JPH04296438A - Small-sized metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To provide a small-sized metal vapor discharge lamp capable of preventing a light emitting tube from being deteriorated due to of an curving. CONSTITUTION:In a small-sized metal vapor discharge lamp where crash sealing portions 2 are formed at both ends of a light emitting tube 1, a metal foil conductor 3 is attached to the crash sealing portion, an electrode 4 and an outside lead wire 5 are connected to the metal foil conductor, and the lamp is lighted with the sealing portions oriented toward the almost horizontal direction, both surfaces of the metal foil conductor sealed in the crash sealing portion are oriented upward and downward, and the base end of the electrode is bonded to the upper surface while the tip end of the electrode is inclined downward. The tip end of the electrode is displaced downward due to a flow of softened glass in the case where the sealing portion is crashed and sealed so that the center of an arc can approximately be brought on the axis of a lamp.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small metal vapor discharge lamp, such as a small metal halide lamp, which is operated horizontally and is sealed at both ends.

0002

[Prior Art] Metal halide lamps have traditionally been widely used as light sources for outdoor lighting, but due to their excellent luminous efficiency and long life, as well as excellent color rendering properties, they have recently been used for indoor lighting in stores, etc., and for liquid crystal projector devices. It has come to be used as a light source for automobiles and vehicle headlights.

[0003] Metal halide lamps used for such purposes are small in size because they must be accommodated in lamps of limited size, and in some cases, they must be used horizontally.

[0004] In other words, metal halide lamps generally have the following characteristics:
A crushed sealing portion is formed at both ends of an arc tube made of quartz glass or the like, a metal foil conductor is sealed to each of these crushed sealing portions, and an electrode and an external lead wire are connected to each of these metal foil conductors, respectively. These electrodes are sealed so as to face each other within the arc tube. In such an arc tube, mercury as a buffer metal, a metal halide as a luminescent metal, and a starting rare gas are sealed. The arc tube is lit horizontally in such a position that the lamp axis passing through the center of the sealing portions at both ends is horizontal, that is, the sealing portions at both ends are oriented in the horizontal direction.

[0005]

[Problem to be Solved by the Invention] However, when such a metal halide lamp is lit horizontally, the arc curves into an arch shape due to gas convection within the arc tube, and the center of the arc approaches the upper side of the wall of the arc tube. can be seen. When the arc approaches the tube wall of the arc tube, the tube wall is overheated and deformed, and the reaction between the metal halide and quartz progresses, resulting in deterioration of the arc tube and a decrease in luminous flux.

In particular, small metal halide lamps are given high power in order to increase their light output and are used under conditions where the tube wall load is high, so the temperature of the arc tube increases significantly, and the progress of deterioration due to the approach of the arc is accelerated. The disadvantage is that it becomes intense.

It is known that in order to prevent this, the tips of the horizontally opposing electrodes may be lowered from the lamp axis. In this way, even if the arc generated between the electrodes is curved, the center of the curve will be exactly aligned with the lamp axis, and the arc will no longer approach the wall of the arc tube.

However, in the past, it was not easy to configure the tips of the horizontally opposing electrodes to be lower than the lamp axis. In particular, when the lamp is small, the sealing portion and the electrodes are also small, making it difficult to control the mounting orientation of the electrodes.

The present invention was made based on the above circumstances, and its purpose is to provide a small metal vapor discharge lamp having a structure that allows the tips of the electrodes to be easily lowered from the horizontal direction. It is something.

0010

[Means for Solving the Problems] The present invention forms crushing sealing parts at both ends of an arc tube, sealing metal foil conductors to these crushing sealing parts, and attaching electrodes and external parts to these metal foil conductors, respectively. In a small metal vapor discharge lamp that is lit with lead wires connected, the electrodes facing each other in the arc tube, and the sealing part facing in a substantially horizontal direction, the lamp is sealed to the crushing sealing part. Both surfaces of the metal foil conductor face in the vertical direction, and by joining the base end of the electrode to the upper surface, the tip of the electrode is slanted downward within the arc tube.

