JPH01298638A - Small-sized metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To improve luminous efficiency and color rendition by bending the tip vicinity of the electrode aces in the rear direction so as to be adjacent to the inside of a luminous tube. CONSTITUTION:The electrode axes 4 are formed while being bent along the inside of a bulb 1 so as to be mutually facing to become the access parts 8, to the tips of which the electrode coil parts 5 are fixed. As to the access parts 8, by warming the wand of the bulb 1 with radiation heat, a temperature of the coolest part generated on the parts facing the access parts 8 of the axes 4 is heightened to raise vapor pressure so that both of the luminous efficiency and color rendition are improved. Further, since the axes 4 are bent along the inside of the bulb 1, the coil parts 5 come to face being mutually separated so that the interval size of the electrodes 3 can be enlarged even the bulb is small, while enlarging the length of an arc so as to improve the luminous efficiency. thereby, the luminous efficiency and color rendition can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Field of Application) The present invention relates to a small metal vapor discharge lamp, such as a small metal halide lamp, in which the electrode structure is changed.

(Prior Art) For example, metal halide lamps have excellent efficiency and color rendering properties, and have recently become popular as light sources for display lighting in stores and indoor lighting with low ceilings. As such devices become more widespread, there is a demand for smaller devices, and for this reason metal halide lamps, which serve as the light source, are being made smaller.

When trying to further miniaturize such lamps,
If the shape of the arc tube is a bulb structure of the conventionally generally adopted both-ends crush-sealed type, it not only takes time and effort to mold, but also has the drawback that the crush-sealed portion becomes large, resulting in a large overall size.

Therefore, the structure of the arc tube adopts a one-end crush-sealed structure. That is, the arc tube made of quartz glass has only one end crushed and sealed, a pair of electrodes are supported by this one end crushed seal, and the outer tube that houses this has a structure in which only one end is crushed and sealed. It is.

According to such a structure, since there is only one crushing sealing part, the number of crushing sealing parts, which tend to be relatively large for a relatively small discharge space, is reduced, and the entire bulb can therefore be miniaturized. becomes possible.

In addition, since the sealing portion, which is a major factor in heat loss from the arc tube, exists only on one side, there are advantages such as less heat loss and being suitable for improving luminous efficiency compared to a double-sealed type.

(Problem to be Solved by the Invention) In the case of the above-mentioned arc tube structure, two metal foil conductors are juxtaposed and sealed in one crushed sealing part, and electrodes are attached to these metal foil conductors. The electrodes are connected to each other, and these electrodes are arranged to face each other in the discharge space. In this case, the width dimension of the crush sealing part cannot be made unnecessarily large in order to make the whole compact, and in order to maintain good airtightness between the quartz glass and the two metal foil conductors, It is not possible to seal the two metal foil conductors close to the ends in the width direction of the crush sealing portion.

Therefore, the distance between the two metal foil conductors cannot be set large, and the distance between the electrodes connected to these metal foil conductors cannot be set large.

Therefore, the distance between the tip of the electrode and the wall surface of the arc tube bulb located behind the tip of the electrode becomes large.

As described above, when the distance between the tip of the electrode and the bulb wall of the arc tube increases, the coldest part of the discharge space occurs at the tube wall surface at the back of the electrode. This coldest part is relatively far from the electrodes, so the temperature is low, and therefore the vapor pressure inside the arc tube is low, resulting in lower luminous efficiency, lower color rendering, and lamp characteristics when the lighting direction changes. This may lead to problems such as large fluctuations in the amount of water.

The present invention aims to provide a small metal vapor discharge lamp that can increase the distance between the electrodes and increase the temperature of the coldest part generated at the back of the electrodes to improve luminous efficiency and color rendering. It is something to do.

[Structure of the Invention (Means for Solving the Problems) The present invention includes a pair of electrodes housed inside an arc tube whose one end is closed and a crushed seal formed at the other end, and each of these electrodes has a In a small metal vapor discharge lamp in which the proximal ends of the electrode shafts are sealed to the crushing sealing part and the distal ends thereof are opposed to each other so as to face the center of the arc tube, the electrode shafts are placed near the distal end side once. It is characterized by being bent toward the back so as to be close to the inner surface of the arc tube.

