Optical pick-up system with servo using reflection plate having aperture

Claim 1

An optical pick-up system for reading information recorded on an optical disc, said system comprising: a light source; information reading means for reading said information recorded on said optical disc, by using light beams emitted from said light source; error correcting means for detecting an error occurring when said information reading means reads the information and correcting said error; and supporting means for providing optical paths for said information reading means and said error correcting means and supporting both the information reading means and the error correcting means; wherein said information reading means comprises: a beam splitter adapted to transmit a part of incident light beams therethrough and reflect the remaining part of said incident light beams; reflecting means adapted to reflect said light beams transmitted through said beam splitter, at a predetermined reflection angle, and reflect light beams reflected from the optical disc at a predetermined reflection angle; collimating means for converting said light beams reflected from said reflecting means into parallel light beams; and focusing means adapted to focus said parallel light beams emerging from said collimating means onto a surface of the optical disc, and feed light beams reflected from the optical disc to the collimating means; wherein said reflecting means comprises: a first mirror adapted to reflect light beams from said beam splitter at a predetermined angle and light beams carrying said information recorded on said optical disc toward said error correcting means; and a second mirror adapted to reflect light beams from said first mirror toward said collimating means and information-carrying light beams from the collimating means toward the first mirror; wherein said error correcting means comprises: a reflection plate having a aperture surrounded by a reflector so as to reflect a part of the information-carrying light beams reflected from said information reading means at a predetermined angle, and to allow the remaining part of said information-carrying light beams to pass through said aperture; error detecting means, comprising at least two photodetectors, adapted to detect an occurrence of an error, from said information-carrying light beams, said error detecting means comprising a first error detector adapted to detect said light beams reflected from said reflection plate and a second error detector adapted to detect said light beams passing through the reflection plate; and actuating means, adapted to adjust said information reading means, based on an error detection result obtained by said error detecting means; wherein each of said photodetectors is adapted to detect said light beams reflected from said reflection plate when the error has occurred and not to detect the light beams at a normal operation state of said system.