JPH07192688A - Metal halide lamp, lighting system and projection display device - Google Patents

Abstract

PURPOSE:To provide a metal halide lamp suited for a projector use light source having high luminous efficiency and screen brightness in small size to improve also color balance further with a long life. CONSTITUTION:Input power of a metal halide lamp 2 is set within a range from about 130 to about 180W, to set an interelectrode distance AL within a range from about 2.5mm to about 3.5mm, and a luminous part 22 of an arc tube 21 is formed as a whole into almost an elliptic sphere or almost a spherical shape, to set its external diameter D within a range from about 9mm to about 11mm, and also to set its length L within a range of about 9mm to about 11mm. Further, a diameter of electrode mandrels 25, 26 of constituting an electrode is set within a range from about 0.55mm to about 0.65mm. By this constitution, a lamp, through it is in small size, having high screen illuminance to improve color balance further with a long life, can be realized. Particularly, the lamp of this invention is suited for use as a light source for a projector or the like.

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 suitable for use as a light source of a projection type display device. The present invention also relates to a lighting device including a combination of the metal halide lamp and a reflecting mirror. Further, the present invention relates to a projection display device using this metal halide lamp as a light source.

[0002]

2. Description of the Related Art Metal halide lamps have high luminous efficiency, long life and excellent color rendering properties as compared with other types of lamps, and therefore, projection display devices (hereinafter referred to as projectors) and the like. It is used as a light source. Generally, an illumination device is configured by combining it with a reflecting mirror and is used as a light source for a projector or the like.

In a general metal halide leamp used conventionally, the arc length, that is, the distance between electrodes is about 5 mm to 7 mm, and the input power is about 150 W. Here, when a metal halide lamp is used as a light source of a projector or the like, it is desired to reduce the light emitting portion of the lamp to improve the optical efficiency such as the light collection rate.

[0004]

However, in order to reduce the size of the light emitting portion of the lamp, it is necessary to shorten the distance between the electrodes sealed by the seal portions formed at both ends of the light emitting portion. The spectrum tends to be a bright line spectrum, which makes it unsuitable as a light source for a projector. Also, if the light emitting part is made smaller, the arc tube may devitrify due to the reaction with the metal halide enclosed therein, or the load on the tube wall of the arc tube may increase and the lamp life may be significantly shortened. There is.

An object of the present invention is to propose a metal halide lamp which has a small light emitting portion suitable for use as a light source of a projector, has a good color rendering property, and has a long life. Another object of the present invention is to propose an illumination device including a combination of the metal halide lamp and a reflecting mirror. Furthermore, the subject of this invention is proposing the projector which used this metal halide lamp as a light source.

[0006]

In order to solve the above-mentioned problems, according to the present invention, a light-emitting tube and a seal section formed at both ends of the light-emitting tube are provided with a predetermined sealing member. In a metal halide lamp having a structure in which a pair of electrodes arranged to face each other at a space of and a metal halide are enclosed, the following structure is adopted. That is, the input power of the lamp is set within the range of about 130 to about 180W. Moreover, the distance between the electrodes is about 2.5.
It is set within the range of mm to about 3.5 mm. Further, the light emitting part of the arc tube is generally elliptical or spherical, and its outer diameter is within the range of about 9 mm to about 11 mm, and its length is about 9 mm to about 11 m.
It is set within the range of m. Furthermore, the diameter of the electrode mandrel which constitutes the electrode is about 0.55 mm to about 0.65 mm.
It is set within the range of mm.

In the above structure, the input power is 130 W
If it is less than 180 W, the luminous efficiency of the lamp is drastically reduced, and if it exceeds 180 W, the tube wall load becomes too large and the life becomes short, which is not preferable.

The shorter the distance between electrodes, that is, the arc length,
Although the light collection efficiency can be improved, the longer the light emission efficiency is, the better. Therefore, the optically suitable range is a range in which both of these are taken into consideration, and this range is about 2.5 mm.
To about 3.5 mm.

If the size of the light emitting portion of the lamp is smaller than the above range, the tube wall load becomes excessive and the life of the lamp is adversely affected. On the other hand, if the size is larger than the above range, the optical characteristics, especially the color rendering properties are deteriorated, which is not preferable.

