JPH09153342A - Metal halide lamp - Google Patents

Abstract

(57) Abstract: A metal halide lamp having a small variation in color rendering properties and capable of reducing a color temperature to a desired value without coloring or dimming light. SOLUTION: DyI ₃ , NdI ₃ , CsI, mercury and argon gas are sealed inside, the color temperature of the light inside is 6500K when the lamp is on, and the end of the portion surrounding the electrodes 2, 3 on the outer surface. An arc tube 1 having heat insulating films 4 and 5 made of fine particles such as zirconium oxide coated on the surface of the part, a sleeve 7 surrounding the arc tube 1, an outer tube 1 and the sleeve 7 built-in. In a metal halide lamp 13 including a tube 12, an infrared reflection film 6 composed of a twelve-layer film of tantalum oxide and silicon dioxide is provided on the outer surface of the arc tube 1 sandwiched by the heat insulation films 4 and 5 to provide a low color temperature. Composing a metal halide lamp of.

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 having an improved color temperature of light of the lamp as an optical characteristic.

[0002]

2. Description of the Related Art A technique of providing a light interference film on the surface of a light-transmitting base material surrounding a light source and converting the color temperature of the light source by this light interference film is already known. Has been done. For example, a metal halide lamp having a high color temperature can reduce the color temperature to a desired value by applying an optical interference film (usually composed of a multilayer film) without impairing its lamp efficiency and color rendering properties. Has been realized. In this case, if a metal halide lamp is formed by forming a multilayer optical interference film on the surface of the light emitting tube or a light-transmissive cylindrical tube that is arranged so as to surround the light emitting tube, depending on the spectral transmittance characteristics of this light interference film. Since the spectral distribution of light transmitted through the light interference film changes, the color temperature decreases.

A film having a color temperature converting function such as the above-mentioned multilayer optical interference film (hereinafter referred to as "color temperature converting film").
Has a spectral transmittance characteristic that only light in a specific range of the visible light region is reflected and light in other regions is mostly transmitted. The present inventor has already proposed to apply some types of color temperature conversion films having spectral transmittance characteristics to which detailed limiting conditions are added to a metal halide lamp, but these color temperature conversion films are , And all have the common feature of reflecting only light in a narrow wavelength range of approximately 400 to 600 nm. FIG. 11 shows an example of the spectral transmittance characteristic of such a color temperature conversion film.

[0004]

However, the conventional metal halide lamp to which the color temperature conversion film is applied has the following drawbacks. That is, there are problems that the color rendering properties of the lamps tend to be uneven and uneven, the light of the lamps is easily colored, and the luminous flux of the lamps is reduced as compared with the case where the color temperature conversion film is not provided.

Next, considering these problems, it is thought that, first of all, a slight film thickness deviation at the time of forming the color temperature conversion film has a great influence on the lamp characteristics. In general, when the film thickness of each layer of the color temperature conversion film (multilayer film) becomes thicker or thinner than the target value, the spectral transmittance characteristic of the color temperature conversion film is generally right or left with respect to the wavelength axis. It fluctuates a little. On the other hand, in the metal halide lamp, a large number of emission peaks due to the metal enclosed in the arc tube exist over the entire visible range, and some of these peaks are close to each other. Therefore, a small variation in the spectral transmittance characteristic of the color temperature conversion film caused by a slight film thickness deviation causes a difference in the emission peak cut by the color temperature conversion film, and the lamp characteristics such as color temperature and color rendering properties are changed. Will have a significant effect on.

For example, in a dysprosium (Dy) -thallium (Tl) type metal halide lamp, a multilayer optical interference film having a minimum spectral transmittance in the visible region at a wavelength of 445 nm (see FIG.
When applying 11) to the surface of an arc tube to measure the color temperature drop, the main emission peaks of this lamp exist at wavelengths of 420 nm and 535 nm, so the spectral transmittance curve of the multilayer optical interference film is either left or right with respect to the wavelength axis. Even if it deviates in the direction of, the lamp characteristics will be greatly changed and the color temperature will deviate from the target value by at least about 500K.

