The invention relates to a lamp comprising a cap and a burner attached to the cap, wherein the burner and the cap are connected through a metal part, which part engages the burner. Such a lamp, in particular a high-pressure discharge lamp, is suitable, for example, for use in mobile applications, such as for automotive headlights.
In general, the burner of a lamp comprises a bulb of transparent glass enveloping means for generating light. Normally, the cap of the lamp is made of synthetic resin material and is provided with electric guiding means for supplying electric power to the burner of the lamp. These guiding means comprise electrical contacts that can engage corresponding contacts at the lampholder, to which the cap can be connected.
For certain applications, such as automotive headlamps or lamps for projecting images on a screen, it is essential that the light source has an exact predetermined position with respect to the cap. The light source will then have a predictable location after the cap has been fixed in the lampholder. Furthermore, the connection between the burner and the cap must be stiff to avoid a relative movement of the burner with respect to the cap.
The object of the invention is a lamp, and a method of attaching a burner to the cap of a lamp whereby the burner is attached to the cap in an effective and simple manner.
To accomplish that object, said metal part, which engages the burner, has at least two legs, and preferably three legs, such that a portion of each leg engages a corresponding portion of the cap, said corresponding portion being of synthetic resin material of the cap, and said portion of each leg has been heated in order to melt the synthetic resin material and to deform it so as to correspond to the shape of the leg, whereby a mutual engagement of said portion of the leg and said corresponding portion of the cap is obtained. Melting the synthetic resin material means that the material becomes weak enough to be deformed.
Such a connection between said metal part and the cap is effective, because the shape of said portion of each leg and the shape of said corresponding portion of the cap will be complementary after the melting of the synthetic resin material, so that a complete engagement between said two portions is realized. Furthermore, this engagement can be realized while the burner and the cap are kept in the desired positions with respect to each other, which positions will be maintained after the connection between the metal part and the cap has been made.
The metal part may engage the burner of the lamp in several ways, but in one preferred embodiment said metal part comprises an annular portion surrounding a cylindrical portion of the burner, such that said legs extend from said annular portion. Said annular portion may be connected to the burner by means of glue or some other intermediary material, however, preferably the said annular portion includes spring means, so that said portion of the burner is engaged by said annular portion clamping around said portion of the burner.
Preferably, the legs, or at least portions of the legs, mutually diverge in directions away from the burner. A stable support of the burner is created thereby, also if the legs themselves are less stiff, or if only two strip-like legs are present.
In one preferred embodiment, said legs are leaf springs, i.e. the legs have a strip-like shape and are made of resilient metal. So, when the material of the leg is heated, the spring force of the leaf spring can press the relevant portion of the leg into the melted synthetic resin material in order to achieve the required engagement. Furthermore, the force exerted by the leaf spring may press the portion of the leg against the engaging portion of the cap in order to maintain the engagement. A less complex shape or a less intensive engagement can then be sufficient to keep said portions connected.
Preferably, said portion of each leg has a shape comprising one or more edges enclosing an angle with the longitudinal direction of the leg. The main force exerted on the connection between the leg and the cap will be in said longitudinal direction, and said edge, engaging the material of the cap, will resist said force easily.
In one preferred embodiment, said portion of each leg comprises one or more holes, so that the synthetic resin material of the cap can flow into said hole or holes when it is melted, resulting in an effective engagement.
The invention further relates to a method of attaching the burner of a lamp to the cap of the lamp, whereby metal part is fixed to the burner and said metal part is fixed to the cap, which metal part has at least two legs, and whereby—during fixation—the burner and the cap are kept in predetermined positions with respect to each other, such that a portion of each leg abuts against a corresponding portion of the cap, said corresponding portion being of synthetic resin material, so that said portion of each leg is heated in order to melt the synthetic resin material and to deform it so as to correspond to the shape of the leg, to obtain a mutual engagement of said portion of the leg and said corresponding portion of the cap.
In one preferred embodiment, said portions of the legs are heated by HF (high-frequency) heating. The lamp, i.e. the burner and the cap, can thus be surrounded by a coil for generating a high-frequency field in order to heat the relevant portions of the legs very fast to the required temperature. Such a heating operation can take place in a few seconds.
The invention will now be further elucidated by means of a description of an embodiment of a lamp, for which reference is made to the drawing comprising Figures, which are only schematic representations, in which:
The lamp furthermore comprises a cap 6, substantially made of synthetic resin material. At its upper side, the cap 6 is provided with a flange 7, extending in a radial plane. As is shown in
The lamp is a high-pressure discharge lamp with a double-ended burner 1, i.e. both ends of the burner are provided with electric guiding means for supplying electric power to the light source in the burner 1.
Furthermore, cap 6 is provided with a cylindrical bore 12 to accommodate the lower end of tubular member 11. The shape of the bore 12 corresponds to the shape of the lower end of member 11, so that tubular member 11 is kept in its axial position after it has been inserted into the bore 12.
The metal part 3 also comprises three legs 5 that extend in downward direction. Portions 19 of the legs 5 mutually diverge in the direction away from the burner 1. Near the end of each leg 5 there is a hole 20 in the strip-like material of the leg 5. The ends of the legs 5 may be provided with additional recesses forming edges of the material in a direction inclined to the longitudinal direction. Such edges improve the engagement with the portion of the cap 6 abutting such an edge.
On its left-hand side, the burner 1 is provided with tubular part 16 enclosing metal wire 24. The wire 24 is connected to electrical contact 25 in the central part of the cap 6. The cap is made of synthetic resin material except for the metal contacts 13,25. When the lamp is placed in a lampholder, the lampholder engages the cap 6 of the lamp, and the contacts 13,25 make contact with corresponding electrical contacts in the lampholder.
During the fixation operation, the burner 1 and the cap 6 are both maintained in an exact predetermined positions with respect to each other. The cap 6 is for this purpose engaged by a tool 27, and the burner 1 is engaged by a tool 29. Both tools are schematically shown in
The embodiment of the lamp as described above is only an example; a great many other embodiments are possible, including embodiments with other types of lamps.
Number | Date | Country | Kind |
---|---|---|---|
04100193.4 | Jan 2004 | EP | regional |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/IB05/50104 | 1/10/2005 | WO | 00 | 7/18/2006 |