| 摘要 |
PROBLEM TO BE SOLVED: To largely reduce an offset by reducing the number of those signal lines to at least the predetermined number of lines or less, which connect predetermined signal lines transmitting photo-electrically converted signals obtained from light-receiving surfaces divided into predetermined pieces and transmit the photo-electrically converted signals from the photo-detectors to a signal processing circuit. SOLUTION: On both sides of a quadripertite light-receiving area 200 consisting of split light-receiving surfaces a-d, a quadripertite light-receiving area 201 consisting of e-h adjacently and a quadripertite light-receiving area 202 of i-1 are arranged. Detected currents photo-electrically converted by the light-receiving surfaces are converted by current-to-voltage converters 40-43, and a, b, d, e+i, g+k, and h+1 are outputted to eight output terminals of the photo-detector 9. Light spot signals of (a+b) and (c+d) which have subtracted tracking error signals from light spots of (a+b)-(c+d)}-K 2(amplification factor of amplifiers 61, 62). (e+f+i+j)-(h+g+l+k)} are obtained from the eight detected signals through adders 48-55 and substacters 70-72.
|
