A lamp with power supply wires reaching outside the lamp

FIELD OF THE INVENTION

The invention is related to a lamp whereby the burner of the lamp is fixed in the base part of the lamp by means of cement and whereby at least one power supply wire is embedded in said cement and reaches outside the lamp in order to be connected with an electric power supply member.

BACKGROUND OF THE INVENTION

It is generally known to make use of cement in order to fix the burner of a lamp in the base part of the lamp. The base part of the lamp may comprise a cap, means for fixing the lamp in a lamp-holder and/or light reflector means in order to produce a light beam. Cement is an appropriate connection means between the burner and the base part and it can resist the very high temperature of the burner of the lamp. By means of cement, the light source of the burner can be positioned precisely at a predetermined location with respect to the base part of the lamp. The exact positioning of the light source with respect to the base part of the lamp may be important, in particular when the light source has to be located at a predetermined position with respect to a reflector in order to produce a predetermined light beam. Such lamps can be used for automotive headlights or for beamers or projectors, etc.

The base part of the lamp comprises means for connecting the lead-in wires of the burner to electric power supply members, which power supply members are present in the lamp-holder. In the lamp according to the invention said means for connecting the lead-in wires comprise at least one, but in most cases two power supply wires, which power supply wires are partly embedded in the cement and are reaching outside the base part of the lamp. The power supply wire may be the same wire as the lead-in wire of the burner.

When the lamp is installed in the lamp-holder, the power supply wires have to be connected to the power supply members, for example by clamping means of the power supply members. Thereby, the power supply wire is bended towards the power supply member, and during that operation, the power supply wire may break, in particular when it is made of relative fragile material, such as molybdenum or other metals that are resistant against the very high temperatures of the lamp during operation.

In case the lamps are installed in, for example, a beamer during the assembling operation of the beamer, the power supply wires can be carefully connected to the power supply members in such manner that the wires does not break. However, in case the lamps are delivered as spare parts for that beamer, the lamp will be installed by the operator of the beamer, whereby there is a real chance of breakage of a power supply wire.

SUMMARY OF THE INVENTION

The object of the invention is a lamp whereby the burner of the lamp is fixed in the base part of the lamp by means of cement and whereby at least one power supply wire is embedded in said cement and reaches outside the lamp in order to be connected with an electric power supply member, whereby the chance of breakage of the power supply wire during installation of the lamp is substantially reduced.

In order to accomplish with that object, at least a part of said power supply wire is surrounded by a coil of metal wire, whereby a part of said coil is embedded in the cement and another part reaches outside the cement. It has appeared that crashes in the power supply wires always occur near the location where the wire leaves the cement. Movement of the power supply wire may result in sharp bending of the wire at that location. When a coil of metal wire is wound around the power supply wire at that location, the wire cannot be bended sharply and the chance of breakage will be reduced to a minimum. In a preferred embodiment, the base part of the lamp comprises a tube-like portion in which portion the burner is fixed by means of cement, whereby the burner extends outside the cement at one end of the tube-like portion and said at least one power supply wire extends outside the cement at the other end of the tube-like portion. Thereby the power supply wire or wires leave the lamp at the end of the lamp opposite to the burner, where the temperature is lower than the very high temperature of the burner.

Preferably, the base portion of the lamp comprises a reflector surrounding at least a portion of the burner. As said before, the use of cement to fix the burner to the base part of the lamp enables an exact positioning of the burner with respect to the base part, and therewith to the reflector, when that reflector is a portion of the base part of the lamp. In a preferred embodiment, two power supply wires are partly embedded in the cement, whereby both power supply wires are surrounded by a coil of metal wire, which coils are both partly embedded in the cement. Many lamps are provided with two power supply wires, and preferably both wires are embedded in the cement of the lamp in the same way and near each other at the end of the lamp opposite to the burner.

