JPH03147242A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To extinguish Na, Li as the impurity during the lighting initial time in a metal halide lamp not using NaI, LiI by providing a contactless conductor in the periphery of a light emitting tube. CONSTITUTION:The iodide of more than one kind of rare earth metal, Sc, Tl, In, Sn and Al and the alkali metal iodide of more than one kind of K, Rb and Cs as the main light emitting material are sealed with mercury and argon in a light emitting tube 4 comprising a pair of electrodes 7, 8 and made of quartz glass. A contactless conductor 10 made of tungusten wire of which diameter is 0.2mm is wound around of the light emitting tube 4 so as to contact to the center of the light emitting tube 4 in the periphery of the light emitting tube 4, and both ends thereof are electrically insulated through glass bases 11 and fixed to supports 6. Na and Li contaminated as the impurity harmful to the color characteristic are thereby extinguished within a short time in the lighting initial time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a metal halide lamp with stable color characteristics that does not contain Nap or Lit as a luminescent substance.

[Conventional technology]

Metal halide lamps are currently widely used because of their high efficiency and high color rendering properties, and recently even smaller metal halide lamps have come to be used most often for lighting purposes.

In general, metal halide lamps contain Na r , Li I , K I , Rb in addition to mercury and argon.
By appropriately combining alkali metal iodides such as I, CsI, rare earth metal iodides, Sc1in, Tl, Sn, etc., a lamp with a stable arc state can be obtained.

By the way, recent metal halide lamps are highly efficient,
Many products contain Nal or Lil for the purpose of lowering the color temperature, and 5c-N is especially popular as a type containing Nal.
There are a-type lamps, Tl-Na-In type lamps, and Dy-Tl-Na type lamps, which account for most of the lamps currently on the market.

However, the color rendering index (R,) of such Nal-filled lamps is mostly around 65, and even good ones have a limit of around 80, and furthermore, the color rendering index (R,) is limited to around 80 among the special color rendering indexes. Since R9 is less than 0, there is a limit to the color characteristics of these lamps.

In addition, in a lamp filled with such Nal,
Proximity conductors such as pillars, lead wires, and support plates
It has been known that this N
The loss of a causes a rise in lamp voltage and poor starting. As a countermeasure to this problem, methods have been implemented such as separating the lead wire from the arc tube or making it thinner, and even making the lamp base double-sided. However, by taking such measures to prevent Na loss, a problem arises in that the structure of the lamp becomes complicated.

Further, in metal halide lamps, it is common to use a commutating pole to improve starting, but it is difficult to use an external commutating pole for the same reason of Na loss. Therefore, a commutative pole is usually provided within the arc tube, but in this case, there is a possibility that an electrolytic phenomenon may occur due to discharge between the main pole and the commutative pole, so there are problems such as restrictions on the lighting position.

On the other hand, rare earth metal iodides were similarly used. yNd
There is a metal halide lamp containing a -Cs-based iodide. This is a lamp that does not use NaT or Lil, and does not emit strong light like Na, so it can utilize the excellent characteristics of ay-Nd, and both Rs + R9 are 90%.
High color rendering properties are obtained in the front and back.

Further, the above-mentioned problems due to Na disappearance do not occur.

[Problem to be solved by the invention]

However, other KIRbls without using the above Nal and Lil
In metal halide lamps filled with alkali metal iodides such as CSL, Na and Li may be contained as impurities in the sealed alkali metals.
Emission peaks of these metals may be seen in the early stages of lighting. For a lamp aiming at high color rendering, such light emission is not only useless, but also harmful as it causes variations in characteristics.

The present invention was made to solve the above-mentioned problems in conventional metal halide lamps that do not use Nal or Lil.
It is an object of the present invention to provide a metal halide lamp which can easily remove Na and Li mixed as impurities of Cs iodide and has stable color characteristics.

[Means and effects for solving the problems] In order to solve the above-mentioned problems, the present invention provides a quartz glass arc tube equipped with a pair of electrodes, which contains mercury.

Rare earth metal Sc as the main luminescent material along with argon,
In addition to at least one type of iodide of Tl, In, Sn, and Al, at least one type of alkali metal iodide of K, Rh, and Cs is sealed, and impurities Na and Li are removed from the outer periphery of the arc tube. A metal halide lamp is constructed by providing a nearby conductor for this purpose.

By providing a proximal conductor on the outer periphery of the arc tube in this way, Na mixed as an impurity of one or more alkali metal iodides of Rb and Cs can be removed from the enclosed space.
Alternatively, Li can be easily eliminated at the initial stage of lighting, thereby significantly improving R□R1, etc., and easily realizing a metal halide lamp with stable color characteristics.

〔Example〕

Next, an example will be described. FIG. 1 is a diagram showing an embodiment of the metal halide lamp according to the present invention, and is a diagram showing an embodiment of the metal halide lamp according to the present invention.
A 250W l-Cs lamp is shown. In the figure, ▪ is an outer tube of a metal halide lamp, and a stem 2 is sealed at one end of the outer tube 1, and a base 3 is fixedly attached. 4 is an internal volume 5 c made of quartz glass
In the arc tube c, the lead-in wire 5 is sealed through the stem 2.
It is supported by a support 6 fixed to one end of the .

