JPH08124531A - Short arc type electric discharge lamp, light source device, projector device and liquid crystal projector device - Google Patents

Abstract

PURPOSE: To provide a short arc type electric discharge lamp, a light source device, a projector device and a liquid crystal projector device hardly generating an illuminance difference on an irradiated surface. CONSTITUTION: A light diffusion section 28 is formed on the outer surface of a wall forming the discharge space of a light emitting tube 20, and a transparent section 29 is formed between a thermal insulation film 27 and the section 28. In this case, the section 28 is formed to have light diffusivity capable of a continuous change in sequence along a lamp axis 01-01, so that a light diffusion coefficient becomes O1 at a boundary with the section 29, giving a small value, and a light diffusion coefficient QI becomes larger at a position nearer the top of a reflector 2 (i.e., small linear transmission factor). As a result, a section having an extreme difference in light transmission factor is not formed on an internal space wall.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short arc discharge lamp, a light source device, a light projecting device and a liquid crystal projector device.

[0002]

2. Description of the Related Art A color liquid crystal projector device uses a metal halide lamp as a light source, which has a higher light output than a light bulb and is excellent in luminous efficiency and color rendering. In this case, an optical system such as a reflector that reflects the light emitted from the metal halide lamp and a lens that controls this reflected light performs light control such as focusing and projection, and the light controlled by this optical system. In response to this, the image on the liquid crystal panel is projected on the screen. As a light source for such a color liquid crystal projector device,
There is a short arc metal halide lamp described in Japanese Patent Laid-Open No. 4118849/1992 shown in FIG.

This is designed to equalize the illuminance distribution of the screen to be irradiated, and the clear portion 101, the frosted portion 102, and the heat insulating film portion are formed on the wall surface forming the internal space of the arc tube 100. 103 is formed. In this publication, the frosted portion 1 is partially formed on the arc tube 100.
By forming 02 and leaving the clear portion 101, the arc tube 1
It is described that a desired illuminance can be obtained by suppressing a decrease in the illuminance of the entire screen when the light from 00 is applied to the screen.

[0004]

However, in this case, there is a clear boundary between the clear portion 101 and the frosted portion 102. Therefore, the conventional lamp has a problem that when the screen is irradiated with the light from the arc tube 100, a step of illuminance is likely to occur on the screen at a portion corresponding to the boundary. This illuminance step becomes larger as the light diffusivity of the frosted portion becomes higher. When this illuminance difference occurs, a ring-shaped stripe is formed on the irradiation surface, which hinders visual recognition of images and the like.

The present invention has been made in consideration of the conventional problems, and an object thereof is to provide a short arc discharge lamp, a light source device, a light projecting device, and a liquid crystal projector device in which an illuminance difference on an irradiation surface is unlikely to occur. Is.

[0006]

According to a first aspect of the present invention, there is provided an arc tube having an internal space, a discharge medium sealed in the internal space, and a pair of electrodes sealed so as to discharge in the internal space. A light diffusing section formed on the arc tube wall by changing the degree of diffusion,
It is a short arc discharge lamp characterized by comprising:

The discharge medium contains a rare gas, mercury, and a metal halide. By applying a voltage between the electrodes,
A medium in which an electric discharge can be formed.

The short arc discharge lamp means a lamp having an electrode distance of 20 mm or less.

The light diffusing portion includes not only those formed on the inner space side surface of the wall portion, the outer surface and the member of the wall portion, but also those attached to the wall portion in the form of a film or the like.

According to a second aspect of the present invention, an arc tube having an internal space, a discharge medium is enclosed in the internal space, and a pair of electrodes sealed so as to be dischargeable in the internal space, and an internal space of the arc tube are formed. The second light diffusion portion, which is formed adjacent to the first light diffusion portion of the wall portion forming the internal space of the arc tube and has a light diffusion rate lower than that of the first light diffusion portion And a transparent portion formed adjacent to a second light diffusing portion of a wall portion that forms an internal space of the arc tube.

It is preferable that there is no clear boundary between the first light diffusion portion and the second light diffusion portion.

In this case, the light diffusivity of the light diffusing section in the present invention is the average value of the light diffusivity for convenience. Further, the light diffusivity is defined by the percentage of the incident light that is emitted in the incident direction when linear light is incident on an object that transmits light. That is, when light is incident on the transparent glass at a right angle, the light diffusivity is zero.

According to a third aspect of the present invention, an arc tube having an internal space, a discharge medium is enclosed in the internal space, and a pair of electrodes sealed so as to be dischargeable in the internal space, and an internal space of the arc tube are formed. A transparent portion formed on the wall portion, and a light diffusion portion formed adjacent to the transparent portion of the wall portion forming the internal space of the arc tube and having a high light diffusion rate in a direction away from the transparent portion. Is a short arc discharge lamp.

According to a fourth aspect of the present invention, the arc tube is made of quartz, and the light diffusing portion is a fine uneven surface formed on the surface of the arc tube. It is a short arc discharge lamp.

According to a fifth aspect of the present invention, the arc tube is made of transparent ceramics, and the transparent portion and the portion of the light diffusing section having a low light diffusivity form a smooth surface of the arc tube. A short arc discharge lamp according to any one of claims 1 to 3.

