JP2009054409A - Metal halide lamp, metal halide lamp lighting device - Google Patents

Abstract

[PROBLEMS] To significantly improve the life characteristics of a mercury-free metal halide lamp.
A discharge vessel 11 is constituted by sealing portions 12a and 12b at both ends of a discharge space 14 in which a discharge medium containing a halide and a rare gas and not containing mercury is enclosed. The anode 3a2 and the cathode 3b2 are disposed to face each other in the discharge space 14, and one end of the metal foil 3a1 is coupled to the base side end of the anode 3a2, and one end of the metal foil 3b1 is coupled to the base side end of the cathode 3b2. The metal foils 3a1 and 3b1 are hermetically sealed by the sealing portions 12a and 12b. The other end portions of the metal foils 3a2 and 3b2 are coupled to the external leads 3a3 and 3b3, respectively, and are led out of the sealing portions 12a and 12b, respectively. The direction of the current flowing in the discharge vessel 14 is constant, the metal foil 3a1 on the anode 3a2 side contains 0.5 to 8 wt% of rhenium metal mainly composed of molybdenum metal, and the rhenium metal film is coated on the surface of the metal foil foil 3a1. did.
[Selection] Figure 1

Description

  The present invention relates to a discharge lamp, particularly a mercury-free metal halide lamp and a metal halide lamp lighting device.

Conventional mercury-free metal halide lamps that do not use mercury have a problem in that the metal foil made of molybdenum foil or the like that ensures the hermeticity of the discharge vessel tends to react with the discharge medium. In order to prevent the reaction with the discharge medium and to improve the life characteristics due to the absence of mercury. (For example, Patent Document 1)
Japanese Patent Laid-Open No. 2002-260581

  The technique of Patent Document 1 described above frequently blinks like an automobile headlamp, and the metal foil of the lamp that allows a large current to pass at the start does not satisfy the improvement in halogen resistance and adhesion with quartz. Must not. In particular, the metal foil on the anode side of the lamp, which frequently blinks like a DC lighting automotive headlamp and allows a large current to pass during start-up, does not fully satisfy the improvement in halogen resistance and adhesion with quartz. must not.

  However, when a coating film is formed on the surface of a metal foil made of molybdenum (Mo) in order to obtain halogen resistance, the film material is interposed between the surface of the metal foil and quartz glass so that the overall adhesion is There was a problem that it was not necessarily improved.

  An object of the present invention is to provide a mercury-free metal halide lamp and a metal halide lamp lighting device having improved life characteristics. It is another object of the present invention to provide a mercury-free metal halide lamp and a metal halide lamp lighting device that have improved life characteristics particularly in a direct current lighting system.

  In order to solve the above-described problems, a metal halide lamp according to the present invention includes a discharge vessel having a discharge space and sealing portions provided at both ends of the discharge space, and an electrode disposed to face the discharge space. One end of each of the electrodes is bonded to the base side end of the electrode, and the metal foil hermetically sealed by the sealing portion and the other end of the metal foil, respectively, A pair of external leads led out of the stopper, and a discharge medium enclosed in the discharge vessel, containing a halide and a rare gas, and essentially free of mercury, the metal foil comprising: It is characterized in that it contains 0.5 to 8 wt% of rhenium metal mainly composed of molybdenum metal, and a rhenium metal film is coated on the metal foil surface.

  A discharge vessel having a discharge space and sealing portions provided at both ends of the discharge space; an anode and a cathode disposed opposite to each other in the discharge space; and a base side end of the anode and the cathode One end of each of the metal foils is joined and hermetically sealed by the sealing part, and a pair of external parts connected to the other end of the metal foil and led out of the sealing part A lead, and a discharge medium enclosed in the discharge vessel, containing a halide and a rare gas, and essentially free of mercury, and the current flowing in the discharge vessel has a constant direction, at least The metal foil on the anode side contains 0.5-8 wt% of rhenium metal mainly composed of molybdenum metal, and a rhenium metal film is coated on the metal foil surface.

