JPH04169032A - Metallic vapour electric 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 Field of the Invention The present invention relates to improvements in metal vapor discharge lamps, and more particularly to improvements in end caps of arc tubes for high pressure sodium lamps.

[Prior Art] A high-pressure sodium lamp, which is formed by sealing end caps at both ends of a translucent ceramic tube, has a rare gas such as xenon gas, sodium, and mercury sealed in the arc tube.

In addition, taking into account the consumption of sodium during lamp lighting, sodium is sealed in the sodium amalgam state in an amount larger than the amount required to emit light, and during one lighting period, the excess amalgam condenses in liquid form near the coldest part of the arc tube. This is called a saturated vapor pressure discharge lamp.

In addition, there are two types of lamps in the coldest part of the arc tube of high-pressure sodium lamps based on differences in the structure of the arc tube end.

The first type, as shown in Figure 1(b), is a type in which exhaust pipes made of metal such as niobium, which serve as electrode introduction conductors, protrude from both ends of the arc tube, and the coldest part is the end of the niobium tube. , excess amalgam collects at the inner end of the niobium tube.

The second type, as shown in FIG. 1(a), uses an electrode introduction conductor without using an exhaust pipe, and the coldest part is the inner end of the arc tube.

Now, consider a case where shock or vibration is applied while the lamp is lit.

The former has a structure in which it takes some time for the surplus amalgam to flow out into the discharge arc of the arc tube due to the impact, but the latter has a structure where the surplus amalgam is inside the arc tube.
It will immediately come out in the discharge arc. Then, when excess amalgam comes out into the arc, the lamp voltage suddenly rises, causing problems such as changes in lamp characteristics and failure of the lamp.

[Problems to be Solved by the Invention] As described above, the saturated vapor pressure type metal vapor discharge lamp, in which surplus amalgam condenses in the coldest part of the arc tube during lighting, has the problem of turning off due to vibration or impact during lighting. .

The present invention has been made in view of the above, and an object of the present invention is to provide a metal vapor discharge lamp which has stable lamp characteristics and has a long life without increasing the lamp voltage due to excess amalgam in one arc tube.

[Means for Solving the Problems] In order to achieve the above object, the present invention seals end caps at both ends of a translucent ceramic tube, through which an electrode introduction conductor is fixed through the center part, and a dielectric conductor is fixed inside. A metal vapor discharge lamp comprising an arc tube that encloses sodium amalgam together with gas, characterized in that an uneven portion is formed on the inner surface of the end cap.

Further, in the discharge lamp, the coldest part of the arc tube during lighting is configured inside the tube end.

Further, during operation of the discharge lamp, excess amalgam of the arc tube is aggregated on the inner surface of the end cap.

[Function] The above configuration increases the contact area between the liquid amalgam and the inner end surface compared to a conventional arc tube in which excess amalgam aggregates on the inner end surface (plane) of the end of the arc tube.

The larger the contact area, the more difficult it is to shake due to vibrations, etc., and the more difficult it is for amalgam to come out in the discharge arc.

[Example] Hereinafter, an example according to the present invention will be described based on FIGS. 1 and 2.

In the figure, 1 is an arc tube, and electrode introduction conductors made of niobium wire 4 or niobium tube 8 with an electrode 3 fixed at the tip are fixed at both ends of the translucent ceramic tube 2 through a through hole in the center. End camps 5 and 5 are sealed. and.

Inside, xenon gas is sealed along with sodium and mercury.

Note that FIG. 1(c) shows a conventional end cap 5, and 5a
is a through hole.

As shown in FIGS. 2(a) to 2(d), the end cap according to the present invention is a bottomed cylindrical aluminum oxide 1 having a single step.
0, and electrode introduction conductors 4 and 8 are provided at the center of the cylindrical portion 11.
A through-hole portion 12 is formed through which the material can be inserted. Further, the cylindrical portion 5 has a recessed portion 13° and a convex portion 14 formed in a chrysanthemum-like or wavy shape with four peaks and four valleys.

