JPH05135739A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To provide a light source having a luminescence spectrum over the whole visible area, an excellent color rendering property, and a long life in a single tube type metal halide lamp. CONSTITUTION:DyI3, NdI3, CsI are sealed in a metal halide lamp sealed with mercury and rare gas and having the lamp power per arc length of 20W/mm or above so that their total weight is set to 1mg/cc or above, the weight of CsI is set to 15-50% of all the iodides, and the weight ratio between DyI3 and NdI3 is set to 0.2<=NdI3/DyI3<=5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal halide lamp used for general lighting, optical equipment and the like.

[0002]

2. Description of the Related Art In recent years, metal halide lamps are widely used for general lighting such as store lighting and road lighting, and the demand for them is expanding as lighting for automobiles or light sources for optical equipment. An example of the metal halide lamp described above will be described below with reference to the drawings.

FIG. 1 shows the structure of a single tube metal halide lamp. In FIG. 1, 1 is a light emitting part of a quartz glass arc tube, 2 is a tungsten electrode installed via a molybdenum foil, 3 is a sealing part obtained by hermetically sealing the molybdenum foil,
4 is an external lead wire.

The operation of the metal halide lamp having the above structure will be described below.

In the metal halide lamp, the metal halide added together with mercury and a noble gas exists as a liquid near the arc tube wall during lighting, while the partially evaporated metal halide vapor forms metal atoms at the center of the arc. Dissociated into halogen atoms, the metal vapor is excited by an arc and emits a spectrum peculiar to the metal. Therefore, the metal halide lamp has an advantage that it is superior in luminous efficiency and color rendering property to the high pressure mercury lamp.

As a metal iodide, Tl-Na-In, S
Many metal halide lamps containing c-Na and Dy-Tl have been put into practical use.

[0007]

Generally, in this type of metal halide lamp, the emission characteristics of the lamp are determined by the vapor pressure of the enclosed metal halide. That is,
In order to obtain the emission spectrum peculiar to the enclosed metal, it is necessary to raise the temperature of the coldest part of the arc tube and increase the vapor pressure of the metal halide. Therefore, in the metal halide lamp, the tube wall load is properly designed so that the desired coldest spot temperature can be obtained. Further, usually, a method of applying a heat insulating film to the outer surface of the arc tube near the coldest spot is adopted.

By the way, in order to use a metal halide lamp of this kind as a light source for an OHP, a slide projector and a projection type liquid crystal display, a single tube type structure naturally leads to a double tube type lamp having an outer tube. The coldest spot temperature decreases. Tl-Na-In, Sc-Na, Dy-T
In the conventional metal halide lamp containing 1 or the like, if the lamp structure is a single tube structure, the coldest spot temperature is lowered as described above, and the vapor pressure of the metal halide is lowered.

As a result, the emission spectrum intensity of the added metal is lowered and the color rendering of the lamp is lowered. Further, in these conventional metal halide lamps, when the tube wall load of the metal halide lamp is increased for the purpose of increasing the vapor pressure of the added metal halide and improving the color rendering property, the added metal and the arc tube constituent material react rapidly, and the luminous flux There is a problem that the life is shortened due to deterioration and rupture of the arc tube.

In view of the above problems, it is an object of the present invention to provide a single-tube metal halide lamp which has an emission spectrum distributed in the entire visible range and is excellent in color rendering and has a long life.

[0011]

In order to solve the above problems, the present invention provides mercury, a rare gas for starting, cesium iodide (CsI) and a disodium iodide in a transparent container having a pair of electrodes. Siumu (DyI ₃₎ and enclosing the neodymium iodide (NdI _3), in single tube type metal halide lamp lamp power per distance between the electrodes is 20W / mm or more, the iodide dysprosium, wherein neodymium iodide , The total weight of the cesium iodide is 1 mg / c
c, the weight of cesium iodide in the total weight of iodide is 15% or more and 50% or less, and the weight ratio of dysprosium iodide to neodymium iodide is 0.2 ≦.
It constitutes a metal halide lamp which is characterized in that the NdI ₃ / DyI ₃ ≦ 5.

[0012]

According to the present invention, by adding dysprosium iodide, neodymium iodide, and cesium iodide to a single-tube type metal halide lamp, and further appropriately setting the composition and the amount of inclusion, the emission spectrum in the entire visible region is obtained. It is possible to obtain a light source having excellent color rendering properties. Also,
The reaction between the arc tube constituent material and the added metal is less likely to proceed, and a longer life can be realized.

[0013]

【Example】

(Embodiment 1) A metal halide lamp according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a single tube type quartz glass metal halide lamp arc tube, 1 is a quartz glass arc tube light emitting part, 2 is a tungsten electrode, 3
Is a sealing portion in which molybdenum foil is hermetically sealed, and 4 is an external lead wire.