  In the present invention, the metal foil contains 0.5 to 8 wt% of rhenium metal mainly composed of molybdenum metal, and the rhenium metal film is coated on the surface thereof, thereby improving the life characteristics. In particular, in direct current lighting, the anode side metal foil mainly contains molybdenum metal and contains 0.5-8 wt% rhenium metal, and the surface thereof is coated with a rhenium metal film, thereby greatly improving the life characteristics. Is possible.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 are schematic configuration diagrams, and FIG. 2 is an enlarged configuration diagram of FIG. 1, for explaining an embodiment of a metal halide lamp according to the present invention.
Reference numeral 1 denotes an inner tube constituting a metal halide lamp. Plate-shaped sealing portions 12a and 12b are formed at both ends of the discharge vessel 11 at the center, and cylindrical unsealed at both ends. Stop portions 13a and 13b are formed. The inner tube 1 can be used as long as the material has excellent heat resistance and translucency. For example, quartz glass can be used.

  Inside the discharge vessel 11, a discharge space 14 having a substantially cylindrical shape at the center and a tapered shape at both ends in the axial direction is formed. The volume of the discharge space 14 is preferably 100 μl or less for a short arc type discharge lamp, and the volume of the discharge space is preferably 10 μl to 40 μl when an application is specified for an automotive headlamp.

  The discharge space 14 is filled with a discharge medium composed of the metal halide 2 and a rare gas, and the discharge medium essentially does not contain mercury. Next, a specific example of the discharge medium will be described.

  First, as the metal halide, halides of various metal elements can be used. For example, a first metal halide that mainly contributes to light emission is used. As the first halide, a halide of one or more kinds of metal elements selected from sodium (Na), scandium (Sc), and a rare earth metal is used. Na and Sc are particularly efficient luminous materials.

  The metal halide has a vapor pressure that is relatively high and includes one or more types of metal halides that do not easily emit light in the visible light region as compared to the metal of the first halide as the second halide. Can do. The metal that does not easily emit light in the visible light region has a higher energy level than the metal of the first halide and may be in a state where the metal of the first halide mainly emits light. By adding the second halide, a lamp voltage close to that of a lamp containing mercury can be obtained, and the electrical characteristics and light emission characteristics of the mercury-free metal halide lamp can be improved. The second halide contributes to chromaticity improvement and the like.

  Examples of the second halide include magnesium (Mg), iron (Fe), cobalt (Co), chromium (Cr), zinc (Zn), nickel (Ni), manganese (Mn), aluminum (Al), and antimony. One or more selected from (Sb), beryllium (Be), rhenium (Re), gallium (Ga), indium (In), titanium (Ti), zirconium (Zr), hafnium (Hf) and tin (Sn) These metal halides are used.

  As the halogen constituting the metal halide, iodine (I) is most suitable in terms of low reactivity, and the reactivity increases in the order of bromine (Br), chlorine (Cl), and fluorine (F), but is necessary. It is possible to select appropriately according to. Further, different halogen compounds such as iodide and bromide can be used in combination.

  Regarding the amount of metal halide to be enclosed, for example, the first halide that mainly contributes to light emission can be enclosed in the range of 5 mg to 110 mg per 1 cc of the internal volume of the discharge vessel (volume of the discharge space). A more preferable range is 5 mg to 35 mg per 1 cc of the internal volume of the discharge vessel. In such a range, the rise of the luminous flux can be accelerated and the light color can be stabilized. The second halide can be enclosed in the range of 0.05 mg to 200 mg per 1 cc of the internal volume of the discharge vessel. About other halides, it adjusts suitably.

  In addition to the starting gas and the buffer gas, the rare gas acts to emit main light immediately after the starting. Generally, it is not particularly limited as long as it does not pass through the discharge vessel, but when the discharge vessel is formed of quartz glass, argon (Ar), krypton (Kr), or xenon (Xe) is recommended. When light emission immediately after start-up depends on a rare gas, xenon is optimal because xenon has the highest luminous efficiency.

