JP2002093369A - Short arc metal halide lamp for head lamp, metal halide lamp lighting device and head lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a short arc metal halide discharge lamp that has a high beam-condensing efficiency without using mercury and a good chromaticity and start-up luminous flux at the start and is easy in instantaneous restart, capable of dimming and hard to break the airtight container, and further has little fluctuation of its property, and a metal halide lamp lighting device and a head lamp. SOLUTION: The halide lamp comprises a fire resistant and light translucent airtight container 1 having an inner volume of 0.005-0.1 cc, a pair of electrodes 2, 2 having a distance of 6 mm or less between the electrodes, and a discharge medium filled in the airtight container containing the first halide composed of a halide containing at least sodium Na and scandium Sc, the second halide composed of a halide that has a relatively large vapor pressure and is made of a metal of one kind or plural kinds that does not easily emit light in the visible region compared with the metal of the first halide and is contained 1 mg or more per 1 cc of the inner volume of the airtight container, and a rare gas, but mercury is not filled essentially in the container.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Metal halide lamps in which a rare gas, a luminescent metal halide and mercury are sealed in an arc tube having a pair of electrodes facing each other are widely used because of their relatively high efficiency and high color rendering properties. ing. As is well known, metal halide lamps include a short arc type and a long arc type.

[0003] The short arc type metal halide lamp is used for light projection such as a liquid crystal projector and an overhead projector for condensing the light emitted from the lamp and projecting it on a screen, and for store lighting such as a downlight and a spotlight. In the field of floodlights, small-sized short-arc metal halide lamps have recently been used in place of halogen bulbs as headlights for automobiles. The specification of a metal halide lamp for a headlight of an automobile is described in, for example, Japanese Patent Application Laid-Open No. 2-7347, but it is essential that about 2 to 15 mg of mercury be charged.

There is a need for a metal halide lamp which does not require the incorporation of mercury, and the invention described in, for example, JP-A-3-112045 has been made to meet this need. The present invention seeks to obtain a required lamp voltage by filling helium or neon at a pressure of 100 to 300 Torr instead of mercury. Further, since these rare gases have a small atomic radius, quartz glass is used. In this case, the airtight container is formed of a translucent ceramic because the airtight container is transmitted.

However, metal halide lamps currently in practical use require mercury in order to obtain a desired lamp voltage and maintain electrical characteristics. That is, for example, when the lamp voltage is low, the lamp current must be increased to obtain a desired lamp input. In this case, an increase in current capacity and an increase in generated heat 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 with an increase in electrode loss. That is, since the electrode drop voltage of a metal halide lamp is constant depending on the lamp, if the lamp voltage is low, the lamp current must be increased to compensate for this, so the electrode loss increases in proportion to the lamp current, and the lamp efficiency increases. Will drop. Therefore, in general, 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 mercury is required to be filled will be described while considering the lamp voltage.

FIG. 16 is a conceptual diagram for explaining a lamp voltage in a 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 V1 is a voltage appearing between the lead wires 3 when the metal halide lamp is turned on. The distance L between the electrodes 2 and 2 is called the distance between the electrodes.

[0010] The lamp voltage Vl can be expressed by equation (1).

[0011]

V1 = E × L + Vd where 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.

[0013]

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).

[0015]

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 cross section of the collision.

The lamp voltage Vl is calculated from the following equation (1).
It can be seen that the larger the distance between the electrodes and the larger the distance L between the electrodes, the larger the distance. Further, the potential gradient E is calculated from Equation 2 as the electric conductivity σ is smaller and the lamp current I is larger.
It turns out that it becomes large. Furthermore, the electrical conductivity sigma, from Equation 3 as N _E is small, N _A and Q is can be seen that the larger small.

Therefore, when the distance L between the electrodes and the lamp current I are constant, the substance A for which the lamp voltage Vl increases 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.

Mercury has a very high vapor pressure (1 atm at 361 ° C.), is hard to ionize, and has a large cross section in collision with electrons. Therefore, a desired lamp voltage can be easily obtained by adjusting the amount of mercury charged 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 a conventional metal halide lamp.

[0020]

By the way, in the case of a metal halide lamp, the vapor pressure of mercury must be increased in order to secure a required lamp voltage as the distance L between the electrodes is small and small. For example, in a small short-arc metal halide lamp having an arc tube with an inner volume of 1 cc or less,
The mercury vapor pressure during lighting becomes 20 atmospheres or more. A metal halide lamp for a headlight of a mobile body such as an automobile and having a rated lamp power of 100 W or less has a feature that a distance between electrodes is small and a tube wall load is large. For this reason, in the case of a conventional metal halide lamp in which mercury is sealed, the mercury vapor pressure is increased to 20 atm or more in order to obtain a required lamp voltage as described above. Easy to break.

In addition, since xenon is sealed at a high pressure to improve the light flux rising characteristics, the xenon becomes about 35 atm during lighting. For this reason, it is necessary to apply a high-voltage and high-power pulse voltage for starting in order to start the starting gas by dielectric breakdown. At the time of instantaneous restart, a higher starting pulse voltage is required, so that the lighting circuit, the luminaire, and the wiring need to have a height suitable for the dielectric strength grade, and therefore become expensive.

Further, the problem of light flux rising characteristics was solved by enclosing high-pressure xenon and applying a means for applying a high starting pulse voltage and applying a large current immediately after lighting to gradually reduce the current. Poor rise characteristics. That is, xenon emits light first, and then mercury emits light. This emission of mercury continues until after 10 to 20 seconds. The emission of mercury has poor color rendering properties and does not fall within the required white range.

Hereinafter, in the short arc type metal halide lamp for a headlamp, the problems caused by the incorporation of mercury and the problems in the case where the mercury is not enclosed in the prior art will be summarized. 1. Problems due to the inclusion of mercury (1) Problems with environmentally hazardous substances At present, environmental issues are very close up on a global scale, and even in the field of lighting, mercury is an environmentally hazardous substance that has an adverse effect on the environment. Reduction and even elimination of light from lamps is considered a very important task.

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

(2) Problem of Chromaticity Characteristics Rising at Startup In the case of a short-arc metal halide lamp for a headlight of an automobile, an instantaneous rise of a luminous flux is required. For this,
In a conventional short arc metal halide lamp for a headlamp, a lighting method is employed in which xenon is sealed at a high pressure as a starting gas, a large current is supplied at an initial stage of lighting, and the current is reduced with time. In this way, instantaneous rise is possible, but mercury evaporates rapidly at the time of switch-on and deprives energy, so that the rise in vapor pressure of the luminescent metal is slow, so that the state of strong mercury emission is 10 to 10. Continues after 20 seconds. Since mercury emission is inferior in color characteristics, its color rendering properties are poor and its chromaticity does not fall within the white range. Thus, the rise of the chromaticity characteristics is extremely bad. Therefore, it takes a long time to emit light having the desired chromaticity characteristics.

(3) Problems unsuitable for dimming When the temperature of the arc tube changes, the color temperature of light emission greatly changes, and the color rendering properties also change accordingly. Hereinafter, this problem will be described with reference to FIG.

FIG. 17 is a graph showing the emission spectrum distribution of a conventional short arc metal halide lamp for projecting light. In the figure, the horizontal axis indicates the wavelength (nm), and the vertical axis indicates the relative radiation power (%).

[0028] The conventional short arc type metal halide lamp, argon 500 Torr, the dysprosium iodide DyI ₃ 1mg and neodymium iodide NdI ₃ as halide 1mg as the rare gas, and mercury 13
mg is enclosed. The emission spectrum is composed of continuous emission by dysprosium and neodymium, and a main emission line spectrum by an element with a symbol on each arrow, and it can be seen that the emission line spectrum by 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 a luminescent metal is significantly lower than that of mercury, when the temperature of the arc tube changes, the luminous metal changes its vapor pressure in the lamp due to the change in the evaporation amount of the halide. , 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 emitted by the mercury strong emission line spectrum is small. Therefore, when the input power to the arc tube decreases, the emission of light by mercury becomes relatively dominant, so that the color temperature of the emission decreases and the color rendering property decreases. This means that conventional metal halide discharge lamps containing mercury are not suitable for dimming.

