JPH04133256A - Double tube type metal halide discharge lamp for illumination use - Google Patents

Abstract

PURPOSE:To have light emission with stable color temp. by coating the surface of an outer tube with a transparent film consisting of Ti oxide and Si oxide and having a thickness over 50nm, wherein the mol ratio ranges 6:4 thru 2:8, and including a fine powder of ceramic material in this transparent film in such a way as well dispersed. CONSTITUTION:A transparent film F consisting of Ti oxide and Si oxide is formed on the surface of an outer tube 20. This hybrid film F shall be in composition such that the mol ratio of Ti oxide to Si oxide ranges 6:4 thru 2:8, and ceramic material fine powder of Si oxide etc., is dispersed therein. The film F shall have a thickness over 50nm, and particle sizes of fine powder of Si oxide preferably lie between 0.1mum and several mums. The light penetrating the film F is diffused by the fine powder of ceramic material as dispersed in the film F, so that well mixed light with high uniformity is obtained. This enables relieving chromatic unevenness and illuminance unevenness in the region not irradiated with light in satisfactory performance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a double-backed metal halide discharge lamp used for general lighting.

[Conventional technology]

In general, metal halide lamps have a higher light radiation efficiency than normal halogen lamps, and for example, 3000
Since it is relatively easy to produce a product with a high color temperature of K or higher and provides synchrotron radiation with excellent color rendering, it is suitable for lighting for various products, indoor or outdoor lighting, and other general lighting. It can be used for.

However, since the color temperature of a metal halide lamp when it is lit is easily affected by temperature, a double back type lamp is used in which the metal halide lamp is enclosed within an outer bulb.

[Problem to be solved by the invention]

However, even with a double-backed metal halide discharge lamp, the color temperature of the emitted light changes depending on the lighting position, such as whether it is lit upward, downward, or horizontally. It has been found that there is a problem in that a stable lighting effect cannot be obtained.

In addition, mercury is sealed in the light emitting space of a metal halide lamp to maintain the discharge, but a large amount of ultraviolet rays are emitted due to this, and when irradiated with ultraviolet rays, it has an adverse effect on the illuminated objects such as the human body and products. Therefore, in this respect, there is a problem that it is not preferable as a light source for general illumination.

Furthermore, when the outer bulb of a double-back metal halide discharge lamp is sealed at one end, the shape of the tip, especially the presence of a tip at the tip, can greatly disrupt the light distribution in the irradiated area. There are some problems with the condition.

The purpose of the present invention is to solve the above problems, and to make it possible to always obtain emitted light with the same stable color temperature even when the lighting is in a lighting position such as the above, and to emit less ultraviolet rays, An object of the present invention is to provide a double-tube metal halide discharge lamp for illumination, which can achieve illumination with high uniformity of color and light intensity distribution in the irradiated area.

[Means to solve the problem]

The double-tube metal halide discharge lamp for illumination of the present invention is characterized by a metal halide lamp enclosed in a transparent outer tube, and titanium oxide (TiO2) on the surface of the outer tube.
A transparent film with a thickness of 50 nm or more is formed, consisting of J and silicon oxide (Sin), with a molar ratio of titanium oxide and silicon oxide of 6.4 to 2:8, and this transparent film is made of ceramic. The point is that the material is finely powdered or dispersed.

[Effect]

In a metal halide discharge lamp with such a configuration, a light-transmitting film having a thickness exceeding a certain value and made of a mixture of titanium oxide and silicon oxide with a certain molar ratio is formed on the surface of the outer bulb. This light-transmitting film reflects infrared rays, raising the temperature of the outer bulb and greatly exerting a heat-insulating effect on the metal halide lamp inside.
The temperature state in the envelope of the metal halide lamp is stabilized, and the influence of the lighting posture is significantly suppressed. Moreover, since the light-transmitting film of the outer tube also has an ultraviolet absorption function, harmful ultraviolet rays are prevented from being emitted. In addition, since the light-transmitting film is dispersed with fine powder of ceramic material, the light passing through the film is scattered, and as a result, the area to be irradiated with light has high uniformity with no color unevenness or uneven illuminance. illumination is achieved. This is because when a metal halide lamp is turned on, parts of different colors are formed in the arc due to the difference in mass of metal atoms, resulting in color unevenness in the irradiated area, or the emitted light is scattered by the transparent film. This is because, by doing so, the occurrence of color unevenness in the irradiated area is prevented, and also the occurrence of light intensity unevenness is prevented.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 shows the configuration of an example of a double-back type metal halide discharge lamp according to the present invention, and shows a small metal halide lamp I.
It is enclosed within the outer tube 20.

