JP2000231903A - Discharge lamp, light source device and projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the start, the arc stability and the lamp life of a discharge lamp consisting mainly of a short arc. SOLUTION: This discharge lamp is provided with a light emitting tube 10, sealed parts 11 and 12 formed on both sides of the light emitting tube 10, and metallic foils 13 and 14 sealed on the sealed parts 11 and 12, a pair of electrodes 15 and 16 connected to the metallic foils 13 and 14 with a large diameter part on their tip ends, coils 17 and 18 disposed backward the large diameter part of the electrodes 15 and 16, and discharge media 21 and 22 sealed in the light emitting tube 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp, a light source device for forming illumination light using the discharge lamp, and a spatial light modulator for forming an optical image by supplying a video signal from the light source device and an external device. The present invention relates to a projection display device that projects a large-screen image on a screen using a liquid crystal element (for example, a liquid crystal element) and a projection lens.

[0002]

2. Description of the Related Art Small discharge lamps such as metal halide lamps and ultra-high pressure mercury lamps are widely used as light sources for projection display devices and the like. In such a case, a light source device is configured by combining a discharge lamp and a concave mirror,
This is generally used as a light source of a projection display device.

FIG. 17 shows a configuration example of a conventional discharge lamp. The discharge lamp 321 mainly includes an arc tube 301, sealing portions 302 and 303, metal foils 304 and 305, and an electrode 30.
6, 307, external conductors 308, 309, discharge medium 31
0, 311, and 312. Quartz glass, an electrode 306,
Tungsten 307 is used, molybdenum foil is used for the metal foils 304 and 305, and molybdenum is used for the external conductors 308 and 309. Further, mercury 310, a luminescent metal 311 such as a metal halide, and a rare gas 312 such as argon are mainly used as a discharge medium.

[0004] When a predetermined voltage is applied to the external conductors 308 and 309, an arc discharge is generated between the electrodes 306 and 307, and light emission specific to the mercury 310 and the metal halide 311 is obtained. Argon gas 312 is used to improve startability. In this type of discharge lamp, the distance between the electrodes is extremely short, and a large current flows at the time of starting. Therefore, electrode deformation and blackening due to evaporation of the electrode material are likely to occur, and it is difficult to extend the life. On the other hand, various discharge lamps have been disclosed in which the lamp life is improved by devising an electrode structure (for example, JP-A-7-192688, JP-A-10-192688).
-92377). 18 to 20 are enlarged views showing examples of the configuration of the electrode.

FIG. 18 shows that a coil 33 is provided at the tip of the electrode 330.
This is an example in which the heat radiation property is improved by providing No. 1 and deterioration and deformation due to excessive temperature rise of the tip are suppressed. FIG. 19 shows an example in which a discharge portion 342 having a diameter larger than the axis of the electrode 341 is provided at the tip of the electrode 340 to increase thermal conductivity, and to suppress deterioration and deformation due to excessive temperature rise at the tip. This type of electrode is used as the anode of a DC discharge lamp.

FIG. 20 shows that a coil is thickly wound around the tip of the electrode 350, and the tip is melted by discharge so as to be integrated with the electrode shaft 351 to form a discharge portion 352 having a diameter larger than that of the electrode shaft 351. In this example, a heat radiating portion 353 in which a coil is integrally melted is provided behind the discharge portion 352 to suppress deterioration and deformation of the electrode. The radiator 353 is
It is configured using a coil or a cylindrical electrode member.

[0007]

However, FIG.
20 have the following problems.
In the case of FIG. 18, since the contact area between the electrode 330 and the coil 331 is small, heat conduction is low, and it is difficult to obtain a sufficient heat radiation effect. If the coil 331 is too thin, the coil 33
1 was melted and deformed. The coil 331 may be made thicker, but the tungsten used for the electrode 330 is made of a hard material, which makes it difficult to wind the coil 331. Further, there is a problem that the arc spot of the discharge moves to the tip of the electrode or the end of the coil, and it is difficult to stabilize the arc.

In the case of FIG. 19, if the diameter of the large-diameter discharge portion 342 is too large, it is difficult for the electrode 340 to rise to a temperature required for emitting thermoelectrons, causing problems such as deterioration of startability and extinguishing. . This is a serious problem particularly when the lamp is to be AC-lit, and it has been difficult to use such an electrode for AC lighting. In the case of FIG.
And the coil 353 are integrally and continuously formed, the heat conduction between the discharge unit 352 and the coil 353 is high, and it is difficult for the discharge unit 352 to rise to the temperature required for thermionic emission. Similarly, deterioration of startability and disappearance occur. This is a serious problem particularly when the discharge lamp is to be operated by AC. The electrode as shown in FIG. 20 is obtained by discharging an electrode having a configuration in which a coil 353 is wound around an electrode shaft 351 in an atmosphere of an inert gas such as a nitrogen gas or an argon gas and melting a tip portion thereof. Manufactured. In a discharge lamp, an electrode obtained by adding a doping material such as thorium to tungsten as an electrode material is often used in order to improve startability. However, the electrode manufactured by the above-described manufacturing method has a problem that the doping material evaporates when the tip portion is melted. Furthermore, since the recrystallization proceeds at the tip due to melting, the strength is weak,
There was a problem that processing was difficult.

On the other hand, when this kind of discharge lamp is used in a projection display device, it is general to constitute a light source in combination with a concave mirror. FIG. 21a shows an example of the configuration. FIG. 21B is a cross-sectional view taken along line AA in FIG. 21A. The concave mirror 371 is provided with a reflective coating 372 on its inner surface, and efficiently reflects the light emitted from the lamp 360 in a predetermined direction. The concave mirror 371 is provided with a lamp insertion portion 373 and a lead hole 374.
The lamp 360 has the sealing portion 362 inserted into the lamp insertion portion 373, and is fixed to the concave mirror 371 by a heat-resistant adhesive 375. The external conductor 369 has an extension conductor 376.
Is connected, and the other end of the extension conductor 376 is connected to the conductor extraction hole 3.
74 is drawn out of the concave mirror 371. By applying a predetermined voltage between the external conductor 368 and the extension conductor 376, light emission of the lamp 360 can be obtained.

[0010] Lamps used in projection display devices are required to be as small as possible and have a long life. However, the conventional light source shown in FIG. 21A has the following problems. First, there is a problem that the metal foils 364 and 365 and the external conductors 368 and 369 provided at both ends of the lamp 360 are broken due to oxidation and the lamp life is shortened. In the case of the light source shown in FIG.
As shown in the enlarged cross-sectional view of A, a distortion due to thermal stress occurs between the external conductor 369 and the sealing portion 363 during sealing, and a gap B is formed. Therefore, the ends of the external conductor 369 and the metal foil 365 on the side of the external conductor 369 are in contact with air, and oxidation of these parts is promoted under extremely high temperature conditions during lamp operation. The time until the wire breaks due to oxidation varies depending on the temperature. For example, when molybdenum is used for the metal foil, it is about 5000 hours under the condition of 350 ° C. in the air. The same applies to the external conductor 368 and the sealing portion 362.

In general, a discharge lamp used in a projection display device has an extremely high temperature during operation, and the arc tube 361 has a temperature close to 1000 ° C. at the maximum. Therefore, the arc tube 361
The temperature near the connection between the metal foils 364 and 365 and the external conductors 368 and 369 reaches several hundred degrees due to heat conduction from the electrodes 366 and 367. The temperature can be lowered by forcibly cooling with a fan or the like.
If the temperature is lowered to 61, evaporation of the luminescent metal is suppressed, and the luminous efficiency is significantly reduced. Therefore, extremely local cooling is required and difficult.

In order to solve this problem, in a conventional discharge lamp, a sufficiently long metal foil is used, and a temperature rise due to heat conduction is reduced to suppress disconnection due to oxidation. However, there has been a problem that the longer the metal foil, the longer the total length of the lamp becomes, and it is difficult to reduce the size of the light source.
Second, since the luminescent metal evaporates during lamp operation, the pressure inside the arc tube is, for example, several tens of atmospheres in the case of a metal halide lamp and several tens of MPa in the case of an ultra-high pressure mercury lamp.
(Megapascal), which is very high, and there is a problem that the arc tube is easily damaged during lighting.

It is an object of the present invention to improve the starting performance, arc stability, and lamp life, even for short arcs. Another object of the present invention is to provide a compact, highly reliable light source device suitable for use mainly in a projection type display device, and to efficiently collect light emitted from a discharge lamp. Further, by using the light source device of the present invention, a bright, compact, and highly reliable projection display device can be provided.

[0014]

According to a first aspect of the present invention, there is provided a first discharge lamp comprising: an arc tube; sealing portions formed at both ends of the arc tube; A pair of electrodes opposed to each other at a predetermined interval, and a discharge medium sealed in the arc tube, wherein the electrodes are formed integrally with an electrode shaft and a tip of the electrode shaft. A discharge portion having a larger outer diameter than the discharge portion, and having a heat dissipation conductor surrounding the electrode axis at the rear of the discharge portion.