In the case of a headlight for an automobile, dimming is required for daylighting (daylight) employed in Europe and the United States. In a conventional metal halide lamp containing mercury, The color characteristics are significantly reduced.

(4) Problem of Large Variation in Characteristics In a metal halide filled with mercury, the temperature of the arc tube varies with the dimensional variation of individual lamps, so that the characteristics tend to vary even with the same input. In addition, the characteristics are liable to change due to an increase in the temperature of the coldest part due to blackening of the arc tube during a long life.

(5) The problem that instantaneous restart is difficult In a short arc type metal halide lamp for a headlight,
As described above, high-pressure xenon is sealed to speed up the rise of the luminous flux, and the xenon becomes about 35 atm during lighting. Since the mercury vapor pressure and the xenon vapor pressure during lighting are extremely high as described above, it is necessary to apply a very high and high-power pulse voltage to restart the operation. As a result, not only is the lighting circuit expensive, but also it is necessary to insulate the lighting circuit, the lamp, and the equipment housing these components from high voltages.

In a small short arc type metal halide lamp, the distance between the electrodes is small, so that the mercury vapor pressure is set high in order to obtain a required lamp voltage. become.

(6) The problem that the arc tube is easily ruptured As described above, since the mercury vapor pressure at the time of lighting is high, the initial tube or the strain increases during long-term lighting, so that the arc tube tends to burst. This problem significantly reduces lamp reliability.

(7) The problem of low illuminance on the illuminated surface In the case of a short arc type metal halide lamp for a headlamp, when illuminating the illuminated surface at a separated position brightly, the light emission of the lamp passes through the optical system without any loss. It is important to reach the irradiation surface. As has been found by the present invention, in order to reduce the loss and improve the illuminance on the irradiation surface, the arc needs to be narrowed down. The fact that the arc is narrowed means that the distribution of the arc temperature is sharp.

However, the emission of mercury is optically thick due to absorption, and the energy rises due to the absorption of the emission in the middle and low temperature portions, and the temperature rises. Arc cannot be squeezed.

On the other hand, it is known that when scandium or a rare earth metal is used as the light emitting metal and the light emission is extremely increased, the arc can be narrowed even in the presence of mercury. However, since the lighting pressure of mercury is high, convection becomes intense, and arc instability occurs, making it unpractical. 2 Problems of the prior art without mercury filling In the above-mentioned metal halide lamp without mercury filling, helium or neon becomes extremely high in pressure during operation. Obtainable. Therefore, it can be highly evaluated that a metal halide lamp not containing mercury can be obtained.

However, it is quite difficult to realize the same structure as a conventional metal halide lamp in which mercury is sealed at a high pressure during operation. For example, in a small metal halide lamp, the required lamp voltage is 50
In the case of ６０60 V, the pressure of helium or neon during lighting will exceed 150 atmospheres, so that a hermetic container as conventionally used cannot provide high reliability against rupture.

The present invention does not essentially use mercury, which has a large environmental load, has almost the same electrical characteristics and luminous characteristics as those in which mercury is sealed, has a high light-collecting efficiency, and has a high starting color. Short arc type metal halide lamp for headlights, which has good temperature and luminous flux rise, easy instantaneous restart, dimming is possible, hardly ruptures the airtight container, and has little variation in characteristics. An object of the present invention is to provide a metal halide discharge lamp lighting device and a headlight.

The present invention does not essentially use mercury, which has a large environmental load, has almost the same electrical characteristics and luminous characteristics as those in which mercury is sealed, and has a good rise in chromaticity at startup. Another object of the present invention is to provide a short arc metal halide lamp for a headlight, a metal halide discharge lamp lighting device including the same, and a headlight.

[0042]

According to a first aspect of the present invention, there is provided a short arc type metal halide discharge lamp for a headlight, comprising: a fireproof and translucent airtight container having an inner volume of 0.005 to 0.1 cc; A pair of electrodes sealed in a container and having a distance between the electrodes of 6 mm or less; a first halide made of a halide containing at least sodium Na and scandium Sc, having a relatively large vapor pressure, and 1 m or more of one or more metals that are less likely to emit light in the visible region than the halide metal of 1
g of a second halide comprising at least g of a halide, and a discharge medium containing a rare gas and sealed in an airtight container, wherein essentially no mercury is sealed.

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

<Regarding Airtight Container> In the present invention, the airtight container must have an inner volume of 0.005 to 0.1 cc, and must be fire-resistant and translucent. The above-mentioned internal volume is a suitable value for a short-arc type metal halide lamp for a headlight. The term “fireproof and translucent” for an airtight container means that a material having fireproof property enough to withstand the normal operating temperature of a discharge lamp, and that visible light in a desired wavelength range generated by discharge is externally emitted. If we can derive
It can be made of any material. For example, quartz glass, translucent alumina, ceramics such as YAG, or a single crystal thereof can be used. In addition,
If necessary, it is permissible to form a halogen-resistant or metal-resistant transparent coating on the inner surface of the hermetic container or to modify the inner surface of the hermetic container.

The airtight container preferably has a maximum diameter portion having an inner diameter of 3 to 10 mm and an outer diameter of 5 to 13 mm.

<Regarding a Pair of Electrodes> The pair of electrodes forms a short arc structure in which the distance between the electrodes is 6 mm or less. And it is sealed inside the airtight container so as to be spaced apart and opposed. The “short arc type” is a type in which the distance between electrodes formed in the airtight container is reduced, and a so-called electrode stable type in which arc discharge is stabilized by the electrodes can be used. Therefore, in the case of the short arc type, since the distance between the electrodes is small, the light emission of the discharge lamp can be made as close as possible to the point light source, and the light can be efficiently collected by an optical system such as a reflecting mirror or a lens. When the distance between the electrodes exceeds 6 mm, the distance from the point light source is increased, and the light-collecting property by a reflecting mirror or the like is deteriorated, and the illuminance on the irradiated surface is reduced. The distance between the electrodes is preferably 1 to 5 mm, more preferably 4 mm or less, and most preferably 1 to 3 mm. The distance between the electrodes is measured at the tip of the electrode.

Further, the short arc type metal halide lamp for a headlight according to the present invention may be configured to be lit by either AC or DC. Therefore, the pair of electrodes have the same structure when operated by alternating current, but when operated by direct current, the temperature of the anode generally increases sharply. Can be.

<Regarding the 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) The first halide is a halide of a metal that generates visible light and contains at least sodium Na and scandium Sc as main components. In general, these first halides do not always have a relatively high vapor pressure during operation.

The first halide is allowed to contain a rare earth metal halide or the like as an auxiliary component in addition to sodium Na and scandium Sc, if necessary.

(Regarding the Second Halide) The second halide is a metal which has a relatively high vapor pressure during lighting and is hard to emit light in the visible region as compared with the first halide metal. If it is, it is not limited to a specific metal. In addition, "the vapor pressure is large" does not need to be too large like mercury.
Less than atmospheric pressure. “It is difficult to emit light in the visible region as compared with the metal of the first halide” does not mean that visible light is less emitted in an absolute sense, but has a relative meaning. This is because Fe and Ni certainly emit more ultraviolet light than visible light, but Ti, Al and Z
n emits a lot of light in the visible region. Therefore, if these metals that emit a large amount of light in the visible region alone emit light, energy concentrates on the metal, and the light emission in the visible region is large. However, if the metal of the second halide has a higher energy level than that of the metal of the first halide and thus hardly emits light, the energy is low in the state where the first and second halides coexist. This is because the concentration of the light emission of the first halide is reduced, and the light emission of the metal constituting the second halide is reduced.

