CX-890
2.3 Automatic Adjustment Function
Constant RF level
With this system, all circuit adjustments are automati-System
microcomputer
cally performed by using the preamplifier (UPC2572GS)
Corrected Transfer
RF signalvoltage D/Aof amount
and servo LSI (UPD63702AGF). All adjustments areAGC outputof correction
circuit
automatically performed whenever disc is inserted or
TE.O, T.BAL
CD mode is selected by the Source key. Details of auto-FZD FE.B Gain
FE signal
matic adjustments are as follows:
Detection A/DReading Calculation of amount
amount of
of deviationof correction
deviation
TE signal
Items of
automatic
ADJ
IC101IC201
UPC2572GSFZDUPD63702AGF
TE.O
T.BAL
FE.B
F and T.G
Fig. 18 Outline of Automatic Adjustment
1) Setting of FZD cancellation(4)The voltage output from the servo LSI is input to Pin
This setting ensures focus closing. The system reads37 of the preamplifier (IC101: UPC2572GS). Pin 37 is
the FE offset level when the power is turned to ON,a control-voltage terminal of the TEVCA amplifier.
then writes the inverse voltage of offset value of thatAccording to voltage input, the system changes gain
level to CRAM inside IC to cancel offset. Thus, theof Ech and Fch in the preamplifier, and adjusts the
threshold level of FZD can be set to a constant valuetracking balance to make the upper and lower por-
(+150 mV). As a result, "Latching FZD signal to H",tions of TE waveforms symmetric to REFOUT.
which is one of the conditions required for focus clos-
ing in IC, is ensured.4) FE bias automatic adjustment
2) TE offset automatic adjustmentMaximizes the RFI level by optimizing focus point dur-
Adjusts TE amplifier offset of the preamplifier to 0 Ving playback. Adjustment is made by using 3T level
when the power is turned to ON.waveforms of RF waveforms and the phase difference
Adjustment is made as follows:generated by input of disturbance of focus error. Since
(1)The microcomputer reads TE offset in LD OFF statusadjustment is made by inputting disturbance to focus
via the servo LSI (TE1).loop, the system uses the same timing as with auto
(2)The microcomputer calculates the voltage to be cor-gain control (mentioned later~) for adjustment.
rected using the TE1 value, and outputs from Pin 65Adjustment is made in the following steps:
(pin name: TOFST) of the servo LSI. More specifical-(1)Disturbance is input to focus loop by the command
ly, calculation is made as follows:from the microcomputer (inside the servo LSI).
TOFST2 = TOFST1 + TE1 x R110 / R109(2)The system detects flickering of 3T components of
3) Tracking balance (T.BAL) automatic adjustmentRF signal in the preamplifier.
(3)The system checks the phase difference between 3T
To make the sensitivity of Ech of TE output equal to that
of Fch. In fact, adjustment is made so that the uppercomponents mentioned above and FE signal caused
by input of disturbance to detect the direction of
and lower portions of TE waveforms are symmetric to
focus deviation. The result is output as DC voltage
REFOUT.
from Pin 30 (3TOUT) of the preamplifier.
Adjustment is made in the following steps:
(1)After focus close, the system kicks the lens in the(4)The 3TOUT voltage is input to Pin 75 (A/D port) of the
servo LSI. The microcomputer reads this 3TOUT volt-
radial direction to ensure TE waveforms to be gener-
age via the servo LSI.
ated.
(5)The microcomputer calculates the amount of correc-
(2)The microcomputer reads the peak bottom of TE
waveforms via the servo LSI.tion required. The results are transferred to offset of
focus loop in the servo LSI.
(3)The microcomputer calculates the amount of offset,
As with auto gain control, the system repeats the
then calculates the voltage to be corrected based on
same adjustment process several times to improve
that offset. The system outputs the result from Pin 66
(pin name: TBAL) of the servo LSI.adjustment precision.
13 |
ACEC