[0007] Next, similarly to the above, the second factor is caused by a slight variation in the spectral transmittance characteristics of the color temperature conversion film. Metal halide lamps for general lighting are designed so that the color temperature coordinates of the lamp are on or near the blackbody radiation locus, and the light is not significantly colored.Also, even in lamps with a film so far, Many efforts have been made to maintain this property. However, the spectral transmittance characteristic condition of the film that keeps the chromaticity coordinates of the lamp after the color temperature conversion film near the black body radiation locus is limited to a relatively narrow range. Even if the peak wavelength of the valley is shifted by 50 nm, the light may be colored so that it can be discerned by the eye.

Regarding the above, it is an essential drawback of the conventional color temperature conversion film, and it is a natural result because the color temperature conversion film cuts off a part of visible light. The degree of dimming varies depending on the spectral transmittance characteristics of the color temperature conversion film, but in the case of the color temperature conversion film having the characteristics shown in FIG. 11, the luminous flux is reduced by about 10%. In general, increasing the color temperature conversion width tends to increase the cost of dimming.

As described above, in the conventional metal halide lamp to which the color temperature conversion film is applied, the allowable range of the film thickness variation is narrow, and thus it is difficult to strictly control the film thickness when forming the color temperature conversion film. It had the inherent drawback of cutting visible light.

The present invention has been made to solve the above-mentioned problems of the conventional metal halide lamp to which the color temperature conversion film is applied, and lowers the original high color temperature of the lamp to a desired value by applying the light interference film. In metal halide lamps, the variation in color rendering between lamps is small,
It is an object of the present invention to provide a metal halide lamp that has almost no coloring or dimming of light.

[0011]

In order to solve the above problems, the color temperature conversion film has a spectral transmittance curve
Flat or close to the entire visible light range,
It suffices that it has a characteristic that it does not have a valley-shaped depression in the visible light region. Therefore, in the present invention, a visible light transmitting infrared reflecting film (hereinafter, simply referred to as "infrared reflecting film") is used as the light interference film, and the color temperature reduction due to the heat retaining effect is utilized.

That is, the invention according to claim 1 encloses a metal halide, mercury, and a rare gas inside, and the color temperature of the light inside is 4500 to 7500 K when the lamp is lit, and the electrode on the outer surface is A metal halide lamp comprising at least an arc tube having a heat insulating film made of fine particles of a metal oxide or the like coated on an end surface of a surrounding portion, and an outer tube containing the arc tube. An infrared reflecting film is provided on the surface of a portion of the outer surface where the heat insulating film is not applied, or on at least one of the inner and outer surfaces of the translucent member arranged so as to surround the arc tube. , A multilayer optical interference film made of a metal oxide having four or more layers and transmitting substantially 85% or more of light in the wavelength range of 400 to 700 nm, and the spectral transmittance curve of the infrared reflecting film is 900 nm. At least 1 in the above wavelength range Valley-like recess is formed of,
At least one of the valley-shaped depressions is configured to have a spectral transmittance characteristic that the light transmittance has a minimum transmittance value of 50% or less.

By adopting an infrared reflection film (visible light transmission) as the color temperature conversion film, the variation in color rendering between lamps due to film thickness variation is small, and the light is sufficiently distributed over the entire visible light region. Since the transmitted light (light of the lamp) is not colored by the film and the luminous flux is not reduced, a metal halide lamp having a lowered color temperature can be realized.

According to a second aspect of the present invention, in the metal halide lamp according to the first aspect, the metal halide is at least iodide of dysprosium (Dy), neodymium (Nd) and cesium (Cs), The color temperature of the light inside the arc tube is 6000 to 7500 when the lamp is lit.
K, the color temperature of the lamp can be selected from any value in the range of 3000 to 6000K, and the average color rendering index (Ra) of the lamp is 92 or more.

As described above, by selecting the metal halide in the arc tube, which is composed of each iodide of Dy, Nd and Cs, it is possible to obtain a highly efficient lamp having a small variation in characteristics among the lamps based on the arc tube. In addition, since the infrared reflection film is composed of a multilayer optical interference film having a predetermined spectral transmittance characteristic and the Ra of the lamp is set to 92 or more, the infrared reflection film can be provided in a wide range of 3000 to 6000K. It is possible to realize a metal halide lamp having a color temperature and a high color rendering property.

