Image formation apparatus and charging control method of charging roll

Abstract

An image formation apparatus includes: a photoconductor that has a photoconductive layer having a surface on which an electrostatic latent image is formed; a charging roll to which a bias with an AC component superposed on a DC component is applied for charging the photoconductor at a predetermined potential; a film thickness detector that detects a film thickness of the photoconductive layer of the photoconductor without applying the AC component; an environment measuring section that measures at least one of ambient temperature and humidity; an AC component setting section that sets a value of the AC component of the bias based on detection results of the film thickness detector and the environment measuring section; and a charging controller that controls at least one of voltage and current applied to the charging roll based on the value of the AC component set by the AC component setting section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described in detail based on the following figure, wherein

FIG. 1 is a schematic drawing to show the configuration of one embodiment of an image formation apparatus according to the invention;

FIG. 2 is a block diagram to schematically show the configuration of charging control according to the invention;

FIG. 3 is a drawing to show the trends of theoretical values and actual measurement values of saturated AC reference value; and

FIG. 4 is a flowchart to describe charging control according to the invention.

Claims

1. An image formation apparatus comprising: a photoconductor that comprises a photoconductive layer having a surface on which an electrostatic latent image is formed;a charging roll to which a bias with an AC component superposed on a DC component is applied for charging the photoconductor at a predetermined potential;a film thickness detector that detects a film thickness of the photoconductive layer of the photoconductor without applying the AC component;an environment measuring section that measures at least one of ambient temperature and humidity;an AC component setting section that sets a value of the AC component of the bias based on detection results of the film thickness detector and the environment measuring section; anda charging controller that controls the voltage or current applied to the charging roll based on the value of the AC component set by the AC component setting section.

2. The image formation apparatus as claimed in claim 1, wherein the film thickness detector detects the film thickness of the photoconductive layer based on a charge amount of the photoconductor at the time of detecting the film thickness.

3. The image formation apparatus as claimed in claim 1, wherein the film thickness detector detects the film thickness based on charging history information of the photoconductor.

4. The image formation apparatus as claimed in claim 1, wherein the AC component setting section sets the AC component of the bias based on the product of a value of the film thickness detected by the film thickness detector to the (−½ ) th power and an environmental compensation coefficient based on at least one of an ambient temperature and humidity measured by the environment measuring section.

5. The image formation apparatus as claimed in claim 1, wherein when a value of the film thickness detected by the film thickness detector exceeds a stipulated value, the AC component setting section sets a value of the AC component of the bias based on a predetermined correlation between (i) the at least one of measured ambient temperature and humidity, and the film thickness and (ii) an AC bias,and when the detected film thickness value is equal to or less than the stipulated value, the AC component setting section actually measures the AC component when the DC component is saturated by gradually increasing or decreasing the AC component and applying the AC component to the photoconductor and sets the AC component of the bias based on the actual measurement value.

6. A charging control method of a charging roll comprising: providing a photoconductor that comprises a photoconductive layer having a surface on which an electrostatic latent image is formed and a charging roll to which a bias with an AC component superposed on a DC component is applied for charging the photoconductor at a predetermined potential;detecting a film thickness of the photoconductive layer of the photoconductor and at least one of ambient temperature and humidity without applying the AC component;when the detected film thickness exceeds a stipulated value, setting a value of the AC component of the bias based on a predetermined correlation between (i) the detected film thickness and the at least one of ambient temperature and humidity and (ii) an AC bias, and applying the AC component to the charging roll; andwhen the detected film thickness value is equal to or less than the stipulated value, actually measuring the value of the AC component when the DC component is saturated, setting a value of the AC component of the bias based on the actual measurement value, and applying the AC component to the charging roll.