JPH04129161A - High voltage sodium lamp of both-ended base type - Google Patents

Abstract

PURPOSE:To make an instantaneous re-start possible with simple constitution by using an insulator for a support of a luminous tube in a sodium lamp comprising a luminous tube supported and secured with a luminous tube support body at both sides within a rare gas-sealed outer tube having a base at both ends. CONSTITUTION:700Torr of argon gas is sealed in a quartz outer tube 2 having an RX7s type base 3 secured at both ends. A conductive tube 5 comprising niobium is sealed at both ends of a luminous tube 1 made of polycrystal alumina, and 4mg of sodium, 16mg of mercury and 20Torr of xenon are sealed in the tube 1. A luminous tube support body 4 is made of an insulation body such as alumina sintered body. A hole 6 is formed at the center of the body 4, and both conductive tubes 5 are inserted through the hole 6 for supporting and securing the tube 1 within the outer tube 2. According to the aforesaid construction, the occurrence of electrical discharge between the support bodies 4 within the outer tube 2 can be prevented, even when high pulse voltage of 14kV is applied for an instantaneous start in re-starting a lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a double-capped high-pressure sodium lamp.Prior art A high-pressure pulse voltage of 20 kV or more is required to restart a high-pressure sodium lamp immediately after extinguishing it. Although this is already known, it is difficult to restart the high-pressure sodium lamps that are currently in widespread use and have a cap at one end.
~ In order to solve these problems, a double-cap type high-pressure sodium lamp with caps at both ends has been put into practical use, but this arc tube incorporates a polycrystalline alumina arc tube with sodium etc. sealed inside the outer bulb. Even though both sides of the arc tube are supported and fixed by metal arc tube support plates, a rare gas is filled in the outer bulb to lower the surface temperature of the arc tube and suppress the reaction between polycrystalline alumina and sodium. However, in this lamp, a high-voltage pulse voltage of 14 kV applied when restarting causes a discharge within the outer bulb.This outer bulb discharge occurs between the metal arc tube support plates that are the shortest distance apart. The amount of high-voltage pulse voltage that can be applied without causing discharge inside the outer tube is at most 1.
0 kV, and in this case, the time required to restart is 5 seconds or more, and it cannot be said to be an instantaneous restart.The present invention was made in consideration of this problem.
The object of the present invention is to provide a double-cap type high-pressure sodium lamp that can perform instantaneous restart without reducing the magnitude of the high-voltage pulse voltage applied at the time of restart. A double-cap type high-pressure sodium lamp is a double-cap type high-pressure sodium lamp in which an arc tube is supported and fixed by arc tube supports on both sides of the arc tube in an outer bulb having caps at both ends and a rare gas sealed inside. According to the present invention, since an insulator is used for the arc tube support, even if a high pulse voltage of, for example, 14 kV is applied at the time of restart, the arc tube inside the outer bulb remains intact. As shown in FIG. 1, the double-ended high-pressure sodium lamp of the embodiment of the present invention is made of quartz and has an outer tube 1 with an inner diameter of 19 mm and an outer diameter of 22 mm. , made of polycrystalline alumina incorporated inside, inner diameter 6.75mm, total length 92m.
m arc tube 2, an arc tube support 3 supporting and fixing the arc tube inside the outer tube 1 as described later, and RX7s type metal alloys 4 fixed to both ends of the outer tube 1. The outer tube 1 is filled with argon gas at 700 Torr, and the arc tube 2 has electrodes (not shown) at both ends with a diameter of 3 mm. A conductive tube 6 made of Omm niobium is sealed, and 4 mg of sodium, 16 mg of mercury, and 20 Torr of xenon are sealed inside.The arc tube support 3 has a diameter of 18.5 mm and a thickness as shown in FIG. 1.
It is made of an insulator such as a 5 mm alumina sintered body, and a hole 5 with a diameter of 3°2 mm is formed in the center.a Both conductive tubes 6
The holes 5 of the arc tube support 3 are inserted into the outer tube 1, and the arc tube 2 is supported and fixed inside the outer tube 1 along its central axis.a The shortest distance of the planar arc tube support 3 is 88 mm. The pulse generator is connected to a single coil ballast for a power supply voltage of 200V so that the lamp input is 250W while the lamp is lit.The pulse generator operates only when the lamp is started or restarted, and the pulse voltage is changed every half cycle. The peak voltage is 14 kV, the half width is 5 μsec, and the generation phase angle is 75” (1 lamp).At night when the lamp has been on for more than 30 minutes, turn off the power, immediately apply power to the lamp, and turn off the lamp to 2. The probability of starting within seconds was investigated. The results were as follows: In 20 starting tests, the lamp of the above example started within 2 seconds and no external discharge occurred at all.゜We conducted a lighting experiment with a 5-hour off cycle (＼ Rated 12,000
When we conducted an instantaneous restart experiment with timed lighting, we found that
As in the initial case, all of the 20 starting experiments restarted within 2 seconds, and no external discharge occurred.As for the luminescent support 3, the power of alumina shown in the above example ＼ stone moxibustion Porcelain made of silica, forsterite, mullite, etc. can also be used, and results similar to those in the above example can be obtained. In the example where there are 4 tubes and 3 tubes, respectively, the power of the argon gas shown in the above example is the same as the rare gas sealed in the outer tube. Moyoshi ~ Detailed explanation of the invention: The present invention is a double cap in which an arc tube is supported and fixed on both sides of the arc tube by arc tube supports in an outer bulb having caps at both ends and filled with a rare gas. By using an insulator for the arc tube support, it is possible to provide a double-cap type high-pressure sodium lamp that can be restarted instantly with a simple structure.

[Brief explanation of drawings]

FIG. 1 is an enlarged front view of a double-ended high-pressure sodium lamp according to an embodiment of the present invention. FIG. 2 is an enlarged front view showing an example of an arc tube support. FIG. 3 is an enlarged view of another example of an arc tube support. Figure 4 is an enlarged front view showing another example of the arc tube support.

Claims (1)

[Claims] In a double-cap type high-pressure sodium lamp in which an arc tube is supported and fixed by arc tube supports on both sides of the arc tube in an outer bulb having caps at both ends and a rare gas sealed inside, the arc tube support is made from an insulator. A double-capped high-pressure sodium lamp characterized by: