Field
[0001] Embodiments described herein relate to a discharge lamp and a manufacturing method
for the discharge lamp.
Background
[0002] A discharge lamp is a lamp comprised of an electrode mount sealed by a seal section
of an arc tube including the arc tube and the seal section. The electrode mount is
configured by a metal foil and an electrode. The metal foil and the electrode can
be welded by laser irradiation. In the electrode mount in which the metal foil and
the electrode are joined by the laser welding, a deficiency of disjoining of the metal
foil and the electrode occurs, and thus improvement in joining strength is demanded.
Advantageous Effect of Invention
[0004] According to the present invention, it is possible to provide a discharge lamp excellent
in joining strength and a manufacturing method for the discharge lamp.
Brief Description of Drawings
[0005]
FIG. 1 is a diagram showing a discharge lamp in a first embodiment.
FIG. 2 is a sectional view showing the discharge lamp in the first embodiment.
FIG. 3 is a diagram showing a state in which a metal foil of the discharge lamp is
viewed from a second surface side in the first embodiment.
FIG. 4 is an enlarged view showing a range A shown in FIG. 3.
FIGS. 5A and 5B are sectional views showing an electrode mount in the first embodiment.
FIG. 6 is a diagram showing a relation between a disjoining occurrence ratio and L1/L2
of the discharge lamp in the first embodiment.
FIG. 7 is a diagram showing a manufacturing method for the electrode mount in the
first embodiment.
FIGS. 8A and 8B are explanatory diagrams showing laser irradiation of the electrode
mount in the first embodiment.
FIGS. 9A and 9B are diagrams showing another example of the electrode mount.
FIGS. 10A and 10B are diagrams showing another example of the electrode mount.
Description of Embodiments
[0006] According to one embodiment, a discharge lamp includes a light-emitting section,
a seal section, and an electrode mount. The light-emitting section includes a discharge
space in which metal halide is encapsulated. The seal section is formed at an end
portion of the light-emitting section. The electrode mount includes a metal foil including
first and second surfaces located on the front and the back and an electrode connected
to the metal foil. A welding mark is formed such that the first surface and at least
a part of the electrode overlap each other. The welding mark has an elliptical shape
long in the axial direction of the electrode when viewed from the second surface side.
A ratio L1/L2 of a first length L1 in the axial direction and a second length L2 in
a direction orthogonal to the axial direction is in a relation of 1.08≤L1/L2≤1.56.
[0007] According to the embodiment, it is possible to provide a discharge lamp excellent
in joining strength and a manufacturing method for the discharge lamp.
A discharge lamp according to an embodiment explained below includes a light-emitting
section 11, seal sections 12, and electrode mounts 3. The light-emitting section 11
includes a discharge space 111 in which metal halide is encapsulated. The seal sections
12 are formed at end portions of the light-emitting section 11. The electrode mounts
3 include metal foils 31 including first surfaces 311 and second surfaces 312 located
in the front and the back and electrodes 32 connected to the metal foils 31. Welding
marks 36 are formed such that at least parts of the first surfaces 311 and the electrodes
32 overlap each other. The welding marks 36 have an elliptical shape long in the axial
direction of the electrodes 32 when viewed from the second surfaces 312 side. A ratio
L1/L2 of a first length L1 in the axial direction and a second length L2 in a direction
orthogonal to the axial direction is in a relation of 1.08≤L1/L2≤1.56.
[0008] In the discharge lamp according to the embodiment explained below, a ratio L2/W of
the second length L2 and a diameter W of the electrodes 32 is in a relation of 0.3≤L2/W≤0.9.
[0009] In the discharge lamp according to the embodiment explained below, the diameter W
of the electrodes 32 is 0.2 mm to 0.4 mm.
[0010] In the discharge lamp according to the embodiment explained below, the welding marks
36 are formed to extend from the metal foils 31 side to the insides of the electrodes
32. The center lines of the welding marks 36 incline with respect to the perpendicular
direction of the second surfaces 312.
