Developing device and image forming apparatus incorporating same that reduce low-flow regions of toner within the developing device

Patent metadata

Field	Value
Publication number	US-10007209-B2
Application number	US-201715604235-A
Country	US
Kind code	B2
Filing date	May 24, 2017
Priority date	Jun 3, 2016
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

A developing device includes a developer bearer, a developer regulator disposed opposite the developer bearer across a first gap, and an opposing member having an opposing face disposed opposing the developer bearer across a second gap wider than the first gap. The opposing face is disposed adjacent to and upstream from the developer regulator in a direction of rotation of the developer bearer. The opposing face is inclined relative to an orthogonal plane direction orthogonal to a side face of the developer regulator. The opposing face is inclined to progressively reduce a distance from the developer bearer to the opposing face in a direction of rotation of the developer bearer. A difference between the second gap and the first gap is not greater than 1.75 times as large as the first gap.

First claim

What is claimed is:

1. A developing device comprising:
a developer bearer to bear developer and supply the developer to a latent image on a latent image bearer;
a developer regulator disposed opposite the developer bearer, across a first gap, to regulate a layer thickness of the developer borne on the developer bearer;
an opposing member having an opposing face disposed opposing the developer bearer across a second gap, the opposing face disposed adjacent to and upstream from the developer regulator in a direction of rotation of the developer bearer, the opposing face inclined relative to an orthogonal plane direction orthogonal to a side face of the developer regulator, the opposing face being inclined to progressively reduce a distance from the developer bearer to the opposing face in a direction of rotation of the developer bearer;
the developer regulator includes
a nonmagnetic plate; and
a thin plate thinner than the nonmagnetic plate, the thin plate attached to the nonmagnetic plate and projecting beyond the nonmagnetic plate toward the developer bearer, the thin plate attached to an upstream-side face of the nonmagnetic plate facing an upstream side in the direction of rotation of the developer bearer,
wherein the first gap is narrower than the second gap, and
wherein a difference between the second gap and the first gap is not greater than 1.75 times as large as the first gap.

2. The developing device according to claim 1 , wherein the developer includes toner and magnetic carrier,
wherein the developer bearer includes:
a hollow developing sleeve to rotate and bear the developer; and
a magnetic force generator contained inside the hollow developing sleeve not to rotate together with the hollow developing sleeve, the magnetic force generator having a plurality of magnetic poles arranged in the direction of rotation of the developer bearer,

wherein the plurality of magnetic poles includes:
a regulation pole to attract the developer to a surface of the hollow developing sleeve at a position where the developer regulator regulates the layer thickness of the developer; and
a post-regulation pole disposed adjacent to and downstream from the regulation pole in the direction of rotation of the developer bearer,

wherein a maximum point of a magnetic force of the regulation pole in a direction normal to the surface of the hollow developing sleeve is disposed upstream from the developer regulator in the direction of rotation of the developer bearer, and
wherein a maximum point of a magnetic force of the post-regulation pole in the direction normal to the surface of the hollow developing sleeve is disposed downstream from the developer regulator in the direction of rotation of the developer bearer.

3. The developing device according to claim 2 , wherein a minimum point, at which the magnetic force of each of the regulation pole and the post-regulation pole in the direction normal to the surface of the hollow developing sleeve is minimum, is disposed opposing an end of the developer regulator.

4. The developing device according to claim 1 , wherein the side face of the developer regulator opposes the upstream side in the direction of rotation of the developer bearer.

5. The developing device according to claim 1 , wherein an upstream-side edge at an end of the thin plate has a chamfered edge, the upstream-side edge facing the upstream side in the direction of rotation of the developer bearer.

6. The developing device according to claim 1 , wherein the opposing member includes a plurality of ribs for heat radiation, the plurality of ribs disposed on a face of the opposing member different from the opposing face.

