JPS5838449A - High pressure sodium lamp - Google Patents

Abstract

PURPOSE:To aim at checking a scatter of electrode matter at the time of lamp starting and improving life characteristics, by sealing up a mixture of neon- krypton gases as a starting noble gas inside a luminous tube, while setting a partial pressure ratio of the krypton gas the sealed pressure to the specified value. CONSTITUTION:Niobic tubes 4 and 5 are sealed in both ends of a luminous tube 1 via end rings 2 and 3 made of alumina, etc., and electrodes 6 and 7 are held at each of their nose parts; the shortest distance d between these electrodes is set to be less than 25mm., and sodium amalgam 8 whose sodium molar ratio is 78% and the neon-krypton mixed gas serving as a starting noble gas are sealed up inside the luminous tube 1. The sealed pressure of this mixed gas is 30-250 torr while the partial pressure ratio of krypton gas contained in this mixed gas is set down to a range of 3-50%. A high pressure sodium lamp provided with a suchlike luminous tube is so designed that it can start with a starting lamp, a glow starter, and so on.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-pressure sodium lamp apparatus in which the lamp is started by a starter tube or a solid-state starter.

High color rendering high pressure sodium lamps (160 to 40 oW) 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. Furthermore, this lamp has a brightness of 40 to 6 olTn/W, which is 3 to 4 times as bright as a light bulb, and a neon lamp containing about 0, s% argon gas inside the arc tube to enable low voltage starting. Argon mixed gas is about 20-30 T
It can be said that it is an energy-saving, high-intensity lamp that more than satisfies today's 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 while retaining the characteristics of light bulbs, and if possible, I would like to use a simple lighting device with a 100-120V commercial power source. This is the request. It is extremely difficult to find other discharge lamps that have the potential to meet such strict demands, and the high color rendering high pressure sodium lamp mentioned above is the only discharge lamp in this sense. It can be said that there is. Under these circumstances, the applicant has previously proposed a compact, high-color-rendering, high-pressure sodium lamp with a lamp efficiency of more than 407 m/W at a rated lamp power of 20 to 1 oow. This lamp is designed with an effective lamp voltage of around 60V, so once the lamp starts,
This is a discharge lamp that can be lit using an inductance ballast using a commercial power supply of 00 to 120V.

In this way, this compact, high-color-rendering, high-pressure sodium lamp already satisfies the major requirements for a compact discharge lamp to replace incandescent bulbs, as mentioned above. The following two problems must be solved in order for the product to be commercialized and widely used in the market.The other problem is the problem of lamp life characteristics.

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 device 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 this small lamp, in accordance with the design of high-pressure sodium lamps with high color rendering properties of 160 to 400 W, which have already been commercialized, with the aim of starting at low voltage, 0.5%
Even if a neon-argon mixed gas containing about 25 Torr of argon gas is sealed in an arc tube, the
It was no longer possible to reliably start the lamp with ~120V utility power. This situation could not be improved even if some kind of starting aid means was provided for the arc tube, as has been widely used in the past.

However, solving this problem itself is not very difficult. For example, lighting tubes such as those used in fluorescent lamps may use solid state (semiconductor) lighting elements. If the lighting tube is placed in parallel with the lamp and in series with the ballast, the 1
Since a high pulsed voltage of ~2kV is applied to the lamp,
Starts reliably. This method of using a lighting tube is very superior to other methods of incorporating an igniter into a ballast or installing a bimetallic switch in the lamp outer tube in that it does not impair the characteristics of a small 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, as in the previous application, the inner diameter of the arc tube is much larger than that of a 150 to 400 W lamp that has already been commercialized. As the bulb becomes smaller, the distance between the inner wall of the arc tube and the electrode also becomes smaller, and for this reason, if the starting rare gas of the same type, composition ratio, and sealing pressure as currently used in 150-400W lamps is filled. 6.- means that the electrode material scatters violently when starting the lamp. 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 above-mentioned starting rare gas, and conducted experiments and studies on the relationship between these and the lamp life characteristics.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows a longitudinal section of an alumina arc tube of a 50 W 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 4.78 mm, and a niobium tube 4.6 is sealed at both ends of the tube with end rings 2.3 made of alumina interposed therebetween. Electrodes 6 and 7 are held at the tips of the niobium tubes 4 and 6, and the shortest distance d between these electrodes is 10. om. Inside the arc tube 1, the sodium molar ratio is 78.
The sodium amalgam 8 and a neon-krypton mixed gas as a starting rare gas are sealed. Reference numerals 9 and 10 denote thermal protection films made of tantalum, which are attached to the outer periphery of both ends of the arc tube 1 to prevent heat and light radiated from the interior of the arc tube 1, particularly from the electrodes 6 and 7, to the rear of the electrodes during lamp operation. In the experiment in this example, the color temperature was set to 2500 with the lamp voltage 45V and lamp power 5oW constant. The length of the thermal protection film 9.10 in the longitudinal direction of the arc tube 1 is adjusted in advance so that the average color rendering index Ra is higher than the illusion.

