JP2003178710A - Metal halide lamp, metal halide lamp lighting device and lighting device - Google Patents

Abstract

(57) Abstract: A metal halide lamp having substantially the same electrical characteristics and luminous characteristics as those in which mercury is sealed without essentially using mercury having a large environmental load, and a metal halide lamp lighting device including the same. And a lighting device. An airtight container, a pair of electrodes sealed in the airtight container, a first halide mainly containing sodium Na and scandium Sc,
Magnesium Mg, iron Fe, cobalt Co, chromium C
r, zinc Zn, nickel Ni, manganese Mn, aluminum Al, antimony Sb, beryllium Be, rhenium Re, gallium Ga, titanium Ti, zirconium Zr and hafnium Hf, a halide of one or more metals selected from the group consisting of And a discharge medium containing a rare gas and containing essentially no mercury, the second halide having a vapor pressure of 5 atm or less during lighting.

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 essentially containing no mercury, a metal halide lamp lighting device and a lighting device including the same.

[0002]

2. Description of the Related Art A metal halide lamp in which a rare gas, a halide of a luminescent metal and mercury are enclosed in an arc tube having a pair of electrodes facing each other is widely used because of its relatively high efficiency and high color rendering. ing. As is well known, the metal halide lamp is classified into a short arc type and a long arc type.

Short arc type metal halide lamps are used for projecting liquid crystal projectors, overhead projectors, and the like, which collect the light emitted from the lamps and project them on a screen, and for store lighting, such as downlights and spotlights. For light projection, a small, short arc type metal halide lamp has recently been used instead of a halogen light bulb as a headlight of an automobile.
The specifications of a metal halide lamp for a headlight of an automobile are described in, for example, Japanese Patent Application Laid-Open No. 2-7347, but it is indispensable to enclose about 2 to 15 mg of mercury.

By the way, there is a need for a metal halide lamp that does not require the encapsulation of mercury, and the invention described in, for example, Japanese Patent Application Laid-Open No. 3-112045 has been made to meet this need. The present invention is intended to obtain a required lamp voltage by enclosing helium or neon in place of mercury at a pressure of 100 to 300 Torr. Furthermore, since these rare gases have a small atomic radius, they are made of quartz glass. Since it will be transmitted through, the airtight container is made of translucent ceramics.

However, the metal halide lamps currently put into practical use require mercury in order to obtain a desired lamp voltage and maintain the electrical characteristics. That is, for example, if the lamp voltage is low, the lamp current must be increased to obtain the desired lamp input. In this case, an increase in current capacity and an increase in heat generation of related equipment such as a lighting circuit, a lighting fixture, and wiring become problems. Also,
When the lamp current is large, there is also a problem that the electrode efficiency increases and the lamp efficiency decreases. That is, since the electrode drop voltage of the metal halide lamp is constant in the lamp, if the lamp voltage is low, it is necessary to increase the lamp current in order to make up for it and supply the same lamp power. And the lamp efficiency decreases. Therefore, generally, in a discharge lamp, it is advantageous to set the lamp voltage as close as possible to the input voltage of the lamp, that is, as high as possible within a range where the arc does not extinguish.

Next, the reason why the mercury filling is necessary will be explained while considering the lamp voltage.

FIG. 21 is a conceptual diagram for explaining the lamp voltage in the metal halide lamp. In the figure, 1 is an airtight container, 2 and 2 are electrodes, and 3 and 3 are lead wires.

The lamp voltage Vl is a voltage appearing between the lead wires 3 and 3 when the metal halide lamp is in a lighting state. The distance L between the electrodes 2 and 2 is called the inter-electrode distance.

The lamp voltage Vl can be expressed by Equation 1.

[0010]

## EQU1 ## Vl = E × L + Vd Here, E is the potential gradient of the plasma between the electrodes, and Vd is the electrode drop voltage.

The potential gradient E of the plasma can be expressed by Equation 2.

[0012]

## EQU2 ## E = I / 2π∫σr dr where I is the lamp current, σ is the electrical conductivity of the plasma, and is a function of the temperature T. r is a radial distance from the center to an arbitrary position.

Assuming that the substance A exists in the discharge space during the lighting of the metal halide lamp, the electric conductivity σ of the substance A at the temperature T can be expressed by the following equation (3).

[0014]

Equation 3] ^{_{σ = C · N E / (}} T 1/2 · (N A · Q)) where, C is a constant, _{N E} is the electron density, _{N A} is the density of material, Q is an electron substances A Is the collision cross section for.

The lamp voltage Vl can be calculated from the formula 1 by using the potential gradient E.
It can be seen that the larger the value is, and the larger the distance L between the electrodes is, the larger the value is. Further, the potential gradient E is calculated from Equation 2 as the electric conductivity σ is smaller and the lamp current I is larger,
You can see it grows. Furthermore, it can be seen from Equation 3 that the electrical conductivity σ is smaller as N _E is larger and N _A and Q are larger.

Therefore, when the inter-electrode distance L and the lamp current I are constant, the substance A whose lamp voltage Vl becomes large
Conditions of, (. Which is suppressed to a small N _E) ionization difficult, density in the lamp is large (can be increased N _A.), Is that a large collision cross section Q of the electrons.

Thus, mercury is a substance having a very high vapor pressure (1 atm at 361 ° C.), is hard to ionize, and has a large collision cross section with electrons. Therefore, a desired lamp voltage can be easily obtained by adjusting the enclosed amount of mercury according to the size of the lamp.

From the above description, it can be understood that the desired lamp voltage can be easily obtained by using mercury in the conventional metal halide lamp.

[0019]

In the case of a metal halide lamp, it is necessary to increase the vapor pressure of mercury in order to secure a required lamp voltage as the size of the metal halide lamp is smaller and the distance L between the electrodes is shorter. For example, even in a small and short arc type metal halide lamp having an inner volume of the arc tube of 1 cc or less, the mercury vapor pressure during lighting becomes 20 atm or more. Rated lamp power of 100 for headlights of moving bodies such as automobiles
The metal halide lamp of W or less is characterized in that the distance between the electrodes is small and the load on the tube wall is large. For this reason, in the case of the conventional metal halide lamp in which mercury is sealed, the mercury vapor pressure becomes higher than 20 atm in order to obtain the required lamp voltage as described above, and the airtight container relatively moves accordingly. It is easily damaged.

Further, since xenon is enclosed at a high pressure in order to improve the luminous flux rising characteristics, the xenon during lighting is 3%.
It can reach about 5 atm. Therefore, it is necessary to apply a high-voltage and high-power starting pulse voltage for dielectric breakdown and starting the starting gas. At the time of an instant restart, a higher starting pulse voltage is required, and therefore, it is necessary to make the height of the dielectric strength of the lighting circuit, the lighting equipment and the wiring compatible with the grade, and thus it becomes expensive.

Further, the problem of the luminous flux rising characteristic has been solved by the high-pressure encapsulation of xenon and the adoption of a lighting circuit means for applying a high starting pulse voltage and for supplying a large current immediately after lighting and gradually reducing the current. , The chromaticity rising characteristic is poor. That is, xenon first emits light, and then mercury emits light. The light emission of this mercury continues until after 10 to 20 seconds. The emission of mercury has poor color rendering and does not fall within the required white chromaticity range.

In the following, in the metal halide lamp, the problems caused by enclosing mercury and the problems in the case of not enclosing mercury in the prior art will be sorted out. 1. Problems caused by encapsulating mercury (1) Problems with environmentally hazardous substances At present, environmental problems are being closely addressed on a global scale, and even in the lighting field, mercury, which is an environmentally hazardous substance that adversely affects the environment Reducing from lamps and even eliminating them is considered a very important issue.

Therefore, the biggest problem of the conventional metal halide lamp is that mercury is enclosed.

(2) Problem of rise of chromaticity characteristics at start-up In the case of a short arc type metal halide lamp for a vehicle headlight, an instantaneous rise of luminous flux is required. For this,
A conventional metal halide lamp employs a lighting method in which xenon is charged at a high pressure as a starting gas, a large current is supplied in the initial stage of lighting, and the current is reduced over time. In this way, the instantaneous rising is possible, but when the switch is turned on, mercury rapidly evaporates and takes energy, so that the rising of the vapor pressure of the luminescent metal is delayed, so that the state of strong mercury emission is 10%. ~ 20 seconds later. Mercury light emission is inferior in color characteristics, so the color rendering property is also poor and the chromaticity does not fall within the white range. As described above, the rising characteristic of the chromaticity characteristic is extremely bad. Therefore, it takes a long time to achieve the desired chromaticity characteristics.

(3) Problem not suitable for dimming When the temperature of the arc tube changes, the color temperature of light emission changes greatly, and the color rendering property also changes accordingly. Hereinafter, this problem will be described with reference to FIG.

FIG. 22 is a graph showing the emission spectrum distribution of a conventional short arc type metal halide lamp for projection. In the figure, the horizontal axis is wavelength (nm)
, And the vertical axis represents the relative radiant power (%).

[0027] The conventional short arc type metal halide lamp, argon 500Torr as a rare gas, dysprosium iodide DyI ₃ 1 mg and neodymium iodide NdI ₃ 1 mg as halide, and mercury 13m
g, respectively. The emission spectrum shows continuous emission by dysprosium Dy and neodymium Nd,
Each of them is composed of a main emission line spectrum of the element with a symbol above the arrow, and it can be seen that the emission line spectrum of mercury has a large power.

By the way, the amount of light emitted by each luminescent metal changes in proportion to the vapor pressure in the lamp. Since the vapor pressure of the halide of the luminescent metal is significantly lower than that of mercury, when the temperature of the arc tube changes, the vapor pressure of the luminescent metal of the luminescent metal changes and the vapor pressure in the lamp changes. , The amount of light emission 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 light emission due to the strong emission line spectrum of mercury does not change much. Therefore, when the input power to the arc tube is reduced, the light emission by mercury becomes relatively dominant, so that the color temperature of the light emission is lowered and the color rendering property is lowered. This means that the conventional metal halide lamp that encapsulates mercury is not suitable for dimming.

In the case of automobile headlights, dimming is necessary for daytime lighting (daylight) adopted in Europe and the United States, but a conventional metal halide lamp containing mercury is used as a light source. If used, the color characteristics will be significantly reduced.

(4) Large variation in characteristics Since the temperature of the arc tube of a metal halide lamp containing mercury varies depending on the dimension variation of each lamp, variation in characteristics is likely to occur even with the same input. In addition, the characteristics are likely to change even when the temperature of the coldest part rises due to blackening of the arc tube during a long life.

(5) Difficult to instantaneously restart In the metal halide lamp for headlight, high-pressure xenon is enclosed to accelerate the luminous flux rise as described above. It will be about.
Since the mercury vapor pressure and the xenon vapor pressure during lighting are extremely high as described above, a very high pulse voltage with high power must be applied for restarting. This not only makes the lighting circuit expensive, but it is also necessary to provide high-grade insulation of the lighting circuit, the lamp, and the equipment that houses them for high voltages.

In a small short arc type metal halide lamp, since the distance between the electrodes is small, the mercury vapor pressure is set high in order to obtain the required lamp voltage.
The mercury vapor pressure becomes 20 atm or higher during lighting.

(6) Problem that the arc tube easily bursts As described above, since the mercury vapor pressure during lighting is high, the initial distortion or the distortion increases during long-term lighting, and the arc tube easily breaks. This problem significantly reduces the reliability of the lamp.

(7) The problem of low illuminance on the irradiation surface In the case of a metal halide lamp for a headlight, when the irradiation surface at the separated position is illuminated brightly, the light emission of the lamp passes through the optical system without any loss. It is important to reach. As has been clarified by the present invention, in order to reduce the loss and improve the illuminance of the irradiation surface, it is effective that the arc is narrowed down. That the arc is narrowed means that the distribution of the arc temperature is steep.

However, as will be described later, the light emission of mercury has absorption and is optically thick, and the temperature rises due to absorption of energy by absorption of the light emission in the middle to low temperature portions, resulting in a parabolic arc temperature distribution. Spread and therefore the arc cannot be narrowed.

On the other hand, it is known that if scandium or a rare earth metal is used as the light emitting metal and the amount of light emitted is extremely increased, the arc can be narrowed even in the presence of mercury. However, since the lighting pressure of mercury is high, the convection becomes intense and the arc becomes unstable, so that it cannot be put to practical use. 2. Problems of Prior Art Not Encapsulating Mercury In the above-mentioned metal halide lamps not encapsulating mercury, helium or neon will have a remarkably high pressure during lighting. be able to. Therefore, it can be highly evaluated in that a metal halide lamp that does not contain mercury is obtained.