  When the enclosure pressure of the rare gas is increased, the lamp voltage is increased, and the lamp input can be increased for the same lamp current to improve the rising characteristics of the luminous flux. Good rise characteristics of the luminous flux are convenient for any purpose of use, but are particularly important for automotive headlamp devices and liquid crystal projectors. For example, the rare gas is sealed at a pressure of 3 atm or more, and is preferably sealed in a range of 5 to 15 atm.

  Further, “essentially no mercury is enclosed” is not limited to the state where mercury is not enclosed at all, and it is acceptable that less than 2 mg of mercury, preferably 1 mg or less of mercury exists per 1 cc of internal volume of the discharge vessel. Means. However, it is environmentally desirable that mercury is not encapsulated. In the case where the electrical characteristics of the discharge lamp are maintained by the conventional mercury vapor, the short arc type is filled with 20 mg to 40 mg of mercury per 1 cc of the internal volume of the discharge vessel, and in some cases, 50 mg or more of mercury. It can be said that the amount of mercury used in is essentially low.

  In FIG. 1 again, mounts 3a and 3b are sealed inside the sealing portions 12a and 12b. The mounts 3a and 3b include metal foils 3a1 and 3b1, an anode 3a2, a cathode 3b2, and external leads 3a3 and 3b3. The metal foils 3a1 and 3b1 are strip-shaped thin metal plates having a high melting point such as molybdenum.

  The metal foil 3a1 is composed of a rhenium metal film 4 mainly containing molybdenum, containing rhenium metal within 8 wt%, and further having a rhenium metal coated on the surface thereof. The rhenium metal film 4 is coated with a film thickness in the range of 200 nm to 2500 nm by an ion plating method described later.

FIG. 3 is a schematic configuration diagram for explaining a case where the metal halide lamp according to the present invention is applied to an automotive headlamp. The same components as those in FIG. The description will focus on the different parts.
In FIG. 3, the arc tube constituting the main part of the metal halide lamp has a double tube structure, and an inner tube 1 made of, for example, quartz glass is disposed inside the arc tube. The inner tube 1 has an elongated shape in the lamp axis direction, and a substantially elliptical discharge vessel 11 is formed at a substantially central portion thereof. Sealing portions 12a and 12b are formed at both ends of the discharge vessel 11, and cylindrical non-sealing portions 13a and 13b are formed at both ends thereof.

  A socket 7 is connected to the non-sealing portion 13a side of the arc tube. The metal band 71 attached to the outer peripheral surface of the outer tube 9 near the non-sealing portion 13a is connected to the four metal tongue pieces 72 formed on the opening end of the socket 7 on the inner tube 1 holding side. (In FIG. 3, two are shown). And in order to strengthen a connection further, the contact point of the metal band 71 and the tongue piece 72 is welded. A terminal to which an external lead 3a3 and a support wire (not shown) are connected is formed at the bottom of the socket 7.

  The other ends of the external leads 3a3 and 3b3 whose one ends are connected to the end portions of the metal foils 3a1 and 3b1 extend to the outside of the sealing portions 12a and 12b along the tube axis. One end of an L-shaped support wire 6 made of nickel is connected to the external lead 3 b 3 extending to the outside, and the other end extends in the direction of the socket 7. A portion of the support wire 6 parallel to the tube axis is covered with an insulating sleeve 8 made of ceramic.

  Outside the inner tube 1 configured as described above, a cylindrical outer tube 9 in which a metal oxide having an ultraviolet blocking effect is added to quartz glass along the tube axis is provided substantially concentrically with the inner tube 1. It has been. The inner tube 1 and the outer tube 9 are connected by welding the outer tube 9 in the vicinity of the cylindrical non-sealing portions 13a and 13b at both ends of the inner tube 1, and the inner space is airtight. In the space, for example, a rare gas such as nitrogen, neon, argon, xenon, or the like can be sealed or mixed.

