Patent ID: 7065023

Claim:
A light spot moving direction judging device for detecting reflected light coming from a main spot formed on an optical disc by a first light beam irradiated onto the optical disc and the reflected light coming from a side spot formed on the optical disc by a second light beam also irradiated onto the optical disc and for judging a radial moving direction of the main spot based on an outcome of the detection, said optical disc having lands and grooves helically arranged side by side on a surface thereof and operating as recording tracks, each pair of said lands located adjacently and sandwiching a groove and/or each pair of said grooves located adjacently and sandwiching a land respectively having different heights and/or depths, said device comprising: first computing means for computationally producing a difference signal of two signals obtained by detecting a quantity of the reflected light coming from the main spot by means of first two divided detecting regions; second computing means for computationally producing a difference signal of two signals obtained by detecting a quantity of the reflected light coming from one side spot by means of second two divided detecting regions; first binarizing means for binarizing the difference signal of the main spot computationally produced by the first computing means; second binarizing means for binarizing the difference signal of the side spot computationally produced by the second computing means; and judging means for judging the radial moving direction of the main spot based on the binarized data from the first binarizing means and the binarized data from the second binarizing means wherein said judging means comprises a judgment data generating section for generating judgment data for judging the radial moving direction of said main spot, said judgement data generating section including two synchronous type flip-flop circuits and a changeover switch for selectively outputting a positive output of one of the flip-flop circuits and an inverted output of an other flip-flop circuit according to a low or high state of the binarized data from said first binarizing means.