Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1987-03-27
1988-06-28
Westin, Edward P.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
250556, 369 44, G11B 2102
Patent
active
047541296
ABSTRACT:
This invention relates to a grating adjustment apparatus of 3-beam type optical pick-up for the compact disk player and, more particularly, to an apparatus automatically and readily adjusting a grating to the angle where the target value of a tracking error signal is obtainable. Sub-beam currents from the optical pick-up is, through current-voltage transducing amplifiers, converted into voltage signals, which are applied to a differential amplifier. The differential amplifier puts out the tracking error signal mixed with noise, which passes through a band pass filter removing said noise. So only pure tracking error signal is obtained, which is, after its phase is compensated by the low frequency lag compensator, applied to a differentiator. This signal is applied to a discriminator. When the tracking error signal detected by the discriminator is far smaller than the lowest limit of the target value of the grating adjustment, a jig actuator regulates the grating angle in the direction that said signal can be increased, by rotating a motor. In the end, the target value of the tracking error signal is obtainable. When the tracking error signal detected by the discriminator is larger than the target value, a system controller generates an amplifier enable signal making the discriminator produce a grating adjustment stop signal and a tuned indicating signal, whereby the motor driving stage generates a signal for braking the motor. In the end, the target value of the tracking error signal is maintainable.
REFERENCES:
patent: 4234837 (1980-11-01), Winslow
patent: 4541084 (1985-09-01), Oku et al.
patent: 4561080 (1985-12-01), Yamazaki
patent: 4615023 (1986-09-01), Inada et al.
patent: 4651314 (1987-03-01), Yoshikawa et al.
Samsung Electronics Co,. Ltd
Westin Edward P.
Wieland Charles
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