JP2009043446A - Metal halide lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal halide lamp having superior light-emitting characteristics while preventing swelling of a discharge part. <P>SOLUTION: The metal halide lamp is equipped with an airtight container 1 which has a discharge part 11 in which a discharge space 14 is formed and a pair of sealing parts 12a, 12b formed at the both ends of the discharge part 11, a discharge medium which is filled in the discharge space 14 and contains xenon and a metal halide 2 having tin halide, but does not contain mercury in substance, and a pair of electrodes 3a2, 3b2 of which one end is fixed to the sealing parts 12a, 12b and the other ends are arranged oppositely in the discharge space 14. When the thickness volume of the discharge part 11 is V1 (mm<SP>3</SP>) and its inner volume is V2 (mm<SP>3</SP>), V1/V2≤4.5, and the filling amount of the tin halide is 0.5 wt.% or more and 5.0 wt.% or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  A metal halide lamp that does not use mercury (hereinafter referred to as a mercury-free lamp) is known from Japanese Patent Application Laid-Open No. 2003-187742 (hereinafter referred to as Patent Document 1). This mercury-free lamp has a structure in which halides such as xenon, sodium, scandium, and zinc are enclosed in the discharge space inside the discharge part instead of mercury. We are realizing the characteristics of lamps or better. However, characteristics such as luminous efficiency and luminous flux rise are still not satisfactory.

JP 2003-187742 A

  Therefore, attempts are being made to change the design of the discharge part, that is, the amount of glass and the internal volume of the glass. However, it has been found that when the amount of meat is reduced with respect to the internal volume in order to improve the light emission characteristics, there is a negative effect that the discharge part tends to swell.

  An object of the present invention is to provide a metal halide lamp having excellent light emission characteristics while suppressing swelling of a discharge portion.

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 including a rare gas and a metal halide having tin halide enclosed therein, substantially free of mercury, and a pair of one end sealed to the sealing portion and the other end opposed to the discharge space An electrode, and when the thickness of the discharge part is V1 (mm ³ ) and the internal volume is V2 (mm ³ ), V1 / V2 ≦ 4.5, and the enclosed amount of the tin halide is It is characterized by being 5.0% by weight or less.

  ADVANTAGE OF THE INVENTION According to this invention, the metal halide lamp excellent in the light emission characteristic can be provided, suppressing the swelling of a discharge part.

(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.

In the metal halide lamp, the hermetic container 1 is formed of a material having heat resistance and translucency, for example, quartz glass. Airtight container 1 is an elongated shape to the lamp axis, the discharge portion 11 of the substantially elliptical amount meat is 60mm ³ ~180mm ³ at its substantially central portion. 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.

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 (= the internal volume of the discharge portion 11) is desirably at 100 mm ³ or less, when used as vehicle headlights, more desirably at 15mm ³ ~40mm ^3.

The discharge space 14 is filled with a discharge medium composed of the metal halide 2 and a rare gas. As the metal halide 2, sodium halide, scandium halide, zinc halide, indium halide and tin halide are encapsulated. Other metal halides can be further encapsulated. The halogen is bound to the metal halide, iodine, bromine, can be combined chlorine, or a plurality of halogen, e.g., sodium iodide (NaI), scandium iodide (ScI _3), iodide Zinc (ZnI ₂ ), indium bromide (InBr), and tin iodide (SnI ₂ ) can be encapsulated.

  As the rare gas, xenon is enclosed. As the xenon sealing pressure increases, the total luminous flux increases and becomes brighter. Therefore, it is desirable to seal at least 12 atm, more preferably at least 14 atm at room temperature (25 ° C.). There is no particular upper limit, but at present, about 20 atm is considered the enclosure limit.

  Here, mercury is not substantially enclosed in the discharge space 14. “Mercury is substantially not encapsulated” means that it contains no mercury at all, or an amount equivalent to almost not encapsulated in comparison with a conventional metal halide lamp containing mercury, for example, less than 2 mg per ml, Preferably, it means that 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 constituted by metal foils 3a1 and 3b1, electrodes 3a2 and 3b2, coils 3a3 and 3b3, and external lead wires 3a4 and 3b4.

  Metal foil 3a1, 3b1, for example, a thin metal plate made of molybdenum.

  The electrodes 3a2 and 3b2 are triated tungsten electrodes having a diameter of 0.30 mm to 0.40 mm in which tungsten is doped with thorium oxide. 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.

  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. The other end sides of the external lead wires 3a4 and 3b4 extend to the outside of the sealing portions 12a and 12b along the tube axis. 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, and the support wire 3c parallel to the tube axis is covered with a sleeve 4 made of ceramic.

  A cylindrical outer tube 5 in which an oxide such as titanium, cerium, or aluminum is added to quartz glass is provided on the outside of the hermetic container 1 configured as described above, concentrically with the hermetic container 1 along the tube axis. It has been. 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. The space formed by the connection between the airtight container 1 and the outer tube 5 may be filled with, for example, nitrogen, neon, argon, xenon or the like at a pressure of 0.05 atm to 0.5 atm. it can.

