| 摘要 |
PROBLEM TO BE SOLVED: To reduce constraints on layout, to reduce cost, to measure an image position highly accurately irrespectively of the amount of toner attached to a measuring pattern, and to enable high-quality image formation by providing a light receiving means which receives illuminating light via an endless bandlike rotary member and a slit, and composing the endless bandlike rotary member out of a member which transmits light. SOLUTION: This device has an illuminating device 20a being illuminating means which illuminates the measuring pattern 21 on a transfer belt 17 from the above when the measuring pattern 21 on the transfer belt 17 passes a specific measuring position, and a photodetector 20e as the light receiving means which is set on the underside of a mask 20b and detects an amount of light by receiving light which has passed from the illuminating device 20a through the transfer belt 17 and the slit of the mask 20b. In the transfer belt 17, the end of the range illuminated by the illuminating device 20a and including at least an area where the measuring pattern 2 is transferred is made of a transparent material, to transmit the illuminating light thrown from the illuminating device 20a. |
