Toshiba TW40F80 - Manual (Page 48)

48
4-2. Sub Screen Process Section
The sub screen process section is shown in Fig. 6-3.
The Y, I and Q signals from the video/color/deflection pro-
cess section are limited in their frequency bandwidth by the
LPF in the prceeding stage and input to pins 6, 13 and 15 of
QY03.
The frequency of 18.5 MHz generated by LY102 is multi-
plied by 1/2 inside QY03. The Y signal is sampled by 9.25
MHz and the I and Q signals are sampled by 4.63 MHz (1/2
frequency to multiplex) and then the signals are converted
into 8-bit digital signals.
The horizontal sync signal WHD (the signal mixed with
WHD1 and WHD2 by QY43) for writing input to pins 21
and 20 of QY03 and the vertical sync signal WVD for trig-
ger writing on the field memory QY10 and QY11.
Fig. 6-3 Sub screen process section
6
13
15
79
80
20
21
24
25
77
75
72
73
95
100
97
70
48
32
51
65
Y IN
R-Y IN
B-Y IN
SCL
SDA
FVS
FHS
OSCSI
OSCSO
FVM
FHM
OSCMI
OSCMO
L.P.F
L.P.F
L.P.F
Y
I
Q
I 2 C BUS (SCL, SDA)
WVD
WHD2
1
2
4
OR
circuit
WHD1
WHD
QY43
TC7S32F
LY102
LY101
PY01
RVD
RHD
YS
Signal reception circuit
Video/c
o
lor/
deflect
ion pr
ocess section
QY03 TC9092AF
Sub screen process IC
Y OUT
R-Y OUT(I)
B-Y OUT(Q)
YS OUT
MWD 0
MWD15
MRD 0
MRD15
Y
I
Q
L.P.F
L.P.F
L.P.F
YS
QY10, QY11
MSM518221-30ZS
2M
memory
Date out
To Main/Sub pictore superimposing process section
Date in
Y11
Y12
Y01
The horizontal sync signal RHD for reading-out and the ver-
tical sync signal RVD for reading out input to pins 75 and 77
of QY03 trigger the reading at 18.0 MHz which is created
by 2/3-multiplying 27.0 MHz developed in LY101and then
output as the analog signal.
The Y, I and Q signals converted for the sub screen are out-
put from pins 95, 100 and 97 of QY03. The output signals
are used for the input signals compressed by 1/2 in the hori-
zontal direction in the double window mode and for the in-
put signal compressed by 1/6 in the horizontal direction and
by 1/3 in the vertical direction in 9-screen multi-search mode.
Then the signals are smoothed by the LPF in the next stage
then input to the main/sub screen superimposing section.