The second halide is, for example, magnesium Mg, iron Fe, cobalt Co, chromium Cr, zinc Z
n, nickel Ni, manganese Mn, aluminum Al,
One or more halides selected from the group consisting of antimony Sb, beryllium Be, rhenium Re, gallium Ga, titanium Ti, zirconium Zr and hafnium Hf can be used. Among the above groups, iron Fe, zinc Zn, manganese Mn,
One or more halides selected from the group consisting of aluminum Al and gallium Ga are particularly preferred. However, these metals are optimally used as the main components, but magnesium Mg, cobalt Co, chromium Cr, nickel Ni, antimony Sb,
By adding one or more selected from the group consisting of beryllium Be, rhenium Re, titanium Ti, zirconium Zr and hafnium Hf as sub-components, the lamp voltage can be further increased.

Table 1 exemplifies the second halide effective in practicing the present invention, together with the temperature at which it reaches 1 atm. Note that these values are slightly different depending on the literature and the like, and therefore, the temperature values in Table 1 are approximate values.

[0054]

[Table 1] 2nd halide 1 Atmospheric temperature (° C) 1 AlI₃ 422 2 FeI₂ 827 3 ZnI₂ 727 4 SbI₃ 427 5 MnI₂ 827 6 CrI₂ 827 7 GaI₃ 349 8 ReI₃ 627 9 MgI₂ 927 10 CoI₂ 827 11 NiI₂ 747 12 BeI₂ 487 13 TiI₄ 377 14 ZrI₄ 431 15 HfI₄ 427 Most of the halides shown in Table 1 have a vapor pressure higher than that of mercury.
And the adjustment range of lamp voltage is narrower than mercury,
If necessary, mix and encapsulate multiple types.
As a result, the adjustment range of the lamp voltage can be expanded. Was
For example, AlI ₃Is in a state of incomplete evaporation,
If the desired lamp voltage is not obtained,
I₃Does not change the lamp voltage. In contrast
And AlI₃Instead of adding ZnI₂Is added, Z
nI₂Ramp voltage generated by the action of
Therefore, the lamp voltage can be increased. further,
With the addition of other second halides, a higher lamp
Voltage can be obtained.

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

Further, in the present invention, 1 mg or more of the second halide is sealed per 1 cc of the inner volume of the airtight container. In addition, it is preferably 1 to 200 mg.

(Regarding Halogen) As the halogen constituting the first and second halides, iodine is optimal in terms of reactivity, and the reactivity increases in the order of bromine, chlorine, and fluorine. Any of the above may be used. Also, different halogen compounds such as iodide and bromide can be used in combination.

(Rare gas) A rare gas is a gas that acts as a starting gas and a buffer gas, and is sealed in an airtight container. As the rare gas, xenon, argon, or krypton can be used alone or in combination of two or more. However, when xenon is used as a rare gas and the pressure of the sealed gas is increased to 1 atm or more, the luminous flux rising characteristics of the metal halide lamp can be improved. Good luminous flux rising characteristics are extremely important for headlights of moving objects such as automobiles. The filling pressure of xenon is preferably 1 to 15 atm.

(Regarding Mercury) In the present invention, "essentially no mercury is enclosed" means not only that no mercury is enclosed, but also 0.3 m / cc of an airtight container.
This means that less than g, preferably less than 0.2 mg, of mercury is allowed to be present. However, it is environmentally desirable not to encapsulate any mercury. If the electric characteristics of the discharge lamp are maintained by mercury vapor as in the prior art, the internal volume of the hermetic container is 1 in the short arc type.
Based on the fact that 20 mg or more per cc and also 5 mg or more in the long arc type are sealed, it can be said that the present invention essentially does not contain mercury.

<Other Configurations> Although not essential components of the present invention, the following configurations can be added as necessary.

1. Outer tube The outer tube houses the arc tube inside. If necessary, the inside of the outer tube can be evacuated. As a result, the heat loss of the hermetic container can be further reduced, the luminous efficiency can be improved, and the luminous efficiency can be made higher than that of the conventional case in which mercury is sealed.

2 Heat Insulation Means The heat insulation means is a means for reducing the loss of heat generated from the arc tube, and has any configuration as long as the heat loss generated from the arc tube can be reduced. However, for example, the following configuration is allowed.

By making the inside of the outer tube vacuum, heat loss due to convection and conduction of heat generated from the arc tube is reduced, and the discharge medium is kept warm. In this case, the specific structure, shape and constituent material are not limited. The fact that the inside of the outer tube is vacuum means that the pressure inside the outer tube is 10 Torr or less.

In addition, heat rays radiated 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, so that heat loss due to radiation is reduced and discharge is performed. The medium can be kept warm. The heat reflection / visible light transmission film is formed on the inner surface, outer surface, inner and outer surfaces of the cylindrical body or outer tube made of quartz glass or the like disposed between the arc tube and the outer tube, or formed on the outer surface of the arc tube. be able to.

Further, it is needless to say that the above-mentioned means can be implemented by appropriately combining them.

Since the heat retaining 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. Lamp Power Since the lamp power is for a headlight, it is preferable to set the lamp power to 100 W or less.

<Effects 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 desired light emission, the vapor pressure is compared with that of the first halide. Since a metal halide which is relatively large and hardly emits light in the visible region as compared with the first halide is sealed as the second halide, essentially replacing mercury, the lamp voltage is mainly It is determined by the evaporation amount of the second halide. When the second halide is incompletely evaporated, the amount of evaporation is determined by the vapor pressure of the second halide. The vapor pressure of the halide is determined by the coldest part temperature. Further, the second halide has a vapor pressure during lighting lower than that of mercury, but is clearly higher than that of the first halide, and may be about 5 atm or less.

Therefore, the short arc metal halide lamp for a headlight according to the present invention can be operated as desired without essentially encapsulating mercury, and its lamp voltage can be substantially the same as that of the prior art using mercury. Characteristics and emission characteristics can be obtained. Here, “substantially” means that a difference that is somewhat inferior to the prior art within a practicable range is allowed. This is also a practically acceptable range in consideration of the fact that the short arc type metal halide discharge lamp for a headlight is lighted by an electronic lighting device. However, the lamp voltage can be further increased by applying a heat retaining means to the airtight container if desired.

Based on the above operation, the following specific effects can be obtained. For this reason, the short arc metal halide lamp for a headlight of the present invention is most suitable for a headlight of a moving body such as an automobile.

(1) In an optical system using a reflecting mirror, high light-collecting efficiency can be obtained.

The short arc metal halide lamp for a headlight according to the present invention can be combined with an optical system using a reflecting mirror.
Surprisingly, it has been found that extremely high light-collecting efficiency can be obtained. The reason is that when the second halide is sealed in place of mercury, the arc is effectively reduced as shown in FIG.

FIG. 1 is a graph showing the respective arc temperatures in a short arc type metal halide lamp in which a second halide is sealed in place of mercury and an example in which mercury is sealed. In the figure, the horizontal axis represents the radial position in the center cross section between the electrodes of the airtight container, and the vertical axis represents the arc temperature (K). In the figure, curve A is an example in which a second halide is sealed in place of mercury, curve B
Indicates an example in which mercury is sealed. Note that the example of the curve A shows that dysprosium iodide DyI 31 mg and neodymium iodide NdI 31 mg as the first halide were used.
And 38 mg of AlI as the second halide,
This is an example in which the container is sealed together with 500 Torr of argon in a spheroidal airtight container having an inner diameter of 14 mm. The example of the curve B has the same specifications as the former except that 13 mg of mercury is sealed in place of the second halide. It can be seen that the curve A has a narrower arc than the curve B.

Therefore, when the short arc type metal halide lamp for a headlight according to the present invention is used as a light source of the headlight, the illuminance on the irradiated surface can be remarkably improved.

