JPH0850880A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To provide a metal halide lamp capable of preventing leakage of a sealed material from a light emitting tube during keeping the life, having high life performance, light color similar to incandescent lamp color, and high color rendering property. CONSTITUTION:A light emitting tube 1 made of quartz has a pair of electrodes on the inside, a light emitting part 2 in which argon, mercury, and a metal halide having a composition of DyI3-TlI-CsI are sealed, and a sealing parts 3 which are arranged at both ends and seals a metal foil. The light emitting tube 1 is surrounded by a translucent cylinder 4, and the sealing parts 3 are protruded from the both ends apertures of the cylinder 4. A multilayer interference film serving as a reflecting film is formed in the cylinder 4. The length of the ligh't emitting part 2 of the light emitting tube 1 (c) is 16mm, the length of the sealing part 3 (a) is 13mm, and the length of the sealing part extruded from the sealing part 3 (b) is 6.5mm. That is, the relations of 4.3<=6.5<=13, 13<=16, and a/3<=b<=a, and a<=c are satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal halide lamp.

[0002]

2. Description of the Related Art Metal halide lamps are compact and
As the color rendering becomes higher, it tends to be frequently used in indoor commercial areas such as stores. Especially, the color temperature is 3000
A metal halide lamp having a light color close to that of an incandescent light bulb of up to 4000 K is widely used as a light source that creates a warm and high-class atmosphere.

The metal halide lamp which emits radiant light close to the color of the light bulb has been known for a long time using tin halide as an enclosure. However, the metal halide lamp using tin halide has a problem in that the low temperature part of the electrode is severely eroded by the enclosed material during the travel, causing the electrode to break.

Therefore, conventionally, in order to realize radiant light having a high color rendering and a color close to that of a light bulb without using tin halide which causes electrode breakage, the light emitting part and the sealing part of the arc tube are completely translucent. There is a metal halide lamp that is surrounded by the above and has a structure in which a light emitting tube and a transparent tube are supported inside an outer tube. Furthermore, this metal halide lamp, on the surface of the translucent cylinder,
A reflective film consisting of a multilayer interference film that reflects a part of visible region light is formed. Any color temperature can be selected by the characteristics of this multilayer interference film, and energy is emitted during multiple reflections by the multilayer interference film. It was returned to the pipe and high efficiency was obtained. By enclosing a metal halide containing a lanthanoid metal halide such as DyI _{3 in} such a conventional metal halide lamp, a high color rendering metal halide lamp having a color temperature of 3000 to 4000 K and an average color rendering index of 90 or more. Can be realized.

[0005]

However, a metal halide lamp having a structure in which a reflective film is formed on a translucent tube is
While part of the reflected light from the reflective film is returned to the arc tube to obtain high efficiency, the temperature of the arc tube rises compared to the case without the reflective film, and therefore the deterioration of the arc tube during the travel is remarkable. The problem arises. There are various factors in the deterioration of the arc tube, but a particular problem is the reaction between the material enclosed in the arc tube and the material of the arc tube. The reaction of such fill with the arc tube material, such as quartz, can be suppressed by reducing the arc tube load. However, apart from this, there is a problem that the enclosed material penetrates the arc tube sealing portion along the electrode and corrodes the surface of the metal foil used for hermetic sealing. This occurs because the temperature of the sealing portion and the metal foil rises due to the reflected light from the reflection film, and the inclusions react and erode on the contact surface between the metal foil and quartz. When such erosion progresses to the outer end of the metal foil, the inclusions leak outside the arc tube, and the lamp cannot be lit. In particular,
Since it is necessary to maintain the compactness of the metal halide lamp, when the length of the sealing portion is set to be equal to or less than the length of the light emitting portion, the temperature of the sealing portion rises, and the encapsulated material is likely to leak to the outside. It has been found that the above-mentioned problems particularly occur when a lanthanoid-based metal halide having high reactivity with quartz is encapsulated.

The present invention has been made in order to solve such a problem, and has a good travel characteristic without the inclusions leaking from the arc tube during the life of the discharge tube to prevent lighting. An object of the present invention is to provide a high color rendering metal halide lamp having a light color close to that of a light bulb.

[0007]

The metal halide lamp of the present invention has a pair of electrodes inside, a light emitting portion in which a metal halide and a buffer gas are sealed, and a light emitting portion which is connected to both ends of the light emitting portion. A light emitting tube having a sealing portion in which a metal foil is sealed, a transparent tube surrounding the light emitting tube, an outer tube containing the light emitting tube and the tube, and visible on the surface of the tube. A reflection film that reflects a part of the area light is formed, the sealing portion projects from both end openings of the cylinder, the length of the sealing portion is a (mm), and the projection projects from the cylinder. When the length of the sealing portion is b (mm) and the length of the light emitting portion is c (mm), a / 3 ≦ b ≦ a and a ≦ c
Has a configuration that is

[0008]

With this structure, leakage of the inclusions does not occur from the arc tube during travel.

