JPH03112048A - High-pressure sodium lamp - Google Patents

Abstract

PURPOSE:To suppress the change of the lamp voltage by electrically connecting a light emitting tube in which all the sealed metal is evaporated and gasified and a light emitting tube in which part of the sealed metal is evaporated and gasified in series in the stably lighted state of a lamp. CONSTITUTION:Light emitting tubes 7 and 8 are connected in series in an outer bulb 1 sealed with a base 2 at one end and kept at high vacuum inside and integrally supported via mounts. A saturation type lamp is used for the light emitting tube 7, and xenon gas is sealed together with excess sodium and mercury inside. A nonsaturation type lamp is used for the light emitting tube 8, and a quantity of sodium, mercury and xenon gas that is completely evaporated and gasified during lighting is sealed inside. The change of the lamp voltage after the preset time elapses can be suppressed. The light output can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in high pressure sodium lamps, and more particularly to improvements in lamp working characteristics.

[Prior art] A saturated vapor pressure type lamp, which is conventionally used as a high-pressure sodium lamp, is filled with sodium and mercury in an amount greater than that which evaporates during lighting, and excess amalgam condenses in the coldest part of the arc tube during lighting. There is.

By the way, in this type of lamp, after the lighting time elapses, (1) the sodium in the arc tube disappears and the sodium ratio in the amalgam decreases.

■The electrode material sputters onto the wall of the arc tube and turns black, keeping the electrode warm and increasing the temperature of the coldest part.

■The electron emitting material coated on the electrode is depleted, the electrode operating temperature rises, and the temperature of the coldest part rises accordingly, causing the lamp voltage to rise during the working cycle and eventually the lamp to turn off. This phenomenon occurs.

Also, unlike the saturated type lamps, in unsaturated vapor pressure type high-pressure sodium lamps, all of the sodium and mercury sealed in the arc tube evaporate during lighting. Because it reacts with the material and disappears, a phenomenon occurs in which the lamp voltage decreases as the lighting time elapses.

For this reason, lamp design must be carried out strictly.
When lighting a lamp using a choke-type ballast, the lamp current increases as the lamp voltage decreases, causing the ballast winding temperature to rise and damaging the ballast.

[Problems to be Solved by the Invention] As described above, since the lamp voltage changes during lighting for both the saturated vapor pressure type lamp and the unsaturated vapor pressure type lamp inside the shell, due to the input characteristics of the ballast, the lamp voltage changes as the lighting continues. There is a problem in that the light output changes greatly as the lamp input changes.

[Means for Solving the Problems] The present invention has been made in view of the above, and it is an object of the present invention to connect an arc tube for a saturated lamp and an arc tube for an unsaturated lamp electrically in series, and to integrate an outer bulb into one body. An object of the present invention is to provide a high-pressure sodium lamp which is made up of a high-pressure sodium lamp supported within the lamp and whose lamp light output changes little during operation by reducing changes in lamp voltage during lighting.

[Example] Hereinafter, an example according to the present invention will be described based on FIG. 1.

The outer bulb 1 has a cap 2 sealed at one end, and the inside of the outer bulb is maintained at a high vacuum by a getter.

A support 4 is installed on the stem 3 inside the outer sphere, and arc tubes 7 and 8 are electrically connected in series inside the outer sphere through a mount constituted by auxiliary supports 5 and 5' and a spring 6, and are integrated. is widely supported.

Here, 7 is an arc tube used in a general saturation type lamp, and a niobium tube with electrodes connected inside the tube is sealed at both ends of the translucent alumina tube. In addition to mercury as a metal for tlt'fTf, xenon gas as a rare gas for starting aid is sealed.

Further, the arc tube 8 is an arc tube used in an unsaturated lamp, and has the same structure as above, and is filled with sodium and mercury in an amount that completely evaporates during lighting, as well as xenon gas. There is.

Next, explanation will be given based on experimental results.

The lamp used in the experiment had an inner diameter of 6.6 m as an arc tube dimension.
A high-pressure sodium lamp is constructed by using two arc tubes with mφ and an interelectrode distance of 67 nwn, one being a saturated type and the other being an unsaturated type, and mounted electrically in series inside the outer bulb. I experimented by lighting it with an input of 360W.

In addition, in order to compare the lamp according to the present invention with a conventional lamp, the inner diameter of one arc tube is 8. Omφ, distance between electrodes 82o
Saturated high-pressure sodium lamps using n arc tubes (Table 1, Nα6-8), and unsaturated high-pressure sodium lamps with arc tube dimensions similar to the conventional ones (Table 1, Nα9-8).
11) were each turned on with a tube input of 360 W, and changes in lamp voltage were measured.

The experimental results are shown in Table 1. Here, the lamp voltage for each lamp indicates a lamp voltage measurement value after a predetermined period of time has elapsed. Note that the power supply voltage is constant.

(Leaving space below) Table 1 As is clear from Table 1, the lamp according to the present invention shows almost no change in lamp voltage after a predetermined period of time has elapsed, especially after 10,000 hours, and therefore the lamp has a constant lamp input. Obtainable. Furthermore, by housing two arc tubes within the outer bulb, lamp characteristics such as increased light output can be improved.

[Effects of the Invention] As explained above, the high-pressure sodium lamp according to the present invention has a relatively simple configuration, and can suppress changes in lamp voltage after a predetermined period of time has elapsed, and can also suppress changes in the lamp voltage after a predetermined period of time has elapsed. Not only is it effective, but its economic impact is also great.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of a high-pressure sodium lamp according to the present invention.

Claims (1)

[Claims] (1) An arc tube in which a rare gas for starting aid is sealed together with sodium and a metal for buffer gas inside, and all of the sealed metal evaporates and vaporizes when the lamp is in a stable lighting state; A high-pressure sodium lamp consisting of an arc tube whose part evaporates and which is electrically connected in series and supported integrally within an outer bulb.