This wall is formed by a cylindrical portion 11 and a through-hole portion 12 in order to prevent contact between the sealant and the sodium amalgam and to reduce loss of sodium.

Further, the volume of the recess 13 varies depending on the volume of the amalgam to be sealed, but it is preferable that the volume of the recess is larger than the volume of the amalgam.

A high-pressure sodium lamp with a lamp input of 360 W uses a light-transmitting ceramic tube with an inner diameter of 8 I, an outer diameter of 9.5 cm, and a total length of 95 cm, and a luminescent tube with an electrode distance of 75 cm. About 40 μm of sodium amalgam is sealed in the lamp. However, the volume of the sodium amalgam at this time is about 9 mm, and the volume of the recess is preferably about 12 mm.

Next, an experimental example will be explained.

A 360W high-pressure sodium lamp with the shape shown in Figure 2 and a conventional flat inner end of the end cap of the arc tube was lit, and after the characteristics had stabilized, a shock was applied to the lamp. Check the voltage rise value and the presence or absence of fading.
As a result, the results shown in Table 1 were obtained.

Table 1 As is clear from Table 1, the lamp according to the present invention had a smaller increase in lamp voltage than the conventional lamp, and did not cause the lamp to turn off.

The coldest part where sodium amalgam aggregates during lighting is the inner end of the arc tube, but in contrast to conventional methods where the sodium amalgam aggregates on the inner end plane of the end cap, the present invention has a wavy shape on the end cap. It gets into the valley of the surface and accumulates.

For this reason, for an equal amount of amalgam, the area in contact with the inner end face is large, making it difficult for the amalgam to move.

Other embodiments of the end cap are shown in FIGS. 3 and 4.

FIG. 3 shows a shape with eight peaks and valleys and no tip end of the cylindrical portion shown in FIG. 2, and FIG. 4 shows a shape in which a large number of fine grooves are formed in the cylindrical portion.

In this way, in both cases, an uneven portion is formed on the inner end surface of the arc tube end cap.

[Effects of the Invention] As is clear from the above description, the metal vapor discharge lamp according to the present invention has a relatively simple structure, and is capable of suppressing the increase in lamp voltage and the lamp extinguishment caused by vibrations during lighting caused by excess sodium amalgam in the arc tube. It has advantages such as stable lamp characteristics throughout its life and long life.

[Brief explanation of drawings]

1(a) and 1(b) are sectional views of essential parts showing the arc tube of a metal vapor discharge lamp, FIG. 1(c) is a perspective view showing a conventional end cap, and FIG. 2(a) is a sectional view of the main part showing the arc tube of a metal vapor discharge lamp. (b) is a plan view, (C) is a sectional view taken along line A-A', (d) is a perspective view of the end cap according to
3(a) is a sectional view taken along line BB', and FIG. 3(a) is a plan view of an end cap according to another embodiment. (b) is a side view, (c) is a sectional view taken along line AA', (d) is a sectional view taken along line BB', and FIG. 4(a) is a plan view of an end cap according to another embodiment. (b) is a side view, (c) is A-A'
A line sectional view, (d) is a BB' line sectional view.

Claims (3)

[Claims] (1) In a metal vapor discharge lamp consisting of an arc tube in which end caps with electrode introduction conductors fixed through the center are sealed at both ends of a translucent ceramic tube, and sodium amalgam is sealed together with a rare gas inside. A metal vapor discharge lamp comprising an uneven portion formed on the inner surface of the end cap. (2) The metal vapor discharge lamp according to claim 1, wherein the discharge lamp is characterized in that the coldest part of the arc tube during lighting is located inside the tube end. (3) During lighting of the discharge lamp, surplus amalgam of the arc tube aggregates on the inner surface of the end cap.
Metal vapor discharge lamps as described in .