JP2001102001A - Short arc type metal halide discharge lamp, metal halide discharge lamp device, and lighting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a short arc type metal halide discharge lamp having slow corrosion rate properties of molybdenum foil at the sealing portion, without using mercury that has heavy environmental load and poor light starting characteristics. SOLUTION: In the lamp, there are provided an airtight vessel 1, an electrode 2 with its sealing portion mirror surface finished by electrolytic polishing, a molybdenum foil 3, and outer lead-wire 4. The airtight vessel 1 is molded in the form of rotating ellipse face having outer diameter of 7 mm out of quartz glass. The airtight vessel 1 is integrally provided with a pair of elongated seal closures 1a extended from both longitudinal ends of the ellipse. Within the airtight vessel 1, an inert gas, a first halide and a second halide are filled as discharge medium. As the inert gas, 5 atm of xenon is used. As the first halide, 3.5 mg of sodium iodide and 0.5 mg of scandium iodide are used. As the second halide, 0.6 mg of ZnI2 is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short arc type metal halide discharge lamp, a metal halide discharge lamp device using the same, and a lighting device.

[0002]

2. Description of the Related Art Metal halide discharge lamps in which a rare gas, a luminescent metal halide and mercury are sealed in an arc tube having a pair of electrodes opposed to each other are widely used because of their relatively high efficiency and high color rendering properties. Have been.

In a liquid crystal projector or the like that condenses the light emitted from the lamp and projects it on a screen, a small, short arc type metal halide discharge lamp is used. Recently, small and short-arc metal halide discharge lamps have been used as headlights for automobiles.

[0004]

In the case of a small and short arc metal halide discharge lamp, the shorter the distance between the electrodes, the higher the vapor pressure of mercury in order to secure a required lamp voltage. That is, the metal halide discharge lamp is filled with mercury in order to maintain required electric characteristics. For example, in a small, short arc metal halide discharge lamp having an arc tube of 1 cc or less, the mercury vapor pressure during operation becomes as high as 20 atm or more. Therefore, there are the following disadvantages.

[0005] The first problem is that when the temperature of the arc tube changes, the color temperature of light emission greatly changes, and accordingly, the color rendering properties also change. This conventional discharge lamp has a rare gas filled with 500 torr of argon, 1 mg of dysprosium iodide DyI3, 1 mg of neodymium iodide NdI3, and 13 mg of mercury as halides.

[0006] The amount of light emitted by a luminescent metal changes in proportion to its vapor pressure. Since the vapor pressure of the luminescent metal is significantly lower than that of mercury, when the temperature of the luminous tube changes, the luminous metal changes its vaporization amount and its vapor pressure, so that the luminescence amount changes.

On the other hand, since the vapor pressure of mercury is so high that it does not change so much even if the temperature of the arc tube changes, the amount of luminescence of mercury by the strong emission line spectrum changes little. Therefore, when the input power to the arc tube decreases, the emission of light by mercury becomes relatively dominant, so that the color temperature of the emission decreases and the color rendering property decreases. This means that conventional metal halide discharge lamps containing mercury are not suitable for dimming.

The second problem is that since the mercury vapor pressure during operation is very high, a restart voltage that is very high and has a large power is required to restart. This not only makes the lighting circuit expensive, but also makes it necessary to insulate the circuit, the lamp and the equipment containing them from high voltages.

[0009] A third problem is that the arc tube tends to burst. As described above, since the vapor pressure at the time of lighting of mercury is high, the initial strain or the strain increases during long-term lighting, so that the arc tube is easily ruptured.

In addition to the above-mentioned problems associated with the high vapor pressure of mercury, there is also the problem of encapsulating mercury itself. That is, since mercury has a large environmental load, it is convenient if it is not necessary to use it.

A fourth problem is that the light output characteristics from the start are poor because mercury is sealed.

When the light is condensed via an optical system such as a liquid crystal projector and the illuminance is greatly illuminated on an irradiation surface at a separated position, for example, a screen, the light emitted from the discharge lamp passes through the optical system without any loss. It is important to reach the irradiation surface.

