# US 8,543,041 B2 · Image forming apparatus

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- Number: US 8,543,041 B2
- Document ID: US8543041B2
- Status: Granted
- Kind: B2
- Application number: 13/273,104
- Filed: 2011-10-13
- Published: 2012-06-14
- Granted: 2013-09-24
- Earliest claimed: 2010-12-08
- Assignees: Canon Kabushiki Kaisha
- Applicants: Katsuya Nose; Akihiro Noguchi; Kyosuke Takahashi
- Inventors: Katsuya Nose; Akihiro Noguchi; Kyosuke Takahashi
- Web page: https://patentgrep.com/patent/US8543041B2

## CPC

- G03G 15/0898: {for preventing toner scattering during operation, e.g. seals (sealing the donor member G03G15/0817; sealing the magnetic brush G03G15/0942)}
- G03G 15/0815: {characterised by the developer handling means after the developing zone and before the supply, e.g. developer recovering roller}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

The specification discloses a developing device comprises a first developer bearing member configured to bear a developer including a toner and a carrier, and to convey the developer to a first developing region facing an image bearing member, so as to develop an electrostatic latent image formed onto the image bearing member and a second developer bearing member configured to bear a developer transferred from the first developer bearing member, and to develop an electrostatic latent image formed on the image bearing member, by conveying a developer to a second developing region facing the image bearing member and a cover unit configured to shield a route toward the image bearing member from a mutual gap position between the first developer bearing member and the second developer bearing member.

## Claims

### Claim 1

A developing device comprising:
a first developer bearing member configured to bear a developer including a toner and a carrier, and to convey the developer to a first developing region facing an image bearing member, so as to develop an electrostatic latent image formed onto the image bearing member;
a second developer bearing member configured to bear a developer transferred from the first developer bearing member, and to develop an electrostatic latent image formed on the image bearing member, by conveying a developer to a second developing region facing the image bearing member; and
a cover unit configured to not overlap respective developing regions at end portions in axis line direction of the first and the second developer bearing members, and to shield a route toward the image bearing member from a mutual gap position between the first developer bearing member and the second developer bearing member to the image bearing member,
wherein the cover unit has a projection portion that projects with respect to an axis line direction of the first developer bearing member, so as to shield more inward regions than end portions of respective developing regions between the respective developing regions.

### Claim 2 (depends on 1)

The developing device according to claim 1, wherein a length of the projection portion is equal to or greater than a length to the cover unit from a position which is a closest proximity position between the first developer bearing member and the second developer bearing member.

### Claim 3 (depends on 1)

The developing device according to claim 1, wherein the projection portion is provided not to overlap respective developing regions.

### Claim 4 (depends on 1)

The developing device according to claim 1, wherein one end of the cover unit is fixed to a regulating member that regulates a layer thickness of the first developer bearing member, and the other end of the cover unit is attached to the developing device on downstream side in a rotational direction of the second developer bearing member.