According to a third aspect of the present invention, in the metal halide lamp according to the first aspect, the metal halide is at least iodide of dysprosium (Dy), thallium (Tl) and cesium (Cs), The color temperature of the light inside the arc tube is 4500-6000 when the lamp is on.
K, the color temperature of the lamp can be selected from any value in the range of 3000 to 5000K, and the average color rendering index (Ra) of the lamp is 92 or more.

As described above, as the metal halide in the arc tube, Dy, Tl and Cs which give a color temperature relatively close to the color temperature range of 3000 to 4000K which has been increasing in demand in recent years.
By selecting the iodide of the above, the width of the color temperature decrease due to the infrared reflection film can be small, and therefore the film configuration of the infrared reflection film can be simplified, and the infrared reflection film can be made to have a predetermined spectral distribution. Since the lamp is composed of a multi-layered optical interference film having transmittance characteristics and the Ra of the lamp is 92 or more, it is possible to realize a metal halide lamp having a desired color temperature in the range of 3000 to 5000K and a high color rendering property. it can.

According to a fourth aspect of the present invention, in the metal halide lamp according to any one of the first to third aspects, the infrared reflecting film is Ta ₂ O ₅ --SiO ₂ , TiO ₂ --Si.
One of a total of eight combinations of O ₂ , ZrO ₂ —SiO ₂ or Nb ₂ O ₅ —SiO ₂ film substance combinations, and combinations of the film substances in which Al ₂ O ₃ is added to each of these combinations. Seed or 2
It consists of more than one species. By thus forming the infrared reflecting film with the above metal oxide, it is possible to obtain an infrared reflecting film having excellent heat resistance and capable of maintaining initial characteristics for a long period of time.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described. FIG. 1 is a partially cutaway schematic view of a first embodiment of a metal halide lamp according to the present invention. In the figure,
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. Further, heat insulating films 4 and 5 made of fine particles such as zirconium oxide (ZrO ₂ ) are formed on the outer surfaces of both ends of the arc tube 1. An infrared reflecting 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 so as to surround the arc tube 1 in order to prevent scattering of fragments of the arc tube. Numerals 8 and 9 are arc tube supports which also serve as lead wires, and are connected to the outer tube 12 via fixing metal fittings 10 and 11.
The arc tube 1 is supported inside, and a metal halide lamp 13 with a rated power of 150 W is constructed.

The infrared reflection film 6 is composed of a 12-layer film,
The film structure has the structure shown in [Table 1]. The odd-numbered high refractive index layers are formed of, for example, tantalum oxide (Ta ₂ O ₅ ), and the even-numbered low refractive index layers are formed of, for example, silicon dioxide. It is formed by (SiO _2). Further, the film formation of each layer of the infrared reflective film 6 having the above-mentioned configuration is formed by using a known method, for example, a low pressure CVD method. In the layer numbers in [Table 1], S indicates the arc tube, and O indicates the air inside the outer tube in contact with the outermost layer of the infrared reflection film 6.

[0021]

[Table 1]

Next, second to fifth embodiments will be described. The metal halide lamps of the second to fifth embodiments have the same structure as that of the first embodiment except the structure of the infrared reflection film provided on the outer surface of the arc tube. The infrared reflective film in each of the second to fifth embodiments is composed of an 18-layer film, a 6-layer film, an 8-layer film and a 10-layer film, respectively, and the film configurations are [Table 2] and [Table 3], respectively. ],
The high refractive index layer is formed of, for example, tantalum oxide (Ta ₂ O ₅ ), and the low refractive index layer is formed of, for example, silicon dioxide (SiO ₂ ) having the configurations shown in [Table 4] and [Table 5]. It is formed and is formed by a known method similarly to the first embodiment.

