OUTPUTTED IMAGE DENSITY CONTROLLER

摘要

PURPOSE:To provide an image density controller capable of controlling the outputted density of test images of low density and high density without changing the image quality and always obtaining an outputted image of constant image quality even in the case the change of properties is generated in an electrophotographic process. CONSTITUTION:Set values for an electrostatic charging quantity T and a developing bias voltage B are calculated by a T and B computing element 202 based on an error signal from an error detector 201. In the case of detecting by a setting limit detector 203 that the set value for the electrostatic charging quantity, or for the developing bias voltage B exceeds its setting limit, the set value for exposure intensity P is calculated by a P computing element 204. Ordinarily, the electrostatic charging quantity T and the developing bias voltage B are controlled and the exposure intensity P is controlled as necessary, so that the image quality is prevented from changing after the control is finished by performing the control of the exposure intensity P as little as possible.