A method and apparatus for producing an apparent increase in display
brightness in an RPTV engine without an actual increase in total light
output. Light is generated with an illumination source and optically
processed to produce a light beam of rectangular format. The light beam is
formed intentionally to have an intensity that is non-uniform, varying
from a peak intensity at a center of the beam to a minimum intensity at a
periphery of the beam. The optical processing step can include varying the
intensity to selectively produce an illumination profile that decreases by
at least about 30% to 70% from the peak intensity to the minimum
intensity. The optical processing step can further include projecting the
light beam through an integrator that is configured to produce an
illumination profile that is at least partially controlled by a length of
the integrator. The integrator can be configured so that a decrease in
length will result in reduced uniformity.