2. The chromaticity rise at the start is good.

In the present invention, since mercury is not essentially enclosed, the luminescence of the luminescent metal constituting the first halide substantially contributes mainly to the luminescence. The temperature rise is good.

3. Instantaneous restart is facilitated.

In the present invention, since the vapor pressure of the second halide is clearly lower in most cases as compared with mercury, instantaneous restart is facilitated. For this reason, the peak value of the starting pulse voltage applied for restart can be reduced, so that the dielectric strength of the electronic lighting device, the starting device, the wiring, and the lighting fixture can be reduced and the cost can be reduced.

(4) Dimming becomes possible.

Even when the input to the lamp changes, the dimming becomes possible because there is little change in the color temperature and color rendering of the light emission. Therefore, lighting during the day (daylight) becomes possible.

5 Rupture of the airtight container during lighting is reduced.

In the present invention, since the vapor pressure during lighting is not extremely high and can be easily reduced to about 60% of that when mercury is filled, the burst of the hermetic container during lighting is reduced.

6. Variation in emission color with respect to variation in shape, size, etc. is small.

Since there is little change in the lamp characteristics with respect to variations in the shape and dimensions of the arc tube, variations in emission colors are small.

7 White light emission can be obtained with high luminous efficiency.

In the present invention, in addition to the fact that mercury is not essentially encapsulated, scandium Sc and sodium Na, which are luminescent metals having higher luminous efficiency than mercury, are used as the first halide. ,
White light emission required as a headlight can be obtained, and luminous efficiency is increased.

(8) The luminous flux rising characteristics at the time of starting can be improved.

In the present invention, if xenon is sealed as a rare gas at a pressure of 1 atm or more, the luminous flux rising characteristics at the time of starting can be improved in addition to the chromaticity rising characteristics.

9 Suitable for DC lighting.

When a conventional metal halide discharge lamp in which mercury is sealed is DC-operated, luminescent metals such as sodium Na and scandium Sc are positively ionized.
It is attracted to the cathode side, and the concentration of the luminescent metal is lower on the anode side than on the cathode side. On the other hand, some mercury is also sucked to the cathode side, but since the amount of mercury is originally overwhelmingly large, a sufficient amount of mercury also exists on the anode side. As a result, the light-emitting metal emits light sufficiently on the cathode side, but the light-emitting metal emits extremely weak light on the anode side, and mainly mercury light emission. For this reason, 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, a metal halide discharge lamp in which mercury is sealed is mainly used by AC lighting.

On the other hand, in the present invention, the difference in the color temperature between the electrodes is small even when direct current lighting is performed by enclosing the second halide instead of essentially enclosing mercury. Can be used practically. This is because the second halide hardly emits light in the visible region, and the metal of the first halide emits strong light even on the anode side.

[0092] The short arc metal halide lamp for a headlight according to the second aspect of the present invention comprises a fire-resistant and translucent airtight container; a pair of electrodes sealed in the airtight container; at least sodium Na and scandium Sc. A halide having a relatively high vapor pressure and being less luminous in the visible region than the metal of the first halide; And a discharge medium containing xenon of 1 atm or more and sealed in an airtight container, wherein essentially no mercury is sealed.

The present invention is a short arc type metal halide lamp for a headlamp having good chromaticity rising characteristics at the time of starting. That is, by enclosing the second halide,
In addition to the fact that mercury is not essentially enclosed, the first halide as a luminescent substance is a halide containing sodium Na and scandium Sc, and at least 1 atm of xenon as a rare gas is enclosed. It has the following features.

Thus, in the metal halide lamp of the present invention, the luminescent metal of the first halide emits light from the start, so that the chromaticity is specified in the standard of the metal halide lamp for a headlight almost simultaneously with the start. It falls within the range of the chromaticity of white light (white chromaticity range described in the description of automotive lamps in Japanese Industrial Standard JIS D 5500-1984). Therefore, there is no sense of incongruity in light emission.

In contrast, in the case of a conventional short arc type metal halide lamp for a headlight in which mercury is sealed, mercury is mainly emitted for 10 to 20 seconds at the time of starting, and therefore, the color rendering properties are poor. At the same time, the chromaticity greatly deviates from the above chromaticity range.

Further, according to the present invention, since xenon is sealed at a pressure of 1 atm or more, the luminous flux rising characteristics at the time of starting can be improved.

According to a third aspect of the present invention, there is provided a metal halide lamp lighting device, comprising: a short arc type metal halide lamp for a headlight; and an electronic lighting device for energizing the short arc type metal halide lamp for a headlight. And;

The electronic lighting device is configured to output AC when the short arc metal halide lamp for a headlight is AC-lit, and to output DC when the DC lamp is lit.

In the case of AC lighting, the electronic lighting device is designed so that the DC of the battery power supply or the rectified DC of the commercial frequency is converted into a high-frequency AC and then supplied to the short arc type metal halide lamp for a headlight. It is common to configure.

On the other hand, in the case of DC lighting, there is no need to convert to high frequency AC. For this reason, the circuit configuration of the electronic lighting device can be simplified, and the electronic lighting device can be reduced in size, weight, and cost. That is, mobile objects such as cars
As described above, since a battery power supply is generally provided, it is better to use a direct current than to convert a direct current into an alternating current and then supply it to a short-arc metal halide lamp for headlights to light it. The configuration is simplified. Note that the above-described effect is essentially unchanged even when a control means such as a step-up chopper or a step-down chopper is used in order to convert a direct current to a desired voltage. This is because, even in the case of AC lighting, the control means is used when necessary. The reason why the direct current lighting is possible is that color separation becomes practically acceptable without mercury being enclosed.

Also, the electronic lighting device supplies a current more than three times the rated lamp current immediately after the short arc type metal halide lamp for the headlight is turned on, and reduces the current as time passes. Can be configured. Then, a metal halide lamp lighting device that satisfies the luminous flux rising characteristics required for a headlight of a moving body can be obtained. In this case, lighting may be any of AC lighting and DC lighting.

The headlamp according to the fifth aspect of the present invention is characterized in that the headlamp is provided with a reflector; and the light is incident on the reflector of the headlamp. A short arc type metal halide lamp for a headlamp; and an electronic lighting device for energizing the short arc type metal halide lamp for a headlamp.

The "headlight main book" means the remaining part of the headlight excluding the short arc metal halide lamp for the headlight and the electronic lighting device. And it has a reflector, a front cover, and the like.

The short arc type metal halide lamp for a headlamp is disposed at a predetermined position so that light emission enters a reflecting mirror. Generally, a short arc type metal halide lamp for a headlamp is disposed in a headlamp main body. But,
It is also possible to arrange a short arc type metal halide lamp for a headlamp outside the headlamp main body, and to make only the emitted light incident on the reflecting mirror via a light guiding means such as an optical fiber. In this way, a pair of headlights is generally provided on the left and right sides of the front surface of the moving body, but the short arc metal halide lamp for headlights can be shared by each headlight. Even when the headlight has a low-beam lamp and a high-beam lamp adjacent to each other, if the light distributed to each lamp is controlled using the light distributor, the headlight short-circuit can be controlled. The arc-shaped metal halide lamp can be shared by each lamp.

[0105]

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

FIG. 2 is a front view of the arc tube of the short arc type metal halide lamp for a headlamp according to the first embodiment of the present invention, which is a cross-sectional front view at the center.

In the figure, IB denotes an arc tube, which is an airtight container 1, a pair of electrodes 2, 2, a sealing metal foil 3, and an external lead wire 4.
It has.

The airtight container 1 has an enclosing portion 1a and a pair of sealing portions 1b, 1b. The surrounding portion 1a is formed by forming quartz glass into a spheroidal shape. The sealing portion 1b extends in the axial direction from both ends in the axial direction of the surrounding portion 1a.

The pair of electrodes 2, 2 are respectively connected to the electrode shaft 2a.
Is buried in the sealing portion 1b, and the front end is present in the surrounding portion 1b of the airtight container 1.

