JP3241611B2 - Metal halide lamp - Google Patents

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 used as a light source for a liquid crystal projector or the like.

[0002]

2. Description of the Related Art As means for enlarging and projecting images such as characters and figures, liquid crystal projectors and the like have recently been known. Since such an image projection device requires a predetermined light output, a metal halide lamp having high luminous efficiency is generally widely used as a light source.
This type of metal halide lamp is used as a metal halide sealed in an arc tube, for example, as disclosed in JP-A-3-21.
Neodymium (N
It was common to use iodides of d), dysprosium (Dy) and cesium (Cs).

[0003]

SUMMARY OF THE INVENTION Incidentally, this Japanese Patent Laid-Open No.
Neodymium (N
d), a lamp in which iodide of dysprosium (Dy) and cesium (Cs) is sealed (hereinafter referred to as a Dy-Nd-Cs-I type lamp) has excellent luminous efficiency, but in particular neodymium iodide (NdI ₃ ) And the quartz glass of the arc tube are strongly reactive, so that devitrification of the arc tube occurs early in the life. Such devitrification lowers the luminous flux, lowers the luminance, and diffuses the light, causing uneven illuminance and lowering the brightness on the screen of the liquid crystal projector. That is, Dy-Nd-
When a Cs-I lamp is used as a light source for a liquid crystal projector, there is a disadvantage that the life is short.

[0004] From the viewpoint of energy saving in recent years, Dy
A light source having a higher luminous efficiency than the -Nd-Cs-I type lamp is desired. Regarding this point, for example, in 1982, Journal of the Illuminating Engineering Institute (Vol. 65) No. 10, page 17, “Emission Characteristics of Metal Halide Lamps Containing Rare Earth Halides”, rare earth halides and halides of thallium (Tl) and indium (In) are described. By combining
It is disclosed that a light source having high luminous efficiency can be obtained. However, the low correlated color temperature of the disclosed light source is
It is not suitable for use as a light source for a liquid crystal projector or the like. One example of the disclosed light source is a metal halide lamp (hereinafter referred to as an In-Tm-I lamp) in which indium iodide (InI) and thulium iodide (TmI ₃ ) are enclosed. The expected correlated color temperature is about 4500K. On the other hand, the white standard of an image projection device such as a liquid crystal projector device is about 900.
0K.

In view of the above-mentioned problems of the conventional metal halide lamp, the present invention has an emission spectrum that is distributed over the entire visible region, and is different from the conventional Dy-Nd-Cs-I lamp and the In-Tm-I lamp. An object of the present invention is to provide a metal halide lamp having excellent efficiency, an appropriate color temperature, and a long life.

[0006]

The present invention SUMMARY OF] includes a starting rare gas into transparent envelope, and halide Lee indium (In), terbium (Tb), dysprosium (Dy), holmium (Ho), Erbium (Er), thulium (T
In metal halide lamps sealed entering at least one of halides m), the metal halide lamp
Has a set of electrodes, to which alternating current is applied
The metal halide lamp is supplied and driven, and the indium (In) halide is sealed at 0.1 mg / cc to 1.5 mg / cc.

[0007]

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

A problem with the conventional Dy-Nd-Cs-I lamp is that, first of all, since the reactivity between neodymium (Nd) and the quartz glass of the arc tube is strong, the devitrification of the arc tube shortens its life. Is to happen. Therefore, the problem can be solved by configuring the lamp enclosure with a substance having a lower devitrification (reactivity with quartz glass) than neodymium iodide (NdI ₃ ). From such a concept, first, the devitrification (reactivity with quartz glass) of various metal halides was examined by the following devitrification evaluation test. The devitrification evaluation test was conducted by placing an ampoule containing 10 mg of metal halide in a 5 cc tube made of quartz glass at 1100 ° C.
After heating for 00 hours, measure the total transmittance of the ampoule tube,
This is to evaluate the devitrification of the metal halide. Table 1 shows the ratio (%) of the total transmittance after heating (after the test) to the total transmittance of the ampoule tube measured before heating.
Shown in The larger the value, the weaker the devitrification. In addition, the blank part in (Table 1) means unevaluated.

