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