[0015] A second discharge lamp according to the present invention comprises: an arc tube;
Sealing portions formed at both ends of the arc tube, a pair of electrodes sealed to the sealing portion, and disposed opposite to each other at a predetermined interval in the arc tube, and a discharge medium sealed in the arc tube. ,
The electrode comprises an electrode shaft, a discharge portion having a larger outer diameter than the electrode shaft formed integrally with the tip of the electrode shaft, and the tip of the discharge portion is tapered. ,
A heat-radiating conductor surrounding the electrode axis is provided at the rear of the discharge part, the distance between the electrodes in the arc tube is L, the diameter of the tip of the discharge part is φ, and the angle formed by the taper with the electrode axis is θ. Then, φ / L ≦ 0.6 20 ° ≦ θ ≦ 60 ° is satisfied.

A third discharge lamp according to the present invention comprises an arc tube,
Sealing portions formed at both ends of the arc tube, a pair of electrodes sealed to the sealing portion, and disposed opposite to each other at a predetermined interval in the arc tube, and a discharge medium sealed in the arc tube. ,
And the electrode comprises: an electrode shaft; and a cylindrical conductor fitted into the tip of the electrode shaft, and having a heat dissipation conductor surrounding the electrode shaft at the rear of the cylindrical conductor.

A fourth discharge lamp according to the present invention comprises an arc tube,
Sealing portions formed at both ends of the arc tube, a pair of electrodes sealed to the sealing portion, and disposed opposite to each other at a predetermined interval in the arc tube, and a discharge medium sealed in the arc tube. ,
The electrode has an electrode shaft, a cylindrical conductor fitted into the tip of the electrode shaft, the outer diameter portion on the tip side of the electrode shaft is formed in a tapered shape, the cylindrical conductor of the A heat radiation conductor surrounding the electrode axis is provided at the rear, the distance between the electrodes in the arc tube is L, the outer diameter of an end surface of the cylindrical conductor near the tip of the electrode axis is φ, and the taper is the electrode axis. Assuming that the formed angle is θ, φ / L ≦ 0.620 ° ≦ θ ≦ 60 ° is satisfied.

A fifth discharge lamp according to the present invention comprises an arc tube,
Sealing portions formed at both ends of the arc tube; a pair of electrodes sealed to the sealing portion and arranged at predetermined intervals in the arc tube; and mercury and rare earth sealed in the arc tube. A gas, and the amount of the enclosed mercury is 150 mg / cc.
That is, the electrode includes an electrode shaft and a discharge portion having a larger outer diameter than the electrode shaft formed integrally with the tip of the electrode shaft, and the discharge portion has a tapered tip. There is a heat-radiating conductor surrounding the electrode axis behind the discharge part, the distance between the electrodes in the arc tube is L, the diameter of the tip of the discharge part is φ, and the angle formed by the taper with the electrode axis. Assuming that θ, φ / L ≦ 0.6 20 ° ≦ θ ≦ 60 ° is satisfied, and an AC voltage is applied to the electrodes to light them.

A sixth discharge lamp according to the present invention, in the third or fourth discharge lamp, wherein the electrode comprises only an electrode shaft and a cylindrical conductor fitted into a tip of the electrode shaft,
No heat dissipation conductor is provided. A seventh discharge lamp according to a fifth aspect of the present invention is the discharge lamp according to the fifth aspect, wherein the electrodes are formed only by the electrode shaft and a discharge portion having a larger outer diameter than the electrode shaft integrally formed at a tip of the electrode shaft. No heat dissipation conductor is provided.

In the third or fourth discharge lamp,
It is preferable that the cylindrical conductor has a tapered inner end farther from the tip of the electrode shaft. The above first to first
In any one of the fifth discharge lamps, the heat dissipation conductor is preferably in a coil shape. In any one of the first to fifth discharge lamps, it is preferable that the materials of the electrode and the heat radiation conductor are different. In any one of the first to seventh discharge lamps, the electrode is preferably formed by doping tungsten with thorium.

In the first, second, fifth, or seventh discharge lamp, the distance between the electrodes is 2 mm or less, the outer diameter of the electrode shaft is D1, the outer diameter of the discharge part is D2, and the electrode of the discharge part is D2. Assuming that the length in the axial direction is D3, it is preferable to satisfy 2.0 ≦ D2 / D1 ≦ 5.0 D3 / D1 ≦ 9.0.

In the third, fourth or sixth discharge lamp, the electrode spacing is 2 mm or less, the outer diameter of the electrode axis is D1, the outer diameter of the cylindrical conductor is D2, and the electrode axis of the cylindrical conductor is Assuming that the length in the direction is D3, it is preferable to satisfy 2.0 ≦ D2 / D1 ≦ 5.0 D3 / D1 ≦ 9.0.

In any one of the first to seventh discharge lamps, the discharge medium is preferably mercury and a rare gas. In any one of the first to seventh discharge lamps,
The thing that applies an AC voltage to the electrodes and turns them on is
preferable. In any one of the first to seventh discharge lamps, a DC voltage is applied to the electrodes to light the electrodes,
It is preferable that the polarity of the voltage be inverted according to the driving time or the number of lightings.

In any one of the first to seventh discharge lamps, it is preferable that the electrode is made of pure tungsten. In any one of the first to seventh discharge lamps,
The electrode is preferably made of pure tungsten in which at least one of potassium, silicon, and aluminum is 10 ppm or less.

According to an eighth aspect of the present invention, there is provided an discharge lamp, comprising: a discharge tube forming a discharge space; sealing portions formed at both ends of the discharge tube; and metal foils respectively sealed in the sealing portions. An electrode having one end connected to the metal foil and the other end disposed opposite the inside of the arc tube, and an external electrode having one end connected to the metal foil and the other end protruding outside the sealing portion. The metal foil includes a conductor and a discharge medium sealed in the arc tube, and the metal foils have different lengths.

In an eighth discharge lamp, the discharge medium is:
Contains inert gas and mercury. In an eighth discharge lamp,
The arc tube is made of quartz glass or sapphire glass. In the eighth discharge lamp, holding means is provided in a sealing portion in which a short length of metal foil is sealed.

[0027] In the eighth discharge lamp, the holding means is made of metal. ADVANTAGE OF THE INVENTION According to this invention, the discharge lamp which is excellent in starting property and has a long life even if it is a short arc can be implement | achieved. A first light source device of the present invention includes any one of the first to seventh discharge lamps, and a concave mirror that reflects light emitted from the discharge lamp in a predetermined direction.

A second light source device according to the present invention includes the first to seventh discharge lamps, and a concave mirror that reflects light emitted from the discharge lamp in a predetermined direction, wherein the concave mirror reflects reflected light. The discharge lamp has an opening for emitting light and a lamp insertion portion provided on the opposite side of the opening, and the discharge lamp has one end inserted into the lamp insertion portion and a light emitting region formed between a pair of electrodes. The center is arranged so as to substantially coincide with the focal point on the short side of the concave mirror, and light rays emitted from the center of the light emitting region and incident on the effective reflection surface of the concave mirror are not blocked by the electrodes of the discharge lamp. Things.

A third light source device according to the present invention includes an eighth discharge lamp and a concave mirror that reflects light emitted from the discharge lamp from a predetermined direction, wherein the discharge lamp is made of a metal having a short length. A sealing portion in which the foil is sealed is fixed to the concave mirror. A fourth light source device according to the present invention includes a discharge lamp, and a concave mirror that reflects light emitted from the discharge lamp in a predetermined direction, wherein the discharge lamp is sealed at both ends of an arc tube. The concave mirror has an opening through which reflected light is emitted, and a lamp insertion portion provided on the opposite side of the opening, and the discharge lamp has a long length. Inserting a sealing portion in which a short metal foil is sealed into the lamp insertion portion, and disposing the sealing portion so that the center of the light emitting region formed in the arc tube approximately matches the focal point on the short side of the concave mirror. Things.

A fifth light source device according to the present invention comprises a discharge lamp, a concave mirror for reflecting light emitted from the discharge lamp in a predetermined direction, and an opening on the reflected light emission side of the concave mirror. And a translucent sealing means for forming a sealed space inside the concave mirror, wherein an inert gas is sealed in the sealed space. A sixth light source device according to the present invention includes a discharge lamp, a concave mirror that reflects light emitted from the discharge lamp in a predetermined direction, and a concave mirror that is disposed in an opening on a reflected light emission side of the concave mirror, and Light-transmitting sealing means for forming a sealed space therein, wherein gas is sealed in the sealed space at a pressure higher than 1 atm and lower than the operating pressure of the discharge lamp. .

The seventh light source device of the present invention has an operating pressure of 10
A discharge lamp of not less than MPa (megapascal), a concave mirror for reflecting light emitted from the discharge lamp in a predetermined direction, and a light-transmitting sealing means;
The lengths of the metal foils sealed in the sealing portions provided at both ends of the arc tube are different from each other, and the concave mirror has an opening through which reflected light is emitted, and a lamp insertion portion provided on the opposite side of the opening. And the discharge lamp, while inserting a sealing portion in which a short metal foil is sealed into the lamp insertion portion,
The center of a light emitting region formed in the arc tube is arranged so as to substantially coincide with the focal point on the short side of the concave mirror, and the sealing means is arranged in the opening of the concave mirror.

