An obtaining unit configured to obtain information on a length of the sheet in the conveying direction, and A control unit configured to control the moving unit based on the information on the length of the sheet obtained by the obtaining unit, Wherein, in a case where the first sheet is reversed and conveyed, the control unit controls the moving unit to move the reversing roller pair conveying the first sheet in the width direction, and Wherein, in a case where a second sheet is reversed and conveyed, the control unit controls the moving unit to restrict movement of the pair of reversing rollers conveying the second sheet in the width direction, a length of the first sheet in the conveying direction being a first length, and a length of the second sheet in the conveying direction being a second length that is greater than the first length.
  12. 12. The image forming apparatus according to claim 11, wherein in a case where the second sheet is reversed and conveyed, the control unit controls the moving unit so that the moving unit does not move the reversing roller pair conveying the second sheet in the width direction.
  13. 13. The image forming apparatus according to claim 11 or 12, Wherein, in a case where the second sheet is reversed and conveyed, the control unit controls the movement unit to restrict the movement amount of the reversing roller pair conveying the second sheet in the width direction to not more than a predetermined amount, and Wherein the control unit is configured to control, in a case where the first sheet is reversed and conveyed, the moving unit to allow the reversing roller pair conveying the first sheet to move in the width direction more than the predetermined amount.

Description

Image forming apparatus having a plurality of image forming units Technical Field The present invention relates to an image forming apparatus that forms an image on a sheet. Background In general, a sheet conveyed in an image forming apparatus such as a copier may be laterally deviated in a width direction orthogonal to a sheet conveying direction. If an image is formed on a laterally offset sheet, the image may be printed off the center position in the width direction of the sheet. As discussed in japanese patent application laid-open No.2009-143643, a shift (shift) mechanism for detecting the position of an end portion of a sheet in the width direction and correcting the lateral deviation (positional deviation) of the sheet before forming an image on the sheet is thus known. As discussed in japanese patent application laid-open No.6-250464, some known image forming apparatuses include a reversing mechanism for folding back a sheet and conveying the sheet to form an image on a surface of the sheet opposite to a position where an image has been formed. If an inversion-shift mechanism including both the shift mechanism and the inversion mechanism shifts a skewed sheet transversely in the sheet conveyance direction by a long distance, the apparatus increases in size because a large space in the width direction is to be provided. Disclosure of Invention According to an aspect of the present invention, an image forming apparatus includes an image forming unit configured to form an image on a sheet, a reversing roller pair configured to nip the sheet on which the image is formed and rotate in a first direction and then rotate in a second direction opposite to the first direction to reverse and convey the sheet, a moving unit configured to move the reversing roller pair in a width direction of the sheet in a state in which the sheet is nipped by the reversing roller pair, the width direction being orthogonal to a conveying direction of the sheet, an obtaining unit configured to obtain information about a length of the sheet in the conveying direction, and a control unit configured to control the moving unit based on the information about the length of the sheet obtained by the obtaining unit, wherein in a case in which a first sheet is reversed and conveyed, the control unit controls a movement amount of the reversing roller pair that will convey the first sheet in the width direction and a case in which a second sheet is reversed and a length of the first sheet is conveyed in the first direction, and wherein the length of the control unit controls the movement amount of the reversing roller pair in the width direction and the first direction is smaller than the length of the first sheet. Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. Drawings Fig. 1 is an overall schematic diagram illustrating a printer (image forming apparatus) according to a first exemplary embodiment. Fig. 2 is a perspective view illustrating an alignment unit. Fig. 3 is a control block diagram illustrating a control unit. Fig. 4 is a flowchart illustrating a skew correction operation and a shift operation to be performed by the alignment unit. Fig. 5A is a plan view illustrating a state in which the sheet is conveyed askew toward the registration roller pair. Fig. 5B is a plan view illustrating a state in which the end position of the sheet abutting against the registration roller pair is detected. Fig. 5C is a plan view illustrating a state in which the sheet is conveyed by the registration roller pair. Fig. 5D is a plan view illustrating a state in which the sheet is shifted by the registration roller pair. Fig. 6 is a perspective view illustrating the reverse conveyance unit. Fig. 7 is a flowchart illustrating a shift operation to be performed by the inversion transfer unit. Fig. 8A is a schematic diagram illustrating a state in which the sheet is conveyed toward the reverse shift unit. Fig. 8B is a schematic diagram illustrating a state in which the sheet is stopped by the reverse shift unit. Fig. 8C is a schematic diagram illustrating a state in which the reversed sheet is conveyed by the reversing shift unit. Fig. 9 is a perspective view illustrating a second duplex transfer unit. Fig. 10 is a flowchart illustrating a skew correction operation of the second duplex conveying unit. Fig. 11 is a perspective view illustrating a second duplex transfer unit according to a second exemplary embodiment. Fig. 12 is a control block diagram illustrating a control unit. Fig. 13 is a flowchart illustrating a skew correction operation and a shift operation to be performed by the second duplex conveying unit. Fig. 14A and 14B are diagrams illustrating a state in which a sheet is conveyed askew. Detailed Description [ Image Forming apparatus ] First, a first exemplary embodiment of the present invention will be described. The image forming apparatus