Patent ID: 6454443
Filing Date: 2002-09-24
Classification: F21S,F21V

Abstract:
A method of determining a reflective surface of a reflector used in a vehicle lamp, said method comprising:a condition setting step of setting a light source position at which a light source is to be placed, and an optical axis that passes said light source position and that defines a direction into which light from said light source is to be reflected by a reflector; a free-formed surface creating step of creating a free-formed surface satisfying a predetermined shape constraint; a free-formed surface selecting step of selecting said free-formed surface satisfying a predetermined functional condition, as a free-formed surface to be used for creation of a reflective surface; a reflective surface creating step of dividing said free-formed surface selected, into a plurality of segments and assigning a reflective surface element for reflecting the light from said light source placed at said light source position, into the direction along said optical axis, to each of said segments, thereby creating a reflective surface including a plurality of said reflective surface elements; and a reflective surface selecting step of setting an evaluation axis for evaluation of optical reflection characteristics of said reflective surface, preparing a light reflecting region distribution by determining for each portion of said reflective surface a reflecting region accepting the light from said light source placed at said light source position and reflecting the light into the direction of said evaluation axis, and selecting said reflective surface with said light reflecting region distribution satisfying a predetermined region distribution condition, as a reflective surface to be used for the reflector.