JPH0765790A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To eliminate a fear of damaging the inner surface of an outer tube by the tongue piece of a plate supporting a translucent tube body for outer tube protection, or a collision of the translucent tube body receiving a shock to the outer tube. CONSTITUTION:This metal halide lamp is provided with a luminous tube 1 having a pair of electrodes at bothe ends, and mercury, a rare gas for starting, and a metal halide are sealed; a translucent tube body 3 to surround the luminous tube 1; a pair of plates 5 to support the luminous tube 1 by its both ends by blocking both openings of the tube body 3; and an outer tube 4 to be an envelope. Each plate 5 has the plate surface 6 with the maximum outer diameter being A; and an elastic tongue piece 7 being erected without projecting from the plate surface 6 to the side, and holding the tube body 3 by its end. When the inner diameter of the outer tube 4 is made B, the relation B-5mm<=A<=B-1 mm is set. A reflected part may be formed at the outer peripheral edge of the plates 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal halide lamp.

[0002]

2. Description of the Related Art Conventionally, metal halide lamps have been used for outdoor lighting, but in recent years, compact, straight tube type lamps have come to be used for indoor lighting in stores and the like. Since the arc tube of the metal halide lamp is made of quartz glass, it easily reacts with the metal halide in the arc tube and deteriorates. Therefore, if the lamp is used for a long period of time, the arc tube is damaged, although it is rare.

If the quartz pieces scattered by the breakage of the arc tube hit the outer tube as the envelope, there is a risk of damaging the outer tube. Therefore, the outer surface of the outer tube is generally covered with a fluororesin film. .

However, in a compact straight tube type metal halide lamp, the temperature of the outer bulb when the lamp is lit exceeds the allowable temperature range of the fluororesin coating, so that the fluororesin coating cannot be attached to the outer bulb. Therefore, a front protection plate made of tempered glass is installed on the lamp side to prevent scattering of the outer tube fragments, but there are various restrictions on the side of the lamp, so a compact body with an outer tube damage prevention function is provided. The appearance of new metal halide lamps is desired.

In the metal halide lamp disclosed in JP-A-2-230655, the arc tube is surrounded by a transparent cylinder. In this case, since the translucent cylinder is interposed between the arc tube and the outer tube, the risk of damaging the outer tube by the broken pieces of the arc tube is eliminated.

[0006]

However, in order to support the arc tube and the light-transmissive tube inside the outer tube, Japanese Patent Laid-Open No. 2-2306 has been proposed.
If a metal plate as disclosed in Japanese Patent Publication No. 55 is used, even if a seismic support effect is obtained, the outer tongue extending from the metal plate may instead damage the outer tube. That is, the metal plate has a plurality of elastic tongues for supporting the translucent cylinder, and a part of the tongues is projected to the outer tube side and elastically contacts the inner surface of the outer tube. During the lamp manufacturing process in which the electrode assembly is inserted into the outer tube, the inner surface of the outer tube is likely to be damaged by the tongue portion protruding toward the outer tube.

Therefore, an object of the present invention is to provide a compact metal halide lamp which is provided with a plate for supporting an arc tube and a light-transmissive cylinder surrounding the arc tube and which does not damage the inner surface of the outer tube during the lamp manufacturing process. To do.

[0008]

According to the present invention, in order to achieve the above object, an arc tube having a pair of electrodes at both ends and containing mercury, a rare gas for starting and a metal halide. A translucent cylinder surrounding the arc tube, a pair of plates for closing the open ends of the tube to support the arc tube at both ends thereof, and an outer tube as an envelope. And the plate has a plate surface with a maximum outer diameter of A, and
When the inner diameter of the outer tube is B, B-5 mm ≤ A ≤ B-, which has an elastic tongue that stands up without laterally protruding from the plate surface and clamps the tubular body at its end. A metal halide lamp having a size of 1 mm is provided.

[0009]

According to the present invention, the plate for supporting the arc tube and the light-transmissive cylinder has an elastic tongue which holds the cylinder at its end. However, this tongue is lateral to the plate surface of the plate. Since it stands up without overhanging, there is no risk of the inner surface of the outer tube being damaged by the tongue piece during the lamp manufacturing process in which the electrode structure is inserted into the outer tube, and the insertion work can be facilitated. .

Generally, in a straight-tube type metal halide lamp, the distance between the arc tube and the outer tube is narrow, so that the distance between the light-transmissive cylinder provided between the two and the outer tube is also narrow.
For this reason, the cylindrical body is likely to collide with the outer tube when receiving an impact, and the risk of damage to the outer tube is rather increased.

In the present invention, when the maximum outer diameter of the plate is A and the inner diameter of the outer tube is B, B-5 mm≤A≤B-1
Set to mm. Since the average gap between the outer edge of the plate and the outer tube is 0.5 mm to 2.5 mm,
Even if a strong impact is applied to the lamp due to a drop or the like, the outer peripheral edge of the plate only comes into contact with the inner surface of the outer tube, so that the translucent cylindrical body can be prevented from directly colliding with the outer tube. In other words, damage to the outer tube due to direct collision of the translucent cylinder with the outer tube,
It will be prevented by the outer periphery of the plate.

[0012]

An embodiment of the present invention will be described below with reference to the drawings.

