PURPOSE: To provide an operation sensor using a pair of linear position sensors for detecting of passing of a hole formed in the periphery of a photoreceptor to measure the speed of a photoreceptor for example a photosensitivitive body belt.
CONSTITUTION: Two linear position sensors 30, 32 are positioned in such a manner as to observe passing of an irradiated slit. The sensors are shifted fore and aft and positioned to have an overlapping area. When one slit is moved and separated from a downstream sensor 32, a second slit is moved to be superposed on an upstream sensor 30. The outputs from irradiated sensors 30, 32 are alternately switched to a second sensor. The sensor output is differentiated to provide an output signal showing the speed of a belt. The speed is compared with the speed of a belt driving system, and an error signal is generated to compensate for a detected change of belt speed.
| JP2833903 | IMAGE DEVICE |
| JP2000037905 | IMAGE FORMING APPARATUS |
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