Ellipsoidal reflector lamp

An ellipsoidal reflector lamp characterized by low brightness and high illumination comprising:

• a filament, a blown glass envelope having an ellipsoidal, [specular] reflector surface and a translucent face, wherein the major axis of said ellipsoidal envelope approximately intersects said filament and the minor diameter of the ellipsoid defines the approximate boundary between said surface and said translucent face, wherein said face includes a curved portion so shaped that direct light from said filament is incident approximately normal thereto, and wherein said face includes a conical section which joins said curved portion to said ellipsoidal surface approximately at the minor diameter thereof, said conical portion forming an angle with the minor diameter at least approximately conforming to the path of the last ray reflected near the minor diameter said ellipsoid has an eccentricity of from 0.66 to 0.88 inclusive, said face is outwardly positioned no further [that] than 1/2 d from the intersection of the axes of the ellipsoid, where d is the distance from said intersection to a focus of the ellipsoid, and wherein direct and reflected light are produced within approximately equal solid angles.