DEVELOPING DEVICE

• US 20180284656A1
• Filed: 03/20/2018
• Published: 10/04/2018
• Est. Priority Date: 03/30/2017
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Takahashi, Masafumi, Terada, Ryohei, Sadamitsu, Yushi, Shimoi, Yasuhiro, Koga, Yutaka, Soeta, Yukihiro
• Granted Patent: US 10,331,061 B2
• Time in Patent Office: Days
• CPC Class Codes: G03G 15/0216 by bringing a charging member into contact with the member to be charged, e.g. roller, brush chargers
• CPC Class Codes: G03G 15/0806 on a donor element, e.g. belt, roller complete developer unit G03G15/0896
• CPC Class Codes: G03G 15/0808 characterised by the developer supplying means, e.g. structure of developer supply roller
• CPC Class Codes: G03G 15/0812 characterised by the developer regulating means, e.g. structure of doctor blade
• CPC Class Codes: G03G 15/0865 Arrangements for supplying new developer
• CPC Class Codes: G03G 15/0898 for preventing toner scattering during operation, e.g. seals sealing the donor member G03G15/0817; sealing the magnetic brush G03G15/0942
• CPC Class Codes: G03G 15/0921 Details concerning the magnetic brush roller structure, e.g. magnet configuration
• CPC Class Codes: G03G 15/167 at least one of the recording member or the transfer member being rotatable during the transfer
• CPC Class Codes: G03G 15/2053 Structural details of heat elements, e.g. structure of roller or belt, eddy current, induction heating

Abstract

A developing device includes an accommodating casing, a rotatable developer carrying member, a regulating portion, a magnetic flux generating portion including a first magnetic pole and a second magnetic pole which have the same polarity, and a cover portion provided downstream of the developing region and upstream of a maximum magnetic flux density position of the second magnetic pole with respect to a rotational direction of the developer carrying member. The cover portion is disposed between the casing and the developer carrying member. A downstream end of the cover portion with respect to the rotational direction is in a side upstream, with respect to the rotational direction, of a minimum magnetic flux density position between the first magnetic pole and the second magnetic pole with respect to the rotational direction.

Claims

1. A developing device comprising:

an accommodating casing configured to accommodate a developer;

a rotatable developer carrying member provided in said accommodating casing and configured to develop, in a developing region, an electrostatic latent image formed on an image bearing member;

a regulating portion provided below said developer carrying member with respect to a vertical direction and configured to regulate an amount of the developer on said developer carrying member;

a magnetic flux generating portion provided inside said developer carrying member and including a first magnetic pole provided downstream of the developing region with respect to a rotational direction of said developer carrying member and a second magnetic pole which is provided adjacently downstream of said first magnetic pole with respect to the rotational direction and which has a polarity identical to a polarity of said first magnetic pole; and

a cover portion provided downstream of the developing region and upstream of a maximum magnetic flux density position of said second magnetic pole with respect to the rotational direction, said cover portion being disposed between said casing and said developer carrying member over a rotational axis direction of said developer carrying member with a gap between itself and said casing and with a gap between itself and said developer carrying member,

wherein a downstream end of said cover portion with respect to the rotational direction is in a side upstream, with respect to the rotational direction, of a minimum magnetic flux density position between said first magnetic pole and said second magnetic pole with respect to the rotational direction.

2. A developing device according to claim 1, wherein said cover portion is disposed so that an opposing region between an inner surface of said casing and said developer carrying member is in a side downstream of the developing region and upstream of an upstream said cover portion with respect to the rotational direction.

3. A developing device according to claim 1, wherein a lower end of said cover portion with respect to the longitudinal direction is in a side downstream, with respect to the rotational direction, of a minimum magnetic flux density position between said first magnetic pole and a third magnetic pole which is provided adjacently upstream of said first magnetic pole with respect to the rotational direction and which has a polarity different from a polarity of said first magnetic pole.

4. A developing device according to claim 1, wherein a lower end of said cover portion with respect to the rotational direction is in a side downstream of a maximum magnetic flux density position of said first magnetic pole with respect to the rotational direction

5. A developing device according to claim 1, wherein a lower end of said cover portion with respect to the rotational direction is in a half-width region of a magnetic flux density of said first magnetic pole with respect to the rotational direction.

