Developing apparatus and image forming apparatus

• US 20030128997A1
• Filed: 11/18/2002
• Published: 07/10/2003
• Est. Priority Date: 12/28/2001
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Shibata, Masahiro, Tsuruya, Satoshi, Sakaizawa, Katsuhiro, Shinohara, Seiichi
• Granted Patent: US 6,751,423 B2
• Time in Patent Office: Days
• US Class Current: 399/55
• CPC Class Codes: G03G 15/0812 characterised by the developer regulating means, e.g. structure of doctor blade

Abstract

A developing apparatus includes a developer carrying member for carrying a developer to develop an electrostatic image formed on an image bearing member with the developer; a developer regulating member for regulating an amount of the developer carried on the developer carrying member; and control means for controlling a potential difference between the developer carrying member and the developer regulating member such that the potential difference is larger in at least a part of non-developing operation than in a developing operation when the developer carrying member carries the developer control means for controlling a potential difference between the developer carrying member and the developer regulating member such that the potential difference is larger in at least a part of non-developing operation than in a developing operation when the developer carrying member carries the developer.

Claims

1. A developing apparatus comprising:

a developer carrying member for carrying a developer to develop an electrostatic image formed on an image bearing member with the developer;

a developer regulating member for regulating an amount of the developer carried on said developer carrying member; and

control means for controlling a potential difference between said developer carrying member and said developer regulating member such that the potential difference is larger in at least a part of non-developing operation than in a developing operation when said developer carrying member carries the developer.

2. An apparatus according to claim 1, wherein the potential applied to said developer regulating member is larger than a potential applied to said developer carrying member, toward a polarity of a regular charging polarity of toner in the developer.

3. An apparatus according to claim 1, wherein the potential applied to said developer regulating member has a polarity which is the same as a regular charging polarity!kP of toner in the developer, and an absolute value of the potential applied to said developer regulating member is larger than an absolute value of a potential applied to said developer carrying member.

4. An apparatus according to claim 1, wherein said potential difference is 60-500V.

5. An apparatus according to claim 1, wherein said developer contains toner particles and auxiliary particles which are externally added thereto and which have a charging polarity!kP opposite that of the toner particles.

6. An apparatus according to claim 5, wherein said toner has a shape factor SF-1 of 100-160, and a shape factor SF-2 of 100-140.

7. An apparatus according to claim 6, wherein said toner is non-magnetic.

8. An apparatus according to claim 1, further comprising a single voltage applying means for applying a voltage to said developer carrying member and said developer regulating member, and voltage delaying circuit for delaying a voltage applied to said developer regulating member, wherein the applied voltage is changed by said voltage applying means, and a change of the applied voltage is delayed by said voltage delaying circuit.

9. An apparatus according to claim 8, wherein said voltage applying means applies the voltage which is higher when the applied voltage is changed than when the developing operation is carried out.

10. An apparatus according to claim 8, wherein the potential difference is produced by impulse-like application of the voltage by said voltage applying means.

11. An apparatus according to claim 8, wherein a plurality of such developer carrying members and such developer regulating members are provided, and said apparatus further comprises a plurality of electrode contact portions for applying voltages to said developer carrying members and said developer regulating members.

12. An apparatus according to claim 11, wherein said plurality of said developer carrying members and said developer regulating members are provided in developing devices, respectively, and said apparatus further comprises a developing device holding member for rotatably holding said developing devices.

13. An apparatus according to claim 1, wherein said at least a part of the non-developing operation includes an instance when a rotation of said developer carrying member starts.

14. An apparatus according to claim 1, wherein said developer carrying member has a surface resistance value of 8×

10⁵-1×

10¹² Ohm, and a resistance value with respect to a thickness direction is 3×

10⁵-5×

10⁸ Ohm.

15. An apparatus according to claim 14, wherein the surface resistance value is larger than the resistance value with respect to the thickness direction by at least one order.

16. An apparatus according to claim 1, wherein said developer carrying member and said developer regulating member are provided in a cartridge which is detachably mountable to a main assembly of an image forming apparatus.

17. An apparatus according to claim 8, wherein said developer carrying member, said developer regulating member and said voltage delaying circuit are provided in a cartridge detachably mountable to a main assembly of an image forming apparatus.

