Discrimination circuit for the prefabricated master - pits and the prefabricated master - grooves on an optical disc

摘要

PURPOSE: To obtain a circuit which discriminates pits/groups in both of during tracking and crossing of track arrays of an optical pickup. ;CONSTITUTION: The output signals from a photodetector impressed to input terminals 9 and 10 are added in an adder circuit 11 and thereafter, the added signal is impressed to first and second transistors 12 and 13. The output signal from the first TR 12 is envelope detected by a capacitor 14 and is subtracted from the output signal of the second TR 13 in a subtraction circuit 17. The output signal of the subtraction circuit 17 is compared with a reference value Vref in a comparator circuit 18. The output signal of this comparator circuit 18 according to the result of the comparison is impressed by a retrigger monomultivibrator 19. The output signal meeting the result of the discrimination of the pits/groups of the optical disk is generated from this retrigger monomultivibrator 19.;COPYRIGHT: (C)1995,JPO