[0009]

[Table 1] As shown in Table 1, terbium iodide (Tb
I _3), dysprosium iodide (DyI _3), iodide holmium (HoI _3), iodide erbium (ERI _3), iodide thulium (TmI _3), indium iodide (In
I) and tin iodide (SnI ₂ ), dysprosium bromide (DyBr ₃ ), thulium bromide (TmBr ₃ ), indium bromide (InBr) and tin bromide (SnBr ₂ ). All the transmittances exceeded the total transmittance of the ampoule tube in which neodymium (Nd) iodide was sealed, and showed weak devitrification.

Therefore, these weakly devitrifying substances are variously
Various characteristics were investigated in combination. As a result, as described below, indium (In) halides include terbium (Tb), or dysprosium (Dy), or holmium (Ho), or erbium (Er), or thulium (Tm) halides. It has been found that by adding these mixtures, excellent characteristics can be obtained in both lifetime and luminous efficiency. (Embodiment 1) FIG. 1 is a view showing a first embodiment of a metal halide lamp according to the present invention. In FIG. 1, reference numeral 1 denotes an arc tube made of quartz, which is a light-transmitting container, and sealing portions 6a and 6b are formed at both ends. Sealing portion 6a,
6b each has a metal foil conductor 3a made of molybdenum;
The metal foil conductors 3a and 3b are electrically connected to electrodes 2a and 2b and external lead wires 4a and 4b made of molybdenum, respectively.

The electrodes 2a and 2b are made of tungsten rods 7a and 7
b and tungsten coils 8a and 8b. The coils 8a and 8b are each a tungsten rod 7
The electrodes 2a and 2b are electrically fixed to the tips of the electrodes 2a and 2b by welding and serve as radiators for the electrodes 2a and 2b. The electrodes 2a and 2b are opposed to each other inside the arc tube 1 so that the distance between the electrodes 2a and 2b is 3.5 ± 0.5 mm.

The arc tube 1 has a substantially spherical shape and an inner diameter of about 1 at the center.
0.8mm, inner volume is about 0.7cc, inner surface area is about 3.6
cm ² , 0.4 mg (0.57 mg / c) of indium iodide (indium iodide InI) as an enclosure.
c), holmium iodide (HoI) as a rare earth iodide
₃ ) 1 mg (1.43 mg / cc), 35 mg of mercury as a buffer gas, and 200 of argon as a starting rare gas.
mbar enclosed. Electric power is supplied from the external lead wires 4a and 4b to the metal halide lamp having the above configuration, and the rated lamp power is 200W (tube wall load 55W / cm).
^The light was turned on in ² ) to evaluate the light emission characteristics.

FIG. 2 is a diagram showing a spectral distribution of the metal halide lamp according to the present embodiment. In this case, the correlated color temperature is about 5500 K, and the luminous efficiency is about 87 lm / W. Abundant light emission can be seen throughout the visible range. In particular, there is much light emission in the red region.

For comparison, indium iodide (InI)
And holmium iodide (HoI ₃ ), dysprosium iodide (DyI ₃ ) and neodymium iodide (Nd)
I ₃₎ with each and 1mg sealed cesium iodide (CsI), a lamp other configuration is the same as the metal halide lamp shown in FIG. 1 of the present embodiment (hereinafter Dy-Nd-C
The luminous efficiency at the time of rated lighting of the s-I lamp is 77 l.
m / W. It can be seen that the metal halide lamp of the present embodiment has excellent luminous efficiency.

Next, various lamps were manufactured in which the amount of indium iodide (InI) and the amount of holmium iodide (HoI ₃ ) were different and the other structures were the same as the metal halide lamp shown in FIG. 1 of the present embodiment. The light emission characteristics of these lamps at the time of rated operation were examined, and indium iodide (InI)
The basic characteristics of a lamp in which holmium iodide (HoI ₃ ) was encapsulated were examined. The results will be described with reference to FIGS. 3, 4, and 5.

FIG. 3 shows the amount of holmium iodide (HoI ₃ ) as a parameter, the amount of indium iodide (InI) per unit volume (1 cc) (mg) (horizontal axis), and the correlated color temperature ( K) (vertical axis). The three marks ●, ○, and □ in the figure indicate that the amount of holmium iodide (HoI ₃ ) was 0.5, respectively.
7, 1.43, and 2.86 mg / cc lamps are shown.