Next, when the outer diameter of the electrode rod is less than 0.55 mm, the heat capacity thereof is small, which may cause heat damage. On the other hand, when the thickness exceeds 0.65 mm, the lamp starting voltage is increased and the heat loss of the electrodes is increased, which causes deterioration of the light emission characteristics such as the light emission efficiency of the lamp and the color rendering.

According to the present invention configured as described above, it is possible to realize a metal halide lamp having good optical characteristics, a long life, and suitable for use as a light source of a projector.

Next, in the metal halide lamp having the above structure, the amount of metal halide enclosed therein is
A range of about 0.2 mg to about 0.6 mg is preferred. If the amount is larger than this, devitrification of the arc tube will start early and the lamp life will be shortened. On the other hand, if it is less than this range, the light emitting characteristics are deteriorated and the blackening of the arc tube is likely to occur, which is not preferable.

Here, as the metal halide to be encapsulated, at least one of tin halide, lead halide and zinc halide is further added in an amount within the range of about 0.05 mg to about 0.1 mg. It is preferable to add.
By doing so, the vapor pressure in the arc tube can be increased, the color rendering properties can be further improved, and a lamp with a better color balance can be realized. If you add more than this range,
Luminous efficiency is reduced, which is not preferable. If the amount is less than this range, the effect of adding these metal halides cannot be obtained.

As the metal halide to be enclosed, it is preferable to add mercury bromide instead of the generally enclosed mercury iodide. The amount of mercury bromide added is
The molar ratio of the bromine to the total amount of iodine is about 0.1 to about 0.
It is preferably within the range of 6. When the amount of bromine added in this range is high, bromine has a high activity and therefore has a strong bond with the tungsten of the electrode and has a fast reaction rate, so that it is possible to prevent blackening in the arc tube and prolong the life of the lamp. . If the added amount is more than the above range,
It is not preferable because bromine causes the consumption of the electrode. On the other hand, if the amount is less than the above range, the effect of addition cannot be obtained.

Next, the illuminating device of the present invention adopts a constitution comprising a combination of the metal halide lamp having the above constitution and a reflecting mirror having a reflecting surface, and the opening side of the reflecting mirror in the arc tube of the metal halide lamp. The feature is that the shape of is thin. When combined with the reflector, the temperature of the lamp on the bottom side of the reflector increases, but the temperature on the opening side of the reflector does not rise so much. In the present invention, since the shape of the opening-side portion of the reflecting mirror is made thin, it is possible to raise the temperature of this portion, thereby improving the temperature balance in the arc tube and improving the emission vector. .

Here, in order to raise the temperature on the opening side of the reflecting mirror, the outer periphery of the seal part of the arc tube of the lamp located on the opening side and the light emitting part continuous to this is covered with a heat insulating film. I'll do it. However, in a miniaturized arc tube as in the present invention, if the range covered by the heat retaining film is too wide, the temperature of the arc tube on the bottom side of the reflecting mirror becomes too high,
Not preferable. Therefore, in the lighting device of the present invention,
Among the seal portion of the arc tube on the opening side of the reflecting mirror and the outer periphery of the light emitting portion continuous with the seal portion, at least only the portion of the outer periphery of the seal portion that is continuous with the light emitting portion is covered with the heat insulating film. Further, when covering the portion of the light emitting portion continuous to this with a heat insulating film, the width is about 2 mm or less from the boundary between the seal portion and the light emitting portion toward the bottom side of the reflecting mirror. By forming the heat insulating film in this way, it is possible to suppress the temperature rise of the highest temperature part of the arc tube.

