The Cathode Ray Tube TV set has ruled the consumer electronics
world for decades. Now a days every one wants big screens for
their entertainment rooms. But bigger a CRT screen, the glass
tube will be deeper and the set becomes impossibly heavy and unwieldy
when the diagonal measurement of the screen goes beyond about
36 inches. Thus the CRT is destined for a slow but sure decline
giving way to many new technologies.
All of us
must have noted the red colour of the hero's suit in the movie
'spiderman', the blues of the sky and water scenes were captivating.
The dark horse technology behind this is GRATING LIGHT VALVE TECHNOLOGY
GLV device concepts were developed at Stanford University. Later
Silicon Light Machines was found in 1994 to develop and commercialize
a range of products based on this technology.
The GLV device
is a type of optical micro electromechanical system or MEMS essentially
a movable, light reflecting surface created directly on a silicon
wafer, utilizing standard semiconductor processes and equipment.
A Grating Light Value (GLV) device consists of parallel rows of
reflective ribbons. Alternate rows of ribbons can be pulled down
approximately one-quarter wavelength to create diffraction effects
on incident light (see figure 1). When all the ribbons are in
the same plane, incident light is reflected from their surfaces.
By blocking light that returns along the same path as the incident
light, this state of the ribbons produces a dark spot in a viewing
system. When the (alternate) movable ribbons are pulled down,
however, diffraction produces light at an angle that is different
from that of the incident light. Unblocked, this light produces
a bright spot in a viewing system.
The Grating Light Valve uses reflection and diffraction to create
and bright image areas.
If an array
of such GLV elements is built, and subdivided into separately
controllable picture elements, or pixels, then a white-light source
can be selectively diffracted to produce an image of monochrome
bright and dark pixels. By making the ribbons small enough, pixels
can be built with multiple ribbons producing greater image brightness.
If the up and down ribbon switching state can be made fast enough,
then modulation of the diffraction can produce many gradations
of gray and\or colors.
several means for displaying color images using GLV devices. These
include color filters with multiples light valves, field sequential
color, and sub-pixel color using "turned" diffraction