Halogen Cycle Incandescent Lamp Having an Intermediate Lead-in Conductor Part

The present invention relates to a halogen cycle incandescent lamp, and more particularly to such a lamp which has a lamp housing made of quartz glass or hard glass and current leads passing through the housing which, simultaneously, may serve as connecting pins for the lamp.

It has been proposed to make halogen cycle incandescent lamps with connecting leads passing through the glass housing, made of molybdenum or tungsten wire. The high temperature of operation of halogen lamps requires the use of quartz glass or hard glass for the lamp housing. The internal connections of the lamp lead-in wires are usually much smaller or thinner than the external connections of the lamp leads if the external connections are to be used at the same time as connecting pins which can be fitted into a socket formed as a connector with spring clips to make electrical contact with the projecting lead-in wires. In order to connect the externally projecting pins and the internally projecting lead-in elements, welding processes have been used. It has been found that if molybdenum lead-in wires or tungsten lead-in wires are welded together, regions of brittle zones may form at the weld points. This detracts from the mechanical strength of the lead-in wires as well as of the lamp as a whole.

It is an object to provide a lamp in which lead-in wires can be used having lead wires which are thicker at the outside than at the inside, and in which weakening of the lead-in connections is eliminated.

Briefly, an intermediate connecting element of nickel is used between the internally projecting and externally projecting lead-in wires which may be made either of molybdenum or tungsten, for example. Either arc-welding or flame-welding is a suitable process for welding together the internally projecting lead-in wires to the externally projecting wires with the intermediate nickel connector.

FIG. 1 is a schematic illustration of two lead-in connectors for a halogen cycle incandescent lamp; and

FIG. 2 is a halogen cycle incandescent lamp with a housing made of hard glass and pin socket connections.

A housing 1 (FIG. 2) of hard glass retains therein a filament 2. The filament 2 receives electrical power and is mechanically supported by leads 3, 3'. The leads 3, 3' are made of two parts 3a, 3b and 3a', 3b', respectively. The two parts 3a, 3b and 3a', 3b', respectively, have different diameters. The wires 3, 3' are of molybdenum. The diameter of the wire portions 3a, 3a' may, for example, be about 0.4 mm. The diameter of the wire portions 3b, 3b', which form connection pins, may for example be about 0.7 mm.

In accordance with the invention, the thinner, internally projecting wires 3a, 3a' are joined to the respective externally projecting wire pins 3b, 3b' by an interposed short element 4 of nickel. The element 4 of nickel may be a short piece of nickel wire, having a diameter which, preferably, at least approximately matches the diameter of the externally projecting pins 3b, 3b', in this case a diameter of about 0.7 mm. It can be very short, for example only about 0.3 mm long. The weld connection, with the interposed nickel element 4, can be done by arc-welding. Flame-welding is also suitable.

The nickel element 4 forms a welding assistance zone. The nickel portion eliminates direct connection, by welding, of molybdenum-to-molybdenum, or of tungsten-to-tungsten, if tungsten wires are used; thus, the danger of obtaining a brittle zone within the joined or welded lead wires 3, 3' is eliminated. The welding or connecting zone normally is positioned within the region of the press 5 of the lamp. A weld connection molybdenum-nickel-molybdenum provides for reliable mechanical strength of the wires, and eliminates breakage of the lamp or lamp housing, particularly in the region of the press 5, as well as damage to the pins in case of careless installation of the lamp in a socket, or when subjected to vibration or shock. The molybdenum-nickel-molybdenum or tungsten-nickel-tungsten junction, particularly when located within the press of a lamp, provides a reliable, secure and air-tight connection. In contrast to a weld formed by direct welding of molybdenum to molybdenum, or tungsten to tungsten, the weld which includes the intermediate part of nickel does not decay.