From FIG. 3, the correlated color temperature is represented by curve 3A in the figure.
As shown in the graph, it can be seen that the intensity strongly depends on the amount of indium iodide (InI) encapsulated. In contrast, the effect of the amount of holmium iodide (HoI ₃ ) on the correlated color temperature is relatively small. This is because indium iodide (InI) generally performs an unsaturated operation, and holmium iodide (HoI ₃ ) generally performs a saturated operation.

The correlated color temperature required for the light source varies depending on the purpose of use, but when it is used as a light source for a liquid crystal projector or the like, it is preferably at least about 4500K or more. If it is lower than this, the white chromaticity on the screen tends to be yellowish, which is not preferable. Ideally, it is ideally close to about 9000K, which is adopted by many liquid crystal projectors as a white standard. In the metal halide lamp of the present embodiment, the preferable amount of indium iodide corresponding to the demand for such relatively high various correlated color temperatures is from 0.1 mg / cc to 1.5 mg / cc from the results shown in FIG.
mg / cc.

The preferable range of the amount of indium iodide charged corresponding to the demand for the relatively high and various correlated color temperatures is that another lamp having a tube wall load different from the tube wall load of the lamp of the present embodiment is used. This is also true from the following description.

A lamp having a different amount of indium indium iodide InI and having the same other structure as the metal halide lamp shown in FIG. 1 of this embodiment was operated with various lamp powers, and the correlated color temperature was measured. The result is shown in FIG. In FIG. 14, curves 14A, 14B, and 14C respectively represent lamp power of 175 W (tube wall load of about 48 W / c).
m ² ), 200 W (tube wall load about 55 W / cm ² ), 225
The graph shows the relationship between the amount of indium iodide InI charged and the correlated color temperature in the case of W (tube wall load of about 62 W / cm ² ). From these results, it was found that even for different tube wall loads, 0.1
It can be seen that a preferable correlated color temperature of about 4500 K to 9000 K can be obtained at an indium iodide loading of mg / cc to 1.5 mg / cc. However, the higher the tube wall load, the lower the correlated color temperature tends to be. When the amount of indium iodide is 0.57 mg / cc, the correlated color temperature at a tube wall load of 55 W / cm ² is about 6800.
K, the correlated color temperature at a tube wall load of 62 W / cm ² is about 5800K. However, this decrease in color temperature tends to decrease as the amount of indium iodide InI encapsulated increases. About 1.5m of indium iodide
g / cc, the tube wall load is 55 W / cm ² to 62 W /
The rate of change of the correlated color temperature with respect to the increase to cm ² is less than 5%, which is negligible. This fact indicates that the amount of indium iodide charged was 1.5 mg /
It is shown that the correlated color temperature of about 4500 K or more can be obtained by setting the value to cc or less.

Next, the metal halide lamp of this embodiment was used as a light source of the optical system shown in FIG. 4, and the illuminance maintenance rate of the screen 13 with respect to the lighting time was evaluated. Here, in FIG. 4, reference numeral 10 denotes a light source, 11 denotes a condenser mirror that reflects and condenses light emitted from the light source 10, and 12 denotes a condenser mirror 1.
1 is a projection lens system that projects the light condensed at 1 on the screen 13. The result is shown in FIG. 5 (curve 5A). In FIG. 5, the horizontal axis is the lighting time, and the vertical axis is 1 on the screen 13.
It is the maintenance rate of the average illuminance of three places. Dy-
The results for the Nd-Cs-I lamp are also appended (curve 5B).
From these results, it is clear that indium iodide (In
I) and holmium iodide (HoI ₃ ) metal halide lamp is a conventional neodymium iodide (NdI ₃ ).
A new fact has been revealed that the lamp has a longer life than the lamp that encapsulates the lamp. This result also supports the results of the devitrification evaluation test shown in Table 1 above. (Embodiment 2) Then, 1 mg (1.4 ml) of thulium iodide (TmI ₃ ) instead of holmium iodide (HoI ₃ ).
3 mg / cc), and the other configuration is the same as the metal halide lamp shown in FIG. 1 of the first embodiment.