(1) Problem of rupture of airtight container However, it is quite difficult to realize the above-described metal halide lamp having a high pressure during lighting with a structure similar to that of a conventional metal halide lamp in which mercury is sealed. is there. For example, in a small-sized metal halide lamp, when the required lamp voltage is 50 to 60 V, the pressure of helium or neon will exceed 150 atm during lighting. Can't get high reliability for.

(2) High heat loss Further, when a metal halide lamp is constructed without containing mercury, there is a problem that the heat loss becomes large in addition to the lamp voltage. That is, when mercury is enclosed, it causes self-absorption in the middle or low temperature region of the discharge space,
In the medium to low temperature region, the temperature rises to obtain energy, and the temperature of the high temperature region decreases from the overall energy balance accordingly.

FIG. 23 is a graph schematically explaining the arc temperature distribution in the metal halide lamp when mercury is not enclosed and when mercury is enclosed. In the figure, the horizontal axis represents the position of the arc tube in the radial direction, and the vertical axis represents the arc temperature (K). Also,
A curve A shows an arc temperature distribution when mercury is not enclosed, and a curve B shows an arc temperature distribution when mercury is enclosed.

As is clear by comparing the curves A and B in the figure, the arc temperature distribution when mercury is not enclosed is steeper, that is, the temperature gradient is larger than when mercury is enclosed. As is well known to those skilled in the art, the heat loss lost from the arc tube is related to the weight of the rare gas to be filled and the filling pressure, but since it is proportional to the temperature gradient, the heat loss is smaller when mercury is not filled. large. This means that the metal halide lamp not containing mercury has a large heat loss, and thus the luminous efficiency is inferior to that of the metal halide lamp containing mercury.

The present invention essentially does not use mercury, which has a large environmental load, and has a metal halide lamp having substantially the same electrical characteristics and light emission characteristics as those in which mercury is sealed, a metal halide lamp lighting device and lighting provided with the same. The purpose is to provide a device.

Further, according to the present invention, a metal halide lamp which can reasonably increase the lamp voltage and obtain high lamp efficiency without using mercury essentially, a metal halide lamp lighting device including the same, and Another object is to provide a lighting device.

Still another object of the present invention is to provide a metal halide lamp in which the airtight container is less likely to burst, a metal halide lamp lighting device and a lighting device including the metal halide lamp.

Still another object of the present invention is to provide a metal halide lamp that emits white light, a metal halide lamp lighting device and a lighting device including the same.

Still another object of the present invention is to provide a metal halide lamp which has a relatively low starting voltage and can be easily started or instantly restarted, and a metal halide lamp lighting device and a lighting device including the same.

[0047]

A metal halide lamp according to a first aspect of the present invention comprises an airtight container; a pair of electrodes sealed in the airtight container; sodium Na and scandium Sc.
First halide mainly composed of magnesium halide, magnesium Mg, iron Fe, cobalt Co, chromium Cr, zinc Zn, nickel Ni, manganese Mn, aluminum A
1, antimony Sb, beryllium Be, rhenium Re,
A second halide mainly containing a halide of one or more kinds of metals selected from the group consisting of gallium Ga, titanium Ti, zirconium Zr, and hafnium Hf, and having a vapor pressure of 5 atm or less during lighting; A discharge medium containing a rare gas and essentially containing no mercury;

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

<Airtight Container> In the present invention, the airtight container must be fireproof and transparent.
An airtight container that is "fireproof and translucent" is a material that is fireproof enough to withstand the normal operating temperature of a discharge lamp, and guides visible light in the desired wavelength range generated by discharge to the outside. It can be made of any material as long as it can. For example, quartz glass, translucent alumina, ceramics such as YAG, or single crystals thereof can be used. If necessary, a halogen-resistant or metal-resistant transparent coating may be formed on the inner surface of the airtight container, or the inner surface of the airtight container may be modified.

In the case of a moving headlight, the airtight container preferably has a maximum diameter portion of 3-10 mm in inner diameter,
The outer diameter is 5 to 13 mm.

<Regarding a Pair of Electrodes> The pair of electrodes are sealed inside the airtight container so as to be opposed to each other. The distance between electrodes is 6 mm or less, preferably 1 to 5 mm in the case of a small short arc type used for projection such as a liquid crystal projector or headlight of a moving body such as an automobile. It is optimally 1 to 3 mm for projection of a liquid crystal projector or the like. The distance between the electrodes is measured at the tips of the electrodes.

Further, the metal halide lamp of the present invention is
It may be configured to illuminate with either AC or DC. Therefore, the pair of electrodes, when operated with alternating current,
Although having the same structure, in the case of operating with a direct current, the temperature of the anode generally rises sharply, so that it is possible to use one having a larger heat radiation area than the cathode and therefore a thicker main part.

<Discharge Medium> In the present invention, the discharge medium essentially contains the first halide, the second halide and the rare gas as described above.

(Regarding First Halide) First
The halide of 1 contains the halides of sodium Na and scandium Sc as the main components. If desired, a rare earth metal can be selectively included as the first halide. The metal forming the first halide mainly contributes to white light emission, but the first halide generally does not necessarily have a relatively higher vapor pressure during lighting than the second halide described below.

(Regarding Second Halide) Second
The halides of magnesium are magnesium Mg, iron Fe, cobalt Co, chromium Cr, zinc Zn, nickel Ni, manganese Mn, aluminum Al, antimony Sb, beryllium Be, rhenium Re, gallium Ga, titanium Ti, zirconium Zr and hafnium Hf. It is mainly composed of one or more kinds of halides selected from the group. These halides are metal halides that have a relatively high vapor pressure during lighting and are less likely to emit light in the visible region than the metal of the first halide, and are used to maintain the lamp voltage. It works effectively.

Further, the above-mentioned second halide is constructed so that the vapor pressure during lighting is 5 atm or less. Note that the vapor pressure of the second halide does not need to be too high as with mercury, and the required electrical characteristics can be obtained as long as it is approximately 5 atm or less.

Further, the metal of the second halide has a common feature that it is less likely to emit light in the visible region as compared with the metal of the first halide. Note that "it is difficult to emit light in the visible region" does not mean that the emission of visible light is small in an absolute sense, but has a relative meaning with respect to the first halide. This is because iron Fe and nickel Ni certainly emit more ultraviolet light than visible light, whereas titanium Ti, aluminum Al, and zinc Zn emit more light in the visible light range. Therefore, when these metals that emit a large amount of visible light are emitted alone, the energy is concentrated on the metal, so that the amount of visible light is increased. However, if the metal of the second halide has a higher energy level than the metal of the first halide and it is difficult to emit light, in the state where the first and second halides coexist,
Since the energy is concentrated on the light emission of the metal of the first halide, the light emission of the metal of the second halide is reduced. Therefore, these metals are also suitable as the second halide in the present invention. It should be noted that the second halide metal is not prohibited from emitting visible light, and is allowed as long as the ratio thereof to the total visible light emitted by the discharge lamp is small and its influence is small.

Furthermore, the second halide is iron Fe, zinc Zn, manganese M, among the above groups.
Especially preferred is one or more halides selected from the group consisting of n, aluminum Al and gallium Ga. However, although these halides are preferably used as the main component, they are preferably magnesium Mg, cobalt Co, chromium Cr, nickel Ni, antimony Sb, beryllium Be, rhenium Re, titanium Ti, zirconium Zr and hafnium Hf. The lamp voltage can be further increased by adding one or more kinds of halides selected from the above as auxiliary components.

Table 1 exemplifies the second halide that can be used in the present invention together with the temperature of 1 atm. It should be understood that these values are slightly different depending on the literature and the like, and therefore the temperature values in Table 1 should be understood as approximate values.

[0060]

[Table 1] No. Temperature becomes the second halide 1 atm _{(℃) 1 AlI 3 422 2} FeI 2 827 3 ZnI 2 727 4 SbI 3 427 5 MnI 2 827 6 CrI 2 827 7 GaI 3 349 8 ReI 3 627 9 MgI 2 927 10 CoI ₂ 827 11 NiI ₂ 747 12 BeI ₂ 487 13 TiI ₄ 377 14 ZrI ₄ 431 15 HfI ₄ 427 Most of the halides shown in Table 1 have a lower vapor pressure than mercury, and the adjustment range of the lamp voltage is higher than that of mercury. Narrow,
As described above, the range of adjustment of the lamp voltage can be expanded by mixing and encapsulating a plurality of these as necessary. For example, if AlI ₃ is incompletely evaporated and the desired lamp voltage is not obtained, adding AlI ₃ does not change the lamp voltage. On the other hand, instead of adding AlI ₃ , ZnI ₂
By adding, the lamp voltage generated by the action of ZnI ₂ is added, so that the lamp voltage can be increased. Furthermore, if another second halide is added, a higher lamp voltage can be obtained.

Furthermore, in the present invention, the second halide is 0.05 mg per 1 cc of the internal volume of the airtight container.
The above is enclosed. In addition, for example, as a small-sized metal halide lamp for headlights, it is preferably 1 to 200 m.
It is g / cc.

(Regarding Halogen) First and Second
As the halogen constituting the halide of 1, the iodine is optimal in terms of reactivity, and the reactivity becomes stronger in the order of bromine, chlorine, and fluorine, but any of the above may be used if necessary. Further, different halogen compounds such as iodide and bromide can be used together.

(Regarding Rare Gas) The rare gas is a gas that acts as a starting gas and a buffer gas, and is enclosed in an airtight container. As the rare gas, xenon, argon, or krypton can be used alone or in combination of two or more. Further, the luminous flux rising characteristic of the metal halide lamp can be improved by setting the pressure of the rare gas to be 1 atm or more. A good luminous flux rising characteristic is extremely important in a headlight of a moving body such as an automobile. The pressure is preferably 1 to 15 atm.

<About Mercury> In the present invention,
"Inherently not containing mercury" means that, in addition to not containing mercury at all, less than 0.3 mg, preferably 0.2 mg or less of mercury is present per 1 cc of the internal volume of the airtight container. Means to allow. But,
Not encapsulating mercury at all is environmentally desirable. In the case of maintaining the electrical characteristics of a metal halide lamp with mercury vapor as in the conventional case, 20 mg or more per 1 cc of the internal volume of the airtight container for the short arc type and 5 mg or more for the long arc type have been sealed. Thus, it can be said that the present invention is essentially free of mercury.

<Regarding Other Configurations> The following configurations can be added if necessary, although they are not essential configuration requirements of the present invention. 1. About the outer tube The outer tube houses the arc tube. The airtight container can be mechanically protected by using the outer tube. If necessary, the inside of the outer tube can be evacuated as described below. Here, the arc tube is composed of an airtight container, a pair of electrodes, and a discharge medium. 2. About the heat retention means The heat retention means is a means for reducing the loss of heat generated from the arc tube and, as a result, for maintaining the vapor pressure of the second halide at a value as high as possible with a relatively small amount of heat. Any configuration may be used as long as the loss of heat generated can be reduced, but for example, the following configurations are allowed.

By disposing an outer tube accommodating the above-mentioned arc tube inside and evacuating the outer tube, heat loss due to convection and conduction of heat generated from the arc tube is reduced and the discharge medium is kept warm. To be done. In this case, the specific structure, shape and constituent material of the outer tube do not matter. The inside of the outer tube being vacuum means that the inside of the outer tube has a pressure of 10 ⁻⁴ Torr or less.

Further, heat rays emitted from the arc tube to the outside are reflected and returned to the arc tube, and a heat ray reflecting / visible light transmitting film for transmitting visible light is provided to reduce heat loss due to radiation and discharge. The medium can be kept warm. The heat-reflecting / visible light-transmitting film is formed on the inner surface, outer surface, or both inner and outer surfaces of a cylindrical body or outer tube made of quartz glass or the like arranged between the arc tube and the outer tube, or on the outer surface of the arc tube. be able to.

Further, it goes without saying that the above means can be combined with each other as appropriate.

Since the heat insulating means for reducing the loss of heat generated from the arc tube is provided, the heat loss generated by the discharge inside the arc tube is small, so that the heat loss of the arc tube is reduced. The luminous efficiency is improved. 3. About Lamp Power The lamp power is preferably 100 W or less for applications such as headlights and liquid crystal projectors. 4. About the ultraviolet ray removing means The ultraviolet ray removing means is a means for substantially removing the ultraviolet rays from the light emitted from the metal halide lamp to the outside.
In addition, "substantially removes ultraviolet rays" means that the amount of ultraviolet rays is practically removed to an allowable range, and ultraviolet rays must be completely cut 100%. is not.