The metal halide lamp 10 includes an enclosure 11 made of quartz glass, and a pair of metal foils 13 and 13 sealed in a sealing part 12 at one end of the enclosure 11. The metal halide lamp 10 has discharges extending from a pair of metal foils 13 and 13 and facing each other within the enclosure 11. In addition to mercury, metals such as lithium, thallium, sodium, and indium, and halogen are sealed in the enclosure 11. 1
Reference numeral 5 denotes a chip portion formed at the other end of the enclosure 1.

The outer tube 20 is a sealed tube with one end sealed and has an internal space S that is sufficiently larger than the metal halide lamp 10, and is made of quartz glass.
A pair of metal foils 23 and 23 are sealed in the sealing part 22 located at the end on the sealing part 12 side. The tip of a support lead wire 21.21 extending from the metal foil 13.13 of the metal halide lamp 10 to the outside of the envelope 1 is connected to the metal foil 23.23.
1 supports the metal halide lamp IO. A tip portion 24 is formed at the end of the outer tube 20 on the same side as the tip portion 15 of the metal halide lamp 10, and an internal space S of the outer tube 20 is filled with, for example, nitrogen gas.

The sealing portion 22 of the outer tube 20 is held and fixed to a ceramic base 3o, and external leads (not shown) extending outward from the metal foil 23.23 are connected to lead bins 31.31 protruding from the base 30. There is.

A light-transmitting film F made of titanium oxide and silicon oxide is formed on the surface of the outer tube 20. The composition of this transparent film F is such that the molar ratio of titanium oxide silicon dioxide is 6:4 to 2:8.
It is a mixture of a range of 100% and 100% fine powder of ceramic material such as silicon oxide is also dispersed therein. The thickness of the light-transmitting film F is 50 nm or more, and the particle diameter of the fine powder made of silicon oxide is not particularly limited, but is preferably about 0.1 μm to several μm.

This light-transmitting film F covers the outer peripheral surface of the outer tube 20 and the tip portion 24.
It is preferable to form it on the leading end surface including the

In order to form the transparent film F, for example, titanium alcoholate (Tico C, H5) 2) and silicon alcoholate (Sl(OCzHs) 4) are mixed, and an appropriate amount of oxidation is added to the mixed solution. It is advantageous to add silicon and apply this dispersion liquid to the surface of the outer tube 20 by dipping or the like, followed by firing. The dispersion liquid may contain appropriate additives as necessary.

As the fine powder of the ceramic material dispersed in the transparent film F, in addition to silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, etc. can be used.

Since the double-tube metal halide discharge lamp for illumination of the present invention has the above configuration, the composition of the transparent film F formed on the surface of the outer bulb 20 is a mixture of titanium oxide and silicon oxide. Since the molar ratio is 64 to 2:8 and the thickness of the transparent film F is 50 nm or more, the visible light of the light emitted from the metal halide lamp 10 is sufficiently transmitted through the transparent film F. However, some of the infrared rays are reflected and some of the ultraviolet rays are absorbed.

Since the visible light of the light emitted from the metal halide lamp 10 sufficiently passes through the light-transmitting film F, sufficient visible light is emitted from the outer tube 20, and therefore good color rendering properties are exhibited. The intended general illumination can be suitably provided.

