Optical information apparatus and gap control method thereof

An optical information apparatus that records and/or reproduces information using an information recording medium, comprising:

• a light source that outputs light;
• an optical system that forms a predetermined sized beam spot on the information recording medium using the light from the light source;
• a power detection unit that detects output power of the light source and generates a power detection signal;
• a power control unit that controls the output power of the light source using the power detection signal;
• a gap detection unit that detects a gap length between the information recording medium and the optical system, and generates a gap detection signal;
• a correction unit that generates a corrected gap detection signal by removing, from the gap detection signal, a fluctuation component which is not less than a gain crossover frequency of the power control unit;
• and
• a gap control unit that controls the gap length between the information recording medium and the optical system using the corrected gap detection signal, wherein,
• the correction unit includes:
• a filter unit that extracts a fluctuation component, which is not less than the gain crossover frequency of the power control unit, from the power detection signal;
• and
• a fluctuation component removal unit that generates the corrected gap detection signal by removing, from the gap detection signal, the fluctuation component extracted by the filter unit.

A gap control method for an optical information apparatus that records and/or reproduces information using an information recording medium, comprising:

• a first step of detecting output power of a light source that outputs light and generating a power detection signal;
• a second step of controlling the output power of the light source using the power detection signal;
• a third step of detecting a gap length between the information recording medium and an optical system which forms a predetermined sized beam spot on the information recording medium using the light from the light source, and generating a gap detection signal;
• a fourth step of generating a corrected gap detection signal by removing, from the gap detection signal, a fluctuation component which is not due to fluctuation of the gap between the information recording medium and the optical system;
• and
• a fifth step of controlling the gap length between the information recording medium and the optical system using the corrected gap detection signal, wherein
• a gain crossover frequency of the power control in the second step is greater than a gain crossover frequency of the gap control in the fifth step, and
• the fourth step includes:
• a sixth step of extracting a fluctuation component of the output power of the light source from the power detection signal;
• and
• a seventh step of generating the corrected gap detection signal by removing, from the gap detection signal, the fluctuation component extracted in the sixth step.

A gap control method for an optical information apparatus that records and/or reproduces information using an information recording medium, comprising:

• a first step of detecting output power of a light source that outputs light and generating a power detection signal;
• a second step of controlling the output power of the light source using the power detection signal;
• a third step of detecting a gap length between the information recording medium and an optical system which forms a predetermined sized beam spot on the information recording medium using the light from the light source, and generating a gap detection signal;
• a fourth step of generating a corrected gap detection signal by removing, from the gap detection signal, a fluctuation component which is not less than a gain crossover frequency of the power control in the second step;
• and
• a fifth step of controlling the gap length between the information recording medium and the optical system using the corrected gap detection signal, wherein
• the fourth step includes:
• a sixth step of extracting a fluctuation component, which is not less than the gain crossover frequency of the power control in the second step, from the power detection signal;
• and
• a seventh step of generating the corrected gap detection signal by removing, from the gap detection signal, the fluctuation component extracted in the sixth step.