Laser power controller and optical disk device

Abstract

A power control device for controlling a power of a light source of an optical beam directed to an optical medium. The power control device includes a reflected light detector for detecting reflected light from the optical medium when irradiated by an optical beam which is following a track; an arithmetic unit for calculating from the reflected light a transmissivity of light transmitted from a disk surface to a recording layer or an amount of directed light on the recording layer of the medium; and power control means for controlling the power of the light source for emission based on a calculation result produced by the arithmetic unit.

1. An optical disk apparatus for recording or reproduction on an optical disk including a track in which a recording region is wobble-processed, comprising:
 optical means for reading information from the optical disk or recording information in the optical disk;    signal generation means for generating a tracking error signal indicating a scanning state of the optical means on the track included in the optical disk by the optical means;    extraction means for extracting a wobble signal from the tracking error signal;    amplitude detection means for detecting a wobble envelope voltage representing an amplitude of the wobble signal based on the wobble signal extracted by the extraction means;    a bias generation circuit for outputting an average value of the wobble envelope voltage as a bias voltage;    an arithmetic unit for calculating a positive square root of the wobble envelope voltage with respect to the bias voltage assumed as being “1”, and outputting a reciprocal of the calculated positive square root as a calculation result; and    recording power control means for controlling recording power when the optical means records the information in the optical disk, based on the calculation result.    
     
     
       2. An optical disk apparatus according to  claim 1 , wherein:
 the optical disk apparatus is capable of recording data in a guiding groove portion and an inter-guiding groove portion of the optical disk;    the optical disk apparatus further comprises identification means for identifying whether a track scanned by the optical means is in the guiding groove portion or the inter-guiding groove portion; and    the bias generation circuit generates two types of bias voltages, a bias voltage for recording in the guiding groove portion and a bias voltage for recording in the inter-guiding groove portion, based on an identification result by the identification means.    
     
     
       3. An optical disk apparatus according to  claim 1 , wherein the arithmetic unit calculates a positive square root of the wobble envelope voltage with respect to the bias voltage assumed as being “1”, and provides a value obtained by adding “1” to a result of subtraction of the positive square root from “1” as a calculation result. 
     
     
       4. An optical information recording apparatus for recording on or reproducing from an optical information recording medium including a track in which a recording region is wobble- processed, comprising:      optical means for reading information from the optical information recording medium or recording information in the optical information recording medium;        signal generation means for generating a tracking error signal indicating a scanning state of the optical means on the track included in the optical information recording medium, based on the information read from the optical information recording medium by the optical means;        extraction means for extracting a wobble signal from the tracking error signal;        amplitude detection means for detecting a wobble envelope voltage representing an amplitude of the wobble signal based on the wobble signal extracted by the extraction means;        a bias generation circuit for generating an average value of the wobble envelope voltage as a bias voltage;        an arithmetic circuit for calculating a positive square root of the wobble envelope voltage in the case that the bias voltage is assumed as being “ 1 ”, and outputting a reciprocal of the calculated positive square root as a calculation result; and        recording power control means for controlling recording power when the optical means records the information in the optical information recording medium, based on the calculation result.     
     
     
       5. An optical information recording apparatus for recording on or reproducing from an optical information recording medium including a track in which a recording region is wobble- processed, comprising:      optical means for reading information from the optical information recording medium or recording information in the optical information recording medium;        signal generation means for generating a tracking error signal indicating a scanning state of the optical means on the track included in the optical information recording medium, based on the information read from the optical information recording medium by the optical means;        extraction means for extracting a wobble signal from the tracking error signal;        amplitude detection means for detecting a wobble envelope voltage representing an amplitude of the wobble signal based on the wobble signal extracted by the extraction means;        a bias generation circuit for generating an average value of the wobble envelope voltage as a bias voltage;        an arithmetic circuit for calculating a positive square root of the wobble envelope voltage in the case that the bias voltage is assumed as being “ 1 ”, and outputting a value obtained by adding “ 1 ” to a result of subtraction of the calculated positive square root from “ 1 ” as a calculation result; and        recording power control means for controlling recording power when the optical means records the information in the optical information recording medium, based on the calculation result.     
     
     
       6. An optical information recording apparatus according to any one of  claim 5  or  6 , wherein:
   the optical information recording medium is capable of recording data in a guiding groove portion and an inter - guiding groove portion of the optical information recording medium;        the optical information recording apparatus further comprises identification means for identifying whether a track scanned by the optical means is in the guiding groove portion or the inter - guiding groove portion; and        the bias generation circuit generates two types of bias voltages, a bias voltage for recording in the guiding groove portion and a bias voltage for recording in the inter - guiding groove portion, based on an identification result by the identification means.