In the fifth or sixth light source device, the concave mirror is preferably an elliptical mirror. The fifth or sixth above
In the light source device, the operating pressure of the discharge lamp is 10 MPa.
(Megapascal) or more is preferable. In the fourth or seventh light source device, the concave mirror is an elliptical mirror,
It is preferable that the distance from the vertex of the elliptical surface on the lamp insertion portion side to the end of the long metal foil on the concave mirror opening side is not more than １ ／ of the major axis length of the elliptical surface.

According to the present invention, it is possible to realize a light source device for efficiently condensing light emitted from a lamp. Further, a small and highly reliable light source device can be realized. A projection display device according to the present invention includes a light source, an image forming unit that is illuminated by the light source and forms an optical image according to a video signal, and projects an optical image formed on the image forming unit onto a screen. And a projection unit, wherein the light source is any one of the first to seventh light source devices.

According to the present invention, a small, highly reliable and bright projection display device can be realized.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. 1a and 1b are configuration examples showing a first embodiment of the discharge lamp of the present invention. FIG. 1b is an enlarged sectional view of the electrode portion shown in FIG. 1a. 10 is an arc tube, 11 and 12 are sealing parts, 13 and 14 are metal foils, 15 and 16 are electrodes, 17 and 18 are coils as heat dissipation conductors, 19 and 20 are external conductors, and 21 and 22 are discharge media. Is a discharge lamp of the present invention.

The arc tube 10 has an outer diameter of 15 mm and a maximum thickness of 3
mm transparent quartz glass, in which a spherical or elliptical discharge space is formed. Transparent quartz glass has excellent heat resistance and is a material suitable for a discharge lamp whose operating temperature is extremely high. Another advantage is that the light transmittance is high. Alternatively, a high thermal conductivity material such as sapphire glass can be used. When the thermal conductivity is high, there is an advantage that the temperature distribution of the arc tube 10 becomes uniform, the light emission characteristics are stabilized, and the arc tube 10 is easily cooled.

At both ends of the arc tube 10, sealing portions 11 and 12 are provided.
Is provided. The sealing portions 11 and 12 are made of the same transparent quartz glass as the arc tube 10. Metal foils 13 and 14 having a width of 3.5 mm and a length of 16 mm are sealed to the sealing portions 11 and 12, respectively. The metal foils 13 and 14 use molybdenum as a high melting point metal. The electrodes 15 and 16 have one ends connected to the metal foils 13 and 14, respectively, and the other ends opposed to each other within the arc tube 10 with a distance of 2.0 mm. FIG.
As shown in FIG. 2B, the electrode 15 is composed of an electrode shaft 15a and a discharge portion 15b integrally formed with a larger diameter. Pure tungsten is used as the material of the electrode 15. The electrode 15 can be easily obtained by cutting a columnar electrode material. Alternatively, the electrode 15 having a predetermined shape may be formed using a mold made of molybdenum, carbon, ceramic, or the like. The outer diameters of the electrode shaft 15a and the discharge part 15b are 1.0 mm and 3.0 mm, respectively. The length of the discharge portion 15b in the axial direction is 1.8 mm. A coil 17 is wound behind the discharge portion 15b so as to surround the electrode shaft 15a. Coil 17
Is pure tungsten having a wire diameter of 0.5 mm. The coil 17 may be fixed to the electrode shaft 15a by, for example, spot welding. Similarly, the electrode shaft 1
6a and a discharge portion 16b having a larger diameter than the discharge portion 16a. A coil 18 is wound behind the discharge portion 16b so as to surround the electrode shaft 16a.

One end of each of the external conductors 19 and 20 is connected to the metal foils 13 and 14, and the other end protrudes outside the sealing portions 11 and 12. As the metal foils 13 and 14, molybdenum is used for the external conductors 19 and 20. By applying a predetermined voltage to the external conductors 19 and 20, the electrodes 1
An arc discharge occurs between 5 and 16, and the emission of the mercury 21 as the discharge medium can be obtained with the evaporation of the mercury 21. In addition, an argon gas 22 is sealed as a rare gas at a predetermined pressure to improve the startability of the lamp.

As the rare gas, an inert gas such as xenon gas may be used in addition to the argon gas, and the starting performance can be improved. In addition, a predetermined amount of a halogen gas, for example, iodine, bromine, chlorine or the like may be sealed together with the rare gas. These halogen gases combine with tungsten as an electrode material to generate a halogen cycle, and prevent the inner wall of the arc tube from being blackened due to the scattering of tungsten during lighting, thereby improving the life of the lamp.

If the discharge lamp 31 is formed by using the electrodes 15 and 16, a light emitting portion by arc discharge is formed between the large-diameter discharge portions 15b and 16b. Discharge parts 15b, 16b
Has a large heat capacity and good thermal conductivity, and thus has an effect of suppressing excessive heating of the electrodes 15 and 16 even when a relatively large current flows. Thereby, the electrodes 15, 16
Deformation and evaporation of the electrode material are greatly suppressed, and the lamp life is improved. The coils 17, 18 are connected to the electrode shafts 15a, 1
Excessive temperature rise is suppressed by increasing the heat radiation of 6a, and thinning and breakage of this portion are prevented. Further, unlike the electrode of FIG. 17, the arc spot does not become unstable, and stable light emission can be obtained. Further, since the electrodes 15, 16 and the coils 17, 18 are not integrally melted but are separate bodies, the thermal conductivity between the discharge portions 15b, 16b and the coils 17, 18 is low. In addition, since the shapes of the discharge portions 15b and 16b are appropriately set so that the heat capacities do not become too large,
The discharge portions 15b and 16b are not excessively cooled, and can easily rise to a temperature at which thermionic electrons can be emitted. As compared with the case where the electrodes shown in FIGS. To be improved.

As described above, according to the structure of the present invention, an electrode composed of an electrode shaft and a discharge portion having a larger outer diameter than the electrode shaft integrally formed at the tip of the electrode shaft is used. By providing a heat-radiating conductor surrounding the electrode axis behind the discharge portion, a discharge lamp with excellent startability and a long life even with a short arc can be realized. 2a and 2b are configuration examples showing a second embodiment of the discharge lamp of the present invention.
FIG. 2B is an enlarged sectional view of the electrode portion shown in FIG. 2A.

In the discharge lamp 51, the electrodes 41, 42
The other configuration is the same as that shown in FIG. 1A. FIG.
The difference from a is that a large-diameter discharge portion 41 constituting the electrode 41
b, the point is that the tip is tapered 41c. The taper 41c is formed at an angle of 45 ° with respect to the electrode axis 41a, and the tip of the discharge part 41b has a circular cross section with a diameter of 1.0 mm. As for the electrode 42, the electrode 41
Similarly, the taper 4 is formed at an angle of 45 ° with respect to the electrode 42a.
2c is formed.

The present embodiment has the following effects in addition to the effects obtained in the embodiment of FIGS. 1A and 1B. Tapers 41c, 42 are provided at the tips of the discharge portions 41b, 42b.
By providing c and reducing the tip diameter φ, the electron emissivity is increased, and the startability is further improved as compared with those shown in FIGS. 1a and 1b. At the same time, the ramp-up time until the lamp reaches a stable state is greatly improved. Further, since thermionic emission is mainly generated from the tips of the discharge portions 41b and 42b, there is an advantage that the radial width of the arc is smaller and the brightness of the light emitting portion is higher than when the tapers 41c and 42c are not provided. is there. Also, the discharge units 41b, 42b
Is small, so that the so-called bright spot shift, in which the arc spot moves at the tips of the discharge portions 41b and 42b, is less likely to occur, and the arc stability at the time of lighting is improved. Furthermore,
Since the range in which the radiated light from the light emitting unit is shielded by the large-diameter discharge units 41b and 42b can be reduced, the radiated light can be used efficiently. Further, as compared with the conventional electrode shown in FIG. 20, the processing of the tip portion is easier, and the yield is improved.

In order to obtain a sufficient effect of the present invention, the following conditional expressions may be satisfied. φ / L ≦ 0.6 (Equation 1) 20 ° ≦ θ ≦ 60 ° (Equation 2) where L is the distance between the electrodes 41 and 42 in the arc tube 10, φ is the diameter of the tip of the discharge part 41b or 42b, θ is the angle between the taper 41c, 42c and the electrode axis 41a, 42a.

In the formula 1, when φ / L is larger than the upper limit value, the above-mentioned effects relating to startability, rise time and arc stability are undesirably reduced. Further, the amount of light shielded by the discharge units 41b and 42b increases, which is not preferable. In Equation 2, if θ is smaller than the lower limit, the tips of the discharge portions 41b and 42b become too thin, and the electrodes 41 and 42 are easily deteriorated. On the other hand, if it is larger than the upper limit value, the above-mentioned effects relating to startability, rise time and arc stability are undesirably reduced. Further, the amount of light shielded by the discharge units 41b and 42b increases, which is not preferable.

The electrode may be an electrode 45 having a spherical tip at the discharge portion as shown in FIG. in this case,
The diameter φ of the tip of the discharge portion 45b in Expression 1 may be defined by the distance between the contact points between the outer periphery 46 of the sphere and the taper 45c. As described above, according to the configuration of the present invention, an electrode axis,
By using an electrode composed of a discharge portion integrally formed at the tip of the electrode shaft and having a larger outer diameter and a taper than the electrode shaft, and having a heat dissipation conductor surrounding the electrode shaft behind the discharge portion, It is easy to manufacture, does not induce unstable discharge, is excellent in startability and start-up performance at the time of lighting, can efficiently use emitted light, and can realize a long-life discharge lamp even with a short arc. FIGS. 4A and 4B are configuration examples showing a third embodiment of the discharge lamp of the present invention. FIG. 4B is an enlarged sectional view of the electrode portion shown in FIG. 4A.

