Image forming apparatus having developing supporters

• US 6,507,715 B2
• Filed: 07/06/2001
• Issued: 01/14/2003
• Est. Priority Date: 07/07/2000
• Status: Expired due to Term

• Current Assignee: Hitachi Printing Solutions, Ltd. (Ricoh Company Limited)
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Okada, Hisao
• Primary Examiner(s): Royer, William J.
• Application Number:
  US09/899,077
• Publication Number:
  US 20020003967A1
• Time in Patent Office: 557 Days
• Field of Search: 399/55, 399/269, 399/270
• US Class Current: 399/55
• CPC Class Codes: G03G 15/065 Arrangements for controlling the potential of the developing electrode
• CPC Class Codes: G03G 2215/0648 Two or more donor members

Abstract

An image forming apparatus includes a developing device including plural developer supporters provided opposite to a photoconductor, a development bias applying unit for applying a development bias voltage generated by superimposing an AC voltage on a DC voltage to each of the developer supporters, and a phase shifter for shifting a phase of the AC voltage in the development bias voltage in each of the developer supporters.

Claims

1. An image forming apparatus comprising:

a photoconductor supported endlessly movably, latent image forming means for recording and forming an electrostatic latent image on the photoconductor; and

a developing device supplying a developer to the photoconductor holding the electrostatic latent image and forming a toner image on the photoconductor;

wherein said developing device includes plural developer supporters provided opposite to the photoconductor, a development power bias source for applying a development bias voltage generated by superimposing an AC voltage on a DC voltage to each of the developer supporters, and a phase shifter for shifting a phase of the AC voltage in the development bias voltage in each of the developer supporters.

2. An image forming apparatus as defined in claim 1, wherein when an arrangement distance between two adjacent developer supporters of the plural developer supporters in a movement direction of the photoconductor is indicated by d and a peripheral speed of the photoconductor is indicated by vp, a frequency f of the AC voltage substantially satisfies a condition of (f·

d)/vp=m+0.5 (where m is an integer).

3. An image forming apparatus as defined in claim 1, wherein when an arrangement distance between two adjacent developer supporters of the plural developer supporters in a movement direction of the photoconductor is indicated by d and a peripheral speed of the photoconductor is indicated by vp, a frequency f of the AC voltage substantially satisfies a condition of (f·

d)/vp=m (where m is an integer) and AC voltages with opposite phases from each other are applied to the two adjacent developer supporters.