JPS61190847A - metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To prevent a heat retension film from coming off, by providing a plurality of piled heat retention films on at least one end of the luminous tube of a metal vapor discharge lamp in such a manner that the end of at least one of the films is not coincident with those of the others nearer the central portion of the tube. CONSTITUTION:A luminous tube 1, which has electrodes 2a, 2b and in which rare gas, mercury and a metal halide are sealed, is housed in an outer tube 3 so that a metal vapor discharge lamp is constructed. A plurality of piled heat retension films 5a-5c are provided on the peripheral surface of the lowermost portion of the luminous tube 1 by coating the surface with zirconia or the like, in such a manner that the distance A between the ends of the first and the second films 5a, 5b nearer the central portion of the tube 1 and that B between the ends of the second and the third films 5b, 5c nearer the central portion of the tube 1 are set at about 1mm. The total thickness of the films 5a-5c at their above-mentioned ends is thus reduced to prevent the films from coming off at the ends which would conventionally be likely to come off. This results in keeping the performance of the lamp stable.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to metal vapor discharge lamps such as metal halide lamps and high-pressure sodium lamps, and particularly relates to improving efficiency by controlling the temperature of their arc tubes. be.

[Conventional technology]

Figure 14 shows the structure of a conventional metal halide lamp.
A light emitting tube 1 made of quartz glass has a pair of electrodes 2 at both ends thereof.
a and 2b facing each other, and a rare gas, mercury, and metal halide are sealed inside. The outer tube 3 covers the arc tube 1, and the inside thereof is filled with, for example, nitrogen gas. The cap 4 is attached to the upper end of the outer tube 3 and is electrically connected to the electrodes 2a and 2b. A heat insulating film 5 is provided at the lower end of the arc tube 1 and is formed of, for example, a zirconia coating. Regarding this coating,
It is disclosed in Japanese Patent Application Laid-Open No. 55-166858.

A device with such a structure is lit with the cap 4 facing upward, but in this lighting state, the lower end of the arc tube 1 is cooled by gas convection within the arc tube 1 and nitrogen convection within the outer bulb 3. It becomes the coldest part.

Since the vapor pressure of the metal halide changes depending on the temperature of the coldest part, the lamp efficiency also depends on the temperature of the coldest part. Therefore, conventionally, as shown in FIG. 15, a plurality of heat insulation films 5a, 5b, and 5c have been applied to increase the thickness of the heat insulation film to increase the temperature of the coldest part. Further, the ends of the heat insulating films 5a to 5c on the side of the center of the arc tube 1 were aligned on the same line.

[Problem that the invention seeks to solve]

However, in the conventional products described above, the adhesion of the zirconia coating film is not very strong, and as the film thickness increases, it is difficult to maintain stable characteristics. There were problems such as the paint film peeling off from the edges of the central part.

The present invention has been made to solve the above-mentioned conventional problems, and provides a metal vapor discharge lamp that prevents the peeling of the multiple layers of heat insulating film provided at one end of the arc tube and provides stable characteristics. The purpose is to provide.

[Means for solving problems]

In the metal vapor discharge lamp according to the present invention, at least one layer of the plurality of layers of heat insulating films provided at at least one end of the arc tube at the end on the central part of the arc tube is not aligned with the other layers. be.

[For production]

When looking at the temperature film as a whole, the wall thickness at the end on the center side of the arc tube becomes thinner, so that peeling of the heat insulating film at this end becomes less likely to occur.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a 400W metal pallite lamp according to this embodiment, in which the inner diameter of the arc tube 1 is 2 am and the electrode 2a.

The distance between 2b is 4.5cm, and 9.5mg is contained in arc tube 1.
of sodium iodide, 10.6 mg of scandium iodide, an appropriate amount of mercury, and 20 Torr of argon gas were sealed.

Further, nitrogen gas of 560 Torr was filled in the outer tube 3. Furthermore, as shown in FIG. 2, light emission Iti! A plurality of protective films 5a to 5c made of a metal oxide, such as a zirconia coating, were sequentially applied to the outer periphery of the lower end of 1. Also, the 1st layer and 2nd layer
The distance between the ends of the heat insulating films 5a and 5b of the second layer on the center side of the arc tube 1 is A1, and the distance between the ends of the second and third heat insulating films 5b and 5c is B, and A and B are both was also set as IMIm. Therefore, the only difference from the conventional method is that the end portions of the heat insulating films 5a to 5c on the central side of the arc tube 1 are made different by one point each.

Next, one metal paralite lamp of this embodiment having the above configuration was used.
0 lamps (Bl~B10) and 10 conventional halide lamps (
A lifespan test was conducted on AI-AIO) and it lit up 3000 times.
After hours, the luminous flux maintenance rate and the state of peeling of the zirconia heat insulating films 5a to 5c were examined based on the value at 100 hours. The results are shown in the table below. Note that the O mark indicates no peeling, the Δ mark indicates slight peeling, and the X mark indicates peeling.

As is clear from the above table, the peeling state of the example is better than that of the conventional example, and the luminous flux maintenance rate is about 8.6% higher on average. Therefore, the metal halide lamp of this embodiment can obtain stable characteristics throughout its life.

In addition, in the above embodiment, A=B=1 mm, but A, B
It is effective if both are 0.5++na or more and 511III+ or less. Of course, A and B may be different.

Also, if either A or B is 0, the other is 0.
It is sufficient if it is 5 mm or more and 5 mm or less. In addition, heat retention 5
Although 8 to 5C have three layers, the same effect as in the above example can be obtained if there are two or more layers.

3 to 13 show respective embodiments of the present invention, and in each case, at least one of the three layers of heat-retaining films 5a to 5c has an end on the center side of the arc tube in line with the other layers. They are arranged so that they are not lined up, thereby reducing the thickness of the entire heat-retaining film at the end portions and making it difficult for peeling to occur.

〔Effect of the invention〕

As described above, in the present invention, a plurality of layers of heat insulating films are provided on at least one end of the arc tube, and the end of one of the layers at the center of the arc tube does not coincide with the other end. This makes it possible to reduce the thickness of the entire heat insulating film at the end portions, and prevent peeling at the end portions where peeling is likely to occur. Moreover, this makes it possible to obtain stable characteristics such as luminous flux maintenance factor.

[Brief explanation of drawings]

FIGS. 1 and 2 are a front view and an enlarged sectional view of a main part of a metal vapor discharge lamp according to a first embodiment of the present invention, and FIGS. 3 to 13 are respectively according to each embodiment of the present invention. 14 and 15 are a front view and an enlarged sectional view of the main part of a conventional metal vapor discharge lamp, respectively. DESCRIPTION OF SYMBOLS 1... Arc tube, 2a, 2b... Electrode, 3... Outer tube, 5a-5c... Heat insulation membrane. Note that the same reference numerals in the figures indicate the same or corresponding parts. ]) 5. 'V - Agent Masuo Oiwa Figure 2 Figure 3 Figure 11 Figure 13 Figure 15

Claims (1)

[Claims] (1) An outer tube with a predetermined gas sealed inside, and an arc tube mounted inside the outer tube, with a pair of electrodes facing each other at both ends, and filled with at least a rare gas and mercury. In a metal vapor discharge lamp, a plurality of layers of heat insulating films are provided around the outer periphery of at least one end of the arc tube, and at least one layer of each layer of heat insulating film at the end of the center part of the arc tube is not lined up with the other layers. A metal vapor discharge lamp characterized by: