JP4260493B2 - High pressure discharge lamp and lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-pressure discharge lamp having an improved electrode welding structure and a lighting device using the same.
[0002]
[Prior art]
The high-pressure discharge lamp has a pair of electrodes sealed in a discharge space formed inside a fireproof and translucent airtight container, and a discharge medium is sealed inside. The pair of electrodes is formed by integrally forming a pair of elongated sealing portions at both ends of the hermetic container, and by connecting the base ends thereof to a sealing metal foil embedded hermetically inside the sealing portion by welding, and sealing the middle portion. In general, the structure is such that the electrode main portion at the tip is exposed to the discharge space by being loosely supported by the stopper and projecting into the discharge space.
[0003]
In the high-pressure discharge lamp, the quality of welding between the electrode and the sealing metal foil greatly affects the life reliability of the sealed portion. In a lamp, resistance welding is generally used for welding the electrode and the sealing metal foil. In this case, in order to stabilize welding, a brazing material having a low melting point such as platinum is generally sandwiched between the electrode and the sealing metal foil and welded, and the most stable welding is obtained.
[0004]
However, the welded structure as described above has a high degree of difficulty in automated design in terms of mass production, and is disadvantageous in terms of equipment cost and manufacturing yield. In resistance welding, the weldability varies greatly depending on the surface condition of the pair of welding electrodes that supply current, and the surface of the welding electrode tends to become rough or dirty during manufacturing, which tends to deteriorate the welding condition. is there. Therefore, resistance welding is disadvantageous in terms of the above for mass production. Therefore, laser welding has attracted attention.
[0005]
On the other hand, high-pressure discharge lamps having an internal volume of 0.1 cc or less are used in metal halide lamps for automobile headlamps and spot lighting. Such a metal halide lamp generally has a configuration in which a rare gas, a luminescent metal halide and mercury are enclosed in an arc tube having a pair of electrodes facing each other, and is relatively high in efficiency and high color rendering. Because it is widely used. 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, in the specification of a metal halide lamp for an automobile headlamp, it is indispensable to enclose about 2 to 15 mg of mercury (see, for example, Patent Document 1).
[0006]
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, some proposals for not using mercury have already been made in metal halide lamps (see, for example, Patent Document 2). In Patent Document 2, instead of mercury, ZnI ₂ A substance having a high vapor pressure such as a halide of a luminescent substance, for example, ScI ₃ By enclosing in addition to -NaI, the same electrical characteristics and light emission characteristics as a mercury-containing lamp are obtained.
[0007]
By the way, the electrode used for the high-pressure discharge lamp is generally made of tungsten or an alloy mainly composed of tungsten, and the electrode material is drawn and elongated using a die. When the electrode material is drawn with a die, a large number of stripes called die marks are formed over the entire peripheral surface. It is known that the electrode surface is smoothed by electropolishing (see, for example, Patent Document 3), but impurities such as carbon remaining on the electrode surface and surface irregularities are managed to scatter and discharge the electrode material. It is intended to improve the flickering of the film, and is not related to welding with the sealing metal foil.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 2-7347
[Patent Document 2]
JP 11-238488 A
[Patent Document 3]
JP 2000-10037 A
[Problems to be solved by the invention]
When welding an electrode to a sealing metal foil by laser welding, there is a tendency to fail unless the adhesion between the sealing metal foil and the electrode is high. For example, there is a hole in the sealing metal foil, or only the temperature on the sealing metal foil side of the welded part is abnormally increased, resulting in a coarse crystal size of the sealing metal foil and a decrease in mechanical strength. In this case, heat is not sufficiently transmitted to the electrode side, resulting in a welding area that is too small. For this reason, a technique is employed in which laser welding is performed in a state where the sealing metal foil and the electrode are mechanically pressed and in close contact with each other.
[0009]
However, it has been found that even if they are pressed mechanically and brought into contact with each other, there is a dice mark, so that it cannot be sufficiently adhered to a required level microscopically. For this reason, it is difficult to obtain optimum electrode welding conditions, and it is not only possible to improve the yield during manufacturing but not to reduce the cost, and there is also a problem in ensuring reliability.