18. A developing apparatus comprising:

a developer carrying member for carrying a developer to develop an electrostatic image formed on an image bearing member with the developer;

a developer regulating member for regulating an amount of the developer carried on said developer carrying member; and

control means for controlling a potential difference between said developer carrying member and said developer regulating member, said control means making the potential difference substantially zero during a developing operation, and provides a non-zero potential difference in at least a part of non-developing operation when said developer carrying member carries the developer.

19. An apparatus according to claim 18, wherein the potential applied to said developer regulating member is larger than a potential applied to said developer carrying member, toward a polarity of a regular charging polarity of toner in the developer.

20. An apparatus according to claim 18, wherein the potential applied to said developer regulating member has a polarity which is the same as a regular charging polarity!kP of toner in the developer, and an absolute value of the potential applied to said developer regulating member is larger than an absolute value of a potential applied to said developer carrying member.

21. An apparatus according to claim 18, wherein said potential difference is 60-500V.

22. An apparatus according to claim 18, wherein said developer contains toner particles and auxiliary particles which are externally added thereto and which have a charging polarity!kP opposite that of the toner particles.

23. An apparatus according to claim 22, wherein said toner has a shape factor SF-1 of 100-160, and a shape factor SF-2 of 100-140.

24. An apparatus according to claim 23, wherein said toner is non-magnetic.

25. An apparatus according to claim 18, further comprising a single voltage applying means for applying a voltage to said developer carrying member and said developer regulating member, and voltage delaying circuit for delaying a voltage applied to said developer regulating member, wherein the applied voltage is changed by said voltage applying means, and a change of the applied voltage is delayed by said voltage delaying circuit.

26. An apparatus according to claim 25, wherein said voltage applying means applies the voltage which is higher when the applied voltage is changed than when the developing operation is carried out.

27. An apparatus according to claim 25, wherein the potential difference is produced by impulse-like application of the voltage by said voltage applying means.

28. An apparatus according to claim 25, wherein a plurality of such developer carrying members and such developer regulating members are provided, and said apparatus further comprises a plurality of electrode contact portions for applying voltages to said developer carrying members and said developer regulating members.

29. An apparatus according to claim 28, wherein said plurality of said developer carrying members and said developer regulating members are provided in developing devices, respectively, and said apparatus further comprises a developing device holding member for rotatably holding said developing devices.

30. An apparatus according to claim 18, wherein said at least a part of the non-developing operation includes an instance when a rotation of said developer carrying member starts.

31. An apparatus according to claim 18, wherein said developer carrying member has a surface resistance value of 8×

10⁵-1×

10¹² Ohm, and a resistance value with respect to a thickness direction is 3×

10⁵-5×

10⁸ Ohm.

32. An apparatus according to claim 31, wherein the surface resistance value is larger than the resistance value with respect to the thickness direction by at least one order.

33. An apparatus according to claim 18, wherein said developer carrying member and said developer regulating member are provided in a cartridge which is detachably mountable to a main assembly of an image forming apparatus.

34. An apparatus according to claim 25, wherein said developer carrying member, said developer regulating member and said voltage delaying circuit are provided in a cartridge detachably mountable to a main assembly of an image forming apparatus.

35. An image forming apparatus comprising:

an image bearing member;

a developer carrying member for carrying a developer to develop an electrostatic image formed on said image bearing member with the developer;

a developer regulating member for regulating an amount of the developer carried on said developer carrying member; and

control means for controlling a potential difference between said developer carrying member and said developer regulating member such that potential difference is larger in at least a part of non-image-forming operation than in an image forming operation when said developer carrying member carries the developer.

36. An image forming apparatus comprising:

an image bearing member;

a developer carrying member for carrying a developer to develop an electrostatic image formed on said image bearing member with the developer;

a developer regulating member for regulating an amount of the developer carried on said developer carrying member; and

control means for controlling a potential difference between said developer carrying member and said developer regulating member, said control means making the potential difference substantially zero during a developing operation, and provides a non-zero potential difference in at least a part of non-image-forming operation when said developer carrying member carries the developer.