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

[0026]

[Table 5]

Next, the lamp characteristics in each embodiment will be described. First, the color temperature conversion effect of the infrared reflective film will be described. The color temperature conversion effect was evaluated as follows. First, except that the infrared reflection film is not formed on the outer surface of the arc tube, a metal halide lamp having the same structure as that of each of the above-described embodiments is produced, and the color temperature and the spectrum of the metal halide lamp without the infrared reflection film are measured. Lamp characteristics such as irradiance were measured. next,
The outer tube of the lamp is destroyed to remove only the arc tube, and the outer surface of the arc tube is subjected to the above-mentioned first to fifth steps by a known method.
After forming an infrared reflection film having a film structure corresponding to each of the above embodiments, the infrared reflection film is arranged again in the outer tube to assemble the lamp.
~ The metal halide lamp of each of the fifth embodiments is completed, the lamp characteristics such as the color temperature and the spectral irradiance of the metal halide lamp in the state of having the infrared reflection film are measured, and the lamp characteristics of both are compared and evaluated. It was

The color temperature of each of the metal halide lamps of the first to fifth embodiments at the rated lighting, the color temperature change as compared with those without an infrared reflection film, the average color rendering index (Ra), and the total luminous flux. , And the color temperature coordinates are shown in [Table 6]. In the case where the infrared reflection film is not provided, the color temperature of the lamp corresponding to the first to fifth embodiments is 6460 to 6530K, the average color rendering index (Ra) is 95, and the total luminous flux is 11500 to.
12000lm, color temperature coordinate is x = 0.132 to 0.313, y = 0.33
It is 0 to 0.333.

[0029]

[Table 6]

Next, the spectral irradiance characteristic measured for the metal halide lamp of the first embodiment is shown by the solid line in FIG. For comparison, the broken line shows the spectral irradiance characteristic of the metal halide lamp corresponding to the first embodiment in which the infrared reflecting film is not provided.

As can be seen from FIG. 2, in the case of the metal halide lamp of the first embodiment having the infrared reflecting film,
The irradiance in the visible region from 400 to 700 nm is generally only slightly higher than that of the lamp without the film. On the other hand, the irradiance increases considerably on the long wavelength side above 700 nm. Further, the color temperature of the metal halide lamp of the first embodiment is 4310K when the lamp is rated lighting.
Which is 2150K lower than when the infrared reflection film is not provided. On the other hand, Ra of this metal halide lamp is 94.
There is almost no change from the case where no film is provided, but the total luminous flux is 1
At 2800 lm, it increased by a little less than 10% compared to the case without the film, and the color temperature coordinate was also present near the black body radiation locus (see Table 6).

Next, the spectral transmittance characteristics of the infrared reflecting film applied to the metal halide lamp will be described. This characteristic was measured as follows. That is, when an infrared reflecting film is formed on the outer surface of an arc tube, at the same time, the same infrared reflecting film is formed on the outer surface of another arc tube having the same specifications, and the fragments obtained by destroying the arc tube. The spectral transmittance of the infrared reflective film on the surface of the was measured.

As a result of the above measurement, the infrared reflection film (12-layer film) in the metal halide lamp of the first embodiment had the spectral transmittance characteristics shown in FIG. As can be seen from FIG. 3, in the spectral transmittance curve of the infrared reflective film of the first embodiment, the transmittance in the visible light region of 400 to 700 nm is substantially 85% or more, and the wavelength region of 900 nm or more. Has two or more valley-shaped depressions in the
The largest of these is located near 1100 nm, and the minimum transmittance for that is about 10%.

Next, the spectral transmittance characteristics of the infrared reflecting film in the metal halide lamp of the second embodiment will be described. The infrared reflective film in this embodiment has an 18-layer film structure as shown in [Table 2], and its spectral transmittance characteristics are as shown in FIG. The lamp characteristics of the second embodiment are as follows:
The color temperature is 6150K, Ra is 95, and the total luminous flux is 11700lm. However, as shown in [Table 6] in the second embodiment, the color temperature is 3520K, Ra is 93, and the total luminous flux is 13300lm. It can be seen that the infrared reflection film causes a color temperature reduction of about 3000K. A high Ra value is maintained regardless of the presence or absence of an infrared reflective film, and the color temperature coordinate is also present near the black body locus.

Further, the spectral transmittance characteristics of the infrared reflecting film of the metal halide lamps of the third to fifth embodiments are as shown in FIGS. 5, 6 and 7, respectively.