The arc tube light-emitting portion 1 has a substantially spheroidal shape and has a central maximum inner diameter of 8.0 mm and an internal volume of 0.5 cc.
The distance between the electrodes, that is, the arc length is 6.0 mm.
0.5mg is DyI ₃ in the light-emitting tube, NdI ₃ is 0.2m
g, CsI of 0.3 mg, mercury as a buffer gas of 10.0 mg, and Ar as a starting rare gas of 200 Torr. The metal halide lamp having the above structure was incorporated into the optical system shown in FIG. 2 to evaluate the emission spectrum. Lamp power 150W, lamp voltage 90V,
It was lit with a lamp current of 1.7A. The power per arc length is 25 W / mm.

Reference numeral 5 is a metal halide lamp, 6 is a condenser mirror, 7 is a projection lens system, and 8 is a light receiving surface. The spectral distribution at the center of the light receiving surface is shown in FIG. 3 together with the case where the inclusion is DyI ₃ -TlI-CsI.

In FIG. 3, curve 1 is a lamp according to the present invention, and curve 2 is a DyI ₃ -TlI- prepared for comparison.
It is an emission spectrum of a CsI system lamp. These two lamps were all the same except for the enclosure. Further, FIG. 3 shows a light emission spectrum as a curve 3 when the lamp according to the present invention is turned on with a lamp power of 100 W, that is, an electric power per arc length of 17 W / mm.

Comparing curve 1 and curve 2, DyI ₃ , N
It can be seen that in the lamp of the present invention in which a predetermined amount of dI ₃ and CsI are encapsulated, abundant light emission peculiar to the encapsulated metal is obtained from the near ultraviolet region to the entire visible region, and the color rendering property is significantly improved. Further, comparing the curves 1 and 3, in order to improve the color rendering, the power per arc length is 21 W / mm.
It can be seen that it is necessary to increase the lamp load by increasing it.

When the emission spectrum was measured by continuously changing the lamp power per arc length, it was found that there was no practical problem if the power per arc length was 20 W / mm or more. Since the metal halide lamp according to the present invention has an emission spectrum distributed in the entire visible region,
When used as a light source for a projection type liquid crystal display or a projection type liquid crystal display, the screen has excellent brightness and color characteristics as compared with a conventional metal halide lamp.

The reason why the total weight of dysprosium iodide, neodymium iodide and cesium iodide enclosed in the metal halide lamp having the above-mentioned structure is 1 mg / cc is as follows. Most of the iodide is a liquid and exists in the vicinity of the coldest point during the operation of the lamp, and a part of the iodide is evaporated and exists in the discharge space as a gas.

Considering the case where the total weight of iodide is increased, liquid iodide is excessively present and a part of the liquid iodide comes into contact with the inner wall of the lamp whose temperature is higher than the coldest spot. become. Then, even at that place, the liquid evaporates, and the vapor pressure of iodide rises higher than in the state before increasing iodide. As a result, the emission intensity of the metal is increased and the color rendering is improved. As a result of conducting an experiment with various amounts of inclusion, D
It was found that there was no practical problem if the total weight of the enclosed yI ₃ , NdI ₃ , and CsI was 1 mg / cc or more. However, the internal volume of the lamp needs to be 0.4 cc or more and 2.0 cc or less. When the internal volume is less than 0.4 cc, when the lamp is turned on, liquid iodide adheres to the entire inner surface of the lamp, resulting in a significant decrease in brightness. When the internal volume is larger than 2.0 cc, the area of the coldest spot becomes large, so iodide must be further increased.

Further, the weight ratio of NdI ₃ / DyI ₃ 0.2
It was found that if it is less than the above range, the brightness of the light emitting arc is lowered and the efficiency is lowered, which is not preferable. Also NdI ₃ / D
If the weight ratio of yI ₃ exceeds 5, the continuous emission intensity decreases in the emission spectrum distribution, and conversely, the emission intensity of mercury increases and the color rendering property deteriorates.

On the other hand, among the enclosed iodides, cesium iodide
Works to stabilize the arc and DyI ₃And NdI₃Vapor pressure of
Has the effect of increasing. In other words, enclose cesium iodide
To stabilize the arc and at the same time DyCs
I_FourThe desired emission spectrum is formed by forming a complex iodide such as
Will be obtained. However, encapsulating a large amount of CsI
And iodide adhere to the inner surface of the arc tube, resulting in a decrease in brightness. Fruit
From the test results, cesium iodide is practically considered to be the weight of all iodides.
Must be 15% or more and 50% or less of the amount
I understood.

