| 摘要 |
An image display apparatus utilizing a hollow light guide having a non-diffuse highly reflective inner rear surface and a non-diffusely partially transmissive, non-diffusely partially reflective image-bearing front surface. A light source emits light into one end of the light guide. The image-bearing front surface has high reflectivity and low transmissivity adjacent portions of the image which are to be illuminated at relatively low intensity; and, has low reflectivity and high transmissivity adjacent portions of the image which are to be illuminated at relatively high intensity. This can, for example, be achieved by forming the image-bearing front surface of an outer image-bearing sheet laminated to an inner sheet of highly reflective perforated material. The inner sheet's apertures are distributed, or the size of the apertures is varied, such that any selected area on the inner sheet is apertured in proportion to the desired intensity of illumination of the image adjacent that selected area. Alternatively, the image-bearing front surface may be a half-tone imaged sheet of high reflectivity material, with the image being formed such that the density of the image varies in proportion to the desired intensity of illumination of the image adjacent. A prismatic film mounted in front of the image-bearing front surface redirects light into the perpendicular viewing direction.
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