[0010]
In the present invention, when laser welding the sealing metal foil and the electrode, the two are sufficiently brought into close contact with each other so that optimum welding conditions can be easily obtained, the manufacturing yield is improved, the cost is reduced, and the reliability of welding is improved. It is an object of the present invention to provide a high-pressure discharge lamp capable of ensuring high performance and a lighting device using the same.
[0011]
Another object of the present invention is to provide a high-pressure discharge lamp having an electrode weld suitable for a small high-pressure discharge lamp having an internal volume of 0.1 cc or less, and an illumination device using the same. .
[0012]
[Means for achieving the object]
A high-pressure discharge lamp according to a first aspect of the present invention is a fire-resistant and light-transmitting hermetic container having an enclosure part in which a discharge space is formed and a pair of sealing parts extending from both ends of the enclosure part; A pair of sealing metal foils hermetically embedded in a pair of sealing portions of the container; After drawing with a die, Dice marks on the circumference 70% or more A pair of refractory metal rods that have been removed, the base end of which is laser welded to the sealing metal foil, and the tip of the pair faces the discharge space of the hermetic vessel so as to face the discharge space of the airtight container. An electrode; and a discharge medium sealed in the discharge space of the hermetic vessel.
[0013]
In the present invention and each of the following inventions, the definitions and technical meanings of terms are as follows unless otherwise specified.
[0014]
<Regarding the Airtight Container> The airtight container is fireproof and translucent, and includes an enclosing portion and a pair of sealing portions. “Fire resistance” means sufficiently withstanding 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 in a desired wavelength region generated by discharge to the outside. Is formed using quartz glass or the like. 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.
[0015]
Further, the surrounding portion is formed with a discharge space having an appropriate shape therein, for example, an elongated discharge space preferably for an automobile headlamp having an internal volume of 0.1 cc or less. In addition, as an elongate discharge space, a discharge space can be made into a column shape, for example. As a result, the arc tends to bend upward in the horizontal lighting, and thus approaches the upper inner surface of the discharge vessel, so that the temperature rise at the top of the discharge vessel is accelerated.
[0016]
Furthermore, the surrounding portion can have a relatively large thickness. 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 is improved and the temperature rise of the discharge medium adhering to the lower part of the discharge space and the inner side surface of the discharge vessel is accelerated, so that the rise of the luminous flux is accelerated.
[0017]
The pair of sealing portions are means for sealing the surrounding portion, sealing the electrode, and contributing to airtight introduction of current from the lighting circuit to the electrode, and extend integrally from both ends of the surrounding portion. is doing. And in order to seal an electrode and to introduce | transduce an electric current from a lighting circuit to an electrode airtightly, the below-mentioned sealing metal foil is embed | buried airtightly.
[0018]
<About a pair of sealing metal foil> A pair of sealing metal foil is embedded in the inside of the sealing part, and the current conduction while cooperating to keep the inside of the enclosure part of the hermetic container airtight. It is a means for functioning as a conductor, and when the airtight container is made of quartz glass, molybdenum is optimal as a material. Molybdenum oxidizes at about 350 ° C., so it is buried in a position where the temperature is lower than this.
[0019]
Although the method for embedding the sealing metal foil in the sealing portion is not particularly limited, for example, a reduced pressure sealing method, a pinch sealing method, or the like can be employed. In the case of a high-pressure discharge lamp for an automobile headlamp or the like that has a small internal volume of 0.1 cc or less and in which a rare gas such as xenon is sealed at 5 atmospheres or more at room temperature, the former is preferable.
[0020]
<About a pair of electrodes> A pair of electrodes are separated and opposed to the inside of both ends of an airtight container. In the case of a high-pressure discharge lamp for a small automotive headlamp having an internal volume of the discharge space of 0.1 cc or less, the distance between the electrodes is set to 5 mm or less.