FIG. 6 is a diagram showing the spectral distribution of the metal halide lamp of the present embodiment. In this case, the correlated color temperature is about 6400 K, and the luminous efficiency is about 94 lm / W.

A feature of the lamp in which holmium iodide (HoI ₃ ) is replaced with thulium iodide (TmI ₃ ) is that it has a higher luminous efficiency than that shown in this embodiment.
On the other hand, light emission in the red region is slightly less.

The correlated color temperature is equivalent to that of a lamp containing holmium iodide (HoI ₃ ). When the correlated color temperature of the lamp of the present embodiment is plotted on the graph of FIG. 3, it fits a curve 3A that relates the amount of indium iodide (InI) to the correlated color temperature. Therefore, the preferred amount of indium iodide sealed in the lamp of this embodiment in which holmium iodide (HoI ₃ ) is replaced by thulium iodide (TmI ₃ ) (which is a conventional In-T
A relatively high correlated color temperature not obtained by the m-I lamp can be obtained), as in the first embodiment, from 0.1 mg / cc to 1.
5 mg / cc. The lamp of the present embodiment also
It has the feature of long life. FIG. 7 is a diagram showing a change in the maintenance rate of the average illuminance of the screen 13 with respect to the lighting time when the lamp of the present embodiment is used as the light source of the optical system shown in FIG. 4 as in FIG. (Curve 7
A). Thulium iodide (TmI)
_The lamps with ₃ ) of 2 mg (2.86 mg / cc) and the conventional Dy-Nd-Cs-I lamp are also shown (curves 7B and 7C, respectively). With the conventional Dy-Nd-Cs-I lamp, the average illuminance of the screen is reduced to 50% of the initial value after lighting for about 1400 hours.
The lamp according to the present embodiment has an initial 60% even after 2000 hours.
To maintain. However, as shown by the curve 7B, there is a new discovery that the life is deteriorated when the amount of thulium iodide (TmI ₃ ) is increased. This tendency is the same for the lamp in which holmium iodide (HoI ₃ ) described in the first embodiment is sealed. Therefore, the smaller the amount of thulium iodide (TmI ₃ ) is, the better the life is. The lower limit is an amount sufficient to evaporate (thulium iodide (TmI
₃ ) and holmium iodide (HoI ₃ ) have a low vapor pressure, so that the whole amount enclosed does not evaporate.) As in a general metal halide lamp, the coldest point temperature of the lamp of the present embodiment is about 1000 K. For example, the saturated vapor pressure of TmI ₃ at this temperature is about 4 × 10 ⁻⁵ atm.
Thus, the amount of TmI ₃ evaporating in a 0.7 cc volume lamp can be easily determined from the equation of state of the gas, which is about 0.0001 mg. However, such a trace amount cannot be weighed in practice. 0.01 mg is a practical lower limit. The upper limit is 2 mg from the results in FIG.
(= About 3 mg / cc) is the limit. This preferable range of the filling amount also applies to the lamp filled with holmium iodide (HoI ₃ ) described in the first embodiment for the same reason.

It should be noted that the difference in the amount of thulium iodide (TmI ₃ ) or holmium iodide (HoI ₃ ) has little effect on luminous efficiency because they perform a saturation operation. FIG. 8 shows thulium iodide (Tm) of this embodiment.
The I ₃₎ in the lamp is replaced with iodide holmium (HoI _3), a diagram showing the relationship between added amount and luminous efficiency of the iodide holmium (HoI _3). Iodide terbium (TBI ₃₎ in place of (Embodiment 3) Next iodide holmium (HoI ₃₎ 1 mg (1.
43 mg / cc), and the other configuration is the same as that of the first embodiment.
A lamp which is the same as the metal halide lamp shown in FIG. 1 will be described.

FIG. 9 is a diagram showing the spectral distribution of the metal halide lamp of the present embodiment. In this case, the correlated color temperature is about 7,000 K, and the luminous efficiency is about 82 lm / W.

A feature of the lamp in which holmium iodide (HoI ₃ ) is replaced by terbium iodide (TmI ₃ ) is a higher correlated color temperature than the present embodiment shows. Light emission at a wavelength around 500 nm, which is more abundant than in the red region, contributes to this.