In the discharge lamp 71, the electrodes 61, 62
The other configuration is the same as that shown in FIG. 1A. FIG.
The difference from a is that the electrode 61 is composed of an electrode shaft 61a and a cylindrical conductor 61b provided at the tip thereof. The electrode shaft 61a is a pure tungsten having an outer diameter of 1.0 mm. The cylindrical conductor 61b has an outer diameter of 3.0 mm. The length of the cylindrical conductor 61b in the axial direction is 1.8 mm and is made of pure tungsten, and is fitted to the tip of the electrode shaft 61a. The cylindrical conductor 61b can be fixed to the electrode shaft 61a by, for example, spot welding or the like. Similarly to the electrode 61, a cylindrical conductor 62b is provided at the tip of the electrode 62.

The heat generated at the electrode shafts 61a and 62a is radiated through the cylindrical conductors 61b and 62b. Since the cylindrical conductors 61b and 62b have good contact with the electrode shafts 61a and 62a and have high thermal conductivity, the electrode shaft 6 at which the temperature is the highest is obtained.
Heat is efficiently dissipated from the distal end portions of 1a and 62a. Compared to the electrode shown in FIG. 1b, the large diameter portion at the tip is formed separately, so that there is no need to cut out this portion and there is an advantage that it can be manufactured more easily.

By disposing a heat radiating conductor such as the coil 65 behind the cylindrical conductor 61b, the heat transmitted to the rear of the electrode shaft 61a can be efficiently radiated, so that the electrode shaft 61a can be prevented from being thinned or broken. . The same applies to the electrode 62. 4A and 4B, the electrode shaft 61
a and 62a are arranged so that the end faces of the cylindrical conductors 61b and 62b are flush with each other.
The end of 2a may be fitted so that it slightly protrudes from the end surfaces of the cylindrical conductors 61b and 62.

As in the case of the electrode 66 shown in FIG.
A cylindrical conductor 66b provided with a taper 67 which is notched inward may be used in the inner peripheral part on the side remote from the tip of a.
The taper 67 has the effect of increasing the surface area of the cylindrical conductor 66b to further enhance heat dissipation. At the same time, by adjusting the angle η of the taper 67 and appropriately setting the contact area between the electrode shaft 66a and the cylindrical conductor 66b, the startability can be further improved. A heat dissipating conductor such as a coil 65 may be provided behind the cylindrical conductor 66b. The same applies to the electrode 62.

Further, as shown in FIG. 6, the same effect can be obtained by using an electrode 68 in which a cylindrical conductor 68b whose inner peripheral portion does not penetrate is fitted to the tip of the electrode shaft 68a.
A heat-radiating conductor such as the coil 65 or an inner peripheral taper similar to that shown in FIG. 5 may be provided. However, in the present invention, the heat dissipating conductor such as the coil 65 is arranged in FIGS. 4, 5, and 6, but the coil 65 may not be provided.

As described above, according to the configuration of the present invention, the electrode shaft, the cylindrical conductor fitted to the tip of the electrode shaft,
By using an electrode composed of
It is possible to realize a discharge lamp having excellent startability and having a long life even with a short arc without inducing an unstable discharge.
FIGS. 7A and 7B are configuration examples showing a fourth embodiment of the discharge lamp of the present invention. FIG. 7B is an enlarged sectional view of the electrode portion shown in FIG. 7A.

In the discharge lamp 91, the electrodes 81, 82
The other configuration is the same as that shown in FIG. 4A. FIG.
The difference from a is that the cylindrical conductor 81b constituting the electrode 81
Is tapered 81c. Taper 81c
Are formed at an angle of 45 ° with respect to the axis of the electrode 81,
The outer diameter of the tip of the cylindrical conductor 81b is 1.0 mm and the electrode shaft 8
1a is equal to the outer diameter. Regarding the electrode 82,
Similarly to the electrode 81, a taper 82c is formed in the cylindrical conductor 82b. By arranging a heat radiating conductor such as the coil 85 behind the cylindrical conductor 81b, the heat transmitted to the rear of the electrode shaft 81a can be efficiently radiated, so that the thinning and breaking of the electrode shaft 81a can be prevented. The same applies to the electrode 82.

In the present embodiment, the heat radiating conductor such as the coil 85 is disposed, but the coil 85 may not be provided. In the present embodiment, in addition to the effects obtained in FIG. 4, the startability and the rise time are further improved. At the same time, there is an advantage that the luminance of the light emitting unit is increased. In addition, the bright spot shift is less likely to occur, and the arc stability during lighting is improved. Further, since the area where the light emitted from the light emitting section is shielded by the cylindrical conductors 81b and 82b is small, the emitted light can be used efficiently.

In order to obtain a sufficient effect of the present invention, the following conditional expression should be satisfied. φ / L ≦ 0.6 (Equation 3) 20 ° ≦ θ ≦ 60 ° (Equation 4) where L is the distance between the electrodes 81 and 82 in the arc tube 10, and φ is the electrode axis 81 in the cylindrical conductors 81b and 82b.
a, 82a are outer diameters of end faces close to the tip, and θ is
c, 82c are angles formed by the electrodes 81, 82.

In Expression 3, when φ / L is larger than the upper limit value, the above-mentioned effects relating to startability, rise time, and arc stability are undesirably reduced. In addition, the amount of light blocked by the cylindrical conductors 81b and 82b increases, which is not preferable. In Equation 4, if θ is smaller than the lower limit, the tips of the cylindrical conductors 81b and 82b are too thin, and the electrodes 81 and 82 are easily deteriorated, which is not preferable. On the other hand, if it is larger than the upper limit value, the above-mentioned effects relating to startability, rise time and arc stability are undesirably reduced. Further, the cylindrical conductors 81b, 82
This is not preferable because the amount of light blocked by b increases.

As described above, according to the configuration of the present invention, the electrode shaft and the cylindrical conductor surrounding the tip of the electrode shaft and having a tapered outer diameter portion on the tip side of the electrode shaft. By using electrodes that are manufactured, they are easy to manufacture, do not induce unstable discharge, have excellent startability and start-up performance at the time of lighting, can efficiently use radiated light, and have a long service life even with a short arc. Discharge lamp with a long length. FIGS. 8A and 8B are configuration examples showing a fifth embodiment of the discharge lamp of the present invention. FIG. 8B is an enlarged sectional view of the electrode portion shown in FIG. 8A.

The discharge lamp 121 is an ultra-high pressure mercury lamp operated by AC. Ultra-high pressure mercury lamps are small in size, have high luminance of a light-emitting portion, and are widely used in projection display devices.
Generally, this type of lamp is mainly used for horizontal lighting. The arc tube 101 has an outer diameter of 12 mm and a maximum thickness of 2.5 m.
m, and molybdenum foils 104, 10 having a width of 2.5 mm and a length of 20 mm are formed on the sealing portions 102, 103.
5 are sealed. The electrodes 106 and 107 made of pure tungsten connected to the molybdenum foils 104 and 105 are opposed to each other at a distance of 1.5 mm in the arc tube 101. In the arc tube 101, 170 mg / cc of mercury;
200 mb of argon gas and a very small amount of bromine are enclosed. Bromine is converted to the electrode 10 by the halogen cycle.
Arc tube 10 made of tungsten evaporated from 6, 107
1 has a function of suppressing the blackening of the inner wall and improving the life of the lamp 121.

By applying an AC voltage of a predetermined frequency to the external conductors 108 and 109 connected to the molybdenum foils 104 and 105, light emission of the mercury 110 can be obtained. The electric power when the lamp 121 is stable is set to 200W. The electrode 106 includes an electrode shaft 106a and a discharge portion 106b having a larger diameter than the electrode shaft 106a. The diameter of the electrode shaft 106a is 0.5 mm. The discharge part 106b has an outer diameter of 1.8.
mm, tip diameter 0.3 mm, core length 2.5 m
m, and the taper angle is 30 °. By disposing a heat radiating conductor such as the coil 112 behind the discharge unit 106b, heat transmitted to the rear of the electrode shaft 106a can be efficiently radiated, so that the electrode shaft 106a can be prevented from being thinned or broken. The electrode 107 has the same configuration.

In the present embodiment, the heat radiating conductor such as the coil 112 is arranged, but the coil 112 may not be provided. The distance between the electrodes 106 and 107 is as short as 1.5 mm, and an extremely high-luminance light emitting portion is formed between the electrodes. Discharge lamp 1 using electrodes 106 and 107
If the light-emitting portion 21 is configured, the light-emitting portion has high brightness, and the electrodes 106, 1
Even if the heat generation at 07 is extremely large, electrode deterioration is suppressed, and the lamp life can be extended. Also, the discharge unit 10
Since the shapes of 6b and 106b are appropriately set, the startability is good, the rise time is short, and the arc stability at the time of lighting is also good. Further, the electrode 1 for the light emitted from the light emitting unit
Since the light-shielding areas of 06 and 107 can be reduced, the emitted light can be used efficiently.