[0021]
The pair of electrodes is made of a rod-shaped body made of a refractory metal such as tungsten or a tungsten-rhenium alloy. And the rod-shaped body After drawing with a die, At least in the vicinity of the laser weld, That Dice marks on the circumference 70% or more It has been removed. Of the electrode body Dice mark The inventor has found that good laser welding can be obtained if 70% or more is removed. On the contrary, Circumferential If the removal of the die marks is less than 70%, good laser welding cannot be obtained. Dice marks can be removed by one or a combination of several types, such as electropolishing by applying an electric field and electrochemical polishing, chemical polishing by etching with acid or alkali, and mechanical polishing by mechanical polishing. Can do. The die mark is formed when the wire passes through the die during drawing, and consists of a specific line whose cross section is geometrically continuous in the longitudinal direction, and can be easily observed by observing the cut surface. Can be determined. The dice mark is a photograph of a long side of about 120 mm obtained by photographing a cross section of the electrode at the welded portion of the electrode with the sealing metal foil with an electron microscope, for example, SEM at a magnification of 50 to 200 times, or an area corresponding to this photograph. Observe on the monitor screen and measure the length of the outer circumference of the remaining electrode, excluding the welded portion, of the outer circumference near the welded portion, without the dice mark consisting of geometric irregularities, Calculate the rate. If the above observation is performed on a plurality of cross sections per welded portion and the above conditions are satisfied in one or more cross sections, the requirements of the present invention are satisfied. In addition, when the geometrical unevenness observed as described above is a dice mark, the geometrical unevenness is observed in the electrode axis direction when the side surface of the electrode in the same place is observed in the same manner as described above. Recognized as continuous groove marks.
[0022]
Further, the electrode has a base end of the rod-like body laser welded to the sealing metal foil, the middle is loosely supported by the sealing portion of the hermetic container, and the tip is opposed to both ends of the discharge space so as to face the discharge space of the hermetic container. It is arranged to be opposed to each other.
[0023]
Furthermore, the electrode may be configured to operate with 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 an automobile headlamp, if necessary, the vicinity of the tip of the electrode can be made 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. Thus, by forming a large diameter portion in the vicinity of the tip of the electrode, the electrode can be made to flash, but since the shaft portion is not large in diameter, cracks are less likely to occur. When operating with direct current, the temperature of the anode generally increases greatly, so if a large diameter portion is formed in the vicinity of the tip, the heat radiation area can be increased and frequent flashing can be accommodated. On the other hand, the cathode does not necessarily have to have a large diameter portion.
[0024]
<Discharge Medium> In the present invention, the discharge medium generally may be a metal vapor or gas as the luminescent material. A single luminescent metal, such as mercury, or a luminescent metal halide can be encapsulated as a metal vapor source for the luminescent metal. In addition to the luminescent metal, mercury or a metal halide having a relatively high vapor pressure can be enclosed as a lamp voltage forming substance. Further, a rare gas can be used as the starting gas.
[0025]
Next, a discharge medium of a metal halide lamp for automobile headlamps, which is a preferred embodiment of the high-pressure discharge lamp of the present invention, will be described. The discharge medium in this embodiment contains a metal halide and xenon and is essentially free of mercury.
[0026]
The metal halide includes a light emitting metal halide and a lamp voltage forming metal halide.
[0027]
The halide of the luminescent metal is not particularly limited, but is preferably a halide mainly composed of sodium Na and scandium Sc. If desired, halides such as indium In and rare earth metals can be added. Note that indium contributes to both the luminescent material and the lamp voltage formation. The light emission of indium In also serves to adjust the chromaticity of light emission of the metal halide lamp.
[0028]
The lamp voltage forming metal halide is a metal having a relatively high vapor pressure and effectively contributing to forming the lamp voltage, such as zinc Zn, magnesium Mg, cobalt Co, chromium Cr, manganese Mn, antimony Sb, One or a plurality of halides selected from the group of rhenium Re, gallium Ga, tin Sn, iron Fe, aluminum Al, titanium Ti, zirconium Zr, and hafnium Hf can be used. The lamp voltage can be increased to a required range by selectively enclosing an appropriate amount of these metal halides. As a result, the electrical 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. It is optimal to use zinc Zn halide. Zinc Zn is a substance that has a relatively high vapor pressure, is chemically safe, is inexpensive, and can be easily obtained on an industrial scale. Moreover, the light emission of zinc Zn can also contribute to the adjustment of the light emission chromaticity of the metal halide lamp.