In order to reduce the loss and improve the illuminance on the irradiation surface, the arc of the discharge lamp needs to be narrowed down. The fact that the arc is narrowed means that the distribution of the arc temperature is sharp.

However, the emission of mercury is optically thick due to absorption, and the energy rises due to the absorption of the emission in the middle and low temperature areas, and the temperature rises. Therefore, the distribution of the arc temperature spreads in a parabolic manner. Arc cannot be squeezed.

On the other hand, it is known that when scandium or a rare earth metal is used as the luminescent metal and the luminescence is extremely increased, the arc can be narrowed even in the presence of mercury.

However, in the above case, if the lighting pressure of mercury is high, convection becomes intense, causing arc instability and making it unpractical. In addition, since the mercury is not used, a large amount of halide is sealed, so the corrosion of the sealed part is
Severe compared to mercury filling. In particular,
Since fine irregularities are formed on the surface of the electrode shaft, sealing with quartz glass is not performed well, and the speed of corrosion of the enclosed molybdenum foil is faster than that of conventional mercury-filled metal halide lamps I understood the problem.

According to the present invention, the starting characteristics can be improved, the illuminance on the irradiation surface can be increased, the dimming can be performed, and the restart voltage can be increased without using mercury, which has a poor light rising characteristic at the time of starting and has a large environmental load. It is an object of the present invention to provide a metal halide discharge lamp of a short arc type, which has a low airtightness, is hardly ruptured in an airtight container, and can suppress the corrosion rate of molybdenum foil as an enclosure, a metal halide discharge lamp device and a lighting device using the same. .

According to the present invention, a short arc type metal halide discharge lamp according to the present invention is sealed in a fire-resistant glass and light-transmitting airtight container; and is sealed in the airtight container. A pair of electrodes; a pair of molybdenum foils sealed in an airtight container and electrically connected to the electrodes; a first halide, a second halide and a rare gas and sealed in the airtight container. The first halide is one or more halides selected from the group consisting of sodium Na, scandium Sc, and rare earth metals, and the second halide has a relatively high vapor pressure. Iron Fe, zinc Zn, aluminum Al, cadmium Cd, magnesium Mg, cobalt C
o, chromium Cr, nickel Ni, manganese Mn, antimony Sb, beryllium Be, rhenium Re, and a discharge medium that is one or more halides selected from the group consisting of gallium Ga. It is characterized by no mercury being enclosed.

In the present invention and each of the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified.

First, the airtight container will be described.

The fire-resistant glass and light-transmitting hermetic container is a glass material having fire resistance enough to withstand the normal operating temperature of the discharge lamp, and leads out the visible light of a desired wavelength region generated by the discharge to the outside. It can be made of any material that can. For example, quartz glass.

If necessary, a halogen-resistant or metal-resistant transparent film is formed on the inner surface of the airtight container.
Reforming the inner surface of the airtight container is allowed.

Next, the electrodes will be described.

The short arc type metal halide discharge lamp of the present invention may be configured to be operated by either AC or DC. It is necessary that the surface of the electrode be mirror-finished at a portion sealed in the airtight container, that is, at a portion in close contact with the airtight container. The term “mirror surface” is similar to having a specular reflection characteristic. In short, it is possible to allow irregularities in the order of micrometer, but it is a plane (curved surface) in the order of mm.

The pair of electrodes have the same structure when operated by an alternating current. However, when operated by a direct current, the anode generally has a larger heat radiation area than the cathode because the temperature rises sharply. The short arc type is designed to reduce the distance between electrodes formed in an airtight container so that the light emission of a discharge lamp is brought as close as possible to a point light source and light is efficiently collected by an optical system such as a reflector or lens. In the present invention, the distance between the electrodes is actually 6 mm or less. That is, if the distance between the electrodes exceeds 6 mm, the upward curvature of the arc due to the convection of the discharge medium becomes too large.

Therefore, in the present invention, the short arc type means one having a distance between the electrodes of 6 mm or less. But,
It is preferably 4 mm or less, and most preferably 1 to 3 mm for projection for a liquid crystal projector or the like. The distance between the electrodes is measured at the tip of the electrode.