In the lamp of the present embodiment, the amount of indium iodide InI charged is 0.6 mg (0.86 m
g / cc) and another lamp with a terbium iodide (TbI ₃ ) loading of 2 mg (2.86 mg / cc):
Correlated color temperature is about 6300K, luminous efficiency is about 80lm / W
It is.

In the lamp according to the present embodiment, a preferable amount of indium iodide is 0.1 mg / cc to 1.5 mg / cc as in the lamp described in the first embodiment.

From the results of the devitrification evaluation test (Table 1) and the results of the first and second embodiments, the lamp in which terbium iodide (TbI ₃ ) shown in the present embodiment is sealed also has an excellent life. Of course. (Embodiment 4) Next, indium iodide InI is added to 0.6.
mg (0.86 mg / cc), holmium iodide (Ho
2 mg of erbium iodide (ErI ₃ ) instead of I ₃ )
(2.86 mg / cc) will be described, and the other configuration is the same as the metal halide lamp shown in FIG. 1 of the first embodiment.

FIG. 10 is a diagram showing the spectral distribution of the metal halide lamp of the present embodiment. In this case, the correlated color temperature is about 5000 K, and the luminous efficiency is about 86 lm / W.

This embodiment shows erbium iodide (E
rI ₃ ) is characterized by having a luminescence distribution completely similar to that of holmium iodide (HoI ₃ ). In this regard, erbium iodide (ErI ₃ ) can be completely replaced by holmium iodide (HoI ₃ ).

In the lamp of the present embodiment, a preferable amount of indium iodide is 0.1 mg / cc to 1.5 mg / cc as in the lamp shown in the first embodiment.

In the present embodiment, a similar light emission characteristic was obtained in a lamp in which erbium iodide (ErI ₃ ) was replaced with dysprosium iodide (DyI ₃ ). However, due to the relatively strong devitrification shown in Table 1 of the results of the devitrification evaluation test, the effect on the service life is slightly weaker by replacement of dysprosium iodide (DyI ₃ ). Embodiment 5 Next, indium iodide InI is added at 0.6.
mg (0.86 mg / cc), holmium iodide (Ho
I ₃ ) in an amount of 1 mg (1.43 mg / cc), and 1 mg (1.43 mg) of terbium iodide (TbI ₃ ).
/ Cc), and the other structure is the same as that of the first embodiment shown in FIG.
A lamp which is the same as the metal halide lamp shown in FIG.

FIG. 11 is a diagram showing the spectral distribution of the metal halide lamp according to the present embodiment. In this case, the correlated color temperature is about 6100 K, and the luminous efficiency is about 83 lm / W.

In this embodiment, holmium iodide (H
OI ₃₎ to the added ramp features iodide terbium (TBI ₃₎ is to have a luminous distribution both features have been added. The emission at around 500 nm, which is more abundant than the lamp containing only holmium iodide (HoI ₃ ), is an effect brought about by terbium iodide (TbI ₃ ), and is more abundant than the lamp containing only terbium iodide (TbI ₃ ). Emission in the red region is holmium iodide (HoI ₃ )
Is an effect brought about.

The effect of the addition shown in this embodiment is that holmium iodide (HoI ₃ ) and terbium iodide (Tb
It should be noted that other than the combination of I ₃ ) can be obtained.
Iodide terbium (TBI _3), dysprosium iodide (DyI _3), iodide holmium (HoI _3), iodide erbium (ERI _3), by combining appropriate iodide thulium (TmI _3), each with characteristics A lamp is obtained. For example, when holmium iodide (HoI ₃ ) and thulium iodide (TmI ₃ ) are combined, holmium iodide (HoI ₃ ) improves light emission in the red region where thulium iodide (TmI ₃ ) is slightly less, and thulium iodide (TmI ₃ ) TmI ₃ ) provides even higher luminous efficiency than a lamp containing only holmium iodide (HoI ₃ ). (Embodiment 6) Next, 0.4 mg of indium bromide (InBr) is used instead of indium iodide (InI).
57 mg / cc) and the other configuration is the first embodiment.
A lamp which is the same as the metal halide lamp shown in FIG. 1 will be described.

