JP2006073538A - Metal-halide lamp, metal-halide lamp lighting device and automotive head light apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal-halide lamp of which rising of flux of light is quickened, its lighting device and automotive head light apparatus. <P>SOLUTION: The lamp includes a discharge container and a discharge medium to turn on with electric power of not more that 100 W without using mercury. In the discharge container, when a distance between electrode ends is L (mm), a distance between an intersection point of a first imaginary straight line connecting between discharge starting points of the electrodes and a second imaginary straight line extending from an inner surface of a central upper portion in a discharge space perpendicularly to the first imaginary straight line and the inner surface of the central upper portion in the discharge space is Dc/2 (mm), the maximum thickness of an airtight container at the position of 80% of the distance between the electrodes toward the center is t (mm), 0.25 ≤Dc/L≤0.96 and 0.16 ≤t/L≤1.10 are satisfied; and when a distance between each of inner surfaces at both ends of the discharge space and an inflection point of the inner surface shape is p1 (mm) and the projecting length of the electrode is p2 (mm), 0.6 ≤p2/p1 ≤1.7 is satisfied. The discharge medium contains first halide from among a plurality of halides including at least Na, Sc or rare earth metal, second halide from among metal halides hardly emitting light to visible region and noble gas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a metal halide lamp, a metal halide lamp lighting device using the metal halide lamp, and an automotive headlamp device.

  A metal halide lamp in which a rare gas, a halide of a luminescent metal, and mercury are enclosed in an arc tube having a pair of electrodes facing each other is widely used because of its relatively high efficiency and high color rendering. The use of metal halide lamps has also become widespread for automotive headlamps. Mercury lamps are indispensable for metal halide lamps in practical use, including those for automotive headlamps. In addition, the specification of the metal halide lamp for motor vehicle headlamps is known (for example, refer patent document 1). However, about 2 to 15 mg of mercury is indispensable for this metal halide lamp.

  Further, the wall thickness t of the lamp vessel in the middle between the electrodes is 1.5 to 2.5 mm, the inner diameter D of the lamp vessel in the middle between the electrodes is 1 to 3 mm, and the distance d between the tips of the electrodes is 3.5 to 6 mm. The distance l of the electrode protruding into the lamp vessel is 0.5 to 1.5 mm, the gas filling contains a rare gas, mercury and a metal halide, and the enclosed amount A (mg) of mercury is There is known a discharge lamp, that is, a metal halide lamp suitable for an automobile headlamp having a configuration satisfying the above (see Patent Document 2). In this metal halide lamp, it is described that the discharge arc contracts in a horizontal operation state and becomes at least almost linear, and exhibits high efficiency.

0.002 (d + 4 ・ l) ・ D exp 2 <A <0.2 (d + 4 / l) ・ D exp (1/3)
However, now that environmental problems are becoming more serious, it is considered very important in the lighting field to reduce mercury from the lamp, which has a large environmental load, and to eliminate it.

  In order to solve this problem, several proposals have already been made not to use mercury even in metal halide lamps (see, for example, Patent Documents 3, 4, and 5). The inventions described in these patent documents have been made by the present inventors. The former is a configuration in which scandium Sc or a rare earth metal halide and a rare gas are enclosed and lighting control is performed with a pulse current. In the middle, the discharge medium is composed of a metal halide and a rare gas, so that dimming lighting can be performed with less change in color characteristics over a wide input range. The latter has a configuration in which, in addition to the first halide which is the main luminescent material, the second halide which has a high vapor pressure and does not easily emit light is added to improve the electrical characteristics and the like. is there.

Further, in addition to halides of scandium Sc and sodium Na, yttrium is used as a third halide in which the ionization voltage of a single metal is ⁵ to 10 eV and the vapor pressure during operation is 1 × 10 ^−5. A configuration is also known in which blackening due to electrode scattering is prevented by adding Y and indium In (see Patent Document 6). In this prior art, it is described that the metal halide lamp obtained by the invention has a total luminous flux and a chromaticity range for automobile headlamps.

Japanese Patent Laid-Open No. 02-007347 JP 59-111244 A Japanese Patent Laid-Open No. 03-236151 Japanese Patent Laid-Open No. 06-084496 JP 11-238488 A JP-A-11-3007048

  When a metal halide lamp is used as a headlamp, the brightness on the irradiated surface is required to be a predetermined value or more after a predetermined time from turning on the power because of a safety problem. For example, in Japanese automobile lamp industry standard JEL-215, the luminous flux of a single lamp is defined as 25% or more after 1 second and 80% or more after 4 seconds. In a mercury-filled metal halide lamp, approximately 4 seconds later, mercury that tends to evaporate even at low temperatures mainly emits light, and then a light-emitting metal halide starts to emit light. For this reason, the light emission efficiency at the time of 1 second and 4 seconds is less than half that of light emission mainly from a light emitting metal in a general halide. Therefore, the standard value is achieved by increasing the input power immediately after lighting to about twice the steady state. For this reason, in the case of a metal halide lamp enclosing mercury, the light emission color immediately after lighting is due to mercury discharge, so the light characteristics are very bad, and it deviates from the white chromaticity range defined in JEL-215. It takes several tens of seconds to fit within the standard.