[0029]
As the halogen constituting the halide, iodine is most suitable among the halogens in terms of reactivity, and at least the main light emitting metal is mainly encapsulated as iodide. However, if necessary, different halogen compounds such as iodide and bromide can be used in combination.
[0030]
Xenon is sealed at a pressure of 5 atm or more at room temperature. Further, xenon acts as a starting gas and a buffer gas, and also acts as a luminescent substance when the vapor pressure of the luminescent metal halide is not high immediately after lighting by being sealed at the above pressure. Argon or krypton can be added as desired. The enclosed pressure of xenon is preferably 8 to 15 atmospheres. As a result, the lamp voltage of the metal halide lamp is increased, the lamp input can be increased for the same lamp current, and the luminous flux rising characteristics can be improved. A good luminous flux rise characteristic is convenient for any purpose of use.
[0031]
In this embodiment, “essentially free of mercury” not only does not contain mercury at all, but also contains less than 2 mg, preferably 1 mg or less of mercury per 1 cc of internal volume of the hermetic container. It means to allow. However, it is environmentally desirable not to enclose mercury at all. In the case of maintaining the electrical characteristics of the discharge lamp with mercury vapor as in the prior art, in the short arc type, 20 to 40 mg per 1 cc of the internal volume of the hermetic container, and in some cases 50 mg or more was sealed, It can be said that the present invention has substantially less mercury.
[0032]
<Other Configurations of the Present Invention> By selectively adding the configuration shown below, the performance of the high-pressure discharge lamp is improved or the function is increased.
[0033]
1. About the outer tube The outer tube is made of quartz glass, high silicate glass, or the like, and is a means for accommodating at least the main part of the discharge vessel therein. It blocks UV rays radiated from the outer tube and arc tube to the outside, mechanically protects them, and touches the hermetic container of the arc tube with hands to cause fingerprints and fat and cause devitrification. Prevent it from happening or keep the airtight container warm. Further, the inside of the outer tube may be hermetically sealed with respect to the outside air according to the purpose, or air or an inert gas having the same or reduced pressure as the outside air may be enclosed. Further, if necessary, it may communicate with the outside air. Further, a light shielding film can be provided on the outer surface or the inner surface of the outer tube.
[0034]
Further, when forming the outer tube, the outer tube can be supported by the hermetic container by glass-welding both ends of the outer tube to the sealing portion extending in the tube axis direction from both ends of the hermetic container. it can.
[0035]
2. About the base The base functions to connect the high-pressure discharge lamp to the lighting circuit and in addition to support it mechanically.
[0036]
3. About the igniter The igniter is a means for generating a high-voltage pulse voltage and applying it to the high-pressure discharge lamp to promote its start-up. The igniter can be integrated with the high-pressure discharge lamp by storing it inside the base. it can.
[0037]
4). About the auxiliary starting conductor The auxiliary starting conductor is a means for increasing the electric field strength in the vicinity of the electrode to assist the starting of the high-pressure discharge lamp. One end of the auxiliary auxiliary conductor is connected to the same potential as the other electrode, and the other end is connected to one of the electrodes. It arrange | positions on the outer surface of the airtight container in the electrode vicinity.
[0038]
<About the effect | action of this invention> In this invention, as clear from the above description, After drawing with a die, Dice marks on the circumference 70% or more Since it is removed and the electrode is laser welded to the sealing metal foil, the adhesion between the electrode and the sealing metal foil during welding is increased, and the mechanical strength of the obtained welding is increased. As a result, the manufacturing yield is improved and the reliability of welding can be ensured.
[0039]
A lighting device according to a second aspect of the present invention comprises: a lighting device main body; the high-pressure discharge lamp according to claim 1 disposed in the lighting device main body; and a lighting circuit for lighting the high-pressure discharge lamp. It is a feature.
[0040]
In the present invention, the “illumination device” is a broad concept including all devices using a high-pressure discharge lamp as a light source, such as an automobile headlamp, a lighting fixture, a signal lamp, a marker lamp, an optical fiber illumination device, a photochemical reaction device, etc. It is. The “illuminating device body” means all remaining portions of the lighting device excluding the high-pressure discharge lamp and the lighting circuit.