FIG. 12 is a diagram showing the spectral distribution of the metal halide lamp according to the present embodiment. In this case, the correlated color temperature is about 5300 K, and the luminous efficiency is about 80 lm / W.

As shown in this embodiment, no change in the light emission distribution due to the substitution of indium bromide (InBr) is observed. In this regard, it is possible to replace indium iodide (InI) with indium bromide (InBr). Of course, there is no adverse effect on the service life from the results of the devitrification evaluation test (Table 1). However, efficiency is slightly reduced.

The substitution of indium iodide (InI) with indium bromide (InBr) is not limited to the combination with holmium iodide (HoI ₃ ) shown in the present embodiment. Terbium iodide (Tb
I _3), dysprosium iodide (DyI _3), iodide erbium (ERI _3), iodide thulium (TmI _3), and it is also possible in union with these mixtures. The iodide may be bromide or a combination of iodide and bromide. Bromide holmium (HOBr ₃₎ in place of (Embodiment 7) Next iodide holmium (HoI ₃₎ 1 mg (1.
43 mg / cc), and the other configuration is the same as that of the first embodiment.
A lamp which is the same as the metal halide lamp shown in FIG. 1 will be described.

FIG. 13 is a diagram showing the spectral distribution of the metal halide lamp according to the present embodiment. In this case, the correlated color temperature is about 7200 K, and the luminous efficiency is about 74 lm / W.

A feature of the lamp in which holmium iodide (HoI ₃ ) is replaced by holmium bromide (HoBr ₃ ) is a higher correlated color temperature than the present embodiment shows. Wavelength 44
Emission around 0 nm is greatly increased. The efficiency is reduced by 10% and is comparable to a conventional Dy-Nd-Cs-I lamp.

In the lamp containing thulium iodide (TmI ₃ ) described in the second embodiment, thulium bromide (TmBr ₃ ) is used instead of thulium iodide (TmI ₃ ).
Another lamp enclosing 1 mg (1.43 mg / cc) has a correlated color temperature of about 8600 K and a luminous efficiency of about 81 lm.
/ W. FIG. 14 shows the spectral distribution of this lamp.

As described above, the change of holmium (Ho) or thulium (Tm) from iodide to bromide results in a higher correlated color temperature and a decrease in efficiency of about 10%. On the other hand, the life is longer than that of iodide. This is because thulium (Tm) has a lower devitrification property of bromide than iodide, which is demonstrated in the devitrification evaluation test results (Table 1) described above.

Furthermore, even with dysprosium (Dy) and neodymium (Nd), which showed strong devitrification with iodide, the weak devitrification of bromide is comparable to that of thulium bromide (TmBr ₃ ). It has been clarified that bromide of Ho), terbium (Tb), and erbium (Er) can provide a similar long-life effect.

Of course, even in the case of these bromides, there is no problem in replacing indium iodide (InI) with indium bromide (InBr).

As described above, 0.1 mg / cc to
1.5 mg / cc of indium (In) halide and rare earths, ie, terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (E)
By combining with a halide of the group consisting of r), thulium (Tm) and a mixture thereof, it is possible to realize a highly efficient metal halide lamp capable of meeting demands for relatively high various correlated color temperatures. Further, terbium (Tb), dysprosium (Dy), holmium (H
o) The amount of halide enclosed in erbium (Er), thulium (Tm) or a mixture thereof is set such that the lower limit is an amount determined by the temperature of the halide only to evaporate and the upper limit is 3.0 mg / cc. Then, a metal halide lamp having a longer life can be realized.

In the above embodiment, the arc length is 3.5 ±
Although a 0.5 mm lamp has been described as an example, similar effects can be obtained for lamps outside the range of the arc length as long as the arc length is about 5 mm or less due to manufacturing variations. If it is longer than 5 mm, the efficiency increases but the correlated color temperature decreases.

When indium (In) was replaced with gallium (Ga) belonging to the same 3B group, the luminous efficiency became 70%.
It was less than lm / W. Further, when a halide of tin (Sn) and a iodide of indium (In), which showed weak devitrification in the results of the devitrification evaluation test, were combined, an efficiency of 70 lm / W or more was obtained, but the luminance was low. However, it is not suitable for a light source such as a liquid crystal projector.

