Signal Detection Of The P/U - LG GCE-8240B Service Manual

2. Signal detection of the P/U

1) Focus Error Signal ==> (A+C)-(B+D)
This signal is generated in RF IC (IC401 : CXA2638R) and controls the pick-up's up and down to focus on
Disc.
2) Tracking Error Signal (DPP Method) ==> {(A+D)-(B+C)}-
This signal is generated in RF IC (IC401 : CXA2638R) and controls the pick-up's left and right shift to find
to track on Disc.
3) RF Signal ==> (A+B+C+D)
This signal is converted to DATA signal in DSP IC (IC201 : OTI-9797).
Main
Sub2
Offset
TE
Pick-Up module
Track Center
Tp/2
Tp
Photo Diode
k x {(F+H)-(E+G)}
Sub1
H,G
k[(F+H) - (E+G)]
(A+D) - (B+C)
(A+D) - (B+C) - k[(F+H) - (E+G)]
Infrared Iaser
Focusing
Tracking
F,E
D,C
A,B
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