  In contrast, in the case of a metal halide lamp that does not contain mercury, the vapor pressure of the halide is much lower than that of mercury, so the luminous flux from the power-on to 4 seconds is negligible, and the emission of mainly rare gases. It becomes. In such a case, the emission efficiency of the rare gas is lower than that of mercury. Therefore, there is a problem that even if the input power is increased by about twice, the above standard value cannot be satisfied. Even if only the configuration in which the second halide is sealed instead of mercury as described in Patent Document 5, the vapor pressure of the second halide immediately after lighting is still lower by one digit or more than the mercury vapor pressure. This is not an essential solution to the above problem.

  The present invention relates to a metal halide lamp suitable for use as an automobile headlamp because a light flux rises quickly even if the discharge start point formed on the surface of the electrode is deviated upward from the axis of the electrode, and a metal halide lamp lighting device using the metal halide lamp. An object is to provide an automotive headlamp device.

  In addition, the present invention also provides a metal halide lamp suitable for an automobile headlamp that is environmentally friendly without essentially using mercury, a metal halide lamp lighting device using the metal halide lamp, and an automobile headlamp device. For other purposes.

  Furthermore, the present invention additionally provides a metal halide lamp suitable for automobile headlamps and a metal halide lamp using the same, by making the rise of the luminous flux faster by making the mutual relationship between the structure of the discharge vessel and the discharge medium appropriate. It is still another object to provide a lighting device and an automotive headlamp device.

  In addition, the present invention also provides a metal halide lamp suitable for use as an automobile headlamp, which accelerates the rise of the luminous flux and prevents the discharge vessel from bulging, a metal halide lamp lighting device using the metal halide lamp, and an automobile headlamp. It is still another object to provide an apparatus.

  The metal halide lamp of the present invention includes a fire-resistant and light-transmitting hermetic container in which a long and narrow discharge space is formed, and a pair of electrodes sealed and opposed to both ends of the discharge space in the hermetic container. The distance between the electrodes is L (mm), a first imaginary straight line connecting between the discharge start points of the pair of electrodes is drawn, and a second perpendicular to the first imaginary straight line is drawn from the inner upper surface of the center of the discharge space. When the imaginary straight line is drawn, the distance between the intersection of the first and second imaginary straight lines and the inner surface at the upper center of the discharge space is Dc / 2 (mm), and the region is 80% closer to the center of the distance between the electrodes Dc / L and t / L satisfy the following formula, and the distance between the inner surface of both ends of the discharge space and the inflection point of the inner surface shape is defined as t (mm). p1 (mm), and the protruding length of the pair of electrodes into the discharge space is p2 (mm A discharge vessel in which p2 / p1 satisfies the following formula; a first halide composed of a plurality of luminescent metal halides including at least sodium Na, scandium Sc, or a rare earth metal, and a vapor pressure during lighting is Second metal halide composed of one or more metal halides that are relatively large and hard to emit light in the visible region as compared to the first halide, and a rare gas, and enclosed in an airtight container And is characterized in that it is lit essentially at a lamp power of 100 W or less and without mercury being enclosed therein.

0.25 ≦ Dc / L ≦ 0.96
0.16 ≦ t / L ≦ 1.10
0.6 ≦ p2 / p1 ≦ 1.7
In the present invention, terms and technical meanings are as follows unless otherwise specified.

<About the discharge vessel>
The discharge vessel includes an airtight vessel and a pair of electrodes.

(About airtight containers)
The hermetic container is fireproof and translucent. “Fire resistance” means sufficiently withstanding the normal operating temperature of the discharge lamp. Therefore, the hermetic container may be made of any material as long as it is a material having fire resistance and visible light in a desired wavelength region generated by discharge can be led to the outside. For example, it can be formed using quartz glass, translucent alumina, ceramics such as YAG, or single crystals thereof. If necessary, it is allowed to form a halogen-resistant or halogenated-resistant transparent coating on the inner surface of the hermetic container or to modify the inner surface of the hermetic container.

  Further, the hermetic container has an elongated discharge space formed therein. As will be described later, the inner diameter of the elongated discharge space is defined by a relative numerical relationship with the interelectrode distance. Further, as will be described later, the thickness of the hermetic container is defined by a relative numerical relationship with the interelectrode distance.

(About electrodes)
The metal halide lamp of the present invention may be configured to be lit by either alternating current or direct current.

  When operating with alternating current, the pair of electrodes have the same structure. Further, in the case of a metal halide lamp for automobile headlamps, it is convenient to make the tip of the electrode larger in diameter than the shaft. That is, the number of times the lamp blinks is very large, and a larger current flows at the time of starting than at the normal time. Accordingly, if the entire electrode is made large in diameter, the constituent material of the hermetic container that is in contact with the electrode shaft Each time is blinking, it tends to crack due to thermal stress. Therefore, by forming a large diameter portion at the tip of the electrode, it is possible to make the electrode respond to blinking, but since the shaft portion is not large in diameter, cracks are unlikely to occur.

  When operating with a direct current, the temperature of the anode generally increases greatly, so forming a large diameter portion at the tip can increase the heat dissipation area and cope with frequent flashing. On the other hand, the cathode does not necessarily have to have a large diameter portion.