The ultraviolet ray removing means may have any structure as long as the ultraviolet rays are substantially removed.
For example, the arc tube is housed in an outer tube made of a glass material having a composition having an ultraviolet blocking property. The inside of the outer tube may be in communication with the outside air, may be airtight, and may have a vacuum inside.

Furthermore, the inner surface of the airtight container or the airtight container itself may be provided with ultraviolet ray removing performance. By replacing the material structure on the inner surface or the outer surface of the airtight container with a structure that blocks ultraviolet light, or by coating a film of a translucent material that blocks ultraviolet light, it is possible to impart ultraviolet blocking performance.

Furthermore, an ultraviolet blocking cylinder can be provided outside the arc tube.

In this way, since the ultraviolet rays emitted to the outside by the ultraviolet ray removing means are substantially removed, the illuminating device, for example, the headlamp is prevented from being deteriorated by the ultraviolet rays and the human eye is irradiated with the ultraviolet rays. Prevent from.

<Operation of the Present Invention> As is clear from the above description, in the present invention, in addition to the first halide which is a metal halide mainly responsible for white light emission, magnesium Mg, iron One or more selected from the group consisting of Fe, cobalt Co, chromium Re, zinc Zn, nickel Ni, manganese Mn, aluminum Al, antimony Sb, beryllium Be, rhenium Re, gallium Ga, titanium Ti, zirconium Zr, and hafnium Hf. The lamp voltage is formed by the second halide, since a seed metal halide is essentially encapsulated as the second halide instead of mercury. The lamp voltage is mainly determined by the evaporation amount of the second halide, but in the present invention, since the vapor pressure is about 5 atm or less as described above, as a result, the lamp voltage is maintained at the required value. . When the second halide is incompletely evaporated, the evaporation amount is determined by the vapor pressure of the second halide. The vapor pressure of the halide is determined by the temperature of the coldest part of the discharge space. Also, the vapor pressure of the second halide during lighting is lower than that of mercury, but is obviously higher than that of the first halide, and as described above, it may be about 5 atm or less. .

Therefore, in the metal halide lamp of the present invention, it is possible to operate as desired even though mercury is not essentially enclosed, and to obtain the electrical characteristics and the light emission characteristics which are almost the same as those of the prior art in which mercury is enclosed. it can. It should be noted that, in the above description, “substantially” means that there is a difference that is slightly inferior within a practicable range as compared with the related art. Considering that the metal halide lamp is lit by a computerized lighting device, this level is practically acceptable. However, as described above, the lamp voltage can be further increased by applying the heat insulating means to the airtight container, if desired.

Further, in the present invention, the above-mentioned various problems in the prior art in which mercury is enclosed can be improved.

The effects of the present invention will be listed below. 1. It is possible to secure a lamp voltage that is almost the same as the one in which mercury is sealed.

Encapsulating a second halide, which is predominantly a halide of a metal selected from a group of specific metals, to reasonably increase the lamp voltage despite essentially no use of mercury. You can Accordingly, the lamp current can be made relatively small and the required lamp power can be supplied. 2. It is possible to obtain a lamp efficiency that is almost comparable to that of a mercury lamp. In addition to the structure of the present invention, by keeping the temperature of the airtight container and adding a halide of cesium Cs to the discharge medium, it is possible to obtain a higher lamp efficiency than that in which mercury is sealed. 3. The airtight container does not burst easily.

The vapor pressure during lighting does not become extremely high,
Since it can be easily reduced to about 60% of that when mercury is filled, the number of bursts during lighting of the airtight container is reduced. 4. White light emission is obtained.

The first halide is mainly sodium Na and scandium Sc halide,
In addition, since mercury is not essentially enclosed, the metal of the first halide emits light immediately after lighting, so that white light emission is obtained. White light is versatile. 5. Since the starting voltage is relatively low, starting and instant restart are easy.

Since the vapor pressure of the second halide is obviously lower than that of mercury in most cases, the starting voltage becomes low and the instant restart becomes easy. For this reason,
Since the peak value of the starting pulse voltage applied for starting or restarting can be reduced, the lighting circuit, igniter,
It is possible to reduce the dielectric strength of the wiring and the lighting equipment to reduce the cost. 6. In an optical system using a reflecting mirror, high light collection efficiency can be obtained.

It has been found that, when the metal halide lamp of the present invention is combined with an optical system using a reflecting mirror, a surprisingly high light-collecting efficiency can be obtained. The reason is that when the second halide is filled instead of mercury, the arc is effectively narrowed as shown in FIG.

Therefore, when the metal halide lamp of the present invention is used as a light source for a headlight, for example, the illuminance on the irradiation surface can be significantly improved. 7. Dimming becomes possible.

Even when the input to the lamp changes, the color temperature of emitted light and the color rendering properties do not change so much, so that dimming is possible. Therefore, it is possible to light up during the day (daylight). 8. There is little variation in emission color with respect to variations in shape and size.

Since there is little change in the lamp characteristics with respect to variations in the shape and size of the arc tube, variations in emission color are small. 9. It is suitable for direct current lighting.

When a conventional metal halide lamp containing mercury is lit by direct current, for example, sodium N as a light emitting metal is used.
Since a and scandium Sc are positively ionized,
It is attracted to the cathode side, and the concentration of the luminescent metal on the anode side becomes smaller than that on the cathode side. On the other hand, although mercury is also sucked to the cathode side to some extent, since the amount of mercury is originally overwhelmingly large, a sufficient amount of mercury also exists on the anode side. As a result, the luminescent metal on the cathode side sufficiently emits light, but on the anode side, the luminescence of the luminescent metal is significantly weakened, and the luminescence of mercury is mainly. Therefore, remarkable color separation occurs between the electrodes, which is not suitable for practical use. Therefore, in an application field in which color separation is a problem, metal halide lamps containing mercury are used exclusively by AC lighting.

On the other hand, in the present invention, by encapsulating the second halide instead of essentially encapsulating mercury, the difference in the color temperature between the electrodes is small even when DC lighting is performed. , Practical enough. This is because the second halide does not easily emit light in the visible region, and the metal of the first halide also emits intense light even on the anode side. 1
0. The luminous flux rising characteristics at the time of starting can be improved.

By enclosing a rare gas such as xenon at a pressure of 1 atm or more, not only the chromaticity rising characteristics but also the luminous flux rising characteristics at the time of starting can be improved.

Therefore, in addition to the other effects described above, a metal halide lamp suitable as a headlamp can be obtained.

According to the metal halide lamp of the invention of claim 2, in the metal halide lamp of claim 1, the emission of light generated by lighting is according to Japanese Industrial Standard JIS D 5
It is characterized in that it falls within the range of white chromaticity specified in 500-1984.

The present invention defines a metal halide lamp having suitable chromaticity for a headlight.

That is, Japanese Industrial Standard JIS D 55
00-1984 stipulates standards for automotive lamps,
The chromaticity range of white is defined therein. Therefore,
By satisfying the above chromaticity range of the metal halide lamp, a lamp having a white emission color that meets the JIS standard for automobiles such as headlights can be obtained.

In the present invention, since essentially no mercury is encapsulated, white light emission from the luminescent metal forming the first halide mainly contributes from the time of starting, so that the chromaticity at the time of starting is increased. The start-up characteristics are excellent, and the chromaticity of light emission satisfies the standard of white chromaticity almost at the same time as starting. Therefore, the chromaticity of light emission at the time of starting does not feel uncomfortable.

On the other hand, in the case of a conventional metal halide lamp for a headlight, which contains mercury, it is necessary to set 10
The light emission for up to 20 seconds is mainly mercury light emission, so that the color rendering property is poor and the chromaticity largely deviates from the predetermined chromaticity range.

A metal halide lamp according to a third aspect of the present invention is the metal halide lamp according to the first or second aspect, in which the total luminous flux is at least 22 when turned on at 35 W.
It is characterized by being 05 lm.

The present invention defines the lower limit of the total luminous flux in a metal halide lamp that does not essentially contain mercury. The lower limit value is clear from the description in Examples below. The above total luminous flux is
When converted into a lamp efficiency, it is 63 lm / W, and if the lamp efficiency is equal to or higher than this lower limit value, the lamp efficiency of a conventional metal halide lamp for headlamps containing mercury is 89 lm.
It can be said that it is almost comparable to / W. According to the present invention, as is clear from the description in the embodiments other than the above-mentioned embodiments, it is possible to obtain a metal halide lamp having a lamp efficiency equal to or higher than the lower limit value.

That is, according to the present invention, as will be described later, in each of the examples, the lamp efficiency of the comparative example corresponding to the conventional example and the minimum value and the maximum value of each lamp of the example are shown in Table 2. It is as shown collectively.

[0098]

[Table 2] Example No. Listing Table Minimum value (lm / W) Maximum value (lm / W) of each lamp Comparative example (lm / W) 1 3 72 78 80 2 6 9 91 98 101 3 3 8 63 63 68 71 4 9 106 108 101 5 10 76 76 77 71 71 6 11 106 108 101 101 7 12 76 79 79 71 8 13 96 98 98 101 9 16 16 78 81 87 87 10 20 90 94 94 89 11 21 21 79 82-12 12 22 92 92 94 86 13 25 25 80 27 88 89 94 As can be understood from Table 2, in the present invention, not only can a lamp efficiency comparable to that of a conventional metal halide lamp in which mercury is sealed but also a heat insulating means or cesium is provided. It is also possible to obtain a higher lamp efficiency than before by adding a structure such as adding a Cs halide.

A metal halide lamp according to a fourth aspect of the present invention is the metal halide lamp according to any one of the first to third aspects, wherein the rare gas has a filling pressure of xenon of 1 or less.
It is characterized by being above atmospheric pressure.

The present invention also improves the luminous flux rising characteristic of the metal halide lamp by setting the pressure of the rare gas to be 1 atm or more. A good luminous flux rising characteristic is extremely important in a headlight of a moving body such as an automobile. The pressure is preferably 1 to 10 atm or 1 to 15 atm.

A metal halide lamp lighting device according to a fifth aspect of the present invention is the metal halide lamp according to any one of the first to fourth aspects; and a current of at least three times the rated lamp current is supplied to the metal halide lamp immediately after the metal halide lamp is turned on. The lighting circuit is configured to reduce the current with the passage of time.

The present invention defines a metal halide lamp lighting device which satisfies the luminous flux rising characteristics required for a vehicle headlight. That is, since the lighting circuit is configured to supply a large current to the metal halide lamp as described above immediately after lighting the metal halide lamp, the luminous flux rises quickly even though mercury is not sealed in the metal halide lamp. And keep the lamp voltage of the metal halide lamp high,
It is possible to obtain a lamp efficiency comparable to that of a conventional metal halide lamp in which mercury is sealed.

The lighting circuit may be either an AC operation or a DC operation.

An illumination device according to a sixth aspect of the present invention comprises: an illumination device main body; and the metal halide lamp according to any one of the first to fourth aspects, which is supported by the illumination device main body. .

The present invention is applicable to all devices using the metal halide lamp according to any one of claims 1 to 4 for some illumination purpose. In the case of the short arc type, in particular, an illumination device used in combination with an optical system such as a reflecting mirror and / or a lens, such as a liquid crystal projector, an overhead projector, a headlight of a moving body such as an automobile, an optical fiber illumination device, a spotlight, etc. It is suitable for lighting equipment for stores.

In the case of the long arc type, various lighting fixtures for general lighting such as downlights, direct ceiling lights,
It can be used for road lighting equipment, tunnel lighting equipment, floodlights, and the like, as well as display devices and the like.

[0107]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment of Metal Halide Lamp of the Present Invention> FIG. 1 is a central sectional front view showing a first embodiment of a metal halide lamp of the present invention. In the figure, 1 is an airtight container, 2 is an electrode, 3 is a sealing metal foil, 4
Is an external lead wire. The present embodiment is a small-sized, short-arc type metal halide lamp suitable for headlights.

The airtight container 1 is made of quartz glass and formed into a spheroidal shape, and is integrally provided with a pair of elongated sealing portions 1a, 1a at both ends in the major axis direction of the ellipse.

In the electrode 2, the electrode shaft 2a and the tip of the electrode shaft 2a are slightly projected into the airtight container 1. Electrode shaft 2
The base portion of a is welded to one end of the sealing metal foil 3 in the sealing portion 1a. No electrode coil is attached to the tip of the electrode 2.

The sealing metal foil 3 is made of molybdenum foil,
The external lead wire 4 is welded to the other end while being hermetically embedded in the sealing portion 1a.

A rare gas, a first halide and a second halide are enclosed as a discharge medium in the hermetic container 1.

The hermetic container 1, the pair of electrodes 2 and 2 and the discharge medium constitute an arc tube IB.

