Image forming apparatus and printer having a double-sided printing mode

• US 7,203,435 B2
• Filed: 03/17/2006
• Issued: 04/10/2007
• Est. Priority Date: 07/05/2002
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ito, Mitsuhiro, Sakai, Hiroaki
• Primary Examiner(s): Chen; Sophia S.
• Application Number:
  US11/377,374
• Publication Number:
  US 20060177233A1
• Time in Patent Office: 389 Days
• Field of Search: 399/50, 399/45, 399/43, 399/16, 399/46, 399/82, 399/364, 399/401
• 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

An image forming apparatus operating in a double-sided print mode, includes a charger for charging an image carrier, a charge voltage loader for applying a charge voltage to the charger, an image forming device for forming an image on a recording material, and a controller for controlling the charge voltage applied by the charge voltage loader to the charger. When an image is formed on both sides of a plurality of recording materials, the controller changes the charge voltage applied by the charge voltage loader from a first to a second voltage when an image is formed on first and second sides of the recording material in a period in which an image is formed on the recording sheet, and does not change the charge voltage during an interval between a first recording material and a second recording material to the second charge voltage.

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 both sides of a plurality of recording materials, said control means changes the charge voltage 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 to a second charge voltage which is different from a first charge voltage applied by said charge voltage loading means in a period in which an image is formed on the recording material, and said control means does not change the charge voltage during an interval between a first recording material and a second recording material of the plurality of recording materials to the second charge voltage.

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 recording material basis.

3. The image forming apparatus according to claim 1, wherein said control means sets the second charge voltage to a voltage level which is lower than the first charge voltage.

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 configured and positioned to charge an image carrier;

a charge voltage loading unit configured and positioned to apply a charge voltage to said charging portion;

an image forming portion configured and positioned to form an image on a recording material; and

a controller configured and positioned to control the charge voltage applied by said charge voltage loading unit to said charging portion,

wherein, when an image is formed on both sides of a plurality of recording materials, said controller changes the charge voltage 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 portion to a second charge voltage which is different from a first charge voltage applied by said charge voltage loading unit in a period in which an image is formed on the recording material, and the controller does not change the charge voltage during an interval between a first recording material and a second recording material of the plurality of recording materials to the second charge voltage.