Pioneer PD-6050 서비스 매뉴얼 - 페이지 18
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1-1 .Description of FS4
This switch is situated between Focus
Error
input 6 and the Focus Phase Compensator to
receive the Focus Servo ON/OFF data.
$00
->
$08
Focus OFF
<-
Focus ON
To summarize the above, the focus will be optimally
applied in accordance with the time chart below.
(In actuality, this IC's auto sequence is being used so
the system JU-COM only sends $47 from point®. See
auto sequence on page 20.)
1-2Procedure for Applying Focus
The
following
explanation
will
presume
the
below polarities:
(a) The lens is searching the disc in the far-to-
close direction.
(b) At this time, the output voltage © changes
from negative to positive.
(c) Furthermore, the S-curve of the focus at this
time changes according to Fig. 4-8 below.
The Focus Servo is applied with Point (A) of Fig.
4-8 as its operating point. The Focus Search oper-
ation is performed and the Focus Servo SW is set
to ON while Point (A) of Fig. 4-8 is being crossed.
In order to also prevent malfunction, the logical
product of the operation and the Focus OK signal
is obtained.
This IC is designed so that FZC (Focus Zero Cross)
will be output - as the signal which indicates the
crossing of Point ® - from the ® SENS pin.
In
addition, the Focus OK signal is output as an indi-
cation that focus is being applied (or can be applied
in this case).
Fig. 4-8
S-Curve of the Focus
Drive voltage
Focus error
SENS pin
(FZC)
only BUSY of $47.
h
The broken lines within this figure
indicate the status in which focus
has not been applied.
Focus OK
(CXA1081)
Fig. 4-9.
Timing Chart of the Focus ON Operation
1 B