Projection screen having electric field responsive reflectance layer and a photosensitive material
First Claim
Patent Images
1. A projection screen for reflecting from a first side a projected image with enhanced contrast, comprising:
- an active layer whose reflectance can be changed under the influence of an electric field;
at least a first electrode for applying an electric field across the active layer; and
a photosensitive material whose electrical or dielectric properties can be changed under illumination, wherein the photosensitive material is arranged such that the electrical field across local regions of the active layer is dependent on the illumination incident upon the photosensitive material in each such local region with the result that reflectance of the active layer is locally dependent upon an intensity of light incident upon the first side of the projection screen in that local region.
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Abstract
An active screen reflects a high contrast projected image. The screen has (1) an active layer having visible optical properties changed by an electric field provided by electrodes and (2) a photosensitive layer. The photosensitive layer is such that the electric field across a localized area of the active layer depends on the illumination incident on the photoconductor in that area. The local reflectance of the projection screen thus depends on the intensity of light incident upon it. In one embodiment, the reflectance of the screen increases with increasing light intensity to produce a high contrast reflected image.
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Citations
21 Claims
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1. A projection screen for reflecting from a first side a projected image with enhanced contrast, comprising:
- an active layer whose reflectance can be changed under the influence of an electric field;
at least a first electrode for applying an electric field across the active layer; and
a photosensitive material whose electrical or dielectric properties can be changed under illumination, wherein the photosensitive material is arranged such that the electrical field across local regions of the active layer is dependent on the illumination incident upon the photosensitive material in each such local region with the result that reflectance of the active layer is locally dependent upon an intensity of light incident upon the first side of the projection screen in that local region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
- an active layer whose reflectance can be changed under the influence of an electric field;
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20. A projection system, comprising a projection screen and a projector for projecting an image on the projection screen the projection screen being adapted for reflecting from a first side a projected image with enhanced contrast, and comprising:
- an active layer whose reflectance can be changed under the influence of an electric field;
at least a first electrode for applying an electric field across the active layer; and
a photosensitive material whose electrical or dielectric properties can be changed under illumination, wherein the photosensitive material is arranged such that the electrical field across local regions of the active layer is dependent on the illumination incident upon the photosensitive material in each such local region with the result that reflectance of the active layer is locally dependent upon an intensity of light incident upon the first side of the projection screen in that local region. - View Dependent Claims (21)
- an active layer whose reflectance can be changed under the influence of an electric field;
Specification