| 摘要 |
PURPOSE:To accurately detect the peripheral speed of the photosensitive body, etc., at all times by detecting detection patterns provided to the outer peripheral part of the photosensitive body, etc., and detecting the peripheral speed of the photosensitive body, etc., from the detection signal. CONSTITUTION:The peripheral speed of the photosensitive drum 13 is detected by patterns 46 provided on the outer peripheral surface of the photosensitive drum 13 outside the image area A at one side end part at equal intervals in the circumferential direction, a reflection type photoelectric sensor 47 which is provided opposite the pattern part and detects the pattern 46, and a CPU which detects the peripheral speed of the photosensitive body with its output. Namely, when the photosensitive body 13 is rotated by a motor 20, the patterns 46 are read by the sensor 47 and the CPU calculates the product of the number of patterns detected per unit time and the intervals of the patterns of find the peripheral speed of the photosensitive body. Consequently, the peripheral speed of the photosensitive body, etc., is accurately detected by the simple constitution. |
