JPH04137451A - Ceramics discharge lamp - Google Patents

Abstract

PURPOSE:To prevent the variation of the lamp performance and the voltage by providing a throttle passage with the section area smaller than that of a luminous metal condensate, positioning close to a luminous tube side than the liquid level of the luminous metal, and connecting a luminous tube holder at the position close to the luminous tube side than the liquid level of the luminous metal condenced at the end of a small tube. CONSTITUTION:Since a throttle passage 5c is provided at the position close to a luminous tube 3 side than to the liquid level of a luminous metal, the movement of an amalgam 15 in a condensate 5b to the luminous tube 3 side by receiving a shock and the like during the lamp is lighted is reduced. And, even though the amalgam 15 in the condensate 5b is moved to the luminous tube 3 side, a luminous tube holder 10a is connected to the place the amalgam 15 moves, and thereby, the temperature of a small tube there is reduced. As a result, the temperature difference at the amalgam pool and the connecting part of the luminous tube holder 10a in the small tube is little, and a sudden large amount of evaporation is prevented even though the amalgam 15 in the condensate 5b is moved to the luminous tube 3 side. Consequently, the variation of vaper pressure is prevented, and the variation of the lamp performance and the lamp voltage can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a ceramic discharge lamp using an arc tube made of translucent ceramic.

(Prior art) For example, a high-pressure sodium lamp has a ceramic arc tube made of translucent alumina or the like housed in an outer bulb, electrodes are sealed at both ends of the arc tube, and sodium as a luminescent substance is housed inside the arc tube. It is filled with mercury as a buffer gas metal and a rare gas for starting, and has the highest luminous efficiency among various discharge lamps, so it is attracting attention as a lamp suitable for energy saving.

However, conventional high-pressure sodium lamps still have a problem of low color rendering, and are not necessarily suitable for indoor lighting. Therefore, it is desired to develop a high-pressure sodium lamp with improved color rendering properties.

In order to improve color rendition, it is necessary to increase the vapor pressure of sodium during lighting, and for this reason, the temperature of the coldest part of the arc tube is increased, and the vaporization of excess sodium amalgam that condenses in this coldest part is promoted. This is effective.

By the way, in a high-pressure sodium lamp, the end of an arc tube made of alumina or the like is closed with a closing wall (end cap) made of alumina or niobium, and an exhaust capillary made of niobium as an electricity introduction body is connected to this closing wall. It is constructed by penetrating and sealing, and an electrode is connected to the inside of the arc tube of this exhaust capillary.

In many cases, the coldest part of the arc tube is formed at the tip of the exhaust capillary, and therefore excess sodium amalgam is condensed at the tip of the exhaust capillary.

(Problem to be Solved by the Invention) However, when an amalgam with a high proportion of sodium is sealed in an arc tube, this amalgam with a high proportion of sodium has higher fluidity than amalgam with a low proportion of sodium. When an impact is applied to the exhaust pipe, the sodium amalgam condensed in the condensation part (pool part) at the tip of the exhaust tube is likely to move. When the sodium amalgam that has condensed in the pool at the tip of the exhaust capillary moves, it moves to a higher temperature area on the arc tube side, and as a result, a large amount of sodium evaporates rapidly, causing lamp characteristics such as luminous efficiency and color rendering to deteriorate. or the lamp voltage VL fluctuates.

If this lamp voltage vL fluctuates greatly, the lamp may go out.

In other words, in the conventional case, if a shock is applied while the lamp is lit, the sodium amalgam condensed in the condensation part (pool part) at the tip of the exhaust capillary moves to the arc tube side and may come into contact with a high temperature area. be.

Therefore, an object of the present invention is to make it difficult for the sodium amalgam condensed in the condensation part (reservoir part) at the tip of the capillary to move even if it is subjected to an impact while the lamp is lit, and to The object of the present invention is to provide a ceramic discharge lamp that can prevent sodium from coming into contact with sodium and prevent fluctuations in lamp characteristics and lamp voltage VL due to rapid evaporation of sodium.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a thin tube connected to the end of the arc tube, which is located closer to the arc tube than the liquid level of the luminescent metal condensed at the end of the thin tube. In addition, a constriction passage having a cross-sectional area narrower than the cross-sectional area of the luminescent metal condensation portion is provided, and the luminescent metal condensation portion is located at a location closer to the arc tube than the liquid surface of the luminescent metal condensed at the end of the capillary tube. It is characterized by a luminous tube holder that supports the tube.

