JP2004220879A - Metal halide lamp for automobile head-light and head-light apparatus for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal halide lamp for an automobile head-light where by optimizing an upper hemispherical flux and a lower hemispherical flux, the coloration of an irradiation center at the low beam, the difference in color between the high beam and low beam, and the unclearness of an illumination pattern are prevented, and to provide a headlight apparatus using this. <P>SOLUTION: The metal halide lamp HPDL for an automobile headlight has a discharge container IT which has a refractory and transparent airtight container 1aT where a discharge space 1c with an inside diameter of not less than 1.5 mm is formed and a pair of electrodes 1b with a distance between the electrodes of not more than 5 mm; and the discharge medium which is sealed in an airtight container 1a and does not essentially include mercury, including a light-emitting metal and metal halide for use in the lamp voltage formation, as well as xenon having five or higher atmospheric pressure at room temperature. In the lamp, a tube wall load in the stable lighting is not less than 50 W/cm<SP>2</SP>, a lamp electric power in the stable lighting is not more than 60 W, and the upper hemispherical flux A and the lower hemispherical flux B of the discharge container IT in a horizontally lighted state satisfy equation 1 (A≥B≥0.6 A). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a metal halide lamp for a vehicle headlight and a vehicle headlight device using the same.
[0002]
[Prior art]
A metal halide lamp in which a rare gas, a luminescent metal halide, and mercury are sealed in an arc tube provided with a pair of electrodes facing each other has been widely used because of its relatively high efficiency and high color rendering. The use of metal halide lamps has also become widespread for automotive headlights. Metal halide lamps currently in practical use, including those for automobile headlights, require mercury. In addition, in the specification of a metal halide lamp for a vehicle headlight, it is indispensable that about 2 to 15 mg of mercury is enclosed (hereinafter, referred to as "lamp containing mercury" for convenience) (for example, see Patent Document 1).
[0003]
However, as environmental problems are becoming more serious, it is considered very important in the lighting field to reduce mercury, which has a large environmental load, from lamps and further eliminate them.
[0004]
In order to solve this problem, some proposals have been made not to use mercury in metal halide lamps (for example, see Patent Document 2). In Patent Document 2, in place of mercury, a metal halide for forming a lamp voltage having a high vapor pressure such as ZnI ₂ is added to a halide of a luminescent substance, for example, ScI ₃ —NaI, and sealed, so that a metal halide containing mercury is enclosed. 2. Description of the Related Art A metal halide lamp for a vehicle headlight (hereinafter, referred to as "mercury-free lamp" for convenience) having the same electrical characteristics and light emission characteristics as a lamp has been obtained.
[0005]
In general, a metal halide lamp for a vehicle headlight is horizontally lit. The reflector and / or front lens of an automobile headlamp is designed so as to satisfy a predetermined light distribution characteristic by optically effectively using an upper hemisphere light flux and a lower hemisphere light flux of a metal halide lamp.
[0006]
[Patent Document 1]
JP-A-2-7347 [Patent Document 2]
Japanese Patent Application Laid-Open No. H11-238488 [Problems to be Solved by the Invention]
The mercury-free lamp is different from the mercury-containing lamp in the following points. That is,
1. In a mercury-free lamp, in addition to a metal halide in a mercury-containing lamp (hereinafter, referred to as “first halide” for convenience), a metal halide having a lower melting point (hence, a higher vapor pressure) (hereinafter, referred to as “first halide” for convenience). 2 halide).). The second halide has the effect of increasing the lamp voltage, improving the system efficiency, and reducing the size and cost of the ballast. In addition, it has the function of correcting chromaticity instead of mercury. Furthermore, since the melting point of the entire mixed halide of the first halide and the second halide is reduced, the time required for the mixed halide to melt after starting is significantly reduced.
[0007]
On the other hand, in a mercury-free lamp for a headlight, a power that is twice or three times that of a stable state is applied for about 4 to 8 seconds at the time of starting, so that the rise of the luminous flux is accelerated. In a mercury-containing lamp, it takes about 10 seconds or more for the halide to evaporate and start emitting light, so the halide evaporates when the lamp power starts to decrease. On the other hand, in the mercury-free lamp, since the melting point of the halide is low as described above, the halide melts and evaporates during the period of 4 to 8 seconds when high power is applied, and starts emitting light. The halide melts rapidly and the area of the halide film tends to increase. Therefore, the mercury-free lamp tends to have a larger halide film area even when it is stable.
