| 摘要 |
PURPOSE:To reduce errors caused by noises, etc., and to obtain a good reproducing signal by constituting a titled device so that binary-coding processing is executed, changing a threshold level in accordance with an output signal of a photodetector for detecting reflected light from an optical recording medium. CONSTITUTION:An output of a photodetector 13 is amplified by a preamplifier 14 and becomes one input of a comparator 16. Also, the output of the photodetector 13 is inverted and amplified by an inverting and amplifying circuit 21. This inverting and amplifying circuit 21 is constituted so as to output a signal which has inverted and amplified an output of an average level of an output signal of the photodetector 13. Accordingly, an output of the inverting and amplifying circuit 21 is that which has inverted a code of a signal corresponding to an average reflection factor of a recording medium 1. The output of the inverting and amplifying circuit 21 is adjusted by a level adjusting circuit 22, and becomes an input to the other of the comparator. Accordingly, the threshold voltage of the comparator 16 becomes a negative level by a voltage portion Er corresponding to the reflection factor from a zero level, and binary-coding is executed by this voltage Er, therefore, it becomes an optimum threshold voltage to the binary-coding. |
