JP4367714B2 - Metal halide lamp - Google Patents

Description

  The present invention relates to an improvement in a metal halide lamp including a translucent airtight container made of quartz glass.

  In the metal halide lamp, a discharge medium containing a halide of a luminescent metal is sealed in a light-transmitting hermetic container in which a pair of electrodes are sealed. Quartz glass or translucent ceramics is used as a constituent material of the translucent airtight container. Quartz glass-made translucent airtight containers are frequently used mainly for metal halide lamps such as headlamps and projections because they are relatively inexpensive and have high linear transmittance. In the translucent airtight container made of quartz glass, a sealing portion connected to the surrounding portion is formed integrally with the surrounding portion in order to seal the surrounding portion in which the discharge space is formed.

  In order to seal the light-transmitting airtight container with the sealing part, it is common to embed a sealing metal foil in the sealing part in an airtight manner. Then, the base end of the electrode is welded to one end of the sealing metal foil on the surrounding portion side, and an external lead wire is welded to the other end to supply power to the electrode via the sealing metal foil.

  Thus, in the light-transmitting airtight container made of quartz glass, the sealing metal foil embedded in the inside of the sealing portion and the quartz glass surrounding the sealing metal foil have good bonding throughout the lighting of the metal halide lamp. By forming, the inside of the translucent airtight container is maintained in an intended airtight state. When forming the sealing part using the sealing metal foil, the length of the outer periphery of the sealing metal foil is made fine by applying a satin finish on both the front and back surfaces of the sealing metal foil by sandblasting or an electrochemical method. It is known to increase the unevenness to suppress leakage occurring in the sealing portion (see, for example, Patent Document 1).

  That is, in a metal halide lamp, it is advantageous to give the surface of the sealing metal foil an appropriate roughness.

Japanese Patent No. 3150918

  However, in the case of the sealing metal foil described in Patent Document 1, a rough surface is formed only in a desired partial region of the foil, or the surface roughness of the rough surface is changed as desired depending on the region. The formation position and surface roughness of the rough surface cannot be controlled as desired. For this reason, for example, when it is intended to form a rough surface having an effective surface roughness to improve the adhesion between the sealing metal foil and the quartz glass, there is a problem that the side edge portion which is brittle in strength is easily broken. .

  In addition, when the rough surface is formed by the sandblast method, the sprayed abrasive grains tend to adhere to the sealing metal foil and remain, so that the abrasive grains become impurities and the conductive connection between the electrode or external lead wire and the sealing metal foil The formation of the part and the adhesion of the sealing part are likely to be hindered. Moreover, when it is going to remove the abrasive grain adhering to sealing metal foil, a post-process will be needed and will require time and effort, and it will be difficult to remove enough.

  Therefore, the present inventor, when forming a rough surface on the surface of the sealing metal foil by laser processing, the adhesion between the sealing metal foil and the quartz glass is improved, the desired roughness on the sealing metal foil, It was found that a rough surface having a desired shape can be easily formed. The present invention has been made based on such knowledge.

An object of this invention is to provide the manufacturing method of the metal halide lamp which suppressed generation | occurrence | production of the crack leak in the sealing part which formed the rough surface of sealing metal foil by laser processing , and embedded sealing metal foil.

A metal halide lamp according to the present invention includes a light-transmitting airtight container made of quartz glass provided with an enclosure having a discharge space inside and a sealing portion connected to the enclosure; and sealed in the discharge space of the light-transmitting airtight container A discharge medium containing at least a light-emitting metal halide and a rare gas and sealed in a discharge space of the light-transmitting hermetic container; and sealing the light-transmitting hermetic container connected to the base end of the electrode It comprises a; buried hermetically portion, the sealed metal foil rough surface is formed on the surface of the sealed metal foil by forming a plurality of spots having a recess with a laser irradiated a plurality of times on the surface It is characterized by being.

According to the present invention, the sealing metal foil having a rough surface formed by irradiating the laser a plurality of times to form a plurality of spots having dents is embedded in the sealing portion. It is possible to provide a metal halide lamp in which the sealing property between the foil and the quartz glass of the sealing portion is excellent and crack leakage is suppressed.

Further, according to the present invention, since a plurality of spots was formed rough surface having a recess with a laser irradiated a plurality of times, the rough surface of Nozomu Tokoro surface roughness, to a desired area, yet desired It can be formed by controlling to the extent of.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

    1 to 4 show a metal halide lamp for an automobile headlamp as a first embodiment for carrying out the metal halide lamp of the present invention, FIG. 1 is a side view, and FIG. 2 is an enlarged front view of a sealing metal foil portion. FIG. 3 is an enlarged cross-sectional view of a sealing metal foil, and FIG. 4 is a schematic enlarged cross-sectional view showing an enlarged cross-sectional shape of a groove formed by laser processing.

