JPS6038820B2 - High pressure sodium lamp and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION High-pressure sodium lamps, in which sodium, mercury, and a starting rare gas are sealed in an alumina ceramic arc tube, are widely used for general lighting purposes.

Conventional lamps of this kind are so-called saturated vapor pressure discharge lamps, in which the amount of fill material exceeds the amount that evaporates in the arc tube, and most of the sodium is stored together with mercury as surplus amalgam in the coldest part of the arc tube. For this reason, the sodium vapor pressure within the arc tube fluctuates in response to changes in the temperature of the coldest part within the arc tube, resulting in large fluctuations in the lamp lighting characteristics, particularly the tube voltage. By limiting the amount of sodium and mercury contained in the tube and making it a so-called unsaturated vapor pressure type, in which all of the sodium and mercury is evaporated in the lit state, the vapor pressure inside the tube hardly changes even if the temperature at the innermost part changes.
Therefore, it is already known that the tube voltage becomes stable when the lamp is lit. Therefore, the maximum allowable amount of inclusions can be calculated to some extent. However, in order to complete this type of unsaturated vapor pressure type high-pressure sodium lamp, it is necessary to fill in an extremely large amount of filler material, and sodium is an extremely chemically active element that readily oxidizes in the air, and mercury Due to difficulties in encapsulation technology, such as the difficulty in producing precise amounts of microparticles due to their relative gravity and large surface tension,
The appropriate amount of inclusion was not set correctly.

In order for a discharge lamp to be put to practical use, it must not only have a suitable light color and an economical efficiency, but also have lamp characteristics that allow it to be operated with an economical ballast. In the case of unsaturated vapor pressure discharge lamps, these factors are primarily determined by the amount of fill material, so it is an essential condition to uniformly fill each lamp with an optimum amount of fill material. The inventors investigated the relationship between the amount of charged sodium and mercury and the characteristics of the lamp by making full use of an encapsulation technique that accurately and completely excluded the shadows of air and other impurities. We were able to set the optimal amount of inclusion. In other words, the amount of sodium is 0.0 per area in the arc tube.
07 ta to 0.018 9 preferably < is 0.01 9 to 0.01&9, and mercury silver is also 0.05 per 1
A practically suitable unsaturated vapor pressure type high-pressure sodium lamp could be completed by setting the ratio to 4.9 or more and 0.6 to less than 9.

The details of the present invention will be explained with reference to the drawings with reference to concrete examples.

FIG. 1 is a partially cutaway front view of a high-pressure sodium lamp arc tube, and the structure of the conventional one and the unsaturated vapor pressure type according to the present invention are basically the same.

1 is a translucent alumina tube, which may be a polycrystalline alumina ceramic tube, but a single crystal alumina (sapphire) tube has better stability of lamp characteristics during its life.

2, 2 is a closed body made of alumina, 3, 3 is a closed body 2,
A tungsten electrode 4 penetrates through the center hole of 2 and is attached to the inner end surface.
These three sections are hermetically sealed to each other using a ceramic brazing material.

FIG. 2 is a front view of the main parts of the arc tube in the process of being manufactured to explain the method of enclosing the required inclusions, and the same reference numerals as in FIG. 1 indicate the same parts. Sodium azide NaN3, which is a compound of sodium and nitrogen, is a white powder that is stable in air at room temperature and is easily soluble in water, but it is better to dissolve it in methyl alcohol to avoid evaporation and drying of the solvent.

For example, dissolve 0.5 parts of sodium azide in 100 parts of methyl alcohol. Arc tube 1 for 400 watt lamp
For books, 0.04' of this solution is injected into the enclosure container 5 using a small syringe.

The enclosure container 5 is made of a heat-resistant metal such as stainless steel and molded into a cup shape or a long tube shape with one end closed. By drying this product at room temperature or heating, the solvent methyl alcohol evaporates and sodium azide remains in the container 5 in an amount of 50%.
X shell:.・It's 2 of 9. Next, a ternary alloy of aluminum-zirconium-mercury (AI-Zr per day) was placed in a container 5.
Insert into.