The molybdenum foil is sealed substantially in close contact with an airtight container, and is electrically connected to the electrodes. Further, the discharge medium will be described. In the present invention, the discharge medium is composed of the first halide, the second halide and the rare gas as described above. First
Are metal halides having good starting characteristics and emitting visible light. The vapor pressure during lighting of these metals is not always high. Any one or more of them can be used as long as they are within the group consisting of the luminescent metals specified above. The second halide is
The above metal has a relatively large vapor pressure during lighting. High vapor pressure doesn't have to be too high like mercury,
Preferably, the pressure is about 5 atm or less.

The second halide is not one that does not inhibit the emission of visible light, but is acceptable as long as its proportion to the total visible light emitted by the discharge lamp is small and the influence is small.

As the halogen constituting the first and second halides, iodine is most suitable in reactivity,
The reactivity increases in the order of bromine, chlorine, and fluorine,
Any of the above may be used if necessary. Also, different halogen compounds such as iodide and bromide can be used in combination.

The rare gas acts as a starting gas and a buffer gas, and is not particularly limited as long as it does not pass through the airtight container. Is recommended for argon, krypton or xenon.

Further, mercury will be described.

In the present invention, the fact that mercury is not essentially enclosed is defined as 0.1 mg / cc of the inner volume of the airtight container.
Means less than, preferably less than 0.2 mg, of mercury is present.

However, it is environmentally desirable not to encapsulate any mercury.

In the case where the electric characteristics of the discharge lamp are maintained by mercury vapor as in the prior art, the inner volume 1c of the hermetic container is required.
Based on the fact that 20 mg or more was filled per c, it can be said that the present invention has a substantially small amount of mercury.

Finally, the operation will be described.

As is apparent from the above description, in the present invention, in addition to the first halide which is a metal halide mainly responsible for emitting visible light, a metal halide having a relatively high vapor pressure is used. Is sealed in place of mercury as the second halide, the lamp voltage is determined mainly by the evaporation amount of the second halide. When the second halide is incompletely evaporated, the amount of evaporation is determined by the vapor pressure of the second halide. The vapor pressure is determined by the coldest part temperature.

However, since it is highly reactive compared to mercury, the reaction with molybdenum foil is significantly accelerated. However, the sealing portion of the airtight container has a higher degree of adhesion because the electrode forms a mirror surface portion, and the gap reaching the molybdenum foil is smaller than before. Accordingly, the speed at which the halide enters is also reduced, and the phenomenon of non-lighting of the lamp due to erosion of the molybdenum foil during the life is reduced.

A short arc type metal halide discharge lamp according to a second aspect of the present invention is characterized in that the short arc type metal halide discharge lamp according to the first aspect is operated at 100 W or less.

A short arc type metal halide discharge lamp according to a third aspect of the present invention is the short arc type metal halide discharge lamp according to the first or second aspect.
The inner volume is 1 cc or less; and the distance between the pair of electrodes is 6 mm or less.

The present invention defines a preferable specific numerical range for obtaining a metal halide discharge lamp which is small and has a short arc shape and is close to a point light source which can be replaced with a small incandescent lamp conventionally used. It was done.

The inner volume of the airtight container is within the above range, and is suitably 0.1 to 1 cc for uses such as a liquid crystal projector and a store lighting fixture. For applications such as automotive headlights and fiber optic lighting devices,
0.005 to 0.1 cc is appropriate.

The distance between the electrodes is as described in claim 1.

A short arc type metal halide discharge lamp according to a fourth aspect of the present invention is the short arc type metal halide discharge lamp according to any one of the first to third aspects, wherein heat is kept around the airtight container on at least one electrode side. Means are provided.

The present invention is intended to maintain the electric characteristics by the vapor pressure of the second halide.
Since the vapor pressure of the halide is lower than that of mercury, the vapor pressure can be made as high as possible by using the heat retaining means in combination.

As the heat retaining means, a known structure can be adopted. When combined with a reflecting mirror, it is preferable to form a heat retaining film on the outer surface of an airtight container surrounding the electrode on the light emitting opening side of the reflecting mirror. Good.

