Appeal No. 1996-0774 Page 2
Application No. 08/048,117
BACKGROUND
The invention at issue in this appeal is an automatic
gain control (AGC) circuit for an optical disc drive.
Conventional AGC circuits normalize tracking and focusing
signals by employing analog dividers to divide the signals by
another signal corresponding to a total amount of light
reflected from a disc. Variations in temperature and supplied
power, however, subject the analog dividers to problems. The
invention employs a digital-to-analog (D/A) converter to
normalize tracking and focusing signals. Accordingly, the
invention is less affected by variations in temperature and
power.
Claim 1, which is representative for our purposes,
follows:
1. An AGC circuit for an optical disc drive
including means for generating a tracking and
focusing error signal by utilizing an output signal
supplied from an optical pickup detector, and an
actuator for correcting an error, which is driven by
a servo drive signal generated by a normalized error
signal, the AGC circuit comprising:
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