Patent ID: 8289473
Filing Date: 2012-10-16
Classification: F21V,F21Y,G02F

Abstract:
1. A lens for illumination for spreading light emitted from a light source so that a surface to be irradiated is irradiated with the spread light, the lens comprising: a light entrance surface through which the light emitted from the light source enters the lens; and a light exit surface through which the light that has entered the lens exits the lens, the light exit surface being axisymmetric with respect to an optical axis, wherein the light exit surface has a first light exit surface and a second light exit surface, the first light exit surface projecting toward a vertex on the optical axis, and the second light exit surface extending outwardly and continuously from a periphery of the first light exit surface to form a convex, when a position of the light source on the optical axis is defined as a starting point, the first light exit surface has a shape allowing light that has been emitted from the starting point at an angle of a specified value or more with respect to the optical axis and reached the first light exit surface to reach the surface to be irradiated by totally reflecting the emitted light at a first point thereon reached by the emitted light first and then refracting the totally reflected light at a second point thereon reached by the emitted light after being totally reflected, and the second light exit surface has a shape allowing light that has been emitted from the starting point and reached the second light exit surface to reach the surface to be irradiated by refracting the emitted light at a point thereon reached by the emitted light.