Patent ID: 6091682
Filing Date: 2000-07-18
Classification: G11B

Abstract:
A pre-pit information detecting device for detecting information recorded in a form of pre-pits on a storage medium which is recorded with movement control information for controlling a moving speed of the storage medium at the time of recording main information on the storage medium and recording control information for use in a recording control at the time of recording the main information, said movement control information being recorded by wobbling information tracks for carrying the main information at a frequency corresponding to the movement control information, said recording control information being recorded by forming the pre-pits on neighboring tracks of the information track in a predetermined relation in phase with the wobbled information tracks, said device comprising:a pickup for irradiating a light beam on the information track and the neighboring tracks at the same time and for outputting a reproduction signal based on the light beam reflected by the information track and the neighboring tracks;a wobbling signal extracting unit for extracting only the wobbling signal indicating the movement control information from the reproduction signal outputted;a pre-pit signal detector for detecting a pre-pit signal multiplexed with the wobbling signal from the reproduction signal outputted;a measuring unit for measuring a pre-pit signal absent period, in which the pre-pit signal detector detects no pre-pit signal, on a wobbling signal period basis; anda detection enabling unit for judging whether or not the pre-pit signal absent period accords with a first predetermined period, and for enabling the pre-pit signal detection by the pre-pit signal detector in a second predetermined period determined on the basis of the wobbling signal period if the pre-pit signal absent period accords with the first predetermined period.