JPH034441A - High-pressure sodium lamp - Google Patents

Abstract

PURPOSE:To light the subject lamp by using a constant-energy type stabilizer for a mercury lamp by adopting an electrode construction wherein an external coil is in a signal coil shape, while an internal coil is in a double coil shape. CONSTITUTION:An adhesion type electrode coil is composed of an internal coil consisting of a double coil of a tungsten line wound about a tip part of an electrode axis and an external coil consisting of a single coil of a tungsten line. In this case, when dielectric breakdown of a luminous tube is generated, heat energy of the heated external coil becomes hard to escape to the axis due to the internal coil consisting of a double construction excellent in heat insulation while getting easy and active in thermion emission and being able to smoothly transfer to an arc. Thereby, lighting can be easily performed even by using a constant-energy tube stabilizer.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to the improvement of high-pressure sodium lamps, and in particular to the improvement of arc tube electrodes of high-pressure sodium lamps operated using constant-power mercury lamp ballasts as ballasts. Regarding improvements.

[Prior Art] High-pressure sodium lamps configured to be lit using mercury lamp ballasts are becoming popular, but these ballasts are generally limited to choke-type ballasts, and constant-power ballasts are is considered inappropriate.

The reason for this is that high-pressure sodium lamps are generally saturated lamps and contain more sodium and mercury than can be evaporated during one lighting operation, so that (1) sodium disappears and its proportion in the sodium amalgam decreases; (2)
The electrode material sputters, the inner wall of the arc tube becomes black, and the electrode part is kept warm, causing the temperature of the coldest part to rise. ■The electron emitting material coated on the electrode is depleted, and the electrode operating temperature rises, resulting in a rise in the temperature of the coldest part. As the cold part temperature rises, the lamp voltage increases during lamp operation, so in constant power type ballasts, which have constant current characteristics, the lamp input increases, and in extreme cases, the lamp may be damaged. It is.

Furthermore, when vibrations or shocks are applied to the lamp, there is a risk similar to that described above in that excess amalgam will bump and the lamp voltage will rise rapidly.

Therefore, if you use an unsaturated lamp, such as a mercury lamp, in which all the amalgam sealed in the lamp evaporates, the danger caused by the rise in lamp voltage will be eliminated, and in fact, unsaturated high-pressure sodium lamps were developed as lamps. ing.

[Problems to be Solved by the Invention] However, there are reasons why even the unsaturated lamp described above is difficult to light with a constant power ballast.

That is, at the moment when the arc tube undergoes dielectric breakdown when starting the lamp, the lamp current waveform exhibits a shape close to the secondary side short-circuit current waveform of the ballast shown in FIG.

Now, if the light is lit with a choke type ballast.

Since energy close to a sine wave heats the electrode, thermionic emission occurs easily and a smooth transition to stable discharge occurs.

However, when lit with a 2 constant power type ballast.

As shown in Figure 2(b), due to the long current stop period,
There was a problem that the transition to stable discharge did not occur due to insufficient energy to heat the electrodes.6 [Means for Solving the Problems] The present invention was made in view of the above problems, and the present invention has been made in view of the above. The object of the present invention is to provide a high-pressure sodium lamp that can be operated with a constant power ballast for a mercury lamp by improving the structure of the sealed electrode, particularly the electrode coil portion.

[Embodiments and Effects] Hereinafter, embodiments according to the present invention will be described based on FIG. 1 while comparing them with conventional examples.

In the high-pressure sodium lamp according to the present invention, electrode support tubes are sealed at both ends of a translucent alumina tube, a tungsten electrode core frame is fixed to the inner end of the support tube, and a tungsten wire is coiled at the tip of the support tube. An electrode coil portion formed in a shape is provided.

The arc tube constructed in this way, in which mercury and sodium are sealed together with a rare gas inside the tube, is sealed and supported in an outer bulb with a cap at one end, together with an inner support and a starter. The conventional electrode coil structure is shown in Figure 3 (not shown). Fig. 3(a) shows a close-contact type electrode coil portion consisting of a single coil of tungsten wire in which both the outer and inner coils are wound around the tip of the electrode core frame, and Fig. 3(b) shows a similarly skipped type electrode coil portion. This is the electrode coil section.

Here, when dielectric breakdown occurs in the arc tube when starting the lamp,
The arc is not generated from the tip of the electrode core rod, but from the tip or end of the outer coil. And, as mentioned above, the inner coil is a single wire with the same diameter as the outer coil,
In addition, if the outer coil and electrode core frame are in strong contact, the thermal energy of the heated outer coil escapes from the core frame through conduction through the inner coil, resulting in a lack of energy as in a constant power ballast. It is thought that the waveform does not heat the electrode to the extent that thermionic emission becomes active.

Therefore, FIG. 18 shows the structure of the electrode coil portion according to the present invention. Figure 1(a) shows an inner fill made of a double coil of tungsten wire wound around the tip of the electrode core rod and an outer coil made of an exposed coil of tungsten wire, forming a close-contact electrode fill part. are doing. In addition, Fig. 1(b) shows the electrode coil part of the same spiral-wound shape.If the electrode structure is like this, when dielectric breakdown occurs in the 5 arc tube, the thermal energy of the heated outer coil will be absorbed by the thermal insulation. The inner coil, which has an excellent double structure, makes it easy to emit thermionic electrons and smoothly transition to an active arc, making it easy to use a high-pressure sodium lamp even when using a constant power ballast. Can be lit.

[Effects of the Invention] As is clear from the above description, the starting characteristics of the high-pressure sodium lamp according to the present invention can be improved by relatively easily improving the structure of the arc tube electrode section.
- Since it can be lit using a constant power ballast for mercury lamps, which is widely used in the market, its industrial utility value is great.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of an electrode coil section according to the present invention, FIG. 2 is a diagram showing a short-circuit current waveform on the secondary side of a ballast, and FIG. 3 is a side view showing a conventional electrode coil section.

Claims (1)

[Claims] 1 Electrodes are sealed at both ends of the arc tube, and the electrode structure is such that the outer coil is a single coil and the inner coil is a double coil, and sodium, buffer gas metal, and starting rare gas are sealed inside. , a lamp having an arc tube in which all of the enclosed metal evaporates when the lamp is stably lit, and the arc tube is sealed and supported in an outer bulb together with a starter, is lit with a constant power type ballast for a mercury lamp. A high-pressure sodium lamp characterized by: