Patent ID: 6333818
Filing Date: 2001-12-25
Classification: G11B

Abstract:
An optical pickup device comprising:a light emitting means capable of emitting a recording light beam or a reading light beam on to an information recording medium, for recording information on or reading information from the recording medium;a light treating means capable of producing at least two guide beams on to the recording medium;a first light receiving means capable of receiving a reflected light generated when the recording light beam or the reading light beam is incident on the recording medium;a second light receiving means and a third light receiving means each capable of receiving a reflected light generated due to a guide beam;a focus error signal generating means provided for performing calculation on various output signals fed from each light receiving means so as to produce a focus error signal;characterized in that:a light beam is emitted from the light emitting means and is passed through the light treating means to form three optical paths extending to the first, second and third light receiving means, the second light receiving means is disposed at a position forming a longer optical path than an optical path associated with the first light receiving means, the third light receiving means is disposed at a position forming a shorter optical path than the optical path associated with the first light receiving means;the light-receiving area of each of the second and third light receiving means is non-symmetrically divided into two portions;the second light receiving means and the third light receiving means are arranged symmetrically with respect to the first light receiving means.