| 摘要 |
PURPOSE:To ensure the proper displacement of a movable part by increasing the gains of a control system including said movable part and a drive part in response to the temperature drop when the frequency of a position control signal is lower than the resonance frequency of the movable part. CONSTITUTION:The component having a frequency less than the resonance frequency f0 of a movable part 27 undergoes the division of pressure with the resistance of a resistor 51 and the series synthetic resistance of a resistor 57 and a thermistor 58 and supplied to an operational amplifier 52 for the focus error signal Et which is supplied to the amplifier 52 through a focus error signal processing part 50 with connection of a gain control circuit 56. That is, the resistance value of the thermistor 58 increases in accordance with the temperature drop and therefore the dividing ratio increases as the temperature drops for said component of the signal Et. Then the gains of said component of the signal Et are increased as the temperature drops through the amplifier 52. Thus the part 27 can have a proper displacement.
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