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

A first halide, a second halide and xenon are sealed as a discharge medium in the surrounding portion 1b of the airtight container 1.

EXAMPLE 1 airtight container 1: an inner diameter 4mm of the surrounding portion, the internal volume 0.05cc electrode distance: 4.2 mm discharge medium: first halide is scandium iodide _ScI 3 0.14 mg, sodium iodide NaI0. 8
6 mg, the second halide was 1 mg of the halide shown in Table 2, and the xenon was 1 atm. The short arc metal halide lamp for a headlamp of Example 1 was lit at a constant input power of 35 W, and the lamp voltage,
Table 2 shows the results obtained by measuring the luminous efficiency, the average color rendering index (hereinafter referred to as “color rendering properties”) Ra and the color temperature together with the comparative examples shown below. The comparative example is a short arc type metal halide lamp for a headlight based on the conventional technology having the same specifications as the present embodiment except that 1 mg of mercury is sealed in place of the second halide.

[0112]

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

From the above, it can be evaluated that the characteristics of this embodiment are almost the same as those of the comparative example in the steady state.

Next, with respect to the lamp 3 and the lamp 1 (comparative example) of this embodiment in Table 2, the input power of 15 W, 20 W
Table 3 shows the results of measuring the color rendering properties and the color temperatures when lighting was performed at W, 25 W, and 30 W.

[0115]

Table 3 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 69 Color temperature (K) 4530 4440 4310 4240 As shown in Table 3, in the comparative example of Lamp 1, 35 W (Table 2)
When the input was changed from 15 W to 15 W, the color temperature changed by 1520 K, and the color rendering property changed by 23. In this case, the change is so large that dimming cannot be performed in practice.

On the other hand, in the present embodiment, the change in color temperature is 320 K and the change in color rendering is only 8, so that sufficient light control is possible.

Table 4 shows the results of the evaluation of the restart.
Shown in

The lamp 10 was manufactured with the same specifications as the lamp 3 except that xenon Xe was sealed at 100 Torr, and the results of measurement of the restart voltage are also shown.

[0119]

Table 4 Lamp restart voltage (kV) 1 (comparative example) 14 3 7 10 3 As shown in Table 4, in this example, the restart voltage was half of the comparative example. In addition, as a reference, the lamp 1 in which the filling pressure of the rare gas is particularly low and the rising of the luminous flux is not considered important.
At 0, a further significant improvement was seen.

FIG. 3 is a graph showing the relationship between the filling pressure of xenon Xe and the luminous flux rising time in the first embodiment of the short arc type metal halide lamp for a headlight according to the present invention. In the figure, the horizontal axis is the Xe filling pressure (atmospheric pressure).
, And the vertical axis indicates the luminous flux rise time (second).

As is apparent from the figure, when the sealing pressure is 1 atm or more, the light flux rising time is significantly shortened, but when the filling pressure is less than 1 atm, it is extremely long.

FIG. 4 shows the first embodiment.
FIG. 9 is a graph showing a relationship between a charged amount and a lamp voltage when iron iodide FeI 2 is used as a second halide. FIG. In the figure, the horizontal axis represents the amount of FeI ₂ encapsulated (mg / c
c), and the vertical axis indicates the lamp voltage (V).

According to the figure, it is understood that the lamp voltage exceeding 30 V is 1 mg or more per 1 cc of the internal volume of the hermetic container.

It is to be noted that 20 cc per 1 cc of the inner volume of the airtight container is required.
If it is 0 mg or more, the luminous efficiency is reduced because unevaporated FeI2 absorbs light.

FIG. 5 is a front view showing a second embodiment of a short arc type metal halide lamp for a headlight according to the present invention. In the figure, the same parts as those in FIG.

In this embodiment, an arc tube IB similar to that shown in FIG. 2 is configured to be easily mounted on a headlight of a moving body. In the figure, OB is an outer tube, B is a base, and IT is an insulating tube.

The outer tube OB has a function of cutting off ultraviolet rays, and has an arc tube IB having substantially the same structure as that shown in FIG. 2 inside.
And a pair of sealing portions 1b of the airtight container 1 at both ends.
The interior is not airtight and communicates with the outside air. Further, one sealing portion 1b is planted on the base B. The external lead wire 4 led out from the distal end of the outer tube OB is folded back parallel to the outer tube OB, introduced into the base B, and connected to a terminal (not shown).

The insulating tube IT covers the external lead wire 4.

FIG. 6 is a perspective view showing a headlight according to a first embodiment of the present invention.

In the figure, 31 is a reflecting mirror and 32 is a front cover.

The reflecting mirror 31 is formed on a paraboloid of revolution having a deformed shape by molding plastics, and is configured so that a metal halide discharge lamp (not shown) shown in FIG.

The front cover 32 integrally forms a prism or a lens by molding a transparent plastic, and is hermetically mounted on the front opening of the reflecting mirror 31.

Embodiment 2 In this embodiment, the structure and size of a short arc type metal halide lamp for a headlight shown in FIG.
The following discharge medium was used. Discharge medium: the first halide is scandium iodide S
cI ₃ 0.14mg, sodium iodide NaI0.7m
g, the second halide is 0.1 g of the halide shown in Table 5.
4 mg, xenon: 5 atm. As a comparative example, a product in which 1 mg of mercury was further sealed was produced.

Table 5 shows the results of measuring the lamp voltage, the luminous efficiency, the color rendering (average salt color evaluation number) Ra, and the color temperature of the present example and the comparative example by lighting the lamp at a constant input of 35 W. Shown in

[0134]

TABLE 5 lamps second halide lamp voltage luminous efficiency color rendering color temperature (V) (lm / W) (Ra) (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 lamp voltage of the comparative example, but determined by the amount of enclosed mercury, in this embodiment the second halogen It is determined by the amount of evaporation of the compound. Therefore, by keeping the temperature of the arc tube good, a required lamp voltage can be easily obtained. As can be understood from Table 5, in this embodiment, the lamp voltage is lower than that of the comparative example, but is 50 V or more, and this kind of small head-type short arc metal halide lamp for a headlight has an electronic lighting circuit. There is no practical problem because it is used for lighting. In terms of characteristics, the luminous efficiency is slightly inferior, but the color rendering properties tend to be improved since the added metal (such as aluminum Al) emits light in the visible region.

FIG. 7 is a chromaticity diagram showing a change in chromaticity of the lamp 2 of Table 5 in the second embodiment of the present invention and the lamp 1 of the comparative example.

The chromaticity diagram is based on Japanese Industrial Standard JIS D
5500-1984 shows the chromaticity range of white described in the description of automotive lamps. A curve C in the figure indicates a change in chromaticity according to the present embodiment. Curve D is
7 shows a change in chromaticity of a comparative example. The number given near the measurement point of each curve indicates the elapsed time (second) after the start of lighting. These measurements were performed for each lamp immediately after power-on for 2.6.
A lamp current of A was passed, the current was gradually reduced, and lighting was performed using an electronic lighting circuit set to perform constant power control to a rated lamp power of 35 W.

As is apparent from the figure, in this example, the light emission entered the white range within 0.5 seconds after lighting, whereas in the comparative example, the light emission entered the white range after 18 seconds.

Next, Table 6 shows the results of measuring the average color rendering index Ra and the color temperature (K) when the lamps 2 and 1 in Table 5 were turned on at lamp inputs of 15 W, 20 W, 25 W and 30 W.

[0139]

Table 6 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 66 Color temperature (K) 4280 4220 4110 4040 Lamp 1 (Comparative example) Since the vapor pressure of mercury is high, the mercury is completely 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, and conversely the color rendering properties decrease, so the comparative example is suitable for dimming in a practical sense. You will understand that there is no.

On the other hand, the lamp 2 (this embodiment)
It can be understood that there is little change in both the color rendering property and the color temperature, and it is sufficiently suitable for light control.

