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3 Automatic Adjustment Function
With this system, all circuit adjustments are automati-
cally performed by using the preamplifier (UPC2572GS)
and servo LSI (UPD63702AGF). All adjustments are
automatically performed whenever disc is inserted or
CD mode is selected by the Source key. Details of auto-
matic adjustments are as follows:
1) Setting of FZD cancellation
This setting ensures focus closing. The system reads
the FE offset level when the power is turned to ON,
then writes the inverse voltage of offset value of that
level to CRAM inside IC to cancel offset. Thus, the
threshold level of FZD can be set to a constant value
(+150 mV). As a result, "Latching FZD signal to H",
which is one of the conditions required for focus clos-
ing in IC, is ensured.
2) TE offset automatic adjustment
Adjusts TE amplifier offset of the preamplifier to 0 V
when the power is turned to ON.
Adjustment is made as follows:
(1)The microcomputer reads TE offset in LD OFF status
via the servo LSI (TE1).
(2)The microcomputer calculates the voltage to be cor-
rected using the TE1 value, and outputs from Pin 65
(pin name: TOFST) of the servo LSI. More specifical-
ly, calculation is made as follows:
TOFST2 = TOFST1 + TE1 x R110 / R109
3) Tracking balance (T.BAL) automatic adjustment
To make the sensitivity of Ech of TE output equal to that
of Fch. In fact, adjustment is made so that the upper
and lower portions of TE waveforms are symmetric to
REFOUT.
Adjustment is made in the following steps:
(1)After focus close, the system kicks the lens in the
radial direction to ensure TE waveforms to be gener-
ated.
(2)The microcomputer reads the peak bottom of TE
waveforms via the servo LSI.
(3)The microcomputer calculates the amount of offset,
then calculates the voltage to be corrected based on
that offset. The system outputs the result from Pin 66
(pin name: TBAL) of the servo LSI.
Constant RF level
Corrected
RF signal
voltage
AGC
output
circuit
TE.O, T.BAL
FE signal
Detection
of deviation
TE signal
Items of
automatic
ADJ
IC101
UPC2572GS
FZD
UPD63702AGF
TE.O
T.BAL
FE.B
F and T.G
Fig. 18 Outline of Automatic Adjustment
(4)The voltage output from the servo LSI is input to Pin
37 of the preamplifier (IC101: UPC2572GS). Pin 37 is
a control-voltage terminal of the TEVCA amplifier.
According to voltage input, the system changes gain
of Ech and Fch in the preamplifier, and adjusts the
tracking balance to make the upper and lower por-
tions of TE waveforms symmetric to REFOUT.
4) FE bias automatic adjustment
Maximizes the RFI level by optimizing focus point dur-
ing playback. Adjustment is made by using 3T level
waveforms of RF waveforms and the phase difference
generated by input of disturbance of focus error. Since
adjustment is made by inputting disturbance to focus
loop, the system uses the same timing as with auto
gain control (mentioned later~) for adjustment.
Adjustment is made in the following steps:
(1)Disturbance is input to focus loop by the command
from the microcomputer (inside the servo LSI).
(2)The system detects flickering of 3T components of
RF signal in the preamplifier.
(3)The system checks the phase difference between 3T
components mentioned above and FE signal caused
by input of disturbance to detect the direction of
focus deviation. The result is output as DC voltage
from Pin 30 (3TOUT) of the preamplifier.
(4)The 3TOUT voltage is input to Pin 75 (A/D port) of the
servo LSI. The microcomputer reads this 3TOUT volt-
age via the servo LSI.
(5)The microcomputer calculates the amount of correc-
tion required. The results are transferred to offset of
focus loop in the servo LSI.
As with auto gain control, the system repeats the
same adjustment process several times to improve
adjustment precision.
YPM-MG2196ZF
System
microcomputer
Transfer
D/A
of amount
of correction
FZD FE.B
Gain
Calculation
Reading
of amount
A/D
amount of
of correction
deviation
IC701
IC201
PD5467B
63
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