FIG. 4 is an explanatory diagram for explaining a method of coating the rhenium metal film on the base side of the anode 3a2, the metal foil 3a1, and the external lead 3a3 connected to the metal foil 3a1 by ion plating. . FIG. 5 is an explanatory diagram for explaining a mount to which a rhenium metal film is applied.
In FIG. 4, reference numeral 61 denotes a vacuum chamber that has been evacuated. A large number of mounts 3 a shown in FIG. 5A are attached to a substrate 63 placed on a substrate support 62 that serves as a cathode above the vacuum chamber 61. . At this time, the external lead 3a3 is fixed to the substrate 63 with the anode 3a2 facing downward. The rhenium metal placed on the evaporation table 64 below the vacuum chamber 61 is heated and evaporated by electrode discharge. The evaporated rhenium metal is ionized and accelerated by the high frequency coil 65 installed between the evaporation table 64 and the substrate 63, and the surface of the mount 3a is coated as the rhenium metal film 4.

  The entire vacuum chamber 61 is uniformly coated on the entire surface of the mount 3a by, for example, applying two types of rotation in the X-axis and Y-axis directions. At this time, the film thickness of the coating can be determined by controlling the output and time of the high frequency coil 65.

  The anode 3a2 is bulky when the rhenium metal film is formed. Therefore, as shown in FIG. 5B, when the mount 3a ′ without the anode 3a2 is formed, the number of rhenium metal films 4 that can be formed at a time can be increased. There are advantages. The anode 3a2 and the metal foil 3a1 are joined using a joining means such as laser welding or resistance welding.

  The mount 3a thus coated with the rhenium metal film 4 is used in the metal halide lamp shown in FIG. The rhenium metal film 4 covered with the metal foil 3a1 prevents a reaction such as free iodine (I) with respect to the metal foil 3a1. Further, the high-quality rhenium metal film 4 formed on the surface of the metal foil 3a1 has a bonding effect with the rhenium metal component in the metal foil 3a1, thereby providing adhesion between the metal foil 3a1 and the quartz glass of the sealing portion 12a portion. It has been found that the flashing characteristics can be improved by improving the sealing power of the sealing portion 12a.

  The rhenium metal film 4 can be formed by a plating method in addition to the ion plating method. In the case of the plating method, the rhenium metal film 4 of the mount 3a is plated by plating the rhenium metal by dipping the mount 3a in the electrolyte solution while supporting the external lead 3a3 side and with the anode 3a2 facing down in FIG. Can be coated.

  Here, specific numerical values of the metal halide lamp when applied as a vehicle headlamp using the metal halide lamp of the present invention described in FIG. 3 will be given and described again with reference to FIG.

  The discharge vessel 1 made of quartz glass has an inner diameter A of 2.6 mm and is formed into a spheroidal shape. Elongated sealing portions 12a and 12b are provided at both ends of the major axis of the ellipse. The tip portions of the anode 3 a 2 and the cathode 3 b 2 are projected into the discharge space 14. The base portions of the anode 3a2 and the cathode 3b2 are welded to one ends of the metal foils 3a1 and 3b1, respectively, in the sealing portions 12a and 12b. The tip of the anode 3a2 has a sphere with a diameter B of 0.65 mm, an axial shape with a diameter C of 0.35 mm, and the material is doped tungsten. The cathode 3b2 has an axial shape with a diameter D of 0.35 mm, and the material is tungsten containing 1.0% tria. The distance E between the anode 3a2 and the cathode 3b2 is set to 4.2 mm.

  Further, the diameter F of the sealing portion 12a is 5 mm, and the metal foil 3a1 has a length of 12 mm, a thickness of 20 μm, and a width of 2.0 mm. In the discharge vessel 1, a rare gas, a first halide and a second halide are sealed as a discharge medium. The length of the metal foil 3b1 of the cathode 3b2 is 7 mm.