[0011]

[Operation] According to the present invention, when the base end of the electrode is joined to one side of the metal foil conductor and the sealing portion housing the metal foil conductor is crushed and deformed in the direction of both sides of the metal foil conductor, the sealing is completed. Depending on the flow of the overheated and softened meat, the tip of the electrode will be inclined to the opposite side of the metal foil conductor, and therefore the tip of the electrode can be easily tilted to deviate from the horizontal direction to one side. .

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on embodiments shown in the drawings. The drawings show a horizontally lit small metal halide lamp used as a light source for a liquid crystal projector device, with FIG. 1 being a side view and FIG. 2 being a plan view.

In the figure, reference numeral 1 denotes an arc tube, which is made of quartz or hard glass and has a substantially elliptical shape. Crushing sealing portions 2, 2 are formed at both ends of the arc tube 1 along the lamp axis O-O. These crushing sealing parts 2, 2 are formed by crushing the heat-softened end of the arc tube from the top and bottom directions in FIG.

Metal foil conductors 3, 3 are sealed to these sealing parts 2, 2, respectively. These metal foil conductors 3, 3 are made of a high melting point metal such as molybdenum, and both surfaces thereof face in the crushing direction of the crushing sealing parts 2, 2. That is, in FIG. 1, both surfaces of the metal foil conductors 3, 3 face upward and downward. Electrodes 4, 4 and external lead wires 5, 5 are connected to each metal foil conductor 3, 3.

The electrode 4 consists of an electrode shaft 6 and an electrode coil 7 wound about 3 to 4 times around the tip of the electrode shaft 6.
The base end of the electrode shaft 6 is welded to the metal foil conductor 3. In this case, the base end of the electrode shaft 6 is joined to the metal foil conductor 3 on the upper surface side in FIG. 1, that is, the surface facing the sky in normal use. In this case, the electrode shaft 6 is bent downwardly from the lamp axis OO as shown in FIG. 1, and the tip is offset downward from the lamp axis OO. The electrode shaft 6 is made of pure rhenium wire or tungsten containing rhenium, and the electrode coil 7 is made of pure tungsten.

External lead wires 5, 5 connected to the metal foil conductors 3, 3 are made of tungsten, and these external lead wires 5, 5 are connected to caps 8 provided at the ends of the sealing parts 2, 2.
, 8. Such an arc tube 1 is filled with mercury as a buffer metal, a metal halide as a luminescent metal, and a starting rare gas such as argon or xenon.

As the metal halide, sodium N
Alkali metal halides such as a and lithium Li are also known, but dysprosium iodide DyI3
Holmium Iodide HoI3, Thulium Iodide Tm
When I3 and rare earth metal halides such as dysprosium bromide DyBr3, holmium bromide HoBr3, and thulium bromide TmBr3 are sealed, the luminous efficiency is further improved and the color temperature becomes higher. Holmium HoI3
, thulium iodide TmI3, dysprosium bromide DyBr3, holmium bromide HoBr3, and thulium bromide TmBr3 are sealed.

[0018] In the case of a 220W metal halide lamp, the distance l between the electrodes is approximately 4 to 10 mm.
The tube wall load is 30 to 50 W/cm2. Also,
The rare earth metal halide sealed in the arc tube 1 is
The rare earth metal iodine and rare earth metal bromide are encapsulated at a ratio of 2.0 mg/cc, and the weight ratio of rare earth metal iodide to rare earth metal bromide is 1:0.5.

[0019] Such a small metal halide lamp is
As shown in the figure, the lamp is attached to a fixture and lit so that the lamp axis O-O is oriented substantially horizontally, that is, the sealing parts 2, 2 at both ends are in a horizontal position. In this case, as shown in FIG. 1, the tip of the electrode 4 is turned on in a posture deviated downward from the lamp axis OO.

[0020] When lighting in this position, the electrodes 4, 4
Even if the arc generated between the tips of the lamp is pushed upward by gas convection within the arc tube 1 and curved into an arch shape, the center of the curve will approximately coincide with the lamp axis O--O. Therefore, the arc does not approach the tube wall unevenly, and local overheating of the tube wall due to the arc is prevented. Therefore, thermal deformation of the arc tube 1, ie, bulges, cracks, etc., is prevented, and the reaction between halogen and quartz is also prevented.

