JPH05325902A - Lighting device and projection type display - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a long-life illumination optical system excellent in bright color characteristics and a projection type display. [Arrangement] A metal halide lamp having a pair of electrodes and a single-tube structure arc tube in which at least mercury, a rare gas, and a metal halide are enclosed, and the arc axis is horizontal, and the metal halide lamp is arranged in combination. Further, in the illumination optical device comprising a concave reflecting mirror whose reflecting surface is a paraboloid or an ellipsoid, the concave reflecting mirror opening is provided from above the horizontally arranged arc tube toward the upper tube wall of the arc tube. Or, a cooling means is provided from the cutout portion, through at least one thin tube, or through at least one small hole provided above the arc tube of the concave reflecting mirror to selectively blow an air flow above the arc tube. The structure has a total flow rate of 250 ml / min or more 20
It is set to 00 ml / min or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical device in which a horizontally lit metal halide lamp having a single tube structure without an outer tube is combined with a concave reflecting mirror.

[0002]

2. Description of the Related Art In recent years, metal halide lamps have been widely used as light sources for optical equipment, from general lighting such as store lighting and road lighting. In particular, the short arc type metal halide lamp having a single tube structure without using an outer tube has excellent light emission characteristics, light emission efficiency, and life, and therefore, demand is rapidly increasing for various image devices such as a liquid crystal projection display and OHP.

An example of the above metal halide lamp will be described below with reference to the drawings.

FIG. 4 is a block diagram of a conventional metal halide lamp. In FIG. 4, 1 is an arc tube made of quartz glass or the like, and 2 and 2'are a pair of electrodes installed via metal foil conductors 3 and 3 '. 4, 4'is an external lead wire, 5,
5'is a sealing part, and 6 is a heat insulating film. In the arc tube, iodide or bromide such as dysprosium, scandium, neodymium, and thulium is enclosed as a metal halide together with mercury and a rare gas for starting.

While the lamp is lit, the solid metal halide enclosed in the lamp melts and exists as a liquid near the wall of the arc tube, while part of it vaporizes, and the evaporated metal halide is at the center of the arc. The metal vapor is dissociated into metal atoms and halogen atoms, and the metal vapor is excited by an arc to emit a spectrum peculiar to the metal. In a metal halide lamp, convection occurs due to a high pressure of 10 atm or more inside the lamp when the lamp is lit, and the upper part of the lamp becomes hotter than the lower part of the lamp.

[0006]

When such a metal halide lamp is lit in such a posture that the arc axis is substantially horizontal, the temperature of the upper part of the arc tube becomes higher than that of the lower part of the arc tube due to the above-mentioned convection.

The emission spectrum of the metal halide lamp is determined by the vapor pressure of the enclosed metal halide, that is, the temperature of the coldest spot of the lamp. Increasing the coldest spot temperature increases the vapor pressure of the metal halide.
As a result, the emission intensity of the added metal is increased, the color rendering is improved, and the emission efficiency is also improved. On the other hand, when the coldest spot temperature decreases, the color rendering properties and the luminous efficiency decrease. Therefore, in order to improve the color rendering properties and light emission efficiency of the metal halide lamp, it is necessary to increase the electric power supplied to the lamp or downsize the lamp to increase the load on the tube wall and raise the coldest spot temperature.

However, in the horizontal lighting type metal halide lamp, if the temperature of the lower part of the arc tube, which is the coldest point, is increased by increasing the load on the tube wall, the temperature of the upper part of the arc tube also rises at the same time.
The lamp will have a short life. The reason for this is that in a metal halide lamp, the lamp encapsulating metal reacts with the quartz glass that is the material of the arc tube to devitrify the quartz glass, but the devitrification rate is faster as the temperature of the lamp is higher. When the quartz glass devitrifies, the transmittance of the glass decreases, the luminous flux decreases, the heat retention of the lamp increases, the vapor pressure of the enclosed metal halide rises, and the color temperature changes. Welcome.

As described above, the horizontal lighting type metal halide lamp has a short life if an attempt is made to improve the initial color rendering properties and luminous efficiency.
There is a problem that the luminous efficiency is reduced.

In view of the above-mentioned problems, the present invention selectively cools the high temperature portion of the upper portion of the metal halide lamp without significantly lowering the temperature of the coldest spot at the lower portion of the metal halide lamp, and has a long life and excellent color rendering and luminous efficiency. An object is to provide an illumination optical device and a projection display.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a single-tube arc tube having a pair of electrodes and at least mercury, a rare gas, and a metal halide enclosed, in which the arc axis is horizontal. And a metal halide lamp arranged so that the metal halide lamp is arranged in combination, and the reflecting surface thereof is a concave reflecting mirror having a parabolic or elliptical surface, and the metal halide lamp has an arc axis of an optical axis of the concave reflecting mirror. In the illumination optical device positioned above, from the upper side of the horizontally arranged arc tube toward the upper tube wall of the arc tube, through the concave reflector opening or notch, through at least one thin tube, or A cooling means for selectively blowing an air current to the upper part of the arc tube through at least one small hole provided in the upper part of the arc tube of the concave reflecting mirror. And concrete, 250m the air flow rate in the total amount
It is 1 / min or more and 2000 ml / min or less.