[0009]

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

As shown in FIG. 2, a 100 W metal halide lamp according to an embodiment of the present invention has an arc tube 1 made of quartz and having an inner diameter of 10 mm. The arc tube 1 has a pair of electrodes (not shown) inside. No.), 10000 Pascal of argon as a buffer gas, 12 mg of Hg, DyI ₃ -T
a light emitting part 2 in which 2 mg of a metal halide having a composition of 11-CsI is enclosed, and the light emitting part 2 is connected to both ends of the light emitting part 2.
And a sealing portion 3 in which a metal foil (not shown) made of molyb foil is sealed. The arc tube 1 is surrounded by a translucent tube 4, and the sealing portion 3 of the arc tube 1 is provided so as to project from both end openings of the translucent tube 4. On the outer surface of the transparent cylinder 4, a multilayer interference film 13 made of TiO ₂ and SiO ₂ is formed as a reflective film. A heat reflection film 5 made of ZrO ₂ or the like is formed on the outer surfaces of both ends of the light emitting section 2 and the outer surface of the sealing section 3. External lead wires 6 and 7 connected to the electrodes are led out from the sealing portion 3 of the arc tube 1 via a metal foil. The arc tube 1 is supported in an outer tube 11 by connecting stem wires 9 and 10 led from a stem 8 and external lead wires 6 and 7, respectively. The light-transmitting tube 4 has a support 12
And the stem wire 10 are connected and supported in the outer tube 11. The inside of the outer tube 3 is in vacuum. As shown in FIG. 1, the length c of the light emitting portion 2 of the arc tube 1 is 16 mm, and the sealing portion 3 is
Has a length of 13 mm, and the length b of the sealing portion 3 protruding from the translucent cylinder 4 is 6.5 mm. That is, the length a of the sealing portion, the length b of the portion of the sealing portion protruding from the transparent tube, and the length c of the light emitting portion are 4.3 ≦ 6.5 ≦ 1.
3 and 13 ≦ 16, a / 3 ≦ b ≦ a and a ≦ c
Are satisfied with the relationship.

In FIG. 2, 14 is a getter, and 15 is a base. FIG. 3 shows transmission characteristics of visible region light of the light-transmissive tube with the multilayer interference film used in the metal halide lamp of one embodiment of the present invention (hereinafter, referred to as the lamp of the present invention). This multilayer interference film has a property of selectively reflecting the blue-green region of visible region light in order to bring the light color of the lamp closer to the light bulb color.

The characteristics of a conventional metal halide lamp (hereinafter referred to as a conventional lamp) in which the light emitting portion and the sealing portion of the lamp of the present invention and the light emitting tube are completely surrounded by a light-transmissive tube have a total luminous flux of 6300 lm and emitted light. Has a color temperature of 3700
K, the average color rendering index of emitted light is 97. However, when the life test of the lamp of the present invention and the life test of the conventional lamp were conducted, respectively, the conventional lamp showed 20
It was confirmed that 7 of the lamps could not be lit due to leakage of the inclusions, whereas the lamps of the present invention were not ignitable, and all 20 lamps were lit well.

Further, as a result of observing the metal foil by stripping off the heat-reflecting film on the sealing portion of the arc tube of the conventional lamp which could not be lit during its life, the whole metal foil turned brown due to the erosion of the inclusions. I was able to confirm that. In addition, as a result of cutting out and analyzing the cross section of the discolored part of the metal foil, it was confirmed that a slight gap was generated between the metal foil and quartz due to the reaction between the arc tube material quartz and the enclosed material. It was In addition, life span 6
As a result of performing the same observation on the conventional lamp that could be lit for 000 hours, the discoloration of the metal foil was 7
It has been confirmed that it has progressed to 0% or more. Therefore, if the life test of this conventional lamp is continued, it is clear that the corrosion of the metal foil progresses, the leakage of inclusions occurs, and finally it becomes impossible to light. Met.

On the other hand, as a result of the same observation as above for all the lamps of the present invention, even if the discoloration of the metal foil is the most advanced, it progresses to 50% or less of the metal foil. Therefore, according to the present invention, it is possible to prevent the metal foil from being eroded, and thus it is possible to prevent the lighting failure due to the leakage of the inclusions during the life. Further, even if the life test is continued for this lamp of the present invention, the reaction between the quartz and the filling material becomes slow, so that the leakage of the filling material from the arc tube does not occur. No lighting failure occurs.