  In this embodiment, the metal halide lamp MHL includes an arc tube IT, an insulating tube T, an outer tube OT, and a base B.

  [About the arc tube IT] The arc tube IT includes a translucent airtight container 1, an electrode 2, a sealing metal foil 3, external lead wires 4A and 4B, and a discharge medium.

    (Translucent Airtight Container 1) The translucent airtight container 1 is made of quartz glass, has translucency and fire resistance, and has an enclosure 1a and a seal in which a discharge space 1c is formed. Part 1b is provided. The surrounding part 1a is hollow, and the hollow part becomes the discharge space 1c. The internal volume of the discharge space 1c can be appropriately set according to the use of the metal halide lamp, but is generally 0.1 cc or less as a small metal halide lamp suitable for applying the present invention. In the case of a headlamp, it is preferably 0.05 cc or less.

  The discharge space 1c can have an arbitrary shape such as a substantially cylindrical shape, a spherical shape, or an elliptical spherical shape. In the case of a headlamp, it preferably has a substantially cylindrical shape. On the other hand, the outer surface of the surrounding part 1a of the translucent airtight container 1 has a rotating quadratic curved surface shape such as an elliptical shape or a spindle shape. Therefore, the wall thickness of the surrounding portion 1a is generally the largest in the central portion in the tube axis direction and gradually decreases in both end directions.

  Moreover, the preferable size of the enclosure part 1a in the translucent airtight container 1 as the metal halide lamp MHL for motor vehicle headlamps, and the discharge space 1c formed in the inside is as follows. That is, the length of the surrounding portion 1a in the tube axis direction is 7.4 to 8.2 mm, the inner diameter of the discharge space 1c is 2.2 to 2.9 mm, the outer diameter is 5.6 to 6.9 mm, and the wall thickness is 1 0.7 to 2.5 mm, and the internal volume of the discharge space 1c is 20 to 35 μl.

  Furthermore, the light-transmitting hermetic container 1 is “translucent and fireproof” means that at least the light guide portion, which is a portion where light emission is to be led out to the outside of the surrounding portion 1a, is light-transmitting. In addition, it means that it has at least heat resistance enough to withstand the normal operating temperature of the metal halide lamp MHL. In addition, a halogen-resistant or halogenated-resistant transparent film is formed on the inner surface of the surrounding portion 1a of the translucent airtight container 1 or the inner surface of the translucent airtight container 1 is modified as necessary. Is acceptable.

  The sealing part 1b is formed integrally with the surrounding part 1a adjacent to the surrounding part 1a. In this embodiment, a pair of sealing portions 1b can be formed so as to extend to both ends of the surrounding portion 1a in the tube axis direction. The sealing portion 1b seals the surrounding portion 1a, and a base end portion of an electrode 2 described later is embedded here. In order to realize this, a sealing metal foil 3 described later is embedded in the sealing portion 1b. Further, the pair of sealing portions 1b and 1b extend integrally from both ends of the surrounding portion 1a along the tube axis direction.

    (About the electrode 2) The main part of the electrode 2 is sealed at a predetermined position in the surrounding part 1a of the translucent airtight container 1. For this purpose, the intermediate part of the electrode 2 is loosely supported by the sealing part 1b and the base end is connected to the sealing metal foil 3 by welding or the like. When the pair of electrodes 1b and 1b are sealed and opposed to each other inside the surrounding portion 1a, the pair of sealing portions 1b and 1b are disposed at both ends of the surrounding portion 1a.

  In addition, the electrode 2 is preferably set to an appropriate value within a range of the diameter of the shaft portion in a range of 0.25 to 0.45 mm.

  Further, the electrode 2 can be formed of a refractory metal selected from the group such as tungsten (W), doped tungsten, thorium tungsten, rhenium (Re), and tungsten-rhenium alloy (W-Re) in this embodiment. .

  Furthermore, the tip of the electrode 2 can be made larger in diameter than the shaft, for example, a columnar shape or a substantially spherical shape. In this case, it is preferable that the shaft portion has a diameter of 0.25 to 0.30 mm and the tip portion has a diameter of 0.30 to 0.40 mm.

