Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1992-08-12
1994-01-11
Messinger, Michael
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
369 4441, G01J 120, G11B 700
Patent
active
052784010
ABSTRACT:
A signal detecting apparatus in an optical disc apparatus having an objective lens which converges light emitted from a light source onto an optical disc and a condenser lens which converges light reflected by the optical disc and transmitted through the objective lens includes first and second light receiving elements, each having a light receiving surface located before or behind a convergence point on which the light reflected from the optical disc is converged when the objective lens is in a focal position. Each of the light receiving surfaces are split into at least four light receiving areas. The signal detecting apparatus also includes a means for calculating a sum of differences of outputs of the light receiving surfaces' inner light receiving areas, calculating a sum of differences of outputs of the light receiving surfaces' outer light receiving areas, and then calculating a difference of the sums of differences, so that a track error signal is output in accordance with the difference of sums of differences calculated by the calculating means.
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Maruyama Koichi
Noguchi Masato
Okuda Isao
Oono Masahiro
Takishima Suguru
Asahi Kogaku Kogyo Kabushiki Kaisha
Messinger Michael
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