[0017]

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

(First Embodiment) FIG. 1 is a schematic block diagram of an optical system of a liquid crystal projector to which the present invention is applied. The light source of the liquid crystal projector 1 is composed of an illuminating device 6 including a combination of a metal halide lamp 2 and a reflecting mirror 4. A green reflection dichroic mirror 7, a red reflection dichroic mirror 8 and a reflection mirror 9 on which aluminum is vapor-deposited are arranged in this order from the side of the lighting device 6 along the optical axis direction of the light emitted from the lighting device 6. There is. These mirrors are arranged at an angle of 45 degrees in the same direction with respect to the optical axis. With respect to the green reflective dichroic mirror 7, a reflective mirror 10 having aluminum vapor-deposited is arranged at a constant interval in a direction orthogonal to the optical axis direction. In a similar arrangement relationship, the red reflection dichroic mirror 8 is arranged to face the red reflection dichroic mirror 8, and the blue transmission dichroic mirror 12 is arranged to face the reflection mirror 9 on which ammiluminium is vapor-deposited. Further, a blue liquid crystal panel 13 is arranged between the red reflection dichroic mirror 8 and the reflection mirror 9 on which aluminum is vapor-deposited,
A red liquid crystal panel 14 is disposed between the red reflection dichroic mirrors 8 and 11, and a green liquid crystal panel 1 is disposed between the reflection mirror 10 and the red reflection dichroic mirror 11.
5 are arranged.

The light emitted from the illuminating device 6 is separated into red, green and blue colors by a reflecting dichroic mirror of each color. The separated lights of the respective colors pass through the liquid crystal panels of the corresponding colors. When passing, the intensity of light is adjusted by the video signal corresponding to each color.
The intensity-adjusted light of each color is transmitted to the dichroic mirror 11
And 12 and then the projection lens 16
Is enlarged and projected by. This allows the screen 17
The image is obtained by connecting the image above.

FIG. 2 is a schematic sectional view of the illumination device 6 in this example. In this figure, 2 is a metal halide lamp, and 4 is a reflecting mirror to which this lamp is attached.
The light emitting tube 21 of the metal halide lamp 2 of this example is made of quartz glass, and the light emitting portion 22 formed in the center thereof has an elliptic spherical shape that is approximately a spherical shape.
Electrode seal portions 23 and 24 are integrally formed on both sides of 2. Inside the light emitting portion 22, electrode core rods 25 and 26, whose base ends are sealed in the seal portions 23 and 24, are arranged so as to face each other at regular intervals on a substantially coaxial line. Coils 27 and 28 formed by winding a tungsten wire around are arranged at positions slightly retracted from the tips of the electrode core rods 25 and 26, respectively.
Each electrode core rod 2 embedded in the seal portions 23 and 24
Molybdenum foils 29 and 30 are provided on the base end sides of 5 and 26, respectively.
Is connected to the molybdenum wires 31 and 32 via. The other ends of the molybdenum wires 31 and 32 are
They are connected to the base 33 and the nickel lead wire 34, respectively.

On the other hand, the reflecting mirror 4 is provided with a reflecting surface 41 having a parabolic cross section as shown in the drawing, and a lamp mounting hole 42 is formed in the center of the bottom of the reflecting surface. A portion of the base 33 of the lamp having the above structure is inserted into the mounting hole 42, and is fixed by a heat resistant adhesive. here,
The lamp 2 is mounted such that the axial centers of the electrode core rods 25 and 26 thereof coincide with the central axis of the reflecting surface 41. The nickel lead wire 34 of the lamp penetrates the reflecting mirror 4 and is routed to the back surface side, and is connected to a terminal 35 for external connection. A terminal member 36 for external connection is also attached to the bottom surface side of the base 33.

Here, the arc tube 21 of the metal halide lamp 2 of this example is designed for a ramp power of 150 W. The maximum outer diameter D of the light emitting portion 22 in the light emitting tube 21.
Is 10 mm. The length L, that is, the distance between the embedded surfaces of the electrode mandrel 25 and 26 is 10 mm. The thickness of the light emitting portion is set to approximately 1 mm.
Next, the pair of electrode core rods 2 enclosed in the light emitting portion 22.
Nos. 5 and 26 have an outer diameter of 0.6 mm, and the distance between them, that is, the inter-electrode distance AL is set to 3 mm. Further, in the present example, in the arc tube 21, as the metal halide, dysprosium iodide,
0.3 mg of neodymium iodide and cesium iodide were enclosed, and mercury as a buffer gas and argon as an auxiliary gas for starting were enclosed.