EXAMPLE 1 Example 1 is the same as the structure shown in FIG. 1 according to the first embodiment of the metal halide lamp of the present invention.
The main specifications are as follows.

Airtight container 1: inner diameter 4 mm, inner volume 0.0
5 cc Distance between electrodes: 4.2 mm Discharge medium: Noble gas = Xenon at 1 atm First halide = Scandium iodide ScI ₃ 0.
14 mg + sodium iodide NaI 0.86 mg Second halide = halide 1 mg shown in Table 3 For the metal halide lamp of Example 1, input power 3
The lamp voltage, the luminous efficiency, the average color rendering index (hereinafter referred to as "color rendering") Ra and the color temperature were measured together with that of the comparative example shown below, and the results are shown in Table 3 together. Show. The comparative example has the same specifications as the example 1 except that 1 mg of mercury was filled instead of the second halide.

[0115]

[Table 3] Lamp 2nd halogenide Lamp voltage (V) Luminous efficiency (lm / W) Color rendering (Ra) Color temperature (K) 1 (Comparative example) -83 80 63 4120K 2 AlI ₃ 62 78 65 3860K 3 _{FeI 2 70 73 71 4210K 4 ZnI} 2 75 78 65 3830K 5 SbI 3 63 75 66 3790K 6 MnI 2 55 72 68 3950K 7 CrI 2 58 74 65 3860K 8 GaI 3 59 76 66 3760K 9 ReI 3 61 78 64 3840K table 3 As is clear from the above, in Example 1, the lamp voltage was 50 V or higher, and although the luminous efficiency was slightly lower than that of the conventional example, the color rendering property tended to improve.

From the above, it can be evaluated that the characteristics of Example 1 in the steady state are almost the same as those of Comparative Example 1.

Next, the lamp 3 in Example 1 in Table 3 was used.
And the lamp 1 (comparative example), input power 15W, 2
Table 4 shows the results of measuring the color rendering properties and the color temperature when the light was turned on at 0 W, 25 W and 30 W.

[0118]

Table 4 Lamp 15W 20W 25W 30W 1 (Comparative example) Color rendering (Ra) 40 45 58 61 Color temperature (K) 5640 4970 4630 4350 3 Color rendering (Ra) 63 64 66 66 69 Color temperature (K) 4530 4440 4310 4240 As is apparent by comparing and comparing Table 3 and Table 4, in the comparative example of the lamp 1, when the input is changed from 35 W (see Table 2) to 15 W, the color temperature changes by 1520 K and the color rendering property changes by 23. did. In this case, the change is too large to actually control the light.

On the other hand, in Example 1, the change in color temperature was 320 K and the change in color rendering was only 8, and dimming is sufficiently possible.

Next, Table 5 shows the results of evaluation of restart in Example 1.

As the lamp 10, a comparative example having the same specifications as the lamp 3 except that xenon Xe was enclosed in 100 Torr was manufactured, and the result of measuring the restart voltage is shown.

[0122]

Table 5 Lamp Restart Voltage (kV) 1 (Comparative Example) 14 3 7 10 3 As shown in Table 5, in Example 1, the restart voltage is half that of the comparative example. Particularly, in the lamp 10 in which the filling pressure of the rare gas is lowered and the luminous flux rising characteristic is not important, a remarkable improvement was observed.

FIG. 2 shows that in Example 1, xenon Xe was used.
3 is a graph showing the relationship between the light-filling time and the filling pressure of the light. In the figure, the horizontal axis represents the Xe enclosure pressure (atmospheric pressure) and the vertical axis represents the luminous flux rise time (seconds).

As is clear from the figure, when the filling pressure is 1 atm or higher, the luminous flux rise time is remarkably shortened, but when it is less than 1 atm, it is remarkably long.

FIG. 3 is a graph showing the relationship between the lamp voltage and the amount of enclosure when iron iodide FeI ₂ was used as the second halide in Example 1. In the figure, the horizontal axis represents the amount of FeI ₂ enclosed (mg / cc), and the vertical axis represents the lamp voltage (V).

From the figure, it can be seen that the lamp voltage exceeds 20 V when the inner volume of the airtight container is 1 cc or more and the lamp voltage exceeds 30 V when the inner volume is 1 mg or more. Although not shown, unvaporized Fe is present when the internal volume of the airtight container is 200 mg or more per cc.
Since I2 absorbs light, the luminous efficiency is reduced.

FIG. 4 is a front view showing a second embodiment of the metal halide lamp of the present invention. In the present embodiment, an arc tube IB, which is a small-sized short arc type metal halide lamp similar to that shown in FIG. 1, is attached to the headlamp of a moving body shown in FIG. In the figure, OB is an outer tube, B is a base, and IT is an insulating tube.

The outer tube OT has a UV-cutting property, contains the arc tube IB therein, and has the sealing portion 1 at both ends.
Although it is fixed to a, it is not airtight and communicates with the outside air. One of the sealing portions 1a is erected on the base B. The external lead wire 4 led out from the other end extends parallel to the outer tube OB, is introduced into the base B, and is connected to a terminal (not shown).

The insulating tube IT covers the external lead wire 4.

FIG. 5 is a front view showing a third embodiment of the metal halide lamp of the present invention. In the figure, IB
Is an arc tube, 42 is a first support band, 43 is a first conductor frame, 44 is a flare stem, 45 is a bimetal and a starting resistor, 46 is a second support band, 47 is a second conductor frame,
48 is a conducting wire, OB is an outer tube, and B is a base.

The arc tube IB seals a pair of main electrodes at one end of an airtight container 41 made of an elongated quartz glass tube and one auxiliary auxiliary electrode close to one of the main electrodes.

The first support band 42 holds the pinch seal portion on the upper side in the drawing of the arc tube IB and is fixed to the first conductor frame 43.

The first conductor frame 43 is fixed to the flare stem 44 and applies a voltage to the upper main electrode of the arc tube IB.

The flare stem 44 is sealed to the neck portion of the outer tube 49.

The bimetal and the starting resistor 45 form a starting circuit and apply a voltage of the opposite polarity to the main electrode adjacent to the starting auxiliary electrode at the time of starting.

The second support band 46 holds the lower pinch seal portion in the figure of the arc tube IB and is fixed to the second conductor frame 47.

The second conductor frame 47 is fixed to the top portion of the outer tube OB.

The conducting wire 48 has one end connected to the lead-in wire of the flare stem 44 and the other end connected to the second support band 46, and the other main electrode of the arc tube 41 via the second conductor frame 47. Connected to.

The outer tube OB has the arc tube IB, the bimetal and the starting resistor 45 sealed inside by the above-mentioned structure. Although not shown, an initial getter is attached to adsorb the impure gas inside.

[Embodiment 2] Embodiment 2 is the same structure as the third embodiment of the metal halide lamp of the present invention shown in FIG.
The main specifications are as follows.

Airtight container 1: inner diameter 20 mm, internal volume 0.
05 cc Distance between electrodes: 42 mm Discharge medium: Noble gas = Argon 20 Torr First halide = Scandium iodide ScI ₃ 3 m
g + sodium iodide NaI 15 mg Second halide = halide 20 mg shown in Table 6 15 kinds of metal halide lamps were manufactured with the above specifications. Of these lamps, in the lamp 14, 5 mg of ZnI ₂ was added in addition to the specifications of the lamp 2. Also, the lamp 15
In addition to the specifications of Lamp 10, 5 mg of FeI ₂ was added. All of them attempted to increase the lamp voltage by using a plurality of second halides.

For comparison, except that 40 mg of mercury was filled in place of the second halide as a comparative example.
A metal halide lamp having the same specifications as in Example 2 was manufactured.

Table 6 shows the results obtained by measuring the lamp voltage, the luminous efficiency, the color temperature and the color rendering property of the lamp of Example 2 and the comparative example, which were lit at a constant lamp input of 400 W, together with those of the comparative example.

[0143]

[Table 6] Lamp Second halogen compound Lamp voltage (V) Luminous efficiency (lm / W) Color temperature (K) Color rendering (Ra) 1 (Comparative example)-132 101 4320 62 2 AlI ₃ 112 96 4120 65 3 _{FeI 2 118 95 4510 68 4 ZnI} 2 120 98 4160 65 5 SbI 3 114 94 4040 69 6 MnI 2 83 93 4210 64 7 CrI 2 109 96 4260 68 8 GaI 3 125 97 4130 67 9 ReI 3 103 91 4240 69 10 MgI _{2 78 95 4140 66 11 CoI 2} 118 95 4480 68 12 NiI 2 109 95 4410 69 13 beI 2 95 93 4210 63 14 AlI 3 + ZnI 2 137 97 4150 65 15 MgI 2 + FeI 2 105 95 4210 67 embodiment The electrical properties of 2 will be described. As is clear from Table 6, the lamp voltage of the comparative example is determined by the amount of mercury enclosed.

On the other hand, the lamp voltage of the second embodiment is
It is mainly controlled by the evaporation amount of the second halide. In this case, if the heat insulating means is provided in the arc tube IB,
For example, even in the lamp 3 in which iron iodide FeI ₂ is enclosed, it is possible to obtain the amount of evaporation required to exhibit the required lamp voltage.

Therefore, by appropriately setting the degree of heat retention of the arc tube IB, the same lamp voltage as in the comparative example can be obtained.

Next, the emission characteristics will be described. In the lamp 3, the emission of iron Fe, which is the second metal halide, is slightly observed in the visible region, but the emission of mercury is lost. The luminous efficiency is slightly lowered, but the color rendering is slightly increased. In addition, if iron halide is enclosed alone,
It was found that strong UV radiation is emitted, but by encapsulating together with the first halide, the intense UV radiation is significantly weakened. Furthermore, the emission of ultraviolet rays is also reduced by the mixed use with another second halide.

As described above, also in the long arc type metal halide lamp, the electric characteristics and the light emitting characteristics of the lamp can be made equal to those of the conventional technique in which mercury is enclosed, without using mercury having a large environmental load. Was confirmed.

Further, as seen in the lamps 14 and 15, it was also confirmed that the lamp voltage was adjusted to a level similar to that of mercury by using a plurality of metals in combination as the second halide.

Next, the metal halide lamp of Example 2 was used with lamp powers of 350 W, 300 W, 250 W and 200.
Table 7 shows the changes in the color rendering properties and the color temperature when the light is turned on in comparison with those of the comparative example. The numbers in the lamp section indicate the same lamps as those in Table 6.

[0150]

[Table 7] Lamp 200W 250W 300W 350W 1 Color rendering (Ra) 38 46 54 60 (Comparative example) Color temperature (K) 6010 5630 5160 4530 2 Color rendering (Ra) 60 61 62 64 Color temperature (K) 4560 4450 4220 4100 As is clear from Table 7, in the comparative example, the color temperature remarkably increases as the lamp power decreases, and the color rendering properties largely decrease.

On the other hand, the lamp 2 of Example 2 has very little change in color rendering and color temperature.

As described above, according to the second embodiment, the color rendering property and the color temperature hardly change even if the lamp power changes.
It was confirmed that dimming is possible.

FIG. 6 is a graph showing the spectral distribution of a conventional long arc type metal halide lamp. In the figure,
The horizontal axis is the wavelength (nm) and the vertical axis is the relative radiant power (%)
Are shown respectively.

This metal halide lamp is the lamp 1 in Table 6, and main emission line spectra are indicated by arrows and chemical symbols of the elements emitted above them. That is,
The light emitted from this lamp is mainly composed of scandium Sc, sodium Na, and mercury Hg.

Then, when the lamp input is reduced,
Scandium iodide ScI3 and sodium iodide NaI
Has a low vapor pressure, so the amount of evaporation decreases.

On the other hand, since mercury has a high vapor pressure, even if the lamp input is lowered to 200 W, all of it is vaporized. That is, when the lamp power is reduced, the emission of light by mercury becomes relatively dominant and the color temperature becomes higher.
As described above, in the comparative example, a large change in the color temperature occurs when the lamp power is changed and light control is performed.

In contrast, in Example 2, when the lamp power was reduced, sodium Na and scandium S
c decreases with the same ratio. Moreover, since the second halide metal emits a small amount of light in the visible region, it has almost no influence on the light emission characteristics of the metal halide lamp. Therefore, in Example 2, even if the lamp power was reduced, the change in color temperature was small. Table 6 again
And returning to Table 7, the lamp power is 400 W.
When the color temperature was changed from 1 to 200 W, the color temperature changed by 1690 K in the comparative example, whereas it changed only by 440 K in the example 2.