FIG. 9 shows the relationship between the angles of the tapers 106c and 107c and the rise time of the lamp in the discharge lamp shown in FIG. 8, in which the horizontal axis represents the elapsed time after lighting and the vertical axis represents light. Output. The light output on the vertical axis is shown as a relative value when the light output when the power of each lamp is stable is 1.0. The rise time of the discharge lamp of the present invention is greatly reduced as compared with the case where the conventional electrode of FIG. 14 is used. As the angles of the tapers 106c and 107c are larger, the rise time is longer, and
When the angle of 7c is in the range of 20 ° to 60 °, good rising performance can be obtained.

In order to obtain a sufficient effect of the present invention, it is sufficient that the following conditional expression is satisfied. φ / L ≦ 0.6 (Equation 5) 20 ° ≦ θ ≦ 60 ° (Equation 6) where L is the distance between the electrodes in the arc tube, φ is the diameter of the tip of the discharge part, and θ is the taper of the electrode axis. Horns.

As described above, according to the configuration of the present invention, by using an electrode having a discharge portion having a larger diameter than the electrode axis and appropriately setting the shape, the electrode load of an ultra-high pressure mercury lamp or the like can be improved. Even when a large discharge lamp is operated by AC, a discharge lamp with excellent startability and start-up performance, high light utilization efficiency, and a long life even with a short arc does not induce unstable discharge. realizable.

The discharge lamp according to Embodiment 1 or 2
Or, in 5, when the interval between the electrodes is 2 mm or less, the outer diameter of the electrode axis is D1, the outer diameter of the discharge part is D2, and the length of the discharge part in the electrode axis direction is D3, 2.0 ≦ D2 / D1 ≦ 5.0 (Formula 7) It is preferable to satisfy D3 / D1 ≦ 9.0 (Formula 8). In the third or fourth embodiment, the distance between the electrodes is 2 mm or less, and the outer diameter of the electrode shaft is D.
1. Assuming that the outer diameter of the cylindrical conductor is D2 and the length of the cylindrical conductor in the electrode axis direction is D3, 2.0 ≦ D2 / D1 ≦ 5.0 (Equation 9) D3 / D1 ≦ 9.0 ( It is preferable to satisfy Expression 10).

In any case, D1 is approximately determined according to the value of the current flowing through the electrode, so that the shape of the discharge portion can be optimally set according to the current value, and the startability is further improved. . In the first to fourth embodiments,
The discharge medium may contain, for example, a metal halide in addition to mercury and a rare gas.

The discharge lamp may be either DC lighting or AC lighting. When compared with the conventional performance, the AC lighting can obtain a greater effect with respect to the startability and arc stability. In the case of DC lighting, the polarity of the input voltage may be inverted according to the lighting time and the number of times of lighting. For example, if the polarity is inverted every 100 hours of lighting, the deterioration of the electrodes will not be biased to one electrode, so that the symmetry of the light emitting unit is improved and the lamp life is improved.

In the first to fifth embodiments, the tungsten as the electrode material preferably has a lower content of impurities such as potassium, silicon, and aluminum. These impurities react with halogens such as bromine to inhibit the halogen cycle, thereby reducing the lamp life. In addition, if the amount of impurities is large, the melting point of tungsten is lowered, so that the electrode is easily deteriorated. Therefore, it is preferable that these contents are each 10 ppm or less.

An electrode material other than pure tungsten may be used. For example, a material obtained by adding a dopant such as thorium to tungsten may be used in order to improve the startability of the lamp. The heat dissipation conductor is not limited to a coil shape. For example, a cylindrical metal conductor surrounding the electrode shaft may be used. Similarly, the heat dissipation of the electrode shaft can be improved.

The heat radiating conductor and the discharge portion may be in contact or non-contact. If the electrode and the heat dissipation conductor are completely separate, good starting performance can be obtained. The main electrode and the heat dissipation conductor may be made of different materials. For example,
The main electrode is made of pure tungsten with an extremely high melting point, and the discharge conductor is made of tungsten containing a relatively large amount of doping material such as potassium in consideration of the ease of coil formation. In consideration of the above, an optimum one may be selected according to the application.

Although the discharge lamp has been described as a target shape,
The sealing portion and the metal foil may have different lengths, or a pair of electrodes may be arranged in one direction.
FIG. 10 is a configuration example showing the first embodiment of the light source device of the present invention. In FIG. 10, 131 is a lamp, 1
32 is a concave mirror, and 133 is a light source device of the present invention.

The lamp 131 is the same as the discharge lamp shown in FIG. 1A. One of the sealing portions 134 is provided with a base 135 serving as a holding means. The base 135 is fixed by filling a gap with the sealing portion 134 with a heat-resistant adhesive 136. The sealing portion 134 on the side where the base 135 is provided,
It is inserted into the lamp insertion part 137 of the concave mirror 132, filled with a heat resistant adhesive 136 and fixed. The base 135 is preferably made of brass having good thermal conductivity. Further, a ceramic or glass discharge lamp holding member may be used instead of the base. By providing the base 135, the heat capacity and the surface area at the tip are increased, and the rise in temperature due to heat conduction from the arc tube is reduced. Therefore, the metal foil can be shortened, and the entire lamp can be shortened.

As the concave mirror 132, a parabolic mirror or an elliptical mirror is used. On the inner surface of the concave mirror 132, a reflective coating 138 made of a dielectric multilayer film is formed.
The light emitted by 31 is reflected in a predetermined direction at a high reflectance. Since the concave mirror 132 has a large solid angle with respect to the light emitting portion of the lamp 131, there is an advantage that the light collection rate can be increased.

One end of the extension conductor 139 is connected to the external conductor 14.
0, and the other end is a lead wire extraction hole 1 of the concave mirror 132.
41 is taken out of the concave mirror 132. The lamp 131 can be started by applying a predetermined voltage between the extension conductor 139 and the external conductor 142. As described above, since the lamp 131 has good arc stability,
An illumination light flux with less flicker and stable brightness can be obtained.

As lamps, FIGS. 2a, 4a, 7a,
Similar effects can be obtained by using the discharge lamp of the present invention shown in FIG. 8A. As described above, according to the configuration of the present invention, in the light source device in which the discharge lamp and the concave mirror are integrated, by using the discharge lamp of the present invention, it is possible to obtain an illuminating light beam with good startability and stable brightness. A light source device can be realized. FIG. 11 is a configuration example showing a second embodiment of the light source device of the present invention. In FIG. 11, 15
1 is a lamp, 152 is a concave mirror, 153 is a front glass, 1
54 is a light source device of the present invention.

The lamp 151 has the same structure as the discharge lamp shown in FIG. 2A. As the concave mirror 152, an elliptical mirror or a parabolic mirror is used. The lamp 151 has the side on which the base 162 is attached inserted into the lamp insertion portion 163, and the electrode 1
The center of the light emitting portion formed between 55 and 156 is arranged so as to substantially coincide with the first focal point 157 of the concave mirror, and is fixed with the heat resistant adhesive 158.

The front glass 153 is made of Pyrex glass having excellent heat resistance and translucency, and is fixed to the exit side opening of the concave mirror 152 with a silicon-based adhesive 159. The incident surface of the front glass 153 reflects ultraviolet light,
A coating 160 that transmits visible light is provided to prevent harmful ultraviolet light emitted from the lamp 151 from leaking to the outside. By providing the front glass 153 at the opening on the emission side of the concave mirror 152, a substantially closed space is formed inside the concave mirror 152, so that even if the lamp 151 is damaged, fragments thereof scatter outside. As a result, the safety of the light source device 154 is improved.

The inner surface of the concave mirror 152 is provided with a reflective coating 161 formed of a dielectric multilayer film. Here, the light is radiated from the center of the light emitting portion of the lamp 151, specifically, the center between the electrodes 155 and 156,
The light condensing range of the light incident on the second effective reflection surface is α. In the lamp 151, the tips of the electrodes 155, 156 are tapered, so that the radiated light within the focusing range α
No light is blocked by 56. Therefore, lamp 1
There is an advantage that the emitted light of 51 can be used effectively and the light use efficiency is improved.

Since the light collection range α differs depending on the shape of the concave mirror 152, it may be set appropriately so that the taper angle θ of the electrodes 155 and 156 and the diameter φ of the tip end satisfy Expressions 1 and 2. Similar effects can be obtained by using the discharge lamp shown in FIGS. 7A and 8A as the lamp 151. In that case,
To satisfy Equations 3 and 4, or Equations 5 and 6,
What is necessary is just to determine the electrode shape.

As described above, according to the configuration of the present invention, in the light source device in which the discharge lamp and the concave mirror are integrated, by using the discharge lamp of the present invention, the illuminating light flux having good startability and stable brightness is provided. And a light source device with high light use efficiency can be realized. FIG. 12 is a configuration example showing a third embodiment of the light source device of the present invention. In FIG. 12, 170 is a discharge lamp, and 181 is a concave mirror.

In the discharge lamp 170, the sealing portion 171 in which the short metal foil 173 is sealed is inserted into the insertion hole 182 of the concave mirror 181, and the focal position 187 of the concave mirror 181 and the lamp 170 are inserted.
Are adjusted so that the centers between the electrodes 175 and 176 substantially coincide with each other, and are fixed with an adhesive 185. Adhesive 185
, An inorganic heat-resistant adhesive such as Sumiceram is used. The extension conductor 186 has one end connected to the external conductor 1 of the discharge lamp 170.
78, the other end of which is a lead wire extraction hole 1 of the concave mirror 181.
Pull out from 83. An adhesive 185 is filled in a gap between the lead hole 183 and the extension lead 186.

