Image forming apparatus that controls a charging bias based on an estimated surface potential

Patent metadata

Field	Value
Publication number	US-11226571-B2
Application number	US-202016986265-A
Country	US
Kind code	B2
Filing date	Aug 6, 2020
Priority date	Aug 9, 2019
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

An image forming apparatus includes a photoconductor, a charger, a charge remover, and control circuitry. The charger is configured to charge the photoconductor. The charge remover is configured to remove charge from a surface of the photoconductor by light and electric discharge. The control circuitry is configured to: estimate a surface potential that the photoconductor has after the photoconductor is charged by the charger, based on a characteristic value of the photoconductor and a value of a current flowing through the charger after the charge remover removes charge from the photoconductor; and control a charging bias applied to the charger, based on the surface potential estimated.

First claim

The invention claimed is:

1. An image forming apparatus, comprising:
a photoconductor;
a charger that charges the photoconductor;
a charge remover that removes charge from a surface of the photoconductor by light and electric discharge; and
control circuitry configured to:
estimate a surface potential of the photoconductor, after the photoconductor is charged by the charger, based on a characteristic value of the photoconductor and a first value of a first current flowing through the charger after the charge remover removes charge from the photoconductor;
control a charging bias applied to the charger based on the surface potential;
estimate a residual potential of the photoconductor, after the charge remover removes charge from the surface of the photoconductor only by light discharge, based on:
a second value of a second current flowing through the charger when the charger charges the photoconductor after the charge remover removes charge from the surface of the photoconductor by light and electric discharge,
a third value of a third current flowing through the charger when the charger charges the photoconductor after the charge remover removes charge from the surface of the photoconductor only by light discharge, and
the characteristic value of the photoconductor; and

adjust image forming conditions based on the residual potential.

2. An image forming apparatus, comprising:
a photoconductor;
a charger that charges the photoconductor;
a charge remover that removes charge from a surface of the photoconductor by light and electric discharge; and
control circuitry configured to:
estimate a surface potential of the photoconductor, after the photoconductor is charged by the charger, based on a characteristic value of the photoconductor and a value of a current flowing through the charger after the charge remover removes charge from the photoconductor; and
control a charging bias applied to the charger based on the surface potential:
acquire the characteristic value of the photoconductor by controlling the charge remover and the charger to repeatedly perform a cycle of charge removal by the charge remover and charging by the charger; and
estimate a charge potential of the photoconductor by controlling the charge remover and the charger to perform only once the cycle of charge removal by the charge remover and charging by the charger.

3. The image forming apparatus according to claim 2 , wherein to acquire the characteristic value of the photoconductor, the control circuitry is configured to measure, a plurality of times, a value of a current flowing through the charger when the charger charges the photoconductor after the charge remover removes charge from the photoconductor by light and electric discharge while changing the charging bias applied to the charger.

4. The image forming apparatus according to claim 2 , wherein the control circuitry is configured to acquire the characteristic value of the photoconductor in a case that a specific condition is satisfied.

5. The image forming apparatus according to claim 4 , wherein the specific condition is a condition having a first occurrence frequency that is less than a second occurrence frequency of estimating the charge potential of the photoconductor.

6. The image forming apparatus according to claim 4 , wherein the specific condition is satisfied in a case that the photoconductor is replaced.

7. The image forming apparatus according to claim 4 , wherein the specific condition is satisfied in a case that a use environment is changed by a predetermined amount or more.

8. The image forming apparatus according to claim 4 , wherein the specific condition is satisfied in a case that the photoconductor is used by a predetermined amount or more.

9. The image forming apparatus according to claim 4 , further comprising:
a current detector that detects a value of a current flowing through the charger; and
a charging power supply that applies the charging bias to the charger, wherein
the specific condition is satisfied in a case that the charging power supply is replaced.

10. The image forming apparatus according to claim 2 , wherein the characteristic value of the photoconductor is an amount of change in charge potential with respect to an amount of change in charging current.

11. The image forming apparatus according to claim 2 , further comprising a charging power supply configured to apply the charging bias to the charger, wherein
the charging power supply generates a direct current and an alternating current, and
the charging power supply applies an alternating current bias to the charger so that the charge remover removes charge from the surface of the photoconductor.

12. The image forming apparatus according to claim 2 , wherein the control circuitry is configured to control the charge remover to remove charge from the photoconductor by light and electric discharge for two or more rotations of the photoconductor.

13. A control device for an image forming apparatus including a photoconductor, a charger and a charge remover, the control device comprising:
control circuitry configured to:
estimate a surface potential of the photoconductor, after the photoconductor is charged by the charger, based on a characteristic value of the photoconductor and a value of a current flowing through the charger after the charge remover removes charge from the photoconductor; and
control a charging bias applied to the charger based on the surface potential;
acquire the characteristic value of the photoconductor by controlling the charge remover and the charger to repeatedly perform a cycle of charge removal by the charge remover and charging by the charger; and
estimate a charge potential of the photoconductor by controlling the charge remover and the charger to perform only once the cycle of charge removal by the charge remover and charging by the charger.

14. The control device according to claim 13 , wherein to acquire the characteristic value of the photoconductor, the control circuitry is configured to measure, a plurality of times, a value of a current flowing through the charger when the charger charges the photoconductor after the charge remover removes charge from the photoconductor by light and electric discharge while changing the charging bias applied to the charger.

15. The control device according to claim 13 , wherein the control circuitry is configured to acquire the characteristic value of the photoconductor in a case that a specific condition is satisfied.

16. The control device according to claim 15 , wherein the specific condition is a condition having a first occurrence frequency that is less than a second occurrence frequency of estimating the charge potential of the photoconductor.

17. The control device according to claim 15 , wherein the specific condition is satisfied in a case that the photoconductor is replaced.

18. The control device according to claim 15 , wherein the specific condition is satisfied in a case that a use environment is changed by a predetermined amount or more.

19. The control device according to claim 15 , wherein the specific condition is satisfied in a case that the photoconductor is used by a predetermined amount or more.

20. The control device according to claim 15 , further comprising:
a current detector that detects a value of a current flowing through the charger; and
a charging power supply that applies the charging bias to the charger, wherein
the specific condition is satisfied in a case that the

Assignees

• Kosuge Akio
• Suzuki Yuji
• Takahashi Daisuke
• Akatsu Shinichi
• Ito Daisuke
• Ricoh Co Ltd

Inventors

• Kosuge Akio
• Suzuki Yuji
• Takahashi Daisuke
• Akatsu Shinichi
• Ito Daisuke

Classifications

• G03G15/0266 Primary

  Arrangements for controlling the amount of charge · CPC title

• G03G15/0291

  corona discharge devices, e.g. wires, pointed electrodes, means for cleaning the corona discharge device · CPC title

• G03G15/05 Primary

  for imagewise charging, e.g. photoconductive control screen or optically activated charging means · CPC title

• G03G21/08

  using optical radiation · CPC title