6. A developing device according to claim 1, wherein a lower end of said cover portion with respect to the rotational direction is in a side downstream, with respect to the rotational direction, of an upstream end of a half-width region of a magnetic flux density of said first magnetic pole with respect to the rotational direction.

7. A developing device according to claim 1, wherein a lower end of said cover portion with respect to the rotational direction is positioned, with respect to the vertical direction, a horizontal plane passing through a rotation axis of said developer carrying member.

8. A developing device comprising:

an accommodating casing configured to accommodate a developer;

a rotatable developer carrying member provided in said accommodating casing and configured to develop, in a developing region, an electrostatic latent image formed on an image bearing member;

a regulating portion provided below said developer carrying member with respect to a vertical direction and configured to regulate an amount of the developer on said developer carrying member;

a magnetic flux generating portion provided inside said developer carrying member and including a first magnetic pole provided downstream of the developing region with respect to a rotational direction of said developer carrying member and a second magnetic pole which is provided adjacently downstream of said first magnetic pole with respect to the rotational direction and which has a polarity identical to a polarity of said first magnetic pole; and

a cover portion provided downstream of the developing region and upstream of a maximum magnetic flux density position of said second magnetic pole with respect to the rotational direction, said cover portion being disposed between said casing and said developer carrying member over a rotational axis direction of said developer carrying member with a gap between itself and said casing and with a gap between itself and said developer carrying member,

wherein a downstream end of said cover portion with respect to the rotational direction is provided below, with respect to a vertical direction, a horizontal plane passing through a rotation center of said developer carrying member.

9. A developing device according to claim 8, wherein a lower end of said cover portion with respect to the rotational direction is in a side upstream, with respect to the rotational direction, of a minimum magnetic flux density position between said first magnetic pole and said second magnetic pole with respect to the rotational direction.

10. A developing device according to claim 8, wherein said cover portion is disposed so that an opposing region between an inner surface of said casing and said developer carrying member is in a side downstream of the developing region and upstream of the upstream end of said cover portion with respect to the rotational direction.

11. A developing device according to claim 8, wherein a lower end of said cover portion with respect to the longitudinal direction is in a side downstream, with respect to the rotational direction, of a minimum magnetic flux density position between said first magnetic pole and a third magnetic pole which is provided adjacently upstream of said first magnetic pole with respect to the rotational direction and which has a polarity different from a polarity of said first magnetic pole.

12. A developing device according to claim 8, wherein a lower end of said cover portion with respect to the rotational direction is in a side downstream of a maximum magnetic flux density position of said first magnetic pole with respect to the rotational direction.

13. A developing device according to claim 8, wherein a lower end of said cover portion with respect to the rotational direction is in a half-width region of a magnetic flux density of said first magnetic pole with respect to the rotational direction.

14. A developing device according to claim 8, wherein a lower end of said cover portion with respect to the rotational direction is positioned, with respect to the vertical direction, a horizontal plane passing through a rotation axis of said developer carrying member.

15. A developing device comprising:

an accommodating casing configured to accommodate a developer;

a rotatable developer carrying member provided in said accommodating casing and configured to develop, in a developing region, an electrostatic latent image formed on an image bearing member;

a regulating portion provided below said developer carrying member with respect to a vertical direction and configured to regulate an amount of the developer on said developer carrying member;

a magnetic flux generating portion provided inside said developer carrying member and including a first magnetic pole provided downstream of the developing region with respect to a rotational direction of said developer carrying member and a second magnetic pole which is provided adjacently downstream of said first magnetic pole with respect to the rotational direction and which has a polarity identical to a polarity of said first magnetic pole; and

a cover portion provided downstream of the developing region and upstream of a maximum magnetic flux density position of sold second magnetic pole with respect to the rotational direction, said cover portion being disposed between said casing and said developer carrying member over a rotational axis direction of said developer carrying member with a gap between itself and said casing and with a gap between itself and said developer carrying member,

wherein an upstream end of said cover portion with respect to the rotational direction is in a position opposing a region, of said developer carrying member, upstream of a top of said developer carrying member with respect to the rotational direction, and

wherein said cover portion is disposed so that an opposing region between an inner surface of said casing and said developer carrying member is in a side downstream of the developing region and upstream of the upstream end of said cover portion with respect to the rotational direction.

