| 摘要 |
PURPOSE:To lessen a start mark, reduce toner consumption, shorten the time for process control, and enhance the accuracy of process control. CONSTITUTION:A toner patch is prepared on a photo-sensitive substance drum 1, and the density is read by a photo-sensor 16. On the basis of the sensed density, the CPU 19 of 3 process control device 15 performs process control by sending control signals to a lamp driving circuit 28, power supply 29, or developing bias power supply 30. The process control device 15 controls the grid voltage to be impressed on a main charger 7, the impression voltage of a copy lamp 4, or the developing bias voltage to be impressed on a developing unit 9, and thereby prepares toner patch with varying gradation on the drum 1 or prepares a start marls preceding to the toner patch. When toner patch density is to be sensed, the sensing start timing is set using this start mark as reference. Thereby density sensing is conducted accurately. |
