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2 . O P T I C A L S Y S T E M
2-1. Configuration
No.
N a m e
1
UHP lamp
L a m p
u n i t
Parabolic
2
reflector
Multi-lenses
3
A, B
Multi-PBS
4
(Polarizing
beam splitter)
Retardation
5
f i l m
Condenser
6
lens
Full reflection
7
mirror
Mirror
box
u n i t
Dichroic
8
mirror
9
Field lens
10
Relay lens
Incident side
polarized
11
plate/Phase
difference
plate
Liquid crystal
12
panel
Prism
u n i t
Dichroic
13
prism
Projec-
Projection
t i o n
14
lens
lens
Light source of the optical system. AC lighting system 120W, arc length 1.3 mm.
As the arc length is shorter than the conventional metal halide lamp, the light source
operates as an ideal light point source and this improves the light convergence factor.
Also, the color temperature gets higher and this allows to reproduce more natural
white color.
Parabolic reflector converges light emitted from the UHP lamp forward in approximate
parallel light beams and illuminates the liquid crystal panel.
Two multi-lenses A and B allow a circular beam light emitted from the light source to
illuminate the square liquid crystal panel evenly, thus providing projected pictures
with less brightness variation. Multi-lens A is coated with UV-IR which passes the
necessary visible rays of the radiation light from UHP lamp and cuts unnecessary
ultraviolet rays and infrared rays.
Separates the illuminating light from the light source via multi-lens B into P polariza-
tion light and S polarization light.
Converts P polarization light into S polarization light among P and S polarization
lights separated by multi-PBS.
Converges the illuminating light emitted from the light source into the liquid crystal
panel.
Reflection mirror to refract light axis.
Separates the white light emitted from the light source into RGB three primary colors.
The white light emitted from the light source reflects B light using a dichroic mirror 1
and the RG lights pass through the dichroic mirror 1. Of the RG lights passed, G light
is reflected by the dichroic mirror 2 and R light passes.
Light transmitted through liquid crystal panel is converged in direction of focal point
and effectively entered entrance pupil of the projection lens. Also, R and G field lens
possess dichroic filter characteristics to improve color purity.
In the B axis optical path which is longer than those of R, G, the relay lens works as
a correction lens to arrange the illumination distribution of the liquid crystal panel
surface with that of other liquid crystal panel.
The illumination lights separated into RGB change the S polarization light component
in processing the PBS and phase difference plate operation previously described.
The incident side polarized plate arranges the illumination light more effective direct
polarization light. The phase difference plate used works to converge the S polariza-
tion light into the polarization light which fits to the transparent axis of the liquid
crystal panel.
These polarizing plates and difference plates are constructed in one plate by
attaching each other, and put on a glass plate.
Light exit side polarized plate is put on the light exit plane. When no signal voltage is
applied, the polarization direction of transmission light rotates by 90 degrees. When a
voltage is applied, the polarization direction is controlled owing to the voltage
applied. That is, the liquid crystal panel employs such general TN type liquid crystal.
In this model, the incidence/exit polarization plate is placed (in normally white mode)
so that the light transmission amount becomes maximum (white) when no voltage is
added and the light transmission amount becomes minimum (black) when maximum
voltage is added. The phase difference plate is pasted on the polarized plate. The
light passed through G panel is developed as P polarization light and each light
passing through R and B panel is developed as S polarization light.
Furthermore, microlens array is attached on the incident light side of LCD panel.
Conventionally, the incident light blocked by TFT portions is focused by the microlens
array to improve light usability and to increase the effective aperture of the LCD panel.
Works to mix RGB lights passed through the liquid crystal panel and forms color
picture image.
Demodulated by the video signal on the liquid crystal panel and projects pictures
with video light mixed by dichroic prism at a screen enlargely. Light axis of the
projection lens is set at upper side of center of the liquid crystal panel and this
realizes easy viewing of the panel because the projected screen position is upper
than the unit position. (The lower side of the projected screen positions at the center
axis of projection lens.)
The projection lens employs the zoom & focus system and allows to project enlarging
a picture upto maximum approx. 300 inch.
2-1
Description
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