16. A developing device according to claim 15, wherein a lower end of said cover portion with respect to the rotational direction is in a side upstream, with respect to the rotational direction, of a minimum magnetic flux density position between said first magnetic pole and said second magnetic pole with respect to the rotational direction.

17. A developing device according to claim 15, wherein a lower end of said cover portion with respect to the longitudinal direction is in a side downstream, with respect to the rotational direction, of a minimum magnetic flux density position between said first magnetic pole and a third magnetic pole provided adjacently upstream of said first magnetic pole with respect to the rotational direction.

18. A developing device according to claim 15, wherein a lower end of said cover portion with respect to the rotational direction is in a side downstream of a maximum magnetic flux density position of said first magnetic pole with respect to the rotational direction.

19. A developing device according to claim 15, wherein a lower end of said cover portion with respect to the rotational direction is in a half-width region of a magnetic flux density of said first magnetic pole with respect to the rotational direction.

20. A developing device according to claim 15, wherein a lower end of said cover portion with respect to the rotational direction is in a side downstream, with respect to the rotational direction, of an upstream end of a half-width region of a magnetic flux density of said first magnetic pole with respect to the rotational direction.

21. A developing device according to claim 15, wherein a lower end of said cover portion with respect to the rotational direction is positioned, with respect to the vertical direction, a horizontal plane passing through a rotation axis of said developer carrying member.

22. A developing device comprising:

an accommodating casing configured to accommodate a developer;

a rotatable developer carrying member provided in said accommodating casing and configured to develop, in a developing region, an electrostatic latent image formed on an image bearing member;

a regulating portion provided below said developer carrying member with respect to a vertical direction and configured to regulate an amount of the developer on said developer carrying member;

a magnetic flux generating portion provided inside said developer carrying member and including a first magnetic pole provided downstream of the developing region with respect to a rotational direction of said developer carrying member and a second magnetic pole which is provided adjacently downstream of said first magnetic pole with respect to the rotational direction and which has a polarity identical to a polarity of said first magnetic pole; and

a cover portion provided downstream of the developing region and upstream of a maximum magnetic flux density position of said second magnetic pole with respect to the rotational direction, said cover portion being disposed between said casing and said developer carrying member over a rotational axis direction of said developer carrying member with a gap between itself and said casing and with a gap between itself and said developer carrying member,

wherein an upstream end of said cover portion with respect to the rotational direction is in a side upstream of a maximum magnetic flux density position of said first magnetic pole with respect to the rotational direction, and

wherein said cover portion is disposed so that an opposing region between an inner surface of said casing and said developer carrying member is in a side downstream of the developing region and upstream of the upstream end of said cover portion with respect to the rotational direction.

23. A developing device according to claim 22, wherein a lower end of said cover portion with respect to the rotational direction is in a side upstream, with respect to the rotational direction, of a minimum magnetic flux density position between said first magnetic pole and said second magnetic pole with respect to the rotational direction.

24. A developing device according to claim 22, wherein a lower end of said cover portion with respect to the longitudinal direction is in a side downstream, with respect to the rotational direction, of a minimum magnetic flux density position between said first magnetic pole and a third magnetic pole provided adjacently upstream of said first magnetic pole with respect to the rotational direction.

25. A developing device according to claim 22, wherein a lower end of said cover portion with respect to the rotational direction is in a side downstream of a maximum magnetic flux density position of said first magnetic pole with respect to the rotational direction.

26. A developing device according to claim 22, wherein a lower end of said cover portion with respect to the rotational direction is in a half-width region of a magnetic flux density of said first magnetic pole with respect to the rotational direction.

27. A developing device according to claim 22, wherein a lower end of said cover portion with respect to the rotational direction is in a side downstream, with respect to the rotational direction, of an upstream end of a half-width region of a magnetic flux density of said first magnetic pole with respect to the rotational direction.

28. A developing device according to claim 22, wherein a lower end of said cover portion with respect to the rotational direction is positioned, with respect to the vertical direction, a horizontal plane passing through a rotation axis of said developer carrying member.