Patent ID: 9523810
Filing Date: 2016-12-20
CPC Classification: G02B

Claim Text:
1. An illumination device comprising: a transmissive light guide body having a first main surface, a second main surface that is located on the opposite side of the first main surface, and four side end faces that connect the first main surface to the second main surface, at least one of the four side end faces being an incidence face; a plurality of light sources that are provided in a first direction, in which the incidence face extends, so as to face the incidence face; a plurality of light deflection elements that are independently provided on the first main surface, deflects light, which is incident to the incidence face and is introduced into the inside of the light guide body, to be directed to the second main surface, the light deflection elements being in a concave or convex scattered arrangement; and an optical path control element that is provided on the second main surface, extends in a second direction substantially orthogonal to the first direction, and regulates an optical path of the light that is introduced into the inside of the light guide body, wherein a density D of the light deflection elements, which represents the number of the light deflection elements being present per unit area, that increases with an increase in a distance in the second direction from the incidence face to the position at which the light deflection elements are arranged, an arrangement pattern of the light deflection elements is separated into a plurality of regions in the second direction, in one region, an arrangement interval of the light deflection elements in the first direction is substantially constant, an arrangement interval of the light deflection elements in the second direction varies to be small with increased distance from the incidence face, in between the regions, as the arrangement interval of the light deflection elements in the first direction discontinuously varies, the arrangement interval in the first direction becomes small with increased distance of the region from the incidence face, where the region which is close to the incidence face is referred to as a first region, the region which is away from the incidence face is referred to as a second region, as the arrangement interval of the light deflection elements in the second direction discontinuously varies at the boundary between the first region and the second region, the arrangement interval of part of the first region which is closest to the boundary is smaller than the arrangement interval of part of the second region which is closest to the boundary, regarding the density D of the light deflection elements which represents the number of the light deflection elements being present per unit area, a function of reciprocal number 1/D(y) of a density function D(y) based on a distance y from the incidence face to a position at which the light deflection elements are provided is represented by mainly summing two functions of a first function F(y) and a second function S(y), the first function F(y) monotonically decreases with respect to the distance y, and while the second function S(y) repeatedly decreases and increases several times with respect to the distance y, an absolute value of a maximum amplitude value of each cycle thereof monotonically decreases.