IMAGE FORMING APPARATUS

• US 20080260444A1
• Filed: 03/27/2008
• Published: 10/23/2008
• Est. Priority Date: 04/20/2007
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ikeda, Yoshimichi
• Granted Patent: US 9,217,978 B2
• Time in Patent Office: Days
• US Class Current: 399/388
• CPC Class Codes: G03G 15/6564 with correct timing of sheet feeding
• CPC Class Codes: G03G 2215/00599 Timing, synchronisation
• CPC Class Codes: G03G 2215/00945 Copy material feeding speed varied over the feed path
• CPC Class Codes: G03G 2215/00949 Copy material feeding speed switched according to current mode of the apparatus, e.g. colour mode
• CPC Class Codes: G03G 2215/0132 vertical medium transport path at the secondary transfer
• CPC Class Codes: G03G 2215/0154 Vibrations and positional disturbances when one member abuts or contacts another member

Abstract

An image forming apparatus capable of setting a plurality of image forming speeds includes a transfer unit configured to transfer an image formed on an image carrier onto a sheet, a paper feed unit configured to feed the sheet, and a control unit configured to control the conveyance speed of the sheet to accelerate and decelerate without stopping the sheet in a section between the paper feed unit and the transfer unit to synchronize the sheet with the image formed on the image carrier. The control unit changes paper feed timing from the paper feed unit according to the image forming speed if the image forming speed is predetermined.

Claims

1. An image forming apparatus comprising a transfer unit configured to transfer an image formed on an image carrier onto a sheet and a paper feed unit configured to feed the sheet, and capable of setting a plurality of image forming speeds used in forming the image on the sheet, accelerating and decelerating a conveyance speed of the sheet without stopping the conveyance of the sheet in a section between the paper feed unit and the transfer unit in order to synchronize the sheet with the image formed on the image carrier, the apparatus comprising:

a conveyance unit configured to convey the sheet fed from the paper feed unit to the transfer unit, and

a control unit configured to control paper feed timing from the paper feed unit;

wherein if the image is formed at a first image forming speed which is a fastest or at a second image forming speed which is a slowest of the plurality of image forming speeds, the control unit feeds the sheet at timing different from the paper feed timing when the sheet is fed at the image forming speed other than the first and the second image forming speeds.

2. The image forming apparatus according to claim 1, wherein if the image forming speed is the first image forming speed, the control unit changes the paper feed timing to timing earlier than the paper feed timing in the case where the image forming speed is other than the first and the second image forming speeds.

3. The image forming apparatus according to claim 1, wherein if the image forming speed is the second image forming speed, the control unit changes the paper feed timing to timing later than the paper feed timing in the case where the image forming speed is other than the first and the second image forming speeds.

4. The image forming apparatus according to claim 1, wherein if the image forming speed is the second image forming speed, the control unit changes the paper feed timing to timing earlier than the paper feed timing in the case where the image forming speed is other than the first and the second image forming speeds, and performs control to stop the conveyance of the sheet when the sheet reaches the conveyance unit, and then restart the conveyance of the sheet.

5. The image forming apparatus according to claim 1, further comprising:

an image forming unit configured to form an image on the image carrier;

wherein the paper feed timing is set according to a length of time from when image forming is started at the image forming unit to when the image is conveyed to the transfer unit in the case where the image forming speed is other than the first and the second image forming speeds.

6. The image forming apparatus according to claim 5, wherein the image forming unit includes a plurality of photosensitive members, and the image carrier is an intermediate transfer member configured to carry the image formed on the plurality of the photosensitive members.

7. The image forming apparatus according to claim 1, further comprising a sensor configured to detect the sheet in the section between the paper feed unit and the transfer unit, wherein the control unit controls the conveyance speed of the sheet to accelerate or decelerate in a section between the sensor and the transfer unit according to a length of time that the sheet takes to be transferred from the paper feed unit to the sensor.

8. The image forming apparatus according to claim 1, wherein timing at which the image is formed on the intermediate transfer member is earlier than the paper feed timing from the paper feed unit.

9. The image forming apparatus according to claim 1, wherein the plurality of image forming speeds are set according to a type of the sheet.

10. An image forming apparatus capable of setting a plurality of image forming speeds used in forming an image on a sheet, the apparatus comprising:

a transfer unit configured to transfer the image formed on an image carrier on the sheet;

a paper feed unit configured to feed the sheet, and

a control unit configured to control a conveyance speed of the sheet to accelerate and decelerate without stopping the sheet in a section between the paper feed unit and the transfer unit to synchronize the sheet with the image formed on the image carrier,

wherein the control unit changes paper feed timing from the paper feed unit according to the image forming speed if the image forming speed is predetermined.

11. The image forming apparatus according to claim 10, wherein the predetermined speed is a fastest image forming speed or a slowest image forming speed of the plurality of the image forming speeds.

12. The image forming apparatus according to claim 10, further comprising a sensor configured to detect the sheet in a section between the paper feed unit and the transfer unit,

wherein the control unit controls the conveyance speed of the sheet to accelerate or decelerate in a section between the sensor and the transfer unit according to a length of time that the sheet takes to be transferred from the paper feed unit to the sensor.