Image forming apparatus

• US 20060177233A1
• Filed: 03/17/2006
• Published: 08/10/2006
• Est. Priority Date: 07/05/2002
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Ito, Mitsuhiro, Sakai, Hiroaki
• Granted Patent: US 7,203,435 B2
• Time in Patent Office: Days
• US Class Current: 399/50
• CPC Class Codes: G03G 15/0266 Arrangements for controlling the amount of charge
• CPC Class Codes: G03G 15/55 Self-diagnostics; Malfunction or lifetime display

Abstract

The invention provides an image forming apparatus where the useful life of the image carrier does not become significantly short. This system has a charging unit, a charge voltage loading unit, an exposure unit, a development unit, an image transfer unit and a control unit, wherein, when the transport interval of the plural recording materials is shorter than a predetermined time the AC charge voltage applied to the image carrier during the transport interval being a first AC charge voltage, and when the transport interval is longer than the predetermined time the ac charge voltage applied to the image carrier during the transport interval being a second AC charge voltage, the control unit makes the current running in the charging unit to which the second charge voltage is applied lower than the current running in the charging unit to which the first AC charge voltage is applied.

Claims

1. An image forming apparatus having a double-sided print mode, comprising:

charging means for charging an image carrier;

charge voltage loading means for applying a charge voltage to said charging means;

image forming means for forming an image on a recording material; and

control means for controlling the charge voltage applied by said charge voltage loading means to said charging means,

wherein, when an image is formed on a plurality of recording materials, said control means sets the charge voltage at different voltage levels such that the charge voltage level during an interval in which an image is formed on a first side and a second side of the recording material by said image forming means is different from the charge voltage level during an interval between a first sheet and a second sheet of the plurality of recording materials.

2. The image forming apparatus according to claim 1, wherein the double-sided print mode is a mode of transporting the recording material so as to print the plurality of recording materials in a double-sided manner on a one-by-one sheet basis.

3. The image forming apparatus according to claim 1, wherein said control means sets the charge voltage such that the charge voltage during an interval in which an image is formed on the first side and the second side is set at a voltage level which is lower than the voltage level during an interval between the first sheet and the second sheet.

4. The image forming apparatus according to claim 1, further comprising a turn-over transport unit for turning over the recording material and transporting the turned-over recording material to said image forming means, wherein, when the recording material turned over by said turn-over transport unit is transported to a predetermined position before the recording material reaches said image forming means, the charge voltage is switched.

5. The image forming apparatus according to claim 1, wherein said image forming means includes image transfer means for transferring an image formed on the image carrier onto the recording material.

6. The image forming apparatus according to claim 1, wherein the charge voltage includes an AC charge voltage.

7. The image forming apparatus according to claim 6, wherein the charge voltage includes a voltage obtained by adding a DC charge voltage to the AC charge voltage.

8. A printer having a double-sided print mode, comprising:

a charging portion for charging an image carrier;

a charge voltage loading unit for applying a charge voltage to said charging portion;

an image forming portion for forming an image on a recording material; and

a controller for controlling the charge voltage applied by said charge voltage loading unit to said charging portion,

wherein, when an image is formed on a plurality of recording materials, said controller sets the charge voltage at different voltage levels such that the charge voltage level during an interval in which an image is formed on a first side and second side of the recording material by said image forming portion is different from the charge voltage level during an interval between a first sheet and a second sheet of the plurality of recording materials.