In the metal halide lamp of each of the above-mentioned embodiments, the infrared reflective film has a film structure of 12 layers, 18 layers, 6 layers, and 8 layers.
Although the number of layers and the number of layers are shown as 10 layers, the film constitution of the infrared reflective film in the present invention is not limited to these.
The same effect can be obtained as long as the film has more than one layer. Regarding the relationship between the number of layers of the infrared reflection film and the size of the color temperature decrease, the width of the color temperature decrease tends to increase as the number of layers increases. This is due to the fact that the lamp characteristics of each embodiment shown in [Table 6] represent that fact, and the color temperature which was around 6500 K when the infrared reflecting film was not provided was increased by the number of layers of the infrared reflecting film. At the same time, the color temperature drop is large in the range of 700 to 3000K.

In the present invention, regarding the spectral transmittance characteristics of the infrared reflecting film, “a light in the wavelength region of 400 to 700 nm is substantially transmitted by 85% or more, and the spectral transmittance curve of the film is in the wavelength region of 900 nm or more. Forming at least one valley-shaped depression,
At least one of the valley-shaped depressions must have the condition that the light transmittance has a minimum transmittance value of 50% or less. ”Next, this point will be described. Regarding this condition, conversely, when the spectral transmittance characteristics of the infrared reflecting film do not satisfy the above conditions, the desired reduction in color temperature of 500 to 3000K is achieved depending on the infrared reflecting film. It will be described based on the following comparative example that not only the above-mentioned problem but also the color rendering of the lamp and the total luminous flux will be reduced.

The metal halide lamps of Comparative Examples 1, 2 and 3 described below are the same as those of the first to third embodiments except for the structure of the reflection film.
It has the same configuration as that of the fifth embodiment. Comparative Examples 1 to
The spectral transmittance characteristics of the infrared reflective film applied to No. 3 are
It has the characteristics shown in FIGS. 8, 9 and 10, respectively. That is, as shown in FIG. 8, the infrared reflective film of Comparative Example 1 had a transmittance of 85 in the wavelength region of 400 to 700 nm.
%, But the main valley-shaped depression of the spectral transmittance curve exists at 700 to 900 nm, and the valley-shaped depressions that exist in the wavelength region of 900 nm and above are small in size and the depth of the depression is large. Is insufficient, and it has the characteristic that valley-shaped depressions with a minimum transmittance of 50% or less do not exist in the wavelength region of 900 nm or more. In the infrared reflective film of Comparative Example 2, as shown in FIG. 9, the main valley-shaped depression of the spectral transmittance curve exists in the wavelength region of 900 nm or more, but the minimum transmittance of the depression is 50% or less. It has the characteristic that it does not exist. In the infrared reflective film of Comparative Example 3, as shown in FIG. 10, there are valley-shaped depressions of the spectral transmittance curve where the minimum transmittance is 50% or less in the wavelength region of 900 nm or more.
It has a large ripple in the range of 00 to 700 nm and an average transmittance of less than 80% in this wavelength range.

As a result of measuring the lamp characteristics of the metal halide lamps of Comparative Examples 1 to 3 provided with the infrared reflecting film having such a spectral transmittance characteristic, in Comparative Examples 1 and 2, the range of color temperature decrease was less than 500K. It was found that the color rendering property was not sufficient, and in Comparative Example 3, the light of the lamp was somewhat colored, and Ra was less than 85.

From these facts, the spectral transmittance curve of the infrared reflecting film has a valley-shaped depression having a depth such that the minimum value is 50% or less in the wavelength region of 900 nm or more.
It has been found that it causes a decrease in color temperature of a predetermined size, that is, 500 K or more.

The infrared reflecting film applied in the present invention is
The function of controlling the color temperature of the lamp is provided merely by the effect of keeping the arc tube warm by the infrared reflection of the infrared reflecting film. Further, by applying the infrared reflection film in the present invention, light in the visible light region is almost completely transmitted over the entire region, so that there is no variation in color rendering between lamps due to film thickness variation, and the lamp Light is not colored by the infrared reflection film,
The advantage is that the original light color is preserved. Furthermore, when trying to realize the same low color temperature of 4000 K or less as to the color temperature of the lamp, when a conventional visible light selective transmission film is applied, the film can be provided to reduce the total luminous flux by a maximum of 10 to 20%. On the other hand, when the infrared reflection film is applied in the present invention, the total luminous flux is not decreased but rather increased, and there is an advantage that an increase of up to 10% or more can be expected.