(Function) According to the present invention, since the throttle passage is located closer to the arc tube than the liquid level of the luminescent metal and has a cross-sectional area narrower than the cross-sectional area of the condensation part of the luminescent metal, it is possible to It is possible to reduce the movement of the amalgam in the condensing part toward the arc tube even if it receives an impact. Even if the amalgam in the condensing part moves to the arc tube side, the arc tube holder is connected to the destination, and the heat of the capillary is released through this arc tube holder, reducing the temperature of the capillary at this location. In other words, in the thin tube, the temperature difference between the above-mentioned pool where the amalgam is condensed and the joint part of the arc tube holder is smaller, and therefore the amalgam in the above-mentioned condensation section moves toward the arc tube. Also, rapid evaporation of a large amount is prevented.

(Example) The present invention will be described below based on an example shown in the drawings.

FIG. 3 shows the entirety of a 150W class high-pressure sodium lamp. In the figure, 1 is an outer tube made of hard glass or the like, and has a BT shape with a cap 2 attached to one end. This outer tube 1 houses an arc tube 3.

The arc tube 3 has a structure whose end portion is shown enlarged in FIGS. 1 and 2. That is, the arc tube 3 is closed by airtightly joining an end plate 4 made of an alumina disk or niobium as a closing wall to the end of a bulb made of a ceramic tube such as polycrystalline alumina or single crystal alumina using glass solder or the like. has been done.

In such an arc tube 3, a predetermined amount of sodium that becomes surplus during lighting, mercury as a buffer gas metal, and 1
It is filled with xenon gas or neon-argon Penning gas at about 0 to 300 torr.

As shown in FIGS. 1 and 2, the end plate 4 on one end is airtightly penetrated by an exhaust thin tube 5 made of niobium as an electricity introduction body, and the end plate 4 on the other end has a third As shown in the figure, an electrode shaft 7 serving as an electricity introduction body is passed through directly and airtight.

An electrode 6 is connected to the exhaust tube 5 at its end on the arc tube 3 side.

The electrode 6 is composed of an electrode shaft 7 made of tungsten and an electrode coil 8 made of tungsten wound in two layers around the chisel electrode 1d17. Emitters like .

The exhaust thin tube 5 is crushed in the middle to clamp the electrode shaft 7, and this clamp portion 6a allows the exhaust thin tube 5 to connect to the electrode 6.
mechanically supported and electrically connected. In addition,
This clamp portion 5a has a gap that connects the tip of the exhaust thin tube 5 and the arc tube 3 side. The tip of the exhaust thin tube 5 is hermetically sealed by welding after being crushed, and a condensation section where excess sodium condenses and accumulates, that is, a pool section 5b of the amalgam 15, is formed near the sealed end. ing. The condensing portion 5b has a predetermined volume for storing the surplus amalgam, and therefore has a predetermined cross-sectional area. Between this condensation part 5b and the clamp part 5a, there is a space on the proximal end of the thin tube 5 with respect to the liquid level of the amalgam 15 condensed in the condensation part 5b, that is,
A throttle passage 5c having a cross-sectional area narrower than that of the condensing part 6b is formed on the arc tube 3 side, more specifically on the clamp part 5a side. This throttle passage 5c restricts the movement of the amalgam 15 condensed in the condensing section 5b.

Both ends of such an arc tube 3 are joined to arc tube holders 10a and 10b which also serve as electric supply lines.

That is, the exhaust thin tube 5 protruding from one end of the arc tube 3
On the outer surface of the arc tube holder 10a, one arc tube holder 10a is intersected and spot welded, and on the outer surface of the electrode shaft 7 protruding from the other end of the arc tube 3, the other arc tube holder 10a is intersected and spot welded. Spot welded.

These arc tube holders 10a and 10b are joined to support wires lla and llb, respectively, and these support wires lla and llb are connected to the sealing support wire 12aS12.
b, and these sealing support wires 12a, 12b are sealed to the stem 13.

Therefore, both ends of the arc tube 3 are connected via support wires 10a and 10b made of the above-mentioned wires.
an arc tube holder 10a-, which is mechanically supported by a and llb, and an exhaust capillary 5 and an electrode shaft 7, which serve as electricity introduction bodies, serve as a power supply body;

10b.

In this embodiment, the arc tube holder 10a connected to the exhaust capillary 5 is attached to the side surface of the throttle passage 5c formed in the capillary 5. That is, the arc tube holder 10
As shown in FIGS. 1 and 2, a is located closer to the end of the arc tube 3, that is, closer to the clamp portion 5a than the liquid level of the amalgam 15 condensed in the condensation portion 5b of the exhaust capillary 5. It is welded to the exhaust thin tube 5.

Specifically, in the case of a 150W high-pressure sodium lamp, 30mg of amalgam is sealed, and the exhaust capillary 5 is made of niobium with an inner diameter of 2.5a+g. The arc tube holder 10g has a throttle passage 5c of the exhaust thin tube 5.
Bonded to the outside.

