Sony DTV-01, Руководство пользователя

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125
Flat screen corner
Electron
beam
spot 2
spot 1
Beam
DQP
Neck
Field
Dynamic Quadrapole Focus
There are three types of electron beam focus circuits used in this flat
screen TV:
Static focus – A DC voltage is applied to the picture tube’s focus grid.
This produces a line of focus points forming an arc pivoting at the yoke
where the beam is swept. The focus point can be moved toward or away
from the yoke by changing the DC focus voltage.
Dynamic focus – The electron beam must focus on the screen. Be-
cause the picture tube screen is flat and does not match the focus arc, the
dynamic focus circuitry moves the focus point up on the left and right
sides to meet the flat screen.
Dynamic Quadrapole focus – Static focus places a round focused spot
at any point along the focus arc, perpendicular to the electron beam (spot
1). This focus point was moved to the flat screen with dynamic focusing.
Although the beam is focused on the screen, it is no longer round (spot 2)
because of the angle the beam strikes the screen. One side of the elec-
tron beam that strikes the screen (spot 2) travels further, forming an oval
instead of a circle. This oval shape is pronounced at the four corners of
the screen if this correction circuit becomes inoperative. This quadrapole
focus circuit reshapes the spot by using the magnetic field from four coils
mounted at the picture tube neck.
The four QP coils work in magnetic pairs; either pushing or pulling the
beam so it is oblong in transition but round at the target screen. The
diagram shows the effects of two facing QP coils:
Dynamic Quadrapole Circuitry
To reshape the spot in the four corners of the picture tube, horizontal and
vertical scanning signals are necessary to locate those corners. They are
input to the DQP Control IC1604 at pins 19 and 21. Serial data and clock
are input to control the amount of correction signal that outputs as Pa-
rabola signals 1 and 2 (IC1604/pins 4 and 6).
IC 1 6 0 4 Q u a d ra p o le fo c u s C o rre c tio n
In p u t N a m e In p u t to O u tp u ts
H o riz A F C fr o m H o riz O u t
Q 1 8 0 4 /C o lle c to r D Q P IC 1 6 0 4 /p in 1 9
H o riz o n ta l p u ls e s
V e rtic a l B la n k in g p u ls e s
fro m IC 1 3 0 5 /7 D Q P IC 1 6 0 4 /p in 2 1
V e rtic a l p u ls e s
Q u a d ra p o le
c o r re c tio n :
P a ra b o la 1 fro m
IC 1 6 0 4 /p in 4
S e ria l D a ta b u s fro m M a in
M ic r o IC 3 2 5 1 /p in 3 1 D Q P IC 1 6 0 4 /p in 1
S e ria l C lo c k b u s fr o m
M a in M ic r o IC 3 2 5 1 /p in 2 8 D Q P IC 1 6 0 4 /p in 2
Q u a d ra p o le
c o r re c tio n :
P a ra b o la 2 fro m
IC 1 6 0 4 /p in 6
DQP Drive
Parabola 1 output from IC1604/pin 4 is current amplified by IC1601 before
being applied to the QP coils. Parabola 2 is inverted by IC1605 before
also being current amplified by IC1602. The inverted signal is applied to
the other end of the QP coils.