Patent ID: 8098560
Filing Date: 2012-01-17
Classification: G11B

Abstract:
1. A light spot position control apparatus comprising: a first light source; a second light source; a beam splitter that splits a light beam emitted from the second light source into m light beams; an optical system that allows a first light beam emitted from the first light source and the m light beams generated by the beam splitter to irradiate a disk-shaped recording medium, where grooves and lands are alternately formed with an equal width in a radial direction thereof so that the grooves are formed in a spiral shape or a concentric shape, through a common objective lens, wherein the optical system allows the m light beams to irradiate the disk-shaped recording medium so that an interval of irradiating spots of the m light beams irradiating the disk-shaped recording medium in the radial direction is 1/m of a pitch of tracks formed on the disk-shaped recording medium according to the formation of the grooves; a tracking control mechanism that is configured to perform tracking control on the light beam irradiated through the objective lens by changing a relative positional relationship between the optical axis of the light beam irradiated through the objective leans and the disk-shaped recording medium in the radial direction; a light receiving unit that individually receives the m light beams irradiated through the objective lens from disk-shaped recording medium; an error signal generation unit that generates error signals representing radial position errors of the spot positions of the m light beams with respect to the tracks formed on the disk-shaped recording medium based on received signals obtained by the light receiving unit; an error signal selector that selects at least one error signal among the error signals generated by the error signal generation unit; and a servo controller that controls the tracking control mechanism to perform the tracking servo on the light beam irradiated through the objective lens based on the error signal selected by the error signal selector.