Patent ID: 7794108
Filing Date: 2010-09-14
Classification: G09F

Abstract:
1. A billboard, comprising: a substrate; a plurality of pattern units provided at a first side of the substrate, each of the pattern units comprising at least first, second, third and fourth pattern cells arranged in a matrix, the at least first pattern cells of the pattern units together forming a first picture, the at least second pattern cells of the pattern units together forming a second picture, the at least third pattern cells of the pattern units together forming a third picture and the at least fourth pattern cells of the pattern units together forming a fourth picture; a plurality of light sources disposed at an opposite second side of the substrate and configured for emitting light rays toward the substrate; and a lens array corresponding to the pattern units arranged on one surface of the substrate at the first side thereof, the lens array displaying images of the first, second, third and fourth pictures at different viewing angles, respectively, wherein the lens array comprises a plurality of lenses arranged in rows and columns, and each of the lenses comprises a second-order surface through which the light rays are output from the lens and a planar surface thorough which the light rays enter the lens, the planar surface being located facing a corresponding pattern unit, the planar surface being divided by at least two reference surfaces in the each of the lenses into at least first, second, third and fourth parts which are arranged in a matrix and located corresponding to the at least first, second, third and fourth pattern cells of the corresponding pattern unit, the at least first and second reference surfaces having different focuses.