Optical memory medium or device

摘要

The optical device has a disc (12), an optical head (13), a stop (16), and a unit/motor (14) for moving the optical head, so that it crosses over the tracks on the disc. There is also a driving circuit (21) for the motor. The modulation circuit (20) compares a value of the current flowing across the driving circuit with a current indicator value, and varies the pulse width of the pulses fed to the driving circuit according to the comparison. A control unit (23) observes the value from the current indicator, monitors the width of the pulses from the modulation circuit and confirms that the optical head is at the stop.