[0008]
2. In a mercury-free lamp, the maximum input power at start-up is controlled to be about two to three times the lamp power in a stable state, so that the halide melts more rapidly and the area of the halide film tends to increase. is there. On the other hand, in the lamp containing mercury, the maximum input power at the time of starting is less than twice the lamp power at the time of stability.
[0009]
3. In mercury-free lamps, the arc tends to be narrow.If this is used for a headlight, the boundary between the light from the halide-attached part and the light from other parts will be It may be more noticeable than the entering lamp, which is not preferable.
[0010]
4. In a mercury-free lamp, the xenon filling pressure is higher than that of a mercury-containing lamp, and accordingly, the buoyancy of the arc increases, and the amount of heat transferred to the inner surface at the upper center of the discharge vessel tends to further increase. Therefore, the central portion of the discharge space becomes relatively high in temperature as a whole. The surplus halide during lighting adheres to the center of the lower part of the discharge space in the form of a liquid, so that this portion becomes higher in temperature as a whole, and as a result, the surplus halide tends to spread toward the electrode, and There is a tendency that the adhesion area of the particles further increases.
[0011]
From the above points, in the mercury-free lamp, the area of the halide film tends to be large at the time of startup and at the time of stability.
[0012]
Generally, when a metal halide lamp is used for a vehicle headlight, there is a possibility that the metal halide lamp is used for both a so-called high beam and a low beam.
[0013]
However, unlike a halogen bulb in which the upper and lower hemisphere luminous fluxes are equal, in a metal halide lamp, during lighting, excess halide in the discharge medium accumulates below the discharge vessel and forms a film. Tend to be reduced from the upper hemispherical luminous flux and to be colored in a halide-specific color. In a mercury-free lamp, this tendency becomes extremely prominent for the reasons described above.
[0014]
The present inventor has discovered that in the case of a mercury-free lamp, if the ratio between the upper hemispherical luminous flux and the lower hemispherical luminous flux is not appropriate, there are the following problems. In other words, even if the mercury-free lamps have the same total luminous flux, when comparing a lamp with a relatively low luminous flux in the lower hemisphere and a lamp with a high luminous flux, in the low beam mainly using the upper hemispherical luminous flux, the former is brighter, but the lower hemisphere The same is true for a high beam that uses both the light beam and the upper hemisphere light beam. However, in the former case, in the former case, the downward radiation has a large coloring ratio due to the halide film, and in comparison with the latter, in the low beam state, the irradiation center part (this part is obliquely downward and obliquely upward radiation). Light mainly contributes), there is a problem that coloring due to a halide film occurs.
[0015]
In addition, even at the time of the high beam, coloring by the halide film is observed on the entire irradiation surface, and there is a problem that a gap with the light color at the time of the low beam occurs.
[0016]
Further, in the former case, there is also a problem that the irradiation pattern becomes unclear due to the halide film.
[0017]
The above problem exists regardless of whether the metal halide lamp for a headlight of an automobile is dedicated to a low beam, dedicated to a high beam, or both. In a mercury-free lamp for a vehicle headlamp, the ratio between the upper hemisphere light flux and the lower hemisphere light flux needs to be optimized in order to improve the above-mentioned problem.
[0018]
However, the prior art does not disclose the necessity of optimizing the upper hemisphere light flux and the lower hemisphere light flux of a metal halide lamp for a vehicle headlight and the solution thereof.
[0019]
The present invention provides a metal halide lamp for an automotive headlight that optimizes the upper and lower hemispherical luminous fluxes to prevent problems such as coloring of an irradiation center at the time of a low beam, color difference between a high beam and a low beam, and unclear irradiation pattern. It is an object of the present invention to provide a vehicle headlight device using the same.
[0020]
[Means for achieving the object]
The metal halide lamp for a vehicle headlight according to the first aspect of the present invention is a fire-resistant and translucent airtight container having a discharge space with an inner diameter of 1.5 mm or more formed therein and opposed to both ends of the discharge space in the airtight container. And a discharge vessel provided with a pair of electrodes having a distance between electrodes of 5 mm or less; a light-emitting metal, a halide of a metal for forming a lamp voltage, and xenon at room temperature of 5 atm or more, and sealed in an airtight vessel. A discharge medium which is substantially free of mercury and has a tube wall load of 50 W / cm ² or more during stable operation, a lamp power of 60 W or less during stable operation, and a horizontal operation state. Is characterized in that the upper hemispherical light beam A and the lower hemispherical light beam B satisfy Expression 1.
