Optical output adjusting apparatus based on shortest recording marks

An optical output adjustment apparatus for adjusting an output level of a reproducing laser beam, in a signal reproducing device which adopts a magnetic wall movement detection reproducing method, irradiates the reproducing laser beam onto a magneto-optical information recording medium on which data is recorded by recording marks having different recording lengths according to a predetermined modulation method, and magnifies a magnetic sector by magnetic wall movement, thereby to perform reproducing of the data, characterized in that

• the optical output adjustment apparatus comprises:
• a light source for emitting the reproducing laser beam;
• first reproducing signal detector means for detecting a first recording mark reproducing signal corresponding to a component of a first recording mark in a reproducing signal obtained by reproducing the magneto-optical information recording medium;
• second reproducing signal detector means for detecting a second recording mark reproducing signal corresponding to a component of a second recording mark in a reproducing signal obtained by reproducing the magneto-optical information recording medium;
• first signal amplitude level detector means for detecting a first amplitude level of the first recording mark reproducing signal;
• second signal amplitude level detector means for detecting a second amplitude level of the second recording mark reproducing signal;
• difference value calculator means for calculating a difference value between the first and second amplitude levels;
• comparator means for comparing the amplitude level with a predetermined threshold value;
• and
• optical output control means for adjusting the reproducing laser beam to an output level which makes the amplitude level equal to or lower than the predetermined threshold value.

An optical output adjustment apparatus for adjusting an output level of a reproducing laser beam, in a signal reproducing device which adopts a magnetic wall movement detection reproducing method, irradiates the reproducing laser beam onto a magneto-optical information recording medium on which data is recorded by recording marks having different recording lengths according to a predetermined modulation method, and magnifies a magnetic sector by magnetic wall movement, thereby to perform reproducing of the data, characterized in that

• the optical output adjustment apparatus comprises:
• a light source for emitting the reproducing laser beam;
• reproducing signal detector means for detecting a high-frequency reproducing signal consisting of a high-frequency component in a reproducing signal obtained by reproducing the magneto-optical information recording medium;
• signal amplitude level detector means for detecting an amplitude level of the high-frequency reproducing signal;
• comparator means for comparing the amplitude level with a predetermined threshold value;
• and
• optical output control means for adjusting the reproducing laser beam to an output level which makes the amplitude level equal to or higher than the predetermined threshold value.

An optical output adjustment apparatus for adjusting an output level of a reproducing laser beam, in a signal reproducing device which adopts a magnetic wall movement detection reproducing method, irradiates the reproducing laser beam onto a magneto-optical information recording medium on which data is recorded by recording marks having different recording lengths according to a predetermined modulation method, and magnifies a magnetic sector by magnetic wall movement, thereby to perform reproducing of the data, characterized in that

• the optical output adjustment apparatus comprises:
• a light source for emitting the reproducing laser beam;
• differentiator means for differentiating a reproducing signal obtained by reproducing the magneto-optical information recording medium, thereby to output a differential signal;
• signal amplitude level detector means for detecting an amplitude level of the differential signal;
• comparator means for comparing the amplitude level with a predetermined threshold value;
• and
• optical output control means for adjusting the reproducing laser beam to an output level which makes the amplitude level equal to or higher than the predetermined threshold value.

An optical output adjustment apparatus for adjusting an output level of a reproducing laser beam, in a signal reproducing device which adopts a magnetic wall movement detection reproducing method, irradiates the reproducing laser beam onto a magneto-optical information recording medium on which data is recorded on a data area by recording marks having different recording lengths according to a predetermined modulation method and a reproducing power adjustment repetitive pattern constructed only by shortest marks is written in a reference area, and magnifies a magnetic sector by magnetic wall movement, thereby to perform reproducing of the data, characterized in that

• the optical output adjustment apparatus comprises:
• a light source for emitting the reproducing laser beam;
• reproducing signal detector means for detecting a power adjustment reproducing signal obtained by reproducing the reproducing power adjustment repetitive pattern;
• signal amplitude level detector means for detecting an amplitude level of the power adjustment reproducing signal;
• comparator means for comparing the amplitude level with a predetermined threshold value;
• and
• optical output control means for adjusting the reproducing laser beam to an output level which makes the amplitude level equal to or higher than the predetermined threshold value.

An optical output adjustment apparatus for adjusting an output level of a reproducing laser beam, in a signal reproducing device which adopts a magnetic wall movement detection reproducing method, irradiates the reproducing laser beam onto a magneto-optical information recording medium on which data is recorded in a data area by recording marks having different recording lengths according to a predetermined modulation method and a reproducing power adjustment pattern constructed only by first and second marks having different lengths is written in a reference area, and magnifies a magnetic sector by magnetic wall movement, thereby to perform reproducing of the data, characterized in that

• the optical output adjustment apparatus comprises:
• a light source for emitting the reproducing laser beam;
• first reproducing signal detector means for detecting a first mark reproducing signal corresponding to a component of the first mark in a power adjustment reproducing signal obtained by reproducing the reproducing power adjustment pattern;
• second reproducing signal detector means for detecting a second mark reproducing signal corresponding to a component of the second mark in a power adjustment reproducing signal obtained by reproducing the reproducing power adjustment pattern;
• first signal amplitude level detector means for detecting an amplitude level of the first mark reproducing signal;
• second signal amplitude level detector means for detecting an amplitude level of the second mark reproducing signal;
• difference value calculator means for calculating a difference value between the first and second amplitude levels;
• comparator means for comparing the difference value with a predetermined threshold value;
• and
• optical output control means for adjusting the reproducing laser beam to an output level which makes the amplitude level equal to or lower than the predetermined threshold value.

An optical output adjustment apparatus for adjusting an output level of a reproducing laser beam, in a signal reproducing device which adopts a magnetic wall movement detection reproducing method, irradiates the reproducing laser beam onto a magneto-optical information recording medium on which data is recorded on a data area by recording marks having different recording lengths according to a predetermined modulation method and a reproducing power adjustment repetitive pattern is written in a reference area, and magnifies a magnetic sector by magnetic wall movement, thereby to perform reproducing of the data, characterized in that

• the optical output adjustment apparatus comprises:
• a light source for emitting the reproducing laser beam;
• reproducing signal detector means for detecting a high-frequency component in a power adjustment reproducing signal obtained by reproducing the reproducing power adjustment repetitive pattern;
• signal amplitude level detector means for detecting an amplitude level of the high-frequency reproducing signal;
• comparator means for comparing the amplitude level with a predetermined threshold value;
• and
• optical output control means for adjusting the reproducing laser beam to an output level which makes the amplitude level equal to or higher than the predetermined threshold value.

An optical output adjustment apparatus for adjusting an output level of a reproducing laser beam, in a signal reproducing device which adopts a magnetic wall movement detection reproducing method, irradiates the reproducing laser beam onto a magneto-optical information recording medium on which data is recorded on a data area by recording marks having different recording lengths according to a predetermined modulation method and a reproducing power adjustment pattern is written in a reference area, and magnifies a magnetic sector by magnetic wall movement, thereby to perform reproducing of the data, characterized in that

• the optical output adjustment apparatus comprises:
• a light source for emitting the reproducing laser beam;
• differentiator means for differentiating a power adjustment reproducing signal obtained by reproducing the reproducing power adjustment pattern, thereby to output a differential signal;
• signal amplitude level detector means for detecting an amplitude level of the differential signal;
• comparator means for comparing the amplitude level with a predetermined threshold value;
• and
• optical output control means for adjusting the reproducing laser beam to an output level which makes the amplitude level equal to or higher than the predetermined threshold value.