As mentioned above, the tip of the electrode 4 is aligned with the lamp axis O-
In order to deviate from O to one side, the base end of the electrode shaft 5 is joined to the surface of the metal foil conductor 3 opposite to the direction in which the tip of the electrode 4 is deviated. This can be achieved by That is, the metal foil conductor 3 is sealed to the crushing sealing part 2, and the crushing direction of the crushing sealing part 2 coincides with the direction of both surfaces of the metal foil conductor 3. When the electrode shaft 5 is joined to one side of the metal foil conductor 3 and the crushing sealing part 2 is crushed, the flow of the softened glass flesh of the sealing part is different from that to the side to which the electrode shaft is joined. There is a difference between the surface and the surface. On the surface where the electrode shaft is joined, the heat of the crushed glass is transferred to the electrode shaft, which quickly cools down and becomes hard.
Therefore, the flow of the softened glass becomes poor. As a result, the electrode shaft is pushed by the hardened glass and tilts to the opposite side.

Therefore, when the arc tube is installed in a horizontal position with the surface of the metal foil conductor 3 to which the electrode shaft 5 is joined facing upward, the tip of the electrode 4 is deviated below the lamp axis O-O. This makes it possible to prevent the arc from approaching the pipe wall.

In particular, the tube wall load is set to 20 to 100 W/cm2.
In the case of small metal halide lamps with high output, the temperature of the tube wall tends to be high, so the heating of the tube wall due to arc bending has a significant effect and tends to cause deformation of the tube wall. If the structure of the above embodiment is used, the influence of heat will be reduced and the life will be extended.

Furthermore, since the sealing part and electrodes of small lamps are small, it is difficult to control the posture of the electrodes by operating or holding them from the outside, but the configuration of the above embodiment allows the electrodes to be automatically moved by crushing and sealing. Since it can be tilted, it is advantageous for small lamps.

In this embodiment, since the electrode shaft 6 is made of pure rhenium wire or tungsten containing rhenium, cracks and leaks in the sealing portion 2 can be prevented. That is, since rhenium or tungsten containing rhenium has lower thermal conductivity than pure tungsten, it is difficult to transfer the heat of the electrode coil 7 to the metal foil conductor 3 during lighting. Therefore, it is possible to suppress the temperature rise of the sealing part 2 and prevent peeling due to the difference in thermal expansion between the sealing part 2 and the metal foil conductor 3 and the occurrence of cracks due to thermal stress. In addition, rhenium has advantages such as better halogen resistance than tungsten and superior weldability to molybdenum foil. Note that the present invention is not limited to the above embodiments. That is, the present invention is not limited to metal halide lamps, but may also be applied to high-pressure mercury vapor discharge lamps. Further, the electrode is not limited to an electrode coil wound around an electrode shaft, and may be only an electrode shaft.

Furthermore, the small metal vapor discharge lamp of the present invention has the following features:
The light source is not limited to the light source of a liquid crystal projector device, and may be a light source of other image projection devices such as a movie projector or a magic lantern, or a light source of a vehicle headlight, or in a sense, a light source for general illumination.

[0027]

Effects of the Invention As explained above, according to the present invention, the base end of the electrode is joined to the upper surface of the metal foil conductor, so that when the crushing sealing part is crushed and deformed, the tip of the electrode is moved downward from the horizontal direction. By tilting to the side, the electrode tip is deflected downward. Therefore, even if the arc curves during lighting, the center of this curve will almost match the lamp axis, preventing the arc from approaching the tube wall and preventing thermal deterioration and thermal deformation of the tube wall. and can have a long lifespan.

[Brief explanation of the drawing]

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

FIG. 2 is a plan view of the same embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Arc tube, 2... Crushing sealing part, 3... Metal foil conductor, 4... Electrode, 6... Electrode shaft, 7... Electrode coil.

Claims (1)

[Claims] Claim 1: A crushed sealing portion is formed at both ends of an arc tube, metal foil conductors are sealed to these crushed sealing portions, and electrodes and external lead wires are connected to these metal foil conductors, respectively. In a small metal vapor discharge lamp that is lit with the metal foil conductors facing each other in the arc tube and the sealing part facing approximately horizontally, both sides of the metal foil conductor sealed to the crushing sealing part are oriented vertically. A small metal vapor discharge lamp characterized in that the base end of the electrode is joined to the upper surface of the electrode, and the tip of the electrode is inclined downward.