Image forming apparatus, control method therefor, and storage medium

Patent metadata

Field	Value
Publication number	US-10895839-B2
Application number	US-201615171567-A
Country	US
Kind code	B2
Filing date	Jun 2, 2016
Priority date	Sep 5, 2011
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

The number of circulatable sheets and the conveying speed of a sheet are decided by referring to a storage unit which stores the number of circulatable sheets and the conveying speed of a sheet in correspondence with the type and size of a sheet, and the resolution of an image to be printed. It is determined whether the conveying speed of the feed surface of a sheet to be fed next to the printing unit and that of a feed surface to be refed next to the printing unit coincide with each other. It is determined whether the conveying speed of the feed surface of the sheet to be fed next to the printing unit and that of the feed surface or the refeed surface of a sheet immediately previously fed to the printing unit differ from each other.

First claim

What is claimed is:

1. An image forming apparatus comprising:
a feeding unit configured to feed a plurality of sheets to a conveyance path;
a conveying unit configured to convey the plurality of sheets fed from the feeding unit along the conveyance path, the conveying unit conveying the plurality of sheets at a first conveying speed in a case where a resolution of an image to be formed is a first resolution, and conveying the plurality of sheets at a second conveying speed, being slower than the first conveying speed, in a case where a resolution of an image to be formed is a second resolution being higher than the first resolution;
an image forming unit configured to form an image on each of the plurality of sheets in the conveyance path;
a re-feeding unit configured to re-feed the sheet having the image formed on a first surface thereof to the conveyance path so as to form an image on a second surface thereof; and
a control unit configured to control the re-feeding unit to re-feed a first sheet, which is one of the plurality of sheets, and control the feeding unit to feed a second sheet, which is one of the plurality of sheets and is subsequent to the first sheet, such that:
the re-feeding of the first sheet to the conveyance path is performed after feeding of the second sheet to the conveyance path in a case where a type and a size of the first sheet and the second sheet are the same, and a resolution of an image on the first surface of the second sheet and a resolution of the first surface of the first sheet are both the first resolution; and
the feeding of the second sheet to the conveyance path is performed after re-feeding of the first sheet to the conveyance path in a case where a type and a size of the first sheet and the second sheet are the same, a resolution of an image on the first surface of the second sheet is the first resolution, and a resolution of an image on the first surface of the first sheet is the second resolution.

2. The image forming apparatus according to claim 1 , wherein the image forming unit comprises:
a photosensitive drum;
a polygon mirror;
a laser emitting unit configured to emit a laser beam corresponding to image data on the photosensitive drum via the polygon mirror so that the image is formed on the photosensitive drum; and
a transfer unit configured to transfer the image on the photosensitive drum into the plurality of sheets.

3. The image forming apparatus according to claim 2 , wherein a rotation number of the polygon mirror in the second resolution is the same as a rotation number of the polygon mirror in the first resolution.

4. The image forming apparatus according to claim 1 , wherein the first conveying speed and the second conveying speed are conveying speeds at a transfer unit.

5. The image forming apparatus according to claim 1 , wherein the first resolution is 600 dpi and the second resolution is 1200 dpi.

6. The image forming apparatus according to claim 1 , wherein the second conveying speed is a half speed of the first conveying speed.

7. The image forming apparatus according to claim 1 , wherein the second sheet is a lead sheet waiting for feeding.

8. The image forming apparatus according to claim 1 , wherein the control unit controls the feeding unit to feed the second sheet after an image formation to the second surface of the first sheet is performed in a case where the resolution of an image formed on the first surface of the second sheet is different from the resolution of the image on the first surface of the first sheet.

9. The image forming apparatus according to claim 1 , wherein the control unit discharges all remaining sheets including the first sheet from the apparatus and then controls the conveying unit to convey the second sheet to the conveyance path.

10. The image forming apparatus according to claim 1 , wherein the control unit compares the resolution of the image on the first surface of the first sheet with the resolution of the image on the first surface on the second sheet at a timing before feeding the second sheet and after feeding the first sheet from the feeding unit.

11. The image forming apparatus according to claim 1 , wherein the control unit determines an image forming order and a sheet feeding order based on a circulating sheet number.

12. The image forming apparatus according to claim 1 , wherein the first surface is a front surface of a sheet to which a double sided printing is performed and the second surface is a back surface of the sheet, which is one or the plurality of sheets, to which a double sided printing is performed.

13. The image forming apparatus according to claim 1 , further comprising a receiving unit configured to receive image data,
wherein the image forming unit forms the images on the plurality of sheets based on the image data received by the receiving unit.

14. The image forming apparatus according to claim 1 , wherein, in a single sided printing, the control unit discharges a sheet, which is one of the plurality of sheets, on which an image is formed by the image forming unit from the apparatus without passing through a double-sided circulation path.

15. An image forming apparatus comprising:
a feeding unit configured to feed a plurality of sheets to a conveyance path;
a conveying unit configured to convey the plurality of sheets fed from the feeding unit along the conveyance path, the conveying unit conveying the plurality of sheets at a first conveying speed in a case where a resolution of an image to be formed is a first resolution, and conveying the plurality of sheets at a second conveying speed, being slower than the first conveying speed, in a case where a resolution of an image to be formed is a second resolution being higher than the first resolution;
an image forming unit configured to form an image on each of the plurality of sheets in the conveyance path;
a re-feeding unit configured to re-feed the sheet having the image formed on a first surface thereof to the conveyance path so as to form an image on a second surface thereof; and
a control unit configured to control the re-feeding unit to re-feed a first sheet, which is one of the plurality of sheets, and control the feeding unit to feed a second sheet, which is one of the plurality of sheets and is subsequent to the first sheet, such that:
the re-feeding of the first sheet to the conveyance path is performed after feeding of the second sheet to the conveyance path in a case where a type and a size of the first sheet and the second sheet are the same, and a resolution of an image on the first surface of the second sheet and a resolution of an image on the second surface of the first sheet are both the first resolution; and
the feeding of the second sheet to the conveyance path is performed after re-feeding of the first sheet to the conveyance path in a case where a type and a size of the first sheet and the second sheet are the same, a resolution of an image on the first surface of the second sheet is the first resolution, and a resolution of an image on the second surface of the first sheet is the second resolution.

16. The image forming apparatus according to claim 15 , wherein the image forming unit comprises:
a photosensitive drum;
a polygon mirror;
a laser emitting unit configured to emit a laser beam corresponding to image data on the photosensitive drum via the polygon mirror so that the image is formed on the photosensitive drum; and
a transfer unit configured to transfer the image on the photosensitive drum into the plurality of sheets.

17. The image forming apparatus accordi

Assignees

• Canon Kk

Inventors

• Miyajima Jun

Classifications

• G03G15/23 Primary

  specially adapted for copying both sides of an original or for copying on both sides of a recording or image-receiving material · CPC title

• G03G15/234 Primary

  by inverting and refeeding the image receiving material with an image on one face to the recording member to transfer a second image on its second face, e.g. by using a duplex tray; Details of duplex trays or inverters · CPC title

• G03G2215/00949

  Copy material feeding speed switched according to current mode of the apparatus, e.g. colour mode · CPC title

• G03G15/6579 Primary

  Refeeding path for composite copying · CPC title

• G03G15/6564

  with correct timing of sheet feeding · CPC title