Improved Liquid Crystal Display panel illumination

Improved Liquid Crystal Display panel illumination

                               Fig.  1

      Described here is a method of efficiently lighting Liquid
Crystal Display (LCD) panels.

      In one embodiment there are three light sources to provide red,
green, and blue illumination (R, G, and B).  The display provides
sets of triads of electro-optical modulators or "valves" which pass
red, green, and blue light, respectively.  Increased efficiency is to
be obtained by arranging that no light from the R source falls on a G
valve, and so on; this would avoid a factor of three or more
inefficiency in having light of one color incident on regions that
would not transmit it.  It would also permit reduction in cost and
improvement in efficiency by allowing elimination of the color
filters.
                               Fig.  2

      Each of the light sources is focused by an objective on the
appropriate "valve", as shown schematically in Fig. 1.  A field lens,
Fig. 2, causes the central ray in each bundle to be perpendicular to
the panel, for viewing in a direction that is basically perpendicular
to the panel.  (This lens could also vary with position on the panel
to concentrate light at a particular viewing position.)  The two
lenses can be combined into a single thick microlens, as shown in
Fig. 3.  An array of such lenses could be constructed by standard
methods.
                ...