FIG. 7 is a front view showing a fourth embodiment of the metal halide lamp of the present invention. In the figure, 5
1 is an airtight container, 52 is an electrode, 53 is a heat insulating means, IB is between light emitting, OB is an outer tube, 55 is a support band, B is a base, 57
Is the lead-in line.

The airtight container 51 is made of quartz glass. Pinch seal portions 51 a are formed at both ends of the airtight container 51.

The electrode 52 is located at the center of the reduced diameter portion at both ends in the airtight container 51, and the base end is embedded in the pinch seal portion 51a, whereby the airtight container 51 is formed.
Is fixed against.

The heat retaining means 53 is arranged on the outer surface of the portion of the airtight container 51 surrounding the electrodes.

The arc tube IB is mainly composed of an airtight container 51, a pair of electrodes 52 and 52, and a discharge medium.

The outer tube OB is formed by sealing both ends of a quartz glass cylindrical body with pinch seal portions 54a, and by providing support bands 55, 55, an airtight seal is formed while forming a relatively narrow gap inside. It contains a container 51.

The mouthpieces B are attached to the pinch seal portions 54a at both ends of the outer tube OB by means of mouthpiece cement.

The introduction line 57 connects the pinch seal portion 54a of the outer tube OB and the pinch seal portion 51a of the airtight container 51.

[Third Embodiment] In the third embodiment, in the structure shown in FIG. 7 of the fourth embodiment of the metal halide lamp of the present invention,
The main specifications are as follows.

Airtight container 1: Inner diameter 12 mm Distance between electrodes: 17 mm Discharge medium: Noble gas = Argon 20 Torr First halide = Scandium iodide ScI ₃ 1.
5 mg + sodium iodide NaI 7.5 mg Second halide = halide 20 mg shown in Table 8 For comparison, as a comparative example (Lamp 1 in Table 8), 12.5 mg of mercury was used instead of the second halide. A metal halide lamp having the same specifications as in Example 3 except for the above was manufactured.

Table 8 shows the results of measuring the lamp voltage, the luminous efficiency, the color temperature, and the average color rendering index Ra of each of the manufactured lamps which were turned on with a lamp input of 100 W.

[0168]

[Table 8] Lamp Second halogen compound Lamp voltage (V) Luminous efficiency (lm / W) Color temperature (K) Color rendering (Ra) 1 (Comparative example) -122 71 4120 61 2 AlI ₃ 112 67 4140 65 3 _{FeI 2 110 66 4480 67 4 ZnI} 2 111 68 4160 64 5 SbI 3 106 63 4140 68 6 MnI 2 80 66 4250 64 7 CrI 2 109 66 4230 68 8 GaI 3 115 67 4180 67 9 CoI 2 110 65 4380 66 10 NiI ₂ 105 65 4460 68 As is apparent from Table 8, it was confirmed that also in Example 3, the electric characteristics and the light emitting characteristics could be made equal to those of the lamp in which mercury is enclosed, without using mercury.

Next, in the third embodiment, the pressure during the lighting of the lamp will be described with reference to the lamp 1 and the lamp 2. The pressure while the lamp 1 is on is the amount of mercury (moles).
And the pressure of the lamp 2 is aluminum iodide AlI ₃
It depends on the quantity in proportion. From the number of moles, the lamp 1 and the lamp 2 have a ratio of about 5: 1, and the pressure during lighting is also 5: 1. Estimated pressure of lamp 1 is about 1
Since the pressure is 5 atm, the lamp 2 has a pressure of about 3 atm.

The metal halide lamp has a problem that the quartz glass becomes brittle due to the reaction between the quartz glass, which is the material of the arc tube, and the halide during long-term lighting, so that the quartz glass breaks without being able to withstand the pressure in the arc tube.

As can be understood from the above, in Example 3, since the pressure during lighting is low by essentially not enclosing mercury, the risk of explosion is greatly reduced.

Further, in Example 3, an experiment using the lamp 1 and the lamp 2 was carried out for the chromaticity rising characteristic. The results will be described with reference to the results.

In the experiment, the rising of the luminous flux is 8 after the switch is turned on.
A lighting circuit was used which was set to 100% in seconds. Then, the spectral distribution in the visible range of the lamp 1 and the lamp 2 was measured every second after the switch was turned on using the instantaneous spectroscope, and the chromaticity coordinates of each time point were calculated based on the result.

FIG. 8 is a chromaticity diagram showing the chromaticity rising characteristics in Example 3 in comparison with those in Comparative Example. In the figure, the horizontal axis represents the x-coordinate of the chromaticity coordinate, and the vertical axis represents the y-coordinate, respectively, and the coordinate area surrounded by the frame is the white color of the headlight for automobiles defined by the Japanese Industrial Standards (JIS). The area is shown. In the figure, a curve C shows the chromaticity rising characteristic of the third embodiment, and a curve D shows the chromaticity rising characteristic of the comparative example. In addition, the number attached beside the measured value of each curve represents the elapsed time after the switch is turned on in seconds.

In the case of the comparative example, since only mercury is initially emitted, the chromaticity rising characteristic is poor as shown by the curve D, and the JI
It is outside the white area defined by S, and it takes about 1 minute to enter the white area.

On the other hand, in the case of Example 3, since sodium Na and scandium Sc emit light from the beginning, they are in the white region.

Therefore, Example 3 shows that it is suitable for applications in which both the rise of luminous flux and the rise of chromaticity after switching on are required to be fast.

Example 4 Example 4 (lamps 2 to 4b in Table 9) is
In the structure shown in FIG. 5 according to the third embodiment of the metal halide lamp of the present invention and in the size shown in Example 2, the following were enclosed as the discharge medium.

First halide = scandium iodide ScI 3 ₃ mg + sodium iodide NaI 15 mg Second halide = halide 20 m shown in Table 12
g Third halide = Cesium iodide CsI ₃ mg Noble gas = Argon 20 Torr As a reference example (a of Lamps 2 to 4 in Table 9), a metal halide having the same specifications as in Example 4 except that cesium iodide CsI is not enclosed. I made a lamp.

Further, as a comparative example (a of lamp 1 in Table 9), Example 4 was used except that cesium iodide CsI was not enclosed.
A metal halide lamp was manufactured in which 40 mg of mercury was sealed in addition to the discharge medium having the same specifications. In addition, as a reference example (b of the lamp 1 in Table 9), one having the same specifications as the comparative example but additionally containing cesium iodide CsI was manufactured.

Table 9 shows the results obtained by measuring the luminous efficiency and the color rendering index (average salt color evaluation number) Ra of Example 4, the reference example and the comparative example, with the lamp input at 400 W and constant lighting. In each of the example 4, the reference example, and the comparative example, nitrogen is contained in the outer tube OB that houses the arc tube IB.
Enclosed in 00 Torr.

[0181]

[Table 9] Lamp CsI Second halogenide Luminous efficiency (lm / W) Color rendering (Ra) 1 (Comparative example) a None-101 62 b Yes-98 61 2 a No AlI ₃ 96 65 b Yes Id 106 67 3 a None ZnI ₂ 94 68 b Yes Id 108 70 4 4 a No GaI ₃ 97 67 b Yes Id 107 70 As is clear from Table 9, in the comparative example in which mercury is enclosed, cesium iodide CsI is included. However, the luminous efficiency is slightly reduced.

Further, in the reference example in which mercury is not enclosed (a in lamps 2 to 4 in Table 9), the luminous efficiency is lower than that in the comparative example in which mercury is enclosed.

On the other hand, Example 4 (Lamp 2 in Table 9)
In b) of 4 to 4, the luminous efficiency is improved and becomes better than that of the comparative example. This is because in the comparative example (lamp 1 in Table 9), mercury is also emitted in addition to the emission of sodium Na and scandium Sc, and mercury has a low emission efficiency as described above. On the other hand, in Example 4, the energy consumed for light emission is not distributed to mercury,
Luminous efficiency is clearly improved because all of the light is emitted by the luminescent metal.

Further, in Example 4, the color rendering property is also slightly improved as compared with the reference example (a of lamps 2 to 4).

[Embodiment 5] Embodiment 5 is the same structure as the third embodiment of the metal halide lamp of the present invention shown in FIG.
The inner diameter of the airtight container 41 of the arc tube IB is 12 mm, and the distance between the electrodes is 17 mm. Then, the following was enclosed as a discharge medium.

First halide = scandium iodide ScI ₃ 1.5 mg + sodium iodide NaI 7.5 mg Second halide = halide shown in Table 10 5 mg Third halide = cesium iodide CsI 1.5 mg Rare Gas = Argon 20 Torr As a reference example (a in Lamps 2 to 4 in Table 10), a metal halide lamp having the same specifications as in Example 5 except that cesium iodide CsI was not enclosed was manufactured.

Further, a comparative example (a of lamp 1 in Table 10)
As a result, a metal halide lamp was produced in which 12.5 mg of mercury was enclosed in addition to the enclosure having the same specifications as in Example 5 except that cesium iodide CsI was not encapsulated. In addition, as a reference example (b of the lamp 1 in Table 10), one having the same specifications as the comparative example and additionally containing cesium iodide CsI was manufactured.

Table 10 shows the results obtained by measuring the luminous efficiency and the color rendering properties (average salt color evaluation number) Ra of Example 5, the reference example and the comparative example, with the lamp input of 100 W and constant lighting. In each of the example 5, the reference example and the comparative example, the inside of the outer tube OB accommodating the arc tube IB was filled with nitrogen.
Enclosed in 00 Torr.

[0188]

[Table 10] Lamp CsI Second halogenide Luminous efficiency (lm / W) Color rendering (Ra) 1 (Comparative example) a None-71 61 b Yes-69 60 2 a None AlI ₃ 67 65 b Yes Yes 77 66 3 a None NiI ₂ 65 68 b Yes Same as above 76 68 4 a No MnI ₂ 68 64 b Yes Same as above 77 63 Example 5 also showed the same tendency as in Example 4.

[Sixth Embodiment] In the sixth embodiment, in the structure shown in FIG. 5 according to the third embodiment of the metal halide lamp of the present invention,
The airtight container 41 of the arc tube IB has a diameter of 20 mm and a distance between electrodes of 42 mm. 10 ^-4 Torr in the outer tube OB
The following vacuum was applied. Then, the following was enclosed as a discharge medium.

First halide = scandium iodide ScI 3 ₃ mg + sodium iodide NaI 15 mg Second halide = halide 20 mg shown in Table 11 Noble gas = Argon 20 Torr Reference example (a in Lamps 2 to 4 in Table 11) ) As the outer tube OB
A metal halide lamp having the same specifications as in Example 6 was manufactured except that 400 Torr of nitrogen was sealed as a gas.

Further, a comparative example (a of lamp 1 in Table 11)
In addition, 40 mg of mercury was further enclosed, and gas was enclosed in the outer tube OB in the same manner as above, and its reference example (Table 11).
As a lamp 1 b) of No. 1, a vacuum lamp was manufactured instead of the gas.

Table 11 shows the results obtained by measuring the luminous efficiency and the color rendering properties (average salt color evaluation number) Ra of Example 6, the reference example and the comparative example, with the lamp input at 400 W and constant lighting.

[0192]

[Table 11] Second halogenide in lamp outer tube Luminous efficiency (lm / W) Color rendering (Ra) 1 (Comparative example) a gas-101 62 b vacuum-103 63 2 a gas AlI ₃ 96 65 b b vacuum same as above 106 67 3 a gas FeI ₂ 95 68 b vacuum same as above 107 70 4 a gas GaI ₃ 97 67 b vacuum same as above 108 69 As is clear from Table 11, a comparative example in which mercury is enclosed (a in lamp 1 of Table 11). In the reference example (b of the lamp 1 in Table 11), the luminous efficiency and the color rendering Ra are not so different when the outer tube OB is filled with gas in a vacuum.

On the other hand, when mercury is not sealed, a reference example (lamp 2 to lamp 2) in which gas is sealed in the outer tube OB.
In 4a), the luminous efficiency is lower than that of the comparative example (lamp 1a) in which mercury is enclosed.

In Example 6 (b of Lamps 2 to 4) in which the inside of the outer tube OB was evacuated, the luminous efficiency was clearly superior to that of the Comparative Example. This is sodium N in the comparative example.
This is because mercury also emits light in addition to the light emitted from a and scandium Sc, and mercury has low emission efficiency as described above. In Example 6, all the energy is passed to the luminescent metal. In addition, the color rendering properties of Example 6 are slightly excellent. A tendency similar to that in Examples 4 to 5 was recognized in Example 6 as well.