The metal halide lamp shown in FIG.
An arc tube 1 of W type, which is made of a quartz glass tube having an inner diameter of 19 mm, has a pair of electrodes 2 and 2 at both ends thereof, and has a rare gas for starting, 10000 Pascal argon, and 25 m.
g of mercury and metal halide (1.7 mg of Tl I,
6.2 mg Dy I ₃ and 2.1 mg Cs I) are encapsulated. The quartz glass translucent cylinder 3 surrounding the arc tube 1 has a double tube structure, and the arc tube 1 and the translucent cylinder 3 are coaxial with each other in a straight tube-shaped outer tube 4 which is an envelope. It is arranged in a way.

Each of the pair of metal plates 5 and 5 for closing both open ends of the light-transmissive cylinder 3 has a plate surface 6 having a maximum outer diameter A, and the plate surfaces 6 project laterally from the plate surface 6. A plurality of elastic tongues 7 and 7 that stand upright sandwich the translucent cylinder 3 at its end. Each plate 5 has a central hole 8 as shown in FIG. 2, and the lead terminal 9 of the arc tube 1 is provided in the central hole 8.
However, it is inserted from ceramics or the like through the insulating tube 10, and thereby the arc tube 1 is supported by the pair of plates 5 and 5. Reference numeral 11 is a stem, and 12 is a base.

When the inner diameter of the outer tube 4 is B, the maximum outer diameter A of each plate 5 is set to B-5 mm≤A≤B-1 mm. That is, since the maximum outer diameter A of the plate 5 holding the translucent cylinder 3 is set as large as possible, the outer peripheral edge of the plate 5 projects to the outer tube 4 side, and the lamp is strongly impacted by dropping or the like. Even if it receives, the translucent cylinder 3 does not directly collide with the outer tube 4.

Even if the maximum outer diameter A of the plate 5 is larger than the outer diameter of the translucent cylinder 3, if the maximum outer diameter A of the plate 5 is too smaller than the inner diameter of the outer tube 4, the plate 5 will be There is a risk of damaging the outer tube 4 by the impact that collides with the outer tube 4. If the maximum outer diameter A of the plate 5 is substantially the same as the inner diameter of the outer tube 4, there is a risk that the inner surface of the outer tube 4 will be damaged by the outer peripheral edge of the plate 5 during the lamp manufacturing process. In addition, there is a risk that the plate 5 whose temperature has risen when the lamp is turned on contacts the outer tube 4 due to thermal expansion and is deformed.

By setting B-5 mm≤A≤B-1 mm, there is no risk of damaging the outer tube 4, and a satisfactory outer tube damage prevention effect can be obtained even with a drop impact.

In the embodiment shown in FIG. 3, the plate 5
The folded portion 5a is formed on the outer peripheral edge of the. in this case,
The risk of damaging the inner surface of the outer tube 4 by the outer peripheral edge of the plate 5 can be almost completely eliminated.

In the above-described embodiment, both ends of the arc tube 1 are supported by the plate 5 via the insulating tube 10. However, the lead terminals 9 of the arc tube 1 are directly connected to the plate 5 and supported. May be Further, the plate 5 is not limited to being made of metal. Further, the plate 5 does not have to be a perfect circle as long as it satisfies the above-described dimensional condition, and the same effect as described above can be obtained even if the plate 5 is partially round and has a substantially circular shape.

[0020]

As described above, according to the present invention, since the arc tube is surrounded by the light-transmissive cylinder, the risk of destroying the outer tube due to breakage of the arc tube can be eliminated. Further, since the elastic tongue of the plate supporting the translucent cylinder does not have a laterally protruding portion, there is no risk of the inner surface of the outer tube being scratched by the tongue during the lamp manufacturing process. Moreover, even if a shock is applied to the lamp, the outer peripheral edge of the plate only abuts on the inner peripheral surface of the outer tube, so that the outer tube is damaged by the light-transmissive cylinder directly colliding with the outer tube. In particular, the present invention can be applied to a compact straight tube metal halide lamp to obtain excellent practical effects.

[Brief description of drawings]

FIG. 1 is a side sectional view of a metal halide lamp according to an embodiment of the present invention.

FIG. 2 is a perspective view of a metal halide lamp plate according to an embodiment of the present invention.

FIG. 3 is a side sectional view of a metal halide lamp according to another embodiment of the present invention.

[Explanation of symbols]

 1 arc tube 2 electrode 3 translucent cylinder 4 outer tube 5 plate 7 elastic tongue

Claims (2)

[Claims] 1. An arc tube having a pair of electrodes at both ends and containing mercury, a rare gas for starting and a metal halide, a light-transmissive cylinder surrounding the arc tube, and this cylinder. Support both ends of the arc tube by closing both open ends of the body 1
The plate has a pair of plates and an outer tube as an envelope, and the plate has a plate surface with a maximum outer diameter of A, and stands up without laterally projecting from the plate surface so that the tubular body has its end. A metal halide lamp having an elastic tongue which is sandwiched by a portion and B-5 mm ≦ A ≦ B-1 mm, where B is the inner diameter of the outer tube. 2. The metal halide lamp according to claim 1, wherein the plate has a folded outer peripheral edge.