From the life evaluation result, it was confirmed from the life evaluation result that the metal halide lamp according to the present invention had no damage or leak and had a small degree of devitrification.

(Example 2) Similar to Example 1 in FIG. 1, an experiment was conducted using a metal halide lamp having a substantially spheroidal shape, a central maximum inner diameter of 12.0 mm, and an internal volume of 1.0 cc. In the inter-electrode distance is 7.5 mm, the arc tube enclosed amount is DyI ₃ 0.3 mg, is NdI ₃ 0.7 mg, CsI is 0.2 mg, the mercury 15 mg, Ar is defined as 100 Torr.

A metal harad lamp having the above structure
A lamp power of 250 W, which is incorporated in the optical system shown in FIG.
Lights up with a lamp voltage of 90 V and a lamp current of 2.7 A, and emits light.
The spectrum was evaluated as in Example 1. Per arc length
Power of 33 W / mm. The result is also for this lamp
As in the case of Example 1, a good emission spectrum was obtained.
The color rendering properties could be improved. Same for life
It was confirmed that it was 2500 hours or more. Example 1
Lamp power per arc length is 20 W / mm or less
Above, DyI for inclusion₃, NdI₃, CsI total weight
1 mg / cc or more, of which CsI is 15% or more 5
0% or less, the weight ratio of rare earth is 0.2 ≦ NdI ₃/ DyI₃
It has been found that it is necessary to satisfy ≦ 5. The internal volume is 0.4
It was necessary to set it to cc or more and 2.0 cc or less.

Further, based on the above two examples, experiments were conducted on the shape of the lamp, and it was found that the effect of the present invention was remarkably exhibited when the lamp had the following shape. That is, in a substantially spheroidal arc tube, the maximum inner diameter of the plane perpendicular to the arc axis is a, and the inner diameter on the arc axis is b.
Both are 5 mm to 15 mm. This is because if the inner diameter of the arc tube is too small, the temperature on the inner surface rises excessively, devitrification of the glass occurs, and the life of the lamp shortens.On the contrary, when the inner diameter increases, the coldest spot temperature decreases and the color rendering This is because it will decrease.

From the viewpoint of lamp life, it is desirable not to increase the lamp power more than necessary. This is because increasing the lamp power means increasing the lamp temperature, and excessive temperature increase leads to a decrease in lamp life. The lamp power should be set in consideration of the required life, and the maximum value of the lamp power was 300 W in order to obtain the life of 2500 hours in the lamp of the present invention.

[0028]

As described above, according to the present invention, mercury, a rare gas for starting, cesium iodide (CsI) and dysprosium iodide (DyI) are contained in a light-transmissive container having a pair of electrodes.
₃ ) and neodymium iodide (NdI ₃ ) are enclosed, and the dysprosium iodide, the neodymium iodide, and the iodine are contained in a single-tube metal halide lamp having a lamp power per electrode distance of 20 W / mm or more. The total weight of cesium iodide is more than 1 mg / cc, the weight of the cesium iodide in the total weight of iodide is 15% or more and 50% or less, and the weight ratio of the dysprosium iodide and the neodymium iodide is 0. with a structure in which a _{.2 ≦ NdI 3 / DyI 3 ≦} 5, it is possible to obtain an excellent light source color rendering has an emission spectrum in the entire visible range. Also, the reaction between the arc tube constituent material and the added metal is less likely to proceed, and a longer life can be realized.

[Brief description of drawings]

FIG. 1 is a metal halide lamp arc tube according to a first embodiment of the present invention.

FIG. 2 Optical system used for evaluation of emission spectrum

FIG. 3 is an emission spectrum of a metal halide lamp according to a conventional example and Example 1 of the present invention.

[Explanation of symbols]

 1 Quartz glass arc tube central light emitting part 2 Tungsten electrode 3 Molybdenum foil sealing part 4 External lead wire 5 Metal halide lamp 6 Condensing mirror 7 Projection lens 8 Light receiving surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideto, 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A mercury to the pair of electrodes transparent envelope provided with the, starting rare gas, cesium iodide (CsI) and iodide dysprosium (DyI ₃₎ and neodymium iodide (NdI ₃₎ enclosed In the single-tube metal halide lamp having a lamp power per electrode distance of 20 W / mm or more, the total weight of the dysprosium iodide, the neodymium iodide, and the cesium iodide is 1 mg / c.
c, the weight of cesium iodide in the total weight of iodide is 15% or more and 50% or less, and the weight ratio of dysprosium iodide to neodymium iodide is 0.2 ≦.
A metal halide lamp which is characterized in that the NdI ₃ / DyI ₃ ≦ 5