It is convenient to use the alloy manufactured in accordance with US Pat. No. 3,203,901, etc., which is commercially available as "Mercury Dispenser" in the form of a powder or a molded product. Nine out of ten of this material is charged into container 5. What is shown with reference numeral 6 in FIG. 2 is a mixture of sodium azide and a Mercury dispenser. In the arc tube that is being manufactured, the outer ends of the exhaust pipes 3 and 3 are both open □, and the container 5 containing the mixed filler 6 is inserted from the closed end of one of the exhaust pipes 3, The parts are sealed and closed by crimping and melting. The other end of the exhaust pipe 3' is connected to an exhaust system (not shown) to evacuate the interior of the arc tube. Next, the portion of the exhaust pipe 3 that accommodates the container 5 is approximately 400 mm
Heat to ℃. At this time, NaN3 in the container 5 generates elemental sodium and nitrogen gas through a thermal decomposition reaction according to the following equation. state aN3 - a + state 2 The amount of sodium generated from 0.2 9 NaN3 in container 5 is quantitatively 0.07 9.

The N2 gas generated at the same time is exhausted through the exhaust pipe 3'. Next, when the exhaust pipe 3 is heated to about 700 oo, mercury is separated from the Mercury dispenser. About 2nd grade mercury is separated from Alloy 10-9.

The generated sodium and mercury evaporate due to the high temperature and escape from the exhaust pipe 3, and are kept at a low temperature. Luminous tube 1
deposited inside the. Next, the exhaust pipe 3 is cooled and the exhaust pipe 3'
After 20 torr of xenon is introduced into the arc tube as a starting gas, the exhaust pipes 3, 3' are sealed by pressing and melting at a predetermined length. The first charged container 5 is the exhauster 3
It is possible that the material is in the fused and removed portion and does not remain inside the completed arc tube, but it may be actually rotated so that it remains inside the arc tube. The above-mentioned encapsulation operation can also be performed by partially changing the actual rotation mode, but
In short, by using sodium azide, the encapsulation process can be carried out industrially under precise quantitative control without contaminating the collected sodium with impurities. Further, by using a Mercury dispenser, a minute amount of mercury can be easily and quantitatively encapsulated. In this way, a completed arc tube product as shown in Figure 1 is produced, and this arc tube is mechanically mounted inside the outer sphere of the glass product in the conventional manner, and the electrical connections are made to give an appearance. A lamp similar to the conventional high-pressure sodium lamp is completed. When this lamp is lit using a compatible ballast and the relationship curve between the response current and tube voltage is drawn, as shown in Figure 3 a, while the tube current is small, the tube voltage increases as the tube current increases. When the tube current reaches a certain value, the tube voltage will maintain a constant value even if the tube current increases further. This refraction point C is the point at which all the contents in the tube have completely evaporated, and the area to the right of point C indicates an unsaturated vapor pressure type lighting state. If the rated output of this lamp is 400 watts, the basic feature of the present invention is that the point D at which the tube power is 400 watts is a flat linear portion of the tube voltage, that is, the unsaturated vapor pressure type lighting state. On the other hand, in conventional high-pressure sodium lamps, the tube voltage increases as the tube current increases, as shown in FIG. 3b. If the value of tube voltage indicating an unsaturated state is expressed as Vsa, Vsa is determined by the amounts of Na and Hg enclosed. As the amount of Na increases, the value of Vsa increases, but at the same time, the spectral characteristics of light emission change, and the efficiency and color rendering properties also change. Although the value of Vsa increases with an increase in the amount of Hg, it does not significantly affect the spectral characteristics of light emission. Therefore, it is convenient to determine the amount of Na included so that the efficiency and color rendering properties have practical values, and then determine the amount of Hg so that Vsa becomes an appropriate value. If the value of Vsa is too high or too low, the ballast used will be extremely expensive and impractical.

The economical Vsa range is 70V to 140V. In the case of the 400 watt lamp mentioned in the practical example, Na is 0.07.
9, Hg is 2 of 9. The contents of this arc tube are 5.
It is the 6th one and the amount of inclusion per 1 is Nao. 0126 evening Hg
0.357 claw 9. This lamp has a rated power of 400 watts, Vsa=110V, and a tube current of 4.3
A, an efficiency of 1101 m/w, and a color rendering property comparable to that of the conventional method were obtained. As a result of experiments conducted on various lamp models and lamps with different arc tube specifications, it was found that if the amount of Na filled in was less than 9 of 0.007 per 1 part of the customer fin in the arc tube, the luminous efficiency would be low; If it is greater than 9, the stability of the lamp life will be poor.