[0041]
The lighting circuit is a means for lighting the high-pressure discharge lamp and is preferably an electronic one. However, if necessary, the lighting circuit may be mainly composed of a coil and an iron core. In the case of a lighting circuit for an automobile headlamp, the maximum input power up to 4 seconds immediately after lighting of a high-pressure discharge lamp, for example, a metal halide lamp, is 2 to 4 times the lamp power at the time of stability, preferably 2.5 to 4 By doubling, the rising of the luminous flux can be accelerated so as to fall within the range required for the automobile headlamp. In addition, when the sealing pressure of xenon as a rare gas is X (atmospheric pressure) in the range of 5 to 15 atm, and the maximum input power up to 4 seconds immediately after the metal halide lamp is turned on is AA (W), AA By satisfying the configuration, it is possible to obtain a luminous intensity of 8000 cd at a representative point on the front face of the headlamp necessary for an automotive headlamp by speeding up the rise of the light beam up to 4 seconds immediately after lighting.
[0042]
AA> −2.5X + 102.5
As described above, since the xenon sealing pressure and the maximum input power have a linear relationship only with a discharge medium having a low vapor pressure, the emission of xenon becomes overwhelming at the point of 4 seconds after starting. Because. The amount of light emitted from xenon is determined by the enclosed pressure of xenon and the power at that time. Therefore, if the xenon pressure is low, the input power may be increased. Conversely, if the xenon pressure is high, the input power may be reduced. In the present invention, the 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. A high-pressure discharge lamp that does not essentially enclose mercury, such as a metal halide lamp, generally has a lower lamp voltage than a mercury-enclosed metal halide lamp, so that the no-load output voltage of the lighting circuit can be 200 V or less. As a result, the lighting circuit can be miniaturized. In addition, a metal halide lamp enclosing mercury requires a no-load output voltage of about 400V.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0044]
1 to 3 show a metal halide lamp for an automotive headlamp as an embodiment of a high-pressure discharge lamp according to the present invention, FIG. 1 is a front view of the entire lamp, and FIG. 2 is a front view of an enlarged main part of a discharge vessel. 3A is an enlarged cross-sectional view of the electrode before removing the dice mark, and FIG. 3B is an enlarged cross-sectional view of the electrode after removing the dice mark.
[0045]
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.
[0046]
The discharge vessel IT includes an airtight vessel 1 and a pair of electrodes 1b and 1b. The airtight container 1 includes an enclosing portion 1a and a pair of sealing portions 1a1. The surrounding portion 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 substantially cylindrical discharge space 1c is formed therein.
[0047]
As shown in FIG. 3A, the electrode 1b is After drawing with a die, For example, an electric field treatment is performed on a tungsten wire having a die mark in advance to Dice mark After removing 70% or more, 100% in FIG. 3B, the base end is laser welded to a sealing metal foil 2 described later embedded in the sealing portion 1a1, and the intermediate portion is sealed. It is disposed at a predetermined position by being loosely supported by the part. Further, the base portion of the electrode 1b is welded to one end of the sealing metal foil 2 in the sealing portion 1a1. In FIG. 1, after forming the lower sealing portion 1 a 1, the sealing tube 1 a 2 is integrally cut from the lower portion of the sealing portion 1 a 1 without being cut and extends into the base B.
[0048]
The sealing metal foil 2 is made of molybdenum foil, and is hermetically embedded in the sealing portion 1 a 1 of the hermetic container 1.
[0049]
The distal ends of the pair of external lead wires 3A and 3B are welded to the other end of the sealing metal foil 2 in the sealing portions 1a1 at both ends of the airtight container 1, and the proximal end sides are led out to the outside. In FIG. 1, an external lead wire 3A led upward from the discharge vessel IT is folded back along an outer tube OT (described later) and introduced into a connector B (described later) to be connected to one of the terminal terminals (not illustrated). ing. In FIG. 1, the external lead wire 3B led downward from the discharge vessel IT extends along the tube axis, is introduced into the base B, and is connected to the other base terminal.
[0050]
In the enclosure 1a of the hermetic vessel 1, a light emitting metal halide, a lamp voltage forming metal halide and a rare gas are sealed as a discharge medium. The luminescent metal is sodium Na and scandium Sc, and the lamp voltage forming metal is zinc Zn.
