Image forming apparatus to correct timing of image formation

Patent metadata

Field	Value
Publication number	US-10254699-B2
Application number	US-201715668480-A
Country	US
Kind code	B2
Filing date	Aug 3, 2017
Priority date	Aug 12, 2016
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

An image forming apparatus includes image bearing members, an intermediate transfer member, a transfer unit, a control unit, and image forming units respectively corresponding to the image bearing members and each configured to form and transfer an image to the intermediate transfer member, which is then transferred to the conveyed recording material. Image patterns on the intermediate transfer member are detected for positional deviation detection. In a first mode, timing of image formation is determined using a first reference. In a second mode, timing of image formation is determined using a second reference. Based on timings at which formed image patterns are detected, the control unit, in the second mode, corrects timing of image formation performed by a second image forming unit or corrects timing at which the recording material is conveyed to the transfer unit.

First claim

What is claimed is:

1. An image forming apparatus comprising:
a plurality of image bearing members;
an intermediate transfer member;
a plurality of image forming units respectively corresponding to the plurality of image bearing members and each configured to form an image on the corresponding image bearing member and to transfer the image formed on the corresponding image bearing member to the intermediate transfer member;
a conveyance unit configured to convey a recording material;
a transfer unit configured to transfer the image formed on the intermediate transfer member to the recording material conveyed by the conveyance unit;
a detection unit configured to detect image patterns for positional deviation detection respectively formed on the intermediate transfer member by the plurality of image forming units; and
a control unit configured to perform control by switching between a first mode, which determines, with a first image forming unit among the plurality of image forming units used as a reference, timing of image formation performed by a second image forming unit different from the first image forming unit, and a second mode, which determines timing of image formation performed by the second image forming unit with the second image forming unit used as a reference,
wherein, based on timings at which, in the first mode, the image pattern formed on the intermediate transfer member by the first image forming unit and the image pattern formed on the intermediate transfer member by the second image forming unit are respectively detected by the detection unit, the control unit, in the second mode, corrects timing of image formation performed by the second image forming unit or corrects timing at which the recording material is conveyed to the transfer unit by the conveyance unit.

2. The image forming apparatus according to claim 1 ,
wherein, in a case where an image with a plurality of colors is formed in the first mode, the control unit causes the first image forming unit to start image formation at timing at which a first predetermined time has elapsed from when a reference signal is output, and
wherein, in a case where an image with a single color is formed in the second mode, the control unit causes the second image forming unit to start image formation at timing at which the first predetermined time corrected based on a result of detection by the detection unit has elapsed from when the reference signal is output.

3. The image forming apparatus according to claim 2 , wherein, in a case where an image with a plurality of colors is formed in the first mode, the control unit causes the second image forming unit to start image formation at timing at which a second predetermined time corrected based on a result of detection by the detection unit has elapsed from timing of image formation performed by the first image forming unit.

4. The image forming apparatus according to claim 1 ,
wherein, in a case where an image with a plurality of colors is formed in the first mode, the control unit causes the first image forming unit to start image formation at timing at which a first predetermined time has elapsed from when a reference signal is output, and causes the conveyance unit to convey the recording material to the transfer unit at timing at which a conveyance interval time has elapsed from when the reference signal is output, and
wherein, in a case where an image with a single color is formed in the second mode, the control unit causes the second image forming unit to start image formation at timing at which the first predetermined time has elapsed from when the reference signal is output, and causes the conveyance unit to convey the recording material to the transfer unit at timing at which the conveyance interval time corrected based on a result of detection by the detection unit has elapsed from when the reference signal is output.

5. The image forming apparatus according to claim 1 ,
wherein each of the plurality of image forming units includes a charging portion configured to electrically charge the corresponding image bearing member, an exposure portion configured to emit light to the image bearing member electrically charged by the charging portion to form an electrostatic latent image on the image bearing member, a developing portion configured to develop the electrostatic latent image formed by the exposure portion to form a toner image on the image bearing member, and a primary transfer portion configured to transfer the toner image formed by the developing portion to the intermediate transfer member, and
wherein, when the determined timing of image formation is reached, the image forming unit causes the exposure portion to start emitting light to the corresponding image bearing member.

6. The image forming apparatus according to claim 1 , wherein the detection unit includes a light-emitting portion and a light-receiving portion, which receives light reflected from a surface of the intermediate transfer member or the image patterns formed on the intermediate transfer member.

7. The image forming apparatus according to claim 1 ,
wherein the plurality of image forming units respectively corresponds to colors yellow, magenta, cyan, and black, and
wherein the first image forming unit is an image forming unit corresponding to yellow, and the second image forming unit is an image forming unit corresponding to black.

8. The image forming apparatus according to claim 1 ,
wherein the control unit obtains positional deviation amount between the image pattern formed by the first image forming unit and the image pattern formed by the second image forming unit based on the timings at which, in the first mode, the image pattern formed by the first image forming unit and the image pattern formed by the second image forming unit are respectively detected by the detection unit, and
wherein the control unit, in the second mode, corrects the timing of image formation performed by the second image forming unit or corrects the timing at which the recording material is conveyed to the transfer unit by the conveyance unit based on the positional deviation amount.

9. The image forming apparatus according to claim 1 ,
wherein the timing at which the image pattern formed by the first image forming unit is detected by the detection unit is a central timing of a timing at which a leading edge of the image pattern formed by the first image forming unit is detected by the detection unit and a timing at which a trailing edge of the image pattern formed by the first image forming unit is detected by the detection unit in a moving direction of the intermediate transfer member, and
wherein the timing at which the image pattern formed by the second image forming unit is detected by the detection unit is a central timing of a timing at which a leading edge of the image pattern formed by the second image forming unit is detected by the detection unit and a timing at which a trailing edge of the image pattern formed by the second image forming unit is detected by the detection unit in the moving direction of the intermediate transfer member.

10. The image forming apparatus according to claim 1 , wherein the conveyance unit temporarily stops conveying the recording material at a position in upstream side of the transfer unit in the conveyance direction of the recording material and resumes conveying the recording material based on the corrected timing at which the recording material is conveyed to the transfer unit.

11. The image forming apparatus according to claim 1 , wherein the conveyance unit changes a conveyance speed of the recording material based on the corrected timing at which the recording materi

Assignees

• Canon Kk

Inventors

• Kanno Naoki
• Yoshizawa Ryuichi

Classifications

• G03G2215/0106

  At least one recording member having plural associated developing units · CPC title

• G03G15/1675 Primary

  with means for controlling the bias applied in the transfer nip · CPC title

• G03G15/5058

  using a test patch · CPC title

• G03G15/6561 Primary

  for sheet registration · CPC title

• G03G2215/0116

  Rotating set of recording members · CPC title