Table 7 shows the results of measurement of the restart voltage at the time of instantaneous restart (hot restart) in this embodiment. In the measurement, the restart voltage was measured when the lamp was turned on and off for 30 minutes and restarted after 10 seconds. In addition,
When the light-off time becomes longer, the electrode temperature decreases, and starting becomes difficult. On the other hand, the vapor pressure of mercury and metal halide in the arc tube decreases as the light-out time increases, and the starting becomes easier. As a result of these conflicting tendencies, restarting is most difficult to start with a turn-off time of about 10 seconds.

[0142]

Table 7 Lamp Second halide restart voltage (kV) 1 (conventional example)-15.22 AlI ₃ 8.7 3 FeI ₂ 9.14 ZnI ₂ 9.6 5 MnI ₂ 9.3 6 GaI ₃ 8.3 lamp 1 (comparative example), because of still high mercury vapor pressure, the starting voltage is high.

On the other hand, lamps 2 to 6 (this embodiment)
During the steady lighting, the metal vapor pressure of the second metal halide is clearly lower than that of mercury. Nevertheless, 10 seconds after the light is turned off is when the difference between the vapor pressure of the metal halide and the vapor pressure of mercury is the smallest. This indicates that the present embodiment has a much better restart characteristic than the conventional example in which mercury is sealed.

Next, Table 8 shows the results of measuring the color characteristics near the electrodes when the lamp of this embodiment was lit by DC. Note that this is obtained by projecting the lamp on a screen when the lamp is turned on at a lamp input of 35 W, and measuring the color temperature (K) near the anode and near the cathode.

[0145]

Table 8 Lamp Second halide Anode side color temperature (K) Cathode side color temperature (K) 1 (conventional 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 color temperature difference with a headlight design.

On the other hand, lamps 2 to 6 (this embodiment)
Is suitable for practical use because the color temperature difference is small.

Embodiment 3 This embodiment is directed to a short arc type metal halide lamp for a headlight shown in FIG. 5, in which both ends of an outer tube 21 are hermetically sealed to sealing portions 1b, 1b of an arc tube 1, respectively. Is provided with a vacuum. Other configurations are the same as those of the second embodiment.

The results obtained by measuring the lamp voltage (V), the luminous efficiency (lm / W), the color rendering (average color rendering index) Ra, and the color temperature (K) for this example and the comparative example are shown below. It is shown in FIG. The comparative example is the same as the present example except that 1 mg of mercury was sealed in place of the second halide.

[0148]

Table 9 Lamp Second halide Lamp voltage Luminous efficiency Color rendering color temperature (V) (lm / W) (Ra) (K) 1 (comparative example) -84 8963 4010 2 AlI ₃ 70 94 68 3890 3 in _{FeI 2 76 91 73 4120 4 ZnI} 2 81 91 68 3720 5 MnI 2 71 92 67 4110 6 GaI 3 80 90 65 4330 in this example, by which the outer tube is evacuated,
As the lamp voltage increases, the luminous efficiency has dramatically improved. On the other hand, in the comparative example, the improvement was only slightly improved.

Embodiment 4 In this embodiment, the discharge medium was sealed as follows in the same structure and size as the short arc metal halide lamp for a headlight shown in FIG. Discharge medium: the first halide is scandium iodide S
0.14 mg of cI _{3 and} 0.1% of sodium iodide NaI.
7 mg, the second halide is zinc iodide ZnI ₂₀ .
4 mg and 0.1 m of the added halide shown in Table 10
g, xenon is 5 atm. The results of measuring the lamp voltage (V), luminous efficiency (lm / W), color rendering (average color rendering index) Ra, and color temperature (K) for this example are shown below. It is shown in FIG.

TABLE 10 lamp added halide lamp voltage luminous efficiency color rendering color temperature _{(V) (lm / W)} (Ra) (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 41 105 SbI ₃ 83 79 66 3810 6 ReI ₂ 86 80 66 3960 The second halide generally has a lower vapor pressure than mercury, but at the same pressure, contributes more to lamp voltage formation than mercury. .

However, since mercury always has a high vapor pressure,
In a small-sized short-arc metal halide lamp for a headlight such as a headlight for a moving object having a rated lamp power of 100 W or less, mercury is completely evaporated. For this reason, the lamp voltage can be adjusted by the amount of mercury charged.

On the other hand, in the case of the present invention in which the second halide is sealed in place of mercury, the vapor pressure of the sealed halide is saturated at the stage of incomplete evaporation, so that the lamp voltage is reduced. No more increase.

However, the lamp voltage can be further increased by enclosing a plurality of the second halides as in this 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 higher when a plurality of second halides are mixed than when one kind is used.

Embodiment 5 In this embodiment, a discharge medium was sealed as follows in the same structure and size as those shown in FIG. Discharge medium: the first halide is scandium iodide S
0.14 mg of cI _{3 and} 0.1% of sodium iodide NaI.
7 mg, the second halide was 0.4 mg of the halide shown in Table 11, the third halide was cesium iodide C
0.1 mg of sI and 5 atm of xenon Further, as a comparative example, a device having the same specifications as the present embodiment except that 1 mg of mercury was sealed in place of the second halide was produced.

In this example and the comparative example, the lamp was lit at a constant input of 35 W, and the lamp voltage (V), luminous efficiency (lm / W), color rendering (average color rendering index) Ra, and color temperature were obtained. Table 11 shows the measurement results of (K).

[0153]

Table 11 lamps second halide lamp voltage luminous efficiency color rendering color temperature (V) (lm / W) (Ra) (K) 1 ( conventional example) - 83 86 63 4140 2 AlI 3 63 93 68 3940 3 in _{FeI 2 68 92 70 4180 4 ZnI} 2 73 94 66 3800 5 MnI 2 65 94 65 4200 6 GaI 3 75 92 65 4310 in this example, by the addition of cesium iodide CsI as the third halide, color rendering Although the property Ra and the color temperature hardly change, 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 was sealed, no improvement in efficiency was observed even when the third halide was added.

Further, since there is no emission of mercury having a low luminous efficiency, the luminous efficiency becomes higher than that of the comparative example.

Next, Table 12 shows the luminous efficiency (lm / W) of the lamp 3 when the amount of the third halide, cesium iodide CsI, was changed.

[0156]

[Table 12] CsI sealing amount (mg) Luminous efficiency (lm / W) 0.005 83 0.01 85 0.05 88 0.1 92 0.3 91 0.5 90 1.0 1.0 89 2.0 84 2 0.579 From Table 12, the addition of CsI is effective from 0.01 mg. Conversely, if the addition amount is too large, the vapor pressure of the luminescent metal is lowered, resulting in a decrease in efficiency.

Further, Table 13 shows the results of measurement of the restart voltage at the time of instantaneous restart (hot restart) under the same conditions as in Embodiment 2 for this embodiment.

[0158]

Table 13 Lamp Second halide Restart voltage (kV) 1 (conventional example)-15.22 AlI ₃ 9.2 3 FeI ₂ 9.6 4 ZnI ₂ 10.15 MnI ₂ 9.8 6 GaI ₃ 8.9 In this example, the restart voltage was much lower than in the comparative example in which mercury was sealed, but slightly lower than in the case where the third halide, cesium iodide CsI, was not sealed. The starting voltage tends to be high. However, there is no problem in practice.

FIG. 8 is a front view showing an arc tube in a third embodiment of a short arc type metal halide lamp for a headlight according to the present invention. In the figure, the same parts as those in FIG.

This embodiment is constructed so that DC lighting is performed.
Is different. In the figure, 2 _KIs the cathode, 2_AIs positive
It is a pole. Cathode 2_KIs relatively thin, anode 2_AIs relative
Thick.

In order to manufacture the arc tube IB of the short arc type metal halide lamp for a headlight having the above structure, first, a sealed tube for forming a sealing portion 1a at both ends of the hermetic container 1 is prepared. I do.