Note that when the arc tube holder 10a is joined to the tip of the exhaust tube 5, the tip of the exhaust tube 5 is sealed by crushing and welding, so the welding of the arc tube holder 10a seals the sealing part. This is not good as it will cause defects and cause leaks.

In a high-pressure sodium lamp having such a configuration, the coldest part occurs at the tip, ie, the lower end, of the exhaust capillary 5 which faces downward during lighting. Therefore, the amalgam 15 accumulates in the condensing portion 5b formed at the tip, that is, the lower end, of the exhaust thin tube 5.

The exhaust thin tube 5 is provided with a throttle passage 5C located closer to the end of the arc tube 3 than the liquid level of the amalgam 15 and having a cross-sectional area narrower than the cross-sectional area of the condensing part 5b.
The constriction passage 5C prevents or restricts the movement of the amalgam 15, which has a high mixing ratio of sodium and therefore has a high fluidity, and has accumulated in the condensing part 5b due to impact during lamp lighting, toward the arc tube 3 side. be able to. This prevents the amalgam 15 from coming into contact with the high temperature portion of the thin tube 5.

For example, if the amalgam 15 in the condensing section 5b is
Even when moving to the c side, the arc tube holder 10a is joined to the side of this constriction passage 5c, and the heat of the thin tube 5 is released through this arc tube holder 10a, and the temperature of the thin tube at this location decreases. In other words, the temperature difference in the thin tube 5 is small between the reservoir section 5b, which is the coldest section where the amalgam 15 is condensed, and the aperture passage 5c section, where the arc tube holder 10a is joined. Even if the amalgam 15 in the condensing section 5b moves toward the proximal end of the thin tube 5, a temperature rise is prevented. This prevents a sudden and large amount of evaporation of the amalgam, thereby preventing a sudden rise in the vapor pressure of sodium.

Therefore, it is possible to prevent changes in luminous efficiency and color rendering properties and fluctuations in lamp voltage, and it is possible to prevent the lamp from turning off.

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

That is, in the above embodiment, the exhaust thin tube 5 was provided protruding from only one end of the arc tube 3, but the exhaust thin tube 5 may be provided protruding from both ends.

Further, the thin tube is not necessarily used for exhaust gas, but may be provided to protrude simply for the purpose of forming the coldest part.

Furthermore, the closing wall that closes the end of the arc tube 3 may be an end cap made of niobium.

Furthermore, the luminescent metal is not limited to sodium.

[Effects of the Invention] As explained above, according to the present invention, since the aperture passage is provided closer to the arc tube than the liquid level of the luminescent metal, the amalgam in the condensation part can be prevented even if it receives an impact while the lamp is lit. The movement of the liquid to the arc tube side is reduced. Even if the amalgam in the condensation part moves to the arc tube side, the arc tube holder is connected to this destination, so the temperature of the capillary at this location is lowered, and the amalgam reservoir part of the capillary and the above The temperature difference with the joint part of the arc tube holder is small, and even if the amalgam in the condensation part moves toward the arc tube side, it is prevented from evaporating a large amount suddenly. Therefore, fluctuations in vapor pressure can be prevented, and fluctuations in lamp characteristics such as luminous efficiency and color rendering properties and lamp voltage vL can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the end of the arc tube of a high-pressure sodium lamp showing an embodiment of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is the entire high-pressure sodium lamp. FIG. 1... Outer tube, 3... Arc tube, 5... Exhaust tube, 5
a... Clamp part, 5b... Condensation part (reservoir part) 5c
...Aperture passage, 6...Electrode, 10a, 10b...
Arc tube holder that also serves as a power supply 11a, llb...Support wire, 15...Amalgam.

Claims (1)

[Claims] A capillary is airtightly connected to the end of an arc tube made of translucent ceramics, an electrode is attached to this capillary, this capillary is joined to an arc tube holder that also serves as a power supply, and the capillary is connected to an arc tube holder that also serves as a power supply. Electricity is supplied to the electrode through the capillary, and a luminescent metal and a starting rare gas that evaporate during lighting are sealed in the arc tube, and the luminescent metal that becomes surplus during lighting is condensed at the end of the capillary. In the ceramic discharge lamp, the capillary has a cross-sectional area that is located closer to the arc tube than the liquid level of the luminescent metal condensed at the end of the capillary and is narrower than the cross-sectional area of the luminescent metal condensation part. What is claimed is: 1. A ceramic discharge lamp characterized in that a constriction passage forming a shape is provided, and the arc tube holder is bonded to a location located closer to the arc tube than the liquid surface of the luminescent metal condensed at the end of the capillary.