[0011] In a manufacturing method for the discharge lamp according to the embodiment explained
below, the metal foils 31 and the electrodes 32 are arranged such that at least parts
of the first surfaces 311 and the electrodes 32 overlap each other. A laser is irradiated
on overlapping portions of the first surfaces 311 and the electrodes 32 from the second
surfaces 312 side along an optical axis inclining with respect to the perpendicular
direction of the metal foils 31 to weld the metal foils 31 and the electrodes 32 to
form the welding marks 36 in which the ratio L1/L2 of the first length L1 in the axial
direction of the electrodes 32 and the second length L2 in the direction orthogonal
to the axial direction is in a relation of 1.08≤L1/L2≤1.56.
First Embodiment
[0012] A first embodiment is explained with reference to FIGS. 1 and 2. FIG. 1 is a diagram
showing a discharge lamp in the first embodiment. FIG. 2 is a sectional view showing
the discharge lamp in the first embodiment. FIG. 3 is a diagram showing a state in
which the metal foil of the discharge lamp in the first embodiment is viewed from
the second surface side.
[0013] The discharge lamp in this embodiment is a metal halide lamp used in a head lamp
for an automobile headlight. The discharge lamp includes an inner tube 1 as an airtight
container. The inner tube 1 has an elongated shape. The light-emitting section 11
having a substantially elliptical shape is formed around the center of the inner tube
1. Tabular seal sections 12 formed by pinch seal are formed at both the ends of the
light-emitting section 11. Cylinder sections 14 are continuously formed at both the
ends of the seal sections 12 by an intercalate section 13. The inner tube 1 is desirably
formed of a material having heat resistance and translucency such as quartz glass.
The seal sections 12 may be formed by shrink seal to be formed in a columnar shape.
[0014] On the inside of the light-emitting section 11, the discharge space 111 having a
substantially columnar shape in the center and having a taper shape toward both the
ends is formed. Metal halide 2 and a rare gas are encapsulated in the discharge space
111. The metal halide 2 is formed of sodium iodide, scandium iodide, zinc iodide,
and indium bromide. Note that the metal halide 2 is not limited to this combination.
For example, halide of tin and cesium may be added.
[0015] As the rare gas, xenon is used. The pressure of the rare gas is 12 atm to 18 atm
and desirably 13 atm to 16 atm. Note that, as the rare gas, a mixed gas obtained by
combining xenon and neon, argon, krypton, or the like can also be used.
[0016] The lamp in this embodiment is a mercury-free discharge lamp. The "mercury-free"
means that the lamp does not substantially include mercury.
[0017] The electrode mounts 3 are respectively sealed by the seal sections 12 formed on
both the sides of the light-emitting section 11. The electrode mounts 3 are configured
by the metal foils 31, the electrodes 32, coils 33, and lead wires 34.
[0018] The metal foil 31 is a thin plate-like member made of, for example, molybdenum. The
metal foil 31 includes the flat first surface 311 and the flat second surface 312
on the front and the back. Both the ends in the latitudinal direction of the flat
surfaces are formed in a knife edge shape gradually reduced in thickness. In this
embodiment, rough surfaces 313 are formed on half surfaces (excluding overlapping
portions of the ends and the electrodes 32) of the first surface 311 and the second
surface 312 on a side to which the electrodes 32 are connected. FIG. 4 is an enlarged
view showing a range A shown in FIG. 3. As shown in FIG. 4, the rough surface 313
is formed from a plurality of circular recesses 3131. The recesses 3131 are, for example,
non-penetrating semicircular hollows having a diameter of 18 µ and depth of 3 µm.
The recesses 3131 can be formed by irradiating a YAG laser.
[0019] The electrodes 32 are bar-like members made of so-called thoriated tungsten obtained
by, for example, doping thorium oxide in tungsten. One ends of the electrodes 32 are
connected to end portions on the light-emitting section 11 side of the metal foils
31. The other ends of the electrodes 32 project into the discharge space 111, and
the distal end portions of the other ends of the electrodes 32 are opposed to each
other while keeping a predetermined distance. The diameter W is 0.2 mm to 0.4 mm.