[0021]
(Equation 1)
A ≧ B ≧ 0.6 × A
In the present invention and each of the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified.
[0022]
<About Discharge Vessel> The discharge vessel includes an airtight vessel and a pair of electrodes.
[0023]
(About the airtight container) The airtight container is fire-resistant and translucent. "Fire resistance" means sufficiently resistant to the normal operating temperature of the discharge lamp. Therefore, the airtight container may be made of any material as long as it is a material having fire resistance and can emit visible light of a desired wavelength range generated by electric discharge to the outside. For example, it can be formed using quartz glass, translucent alumina, ceramics such as YAG, or a single crystal thereof. If necessary, it is permissible to form a halogen-resistant or halide-resistant transparent coating on the inner surface of the hermetic container or to modify the inner surface of the hermetic container.
[0024]
In the hermetic container, a discharge space having an appropriate shape, for example, an elongated discharge space, is formed. The elongated discharge space may be, for example, a cylindrical discharge space. This causes the arc to bend upward during horizontal lighting, so that the arc approaches the inner surface on the upper side of the discharge vessel, so that the temperature of the upper portion of the discharge vessel rises faster.
[0025]
Further, the thickness of the portion surrounding the discharge space can be made relatively large. That is, the thickness at the substantially central portion of the distance between the electrodes can be made larger than the thickness at both sides. As a result, the heat transfer of the discharge vessel becomes good, and the temperature rise of the discharge medium attached to the lower part and the inner surface of the side of the discharge space of the discharge vessel becomes faster, so that the light flux rises faster.
[0026]
(Regarding a pair of electrodes) The pair of electrodes is sealed inside the both ends of the airtight container so as to be spaced apart from each other, and the distance between the electrodes is set to 5 mm or less.
[0027]
Note that the electrodes may be configured to operate with either AC or DC. When operating with alternating current, the pair of electrodes have the same structure. In the case of a metal halide lamp for a vehicle headlight, the vicinity of the tip of the electrode can be made larger in diameter than the shaft. In other words, the number of times the lamp blinks becomes extremely large, and a large current flows at the time of starting. Therefore, if the diameter of the entire electrode is correspondingly increased, the material of the hermetic container in contact with the electrode shaft is increased. Is subject to thermal stress each time it flashes, and cracks easily occur. Thus, by forming a large-diameter portion near the tip of the electrode, the electrode can be made to respond to flickering, but the shaft portion is not large in diameter, so that cracks are less likely to occur. In the case of operating with a direct current, the temperature of the anode generally rises sharply. Therefore, if a large diameter portion is formed in the vicinity of the front end portion, the heat radiation area can be increased and frequent blinking can be dealt with. On the other hand, the cathode does not necessarily need to form a large diameter portion.
[0028]
<Regarding Discharge Medium> In the present invention, the discharge medium contains a metal halide and xenon, and contains essentially no mercury.
[0029]
(Regarding Metal Halide) The metal halide includes a luminescent metal and a halide of a metal for forming a lamp voltage.
[0030]
The halide of the luminescent metal is not particularly limited, but is preferably a halide mainly containing sodium Na and scandium Sc. If desired, a halide such as indium In or a rare earth metal can be added. Note that indium contributes to both the luminescent substance and the formation of the lamp voltage. In addition, light emission of indium In or a rare earth metal is suitable for adjusting the chromaticity of light emission of a metal halide lamp.
[0031]
The halide of the metal for forming the lamp voltage is a metal having a relatively high vapor pressure and effectively contributing to the formation of the lamp voltage, such as zinc Zn, magnesium Mg, cobalt Co, chromium Cr, manganese Mn, antimony Sb, One or more halides selected from the group consisting of rhenium Re, gallium Ga, tin Sn, iron Fe, aluminum Al, titanium Ti, zirconium Zr and hafnium Hf can be used. By selectively encapsulating these metal halides in appropriate amounts, the lamp voltage can be increased to a required range. As a result, the electric characteristics of the metal halide lamp can be set as desired, so that the required lamp power can be supplied with a relatively small lamp current. Optimally, it is a halide of zinc Zn. Zinc Zn is a substance that has a relatively high vapor pressure, is chemically safe, and can be obtained at low cost and easily on an industrial scale. The light emission of zinc Zn can also be used for adjusting the chromaticity of light emission of a metal halide lamp.