At both ends of the arc tube 4, tungsten electrodes 7.8 are placed facing each other. In the arc tube 4, there are 13
■Water jL 50 Torr with argon, dysprosium iodide (DyId5■, cesium iodide (Cs
I) 2 mg of thallium iodide (T11) is enclosed. One electrode 7 of the arc tube 4 configured in this way is connected to the support 6, the other electrode 8 is connected to the lead-in wire 9 which is sealed through the stem 2, and further connected to the center of the arc tube 4. A proximate conductor 10 made of a tungsten wire with a diameter of 0.2 nm is wound around the lamp, and both ends of the proximal conductor 10 are electrically insulated via glass beads 11 and welded to the support 6 to form a lamp. Note that 12 is Genta.

Figures 2 (8) and (B) show the above embodiment of the present invention in which a proximal conductor is provided at the center of the arc tube for the purpose of removing Na and Li components, especially Na components, mixed and sealed as impurities. Fig. 3 is a diagram showing the spectral distribution characteristics of a metal halide lamp immediately after lighting and after one hour of lighting, and Fig. 3^ (old) is a comparative example of a metal halide lamp having the same structure except for the proximity conductor. Immediately after lighting and 1
It is a figure which shows the spectral distribution characteristic after lighting for a time.

As can be seen from Figure 3, (B) above, in the lamp of the comparative example, the spectral distribution characteristics after lighting for 1 hour were almost the same as those immediately after lighting, and Na emission (589 nm) was still observed.
m) is seen. In contrast, the second prisoner.

As can be seen from fBl, when the proximal conductor according to the present invention was provided, it was confirmed that the Na component mixed into the lamp was removed by lighting it for about one hour. Further, FIG. 4 is a diagram showing changes in the chromaticity point distribution in this example, where A shows the distribution immediately after lighting, and B shows the distribution after lighting for one hour. Note that B and L are blackbody loci. From this change in the chromaticity point distribution, it was confirmed that the color variation was reduced and the color characteristics were improved because the color distribution was concentrated on the black body locus.

Next, the distance between the proximal conductor and the outer circumferential wall of the arc tube was varied and the change in Na luminescence output after lighting for one hour was measured, and the results shown in FIG. 5 were obtained. This fifth
As can be seen from the figure, it has been found that if the case where the Na emission output becomes less than half is effective, it is necessary to reduce it to about 15 am or less.

As described above, in a metal halide lamp that does not use Na or Li as an ionizing compound, by providing a proximal conductor near the outside of the arc tube, Na or Li mixed in as impurities harmful to color characteristics can be removed in a short time. Can be removed.

In the above embodiment, a tungsten wire was simply wound around the arc tube as the proximate conductor without applying a potential, but the proximal conductor may be placed away from the arc tube, or the Na.

A potential may be applied to a nearby conductor for removing Li impurities so that it also serves as an external commutative pole. When the adjacent conductor is configured to double as a counter pole in this way, the insulation between the lamp electrodes when a pulse voltage of 4000 V is applied, as shown in Figure 6, is lower than in the comparative example in which no adjacent conductor is provided. As can be seen from the diagram showing the breakdown time distribution, the adjacent conductor can play the role of an external counterpole and improve the starting characteristics.

Further, as the conductor used for the proximity conductor, heat-resistant conductors or semiconductors other than tungsten can also be used.

〔Effect of the invention〕

As described above based on the embodiments, according to the present invention, Rb is used to stabilize the arc in a metal halide lamp aiming at high color rendering properties.

Na and Li, which are mixed as impurities in the Cs iodide, are easily removed because of the provision of the adjacent conductor, resulting in a metal halide lamp with stable color characteristics.

[Brief explanation of the drawing]

Figure 1 shows an example of the metal halide lamp according to the present invention, and Figure 2 (B) shows the spectral distribution characteristics of the metal halide lamp according to this example immediately after lighting and after lighting for 1 hour. Figure 3 W (81 is a diagram showing the spectral distribution characteristics immediately after lighting and after lighting for one hour in a comparative example without a nearby conductor; Figure 4 is the chromaticity point distribution of the metal halide lamp according to this example. FIG. 5 is a diagram showing changes in Na luminescence output when the distance between the proximal conductor and the outer circumferential wall of the arc tube is changed, and FIG. It is a diagram showing the distribution of dielectric breakdown time in the lamp. In the figure, 1 is an outer tube, 4 is an arc tube, 6 is a support body,
8 indicates a tungsten electrode, and IO indicates a nearby conductor.

Claims (1)

[Claims] 1. In a quartz glass arc tube equipped with a pair of electrodes,
Rare earth metals, along with mercury and argon, are the main luminescent materials.
In addition to at least one kind of iodide of Sc, Tl, In, Sn, and Al, at least one kind of alkali metal iodide of K, Rb, and Cs is sealed, and impurities Na and Li are added to the outer periphery of the arc tube. A metal halide lamp characterized by having a nearby conductor for removal. 2. The proximity conductor is 15 mm away from the outer peripheral wall of the arc tube.
2. The metal halide lamp according to claim 1, wherein the metal halide lamp is insulated and arranged within the confines of the metal halide lamp. 3. The metal halide lamp according to claim 1, wherein the proximal conductor is configured to also serve as an external commutative pole.