DE4300103

• Main Authors: BAN, NAOTO, KAWASHIMA, HIROSHI, SHIMIZU, SHIZUOKA, JP
• Format: Patent
• Language: English
• Published: 08.07.1993
• Subjects: BLASTING; FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMSTHEREOF; HEATING; LIGHTING; MECHANICAL ENGINEERING; NON-PORTABLE LIGHTING DEVICES; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHERARTICLES, NOT OTHERWISE PROVIDED FOR; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLEEXTERIORS; WEAPONS

A lamp reflector for a lamp that conforms to a vehicle body shape comprises a plurality of reflecting sections disposed about an optical axis of the lamp. Significant differences in light distribution at the boundaries between the sections are avoided by using a fundamental surface K of a reflecting surface 3 that may be generated as a free surface to conform to the vehicle body shape. After a reference curve is set on fundamental surface K, points P, P, ... are specified on the reference curve. A very small reflecting surface R is determined at the point P according to the law of reflection so that a ray emitted from a light source and made incident on the point P is reflected to become a ray in parallel with the optical axis. Then, a tangential plane T of the fundamental surface at the point P is determined, and an outer product W of a normal vector N_T of the tangential plane T and a normal vector N_R of the very small reflecting surface R is calculated. A closed curve is generated by performing vector control in which the outer product W is employed as its tangential vector at each reflection point P around the optical axis, and connecting the tangential vectors by spline approximation. A V-shaped groove having a slanting surface corresponding to a reflecting surface of a reflecting step is formed on a die workpiece block along the closed curve. The reflecting step formed by die forming assumes a loop form around the optical axis without being divided into several reflecting sections with respect to the optical axis.