However, since a part of the infrared rays from the metal halide lamp 10 is reflected by the transparent film F on the surface of the outer bulb 20, the temperature of the tube wall of the outer bulb 20 increases, and as a result, a large heat retention effect is exhibited. As a result, the temperature state of the envelope 11 of the metal halide lamp 10 becomes stable. This heat retention effect is reliably achieved without being affected by the lighting position, so a stable color temperature can be obtained regardless of the lighting position, and stable illumination can always be achieved. can. That is, in the metal halide discharge lamp of the present invention, the color temperature of the emitted light does not change depending on the lighting orientation, and the same illumination effect can always be obtained.

To be more specific, in the double-backed metal halide discharge lamp having the configuration shown in FIG. Therefore, between the upward position shown in FIG. 1 in which the tip portion 15 is upward, the downward posture opposite to that shown in FIG. If there is no light-transmitting film F, the temperature state of the enclosure 11 will be significantly different, and as a result, the color temperature of the emitted light will be significantly different even under the same lighting conditions.

However, in the metal halide discharge lamp of the present invention, since the outer bulb 20 has a light-transmitting film F, the temperature condition is improved as described above, and the same lighting effect can always be obtained regardless of the lighting orientation. .

This is thought to be because the above-mentioned heat retention effect is large, so that the influence of the coldest point of the chip portion 15 is substantially eliminated or significantly alleviated, resulting in a uniform temperature distribution state in the sealing body 11. .

Furthermore, since the transparent film F has an ultraviolet absorbing effect, the ultraviolet rays emitted from the metal halide lamp 10 are blocked and prevented from being emitted to the outside from the outer bulb 20, and as a result, when used for general lighting. Even in this case, the harmful effects of ultraviolet rays can be reliably prevented.

Further, since the light transmitted through the light-transmitting film F is scattered by the fine powder of the ceramic material dispersed in the light-transmitting film F, the light becomes sufficiently mixed and highly uniform. As a result, color unevenness and illuminance unevenness in the light irradiation area are sufficiently alleviated, and from this point of view as well, there is no problem with the lighting position, and regardless of the lighting position, uniformity is always maintained in the irradiation area. A high lighting effect can be obtained. This effect is particularly significant when the double-backed metal halide discharge lamp is used in combination with a reflector.

In the present invention, the composition of the light-transmitting film F other than the fine powder of the ceramic material is such that the molar ratio of titanium oxide and sulfur oxide is 6:
It is necessary that the ratio is 4 to 2:8, especially 5:5 to 3.
7 is preferable.

If the proportion of titanium oxide is too large, the ultraviolet shielding rate will be high. Interference colors will appear in F, and as a result, there is a great possibility that color unevenness will occur in the emitted light. On the other hand, if the proportion of titanium oxide is too small, the degree of rise in temperature of the outer tube 20 will be low, the heat retention effect will not be sufficiently obtained, and the ultraviolet blocking rate will also be low, so that the purpose of the present invention cannot be fully achieved. cannot be achieved.

The thickness of the light-transmitting film F must be 50r++n or more, and if it is less than 50nm, the above effects cannot be obtained sufficiently. Although there is no need to set an upper limit on the film thickness,
Considering the conditions for film formation, it is realistic to have a thickness of about 300 nm or less.

Furthermore, since the fine powder dispersed in the transparent film F is a fine powder of a ceramic material, the fine powder has a high affinity with the material of the transparent film, and the transparent film F becomes strong. It also has great adhesion to.

Next, the effects of the present invention will be specifically explained.

According to the example of FIG. 1, the distance between the discharge electrodes 14 and 1.4 is 5
A metal halide lamp 10 with a diameter of 7 mm and a rated power consumption of 150 W was used, and was sealed in the outer tube 20 with nitrogen gas. Then, titanium alcoholate and silicon alcoholate were mixed in a ratio such that the molar ratio of titanium to silicon was 4:6, and the mixed solution had an average particle size of 1.9 μm.
A dispersion liquid was prepared by adding 50g of silicon oxide fine powder of m to 500ml of a mixed solution, and this dispersion liquid was applied to the surface of the outer tube 20 by a dipping method, and dried at 120°C for 5 minutes. After baking at 600℃ for 10 minutes, the film thickness is 1.
A 50 nm transparent film F was formed to produce a double back type metal halide discharge lamp.