[0032]
Next, the halogen constituting the halide will be described. That is, with respect to reactivity, iodine is most suitable among halogens, and at least the main luminescent metal is mainly encapsulated as iodide. However, if necessary, different halogen compounds such as iodide and bromide can be used in combination.
[0033]
(About Xenon) Xenon is sealed at room temperature at a pressure of 5 atm or more. In addition, xenon acts as a starting gas and a buffer gas, and also acts as a luminescent material by being sealed at the above pressure, when the vapor pressure of the luminescent metal halide is not high immediately after lighting. Note that, if desired, argon, krypton, or the like can be added. In addition, when xenon is filled at 5 atm or more, it is possible to act so as to take charge of the main light emission immediately after the start in addition to the above. The sealing pressure of xenon is preferably 8 to 15 atm. As a result, the lamp voltage of the metal halide lamp is increased, the lamp input is increased for the same lamp current, and the luminous flux rising characteristics can be improved. Good luminous flux rising properties are advantageous for any purpose of use.
[0034]
(Regarding Mercury) In the present invention, “essentially contains no mercury” means that not only no mercury is sealed but also less than 2 mg, preferably 1 mg or less of mercury per 1 cc of the inner volume of the airtight container. Means to allow However, it is environmentally desirable not to encapsulate any mercury. In the case where the electric characteristics of the discharge lamp are maintained by mercury vapor as in the past, in the case of the short arc type, 20 to 40 mg per 1 cc of the inner volume of the airtight container, and in some cases more than 50 mg are enclosed, In the present invention, it can be said that the amount of mercury is substantially very small.
[0035]
<Regarding Tube Wall Load> In the present invention, the tube wall load must be 50 W / cm ² or more during stable lighting of the metal halide lamp. In the present invention, “tube wall load” refers to lamp power per unit internal surface area (1 cm ² ) of a discharge space formed inside an airtight container. In order to increase the vapor pressure of the discharge medium and increase the total luminous flux, the tube wall load must satisfy the above conditions.
[0036]
<Regarding Lamp Power> Lamp power is 60 W or less during stable lighting. This means that the metal halide lamp is small.
[0037]
<Relationship Between Upper Hemisphere Light Beam and Lower Hemisphere Light Beam> The upper hemisphere light beam A and the lower hemisphere light beam B need to satisfy Expression 1 in order to maintain the ratio between them under optimum conditions. That is, the lower hemispheric light beam B must be 60% of the upper hemispheric light beam A and be equal to or less than the upper hemispheric light beam A. Note that the upper hemisphere light beam A and the lower hemisphere light beam B are measured with a completed metal halide lamp.
[0038]
First, a method of measuring the upper hemisphere light beam A and the lower hemisphere light beam B will be described. The measurement can be performed by adjusting the light distribution characteristics of the metal halide lamp. That is, the illuminance due to the radiation from the lamp is measured at a position separated by 1 m or more from the emission center of the metal halide lamp, and the illuminance is calculated based on the data. The measurement measures at least the illuminance distribution in the direction of 360 ° with the axis of the lamp as the axis of rotation and the distribution of 360 ° with the axis of rotation in the direction normal to the lamp axis as the axis of rotation. Estimate by calculation approximating a cylinder or line. Thus, the total luminous flux can be obtained by integrating all directions. Further, by integrating only the upper hemisphere and the lower hemisphere, the respective luminous fluxes can be measured.
[0039]
Next, a description will be given of a main specific configuration for satisfying Expression 1.
[0040]
1. Increase the inner diameter of the airtight container and reduce the wall thickness. As a result, the temperature of the lower surface of the discharge space decreases, and the attachment position of the discharge medium concentrates on the lower surface, and as a result, the lower hemispherical luminous flux increases.
[0041]
2. Reduce the amount of discharge medium enclosed. As a result, the area of the discharge medium adhered decreases, and as a result, the lower hemisphere luminous flux increases.
[0042]
3. Increase the thickness of the airtight container. As a result, the temperature of the lower part of the discharge space decreases, and the position where the discharge medium adheres is concentrated on the lower surface, and as a result, the lower hemispheric light flux increases.
[0043]
<Other Configurations of the Present Invention> By selectively adding the configurations described below, the performance of the high-pressure discharge lamp is improved or the functions thereof are increased.