In the liquid crystal projector 1 using the illuminating device 6 of the present embodiment thus constructed, good screen illuminance can be obtained, color rendering is excellent, and devitrification occurs even when used for a long time. It was confirmed that there was not.

Here, the inventor of the present invention measured the light emission efficiency and the fluctuation of the tube wall load with respect to the change of the input power, using the metal halide lamp 2 having the above-mentioned structure. This result is shown in Figure 3.
Shown in. As shown by the characteristic curve 101 in the figure, it can be seen that the luminous efficiency (lm / W) sharply decreases when the input power falls below 130W. On the other hand, pipe wall load (W / cm
It can be seen that 2) increases almost in proportion to the input power, as shown by the characteristic curve 102. 90 W / wall load
When the state exceeds cm2, the quartz glass arc tube 21
The risk of bursting increases. Therefore, the input power is about 130 W from the relationship between the luminous efficiency and the wall load.
To about 180 W is preferred. The characteristic curve in the figure is
Although the inter-electrode distance AL is 3 mm as described above, substantially the same result was obtained when the distance AL was changed in the range of about 2.5 mm to about 3.5 mm.

Next, the metal halide lamp 2 having the above structure
In, the fluctuation of the luminous efficiency and the fluctuation of the light collection rate on the liquid crystal panel when the distance AL between the electrodes was changed were measured. In this measurement, a liquid crystal panel having a size of 1.3 inches was used. Curve 103 in FIG. 4 (B)
Indicates the change of the light collection rate (%) with respect to the inter-electrode distance AL,
A curve 104 shows a change in luminous efficiency (lm / W). As can be seen from these curves, the light collection rate is improved as the interelectrode distance AL is shortened. That is, as the light source for the projector, the closer it is to the point light source, the easier it is to use, and a bright screen can be obtained. However, if the inter-electrode distance AL is made too short, the collision of electrons becomes more intense with respect to the electrodes, so that the temperature of the electrodes rises and the tungsten, which is the electrode, exceeds the melting point and gradually scatters.

On the other hand, as shown by the curve 104,
The luminous efficiency is improved as the distance AL between the electrodes is increased, that is, the arc length between the electrodes is increased. As described above, the light emission efficiency and the light collection rate are inversely related to the inter-electrode distance AL. Therefore, the screen illuminance is
Both of these values need to be considered.

FIG. 4A shows a curve 105 obtained by plotting a value obtained by multiplying the inter-electrode distance AL by both of these values. As can be seen from the curve 105, good characteristics are obtained when the inter-electrode distance AL is in the range of about 2.5 mm to about 3.5 mm.

Next, the dimensions of the light emitting portion 22 of the light emitting tube 21 will be described. As the light source of the liquid crystal projector,
It is necessary that the emission spectra of red, green, and blue colors are well balanced. White on the screen is red,
Determined by the ratio of green and blue light intensity. When the inter-electrode distance AL is shortened as in this example, the spectrum is likely to be the bright line spectrum of mercury. For this reason, the bright line of green is strong, and unless the amount of green light is reduced, a greenish white appears on the screen. However, reducing green, which has a high relative visibility, reduces the brightness obtained on the screen. This offsets the improvement in screen illuminance obtained by shortening the inter-electrode distance AL. Here, the element that determines the spectral distribution of the lamp is the vapor pressure in the arc tube, and the element that determines the vapor pressure is the temperature of the coldest part of the arc tube. Therefore, by reducing the size of the arc tube,
The temperature of the coldest part should be raised. By increasing the temperature of the coldest part in this way, the vapor pressure in the arc tube is increased, the light emission of the enclosed metal is promoted, and the emission line spectrum of mercury can be weakened.

