| 摘要 |
Off-axis total internal reflection Fresnel lenses and projection screens are disclosed that, when combined, enable construction of projection assemblies for rear-projection-type screen devices (e.g., projection television systems) that are thinner, provide easier handling and maintenance, and have improved contrast, focusing, and resolution when compared with conventional projection screen devices. The off-axis Fresnel lens comprises a plurality of concentric, outwardly-extending, total internal reflection-type prism facets, the top side of which may be aspherical. Embodiments of the invention also include projection screens having at least one diffuser and one lenticular lens. In addition, one or more opaque layers may be used to improve contrast. The various components, e.g., the fresnel lens, the diffuser, the lenticular lens(es), the opaque layer(s), etc. are all combined, or connected, in such a way as to eliminate substantially all air gaps within the connections.
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