Further, the flow rate of the air flow blown to the metal halide lamp may be increased with the lapse of the life time.

The projection type display of the present invention has the illumination optical device as a light source section.

[0014]

According to the present invention, the temperature of the upper part of the horizontal lighting type metal halide lamp can be selectively and significantly lowered without significantly lowering the temperature of the lowermost cold spot thereof, and the devitrification of the quartz glass can be prevented. Can be suppressed.
Therefore, it is possible to simultaneously improve the color rendering property, the light emission efficiency, and prolong the life.

Further, by increasing the flow rate of the blast air flow blown to the metal halide lamp with the lapse of the life time, the vapor pressure of the enclosed metal halide increases with the life time due to the devitrification of the quartz glass, and the color temperature changes. Can be prevented.

When the illumination optical device according to the present invention is used as a light source section of a projection type display, a display image having a bright display, good color characteristics and a long life can be realized.

[0017]

【Example】

(Embodiment 1) An illumination optical device according to an embodiment of the present invention will be described below.

FIG. 1 shows an illumination optical system in which a cooling mechanism 9 is combined with a light condensing system including a metal halide lamp 7, a concave reflecting mirror 8 having a parabolic reflection surface. 10 is a light receiving surface. In each part of the metal halide lamp 7, the same members as those of the metal halide lamp shown in FIG. 4 are designated by the same reference numerals.

The metal halide lamp 7 is a 250 W type with a maximum outer diameter of 14.2 mm, a wall pressure of 1.5 mm, and an internal volume of 0.95 cc. The tube has 100 Torr of argon as a starting rare gas and mercury as a buffer gas. 25 mg, dysprosium iodide 0.6 mg, neodymium iodide 0.5 mg, and cesium iodide 0.6 mg were enclosed. The arc length is 6.8 mm.

The electrode 2 has a diameter of 0.7 mm and a length of 11 mm and is closely wound with a tungsten wire of 0.3 mm in diameter. These electrodes 2 have a thickness of 0.028 mm,
Through a molybdenum foil with a width of 2.5 mm and a length of 20 mm,
The discharge space of the arc tube 1 is hermetically sealed.

The cooling mechanism 9 is a thin tube 1 having an inner diameter of 2.5 mm at the tip.
1, a cooling fan 12, and a hood 13.

In the illuminating optical device thus constructed, the metal halide lamp 7 is lit with a rectangular wave having a frequency of about 120 Hz. An experiment conducted to confirm the effect of the illumination optical device configured as above will be described.

First, the temperature of the upper outer surface and the lower outer surface of the coldest spot of the horizontal lighting type metal halide lamp, the illuminance at the center of the light receiving surface 10, and the spectral distribution were measured when the electric power supplied to the lamp was changed. The temperature measurement positions are indicated by A and B in FIG. The results are summarized in (Table 1).

[0024]

[Table 1]

When the lamp was turned on at a rated power of 250 W, there was a temperature difference of 930 ° C. in the upper part of the lamp, 830 ° C. in the lower part and 100 ° C. in the upper and lower parts, and the upper part temperature was close to the use limit temperature of quartz glass. When the input power of this lamp is reduced to 200 W, the temperature of the upper high temperature part drops to 880 ° C,
The lowermost cold spot temperature has also dropped to 730 ° C.

As a result, the emission intensity of the enclosed metal decreases,
Both the brightness and the color rendering were poor. On the other hand, when the power supplied to the lamp was increased to 300 W in order to increase the emission intensity of the enclosed metal, the coldest spot temperature increased and the illuminance was 35%.
% And the color rendering was also improved to Ra93. However, in this case, the temperature of the upper part of the lamp rose to 1010 ° C., and the lamp expanded and deformed after about 70 hours of lighting. In this measurement, the power applied to the lamp was changed to change the load on the tube wall, but the power applied to the lamp was kept constant at 250 W, and the size of the lamp was changed to change the load on the wall, that is, the lamp temperature. When the coldest spot temperature was raised to improve the luminous efficiency and the color rendering property to increase the luminous intensity of the enclosed metal, the life became short, and when the life was taken into consideration, the initial luminous efficiency and the color rendering property were deteriorated.