Example 7 Example 7 is the same as the structure shown in FIG. 5 according to the third embodiment of the metal halide lamp of the present invention.
The airtight container 41 of the arc tube IB has a diameter of 12 mm and a distance between electrodes of 17 mm. 10 ^-4 Torr in the outer tube OB
The following vacuum was applied. Then, the following was enclosed as a discharge medium.

First halide = scandium iodide ScI ₃ 1.5 mg + sodium iodide NaI 7.5 mg Second halide = halide 5 mg shown in Table 12 Noble gas = Argon 20 Torr Reference example (Lamp 2 in Table 12) ~ 4 a), the outer tube OB
A metal halide lamp having the same specifications as in Example 7 was manufactured except that 400 Torr of nitrogen was enclosed as a gas.

Further, a comparative example (a of Lamp 1 in Table 12)
As the above, 12.5 mg of mercury was further enclosed, and a gas was enclosed in the outer tube OB in the same manner as above, and a reference example (b of the lamp 1 in Table 12) in which vacuum was used instead of gas was produced. did.

Table 12 shows the results of measuring the luminous efficiency and the color rendering index (average salt color evaluation number) Ra of Example 7, the reference example and the comparative example, which were lit at a constant lamp input of 100 W.

[0198]

[Table 12] Second halogenide in lamp outer tube Luminous efficiency (lm / W) Color rendering (Ra) 1 (Comparative example) a gas-71 61b vacuum-74 642a gas AlI ₃ 67 65 b b vacuum ibid. 77 67 3 a gas NiI ₂ 65 68 b vacuum ibid. 76 70 4 a gas ZnI ₂ 68 64 b vacuum ibid. 79 66 In Example 7, a tendency similar to that in Example 6 was observed.

FIG. 9 is a front view showing a fifth embodiment of the metal halide lamp of the present invention. In the figure, the same parts as those in FIG. The present embodiment is different in that it is a long arc type and is configured for direct current lighting.

That is, the arc tube IB has the airtight container 4
The cathode 41a and the auxiliary electrode 41b are sealed at one end of the No. 1 and the anode 41c is sealed at the other end, and the discharge medium is sealed inside.

The cathode 41a is formed by winding a coil around the inner end of the electrode rod.

The auxiliary electrode 41b is made of a tungsten wire.

The tip of the anode 41c is formed to have a large diameter.

Cathode 41a, auxiliary electrode 41b and anode 41
The c is connected to a sealing foil 41d made of molybdenum and airtightly embedded in the sealing portion 41e.

The anode 41c is composed of a sealing foil 41e and a conductor 48 '.
And it is connected to the base 50 via the flare stem 44.

The auxiliary pole 41b is connected to the conductor 48 'via a starting resistor 45'.

The cathode 41a is connected to the base B through the conductor 48 ″ and the flare stem 44.

At the end of the arc tube IB on the cathode 41a side, a heat insulating film 41f containing platinum as a main component is formed.

The outer tube OB is made of a glass tube and the inside is evacuated.

Example 8 Example 8 is the same as the structure shown in FIG. 9 of the fifth embodiment of the metal halide lamp of the present invention.
The airtight container 41 of the arc tube IB has an inner diameter of 18 mm and a cathode 41a.
Is formed by winding a tungsten wire having a diameter of 0.4 mm around the inner end of a tungsten rod containing thorium having a diameter of 1 mm and a length of 15 mm, the auxiliary electrode 41b is a 0.3 mm tungsten wire, and the tip side of the anode 41c is 1.8 mm. 1.2 on the base side
It is made of a tungsten rod formed to have a length of 40 mm, and the distance between the electrodes is 40 mm. The inside of the outer tube OB having an inner diameter of 40 mm was evacuated to 10 ⁻⁴ Torr or less. Then, the following was enclosed as a discharge medium.

First halide = scandium iodide ScI 3 ₃ mg + sodium iodide NaI 15 mg Second halide = halide 20 mg shown in Table 13 Noble gas = 280 Torr Further, instead of the second halide as a comparative example. Mercury 4
A lamp having the same specifications as in Example 8 except that 0 mg was enclosed was manufactured.

In this way, 5 lamps each of Example 8 and 3 lamps of Comparative Example were manufactured and rated output 360
Table 13 shows the average values of the results obtained by measuring the lamp voltage (V), the luminous efficiency (lm / W), the color rendering properties (average color rendering index) Ra, and the color temperature (K) after the DC lighting at constant W. .

[0212]

[Table 13] Lamp No. 2 halogenide Lamp voltage (V) Luminous efficiency (lm / W) Color rendering (Ra) Color temperature (K) 1 (Comparative example) -132 101 62 4320 2 AlI ₃ 112 96 65 4120 3 ZnI ₂ 120 98 65 4160 4 GaI ₃ 125 97 67 4130 As is clear from Table 13, Example 8 has a slightly lower luminous efficiency than the comparative example, but other characteristics are comparable.

Next, with respect to Lamp 3 (Example 8) and Lamp 1 (Comparative Example) in Table 13, the lamp input was set to 200.
Table 14 shows the results of measuring the color rendering properties Ra and the color temperature (K) at W, 250 W, and 300 W.

[0214]

[Table 14] Lamp item 200W 250W 300W 1 (Comparative example) Ra 38 46 57 Color temperature (K) 6010 5680 5210 3 Ra 59 62 63 Color temperature (K) 4500 4210 4150 As is apparent from Table 14, the comparative example is , The color rendering Ra decreased and the color temperature (K) increased as the lamp input decreased below the rated value. On the other hand, in Example 8, the change was small. That is, in the eighth embodiment, dimming is possible.

For each of the lamps of Example 8 and Comparative Example, 2% at 400 W, which is 10% higher than the rating.
The presence or absence of a rupture of the arc tube when horizontal lighting was performed under the condition of lighting for 10 minutes and extinguished for 10 minutes, and measurement of the instantaneous restart voltage after extinguishing for 2 seconds during rated lighting were performed. As a result, the arc tube did not burst even after lighting for about 2500 hours, and the average value of the instantaneous restart voltage was as shown in Table 15.

[0216]

[Table 15] lamps second halide restart voltage (kV) 1 (Comparative _{Example) - 1.8 2 AlI 3 0.89 3} ZnI 2 0.8 4 GaI 3 1.0 Example 8, restarts The voltage is significantly lower than that of the comparative example.

Further, in Comparative Example, remarkable color separation occurred during lighting, but in Example 8, some color separation was recognized, but it was practical.

[Embodiment 9] In the structure shown in FIG. 1 of the metal halide lamp of the present invention according to the first embodiment and in the same size as that of Embodiment 1, the following are filled as a discharge medium.

First halide = scandium iodide ScI ₃ 0.14 mg + sodium iodide NaI 0.7 mg Second halide = halide shown in Table 16 0.4 mg Noble gas = xenon 5 atm Also, as a comparative example. Further, a product containing 1 mg of mercury was manufactured.

Then, for Example 9 and Comparative Example, the lamp voltage, the luminous efficiency, the color rendering properties (average color rendering index) Ra and the color temperature were measured by lighting with the lamp input kept at 35 W and the results are shown in Table 16. Show.

[0220]

[Table 16] Lamp Second halogen compound Lamp voltage (V) Luminous efficiency (lm / W) Color rendering (Ra) Color temperature (K) 1 (Comparative example) -83 87 63 4120 2 AlI ₃ 65 81 68 3960 3 FeI ₂ 70 79 71 4210 4 ZnI ₂ 75 81 65 3830 5 MnI ₂ 66 81 65 4230 6 GaI ₃ 76 78 65 4330 Although the lamp voltage of the comparative example is determined by the amount of mercury enclosed, in Example 9, the second halogen is used. Determined by the evaporation amount of the compound. Therefore, by keeping the temperature of the arc tube good, it is possible to easily obtain the required lamp voltage. As can be understood from Table 16, in Example 9, the lamp voltage is lower than that of the conventional example, but is 50 V or more, and this type of small metal halide lamp is lit by using an electronic lighting circuit. So practically no problem. In terms of characteristics,
Although the luminous efficiency is slightly inferior, the color rendering property tends to be improved because the added metal (aluminum Al, etc.) emits a little light in the visible region.

FIG. 10 is a chromaticity diagram showing the chromaticity rising characteristics of the lamp 2 of Table 16 in Example 9 and the lamp 1 of Comparative Example. The part surrounded by a frame in this chromaticity diagram shows the white chromaticity range described in the explanation of automobile lamps in Japanese Industrial Standard JIS D 5500-1984. A curve E in the figure shows the chromaticity rising characteristic of the ninth embodiment. A curve F shows the chromaticity rising characteristic of the comparative example. The number given near the measurement point of each curve is
It shows the elapsed time (seconds) after the start of lighting. In these measurements, each lamp was lit by using a lighting circuit set so that a lamp current of 2.6 A was made to flow immediately after the power was turned on, and then the current was gradually reduced to a constant lamp power of 35 W. went.

As is apparent from the figure, in Example 9, the light emission was within the white range within 0.5 seconds after lighting, whereas in the comparative example, it was within the white range after 18 seconds.

Next, Table 17 shows the results of measuring the average color rendering index Ra and the color temperature (K) when the lamps 2 and 1 in Table 16 were turned on with the lamp inputs 15W, 20W, 25W and 30W.

[0224]

[Table 17] Lamp item 15W 20W 25W 30W 1 (Comparative example) Ra 40 45 58 61 Color temperature (K) 5640 4970 4630 4350 2 Ra 63 64 65 65 66 Color temperature (K) 4280 4220 4110 4040 In Table 17, Lamp 1 In (Comparative Example), since the vapor pressure of mercury is high, all the mercury has evaporated even if the lamp input is reduced to 15 W. For this reason, as the lamp input decreases, the emission of mercury becomes dominant and the color temperature rises. On the contrary, the color rendering property decreases, so the comparative example is suitable for dimming in a practical sense. You can understand that there is nothing.

On the other hand, the lamp 2 (Example 9) is
It can be understood that there is little change in the color rendering property and the color temperature, and it is suitable for dimming.

Further, Table 18 shows the result of measurement of the restart voltage at the momentary restart (hot restart) of the ninth embodiment. For the measurement, turn on the lamp for 30 minutes and then turn it off.
The restart voltage when restarting after 2 seconds was measured. It should be noted that if the turn-off time becomes long, the electrode temperature decreases and it becomes difficult to start. On the other hand, the vapor pressure of mercury or metal halide in the arc tube IB decreases as the extinguishing time becomes longer, and it becomes easier to start. As a result of these contradictory tendencies, the restart is most difficult to start when the turn-off time is about 10 seconds.

[0227]

Table 18 Lamp Second halide Restart voltage (kV) 1 (Comparative example) -15.2 ₂ AlI ₃ 8.7 3 FeI ₂ 9.1 4 ZnI ₂ 9.6 5 MnI ₂ 9.3 6 The GaI ₃ 8.3 lamp 1 (comparative example) has a high starting voltage because the mercury vapor pressure is still high.

On the other hand, lamps 2 to 6 (Example 9)
Is clearly lower than the mercury vapor pressure of the second metal halide during steady lighting. Still, 10 seconds after turning off the light is when the difference between the vapor pressure of the metal halide and the vapor pressure of mercury is the smallest. This shows that Example 9 has a very good restart characteristic as compared with the comparative example in which mercury is sealed.

Next, Table 19 shows the results of measuring the color characteristics near the electrodes when the metal halide lamp of Example 9 was lit by direct current. It is to be noted that this is obtained by projecting the lamp on the screen when the lamp is turned on with an input of 35 W and measuring the color temperatures (K) near the anode and the cathode.

[0230]

[Table 19] Lamp Second Halide Anode-side color temperature (K) Cathode-side color temperature (K) 1 (Comparative example) -5330 3720 2 AlI ₃ 4210 3840 3 FeI ₂ 4420 4010 4 ZnI ₂ 4080 3650 5 MnI ₂ 4450 4060 6 GaI ₃ 4530 4130 Lamp 1 (Comparative Example) has a large difference in color temperature between the anode side and the cathode side. It is impossible to cover such a difference in color temperature with the design of the headlight.

On the other hand, lamps 2 to 6 (Example 9)
Has a small difference in color temperature and is therefore suitable for practical use.

Tenth Embodiment In a tenth embodiment, in addition to the structure shown in FIG. 4 according to the second embodiment of the metal halide lamp of the present invention, both ends of the outer tube OB are sealed with the sealing portion 1 of the arc tube IB.
a and 1a are hermetically sealed, and the inside is evacuated. Other configurations are the same as those of the first embodiment including the discharge medium. The comparative example had the same specifications as the comparative example in Example 9, and the outer tube OB in FIG. 4 was evacuated.