  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). 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, about 75 W is supplied at the time of starting, and about 35 W is supplied at the time of starting. A current of about 0.8 A flows through the electrodes 3a2 and 3b2. That is, the current value at the time of starting is three times or more than the current value at the time of stabilization, which contributes to quickening the rise of the luminous flux.

  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; quartz glass,
Discharge unit 11; meat quantity V1 = 109 mm ^3, the internal volume ^V2 = 25.5 mm 3 of the discharge space 14, (V1 / V2 = 4.27 ), the inner diameter A = 2.4 mm, outer diameter B = 6.1 mm, longitudinal Direction sphere length C = 7.8 mm,
Metal halide 2; ScI ₃ -NaI-ZnI ₂ -InBr-SnI ₂ = 1: 1.6: 0.314: 0.007: 0.09, total amount M = 0.30 mg, inclusion of tin halide Amount = 3.0% by weight,
Noble gas; xenon = 15 atm,
Mercury; 0 mg,
Metal foils 3a1, 3b1; made of molybdenum,
Electrodes 3a2, 3b2; made of triated tungsten, diameter = 0.33 mm, distance between electrodes D = 4.34 mm,
Coils 3a3, 3b3; made of doped tungsten, diameter = 0.06 mm, coil pitch = 250%,
Lamp power: Start-up = 75W, stable = 35W
Lamp current; starting time = 2.8A, stable time = 0.818A.

FIG. 3 is a diagram for explaining the bulge amount of the discharge part when the relationship V1 / V2 between the thickness V1 of the discharge part and the internal volume V2 is changed. The test is a flash cycle of the EU 120 minute mode defined in JEL215, which is the standard for automotive headlamp HID light sources. Further, the amount of swelling means the amount of change in the inner diameter A after 2000 hours of lighting with respect to the initial inner diameter A of the discharge portion 11. The thickness V1 of the discharge part is calculated by cutting the boundary between the discharge part 11 and the sealing parts 12a and 12b, measuring the weight of the remaining discharge part 11, and then dividing by the specific gravity of the material of the discharge part 11. it can. For example, when the weight of the discharge part 11 is 0.29 g, the specific gravity of quartz glass is 2.66 g / cm ³ , and thus the amount of the meat is 109 mm ³ . On the other hand, the internal volume V2 of the discharge part 11 can be calculated by filling the discharge part 11 with water and dividing the filling amount by the specific gravity of water.

  As can be seen from this result, the bulge amount of the discharge part 11 is small when V1 / V2> 4.5, but the bulge amount tends to increase when V1 / V2 ≦ 4.5. This is considered because the burden on the discharge part 11 becomes large when V1 / V2 becomes small. In particular, the bulge is likely to occur when high power and high current are applied at the start or when the pressure of xenon is high. In addition, as shown in FIG. 4 which shows the state of the discharge part after 2000 hours lighting of the lamp with V1 / V2 = 4.24, the swelling is likely to occur at the upper part of the discharge part 11 heated by the arc (A1> A2). When the upper part of the discharge part 11 swells, the floating of the arc becomes large during horizontal lighting, so that the light distribution characteristic changes, or the lamp voltage rises early and easily disappears.

  On the other hand, for example, when V1 / V2 is 4.61, the total luminous flux is 3360 lm, and when V1 / V2 is 4.27, the total luminous flux is 3450 lm, and the light emission characteristic becomes higher as the value of V1 / V2 is decreased. Therefore, when a design satisfying V1 / V2 ≦ 4.5 is performed in order to improve the light emission characteristics, it is necessary to simultaneously take measures to prevent the swelling. However, if V1 / V2 is further reduced, the adhesion area of the inner surface of the discharge portion 11 of the metal halide 2 is increased, the light shielding effect is increased, and the total luminous flux starts to decrease. Therefore, 3.8 ≦ V1 / V2 is satisfied. The design within the range to satisfy is suitable.

  Therefore, as a result of investigation by the inventors, it has been found that, even under the condition of V1 / V2 ≦ 4.5, bulging can be prevented while maintaining the above lamp characteristics by enclosing an appropriate amount of tin halide.

  FIG. 5 is a diagram for explaining the total luminous flux at the beginning of lighting and the state of the discharge part after 2000 hours when the amount of tin iodide enclosed is changed. Note that V1 / V2 of the tested lamp is 4.24, and M / V2 is 0.015.