A metal halide discharge lamp device according to a fifth aspect of the present invention is characterized in that the rotating mirror has a quadratic curved surface and is integrated with the reflecting mirror so that the light emission center is located substantially at the focal point of the reflecting mirror. And a short arc type metal halide discharge lamp according to any one of the preceding claims.

According to a sixth aspect of the present invention, there is provided a lighting device comprising: a lighting device main body; and a short arc type metal halide discharge lamp according to any one of the first to fourth aspects, which is supported by the lighting device main body. It is characterized by:

The invention applies to all devices which use the short-arc metal halide discharge lamps according to claims 1 to 4 for any lighting purpose, in particular optical devices such as reflectors and / or lenses. It is suitable for a lighting device used in combination with the system, for example, a liquid crystal projector, an overhead projector, an automobile headlight, an optical fiber lighting device, a store lighting device, and the like.

[0048]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing a first embodiment of a short arc type metal halide discharge lamp according to the present invention.

In the figure, 1 is an airtight container, 2 is an electrode, 3
Is a molybdenum foil, and 4 is an external lead wire.

The airtight container 1 is made of quartz glass having an inner diameter of 14 mm.
And a pair of elongated sealing portions 1a, 1a are integrally provided at both ends of the ellipse in the major axis direction.

The electrode 2 is formed by winding an electrode coil 2b with the electrode shaft 2a and the tip of the electrode shaft 2a projecting slightly. The base of the electrode shaft 2a is welded to one end of the molybdenum foil 3 in the sealing portion 1a. The distance between the electrodes is 4.
It is set to 2 mm. The outer diameter of the central part of the arc tube is 7m
The electrode has a shaft diameter of 0.4 mm, a total length of 9 mm, and the entire shaft is mirror-finished by electrolytic polishing. Molybdenum foil 3
Is hermetically sealed in the sealing portion 1a, and the external lead wire 4 is welded to the other end. A rare gas, a first halide, and a second halide are sealed in the hermetic container 1 as a discharge medium.

As a rare gas, 5 atm of xenon was sealed. As a first halide, 3.5 mg of sodium iodide and 0.5 mg of scandium iodide were enclosed. Enclosed. As the second halide, ZnI2
0.6 mg was enclosed. The starting current of the short-arc metal halide discharge lamp obtained was 4 A
A test was performed in which a blinking cycle of lighting for 3 minutes and turning off for 5 minutes was performed at a (steady current of 1.2 A). As a comparative example, an electrode not subjected to electrolytic polishing was used. The other configurations are the same. As a result of the experiment, it was found that
While it was able to blink 44,000 times, the comparative example was 8,000 times.

FIG. 2 is a front view in central section showing a second embodiment of the short arc type metal halide discharge lamp of the present invention. In the figure, the same parts as those in FIG. The present embodiment is different in that the inner volume of the airtight container 1 is a small metal halide discharge lamp having a capacity of 0.05 cc. The airtight container 1 has an inner diameter of 4 mm
It is. The electrode 2 is mirror-finished as a whole and has no electrode coil. The distance between the electrodes is 4.2 mm. The discharge medium is as follows. 1 atm xenon, the first halide is scandium iodide ScI3
0.14 mg and sodium iodide NaI 0.86 m
g. In addition, as the second halide, 1 m
g.

FIG. 3 is a front view showing a third embodiment of a short arc type metal halide discharge lamp according to the present invention.
In this embodiment, a small-sized short-arc metal halide discharge lamp similar to that shown in FIG. 2 is further mounted on a headlight for an automobile.

Reference numeral 21 denotes an outer tube, 22 denotes a base, and 23 denotes an insulating tube.

The outer tube 21 houses therein a metal halide discharge lamp 5 ′ having a structure substantially similar to that shown in FIG. 2, and is sealed at both ends, and one end of the outer tube 21 is erected on a base 22.
The external lead wire 4 led out from the other end extends parallel to the outer tube 21 and is introduced into the base 22 and is connected to a terminal (not shown). In this case, the molybdenum foil 3 itself is also mirror-finished, so that a gap is hardly generated between the molybdenum foil 3 and the electrode. The insulating tube 23 covers the external lead wire.