Preferably, 9 of 0.01 to 9 of 0.018 is optimal. In addition, the amount of Hg enclosed is 0.05 per 1 in the arc tube.
If it is less than 4 female, the tube voltage adjustment ability will be insufficient, and if it is 0.6 or more, the tube voltage will be too high and it will be impossible to light it with an economical ballast, and the light color of the lamp will be affected. has a red tinge and is not suitable for general lighting. It is clear from the test results described below that such inconvenience occurs. The reason why the light color of the lamp is red is not clear at present, but it may be because the concentration gradient of sodium atoms changes due to the high concentration of mercury atoms, or because the concentration gradient of sodium atoms changes due to the high concentration of mercury atoms.
This is probably because the spectral distribution changes due to the generation of a molecules. Next, several examples of characteristics when lamps were completed using the arc tubes described in the practical example with various filling amounts and operated at 400 W will be shown first. In Table 1, the lamp voltage change during the life is 4 for the prototype lamp.
The table shows the change in lamp voltage (average value for each 3 lamps) per 100 bait hours of lighting time when a life test was conducted with a 00W ballast (a ballast whose lamp power is 400W when the lamp voltage is 100V).

If this value is smaller than -2.5, the lamp voltage after lighting for 1200 hours will drop by 30V or more compared to the initial lamp voltage, which is not preferred in practice. In addition, the following was found from Table 1.

m To obtain a practical efficiency of 100〆/W or more,
The amount of Na enclosed must be 0.007 mg/or more.

■ In order to obtain practical life characteristics, the amount of Na enclosed must be 0.018 mg/c or less.

[3] In order to obtain a practical lamp voltage range (70 to 140V), the lamp voltage value for the combination of the upper limit of the amount of Na and the lower limit of the amount of Hg must be set to the lower limit of the lamp voltage (70V). Must be above.

That is, the lower limit of the amount of Hg enclosed is 9/9 of 0.054. 'B - The lamp voltage for the combination of the lower limit of the Na charge amount and the upper limit of the H history charge amount is the upper limit of the lamp voltage (
140V) or less.

That is, the upper limit of the amount of Hg enclosed must be 0.6 9/Earth. By regulating the fill amount as described above, we have commercialized an economical unsaturated vapor pressure lamp that has the characteristics of high-pressure sodium lamps, such as high efficiency of 100 Sodium/W or more, good color rendering properties, and long-term stability. Its industrial value is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a front view of a high-pressure sodium lamp arc tube with some parts missing; Fig. 2 is a front view of an unfinished arc tube in the middle of manufacture for explaining the enclosing operation of an example of the present invention; FIG. 3 is a diagram showing the relationship between tube current and tube voltage of a high-pressure sodium lamp, where curve a is for the unsaturated vapor pressure type according to the present invention, and curve b is for the conventional unsaturated vapor pressure type. 1... Translucent alumina tube, 2, 2'... Sealing body, 3, 3
'Exhaust pipe, 4... Electrode, 6... Mixed inclusions. A picture of burying two heads.

Claims (1)

[Scope of Claims] 1. Sodium, mercury, and an inert starting gas are sealed in an arc tube made of a heat-resistant, light-transmitting tube body, and these filled materials are lit in a lighting state at or close to the rating specified for the lamp. In an unsaturated vapor pressure type high-pressure sodium lamp that evaporates all of the
A high-pressure sodium lamp characterized in that 0.007 mg to 0.018 mg of mercury is filled per cm^3, and 0.054 mg or more and less than 0.6 mg of mercury per cm^3. 2. Sodium in the arc tube made of a heat-resistant, light-transmitting tube at a concentration of 0.007 mg to 0.01 per cm^3 of the arc tube interior.
8mg, mercury of 0.054mg to 0.6mg per 1cm^3, and an inert gas for starting,
In a lamp that evaporates all of these substances under lighting conditions that are at or close to the specified rating for the lamp, a predetermined amount of a dilute solution of sodium azide, NaN_3, is inserted into the arc tube or the part that communicates with the arc tube, and the The diluted solution is dried in an active gas atmosphere or in a vacuum, and then a predetermined amount of sodium is sealed in the arc tube using a reaction in which sodium is liberated by heating this part. Method of manufacturing high pressure sodium lamps.