| 摘要 |
PROBLEM TO BE SOLVED: To correctly control the irradiating state of a light beam by controlling the irradiating state of the light beam with the average value of controlled variables which are stored and in accordance with temps. to absorb the error of the controlled variables. SOLUTION: When command signals to be applied to the driving circuits 13, 14 of a linear motor 1c and an electromagnetic actuator 1d are not generated for a prescribed time, a control circuit 8 judges that the recording and reproducing of information is not present and it reads out respective values of stored offsets and gains till then from a memory 15 to calculate a moving average value and it applies it to an offset and gain switching circuit 9 to change driving controlled variables of the linear motor 1c and the electromagnetic actuator 1d. Then, when an ambient temp. is changed, the circuit 8 is changed to controlled variables related to its ambient temps. and the light beam is subjected to a tracking control and, then, the proper tracking control of the light beam is performed always without being affected by the change in ambient temps. and it is suppressed that an error is generated in recording information and reproducing information. |
