Mitsubishi Electric VS-45605 Technical Training Manual page 62

Matrix and RGB Circuitry
The R-Y and B-Y signals from the YUV Switch pass
through Axis circuitry. The circuit sets the axis of
the R-Y and B-Y signals and generates the G-Y sig-
nal. The three color difference signals, along with Y
signal from the YUV Switch, are input to the Matrix
circuitry.
In the Matrix, Y signal is added to each of the color
difference signals, resulting in Red, Green and Blue
Video signals. The RGB signals are directed to the
RGB circuitry in the VCJ.
The RGB signals from the Matrix circuit pass through
YM Attenuation, YS Switch and Picture Control cir-
cuitry.
YM Attenuation decreases the RGB signal's ampli-
tude by 6db. Activated by a HIGH at the Half Tone
input, pin 12 of the IC, it is used to produce the trans-
parent gray background for certain on-screen dis-
plays. The amplitude of the RGB video signals is re-
duced by 1/2 in the background area of the OSD.
This dims the video in the background.
The YS Switch, inserts On Screen Display (OSD)
information into the Main Signals. OSD signals are
applied to pins 14, 15 and 16. The YS signal at pin
13 times the insertion of the OSD. The signal path
for the OSD sources is provided at the end of this
section.
The Picture Control circuitry amplifies the RGB
signals. The amount of gain is determined by the
user's Contrast adjustment setting. The signals then
pass through the Dynamic Color stage of the cir-
cuitry.
In the following circuity:
• Gamma -- increases the detail in white areas
of the picture.
• Clamping -- sets the pedestal level of the
three signals.
• Brightness -- sets the DC level of the signals
In the Drive circuitry, the amplitude of the Blue
and Green signals are adjustable. These adjustments
are used when performing White Balance adjust-
ments.
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