  Next, the distance between the electrodes is preferably 6 mm or less in practice. That is, when the distance between the electrodes exceeds 6 mm, the distance from the point light source is increased, and the focal characteristic of the optical system is deteriorated. For example, when used as a light source for automobile headlamps, the brightness of the irradiated surface is lowered. Further, as will be described later, the interelectrode distance has a close correlation with the inner diameter and the wall thickness of the hermetic container.

(Relationship between airtight container distance Dc / 2 and interelectrode distance L)
The distance between the electrodes of the discharge vessel is L (mm), a first imaginary straight line connecting between the discharge start points of the pair of electrodes is drawn, and perpendicular to the first imaginary straight line from the inner surface at the upper center of the discharge space. When the second imaginary straight line is drawn, the distance between the intersection of the first and second imaginary straight lines and the inner surface at the upper center of the discharge space is defined as Dc / 2 (mm). And it is necessary to set Dc / L so as to satisfy the following expression.

0.25 ≦ Dc / L ≦ 0.96
In the above, “electrode discharge start point” means the center of the position of an arc spot generated on the electrode. In so-called horizontal lighting of metal halide lamps, the arc tends to bend upward, so the discharge start point of the electrode is likely to be displaced above the imaginary line connecting the electrodes. Displace to For this reason, the arc approaches the upper part of the inner surface of the discharge space according to the amount of displacement.

  In the present invention, the inner diameter of the discharge space of the discharge vessel is substantially corrected and defined in consideration of the influence of the position of the discharge start point of the electrode. That is, Dc / 2 corresponds to the radius corrected for the displacement from the electrode axis at the discharge start point, and the corrected inner diameter Dc is twice Dc / 2.

  Next, the reason for limiting the above mathematical formula will be described. That is, when Dc / L is within the above range, the central portion of the arc appropriately approaches the inner surface of the discharge vessel, the amount of heat transfer from the arc to the discharge vessel increases, and the expected temperature rise of the discharge vessel Is obtained. The range of Dc / L is generally the above range, but is preferably 0.45 to 0.90.

  On the other hand, when Dc / L is more than 0.96, the increase in the heat transfer amount is too small. On the other hand, if Dc / L is less than 0.25, the temperature rise of the discharge vessel becomes excessive, and the discharge vessel swells or the halide or free halogen reacts with the discharge vessel to cause clouding. Arise.

(Relationship between the thickness t of the airtight container and the distance L between the electrodes)
Let L (mm) be the distance between the electrodes of the discharge vessel, and let t (mm) be the maximum thickness of the discharge space in the 80% region closer to the center. And t / L needs to be set so that the following formula may be satisfied.

0.16 ≦ t / L ≦ 1.10
In the present invention, as described above, the temperature rise of the hermetic vessel is accelerated by bringing the inner surface of the discharge space close to the arc by an appropriate distance. It is a requirement to make it larger within the range. Thereby, the heat received from the arc mainly in the upper part of the discharge vessel can be quickly conducted to other parts such as the side and bottom surfaces of the discharge vessel, and the temperature of these parts can be increased. The range of t / L is generally the above range, but is preferably 0.21 to 0.77. More preferably, it is 0.31-0.57.

  On the other hand, when t / L is less than 0.16, the thickness of the discharge vessel becomes small, and the heat transfer to other parts becomes too slow. On the other hand, if t / L is greater than 1.10, the heat capacity of the discharge vessel becomes too large, and the temperature rise in other parts of the discharge vessel is delayed.

  The reason for defining the 80% region closer to the center of the interelectrode distance L (mm) is as follows. That is, in the present invention, it is intended to accelerate the temperature rise of the hermetic container by bringing the inner surface of the discharge space closer to the arc by an appropriate distance. In the 80% region near the center of the distance L (mm) between the electrodes, the arc can be brought closer to the inner surface of the hermetic container by reducing the inner diameter of the hermetic container. However, the arcs are separated from the inner surface of the hermetic container because they are close to the electrodes in the 10% regions near the pair of electrodes in the distance L between the electrodes. Therefore, in this region, the meaning of defining the inner diameter and the wall thickness is reduced.

(Regarding the relationship between the distance p1 of the inner surface of the airtight container and the protruding length p2 of the electrode)
When the distance between the inner surface of both ends of the discharge space and the inflection point of the inner surface shape is p1 (mm), and the protruding length of the pair of electrodes into the discharge space is p2 (mm), p2 / p1 is expressed by the following formula: It is necessary to be satisfied.

0.6 ≦ p2 / p1 ≦ 1.7
The above formula defines a configuration for specifying the shape of the hermetic container and the range of the protruding length of the electrode to accelerate the rise of the light beam.

  In the above formula, p1 is the distance between the inner surfaces at both ends of the discharge space and the inflection points of the inner surface shape. The distance p1 is determined as follows. That is, at both ends of the discharge space, conical (mortar-shaped) recesses having the base of the electrode shaft as a vertex are formed around the electrodes. In addition, a cylindrical or spindle-shaped body is formed in the middle of the discharge space. The discharge space is formed by a central body portion and a pair of concave portions continuous at both ends thereof.