Next, after inserting the connecting 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 using an oxyhydrogen burner, and pinched. sealed with seals to seal the cathode 2 _K in the airtight container 1.

Then, the first and second halides are sealed in the hermetic container 1 from the other sealing tube in a nitrogen gas atmosphere, and the connection assembly of the anode 2 _A , the molybdenum foil 3 and the external lead wire 4 is assembled. Is inserted into the sealing tube, and a predetermined distance between the electrodes is set to 4.2 mm.

Further, these assemblies are mounted on an exhaust system via a sealing pipe to evacuate the hermetic container 1, and then, after introducing xenon at 2 atm, the other hermetic container is cooled while cooling the hermetic container 1. 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. Hereinafter, Example 6 of the present embodiment will be described.

Embodiment 6 Airtight container: Enclosure is 4 mm in inner diameter and 7 m in length
m: elliptical sphere, sealing part is 30 mm in length Electrode: cathode 2 _K is 0.4 mm in diameter, tungsten rod with thorium of 6 mm in length, anode 2 _A is 0.8 m in diameter
m, tungsten rod with a length of 6 mm Sealing metal foil: width 1.5 mm, length 15 mm, thickness 15μ
Molybdenum foil External lead wire: Conductor 0.5 mm in diameter and 25 mm in length Discharge medium: The first halide is scandium iodide S
0.17 mg of cI _3, 0.83 of sodium iodide NaI
mg, the second halide was ZnI ₂ 0.4
mg, lamp 3 was AlI ₃ 0.2 mg, lamp 4 was Fe
I ₂ 0.4 mg As a comparative example (lamp 1), one having the same specification as that of the present example was manufactured except that 1 mg of mercury was sealed in place of the second halide.

The luminous efficiency (lm / W) of the lamp 2 (this embodiment) and the lamp 1 (comparative example) when the lamp input was turned on at 20 W, 25 W, 30 W and 35 W with respect to the rated power of 35 W Table 14 shows the results of measurement of the color rendering properties (average color rendering index) Ra and the color temperature (K).

[0166]

Table 14 Lamp Lamp Power Luminous Efficiency Color Rendering Color Temperature (W) (lm / W) (Ra) (K) 1 (Comparative Example) 20-45 4970 35 80 65 4100 220-64 4400 25-66 4310 30 -69 4240 35 75 70 4190 FIG. 9 is a chromaticity diagram showing the rise of the chromaticity characteristics of the lamp 2 in Example 6 in comparison with the comparative example. In the drawing, a curve E indicates the rising of the light beam in the present embodiment. Curve F shows the rising of the luminous flux of the comparative example.

This embodiment is in the white area from the beginning of lighting. In the comparative example, it took about 1 minute to enter the white area.

Next, each lamp was turned on for 60 minutes at 42 W, which is 20% of the rated lamp power, and turned off for 15 seconds, and a flashing test was conducted to check whether or not the airtight container ruptured. There were no ruptures.

Table 15 shows the results of the measurement of the restart voltage required for the instantaneous restart two seconds after the light was turned off.

[0170]

Table 15 Lamp restart voltage (kV) 1 12 2 5 3 4 4 4.3 FIG. 10 shows a short-circuit type metal halide lamp for a headlamp according to the third embodiment of the present invention shown in FIG. 6 is a graph showing a relationship with a luminous flux rising time when a gas sealing pressure is changed. In the figure, the horizontal axis represents the xenon sealing pressure (atmospheric pressure), and the vertical axis represents the luminous flux rise time (seconds).
Are respectively shown.

From the figure, it was found that when the xenon sealing pressure was 1 atm or more, the luminous flux rising time was sharply reduced, and it became practical.

FIG. 11 shows the amount of ZnI ₂ encapsulated (mg) as the second halide in the third embodiment.
/ Cc) is a graph showing the relationship between the lamp voltage (V) when changing / cc).

From the figure, it can be understood that if ZnI ₂ is encapsulated in an amount of 1 mg / cc or more, it is possible to increase the lamp voltage to a desired value of 30 V or more in the case of lighting using an electronic lighting circuit.

FIG. 12 is a circuit diagram showing a first embodiment of the metal halide lamp lighting device of the present invention.

In this embodiment, the metal halide discharge lamp is configured to be lit by DC.

In the figure, 71 is a DC power supply, 72 is a chopper, 73 is control means, 74 is lamp current detection means, 7
5 is a lamp voltage detecting means, 76 is a starting means, and 77 is a metal halide discharge lamp.

As the DC power supply 71, a battery or a rectified DC power supply is used. In the case of a moving object, a battery is generally used. However, a rectified DC power supply that rectifies AC may be used. If necessary, an electrolytic capacitor 71a is connected in parallel to perform smoothing.

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

The control means 73 controls the chopper 72. For example, immediately after lighting, a lamp current of three times or more of the rated lamp current is supplied to the metal halide discharge lamp 77 from the chopper 72, and thereafter, the lamp current is gradually reduced over time, and control is performed so that the rated lamp current is eventually reached. I do.

The lamp current detecting means 74 is inserted in series with the lamp, detects the lamp current, and inputs the control to the control means 73.

The lamp voltage detecting means 75 is connected in parallel with the lamp, detects the lamp voltage, and inputs the control to the control means 73.

The control means 73 generates a constant power control signal when the detection signals of the lamp current and the lamp voltage are fed back and controls the chopper 72 at a 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, the control means 73 supplies a lamp current of three times or more of the rated lamp current to the metal halide discharge lamp 77, and as time passes. The chopper 72 is controlled so as to reduce the lamp current.

The starting means 76 is configured to supply a pulse voltage of 20 kV to the metal halide discharge lamp 67 at the time of starting.

Thus, according to the present embodiment, a required luminous flux is generated immediately after lighting while direct current lighting. As a result, the luminous flux is 25% of the rating one second after the power is turned on, which is necessary as a headlight for a moving body such as an automobile, and the luminous flux 8 seconds after the power is turned on.
0% lighting can be realized.

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

FIG. 13 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.

This embodiment is different from the first embodiment in that the metal halide discharge lamp is configured to be operated by alternating current.

Reference numeral 78 denotes AC conversion means. This AC conversion means 78 comprises a full-bridge inverter. That is, a pair of switching circuits 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. The high frequency alternating current is generated between the output terminals of the bridge circuit by alternately supplying them to the means.

Then, the metal halide discharge lamp 77 is turned on by high frequency alternating current.

In this AC lighting type configuration, FIG.
The same control as in No. 2 is performed.

FIG. 14 is a conceptual diagram showing a headlight according to a second embodiment of the present invention.

FIG. 15 is a conceptual diagram showing the same optical distributor.

In the figure, 81 is a lighting circuit, 82 is a light distributor, 83 is a main optical fiber, 84 is an optical shutter 8
5 is an individual optical fiber and 86 is a lamp.

As the lighting circuit 81, the lighting circuit shown in FIG. 12 or 13 can be used.

The light distributor 82 includes a case 82a, a light-collecting / reflecting surface 82b, a metal halide discharge lamp 82c, and an optical connector 82d. Then, light generated from the metal halide discharge 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 optical distributor 82 to the optical shutter 84.

The optical shutter 84 has an individual fiber 85
, And selectively transmitted to each lamp 86.

The lighting device 86 includes a high beam lighting device 86a, a low beam lighting device 86b, and a fog lighting device 86c, one set of which is disposed on both front sides of a moving body such as an automobile.

Embodiment 7 This embodiment is a short arc type metal halide lamp for a headlight suitable for use in the second embodiment of the headlight shown in FIG. Rated lamp power: 80 W Inter-electrode distance: 2 mm Other structure: Same as FIG. Discharge medium: the first halide is scandium iodide S
0.3 mg of cI ₃ , 1.5 m of sodium iodide NaI
g, the second halide was lamp 1 with ZnI ₂ 1 mg,
AlI _{3 1mg,} MnI 2 _1mg, lamp 3 ZnI _{2
2mg, GaI 3 1mg, CrI 2} 1mg, xenon five atmospheres also one may manufacture those of Comparative Example (lamp 1) Other encapsulating mercury 15mg in place of the second halide present embodiment the same specifications did.

