| 摘要 |
PURPOSE:To stabilize copying even if used patch density is dispersed, by forming a patch image having fixed density as an electrostatic latent image on a photoreceptor and controlling development bias voltage on the basis of the difference between the potential of the latent image and the development bias potential set up at the adjustment of a copying machine. CONSTITUTION:The surface potential of an electrostatic latent image of a patch 3 having fixed density which is set up on a platen 1 is detected by a potential sensor 16 and the difference between said patch potential and optimum bias potential is stored at the adjustment of the copying machine, e.g. at the time of shipment from a plant or at the time of adjustment by a service man. Thereafter, patch potential is detected at the use of the copying machine and the value obtained by substracting the stored potential difference from the potential of the electrostatic latent image is impressed to a develpment roll 10 as the development bias voltage through a controller 17. |
