JP3159636U - Mercury-free metal halide lamp - Google Patents

Abstract

[PROBLEMS] To stably obtain a fashionable luminescent color with strong whiteness and bluishness without encapsulating mercury, which is an environmentally hazardous substance, and has a luminous flux and a long life and good color rendering that do not impede practical use. Obtain a mercury-free metal halide lamp. Inside a luminous tube having a pair of electrodes, at least Na (sodium) halide, Sc (scandium) halide, and Ga (gallium) halide as main luminescent materials together with a rare gas. And a metal halide lamp having a configuration substantially free of mercury. [Selection] Figure 2

Description

The present invention relates to a mercury-free metal halide lamp in which a suitable kind of metal halide (metal halide) is enclosed together with a rare gas without containing mercury in an arc tube having a pair of electrodes, particularly as an automobile headlamp. The present invention relates to a mercury-free metal halide lamp suitable for use. As shown in FIG. 1, generally, the arc tube of such a lamp has a pair of electrodes 2 made of tungsten facing each other in a hollow light emitting portion of an arc tube 1 formed of a quartz glass tube, A metal foil 3 made of molybdenum is welded to the base end portion of the electrode 2, and an external lead wire 4 is connected to the metal foil 3. The portion centered on the metal foil 3 is welded into the seal portions at both ends of the quartz glass tube forming the arc tube 1 so that the air-tightness in the hollow light-emitting portion of the arc tube 1 is maintained. In the hollow light emitting part, an appropriate kind of metal halide is enclosed together with a rare gas.

If the electrode 2 and the quartz glass are strongly welded, a crack may occur in the quartz glass from the electrode 2 due to the difference in the thermal expansion coefficient between the electrode 2 and the quartz glass when the lamp is turned on. As shown in FIG. 1, the tungsten coil 5 is wound around the electrode 2 portion to which the quartz glass is welded, thereby preventing strong welding between the electrode 2 and the quartz glass and preventing cracks from the electrodes. .

In recent years, high-efficiency metal halide lamps are being adopted for automobile headlamps. Many of these metal halide lamps contain mercury, which is an environmentally hazardous substance. Mercury has been widely used in this field because it has a large elastic impact cross section with electrons and is very effective in forming a lamp voltage. However, as awareness of environmental issues has increased, mercury-free metal halide lamps that do not enclose mercury, which is an environmentally hazardous substance, have been developed, and some have already been adopted for automobile headlamps.

On the other hand, customer needs for automobile headlamps are in various emission colors. Among them, customers are particularly interested in metal halide lamps for automotive headlamps with strong whiteness and bluishness and fashionable luminescent colors. However, the mercury-free metal halide lamp lacks the spectrum (435 nm) in the blue region of mercury, so it has a brighter white and bluish emission color than a metal halide lamp containing mercury. The current situation is difficult.

In a conventional mercury-free metal halide lamp, mercury is sealed by combining a first halide that is sealed for the main purpose of emitting light and a second halide that is sealed for the purpose of forming a voltage. I am trying to get a proper lamp voltage. Such a lamp is disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-66406.

In the lamp disclosed in Japanese Patent Application Laid-Open No. 2006-66406, a combination of Na (sodium) halide, Sc (scandium) halide and rare earth metal halide is selected as a main luminescent material to form a lamp voltage. Mg (magnesium), Fe (iron), Co (cobalt), Cr (chromium), Zn (zinc), Ni (nickel), Mn (manganese), Al (aluminum), Sb (antimony), Be ( One or a plurality of metal halides selected from beryllium), Re (rhenium), Ga (gallium), Ti (titanium), Zr (zirconium) and Hf (hafnium) are used.
JP 2006-66406 A

In the lamp as disclosed in the above-mentioned patent document, the emission color of the lamp can be changed to some extent by appropriately adjusting the amount of the main luminescent substance, that is, the halide of Na, Sc and rare earth metal. Such a combination of luminescent materials is suitable for stably obtaining a relatively warm light color, but it is difficult to stably obtain a fashionable luminescent color with strong whiteness and blueness. There was found. The problem to be solved by the present invention is that, without enclosing mercury, which is an environmentally hazardous substance, it is possible to stably obtain a fashionable luminescent color with strong whiteness and bluishness. It is to enable a mercury free metal halide lamp with a long life and good color rendering.

