| 摘要 |
PURPOSE:To stop quickly a linear motor, on which an optical head is mounted, of an optical disc device when the linear motor falls into the runaway state, by stopping the linear motor through a comparing means when the detected actual speed reaches a set reference speed. CONSTITUTION:If the linear motor enters into the runaway state at a stop time, a voltage Vb corresponding to the set reference speed reaches a voltage Va corresponding to the detected actual speed, and the output of a comparator 1 in a detecting part A is inverted to the low level, and the output of an OR circuit 3 goes to the low level also. Meanwhile, if the linear motor enters into the runaway state at a moving time, the output of the OR circuit 3 is inverted to the low level similarly, and a low-level runaway signal E is outputted from an AND circuit 4. An FF16 in a driving part B is inverted by this signal E, and a relay 20 is degaussed by an OR circuit 18, a transistor TR19, etc., and a contact 22 is switched to the normal close side, and power of a power source 23 is not suppled to a linear motor coil 24, and a counter electromotive force due to inertial turning is generated by short-circuit of the normal close side of the contact 22, and the linear motor is stopped quickly. |
