Information recording and reproducing method and apparatus

A method of detecting a location on an optical medium, comprising:

• generating a difference signal from at least two photodetectors arranged perpendicular to a track direction;
• comparing the difference signal with a first reference voltage to generate a first signal;
• comparing the difference signal with a second reference voltage to generate a second signal;
• outputting a pulse of a predetermined duration each time a triggering pulse is detected in the first and second signals to indicate a presence of an identification area when pulses are outputted and a presence of a user area when no pulses are outputted.

An apparatus for detecting a location on an optical medium, comprising:

• at least two photodetectors arranged perpendicular to a track direction to output electrical signals corresponding to incident light;
• an amplifier to generate a difference signal from the electrical signals;
• a first comparator to compare the difference signal with a first reference voltage and to generate a first signal;
• a second comparator to compare the difference signal with a second reference voltage and to generate a second signal;
• an RS flip flop connected to outputs of the first and second comparators to generate an output signal indicating a presence of a land track or a groove track.

An apparatus for detecting a location on an optical medium, comprising:

• at least two photodetectors arranged perpendicular to a track direction to output electrical signals corresponding to incident light;
• an amplifier to generate a difference signal from the electrical signals;
• a first comparator to compare the difference signal with a first reference voltage and to generate a first signal;
• a second comparator to compare the difference signal with a second reference voltage and to generate a second signal;
• and
• a retriggerable multivibrater having a time constant determined by a resistor and a capacitor to generate pulses when triggered by the first and second signals to indicate a presence of an identification area when pulses are outputted and a presence of a user area when no pulses are outputted.