| 摘要 |
PURPOSE:To form a satisfactory image without being affected by environmental changes in temperature, humidity, etc., by detecting the concn. of developer for an image formed on an image carrier and controlling an output from an electrification grid according to the concn. CONSTITUTION:A photosensitive drum 30 is rotating and driving, and toner sticks thereto in a developing roller part 33 to develop a latent image formed by laser beams on the surface of the drum. When the photosensitive drum 30 is developed by a developing roller 33, a control circuit 405 makes the light emitting diode of a second toner concn. sensor 431 emit light, and a light receiving diode receives light reflected by the photosensitive drum 30. The light is converted into an electrical signal to detect the toner. When the toner concn. in a low concn. area is insufficient, a high pressure power source 412 is controlled to raise the output from the electrification grid to -600 V from -550 V in -10 V increments. |