  In addition, the specification which winds the coil which consists of tungsten, for example to the axial part of the electrode 2 supported in the sealing part 1b may be sufficient.

    (About Sealing Metal Foil 3) The sealing metal foil 3 is embedded in the sealing portion 1b in an airtight manner to seal the surrounding portion 1a. In addition, in order to supply power to the electrode 2 from an electronic lighting circuit (not shown), the base end portion of the electrode 2 is connected to one end of the sealing metal foil 3 on the side of the surrounding portion 1a, and the other end described later is connected to the outside. Lead wires 4A and 4B are connected. The thickness of the sealing metal foil 3 is not particularly limited in the present invention, but is generally 50 μm or less.

In the present invention, the sealing metal foil 3 is the most characteristic component, and the surface of the sealing metal foil 3 is roughened by forming a plurality of spots having dents by laser processing that irradiates the laser a plurality of times. RS is formed. In this embodiment, the rough surface RS is that make up a plurality of grooves G parallel to the electrode axis direction as shown in FIG. In laser processing , by irradiating the surface of the sealing metal foil 3 with a laser once, for example, one recessed spot is formed as shown in FIG. Therefore, if the laser is irradiated a plurality of times, for example, a plurality of spots are formed as shown in the micrograph of FIG. The spot can control the method of focusing the laser, the shape of the cross section of the recess formed by the input control, and the like. For example, a groove G having a recess having an inverted triangle or inverted trapezoidal cross-sectional shape as shown in FIGS. 4A and 4B can be obtained in the sealing metal foil 3 . Then, by irradiating a part of the previously formed spot with laser again, a groove G in which a plurality of spots are connected to each other can be obtained as shown in the micrograph of FIG. Here, the depth of the recess of the spot constituting the groove G can be freely controlled by changing the laser current value, and the spot diameter can be freely controlled by changing the focal point and the distance from the laser irradiation unit to the irradiation position. Is possible.

Note that spots formed me by the laser processing, by enlarging the spot by a microscope, it is possible to observe the pattern as shown in FIG. That is, since the spot-like laser marks melted and formed by laser irradiation remain on the surface of the sealing metal foil 3, it can be easily determined whether or not the processing has been performed.

In addition, the region where the rough surface RS is formed is preferably the case where it is almost the entire surface of both surfaces of the sealing metal foil 3 because the highest adhesion is obtained. Furthermore, when forming the groove | channel G, it is suitable to form so that the groove | channel G may not be connected with the edge part of the sealing metal foil 3. FIG. Then, the phenomenon that the halide diffuses or progresses radially from the base end portion of the electrode 2 along the surface of the surrounding sealing metal foil 3 and destroys the sealing between the sealing metal foil 3 and the quartz glass. This is because such an aspect also provides the desired effect of the present invention. For the purpose of obtaining such an effect, the groove G may be provided at least in the vicinity of the connection portion of the electrode 2 connected to the sealing metal foil 3. In addition, the said vicinity is a position where the electrode 2 is connected, a position further advanced from the position toward the center between the both ends of the sealing metal foil 3, and a position away from both side edges of the sealing metal foil 3. It is a concept that includes

As an example of the groove G formed by laser processing, a groove in which a plurality of grooves G parallel to the electrode axis direction are arranged on both surfaces of the sealing metal foil 3 as shown in FIG. Forming such a groove is advantageous because it provides both the effect of improving the adhesion between the sealing metal foil 3 and the glass and suppressing the diffusion of halides to the side edge of the sealing metal foil 3.

FIG. 3 shows an enlarged cross-sectional shape of FIG. The sealed metal foil 3 in which a plurality of spots are formed by laser processing extending in the tube axis direction has a knife edge that gradually becomes thinner toward the side edge in order to improve the adhesion between the foil and the glass. It is in the shape. In the case of forming a rough surface by laser processing with respect to the sealing metal foil 3 having such a shape, the side edge portion is not penetrated or broken by the groove G, and a knife edge shape is formed. It can be Rukoto so as not to form a rough surface on the part.

  Next, a suitable surface roughness of the rough surface RS formed by the groove G by laser processing will be described with reference to Ra and Rz values standardized by JIS B0601.

First, the surface roughness Ra will be described. The surface roughness Ra (μm) of the rough surface RS composed of a plurality of spots formed by laser processing is generally preferably in a range satisfying the formula 0.4 ≦ Ra. The above formula has no upper limit for the following reason. That is, in the present invention, the larger the numerical value of the surface roughness Ra, the more effective, and it is possible to form a considerably rough surface by laser processing, but considering the strength of the sealed metal foil. More preferably, it is a range satisfying the formula Ra ≧ 4.0.

