| 摘要 |
PURPOSE:To prevent the malfunction of an optical information recorder and reproducing device so as to improve the reliability of the device, by detecting the dew condensation of an objective in accordance with the change of focus signals obtained from the light transmitted through the objective against control signals for driving the objective. CONSTITUTION:Focus error signals obtained from the light transmitted through an objective are inputted to an input terminal 1a and control signals for driving the objective are inputted to another input terminal 1b. Since the control signals are inputted as the signal of a negative side area in a fixed cycle in a state when dew condensation takes place, the output of a NAND circuit 4 is maintained at 0V. Therefore, when the voltage charging a peak hold circuit 5 drops lower than the reference voltage of a comparator 6, the output of the NAND circuit 4 is inverted and a dew signal is outputted. Accordingly, dew condensation on the objective can be caught directly and malfunctions of this optical information recorder and reproducing device can be prevented. As a result, the reliability of the device is improved. |