  As a result of various investigations and repeated experiments to solve the above-mentioned problems, the inventors have found that inside the arc tube having a pair of electrodes, a rare gas and a sodium (Na) halide as the main luminescent substance, and Sc ( By combining a combination of scandium) and Ga (gallium) halides, and adjusting the amount of these encapsulated substances as appropriate, a bright and bright blue light emission color is achieved. It has been found that a mercury-free metal halide lamp that can be obtained stably, has a luminous flux that does not interfere with practical use, has a long life, and has good color rendering properties.

In this type of lamp, the Ga halide inside the arc tube is also described in the above-mentioned patent document. However, in the invention disclosed in the same patent document, the Ga halide is a lamp. It is possible to select a substance for forming a voltage, and there is no disclosure or suggestion of using Ga halide together with Na halide and Sc halide as a main luminescent substance as in the present invention.

  In addition, as in the present invention, the inside of the arc tube is sealed with a combination of rare earth gas and Na halide, Sc halide, and Ga halide as the main luminescent material. It was confirmed that a strong and fashionable luminescent color could be stably obtained, but in such a lamp, the metal foil made of Mo turned black after several hundred hours of lighting and then Mo foil It was also confirmed that a crack occurred in the quartz glass from the end of the tube, and in a severe case, the enclosed material inside the arc tube was ejected to the outside and could not be lit. This phenomenon is because the heat-resistant temperature of Mo to Ga is as low as about 300 ° C., and Ga and Mo foil react with each other, resulting in a large difference in thermal expansion coefficient between quartz glass and Mo foil. I can guess it is the cause.

  As a result of repeated experiments to solve this problem, the inventors have encapsulated an appropriate amount of Tl (thallium) in addition to the encapsulated material, and as described above, the Mo foil turns black and cracks in the quartz glass. It has been confirmed that the phenomenon of the occurrence of the phenomenon can be effectively suppressed.

Therefore, first, the mercury-free metal halide lamp of the present invention includes a halide of Na (sodium) and a halide of Sc (scandium) as a main luminescent substance together with a rare gas, inside an arc tube having a pair of electrodes. It is characterized in that Ga (gallium) halide is at least enclosed.

Next, the Ga halide inclusion amount is 1.66 × 10 ⁻⁴ mg to 1.3 × 10 ⁻² mg per 1 mm ³ of the inner volume of the arc tube.

  The arc tube is characterized in that at least a halide of Tl (thallium) is enclosed.

Furthermore, the amount of the Tl halide sealed is 1.66 × 10 ⁻⁴ mg to 1.3 × 10 ⁻² mg per 1 mm ³ of the inner volume of the arc tube.

Further, in the light emission, at least a halide of Dy (dysprosium) and a halide of Nd (neodymium) are sealed.

Further, the enclosed amount of the Dy halide and the Nd halide is 3.3 × 10 ⁻⁴ mg to 1.6 × 10 ⁻² mg per 1 mm ³ of the inner volume of the arc tube. To do.

Further, the Nd halide content is 25% to 200% with respect to the Dy halide content.

According to the mercury-free metal halide lamp of the present invention, it is possible to produce a fashionable luminescent color with strong whiteness and bluishness without using the blue light emission of mercury, which is an environmentally hazardous substance, and a luminous flux that has no practical problem. And has an advantage of having a long life and good color rendering.

  Next, embodiments of the present invention will be described based on examples.

In the present invention, as shown in FIG. 1, for example, an arc tube 1 made of quartz glass having an internal volume of about 30 mm ³ to constitute a mercury-free metal halide lamp having a tube power of 35 W (tube voltage 42 V, current value 0.83 A). Is used. One end of an electrode 2 having a diameter of 0.3 mm and a total length of 7 mm made of tungsten containing 2% by weight of thorium oxide is connected to a metal foil 4 made of molybdenum, and the other end of the electrode 2 protrudes into the hollow light emitting portion of the arc tube 1. I'm clumsy. A coil 5 having a wire diameter of 0.05 mm is wound around the electrode 2, and the electrode 2 and the coil 5 are spot-welded using an inverter type welding machine. In the hollow light emitting part of the arc tube 1, together with a rare gas such as xenon gas as a buffer gas, in addition to Na halide and Sc halide as a main luminescent material, Ga halide contains an inner volume of 1 mm ^{3 of the} arc tube. It is enclosed in the range of 1.66 × 10 ⁻⁴ mg to 1.3 × 10 ⁻² mg per unit, and mercury is not enclosed.

