DIFFERENTIAL PHASE ERROR DETECTOR, AND DIFFERENTIAL METHOD GENERATING A TRACKING ERROR SIGNAL BY DETECTING PHASE ERROR

摘要

PROBLEM TO BE SOLVED: To generate a position error signal independently of a frequency component of recorded data in a differential phase detector for an optical disk recording device. SOLUTION: One pair of diagonal signals S1 and S2 are generated by adding each quadrant A-D of a quadripartite detector. Phase offset among these diagonal signals indicate a position error of an image of a pit at a point of time at which a image of a pit passes through an optical detector. This position error is obtained by calculating a difference between positive correlation and negative correlation of diagonal signals S1 and S2 which are called as dual arm correlation(DAC). Then,Δis correlation offset, L is correlation length. In a suitable actual mode, correlation of offsetΔis adjusted to be suitable so that correlation between S1 and S2 is made the maximum.