Patent ID: 7339875

Claim:
An information playback method for reading out information by irradiating an optical spot on an information recording medium having a plurality of tracks, said method comprising the steps of: irradiating said optical spot simultaneously on a first track and a second track adjacent to said first track, among said plurality of tracks; and maintaining an orthogonal relation with a depth of a recorded mark recorded on said first track and a depth of a recorded mark recorded on said second track, when both the recorded marks are converted to electric signals, wherein when a readout signal from said first track is S 1 and a readout signal from said second track is S 2 , frequencies of carrier waves of said S 1 and said S 2 are equal frequency but both phases are deviated by 90 degrees from each other, information bits “1” and “0” of said S 1 are deviated by 180 degrees in phases, and information bits “1” and “0” of said S 2 are deviated by 180 degrees in phases.