Thus, this example and the comparative example were rated 8
The lamp is lit at 0 W constant, and the lamp voltage (V) and the luminous efficiency (lm
/ W), color rendering (average color rendering index) Ra, and color temperature (K) are shown in Table 15.

[0200]

Table 15 Lamp Lamp Voltage Luminous Efficiency Color Rendering Color Temperature (V) (lm / W) (Ra) (K) 1 (Conventional Example) 63 94 63 4020 2 58 88 68 3920 3 62 89 69 4110 Understand from Table 15 In this embodiment, almost the same characteristics as in the comparative example in which mercury is sealed can be obtained. Further, in the headlight shown in FIG. 14, the necessity of dimming by changing the input increases, and it is extremely useful that dimming is possible in that respect.

[0201]

According to the first aspect of the present invention, the inner volume is equal to 0.
005 to 0.1 cc of a fireproof and translucent airtight container, a pair of electrodes having a distance between the electrodes of 6 mm or less, a first halide made of a halide containing at least sodium Na and scandium Sc, and having a vapor pressure of One or more metals that are relatively large and are less likely to emit light in the visible region than the metal of the first halide, and are composed of 1 mg or more of a halide per 1 cc of the inner volume of the hermetic container. Short-arc metal halide lamp for a headlight, which has the following effects by being essentially free of mercury and having a discharge medium sealed in an airtight container containing a compound and a rare gas. Can be provided.

1. In an optical system using a reflecting mirror, high light-collecting efficiency can be obtained.

2 The chromaticity rise at the start is good.

(3) Instant restart is facilitated.

4 Dimming becomes possible.

5 Burst during lighting of the airtight container is reduced.

6. Variation in emission color with respect to variation in shape and size is small.

7 White light emission can be obtained with high luminous efficiency.

8 The arc tube can be mechanically protected by the outer tube, and the heat loss can be reduced to maintain the luminous efficiency at a high value.

9. It is also suitable for DC lighting.

According to the second aspect of the present invention, the airtight container, the pair of electrodes, the first halide made of a halide containing sodium Na and scandium Sc, the vapor pressure is relatively large, and A second halide comprising a metal halide which is less liable to emit light in the visible region than the metal of the first halide, and a discharge medium containing xenon at 1 atm or more, essentially containing mercury Since it is not performed, it is possible to provide a short arc type metal halide lamp for a headlamp having excellent chromaticity rising characteristics and luminous flux rising characteristics at the time of starting.

According to a third aspect of the present invention, there is provided a short arc metal halide lamp for a headlight according to the first or second aspect,
By providing an electronic lighting device for energizing a short arc type metal halide lamp for a headlight, it is possible to provide a metal halide lamp lighting device having the effects of claim 1 or 2.

According to the invention of claim 4, the headlight according to claim 1 or 2, wherein the headlight is provided with a reflecting mirror, and the light is incident on the reflecting mirror of the headlight main body. By providing a short arc type metal halide lamp for a lamp and an electronic lighting device for energizing the short arc type metal halide lamp for a headlight, a headlight having the effects of claim 1 or 2 is provided. be able to.

[Brief description of the drawings]

FIG. 1 is a graph showing respective arc temperatures in a short arc type metal halide lamp in which a second halide is sealed in place of mercury and an example in which mercury is sealed.

FIG. 2 is a front view of a short section arc-type metal halide lamp for a headlight according to a first embodiment of the present invention, which is taken along a center section.

FIG. 3 is a graph showing the relationship between the filling pressure of xenon Xe and the luminous flux rise time in the first embodiment of the short arc metal halide lamp for a headlight according to the present invention.

FIG. 4 is a graph showing a relationship between a charged amount and a lamp voltage in a case where iron iodide FeI 2 is used as a second halide in the first embodiment.

FIG. 5 is a front view showing a second embodiment of a short arc type metal halide lamp for a headlight according to the present invention.

FIG. 6 is a perspective view showing a first embodiment of a headlight according to the present invention.

FIG. 7 is a chromaticity diagram showing a change in chromaticity of the lamp 2 of Table 5 and the lamp 1 of the comparative example in Example 2 of the present invention

FIG. 8 is a front view showing a third embodiment of a short arc type metal halide lamp for a headlight according to the present invention.

FIG. 9 is a chromaticity diagram showing the rise of the chromaticity characteristics of the lamp 2 in Example 6 in comparison with a comparative example.

FIG. 10 is a graph showing the relationship between the rising time of a luminous flux when the pressure of filling a rare gas is changed in the third embodiment of the short arc type metal halide lamp for a headlight of the present invention shown in FIG.

FIG. 11 is a graph showing the relationship between the lamp voltage (V) and the amount (mg / cc) of ZnI ₂ as the second halide in the third embodiment.

FIG. 12 is a circuit diagram showing a first embodiment of a metal halide lamp lighting device of the present invention.

FIG. 13 is a circuit diagram showing a second embodiment of the metal halide lamp lighting device of the present invention.

FIG. 14 is a conceptual diagram showing a second embodiment of a headlight according to the present invention.

FIG. 15 is a conceptual diagram showing a part of the optical distributor.

FIG. 16 is a conceptual diagram for explaining a lamp voltage in a metal halide lamp.

FIG. 17 is a graph showing the emission spectrum distribution of a conventional short arc metal halide lamp for floodlighting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Airtight container 1a ... Surrounding part 1b ... Sealing part 2 ... Electrode 2a ... Electrode shaft 3 ... Sealing metal foil 4 ... External lead wire IB ... Arc tube IT ... Insulating tube OB ... Outer tube

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) // F21W 101: 10 F21Y 101: 00 F21Y 101: 00 F21M 3/02 G (31) Claim number of priority Ganpei 9-346035 (32) Priority date December 16, 1997 (December 16, 1997) (33) Priority claiming country Japan (JP) (72) Inventor Mikio Matsuda 4-chome Higashishinagawa, Shinagawa-ku, Tokyo No. 3-1 Toshiba Litec Co., Ltd. (72) Inventor Toshio Hiruda 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo F-term in Toshiba Litec Co., Ltd. 3K042 AA08 AC06 3K072 AA13 BA03 GA02 GB18 5C015 PP05 PP07 QQ03 QQ14 RR05 5C039 HH03 HH04

Claims (4)

[Claims] 1. A fire-resistant and translucent airtight container having an inner volume of 0.005 to 0.1 cc; a pair of electrodes sealed in the airtight container and having a distance between electrodes of 6 mm or less; A first halide made of a halide containing Na and scandium Sc, one or more kinds of metals having a relatively large vapor pressure and hardly emitting light in the visible region as compared with the metal of the first halide; Of 1 mg or more of halide per 1 cc of airtight container volume
A short arc metal halide lamp for a headlight, characterized by comprising essentially a halide and a discharge medium containing a rare gas and enclosed in an airtight container. 2. A refractory and translucent airtight container; a pair of electrodes sealed in the airtight container;
a first halide comprising a halide containing a and scandium Sc; one or more metals having a relatively high vapor pressure and less luminescence in the visible region than the metal of the first halide And a discharge medium containing at least 1 atm of xenon and sealed in an airtight container, wherein essentially no mercury is sealed. Short arc metal halide lamp for lighting. 3. A short arc type metal halide lamp for a headlight according to claim 1 or 2, and an electronic lighting device for energizing the short arc type metal halide lamp for a headlight. Metal halide lamp lighting device. 4. A short-arc metal halide lamp for a headlight according to claim 1, wherein the headlight body includes a reflector; and the light-emitting device is disposed so that light is incident on the reflector of the headlight body. And an electronic lighting device for energizing the short arc type metal halide lamp for a headlight.