Patent ID: 6314068
Filing Date: 2001-11-06
Classification: G11B

Abstract:
An inclination detection apparatus, comprising:an optical system for collecting a beam emitted by a light source onto an information memory medium;a light detector for generating a detection signal in accordance with a light amount of the beam reflected by the information memory medium, the light detector including a first light receiving section and a second light receiving section; anda signal processing section for processing the detection signal, wherein:the information memory medium has a first pattern area and a second pattern area, the first pattern area including tracks having a mark and space array, the tracks being arranged adjacently to each other, the mark and space array having a mark and a space, the second pattern area including groove tracks having grooves, the groove tracks being arranged with a prescribed gap therebetween,the mark and space array in the first pattern area includes a first mark and space array and a second mark and space array, which are arranged to be away from a center of the groove tracks by a prescribed distance in a direction substantially perpendicular to the longitudinal direction of the tracks,the first pattern area and the second pattern area are alternately arranged on the information memory medium in a longitudinal direction of the tracks,the detection signal includes a first detection signal and a second detection signal,the first detection signal includes a first light receiving section signal, a second light receiving section signal, a third light receiving section signal, and a fourth light receiving section signal,the first light receiving section signal is obtained from the first light receiving section when the first mark and space array in the first pattern area is irradiated by the beam collected by the optical system,the second light receiving section signal is obtained from the second light receiving section when the first mark and space array in the first pattern area is irradiated by the beam collected by the optical system,the third light receiving section signal is obtained from the first light receiving section when the second mark and space array in the first pattern area is irradiated by the beam collected by the optical system,the fourth light receiving section signal is obtained from the second light receiving section when the second mark and space array in the first pattern area is irradiated by the beam collected by the optical system,the second detection signal includes a fifth light receiving section signal and a sixth light receiving section signal,the fifth light receiving section signal is obtained from the first light receiving section when the second pattern area is irradiated by the beam collected by the optical system,the sixth light receiving section signal is obtained from the second light receiving section when the second pattern area is irradiated by the beam collected by the optical system,the signal processing section generates an inclination detection signal based on a difference between a first sum signal and a second sum signal, the first sum signal being based on a sum of the first light receiving section signal and the second light receiving section signal, the second sum signal being based on a sum of the third light receiving section signal and the fourth light receiving section signal, andthe signal processing section generates a tracking error signal based on a difference between the fifth light receiving section signal and the sixth light receiving section signal.