| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable continuation of a stable control even in case of an abnormality in a sensor or in an object detected by the sensor (scale pattern) without increasing the number of sensors and to prevent a stoppage of device operation or the like at low cost. <P>SOLUTION: Control signals include a signal (first signal) by a surface sensor for reading a scale provided on a rotator (belt or drum) and a signal (second signal) from a motor shaft encoder. The rotator is driven based on the signal from the motor shaft encoder. When the feedback signal is changed from the second signal to the first signal at an optional time, whether or not abnormality is present in the surface sensor is determined. When the surface sensor has no abnormality, a control means selects the first signal as the feedback signal, and the rotator is driven based on the first signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