When this metal halide discharge lamp was lit in upward, downward, and horizontal positions, the color temperature of the emitted light was 2,900 to 3.10 in all lighting positions.
It was stable in the 0K range, was substantially the same in each lighting position, and moreover, a highly uniform illumination effect was obtained in the irradiated area.

On the other hand, when a similar lighting test was conducted on a double-backed metal halide discharge lamp with the same configuration except that no transparent film was formed, the color temperature of the emitted light was 2.800 to 3.
．． It varied greatly in the range of 200 K, and the illumination effect changed greatly as the lighting position changed, and large color unevenness and illuminance unevenness occurred in the irradiated area.

FIG. 2 shows the relationship between the wavelength of transmitted light and the transmittance when a transparent film similar to that described above is formed on quartz glass except that fine silicon oxide powder is not dispersed therein. As is clear from this curve, the wavelength is 300 nm or less, especially 25 nm.
The transmittance of ultraviolet rays below Or+n+ is extremely low. Curve B is a case where a light-transmitting film is formed with a molar ratio of titanium oxide and silicon oxide of 2:8, and the transmittance of ultraviolet rays is similarly low. Moreover, curve MC shows the case of quartz glass without a light-transmitting film, and it is clear that the transmittance of ultraviolet rays is high.

In the present invention, the tip portion 2 of the outer tube 20 may be
Opaque heat-resistant coating B can be applied to the surface of the tip portion including 4. This heat-resistant coating B is formed by applying a coating agent containing, for example, alumina powder and zirconia powder and adding a black coloring agent to the coating material, and firing the coating material. When this heat-resistant coating B is applied, the transparent film F may or may not be formed in the area.

When this heat-resistant coating B is applied, infrared rays are absorbed or reflected by the heat-resistant coating, so that an even higher heat retention effect can be obtained for the metal halide lamp 1o inside. In addition, because the heat-resistant coating B prevents light from being emitted to the outside from the tip portion where the tip portion 24 is present, the light distribution in the irradiated area is significantly disturbed, which would otherwise be caused by the presence of the tip portion 24 at the tip portion. From this point of view as well, a highly uniform illumination effect can always be obtained in the illuminated area, regardless of the lighting orientation.

〔Effect of the invention〕

As described above, according to the double-tube metal halide discharge lamp for illumination of the present invention, it is possible to obtain radiated light with a stable color temperature even in the lighting position, and the amount of ultraviolet rays emitted can be reduced. Furthermore, it is possible to make the emitted light sufficiently scattered, and therefore it is possible to suitably realize stable illumination at all times regardless of the lighting position, and moreover highly uniform illumination in the illuminated area. can.

[Brief explanation of drawings]

FIG. 1 is an explanatory front view of a double-tube metal halide discharge lamp for illumination according to an embodiment of the present invention, and FIG. 2 is a characteristic curve diagram showing the relationship between wavelength and transmittance of transmitted light. lO...Metal halide lamp 11...Encapsulation body I2...Sealing part 13.
...Metal foil 14...Discharge electrode 15...
Chip part 20...Outer tube 21...Support lead wire 22...Sealing part 23...Metal foil
24... Chip part 30... Base
31...Lead bin S...Inner space B...Heat-resistant coating F...Transparent film

Claims (1)

[Claims] A metal halide lamp is enclosed in a transparent outer tube.
On the surface of the outer tube, a film with a thickness of 50 nm is made of titanium oxide (TiO_2) and silicon oxide (SiO_2) and has a molar ratio of titanium oxide and silicon oxide of 6:4 to 2:8.
A double-tube metal halide discharge lamp for lighting, characterized in that the transparent film described above is formed, and fine powder of a ceramic material is dispersed in the transparent film.