In view of this point, the present inventor changed the tube diameter D of the arc tube 21 in the metal halide lamp 2 of this example, and measured the average color rendering index (Ra) for it. That is, the change in the average color rendering index with respect to the change in the outer diameter D of the light emitting unit 22 was measured. Curve 106 in FIG. 5 represents this relationship. By reducing the size of the arc tube, the temperature of the coldest part of the arc tube is increased, the vapor pressure in the arc tube is increased, the enclosed metal emits light, and the emission line spectrum is weakened.
This corresponds to an increase in the average color rendering index (Ra) as shown by the curve 106. If the average color rendering index increases, the color balance becomes better and it is more suitable for use as a light source of the projector. It will be suitable. However, if the size of the pipe is too small, the load on the pipe wall increases,
The risk of pipe rupture also increases. Further, the temperature of the highest temperature part is also increased, and the quartz glass, which is the material of the arc tube, may be intolerable. Considering these points, the arc tube has a substantially elliptical sphere or a spherical shape, and the outer diameter D and the length L of the light emitting portion are about 9 mm to about 11 mm.
It was confirmed that it is preferable to set it within the range.

Next, the diameter of the pair of electrode core rods 25 and 26 in the metal halide lamp 2 of this example will be described. The input power generally used in the past is 1
The diameter of the electrode core rod in the 50 W metal halide lamp is about 0.5 mm, and the distance between the electrodes is about 5 mm. When the distance AL between the electrodes is narrowed from about 2.5 mm to about 3.5 mm as in this example, the electrons collide violently with the tungsten, which is the electrode, and the electrode temperature exceeds the melting point of tungsten. The electrodes may scatter gradually. In such a situation, the distance between the electrodes becomes long, and the reaction between tungsten and quartz causes blackening of the interior of the arc tube. In this example, in order to avoid such an adverse effect, the electrode core rod is made thicker than that conventionally used and its diameter is 0.6 mm.
Is set to. By making it thick in this way, the heat capacity of the electrode is increased, scattering of the electrode is less likely to occur, and blackening in the arc tube can be prevented. This makes it possible to extend the life of the lamp. According to the experiments conducted by the inventor of the present invention, if the diameter of the electrode is thicker than 0.65 mm, the lamp starting voltage may increase and the heat loss of the electrode may increase, which may deteriorate the light emission characteristics. It was confirmed. Therefore, the electrode diameter is preferably in the range of about 0.55 mm to about 0.65 mm.

As described above, in the metal halide lamp 2 of this example, the input power is about 130.
It is set within the range of W to about 180 W, the inter-electrode distance AL is set within the range of about 2.5 mm to about 3.5 mm, and the light emitting part of the arc tube has an outer diameter D and a length L of about 9 mm. Set an elliptical sphere in the range of about 11 mm or a roughly spherical shape,
Furthermore, the diameter of the electrode is about 0.55 mm to about 0.65 m.
It is set to m. Therefore, according to this example, a light source suitable for a liquid crystal projector having a high screen illuminance, good color balance, and a long life can be realized.

Here, the relationship between the amount of the metal halide enclosed in the arc tube of the metal halide lamp 2 having the above-mentioned configuration and the life is considered. In order to investigate this relationship, the present inventor measured the relationship of the illuminance maintenance rate of the lamp with respect to the enclosed amount. FIG. 6 shows a variation curve of the illuminance maintenance rate (%) with respect to the lighting time. In this figure, the curve 107 is the curve 10 when the enclosed amount is 0.4 mg.
The curve 8 shows the case where the enclosed amount is 0.6 mg, and the curve 109 shows the case where the enclosed amount is 0.8 mg. As can be seen from these curves, the higher the amount of filling, the shorter the life. This is because, when the amount of the enclosed light is increased, the amount of the enclosed metal does not evaporate with respect to the size of the arc tube, and the liquid layer of metal halide accumulates on the lower side of the arc tube. This liquid layer reacts with the quartz glass, which is the material of the arc tube, to cause devitrification. When devitrification starts, devitrification rapidly spreads throughout the arc tube, shortening its life. It was confirmed that by suppressing the amount of inclusion to be 0.6 mg or less, the reaction between the liquid layer of the metal halide and quartz was less likely to occur, and devitrification due to this reaction was less likely to occur. However, if the enclosed amount is less than 0.2 mg, it is not preferable because it causes problems such as deterioration of light emitting characteristics and blackening of the arc tube. Therefore, by setting the enclosed amount of this metal halide within the range of about 0.2 mg to about 0.6 mg, while maintaining the light emission characteristics,
It is possible to extend the life of the lamp.

