Patent ID: 6361195
Filing Date: 2002-03-26
Classification: F21S,F21V

Abstract:
A method of determining a reflective surface of a reflector used in a vehicle lamp, comprising:a condition setting step of setting a light source position at which a light source is to be placed, and an optical axis passing said light source position and defining a direction into which light from said light source is to be reflected by the reflector; an initial reference line setting step of setting a plurality of initial reference lines each extending radially from a predetermined position on said optical axis so that on each of said initial reference lines luminous exitances M, specified in the direction along said optical axis for respective portions of said initial reference line, are constant; a surface reference line creating step of creating a plurality of surface reference lines by deforming said plurality of initial reference lines so as to satisfy the condition of Mmax/Mmin&lE;6 as to a maximum Mmax and a minimum Mmin on said plurality of initial reference lines out of luminous exitances M for the respective, entire, initial reference lines, and a predetermined shape constraint; a free-formed surface creating step of creating a free-formed surface comprising said plurality of surface reference lines; and a reflective surface determining step of dividing said free-formed surface into an array of segments and assigning a reflective surface element having a diffuse reflection region for diffusely reflecting the light from said light source position, to each of said segments, thereby determining a reflective surface comprising a plurality of said reflective surface elements.