If the diameter W is smaller than 0.2 mm, the temperature of the electrodes 32 during
lighting rises and scattering (spattering) of an electrode substance to the discharge
space 111 increases. Therefore, a luminous flux maintenance factor during lighting
decreases and a life characteristic is deteriorated. If the diameter W exceeds 0.4
mm, distortion (stress) of sealing portions of the inner tube 1 and the electrodes
32 increases. Therefore, it is likely that a crack occurs in the inner tube 1 during
discharge lamp manufacturing or during lighting to cause non-lighting. In this embodiment,
the diameter W is, for example, 0.38 mm. Note that, in the case of a use in an automobile
headlight, the electrodes 32 are preferably positioned in a range in which the distance
between the distal ends of the electrodes 32 is 3.7 mm to 4.4 mm when observed through
an outer tube 5.
[0020] The coils 33 are metal wires made of, for example, doped tungsten. The coils 33 are
wound in a spiral shape around the axes of shaft sections of the electrodes 32 sealed
by the seal sections 12.
[0021] The lead wires 34 are metal wires made of, for example, molybdenum. One end of the
lead wires 34 is connected to the end portions of the metal foils 31 on the opposite
side of the electrode connection side from the light-emitting section 11. The other
end is extended substantially in parallel to a tube axis to the outside of the inner
tube 1. One end of an L-shaped support wire 35 made of, for example, nickel is connected
to, by laser welding, the lead wire 34 extended to the front end side of the lamp,
that is, a far side from a socket 6. In the support wire 35, a sleeve 4 made of, for
example, ceramic is attached to a part extending in parallel to the inner tube 1.
[0022] On the outer side of the inner tube 1 configured as explained above, the cylindrical
outer tube 5 is provided substantially concentrically with the inner tube 1 to cover
the light-emitting section 11. Connection of the inner and outer tubes is performed
by welding the ends of the outer tube 5 near the cylinder section 14 of the inner
tube 1. Gas is encapsulated in a closed space 51 formed between the inner tube 1 and
the outer tube 5. As the gas, dielectric barrier dischargeable gas, for example, one
kind of gas selected from neon, argon, xenon, and nitrogen or mixed gas thereof can
be used. The pressure of the gas is desirably 0.3 atm or less, in particular, 0.1
atm or less. Note that the outer tube 5 is desirably formed of a material having a
coefficient of thermal expansion close to the coefficient of thermal expansion of
the inner tube 1 and having ultraviolet blocking properties. For example, quartz glass
added with oxide of titanium, cerium, aluminum, or the like can be used.
[0023] The socket 6 is connected to one end of the inner tube 1 to which the outer tube
5 is connected. The connection is performed by attaching a metal band 71 to the outer
circumferential surface of the outer tube 5 and gripping the metal band 71 with four
metal tongue pieces 72 formed to be projected from the socket 6. A bottom terminal
81 is formed in the bottom of the socket 6 and a side terminal 82 is formed on a side
of the socket 6. The lead wire 34 and the support wire 35 are respectively connected
to the bottom terminal 81 and the side terminal 82.
[0024] The discharge lamp (a foil seal lamp) configured as explained above is connected
to a lighting circuit (not shown in the figure) to set the bottom terminal 81 on a
high voltage side and set the side terminal 82 on a low voltage side. In this embodiment,
the discharge lamp is lit at lamp power of 75 W during a start and 35 W during stable
lighting.
