| 摘要 |
PURPOSE: To remove a wrong read value of an electrostatic voltmeter (ESV) contaminated by charged particles in a single-path three-level image forming apparatus, by using two ESVs. CONSTITUTION: The voltage level of a relatively noncharged part of a photosensitive substance is measured by using a pair of electrostatic voltmeters(ESV) 55, 80, during each cycle-up after a usual cycle-down. By using one ESV not being contaminated very much as a reference, and adjusting the zero offset of the other ESV, the same residual photosensitive substance voltage read value is achieved. The difference between read values by toner contamination is the zero offset between the two ESVs 55, 80. Using this offset, all the following ESV read values are adjusted until a new offset is measured. |
