| 摘要 |
PROBLEM TO BE SOLVED: To prevent image density from being erroneously detected in the case a shutter is not opened by providing an intercepting part, used for reflecting light differing in amount from light reflected from a density-detection image, onto a face which is opposite a detection face when the shutter is closed. SOLUTION: The intercepting part 19 is provided on the back of the shutter member 13a and opposite the patch-image detection face (window 12) when the shutter 13 is closed. The device is composed so that when light emitted from a light emitting element 11 is reflected from the intercepting part 19, the light differing in amount from that from the patch image is reflected. Therefore, the surface of the intercepting part 19 is processed so as to given specific roughness. Thus, by roughening the surface of the intercepting part 19, the light from the light emitting element 11 is reflected from intercepting part 19 when the shutter member 13a does not move during image-density detection, and the amount of reflected light at the time is smaller than the amount of light reflected from the patch image. Thus, when the shutter 13 is not opened, it indicates an amount of signal, and the value of a signal from the patch image and the value of a signal from the back of the shutter can be separated. |
