Patent ID: 7652963

Claim:
A circuit for detecting a recorded area of an optical disk, the circuit comprising: a counter for detecting an unrecorded area; and a counter for detecting a recorded area, wherein the counter for detecting an unrecorded area receives a reference clock, outputs an unrecorded area detection signal as a first output, and outputs a reset signal to the counter for detecting a recorded area as a second output, respective times elapsed until the unrecorded area detection signal as the first output is outputted, and until the reset signal is outputted to the counter for detecting a recorded area as the second output satisfy a relationship represented by: Time Elapsed Until Unrecorded Area Detection Signal as First Output is Outputted>Time Elapsed Until Reset Signal is Outputted to Counter for Detecting Recorded Area as Second Output, and the counter for detecting a recorded area receives a digitized signal obtained by digitizing an RF signal from the optical disk and produces an output serving as a reset signal for resetting the counter for detecting an unrecorded area and also as a recorded area detection signal.