TEA2029 STMICROELECTRONICS [STMicroelectronics], TEA2029 Datasheet - Page 26

• Manufacturer Part Number: TEA2029
• Description: APPLICATION NOTE
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

TEA2028 - TEA2029 APPLICATION NOTE
B. STUDY OF SHIFT ADJUSTMENT
With R, P network connected to Pin 16, the t
becomes :
With : T2 = ABR’ (where R’ = R // R
Substituting the following values into above equa-
tion :
- R = 470k
- R’ = 470k // 25M
- A = 17 10
- B = 16 s/V
- t
- T
- V
- t
If K varies between 0 and 1
which corresponds to a picture displacement of :
Shift variations as a function of V
(with adjustment)
Therefore, a constant V
potentiometer.
V.6 - Vertical deflection driver stage
This stage must constantly drive the vertical spot
deflection. Such deflection will horizontallyscan the
screen from top to bottom thus generating the
displayed image. Similar to horizontal deflection,
the vertical deflection is obtained by magnetic field
variations of a coil mounted on the picture tube.
A saw-tooth current at frame frequency will go
through this coil commonly called ”frame yoke”.
Frame period is the time required for the entire
26/46
dt
dV
LINE
therefore t
OUT
d
OUT
t
t
2
CC
CC
out
OUT
= 10 s
= 125
[- 4mm to + 11mm].
= 12V
= - 38ns - 390ns + 1.5 s K
[- 0.43ms to 1.07 s]
=
= K 0.12 s/V
=
B
1
R
R
BR I
1 T
-6
out
T
A/ s
2
= 1.5 K - 0.43 ( in s )
K
2
IN
B
+
t
R
R
D
T
= 46k
2
1
at K
CC
dV
K
59.7 s
dL
CC
must be applied to the
T
NOMINAL
2
AR
= 0.34mm/V
K
CC
+
IN
B
) and K
= 0.28
R
R
1
KV
T
2
CC
[0;1]
out
screen to be scanned vertically.
C.C.I.R. and N.T.S.C. TV standardsrequire respec-
tively 50Hz and 60Hz Frame Scanning Frequen-
cies. Also, a full screen display is obtained by two
successivevertical scannings such that the second
scanning is delayed by a half line period with
respect to the first.
This method increases the number of images per
second (50 half images/s or 50 frames/s in 50Hz
standard). This scanning mode called ”Interlaced
Scanning” eliminates the fliker which would have
been otherwise produced by scanning 25 entire
images per second.
The circuit will generate a saw-tooth voltage which
is linear as a function of time and called ”frame
saw-tooth”. A power amplifier will deliver to the
”frame yoke” a current proportional to this saw-
tooth voltage. It is thus clear that this saw-tooth
voltage reflects the function of the vertical spot
deflection; which must itself be synchronized with
the video signal. Synchronization signals are ob-
tained from an extraction stage which will extract
the useful signal during line pulse inversion of the
composite sync signal.
Synchronization occurs at the end of scanning, in
other words, when the saw-tooth voltage at Pin 5
is reset. This function is accomplished by the
”frame logic circuitry” of full digital implementation.
This processing method offers various advan-
tages :
- Accurate free-running scanning frequency
- Digital synchronization locked onto half line
- Automatic 50/60Hz standard recognition and
- Optimized synchronization in VCR mode.
- Generation of variousaccurate time intervals,
- Generation of vertical blanking signal for spot
eliminates the frequency adjustment required by
previous devices.
frequency thereby yielding perfect interlaced dis-
play and excellent stability with noisy video signal.
switching the corresponding display amplitude.
such as narrow ”sync windows” thus reducing
considerably the vertical image instability in case
of for instance, mains interference,superimposed
on frame sync pulse.
flyback and to protect the picture tube in case
of scanning failure.