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AssigneeU.S. Philips Corporation
InventorsIngrid E. J. R. Heynderickx, Dirk J. Broer
Estimating the term…
The invention relates to an illumination system (7) for a colour image projection device (1). The illumination system (7) comprises a radiation source (3) for generating an unpolarized radiation beam (5) and at least a cholesteric mirror (9, 10, 11, 12, 13, 14) for wavelength-selective splitting of the radiation beam (5) into at least two sub-beams of different wavelengths. A composite circular polarizer (35) for directly converting the unpolarized radiation beam (5) into circularly polarized sub-beams jointly forming one beam is arranged in the path of the unpolarized radiation beam (5) between the radiation source (3) and the cholesteric mirror (9). The composite circular polarizer (35) comprises a polarization-sensitive beam splitter (43) which splits the unpolarized radiation beam (5) into two mutually perpendicularly and linearly polarized sub-beams, and a polarization converter (51, 53; 59, 61). The circularly polarized monochrome sub-beams are subsequently modulated, either or not after passage through .lambda./4 plate (63, 65, 67), by a corresponding number of image display panels (27, 29, 31) and projected as an image via a projection lens system (33).
An illumination system for a colour image projection device, successively comprising a radiation source for supplying a radiation beam of unpolarized radiation and at least a cholesteric mirror for splitting the radiation beam into at least two sub-beams, each sub-beam having a different wavelength, characterized in that a composite circular polarizer for directly converting the unpolarized radiation into circularly polarized sub-beams is arranged in the path of the radiation beam between the radiation source and the cholesteric mirror, said polarizer comprising a polarization-sensitive beam splitter for splitting the radiation beam into two mutually perpendicularly and linearly polarized sub-beams, and a polarization converter for converting the linearly polarized sub-beams into circularly polarized sub-beams, the circularly polarized sub-beams from the polarizer jointly forming one beam.
A circular polarizer for converting unpolarized radiation of a radiation beam into circularly polarized radiation in sub-beams, the polarizer comprising a polarization-sensitive beam splitter for splitting the radiation beam into two mutually perpendicularly and linearly polarized sub-beams, and a polarization converter for converting the linearly polarized sub-beams into circularly polarized sub-beams.
Dependencies are inferred from the claim text.