Patent ID: 7307929

Claim:
A tilt correction method for correcting an inclination of an object lens relative to an information recording medium in an optical disk apparatus, the object lens being used to concentrate a light beam onto a recording side of the information recording medium and collect a reflected beam from the recording side, the method comprising the steps of: acquiring first information about a specific inclination of the object lens in response to an access request to the information recording medium, the specific inclination corresponding to one obtained when a signal characteristic of a push-pull signal extracted for track error detection from the reflected beam becomes a prescribed level in or near a target access area; acquiring second information about the optimum inclination of the object lens for the target access area, based on the first information and tilt difference information representing a difference between a first inclination and a second inclination of the object lens defined in advance in a particular area on the information recording medium, the first inclination corresponding to an optimum reproduced signal from said particular area, and the second inclination being obtained when the signal characteristic of the push-pull signal from said particular area becomes said prescribed level; and acquiring tilt correction information for correcting the inclination of the object lens based on the second information.