JPH04359859A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To preclude the risk of breakage of an outer tube even when a light emission tube goes into explosion. CONSTITUTION:A metal halide lamp concerned is equipped with a light emission tube 110 in its outer tube 112, and therein a buffer member 134 is furnished between the tube 110 and the approximate center 130 of a transparent part 112b at the facade of the outer tube 112.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to metal halide lamps,
In particular, it concerns improvements in explosion protection.

0002

2. Description of the Related Art Metal halide lamps have a spectrum covering the entire visible region, and have excellent color rendering properties and good luminous efficiency, so they are widely used in the field of lighting for sports, commercial facilities, and the like.

In general, metal halide lamps are classified into two types: one uses the arc tube 10 itself as shown in FIG. 7, and the other uses an outer bulb 12 covering the outside of the arc tube 10 as shown in FIG.

By the way, many mercury lamps and the like are used which have a reflection type outer bulb 12 made of blown glass as shown in FIG. However, in the case of metal halide lamps, those having such a reflective outer tube 12 are not commercially available.

[0005] This is mainly due to the following reasons. ■Since the reflective outer bulb 12 described above has a vapor-deposited aluminum film on its reflective part 12a, the vapor-deposited film and the metal sealed in the arc tube 10 cause electrostatic action, and sodium etc. It is discharged into the outer bulb 12 through the quartz tube, and the discharge may become abnormal within several hundred hours after the lamp starts lighting, resulting in a short lifespan. - If the arc tube 10 ruptures for some reason, the outer tube 12 will also be damaged because it is made of blown glass and is thin. ■The outer tube is large and the lamp fitting that houses the lamp is also large.

Therefore, a metal halide lamp as shown in FIG. 10 has been explored. In this lamp, as shown in the exploded view of FIG. 11, the outer tube 12 is separated into a reflective section 12a and a front transparent section 12b, and the arc tube 10 is placed inside the reflective section 12a horizontally (perpendicular to the central axis of the reflective section). direction).

A reflective film 14 is provided on the inner surface of the reflective portion 12a, and a cap 16 is attached to the back surface of the reflective portion 12a. After installing the arc tube 10 at the center inside the reflecting section 12a, the flat hemispherical transparent section 12b is attached.

The outer tube 12 shown in FIGS. 8 and 9 is manufactured from blown glass, whereas the outer tube 12 shown in FIG. 10 has a reflective portion 12a and a transparent portion 12b formed by glass molding. be able to. Then, a reflective multilayer film 14 may be applied to the inner surface of the reflective portion 12a.

In the case of a metal halide lamp as shown in FIG. 10, since it is molded into a molded glass, the wall thickness can be increased, and the outer bulb can be made smaller. With blown glass molding, when the wall thickness is increased, the thickness tends to be uneven, and furthermore, molding for attaching a base is difficult, but molded glass molding does not cause such problems. Further, the reflective film can be made of a multilayer film of oxides such as titanium, silicon, tantalum, etc. instead of aluminum. Therefore, problems due to electrostatic effects do not occur.

0010

However, even in the metal halide lamp shown in FIG. 10, problems still remain in terms of explosion protection. That is, since metal halide lamps operate at fairly high temperatures, the encapsulated metal tends to react with the quartz glass. For this reason, there was a possibility that the arc tube would explode explosively at the end of the lamp's life.

In the method shown in FIG. 8, the metal halide lamp is generally used covered with a lighting fixture, so there is little problem even if the lamp explodes, but in the case of the method shown in FIGS. 9 and 10, In the case of reflective metal halide lamps, they are simple lighting devices that are meant to be used naked, so commercialization was delayed due to the fear of glass shattering and falling due to explosions, even though they are easy to use.

The present invention has been made in view of the problems of the prior art described above, and its object is to provide a metal halide lamp with excellent explosion-proof properties.

[0013]

[Means for Solving the Problems] In order to achieve the above object, a metal halide lamp according to the present invention includes an arc tube,
It is characterized in that a buffer is provided between the outer tube and the substantially center of the front transparent portion.

[0014]

[Function] The present inventors investigated the explosion-proof properties of reflective metal halide lamps and found that when an arc tube explodes, most of the damage to the outer bulb occurs at the center of the transparent front surface of the outer bulb. It became clear.

In the metal halide lamp according to the present invention, when the arc tube explodes and fragments fly to the center of the front transparent part of the outer bulb, the destructive force of the fragments is reduced by the buffer, and the outer bulb is damaged. It doesn't need to be damaged.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Note that parts corresponding to the prior art described above are indicated by the reference numeral 100, and their explanation will be omitted.

