REPRODUCING SIGNAL DETECTING CIRCUIT

PURPOSE:To simplify a circuit constitution and to improve the reliability of the reproducing data by making the signal of the amplitude of the same extent with the amplitude center as a same level into a reproducing signal even when any signal of a prepit area and a magneto-optical pit area is reproduced. CONSTITUTION:A prescribed quantity level of a reference signal ref equal to the level when an adder circuit 7 output is 0 is shifted in a level shifting circuit 11 and an output ref' is given to the input terminal of a differential amplifier 9. A switching signal SW is given to the low active enable terminal of switching differential amplifiers 8 and 9, and given through an inverter 10 to the enable terminal of the amplifier 8 and directly to the amplifier 9. Consequently, at the time of reproducing the prepit information reproduction, the signal SW is made low and at the time of reproducing the magneto-optical pit area, it is made high. Thus, even when any signal is reproduced, the oscillation waveform with 0 as a center is obtained, a circuit constitution is simplified and the reliability of the reproducing data is improved.