Patent ID: 8625399

Claim:
An optical disc reproducing apparatus which reproduces information out of a plurality of optical discs of which number of recoding layers are different, the apparatus comprising: a laser which emits a laser beam of a predetermined wavelength; an optical disc discriminating unit for discriminating kinds of optical discs; a high-frequency wave generation circuit for superposing a high-frequency wave of a predetermined amplitude onto the laser beam emitted from the laser; and a laser power control circuit for controlling a laser power of the laser beam, wherein: the optical disc discriminating unit discriminates on whether an optical disc having a plurality of recording layers including a first recording layer disposed at a position of a first distance from a surface of the optical disc and a second recording layer disposed at a position of a second distance from the surface of the optical disc is mounted, a laser power irradiated onto the first recording layer and a laser power irradiated onto the second recording layer are needed to be differentiate, when the optical disc discriminating unit discriminates that the optical disc having a plurality of recording layer is mounted in the optical disc apparatus, the high-frequency wave generation circuit superposes a high frequency wave of a first amplitude onto the laser beam irradiated from the laser when reproducing information recorded on the first recording layer, and superposes a high-frequency wave of a second amplitude which is smaller than the first amplitude onto the laser beam when reproducing information recorded on the second recording layer, when the optical disc discriminating unit discriminates that the optical disc having a plurality recording layers is mounted in the optical disc apparatus, the laser power controlling circuit controls the laser to irradiate the laser beam superposed by the high-frequency wave of the first amplitude on to the first recording layer with a first laser power when the information recorded on the first recording layer is reproduced, and to irradiate the laser beam superposed with the high-frequency wave of the second amplitude with a second laser power which is smaller than the first laser power onto the second recording layer when the information recorded on the second recording layer is reproduced, and a ratio of the first amplitude and the first laser power and a ratio of the second amplitude and the second laser power are the substantially equal.