  Thus, a first imaginary straight line that coincides with a substantially straight part of the recess and a first imaginary straight line that is drawn from the central inner surface of the body portion in parallel to the axis of the discharge vessel. A third imaginary straight line perpendicular to the axis is drawn from the intersection. The distance between the second intersection formed between the third virtual straight line and the axis and the third intersection formed between the first virtual straight line and the axis of the discharge vessel is p1. And

  Next, p2 is the protruding length of the electrode into the discharge space. The distance p2 is determined as follows. That is, the distance between the third intersection point and the electrode tip is defined as p2.

  Thus, if p2 / p1 is less than 0.6, the protruding length of the electrode is small, and if the dimension of the discharge space is constant, the distance between the electrodes becomes large. If the distance between the electrodes is constant, the discharge space is reduced. In this state, the upper part of the electrode becomes an inclined concave part, and the distance between the electrode of this part and the inner wall surface of the discharge space becomes small. This is not possible because a reaction with the airtight container occurs. In addition, when the electrode protrusion length is shortened, the vicinity of the holding portion of the electrode is overheated by the high heat of the arc or the electrode, causing a reaction or swelling, which is also impossible.

  On the other hand, if p2 / p1 exceeds 1.7, the protruding length of the electrode is large, and if the dimension of the discharge space is constant, the distance between the electrodes is small. If the distance between the electrodes is constant, the discharge space becomes large. In this state, the gap between the electrode and the inner wall surface of the discharge space is too large, so that the temperature rise is slow and the rise of the light beam is slow.

  A more preferable range of the present invention is a range satisfying the following formula.

1.0 ≦ p2 / p1 ≦ 1.3
<Discharge medium>
In the present invention, the discharge medium essentially consists of the first and second halides and the rare gas as described above, and essentially does not contain mercury.

(About the first halide)
The first halide is a halide of a plurality of luminescent metals including at least sodium Na, scandium Sc, or a rare earth metal. The sodium Na and scandium Sc are indispensable as light emitting metals that efficiently emit white light. Preferably, in addition to these metals, a rare earth metal, for example, a halide such as dysprosium Dy is included, so that the chromaticity of light emission can be easily adapted to the standard of white light. The first halide is allowed to contain other luminescent metals in addition to the above, if necessary.

(About the second halide)
The second halide is sealed in addition to the luminescent metal halide in the first halide, has a relatively high vapor pressure during lighting, and is less likely to emit light in the visible region than the luminescent metal. Consisting of halides of As the second halide, magnesium Mg, iron Fe, cobalt Co, chromium Cr, zinc Zn, nickel Ni, manganese Mn, aluminum Al, antimony Sb, beryllium Be, rhenium Re, gallium Ga, titanium Ti, zirconium Zr, One or more metal halides selected from the group consisting of hafnium Hf and tin Sn can be used. Among the above groups, one or more metal halides selected from the group of iron Fe, zinc Zn, manganese Mn, aluminum Al and gallium Ga are suitable. Tin Sn emits light in the visible range, but when encapsulated with Na, Na becomes dominant. The addition of the second halide is described in Patent Document 5.

  The aspect in which the second halide is added has a remarkable effect mainly in improving the electrical characteristics of the metal halide lamp. However, there are some points that need to be noted in implementation, and will be described in detail below. That is, firstly, there are cases where the life characteristics are difficult, and secondly, when a metal halide lamp is incorporated in an automobile headlamp, the rise in brightness at the irradiation center is compared to when the lamp is a single lamp. May be inferior.

  The problem in the case of encapsulating the second halide described above can be avoided by optimizing the high-pressure discharge lamp.

  Next, the halogen constituting the halide will be described. That is, iodine is the most suitable as the halogen, and the reactivity increases in the order of bromine, chlorine, and fluorine. In short, any of the above may be used. Further, different halogen compounds such as iodide and bromide can be used in combination.

(About rare gas)
The rare gas acts as a starter gas and a buffer gas, and is generally not particularly limited as long as it does not permeate the hermetic container, but neon tends to permeate quartz glass, so that the hermetic container is formed of quartz glass. For this, argon, krypton or xenon is recommended. When light emission immediately after starting depends on a rare gas, xenon has the highest luminous efficiency, and therefore, xenon is the most suitable rare gas. In addition, when the rare gas filling pressure is increased, the lamp voltage of the metal halide lamp is increased, and the lamp input can be increased with respect to the same lamp current to improve the luminous flux rising characteristics. Good light beam rise characteristics are convenient for any purpose of use, but are extremely important particularly in automotive headlamp devices and liquid crystal projectors.

(About mercury)
In the present invention, “essentially mercury is not enclosed” means that not only mercury is not enclosed, but there is less than 2 mg, preferably 1.0 mg or less of mercury per 1 cc of internal volume of the airtight container. It means to allow that. However, it is environmentally desirable not to enclose mercury at all. In the case where the electrical characteristics of the discharge lamp are maintained by mercury vapor as in the conventional case, the small short arc type is sealed because 20-40 mg per cc of the internal volume of the hermetic container, and in some cases 50 mg or more is sealed. In other words, it can be said that the present invention has a substantially small amount of mercury.

