| 摘要 |
PURPOSE:To stabilize a density by detecting a reference value whenever process conditions are changed, comparing the density of a standard pattern image with the surface density of a photosensitive body, and correcting the process conditions. CONSTITUTION:In a main control part 400, a circuit carrying out the input/ output control of the phototransistor Tr404 of a P sensor PSN and an LED 403 are composed of a digital analog converter IC1, an operational amplifier IC2, a microprocessor IC3, etc. When the density of toner is detected, top end erasing timing is turned on, and then, a P sensor eraser is turned on, so that a P sensor pattern image is formed in front of an original image on the photosensitive body 121. When the P sensor pattern image reaches a P sensor position, the LED 404 is turned on, the P sensor pattern image is irradiated with light, and reflected light is received by the TR 403 to detect the density. Thus, since the process conditions are corrected, a stable density can be always obtained. |
