JPS59112563A - High pressure metal discharge lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Description of Related Applications C.I. Mc Vey
U.S. Pat. It is.

BACKGROUND OF THE INVENTION The present invention relates to a high-pressure sodium lamp using an alumina ceramic inner tube, and more particularly, to a high pressure sodium lamp having an alumina ceramic inner arc tube that can operate under relatively high pressure and that has a long service life. The present invention relates to a high-pressure lithium/lium pair which determines the desired color rendering properties maintained throughout the process.

Over the past decade, high pressure sodium lamps have become widely used for commercial lighting applications, especially outdoor lighting applications. Such a high pressure sodium lamp is described in Schmidt US Pat. No. 3,248,590, entitled "High Pressure Sl Helium Lamp." In high-pressure sodium lamps, an elongated inner tube or arc tube made of a transparent, heat-resistant oxide material (preferably dense polycrystalline alumina or synthetic sapphire) that withstands helium at high temperatures is commonly used. Such an inner tube is typically filled with a gas atmosphere consisting of sodium helium, a noble gas for starting (e.g., xylenone), and mercury for efficiency. The ends of the inner tube are sealed by suitable closures H allowing connection to thermionic electrodes, which may also consist of refractory metal structures activated by electron-emissive substances. The above inner tube is generally
It is supported inside an outer glass tube with a conventional screw cap at one end. The electrodes of the inner tube are connected to the terminals or shell and eyelet of the base. The space between the inner and outer tubes is typically evacuated for heat conservation.

The color rendition of the 49 quasi-type high pressure sodium lamp can be improved by increasing the internal sodium partial pressure in the arc chamber of the inner tube made of polycrystalline alumina. By the way, in order to improve the color rendering properties of standard high-pressure sodium lamps, it is necessary to use a polycrystalline alumina arc tube with an internal sodium partial pressure that is 2 to 3 times higher than that of a standard high-pressure sodium lamp. There are three conditions that must be operated under. On top of that,
In order to compensate for the reduction in luminous efficiency normally associated with operation under such increased sodium partial pressure, the tube wall temperature at J3 between the electrode tips in the arc chamber was increased to a standard high pressure [~compared to a lithium lamp]. The increase in the internal sodium partial pressure and the rise in the tube wall temperature of the arc chamber will cause the life of a high-pressure sodium lamp with improved color rendering to change to normal color rendering. For example, according to the manufacturer, a high-pressure sodium lamp with normal color rendering has a lifespan of 20,000~
While products are classified as having a lifespan of 30,000 hours, high-pressure sodium lamps with improved coloring properties have a lifespan of 800 hours.
Products with a lamp life of 0 to 10,000 hours are usually classified as -C.

The shortened service life of high-pressure sodium lamps with reoriented color rendering is mainly due to the loss of sodium from the arc chamber due to reaction with the inner surface of the arc chamber and leakage through the tube wall of the arc chamber. This is usually caused by C. The result of sodium loss is an increase in the voltage of the high-pressure sodium moon, a decrease in correlated color temperature, a decrease in color rendering index, and a color shift from a desirable warm white to an undesirable pink. Additionally, sodium flowing through the tube walls of the arc chamber is deposited on the inner walls of the evacuated outer chamber, where it reacts with evaporation products from the glass and alumina arc tube, resulting in a brownish color of the outer chamber. It also reduces the light output of high-pressure sodium lamps.
Ru.

It is therefore an object of the present invention to provide means for reducing sodium losses in high pressure sodium lamps with improved color rendering, operating under relatively high pressures derived from sodium in the arc chamber, and also to reduce the loss of sodium during the lifetime. The object of the present invention is to provide a high-pressure sodium lamp as described above, which has a color rendering index of 1' that remains substantially constant throughout.

These are the objects of the present invention, which will become clearer upon consideration of the following description.

SUMMARY OF THE INVENTION The present invention provides a high-pressure system with improved color rendition due to increased sodium partial pressure, characterized in that it includes means for reducing sodium loss commonly caused by high-sodium pressure operation. This is an attempt to provide a 1~ lium lamp.

According to one embodiment of the present invention, the structure includes a structure in which an inner arc tube with thermoelectron electrodes enclosed at both ends is enclosed by an outer tube made of glass. Black-light capable metal filling d5 and 10-30 T with sodium partial pressure in the range of 300 Torr
A high pressure metal discharge system is disclosed containing xenon scum with a pressure in the range of orr. The inner arc tube in this case is made of optically translucent polycrystalline alumina made from an aluminum oxide composition containing 1Q and doped with additives selected from Zr02, HfO2 and mixtures thereof. It is characterized by being made of ceramic. The high pressure sodium lamp according to the invention has an overall color rendering index within the range of 50-85.