When a predetermined voltage is applied to the extension conductor 186 and the external conductor 177, an arc discharge is generated between the electrodes 175 and 176, and the emission of the mercury 170a serving as a discharge medium and the emission specific to the mercury 170a can be obtained. . The concave mirror 181 has an elliptical surface, the first focal point F1 is 15 mm,
The second focal point F2 (not shown) is 140 mm. In general, an ellipsoid has two elliptical axes (long and short). The length of the major axis and the minor axis can be represented by the following equations, respectively. Length of long axis = f1 + f2 (Equation 11) Length of short axis = 2 × (f1 × f2) ^1/2 (Equation 12) The elliptical axis including the first focus F1 and the second focus F2 is the long axis, The elliptical axis perpendicular to this is the minor axis. The lengths of the major axis and the minor axis of the ellipsoidal mirror in FIG.
7 mm. In the case of an ellipsoidal mirror, if the length of the metal foil 174 is too long, it becomes closer to the second focal point, that is, the focusing position, so that the temperature of the metal foil 174 rises conversely. Therefore, the length of the metal foil 174 is limited to the elliptical lamp insertion portion 18.
The distance from the vertex on the second side to the end of the long metal foil 174 on the concave mirror opening side is set to be equal to or less than １ ／ of the major axis length of the elliptical surface.

The inner surface of the concave mirror 181 is provided with a reflective coating 184 made of a dielectric multilayer film.
The light emitted from between the electrodes 175 and 176 is efficiently reflected in a predetermined direction. The concave mirror is not limited to an ellipsoidal mirror, and a parabolic mirror may be used. However, an ellipsoidal mirror can provide a larger solid angle with respect to the light emitting portion of the lamp, so that the light collection rate can be increased.

According to FIG. 12, since the sealing portion 171 in which the short metal foil 173 of the discharge lamp 170 is sealed is fixed to the insertion hole 182 of the concave mirror 181, the protrusion of the lamp backward from the insertion hole 182 is reduced. In addition, the size of the light source device can be reduced. The sealing portion 171 has sufficient heat capacity and surface area by contacting the concave mirror 181. Therefore, temperature rise due to heat conduction from the arc tube 170 can be suppressed, and even if the short metal foil 173 is sealed, there is no disconnection due to oxidation. On the other hand, since the metal foil 174, which is longer than the metal foil 173 and has a sufficient length, is sealed in the sealing portion 172 on the opening side of the concave mirror, there is no disconnection due to oxidation.

The discharge lamp 170 may have a sealing portion 171 provided with a base or the like. As described above, according to the configuration of the present invention, a highly reliable and compact light source device can be configured by fixing the sealing portion in which the short metal foil of the discharge lamp is sealed to the concave mirror. FIG. 13 is a configuration example showing a fourth embodiment of the light source device of the present invention.
In FIG. 13, reference numeral 191 denotes a front glass as a light-transmitting sealing means, 192 denotes a nitrogen gas, and the other configuration is the same as that of FIG.

The front glass 191 is a Pyrex glass which is excellent in heat resistance and is relatively inexpensive, and is fixed to the opening of the concave mirror 181 on the reflected light emission side by an adhesive 193 such as silicon resin. By providing the front glass 191,
An enclosed space is formed inside the concave mirror 181, so that even if the discharge lamp 170 is broken during operation, the fragments can be prevented from scattering outside.

A reflection coating for removing ultraviolet rays and infrared rays may be applied to at least one of the plane of the front glass 191 on the light incidence side and the light emission side.
This can prevent ultraviolet rays and infrared rays from being emitted to the outside. If at least one of the planes is provided with an anti-reflection coating, the emitted light of the discharge lamp 170 can be efficiently emitted.

A nitrogen gas 192 is sealed in a closed space formed inside the concave mirror 181. For example, the nitrogen gas 192 is filled in the concave mirror 1 after fixing the discharge lamp 170.
81 and the front glass 191 were bonded by nitrogen gas 192.
In a glove box filled with. Instead of the nitrogen gas 192, an inert gas such as an argon gas may be used.

According to FIG. 13, since the enclosed space formed inside the concave mirror 181 is filled with the nitrogen gas 192,
The oxidation of the metal foil 174 on the opening side of the concave mirror 181 can be prevented. The concave mirror 181 may be an ellipsoidal mirror, a parabolic mirror, or the like, but the ellipsoidal mirror can increase the solid angle with respect to the light emitting portion of the lamp, so that the light collection rate can be increased. Further, since the depth of the concave mirror 181 in the optical axis direction can be increased, it is suitable when the front glass 191 is arranged to form a closed structure.

The discharge lamp 170 may be one in which a cap or the like is provided on the sealing portion 171. In the present embodiment, an example is shown in which lamps having different metal foil lengths are used as discharge lamps. However, the above effects can be obtained regardless of the metal foil length. As described above, according to the present invention, by forming a closed space inside concave mirror 181 using front glass 191 and enclosing an inert gas such as nitrogen gas 192 in the closed space, oxidation of metal foil can be achieved. Is prevented, and a highly reliable light source device can be configured. FIG. 14 is a configuration example showing a fifth embodiment of the light source device of the present invention. FIG.
In FIG. 4, reference numeral 201 denotes an argon gas, and the other configuration is the same as the embodiment of FIG.

The difference from the embodiment shown in FIG. 13 is that the enclosed space inside the concave mirror 181 has an argon gas 201 of 30 atm.
Is enclosed. In general, the discharge lamp has a very high pressure inside the arc tube at the time of the lighting operation, and the pressure difference between the discharge lamp and the outside of the arc tube becomes extremely large. According to FIG. 14, the pressure inside the arc tube at the time of the lighting operation of the discharge lamp 170 is about 10 MPa (megapascal). However, since the argon gas 201 of 30 atm is sealed in the closed space, the inside and outside of the arc tube are sealed. And the pressure difference between them is reduced, and the risk of damage to the arc tube is greatly reduced. 13, the argon gas prevents the metal foil 174 from being oxidized, so that the metal foil is not disconnected and the reliability of the light source device is improved.

The concave mirror 181 may be an ellipsoidal mirror, a parabolic mirror, or the like. However, the elliptic mirror can increase the solid-state angle with respect to the light emitting portion of the lamp, so that the light collection rate can be increased. Also,
Since the depth of the concave mirror 181 in the optical axis direction can be increased, it is suitable when the front glass 191 is arranged to form a closed structure. An inert gas such as nitrogen may be sealed at a predetermined pressure instead of the argon gas, and the same effect is obtained. Even if air is sealed at a predetermined pressure, the effect of preventing oxidation is lost, but the risk of damage to the arc tube can be greatly reduced.

The pressure of the gas to be sealed may be at least 1 atm and not more than the pressure in the arc tube when the discharge lamp is turned on. The discharge lamp 170 may be one in which a cap or the like is provided in the sealing portion 171. In the present embodiment, an example is shown in which lamps having different metal foil lengths are used as discharge lamps. However, the above effects can be obtained regardless of the metal foil length.

As described above, according to the present invention, a closed space is formed inside a concave mirror using a front glass, and a gas having a pressure of not less than 1 atm and not more than a pressure in an arc tube at the time of lighting is enclosed in the closed space. Thereby, the rupture of the arc tube is suppressed, and a highly reliable light source device can be configured. FIG. 15 is a configuration example showing a sixth embodiment of the light source device of the present invention. FIG.
, 210 is a discharge lamp, and 221 is a concave mirror.

The discharge lamp 210 is an ultra-high pressure mercury lamp of AC lighting, and the operating pressure during lighting is 10 MPa (megapascal) or more. Therefore, a front glass is provided at the opening of the concave mirror in order to prevent the glass pieces from scattering at the time of breakage. In the discharge lamp 210, the sealing portion 211 in which the short metal foil 213 is sealed is inserted into the insertion hole 222 of the concave mirror 221, and the center between the first focal point 227 of the concave mirror 221 and the electrodes 215 and 216 of the lamp 210 approximately coincides with each other. The position is adjusted as described above and fixed with the adhesive 225. As the adhesive 225, an inorganic heat-resistant adhesive such as Sumiceram is used.

The extension conductor 226 has one end connected to the discharge lamp 21.
0, and the other end is drawn out from the lead hole 223 of the concave mirror 221 to the outside. An adhesive 225 is filled in the gap between the conductor outlet hole 223 and the extension conductor 226. By applying a predetermined voltage to the extension conductor 226 and the external conductor 217, an arc discharge is generated between the electrodes 215 and 216, and the emission of the mercury 210a as the discharge medium and the emission specific to the mercury 210a can be obtained.
The concave mirror is an elliptical mirror, which is used in the third embodiment (FIG. 1).
As in 2), the length of the metal foil 214 is such that the distance from the apex of the elliptical surface on the lamp insertion portion 222 side to the end of the long metal foil 214 on the concave mirror opening side is 1 of the major axis length of the elliptical surface. / 2 or less.

