| 摘要 |
PURPOSE: To provide an image forming device which is equipped with a plurality of gradation expression means, can excellently form both photographic images and character images, and can restrain increase of control time required for correcting gradation and increase of quantity of consuming toner. CONSTITUTION: An image forming device comprises a 150-line PWM circuit 301 suitable for photographic image and a 300-line PWM circuit 302 suitable for character image as gradation expression means. The 150-line PWM and the 300-line PWM have a correlation and its correlation table is previously stored in a device body. A toner image of a gradation pattern by the 150-line PWM is formed on a photosensitive drum 2, the density is measured by a sensor 100. Base on it, gradation correction of the 150-line PWM is performed, and gradation correction of the 300-line PWM is performed by the above-mentioned correlation. Accordingly, by forming the gradation pattern of the 150-line PWM, two gradation controls of the 150-line PWM and the 300-line PWM can be done. |
