| 摘要 |
PROBLEM TO BE SOLVED: To always maintain toner concentration to be within the tolerance level of an initialized value and to always obtain an image whose quality is high and whose density is stable by detecting the toner concentration after forming the specified number of images, replenishing the toner based on the detected value and correcting the error of toner-replenished supply amount. SOLUTION: The output level of every pixel of an image signal corresponding to the density of each pixel of an original image is counted by a counter 66, so as to calculate a clock pulse integrated signal value C. When a signal value C is a very small signal value ΔC smaller than a threshold C1 , it is held and added to the next signal value C. When C+ΔC>=C1 , C+ΔC is converted into a toner supply time T so as to replenish the toner. For example, every time the number of copies attains a specified number, a toner concentration detecting device is actuated. Namely, a reference image is formed on a photoreceptor drum 17, the actual toner concentration of developer 21 is detected, and by using the detected value, the error of the replenished toner amount based on the signal value C is corrected. |
