JP4922078B2 - Metal halide lamp - Google Patents

Description

  The present invention relates to a metal halide lamp used for an automotive headlamp or the like.

  A metal halide lamp used for an automobile headlamp is known from Japanese Patent No. 3664972 (hereinafter referred to as Patent Document 1), Japanese Patent Application Laid-Open No. 2001-266794 (hereinafter referred to as Patent Document 2), and the like. This lamp is a discharge lamp (hereinafter, a mercury-free lamp) in which xenon and a metal halide are enclosed as a discharge medium and mercury is not enclosed.

  In this mercury-free lamp, it is known that a crack is generated in the sealing portion where the metal foil is sealed, and a discharge medium or the like leaks from the crack, so-called crack leakage is likely to occur. Therefore, measures for foil leakage have been made, such as reviewing the connection conditions between the metal foil and the electrode as described in Patent Document 1, or processing the metal foil as described in Patent Document 2.

Japanese Patent No. 3664972 JP 2001-266794 A

  On the other hand, since mercury-free lamps tend to have less brightness than conventional mercury-containing lamps, attempts have been made to enclose high-pressure xenon in the discharge space in order to improve the total luminous flux. However, in a mercury-free lamp in which xenon is sealed at a high pressure, specifically 14 atm or more, the problem of foil leakage is more serious than before.

  As a result of examining this problem, it was found that the lamp encapsulating high-pressure xenon increased the load applied to the metal foil, and the glass and the metal foil were easily peeled off. Therefore, the inventors further studied and found that if the lamp design was changed in accordance with the xenon sealing pressure, it was possible to suppress foil leakage even when high-pressure xenon was sealed, so the present invention is proposed. It came.

  The objective of this invention is providing the metal halide lamp which can suppress generation | occurrence | production of foil leak.

  In order to achieve the above object, a metal halide lamp according to the present invention includes a discharge part in which a discharge space is formed, an airtight container having a pair of sealing parts formed at both ends of the discharge part, and the discharge space. A discharge medium containing encapsulated xenon and metal halide, a metal foil sealed to the sealing portion, a pair of electrodes having one end connected to the metal foil and the other end disposed opposite to the discharge space The enclosed pressure of xenon in the discharge medium is 14 atm or more, essentially does not contain mercury, the electrode diameter is R (mm), and the metal foil width is W (mm). ), When the sealed pressure of xenon is P (atm), the relationship of (R / W) ≦ −0.01P + 0.32 is satisfied.

  According to the present invention, the occurrence of foil leak can be suppressed.

(First embodiment)
Below, the metal halide lamp which is one Embodiment of the metal halide lamp of this invention is demonstrated with reference to drawings. FIG. 1 is a view for explaining a first embodiment of a metal halide lamp of the present invention.

  The metal halide lamp has an airtight container 1 made of a material having heat resistance and translucency, for example, quartz glass. The hermetic container 1 has an elongated shape in the lamp axis direction, and a substantially elliptical discharge portion 11 is formed at a substantially central portion thereof. Plate-shaped sealing portions 12a and 12b are formed at both ends of the discharge portion 11, and cylindrical non-sealing portions 13a and 13b are formed at both ends thereof. In addition, as for the dimension of sealing part 12a, 12b, thickness is 2.6 mm-3.0 mm, and width | variety is about 3.9 mm-4.3 mm.

Inside the discharge part 11, a discharge space 14 having a substantially cylindrical shape at the center and tapered at both ends is formed in the axial direction. The volume of the discharge space 14, when used as vehicle ^headlights, is preferably a 10mm ³ ~40mm 3.

The discharge space 14 is filled with a discharge medium composed of the metal halide 2 and a rare gas. The metal halide 2 is composed of sodium iodide (NaI), scandium iodide (ScI ₃ ), zinc iodide (ZnI ₂ ), and indium bromide (InBr). In addition, about the halogen couple | bonded with metal halides other than a scandium iodide, it is not limited to the above, You may use it combining a bromine, chlorine, or several halogen.