  As can be seen from this result, bulging occurs when tin iodide is not encapsulated or when the encapsulating amount is 0.3% by weight, but when it is 0.5% by weight or more, the bulging of the discharge part 11 is suppressed. Yes. This is presumably because the tin iodide quickly vaporized immediately after the start and contributed to the lamp voltage increase at an early stage, and the burden on the discharge part 11 was reduced. On the other hand, since tin iodide is a substance that hardly emits light, the total luminous flux decreases as the amount of encapsulation increases. In particular, as can be seen from FIG. 6 in which the total luminous flux in FIG. 5 is graphed, when the amount of tin iodide enclosed is greater than 5.0% by weight, the rate of decrease in the total luminous flux tends to increase. From the above, it is desirable that the amount of tin iodide enclosed be 0.5 wt% or more and 5.0 wt% or less. Note that the above is not limited to tin iodide, and the same applies to tin bromide and the like.

  On the other hand, if V1 / V2 is reduced as described above, the light shielding effect of the metal halide 2 is increased and the total luminous flux is reduced. Therefore, it is desirable to regulate the amount of the metal halide 2 enclosed. FIG. 7 shows a case in which the amount of tin iodide enclosed is 0% by weight, FIG. 8 shows a case in which the amount of tin iodide enclosed is 5.0% by weight, and FIG. It is a figure for demonstrating the total light beam when changing / V2 and M / V2.

As can be seen from the results, the total luminous flux tends to increase as M / V2 decreases in any lamp in which the amount of tin iodide enclosed is 0% by weight, 5.0% by weight, or 10.0% by weight. . Of particular note, however, the total luminous flux increases as V1 / V2 decreases when M / V2 = 0.02 mg / mm ³ or less, but M / V2 = 0.024 mg / mm ³ or more. Then, the total luminous flux is lower at M / V2 = 4.0 than when M / V2 = 4.2. In other words, when the amount of metal halide 2 enclosed is large, a phenomenon occurs in which the total luminous flux decreases when V1 / V2 is reduced. In this case, V1 / V2 is reduced for the purpose of improving the light emission characteristics. However, it is counterproductive. Therefore, it is effective to implement the present invention at M / V2 (mg / mm ³ ) ≦ 0.02. Note that if M / V2 is too small, the effect on the life characteristics is increased, and therefore it is desirable that the range is 0.007 ≦ M / V2 (mg / mm ³ ).

Therefore, in the present embodiment, when the thickness of the discharge part 11 is V1 (mm ³ ) and the internal volume is V2 (mm ³ ), V1 / V2 ≦ 4.5 and the enclosed amount of tin halide Is 0.5 wt% or more and 5.0 wt% or less, it is possible to suppress the swelling of the light emitting portion 11 during the lifetime while improving the light emitting characteristics.

  In addition, when the amount of metal halide 2 enclosed is M (mg), M / V2 ≦ 0.02, so that even if V1 / V2 is reduced, the total luminous flux is prevented from decreasing due to light shielding. can do.

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

  In the present invention, since the tin halide is encapsulated, the total luminous flux immediately after lighting, for example, 1 second after lighting, tends to be lower than in the past. Therefore, it is desirable to make up for the lowered initial total luminous flux by designing such as increasing the xenon pressure or reducing the diameter of the electrode. Moreover, it is desirable to employ a configuration in which the rise of the light beam is further accelerated by reducing the thickness of the lower part, such as by removing the lower part of the discharge part 11, as disclosed in JP-A-2006-185897.

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 amount of swelling of a discharge part when changing the relationship V1 / V2 of the meat | flesh amount V1 and internal volume V2 of a discharge part. The figure for demonstrating the state of the discharge part after 2000 hours lighting of the lamp | ramp which is V1 / V2 = 4.24. The figure for demonstrating the state of the discharge part after progressing the total luminous flux at the time of lighting at the time of changing the enclosure amount of tin iodide, and 2000 hours. The figure which graphed FIG. The figure for demonstrating the total light flux when V1 / V2 and M / V2 are changed in the lamp | ramp whose enclosing amount of tin iodide is 0 weight%. The figure for demonstrating the total light beam when V1 / V2 and M / V2 are changed in the lamp | ramp whose amount of tin iodide enclosure is 5.0 weight%. The figure for demonstrating the total light beam when V1 / V2 and M / V2 are changed in the lamp | ramp with which the enclosure amount of tin iodide is 10.0 weight%.

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 portion having a discharge space formed therein, an airtight container having a pair of sealing portions formed at both ends of the discharge portion, and a metal halide having a rare gas and tin halide sealed in the discharge space. Including a discharge medium substantially free of mercury, one end sealed to the sealing portion, and the other end includes a pair of electrodes disposed opposite to the discharge space,
When the thickness of the discharge part is V1 (mm ³ ) and the internal volume is V2 (mm ³ ), V1 / V2 ≦ 4.5 and the enclosed amount of the tin halide is 0.5% by weight or more. 5.0% by weight or less of a metal halide lamp.   2. The metal halide lamp according to claim 1, wherein M / V2 ≦ 0.02 when the amount of the metal halide enclosed is M (mg).   3. The metal halide lamp according to claim 1, wherein the tube shaft is turned on in a substantially horizontal state, and a current more than three times as stable as that at the time of start-up is supplied.

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