As the rare gas, 11 atm of xenon was enclosed. Further, scandium iodide (ScI ₃ ) 0.20 mg and sodium iodide (NaI) 0.5 mg were encapsulated as the first halide, and zinc iodide (ZnI ₂ ) 0.24 mg was encapsulated as the second halide, respectively. .

(Example 1)
The metal foil of this embodiment is particularly effective in improving the life of a mercury-free lamp operated by direct current, but is also effective in improving the life of a mercury-free lamp operated by alternating current. In Example 1, among the specific numerical values of the metal halide lamp described above, a 35 W AC type lamp different from FIG. 1 only in the dimensions of the electrode and the metal foil was used.

  Here, the material of the electrodes on both sides (corresponding to 3a2 and 3b2 in FIG. 1) is tungsten containing 1% tria, and has a shaft diameter of 0.36 mm and a length of 8 mm. The metal foils 3a1 and 3b1 have a width of 2 mm, a thickness of 20 μm, and a length of 7 mm, respectively.

As the materials of the metal foils 3a1 and 3b1, four types (A) to (D) were prepared. The metal foil (A) is a molybdenum foil containing 0.5 wt% yttria (Y ₂ O ₃ ), the metal foil (B) is a molybdenum foil containing 0.5 wt% yttria and 2 wt% rhenium, and a metal foil (C ) Is obtained by coating the surface of the metal foil (A) with a rhenium film at a thickness of 400 nm, and metal foil (D) is obtained by coating the surface of the metal foil (B) with a rhenium film at a thickness of 400 nm.

Yttria added in a small amount to molybdenum has an effect of increasing adhesion to quartz. It is known that addition of a small amount of silica (SiO ₂ ), hafnia (HfO ₂ ), zirconia (ZrO ₂ ), titanium oxide (TiO ₂ ), alumina (Al ₂ O ₃ ), etc. has the same effect. .

  Then, five AC lamps using these metal foils (A) to (D) for the metal foils 3a1 and 3b1, respectively, were manufactured. Using an alternating current lighting circuit, which will be described later, a blinking test was performed with alternating current power of 75 W at start-up and 35 W at steady state. The flashing test was performed using the flashing method of the Japan Light Bulb Industry Association “JEL215” flashing method. The time until the average leak point of the five lamps, in other words, the lighting time was as shown in FIG. .

  That is, it was 1500 hours for the metal foil (A), 1700 hours for the metal foil (B), 2700 hours for the metal foil (C), and 4200 hours for the metal foil (D).

  In the case of AC lighting, the influence of the reaction between the chemical and the metal foil of molybdenum is less than in the case of the anode side in DC lighting. Corresponding to flashing automobile headlamps, the Japan Light Bulb Industry Association standard “JEL215” flashing method consists of various combinations of flashing times. As the flashing time progresses, the foil gradually discolors from the electrode side of the foil due to a weak reaction with the chemical. In the case of AC lighting, this discoloration facilitates the peeling of the foil and quartz at that portion. The intense flashing causes stress in the bonded part of the quartz and foil, causing cracks in the quartz part, which is a problem. The metal foil (A) becomes disadvantageous in this way. Molybdenum foil containing 0.01 to 5 wt% rhenium is disclosed in International Patent Publication WO2006 / 035327. It is said that the surface state of the molybdenum foil is improved by containing rhenium. However, in Example 1, the metal foil (B) has a slightly longer life than the metal foil (A), but this is not a significant improvement.