  As the rare gas, xenon which has high luminous efficiency immediately after starting and mainly acts as a starting gas is enclosed. Since the total luminous flux increases as the xenon sealing pressure increases, it is sealed at 14 atm or more at room temperature (25 ° C.). There is no particular upper limit, but at present, about 20 atm is considered the enclosure limit. The pressure of xenon is measured by collecting and surveying xenon in the discharge space 14 by breaking the boundary between the discharge part 11 and the sealing part 12a (or the sealing part 12b) in water, and then measuring the internal volume of the discharge part 11 It is calculated by measuring.

  Here, the discharge space 14 essentially does not contain mercury. This “essentially free of mercury” means that it contains no mercury at all, or an amount equivalent to that which is hardly enclosed even when compared with a conventional metal halide lamp containing mercury, for example, less than 2 mg per ml. Preferably, even if an amount of mercury of 1 mg or less is present, it is acceptable.

Mounts 3a and 3b are sealed inside the sealing portions 12a and 12b.
The mounts 3a and 3b are formed by integrally forming metal foils 3a1 and 3b1, electrodes 3a2 and 3b2, coils 3a3 and 3b3, and external lead wires 3a4 and 3b4 by laser welding. Specifically, a laser having a diameter of 250 μm is irradiated from the back side of the metal foils 3a1, 3b1, and the metal foils 3a1, 3b1 and the electrodes 3a2, 3b2 or a part of the external lead wires 3a4, 3b4 are melted to connect each other. Has been.

The metal foils 3a1 and 3b1 are thin metal plates made of , for example, molybdenum. The thickness is 15 to 25 μm, and the width W is 1.0 mm to 2.5 mm. Further, both ends in the width direction, the thickness of the end portion is not thin than the central portion, and a so-called knife-edge shape.

  The electrodes 3a2, 3b2 are tritated tungsten electrodes obtained by doping tungsten with thorium oxide, and their diameters R are 0.26 mm to 0.38 mm. The base end side is connected to the end portion of the metal foils 3a1, 3b1 on the discharge portion 11 side, and the tip end side is disposed in the discharge space 14 so as to face each other with a predetermined distance between the electrodes. ing. Here, the predetermined distance between the electrodes is preferably 4.1 mm to 4.5 mm in terms of appearance (3.5 mm to 3.9 mm in actual distance).

  The coils 3a3 and 3b3 are made of, for example, doped tungsten, and are spirally wound around the shafts of the electrodes 3a2 and 3b2 sealed by the sealing portions 12a and 12b. However, the coils 3a3 and 3b3 are not wound around the shaft portions of the electrodes 3a2 and 3b2 connected to the metal foils 3a1 and 3b1, but are wound in the direction of the discharge space 14 from the end of the foil. The winding conditions are as follows: the coil diameter is 0.03 mm to 0.15 mm, the pitch is 150% to 300%, and the winding length L ′ is 50 L / L with respect to the electrode sealing length L. % ≦ L ′ / L ≦ 95%.

  The external lead wires 3a4 and 3b4 are made of, for example, molybdenum, and are connected to end portions of the metal foils 3a1 and 3b1 on the opposite side to the discharge portion 11 by welding or the like. The other end sides of the external lead wires 3a4 and 3b4 extend along the tube axis to the outside of the sealing portions 12a and 12b, and further extend in the outward direction while being positioned at the approximate center of the non-sealing portions 13a and 13b. ing. One end of an L-shaped support wire 3c made of nickel is connected to the lead wire 3b4 extending to the front end side. The other end of the support wire 3c extends in the direction of a socket 6 described later. The support wire 3c parallel to the tube axis is covered with a sleeve 4 made of ceramic.