20 To
Lamps were manufactured in which the temperature was selected at several levels in the range from rr to 500 Torr, and a starting test of the lamp was first conducted using a lighting tube.

Figure 2 shows the electrical circuit diagram used in the IJ Umlamb startup experiment, in which a lighting tube 22 is connected in parallel with a high-pressure sodium lamp with an arc tube 1 built into the outer tube 21, and the In order to limit the current, a current limiting resistor 23 is connected in series with the lighting tube 22, and a power source 25 of AC 10 OV is applied to the lamp via a single choke ballast 24.

As a result of this experiment, the lamp can be started reliably if the pressure of the neon-krypton mixed gas is 2.
It was a lamp in which the temperature was 0 Torr or more and 2 ts OTorr or less, and the partial pressure ratio of krypton in the mixed gas was 60% or less. Next, we conducted a rated lighting test on a lamp that can be started reliably in this way, and the lamp life was 900.
When the luminous flux maintenance rate of the lamp was measured after lighting for 0 hours, the results shown in the table below were obtained [unit, chi]. As is clear from the table above, even at the end of the lamp life,
A lamp that can maintain a luminous flux at a practical level (60 inches or more) has a total pressure of 30 Torr or more, 250 Torr or more of the neon-krypton mixed gas, which is a rare starting gas, sealed in the arc tube
rr or less, and the partial pressure ratio of krypton gas in the mixed gas is in the range of 3% or more and rso% or less.

Among them, the luminous flux maintenance rate at the end of the lamp life is 70%.
The pressure of the mixed gas exceeds 40 Torr and does not pose any problem in practice when the pressure is 40 Torr or higher and 25° Torr.
It can be seen that the partial pressure ratio of krypton gas in this mixed gas is in the following range and is 5% or more and 50% or less.

The above results show that the shortest distance d between the electrodes is 10.01rIL,
This was obtained through experiments on a small high-color-rendering high-pressure sodium lamp having an arc tube 1 with an inner diameter φ of 4.7 u. It has been confirmed that the same results can be obtained not only with the above-mentioned high color rendering high pressure sodium lamp but also with general high pressure sodium lamps.

It goes without saying that a solid-state lighting element may be used instead of the lighting tube.

As explained above, the present invention is provided with electrodes at both ends, the shortest distance between the electrodes is 25 mm or less, and a neon-krypton mixed gas is sealed as a starting rare gas. It comprises an arc tube and a lighting tube or solid state lighting element for applying a starting power to the arc tube, and the pressure of the neon-krypton mixed gas is 30 Torr.
As mentioned above, the pressure is 26° Torr or less, and the partial pressure ratio of argon gas in the neon-argon mixed gas is in the range of 3 cm or more and 60 cm or less, and therefore, with a commercial power supply of 100 to 120 V, Needless to say, the lamp starts reliably, and since scattering of the electrode material at the time of lamp starting is greatly suppressed, excellent life characteristics can be obtained. Furthermore, when a neon-krypton mixed gas is used as the starting rare gas, heat conduction loss is reduced compared to when a neon-argon mixed gas is used, which is advantageous in terms of lamp efficiency.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an arc tube of a high-pressure sodium lamp device according to the present invention, and FIG. 2 is a lighting circuit diagram of a high-pressure sodium IJ lamp device 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...
...Thermal protection film, 21...Outer tube, 22...
...lighting tube, 25 ...power supply. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A high-pressure sodium lamp that is provided with electrodes at both ends, the shortest distance between the electrodes is 258 mm or less, and is equipped with an arc tube with an inner diameter of 7 mm or less and filled with a neon-krypton mixed gas as a starting rare gas. The sealed pressure of the neon-krypton mixed gas is 30 Torr or more, 250 Torr or more.
Torr or less, and the partial pressure ratio of krypton gas in the neon-krypton mixed gas is 3 or more,
High pressure (in the range of 50 inches or less) IJum lamp,
A high-pressure sodium lamp device characterized in that it is started by a lighting tube or solid-state lighting element.