[0025] The connection of the metal foil 31 and the electrode 32 is explained. In this embodiment,
the metal foil 31 and the electrode 32 are welded in two places in a state in which
the first surface 311 and at least a part of the electrode 32 are arranged to be overlapped
each other. FIGS. 5A and 5B are sectional views showing the electrode mount in the
first embodiment. As shown in FIGS. 5A and 5B, in an overlapping portion by the welding,
the welding marks 36 extending from the metal foil 31 side to the inside of the electrode
32 and recesses 37 are respectively formed in welded parts. The welding marks 36 are
formed in a substantially elliptical cone shape. When viewed from the second surface
312 side, as shown in FIG. 4, the welding marks 36 are formed in an elliptical shape
long in the axial direction of the electrode 32. As the elliptical shape, the first
length L1 in the axial direction only has to be larger than the second length L2 in
the direction orthogonal to the axial direction and a contour line only has to be
formed of a curved line. The elliptical shape includes a substantially elliptical
shape. In the welding marks 36, the ratio L1/L2 of the first length L1 and the second
length L2 is in a relation of Expression (1) below.
[0026] FIG. 6 is a diagram showing a relation between a disjoining occurrence ratio and
L1/L2 of the discharge lamp in the first embodiment. As shown in FIG. 6, the disjoining
occurrence ratio (%) greatly changes if the ratio L1/L2 of the welding marks 36 is
between 1.00 and 1.08. If the ratio L1/L2 of the welding marks 36 is 1.00 or less
(the shape of the welding marks 36 viewed from the second surface 312 side is a circular
shape or an elliptical shape long in the direction orthogonal to the axial direction
of the electrode 32), compared with if the ratio L1/L2 is 1.08, the disjoining occurrence
ratio suddenly increases (in the figure, about nine times). Therefore, by setting
the ratio L1/L2 of the welding marks 36 to 1.08 or more, it is possible to markedly
suppress disjoining compared with if the ratio L1/L2 is smaller than 1.00. Similarly,
the disjoining occurrence ratio (%) greatly changes if the ratio L1/L2 of the welding
marks 36 is between 1.56 and 1.64. If the ratio L1/L2 of the welding marks 36 is 1.64
or more (the shape of the welding marks 36 when viewed from the second surface 312
side is an elliptical shape considerably longer in the axial direction than in the
direction orthogonal to the axial direction of the electrode 32), compared with if
the ratio L1/L2 is 1.56 (the first length L1 is about 1.5 times as large as the second
length L2), the disjoining occurrence ratio suddenly increases (in the figure, about
six times). Therefore, by setting the ratio L1/L2 of the welding marks 36 to 1.56
or less, it is possible to markedly suppress disjoining compared with if the ratio
L1/L2 is 1.64 or more. In this embodiment, the ratio L1/L2 is 1.32 (the first length
L1=330µm and the second length L2=250µm). The ratio L1/L2 is more preferably 1.16
to 1.48.
[0027] In the welding marks 36, a ratio L2/W of the second length L2 and the diameter W
of the electrode 32 is in a relation of Expression (2) below. If the ratio L2/W is
smaller than 0.3, welding strength decreases and a defective rate of disjoining or
the like increases. If the ratio L2/W exceeds 0.9, the electrode 32 and the metal
foil 31 are welded in a state in which a gap occurs between the electrode 32 and the
metal foil 31. Therefore, only the metal foil 31 is melted by heating during the welding
and a defect such as perforation occurs. In this embodiment, the ratio L2/W is, for
example, 0.66.
[0028] The shape in cross sections of the welding marks 36 along the latitudinal direction
of the metal foil 31 is, as shown in FIG. 5A, a substantially triangular shape, center
lines B1-B1' and B2-B2' (lines passing near a vertex of the welding mark 36 located
on the most inner side of the electrode 32 and dividing the area of the welding mark
36 substantially into two) of which are respectively substantially parallel (including
parallel) to the perpendicular direction of the second surface 312. The shape in cross
sections of the welding marks 36 along the longitudinal direction of the metal foil
31 is, as shown in FIG. 5B, a substantially triangular shape, the center lines B1-B1'
and B2-B2' of which are substantially parallel to the perpendicular direction of the
second surface 312. That is, in this embodiment, inclination angles α1 and α2 of the
center lines are, for example, 0°. Note that the metal foil 31 and the lead wire 34
have the same structure.
