Patent ID: 6928041

Claim:
A pre-pit detecting apparatus for an optical recording medium having a recording surface provided with pre-pits which are repeatedly formed between tracks and carries information related to said tracks, comprising: an optical head having a light receiving surface divided into a first and second light receiving faces in the tangential direction of said track, for receiving the reflected light of a light beam radiated onto said recording surface on said first and second light receiving faces to output first and second light detection signals corresponding to respective amounts of the received light on said first and second light receiving faces; a subtractor for calculating the difference between said first and second light detection signals output from said optical head to generate a push-pull signal; a binarization device for comparing said push-pull signal with a threshold value to generate a pre-pit detection signal; a judging device for judging an area to which a position of said recording surface where the light beam is radiated by said optical head belongs of a plurality of areas including at least a not-yet-recorded area and a recorded area; and a threshold setting device for setting said threshold value corresponding to the judgement result of said judging device.