Arc Lamp Light Path - Hughes JVC Model 200 Service Manual

Chapter 2---System Description

2.2.2 Arc Lamp Light Path

2-4
Combining (4P) Prism: The combining prism consists of
separate prisms that polarize each of the three high intensity
signals and direct them toward the projection lens.
Projection Lens: The Projection Lens picks up the high intensity
image from the Combining Prism and transmits it to the projector
screen.
The Arc Lamp assembly produces the high intensity light used to
transmit bright images to the screen. It consists of a Xenon Arc
Lamp containing xenon gas under pressure, an ignitor assembly
that provides the spark to light the arc lamp, and a laser power
supply to provide the boost voltage to the Ignitor. An exhaust fan
helps keep the arc lamp cool. The description below follows the
sequence of the light path. (See Figure 2-1).
Ignitor and Laser Power Supply: The Laser Power Supply
provides a boost voltage through a spark gap to the Ignitor circuit
which then provides a momentary High Voltage, (32,000 volts), to
excite the xenon gases inside the Xenon Arc Lamp. After the arc
lamp ignites, it is maintained ON by high current and low-voltage
(approximately 37.5 amps and +20 volts). The arc lamp Ignitor
and Laser Power Supply are mounted next to the arc lamp, inside
the Arc Lamp assembly housing.
WARNING!!!
intensity white, ultraviolet and infrared light capable of severe eye
injury. Never look directly at or touch the Xenon Arc Lamp.
Service should be performed by Hughes-JVC certified
technicians only.
Xenon Arc Lamp/Condensing Lens: High pressure, ionized
xenon gas supports a high-current electrical arc to produce the
intense, white light used in the Model 200 projector. The high
intensity light output from the Xenon Arc Lamp is reflected by an
elliptical metal reflector to a Condensing Lens where the light
beam is condensed and directed to the Cold Mirror.
Cold Mirror/IR Filter and Ultraviolet Filter: The arc lamp light
beam passes through the Condensing Lens to the Cold Mirror and
Infrared Filter which removes most of the IR light, then through the
Ultraviolet filter which removes most of the UV light. The light
beam then proceeds toward the Dichroic Mirror Assembly. In this
manner most of the IR and UV light is filtered out before the light
beam enters the more sensitive portions of the optics, leaving only
the visible portion.
Dichroic Mirror Assembly: The condensed and filtered white
light beam enters the Dichroic Mirror Assembly which separates
(dichroic mirrors reflect only one color and pass all others) the
The Xenon Arc Lamp produces high
Model 200 Service Manual