Image forming apparatus

Patent metadata

Field	Value
Publication number	US-2016209786-A1
Application number	US-201615000310-A
Country	US
Kind code	A1
Filing date	Jan 19, 2016
Priority date	Jan 20, 2015
Publication date	Jul 21, 2016
Grant date	—

Abstract

An image forming apparatus includes a movable endless belt, a toner image forming unit, a movable transfer member, a voltage source, a setting portion. When a maximum cumulative value in a case where a length in which an adjusting toner image is formed with respect to a movement direction of the belt at a plurality position with respect to a widthwise direction of the belt perpendicular to the movement direction is accumulated is defined as a representative cumulative value, the setting portion sets the second voltage when the adjusting toner image passing through the transfer portion is a first adjusting toner image so as to be lower than the second voltage when the adjusting toner image passing through the transfer portion is a second adjusting toner image smaller in representative cumulative value than the first adjusting toner image.

First claim

What is claimed is:

1 . An image forming apparatus comprising:
a movable endless belt; a toner image forming unit for forming, on said belt, toner images including a toner image for an image which is transferred onto a recording material and an adjusting toner image which is not transferred onto the recording material; a movable transfer member for transferring the toner image at a transfer portion from said belt onto the recording material which is fed; a voltage source for applying a voltage to said transfer member; and a setting portion for setting the voltage applied to said transfer member in a period in which the toner image for the image passes through the transfer portion at a first voltage and for setting the voltage applied to the transfer member in a period in which the adjusting toner image passes through the transfer portion at a second voltage of an opposite polarity to a polarity of the first voltage, wherein when a maximum cumulative value in a case where a length in which the adjusting toner image is formed with respect to a movement direction of said belt at a plurality of positions with respect to a widthwise direction of said belt perpendicular to the movement direction is accumulated is defined as a representative cumulative value, said setting portion sets the second voltage when the adjusting toner image passing through the transfer portion is a first adjusting toner image so as to be lower than the second voltage when the adjusting toner image passing through the transfer portion is a second adjusting toner image smaller in representative cumulative value than the first adjusting toner image.

2 . An image forming apparatus according to claim 1 , wherein said setting portion applies, to said transfer member, a third voltage which has the same polarity as the polarity of the second voltage and which is larger in absolute value than the second voltage in a period from passing of the adjusting toner image through the transfer portion until a subsequent adjusting toner image reaches the transfer portion.

3 . An image forming apparatus according to claim 2 , wherein said setting portion applies the third voltage in a period in which said transfer member moves through at least one-full circumference.

4 . An image forming apparatus according to claim 2 , wherein said image forming unit includes a developing device, and
wherein the first adjusting toner image is a deterioration suppressing toner image formed for suppressing a deterioration of a toner in said developing device.

5 . An image forming apparatus according to claim 1 , wherein said toner image forming unit includes a developing device, and
wherein the first adjusting toner image is a deterioration suppressing toner image formed for suppressing a deterioration of a toner in said developing device.

6 . An image forming apparatus according to claim 1 , wherein the second adjusting toner image is a density adjusting toner image for adjusting a density of the toner image for the image, and
wherein said image forming apparatus further comprises a detecting member for detecting the density adjusting toner image on said belt and an adjusting portion for adjusting the density of the toner image for the image on the basis of a detection result of said detecting member.

7 . An image forming apparatus according to claim 1 , wherein the second adjusting toner image is a position deviation adjusting toner image for adjusting a position of the toner images formed on said belt, and
wherein said image forming unit includes a plurality of image forming portions for forming a plurality of toner images, a detecting member for detecting the position deviation adjusting toner image on said belt, and an adjusting portion for adjusting positions of the toner images formed on said belt at said plurality of image forming portions on the basis of a detection result of said detecting member.

8 . An image forming apparatus according to claim 1 , further comprising a cleaning device including a cleaning blade which is provided in contact with said belt at a position downstream of the transfer portion and upstream of said image forming unit with respect to the movement direction of said belt, for removing a toner on said belt,
wherein the second adjusting toner image is a supplying toner image for supplying the toner to said cleaning blade.

9 . An image forming apparatus according to claim 1 , further comprising an inner transfer roller for stretching said belt from an inner peripheral surface side and for forming the transfer portion in cooperation with said transfer member.

10 . An image forming apparatus according to claim 1 , wherein said transfer member is an outer transfer roller.

Assignees

• Canon Kk

Inventors

• Kojima Etsuji

Classifications

• G03G2215/00569

  Calibration, test runs, test prints · CPC title

• G03G15/1675

  with means for controlling the bias applied in the transfer nip · CPC title

• G03G15/5058

  using a test patch · CPC title

• G03G15/1605 Primary

  using at least one intermediate support (G03G15/1625 takes precedence) · CPC title

• G03G15/1665 Primary

  by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat · CPC title