Projection display systems for light valves

Abstract

Projection display systems for light valves such as liquid crystal display panels, and in particular to the use of color component rotators, such as retardation filters, to provide for improved projection display architectures.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional application of U.S. patent application Ser. No. 11 / 044,820 filed Jan. 25, 2005, which is a divisional of U.S. patent application Ser. No. 09 / 539,918 filed Mar. 31, 2000, to which it claims priority.BACKGROUND OF THE INVENTION [0002] The present invention relates to projection display systems for light valves such as liquid crystal display panels, and in particular to the use of color component rotators, such as retardation filters, to provide for improved projection display architectures. [0003] Projection systems for reflective liquid crystal displays (LCDs) are generally characterized by their complexity and large size relative to the systems implemented for transmissive LCDs. FIG. 1A discloses a prior art configuration for a transmissive LCD projector, while FIG. 1B shows a prior art reflective LCD projector for comparison. Dichroic filters DF1 and DF2 separate the red, green, and blue color component...

AI Technical Summary

Benefits of technology

"The present invention provides a projection display system that uses color component rotators to control the polarization orientation of the three color components in the system relative to each other. This allows for the use of conventional polarization converters rather than complicated prefiltering systems, reducing the overall size and complexity of the system while maintaining good contrast and brightness. The technical effects of the invention include improved image quality, reduced system size and complexity, and improved cost-effectiveness."

Problems solved by technology

Projection systems for reflective liquid crystal displays (LCDs) are generally characterized by their complexity and large size relative to the systems implemented for transmissive LCDs. FIG. 1A discloses a prior art configuration for a transmissive LCD projector, while FIG. 1B shows a prior art reflective LCD projector for comparison.

These components add complexity to the system and require the use of a larger distribution and recombination optical system to divide the light into the three color channels (i.e. the optical paths traveled by the three color components such as red, green, and blue).

In order to produce that combination of color components and polarizations, a complicated prefiltering system is needed.

This arrangement appears simple, but the control of color in a Philips prism for p-polarization on the input and s-polarization on the output is extremely difficult, and no successful implementation of this type of system exists.

This requires a second optical arrangement to split up the color distributions and leads to a larger, more complicated system overall.

The color splitting and recombination is accomplished by tilted dichroics that perform essentially the same as the dichroics in a Philips prism, with the same polarization related problems.

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