Next, the surface roughness Rz will be described. The surface roughness Rz (μm) is generally preferably in a range satisfying the formula 1.0 ≦ Rz ≦ 7.0. Since the function of the sealing metal foil 3 is hindered if the depth of the recesses of the plurality of spots constituting the rough surface RS exceeds the thickness, the rough surface RS does not penetrate the sealing metal foil 3 in the thickness direction. Must be deep. Further, as a guideline for fully utilizing the function of the sealing metal foil 3, it is desirable that the depth of the recess is about half of the thickness.

Also, when controlling a spot formed by the laser machining, dent depths of their is a current value when generating the laser spot, the width of the spot diameter, the pitch of the adjacent rough surface RS is the irradiation position of the laser spot It is effective to change each of them.

  Further, the material of the sealing metal foil 3 is not particularly limited. For example, molybdenum (Mo) or rhenium-tungsten alloy (Re-W) can be used.

  Furthermore, the method of embedding the sealing metal foil 3 in the sealing portion 1b is not particularly limited, but, for example, a reduced pressure sealing method, a pinch sealing method, or the like can be employed alone or in combination. In the case of a metal halide lamp used for a headlamp or the like in which a rare gas such as xenon (Xe) is enclosed at 5 atm or more at room temperature with a small inner volume of the surrounding portion 1a of 0.1 cc or less, the latter is preferable.

  By the way, in FIG. 1, after forming the left sealing portion 1b, the sealing tube 1d is integrally removed from the outer end portion of the sealing portion 1b without being cut out, and extends into a base B described later. is doing.

    (About External Lead Wires 4A and 4B) In this embodiment, the outer lead wires 4A and 4B are welded to the other end of the sealing metal foil 3 in the sealing portions 1b at both ends of the translucent airtight container 1. The base end side is led out to the outside. In FIG. 1, the external lead wire 4A led rightward from the arc tube IT is folded back along an outer tube OT (to be described later) and introduced into a base B (to be described later), and is connected to one t1 of a base terminal (not shown). Connected. In FIG. 1, the external lead wire 4B led out from the arc tube IT to the left extends along the tube axis in the sealing tube 1d and is introduced into the base B to be connected to the other of the base terminals (not shown). .) Is connected.

    (Regarding the discharge medium) The discharge medium contains at least a metal halide and a rare gas. Mercury may or may not be included. However, according to the present invention, since the sealing metal foil is provided with the rough surface RS formed by laser processing, the adhesiveness with the quartz glass of the sealing portion 1b is remarkably excellent. Even if the mercury-free metal halide lamp has a higher internal pressure during lighting and the temperature of the sealing metal foil than that of the metal halide lamp, crack leakage is effectively suppressed and a metal halide lamp with good life characteristics can be obtained. Needless to say, if it is suitable for a mercury-free lamp, it can be applied to a mercury-containing lamp having a lower internal pressure during operation and a lower temperature of the sealing metal foil without any problem.

  The metal halide is a metal halide containing at least a luminescent metal. However, the specific metal halide is not particularly limited. For example, a preferred configuration as a mercury-free lamp for a headlamp includes a plurality of metals selected from the group of scandium (Sc), sodium (Na), indium (In), zinc (Zn), and rare earth metals. Contains halides. In this aspect, in addition to the structure which consists only of the halide of the metal which belongs to the said group, the discharge medium is allowed to contain the halide of metals other than a group supplementarily. For example, the luminous efficiency can be further increased by adding a thallium (Tl) halide as the main light-emitting substance.

  In the above embodiment, the halide of zinc (Zn) has a relatively high vapor pressure and a small amount of light emission in the visible region, and therefore contributes mainly to lamp voltage formation. However, as the metal halide for forming the lamp voltage, it has almost the same function and effect as zinc if desired. Therefore, in place of zinc or in addition to this, metal halides of the following groups are used. Can be used. That is, magnesium (Mg), cobalt (C), chromium (Cr), manganese (Mn), antimony (Sb), rhenium (Re), gallium (Ga), tin (Sn), iron (Fe), aluminum (Al ), Titanium (Ti), zirconium (Zr), and hafnium (Hf), the lamp voltage can be increased to a desired value by enclosing one or more metal halides selected from the group. None of the above metals are expected to be metals that have high vapor pressure and do not emit light in the visible range, or that emit relatively little light, i.e., light-emitting metals that generate luminous flux, but are primarily suitable for forming lamp voltages. It is a metal.

