Image forming apparatus with transfer member and parallel circuit of grounded electrode and power supply

• US 5,701,569 A
• Filed: 05/16/1996
• Issued: 12/23/1997
• Est. Priority Date: 05/17/1995
• Status: Expired due to Term

• Current Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Original Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Inventors: Hara, Kazuyoshi, Natsuhara, Toshiya, Tanaka, Yasuo, Kanazawa, Masaharu
• Primary Examiner(s): BEATTY, ROBERT B
• Application Number:
  US08/648,750
• Time in Patent Office: 586 Days
• Field of Search: 355/271, 355/272, 355/274, 355/275, 399/302, 399/303, 399/308, 399/314, 399/313
• US Class Current: 399/308
• CPC Class Codes: G03G 15/1605 using at least one intermediate support G03G15/1625 takes precedence
• CPC Class Codes: G03G 15/1675 with means for controlling the bias applied in the transfer nip

Abstract

An image forming apparatus having a toner image carrying member which carries a toner image, an intermediate transfer member or sheet transport type transfer member opposite to the toner image carrying member, a charging device which charges the transfer member for transferring the toner image from the toner image carrying member to the intermediate transfer member or carried sheet, a grounding electrode which contacts the transfer member, an ammeter which measures an electric current through the grounding electrode, and a control device which controls the charging device based on a measured value of the ammeter so as to stabilize said measured value. A power source is connected to the charging device through a resistance and the grounding electrode is in parallel with circuit from the resistance to the toner image carrying member.

Claims

1. An image forming apparatus comprising:

a toner image carrying member which carries a toner image;

an intermediate transfer member opposite to the toner image carrying member;

a charging device which charges the intermediate transfer member for transferring the toner image from the toner image carrying member;

a resistance;

a power source which is connected to the charging device through said resistance and supplies the charging device with electric current; and

a grounding electrode which contacts the intermediate transfer member, said grounding electrode being located so that a circuit from the resistance to the grounding electrode is in parallel with a circuit from the resistance to the toner image carrying member.

2. The image forming apparatus as claimed in claim 1, wherein said toner image carrying member is electrostatic latent image carrying member.

3. The image forming apparatus as claimed in claim 1, wherein said charging device is a conductive roller.

4. The image forming apparatus as claimed in claim 1, wherein said intermediate transfer member is an intermediate transfer belt.

5. The image forming apparatus as claimed in claim 1, further comprising:

a transfer device transferring the toner image from the intermediate transfer member to a recording medium.

6. The image forming apparatus as claimed in claim 5, wherein said transfer device is a conductive roller.

7. The image forming apparatus as claimed in claim 5, wherein said intermediate transfer member is an intermediate transfer belt.

8. The image forming apparatus as claimed in claim 7, further comprising:

a comparing electrode which is connected to the intermediate transfer belt, said comparing electrode being arranged at a downstream side from the charging device with respect to a moving direction of said intermediate transfer belt, and said grounding electrode being arranged at a downstream side from said comparing electrode with respect to the moving direction of said intermediate transfer belt.

9. The image forming apparatus as claimed in claim 1, wherein said grounding electrode is arranged at an upstream side from the charging device with respect to a moving direction of said intermediate transfer member.

10. The image forming apparatus as claimed in claim 9, wherein said charging device is a conductive roller including the resistance.

11. The image forming apparatus as claimed in claim 1, wherein said charging device is a conductive brush.

12. The image forming apparatus as claimed in claim 1, wherein said grounding electrode is a conductive brush.

13. An image forming apparatus comprising:

a toner image carrying member which carries a toner image;

a transfer member opposite to the toner image carrying member;

a charging device which charges the transfer member for transferring the toner image from the toner image carrying member;

a resistance;

a power source which is connected to the charging device through said resistance and supplies the charging device with electric current; and

a grounding electrode which contacts the transfer member, said grounding electrode being located so that a circuit from the resistance to the grounding electrode is in parallel with a circuit from the resistance to the toner image carrying member.

14. The image forming apparatus as claimed in claim 13, wherein said toner image carrying member is electrostatic latent image carrying member.

15. The image forming apparatus as claimed in claim 13, wherein said charging device is a conductive roller.

16. The image forming apparatus as claimed in claim 13, wherein said grounding electrode is arranged at an upstream side from the charging device with respect to a moving direction of said transfer member.

17. The image forming apparatus as claimed in claim 13, wherein said charging device is a conductive roller including the resistance.

18. The image forming apparatus as claimed in claim 13, wherein said charging device is a conductive brush.

19. The image forming apparatus as claimed in claim 13, wherein said grounding electrode is a conductive brush.