In Example 1, Na halide, Sc halide, and Ga halide are encapsulated, but all are encapsulated for the purpose of contributing to light emission. Especially for Ga halides, encapsulating them as GaI ₃ activates the halogen cycle by increasing the amount of halogen in the hollow light emitting part, suppressing electrode scattering, and eventually blackening during the lifetime. It can be assumed that the progress of problems such as devitrification can be suppressed.

  In addition, Ga has a spectrum (403 nm, 417 nm) in the blue region, so it is extremely effective for obtaining a fashionable emission color with strong whiteness and blueness. FIG. 2 shows an emission spectrum of a mercury-free metal halide lamp in which Ga halide is enclosed.

In Example 1, the Ga halide was sealed in the range of 1.66 × 10 ⁻⁴ mg to 1.3 × 10 ⁻² mg per 1 mm ³ of the inner volume of the arc tube. This is because a fashionable luminescent color with strong whiteness or blueness cannot be obtained, and if it exceeds the upper limit, it deviates from the white range (D5500) of automobiles described in JIS.

  FIG. 3 shows the relationship between the amount of Ga halide enclosed and the chromaticity value xy on the white range of the D5500 automobile specified in the JIS standard.

  As is apparent from FIG. 3 above, when the amount of Ga halide enclosed is increased, the chromaticity value xy on the white range of the automobile of D5500 defined in the JIS standard moves in the blue direction. The effect of Ga halide on the chromaticity value xy enables a fashionable luminescent color with strong whiteness and blueness.

The mercury-free metal halide lamp described in Example 1 is further filled with a Dy halide and an Nd halide. The combined amount of the Dy halide and the Nd halide is 3.3 × 10 ⁻⁴ mg to 1.6 × 10 ⁻² mg per 1 mm ³ of the inner volume of the arc tube. Further, the amount of Nd halide enclosed with respect to the amount of Dy halide enclosed is in the range of 25% to 200%, and mercury is not enclosed.

  In Example 2, Na halide, Sc halide, Ga halide, Dy halide, and Nd halide are encapsulated, but all are encapsulated for the purpose of contributing to light emission. Yes. In particular, Dy halide and Nd halide have a large number of emission spectra, and are effective in obtaining a high average color rendering index (Ra). That is, the irradiated object can be seen in a natural color.

  In particular, mercury-free metal halide lamps do not enclose mercury, so there is no energy loss due to mercury, so rare earth materials with low vapor pressure, such as Dy and Nd, are more likely to emit light, which makes it more difficult than mercury-encapsulated metal halide lamps. Can get high Ra.

In Example 2, the combined amount of Dy halide and Nd halide was 3.3 × 10 ⁻⁴ mg to 1.6 × 10 ⁻² mg per 1 mm ³ of the inner volume of the arc tube. If the enclosed amount is less than the lower limit value, high Ra cannot be obtained, and conversely if it is more than the upper limit value, the total luminous flux is lowered.

  Further, in Example 2, the amount of Nd halide enclosed in the Dy halide is in the range of 25% to 200%. However, if this value is less than 25%, the devitrification of the quartz glass due to Dy during the lifetime. This is because, when the amount exceeds 200%, the blackening of quartz glass due to Nd during the lifetime significantly occurs.

  FIG. 4 shows the amount ratio of Dy halide and Nd halide and the degree of devitrification and blackening during the lifetime.

  As is clear from FIG. 4 above, when the encapsulation ratio of the Dy halide is increased, the devitrification of the quartz glass in the hollow light emitting portion is remarkably generated during the lifetime. Excessive devitrification during the lifetime is undesirable for lamps used in this type of optical system. Excessive devitrification may cause leakage due to expansion of the hollow light emitting part.

On the other hand, when the enclosure ratio of the Nd halide is increased, the devitrification of the quartz glass in the hollow light-emitting portion occurs remarkably during the lifetime. Excessive blackening during the lifetime is not preferable from the viewpoint of the luminous flux maintenance factor because it prevents light emission due to discharge generated between the electrodes in the hollow light emitting portion.

In addition to the mercury-free metal halide lamp described in Example 1 or Example 2, the halide of Tl is in the range of 1.66 × 10 ⁻⁴ mg to 1.3 × 10 ⁻² mg per 1 mm ³ of the inner volume of the arc tube. Encapsulated, not mercury.

