Image forming apparatus

• US 6,801,724 B2
• Filed: 04/08/2003
• Issued: 10/05/2004
• Est. Priority Date: 04/09/2002
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Naito, Norihito, Matsumoto, Hideki
• Primary Examiner(s): TRAN, HOAN H
• Application Number:
  US10/408,576
• Publication Number:
  US 20030219265A1
• Time in Patent Office: 546 Days
• Field of Search: 399/38, 399/50, 399/53, 399/55
• US Class Current: 399/38
• CPC Class Codes: G03G 15/0856 Detection or control means for the developer level
• CPC Class Codes: G03G 15/086 the level being measured by electro-magnetic means

Abstract

An image forming apparatus of an electrophotography system, in which 10<PS/|Hz1−Hz2| is satisfied where Hz1 indicates a frequency of charging bias, Hz2 indicates a frequency of developing bias, and PS indicates a peripheral speed of a photosensitive member, whereby preventing density unevenness in an image.

Claims

1. An image forming apparatus comprising

an image bearing member;

a charging means for charging the image bearing member, to which charging means is applied a charging voltage including a first alternating component; and

a developing means for developing an electrostatic image formed on the image bearing member with developer, to which developing means is applied a developing voltage including a second alternating component; and

wherein 10<

PS/|Hz1−

Hz2| is satisfied where Hz1 (Hz) indicates a frequency of the first alternating component, Hz2 (Hz) indicates a frequency of the second alternating component, and PS (mm/sec) indicates a peripheral speed of the image bearing member.

2. The image forming apparatus according to claim 1, further comprising a developer residual quantity detecting means for detecting a residual quantity of the developer by the use of the developing voltage.

3. The image forming apparatus according to claim 2, wherein

Ca1_t (sec) satisfies

Ca1_t× |Hz1−

Hz2|>

4

where Ca1_t indicates a decision time for deciding a representative value related to a residual quantity of the developer on the basis of a detected value from the developer residual quantity detecting means.

4. The image forming apparatus according to claim 2, wherein

Ca1_t (sec) satisfies

Ca1_t×

|Hz1−

Hz2|=1

or Ca1_t×

|Hz1−

Hz2|=2

or Ca1_t×

|Hz1−

Hz2|=3

or Ca1_t×

|Hz1−

Hz2|=4

where Ca1_t indicates a decision time for deciding a representative value related to a residual quantity of the developer on the basis of a detected value from the developer residual quantity detecting means.

5. The image forming apparatus according to claim 1, wherein the charging voltage and the developing voltage are formed by dividing clock generated by a common oscillation circuit.

6. The image forming apparatus according to claim 2, wherein the developer residual quantity detecting means comprises a plurality of electrode members and a residual quantity of the developer is determined according to an electrostatic capacity among the plurality of electrode members when the developing voltage is applied.

7. The image forming apparatus according to claim 6, wherein the developing voltage is applied to one of the plurality of electrode members.

8. The image forming apparatus according to claim 1, wherein the charging means is provided in contact with the image bearing member.

9. The image forming apparatus according to claim 1, wherein the image bearing member, the charging means, and the developing means are provided in a process cartridge, which is detachable from a body of the image forming apparatus.