Patent ID: 7948844

Claim:
An information recording/reproducing device which carries out recording or reproducing data by irradiating laser beam on a recording medium including a plurality of recording layers having a track, comprising: a rotation device for rotating the recording medium; a light receiving device for receiving reflected light of the laser beam from the recording medium; a detection device for detecting a boundary point on the recording medium where light quantity of the reflected light changes depending on the condition of other recording layer when the laser beam is irradiated on a track of an arbitrary recording layer of the recording medium for recording or reproducing and condition in radial direction of the other recording layer; a control device for controlling power of the light beam on the basis of the detection result; a rotation angle detection device for detecting rotation angle of the recording medium; and a memorizing device for associating the boundary point with rotation angle at the point of time when the boundary point is detected and for memorizing the boundary point, wherein the control device controls power of the laser beam by the rotation angle at the point of time when the boundary point is detected.