| 摘要 |
PURPOSE:To compensate deviation of a focus controlling system due to fluctuations of temperature, etc., even if it occurs, and to perform recording and reproduction in the best state, by correcting the focus controlling system to the best focus state, and performing focus control. CONSTITUTION:A program for focus correction is read out of the 1st memory 31 of a control circuit 29 and on the basis of it, the focus of a recording light beam 2 is varied with time. A focus adjustment signal is supplied to a correcting circuit 37 to supply a voltage corresponding to the voltage between elements A and B to an error amplifier 38 when the output of the element B varies gradually, for example, from a minimum to a maximum. In response to this adjustment signal for the best focus decision, the output of an error amplifier 38 varies to displace a lens 10 in proportion to the output of a moving coil 40. Thus, deviation of a focus cotrolling system due to fluctuations of temperature, etc., is compensated to secure recording and reproduction. |