[0017] First, the inventors of the present invention proceeded to study the mode of failure of metal halide lamps. That is, as shown in FIG.
Light up a reflective metal halide lamp as shown in 0,
After it is sufficiently stabilized, an overcurrent is applied to cause the arc tube inside the outer bulb to explode. We then examined the damage to the outer tube.

As a result, out of the 32 lamps to be tested, there were a total of 4 lamps whose outer tubes were damaged, and in FIG.
In one book, the center portion 132 of the book and reflective portion 112a was damaged.

The reason why the damaged parts of the outer tube 112 are unevenly distributed in this way is considered to be due to the following reasons. That is, when the arc tube 110 explodes and its fragments head towards the outer tube as shown in FIG. 2, when the fragments hit the center portion 130 of the front transparent portion 112b, the impact directly becomes a destructive force on the outer tube 112. However, if it deviates from the center 130, the destructive force is dispersed in the wall thickness direction (direction of arrow I in the figure) and tangential direction (direction of arrow II in the figure) of the outer tube 112, and especially in the wall thickness direction, which is a problem. Since the destructive force of the center part 130 is reduced,
Damage to the outer tube is unlikely to occur in other ways.

Based on this knowledge, the inventors of the present invention have decided to use a buffer to reduce the destructive force caused by fragments that fly to the part that would damage the outer tube when the arc tube explodes.

A specific example is shown in FIG. 3, and an enlarged view of the main part is shown in FIG. The metal halide lamp shown in the figure is
Ceramic thin tubes 134 and 136 (as buffers) are placed on the line connecting the arc tube 110 and the center part 130 of the front transparent part 112b of the outer tube 112, and on the line connecting the arc tube 110 and the center part 132 of the reflective part 112a of the outer tube 112. Each outer diameter 1
．． 0mm, inner diameter 0.5mm). and,
Metal wires of about 3 mm are inserted into the ceramic thin tubes 134 and 136, respectively, and the ceramic thin tubes 1
34 is supported by welding a metal wire to the lower holder 138 of the arc tube 110, while the ceramic thin tube 136 is supported by welding a metal wire to the upper holder 140 of the arc tube 110.

When the metal halide lamp constructed as described above was subjected to the same damage test as described above, the result was 43.
None of the tested lamps had damaged outer bulbs.

FIG. 5 shows the main parts of a metal halide lamp according to a second embodiment of the present invention, and the parts corresponding to those in FIG. In this embodiment, metal wires 242a, 242b and 244a, 2
44b, one end of each metal wire 242, 244 is welded and supported on the holder 238, 240, and the other end is crushed near the ceramic thin tube as shown in FIG.
246b to prevent it from falling off.

[0024] In each of the above embodiments, a ceramic thin tube was used as the buffer, but the buffer is not limited to this, and any material can be used as long as it is heat resistant and easy to process. Furthermore, although it is possible to install a plurality of buffers, it is preferable to set the buffer within a range where light loss is not substantially affected.

[0025]

[Effects of the Invention] As explained above, according to the metal halide lamp according to the present invention, since a buffer is provided between the arc tube and the approximate center of the front transparent part of the outer bulb, even if the arc tube explodes, Also, the outer tube will not be damaged.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a portion of the outer tube that would be damaged if the arc tube exploded.

FIG. 2 is an explanatory diagram of the reason why the portions where the outer tube is damaged are unevenly distributed.

FIG. 3 is an explanatory diagram of a metal halide lamp according to a first embodiment of the present invention.

FIG. 4 is an explanatory diagram of the main parts of the metal halide lamp according to the first embodiment.

FIG. 5 is an explanatory diagram of main parts of a metal halide lamp according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a state in which a ceramic thin tube is installed in a metal halide lamp according to a second embodiment.

FIG. 7 is an explanatory diagram of a metal halide lamp consisting only of an arc tube.

FIG. 8 is an explanatory diagram of a metal halide lamp having an outer tube formed by blown glass molding.

FIG. 9 is an explanatory diagram of a reflection type lamp having an outer tube made of blown glass.

FIG. 10 is an explanatory diagram of a reflective metal halide lamp having an outer bulb formed by glass molding.

11 is an exploded explanatory view of the reflective metal halide lamp shown in FIG. 10. FIG.

[Explanation of symbols]

10, 110, 210 Arc tube 12, 112 Outer tube 134, 136, 234, 236 Ceramic tube (buffer)

Claims (1)

[Claims] 1. A metal halide lamp having an arc tube provided within an outer bulb, characterized in that a buffer is provided between the arc tube and approximately the center of the front transparent portion of the outer bulb.