Thus, the results of measuring the lamp voltage (V), the luminous efficiency (lm / W), the color rendering properties (average color rendering index) Ra and the color temperature (K) for the example 10 and the comparative example are shown. Shown in 20.

[0233]

[Table 20] Lamp Second halogen compound Lamp voltage (V) Luminous efficiency (lm / W) Color rendering (Ra) Color temperature (K) 1 (Comparative example) -84 89 63 40 10 2 AlI ₃ 70 94 94 68 3890 3 FeI ₂ 76 91 73 73 4120 4 ZnI ₂ 81 91 68 68 3720 5 MnI ₂ 71 92 67 67 4110 6 GaI ₃ 80 90 65 4330 In Example 10, the outer tube OB was evacuated, and the lamp voltage was increased. , Luminous efficiency is dramatically improved. On the other hand, in the comparative example, it was only slightly improved.

[Embodiment 11] In the embodiment 11, the discharge medium is enclosed as follows in the same structure as the metal halide lamp shown in FIG. 1 and the same size as the embodiment 1.

First halide = scandium iodide ScI ₃ 0.14 mg + sodium iodide NaI 0.7 mg _Second halide = zinc iodide ZnI ₂ 0.4 mg and added halide 0.1 mg rare shown in Table 10 Gas = xenon 5 atm Then, the results of measuring the lamp voltage (V), luminous efficiency (lm / W), color rendering (average color rendering index) Ra and color temperature (K) for Example 11 are shown in Table 21. Shown in.

[0235]

[Table 21] Ranfu ° addition Haroke Bu emissions halide Ranfu ° Voltage (V) luminous efficiency (lm / W) color rendering (Ra) Color Temperature _{(K) 1 MgI 2 88 81} 65 3890 2 NiI 2 91 80 66 3990 3 CoI 2 88 82 67 4020 4 CrI ₂ 96 82 64 411 05 SbI ₃ 83 79 79 66 3810 6 ReI ₂ 86 80 66 3960 The second halide generally has a lower vapor pressure than mercury, but contributes to the formation of a lamp voltage higher than mercury at the same pressure. .

However, since the vapor pressure of mercury is always high,
In a small metal halide lamp with a small load such as a rated lamp power of 100 W or less for a headlight of a moving body, mercury is completely evaporated. Therefore, the lamp voltage can be adjusted by the amount of mercury enclosed.

On the other hand, when the second halide is enclosed instead of mercury, the vapor pressure of the enclosed halide is saturated at the stage of incomplete evaporation, so that the lamp voltage is further increased. do not do.

However, the lamp voltage can be further increased by encapsulating a plurality of second halides as in the eleventh embodiment. That is, when one of the second halides is saturated, the evaporation of the added second halide contributes to an increase in the lamp voltage. Therefore, the lamp voltage can be made higher when a plurality of the second halides are mixed than when the second halide is a single kind.

[Embodiment 12] This embodiment has the same structure as that of the metal halide lamp shown in FIG.
The discharge medium was enclosed as follows.

First halide = scandium iodide ScI ₃ 0.14 mg + sodium iodide NaI 0.7 mg Second halide = halide shown in Table 11 0.4 mg Third halide = cesium iodide CsI0. 1 mg Noble gas = Xenon 5 atm Further, as a comparative example, a metal halide lamp having the same specifications as in Example 12 was manufactured except that 1 mg of mercury was filled in place of the second halide.

Then, in Example 12 and the comparative example, the lamp voltage (V), the luminous efficiency (lm / W), the color rendering (average color rendering index) Ra and the color temperature were lit with the lamp input kept constant at 35 W. Table 22 shows the results of measuring (K).

[0241]

[Table 22] Lamp Second halogen compound Lamp voltage (V) Luminous efficiency (lm / W) Color rendering (Ra) Color temperature (K) 1 (Comparative example) -83 86 63 4140 2 AlI ₃ 63 63 93 68 3940 3 FeI ₂ 68 92 70 4180 4 ZnI ₂ 73 94 94 66 3800 5 MnI ₂ 65 94 65 65 4200 6 GaI ₃ 75 92 65 4310 In Example 12, cesium iodide CsI was added as a third halide to obtain a color rendering. Although the property Ra and the color temperature are almost unchanged, the temperature distribution of the arc is flattened, so that the heat loss is reduced and the luminous efficiency is improved. However, in the comparative example in which mercury is enclosed, the efficiency is not improved even if the third halide is added.

Further, in Example 12, the luminous efficiency is higher than that of the comparative example because mercury, which has a low luminous efficiency, does not emit light.

Next, Table 23 shows the luminous efficiency (lm / W) in the lamp 3 when the enclosed amount of cesium iodide CsI which is the third halide was changed.

[0244]

Table 23 CsI encapsulation amount (mg) Luminous efficiency (lm / W) 0.005 83 0.01 0.01 85 0.05 88 88 0.1 92 92 0.3 91 0.5 0.5 90 1.0 89 89 2.0 84 2 As can be seen from Table 23, the addition of CsI was 0.01
Effective from mg. However, if the addition amount is too large, the vapor pressure of the luminescent metal is lowered, resulting in a decrease in efficiency.

Further, Table 24 shows the results of measuring the restart voltage at the momentary restart (hot restart) of Example 12 and the comparative example under the same conditions as in Example 11 described above.

[0246]

Table 24 Lamp Second halide Restart voltage (kV) 1 (Comparative example) -15.2 ₂ AlI ₃ 9.2 3 FeI ₂ 9.6 4 ZnI ₂ 10.1 5 MnI ₂ 9.8 6 GaI ₃ 8.9 In Example 12, the restart voltage was markedly lower than that of the comparative example in which mercury was sealed, but it was slightly higher than that in the case where cesium iodide CsI which was the third halide was not sealed. The starting voltage tends to be high. However, there is no problem in practical use.

FIG. 11 is a front view showing a sixth embodiment of the metal halide lamp of the present invention. In the figure,
The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. The present embodiment is common in that it is suitable for a headlight of a moving body, but is different in that it is configured to be lit by direct current.

That is, in the figure, 2 _K is a cathode and 2 _A is an anode.

The airtight container 1 has an elliptic spherical shape and is provided with sealing portions 1a having a length of 30 mm at both ends.

[0250] cathode _{2 K} consists of a tungsten rod. The base end of the molybdenum foil 3 is buried in the sealing portion 1a.
Is welded to one end.

[0251] The anode _{2 A} is made of a tungsten rod. The base end portion is welded to one end of the molybdenum foil 3 similar to the above.

The external lead wire 4 is made of a conductor and is welded to the other end of the molybdenum foil 3.

In order to manufacture the metal halide lamp having the above structure, first, the airtight container 1 to which the sealing tubes for forming the sealing portions 1a are joined is prepared.

Next, after inserting the connection assembly of the cathode 2 _K , the molybdenum foil 3 and the external lead wire 4 into one of the sealing tubes, the sealing tube was heated and melted by using an oxyhydrogen burner and pinched. The cathode 2 _K is sealed to the airtight container 1 by sealing with a seal.

Then, the first and second halides were sealed in the airtight container 1 from the other sealing tube in a nitrogen gas atmosphere, and the anode 2 _A , molybdenum foil 3 and external lead wire 4 were connected together. Is inserted into the sealed tube, and a predetermined interelectrode distance is set.

Further, these assemblies were attached to an exhaust system via a sealing tube to evacuate the inside of the airtight container 1, and after introducing 2 atmospheres of xenon, the airtight container 1 was cooled while the other was sealed. the pinch seal the stop tube after heating and melting an oxyhydrogen burner to seal the anode 2 _a in the airtight container 1 to complete the metal halide discharge lamp. Of the discharge medium, the halide of Example 13 was enclosed as the halide.

[Embodiment 13] This embodiment has the same structure as the metal halide lamp shown in FIG. 6 and the main specifications are as follows.

Airtight container 1: Inner diameter 4 mm, length 7 mm Cathode 2 _K : 0.4 mm diameter, length 6 mm containing thorium Anode 2 _A : Diameter 0.8 mm, length 6 mm Electrode distance: 4.2 mm External lead wire 4 is a conductor having a diameter of 0.5 mm and a length of 25 mm Discharge medium: first halide = scandium iodide ScI ₃ 0.17 mg + sodium iodide NaI 0.83 mg second halide = (lamp 2) ZnI ₂₀ .4 mg = (Lamp 3) AlI ₃ 0.2 mg = (Lamp 4) FeI ₂ 0.4 mg Noble gas = Xe ₂ atm Note that, as a comparative example (Lamp 1), 1 mg of mercury was sealed in place of the second halide. A metal halide lamp having the same specifications as in Example 13 except for the above was manufactured.

Then, the lamp input of the lamp 2 (Example 13) and the lamp 1 (comparative example) were rated at 35 W.
Table 25 shows the results of measuring the luminous efficiency (lm / W), color rendering (average color rendering index) Ra, and color temperature (K) when the lamp was turned on at 20 W, 25 W, 30 W, and 35 W.

[0259]

[Table 25] Lamp lamp power (W) Luminous efficiency (lm / W) Color rendering (Ra) Color temperature (K) 1 (conventional example) 20 45 4970 35 80 80 65 4100 2 20 64 64400 25 25 66 4310 30 69 4240 35 75 70 4190 FIG. 12 is a chromaticity diagram showing the chromaticity rising characteristics of the lamp 2 in Example 13 together with that of the comparative example. In the figure, a curve G shows the luminous flux rising characteristic of the sixth embodiment. Curve H
Shows the luminous flux rising characteristics of the comparative example.

The chromaticity of Example 13 is in the white area from the beginning of lighting. On the other hand, the chromaticity of the comparative example required about 1 minute before entering the white region.

Next, for each lamp of Example 13, a blinking test was conducted by turning on the lamp at 42 W, which is 20% increase of the rated lamp power, for 60 minutes and then extinguishing for 15 seconds to examine the presence or absence of rupture of the airtight container. No rupture occurred after 1000 hours.

Further, Table 26 shows the result of measurement of the restart voltage required for the instantaneous restart after 2 seconds from turning off the light.

[0263]

Table 26 Lamp restart voltage (kV) 1 12 2 5 3 4 4 4.3 In FIG. 13, the charging pressure of rare gas is changed in the sixth embodiment of the metal halide lamp of the present invention shown in FIG. It is a graph which shows the relationship with the luminous flux rise time at the time of making it. In the figure, the horizontal axis is the xenon filling pressure (atmospheric pressure),
The vertical axis represents the luminous flux rise time (second).

From the figure, it was found that when the pressure for filling xenon was 1 atm or more, the rise time of the luminous flux was sharply shortened to make it practical.

FIG. 14 shows that in the lamp 2 of Example 13, the amount of ZnI ₂ enclosed as the second halide (mg
9 is a graph showing the relationship of the lamp voltage (V) when / cc) is changed. From the figure, it can be understood that by encapsulating ZnI ₂ at 1 mg / cc or more, the desired value of the lamp voltage for lighting by using the electronic lighting circuit can be set to 30 V or more.

[Embodiment 14] This embodiment has basically the same structure as that shown in FIG. 1, but is constructed so as to be suitable for use in the second embodiment of the illuminating device of the present invention described later. It is a metal halide lamp.

Distance between electrodes: 2 mm Rated lamp power: 80 W Discharge medium: First halide = scandium iodide ScI ₃ 0.
3 mg + sodium iodide NaI 1.5 mg Second halide (Lamp 2) = ZnI ₂ 1 mg + AlI ₃ 1 mg + MnI
₂ 1 mg (lamp 3) = ZnI ₂ 2 mg + GaI ₃ 1 mg + CrI
₂ 1 mg noble gas = xenon 5 atm Further, as a comparative example, mercury 1 was used instead of the second halide.
A metal halide lamp having the same specifications as in Example 14 except that 5 mg was enclosed was manufactured.

Thus, the lamp of Example 14 and the comparative example were lit at a constant rating of 80 W and the lamp voltage (V) and the luminous efficiency (l
m / W), color rendering properties (average color rendering index) Ra and color temperature (K) are shown in Table 27.

[0268]

[Table 27] Lamp lamp voltage (V) Luminous efficiency (lm / W) Color rendering (Ra) Color temperature (K) 1 (Comparative example) 63 94 63 4020 2 58 88 68 68 3920 3 62 62 89 69 4110 Understand from Table 27 As can be seen, in Example 14,
It is possible to obtain almost the same characteristics as the comparative example in which mercury is enclosed. Further, although it is suitable for the second embodiment of the illuminating device of the present invention to be described later, in the system in this illuminating device, it is necessary to change the input to perform the dimming, so dimming is possible at that point. Is extremely useful.

