The invention relates to a line-voltage-operated incandescent lamp having
a translucent lamp vessel sealed in a vacuum-tight manner; PA0 current supply conductors entering through the wall of the lamp vessel and mechanically interconnected inside the lamp vessel by means of glass beams with which they constitute a frame; PA0 a filament comprising several helically wound sections which are stretched at least substantially parallel to each other in the frame, each end of the filament being electrically connected to a respective current supply conductor; and PA0 two sets of supports which are anchored in a respective glass beam of the frame. Each support consists of a wire terminating in a hook and each hook engages the filament between a respective pair of adjacent sections of the filament.
Such a lamp is known from British Patent Specification 2,069,233 to which U.S. Pat. No. 4,367,428 corresponds.
The known lamp has a frame of a rigid construction, as a result of which the lamp is capable of withstanding shocks. In this respect, the known lamp is superior to lamps which were previously commercially available, in which two tungsten wires are anchored each with one end in one of the glass beams of the frame, while the other end of these wires is helically wound and grips around a respective current supply conductor and is fixed thereto. In these commercially available lamps, the length of the frame and hence the stress in the filament can be readily adjusted by slipping the helically wound ends further or less far over the current conductors, but the frame is not very capable of withstanding shocks.
In the manufacture of the lamp according to the that British Patent Specification, it has proved to be difficult to mount the filament with the correct tension in all its sections.