| 摘要 |
PROBLEM TO BE SOLVED: To appropriately control the image forming condition to express the gradation according to the increase/decrease in the printing area ratio such as dots and lines by adjusting the size of the dots by a second adjusting means after the toner adhesion quantity of the dot image is adjusted by a first adjusting means. SOLUTION: A solid reference image, and the dot reference image are formed on a photosensitive body 1 before forming the image, and the area ratio of the dot reference image and the toner adhesion of the solid reference image are detected by an image sensor 10. A printer control part 11 controls the values of the surface electric potential V0 and the developing bias electric potential VB based on the detected values and various look-up tables stored in a memory 16. In forming the dot image, it is preferable to determine the charging quantity of the photosensitive body 1 based on the developing bias electric potential VB adjusted by the concentration of the solid toner image, and to form the dot image of the area ratio in the detected range of the image sensor 10. |