The inner surface of the concave mirror 221 is provided with a reflective coating 224 made of a dielectric multilayer film.
The light emitted from between the electrodes 215 and 216 is efficiently reflected in a predetermined direction. According to FIG.
Since the sealing part 211 in which the short metal foil 213 is sealed is fixed to the insertion hole 222 of the concave mirror 221, the amount of lamp protrusion from the insertion hole 222 to the rear is reduced, and the light source device can be downsized. The sealing part 211 can obtain sufficient heat capacity and surface area by connecting to the concave mirror 221. Therefore, temperature rise due to heat conduction from the arc tube can be suppressed, and even if the short metal foil 213 is sealed, there is no disconnection due to oxidation. On the other hand, the front glass 23 is inserted into the opening of the concave mirror 221.
1 is disposed, the temperature inside the concave mirror 221 is higher than when the front glass 231 is not disposed. Therefore, the temperature rise of the metal foil 214 is large, but the sealing portion 212 on the opening side of the concave mirror has Since the metal foil 214 having a sufficient length than the metal foil 213 is sealed, there is no disconnection due to oxidation.

The concave mirror 221 is not limited to an elliptical mirror, but may be a parabolic mirror. However, an elliptical mirror can increase the solid angle with respect to the light emitting portion of the lamp, so that the light collection rate can be increased. Further, since the depth of the concave mirror 221 in the optical axis direction can be increased, it is suitable for a case where a front glass is arranged to form a closed structure. As in the present embodiment, the metal foil 213 on the lamp insertion part 222 side of the concave mirror 221 is replaced with the metal foil 2 on the opening side.
Making the length shorter than 14 is an extremely effective means for reducing the size of the light source.

The interior of the concave mirror does not need to be completely sealed, and a vent for cooling the discharge lamp or the concave mirror may be provided in the concave mirror or a part of the front glass. The discharge lamp 210 may be one in which a cap or the like is provided on the sealing portion 211. As described above, according to the configuration of the present invention, a highly reliable and compact light source device can be configured by fixing the sealing portion in which the short metal foil of the discharge lamp is sealed to the concave mirror. FIG. 16 is a configuration example showing an embodiment of the projection display device of the present invention. In FIG. 16, 240 is a light source, 241 is a UV-IR cut filter, 242 is a field lens, 243 is a liquid crystal panel,
244 is a projection lens.

The light source 240 is the same as the light source device shown in FIG. 15, and the description of the specific configuration will be omitted. The light emitted from the light source 240 has its UV and IR components removed by the UV-IR cut filter 241, passes through the field lens 242, and then enters the liquid crystal panel 243. The field lens 242 is a liquid crystal panel 243
Is condensed on the projection lens 244. The liquid crystal panel 243 modulates the transmittance of incident light according to the video signal, and forms an optical image on the liquid crystal panel 243. The light transmitted through the liquid crystal panel 243 enters the projection lens 244,
The projection lens 244 enlarges and projects the optical image on the liquid crystal panel 243 onto a screen (not shown).

According to FIG. 16, since the light source device shown in FIG. 15 is used as the light source 240, the reliability of the projection display device is improved and the whole device can be downsized. In the present embodiment, an example in which the light source device shown in FIG. 15 is used as the light source 240 is shown. However, even if the light source device shown in any of FIGS. The effect is obtained. In particular, if the light source device of FIG. 11 is used, the light emitted from the lamp can be more efficiently condensed, so that the brightness of the projection display device can be increased.

An optical element for efficiently or uniformly guiding light emitted from the light source 240 to the liquid crystal panel 243 between the light source 240 and the field lens 242, for example,
You may arrange | position a lens array, a polarization conversion element, etc. Also, an example in which only one transmission type liquid crystal panel using polarized light is used as the spatial light modulation element has been described. For example, a liquid crystal panel using three transmission type liquid crystal panels, a liquid crystal panel using scattering, Alternatively, a spatial light modulator that forms an optical image corresponding to a video signal as a change in diffraction, reflection, or the like may be used. A similar effect can be obtained as long as an optical image is formed by modulating light illuminated by a light source.

Further, a rear projection type display device may be constituted by using a transmission type screen. As mentioned above,
According to the present invention, in a projection display device that illuminates a spatial light modulation element such as a liquid crystal panel with a light source and projects an optical image on the spatial light modulation element, by using the light source device of the present invention as a light source, Thus, a bright projection display device can be configured.

[0103]

According to the discharge lamp of the present invention, the startability, arc stability, and lamp life can be improved even with a short arc. Further, the light source device of the present invention is compact and suitable for use mainly in a projection display device,
It is highly reliable and can efficiently collect the light emitted from the discharge lamp.

Further, by using the light source device of the present invention, a bright, compact, and highly reliable projection display device can be provided.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram showing a first embodiment of a discharge lamp of the present invention, and FIG. 1B is an enlarged view of an electrode structure of the first embodiment.

FIG. 2A is a schematic configuration view showing a second embodiment of the discharge lamp of the present invention, and FIG. 2B is an enlarged view of the electrode structure of the second embodiment.

FIG. 3 is an enlarged view of another electrode structure of the second embodiment.

FIG. 4 (a) is a schematic configuration diagram showing a third embodiment of the discharge lamp of the present invention, and FIG. 4 (b) is an enlarged view of the electrode structure of the third embodiment.

FIG. 5 is an enlarged view of another electrode structure of the third embodiment.

FIG. 6 is an enlarged view of still another electrode structure of the third embodiment.

FIG. 7A is a schematic configuration diagram showing a fourth embodiment of the discharge lamp of the present invention, and FIG. 7B is an enlarged view of the electrode structure of the fourth embodiment.

FIG. 8A is a schematic configuration diagram showing a fifth embodiment of the discharge lamp of the present invention, and FIG. 8B is an enlarged view of the electrode structure of the fifth embodiment.

FIG. 9 is a characteristic diagram showing a relationship between a taper angle and a rise time.

FIG. 10 is a schematic configuration diagram showing a first embodiment of the light source device of the present invention.

FIG. 11 is a schematic configuration diagram showing a second embodiment of the light source device of the present invention.

FIG. 12 is a schematic configuration diagram showing a third embodiment of the light source device of the present invention.

FIG. 13 is a schematic configuration diagram showing a fourth embodiment of the light source device of the present invention.

FIG. 14 is a schematic configuration diagram showing a fifth embodiment of the light source device of the present invention.

FIG. 15 is a schematic configuration diagram showing a sixth embodiment of the light source device of the present invention.

FIG. 16 is a schematic configuration diagram showing an embodiment of a projection display device of the present invention.

FIG. 17 is a schematic configuration diagram showing a configuration of a conventional discharge lamp.

FIG. 18 is a schematic configuration diagram showing an electrode structure of a conventional discharge lamp.

FIG. 19 is a schematic diagram showing another electrode structure of a conventional discharge lamp.

FIG. 20 is a schematic configuration diagram showing still another electrode structure of a conventional discharge lamp.

21A is a schematic configuration diagram showing a configuration of a conventional light source device, and FIG. 21B is an enlarged cross-sectional view of a cross section A in FIG. 21A.

[Description of Signs] 10, 101, 170 Arc tube 11, 12, 102, 103, 134, 171, 17
2, 211, 212 Sealing part 13, 14, 173, 174, 213, 214 Metal foil 15, 16, 41, 42, 45, 61, 62, 66, 8
1, 82, 106, 107, 155, 156, 175,
176, 215, 216 electrodes 15a, 16a, 41a, 42a, 61a, 62a, 6
6a, 68a, 81a, 82a, 106a Electrode axis 15b, 16b, 41b, 42b, 45b, 106b
Discharge unit 17, 18, 65, 85, 112 Heat dissipation conductor 19, 20, 108, 140, 142, 177, 17
8, 217, 218 Outer conductors 21, 22 Discharge medium 31, 51, 71, 91, 121, 170, 210 Discharge lamps 41c, 42c, 45c, 81c, 82c, 106c,
107c Taper 61b, 62b, 66b, 68b, 81b, 82b Cylindrical conductor 67 Taper 132, 152, 181, 221 Concave mirror 135, 162 Holding means 137, 163, 182, 222 Lamp insertion part 153, 191, 231 Translucent sealing Means 243 Spatial light modulation element

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Toshiaki Ogura 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (38)