[0029] A welding method for the metal foil 31 and the electrode 32 is explained. FIG. 7
is a diagram showing a manufacturing method for the electrode mount in the first embodiment.
FIGS. 8A and B are explanatory diagrams showing laser irradiation on the electrode
mount in the first embodiment. First, as shown in FIG. 7, the electrode 32 and the
lead wire 34 are arranged on a jig 91 to be fit in a groove 911. Subsequently, the
metal foil 31 is arranged such that the first surface 311 overlaps a part of the electrode
32 and a part of the lead wire 34. Thereafter, pressing members 92 are arranged at
four corners of the second surface 312 to fix the metal foil 31. As shown in FIGS.
8A and 8B, a laser is irradiated on an overlapping portion of the metal foil 31 and
the electrode 32 from the second surface 312 side by a laser irradiating unit 93 of
a YAG laser irradiating apparatus. The laser irradiating unit 93 irradiates the laser
with optical axes D1-D1' and D2-D2' in welding parts (positions where the welding
marks 36 are formed) set substantially parallel to the perpendicular direction of
the second surface 312 when viewed from the longitudinal direction of the metal foil
31 as shown in FIG. 8A and set substantially parallel to the perpendicular direction
of the second surface 312 when viewed from the latitudinal direction of the metal
foil 31 as shown in FIG. 8B. In this embodiment, optical axis inclination angles β1
and β2 of the optical axes are, for example, 0°. This laser irradiation process is
performed a plurality of times, in this embodiment, twice with a position of the laser
irradiation changed. The two welding marks 36 are formed in the overlapping portion
of the metal foil 31 and the electrode 32. The laser irradiating unit 93 can change
an irradiation range of the laser to not only a circular shape but also an elliptical
shape. The laser irradiating unit 93 irradiates the laser to the overlapping portion
of the metal foil 31 and the electrode 32 from the second surface 312 side in an irradiation
range in which the ratio L1/L2 of the welding marks 36 is in the relation of Expression
1 above.
[0030] The center lines B1-B1' and B2-B2' of the welding marks 36 may incline with respect
to the perpendicular direction of the second surface 312. FIGS. 9A and 9B are diagrams
showing another example of the electrode mount. For example, the shape in the cross
sections of the welding marks 36 along the latitudinal direction of the metal foil
31 is, as shown in FIG. 9A, a substantially triangular shape, the center lines B1-B1'
and B2-B2' of which are respectively substantially perpendicular to the second surface
312. The shape in the cross sections of the welding marks 36 along the longitudinal
direction of the metal foil 31 is, as shown in FIG. 9B, a substantially triangular
shape, the center lines B1-B1' and B2-B2' of which respectively inclined with respect
to the perpendicular direction of the second surface 312. It is possible to improve
joining strength compared with if the center lines B1-B1' and B2-B2' of the welding
marks 36 are substantially parallel to the perpendicular direction of the second surface
312. The inclination angles α1 and α2 of the center lines are, for example, 35°. Note
that, in order to further improve the joining strength, the inclination angles α1
and α2 are suitably 10° to 50°. The vertexes of the recesses 37 deviate in a direction
opposite to a direction in which the welding marks 36 incline. If the welding marks
36 are formed with the center lines B1-B1' and B2-B2' inclining with respect to the
perpendicular direction of the second surface 312, the laser is irradiated to be substantially
orthogonal to the second surface 312 when viewed from the longitudinal direction of
the metal foil 31 and incline with respect to the perpendicular direction of the second
surface 312 when viewed from the latitudinal direction of the metal foil 31. The optical
axis inclination angles β1 and β2 of the optical axes are, for example, 35°. Note
that, in order to further improve the joining strength, the optical axis inclination
angles β1 and β2 are suitably 10° to 50°. Note that, if the irradiation range of the
laser by the laser irradiating unit 93 is circular, the ratio L1/L2 of the welding
marks 36 changes according to inclination degrees of the optical axes D1-D1' and D2-D2'
in the welding parts with respect to the perpendicular direction of the second surface
312. Therefore, the optical axes D1-D1' and D2-D2' in the welding parts are determined
such that the ratio L1/L2 is in the relation of Expression 1 above.