[0051]
The outer tube OT has an ultraviolet ray cutting performance, houses 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 but communicates with the outside air.
[0052]
The insulating tube T covers the external lead wire 3A.
[0053]
The base B is standardized for automobile headlamps, supports the discharge vessel IT and the outer tube OT along the central axis, and is detachable from the back of the automobile headlamp. It is configured to be mounted.
【Example】
Discharge vessel IT
Airtight container 1a: made of quartz glass, sphere length 7 mm, maximum outer diameter 6 mm,
Maximum inner diameter 2.4mm, inner volume 0.025cc
Electrode 1b: Tungsten wire with a diameter of 0.40 mm, distance between electrodes 4.2 mm
Die mark removal rate 70% (electropolishing rate 8%)
Discharge medium
Metal halide: ScI ₃ -NaI-ZnI ₂ = 0.3mg
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
Input current immediately after lighting: 2.8A
Stable lamp voltage: 42V
Lamp power when stable: 35W
Next, the relationship between the die mark removal rate and the welding failure rate will be described with reference to FIG.
[0054]
FIG. 4 is a graph showing the relationship between the die mark removal rate and the welding failure rate in the high-pressure discharge lamp having the structure shown in FIG. In the figure, the horizontal axis represents the electropolishing rate (%) proportional to the die mark removal rate, and the vertical axis represents the welding failure rate (%). An electropolishing rate of 8% shown by drawing a line parallel to the vertical axis corresponds to a removal rate of 70%.
[0055]
As can be understood from the figure, when the dice mark is not removed, the defect rate is 9%, but when the dice mark is removed, the defect rate rapidly decreases, and when the removal rate becomes 70% or more, 1% % Or less, and remains almost constant thereafter.
[0056]
FIGS. 5 and 6 show an automotive headlamp device as an embodiment of the lighting 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 figure, the vehicle headlamp device HL is configured by a vehicle headlamp device body 21, a metal halide lamp HPDL, and two lighting circuits OL.
[0057]
The automotive headlamp device 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 combined with 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 light distribution characteristics required for each. The lamp socket 21d is connected to the output end of the lighting circuit OC and is attached to the base 21d of the metal halide lamp HPDL. The attachment portion 21e is a means for attaching the automobile headlamp device body 21 to a predetermined position of the automobile.
[0058]
The metal halide lamp HPDL has the structure shown in FIG. 1 and is lit horizontally. The lamp socket 21d is attached to and connected to the base. Thus, the two metal halide lamps KPDL are mounted on the vehicle headlight device main body 21 to constitute a four-lamp vehicle headlight device. The light emitting portion of each metal halide lamp HPDL is located substantially at the focal point of the reflectors 21b and 21c of the automotive headlamp device body 21.
[0059]
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 lights the metal halide lamp HPDL.
[0060]
As shown in FIG. 6, the lighting circuit OL includes a DC power source 11, a chopper 12, a control unit 13, a lamp current detection unit 14, a lamp voltage detection unit 15, an igniter 16, a metal halide lamp HPDL, and a full bridge inverter 17. Then, the metal halide lamp HPDL is lit in alternating current.
[0061]
The DC power source 11 is means for supplying DC power to a chopper 12 described later, and 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 11a is connected in parallel to perform smoothing.
[0062]
The chopper 12 is a DC-DC conversion circuit that converts a DC voltage into a DC voltage of a required value, and controls the metal halide lamp HPDL through a full bridge inverter 17 described later. 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.
[0063]
The control means 13 controls the chopper 12. For example, immediately after lighting, a lamp current more than three times the rated lamp current is passed through the metal halide lamp HPDL from the chopper 22 via the full-bridge inverter 17, and then the lamp current is gradually reduced over time. Control to make the lamp current. Further, the control means 13 generates a constant power control signal and performs constant power control of the chopper 22 by receiving feedback input of detection signals corresponding to the lamp current and the lamp voltage as will be described later. Further, the control means 13 has a built-in 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 supplied to the metal halide lamp HPDL. The chopper 12 is configured to control the current.