(Function) According to the present invention, the vicinity of the tip side of the electrode shaft is bent in the back direction so as to be close to the inner surface of the arc tube, so the distance between the pair of electrodes can be increased, and the arc length can be increased even though the bulb is small. In addition, since the electrode axis whose temperature rises is close to the inner surface of the arc tube at the back, the temperature of the coldest part generated at the back can be increased, improving luminous efficiency and color rendering.

(Example) The present invention will be described below based on a first example shown in FIG.

In the figure, reference numeral 1 denotes an oval arc tube bulb made of quartz glass. In this arc tube bulb 1, the long sleeve direction is the bulb axis, and a crushed sealing part 2 is formed at one end in the short axis direction perpendicular to this. has been done. The other end of the valve 1 is closed.

Inside the bulb 1, a pair of electrodes 3.3 are provided spaced apart from each other, and these electrodes 3, 3 are sealed in the crush sealing part 2.

In this embodiment, the electrodes 3, 3 are composed of an electrode shaft 4.4 and an electrode coil portion 5°5 for increasing the heat capacity. 5, 5 are formed from separate members, and an electrode coil portion 5.5 is fixed to the tip of the electrode shafts 4, 4.

Note that the materials of the electrode shafts 4, 4 and electrode coil parts 5, 5 are such that when the electrode shaft 4 is made of pure tungsten, the electrode coil part 5 is made of thorium oxide, and when the electrode shaft 4 is made of pure rhenium or a rhenium alloy. It is desirable that the electrode coil portion 5 be made of pure tungsten or tungsten containing thorium oxide.

Furthermore, when the wire diameter of the electrode shaft 4 is D (am) and the coil diameter of the coil part 5 is d (mm), 0.3≦d/
It is desirable to satisfy the relationship D<1.

The electrode coil parts 5, 5 are arranged along the valve axis within the valve 1.
They are spaced apart and facing each other.

The electrode shafts 4, 4 are introduced into the crushing sealing part 2, and a metal foil conductor 6, such as Mo or the like, is sealed to the crushing sealing part 2.
6, respectively. External lead wires 7, 7 are connected to the metal foil conductors 6, 6, respectively.

The bulb 1 is filled with a predetermined amount of mercury, metal halides such as sodium, thallium, and indium, and a starting rare gas.

The electrode shafts 4, 4 are bent toward the back so as to move away from the center of the bulb, that is, to move the electrode coil parts 5, 5 away from each other, at the point where they are led out from the crushing sealing part 2 into the discharge space. It is.

In the case of this embodiment, the electrode shaft 4.4 is curved so as to extend along the inner surface of the bulb 1, and the tip of the electrode shaft 4.4 is curved so as to extend along the inner surface of the bulb 1.
It approaches the inner surface of 8,8.

The distal ends of this approach portion 8.8 are bent so as to face each other, and the electrode coil portions 5, 5 are fixed to these bent distal ends.

Incidentally, the arc tube having the above structure is housed in an outer tube (not shown) and used as a double tube structure.

The operation of the first embodiment with such a structure will be explained.

Since the arc tube bulb 1 has only one crushing sealing part 2, the number of crushing sealing parts, which tend to be large, is reduced, and the overall structure of the bulb is made smaller and more compact.

While the lamp is lit, the electrode coil portion 5.5 generates heat, and this heat is transmitted to the electrode shaft 4.4.
to raise the temperature.

In this embodiment, the electrode shaft 4.4 is curved so as to extend along the inner surface of the bulb 1, and the access portions 8, 8 formed at the tip of the electrode shaft 4.4 extend along the valve axis direction. Since they are close to the wall, these approaching parts 8, 8 will warm the valve wall with radiant heat. That is, the temperature of the coldest part generated in the part facing the approach part 8.8 of the electrode shafts 4, 4 is increased, and therefore the vapor pressure is increased, the luminous efficiency is improved, and the color rendering properties are also improved. .