<About lamp power>
In the present invention, the lamp power is the power that is input to the metal halide lamp when stable, and is 100 W or less. This means a small metal halide lamp. In this type of conventional metal halide lamp, there is a great demand for quick rise of the luminous flux.

<About the outer tube>
An outer tube that houses the discharge vessel may be provided. In that case, the inside of the outer tube can be evacuated to a vacuum, or an inert gas can be enclosed. However, if necessary, the outer tube may be communicated with the outside air without being sealed.

<About the effect | action of this invention>
In the present invention, the displacement of the discharge start point from the electrode axis is corrected to regulate the inner diameter of the discharge space. Therefore, when the electrode diameter is large or the large diameter portion is formed at the tip of the electrode, Even when the starting point is deviated upward from the axis of the electrode, the inner diameter of the discharge space is set appropriately in accordance with the starting point of the discharge, so that the luminous flux rises quickly and the discharge vessel is caused by excessive temperature rise. No blistering occurs.

  Further, in addition to the above, since the distance p1 of the inner surface of the hermetic container and the protruding length p2 of the electrode have a predetermined numerical relationship, the discharge container does not swell and the reaction between the halide and the hermetic container does not occur. .

  Next, the general actions of the present invention are listed.

  1. Improvement of the heat transfer characteristics of the discharge vessel speeds up the luminous flux rise.

  In the present invention, mercury having a large environmental load is essentially not used, and the distance L between the electrodes of the discharge vessel, the corrected inner diameter Dc of the discharge space, and the wall thickness t have a predetermined numerical relationship. As a result, since the arc approaches the upper inner surface of the discharge vessel, the heat of the arc is favorably transferred mainly to the upper portion of the central portion of the discharge vessel. Further, the heat conducted to the upper part of the discharge vessel is conducted through the tube wall portion of the discharge vessel, and is transmitted from the side surface to the bottom surface to quickly heat and heat those portions.

  As a result, the halide that has adhered and solidified mainly on the bottom and side surfaces of the inner surface of the discharge vessel is quickly heated to increase its temperature, liquefy, and further evaporate. The rise characteristic is remarkably improved. For this reason, it can comprise so that the specification prescribed | regulated as a headlamp for motor vehicles may be satisfied.

  Therefore, the present invention is suitable as a metal halide lamp for an automotive headlamp, but is not limited thereto.

  2. In the present invention, the rise of the luminous flux immediately after turning on the power is better than the metal halide lamp enclosing mercury.

  That is, even if the same discharge vessel is provided, when enclosing mercury, light emission immediately after start-up is mainly mercury, and after start-up, mercury evaporates as the temperature of the discharge vessel rises. The luminous flux increases in proportion to the pressure. Mercury has a luminous efficiency that is about half that of the metals that make up halides. Therefore, in order to compensate for this, headlamps for automobiles generally have a lamp that is about twice as long as 4 seconds or more after starting. The lighting device is configured to be controllable so that power is supplied. For example, in a metal halide lamp used for an automotive headlamp, the luminous flux after 1 second is about 25% of the stable time and is dark within 1 second, particularly immediately after starting. After that, it reaches 100% in about 5 seconds. For this reason, the rise of the luminous flux is slower than that of the halogen light bulb, which is why a faster rise of the luminous flux is desired for safety. Since mercury evaporates rapidly, if the input power is adjusted so as to increase the luminous flux after 1 second from turning on the power, the subsequent rise overshoots and is not suitable for practical use.

  On the other hand, in the present invention, the rare gas mainly emits light immediately after starting, and part of the light emitting metal constituting the halide also emits light. Thereafter, the light emission ratio of the luminescent metal gradually increases, and the luminous flux increases in proportion to this, resulting in stable lighting. By adjusting the input power at the time of starting, a light flux of 25% or more can be obtained after 1 second, which is safer than the case of mercury encapsulation. In particular, the rate of increase in luminous flux per hour from just after startup to 0.3 seconds is very high, more than several times that of mercury-filled metal halide lamps. The light flux immediately after the start is maintained for a few seconds thereafter, and then the light emission of the light emitting metal shifts to the main light emission. For this reason, it is possible to obtain a metal halide lamp that becomes bright immediately after the power is turned on and is close to that of a halogen bulb. Therefore, by appropriately adjusting the input power at the time of start-up in practical use, the luminous flux rise after 1 second can be made equivalent to that of a halogen light bulb with the same power consumption. In a metal halide lamp enclosing mercury, it is extremely difficult to obtain a flat luminous flux rise as described above. That is, since mercury evaporates rapidly, if the input power is adjusted so as to increase the rising rate of luminous flux after 1 second, the subsequent rising will overshoot and become unpractical. .

  3. The risk of explosion of the discharge vessel is less than when mercury is enclosed.

  That is, a commercially available 35 W metal halide lamp used for an automotive headlamp encloses about 1 mg of mercury, a luminescent metal halide and xenon at 4 to 6 atm at room temperature. And, since the mercury is completely evaporated, the pressure during lighting is determined by the mercury amount and the xenon sealing pressure. Note that the vapor pressure of the halide is two orders of magnitude lower than the above, so there is no need to consider it.