Next, in order to further improve the color balance in the lamp of this example, one of tin halide, lead halide, or zinc halide is used as the metal halide to be filled, and the amount of the metal halide is about 0. 05mg to about 0.1mg
It may be added in the range of. For example, when 0.05 mg of tin halide is added, the vapor pressure in the arc tube increases, the emission line spectrum of mercury is suppressed, the emission of other metal halides is promoted, and the average color rendering index (Ra) is It was confirmed that the color balance was improved and the color balance was improved. However, if the amount of tin halide added is more than 0.1 mg, the luminous efficiency is lowered, which is not preferable. On the contrary, if the addition amount is less than 0.05 mg, the effect of addition cannot be obtained. Therefore, the addition amount is preferably within the range of about 0.05 mg to about 0.1 mg. The same applies to the case of lead halide and zinc halide.

On the other hand, in the lamp of this example, in order to achieve a longer life, mercury bromide may be added to the arc tube instead of mercury iodide. When mercury bromide is added, the activity of bromine is higher than when mercury iodide is added, so that the bond with tungsten is stronger and the reaction rate is faster. Therefore, blackening in the arc tube can be prevented and the life of the lamp can be extended. The amount of mercury bromide added should be set so that the molar ratio (B / A) of the total iodine amount (A mol) to the bromine amount (B mol) is in the range of about 0.1 to about 0.6. Good. If the amount added is less than this, the effect of adding mercury bromide cannot be obtained. On the other hand, if the amount of addition is larger than this, bromine with high activity reacts with tungsten, which is the electrode, and the electrode becomes thin or easily broken. FIG. 7 shows the variation of the illuminance maintenance rate (%) with respect to the lighting time of the lamp when mercury bromide was added (curve 110) and mercury iodide was added (curve 111) with the same addition amount. It is shown. As you can see from this figure,
When mercury bromide is added, the illuminance maintenance rate is better and therefore the life of the lamp can be extended.

(Other Embodiment of Arc Tube) FIG. 8 shows another embodiment of the metal halide lamp in the above-mentioned first embodiment. The metal halide lamp 60 of this example is
Since the lamp 2 is the same as the above-described lamp 2 except that the shape of the arc tube is different, the same reference numerals are given to the corresponding portions, and the description of those portions will be omitted below.

When the metal halide lamp is used as a lighting device for a projector or the like, light is collected by a reflecting mirror or the like. Arc tube 62 of metal halide lamp 60 in this case
The temperature distribution of is as follows. Since the arc tube surface surrounded by the reflecting mirror 4 is surrounded by the reflecting mirror as compared with the case of the lamp alone, the temperature rises. On the contrary, the temperature of the arc tube surface on the opening side of the reflecting mirror 4 is equal to or slightly higher than that of the lamp alone. Here, the emission spectrum of the lamp 61 is the lowest temperature portion of the arc tube, that is,
Since it depends on the temperature of the coldest part, the emission spectrum is improved by increasing the temperature of this part. The coldest portion is located substantially at the boundary between the light emitting portion 62 and the seal portion 24 in the light emitting tube on the open side of the reflecting mirror 4.

In this example, in order to raise the temperature of the coldest part, the shape of the arc tube on the opening side of the reflecting mirror in the arc tube is made thin, and this part is brought close to the arc formed between the electrodes. I am trying. That is, the arc tube 6
The shape of the light emitting portion 62 of No. 1 is as follows:
The shape is almost elliptical or spherical, but on the opposite side, it is thin so as to have a substantially truncated cone shape.

Thus, in this example, the arc tube 61 is
Since the shape of the light emitting portion 62 is thin on the opening side of the reflecting mirror, the temperature of the coldest portion thereof can be increased and the emission spectrum of the lamp can be improved. In addition,
It goes without saying that the shape of the light emitting portion 62 on the opening side of the reflecting mirror may be a shape other than the truncated cone shape as in this example.

