Patent ID: 6895348

Claim:
A digital-type unusual waveform detection circuit for detecting an unusual waveform of an analog playback signal, said unusual waveform detection circuit comprising: a digitizing unit for performing analog/digital conversion of the analog playback signal; a detecting unit includes, a comparator for comparing output data of the digitizing unit corresponding to voltage of the playback signal with a preset threshold data corresponding to a threshold voltage at each sampling point of the playback signal, outputting sign data of the output data, a delay circuit for delaying the sign data by a predetermined time, and a logic circuit for outputting a first sign data when both output signals from the comparator and the delay circuit have the same sign, outputting a second sign data when the sign of output signal from the comparator differs from the sign of output signal from the delay circuit; and a counting unit for counting the period during which the first data outputs and outputting an unusualness detection signal when the count value exceeds a predetermined threshold.