Optical disc drive, optical storage medium, optical storage medium inspection apparatus, and optical storage medium inspection method

Abstract

An optical disc drive having an optical pickup head emitting a light beam to an optical storage medium, detecting the light beam reflected from the optical storage medium, and outputting a signal based on the received reflected light, having a jitter measuring unit measuring jitter in signals output from the optical pickup head and having an evaluation unit determining from the measured jitter if the optical storage medium is good or defective. The jitter measuring unit measures jitter in a train of 3T or longer marks or spaces from an optical storage medium to which digital information is recorded as a train of marks or spaces of length kT based on a period T and an integer k of two or more.

The invention claimed is: 
     
       1. An optical storage medium inspection method for determining a quality of an optical storage medium, said method comprising:
 emitting a light beam from an optical pickup head to the optical storage medium to which digital information is recorded as a train of marks or spaces of length kT based on a period T and an integer k which is equal to 2 or greater;   receiving light reflected by a mark or space;   measuring jitter in signals, based on the reflected light obtained only from such edges that each edge is located between a mark having a length equal to 3 T or longer and a space having a length equal to 3 T or longer; and   determining from the measured jitter whether the optical storage medium has a predetermined quality.   
     
     
       2. A reproducing method for reproducing digital information on an optical storage medium that has been inspected by an inspection method that includes emitting a light beam from an optical pickup head to the optical storage medium to which digital information is recorded as a train of marks or spaces of length kT based on a period T and an integer k which is equal to 2 or greater, receiving light reflected by a mark or space, measuring jitter in signals, based on the reflected light obtained only from such edges that each edge is located between a mark having a length equal to 3T or longer and a space having a length equal to 3T or longer, and determining from the measured jitter whether the optical storage medium has a predetermined quality, said reproducing method comprising:
 emitting a laser beam having a wavelength of 405 nm through an objective lens having a numerical aperture of 0.85 to the optical storage medium;   receiving light reflected by a mark or a space formed on the optical storage medium, the mark or space having the length kT, wherein the optical storage medium comprises a first recording layer and a second recording layer, such that the first recording layer is disposed closer to a laser beam incidence side of the optical storage medium than the second recording layer;   setting a first threshold for accepting a jitter measured with respect to the first recording layer to be greater than a second threshold for accepting a jitter measured with respect to the second recording layer;   identifying a type of the optical storage medium using recorded information specific to the optical storage medium; and   controlling a drive speed of the optical storage medium using the recorded information specific to the optical storage medium.    
     
     
       3. A recording method for recording digital information on an optical storage medium that has been inspected by an inspection method that includes emitting a light beam from an optical pickup head to the optical storage medium to which digital information is recorded as a train of marks or spaces of length kT based on a period T and an integer k which is equal to 2 or greater, receiving light reflected by a mark or space, measuring jitter in signals, based on the reflected light obtained only from such edges that each edge is located between a mark having a length equal to 3T or longer and a space having a length equal to 3T or longer, and determining from the measured jitter whether the optical storage medium has a predetermined quality, said recording method comprising:
 emitting a laser beam having a wavelength of 405 nm through an objective lens having a numerical aperture of 0.85 to the optical storage medium so as to form a mark on the optical storage medium, wherein the optical storage medium comprises a first recording layer and a second recording layer, such that the first recording layer is disposed closer to a laser beam incidence side of the optical storage medium than the second recording layer;   setting a first threshold for accepting a jitter measured with respect to the first recording layer to be greater than a second threshold for accepting a jitter measured with respect to the second recording layer, wherein the optical storage medium stores recording condition information;   identifying a type of the optical storage medium using recorded information specific to the optical storage medium; and   controlling a drive speed of the optical storage medium using the recorded information specific to the optical storage medium, so as to form marks and spaces, each of the marks and spaces having the length kT.