JPH0613038A - High voltage sodium lamp and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a high voltage sodium lamp and a method for manufacturing it in which a high Na vapor pressure state can be easily formed in a light emitting tube. CONSTITUTION:In a light emitting tube 1 consisting of light permeable ceramics, an excessive Na-Hg amalgam 9 and a mercury getter 10 which combines with mercury to form an alloy, and also regulates the evaporation of mercury are sealed. Since the mercury getter sealed in the light emitting tube adsorbs the Hg released from the excessively sealed Na amalgam, mercury vapor pressure is reduced, and Na vapor pressure is consequently increased, whereby color rendering property is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-pressure sodium lamp in which sodium is enclosed in an arc tube made of translucent ceramics and a manufacturing method.

[0002]

2. Description of the Related Art A high-pressure sodium lamp contains a ceramic arc tube made of translucent alumina or the like in an outer tube. The arc tube has electrodes sealed at both ends and sodium Na as a light emitting substance and a buffer. Mercury Hg as a gas metal, and xenon Xe as a starting rare gas,
It is known as a lamp suitable for energy saving because it is filled with argon Ar, neon Ne, etc. and has the highest luminous efficiency among various discharge lamps.

However, the conventional high-pressure sodium lamp has a problem that the color rendering property is low and is not necessarily suitable for indoor lighting. Therefore, development of a high-pressure sodium lamp with improved color rendering is desired. In order to improve the color rendering property, it is necessary to increase the vapor pressure of Na during lighting. Therefore, it is effective to enclose Na excessively and heat the Na to promote evaporation.

By the way, when Na and mercury Hg are enclosed in the arc tube, an amalgam of Na and Hg is formed in advance,
A method of encapsulating in the form of such an amalgam is adopted. When Na-Hg is encapsulated in the form of amalgam,
It is possible to reduce the variation in the enclosed amount, it is easy to manage the enclosed ratio and the enclosed total amount with high accuracy, and the solid form makes the handling easy, and the enclosing work is easy.

However, recently, as described above, there has been a demand for improvement in the color rendering properties of the high-pressure sodium lamp, and the chromaticity point is set to BBL (Black Body Lin).
Research is underway to obtain a light color close to natural color by approaching e). In order to enhance the color rendering of this type of lamp, as described above, it is sufficient to increase the Na vapor pressure during lighting. For this purpose, the amount of Na enclosed in the arc tube is compared with the amount of Hg enclosed. It is necessary to increase the relative amount of Na by 25% or more by weight. Therefore, when Na-Hg amalgam is used, it is necessary to use amalgam having a high Na weight ratio.

[0006]

However, when the weight ratio of sodium exceeds 25% by weight, Na-Hg amalgam does not solidify at room temperature and must be handled in a liquid state, and the weighing tends to vary. However, there is a problem that it becomes difficult to manage the enclosed amount with high accuracy, and moreover, the enclosing work requires time and labor.

As a means for increasing the encapsulation ratio of Na in the arc tube, an amalgam having a high Na component ratio is surrounded by an amalgam having a low Na component ratio to form a pellet having a two-layer structure,
A technique for enclosing the pellets in the arc tube has been proposed. However, at the current level of alloy production technology, it is difficult to produce amalgam pellets having a two-layer structure in which the respective component ratios are constant, and the above means is difficult to realize.

As another means, amalgam having a low Na component ratio and Na such as sodium azide or sodium chromate can be decomposed and released at high temperature.
A technique for encapsulating the compound a in a light emitting tube and decomposing and releasing Na at a high temperature in the light emitting tube to increase the amount of Na enclosed in the light emitting tube has also been announced. However, in this case, it is necessary to remove decomposed N2 gas and residual chromium oxide into the arc tube, and this elimination work requires time and it is difficult to reliably extract only the residual substance.

As another means, a method is known in which liquid amalgam having a high Na component ratio is placed in a container of cadmium Cd to be encapsulated, and the capsule is placed in an arc tube and heated to melt and destroy Cd. There is. However, in this case, since Cd also emits light, this emission adversely affects the color misregistration and the emission efficiency.

The present invention has been made in view of the above circumstances. An object of the present invention is to use a solid form of Na-Hg amalgam which is easy to control the amount of inclusion and is convenient to handle. Moreover, it is an object of the present invention to provide a high pressure sodium lamp that can easily create a high Na ratio in the arc tube and a method for manufacturing the same.

[0011]

The high-pressure sodium lamp of the present invention comprises an arc tube made of translucent ceramics, and N
In a high-pressure sodium lamp in which a-Hg amalgam and a starting rare gas are sealed, in the arc tube, in addition to the excess amalgam and the starting rare gas that are vaporized during lighting, the alloy is combined with mercury to form an alloy. And this alloy forms a mercury getter, eg silver Ag, zinc Zn, which regulates the evaporation of mercury from this alloy at normal operating temperatures of the lamp.
At least one of magnesium Mg is encapsulated.

