Patent ID: 6392965
Filing Date: 2002-05-21
Classification: G11B

Abstract:
An optical pickup device comprising:a light source; an optical system which converges light projected by said light source onto a recording medium and directs reflected light from the recording medium to a photoreceptor element; a photoreceptor element which detects the reflected light; a diffracting element, which diffracts reflected light from the recording medium and directs it to said photoreceptor element, divided into at least two divisions by a dividing line intersecting substantially at right angles with a diffraction direction; said photoreceptor element including at least two main photoreceptive domains divided from one another by a dividing line, which receive reflected light corresponding to a focusing error of the light projected onto the recording medium, and an auxiliary photoreceptive domain which detects reflected light which exceeds said main photoreceptive domains in a defocused state; wherein said auxiliary photoreceptive domain is provided adjacent to an end of said main photoreceptive domains in the direction of the dividing line; and wherein a focusing error signal is produced based on diffracted light from at least one of said divisions.