Apparatus for detecting position of light spot

摘要

There is disclosed an apparatus for detecting position of a light spot, suitable for the tracking control or the track-jumping control at the time of reproducing an optical disk. This light spot position detector has a circuit configuration featured below. Namely, three light beams are used to provide three push-pull outputs from the respective light beams to apply a predetermined operation to those push-pull outputs, thereby to generate a light spot position signal permitting discrimination as to whether or not the light spot is in the on-track state. Further, by gain controlling the light spot position signal thus generated, a suitable signal is permitted to be outputted even when a signal is undesirably attenuated for any reason.