Further, according to the manufacturing method of the present invention, sodium amalgam, which is made of a solid phase body that is more than that which is vaporized during lighting, a rare gas for starting, and mercury are combined in an arc tube made of translucent ceramics. To form an alloy, and this alloy encapsulates a mercury getter consisting of a solid phase body that regulates the evaporation of mercury from this alloy at the temperature during normal operation of the lamp, after which the sodium amalgam and mercury getter are encapsulated. It is characterized in that sodium and mercury are evaporated from the sodium amalgam by heating and the mercury vapor is adsorbed by the mercury getter to form an alloy.

[0013]

According to the structure of the present invention, since the mercury getter enclosed in the arc tube adsorbs Hg released from the excessively enclosed amalgam to form an alloy, the amount of mercury evaporated in the arc tube is reduced. The Na ratio becomes higher as a ratio. Therefore, the vapor pressure of Na is increased, the color rendering is improved, the chromaticity point is close to BBL, and a light color that is close to a natural color and does not feel unnatural can be obtained.

Further, according to the method of the present invention, the mercury getter enclosed in the arc tube adsorbs Hg released from the excessively enclosed amalgam to form an alloy, thereby increasing the Na ratio in the arc tube. Therefore, the vapor pressure of Na can be easily increased. Moreover, since the amalgam and the mercury getter can be encapsulated in the state of the solid phase, it is possible to reduce the variation in the encapsulated amount, the handling becomes easy, and the encapsulation work becomes easy.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. The figure shows an arc tube of a high-pressure sodium lamp, and the arc tube is usually housed in an outer tube (not shown) made of hard glass or the like to form a double tube structure. Arc tube
It has a valve 1 formed of a ceramic tube such as polycrystalline alumina or single crystal alumina, and the end portion of the valve 1 has end plates 2 and 2 made of alumina disk or niobium as a closing wall and a glass solder or the like. It is closed by hermetically bonding with the adhesive 3. Thin tubes 4 and 4 made of niobium tubes are penetrated through these end plates 2 and 2 as an electric introducer via an adhesive agent 5 such as glass solder. Electrodes 6 and 6 are bonded to these thin tubes 4 and 4, respectively. Each electrode 6 is composed of an electrode shaft 7 made of tungsten and an electrode coil 8 made of tungsten wound around the electrode shaft 7. Although not shown in the figure, the electrode coil 8 is made of Ba ₂ CaWO ₆ or the like. Various emitters are retained. The thin tubes 4 and 4 are crushed in the middle to clamp the electrode shaft 7, and the outer ends are hermetically sealed by welding after crushing.

In such an arc tube, a predetermined amount of sodium Na, mercury Hg as a metal for a buffer gas, and 1
Xenon Xe gas or neon N of about 0 to 300 torr
A rare gas such as a Penning gas of e-argon Ar is filled. The Na and Hg are enclosed in the arc tube, for example, in the thin tube 4 in the form of an amalgam 9, and in this case, the Na and Hg are enclosed in a surplus amount during lighting. Further, in the thin tube 4, a mercury getter 10 is enclosed in addition to the sodium amalgam 9 and the rare gas. The mercury getter 10 is made of, for example, at least one of silver Ag, zinc Zn, and magnesium Mg, and has a property of incorporating mercury to form an alloy. Moreover, the alloy formed by adsorbing mercury has a small release rate of adsorbed mercury, and the mercury vapor pressure of this alloy is lower than the mercury vapor pressure of the amalgam at the same temperature. For example, when Ag is used as the mercury getter 10, this Ag has a molar ratio of about 20% of mercury and is Ag-
Make an alloy of Hg. Since this alloy is in a solid state and there is almost no evaporation of mercury from this alloy, the residual mercury does not adversely affect the mercury vapor pressure in the arc tube 1. Further, Ag does not easily form an alloy with sodium, and therefore does not reduce the amount of Na.

For example, in the case of a 150 W high-pressure sodium lamp, electrodes 6 and 6 are sealed in a ceramic tube having an inner diameter of 8 mm with a distance between the electrodes of 32 mm, and each of the arc tubes contains 25% by weight of sodium. 6 amalgam 9 having a weight of 5 mg (30 mg in total), 5 mg of a mercury getter 10 made of Ag, and 30 torr of a neon-argon penning gas are enclosed. This lamp is
With 150W input, the lamp voltage is turned on at 100V.