FIG. 9 shows a modification of the arc tube 61. In the metal high-rad lamp 70 shown in this figure, the portion of the arc tube 71 on the side of the reflector opening is
By coating with a heat insulating film, the temperature of the coldest part is raised,
We are working to further improve the emission spectrum. That is, in this example, almost the entire outer peripheral surface of the seal portion 24 on the side of the reflecting mirror opening of the arc tube 71 and the outer peripheral portion of the light emitting portion 72 that is continuous with this are covered with the heat insulating film 75. (In the figure, the formation range of the heat retaining film is shown by hatching.). By forming the heat insulating film 75 in this way, the temperature of the coldest part of the arc tube 71 can be raised and the emission spectrum can be improved.

Here, it is known that the heat insulating film is formed in the past. However, in this example, the heat insulating film 75 formed on the outer periphery of the light emitting portion 72 is formed so that the width from the boundary between the seal portion 24 and the light emitting portion 72 toward the light emitting portion side is about 2 mm or less. It is characterized by that. That is, in this example, as described above,
Since the size of the arc tube is reduced, the arc tube 7
The temperature of the hottest part in 1 is also rising. For this reason, if the outer circumference of the light emitting portion 72 is widely covered with a heat insulating film as in the conventional case, the temperature of the highest temperature portion becomes too high, and the material of the arc tube, quartz, deteriorates. In this example, since the heat insulating film covering the light emitting portion 72 is limited to a small range, devitrification of quartz due to high temperature can be prevented, and the lamp life can be extended.

In this example, the outer circumference of the seal portion 24,
Although the heat insulating film is formed on both the outer periphery of the light emitting portion 72 which is continuous with this, it goes without saying that the heat insulating film may be formed only on the seal portion 24.

[0042]

As described above, according to the present invention,
Input power of metal halide lamp is about 130 to about 18
It is set within the range of 0 W, the distance between the electrodes is set within the range of about 2.5 mm to about 3.5 mm, and the light emitting portion of the arc tube is formed into a generally elliptical or spherical shape, and its outer diameter is set to about The length is set within the range of 9 mm to about 11 mm, and the length thereof is set within the range of about 9 mm to about 11 mm.
Further, the diameter of the electrode mandrel forming the electrode is set within the range of about 0.55 mm to about 0.65 mm. According to this configuration, it is possible to realize a lamp that is small in size, has a high screen illuminance, has good color balance, and has a long life. In particular, the lamp of the present invention is suitable for use as a light source of a projector or the like.

Further, in the present invention, the amount of the metal halide to be enclosed is set in the range of about 0.2 mg to about 0.6 mg, so that the life of the lamp can be extended while maintaining the light emission characteristics. be able to.

Further, in the present invention, at least one of tin halide, lead halide and zinc halide is further added as the metal halide to be encapsulated in an amount of about 0.
An amount in the range of 05 mg to about 0.1 mg is added. By doing so, the vapor pressure in the arc tube can be increased, the color rendering can be further improved, and a lamp with a better color balance can be realized.

Furthermore, in the present invention, as the metal halide to be enclosed, mercury bromide is enclosed instead of mercury iodide, and the molar ratio of the bromide amount to the total iodine amount is about 0.1 to about. The addition is made within the range of 0.6. By doing so, it is possible to prevent blackening in the arc tube and prolong the life of the lamp.

Next, in the present invention, an illumination device is constituted by the metal halide lamp having the above-mentioned structure and a reflecting mirror having a reflecting surface, and the shape of the arc tube side of the reflecting tube in the arc tube of the metal halide lamp is narrowed. The configuration is adopted.
By doing so, the temperature on the opening side of the reflecting mirror in the arc tube (the temperature of the coldest part) can be increased. Therefore, the temperature balance in the arc tube can be improved, and the emission vector can be improved.

Further, in the illuminating device of the present invention, in order to raise the temperature on the opening side of the reflecting mirror, only the sealing part of the arc tube of the lamp located on the opening side, or together with this part, is applied. The outer circumference of the continuous light emitting portion is covered with a heat insulating film with a maximum width of 2 mm. By forming the heat insulating film in this way, the temperature of the coldest part can be raised and an excessive temperature rise of the hottest part of the arc tube can be suppressed.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an optical system of a liquid crystal projector that is an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing the lighting device of FIG.

FIG. 3 is a graph showing changes in luminous efficiency and tube wall load with respect to input power.

