JPH04141941A - ceramic discharge lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Application Field) The present invention relates to a ceramic discharge lamp such as a high-pressure sodium lamp having a curved portion.

(Prior Art) For example, in a high-pressure sodium lamp, electrodes are hermetically sealed at both ends of an arc tube made of a translucent alumina tube, and inside the arc tube are sodium as a luminescent material, mercury as a buffer metal, and diluted starting material. It is constructed by sealing gas.

Translucent alumina tubes have excellent heat resistance and corrosion resistance against sodium chloride, so they are suitable for arc tubes in high-pressure sodium lamps of this type.

However, unlike ordinary glass, translucent alumina tubes do not easily soften even at high temperatures, so conventionally, straight tubes formed by extrusion molding have been used as bulbs, and therefore arc tubes have a straight tube shape. There is.

By the way, there is a recent tendency for high-pressure metal vapor discharge lamps to be used as light sources for indoor lighting, and therefore there is a demand for miniaturization of the lamps.

In reducing the size of the high-pressure sodium lamp, reducing the size of the arc tube is an important issue, and one possible solution to this problem is to curve the middle of the bulb into a U-shape or U-shape.

When the arc tube is formed into a curved shape, the space can be made smaller even if the distance between the electrodes is kept the same as in the conventional case, and the outer tube can be made smaller.

(Problem to be Solved by the Invention) By the way, when the arc tube is formed into a curved shape as described above, discharge occurs so as to connect the shortest path between the electrodes. The resulting arc also tends to shift to the inside of the curve.

However, in high-pressure sodium lamps with curved arc tubes as described above, translucent alumina tubes with a perfectly circular cross section are used based on the same design standards as conventional straight arc tubes. If a curved arc tube is manufactured using a curved arc tube, an imbalance in the color of light emitted from the outside of the curved portion, which is the substantial light emitting portion, will occur.

In other words, if the cross section of the curved part is a perfect circle, the distance between the center of the arc and the outer peripheral surface of the curved part will not be uniform, and the degree to which the light emitted from the arc will be absorbed by the encapsulated sodium will vary. Therefore, it is thought that an imbalance in the light color of the emitted light on the outer circumferential surface of the curved portion occurs.

In addition, such discharge lamps are often used in such a way that the outer part of the curved part substantially contributes to light irradiation;
In particular, the imbalance in the color of light emitted from the outside of the curved portion poses a problem.

The present invention was made based on the above-mentioned circumstances, and an object thereof is to provide a ceramic discharge lamp that can reduce the imbalance in the color of light emitted from the outside of the curved portion.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the ceramic discharge lamp of the present invention includes a luminescent metal, a buffer metal, and a starting rare gas in an arc tube made of a translucent ceramic tube. This is a ceramic discharge lamp in which a lamp is sealed and electrodes are sealed at both ends.The arc tube has a curved part, and the inner diameter of the arc tube connecting the inside and outside of the curved part is reduced. It is characterized by this.

(Function) In the present invention, since the inner diameter of the arc tube connecting the inside and outside of the curved part is reduced, even if the arc shifts to the inside of the curved part, it contributes to substantial light irradiation. Since the increase in the distance between the outer portion of the curved portion and the arc center can be reduced, changes in light color due to absorption of sodium can be significantly suppressed.

(Example) An embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, a high-pressure sodium lamp according to the present invention, an outer tube 1 made of, for example, quartz glass has one end connected to a stem 2.
It is sealed with a screw-type cap 3 on the outside.

Further, in the outer tube 1, an inert gas such as argon, xenon, krypton, nitrogen, etc. is sealed at about 15 to 500 Torr, and an arc tube 4 is housed therein.

The arc tube 4 is made of a translucent alumina tube and is formed into, for example, a U-shape as shown in the figure.

The openings at both ends of the arc tube 4 are closed with, for example, ceramic discs (not shown) via solder such as metal oxide, and the electrodes 5.5 are supported by the ceramic discs.

Here, in this arc tube 4, the distance between the electrodes passing on the bulb center line is approximately 9011IIQ, the curvature passing through the center of the curved portion 6 is approximately 7.5+m, and the height of the arc tube 4 is approximately 4
It is set to 0III11.

In addition, the inner diameter of the arc tube 4 other than the curved portion is approximately 7.2 mm.
5 mm, and the average outer diameter is approximately 8.75 mI++.

The cross-sectional shape of the curved portion is shown in FIG.
As shown in the A-section, the inner diameter of the arc tube connecting the inside and outside of the curved part is reduced. Specifically, the inner diameter of the arc tube connecting the inside and outside of the curved part is 5 m + a, and this inner diameter is reduced. It has an elliptical shape with orthogonal inner diameter axes measuring approximately 7.25 mm.

Inside this arc tube 4, the sodium ratio is 10 to 25.
A weight ratio of sodium amalgam and xenon gas of 20 to 700 Torr as a starting rare gas are sealed.

The lead wire 7.7 connected to the electrode 5.5 is connected to support wires 8, 8, which pass through the stem 2 in an airtight manner and are connected to the base 3.

Therefore, the arc tube 4 is housed with both end sealing portions facing toward the crushing sealing portion of the outer tube 1 and the curved portion 6 facing toward the bulb top portion of the outer tube 1 .

The straight portion of the arc tube 4 is mechanically supported by a bulb holder 9, and elastic contact plates 10 and 10 such as leaf springs are attached to both ends of the bulb holder 9. The plate 10.10 rests elastically on the inner surface of the outer bulb 1 and supports the arc tube 4.

For arc tubes with the above structure, the tube wall load is set to 10~
30 (W/cm2) and observed the light color of the light emitted from the arc tube, there was no imbalance in the light color emitted from the outer peripheral surface of the curved part, and the light color was uniform. It was confirmed that synchrotron radiation could be obtained.

On the other hand, when we manufactured a discharge lamp whose curved part had a perfect circular cross-section and observed the light color of the curved part under the same conditions, we found that there was no difference in the color of the light emitted from the outer peripheral surface of the curved part. Equilibrium was observed.

As mentioned above, if the cross section of the curved part is a perfect circle,
The distance between the center of the arc and the outer circumferential surface of the curved part is no longer uniform, and specifically, the distance between the center of the arc and the inner surface of the arc tube outside the curved part increases as the arc shifts, and this part This is because the influence of sodium absorption becomes significant in
This is thought to cause an imbalance in the light color of the emitted light on the outer peripheral surface of the curved part, but according to the discharge lamp with the configuration shown in this example, the inner diameter of the arc tube connecting the inside and outside of the curved part Since the diameter is reduced, an increase in the thickness of the sodium atoms can be prevented, and the imbalance in the color of light emitted from the outer circumferential surface of the curved portion is improved.

In the above embodiments, the arc tube is formed in a U-shape, but the present invention is not limited to this. If it is, it can be applied in the same manner as the above embodiment.

Furthermore, regarding the cross-sectional shape of the curved portion, although an elliptical cross-sectional shape is explained in the above embodiment, it may be shaped so that the inner diameter of the arc tube connecting the inside and outside of the curved portion is reduced. If so, it is possible to improve the color imbalance of light emitted from the outer circumferential surface of the curved portion.

[Effects of the Invention] According to the present invention described above, since the inner diameter of the arc tube connecting the inside and outside of the curved portion is reduced, even if the arc shifts to the inside of the curved portion, it will not be substantially suppressed. Since the increase in the distance between the outer part of the curved part and the arc center, which contributes to light irradiation, can be reduced, changes in light color due to absorption of sodium can be significantly suppressed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a high-pressure sodium lamp according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing the shape of a curved portion of the arc tube. 1... Outer tube 2... Stem 3... Base 5... Electrode 7... Lead wire 9... Valve Holder 4... Arc tube 6... Curved portion 8... Support wire 10... Elastic contact plate

Claims (1)

[Claims] A ceramic discharge lamp in which a light-emitting metal, a buffer metal, and a starting rare gas are sealed in an arc tube made of a translucent ceramic tube, and electrodes are sealed at both ends, and the arc tube has a curved part. A ceramic discharge lamp characterized in that the inner diameter of the arc tube connecting the inside and outside of the curved portion is reduced.