DISK DRIVE DEVICE AND PRE-PIT DETECTION METHOD, ESPECIALLY CONCERNED WITH PERFORMING RECORDING/REPRODUCING PROCESSES ON A DISK STORAGE MEDIUM SUCH AS AN OPTICAL DISK

摘要

PURPOSE: A disk drive device and a pre-pit detection method are provided to detect a noise pulse based on a pulse width by including the noise pulse in a land pre-pit detection signal obtained by comparing a push-pull signal with a reference voltage, and to remove the detected noise pulse, thereby obtaining a proper pre-pit detection signal. CONSTITUTION: A land pre-pit detection signal is supplied to a noise pulse remover(70). The noise pulse remover(70) removes a noise pulse. The land pre-pit detection signal without any noise is outputted from the noise pulse remover(70), and is supplied to an address decoder to obtain address information. The noise pulse remover(70) comprises as follows. A down edge detection circuit is formed by an AND gate(73) and D flip-flop units(71,72). A detection signal outputted from a comparator(61) becomes a D input of the D flip-flop unit(71), while a clock is applied to the D flip-flop unit(71) to be latched. An output of the D flip-flop unit(71) is supplied to the D flip-flop unit(72), and is reversed to be given to the AND gate(73). An output of the D flip-flop unit(72) is supplied to the AND gate(73), and is given to a counter(74) as an enable signal and a clear signal.