FIG. 4B is a graph showing changes in the light collection efficiency on the panel and the light emission efficiency with respect to the distance between the electrodes, and FIG. 4A is a graph showing the product of the light collection efficiency and the light emission efficiency plotted against the distance between the electrodes. It is a graph.

FIG. 5 is a graph showing variations in the average color rendering index with respect to the size of the arc tube.

FIG. 6 is a graph showing changes in the illuminance maintenance rate with respect to the lighting time of the metal halide lamp when the amount of the enclosed metal halide is changed.

FIG. 7 is a graph showing changes in illuminance maintenance rate with respect to lighting time of a metal halide lamp when mercury bromide or mercury iodide is added.

FIG. 8 is a schematic cross-sectional view showing another embodiment of the metal halide lamp.

9 is a schematic cross-sectional view showing a modified example of the metal halide lamp of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Projector 2 ... Metal halide lamp 4 ... Reflector 21 ... Arc tube 22 ... Light emitting part 23, 24 ... Seal part 25, 26 ... Electrode core rod 41 ... Reflective surface 42 ... Mounting holes 60, 70 ... Metal halide lamp 61, 71 ... Arc tube 62, 72 ... Light emitting part 75 ... Heat insulation film AL ... Distance between electrodes D ... Light emission Outer diameter L ... Length of light emitting part

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Tsuji Urushihara 1-1 Iriyama-cho, Gyoda-shi, Saitama Prefecture Iwasaki Electric Co., Ltd. Saitama Factory (72) Hisao Yoshiike 1-1 Iriyama-cho, Gyoda-shi, Saitama Iwasaki Electric stock company Saitama Factory

Claims (9)

[Claims] 1. An arc tube composed of a light emitting part and seal parts formed at both ends thereof, a pair of electrodes sealed inside the seal part and facing each other at a predetermined interval, and the arc tube. In a metal halide lamp having a metal halide enclosed therein, the input power of the lamp is in the range of about 130 to 180 W, and the distance between the electrodes is in the range of about 2.5 mm to about 3.5 mm. The light emitting portion of the arc tube has an elliptical sphere or a substantially spherical shape as a whole, its outer diameter is in the range of about 9 mm to about 11 mm, and its length is in the range of about 9 mm to about 11 mm. The diameter of the electrode mandrel forming the electrode is about 0.55.
The metal halide lamp is characterized by being in the range of mm to about 0.65 mm. 2. The metal halide according to claim 1, wherein the metal halide includes at least Dy, Nd, and Cs halides, and the amount of the metal halides is in the range of about 0.2 mg to about 0.6 mg. Metal halide lamp that does. 3. The metal halide according to claim 2, further comprising at least one of tin halide, lead halide and zinc halide in an amount of about 0.05 m.
A metal halide lamp characterized by containing an amount within the range of g to about 0.1 mg. 4. The metal halide according to claim 2, which contains mercury bromide as the metal halide, and the molar ratio of the bromine amount to the total iodine amount is in the range of about 0.1 to about 0.6. A metal halide lamp characterized by being present. 5. A metal halide lamp according to any one of claims 1 to 4 and a reflecting surface, wherein one end of the metal halide lamp is located on the bottom side of the reflecting surface and the other is A reflector arranged to be located on the open side of the reflecting surface, and a shape of the arc tube of the metal halide lamp on the side of the opening of the reflector is narrowed. apparatus. 6. The seal portion of the arc tube on the opening side of the reflecting mirror and the outer periphery of the light emitting portion continuous with the seal portion according to claim 5, wherein at least a portion of the outer periphery of the seal portion which is continuous with the light emitting portion. An illuminating device characterized by being covered with a heat insulating film. 7. The heat insulating film according to claim 6, wherein the outer periphery of the light emitting portion continuous with the seal portion covered with the heat insulating film is also covered with the heat insulating film, and the heat insulating film of the light emitting portion is a boundary between the seal portion and the light emitting portion. To about 2 mm from the bottom of the reflector
An illuminating device having the following width. 8. A projection type display device using the metal halide lamp according to any one of claims 1 to 4 as a light source. 9. A projection display device, comprising the illumination device according to claim 5. Description: