JPH07320688A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To provide a metal halide lamp having a light source color having an arbitrary color temperature within a range of 2000-6000K by stabilizing characteristics as a light source adopting a light interference filter films, so as to reduce fluctuation, selecting the metal halide lamp having a high color temperature, and utilizing a color temperature decreasing effect of the light interference filter film. CONSTITUTION:Electrodes 2, 3 are sealed at both ends of a light emitting tube 1, into which dysprosium iodide, neodium iodide, cesium iodide, mercury and argon gas are enclosed. Heat insulating films 4, 5 are formed at the outer surface at the end of the light emitting tube 1. Light interference filter films 6 are disposed at the outer surface held between the heat insulating films 4, 5. The light interference filter film has the two-layer structure, where a first layer is made of tantalum oxide while a second layer is composed of silicon dioxide.

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 which has an improved color temperature of light as an optical characteristic.

[0002]

2. Description of the Related Art In recent years, metal halide lamps tend to be used properly according to their color temperature. For example, a light source color such as the setting sun, a light source color such as the morning sun, a neutral white color such as the sun, and a daylight color such as the blue sky. When you want to produce lighting, 2000-3000K, 3000-4
000K, 4000-5000K and 6000-700
Lamps with a color temperature of 0K have been used. By the way, since the color temperature of the metal halide lamp is determined mainly by the type of the filling material in the arc tube, it is not suitable to use the metal halide lamp as it is for the purpose of producing a light source color of any other color temperature.

Here, if a known technique of providing an optical interference filter film on the surface of a translucent substrate surrounding the light source and converting the color temperature of the light source by this film is used, a lamp having a desired color temperature can be obtained. In order to provide it, it will be realized by adjusting the spectral transmittance characteristic of the optical interference filter film. This brings about an advantage that it is possible to produce light source colors of many kinds of color temperatures by only preparing one kind of arc tube as a light source, which requires advanced quality control because the characteristics are likely to vary. This is useful for mass producing such metal halide lamps having various color temperatures.

The present inventor has already formed an optical interference filter film on the surface of an arc tube or the like in a metal halide lamp in which at least each iodide of dysprosium (Dy) and thallium (Tl) is enclosed in the arc tube. Color temperature of 4500-6000K in the absence state is about 1000-2500K
We have proposed a metal halide lamp that has been reduced to realize a light source color with a color temperature of 3000 to 4000K. This optical interference filter film can be configured not only to reduce the color temperature but also to increase the color temperature by adjusting the film thickness of each layer. The color temperature inside the arc tube during lighting is 4500-6
Only one type of arc tube of the Dy-Tl type metal halide lamp of 000K has a color temperature of 2000-75.
It is possible to provide a metal halide lamp having a desired color temperature in the range of 00K.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Dy-Tl
The system metal halide lamps have the drawbacks that quality control is difficult and that not only the initial characteristics but also the travel characteristics are liable to be unstable and the characteristics among lamps vary widely. Therefore, the emission spectral distribution inside the arc tube, which is the most important factor when applying a light interference filter film to this lamp to perform color temperature conversion, is not constant over time and between lamps. Therefore, it is not always guaranteed that the desired color temperature is obtained.

Further, the Dy-Tl type metal halide lamp is liable to cause phenomena such as blackening of the inner surface of the arc tube and defects at a relatively early time after the start of lighting during continuous lighting, and generally has a short life. There is a problem. Therefore, Dy
The -Tl metal halide lamp cannot be said to be suitable as a light source to which an optical interference filter film is applied in order to obtain a light source color having an arbitrary color temperature in a wide range of 2000 to 7500K due to the color temperature conversion effect.

Next, when an optical interference filter film having a film characteristic that causes an increase in color temperature is applied, there is a problem that a desired degree of increase in color temperature cannot be obtained. The possible reasons for this are as follows. That is,
The optical interference filter film exerts the effect of increasing the color temperature because it has a spectral transmittance such that it transmits light in the wavelength range of approximately 350 to 600 nm in the visible light range and reflects light in the wavelength range of 600 to 800 nm. This means that the optical interference filter film also reflects a long-wavelength component of visible light, that is, a component that contributes as heat. Therefore, the filter film reflects the heat energy component radiated from the inside of the arc tube to bring about a heat retaining effect. Therefore, the component on the long wavelength side is strengthened as compared with the case where the film is not applied, and this acts in the direction of lowering the color temperature. After all, there are two contradictory effects of color temperature decrease and color temperature increase,
The latter effect partially offsets the former effect.

