Patent ID: 9182529
Filing Date: 2015-11-10
Classification: F21K,F21V,G02B

Abstract:
1. A light guide element having a length and an angle of total reflection, the light guide element comprising: a light-incident surface having a first outer peripheral edge and a first inner peripheral edge, there is a distance between the first outer peripheral edge and the first inner peripheral edge; a light-emitting surface which is opposite to the light-incident surface, wherein an area of the light-emitting surface is greater than an area of the light-incident surface, wherein the light-emitting surface includes a second outer peripheral edge and a second inner peripheral edge; a first reflecting surface connecting the first outer peripheral edge and the second outer peripheral edge; and a second reflecting surface connecting the first inner peripheral edge and the second inner peripheral edge, wherein an angle is formed between an extension line of the first reflecting surface and an extension line of the second reflecting surface; wherein the angle is smaller than the angle of total reflection, and the length of the light guide element is greater than a predetermined distance divided by tangent of the angle of total reflection; wherein the predetermined distance is determined by a distance between the first outer peripheral edge of the light-incident surface and where the at least one light beam enters the light guide element; and wherein the second reflecting surface extends from the first inner peripheral edge of the light-incident surface to the second inner peripheral edge of the light-emitting surface inwardly.