| 摘要 |
<P>PROBLEM TO BE SOLVED: To form an image with appropriate density even when the charge amount per unit mass of a developer changes. <P>SOLUTION: In the laser printer of the invention, when image data is received, a main motor is driven to rotate a photosensitive drum or the like and a charging bias is applied on a charger to charge the photoreceptor drum (S110), and paper is fed (S120). Then a predetermined developing bias for current detection is applied for a prescribed period on a developing roller to detect the current value of the developing current in the period (S130). Subsequently a developing bias to be applied on the developing roller so as to obtain constant image density of an image to be printed is calculated (S140). In particular, the charge amount (Q/M) per unit mass of the toner is calculated from the detected current value, the developing bias is calculated based on the Q/M, and further the obtained developing bias is applied on the developing roller to carry out the printing process (S150, S160). <P>COPYRIGHT: (C)2005,JPO&NCIPI |