Therefore, for the purpose of selectively cooling the upper high temperature portion without reducing the coldest spot temperature of the metal halide lamp as much as possible, the hood 13 is provided by the cooling fan 12 installed outside the concave reflecting mirror 8. Squeezed into a stream by
It sprayed on the high temperature part of the lamp through the narrow tube 11. Then, the temperature of the upper part A and the lower part B of the lamp, the illuminance at the center of the light receiving surface 10 and Ra when the air flow rate was changed were measured in the same manner as in the above experiment. The results are shown in (Table 2).

[0028]

[Table 2]

The temperature of A was lowered by 90 ° C. to 840 ° C. by blowing an air flow of 1000 ml · min ⁻¹ from the thin tube 11 to the high temperature portion above the lamp. At this time, the temperature decrease of the lower part B of the lamp was 30 ° C. Although the illuminance and Ra at the center of the light-receiving surface 10 slightly decreased, the temperature of the high temperature part of the lamp decreased, so that the life was extended and the illuminance at the center of the light-receiving surface remained 55% after 2500 hours of lighting, and there was no lamp deformation. .. The life is 1000 hours without air cooling. By changing the lamp flow rate and comprehensively judging the results of examining the optical characteristics of life, illuminance, and Ra, the thin tube 1 is practically used.
The flow rate from 1 to the lamp is 250 ml ・ mi
It has been found that it is necessary to control the amount to be n ⁻¹ or more and 2000 ml · min ⁻¹ or less.

When the inner diameter of the thin tube 11 is small, only a part of the upper part of the lamp is cooled, so that the effect of the present invention is not so remarkable. Further, when the inner diameter is large, the air flow goes around to the lower part of the lamp and the coldest spot temperature is lowered. As a result of examination by changing the size of the thin tube 11, the inner diameter of the thin tube needs to be 0.1D or more and 0.9D or less, where D is the maximum outer diameter of the arc tube.

(Embodiment 2) Next, an illumination optical device according to a second embodiment will be described.

FIG. 2 shows an illumination optical system in which a cooling mechanism 16 is combined with a condensing system comprising a metal halide lamp 14, a concave reflecting mirror 15 having an elliptical reflecting surface and two small holes. 10 is a light receiving surface. Metal halide lamp 1
4, the same members as those of the metal halide lamp shown in FIG. 4 are designated by the same reference numerals. The metal halide lamp 14 has a maximum light emitting portion outer diameter of 11.2 mm and a wall pressure of 1.5 m.
150 W type with an internal volume of 0.50 cc, argon is 100 torr as a starting rare gas, mercury is 15 mg as a buffer gas, and dysprosium iodide is 0.
3 mg, 0.3 mg of neodymium iodide and 0.5 mg of cesium iodide are enclosed. The arc length is 5.0 mm.

The electrode 2 is formed by tightly winding a tungsten wire of φ0.3 mm around a tungsten core rod of φ0.6 mm and a length of 9 mm. These electrodes 2 are hermetically sealed in the discharge space of the arc tube 1 via a molybdenum foil having a thickness of 0.028 mm, a width of 2.0 mm and a length of 15 mm.

The cooling mechanism 16 is composed of a thin tube 17 having a tip inner diameter of 4.0 mm, a cooling fan 12, and a hood 13.

In the illuminating optical device thus constructed, the metal halide lamp 14 is lit with a rectangular wave having a frequency of about 250 Hz. The effects of the illumination optical device configured as described above were evaluated in the same manner as in Example 1. As a result, also in this embodiment, the total flow rate sprayed from the two thin tubes 17 to the upper part of the lamp is 250 ml · min ₋₁ or more and 2000 ml ·
It has been clarified that the effect of the present invention is remarkably exhibited when the _{value is} min ₋₁ or less, and an excellent illumination optical device capable of achieving both optical characteristics and life can be provided. The size of the thin tube had to be 0.1 to 0.9 times the maximum outer diameter of the arc tube as in Example 1.

In the first or second embodiment, the angle formed by the blast cooling thin tube and the vertical axis passing through the center of the lamp may be 90 degrees or less. In other words, it was confirmed that if the lamp is cooled from within the horizontal plane passing through the arc axis or from above the horizontal plane, the high temperature portion above the lamp can be selectively cooled.

By the way, when the lighting life of the lamps in Examples 1 and 2 was evaluated, the glass gradually devitrified with time, though it was smaller than the conventional one. At this time, the illuminance on the light receiving surface decreases due to the decrease in the luminous flux, and the spectral distribution on the light receiving surface also changes due to the change in the color temperature of the lamp. This is because the devitrification phenomenon caused the coldest spot temperature to rise compared to the initial temperature. Therefore, in order to prevent the lamp color temperature from changing with the life of the lamp, it is sufficient to increase the blast flow rate with time when locally cooling the high temperature portion of the lamp according to the present invention. The coldest spot temperature rises due to devitrification and the vapor pressure of the enclosed metal halide increases, which is reduced by increasing the blast flow rate. (Table 3)
In Example 2, there is shown the change over time in the illuminance and color temperature at the center of the light receiving surface when there is no cooling, when the air flow rate is constant, and when the air flow rate is increased with time.

