Patent ID: 8787137
Filing Date: 2014-07-22
Classification: G11B

Abstract:
1. An optical pickup device comprising: a laser light source; a collimating optical system for converting laser light emitted from the laser light source to parallel light; a focusing optical system for focusing the parallel light to which the laser light is converted onto an optical disc; a light detection unit for receiving returning light returning by reflection, from the optical disc, of the light focused by the focusing optical system, and outputting a detection signal; and a reflecting mirror disposed between the collimating optical system and the focusing optical system; wherein the reflecting mirror has a reflecting surface, the reflecting surface having a central region and first and second outside regions located outside the central region; the central region on the reflecting surface meets the first and second outside regions on the reflecting surface, at respective positions illuminated by the light focused by the focusing optical system, in two boundary lines parallel to a radial direction on the optical disc; and a ratio of a reflectance of the central region to reflectances of the first and second outside regions is defined by the following mathematical expression: where Ri denotes the reflectance of the central region; Ro denotes the reflectances of the first and second outside regions; and x denotes a rim light intensity measured on a percentage basis, assuming that a value of Ri/Ro is equal to 1 with respect to a predetermined focused spot diameter on the optical disc.