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> A C T I V E S T E R E O
SINGLE CRT OR DLP™ PROJECTOR
As the projector sequentially projects the left and right
eye images, the duty cycle is 50%. However, the extra
blanking between the left and the right image that is
required to ensure a good stereo separation further
diminishes the light output, resulting in an
efficiency of about 45%.
Due to polarizing filters that are utilized in active
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PA S S I V E S T E R E O
TWO CRT OR DLP™ PROJECTORS
The unpolarized light coming from each projector is
externally polarized, which diminishes the brightness
by more than half and reduces the efficiency to about
45%. Then the polarized image is viewed through
SINGLE PROJECTOR WITH ZSCREEN
When a ZScreen is used to polarize the light, a single
projector is driven in active stereo mode. As a ZScreen
is even slower than active glasses more blanking is
needed between the left and right signal, resulting in a
duty cycle efficiency of about 40%.
TWO LCD PROJECTORS
LCD panels polarize the light that passes through them
in different directions. Through the use of internal
polarization Barco is able to maintain about 70% of
the original light output.
-55%
-55%
-65%
-60%
-30%
-65%
stereo eyewear, each eye receives less than half of
the remaining light. As the shutter glasses do not
open and close instantaneously, and due to the light
lost from the polarization, efficiency of the active
stereo eyewear is rated at about 35%. The overall
efficiency of the active stereo process therefore
equals about 45% x 35%, or approximately 16%.
-16%
passive stereo glasses that transmit the polarized
light at about 84% efficiency, resulting in a final
efficiency rate of approximately 38%.
-16%
The ZScreen polarizes light with a brightness efficiency
of about 35%. With the passive stereo eyewear
having an efficiency rating of 84%, the final efficiency
rating is about 12%.
-16%
Combined with the 84% efficiency of the passive
glasses an overall projection efficiency of 59% is
reached.
16%
38%
12%
59%
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