Image forming apparatus

Patent metadata

Field	Value
Publication number	US-10095150-B2
Application number	US-201514849789-A
Country	US
Kind code	B2
Filing date	Sep 10, 2015
Priority date	Oct 1, 2014
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

An image forming apparatus includes an image bearing member, a charging member, a charging voltage source, an electrostatic image forming portion, a developing device, a developing voltage source, a transfer portion, a transfer voltage source, and a controller. During image formation, the toner remaining on the image bearing member after transfer is collected into the developing device while forming an image. In a cleaning operation performed during non-image formation, while rotating the image bearing member, the controller transfers the toner from the charging member onto the image bearing member, passes the toner through the developing portion in an urged state, reverses a charge polarity of the toner to a normal polarity at a charging portion, and then transfers the toner reversed in charge polarity from the image bearing member onto the developing member at the developing portion to collect the toner in the developing device.

First claim

What is claimed is:

1. A method of executing a cleaning operation in an image forming apparatus that includes (a) a rotatable image bearing member, (b) a charging member for electrically charging the image bearing member while contacting the image bearing member at a charging position by being supplied with a charging voltage, (c) an electrostatic image forming unit for forming an electrostatic image on the electrically charged image bearing member, (d) a developing device including a developing member for forming a toner image by being supplied with a developing voltage to supply a toner charged to a normal polarity to the electrostatic image on the image bearing member at a developing position, (e) a transfer member for electrostatically transferring the toner image from the image bearing member onto a toner image receiving member at a transfer portion by being supplied with a transfer voltage, (f) a discharging unit for discharging the image bearing member at a discharging position downstream of the transfer position and upstream of the charging position with respect to a rotational direction of the image bearing member, and (g) a controller for executing the cleaning operation during non-image formation, the method comprising:
a transfer step of transferring an opposite polarity toner deposited on the charging member and charged to an opposite polarity opposite to the normal polarity from the charging member onto the image bearing member at the charging position;
a discharging step of discharging, by the discharging unit at the discharging position, a region of the image bearing member where the opposite polarity toner is deposited;
a polarity inversion step of inverting the opposite polarity toner deposited on said image bearing member into a normal polarity toner charged to the normal polarity by passing the region discharged by the discharging step through the charging position in a state in which the charging voltage is applied to the charging member; and
a collecting step of collecting the normal polarity toner by transferring the normal polarity toner from the image bearing member onto the developing member at the developing position.

2. The method of executing a cleaning operation according to claim 1 , wherein in the polarity inversion step, electric discharge is generated between the image bearing member and the charging member.

3. The method of executing a cleaning operation according to claim 1 , wherein a region of the image bearing member where the toner charged to the opposite polarity is to be transferred in the transfer step passes through the discharging position without being discharged by the discharging unit after being charged by the charging member and then reaches the charging position, and the toner charged to the opposite polarity is transferred from the charging member onto the image bearing member.

4. The method of executing a cleaning operation according to claim 3 , wherein the region of the image bearing member where the toner charged to the opposite polarity is to be transferred in the transfer step passes through the transfer position after being charged by the charging member, the transfer position being in a state in which a voltage higher in a normal polarity side than a voltage applied to the transfer member during image formation is applied to the transfer member, and then reaches the charging position, and the toner charged to the opposite polarity is transferred from the charging member onto the image bearing member.

5. The method of executing a cleaning operation according to claim 4 , wherein the voltage higher in the normal polarity side than the voltage applied to the transfer member during the image formation is opposite in polarity to the voltage applied to the transfer member during the image formation.

6. The method of executing a cleaning operation according to claim 1 , wherein in the transfer step, a first charging voltage higher in an opposite polarity side to the normal polarity than a surface potential of the image bearing member is applied to the charging member, and in the polarity inversion step, a second charging voltage higher in a normal polarity side than the first charging voltage is applied to the charging member.

7. The method of executing a cleaning operation according to claim 1 , wherein when the region where the toner charged to the opposite polarity is transferred in the transfer step passes through the developing position, the controller applies a first developing voltage higher in an opposite polarity side to the normal polarity than a surface potential in a region of the image bearing member where the toner charged to the opposite polarity is transferred.

8. The method of executing a cleaning operation according to claim 6 , wherein the first charging voltage is 0 V.

9. The method of executing a cleaning operation according to claim 1 , wherein only a DC voltage is applied to the charging member.

10. The method of executing a cleaning operation according to claim 1 , wherein in the transfer step, a charging voltage higher in a normal polarity side than a surface potential of the image bearing member is applied to the charging member.

11. The method of executing a cleaning operation according to claim 1 , wherein the discharging unit discharges the image bearing member at the discharging position by irradiation with light.

Assignees

• Canon Kk

Inventors

• Hiramatsu Takashi
• Usui Yusuke
• Tamagaki Kuniaki
• Iwayama Hiroyoshi

Classifications

• G03G21/0064

  using the developing unit, e.g. cleanerless or multi-cycle apparatus · CPC title

• G03G15/0258 Primary

  provided with means for the maintenance of the charging apparatus, e.g. cleaning devices, ozone removing devices G03G15/0225, G03G15/0291 takes precedence · CPC title