[0038]

[Table 3]

The air flow rate may be increased based on the thermocouple fixed to the lamp or the value of the lamp voltage.
From Table 3, it was found that increasing the air flow rate with time reduced the color temperature change, suppressed the accelerated progress of devitrification, and improved the illuminance reduction.

(Embodiment 3) FIG. 3 is a schematic view showing a liquid crystal projector as an embodiment of a projection type display device using the illumination optical device of FIG. 1 as a light source section. 18 is a light source unit, 1
Reference numeral 9 is a dichroic mirror, 20 is a mirror, 21 is a liquid crystal panel, 22 is a field lens, and 23 is a projection lens. The characteristics of the light-receiving surface 10 reflect the effect of the illumination optical device according to the present invention, and it is possible to realize a long life without significantly lowering the brightness and color characteristics as compared with the case where the conventional cooling mechanism is not installed.

In the embodiment shown in FIG. 3, the illumination optical device shown in FIG. 1 is used as the light source section, but the same effect can be obtained by using the illumination optical device shown in FIG. Further, by increasing the air flow rate with time in these, it is possible to obtain a bright image with excellent color characteristics for a long time.

[0042]

As described above, the present invention provides a metal halide lamp having a pair of electrodes and a single-tube structure arc tube in which at least mercury, a rare gas, and a metal halide are enclosed, and the arc axis is horizontal. In an illumination optical device comprising a concave reflector whose reflection surface is a parabolic surface or an elliptic surface, in which the metal halide lamp is arranged in combination, an upper tube wall of the arc tube is arranged above the horizontally arranged arc tube. Toward, from the concave reflector opening or notch through at least one thin tube, or
A cooling means for selectively blowing an air current is provided above the arc tube through at least one small hole provided above the arc tube of the concave reflecting mirror, and the air flow rate is 25 in total.
By setting it to 0 ml / min or more and 2000 ml / min or less, it is possible to prolong the life without significantly deteriorating the brightness and color characteristics. Further, by increasing the flow rate of air blow with time, it is possible to suppress the change in color temperature and further prolong the life. When the illumination optical device of the present invention is used as a light source unit of a projection type display, it is possible to achieve both brightness, color characteristics and life.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an illumination optical system according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an illumination optical system according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a projection type display according to a third embodiment of the present invention.

FIG. 4 is a block diagram of a conventional metal halide lamp.

[Explanation of symbols]

 1 Quartz glass arc tube 2 Electrode 3 Metal foil conductor 4 External lead wire 5 Sealing part 6 Heat insulation film 7 Metal halide lamp 8 Concave reflector 9 Cooling mechanism 10 Light receiving surface 11 Capillary tube 12 Cooling fan 13 Hood 14 Metal halide lamp 15 Concave surface Reflection mirror 16 Cooling mechanism 17 Capillary tube 18 Light source section 19 Dichroic mirror 20 Mirror 21 Liquid crystal panel 22 Field lens 23 Projection lens

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideto, 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A metal halide lamp comprising a pair of electrodes, and an arc tube having a single-tube structure in which at least mercury, a rare gas, and a metal halide are enclosed, and the arc axis of which is horizontal. Arranged, the reflecting surface is composed of a concave reflecting mirror consisting of a paraboloid or an ellipsoid, the metal halide lamp, the arc axis is located on the optical axis of the concave reflecting mirror in the illumination optical device, the horizontally arranged From the upper part of the arc tube toward the upper tube wall of the arc tube, from the concave reflecting mirror opening or notch, there is provided a cooling means for selectively blowing an air flow to the upper part of the arc tube through at least one thin tube, Total flow rate of air flow is 250ml / min or more 2000ml /
An illuminating optical device characterized in that it is not more than min. 2. A metal halide lamp comprising a pair of electrodes, in which an arc tube having a single tube structure in which at least mercury, a rare gas, and a metal halide are enclosed, is arranged so that the arc axis is horizontal, and the metal halide lamp is combined. Arranged, the reflection surface is composed of a concave reflecting mirror consisting of a paraboloid or an ellipsoid, the metal halide lamp is an illumination optical device whose arc axis is located on the optical axis of the concave reflecting mirror, At least one small hole is provided in the upper part of the arc tube, and cooling means for selectively blowing an air flow from the small hole to the upper part of the arc tube is provided, and the total flow rate of the air flow is 250 ml / min or more and 2000 ml / min or less. An illumination optical device characterized by: 3. The illumination optical apparatus according to claim 1 or 2, wherein the flow rate of the blast airflow is increased as the lighting time of the metal halide lamp elapses. 4. A projection type display incorporating the illumination optical device according to claim 1, claim 2 or claim 3.