Polaview 220 DLP Projector
For reference, how do the three techniques of projection display
actually work?
In current projectors based on liquid-crystal displays (LCDs),
dichroic beam splitters supply red, green, and blue light to trios
of LCD light valves, which pass or block the light as specified by
the pixel data (left). In the display based on a single digital
micro-mirror device (DMD), a synchronized rotating color wheel
in effect tints the light sent to the DMD chip (center). Three con-
secutive 5.6-ms color fields make one 16.7-ms field, for 180 color
fields per second. The cathode-ray-tube (CRT) projector contains
three CRTs (red, green, and blue), each with its own cooled pro-
jection lens (right). The images converge at a large mirror that
reflects them onto a screen. Most CRT displays are rear-projec-
tion systems. Current LCD displays are mainly front-projection
systems, although rear-projection systems are emerging. The
DMD display is suitable for either front or rear projection, with
minor modifications to the optics.