[0031] In this way, by obliquely irradiating the laser on the overlapping portion of the
metal foil 31 and the electrode 32, the shape of the welding marks 36 viewed from
the second surface 312 side is the elliptical shape. Therefore, the size of the welding
marks 36 increases compared with circular welding marks formed if the laser is perpendicularly
irradiated on the second surface 312 (the conventional method). If the size increases,
a contact area of the electrode 32 and the welding mark 36 increases. Therefore, it
is possible to increase the joining strength of the metal foil 31 and the electrode
32.
[0032] Note that, if it is desired to increase the joining strength of the metal foil 31
and the electrode 32 with the conventional method, in general, a method of increasing
the power of the laser is used. In the case of this method, damage to the electrode
increases to cause crystal coarsening and fragility of the electrode. It is likely
that an electrode break due to excessively large height h of the welding marks 36
inside the electrode 32 occurs. There is also a method of increasing an irradiation
diameter of the laser. However, since a usable irradiation diameter of the laser depends
on the diameter of the electrode, the irradiation diameter of the laser cannot be
increased in some case. On the other hand, with the method in this embodiment, it
is possible to increase the joining strength of the metal foil 31 and the electrode
32 while suppressing the occurrence of the problems explained above without increasing
the power of the laser.
[0033] In the first embodiment, the laser is irradiated on the overlapping portion of the
metal foil 31 and the electrode 32 from the second surface 312 side in the state in
which the laser is inclined with respect to the perpendicular direction of the second
surface 312 to weld the metal foil 31 and the electrode 32. Consequently, it is possible
to form, in the overlapping portion, the welding marks 36, the shape of which when
viewed from the second surface 312 side is the elliptical shape and the center lines
B1-B1' and B2-B2' of which incline with respect to the perpendicular direction of
the second surface 312. Therefore, it is possible to increase the joining strength
of the metal foil 31 and the electrode 32 without increasing the power of the laser.
[0034] The present invention is not limited to the embodiment. Various modifications are
possible.
[0035] For example, the material of the metal foil 31 is not limited to molybdenum. The
effect of the present invention can also be obtained if the metal foil 31 is formed
of rhenium molybdenum, tungsten, rhenium tungsten, and the like. The material is not
particularly limited. A thin film or a layer may be formed on the surface of the material.
[0036] The shape of the electrode 32 may be a stepped shape, the diameter of the distal
end of which is larger than the diameter of the proximal end, a shape, the distal
end of which is a spherical shape having size of the diameter, and a shape, one electrode
diameter and the other electrode diameter of which are different. The electrode material
may be, for example, pure tungsten, doped tungsten obtained by doping a very small
amount of aluminum, silicon, or potassium in tungsten, or rhenium tungsten obtained
by doping rhenium in tungsten.
[0037] FIGS. 10A and 10B are diagrams showing another example of the electrode mount. The
shape in the cross sections of the welding marks 36 along the latitudinal direction
of the metal foil 31 may be, as shown in FIG. 10A, a shape, the center lines B1-B1'
and B2-B2' of which respectively incline with respect to the perpendicular direction
of the second surface 312. As shown in FIG. 10B, the shape in a cross section of a
welding mark 361 along the longitudinal direction of the metal foil 31 may be a shape,
the center line B1-B1' of which inclines to the light-emitting section 11 side with
respect to the perpendicular direction of the second surface 312. The shape in a cross
section of a welding mark 362 along the longitudinal direction of the metal foil 31
may be a shape, the center line B2-B2' of which inclines to the lead wire 34 side
with respect to the perpendicular direction of the second surface 312. In these shapes,
since the welding marks 361 and 362 hold the electrode 32, it is possible to further
suppress the disjoining.