[0044]
1. Outer tube The outer tube is made of quartz glass, high silicate glass, or the like, and is a means for housing at least a main part of the discharge vessel therein. Then, the ultraviolet rays radiated from the outer tube and the arc tube to the outside are shielded, mechanically protected, and by touching the airtight container of the arc tube by hand, human fingerprints and fats are attached and cause devitrification. Or keep the airtight container warm. Further, the inside of the outer tube may be hermetically sealed with respect to the outside air depending on the purpose, or may be filled with air or an inert gas which has been reduced to the same degree or reduced pressure as the outside air. Further, if necessary, it may communicate with the outside air. Further, a light-shielding film may be provided on the outer surface or the inner surface of the outer tube.
[0045]
Further, when forming the outer tube, both ends of the outer tube are glass-welded to sealing portions extending in the tube axis direction from both ends of the airtight container, so that the outer tube is supported by the airtight container. Can be.
[0046]
2. About the base The base serves to connect the high-pressure discharge lamp to the lighting circuit and additionally to mechanically support it.
[0047]
3. About the igniter The igniter is a means to generate a high-voltage pulse voltage and apply it to the high-pressure discharge lamp to promote its start.It can be integrated with the high-pressure discharge lamp by storing it inside a base or the like. it can.
[0048]
4. Regarding the starting auxiliary conductor The starting auxiliary conductor is a means for increasing the electric field strength near the electrodes to support the starting of the high-pressure discharge lamp. One end is connected to the same potential as the other electrode, and the other end is connected to one end. It is arranged on the outer surface of the airtight container near the electrode.
[0049]
<Regarding the operation of the present invention> In the present invention, by having the configuration described above, the upper hemispherical light beam and the lower hemispherical light beam are optimized, and the irradiation center at the time of the low beam is colored and the high beam is emitted. It is possible to prevent problems such as a low beam color difference and an unclear irradiation pattern.
[0050]
An automobile headlamp apparatus according to the second aspect of the present invention includes: an automobile headlamp apparatus main body; wherein the axis of the discharge vessel is provided in the automobile headlamp apparatus main body along the optical axis of the automobile headlamp apparatus main body. 2. The metal halide lamp according to claim 1, which is provided; and a lighting circuit in which the maximum input power up to 4 seconds immediately after the lighting of the metal halide lamp is 2 to 4 times the lamp power in a stable state. And
[0051]
Since the vehicle headlight device of the present invention includes the metal halide lamp of claim 1 as a light source, the light flux is fast and safe, and the metal halide lamp does not encapsulate mercury with a large environmental load. Extremely favorable in environmental measures. Note that the “vehicle headlight device main body” means all remaining portions of the vehicle headlight device excluding the metal halide lamp and the lighting circuit.
[0052]
The lighting circuit uses a maximum input power of up to 4 seconds immediately after the lighting of the metal halide lamp to be 2 to 4 times, preferably 2.5 to 4 times the lamp power at the time of stability, so that the rising of the luminous flux is for a vehicle headlight. As fast as possible to get within the required range. In addition, when the filling pressure of xenon as a rare gas is X (atmospheric pressure) in the range of 3 to 15 atm and the maximum input power up to 4 seconds immediately after the lighting of the metal halide lamp is AA (W), AA is expressed by the following equation. With this configuration, it is possible to accelerate the rise of the luminous flux up to 4 seconds immediately after lighting, and obtain a luminous intensity of 8000 cd at a representative point on the front of the headlight required for a vehicle headlight.
[0053]
AA> -2.5X + 102.5
Since only the discharge medium having a low vapor pressure has a linear relationship between the xenon filling pressure and the maximum input power as described above, the xenon emission becomes overwhelming at 4 seconds after the start. Because there is. Since the amount of xenon light emission is determined by the xenon sealing pressure and the power at that time, the input power may be increased if the xenon pressure is low. Conversely, if the xenon pressure is high, the input power may be reduced. In the present invention, lighting of the metal halide lamp may be either AC lighting or DC lighting.
Further, the lighting circuit can be configured to have a no-load output voltage of 200 V or less as required. The metal halide lamp used in the present invention generally has a lower lamp voltage than a mercury-filled metal halide lamp, so that the no-load output voltage of the lighting circuit can be 200 V or less. Thus, the lighting circuit can be downsized. Incidentally, a mercury-filled metal halide lamp requires a no-load output voltage of about 400V.
