Reflector for a vehicular lamp and method of producing a die therefor

Abstract

A lamp reflector for a lamp that conforms to a vehicle body shape and method of producing such reflector, including a die therefor. The lamp reflector comprises a plurality of reflecting sections disposed about an optical axis of the lamp. Significant differences in light distribution at the boundaries between the reflecting sections are avoided by using a fundamental surface K of a reflecting surface 3 that may be generated as a free surface so as to conform to a vehicle body shape. After a reference curve is set on the fundamental surface K, several 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.sub.-- T of the tangential plane T and a normal vector N.sub.13 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.