Abstract: The electric incandescent lamp according to the invention has an annular mirror coating on a hemispherical portion of its lamp envelope and a filament arranged zigzagwise between supporting points which are located on the surface of an imaginary cone. The filament is situated outside the part of the lamp vessel provided with the mirror coating. The lamp is particularly suitable for use as a traffic signal lamp and produces together with an external paraboloidal reflector a light beam of high luminous intensity at the center and in directions enclosing a small angle with the axis of the beam, as a result of which the lamp may be designed for a comparatively low power.

Abstract: The electric lamp has a lamp vessel (1) of which a wall portion (4) is mirror-coated at its inner surface with an aluminum layer. This wall portion (4) has a boundary (5) near the largest diameter (2) of the lamp vessel (1). This boundary (5) is adjoined by a zone (10) coated with a transparent aluminum oxide layer. In the lamp, a dark zone caused by a very thin aluminum layer adjoining the boundary (5) is avoided.

Abstract: The electric lamp has a lamp vessel of which a wall portion is mirror-coated at its inner surface with an aluminum layer. This wall portion has a boundary near the largest diameter of the lamp vessel. This boundary is adjoined by a thermally connected zone having a transparent aluminum oxide layer. In the lamp, a dark zone caused by a very thin aluminum layer adjoining the boundary is avoided.