  A cylindrical outer tube 5 having an action of blocking ultraviolet rays by adding an oxide such as titanium, cerium, or aluminum to quartz glass is provided outside the hermetic container 1 configured as described above. Along the airtight container 1, the airtight container 1 is provided concentrically. These connections are made by melting the cylindrical non-sealing portions 13a, 13b at both ends of the hermetic container 1 and both ends of the outer tube 5. That is, welded portions 51 a and 51 b are formed at both ends of the airtight container 1 and the outer tube 5. The space between the airtight container 1 and the outer tube 5 can be filled with, for example, one or a mixture of rare gases such as nitrogen, neon, argon, xenon, and the like in the present embodiment. Nitrogen is enclosed at 0.05 atm to 0.5 atm.

  And the socket 6 is connected to the non-sealing part 13a side of the outer tube 5 in a state of covering the airtight container 1 inside. For these connections, the metal band 71 attached to the outer peripheral surface of the outer tube 5 in the vicinity of the non-sealed portion 13a is connected to four metal tongue pieces formed on the opening end of the socket 6 on the airtight container 1 holding side. 72 (two are shown in FIG. 1). In order to further strengthen the connection, the contact points of the metal band 71 and the tongue piece 72 are welded by laser. Note that a bottom terminal 8a and a side terminal 8b are formed at the bottom of the socket 6, and a lead wire 3a4 and a support wire 3c are connected thereto, respectively.

  By connecting a lighting circuit to the bottom terminal 8a and the side terminal 8b of the lamp constituted as described above, the lamp is lit at about 35 W at the stable time and at about 75 W, which is more than twice that at the start.

  FIG. 2 is a view for explaining one specification of the metal halide lamp of FIG. The following tests are performed based on this specification unless otherwise specified.

Discharge vessel 1: made of quartz glass, inner volume of discharge space 14 = 27 mm ³ , inner diameter A = 2.5 mm, outer diameter B = 6.2 mm, sphere length C in the longitudinal direction C = 7.8 mm,
Sealing portions 12a and 12b: thickness = 2.8 mm, width = 4.1 mm,
Metal halide _{2: ScI 3 -NaI-ZnI 2} -InBr = 0.40mg,
Noble gas: xenon = 14 atm,
Mercury: 0 mg,
Metal foils 3a1, 3b1: made of molybdenum, thickness 20 μm, width W = 1.5 mm, length = 65 mm,
Electrodes 3a2, 3b2: Triated tungsten, diameter R = 0.38mm, distance between electrodes D = 4.3mm, sealing length L = 4.65mm, connection length 1.0mm with metal foils 3a1, 3b1,
Coils 3a3, 3b3: made of doped tungsten, diameter = 0.05 mm, coil pitch = 250%, winding length L ′ = 3.2 mm,
External lead wires 3a4, 3b4: made of molybdenum, diameter = 0.4 mm.

  For the lamps with the above specifications, the width W of the metal foils 3a1 and 3b1 and the diameter R of the electrodes 3a2 and 3b2 were selected at random, and nine types of lamps having different R / W were created. FIG. 3 shows the specifications. And about the lamp | ramp 1-the lamp | ramp 9, the generation | occurrence | production situation of the foil leak after 2000-hour lighting when the pressure P of the enclosed xenon was changed to 13-17 atm was investigated. The result is shown in FIG. The number of tests is 3 for each, and the test condition is a flash cycle of the EU120 minute mode defined in JEL215, which is the standard for automotive headlamp HID light sources.

  As can be seen from the results, the larger the xenon pressure P, the more likely the foil leak tends to occur. In particular, it is found that the condition is such that the foil leak is more likely to occur at 14 atm or more. This is presumably because the load applied to the metal foil increases due to the high xenon pressure P, and the sealing glass and the metal foil easily peel off. That is, when the xenon pressure P is 14 atm or more, a stricter design is required to prevent foil leakage.

  Therefore, the result of FIG. 4 is illustrated in FIG. In the figure, ◯ means that the number of foil leaks is 0/3, Δ means 1/3, and x means 2/3 or more. As can be seen from FIG. 5, it can be seen that there is a correlation between the xenon pressures P and R / W and the occurrence of foil leak. That is, foil leakage can be prevented by designing so as to satisfy the approximate expression of R / W ≦ −0.01P + 0.32.

