the fiber-optic substrate of the liquid crystal light
valve (LCLV) in the projection function. The fiber-
optic substrate of the LCLV acts as the interface
between the CRT and the LCLV.
Projection Function
The projection function receives the visual image
from the CRT, amplifies it, and projects it to a large
screen. A 500-watt xenon arc lamp provides a high
intensity light source to the LCLV. Figure 4-23
shows a cross section of a LCLV. The LCLV bias is
a variable ac voltage used to align the liquid crystal
molecules. When no light is present on the fiber-optic
plate, the bias voltage drop is primarily across the
photoconductor layer and not the liquid crysta1 layer.
When a point of light hits the fiber-optic plate, the
impedance of the photo conductor at that point will
drop and the ac voltage will be applied to the
corresponding point on the liquid crystal layer. A
voltage drop on the liquid crystal causes the liquid
crystal molecules to rotate and polarizes the light.
The light emitted by the LCLV is polarized (rotated)
in areas that had light applied to the LCLV and
unaltered where there is no liquid crystal molecular
rotation. This light is then processed by a series of
optic lenses and prisms and projected onto the screen.
Power Distribution Function
The power distribution function develops and
distributes the voltages required by the PPU. The
low-voltage power supply develops regulated +5, +15,
and -15 vdc. The medium voltage power supply
develops +31, -31, +100, +110, and -110 vdc. The
medium-voltage power supply also develops the +6.3
vac for the CRT filament.
The arc lamp power supply and lamp igniter
provide the starting and operating voltages for the arc
lamp. When power is applied, the arc lamp power
supply sends +100 vdc to the arc lamp igniter. This
voltage is used to start the arc lamp igniter, which
steps up the 115 vac input voltage to a 24 kv, which
is then sent to the arc lamp. If the arc lamp ignites,
the +100 volts drops to 20 volts to maintain a constant
current through the lamp. If the arc lamp does not
ignite, the 24-kv ignition pulse will be repeated up to
a maximum of 12 times. If ignition fails after 12
attempts, a lockout circuit will inhibit further attempts
and light the lockout indicator on the power supply.
The lockout circuit must be manually reset.
TELEVISION CONVERTER GROUP
The television converter group develops the
composite video signals required to display graphics
and alphanumerics on the OJ-535(V)/UYQ-21(V), the
large screen displays, and the automated status boards
(ASTABs). The television converter group can also
be configured to drive hard-copy printer-plotters.
Depending on the ship’s configuration, the
television converter group will contain one or more of
the following equipments:
l Common digital television graphics generator
(C-DITEG)
,
Digital television graphics generator (DITEG)
Dual television scan converter (dual TVSC)
Tactical DITEG module (TDM)
Central ASTAB generator
In our study of the television converter group, we
look at the C-DITEG in detail and follow it with a
brief description of the functions and capabilities of
the other types of converters.
COMMON DIGITAL TELEVISION
GRAPHICS GENERATOR (C-DITEG)
The common digital television graphics generator
(C-DITEG) is used to generate the text, graphics, and
symbols used in displays and hard-copy printer-
plotters. The C-DITEG is a multichannel device that
can drive up to 14 displays and 2 hard-copy printer-
plotters. Of the 14 displays, 8 are graphic display
units and 6 are text-only units. The 8 graphic displays
are 6 display consoles, (OJ-535(V)/UYQ-21(V)), and
2 large screen displays (PT525/UYQ-21(V)). The
4-21