[0064]
The lamp current detection unit 14 is inserted in series with the lamp via the full bridge inverter 17, detects a current corresponding to the lamp current, and inputs the control input to the control unit 13.
[0065]
Similarly, the lamp voltage detection means 15 is connected in parallel with the metal halide lamp HPDL via the full bridge inverter 17, detects a voltage corresponding to the lamp voltage, and inputs the control input to the control means 23.
[0066]
The igniter 16 is interposed between the full bridge inverter 17 and the metal halide lamp HPDL, and is configured to supply a starting pulse voltage of about 20 kV to the metal halide lamp HPDL at the time of starting.
[0067]
The full bridge inverter 17 includes a bridge circuit composed of four MOSFETs Q1, Q2, Q3 and Q4, a MOSFET Q1 and Q3 of the bridge circuit 17a, a gate drive circuit 28b for alternately switching Q2 and Q4, and a polarity inversion circuit INV. Then, the DC voltage from the chopper 12 is converted into a rectangular-wave low-frequency AC voltage by the above switching and applied to the metal halide lamp HPDL to light the metal halide lamp HPDL with low-frequency AC lighting.
[0068]
Then, when the metal halide lamp HPDL is turned on with a rectangular wave low frequency alternating current using the lighting circuit OC, a required light flux is generated immediately after the 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.
[0069]
【The invention's effect】
According to claim 1, an airtight container provided with an enclosing portion and a pair of sealing portions, a pair of sealing metal foils airtightly embedded inside the sealing portion, After drawing with a die, Dice marks on the circumference 70% or more A pair of refractory metal rods that have been removed, the base end of which is laser welded to the sealing metal foil, and the tip of the pair faces the discharge space of the hermetic vessel so as to face the discharge space of the airtight container. By including the electrode and the discharge medium, when welding the sealing metal foil and the electrode, the two can be sufficiently brought into close contact with each other so that optimum welding conditions can be easily obtained. It is possible to provide a high pressure discharge lamp capable of improving the yield and reducing the cost and ensuring the reliability of welding.
[0070]
According to the invention of claim 2, it comprises: the lighting device main body, the high-pressure discharge lamp according to claim 1 disposed in the lighting device main body, and a lighting circuit for lighting the high-pressure discharge lamp. The lighting device having the effect of item 1 can be provided.
[Brief description of the drawings]
FIG. 1 is a front view showing an entire lamp of a metal halide lamp for an automotive headlamp as an embodiment of a high-pressure discharge lamp according to the present invention.
[Fig. 2] Front view of the enlarged main part of the discharge vessel
3A is an enlarged cross-sectional view of the electrode before removing the dice mark, and FIG. 3B is an enlarged cross-sectional view of the electrode after removing the dice mark.
4 is a graph showing the relationship between the die mark removal rate and the welding failure rate in the high-pressure discharge lamp having the structure shown in FIG.
FIG. 5 is a rear perspective view showing an automotive headlamp device as an embodiment of the illumination device of the present invention.
[Fig. 6] Circuit diagram of the lighting circuit
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Airtight container, 1a ... Enclosing part, 1a1 ... Sealing part, 1a2 ... Sealing tube, 1b ... Electrode, 1c ... Discharge space, 2 ... Sealing metal foil, 3A ... External lead wire, 3B ... External lead wire, 4 ... Reduced diameter part, B ... Base, HPDL ... Metal halide lamp, IT ... Discharge vessel, OT ... Outer tube, T ... Insulating tube

Claims (2)

A fire-resistant and light-transmitting hermetic container including an enclosure portion in which a discharge space is formed and a pair of sealing portions extending from both ends of the enclosure portion;
A pair of sealed metal foils hermetically embedded in a pair of sealing portions of the hermetic container;
After drawing with a die, it consists of a rod-shaped body made of refractory metal from which 70% or more of the dice marks on its peripheral surface have been removed. A pair of electrodes disposed at opposite ends of the discharge space so as to be spaced apart from each other;
A discharge medium enclosed in a discharge space of an airtight container;
A high-pressure discharge lamp comprising: A lighting device body;
The high-pressure discharge lamp according to claim 1 disposed in the illuminating device body;
A lighting circuit for lighting the high-pressure discharge lamp;
An illumination device comprising:

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