5
1.2.5 Disc Determination
Determination is achieved by checking the sine wave by sweeping
the lens with the OE IC gain at L and the FSC error amplifier (SGC)
at the default setting. If no sine wave is detected, checking is retried
after switching the OE IC gain to H and increasing the gain of the
FSC error amplifier (SGC). If no sine wave is detected again, it is
regarded as the NO DISC condition.
If one half of the sine wave detected at the first lens sweep is of a
value less than 0.5 V, the OE IC gain is set to H and the peak-to-
peak value of the sine wave is roughly adjusted to 1.8 Vp-p.
By sweeping the lens around the height where the sine wave has
been detected, disc determination is performed, and the sine wave
is finely adjusted to 1.8 Vp-p.
Offset compensation
Lens sweep
Lens sweep
NO DISC
OEIC gain = H
FCS AMP gain up
Checking
the sine wave
Checking
the sine wave
Roughly adjust to
1.8Vp-p sine wave
Finely adjust to 1.8Vp-p
sine wave
Disc determination
END
Level check
Less than 0.5V
More than 0.5V
Yes
Yes
None
None
OEIC gain = H