7. The developing device according to claim 6 , wherein the opposing member is made of aluminum.

8. An image forming apparatus comprising:
the latent image bearer to bear a latent image; and
the developing device according to claim 1 , to develop the latent image with the developer.

9. A developing device comprising:
a developer bearer to bear developer and supply the developer to a latent image on a latent image bearer, wherein the developer includes toner and magnetic carrier;
a developer regulator disposed opposite the developer bearer, across a first gap, to regulate a layer thickness of the developer borne on the developer bearer,
wherein the developer bearer includes:
a hollow developing sleeve to rotate and bear the developer; and
a magnetic force generator contained inside the hollow developing sleeve not to rotate together with the hollow developing sleeve, the magnetic force generator having a plurality of magnetic poles arranged in a direction of rotation of the developer bearer,

wherein the plurality of magnetic poles includes:
a regulation pole to attract the developer to a surface of the hollow developing sleeve at a position where the developer regulator regulates the layer thickness of the developer; and
a post-regulation pole disposed adjacent to and downstream from the regulation pole in the direction of rotation of the developer bearer,
wherein a maximum point of a magnetic force of the regulation pole in a direction normal to the surface of the hollow developing sleeve is disposed upstream from the developer regulator in the direction of rotation of the developer bearer,
wherein a maximum point of a magnetic force of the post-regulation pole in the direction normal to the surface of the hollow developing sleeve is disposed downstream from the developer regulator in the direction of rotation of the developer bearer,
wherein a minimum point, at which the magnetic force of each of the regulation pole and the post-regulation pole in the direction normal to the surface of the hollow developing sleeve is minimum, is disposed opposing an end of the developer regulator; and

an opposing member having an opposing face disposed opposing the developer bearer across a second gap, the opposing face disposed adjacent to and upstream from the developer regulator in a direction of rotation of the developer bearer, the opposing face inclined relative to an orthogonal plane direction orthogonal to a side face of the developer regulator, the opposing face being inclined to progressively reduce a distance from the developer bearer to the opposing face in a direction of rotation of the developer bearer,
wherein the first gap is narrower than the second gap, and
wherein a difference between the second gap and the first gap is not greater than 1.75 times as large as the first gap.

10. The developing device according to claim 9 , wherein the developer regulator includes:
a nonmagnetic plate; and
a thin plate thinner than the nonmagnetic plate, the thin plate attached to the nonmagnetic plate and projecting beyond the nonmagnetic plate toward the developer bearer, the thin plate attached to an upstream-side face of the nonmagnetic plate facing an upstream side in the direction of rotation of the developer bearer.

11. The developing device according to claim 10 , wherein an upstream-side edge at an end of the thin plate has a chamfered edge, the upstream-side edge facing the upstream side in the direction of rotation of the developer bearer.

12. The developing device according to claim 9 , wherein the opposing member includes a plurality of ribs for heat radiation, the plurality of ribs disposed on a face of the opposing member different from the opposing face.

13. An image forming apparatus comprising:
the latent image bearer to bear a latent image; and
the developing device according to claim 9 , to develop the latent image with the developer.

14. The developing device according to claim 9 ,

Assignees

• Koshizuka Shinnosuke
• Yamazaki Koichi
• Takami Nobuo
• Nakamoto Atsushi
• Suzuki Kazunori
• Kawashima Naohiro
• Ricoh Co Ltd

Inventors

• Koshizuka Shinnosuke
• Yamazaki Koichi
• Takami Nobuo
• Nakamoto Atsushi
• Suzuki Kazunori
• Kawashima Naohiro

Classifications

• G03G15/081

  characterised by the developer handling means after the supply and before the regulating, e.g. means for preventing developer blocking · CPC title

• G03G15/0921

  Details concerning the magnetic brush roller structure, e.g. magnet configuration · CPC title

• G03G15/0812 Primary

  characterised by the developer regulating means, e.g. structure of doctor blade · CPC title

• G03G15/0928

  relating to the shell, e.g. structure, composition · CPC title