[0054]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0055]
1 to 3 show a first embodiment of a metal halide lamp for a vehicle headlight according to the present invention, FIG. 1 is a front view of the entire lamp, FIG. 2 is a front view of an enlarged main part of a discharge vessel, and FIG. 1 is a conceptually enlarged cross-sectional view showing Example 1. FIG. In each figure, IT is a discharge vessel or arc tube, 2 is a sealing metal foil, 3A and 3B are a pair of external lead wires, OT is an outer tube, T is an insulating tube, and B is a base.
[0056]
The discharge vessel IT includes an airtight vessel 1a and a pair of electrodes 1b, 1b. The hermetic container 1a is formed in a hollow spindle shape, has a pair of elongated sealing portions 1a1 integrally at both ends thereof, and has an elongated substantially cylindrical discharge space 1c formed therein. The electrode 1b is supported at a predetermined position by its base end being embedded in the sealing portion 1a1. The base of the electrode 1b is welded to one end of the sealing metal foil 2 in the sealing portion 1a1. In FIG. 1, after the lower sealing portion 1a1 is formed, the sealing tube 1a2 extends integrally from the lower portion of the sealing portion 1a1 without being cut and extends into the base B.
[0057]
The sealing metal foil 2 is airtightly embedded in the sealing portion 1a1 of the airtight container 1a.
[0058]
The pair of external lead wires 3A and 3B have their distal ends welded to the other end of the sealing metal foil 2 in the sealing portions 1a1 at both ends of the hermetic container 1a, and the base ends are led out. In FIG. 1, the external lead wire 3A led upward from the discharge vessel IT is folded back along an outer tube OT described later, introduced into a base B described later, and connected to one of base terminals (not shown). ing. In FIG. 1, an external lead wire 3B extending downward from the discharge vessel IT extends along the tube axis, is introduced into the base B, and is connected to the other of the base terminals.
[0059]
In the airtight container 1a, a metal halide and a rare gas are sealed as a discharge medium. The metal halide contains at least two or more selected from the group consisting of sodium Na, scandium Sc, indium In, and zinc Zn. The rare gas is sealed at an appropriate pressure.
[0060]
The outer tube OT has a function of cutting off ultraviolet rays, accommodates the discharge vessel IT therein, and the reduced diameter portions 4 at both ends are glass-welded to the sealing portion 1a1 of the discharge vessel IT. However, the inside is not airtight and communicates with the outside air.
[0061]
The insulating tube T covers the external lead wire 3A.
[0062]
The base B is standardized for a vehicle headlight, and supports the discharge vessel IT and the outer tube OT along the central axis, and is detachably attached to the back of the vehicle headlight. It is configured to be mounted.
Embodiment 1
Discharge vessel IT
Airtight container 1a: made of quartz glass, sphere length 7 mm, maximum outer diameter 6 mm,
3.5 mm maximum inner diameter, 1.25 mm wall thickness at maximum diameter
Electrode 1b: made of tungsten, distance between the electrodes is 4.2 mm
Discharge medium Metal _{halide: ScI 3 -NaI-ZnI 2 =} 0.9mg
Xenon Xe: 10 atm outer tube OT: outer diameter 9 mm, inner diameter 7 mm, internal atmosphere; atmospheric pressure (atmosphere)
Input power immediately after lighting: 85W
Make-up current immediately after lighting: 2.8A
Lamp voltage when stable: 42V
Stable lamp power: 35W
Lower hemispheric light flux B ratio when stable: 0.75 A (A is the upper hemispheric light flux)
Embodiment 1 is conceptually shown in FIG.
Embodiment 2
Airtight container 1a: made of quartz glass, sphere length 7 mm, maximum outer diameter 6 mm,
2.4 mm maximum inner diameter, 1.65 mm wall thickness at maximum diameter
Metal _{halide: ScI 3 -NaI-ZnI 2 =} 0.1mg
Lower hemisphere luminous flux B ratio when stable: 0.83 A (A is the upper hemisphere luminous flux)
Embodiment 3
Airtight container 1a: made of quartz glass, sphere length 7 mm, maximum outer diameter 7.5 mm,
2.4 mm maximum inner diameter, 2.4 mm wall thickness at maximum diameter
Lower hemisphere luminous flux B ratio when stable: 0.65 A (A is the upper hemisphere luminous flux)
In the second and third embodiments, description of the same parts as in the first embodiment is omitted.
[0063]
Comparative examples not according to the present invention are as follows.