DETAILED DESCRIPTION Referring to FIG. 1, there is shown a high pressure lamp 1o constituting an embodiment of the present invention, which corresponds to a conventional 400 watt type. The high pressure lamp 1o includes a glass outer bulb 12, the end of which is shown at the top of FIG. 1, fitted with a standard large screw cap 13.

A pair of relatively thick lead-in wires 15 and 16 extend through the recessed knob stem 14 and are connected at their outer ends to the shell 17d3 and the eyelet 18 of the base.

The high pressure sodium lamp 1o also includes an inner tube or arc tube 19 located centrally inside the outer tube 12. The arc tube 19 is a length of light-transmissive tubing made of translucent polycrystalline alumina and ramic. The upper end of the arc tube 19 is closed by a plug 20 made of alumina ceramic, and a niobium lead-in wire 21 is provided to pass through the plug in an airtight manner to support an upper electrode (not shown) inside the arc tube 19. . The lower end of the arc tube 19 is also closed by a Hiramic plug 22, through which a thin-walled niobium tube 23 is provided.

Such niobium tube 23 serves as the lead-in to the arc tube 19 and also as a reservoir for excess alkali metal and monomercury within the arc tube 19. The shank of the lower electrode (not shown) of the arc tube 19 extends into the niobium tube 23 and is secured in position by pleating the portion 24 of the niobium tube 23 as shown in FIG. . The crimping creates a restrictive passageway that allows vaporized aluminum and mercury to pass through, but prevents the movement of liquid amalgam within the niobium tube 23.As a result, this high-pressure 1-Lium lamps do not only operate with the cap facing upward, as shown in Figure 1, but also operate with the cap facing down. A more detailed description of the ceramic sealing means can be found in Mc Vey, U.S. Pat. It will be done.

Most important to the invention is the arc tube 19. In Fig. 1, a part of the arc tube 19 is cut out to clearly show the arc chamber 40a3 and the tube wall 42. The arc tube 19 is made of magnesium oxide (
Zirconium oxide (Zr 02 ), hafnium oxide (+
-1f02> and mixtures thereof. More specifically, the arc tube 19 is manufactured from an alumina composition having 633 (B > ppm MgO) and additives selected from among zrO2, HfO2 and mixtures thereof in a proportion of 400 (FFI) ppm. In such an arc tube 1
The high-pressure sodium lamp 10 of FIG.
It has an overall color rendering index within the range of 5. In addition, the additive Zr
O? An arc tube made of an alumina composition containing MgO along with J3 and HfO2 is described in U.S. Pat. No. 4,285,732, assigned to the same assignee as the present invention and entitled "Aluminum Ceramic."

U.S. Pat. No. 4,285,732 describes a method for manufacturing an optically translucent polycrystalline sintered body. It is useful for optical applications such as enclosures for tubes. By the way, according to the present invention, US Pat. No. 4,285,732
An arc tube (I) having a composition as described in the specification of
It has been surprisingly found that the arc tube 19) does not exhibit the superior properties of reducing sodium losses from the arc tube 19 described in the Background of the Invention section. As a result, it is possible to operate under high sodium partial pressure to improve color rendition. δ, and its color rendering properties will be maintained over a better lifetime.

Next, typical parameters regarding the standard high-pressure sodium lamp and the high-pressure sodium lamp 10 with improved color rendering according to the present invention are shown in Table 1 below.

First surface pipe wall load 18.0W/cyn222.
Ow/c+n2 amalgam 25%Na
25% separation xylenone filling pressure 17To
rr 17Torr chromaticity coordinates X, Y
O,512,0,505° The standard high-pressure sodium lamps in Table 1 are manufactured by General Electric 1-Link Company.
The high pressure sodium lamp 10 with improved color rendering properties shown in Table 1 is of the 25 OW type, whereas the commercially available Lu2O3 lamp is of the 400 W type and can be obtained from the lighting business division of New York City. As can be seen by comparing the standard high-pressure sodium pair and the improved color rendering high-pressure sodium pair 10 in Table 1, (
1) While the standard high-pressure sodium lamp has a low color index of 20, the improved color rendering index of the present invention has a low color index of 1 to 1 K.
J' 10 has a color rendering index of 65. Also, <2
) Standard high-pressure lamps have a correlated color temperature of 2-100', while the color rendering improved high-pressure sodium lamp 1 of the present invention has a correlated color temperature of 2250'. ing. Furthermore, (3) the color rendering improved high pressure sodium 1-lium lamp 1o of the present invention is 60 tons in a standard high pressure sodium lamp.
120To, which corresponds to twice the normal sodium partial pressure of rr.
It has a thulium pressure of rr.