FIG. 8 shows an example of the spectral transmittance characteristics of an optical interference filter film that causes an increase in color temperature. For example, dysprosium (Dy) -thallium (Tl) -cesium (Cs) having a color temperature of 4850K without a film.
When the optical interference filter film having the characteristics shown in FIG. 8 is applied to the system metal halide lamp, the color temperature of this lamp is 58
The color temperature was 00K, and the color temperature was about 700K lower than the predicted value of 6520K when the heat retaining effect of the film was not considered. FIG. 3 shows the spectral irradiance of this lamp in comparison with the state without a film (broken line in the drawing) and the case where a filter film having the characteristics of FIG. 8 is applied (solid line in the drawing). 600
It can also be seen from FIG. 3 that the emission components in the wavelength region of up to 800 nm are not significantly reduced. Therefore, when the original color temperature of the lamp is lower than the desired color temperature, the method of applying the light interference filter film and realizing the desired color temperature by the effect of increasing the color temperature also has the effect of lowering the color temperature by the heat retaining effect of the film. Since it coexists and partially offsets the effect of increasing the color temperature, it is hard to say that this is an efficient method.

The present invention has been made in view of the above, and in order to take advantage of the fact that only one type of arc tube is required, the method of utilizing the color temperature conversion effect of the light interference filter film is left and the light interference filter film is used. As a light source to be applied, a metal halide lamp with stable characteristics and less variation and a high color temperature is selected, and a light source color having an arbitrary color temperature in the range of 2000 to 6000K is given by the color temperature lowering effect of the light interference filter film. The purpose is to provide a metal halide lamp.

[0010]

A first metal halide lamp according to the present invention comprises at least an arc tube containing a metal halide, mercury and a rare gas, and an outer tube containing the arc tube. In a metal halide lamp comprising an optical interference filter film having a function of lowering the color temperature of incident light on at least one of the surface of a tube or the surface of a light-transmissive member surrounding the arc tube, the metal halide lamp comprising: The internal color temperature is 6000-7500K,
Further, the optical interference filter film is a multilayer film having two or more layers, and the spectral transmittance curve of the film forms a valley-shaped depression having a minimum transmittance value of 80% or less on the short wavelength side of the visible light region. Then
The wavelength position of the minimum transmittance is in the region of 500 nm or less, and the transmittance of the film in the wavelength region of 600 to 800 nm is 7 or less.
It is characterized by having a spectral transmittance characteristic of 0% or more.

A second metal halide lamp according to the present invention is characterized in that, in the first metal halide lamp, the metal halide is at least dysprosium, neodymium and cesium iodide.

A third metal halide lamp according to the present invention is the same as the first or second metal halide lamp, wherein the optical interference filter film has at least Ta ₂ O ₅ —SiO ₂ , TiO ₂ —SiO ₂ , and ZrO ₂ −
It is characterized by containing a combination selected from the combination of metal oxides composed of SiO ₂ or Nb ₂ O ₅ —SiO ₂ .

[0013]

In the first metal halide lamp of the present invention, the color temperature inside the arc tube is 600 at the time of lighting as a light source to which the light interference filter film having a color temperature converting effect is applied.
Since the metal halide lamp of 0 to 7500K was selected, the light source color of the color temperature of 6000 to 7500K can be obtained by using this metal halide lamp as it is.
Further, all the color temperatures in the range of 2000 to 6000K may be realized by the color temperature lowering effect of the optical interference filter film, and there is an advantage that it is not necessary to depend on the color temperature increasing effect of the filter film. Further, the optical interference filter film is a multilayer film having two or more layers, and the spectral transmittance curve of the film has a valley-shaped depression having a minimum transmittance of 80% or less on the short wavelength side of the visible light region. Since it has a spectral transmittance characteristic that the transmittance is set to 70% or more in the wavelength region of 600 to 800 nm and the wavelength position of the transmittance minimum value is 500 nm or less. ~ 4000
It is possible to effectively use the color temperature conversion effect of the film because the color temperature can be reduced to an arbitrary value within the range of K and the heat retention effect of the film, which has the opposite effect of increasing the color temperature, can be suppressed to a small level.

The second metal halide lamp of the present invention is
The color temperature inside the arc tube is as high as 6200 to 7200K, the range characteristics are stable, and the variation in characteristics between lamps is small, so that the desired color temperature is always obtained when the light interference filter film is applied.

