Patent ID: 7695168

Claim:
An optical film comprising: a set of elements disposed adjacent to each other; and an external material comprising a first layer, a second layer and a third layer, each layer having a refraction coefficient; wherein each element comprises; a lower pyramid comprising a first lower base, a first upper base, a first vertex angle, a plurality of first inclined planes and a second refraction coefficient, the lower pyramid being a truncated pyramid; an upper pyramid comprising a second lower base, a second upper base, a second vertex angle, a plurality of second inclined planes and a third refraction coefficient, the upper pyramid being a non-truncated pyramid; and a plurality of element planes comprising the first inclined planes and the second inclined planes; wherein the first lower base defines a base of the element and the first upper base coincides with the second lower base; wherein the first lower base of each element disposed adjacent to each other forms a common surface of the plurality of elements, the lower and upper pyramids protruding from one side of the common surface; wherein the external material covers the plurality of element planes, the first layer being disposed between the elements, the second layer being disposed over second upper bases of the elements, the third layer being disposed beneath the first lower bases of the element, and the refraction coefficient of each of the first, second and third layers of the external material is greater than the second and third refraction coefficients of the lower pyramid and the upper pyramid, respectively, wherein the refraction coefficient of the third layer is different from the second refraction coefficient of the lower pyramid, and wherein the first and second inclined planes each comprise only three inclined planes, respectively.