In order that the invention may be more clearly understood, Mp,
Comparative test data obtained regarding the quasi-type high-pressure sodium lamp and the high-pressure monolithium lamp with improved color rendering properties of the present invention are summarized below.

The standard high pressure tzitorium lamp used for the comparative test data was rated at 400 W with an overall color rendering index of 60 Torr and a partial pressure of 60 Torr. Comparative tests were conducted on a total of 10 standard high-pressure systems. Improved color rendering high pressure bath 1
- The lithium lamp 10 is equivalent to the standard high-pressure sodium lamp with a 4° OW rating as described above, and contains the additive Zr 02 as described above and has a 120-160 orr.
The only difference was that it included an arc tube 19 operating under pressures in the range of . Comparative tests were conducted on a total of 10 high-pressure sodium lamps with improved color rendering.

Both groups of standard high-pressure sodium lamps and improved color rendering high-pressure L-SUM lamps were operated at 800 W for 100 hours. During the test at 800W, both groups
It was observed that all the samples had an increased overall color rendering index of about 65 during 0W operation, and both groups had a maximum tube wall temperature of about 1350° C. approximately halfway between the opposing electrode tips.

After approximately 100 hours of lighting, the high-pressure sodium lamp was inspected. Tests revealed that when a standard high-pressure sodium lamp was operated at 800W, the outer bulb was colored dark brown. However, the outer bulb of the high-pressure sodium lamp 10 with improved color rendering properties of the present invention showed only slight coloring. Furthermore, the arc tubes of standard high pressure sodium lamps exhibited "why I-spots" due to the presence of sodium beta-alumina, which penetrated into the arc tube wall.

Such sodium β-alumina is harmful to the operation of the arc tube2 because it makes it impossible for the chemically bound sodium to participate in the discharge operation of the arc tube, and the sodium β-alumina This is because the loss of sodium is further increased because it acts as a passageway for sulfur to thulium to move through the arc tube wall, and the coloring of the outer tube due to its deposition is further promoted. The high-pressure sodium phantom arc tube 19 with improved color rendering properties of the present invention did not exhibit [white spora 1~]. arc tube 19
Scanning electron microscopy analysis of the inner surface of the tube revealed that some whisker-like crystals of sodium β-alumina were scattered, but there was a high concentration of β-alumina 1 to lithium YAARC tube 1.
No sodium intrusion into the tube wall of No. 9 was observed.

Thus, according to the practice of the present invention, 100 to 3QQl-
It should be appreciated that a high pressure sodium phantom with improved color rendering properties is available which operates under pressures within the range of 0.25 to 1.35 mm and exhibits an overall color rendering index of 65. In the above-mentioned comparative test regarding the J5, color rendering improved high-pressure lithium lamp, an overall color rendering index of 65 was measured; It should be noted that thorium phantoms which exhibit no overall color rendering index and which are at high pressures are also included within the scope of the present invention. Furthermore, the results of the above comparative test are 4
The parameters related to the 00W type high-pressure Bukawa Lium lamp and in Table 1 are related to the 250W type high-pressure sodium lamp, but with a lower rating (e.g. 3).
5W type) to a higher rated wattage (e.g. 1
It goes without saying that the present invention applies to various high-pressure sodium lamps up to 000W type).

[Brief explanation of the drawing]

FIG. 1 is a front view of a high pressure sodium lamp according to the present invention. In the figure, 10 is a high-pressure sodium lamp, 12 is an outer tube, 13 is a cap, 14 is a stim, 15 and 16 are lead-in wires, 19 is an arc tube, 21 is a 2A7 lead-in wire, 23 is a niobium tube, and 40 is an arc lead-in wire. , and 42 represents the 9-yu wall. patent applicant

Claims (1)

[Claims] 1. The inner arc tube includes a structure in which an inner arc tube with thermionic electrodes sealed at both ends is surrounded by an outer glass tube, and the inner arc tube has a sodium partial pressure in the range of 100 to 300 Torr. vaporizable metal filling with and 10-3
In high-pressure metal discharge lamps, such as those containing xenon gas with a pressure in the range of 0 T orr, which are manufactured from alumina compositions containing MQO and containing Zr 02, Hf
A high-pressure metal discharge couple, characterized in that the inner arc tube consists of an optically translucent polycrystalline alumina ceramic doped with additives selected from O2 and mixtures thereof. The high-pressure metal discharge lamp according to claim 1, having an overall color rendering index within the range of 2.50 to 85. 3. The internal arc tube is 633 (weight) 10 ppm
Zr 02
, Hf 02 a3 and mixtures thereof in a proportion of 400 ppm (by weight). 4. The high-pressure metal discharge pair according to claim 1, wherein the internal arc tube has a wall thickness of 0.5 to 1.5 mm.