  On the other hand, in the present invention, the pressure during lighting is determined by the rare gas. Even if the enclosure pressure of the rare gas is 6 to 10 atm, which is higher than that when mercury is enclosed, it is clearly lower than that when mercury is enclosed. For this reason, if the pressure resistance of the discharge vessel is equivalent, the risk of rupture is lower in the present invention, and the reliability is increased accordingly.

  4). Restarting is easier than with mercury.

  Metal halide lamps used for automotive headlamps need to be restarted in order to cope with the frequent flashing required for their properties and quick rise of luminous flux. In the present invention, the pressure in the discharge vessel is Since it is low, restarting is easier.

  5. Less change in light color than when mercury is encapsulated.

  In the present invention, mercury is essentially not enclosed, so that the change in light color with respect to input fluctuation is small. This is because, in the case of mercury encapsulation, light emission from the lamp consists of light emission of a light emitting metal and mercury. Even if the temperature of the discharge vessel changes, the vapor pressure of mercury is very high, so the lighting pressure is almost unchanged, but the vapor pressure of metal halide is much lower than that of mercury, so the vapor pressure depends on the temperature of the discharge vessel. Changes sensitively. For this reason, when the lamp input changes, the light emission amount of mercury does not change, but the light emission of the metal halide light-emitting metal greatly changes, and the light color changes significantly.

  On the other hand, in the present invention, since the luminescent metal emits most of the light, the light color hardly changes. Therefore, the light control characteristics are good, and the variation in light color at the same lamp power is small. In metal halide lamps that contain mercury, color variation due to differences in the individual color temperature due to variations in the shape and dimensions of the discharge vessel, or due to the rise in the coldest part temperature due to blackening of the discharge vessel over the long life, etc. Although a change in color temperature is a big problem, this point is improved in the present invention.

    A metal halide lamp lighting device according to the present invention includes the metal halide lamp according to claim 1 or 2; and a lighting circuit for lighting the metal halide lamp.

  Since the metal halide lamp lighting device of the present invention includes the metal halide lamp of the present invention as a light source, the rise of the luminous flux is quick and safe.

    The automotive headlamp device of the present invention includes a vehicle headlamp device main body; the axis of the discharge vessel is disposed in the vehicle headlamp device main body along the optical axis of the vehicle headlamp device main body. And a metal halide lamp according to claim 1 or 2.

  Since the automotive headlamp apparatus of the present invention includes the metal halide lamp of the present invention as a light source, the rise of the luminous flux is quick and safe. The “automobile headlamp device main body” means all remaining portions of the vehicle headlamp device excluding the metal halide lamp.

    According to the present invention, even if the discharge start point formed on the surface of the electrode deviates upward from the axis of the electrode, the light flux rises quickly and is suitable for an automobile headlamp, and essentially does not enclose mercury. It is possible to provide a Tal halide lamp that is environmentally friendly, a metal halide lamp lighting device using the same, and an automotive headlamp device.

  In addition, by forming a large diameter portion that is larger in diameter than the shaft portion at the tip of the pair of electrodes, in a metal halide lamp that operates with an alternating current for an automobile headlamp, cracks are less likely to occur even if the number of blinks increases.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

    1 and 2 show a first embodiment for carrying out the metal halide lamp of the present invention, FIG. 1 is a front sectional view, and FIG. 2 is a schematic view of the inside of a discharge vessel for explaining the dimensions of each part. It is a schematic diagram shown.

  In each figure, 1 is a discharge vessel, 2 is a sealing metal foil, 3 is an external lead wire, and H is an attached halide.

  The discharge vessel 1 includes an airtight vessel 1a made of quartz glass and a pair of electrodes 1b. The hermetic container 1a is formed in a hollow spindle shape, and is integrally provided with a pair of elongated sealing portions 1a1 at both ends thereof, and an elongated discharge space 1c is formed therein. The electrode 1b is made of tungsten and includes an electrode shaft 1b1 and a large-diameter portion 1b2. The base end of the electrode shaft 1b1 is supported at a predetermined position by being embedded in the sealing portion 1a1. The large diameter portion 1b2 is formed integrally with the electrode shaft 1b1. Further, the base portion of the electrode shaft 1b1 is welded to one end of the sealing metal foil 2 in the sealing portion 1a1.

  The sealing metal foil 2 is made of molybdenum foil, and is hermetically sealed in the sealing portion 1a1 of the hermetic container 1a, and the external lead wire 3 is welded to the other end.

  In the hermetic vessel 1a, a rare gas, a first halide, and a second halide are sealed as a discharge medium. The first halide is composed of sodium Na, scandium Sc, and a rare earth metal halide. The second halide is composed of one or a plurality of halides of metals that do not easily emit light in the visible region as compared to the first halide.

  The present embodiment is characterized in that the shape of the discharge space 1c is determined in consideration of the case where the discharge start point 4a formed on the surface of the electrode 1b deviates from the axis of the electrode 1b.