FIG. 4 is a perspective view showing an automobile headlight as a first embodiment of the lighting device of the present invention.
In the figure, 31 is a reflecting mirror and 32 is a front cover. The reflecting mirror 31 is formed on a paraboloid of revolution having a deformed shape by molding plastics, and is configured so that a metal halide discharge lamp (not shown) shown in FIG.

The front cover 32 is formed integrally with a prism or lens by molding transparent plastics, and is airtightly mounted on the front opening of the reflector.

[0060]

According to each of the first to sixth aspects of the present invention, instead of mercury, a metal halide having a relatively high vapor pressure and low visible light emission is sealed together with a light-emitting metal halide. As a result, it is possible to improve the starting characteristics without essentially using mercury, which has a large environmental load, to enable dimming, to reduce the restart voltage, and to reduce the corrosion rate of the molybdenum foil. Lamps can be provided.

According to the fourth aspect of the present invention, in addition to the above, the heat retaining means is provided around at least one of the electrodes, so that the short arc can easily maintain the vapor pressure of the second halide in a preferable high range. Shaped metal halide discharge lamps can be provided.

According to the fifth aspect of the present invention, it is easy to exhibit optical performance by being integrated with a reflecting mirror having a rotating quadric surface shape,
Moreover, a metal halide discharge lamp device having the effects of claims 1 to 4 can be provided.

According to the illumination device of the sixth aspect, it is possible to provide an illumination device having the effects of the first to fourth aspects.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a short arc type metal halide discharge lamp of the present invention.

FIG. 2 is a central sectional front view showing a second embodiment of the short arc type metal halide discharge lamp of the present invention.

FIG. 3 is a front view showing a third embodiment of a short arc type metal halide discharge lamp according to the present invention.

FIG. 4 is a perspective view showing an automobile headlight as a lighting device according to a first embodiment of the present invention;

[Description of Signs] 1 ... Airtight container 1a ... Sealing part 2 ... Electrode 2a ... Electrode shaft 2b ... Electrode coil 2c ... Mirror part 3 ... Molybdenum foil 4 ... External lead wire

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Atsushi Saita, Inventor 4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo Inside Toshiba Lighting & Technology Corporation (72) Mikio Matsuda 4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo No. Toshiba Litec Co., Ltd. (72) Inventor Toshio Hiruda 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo F-term in Toshiba Litec Co., Ltd. 5C039 HH03 HH04

Claims (6)

[Claims] 1. An airtight container having a fire-resistant glass and translucency; a pair of electrodes sealed in an airtight container, and a sealed portion forming at least a mirror surface; A pair of molybdenum foils connected thereto; a first halide, a second halide, and a rare gas, which are sealed in an airtight container, wherein the first halide is sodium N
a, one or more halides selected from the group consisting of scandium Sc and rare earth metals, and the second halide is iron Fe, zinc Zn, aluminum Al, cadmium having a relatively high vapor pressure. C
d, a discharge medium that is one or more halides selected from the group consisting of magnesium Mg, cobalt Co, chromium Cr, nickel Ni, manganese Mn, antimony Sb, beryllium Be, rhenium Re, and gallium Ga. A metal arc discharge lamp of short arc type, characterized by being essentially free of mercury. 2. A short arc type metal halide discharge lamp according to claim 1, which is lit at 100 W or less. 3. The short-arc type airtight container according to claim 1, wherein the inner volume of the airtight container is 1 cc or less; and the distance between the pair of electrodes is 6 mm or less. Metal halide discharge lamp. 4. A heat insulating means is provided around an airtight container on at least one electrode side.
4. A short arc type metal halide discharge lamp according to any one of claims 1 to 3. 5. A short arc type metal halide according to claim 1, wherein the reflector is a quadratic curved surface and is integrated so that an emission center is located at a position substantially at a focal point of the reflector. A metal halide discharge lamp device comprising: a discharge lamp; 6. A lighting device comprising: a lighting device main body; and a short arc type metal halide discharge lamp according to claim 1 supported by the lighting device main body.