  The metal foil (C) is a metal foil (A) coated with a rhenium film, but the reaction with chemicals is prevented by covering the surface of the molybdenum foil with the rhenium film. And the separation of quartz is difficult to proceed. Further, it is considered that the advantage that the adhesion between rhenium and quartz is superior to the adhesion between molybdenum and quartz is also effective. However, as the blinking progresses, the strain in the peeling direction increases at the boundary between the molybdenum and rhenium film of the metal foil. For this reason, the overall adhesion between the metal foil and the quartz decreases, stress is applied to the quartz, cracks progress, and leakage occurs. The case of the metal foil (D) is an example, but by containing rhenium in the molybdenum of the metal foil, the connectivity between the rhenium film and the metal foil is increased. For this reason, the strain in the peeling direction at the boundary between the rhenium film and the metal foil seen in the metal foil (C) is small. For this reason, the life of the metal foil (D) is improved as compared with the metal foil (C).

  With respect to the type of metal foil (D), the relationship between the rhenium content wt% of the metal foil and the lifetime was examined. From the rhenium content of 0.5% to 8%, such an effect of good bonding between the rhenium film and the metal foil (Mo-Re) was observed. However, when the rhenium content exceeds 8%, the strain between the metal foil and quartz becomes remarkable, and the life is shortened. As a more preferable range, the rhenium content was 1 to 5%.

In a mercury-free lamp, the reaction between the chemical and the metal foil on the anode side becomes significant in direct current lighting, which is a serious problem. That is, in a mercury-free halogen lamp, since a high vapor pressure, for example, zinc iodide, is enclosed as a lamp voltage forming substance, the amount of halogen anion (I ⁻ ) in the lamp is large. The halogen anion (I ⁻ ) is attracted to the anode in direct current lighting, and then passes between the electrode shaft and the quartz glass in a state presumed to be neutral halogen (I) and reaches the metal foil. To produce molybdenum iodide (MoI ₂ ). Since molybdenum iodide (MoI ₂ ) has a much lower density than Mo, the volume increases when molybdenum changes to molybdenum iodide (MoI ₂ ), and a great deal of stress is exerted on the surrounding quartz glass. When mercury is enclosed, the halogen anion (I ⁻ ) becomes free halogen (I) at a low temperature part and combines with mercury to form mercury halide (HgI ₂ , HgI). Does not surface.

(Example 2)
Next, the case where the structure of the metal halide lamp shown in FIG. That is, the diameter F of the sealing portion 12a is 5 mm, and the metal foil 3a1 on the anode side has a length of 12 mm, a thickness of 20 μm, and a width of 2.0 mm. The length of the metal foil 3b1 on the cathode 3b2 side is 7 mm.

  And 4 types of (A)-(D) were prepared for the material of metal foil 3a1, 3b1. The metal foil (A) is a molybdenum foil containing 0.5 wt% yttria, the metal foil (B) is a molybdenum foil containing 0.5 wt% yttria and 2 wt% rhenium, and the metal foil (C) is a metal foil (A ) Is coated with a rhenium film with a thickness of 400 nm, and the metal foil (D) is obtained by coating the surface of the metal foil (B) with a rhenium film with a thickness of 400 nm.

  Then, five lamps for direct current lighting using these metal foils (A) to (D) for the metal foils 3a1 and 3b1 were manufactured. Using a direct current lighting circuit described later, a blinking test was performed with a direct current power of 75 W at start-up and 35 W during steady operation. The blinking test was performed by a blinking test based on the blinking method based on the Japan Light Bulb Industry Association standard “JEL215”, and the time (lighting time) until five average leak points became as shown in FIG.

  That is, it was 210 hours for the metal foil (A), 230 hours for the metal foil (B), 2100 hours for the metal foil (C), and 3700 hours for the metal foil (D).

  The influence of the reaction between the chemical and the molybdenum metal foil in the case of AC lighting is less than that in the case of the anode side in DC lighting, and leakage is not particularly limited to the vicinity of the metal foil on either electrode side. However, in the case of direct current lighting, the reaction with the chemical proceeds violently on the metal foil on the anode side, so that leakage occurs from quartz near the metal foil on the anode side. The metal foil (A) and the metal foil (B), which are not subjected to measures against reaction with chemicals, have a very short life compared to the case of AC lighting.