  The rare gas acts as a starting gas and a buffer gas, and one or a plurality of kinds such as argon (Ar), krypton (Kr), and xenon (Xe) can be used. In addition, as a metal halide lamp MHL for automobile headlamps, xenon is preferably 5 atm or more, preferably in the range of 7 to 18 atm, and more preferably in order to accelerate the rise of luminous flux and emit white light immediately after starting. It shall be sealed in the range of 8 to 13 atmospheres, or sealed so that the pressure in the internal space at the time of lighting is 50 atmospheres or more. Thereby, when the vapor pressure of the luminescent metal immediately after the start is low, white light emission of Xe can be contributed as a luminous flux at the time of startup.

    (Mercury) In the case of an embodiment as a mercury-free lamp, essentially no mercury is contained. In this embodiment, not only mercury (Hg) is not enclosed, but also it is allowed that less than 2 mg, preferably 1 mg or less of mercury is present per 1 cc of the inner volume of the translucent airtight container 1.

However, it is environmentally desirable not to enclose mercury at all. When the lamp voltage of the discharge lamp is increased to a required level with mercury vapor as in the conventional case, the short arc type may contain 20 to 40 mg per 1 cm ³ of the inner volume of the hermetic container, and moreover 50 mg or more in some cases. It can be said that the amount of mercury is substantially low.

    (Type of Halogen) As the type of 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.

  [Insulating Tube T] The insulating tube T is made of ceramics, and the insulating tube T covers the external lead wire 4A.

  [Outer tube OT] In the present invention, the metal halide lamp MHL is allowed to include the outer tube OT as desired. The outer tube OT is made of quartz glass or high silicate glass, and is a means for accommodating at least the main part of the arc tube IT therein. Then, UV rays radiated from the arc tube IT to the outside are blocked, mechanically protected, and touching the translucent airtight container 1 of the arc tube IT with a hand, it is attached to human fingerprints and fat and is devitrified. Prevent the cause or keep the translucent airtight container 1 warm.

  Further, the inside of the outer tube OT may be hermetically sealed against the outside air according to the purpose, or an inert gas may be enclosed. In this embodiment, nitrogen is sealed at 0.1 atm.

  In the illustrated embodiment, when the outer tube OT is formed, the outer tube OT is made transparent by glass-welding both ends thereof to sealing portions extending in the tube axis direction from both ends of the translucent airtight container 1. It can comprise so that it may support with the airtight container 1. FIG. The outer tube OT has an ultraviolet ray cutting performance, accommodates the arc tube IT therein, and the diameter-reduced portions 5 at both ends are welded to the sealing portion 1b of the arc tube IT. However, the inside is not airtight but communicates with the outside air.

  [About Base B] In the present invention, the metal halide lamp MHL is allowed to include the base B as desired. The base B is a means that functions to connect the metal halide lamp MHL to a lighting circuit (not shown) or to mechanically support the metal halide lamp MHL. In the illustrated form, the base B is standardized for an automobile headlamp. The arc tube IT and the outer tube OT are planted and supported along the central axis, and are configured to be detachably mounted on the rear surface of the automobile headlamp.

  Next, an example of the rough surface RS of the sealing metal foil 3 will be described as follows.

Ra = 0.8, Rz = 2.7
In the above embodiment, a YAG laser having a diameter of 18 A and a spot diameter of 30 μm was used for laser processing. Moreover, in the case of the said Example, the depth of the groove | channel G is about 2 micrometers, and a pitch is about 50 micrometers.

Further, Table 1 and FIG. 5 show the results of testing the leak occurrence rate and the leak occurrence time in the EU rated mode lighting for the metal halide lamp manufactured using the sealed metal foil 3 with the surface roughness Ra of the rough surface RS changed. Will be described with reference to FIG. In addition, the metal halide lamp used for the test is mercury-free, and its main specifications are as follows. The diameter of the base end of the electrode is 0.3 mm, the distance between the electrodes is 4.2 mm, the sealing metal foil is 7.0 mm in length, 1.5 mm in width, and 20 μm in thickness. The surface roughness Ra of the rough surface RS was determined by measuring the area of 50 μm ^{2 on} the surface of the sealing metal foil 3.

表１から理解できるように、粗面ＲＳの表面粗さＲａが０．４μｍ以上であれば、ＥＵ定格モードでリークしないメタルハライドランプを得ることができる。

As can be understood from Table 1, when the surface roughness Ra of the rough surface RS is 0.4 μm or more, a metal halide lamp that does not leak in the EU rated mode can be obtained.

