Image forming apparatus

Patent metadata

Field	Value
Publication number	US-2016291499-A1
Application number	US-201615185641-A
Country	US
Kind code	A1
Filing date	Jun 17, 2016
Priority date	Dec 20, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

In an image forming apparatus including a plurality of image forming stations, on the basis of a density of a toner image formed in an upstream image forming station, an operation of a pre-exposure device in a downstream image forming station is controlled.

First claim

1 . An image forming apparatus comprising:
a first image forming station including a first photosensitive member, charging means configured to charge said first photosensitive member, first exposure means configured to expose said first photosensitive member charged by said first charging means to light, and first developing means configured to develop with a toner an electrostatic latent image formed on said first photosensitive member by said first exposure means; a second image forming station including a second photosensitive member, second charging means configured to charge said second photosensitive member by being supplied with only a DC voltage, second exposure means configured to expose said second photosensitive member charged by said second charging means to light, and second developing means configured to develop with a toner an electrostatic latent image formed on said second photosensitive member by said second exposure means; transfer means configured to electrostatically transfer superposedly a toner image formed on said first photosensitive member and a toner image formed on said second photosensitive member onto an image receiving member in this order; discharging means configured to optically discharge said second photosensitive member; and control means configured to control an operation of said discharging means depending on a density of a toner image formed in said first image forming station.

2 . An image forming apparatus according to claim 1 , wherein said control means actuates said discharging means when the density of the toner image formed in said first image forming station is not less than a predetermined density and does not actuate said discharging means when the density of the toner image formed in said first image forming station is less than the predetermined density.

3 . An image forming apparatus according to claim 1 , wherein said control means controls the operation of said discharging means depending on the density of the toner image formed in said first image forming station and a density of the toner image formed in said second image forming station.

4 . An image forming apparatus according to claim 3 , wherein said control means actuates said discharging means when the density of the toner image formed in said first image forming station is not less than a predetermined density and when the density of the toner image formed in said second image forming station is not less than a predetermined density, and does not actuate said discharging means when the density of the toner image formed in said second image forming station is less than the predetermined density.

5 . An image forming apparatus according to claim 1 , wherein said transfer means includes a first transfer member disposed opposed to said first photosensitive member via the image receiving member and configured to electrostatically transfer the toner image formed on said first photosensitive member onto the image receiving member and a second transfer member disposed opposed to said second photosensitive member via the image receiving member and configured to electrostatically transfer the toner image formed on said second photosensitive member onto the image receiving member, and wherein to said first transfer member and said second transfer member, in a corresponding transfer step, a voltage of an opposite polarity to a normal charge polarity of a toner is applied.

6 . An image forming apparatus according to claim 5 , comprising a transfer mechanism configured to electrostatically transfer the toner image transferred on the image receiving member onto a recording material.

7 . An image forming apparatus according to claim 1 , wherein said discharging means discharges said second photosensitive member at a position downstream of a transfer position by said transfer means and upstream of a charging position by said second charging means with respect to a movement direction of said second photosensitive member.

8 . An image forming apparatus comprising:
a first image forming station including a first photosensitive member, first charging means configured to charge said first photosensitive member, first exposure means configured to expose said first photosensitive member charged by said first charging means to light, and first developing means configured to develop with a toner an electrostatic latent image formed on said first photosensitive member by said first exposure means; a second image forming station including a second photosensitive member, second charging means configured to charge said second photosensitive member, second exposure means configured to expose said second photosensitive member charged by said second charging means to light, and second developing means configured to develop with a toner an electrostatic latent image formed on said second photosensitive member by said second exposure means; a third image forming station including a third photosensitive member, third charging means configured to charge said third photosensitive member by being supplied with only a DC voltage, third exposure means configured to expose said third photosensitive member charged by said third charging means to light, and third developing means configured to develop with a toner an electrostatic latent image formed on said third photosensitive member by said third exposure means; a fourth image forming station including a fourth photosensitive member, fourth charging means configured to charge said fourth photosensitive member by being supplied with only a DC voltage, fourth exposure means configured to expose said fourth photosensitive member charged by said fourth charging means to light, and fourth developing means configured to develop with a toner an electrostatic latent image formed on said fourth photosensitive member by said fourth exposure means; transfer means configured to electrostatically transfer superposedly a toner image formed on said first photosensitive member, a toner image formed on said second photosensitive member and a toner image formed on said third photosensitive member onto an image receiving member in this order; first discharging means configured to optically discharge said third photosensitive member; second discharging means configured to optically discharge said fourth photosensitive member; and control means configured to control an operation of said first discharging means on the basis of densities of toner images formed in said first image forming station and said second image forming station and configured to control an operation of said second discharging means on the basis of densities of toner images formed in said first image forming station, said second image forming station and said third image forming station.

9 . An image forming apparatus according to claim 8 , wherein said control means actuates said first discharging means when densities of the toner images formed in said first image forming station and said second image forming station are not less than a predetermined density and does not actuate said second discharging means when the densities of the toner images formed in said first image forming station and said second image forming station are less than the predetermined density.

10 . An image forming apparatus according to claim 8 , wherein said control means actuates said first discharging means when densities of the toner images formed in said first image forming station, said second image forming station and said third image forming station are not less than a predetermined density and does not actuate said second discharging means when the densities of the toner images formed in said first image forming station, said second image forming station and said th

Assignees

• Canon Kk

Inventors

• Shibuya Kenichi

Classifications

• G03G21/08 Primary

  using optical radiation · CPC title

• G03G15/0275 Primary

  Arrangements for controlling the area of the photoconductor to be charged · CPC title

• G03G2215/0129

  horizontal medium transport path at the secondary transfer · CPC title

• G03G15/0189

  primary transfer to an intermediate transfer belt (G03G15/0184 takes precedence) · CPC title