CX-938
1.3 AUTOMATIC ADJUSTMENT FUNC-
TIONS
Every circuit adjustment on the CD-LSI of this system is
automated.
Every circuit adjustment is automatically implemented
when the disc is inserted or the CD mode is selected
from the source key. The following describes how the
adjustments are executed.
1) FZD Cancel Setting(4) The microcomputer determines if the read offset
This setting is used for executing the focus closevalue is positive, negative or zero.
operation without fail.If the offset value = 0, the adjustment is terminated.
When power is turned on, the FE offset level is read andIf the offset value = A positive or negative value,
a voltage opposite to this offset value is written to thegain of the E and F channels amplifiers are modified
CRAM on the IC to cancel the offset. In this manner, theaccording the predetermined rule.
FZD threshold level can be set to a constant valueThen above steps (2) through (4) are repeated until the
(+240mV), thereby ensuring to meet one of theOOffset value = 0� or OSpecified limit count� is reached.
requirements for the IC to execute the focus close that
Othe FZD signal is latched at high�.4) Automatic Adjustment of FE Bias
This adjustment is intended at maximizing the RFI level
2) Automatic Adjustment of TE, FE and RF Offsetby optimizing the focus point in-play. This adjustment
Using REFO as the reference, this function adjusts theutilizes the phase difference between the RF waveform
pre-amp TE, FE and RF offsets to the respective target3T level and the focus error signal when disturbance is
value when power is turned on (targets values of theapplied.
TE, FE and RF are 0, 0 and -1V, respectively).Since disturbance is applied to the focus loop, this
The following is the adjustment procedure :adjustment is designed to take place in the same timing
(1) Respective offset (LD off) is read by theas the auto gain control (to be described later).
microcomputer via the servo LSI.The following is the adjustment procedure :
(2) The microcomputer calculates the voltages to be(1) Disturbance is injected to the focus loop by the
corrected from the read values, then sets them tocommand from the microcomputer (within the servo
the specified field.LSI).
(2) The LSI detects fluctuation of the RF signal 3T
3) Automatic Adjustment of Tracking Balance (T.component level.
BAL)(3) The LSI determines relationship between fluctuation
This adjustment is used for eliminating differencesof the 3T component and the injected disturbance to
between the pickup E and F channels outputs bydetect magnitude and direction of the off-focus
adjusting gain of the amplifier on the LSI. In the actualintroduced.
(4) The microcomputer reads the detected results from
operation, the TE waveform is adjusted so that it may
be vertically symmetric with REFO.the LSI.
The following is the adjustment procedure :(5) The microcomputer calculates necessary correction,
(1) Make sure the focus close is complete.then hands the calculated value to the bias
adjustment term set on the LSI.
(2) Kick the lens in the radial direction to generate the
TE waveform.This adjustment is repeated several times, as it is so
(3) At this time, the microcomputer reads the TE signalwith the auto gain control, to ensure higher accuracy.
offset value (via the servo LSI) being calculated by
the LSI.
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ACEC