In addition, even if the lighting position changes and the electrodes are turned vertically and the light is turned on, an extremely low-temperature coldest part will not occur below the lower electrode. Problems such as significant fluctuations in lamp characteristics such as luminous efficiency and color rendering properties are also prevented.

Furthermore, since the electrode shafts 4, 4 are curved so as to extend along the inner surface of the bulb 1, the electrode coil parts 5, 5 attached to the electrode shafts 4, 4 can be separated from each other and made to face each other. That is, even if the bulb 1 is small, the distance between the electrodes can be increased, and the arc length is increased, which also improves the luminous efficiency.

In addition, if the electrode shaft 4.4 is made of pure tungsten, it has excellent heat resistance, whereas if the electrode coil part 5 is made of thorium oxide, it has good discharge properties, but there are problems such as discharge occurring at the electrode shaft 4.4. It disappears.

Furthermore, if the electrode shafts 4, 4 are made of pure rhenium or a rhenium alloy, they will have excellent halogen resistance, whereas if the electrode coil portion 5 is made of pure tungsten or tungsten containing thorium oxide, they will have good discharge properties. , breakage of the electrode shafts 4, 4 can be prevented, resulting in a long life.

Moreover, if the diameter of the coil element wire is made smaller than the wire diameter of the electrode shaft 4, discharge of the coil portion 5 can be easily promoted, discharge between the electrode shafts 4 can be prevented, and an increase in the turning-off voltage can be suppressed. In particular, when the wire diameter of the electrode shaft 4 is D (■) and the coil wire diameter of the coil part 5 is d (IllIll), 0.3≦d/
It is desirable to satisfy the relationship D<1.

Note that the present invention is not limited to the above embodiments.

That is, the shape of the electrode shafts 4, 4 is not limited to being curved so as to extend along the inner surface of the bulb 1;
As in the second embodiment shown in the figure, only the portions corresponding to the backs of the electrode coil parts 5, 5 may be brought closer to the bulb 1 10.10.

Further, the electrode 3.3 is not necessarily limited to having the electrode shaft and the coil part made of different materials and having separate structures, but may be one in which the electrode shaft and the coil part are integrally molded.

Furthermore, the electrodes 3, 3 may have a structure that does not include an electrode coil portion, as in the third embodiment shown in FIG.

Furthermore, the present invention is not limited to metal halide lamps, but may be applied to other small metal vapor discharge lamps such as high-pressure mercury lamps, etc. It may be an electric light.

[Effects of the Invention] As explained above, according to the present invention, since the vicinity of the tip side of the electrode shaft is bent in the back direction so as to be close to the inner surface of the arc tube, the distance between the pair of electrodes can be increased. Although the bulb is small, the arc length can be made relatively long, and since the adjacent electrode shaft heats the inner surface of the arc tube at the back, it is possible to increase the temperature of the coldest part generated at the back. 2, the luminous efficiency and color rendering properties are improved, and variations in lamp characteristics due to lighting orientation can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a small metal halide lamp showing a first embodiment of the invention, FIG. 2 is a sectional view of a small metal halide lamp showing a second embodiment of the invention, and FIG. 3 is a sectional view of a small metal halide lamp showing a second embodiment of the invention. FIG. 3 is a sectional view of a small metal halide lamp showing a third embodiment. DESCRIPTION OF SYMBOLS 1... Arc tube bulb, 2... Crushing sealing part, 3...
Electrode, 4... Electrode shaft part, 5... Electrode coil part, 6...
... Metal foil conductor, 7... External lead wire, 8.10...
・Approach area. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Scope of Claims] A pair of electrodes are housed inside an arc tube whose one end is closed and a crushing seal is formed at the other end. In a small metal vapor discharge lamp, the electrode shafts are sealed so that the ends thereof are opposed to each other so as to face the center of the arc tube, and the electrode shafts are bent so that the vicinity of the tip side is once close to the inner surface of the arc tube. A small metal vapor discharge lamp characterized by: