>
A C T I V E S T E R E O
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
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%
.
The influence of the screen has not been taken into account in the pictures.
Indicative average values depend on materials used.
yellow = polarized light
-55%
-65%
16%
SINGLE CRT OR DLP™ PROJECTOR
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
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
.
Combined with the
84%
efficiency of the
passive
glasses
an overall projection
efficiency of 59%
is
reached.
passive stereo glasses
that transmit the polarized
light at about
84% efficiency
, resulting in a
final
efficiency rate of approximately 38%
.
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%
.
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%.
>
PA S S I V E S T E R E O
-55%
-16%
38%
-60%
-65%
-16%
12%
-30%
-16%
59%
TWO CRT OR DLP™ PROJECTORS
SINGLE PROJECTOR WITH ZSCREEN
TWO LCD PROJECTORS
Stereobrochure 02-06-2003 15:39 Pagina 9