<Embodiment of Metal Halide Lamp Lighting Device of the Present Invention> FIG. 15 is a circuit diagram showing a first embodiment of a metal halide lamp lighting device of the present invention. In the present embodiment, the metal halide lamp is configured to be lit by direct current. In the figure, 71 is a DC power supply, 72 is a chopper, 73 is control means, 74 is lamp current detection means, 75 is lamp voltage detection means, 76 is starting means, and 77 is a metal halide lamp.

As the DC power source 71, a battery or a rectified DC power source is used. In the case of moving bodies such as automobiles, batteries are generally used. However, it may be a rectified DC power supply that rectifies AC. If necessary, electrolytic capacitors 71a are connected in parallel for smoothing.

The chopper 72 converts the DC voltage into a voltage of a required value and controls the metal halide lamp 77 as required. When the DC power supply voltage is low, the step-up chopper is used, while when it is high, the step-down chopper is used.

The control means 73 controls the chopper 72. For example, immediately after lighting, the metal halide lamp 77
The chopper 7 with a lamp current more than 3 times the rated lamp current.
Flow from 2 and then gradually reduce the lamp current with the lapse of time, and eventually control to reach the rated lamp current.

The lamp current detecting means 74 is inserted in series with the lamp to detect the lamp current and control-input to the control means 73.

The lamp voltage detecting means 75 is connected in parallel with the lamp to detect the lamp voltage and control-input to the control means 73.

The control means 73 generates a constant power control signal by the feedback input of the detection signals of the lamp current and the lamp voltage, and controls the chopper 72 at constant power. Further, the control means 73 has a built-in microcomputer in which a temporal control pattern is incorporated in advance. Immediately after lighting, a lamp current that is three times or more of the rated lamp current is supplied to the metal halide lamp 77, and the lamp increases with time. The chopper 72 is configured to control the current.

The starting means 76 is constructed so that a pulse voltage of 20 kV can be supplied to the metal halide lamp 67 at the time of starting.

Thus, according to the metal halide lamp lighting device of the present embodiment, the required luminous flux is generated immediately after lighting while lighting DC. As a result, it is possible to realize lighting of a luminous flux of 25% relative to the rating 1 second after the power is turned on and a luminous flux of 80% after 4 seconds, which is necessary for a headlight for a moving body such as an automobile.

In the case of the present embodiment, the DC-AC conversion circuit is not required, so that the cost can be reduced by about 30% as compared with the AC lighting. Also, the weight can be reduced by 15%. Accordingly, the lighting circuit becomes cheaper.

FIG. 16 is a circuit diagram showing a second embodiment of the metal halide lamp lighting device of the present invention. In the figure, the same parts as those in FIG. The present embodiment is different in that the metal halide lamp is configured to be lit by alternating current.

Reference numeral 78 is an AC converting means. The AC converting means 78 is a full bridge inverter. That is, a pair of a series circuit of a pair of switching means 78a, 78a is connected in parallel between the output terminals of the chopper 72 to form a bridge circuit, and the oscillation output of the oscillator 78b is switched diagonally by the four switching means 78a. Means for alternately supplying the means to generate a high frequency alternating current between the output terminals of the bridge circuit.

The metal halide lamp 77 is turned on by the high frequency alternating current.

Also in this AC lighting type configuration, as shown in FIG.
The same control as in 5 is performed.

<Embodiment of Lighting Apparatus of the Present Invention> FIG. 17 is a perspective view showing a headlight for a moving body such as an automobile as a first embodiment of the lighting apparatus of the present invention. In the figure, 31 is a reflecting mirror and 32 is a front cover.

The reflecting mirror 31 is formed into a modified paraboloid of revolution by molding of plastics, and is constructed so that a metal halide lamp (not shown) shown in FIG.

The front cover 32 is integrally formed with a prism or a lens by molding a transparent plastic, and is hermetically attached to the front opening of the reflecting mirror.

FIG. 18 and FIG. 19 show a headlight for a moving body as a second embodiment of the lighting device of the present invention.
FIG. 18 is a conceptual diagram, and FIG. 19 is a conceptual diagram of a part of the optical distributor. In each figure, 81 is a lighting circuit, 82 is a light distributor,
Reference numeral 83 is a main optical fiber, 84 is an optical shutter 85, an individual optical fiber, and 86 is a lamp.

As the lighting circuit 81, any of the lighting circuits shown in FIGS. 15 and 16 can be used.

The light distributor 82 includes a case 82a, a light collecting / reflecting surface 82b, a metal halide lamp 82c, and an optical connector 82d. Then, the light generated from the metal halide lamp 82c is distributed from the optical connector 82d to the main optical fiber 83.

The main optical fiber 83 transmits the light distributed from the light distributor 82 to the optical shutter 84.

The optical shutter 84 includes the individual fiber 85.
It is selectively transmitted to each lighting device 86 via.

The lighting device 86 includes a high beam lighting device 86a, a low beam lighting device 86b and a fog lighting device 86c as one set, and the two sets are arranged on both front sides of a moving body such as an automobile.

FIG. 20 is a sectional view showing a downlight as a third embodiment of the lighting apparatus of the present invention.

In the figure, 91 is a metal halide lamp, and 92 is a downlight body.

The downlight main body 92 includes a base 92a, a socket 92b, a reflector 92c and the like.

The base 92a has a ceiling abutting edge e at its lower end so as to be embedded in the ceiling.

The socket 92b is mounted on the base body 92a.

The reflector 92c is supported by the base 92a and surrounds the light emitting center of the metal halide lamp 91 so as to be located substantially at the center thereof.

[0298]

According to each of the first to fourth aspects of the present invention, the discharge medium is the first halide mainly containing halides of sodium Na and scandium Sc, and magnesium Mg, iron Fe, cobalt Co and chromium Cr. , Zinc Z
n, nickel Ni, manganese Mn, aluminum Al,
Mainly contains one or more metal halides selected from the group consisting of antimony Sb, beryllium Be, rhenium Re, gallium Ga, titanium Ti, zirconium Zr, and hafnium Hf, and the vapor pressure during lighting is 5 atm or less. A second halide exhibiting
By having a discharge medium containing a rare gas and containing essentially no mercury, the electrical characteristics and the characteristics substantially equivalent to those in which mercury is enclosed are obtained without essentially using mercury with a large environmental load. A metal halide lamp having light emitting characteristics can be provided.

According to the invention of claim 2, in addition, the emission of light caused by lighting is based on Japanese Industrial Standard JIS D 5500.
-By entering the range of white chromaticity specified in 1984, it is possible to provide a metal halide lamp for automobiles such as headlights, which has a white chromaticity of emission color conforming to the JIS standard.

According to the third aspect of the present invention, in addition, since the total luminous flux is at least 2205 lm when the lamp is turned on at 35 W, it is almost comparable to the lamp efficiency of the conventional metal halide lamp for headlights in which mercury is enclosed. It is possible to provide a metal halide lamp having a sufficient total luminous flux.

According to the invention of claim 4, in addition to the rare gas, the filling pressure of xenon is 1 atm or more, so that it is possible to provide a metal halide lamp having improved luminous flux rising characteristics.

According to the invention of claim 5, the scope of claim 1
It is possible to provide a metal halide lamp lighting device having the effects of 4 to 4.

According to the invention of claim 6, the scope of claim 1
It is possible to provide a lighting device having the effects of 4 to 4.

[Brief description of drawings]

FIG. 1 is a central sectional front view showing a first embodiment of a metal halide lamp of the present invention.

FIG. 2 is a graph showing the relationship between the rising pressure of the luminous flux and the filling pressure of xenon Xe in Example 1.

FIG. 3 is a graph showing the relationship between the lamp voltage and the filling amount when iron iodide FeI ₂ is used as the second halide in Example 1.

FIG. 4 is a front view showing a second embodiment of the metal halide lamp of the present invention.

FIG. 5 is a front view showing a third embodiment of the metal halide lamp of the present invention.

FIG. 6 is a graph showing a spectral distribution of a conventional long arc type metal halide lamp.

FIG. 7 is a front view showing a fourth embodiment of the metal halide lamp of the present invention.

FIG. 8 is a chromaticity diagram showing chromaticity rising characteristics in Example 3 in comparison with those in Comparative Example.

FIG. 8 is a graph showing the relationship of the lamp voltage (V) in Example 6 when the amount of ZnI ₂ enclosed as the second halide (mg / cc) was changed.

FIG. 9 is a front view showing a fifth embodiment of the metal halide lamp of the present invention.

FIG. 10 is a chromaticity diagram showing chromaticity rising characteristics of Lamp 2 of Table 16 in Example 9 and Lamp 1 of Comparative Example.

FIG. 11 is a front view showing a sixth embodiment of the metal halide lamp of the present invention.

FIG. 12 is a chromaticity diagram showing the chromaticity rising characteristics of the lamp 2 in Example 13 together with those in Comparative Example.

FIG. 13 is a graph showing a relationship with the luminous flux rise time when the rare gas filling pressure is changed in the sixth embodiment of the metal halide lamp of the present invention shown in FIG.

FIG. 14 is a graph showing the relationship between the lamp voltage (V) when the amount of ZnI ₂ enclosed ( _second / halide) (mg / cc) in the lamp 2 of Example 13 was changed.

FIG. 15 is a circuit diagram showing a first embodiment of a metal halide lamp lighting device of the present invention.

FIG. 16 is a circuit diagram showing a second embodiment of the metal halide lamp lighting device of the present invention.

FIG. 17 is a perspective view showing a headlight for a moving body such as an automobile as a first embodiment of an illumination device of the present invention.

FIG. 18 is a conceptual diagram showing a headlight for a moving body as a second embodiment of an illumination device of the present invention.

FIG. 19 is a conceptual diagram showing a part of an optical distributor.

FIG. 20 is a sectional view showing a downlight as a third embodiment of a lighting device of the present invention.

FIG. 21 is a conceptual diagram for explaining a lamp voltage in a metal halide lamp.

FIG. 22 is a graph showing an emission spectrum distribution of a conventional short arc type metal halide lamp for projection.

FIG. 23 is a graph schematically illustrating an arc temperature distribution in a metal halide lamp when mercury is not encapsulated and when mercury is encapsulated.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Airtight container, 1a ... Sealing part, 2 ... Electrode, 2a ... Electrode shaft, 3 ... Sealing metal foil, 4 ... External lead wire, IB ... Arc tube

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // F21W 101: 10 F21M 1/00 M F21Y 101: 00 3/02 G (31) Priority claim number Special Wishhei 9-346035 (32) Priority date December 16, 1997 (December 16, 1997) (33) Country of priority claim Japan (JP) (72) Inventor Mikio Matsuda 4-chome, Higashishinagawa, Shinagawa-ku, Tokyo 3-1 In Toshiba Litec Co., Ltd. (72) Inventor Toshio Hikita 4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo F-Term in Toshiba litec Co., Ltd. (reference) 3K042 AA01 AA08 AC06 3K072 AA13 AC11 AC20 BA05 DA00 DE02 DE04 GB03 GB18 5C015 QQ03 QQ08 QQ09 QQ14 QQ37 QQ38 QQ39 QQ43 QQ44 QQ45 QQ47 QQ52 QQ56 QQ57 QQ65 RR05 SS04 5C039 HH02 HH05

Claims (6)

[Claims] 1. An airtight container; a pair of electrodes sealed in the airtight container; a first halide mainly containing a halide of sodium Na and scandium Sc, magnesium Mg, iron Fe, cobalt Co, chromium Cr. , Zinc Z
n, nickel Ni, manganese Mn, aluminum Al,
Mainly contains one or more metal halides selected from the group consisting of antimony Sb, beryllium Be, rhenium Re, gallium Ga, titanium Ti, zirconium Zr, and hafnium Hf, and the vapor pressure during lighting is 5 atm or less. And a discharge medium containing a rare gas and containing essentially no mercury, and a metal halide lamp containing essentially no mercury. 2. The metal halide lamp according to claim 1, wherein the emission of light generated by lighting falls within the range of white chromaticity defined in Japanese Industrial Standard JIS D 5500-1984. 3. The metal halide lamp according to claim 1, wherein the total luminous flux is at least 2205 lm when the lamp is turned on at 35 W. 4. The metal halide lamp according to claim 1, wherein the rare gas has a xenon filling pressure of 1 atm or more. 5. A metal halide lamp according to claim 1, wherein at least three times the rated lamp current is supplied to the metal halide lamp immediately after lighting of the metal halide lamp, and the current is reduced over time. And a lighting circuit configured to: a metal halide lamp lighting device. 6. A lighting device comprising: a lighting device main body; and a metal halide lamp according to claim 1, which is supported by the lighting device main body.