ILLUMINATION DEVICE FOR GENERATING NON-SYMMETRIC LIGHT BEAM, OPTICAL LENS ARRAY AND OPTICAL LENS

摘要

The invention relates to illumination devices of the type used intraffic lights; to optical lense arrays for use in devices and systems of this and other types, and to optical lens to be used separately on as elements of such arrays. The lens of the invention is able to deviate a part of a light beam at an oblique angle to its optical axis along which the main part of the beam propagates. This effect is achieved by forming at least one side of the lens as a Fresnel surface combined from at least two zones with mutually different set of optical characteristics. If the combined Fresnel surface is a spherical Fresnel surface consisting of concentric facets, or grooves, its constituting zones have mutually offset optical axes. In case of a combined cylindrical Fresnel surface its zones mutually differ in their focal distances. In both cases one zone, corresponding to said main part of the beam, has an area at least twice as large as an area of any other zone, while one or more lesser zones are shifted respective to the largest zones in the direction of required deviation of the part of the light beam. Various embodiments of the novel lens can be produced by forming its other side as a conventional cylindrical Fresnel surface of a combination of several conventional cylindrical surfaces with their generatrixes made parallel or perpendicular to the direction of mutual shift of zones at the first lens side. A plurality of lenses according to the same or different embodiments of the invention can be arranged in arrays which also are capable to deviate a part of the light beam in a required direction off its main axis and thus to generate non-symmetric distribution of light at least in one plane of light propagation. This makes the lens and the array of the invention especially effective for illumination devices of traffic lights or similar signalling systems. The illumination device of the invention employs an array of powerful light diodes and two lens arrays. The first one of said arrays functions as a condenser, with each row of of condenser lens corresponding to a certain row of the diodes. The second lens array is as a diffuser. At least one of these arrays is formed by lenses having at least one combined Fresnel surface, and both arrays may be formed as a monolithic condensing/diffusing unit.