The third metal halide lamp of the present invention comprises:
The optical interference filter film has excellent heat resistance and can maintain initial characteristics for a long period of time.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A metal halide lamp according to the present invention will be described with reference to the drawings. FIG. 1 is a partially cutaway schematic view of the metal halide lamp of the first embodiment. 1 is a light emitting tube made of quartz, the electrodes 2 and 3 was sealed at both ends, the internal iodide and dysprosium (DyI _3), iodide neodymium (NdI ₃₎ and cesium iodide (CsI) and mercury It is filled with argon gas. On the outer surface of the end of the arc tube 1, heat insulating films 4 and 5 made of fine particles such as zirconium oxide (ZrO ₂ ) are formed. An optical interference filter film 6 is provided on the outer surface of the arc tube 1 sandwiched by the heat insulating films 4 and 5. Reference numeral 7 is a quartz glass sleeve provided around the arc tube to prevent scattering of fragments of the arc tube. Reference numerals 8 and 9 denote arc tube supports that also serve as lead wires, and support the arc tube 1 in an outer tube 10. The description of other constituent elements of the lamp is omitted. Thus, the metal halide lamp 11 (Example I) having a rated power of 150 W is configured.

Here, the optical interference filter film 6 is a two-layer film and has a film structure shown in Table 1 as a film structure I.
The layer is composed of, for example, tantalum oxide (Ta ₂ O ₅ ),
The second layer is composed of silicon dioxide (SiO ₂ ).
The film formation of each layer of the optical interference filter film 6 was performed by a known method, for example, a low pressure CVD method.

[0018]

[Table 1]

The metal halide lamps of Examples II to IV are
Except for the optical interference filter film provided on the outer surface of the arc tube, the constituent elements have the same specifications as in Example I.
The film formation of each layer of the optical interference filter film was performed in the same manner as in Example I. The optical interference filter films in the metal halide lamps of Examples II, III and IV are three-layer film, five-layer film and seven-layer film, respectively, and the film configurations shown in Table 1 as film configurations II, III and IV, respectively. And the high refractive index layer has, for example, tantalum oxide (Ta
₂ O ₅ ) and the low refractive index layer is made of, for example, silicon dioxide (SiO ₂ ).

The color temperature conversion effect of the optical interference filter films in Examples I to IV was evaluated as follows. First, a metal halide lamp having the same specifications as in Examples I to IV was prepared except that the light interference filter film was not formed on the outer surface of the arc tube, and the color temperature, the spectral irradiance, etc. in the state without the light interference filter film were prepared. The lamp characteristics were measured. Next, after destroying the lamp and taking out only the arc tube and forming an optical interference filter film of film constitutions I to IV corresponding to Examples I to IV on the outer surface of the arc tube by a known method, The lamp was assembled again to complete the metal halide lamps of Examples I to IV, and the lamp characteristics such as color temperature and spectral irradiance in the state of having the optical interference filter film were measured.

The color temperatures of the metal halide lamps of Examples I to IV at the rated lighting, the color temperature change as compared with the filmless state, the average color rendering index (Ra) and the chromaticity coordinates (x, y) are shown. 2 shows. It should be noted that the lamp characteristics in the state without a film have a color temperature of 6490 to 653 in Examples I to IV.
0K, average color rendering index (Ra) is 95, chromaticity coordinates are x = 0.212 to 0.313, y = 0.330.
It was 0.333.

The spectral irradiance of the metal halide lamp of Example III among Examples I to IV is shown in FIG. In FIG. 2, the solid line represents the characteristics when the light interference filter film is provided on the surface of the arc tube, and the broken line represents the characteristics when the film is not provided. From FIG. 2, the emission components on the shorter wavelength side than this wavelength are significantly and uniformly reduced at around 550 nm as compared with the case where there is no film, and conversely, the emission components on the longer wavelength side than about 550 nm are film. It can be seen that the increase is uniform compared to the case without. Such a change in the spectral irradiance due to the presence or absence of the film is reflected in the change in the color temperature from the color temperature 6490K without the film to the color temperature 3490K with the film.

Thus, the internal color temperature is approximately 6500K.
By adjusting the spectral transmittance characteristics of the optical interference filter film applied to the outer surface of one type of arc tube, the color temperature of the light emitted from the inside of the arc tube is about 1
It was possible to obtain four kinds of metal halide lamps each having four different color temperatures within the color temperature range of 2000 to 6000K by decreasing by 000K. As can be seen from the Ra values and the chromaticity coordinates (x, y) shown in Table 2, the metal halide lamps of Examples I to IV are the same as the existing high color rendering metal halide lamps having substantially the same color temperature. Compared with each other in terms of color rendering, the light source color of white or yellowish white to light yellow red is obtained.

