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Fire Controlman Volume 05-Display Systems and Devices | Next
TELEVISION CONVERTER GROUP |
the PT-525A/UYQ-21(V). For our training purposes,
we are using the PT-525/UYQ-21(V). The PPU is a
large screen projection display device that projects a
visual image onto a 42" x 42" screen.
The
presentation consists of yellow characters on a blue
background. Display resolution can be 525, 729, or
1075 lines per frame.
Figure 4-21 shows the
PT-525/UYQ-21(V) unit.
The PPU receives composite video from the
DITEG or C-DITEG. The PPU is also capable of
displaying raster video from an external source if
separate horizontal and vertical sync signals are
provided. The PPU can also display random stroke
video supplied by an OJ-451(V)2,3/UYQ-21 that is
equipped with the display signal amplifier option.
Figure 4-22 illustrates the interface options available.
The PPU consists of the following five functional
areas:
Video processing function
Sweep and deflection function
CRT function
Projection function
Power distribution function
Video Processing Function
The video processing function receives the
incoming video and develops the video and blanking
signals required to control the electron beam of the
CRT. The video input can be composite video,
noncomposite video with separate horizontal and
vertical sync, or random stroke video. The video
signal is amplified and used to drive the CRT cathode.
The sync signals are processed to form the horizontal
and vertical retrace blanking signals.
Sweep and Deflection Function
The sweep and deflection function develops the
signals required to move the CRT electron beam.
Raster deflection voltages are generated from the
Figure 4-23.–A cross section view of the
liquid crystal light valve.
horizontal and vertical sync signals received from the
video processor function. Random stroke deflection
voltages are received from the TDS display console in
the form of X and Y major (position) deflection
voltages and X and Y minor (symbol) signals. The
deflection voltages are used to drive the yoke of the
CRT.
CRT Function
The CRT function uses the video and deflection
voltages to create a visual image. The CRT in the
PPU is a 2.25-inch diameter, high resolution electron
tube. The video output of the CRT is a fiber-optic
faceplate. The faceplate is in physical contact with
4-20
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