JP3174221B2 - Metal halide lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention relates to high wattage metal halide lamps.

[0002]

2. Description of the Related Art A conventional metal halide lamp generally comprises an electrode rod and an electrode coil. An electrode having a shape in which the electrode coil is wound around the tip of the electrode rod and the tip of the electrode rod protrudes from the electrode coil is used. ing. In such an electrode, when the wire diameter of the electrode rod is increased, the temperature at the tip of the electrode decreases, a bright spot is generated, and the tip of the electrode evaporates and is deformed. At the same time, the temperature at the base of the electrode rises, causing damage to the arc tube. Further, when the diameter of the electrode rod is reduced in order to lower the temperature at the base of the electrode, the temperature at the electrode tip rises, and the electrode tip evaporates and is deformed. Therefore, optimal design of the electrodes is important for satisfying the range characteristics of the lamp. However, in the conventional electrode structure, designing was difficult because the range of optimal design was narrow.

[0003]

In such an electrode,
Since the temperature at the base of the electrode is high, there is a problem that the arc tube is damaged. In addition, since the tip of the electrode evaporates and deforms, the arc tube is blackened during the movement, and the luminous flux maintenance rate is reduced, and
There has been a problem that the lamp goes out due to a rise in the lamp voltage.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a high wattage metal halide lamp capable of improving the lamp life.

[0005]

SUMMARY OF THE INVENTION The metal halide lamp of the present invention has an electrode at both ends and an arc tube in which a rare earth metal halide is sealed together with mercury and a rare gas. In a metal halide lamp of 400 W or more, the electrode includes an electrode rod, an electrode coil fixed to a tip of the electrode rod, and a coil fixed to a tip of the electrode coil. Is wound in one layer and inserted and fixed to the electrode coil, and the other end is wound in two layers and provided so as to protrude from the electrode coil. Further, the metal halide lamp of the present invention is a metal halide lamp having an electrode at both ends and having an arc tube in which a rare earth metal halide is sealed together with mercury and a rare gas, and having a rated power of 400 W or more. The electrode includes an electrode rod, a coil, and an electrode coil wound around and fixed to the coil. The coil has one end wound around one layer, and a tip end of the electrode rod, The distal end surface of the electrode rod and the distal end surface of the coil are inserted and fixed with a distance of not less than the diameter of the electrode rod, and the other end is wound in two layers and provided so as to protrude from the electrode coil. Have been.

[0006]

The electrode tip has a coil shape to increase the surface area, prevent the electrode tip from evaporating due to the temperature rise of the electrode tip, and reduce the heat capacity, so that no bright spots are generated and the electrode tip evaporates. As a result, it is possible to prevent the luminous flux maintenance ratio from being lowered due to blackening of the arc tube during the movement and from being extinguished due to an increase in the lamp voltage. Further, heat conduction to the electrode base is reduced, and damage to the arc tube can be prevented.

[0007]

As shown in FIG. 2, a 1000 W rated metal halide lamp according to an embodiment of the present invention includes an arc tube 1 made of quartz glass and provided with electrodes 2a and 2b at both ends. In the arc tube 1, thallium iodide, cesium iodide and dysprosium iodide are sealed together with mercury and argon as a starting rare gas. The arc tube 1 is attached to and supported by a support wire 4 via arc tube support plates 3a and 3b. The arc tube support plate 3b is insulated from the support wire 4 by an insulator. The arc tube 1 is provided in the outer tube 5, and power is supplied to the arc tube 1 by the support wire 4 and the connection wires 6a and 6b. Nitrogen is sealed in the outer tube 5, and a base 7 is fixed to an end of the outer tube 5.

As shown in FIG. 1, the electrodes 2a and 2b comprise a coil 8, an electrode coil 9 and an electrode rod 10,
Has one end wound on one layer and the other end wound on two layers. One end of the electrode coil 9 is inserted into the tip of the electrode rod 10 for supporting the electrode, and one end of the coil 8 is inserted into the other end of the electrode coil 9. The other end of the coil 8 protrudes from the other end of the electrode coil 9. The coil 8 is made of tungsten having a wire diameter of 0.4 mm and is formed by winding the first layer 9 turns and the second layer 4 turns.
The electrode coil 9 is made of tungsten having a wire diameter of 0.8 mm, and the first and second layers are wound for seven turns. The electrode rod 10 is made of tungsten having a wire diameter of 1.8 mm.

