Patent ID: 6801491
Filing Date: 2004-10-05
Classification: G11B

Abstract:
A focus error detecting apparatus of an optical pickup, for detecting a focus error of an emission light in the optical pickup for writing optical disc recording information onto an information recording surface of an optical disc by said emission light emitted from a light source or reading out said optical disc recording information from return light which is emitted from said light source and reflected and returned by said information recording surface of said optical disc, comprising:an integrated lens device constituted by a plurality of eccentric cylindrical lenses, which separates the light existing in a first quadrant region and a third quadrant region on a plane that is perpendicular to an optical axis of said return light to a optical path, separates the light existing in a second quadrant region and a fourth quadrant region on the plane that is perpendicular to said optical axis to a second optical path, applies a first astigmatism to the light on said first optical path to thereby obtain first processing light, and applies a second astigmatism in a direction that is inclined by 90Â° for said first astigmatism to the light on said second optical path to thereby obtain second processing light; a first photodetector having four trapezoidal first photosensing portions formed by dividing a photosensing area into four portions by lightning-shaped dividing lines and for receiving and detecting said first processing light; a second photodetector having other four trapezoidal second photosensing portions formed by dividing a photosensing area into four portions by other lightning-shaped dividing lines and for receiving and detecting said second processing light; and focus error discrimination value operating means for performing predetermined arithmetic operations to an intensity of each light received by the four portions of said first photosensing portions and an intensity of each light received by the four portions of said second photosensing portions and generating a focus error discrimination value.