The spectral transmittance characteristics of the optical interference filter film applied to the metal halide lamp were confirmed as follows. That is, at the time of forming the light interference filter film on the outer surface of the arc tube, at the same time, a film is formed on the outer surface of another arc tube having the same specifications, and the surface of the fragments obtained by destroying this arc tube. The spectral transmittance of the film was measured. Spectral transmittance characteristics of the optical interference filter films applied to Examples I, II, III and IV thus obtained are shown in FIGS. 4, 5, 6 and 7, respectively.

By the way, it is well known that the form of the spectral transmittance curve of the optical interference filter film changes variously depending on the combination of the refractive index and the film thickness of each layer constituting the film. Therefore, with respect to the optical interference filter film applied to the light source, many studies have been conducted by changing the combination of the refractive index and the film thickness of each layer to change the form of the spectral transmittance curve of the film. As a result, the number of layers of the optical interference filter film is not limited to the above-described examples, and whatever the combination of the refractive index and the film thickness (including the difference in the number of layers) can be implemented. It is a multi-layered film of two or more, and "the spectral transmittance curve of the film forms a valley-shaped depression having a minimum transmittance value of 80% or less on the short wavelength side of the visible light region, and the wavelength position of the minimum transmittance value is formed. Exists in the region of 500 nm or less, and 600 to 800 nm
The transmittance of the film in the wavelength region of is 70% or more. "
It has been found that when the filter film is applied to a light source having a color temperature of 000 to 7500K, a reduction in color temperature of any size in the range of 500 to 4000K can be realized. vice versa,
If the above conditions are not met, some disadvantages occur. This will be described below.

First, regarding the number of layers of the optical interference filter film, in the case of a single-layer film, 400 is most effective in reducing the color temperature.
It is difficult to provide a spectral transmittance characteristic that reflects only a relatively narrow wavelength region of up to 500 nm. FIG. 9 shows an example of the spectral transmittance characteristics of a single layer film. The wavelength position of the minimum transmittance is 400 to 500 nm.
It can be seen from FIG. 9 that even if the wavelength range is set to, the reflection region will spread before and after that. As a result, when the single-layer film is applied, the color temperature decrease of less than 500K is not sufficient. Therefore, it is preferable that the number of layers is two or more, and thin films having different refractive indexes are laminated to form a film.

Next, regarding the depth and position of the valley-shaped depression of the spectral transmittance curve, if the minimum value of the valley-shaped depression exceeds 80%, the magnitude of the color temperature decrease is less than 500K, which is not sufficient. When the wavelength position of the minimum value of the valley-shaped depression is on the longer wavelength side than 500 nm, the magnitude of the color temperature decrease is 50.
It becomes less than 0K or causes an increase in color temperature, which is not preferable. When the number of layers of the optical interference filter film is increased, the minimum value of the valley-shaped depression of the spectral transmittance curve approaches 0%. However, in this case, the number of layers is large and the decrease in color temperature is small, which is inefficient, and the light transmitted through the film is completely colored light. Therefore, if it is desired to avoid completely colored light, the number of layers of the optical interference filter film should be 8 or less, and the minimum value of the valley-shaped depression of the spectral transmittance curve should be approximately 15% or more. It is desirable to adjust the transmittance characteristics.

Further, regarding the transmittance of the film in the wavelength region of 600 to 800 nm, when the transmittance of this region is less than 70%, the main valley-shaped depression of the spectral transmittance curve is a short wavelength in the visible light region. Even if it exists on the side, the color temperature decrease is not sufficient for the number of layers or the color temperature increases, which is not preferable.

In the above-mentioned embodiment, the case where the metal halide to be sealed in the arc tube is three kinds of DyI ₃ , NdI ₃ and CsI has been described, but the present invention is not limited to these materials and other materials. A small amount of another metal halide may be added. Further, if the color temperature inside the arc tube becomes 6000 to 7500K at the time of lighting and stable lamp characteristics are provided, a combination of metal halides other than the above three types can be selected.