[Claims] An arc tube, sealing portions formed at both ends of the arc tube, a pair of electrodes sealed to the sealing portion, and disposed opposite to each other at a predetermined interval in the arc tube; A discharge medium having a discharge medium sealed in an arc tube, wherein the electrode has an electrode shaft and a discharge portion having a larger outer diameter than the electrode shaft integrally formed at a tip of the electrode shaft. And a heat radiating conductor surrounding the electrode axis behind the discharge portion. 2. An arc tube, sealing portions formed at both ends of the arc tube, a pair of electrodes sealed to the sealing portion, and disposed opposite to each other at a predetermined interval in the arc tube, A discharge medium having a discharge medium sealed in an arc tube, wherein the electrode has an electrode shaft and a discharge portion having a larger outer diameter than the electrode shaft integrally formed at a tip of the electrode shaft. And a discharge portion having a tapered tip, a heat-dissipating conductor surrounding the electrode axis behind the discharge portion, a distance between the electrodes in the arc tube being L, and a tip of the discharge portion. Is a diameter of φ and θ is an angle formed by the taper with the electrode axis, φ / L ≦ 0.620 ° ≦ θ ≦ 60 °. 3. An arc tube, a sealing portion formed at both ends of the arc tube, a pair of electrodes sealed to the sealing portion and opposed to each other at a predetermined interval in the arc tube, A discharge medium enclosed in an arc tube, wherein the electrode comprises: an electrode shaft; and a cylindrical conductor fitted into a tip end of the electrode shaft. A discharge conductor surrounding the electrode axis behind the discharge lamp. 4. An arc tube, sealing portions formed at both ends of the arc tube, and a pair of electrodes sealed to the sealing portion and arranged at predetermined intervals inside the arc tube, A discharge medium sealed in an arc tube, wherein the electrode is fitted into an electrode shaft and a tip end of the electrode shaft, and an outer peripheral portion on a tip side of the electrode shaft is tapered. A cylindrical conductor formed, a heat-radiating conductor surrounding the electrode axis behind the cylindrical conductor, a distance L between the electrodes in the arc tube, and a tip of the electrode axis in the cylindrical conductor. The outer diameter of the near end face is φ,
A discharge lamp characterized by satisfying φ / L ≦ 0.620 ° ≦ θ ≦ 60 °, where θ is an angle formed by the taper with the electrode axis. 5. An arc tube, a sealing portion formed at both ends of the arc tube, a pair of electrodes sealed to the sealing portion, and opposed to each other at a predetermined interval in the arc tube, A discharge lamp including mercury and a rare gas sealed in an arc tube, wherein the amount of the mercury is 150 mg / cc or more, and the electrode is integrated with an electrode shaft and a tip of the electrode shaft. A discharge portion having a larger outer diameter than the electrode axis formed in the discharge portion, the discharge portion has a tapered tip, and has a heat dissipation conductor surrounding the electrode axis behind the discharge portion, When the distance between the electrodes in the arc tube is L, the diameter of the tip of the discharge portion is φ, and the angle between the taper and the electrode axis is θ, φ / L ≦ 0.620 ° ≦ θ ≦ 60 ° is satisfied. And discharging the electrode by applying an AC voltage to the electrode. . 6. The discharge lamp according to claim 3, wherein the electrode comprises only the electrode shaft and a cylindrical conductor fitted to a tip of the electrode shaft. 7. The discharge according to claim 5, wherein the electrode comprises only the electrode shaft and a discharge portion formed at the tip of the electrode shaft and having a larger outer diameter than the electrode shaft. lamp. 8. The discharge lamp according to claim 3, wherein the cylindrical conductor is provided with a taper at an inner end farther from the tip of the electrode shaft. 9. The discharge lamp according to claim 1, wherein the heat radiating conductor has a coil shape. 10. The discharge lamp according to claim 1, wherein the electrodes and the heat radiation conductor are made of different materials. 11. The discharge lamp according to claim 1, wherein the electrode is made of tungsten doped with thorium. 12. If the distance between the electrodes is 2 mm or less, the outer diameter of the electrode axis is D1, the outer diameter of the discharge part is D2, and the length of the discharge part in the electrode axis direction is D3, 2.0 ≦ 2.0. The discharge lamp according to claim 1, wherein D2 / D1 ≦ 5.0 D3 / D1 ≦ 9.0 is satisfied. 13. The electrode spacing is 2 mm or less, the outer diameter of the electrode shaft is D1, the outer diameter of the cylindrical conductor is D2, and the length of the cylindrical conductor in the electrode axis direction is D3. 7. The discharge lamp according to claim 3, wherein 0 ≦ D2 / D1 ≦ 5.0 D3 / D1 ≦ 9.0 is satisfied. 14. The discharge lamp according to claim 1, wherein the discharge medium is mercury and a rare gas. 15. The discharge lamp according to claim 1, wherein the electrode is lit by applying an AC voltage to the electrode. 16. The discharge lamp according to claim 1, wherein a direct current voltage is applied to the electrode to light the electrode, and the polarity of the voltage is inverted according to a driving time or the number of times of lighting. 17. The discharge lamp according to claim 1, wherein the electrode is made of pure tungsten. 18. The electrode according to claim 1, wherein the content of at least one of potassium, silicon, and aluminum is 10 pp.
The discharge lamp according to any one of claims 1 to 7, wherein the discharge lamp is made of pure tungsten of m or less. 19. An arc tube forming a discharge space, sealing portions formed at both ends of the arc tube, metal foils respectively sealed in the sealing portions, and one end connected to the metal foil. And an electrode having the other end disposed opposite the inside of the arc tube, an external conductor having one end connected to the metal foil and the other end protruding outside the sealing portion, and sealed in the arc tube. A discharge medium, wherein the metal foils have different lengths. 20. The discharge lamp according to claim 19, wherein the discharge medium contains an inert gas and mercury. 21. The discharge lamp according to claim 19, wherein the arc tube is made of quartz glass or sapphire glass. 22. The discharge lamp according to claim 19, wherein a holding means is provided in a sealing portion in which the metal foil having a short length is sealed. 23. The discharge lamp according to claim 22, wherein the holding means is made of metal. 24. A light source device comprising: the discharge lamp according to claim 1; and a concave mirror that reflects light emitted from the discharge lamp in a predetermined direction. 25. The discharge lamp according to claim 1, further comprising: a concave mirror that reflects light emitted from the discharge lamp in a predetermined direction, wherein the concave mirror has an opening through which reflected light is emitted. And a lamp insertion part provided on the opposite side of the opening part. The discharge lamp has one end inserted into the lamp insertion part, and the center of a light emitting region formed between a pair of electrodes is the concave mirror. The light source device is arranged so as to be substantially coincident with the focal point on the shorter side of the light source, and does not block light rays emitted from the center of the light emitting region and incident on the effective reflection surface of the concave mirror by the electrodes of the discharge lamp. 26. The discharge lamp according to claim 19, further comprising a concave mirror configured to reflect light emitted from the discharge lamp from a predetermined direction, wherein the discharge lamp is provided with a metal foil having a short length. A light source device, wherein a sealing portion is fixed to the concave mirror. 27. A discharge lamp, comprising: a concave mirror that reflects light emitted from the discharge lamp in a predetermined direction; wherein the discharge lamp is sealed in sealing portions provided at both ends of an arc tube. The concave mirror has an opening through which reflected light is emitted, and a lamp insertion portion provided on the opposite side of the opening, and the discharge lamp has a short metal foil. Inserting the sealed portion sealed into the lamp insertion portion, is arranged so that the center of the light emitting region formed in the arc tube approximately coincides with the focal point on the short side of the concave mirror. Light source device. 28. A discharge lamp, a concave mirror for reflecting light radiated from the discharge lamp in a predetermined direction, and disposed in an opening on the reflected light emission side of the concave mirror to form an enclosed space inside the concave mirror. A light source device comprising: a light-transmitting sealing means for forming; and an inert gas sealed in the sealed space. 29. A discharge lamp; a concave mirror for reflecting light emitted from the discharge lamp in a predetermined direction; and a concave mirror disposed in an opening of the concave mirror on a reflection light emission side to form an enclosed space inside the concave mirror. A light-transmitting sealing means for forming the light source device, wherein a gas is sealed in the sealed space at a pressure higher than 1 atm and lower than the operating pressure of the discharge lamp. 30. Operating pressure of 10 MPa (megapascal)
The discharge lamp, a concave mirror that reflects light emitted from the discharge lamp in a predetermined direction, and a translucent sealing unit, wherein the discharge lamp is provided at both ends of an arc tube. The length of the metal foil sealed in the portion is different, the concave mirror has an opening through which reflected light is emitted, and a lamp insertion portion provided on the opposite side of the opening, and the discharge lamp has a length Inserting a sealing portion in which a short metal foil is sealed into the lamp insertion portion, and disposing the sealing portion so that the center of the light emitting region formed in the arc tube approximately matches the focal point on the short side of the concave mirror. The light source device, wherein the sealing means is disposed in the opening of the concave mirror. 31. The light source device according to claim 28, wherein the translucent sealing means is made of Pyrex glass. 32. The light source device according to claim 28, wherein the transparent sealing means is provided with a coating for reflecting at least one of infrared rays and ultraviolet rays. 33. The light source device according to claim 28, wherein the translucent sealing means is provided with an antireflection coating for preventing reflection of incident light. 34. The discharge lamp according to claim 19, wherein the sealing portion in which the short metal foil is sealed is fixed to the concave mirror.
The light source device according to any one of the preceding claims. 35. The light source device according to claim 28, wherein the concave mirror is an elliptical mirror. 36. The discharge lamp has an operating pressure of 10 MPa.
(Megapascal) or more.
30. The light source device according to 8 or 29. 37. The concave mirror is an elliptical mirror, and a distance from a vertex of the elliptical surface on the lamp insertion portion side to an end of the long metal foil on the concave mirror opening side is not more than の of a major axis length of the elliptical surface. 31. The light source device according to claim 27, wherein the light source device is provided. 38. A light source, a spatial light modulator illuminated by the light source and forming an optical image in accordance with a video signal, and a projection means for projecting the optical image formed on the spatial light modulator on a screen 31. A projection display device comprising: the light source device according to claim 19;