[0064]
Airtight container 1a: made of quartz glass, sphere length 7 mm, maximum outer diameter 6 mm,
2.4 mm maximum inner diameter, 1.65 mm wall thickness at maximum diameter
Metal _{halide: ScI 3 -NaI-ZnI 2 =} 0.9mg
Lower hemisphere luminous flux B ratio when stable: 0.55 A (A is the upper hemisphere luminous flux)
A comparative example is conceptually shown in FIG.
[0065]
5 and 6 show an embodiment of the vehicle headlight device of the present invention, FIG. 5 is a rear perspective view of the entire device, and FIG. 6 is a circuit diagram of a lighting circuit. In each of the drawings, the vehicle headlight device HL includes a vehicle headlight device body 21, a metal headlamp lamp HPDL for a vehicle headlight, and two lighting circuits OL.
[0066]
The vehicle headlamp apparatus main body 21 includes a front transmission panel 21a, reflectors 21b and 21c, a lamp socket 21d, a mounting portion 21e, and the like. The front lens 21a has a shape conforming to the outer surface of the automobile, and includes necessary optical means such as a prism. The reflectors 21b and 21c are provided for each metal halide lamp HPDL, and are configured to obtain the light distribution characteristics required for each. The lamp socket 21d is connected to the output terminal of the lighting circuit OC and is mounted on the base 21d of the metal halide lamp HPDL. The mounting portion 21e is a means for mounting the vehicle headlamp device main body 21 at a predetermined position of the vehicle.
[0067]
The metal halide lamp HPDL has the structure shown in FIG. The lamp socket 21d is attached to a base and connected. Then, the two metal headlamps HPDL for the vehicle headlight are mounted on the vehicle headlight device main body 21 to form a four-light type vehicle headlight device. The light-emitting portion of each automobile headlamp metal halide lamp HPDL is located substantially at the focal point of the reflectors 21b and 21c of the automobile headlamp apparatus body 21.
[0068]
Each of the two lighting circuits OL has a circuit configuration to be described later, is housed in the metal container 22, and energizes and turns on the metal halide lamp HPDL for a vehicle headlight.
[0069]
As shown in FIG. 6, the lighting circuit OL includes a DC power supply 11, a chopper 12, a control unit 13, a lamp current detecting unit 14, a lamp voltage detecting unit 15, an igniter 16, a metal halide lamp HPDL for a vehicle headlight, a full bridge inverter. 17 for alternating-current lighting of a metal halide lamp HPDL for a vehicle headlight.
[0070]
The DC power supply 11 is a means for supplying DC power to a chopper 12 described later, and a battery or a rectified DC power supply is used. In the case of an automobile, a battery is generally used. However, a rectified DC power supply that rectifies AC may be used. If necessary, an electrolytic capacitor 11a is connected in parallel to perform smoothing.
[0071]
The chopper 12 is a DC-DC conversion circuit that converts a DC voltage into a DC voltage having a required value, and controls a metal halide lamp HPDL for a headlight of an automobile as required through a full-bridge inverter 17 described later. When the DC power supply voltage is low, a boost chopper is used, and when it is high, a step-down chopper is used.
[0072]
The control means 13 controls the chopper 12. For example, immediately after lighting, a lamp current of three times or more of the rated lamp current is supplied to the metal halide lamp HPDL from the chopper 22 via the full-bridge inverter 17, and thereafter the lamp current is gradually reduced as time passes. Control is performed to make the lamp current. The control means 13 generates a constant power control signal by performing feedback input of the respective detection signals corresponding to the lamp current and the lamp voltage as described later, and controls the chopper 22 with the constant power. Further, the control means 13 has a built-in microcomputer in which a temporal control pattern is incorporated in advance, and immediately after lighting, supplies a lamp current of three times or more of the rated lamp current to the metal halide lamp HPDL for a vehicle headlight, The chopper 12 is controlled so as to reduce the lamp current as time passes.
[0073]
The lamp current detecting means 14 is inserted in series with the lamp via the full bridge inverter 17, detects a current corresponding to the lamp current, and controls and inputs the current to the control means 13.
[0074]
The lamp voltage detecting means 15 is similarly connected in parallel with the metal halide lamp HPDL via the full bridge inverter 17, detects a voltage corresponding to the lamp voltage, and performs control input to the control means 23.
[0075]
The igniter 16 is interposed between the full-bridge inverter 17 and the metal headlamp lamp HPDL for a vehicle headlight, and is configured to supply a starting pulse voltage of about 20 kV to the metal halide lamp HPDL for a vehicle headlight at the time of starting. Have been.