  The metal foil (C) is obtained by coating the metal foil (A) with a rhenium film, and the reaction with the chemical is prevented by covering the surface of the molybdenum foil with the rhenium film. ) And the metal foil (B), the lifetime is greatly improved. Further, it is considered that the advantage that the adhesion between rhenium and quartz is superior to the adhesion between molybdenum and quartz is also effective.

  However, as the blinking progresses, the strain in the peeling direction increases at the boundary between the molybdenum and rhenium film of the metal foil. For this reason, the overall adhesion between the metal foil and the quartz decreases, stress is applied to the quartz, cracks progress, and leakage occurs. Further, as the flashing progresses, peeling occurs partially between the metal foil and the rhenium film, during which chemical (free iodine) erodes and reacts with molybdenum to advance quartz cracks.

  The case of the metal foil (D) is an example, but by containing rhenium in the molybdenum of the metal foil, the connectivity between the rhenium film and the metal foil is increased. For this reason, the strain in the peeling direction at the boundary between the rhenium film and the metal foil seen in the metal foil (C) is small. Further, due to the increase in the bonding property, partial peeling between the metal foil and the rhenium film seen in the metal foil (C) is prevented. Due to these two effects, the life of the metal foil (D) is greatly improved compared to the metal foil (C).

  In the case of direct current lighting, as in the case of alternating current lighting, the effect of good bonding between the rhenium film and the metal foil (Mo-Re) is seen from 0.5% rhenium, and the rhenium content exceeds 8%. The strain between the metal foil and quartz became prominent and the life was shortened. Moreover, the rhenium content rate was similarly 1 to 5% in the suitable range.

  The thickness of the rhenium film is suitably 200 to 2500 nm. When the film thickness is less than 200 nm, the reaction with free halogen becomes prominent as the lighting time becomes longer. If the film thickness is too thick, the adhesion with quartz is lowered. The preferred range was 400-2000 nm.

FIG. 8 is a circuit diagram for explaining a first embodiment relating to a metal halide lamp lighting device of the present invention. This embodiment is a lighting device for direct current lighting of the metal halide lamp of the present invention.
In the figure, 81 is a DC power source, 82 is a chopper, 83 is a control unit, R is a lamp current detecting means, VR is a lamp voltage detecting means, 84 is a starting portion, and 85 is a metal halide lamp having the configuration shown in FIG.

  As the DC power source 81, 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 C is connected in parallel to perform smoothing.

  The chopper 82 converts the DC voltage into a voltage having a required value and controls the metal halide lamp 85 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 unit 83 controls the chopper 82. 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 82 to the metal halide lamp 85, and thereafter, the lamp current is gradually reduced with the passage of time, and is controlled so as to eventually reach the rated lamp current. . The control unit 83 receives a detection signal of the lamp current and the lamp voltage as feedback, thereby generating a constant power control signal to control the chopper 82 with constant power. Further, the control unit 83 includes a microcomputer in which a temporal control pattern is incorporated in advance, and is configured to control the lamp current.

  The lamp current detection means R is inserted in series with the lamp, detects the lamp current, and inputs the control input to the control unit 83. The lamp voltage detection means VR is connected in parallel with the lamp, detects the lamp voltage, and inputs the control voltage to the control unit 83. The starting unit 84 is configured to supply a pulse voltage of 20 kV to the metal halide lamp 85 at the time of starting.

  Then, when the metal halide lamp is DC-lit using the metal halide lamp lighting device of this embodiment, 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. Further, no DC / AC conversion circuit is required, and it is possible to improve the life characteristics while enjoying the advantages of a metal halide lamp that is lit by DC.

  FIG. 9 is a circuit diagram for explaining a second embodiment relating to the lighting device of the present invention. The same parts as those in FIG. This embodiment is different in that the metal halide lamp is configured to be AC-lit.