  That is, the arc 4 formed in the discharge space 1c is formed between the discharge start points 4a and 4a generated on the pair of electrodes 1b and 1b. When the metal halide lamp is lit horizontally, the arc 4 is curved upward, so that the discharge start point 4a is biased to the upper part of the electrode 1b. Therefore, the entire arc 4 is displaced to the upper side of the discharge space 1c. This phenomenon becomes more prominent as the large diameter portion 1b2 of the electrode 1b is increased to some extent. The vertical distance between the discharge start point 4a and the central upper inner surface of the discharge space 1c is Dc / 2, and twice that is Dc. The ratio Dc / L between the inner diameter Dc and the interelectrode distance L is set in the range of 0.25 to 0.96. It goes without saying that the position of the discharge start point 4a is based on the center of the discharge in the vertical direction at the discharge start point.

  Moreover, about the wall thickness t of the airtight container 1a, t / L is set to 0.16 to 1.10. Note that the inner diameter Dc and the wall thickness t are both the maximum values at 80% of the distance L between the electrodes.

    3 and 4 show a second embodiment for carrying out the metal halide lamp of the present invention, FIG. 3 is a front sectional view, and FIG. 4 schematically shows the inside of the discharge vessel in order to explain the dimensions of each part. It is a schematic diagram.

  In the present embodiment, the distance p1 and the protruding length p2 of the electrode 1b are set so as to satisfy the following expression.

0.6 ≦ p2 / p1 ≦ 1.7
That is, the inner surface of the discharge space 1c of the hermetic vessel 1a is formed with mortar-shaped recesses 1c1 and 1c1 at both ends thereof, and the body 1c2 located between them has a spindle shape. And as shown in FIG. 4, the inflection point 1c3 shall be formed in the boundary of the mortar-shaped recessed part 1c1 and the spindle-shaped trunk | drum 1c2. The inflection point 1c3 includes a first imaginary straight line l2 coinciding with a substantially linear portion of the recess 1c1, and a second imaginary straight line drawn parallel to the axis l3 of the discharge vessel 1 from the central inner surface of the body 1c2. This is the intersection point P1 formed with l4. An intersection P2 formed between the first imaginary straight line 12 and the axis 13 indicates the inner surface of the end of the discharge space 1c. Therefore, the distance p1 is a distance between the intersections P1 and P2 projected on the axis L3.

  On the other hand, the protruding length p2 of the electrode 1b is a distance between the intersection P1 and the tip of the electrode 1b. The lamp power is 100 W or less.

The shape of the discharge vessel is the same as in FIG.
Discharge vessel: outer diameter of central portion 6.5 mm, maximum inner diameter 4.5 mm, distance between electrodes 4.2 mm,
Electrode shaft diameter 0.4mm, length 7mm, diameter of large diameter 0.6mm,
p2 / p1 = 1.0
Discharge medium: 1st halide-ScI ₃ 0.5 mg, NaI 3.5 mg,
Second halide-ZnI ₂ 0.6 mg, noble gas Xe 5 atm

The shape of the discharge vessel is the same as in FIG.
Discharge vessel: outer diameter of central portion 6.5 mm, maximum inner diameter 3.0 mm, distance between electrodes 4.2 mm,
Electrode shaft diameter 0.4mm, length 7mm, diameter of large diameter 0.6mm,
p2 / p1 = 1.3
Discharge medium: 1st halide-ScI ₃ 0.5 mg, NaI 3.5 mg,
Second halide-ZnI ₂ 0.6 mg, noble gas Xe 5 atm

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

  In the present embodiment, a metal halide lamp similar to that shown in FIG. 3 is further mounted on the automotive headlamp device.

  5 is an outer tube, 6 is a base, and 7 is an insulating tube.

  The outer tube 5 has a UV-cutting performance, and houses a metal halide lamp 10 having a structure similar to that shown in FIG. 3 and is fixed to the sealing portion 1a1 at both ends. There is no communication with the outside air. One sealing portion 1 a 1 is planted in the base 6. The external lead wire 3 led out from the other end extends in parallel with the outer tube 5 and is introduced into the base 6 and connected to a terminal (not shown).

  The insulating tube 7 covers the external lead wire 3.

    FIG. 6 is a perspective view showing an embodiment of the automotive headlamp device of the present invention.

  In the figure, 11 is a reflecting mirror and 12 is a front cover.

  The reflecting mirror 11 is formed into a deformed paraboloid by molding plastics, and is configured to attach and detach a metal halide lamp (not shown) shown in FIG. 16 from the back of the top.

  The front cover 12 is integrally formed with prisms or lenses by molding transparent plastics, and is airtightly attached to the front opening of the reflecting mirror 11.

    FIG. 7 is a circuit diagram of a first embodiment for carrying out the metal halide lamp lighting device of the present invention.

  In the present embodiment, a metal halide lamp is configured to be lit by direct current.

  In the figure, 21 is a DC power source, 22 is a chopper, 23 is a control means, 24 is a lamp current detection means, 25 is a lamp voltage detection means, 26 is a starting means, and 27 is a metal halide lamp.

  As the DC power source 21, a battery or a rectified DC power source is used. In the case of an automobile, a battery is generally used. However, it may be a rectified DC power source that rectifies AC. If necessary, the electrolytic capacitor 21a is connected in parallel to perform smoothing.

