| 摘要 |
A reflective liquid crystal display (1) is provided with a front illumination unit. The front illumination unit comprises a flat waveguide (2), at least one surface of which is provided with a diffraction grating (7). A period of the diffraction grating (7) is of the order of the wavelength of the light. A light source (4) generates light of one or more colors, and the colors of light are sequentially coupled into the flat waveguide (2). The diffraction grating (7) is divided into separate areas (10, 11, 12). Each of these separate areas (10, 11, 12) is tuned to one particular wavelength of the light generated by the light source (4). Each separate area (10, 11, 12) is subdivided into various small areas so that the surface of the flat waveguide is subdivided into a large number of small areas (10-1, 11-1, 12-1, . . . 10-11, . . . 1241). Each small area (10-1, 11-1, 12-1, . . . . 10-11, . . . 12-41) is bounded by small areas (10-1, 11-1, 12-1, . . . 10-11, . . . 12-41) tuned to other light wavelengths. A polarizer (6) is present above the waveguide (2) to reflect light polarized in one direction back to the reflective liquid crystal display (1) and to transmit image-wise polarized light in a direction transverse to the one direction.
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