  91 is an inverter that converts direct current into alternating current, and this inverter 91 is a full-bridge inverter. That is, a pair of switching circuits Q1, Q2 and a series circuit of Q3, Q4 are connected in parallel between the output ends of the chopper 82 to form a bridge circuit, and the oscillation output of the oscillator 92 is supplied to the four switching means Q1 to Q4. The switching means Q1, Q4 and Q2, Q3 in the diagonal direction are alternately supplied to Q4 to generate high-frequency alternating current between the output ends of the bridge circuit.

  The metal halide discharge lamp 85 is turned on by high frequency alternating current. In this AC lighting type configuration, the same control as in FIG. 13 is performed.

  According to each embodiment of the lighting device of the present invention of AC and DC, the above-described metal halide lamp of the present invention having excellent life characteristics can be safely maintained over a long period of time as a vehicle headlamp. .

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram for demonstrating one Embodiment regarding the metal halide lamp of this invention. The block diagram which shows the enlarged view of the principal part of FIG. The schematic block diagram for demonstrating the case where the metal halide lamp of this invention is applied for vehicle headlamps. The conceptual diagram for demonstrating the film-forming of rhenium metal by an ion plating method. Explanatory drawing for demonstrating the target object which applies the rhenium metal film of this invention. Explanatory drawing for demonstrating the result of Example 1 of this invention. Explanatory drawing for demonstrating the result of Example 2 of this invention. The circuit diagram for demonstrating 1st Embodiment regarding the lighting device of this invention. The circuit diagram for demonstrating 2nd Embodiment regarding the lighting device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner tube 11 Discharge container 12a, 12b Sealing part 13a, 13b Non-sealing part 14 Discharge space 2 Metal halide 3a, 3b Mount 3a1, 3b1 Metal foil 3a2 Anode 3b2 Cathode 3a3, 3b3 External lead 4 Rhenium metal film 81 DC power supply 82 Chopper 83 Control unit 84 Start unit 85 Metal halide lamp R Lamp current detection means VR Lamp voltage detection means

Claims (5)

A discharge vessel having a discharge space and sealing portions provided at both ends of the discharge space;
Electrodes disposed opposite to each other in the discharge space;
One end is joined to the base side end of the electrode, and a metal foil hermetically sealed by the sealing portion;
A pair of external leads coupled to the other end of the metal foil and led out of the sealing portion;
A discharge medium enclosed in the discharge vessel, containing a halide and a noble gas, and essentially free of mercury,
A metal halide lamp characterized in that the metal foil contains molybdenum metal as a main component and contains rhenium metal in an amount of 0.5 to 8 wt%, and the metal foil surface is coated with a rhenium metal film. A discharge vessel having a discharge space and sealing portions provided at both ends of the discharge space;
An anode and a cathode disposed opposite to each other in the discharge space;
One end is joined to the base side end of the anode and the cathode, respectively, and a metal foil hermetically sealed by the sealing portion;
A pair of external leads coupled to the other end of the metal foil and led out of the sealing portion;
A discharge medium enclosed in the discharge vessel, containing a halide and a noble gas, and essentially free of mercury,
The direction of the current flowing in the discharge vessel is constant, and at least the metal foil on the anode side contains 0.5 to 8 wt% of rhenium metal mainly composed of molybdenum metal,
A metal halide lamp characterized in that a rhenium metal film is coated on a metal foil surface.   The metal halide lamp according to claim 1 or 2, wherein the metal film has a thickness in a range of 200 nm to 2500 nm. A metal halide lamp according to any one of claims 1 and 3,
A metal halide lamp lighting device comprising: a lighting circuit that supplies current to a metal halide lamp to light it. A metal halide lamp according to claim 2 or 3,
A metal halide lamp lighting device comprising: a lighting circuit that supplies a current that is always in a single direction to a metal halide lamp so that the current flows in the discharge vessel without changing with time.

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