  The chopper 22 converts the DC voltage into a voltage having a required value and controls the metal halide lamp 27 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 23 controls the chopper 72. For example, immediately after the lamp is turned on, a lamp current more than three times the rated lamp current is supplied from the chopper 22 to the metal halide lamp 27. Thereafter, the lamp current is gradually reduced as time passes, and control is performed so that the rated lamp current is eventually achieved. . In addition, the control means 23 generates a constant power control signal when the detection signal of the lamp current and the lamp voltage is fed back and controls the chopper 22 with constant power. Further, the control means 23 incorporates a microcomputer in which a temporal control pattern is incorporated in advance, and immediately after the lamp is turned on, a lamp current more than three times the rated lamp current is caused to flow through the metal halide lamp 27. The chopper 22 is configured to control the current.

  The lamp current detection means 24 is inserted in series with the lamp, detects the lamp current, and inputs the control input to the control means 23.

  The lamp voltage detection means 25 is connected in parallel with the lamp, detects the lamp voltage, and inputs the control input to the control means 23.

  The starting means 26 is configured to supply a pulse voltage of 20 kV to the metal halide lamp 27 at the time of starting.

  Then, when the metal halide lamp is lit by direct current using the metal halide lamp lighting device, a required light flux is generated immediately after lighting. As a result, it is possible to realize lighting with a luminous flux of 25% and a luminous flux of 80% after 4 seconds 1 second after turning on the power necessary as a vehicle headlamp.

  In addition, since a DC-AC conversion circuit is not required, the cost can be reduced by about 30% compared to AC lighting. Further, the weight can be reduced by 15%. Along with this, the lighting circuit becomes inexpensive.

    FIG. 8 is a circuit diagram of a second embodiment for implementing the metal halide lamp lighting device of the present invention.

  The same parts as those in FIG. In this embodiment, the metal halide discharge lamp is configured to be lit with alternating current.

  Reference numeral 28 denotes AC conversion means. The AC conversion means 28 is composed of a full bridge inverter. That is, a pair of series circuits of a pair of switching means 28a, 28a are connected in parallel between the output ends of the chopper 22 to constitute a bridge circuit, and the oscillation output of the oscillator 28b is switched in the diagonal direction of the four switching means 28a. By alternately supplying to the means, high-frequency alternating current is generated between the output ends of the bridge circuit.

  Thus, the metal halide lamp 27 is turned on by high frequency alternating current.

  Also in this example, the same control as in FIG. 7 is performed.

Front sectional drawing of the 1st form for carrying out the metal halide lamp of the present invention Similarly, a schematic diagram schematically showing the inside of the discharge vessel in order to explain the dimensions of each part Front sectional view of a second embodiment for carrying out the metal halide lamp of the present invention Similarly, a schematic diagram schematically showing the inside of the discharge vessel in order to explain the dimensions of each part The front view of the 3rd form for carrying out the metal halide lamp of the present invention The perspective view of one form for carrying out the headlight device for cars of the present invention The circuit diagram of the 1st form for carrying out the metal halide lamp lighting device of the present invention The circuit diagram of the 2nd form for carrying out the metal halide lamp lighting device of the present invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Discharge container, 1a ... Airtight container, 1a1 ... Sealing part, 1b ... Electrode, 2 ... Electrode, 3 ... Sealing metal foil

Claims (4)

A fire-resistant and translucent airtight container in which a long and narrow discharge space is formed, and a pair of electrodes sealed oppositely at both ends of the discharge space in the airtight container, the distance between the electrode ends being L (mm) When drawing a first imaginary straight line connecting between the discharge start points of the pair of electrodes and drawing a second imaginary straight line perpendicular to the first imaginary straight line from the inner surface at the upper center of the discharge space, The distance between the intersection of the first and second imaginary straight lines and the inner surface of the upper center of the discharge space is Dc / 2 (mm), and the maximum thickness of the hermetic container in the region of 80% closer to the center of the distance between the electrodes Is t (mm), Dc / L and t / L satisfy the following expressions, and the distance between the inner surface of both ends of the discharge space and the inflection point of the inner surface shape is defined as p1 (mm). When the projecting length of the electrode to the discharge space is p2 (mm), p2 / p1 is expressed by the following equation: And the discharge vessel to the foot;
A first halide composed of halides of a plurality of kinds of luminescent metals including at least sodium Na, scandium Sc, or rare earth metals, which has a relatively large vapor pressure during lighting and is compared with the luminescent metal of the first halide. A discharge medium containing a second halide composed of one or a plurality of halides of a metal that hardly emits light in the visible range, and a rare gas, and enclosed in an airtight container;
The metal halide lamp is characterized in that it is essentially sealed with mercury and is lit at a lamp power of 100 W or less.
0.25 ≦ Dc / L ≦ 0.96
0.16 ≦ t / L ≦ 1.10
0.6 ≦ p2 / p1 ≦ 1.7   The metal halide lamp according to claim 1, wherein the pair of electrodes has a large diameter portion formed larger in diameter than the shaft portion at a tip thereof. A metal halide lamp according to claim 1 or 2;
A lighting circuit for lighting a metal halide lamp;
A metal halide lamp lighting device comprising: An automotive headlamp body;
The metal halide lamp according to claim 1 or 2, wherein an axis of the discharge vessel is disposed in the automobile headlamp apparatus body along the optical axis of the automobile headlamp apparatus body;
A vehicle headlamp device characterized by comprising:

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