| 摘要 |
<p>A light sensor generates a detection signal upon receiving laser light. A rotation sensor generates a rotation signal in synchronization with rotation of a polygon motor. A mirror-rotation-signal generating section generates a mirror rotation signal, based on the detection signal. A motor-rotation-signal generating section generates a motor rotation signal, based on the rotation signal. A phase-difference measuring section measures a phase difference between the motor rotation signal and the mirror rotation signal. A prediction-signal generating section generates a prediction signal that is delayed from the motor rotation signal by the phase difference. A switching section switches a control mode between: a mirror control mode in which the mirror rotation signal is used to control a rotational speed of the polygon mirror; and a prediction control mode in which the prediction signal is used to control the rotational speed. A motor driver drives the polygon motor in the selected control mode.</p> |