In the above embodiment, a metal halide lamp having electrodes has been described as an example. However, a so-called electrodeless metal halide lamp in which a filler inside an arc tube is excited and emits light by an electromagnetic wave or the like supplied from outside without electrodes. Has the same effect.

Although the present invention has been described with reference to a preferred embodiment, such description is by no means limiting, and it goes without saying that various modifications are possible. Similar effects can be obtained with lamps of different wattage and size,
Sodium (Na) to stabilize the arc
The same effect can be obtained by adding a substance containing cesium (Cs) or the like.

It is desirable that the lamp is driven by an alternating current such as a rectangular wave of 270 Hz, a sine wave or a triangular wave. The frequency may be other than 270 Hz.

[0053]

As is apparent from the above description,
According to the present invention, in addition to the starting rare gas, at least a halide of indium (In) and a rare earth, namely, terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), and thulium (Tm). Alternatively, by combining with a halide of these mixtures, an economical light source having an emission spectrum over the entire visible region and having excellent luminous efficiency and capable of responding to a demand for relatively high various correlated color temperatures can be obtained.

Further, the reaction between the material of the light-transmitting container and the additional metal also hardly progresses, devitrification is suppressed, and a long-life light source suitable as a light source for a liquid crystal projector, for example, is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a metal halide lamp according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a light emission distribution of the metal halide lamp according to the first embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the amount of indium iodide and the correlated color temperature in Embodiment 1 of the present invention.

FIG. 4 is a diagram showing a configuration of an optical system used for evaluating the life of the metal halide lamp of the present invention.

FIG. 5 is a diagram showing the relationship between the lighting time and the illuminance maintenance rate of the metal halide lamp according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a light emission distribution of a metal halide lamp according to a second embodiment of the present invention.

FIG. 7 is a diagram showing the relationship between the lighting time and the illuminance maintenance rate of the metal halide lamp according to the second embodiment of the present invention.

FIG. 8 is a graph showing the relationship between the amount of holmium iodide and the luminous efficiency of the metal halide lamp of the present invention.

FIG. 9 is a diagram showing a light emission distribution of a metal halide lamp according to a third embodiment of the present invention.

FIG. 10 is a diagram showing a light emission distribution of a metal halide lamp according to a fourth embodiment of the present invention.

FIG. 11 is a diagram showing a light emission distribution of a metal halide lamp according to a fifth embodiment of the present invention.

FIG. 12 is a diagram showing a light emission distribution of a metal halide lamp according to a sixth embodiment of the present invention.

FIG. 13 is a diagram showing a light emission distribution of a metal halide lamp according to a seventh embodiment of the present invention.

FIG. 14 is a diagram illustrating a relationship between a tube wall load and a correlated color temperature according to the first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arc tube 2a electrode 2b electrode 10 Light source 11 Condensing mirror 12 Projection lens system 13 Screen

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-288101 (JP, A) JP-A-51-35579 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 61/20 H01J 61/88

Claims (6)

(57) [Claims] [1 claim: a starting rare gas into transparent envelope, and halide Lee Nji <br/> ium (In), terbium (Tb),
Dysprosium (Dy), holmium (Ho), erbium (Er), halides out small thulium (Tm)
In the metal halide lamp Type seal the one even without the metal halide lamp has a pair of electrodes,
An alternating current is supplied to the pair of electrodes to be driven, and the indium (In) halide is 0.1 mg /
A metal halide lamp characterized by containing cc to 1.5 mg / cc. 2. Terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er),
3 the upper limit of the enclosed amount of Ha androgenic compound of thulium (Tm).
2. The metal halide lamp according to claim 1, wherein the amount is 0 mg / cc. 3. A tube wall load of 48 W / cm ^{2 to} 62 W / cm ^2.
The metal halide lamp according to claim 1, which is lit by the lamp power of Halogen wherein the halide of the indium (In) may be any metal halide lamp of claim 1 to 3 wherein the iodine or bromine. Halogen wherein the rare earth halide may be any metal halide lamp of claim 1-4, wherein the iodine or bromine. 6. A distance between the electrodes of a pair of electrodes connected to an external power source, according to claim 1, 2, 3 is 5mm or less, or 5
Serial mounting of a metal halide lamp.