Under the above conditions, "400-700 nm
The requirement of "transmit substantially 85% or more of light in the wavelength region of" is that even if there is a portion where the spectral transmittance curve locally falls below 85% due to ripple etc. in this wavelength region, This means that there is no portion having an extremely low transmittance of less than about 80% and the average transmittance of this region is 85% or more.

In the infrared reflecting film, if the film structure is complicated by making it to have a plurality of optical axes, a local ripple may occur in the visible light region, and the light transmittance of this region may be increased. Since the decrease cannot be ignored, it is preferable to make the film structure as simple as possible.

In the first to fifth embodiments described above,
In the present invention, the infrared reflection film is formed on the outer surface of the arc tube of the metal halide lamp, but in the present invention, the infrared reflection film is formed on the outer surface of the outer tube of the lamp or the arc tube. Of course, it may be the surface of the surrounding translucent member.

[0045] In the above embodiments, as the inclusion metal halide into the light emitting tube, DyI ₃ -NDI ₃
-CsI combination was used, and the one for the arc tube in which the color temperature of light of the arc tube when the lamp is turned on is 6000 to 7500K is shown, but as the metal halide, DyI _3-
Enclosed with a combination of TlI-CsI and a color temperature of 4500-60
The infrared reflecting film may be applied by using an arc tube having a value of 00K. Further, as long as it has stable lamp characteristics and exhibits a desired color temperature, an arc tube in which another combination of metal halides is enclosed may be used. Preferred examples of inclusion metal halide arc tube color temperature is 6000～7500K, otherwise, there is a combination of DyI ₃ -NdI ₃ -GaI _3, preferred examples of the 4500~6000K are other , DyI ₃ -TlI-InI _{3 and} the like.

Further, in each of the above embodiments, Ta ₂ is used as the film material of the high refractive index layer constituting the infrared reflecting film.
Although O ₅ is used as the material of the high refractive index layer, titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ) or niobium oxide (Nb ₂ O ₅ ) may be used instead. Well, therefore, the film constitution of the infrared reflecting film is Ta ₂ O
_{5 -SiO 2, TiO 2 -SiO 2} , ZrO 2 -SiO 2 and Nb ₂
An appropriate one may be selected from the combination of O ₅ —SiO ₂ film materials. Alternatively, when the film structure includes the intermediate refractive index layer, Ta ₂ O ₅ —SiO ₂ —Al ₂ O ₃ and TiO _{2 are used.
-SiO 2 -Al 2 O 3, ZrO} 2 -SiO 2 -Al 2 O 3 and Nb
_An appropriate one may be selected from the combination of film materials of ₂ O ₅ —SiO ₂ —Al ₂ O ₃ .

In the present invention, the constituent requirements of the metal halide lamp (type of constituent member, size, shape, rated power of lamp, presence / absence of heat insulating film, etc.) are not limited to those in each of the above embodiments. Needless to say.

[0048]

As described above based on the embodiments, according to the invention described in claim 1, the metal halide lamp provided with the arc tube whose internal color temperature becomes 4500 to 7500K when the lamp is lit is predetermined. Since the infrared reflective film having the spectral transmittance characteristic of 1 is applied, it is possible to easily reduce the color temperature of any size in the range of 500 to 3000K without reducing the lamp efficiency, the color rendering property and the luminous flux due to the reflective film. Can be realized, 3000
It is possible to easily provide a metal halide lamp having a color temperature in the range of up to 6000K. Furthermore, even if the film thickness varies during the formation of the infrared reflection film, it does not cause a large variation in the color rendering properties between the lamps due to this, and since the infrared reflection film is used, the film is rather provided. There is also an additional effect that the total luminous flux is increased to some extent as compared with the case where it is not present.

According to the second aspect of the present invention, a metal halide lamp in which the metal halide enclosed in the arc tube is DyI ₃ -NdI ₃ -CsI and the color temperature in the arc tube is 6000 to 7500K, a predetermined spectral transmittance is obtained. Since the infrared reflective film having characteristics is applied, it is possible to provide a metal halide lamp having high color rendering properties over a wide range of color temperatures of 3000 to 6000K. According to the third aspect of the invention, an infrared ray having a predetermined spectral transmittance characteristic is applied to a metal halide lamp in which the metal halide enclosed in the arc tube is DyI ₃ -TlI-CsI and the color temperature in the arc tube is 4500 to 6000K. Since the reflective film is applied, it is possible to provide a metal halide lamp having a high color rendering property with respect to a color temperature in the range of 3000 to 4000 K, which has been in great demand in recent years. Further, according to the invention of claim 4, by limiting the combination of the film substances constituting the infrared reflecting film to be applied to a predetermined combination, the infrared reflecting having excellent heat resistance and capable of maintaining initial characteristics for a long period of time. A metal halide lamp equipped with a membrane can be realized.

