Patent ID: 6364488
Filing Date: 2002-04-02
Classification: H04N

Abstract:
A projection display device comprising:a light source for producing tri-chromatic polarized light having red, green, and blue polarized beams, each beam having a same polarization; first, second, and third modulation units, each modulation unit using reflection to modulate one of the polarized beams and to change the polarization of the polarized beam; an optical module comprising: first, second, and third polarization beam splitter mirrors, the first and the third polarization beam splitter mirrors aligned in a plane that is perpendicular to the second polarization beam splitter mirror; and a first retarder film located between the second and the third polarization beam splitter mirrors; and an input lens series located between the light source and the optical module, the input lens series comprising a dichroic mirror for splitting the tri-chromatic polarized light into a first monochromatic polarized beam and a bi-chromatic polarized beam comprising a second monochromatic polarized beam and a third monochromatic polarized beam, and a second retarder film for changing the polarization of the second monochromatic polarized beam in the bi-chromatic polarized beam, the first monochromatic polarized beam and the bi-chromatic polarized beam exiting from the input lens series along two perpendicular directions; wherein the first monochromatic polarized beam is directed to the first polarization beam splitter mirror, the bi-chromatic polarized beam is directed to the third polarization splitter mirror, the first polarization beam splitter mirror directing the first monochromatic polarized beam to the first modulation unit and a first modulated beam reflecting from the first modulation unit to the second polarization beam splitter mirror, the third polarization beam splitter mirror splitting the bi-chromatic polarized beam into the second monochromatic polarized beam and the third monochromatic polarized beam according to the polarizations of the second and the third monochromatic polarized beams and directing the second and the third monochromatic polarized beams to the second and the third modulation units, respectively, a second and a third modulated beams respectively reflecting from the second and the third modulation units to the second polarization beam splitter mirror via the first retarder film, the first retarder film changing the polarization of the second or third modulated beam, the second polarization beam splitter mirror combining the first, the second, and the third modulated beams to form an output beam.