[0076]
The full-bridge inverter 17 includes a bridge circuit composed of four MOSFETs Q1, Q2, Q3 and Q4, a gate drive circuit 28b for alternately switching the MOSFETs Q1 and Q3 of the bridge circuit 17a and Q2 and Q4, and a polarity inversion circuit INV. The DC voltage from the chopper 12 is converted into a rectangular wave low-frequency AC voltage by the above-described switching, and is applied to the metal headlamp lamp HPDL for the vehicle headlight. Turn on.
[0077]
Thus, when the metal halide lamp HPDL for a vehicle headlight is turned on by a rectangular wave low-frequency alternating current using the lighting circuit OC, a required luminous flux is generated immediately after lighting. As a result, it is possible to achieve lighting of 25% of the luminous flux with respect to the rating one second after the power is turned on, which is necessary for a vehicle headlamp, and 80% of the luminous flux after 4 seconds.
[0078]
【The invention's effect】
According to claim 1, a discharge vessel provided with a refractory and translucent airtight container having an inner diameter of 1.5 mm or more and a pair of electrodes having a distance between the electrodes of 5 mm or less, a luminescent metal and a metal for forming a lamp voltage And a discharge medium containing xenon at room temperature of 5 atm or more and containing essentially no mercury, a tube wall load of 50 W / cm ² or more at the time of stable lighting, and a lamp power at the time of stable lighting of When the upper and lower hemisphere light beams A and B satisfy the formula 1 below 60 W and in the horizontal lighting state, the upper hemisphere light beam and the lower hemisphere light beam are optimized, and the irradiation center at the time of low beam It is possible to provide a metal halide lamp for a headlight of an automobile in which problems such as coloring of a portion, a difference in color between a high beam and a low beam, and an unclear irradiation pattern are prevented.
[0079]
(Equation 1)
A ≧ B ≧ 0.6 × A
According to the invention of claim 2, a vehicle headlight device main body, the vehicle headlight metal halide lamp according to claim 1 or 2 disposed on the vehicle headlight device main body, and a vehicle headlight 2. A headlight device for an automobile having the effect of claim 1, comprising a lighting circuit in which the maximum input power up to 4 seconds immediately after the lighting of the metal halide lamp is 2 to 4 times the lamp power at the time of stability. Can be provided.
[Brief description of the drawings]
FIG. 1 is a front view of a first embodiment of a metal halide lamp for a vehicle headlight according to the present invention; FIG. 2 is a front view showing an enlarged main part of the discharge vessel; FIG. FIG. 4 is a conceptual enlarged cross-sectional view showing a comparative example not according to the present invention. FIG. 5 is a perspective view showing an embodiment of the automotive headlight device of the present invention. Circuit diagram of circuit [Explanation of reference numerals]
1a: airtight container, 1a1: sealed portion, 1a2: sealed tube, 1b: electrode, 1c: discharge space, 2: sealed metal foil, 3A: external lead wire, 3B: external lead wire, 4: reduced diameter portion , B: Base, HPDL: Metal halide lamp for automotive headlamp, IT: Discharge vessel, OT: Outer tube, T: Insulating tube

Claims (2)

A refractory and translucent airtight container having a discharge space with an inner diameter of 1.5 mm or more formed therein, and a pair of electrodes which are separately sealed at both ends of the discharge space in the airtight container and have a distance between the electrodes of 5 mm or less. A discharge vessel comprising:
A discharge medium containing a luminous metal and a halide of a metal for forming a lamp voltage, and xenon at room temperature of 5 atm or more, which is enclosed in an airtight container and is essentially free of mercury;
The upper hemispherical light flux A and the lower hemispherical light flux B of the discharge vessel in the horizontal lighting state have a tube wall load of 50 W / cm ² or more during stable lighting and a lamp power of 60 W or less during stable lighting. A metal halide lamp for a vehicle headlight, which satisfies condition 1.
(Equation 1)
A ≧ B ≧ 0.6 × A A headlight unit for an automobile;
2. The metal halide lamp for a vehicle headlight according to claim 1, wherein a shaft of the discharge vessel is disposed in the vehicle headlight device main body along an optical axis of the vehicle headlight device main body;
A lighting circuit in which the maximum input power up to 4 seconds immediately after the lighting of the metal halide lamp for a vehicle headlight is 2 to 4 times the lamp power in a stable state;
An automotive headlight device comprising:

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