[Brief description of the drawings]

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

FIG. 2 is a spectral irradiance according to the first embodiment of the present invention,
It is a figure which shows the spectral irradiance of the metal halide lamp which has not formed the infrared reflective film on the outer surface of an arc tube.

FIG. 3 is a diagram showing a spectral transmittance characteristic of an infrared reflecting film applied to the metal halide lamp according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a spectral transmittance characteristic of an infrared reflecting film applied to a metal halide lamp according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a spectral transmittance characteristic of an infrared reflecting film applied to a metal halide lamp according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a spectral transmittance characteristic of an infrared reflecting film applied to a metal halide lamp according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a spectral transmittance characteristic of an infrared reflecting film applied to a metal halide lamp according to a fifth embodiment of the present invention.

8 is a diagram showing a spectral transmittance characteristic of an infrared reflective film applied to the metal halide lamp of Comparative Example 1. FIG.

9 is a diagram showing a spectral transmittance characteristic of an infrared reflective film applied to a metal halide lamp of Comparative Example 2. FIG.

FIG. 10 is a diagram showing a spectral transmittance characteristic of an infrared reflective film applied to a metal halide lamp of Comparative Example 3.

FIG. 11 is a diagram showing an example of spectral transmittance characteristics of a conventional color temperature conversion film.

[Explanation of symbols]

 1 arc tube 2,3 electrode 3,4 heat insulation film 6 infrared reflection film 7 sleeve 8,9 lead wire 10,11 fixing metal fitting 12 outer tube 13 metal halide lamp

Claims (4)

[Claims] 1. A metal halide, mercury, and a rare gas are sealed inside, and the color temperature of the light inside is 4500 when the lamp is on.
7500K, which comprises at least an arc tube in which a heat insulating film made of fine particles of metal oxide or the like is attached to the end surface of the portion surrounding the electrode on the outer surface, and an outer tube containing the arc tube. In the metal halide lamp, the infrared rays are applied to the surface of the outer surface of the arc tube where the heat insulating film is not applied, or at least one of the inner and outer surfaces of the translucent member arranged so as to surround the arc tube. A reflection film is provided, and the infrared reflection film is composed of a multilayer optical interference film made of a metal oxide having four or more layers, and transmits substantially 85% or more of light in the wavelength region of 400 to 700 nm, The spectral transmittance curve of the infrared reflective film forms at least one valley-shaped depression in the wavelength region of 900 nm or more, and at least one of the valley-shaped depressions has a minimum transmittance of 50% or less. Has the spectral transmittance characteristic of having Metal halide lamp, wherein the door. 2. The metal halide is composed of at least each of iodides of dysprosium, neodymium, and cesium, and the color temperature of light inside the arc tube when the lamp is turned on.
6000-7500K, and the color temperature as a lamp is 3000
2. The metal halide lamp according to claim 1, wherein any value in the range of up to 6000 K can be selected, and the average color rendering index (Ra) of the lamp is 92 or more. 3. The metal halide comprises at least dysprosium, thallium and cesium iodides, and the color temperature of the light inside the arc tube is 45 when the lamp is on.
00-6000K, and the color temperature of the lamp is 3000-
2. The metal halide lamp according to claim 1, wherein any value in the range of 5000K can be selected, and the average color rendering index (Ra) of the lamp is 92 or more. 4. The infrared reflective film is made of Ta ₂ O ₅ —Si.
_{O 2, TiO 2 -SiO 2,} ZrO 2 -SiO 2 or Nb ₂ O ₅ -
Combinations of SiO ₂ film materials and Al ₂
The metal halide lamp according to any one of claims 1 to 3, wherein the metal halide lamp is composed of one kind or two or more kinds out of a total of eight kinds of combination of film substances to which O ₃ is added. .