Image forming apparatus

• US 20020048468A1
• Filed: 09/07/2001
• Published: 04/25/2002
• Est. Priority Date: 09/07/2000
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Suzuki, Jun, Sakaizawa, Katsuhiro, Shimura, Masaru, Tsuruya, Satoshi
• Granted Patent: US 6,560,426 B2
• Time in Patent Office: Days
• US Class Current: 399/150
• CPC Class Codes: G03G 15/0241 by bringing charging powder particles into contact with the member to be charged, e.g. by means of a magnetic brush
• CPC Class Codes: G03G 21/0064 using the developing unit, e.g. cleanerless or multi-cycle apparatus

Abstract

An image forming apparatus includes an image bearing member; electrostatic image forming means for forming an electrostatic image on said image bearing member, said electrostatic image forming means including a flexible charge member for electrically charging said image bearing member, said charge member forming a nip between said image bearing member and itself and is supplied with an oscillating voltage, wherein electroconductive particles are provided in the nip; and developing means for developing an electrostatic image formed on said image bearing member with a developer, said developing means being capable of a residual developer on said image bearing member, wherein a frequency f (cycle/sec) of the oscillating voltage and a peripheral speed v (mm/sec) of said image bearing member satisfy ¦f/v¦≧12 (cycle/mm).

Claims

1. An image forming apparatus comprising:

an image bearing member;

electrostatic image forming means for forming an electrostatic image on said image bearing member, said electrostatic image forming means including a flexible charge member for electrically charging said image bearing member, said charge member forming a nip between said image bearing member and itself and is supplied with an oscillating voltage, wherein electroconductive particles are provided in the nip; and

developing means for developing an electrostatic image formed on said image bearing member with a developer, said developing means being capable of a residual developer on said image bearing member, wherein a frequency f (cycle/sec) of the oscillating voltage and a peripheral speed v (nm/sec) of said image bearing member satisfy

¦

f/v¦

≧

12 (cycle/mm).

2. An apparatus according to claim 1, wherein said charge member is provided with a foam member at its surface.

3. An apparatus according to claim 1, wherein the oscillating voltage is applied when said charge member charges said image bearing member, for image formation.

4. An apparatus according to claim 1, wherein the oscillating voltage has a peak-to-peak voltage which is not less than 500V and less than an applied voltage when a potential of said image bearing member converges.

5. An apparatus according to claim 1, wherein the oscillating voltage has a peak-to-peak voltage which is not less than 500V and less than 1200V.

6. An apparatus according to claim 1, wherein the electroconductive particles have a particle size of 0.1-3 μ

m, and have a resistance of not more than 10¹² Ω

cm.

7. An apparatus according to claim 1, wherein said charge member is driven so as to provide a peripheral speed difference relative to said image bearing member.

8. An apparatus according to claim 1, wherein a moving direction of said charge member is opposite from a moving direction of said image bearing member.

9. An apparatus according to claim 1, wherein said charge member is in the form of a roller.

10. An apparatus according to claim 1, wherein said image bearing member is a photosensitive member, and said electrostatic image forming means includes exposure means for exposing said image bearing member charged by said charge member.

11. An apparatus according to claim 1, wherein said developing means includes a developer carrying member for charring the developer, and said developer carrying member is contactable to said image bearing member.

12. An apparatus according to claim 1, wherein the developer has a shape factor SF-i of 100-150 and a shape factor of 100-140.

13. An apparatus according to claim 1, wherein said developing means is capable of collecting the residual developer from said image bearing member simultaneously with a developing operation.

14. An apparatus according to claim 1, further comprising transferring means for transferring a developed image from said image bearing member onto a transfer material.

15. An apparatus according to claim 1, wherein said apparatus comprises a plurality of such image bearing members and transferring means for transferring developed image from said image bearing members to a transfer material.

16. An apparatus according to claim 14 or 15, wherein the transfer material is a sheet or an intermediary transfer member.

17. An apparatus according to claim 15, wherein an image on one of said image bearing members on which the image is first developed, is developed with a developer having a lowest spectral luminous efficacy.

18. An apparatus according to claim 1, wherein said image bearing member and said charge member are provided in a process cartridge which is detachably mountable a main assembly of said apparatus.

19. An apparatus according to claim 1, wherein said charge member electrically charges said image bearing member through injection charging.