Further, in the above-mentioned embodiment, the formation portion of the light interference filter film is entirely the outer surface of the arc tube of the metal halide lamp, but the surface of the outer tube of the lamp or a transparent lamp constituent member surrounding the arc tube. For example, it may be formed on the surface of a tubular sleeve. Further, the combination of metal oxides forming the optical interference filter film was Ta ₂ O ₅ —SiO ₂ , but Ta ₂ O ₅ —SiO ₂ , TiO ₂ —SiO ₂ , Zr.
Any combination of O ₂ —SiO ₂ and Nb ₂ O ₅ —SiO ₂ may be used. Therefore, the optical interference filter film is made of, for example, aluminum oxide (Al ₂ O ₃ )
Other metal oxides such as may be included as a single thin layer or in the form of mixed oxides.

[0031]

In the first metal halide lamp of the present invention, the metal halide lamp having a high color temperature of 6000 to 7500K inside the arc tube is selected as a light source to which the light interference filter film is applied.
Color temperatures in the range of 0 to 6000K may be realized by the color temperature lowering effect of the optical interference filter film,
Further, since the spectral transmittance characteristic of the filter film is limited within a predetermined range, it is possible to avoid a secondary effect due to heat ray reflection of the filter film.
Even with a relatively small number of layers, it is possible to efficiently realize an arbitrary reduction in color temperature in the range of 500 to 4000K.

In the second metal halide lamp of the present invention, the range characteristic is stable, and the characteristic variation among the lamps is small, so that the desired color temperature can always be obtained by applying the optical interference filter film. To be

In the third metal halide lamp of the present invention, the light interference filter film is excellent in heat resistance and can maintain initial characteristics for a long period of time.

[Brief description of drawings]

FIG. 1 is a partially cutaway schematic view of a metal halide lamp according to an embodiment of the present invention.

FIG. 2 is a diagram showing the spectral irradiance of a Dy-Nd-Cs-based metal halide lamp, the solid line shows the characteristics of the metal halide lamp of one embodiment of the present invention, and the broken line shows the optical interference filter film in the metal halide lamp. Represents the characteristics when not having.

FIG. 3 is a diagram showing the spectral irradiance of a Dy-Tl-Cs-based metal halide lamp, where the solid line represents the characteristics of a conventional metal halide lamp having an optical interference filter film, and the broken line represents the optical interference filter film in the metal halide lamp. Represents the characteristics when there is no.

FIG. 4 is a diagram showing a spectral transmittance characteristic of an optical interference filter film used in a metal halide lamp of Example I.

FIG. 5 is a diagram showing a spectral transmittance characteristic of an optical interference filter film used in the metal halide lamp of Example II.

FIG. 6 is a diagram showing a spectral transmittance characteristic of an optical interference filter film used in the metal halide lamp of Example III.

FIG. 7 is a diagram showing a spectral transmittance characteristic of an optical interference filter film used in the metal halide lamp of Example IV.

FIG. 8 is a diagram showing a spectral transmittance characteristic of an optical interference filter film exemplified for comparison.

FIG. 9 is a diagram showing an example of spectral transmittance characteristics of a single layer film.

[Explanation of symbols]

 1 arc tube 2,3 electrode 4,5 heat insulating film 6 optical interference filter film 7 quartz sleeve 8,9 lead wire 10 outer tube

[Table 2]

Claims (3)

[Claims] 1. A translucent member which comprises at least an arc tube containing a metal halide, mercury and a rare gas, and an outer tube containing the arc tube, and which surrounds the surface of the arc tube or the arc tube. In a metal halide lamp having an optical interference filter film having an action of lowering the color temperature of incident light on at least one of the surfaces, the color temperature inside the arc tube is 6000 to 7500K when the lamp is lit, and The optical interference filter film is a multilayer film having two or more layers, and the spectral transmittance curve of the film forms a valley-shaped depression having a minimum transmittance of 80% or less on the short wavelength side of the visible light region, The wavelength position of the minimum transmittance exists in a region of 500 nm or less,
And the transmittance of the film in the wavelength range of 600 to 800 nm is 70%.
A metal halide lamp having the spectral transmittance characteristics described above. 2. The metal halide lamp according to claim 1, wherein the metal halide is at least iodide of dysprosium, neodymium and cesium. 3. The optical interference filter film comprises at least Ta ₂ O ₅ —SiO ₂ and TiO ₂ —Si as constituent elements.
O _2, ZrO ₂ -SiO ₂ or Nb ₂ O ₅ according to claim 1 or 2 claim of a metal halide lamp characterized in that it comprises a combination selected from combinations of metal oxides consisting of -SiO _2.