JPS6254233B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a compact high pressure sodium lamp that is started by a starter tube or solid state (semiconductor) lighting element. High color rendering high pressure sodium lamps (150-400W) using translucent alumina arc tubes have already been commercialized. This lamp has a larger inner diameter than the arc tube of conventional high-pressure sodium lamps, and has a much higher sodium vapor pressure inside the arc tube during lamp operation, producing a warm light color similar to that of an incandescent light bulb. It has excellent color rendering properties.
This lamp has 3 to 4 times the brightness of a light bulb (40 to 60 lm/W), and the arc tube contains neon gas containing approximately 0.5% argon gas to enable low-voltage starting. −Argon mixed gas is about 20~
It is an energy-saving, high-intensity lamp that is encapsulated with 30 Torr and fully meets the current social demands for energy conservation. Incidentally, recently, there has been a growing trend to further promote energy conservation in the field of lighting. Specifically, I would like to replace low-wattage, low-efficiency incandescent light bulbs with small, compact discharge lamps that still take advantage of the features of incandescent electricity, and that also have 100 to 120 V.
There is a desire to use a simple lighting device with a commercial power source. It is extremely difficult to find other discharge lamps that have the potential to meet such strict demands, and in this sense, the above-mentioned high color rendering high pressure sodium lamp is
It can be said that it is the only discharge lamp. Under these circumstances, the applicant first applied 20 to 100W.
Under the rated lamp power of , the lamp efficiency is 40lm/
We are proposing a compact high-pressure sodium lamp with high color rendering properties and higher efficiency than W. This lamp is designed with an effective lamp voltage of around 50V, so once the lamp is started, it is a discharge lamp that can be lit using an AC 100-120V commercial power source using an inductance ballast. In this way, the compact high-color-rendering high-pressure sodium lamp already satisfies the major requirements for a compact discharge lamp to replace incandescent bulbs, as described above, but it is difficult to actually use this lamp as a product. The following two problems must be solved in order for the technology to become widely used in the market. One is the problem with the starting characteristics of the lamp.
The other problem is the lifetime characteristics of the lamp. The present invention has been made in view of these problems, and it is an object of the present invention to provide a compact high-pressure sodium lamp that can be reliably started with a commercial power supply of 100 to 120 V and has excellent life characteristics. The former problem originates from the starting rare gas sealed in the arc tube of the above-mentioned small high color rendering high pressure sodium lamp. In other words, in the case of small lamps, in accordance with the design of 150 to 400W high color rendering high pressure sodium lamps that have already been commercialized, neon-argon mixed gas containing about 0.5% argon gas is heated at 25 Torr with the aim of low voltage starting. Even if the lamp was sealed in an arc tube, it was impossible to reliably start the lamp with a commercial power supply of 100 to 120V. This situation could not be improved even if some kind of starting aid means was provided to the arc tube, as has been widely used in the past. However, solving this problem itself is not very difficult. for example,
The use of lighting tubes or solid state (semiconductor) lighting elements such as those used in fluorescent lamps. If this lighting tube is placed in parallel with the lamp and in series with the ballast, a high pulse voltage of 1 to 2 kV induced in the ballast's inductance will be applied to the lamp when the lighting tube is shut off. Starts reliably. This method of using a lighting tube is superior to other methods of incorporating an igniter into a ballast or of mounting a bimetallic switch in the lamp outer tube in that it does not impair the characteristics of a compact lamp. In this way, although the starting of the lamp can be solved, the latter problem regarding lamp life characteristics remains unsolved. In other words, in the case of a compact high-color-rendering high-pressure sodium lamp with a low rated lamp power of 20 to 100 W, the inner diameter of the arc tube is much smaller than that of a 150 to 400 W lamp, which is already commercially available. As a result, the distance between the inner wall of the arc tube and the electrodes has become smaller, and as a result, the current
If a starting rare gas of the same type, composition ratio, and filling pressure as used in a 150-400W lamp is filled, it will be difficult to transition from glow discharge to arc discharge when starting the lamp, resulting in scattering of electrode material. is becoming more intense. As a result, the luminous flux decreases significantly during its life. Therefore, the inventors focused on the mixing ratio and the sealing pressure of the starting rare gas, and conducted experiments and studies on the relationship between these and lamp life characteristics. Hereinafter, the present invention will be explained in detail with reference to the drawings. Figure 1 shows a longitudinal section of the alumina arc tube of the 50W high color rendering high pressure sodium lamp used in the experiment. In the figure, reference numeral 1 denotes an arc tube made of alumina and having an inner diameter φ of 4.7 mm, and niobium tubes 4 and 5 are sealed to both ends of the tube through end rings 2 and 3 made of alumina. Electrodes 6 and 7 are held at the tips of the niobium tubes 4 and 5, and the shortest distance d between these electrodes is 10.0 mm. Luminous tube 1
Inside, a sodium amalgam 8 with a sodium molar ratio of 78% and a neon-argon mixed gas as a starting rare gas are sealed. 9 and 10 are thermal protection films made of tantalum attached to the outer periphery of both ends of the arc tube 1, and when the lamp is operating, heat and light radiated from the inside of the arc tube 1, especially the electrodes 6 and 7, are formed behind the electrodes. It functions to increase the temperature of the coldest point of the arc tube by confining it to the coldest point of the arc tube. When conducting the experiment in this example, the lamp voltage was set in advance.
Color temperature under constant 45V and 50W lamp power
2500K, with an average color rendering index Ra of 80 or higher,
The lengths of the thermal protection films 9 and 10 in the longitudinal direction of the arc tube 1 are adjusted in advance. A lamp was manufactured by filling the arc tube 1 shown in Fig. 1 described above with neon-argon mixed gas at various mixing ratios as a starting rare gas at several levels in the range of 20 Torr to 500 Torr, and first, the lamp was lit. A lamp starting test was conducted using the tube. FIG. 2 is an electrical circuit diagram of a high-pressure sodium lamp in which a lighting tube 21 and a single-choke ballast 22 were used to conduct a starting experiment of a high-pressure sodium lamp in which the arc tube 1 was incorporated in the outer bulb 23. In this experiment, the lighting tube 21
A current limiting resistor 24 was inserted to control the interrupting current. Further, in this experiment, a power source 25 of 100 V AC was applied to the lamp. As a result of the experiment, lamps can be started reliably when the pressure of the neon-argon mixed gas is 25 Torr or more and 300 Torr or less, and the argon partial pressure ratio of this mixed gas is 75% or less. It was hot. Next, we conducted a rated lighting test on a lamp that can be started reliably in this way, and measured the luminous flux maintenance rate of the lamp after 9,000 hours of operation, which is the lamp's lifespan, and the results shown in the table below were obtained. .

