JPH0310604Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in a high-pressure metal vapor discharge lamp comprising a heat insulator provided at the end of an arc tube made of translucent ceramic.

In order to improve the color rendering of high-pressure metal vapor discharge lamps, such as high-pressure sodium lamps, it is known to provide a heat insulator at the end of an arc tube made of translucent ceramic.

Conventionally, such means have been widely known and practiced by wrapping a thin plate or foil made of a heat-resistant metal such as tantalum or molybdenum around the end of the arc tube, or by wrapping the thin plate or foil into a cap. It is molded into a shape and fitted into the end of an arc tube to serve as a heat insulator.

However, with a structure in which a thin plate or foil is wrapped around the end of the arc tube, it is difficult to secure the thin plate or foil at a predetermined position on the arc tube accurately and without movement, resulting in variations in lamp characteristics. It has the disadvantage of being easy.

In addition, in the structure where a thin plate or foil is formed into a cap shape and fitted to the end of the arc tube, it is difficult to manufacture the heat insulator because the thin plate or foil is deep-drawn using a press, and the heat insulator deforms during handling. It has the disadvantage of being easy.

Furthermore, in either structure, in order to prevent the heat insulator fitted to the end of the arc tube from moving, the heat insulator must be fixed to the arc tube support using a special support wire or insulator. The disadvantage was that the structure was complicated and assembly was time-consuming.

The object of the present invention is to provide a high-pressure metal vapor discharge lamp that eliminates the above-mentioned drawbacks.

FIG. 1 is an external view of a high-pressure metal vapor discharge lamp according to the present invention. In the figure, 1 is an arc tube made of translucent ceramic, and 2a and 2b are heat insulators provided at the ends of the arc tube 1. The arc tube 1 is the arc tube support 3
It is supported at a predetermined position within the outer sphere 5 by arc tube support lines 4a and 4b.

In the present invention, heat insulators 2 provided at both ends of the arc tube 1
As shown in FIG. 2, instead of using a thin plate or foil made of heat-resistant metal as in the conventional case, as shown in FIG. A bottomed cylindrical thermal insulation cap 2 is used. This heat insulating cap 2 is fitted onto the end of the arc tube 1 in the shape shown in the figure, and is held and fixed by a part of the arc tube support wire 4 which is crossed over the current-carrying conductor 6 of the arc tube 1 and fixed by welding. do. It is desirable that the arc tube support wire 4 is welded and fixed to a portion of the current-carrying conductor 6 of the arc tube 1 that is as close to the end face of the arc tube 1 as possible so as to intersect with the current-carrying conductor 6. If the arc tube support line 4 is separated from the end face of the arc tube 1 and welded above the current-carrying conductor 6, the distance between the arc tube support line 4 and the heat insulation cap 2 will increase, causing the heat insulation cap 2 to move, which will affect the lamp characteristics. This is because it becomes unstable. However, after fitting the heat insulating cap 2 to the end of the arc tube 1, it is not easy to weld the arc tube support wire 4 to a portion of the current-carrying conductor 6 as close to the end surface of the arc tube 1 as possible.

Therefore, in order to solve this problem, the following structure can be considered. As shown in FIG. 3, in the first structure, before fitting the heat insulation cap 2 to the end of the arc tube 1, the arc tube support wire 4 is placed as close to the end surface of the arc tube 1 as possible among the current-carrying conductors 6. Weld the parts in advance. Then, the heat insulating cap 2 is fitted onto the end of the arc tube 1 with both sides of the welded portion of the arc tube support line 4 bent toward the tip of the current-carrying conductor 6. After that, the arc tube support wire 4 is bent back to its original state so as to press the heat insulating cap 2.

The second structure includes an arc tube 1 as shown in FIG.
After fitting the heat insulating cap 2 to the end of the arc tube support wire 4, the arc tube support wire 4 is welded to a position of the conductor 6 where it can be easily fixed. Then, both sides of the arc tube support line 4 are curved or bent in the direction of the heat insulating cap 2 to hold down the heat insulating cap 2, and then the ends of the arc tube support line 4 are fixed to the arc tube support columns 8a and 8b.

With these structures, rattling of the heat insulation cap 2 can be easily and reliably prevented.

As is clear from the above description, the present invention uses a bottomed cylindrical heat insulating cap made of ceramic as a heat insulating body installed at the end of the arc tube made of translucent ceramic, and also uses this cap to conduct electricity through the arc tube. It is fixed to the end of the arc tube by holding it down with a part of the arc tube support wire that is welded and crossed over the conductor.
Since the heat insulator is made of ceramic, it has the same shape and
It is possible to easily manufacture a heat insulating body with the same dimensions and quality. Further, the ceramic heat insulator does not deform during handling and can be easily and reliably attached to the end of the arc tube. As a result, the lamp characteristics after assembly are also extremely stable.

Furthermore, the present invention has a structure in which the heat insulator is held and fixed by the arc tube support wire, so there is no need for a dedicated support wire or insulator, and the number of parts is small and assembly is easy. There are advantages.

[Claims for Utility Model Registration] At the end of the arc tube 1 made of translucent ceramic,
It is made of ceramic and has a current-carrying conductor 6 of the arc tube 1 at the bottom.
The arc tube support wire 4 is fitted with a heat insulating cap 2 having a bottomed cylindrical shape and having a through hole 7 for charging the arc tube, and the heat insulating cap 2 is welded and fixed across the current-carrying conductor 6 of the arc tube 1. A high-pressure metal vapor discharge lamp characterized by being partially held down and fixed.

[Brief explanation of drawings]

Fig. 1 is a side view of a high-pressure metal vapor discharge lamp according to the present invention, Fig. 2 is a perspective view showing an embodiment of the arc tube end of the same discharge lamp, and Fig. 3 is the arc tube end of Fig. 2. A perspective view showing the arrangement of each part when assembling the 4th
The figure is a perspective view showing another embodiment of the arc tube end of the discharge lamp according to the present invention. In FIGS. 1 to 4, 1... arc tube; 2;
2a, 2b... heat insulator, 4, 4a, 4b... arc tube support line, 6... energizing conductor, 7... through hole.