When the lamp having the above-described structure was manufactured and subjected to a life test, even after lighting for 6000 hours, there was no deformation of the electrodes, the luminous flux maintenance factor was 80% or more, and problems such as breakage of the arc tube occurred. It was confirmed that stable travel characteristics could be obtained without occurrence.

Next, another embodiment of the present invention will be described. A metal halide lamp according to another embodiment of the present invention has a structure similar to that of the above embodiment, but has the following structure with respect to the electrodes. That is, as shown in FIG.
It is composed of a coil 11, an electrode coil 12, and an electrode rod 13,
The coil 11 has one end wound on one layer and the other end wound on two layers. The tip of the electrode rod 13 for supporting the electrode is inserted into one end of the coil 11, the tip surface of the electrode rod 13 and the tip surface of the coil 11 are separated by 2.5 mm, and the same end of the coil 11 One end of the electrode coil 9 is inserted into and fixed to the portion. The other end of the coil 11 is provided so as to project from one end of the electrode coil 12. The coil 11 is made of tungsten having a wire diameter of 0.4 mm.
The layer is formed by winding 9 turns and the second layer by 4 turns. The electrode coil 12 is made of tungsten having a wire diameter of 0.8 mm, and the first and second layers are wound for seven turns. The electrode rod 13 is made of tungsten having a wire diameter of 1.0 mm.

A lamp having such a structure was manufactured and subjected to a life test. Even after lighting for 6000 hours, the electrodes were not deformed, the luminous flux maintenance factor was 80% or more, and the arc tube was damaged. The same effect as that of the above-mentioned one example, in which a stable travel characteristic can be obtained without occurrence of a crack, was confirmed.

The conventional electrode structure, that is, a lamp having an electrode in which an electrode coil is wound around the tip of the electrode rod and the tip of the electrode rod protrudes from the electrode coil, is used for the wire diameter of the electrode rod. When the wire diameter of the electrode rod was 1.63 mm or less, there was no damage to the arc tube, but the electrode tip evaporated and deformed in several hundred hours, causing the lamp voltage to rise and disappear. In addition, it was confirmed that when the wire diameter of the electrode rod exceeded 1.63 mm, the temperature at the base of the electrode was increased and breakage occurred.

In each of the embodiments described above, the case of a metal halide lamp of 1000 W has been described. However, the present invention can achieve the same effect by using a lamp of 400 W, 2000 W or the like.

[0014]

As described above, according to the present invention, there is no deformation of the electrode, the luminous flux maintenance factor is 80% or more, and a stable range characteristic can be obtained without causing problems such as breakage of the arc tube. A long-life metal halide lamp can be provided.

[Brief description of the drawings]

FIG. 1 is an enlarged front view of a main portion of a metal halide lamp according to an embodiment of the present invention;

FIG. 2 is also a front view

FIG. 3 is an enlarged front view of a main part of a metal halide lamp according to another embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arc tube 2a, 2b Electrode 5 Outer tube 8 Coil 9 Electrode coil 10 Electrode rod

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Sho 58-188891 (JP, U) Japanese Utility Model Sho 56-165355 (JP, U) Japanese Patent Publication No. 48-22116 (JP, B1) (58) Field (Int.Cl. ⁷ , DB name) H01J 61/073 H01J 61/34

Claims (2)

(57) [Claims] A metal halide lamp having a power rating of 400 W or more, comprising an arc tube in which both ends are provided with electrodes and a halide of a rare earth metal is enclosed together with mercury and a rare gas. An electrode rod, an electrode coil fixed to the tip of the electrode rod, and a coil fixed to the tip of the electrode coil, the coil having one end wound in a single layer, A metal halide lamp, wherein the other end is wound in two layers and is provided so as to protrude from the electrode coil. 2. A metal halide lamp having an electrode at both ends and having an arc tube in which a rare earth metal halide is sealed together with mercury and a rare gas, and having a rated power of 400 W or more. An electrode rod, a coil, and an electrode coil wound around and fixed to the coil. The coil has one end wound around a single layer, and the tip of the electrode rod is The distal end face and the distal end face of the coil are inserted and fixed at a distance of not less than the diameter of the electrode rod, and the other end is wound in two layers and provided so as to protrude from the electrode coil. A metal halide lamp characterized by the following.