In the high-pressure sodium lamp having such a structure, the Na amalgam 9 is enclosed in the thin tube 4 so that the amount of Na and Hg is more than the amount evaporated during lighting, and the mercury getter made of Ag. 10 is sealed in the thin tube 4, and the Na amalgam 9 and the mercury getter 10 are heated from the outside of the thin tube 4 by means of burner flame, high-frequency heating or the like to about 600 ° C. Is evaporated. Of these, mercury is a thin tube 4
Ag is absorbed by the mercury getter-10 housed at the lower end of the
Make an alloy of Hg. This Ag-Hg alloy is in a solid phase state in the temperature range of 600 to 700 ° C corresponding to the coldest temperature of the high-pressure sodium lamp, and the mercury taken therein is hardly evaporated or the evaporation thereof is extremely small.
Moreover, Ag is difficult to form an alloy with sodium, so Na
It does not reduce the quantity. Therefore, the mercury vapor is relatively small in the discharge space of the arc tube 1, and as a result, the vapor pressure of sodium is high. Therefore, it is possible to suppress an increase in the lamp voltage, keep the sodium emission spectrum high, and enhance the color rendering properties.

Moreover, since this lamp can handle both the amalgam 9 and the mercury getter 10 in the solid state, the enclosed amount can be regulated with high precision.
It is possible to prevent variations and facilitate the filling work. The results of experiments on the 150 W high-pressure sodium lamp will be described.

The structure and dimensions are as specified above 150
In a high-pressure sodium lamp of W, (A) 6 pieces of amalgam 9 each containing 25% by weight of sodium and having a weight of 5 mg and 7 pieces of mercury getter 10 composed of Ag were used.
mg of the lamp of the present invention and (B) sodium
Amalgam containing 5% by weight of 5 mg per piece
6 lamps, however, a conventional lamp not using the mercury getter 10, and (C) 28.9% by weight of liquid N
A conventional lamp in which a-Hg amalgam was enclosed and a mercury getter 10 was not used was manufactured, and the color rendering properties and the color temperature when each lamp was turned on were measured.

The first characteristic of these lamps is that the correlated color temperature is 2
The average color rendering index Ra at 500k is always 85.
Although it showed good color rendering properties, the result of investigation on color change during the life of 100 to 9000 hours showed that the lamp (A) of the present invention using the mercury getter 10 and 28.9% by weight of liquid amalgam were used. In the conventional lamp (C) in which is enclosed, the change in chromaticity is changed from (0,478,0,416) to (0,452,0,406), but the mercury getter 10 is not used ( The lamp of B) changes in chromaticity from (0,477,0,414) to (0,450,0,3).
98), and since the chromaticity points of the lamps of (A) and (C) change substantially along the BBL (Black Body Line), it is possible to obtain a light color that is close to the natural color and has no discomfort. , (B) became a pinkish and strange light at the end of its life. The closing wall that closes the end of the arc tube may be an end cap made of niobium.

[0022]

As described above, according to the structure of the present invention, the mercury getter enclosed in the arc tube adsorbs Hg released from the excessively enclosed amalgam to form an alloy. The mercury evaporation amount decreases and the Na ratio increases in proportion. Therefore, the vapor pressure of Na is increased, the color rendering is improved, the chromaticity point is close to BBL, and a light color that is close to a natural color and does not feel unnatural can be obtained.

According to the method of the present invention, the mercury getter enclosed in the arc tube adsorbs Hg released from the excessively enclosed amalgam to form an alloy, thereby increasing the Na ratio in the arc tube. Therefore, the vapor pressure of Na can be easily increased. Moreover, since the amalgam and the mercury getter can be encapsulated in the state of the solid phase, it is possible to reduce the variation in the encapsulated amount, the handling becomes easy, and the encapsulation work becomes easy.

[Brief description of drawings]

FIG. 1 is a sectional view of an arc tube of a high pressure sodium lamp showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Outer tube, 3 ... Arc tube, 4 ... Capillary tube, 6 ... Electrode, 9 ... Na
-Hg amalgam, 10 ... Mercury getter.

Claims (3)

[Claims] 1. A high-pressure sodium lamp in which an amalgam of sodium and a rare gas for starting are enclosed in an arc tube made of translucent ceramics, wherein an excess sodium amalgam is evaporated in the arc tube during lighting. In addition to the starting noble gas, a high pressure characterized by the fact that it combines with mercury to form an alloy and this alloy encapsulates a mercury getter that regulates the evaporation of mercury from this alloy at normal operating temperatures of the lamp. Sodium lamp. 2. The high pressure sodium lamp according to claim 1, wherein the mercury getter is made of at least one of silver, zinc, and magnesium. 3. An arc tube made of a translucent ceramic is combined with sodium amalgam made of a solid phase body, which is an excess of the solid state body evaporated during lighting, a rare gas for starting, and mercury to form an alloy. This alloy encapsulates a mercury getter consisting of a solid phase body that regulates the evaporation of mercury from this alloy at the temperature during normal operation of the lamp, and after encapsulation, the sodium amalgam and the mercury getter are heated to A method for producing a high-pressure sodium lamp, characterized in that sodium and mercury are evaporated, and the mercury vapor is adsorbed by the mercury getter to form an alloy.