PURPOSE: To improve the reliability of information reproduction on an optical disk by generating a slice level according to the difference between the maximum value of the signal of a data start part and the maximum value of the signal of the following area and slicing the signal according to the level.
CONSTITUTION: The reproduced signal from a gap part is separated by an amplifier 21 into a positive-polarity signal and a negative-polarity signal, and holders 22 and 23 detects their peak value and bottom value; and a difference circuit 24 calculates their difference and the difference signal is sampled and held. The difference signal generated by subtracting the sampled and held signal from the signal amplitude between the peak value and bottom value of the reproduced signal from a data part is multiplied by 1/2 through a multiplier 27 to become the slice level. A comparator 28 compares the signal from the amplifier 21 with the slice level and outputs a high level 1 when the signal is larger than the slice level, thereby converting the reproduced signal into a binary signal. Consequently, the accurate slice level is detected from the reproduced signal to stably read the signal out of the optical disk.
IZUMI HARUHIKO
TAGUCHI MASAKAZU
