21
3-2. AS (ALL SUM)
ASG
47
46
44
43
A
D
C
B
IC101
IC201
1.65V
1.65V
V
2
(V)
threshold (V)
V
1
(V)
A/D
AS
Detect
Amplitude
FOCUS ON
: about 2.5V
FOCUS OFF
: about 1.65V
110
16
AS
FE
Threshold(V) = V
1
(V) +
V
2
(V) - V
1
(V)
8
AS circuit
AS(All sum) signal is obtained from low pass filter and FOK is made from AS signal in IC201.
This FOK signal is used to check servo status.
Threshold is that compare with AS signal to obtain FOK signal.
Threshold can be made to focus sweep(Training) in initial read.
