Developing device, and image forming apparatus and process cartridge incorporating same

Patent metadata

Field	Value
Publication number	US-2017336733-A1
Application number	US-201715593010-A
Country	US
Kind code	A1
Filing date	May 11, 2017
Priority date	May 20, 2016
Publication date	Nov 23, 2017
Grant date	—

Abstract

A developing device includes a developer container to contain developer including toner and magnetic carrier, the developer container; a developer bearer to carry, by rotation, the developer to a developing range facing a latent image bearer; a communication opening in a wall defining the developer container; a toner conveyance passage connected to the communication opening; and a cylindrical magnet having a magnetic pole arrangement parallel to an axis of the cylindrical magnet. The cylindrical magnet is disposed to enclose a space overlapping with the communication opening on a cross section perpendicular to the axis of the cylindrical magnet.

First claim

What is claimed is:

1 . A developing device comprising:
a developer container to contain developer including toner and magnetic carrier, the developer container; a developer bearer to carry, by rotation, the developer to a developing range facing a latent image bearer; a communication opening in a wall defining the developer container; a toner conveyance passage connected to the communication opening; and a cylindrical magnet having a magnetic pole arrangement parallel to an axis of the cylindrical magnet, the cylindrical magnet disposed to enclose a space overlapping with the communication opening, on a cross section perpendicular to the axis of the cylindrical magnet.

2 . The developing device according to claim 1 , wherein the cylindrical magnet is disposed on an inner wall face of the developer container defining the communication opening.

3 . The developing device according to claim 1 , further comprising a conveying screw disposed in the developer container to stir and convey the developer in the developer container,
wherein the conveying screw is inserted inside the cylindrical magnet.

4 . The developing device according to claim 3 , wherein the conveying screw has a shaft made of a magnetic material.

5 . The developing device according to claim 3 , wherein the conveying screw has a shaft including a magnetic portion and a nonmagnetic coating covering the magnetic portion.

6 . The developing device according to claim 3 , wherein the conveying screw includes:
a first portion having a first diameter; and a second portion having a second diameter greater than the first diameter, wherein, when the first diameter is 6 mm and the second diameter is 11 mm, a distance from the cylindrical magnet to an end of the second portion on a side of the cylindrical magnet in an axial direction of the conveying screw is 0 to 2 mm.

7 . 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 toner into a toner image.

8 . The image forming apparatus according to claim 7 , further comprising:
a transfer device to transfer the toner image from the latent image bearer onto a transfer medium; a cleaning device to collect a substance adhering to a surface of the latent image bearer after transferring of the toner image, the substance including the toner; a waste-toner container to store waste toner collected by the cleaning device; a toner conveyance device to supply the toner to the developing device, the toner conveyance device including a collected-toner passage through which collected toner collected by the cleaning device is conveyed, the collected-toner passage branching into:
a waste-toner passage coupled to the waste-toner container; and
a collected-toner supply passage coupled to the toner conveyance passage connected to the communication opening of the developing device; and
a passage selector to guide the collected toner inside the collected-toner passage to one of the waste-toner passage and the collected-toner supply passage.

9 . A process cartridge to be removably installed in an image forming apparatus, the process cartridge comprising:
the latent image bearer to bear a latent image; the developing device according to claims 1 ; and a holder to hold the latent image bearer and the developing device.

Assignees

• Adachi Takahiro
• Fujimori Akira
• Takahashi Yutaka
• Hamada Daisuke
• Ricoh Co Ltd

Inventors

• Adachi Takahiro
• Fujimori Akira
• Takahashi Yutaka
• Hamada Daisuke

Classifications

• G03G15/0891

  for conveying or circulating developer, e.g. augers · CPC title

• G03G21/105

  Arrangements for conveying toner waste · CPC title

• G03G15/09

  using magnetic brush · CPC title

• G03G15/0889 Primary

  for agitation or stirring · CPC title

• G03G15/0893

  in a closed loop within the sump of the developing device · CPC title