Preferably, the burner is a high-pressure gas discharge burner, whereby a pinch portion of the burner is embedded in the cement, which pinch portion comprises at least one lead-in wire, which lead-in wire is said power supply wire being partly embedded in the cement and reaching outside the lamp. This preferred embodiment of the invention is preferably provided with a reflector. Thereby, an exact positioning of the light source with respect to the reflector can be achieved, also in case the shape of the pinch portion is varying a little. Furthermore, the one or two lead-in wires can easily be used as power supply wires, because at least one of them is surrounded by the cement at the location where it leaves the embedded pinch portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further elucidated by means of a description of an embodiment of a high-pressure gas discharge lamp, whereby two power supply wires reach outside the lamp in order to be connected with electric power supply members, whereby reference is made to the drawing comprising schematic representations, whereby: Fig. 1 is a sectional view of the lamp; and Fig. 2 shows a detail of the lamp in sectional view.

DETAILED DESCRIPTION OF THE EMBODIMENTS Figure 1 shows the lamp assembly comprising a base part 1 and a burner 2.

The base part 1 is mainly made of glass (glass, glass-ceramic or quartz) and comprises a reflector 3, which reflector 3 is bell- shaped, whereby its central axis is in the plane of the drawing. The reflector 3 is provided with a light reflecting coating on its parabolic-shaped inner surface 4. The burner 2 is a high-pressure gas discharge burner and is present inside the reflector 3, so that the light source in the gas discharge space 5 of the burner 2 is located at or near the focus point of said parabolic shape. Inside the gas discharge space 5 are two electrodes 6, 7, each being electrically connected through a molybdenum foil 8, 9 with lead- in wires 10, 11. Each molybdenum foil 8, 9 is located in a sealed end portion or pinch portion

12, 13 of the burner 2, whereby the two pinch portions 12, 13 extend outwardly in opposite directions, substantially along the central axis of the base part 1.

The burner 2 is attached to the base part 1 of the lamp through pinch portion

13, which pinch portion 13 is fixed in a tubular portion 14 of the base part 1, whereby it is embedded in cement 15 that is present in the cylindrical space in the tubular portion 14. The lead-in wire 11 for supplying electric current to electrode 7 leaves the burner 2 through pinch

portion 13, and is also embedded in the cement 15. The end of lead-in wire 11 reaches outside the cement 15 in order to be connected with a power supply member (not shown), and thereby the lead-in wire 11 functions as a power supply wire of the lamp.

The other lead-in wire 10 leaves the pinch portion 12 at the other end of the burner 2 and is connected with electric conductor wire 16. Conductor wire 16 is embedded in the cement 15, where it is connected to the end of power supply wire 17. The other end of power supply wire 17 reaches outside the cement 15 in order to be connected with a power supply member (not shown). Lead-in wire 11 as well as power supply wire 17 is surrounded by a coil 18, 19 of metal wire at the location where the lead-in wire 11 and the power supply wire 17 respectively leave the cement. The coils 18, 19 are partly embedded in the cement 15 and reach outside the cement 15.

Figure 2 shows the lead-in wire 11 being partly embedded in the cement 15 and being surrounded by coil 18. Thereby, the coil 18 is shown in a sectional view. From figure 2 it will be clear that the lead-in wire 11 cannot be bended in a sharp curve at the location where the coil 18 is present, so that the risk of breakage at that location is reduced.

The embodiment as described above is merely an example of a lamp assembly according to the invention; many other embodiments are possible.

LIST OF REFERENCE NUMERALS:

1. base part of the lamp

2. burner of the lamp

3. reflector

4. reflecting surface of the reflector 3

5. gas discharge space of the burner 2

6. electrode

7. electrode

8. molybdenum foil

9. molybdenum foil

10. lead-in wire

11. lead-in wire

12. sealed pinch portion

13. sealed pinch portion

14. tubular portion of base part 1

15. cement

16. conductor wire

17. power supply wire

18. coil of metal wire

19. coil of metal wire