  The above design is desirably performed under the condition that the electrode sealing length L is 4.0 mm or more. The reason for this is that the load applied to the metal foil decreases as the electrode sealing length L increases and the foil temperature decreases. However, if the electrode sealing length L is too long, this will cause a problem of axial leakage. This problem can be solved by designing the relationship between the sealing length L of the electrodes 3a2, 3b2 and the winding length L 'of the coils 3a3, 3b3 to be 50% ≦ L ′ / L ≦ 95%.

  Therefore, in the present embodiment, the sealed pressure of xenon in the discharge medium is 14 atm or more, and in the metal halide lamp that does not essentially contain mercury, the diameter of the electrodes 3a2, 3b2 is R (mm), and the metal foil 3a1. Preventing foil leakage by satisfying the relationship of (R / W) ≦ −0.01P + 0.32, where the width of 3b1 is W (mm) and the sealing pressure of xenon is P (atm) Can do.

  In this case, the above design is preferably performed with an electrode sealing length L of 4.0 mm or more, and a relational expression between the sealing length L of the electrodes 3a2, 3b2 and the winding length L ′ of the coils 3a3, 3b3. By designing L ′ / L to be 50% ≦ L ′ / L ≦ 95%, foil leakage and shaft leakage can be prevented.

  The embodiment of the present invention is not limited to the above, and may be modified as follows, for example.

  The metal foils 3a1 and 3b1 are not limited to molybdenum foils, and rhenium tungsten foils or the like may be used. If desired, the foil surface may be roughened by sandblasting or laser, or a halogen-resistant film may be formed.

  The electrodes 3a2, 3b2 are not limited to triated tungsten electrodes, but may be electrodes made of pure tungsten, doped tungsten, rhenium tungsten, or the like. Moreover, the electrode with the stepped electrode in which the electrode front-end | tip part was formed larger diameter than the axial part, and the front-end | tip part formed in spherical shape or the half moon shape may be sufficient. In the case of such an electrode other than a straight rod, the diameter R of the present invention is the diameter of the portion sealed to the sealing portions 12a and 12b.

The figure for demonstrating 1st Embodiment of the metal halide lamp of this invention. The figure for demonstrating one specification of the metal halide lamp of FIG. The figure for demonstrating the specification of the lamps 1-9. The figure for lamp | ramp 1-9 for demonstrating the generation | occurrence | production situation of the shaft leak when changing xenon pressure. FIG. 5 is a graph of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airtight container 11 Discharge part 12a, 12b Sealing part 13a, 13b Non-sealing part 14 Discharge space 2 Metal halide 3a, 3b Mount 3a1, 3b1 Metal foil 3a2, 3b2 Electrode 3a3, 3b3 Coil 3a4, 3b4 External lead wire 3c Support wire 4 Sleeve 5 Outer tube 6 Socket 71 Metal band 72 Tongue piece 8a Bottom terminal 8b Side terminal

Claims (3)

A discharge part having a discharge space formed therein, an airtight container having a pair of sealing parts formed at both ends of the discharge part, a discharge medium containing xenon and a metal halide sealed in the discharge space; A metal foil sealed in a sealing portion; and one end connected to the metal foil, the other end comprising a pair of electrodes disposed opposite to the discharge space;
The enclosed pressure of xenon in the discharge medium is 14 atm or more and essentially does not contain mercury,
When the diameter of the electrode is R (mm), the width of the metal foil is W (mm), and the sealed pressure of xenon is P (atm), the relationship of (R / W) ≦ −0.01P + 0.32 is satisfied. This is a metal halide lamp.   2. The metal halide lamp according to claim 1, wherein L ≧ 4.0 mm is satisfied, where L is a distance from an end of the metal foil of the electrode to the discharge space.   A coil is wound on the electrode sealed in the sealing portion, and 50% ≦ L ′ / L ≦ 95% is satisfied, where L ′ is a winding length of the coil. The metal halide lamp according to claim 2.

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