Signal Detection Of The P/U - LG RH178H Service Manual

3. SIGNAL DETECTION OF THE P/U

1) Focus Error Signal ==> (A+C)-(B+D)
This signal is generated in RF IC (LIC121 : AN22113A) and controls the pick-up's up and down to focus on
Disc.
2) Tracking Error Signal (DPP Method) ==> {(A+D)-(B+C)}- k x {(EF
This signal is generated in RF IC (LIC121 : AN22113A) 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 (LIC201 : MN103SA6G).
Track Center
Tp/2
Main
Sub2
Offset
TE
Pick-Up module
Photo Diode
Sub1
Tp
k[(F+H) - (E+G)]
(A+D) - (B+C) - k[(F+H) - (E+G)]
4-33
Focusing
Tracking
+EF )-(EF
1 4
F,E
D,C
A,B
H,G
(A+D) - (B+C)
Infrared Iaser
+EF )}
2 3