[0038] The shape in the cross sections of the welding marks 36 along the latitudinal direction
of the metal foil 31 may be a shape, the center lines B1-B1' and B2-B2' of which respectively
incline to cross across the perpendicular direction of the second surface 312. In
the shape in the cross sections of the welding marks 36 along the longitudinal direction
of the metal foil 31, the inclination angles α1 and α2 may be different.
[0039] While certain embodiments have been described, these embodiments have been presented
by way of example only, and are not intended to limit the scope of the inventions.
Reference Signs List
[0040]
- 1
- inner tube
- 11
- light-emitting section
- 12
- seal section
- 3
- electrode mount
- 31
- metal foil
- 32
- electrode
- 36
- welding mark
1. Entladungslampe, umfassend:
einen lichtemittierenden Abschnitt (11), der einen Entladungsraum aufweist, in dem
Metallhalogenid eingekapselt ist;
einen Dichtungsabschnitt (12), der an einem Endabschnitt des lichtemittierenden Abschnitts
ausgebildet ist; und
eine Elektrodenhalterung (3), die eine Metallfolie (31) mit einer ersten und zweiten
Oberfläche, die sich auf einer Vorderseite und einer Rückseite befinden, und eine
Elektrode (32), die mit der Metallfolie verbunden ist, aufweist, wobei
eine Schweißmarke (36) derart ausgebildet ist, dass die erste Oberfläche und mindestens
ein Teil der Elektrode einander überlappen,
die Schweißmarke, von der Seite der zweiten Oberfläche gesehen, eine elliptische Form,
lang in einer axialen Richtung der Elektrode, aufweist und
ein Verhältnis L1/L2 einer ersten Länge L1 in der axialen Richtung und einer zweiten
Länge L2 in einer Richtung rechtwinklig zu der axialen Richtung in einer Beziehung
des nachstehenden Ausdrucks (1) steht.
2. Lampe nach Anspruch 1, wobei
ein Verhältnis L2/W zwischen der zweiten Länge L2 und einem Durchmesser W der Elektrode
in einer Beziehung des nachstehenden Ausdrucks (2) steht.
3. Lampe nach Anspruch 1, wobei ein Durchmesser W der Elektrode 0,2 mm bis 0,4 mm beträgt.
4. Lampe nach Anspruch 1, wobei die Schweißmarke dazu ausgebildet ist, sich von der Metallfolienseite
zu einer Innenseite der Elektrode zu erstrecken, und eine Mittellinie der Schweißmarke
bezogen auf eine rechtwinklige Richtung der zweiten Oberfläche geneigt ist.
5. Herstellungsverfahren für eine Entladungslampe, aufweisend:
einen lichtemittierenden Abschnitt, der einen Entladungsraum aufweist, in dem Metallhalogenid
eingekapselt ist;
einen Dichtungsabschnitt, der an einem Endabschnitt des lichtemittierenden Abschnitts
ausgebildet ist; und
eine Elektrodenhalterung, die eine Metallfolie mit einer ersten und zweiten Oberfläche,
die sich auf einer Vorderseite und einer Rückseite befinden, und eine Elektrode, die
mit der Metallfolie verbunden ist, aufweist,
wobei das Herstellungsverfahren umfasst: Anordnen der Metallfolie und der Elektrode
derart, dass die erste Oberfläche und mindestens ein Teil der Elektrode einander überlappen
und danach Bestrahlen eines überlappenden Abschnitts der ersten Oberfläche und der
Elektrode mit einem Laser von der Seite der zweiten Oberfläche her entlang einer optischen
Achse, die bezogen auf eine rechtwinklige Richtung der Metallfolie geneigt ist, und
Schweißen der Metallfolie und der Elektrode, um eine Schweißmarke auszubilden, wobei
ein Verhältnis L1/L2 einer ersten Länge L1 in einer axialen Richtung der Elektrode
und einer zweiten Länge L2 in einer Richtung rechtwinklig zu der axialen Richtung
derselben in einer Beziehung des nachstehenden Ausdrucks (3) steht.