[Table] 〓Unit:%〓
As is clear from the above table, even at the end of the lamp life, the total pressure of the neon-argon mixed gas, which is the starting rare gas sealed in the arc tube 1, must be kept at 50 Torr or more and 300 Torr or less, and the argon gas proportion in the mixed gas must be By setting the partial pressure ratio to 50% or more and 75% or less, the luminous flux maintenance factor can be significantly improved. The above results were obtained through experiments on a small high-color-rendering high-pressure sodium lamp having an arc tube 1 with a minimum distance d between electrodes of 10.0 mm and an inner diameter φ of 4.7 mm. It has been confirmed that, as long as the above-mentioned arc tube has a diameter of 7 mm or less, the same effect can be obtained not only in the above-mentioned high color rendering high pressure sodium lamp but also in a general high pressure sodium lamp. It goes without saying that a solid-state lighting element may be used instead of the lighting tube. As explained above, the high pressure sodium lamp of the present invention is 20 to 100 W, has electrodes at both ends, the shortest distance between the electrodes is 25 mm or less, and uses neon-argon as the starting rare gas. It is equipped with an arc tube with an inner diameter of 7 mm or less filled with a mixed gas, and a lighting tube or solid lighting element for applying a start to the arc tube, and when the pressure of the neon-argon mixed gas is 50 Torr or more and 300 Torr or less. and the partial pressure ratio of argon gas in the neon-argon mixed gas is in the range of 50% or more and 75% or less, and therefore 100 to 120V
It goes without saying that the lamp can be started reliably even with a commercial power source of 1000 yen, and the scattering of the electrode material at the time of lamp starting is greatly suppressed, resulting in extremely excellent life characteristics.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an arc tube of a high-pressure sodium lamp according to the present invention, and FIG. 2 is a lighting circuit diagram of a high-pressure sodium lamp according to an embodiment of the present invention. 1... Arc tube, 2, 3... End ring, 4,
5... Niobium tube, 6, 7... Electrode, 8... Sodium amalgam, 9, 10... Heat protection film, 21...
...lighting tube, 23...outer tube, 25...power supply.

Claims (1)

[Claims] 1. An arc tube with an inner diameter of 7 mm or less, which is provided with electrodes at both ends, the shortest distance between the electrodes is 25 mm or less, and is filled with neon-argon mixed gas as a starting rare gas, and this arc tube has an internal diameter of 7 mm or less. 20~ equipped with a lighting tube or solid state lighting element for applying voltage and lit with a power supply voltage of 100~120V
It is a 100W high-pressure sodium lamp, and the sealed pressure of the neon-argon mixed gas is 50 Torr or more and 300 Torr or less, and the partial pressure ratio of argon gas to the neon-argon mixed gas is
A high-pressure sodium lamp characterized by a range of 50% or more and 75% or less.