Further, when the lamp of the present invention and the conventional lamp were assembled and mounted on the mount in the vacuum container with the outer tube lighted and the temperature of the central portion of the arc tube sealing portion was measured, the temperature of the conventional lamp was 730. While the temperature of the lamp of the present invention was 689 ° C., the temperature of the sealed portion of the lamp of the present invention was clearly lower than that of the conventional lamp.

In the present invention, since the reflected light from the reflective film returned to the sealing portion of the arc tube is reduced, the temperature rise of the sealing portion and the metal foil sealed in the sealing portion is suppressed. Further, since the portion of the sealing portion projecting from the openings at both ends of the translucent tube is not surrounded by the translucent tube having a relatively high temperature, there is no heat retaining effect by the translucent tube, and therefore the heat radiation Is promoted and the temperature of the sealing portion is reduced. That is, since the temperature of the sealing portion and the metal foil is lowered, the reaction between the sealed material and the arc tube material on the contact surface between the sealed portion and the metal foil is suppressed, and the speed of erosion of the metal foil by the sealed material is delayed. To be done. Therefore, it is possible to suppress the leakage of the inclusions from the arc tube during the travel, to obtain a metal halide lamp having a good travel characteristic, a light color close to that of an incandescent lamp, and a high color rendering property with excellent life characteristics. You can Further, the same effect can be obtained when a light emitting tube material, for example, a lanthanoid metal halide having high reactivity with quartz is enclosed.

Table 1 shows the relationship between the ratio of the portion of the sealing portion protruding from the translucent tube, the temperature of the central portion of the sealing portion, and the generation state of non-lightable products during the life.

[0018]

[Table 1]

As is clear from Table 1, if the rate of the portion of the sealing portion protruding from the transparent tube, that is, the sealing portion protrusion rate b / a is 1/3 or more, the sealing portion It can be seen that the temperature of the central portion becomes 700 ° C. or lower, and no non-lightable products are generated during the movement of the rated life of 6000 hours. On the other hand, when the length b of the portion of the sealing portion protruding from the transparent tube exceeds the length a of the sealing portion, that is, even the light emitting portion of the arc tube projects from both ends of the transparent tube. In such a case, even the heat retention of the coldest part in the arc tube near the electrode in the arc tube is impaired, so that the vapor pressure of the enclosed material is reduced, the color temperature of the lamp is changed, and the color rendering property is significantly reduced.

As described above, in the metal halide lamp of the embodiment of the present invention, an optional light color close to, for example, an incandescent lamp color can be selected by the reflection film, and a highly reactive lanthanoid metal halide such as DyI _3. It is possible to provide an extremely high color rendering metal halide lamp having good travel characteristics without the leakage of the inclusions from the arc tube during the life even when the is enclosed.

In the above embodiment, the enclosed halide has a composition of DyI ₃ -TlI-CsI.
Halides having other compositions may be used. Further, although the multilayer interference film made of TiO ₂ and SiO ₂ is used as the reflection film, the reflection film made of other materials may be used. Further, the reflective film is formed on the outer surface of the translucent cylinder, but it may be formed on the inner surface or both the inner and outer surfaces. Furthermore, materials other than quartz may be used for the arc tube and the transparent tube.

[0022]

As described above, according to the present invention, it is possible to prevent the inclusions from leaking from the arc tube during the life, have a good travel characteristic, and have an excellent light color and life characteristic close to the bulb color. It is possible to provide a metal halide lamp with high color rendering.

[Brief description of drawings]

FIG. 1 is an enlarged front view of a main part of a metal halide lamp according to an embodiment of the present invention.

FIG. 2 is a front view of the same metal halide lamp.

FIG. 3 is a diagram showing a transmittance characteristic of visible region light of a light-transmitting cylinder having a multilayer interference film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 luminous tube 2 luminous part 3 sealing part 4 translucent cylinder 5 heat reflection film 13 multilayer interference film

Claims (3)

[Claims] 1. A light emitting part having a pair of electrodes inside and containing a metal halide and a buffer gas sealed therein, and a sealing part continuous with both ends of the light emitting part and sealed with a metal foil. A light-transmitting tube surrounding the light-emitting tube, an outer tube containing the light-emitting tube and the tube, and a reflective film for reflecting a part of visible region light on the surface of the tube. The sealing portion is formed and protrudes from both end openings of the cylinder, the length of the sealing portion is a (mm), and the length of the portion of the sealing portion protruding from the cylinder is b ( mm), and when the length of the light emitting portion is c (mm), a / 3 halide lamps satisfying a / 3 ≦ b ≦ a and a ≦ c. 2. The metal halide lamp according to claim 1, wherein the arc tube is made of quartz. 3. The metal halide lamp according to claim 1, wherein the metal halide contains a lanthanoid metal halide.