  The mercury-free metal halide lamp described in Example 1 or Example 2 was subjected to a life test by a blinking cycle in accordance with JEL215 defined in JIS standards. It was confirmed that some of the ends on the connection side had turned black.

This is presumed that the heat resistance temperature of Mo with respect to Ga is as low as about 300 ° C., so that a chemical reaction between Ga and Mo metal foil has occurred. Furthermore, when this chemical reaction progresses, cracks are generated in the quartz glass due to the difference in thermal expansion coefficient with the quartz glass, and in the worst case, the encapsulated material inside the sphere is ejected to the outside and the lighting is turned off. It is done.

  The purpose of Tl halide encapsulation is to suppress the above-mentioned problems and to use a spectrum with high relative visibility (535 nm) possessed by Tl. In addition, it can be inferred that the Tl and Ga composite metal is formed in the hollow arc tube portion by enclosing Tl, and this suppresses the reaction with the metal foil made of Mo. This enables a longer-life mercury-free metal halide lamp.

In Example 3, the Tl halide was sealed in the range of 1.66 × 10 ⁻⁴ mg to 1.3 × 10 ⁻² mg per 1 mm ³ of the inner volume of the arc tube. The effect of suppressing the chemical reaction between the metal foil made of Ga and Mo due to the metal cannot be sufficiently expected. Moreover, it is because it will deviate from the white range (D5500) of the motor vehicle described in JIS when it exceeds more than an upper limit.

  FIG. 5 shows the relationship between the amount of halide of Tl and the chromaticity value xy in the white range of the D5500 automobile specified in the JIS standard.

  As is clear from FIG. 5, the chromaticity value xy on the white range of the automobile of D5500 defined in the JIS standard moves in the green direction when the amount of Tl halide enclosed is increased.

  The mercury-free metal halide lamp of the present invention can stably obtain a fashionable luminescent color with strong white and blue without enclosing mercury, which is an environmentally hazardous substance, This makes it possible to produce mercury-free metal halide lamps with good color rendering, and can be widely used in industry.

It is a vertical front view of the mercury-free metal halide lamp of the present invention. This is a spectral distribution of a mercury-free metal halide lamp in which Ga halide is enclosed. FIG. 6 is a relationship diagram of Ga halide content and chromaticity value xy on the white range of a D5500 automobile specified in JIS standards. FIG. 5 is a relationship diagram of the ratio of the amount of Dy halide and Nd halide enclosed and the degree of devitrification and blackening during the lifetime. It is a relationship diagram between the amount of halide of Tl and the chromaticity value xy on the white range of a D5500 automobile specified in JIS standard.

1 arc tube 2 electrode 3 metal foil 4 external lead wire 5 tungsten coil

Claims (8)

Inside the arc tube having a pair of electrodes, at least a rare gas and Na (sodium) halide, Sc (scandium) halide, and Ga (gallium) halide as the main luminescent material are enclosed. This is a mercury-free metal halide lamp. 2. The mercury according to claim 1, wherein the Ga (gallium) halide is enclosed in an amount of 1.66 × 10 ⁻⁴ mg to 1.3 × 10 ⁻² mg per 1 mm ³ of the inner volume of the arc tube. Free metal halide lamp. The mercury-free metal halide lamp according to claim 1 or 2, wherein a halide of Tl (thallium) is sealed in the arc tube. The mercury according to claim 3, wherein the amount of Tl (thallium) halide enclosed is 1.66 × 10 ⁻⁴ mg to 1.3 × 10 ⁻² mg per mm ³ inner volume of the arc tube. Free metal halide lamp. The mercury-free metal halide lamp according to any one of claims 1 to 4, wherein a halide of Dy (dysprosium) and a halide of Nd (neodymium) are enclosed in the light emission. The enclosed amount of the halide of Dy (dysprosium) and the halide of Nd (neodymium) is 3.3 × 10 ⁻⁴ mg to 1.6 × 10 ⁻² mg per 1 mm ³ inner volume of the arc tube. The mercury-free metal halide lamp according to claim 5. 7. The mercury-free metal halide lamp according to claim 6, wherein the amount of Nd (neodymium) halide enclosed is 25% to 200% with respect to the amount of Dy (dysprosium) halide enclosed. The mercury-free metal halide lamp according to any one of claims 1 to 7, wherein the mercury-free metal halide lamp is used for an automobile headlamp.

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