  FIG. 6 is a graph showing the lighting time when a crack leak occurs in any one of the 12 metal halide lamps in Table 1 when the EU mode test is performed. If the surface roughness Ra is 0.4 μm or more, no leakage occurs in the above mode until 2000 hours. Moreover, if Ra is 0.7 μm or more, a metal halide lamp can be obtained in which no leakage occurs up to 2500 hours, and further, if Ra is 1.7 μm or more, no leakage occurs up to 2700 hours.

  Hereinafter, another embodiment for carrying out the metal halide lamp of the present invention will be described with reference to FIGS. In each figure, the same parts as those in FIGS.

FIG. 7 is an enlarged schematic sectional view showing the shape of a groove formed by laser processing in the second embodiment for implementing the metal halide lamp of the present invention. In this embodiment, in FIG. 7A, the arrangement pitch of the grooves G by laser processing is changed, for example, it is dense at the center and becomes sparse as it approaches both side edges.
Further, in FIG. 7B, the depth of the groove of the rough surface RS made of the groove G formed by laser processing is changed, for example, deeper in the central portion and shallower as it approaches both side edges.

    FIG. 8 is a front view showing a surface pattern of grooves formed by laser processing on the surface of the sealed metal foil in the third embodiment for implementing the metal halide lamp of the present invention. In this embodiment, the surface pattern of the rough surface RS formed by the grooves G by laser processing is formed in a mesh shape.

    FIG. 9 is a front view showing a surface pattern of grooves formed by laser processing on the surface of the sealed metal foil in the fourth embodiment for implementing the metal halide lamp of the present invention. In the present embodiment, the surface pattern of the rough surface RS formed by the spot G ′ formed by laser processing is formed in a dotted pattern.

The side view which shows the metal halide lamp for motor vehicle headlamps as a 1st form for implementing the metal halide lamp of this invention Similarly, an enlarged front view of the sealed metal foil Similarly, an enlarged cross-sectional view of the sealing metal foil Schematic enlarged cross-sectional view showing an enlarged shape of a groove formed by laser processing Similarly, a micrograph showing an enlarged rough surface formed by laser processing on the surface of the sealed metal foil The graph which shows the relationship between surface roughness Ra and leak generation time in the 1st form for implementing the metal halide lamp of this invention The typical expanded sectional view which expands and shows the shape of the groove | channel formed by the laser processing in the 2nd form for implementing the metal halide lamp of this invention The front view which shows the surface pattern of the groove | channel formed in the surface of the sealing metal foil in the 3rd form for implementing the metal halide lamp of this invention by laser processing The front view which shows the surface pattern of the disperse | distributed spot formed in the surface of the sealing metal foil in the 4th form for implementing the metal halide lamp of this invention by laser processing

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Translucent airtight container, 1a ... Enclosing part, 1b ... Sealing part, 1c ... Internal space, 2 ... Electrode, 3 ... Sealing metal foil, 4A, 4B ... External lead wire, 5 ... Reduced diameter part, G ... grooves formed by laser processing, IT ... arc tube, MHL ... metal halide lamp, OT ... outer tube, RS ... rough surface

Claims (4)

A translucent airtight container made of quartz glass provided with an enclosing portion having a discharge space therein and a sealing portion connected to the enclosing portion;
An electrode sealed in the discharge space of the translucent airtight container;
A discharge medium containing at least a luminescent metal halide and a rare gas and enclosed in a discharge space of a light-transmitting hermetic vessel;
Is connected to the proximal end of the electrode is hermetically in the sealing portion of the light-transmissive airtight envelope, the surface of the sealed metal foil by forming a plurality of spots having a recess with a laser on a surface by irradiating a plurality of times a sealed metal foil rough surface to have been formed;
A metal halide lamp characterized by comprising: Rough formed on the surface of the sealed metal foil has a surface roughness Ra ([mu] m) is a formula 0.4 ≦ Ra, Rz (μm) is a formula 1.0 ≦ Rz ≦ 7.0, respectively satisfied The metal halide lamp according to claim 1. Rough surface formed on the surface of the sealed metal foil, according to claim 1 or 2 wherein the metal halide lamp characterized Rukoto such a plurality of grooves parallel to the electrode axis. 4. The metal halide lamp according to claim 1, wherein a rough surface is not formed on a knife edge portion at a side edge of the sealing metal foil.

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