Image forming apparatus with cleaning sequence of contact charging members

• US 20010026694A1
• Filed: 12/21/2000
• Published: 10/04/2001
• Est. Priority Date: 12/27/1999
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Sekiguchi, Manami, Sakaizawa, Katsuhiro
• Granted Patent: US 6,438,331 B2
• Time in Patent Office: Days
• US Class Current: 399/50
• CPC Class Codes: G03G 15/0225 provided with means for cleaning the charging member
• CPC Class Codes: G03G 2221/0005 Cleaning of residual toner

Abstract

The present invention provides an image forming apparatus, which has an image bearing body for bearing a toner image, transferring device for transferring a toner image on the image bearing body to a transferring material, a charging member for charging the image bearing body, having a residual toner after the transfer on a surface thereof by being brought into contact therewith, electrostatic image forming device for forming an electrostatic image on the image bearing body charged by the charging member, developing device for collecting the residual toner on the image bearing body while developing the electrostatic image on the image bearing body by using a toner charged in the same polarity as a charging polarity generated by the charging member, control device for controlling a voltage to be applied to the charging member, and a cleaning sequence for performing a cleaning of the charging member by applying a voltage not higher than a discharge threshold and equal to the polarity of the toner after a discharge voltage reverse to the polarity of the toner is applied onto the charging member, when an image formation is not effected.

Claims

1. An image forming apparatus, comprising:

an image bearing body for bearing a toner image;

transferring means for transferring a toner image on said image bearing body to a transferring material;

a charging member for charging said image bearing body having a residual toner after the transfer on a surface thereof by being brought into contact therewith;

electrostatic image forming means for forming an electrostatic image on said image bearing body charged by said charging member;

developing means for collecting the residual toner on said image bearing body while developing the electrostatic image on said image bearing body by using a toner charged in the same polarity as a charging polarity generated by said charging member;

control means for controlling a voltage to be applied to said charging member; and

a cleaning sequence for performing a cleaning of said charging member by applying a voltage not higher than a discharge threshold and equal to the polarity of the toner after a discharge voltage reverse to the polarity of the toner is applied onto said charging member, when an image formation is not effected.

2. An image forming apparatus according to claim 1, wherein the cleaning sequence is performed for a preparatory period performed after the image formation.

3. An image forming apparatus according to

claim 1

, wherein the cleaning sequence is performed for a post-processing period performed after the image formation.

4. An image forming apparatus according to

claim 1

, wherein the cleaning sequence is performed between the image formation and the image formation in a succession of image formation.

5. An image forming apparatus according to

claim 1

, wherein the cleaning sequence is performed at a restart of said apparatus.

6. An image forming apparatus according to

claim 1

, wherein the discharge voltage reverse to the polarity of the toner, to be applied during the cleaning sequence, is a voltage controlled so that a constant current is effected.

7. An image forming apparatus according to

claim 1

, wherein said developing means includes a toner carrying body being in contact with said image bearing body.

8. An image forming apparatus according to

claim 1

, further comprising a distorting member for distorting a residual toner image, said image forming apparatus being provided at an upper stream side in a moving direction of said image bearing body from said charging member.

9. An image forming apparatus according to

claim 1

, wherein said charging member is formed by a roller shape and dynamic friction coefficient of a surface of said charging member is 0.01 to 0.4.

10. An image forming apparatus according to

claim 1

, wherein a shape factor SF1 of the toner is 100 to 160, and a shape factor SF2 of the toner is 100 to 140.