Optical disk apparatus

#This application claims priority to Japanese Patent Application No. 2005-215279 filed on Jul. 26, 2005, which is incorporated herein by reference in its entirety.

#1. Technical Field

#The present invention relates to an optical disk apparatus, and more particularly a technique for demodulating address information from an MSK-modulated wobble signal.

#Preferred embodiments of the present invention will be described in detail by reference to the following figures, wherein:

#FIG. 1 is a block diagram showing the configuration of an optical disk apparatus;

#FIG. 2 is a block diagram showing the configuration of an MSK modulation mark detection circuit in an address decoding circuit; and

#An embodiment of the present invention will be described hereinbelow by reference to the drawings.

#FIG. 1 shows a block diagram of an optical disk apparatus according to the embodiment of the present invention. An optical disk 10 is rotationally driven by a spindle motor (SPM) 12. The spindle motor SPM 12 is driven by a driver 14, and the driver 14 is servo-controlled by a servo processor 30 so as to attain a desired rotational speed. One example of the optical disk 10 is a Blu-ray disk.

#An optical pickup 16 includes a laser diode (LD) for radiating a laser beam onto the optical disk 10, and a photodetector (PD) which receives the light reflected from the optical disk 10 and converts the light into an electric signal. The optical pickup 16 is disposed opposite the optical disk 10. The optical pickup 16 is driven by a sled motor 18 in a radial direction of the optical disk 10, and the sled motor 18 is driven by a driver 20. Like the driver 14, the driver 20 is servo-controlled by the servo processor 30. The LD of the optical pickup 16 is driven by a driver 22, and the driver 22 is controlled by an auto power control circuit (APC) 24 such that a drive current assumes a desired value. The APC 24 controls the drive current of the driver 22 in such a way that optimum recording power selected through OPC (Optimum Power Control) performed in a test area (PCA) of the optical disk 10 is achieved. OPC is processing for recording test data in the PCA of the optical disk 10 while changing the recording power in a plurality of steps, evaluating the quality of a signal by reproducing the test data, and selecting recording power at which desired signal quality is attained. A β value, a γ value, the degree of modulation, a jitter, or the like is used as an index of signal quality.