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4. Structure of the Photo Diode (DVD-RAM)
e
4
e
3
1) Focus Error Signal –> {(a+c) - (b+d)} - 1.17 x {(e
• In case of DVD Disc
This signal is generated in RF AMP IC (IC101) and controls the pick-up's up and down to
focus on DVD Disc.
2) Tracking Error Signal (DPP Method) –> {(a+b) -(c+d)} - 1.17 x {(e
- (e
+ f
+ e
+ f
3
3
4
• In case of DVD Disc
This signal is generated in RF AMP IC (IC101) and controls the pick-up's left and right shift to find the track
on DVD Disc.
3) RF Signal –> A+B+C+D
• In case of DVD Disc
This signal is converted to DATA signal in DSP IC (IC201).
e
d
1
e
c
2
)}
4
Pick-Up module
Photo Diode
a
f
b
f
(As seen from light receiving side)
+ f
+ e
+ f
2
2
4
Tracking
f
1
4
f
2
3
) - (e
+ f
- e
+ f
)}
4
1
1
3
3
+ f
+ e
+ f
1
1
2
2
Red laser
Focusing
)
17
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