US 2008/0304375 A1 · OPTICAL DISC APPARATUS AND OFFSET ADJUSTMENT METHOD THEREOF

Abstract

An optical disc apparatus includes a laser diode for emitting a laser light, a beam splitter for dividing the laser light into a main beam and sub beam, a main photodetector for detecting the main beam to output a main push-pull signal, a sub photodetector for detecting the sub beam to output a sub push-pull signal, and a subtracter for calculating the main and sub push-pull signals to output a differential push-pull signal, in which an amplification degree of the sub push-pull signal is adjusted so that a DC offset on the differential push-pull signal is adjusted, even in the case where a laser intensity is varied.

Claims16

Dependent claims

An optical disc apparatus for recording information on an optical disc, comprising:

a laser diode that emits a laser light;
a lens that focuses the laser light on the optical disc;
lens adjustment means that adjusts a position of the lens;
means that divides the laser light into a main beam and a sub beam;
means that detects the main beam to output a main push-pull signal;
means that detects the sub beam to output a sub push-pull signal;
means that outputs a differential push-pull signal from the main push-pull signal and the sub push-pull signal;
laser intensity detecting means that detects a laser intensity;
offset amount detecting means that detects an offset amount for each of the main push-pull signal, the sub push-pull signal, and the differential push-pull signal;
and
adjustment means that adjusts the offset amount on the differential push-pull signal in accordance with a variation of the offset amounts on the main push-pull signal, the sub push-pull signal, and the differential push-pull signal, in relation to the laser intensity.

8 more elements

Dependencies are inferred from the claim text.

Optical disc apparatus and offset adjustment method thereof

Life of this patent

Optical disc apparatus and offset adjustment method thereof

Life of this patent

Abstract

Claims16