According to a sixth aspect of the present invention, there is provided a short arc discharge lamp according to any one of the first to fifth aspects, a top part and a closed part, the discharge lamp is provided, and light output by discharge of the discharge lamp is provided. And a reflector that reflects the light and outputs the light from the closing portion.

According to a seventh aspect of the present invention, there is provided a short arc discharge lamp according to any one of the first to fifth aspects, a top portion and a closed portion, and a portion of the light diffusion portion having a high light diffusion rate has a low light diffusion rate. The discharge lamp is arranged so as to be located on the top side of the portion, and a reflector for reflecting the light output by the discharge of the discharge lamp and outputting the light from the closed portion is provided. It is a light source device.

An eighth aspect of the present invention includes the light source device according to the sixth or seventh aspect, a power source for stably lighting a discharge lamp of the light source device, and a housing for housing the light source device and the power source. It is a light projecting device characterized in that

According to a ninth aspect of the present invention, there is provided a light source device according to the sixth or seventh aspect, a power source for stably lighting a discharge lamp of the light source device, and a liquid crystal panel for making light output from the light source device incident and controlling the light source device. A liquid crystal projector device comprising: a light source device; a power supply; and a housing that houses a liquid crystal panel.

[0020]

According to the first aspect, since the degree of light diffusion of the light diffusing portion is changed, it is possible to eliminate a portion having extremely different light transmittance on the wall forming the internal space. Therefore,
For example, when the output light of the discharge lamp is applied to the irradiation surface, it becomes difficult for an extreme difference in illuminance, which has conventionally occurred, to occur.

According to the second aspect, since the second light diffusing section having a light diffusivity lower than that of the first light diffusing section is formed between the transparent section and the first light diffusing section, the internal space is formed. It is possible to eliminate a portion on the wall where the light transmittance is extremely different. Therefore, for example, when the output light of the discharge lamp is applied to the irradiation surface, it is difficult for the extreme step of illuminance, which has been conventionally generated, to occur.

According to the third aspect, since the light diffusing portion having a high light diffusing rate is formed in the direction away from the transparent portion, it is possible to eliminate a portion having an extremely different light transmitting rate on the wall forming the internal space. it can. Therefore, for example, when the output light of the discharge lamp is applied to the irradiation surface, it is difficult for the extreme step of illuminance, which has been conventionally generated, to occur.

According to the fourth aspect, in addition to having the effect according to any one of the first to third aspects, and since the light diffusing portion is a fine uneven surface, it is not necessary to provide light diffusing pus or the like.

According to Claim 5, the surface of the translucent ceramic having the function of any one of Claims 1 to 3 and a high light diffusion coefficient is polished to form the transparent portion and the light diffusion portion. Therefore, it is not necessary to provide a light diffusion film or the like.

According to the sixth aspect, there is provided the operation according to any one of the first to fifth aspects.

According to the seventh aspect, there is provided the operation according to any one of the first to fifth aspects. In addition, if the reflector is spheroidal or paraboloidal in shape and the arc of the discharge lamp is located at the approximate focus position of the reflector, the reflected light from the reflector has a reflection expected angle that increases from the top to the closed part. growing. That is, the reflected light at the top has a high illuminance on the irradiation surface, and the reflected light at the closed portion has a low illuminance on the irradiation surface. According to claim 7, since the discharge lamp is arranged in the reflector so that a portion having a high light diffusivity of the light diffusing portion is located closer to the top side than a portion having a low light diffusivity, the top portion of the reflector is separated from the discharge lamp. The light going to is significantly diffused and reflected by the reflector. Further, of the reflecting surface of the reflector, the light from the discharge lamp toward the reflector is reflected by the reflector without being diffused as it goes from the top to the closed portion.

Therefore, the reflected light in the vicinity of the top of the reflector is diffused to reduce the illuminance on the irradiation surface, and the reflected light on the closed portion side of the reflector is hardly diffused. It is possible to improve the uniformity of illuminance.

According to the eighth aspect, there is provided the operation according to any one of the sixth to seventh aspects.

According to the ninth aspect, there is provided the operation according to any one of the sixth to seventh aspects.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in FIGS.

FIG. 1 is a partially sectional front view showing a light source device 50 used in a color liquid crystal projector device. The light source device 50 includes a light source 1 and a reflector 2 that reflects light emitted from the light source. As the short arc discharge lamp 1, for example, an AC lighting type short arc metal halide lamp with a rated input of 250 W is used. Used.

The discharge lamp 1 will be described with reference to FIG. 1 and FIG. 2 showing the details of the arc tube. In the figure, reference numeral 20 denotes an arc tube made of quartz glass. The light emitting portion of the arc tube 20 is made of quartz glass having an inner thickness of 1.4 mm, and has a spheroidal shape with a major axis of about 15 mm and a minor axis of about 11 mm. The internal surface area is approximately 4.7 cm 2, and the internal volume is approximately 0.9 CC.

Electrodes 2 are provided on both ends of the arc tube 20, respectively.
1, 21 are sealed. The electrode 21 is an electrode coil 2 made of a tungsten alloy containing 0.7 mm thorium at the tip of an electrode shaft 211 made of 0.7 tungsten.
It is configured by winding a plurality of windings 12. These electrodes 21,
The electrode-to-electrode distance L of 21 is 6.0 mm.

The electrodes 21 and 21 are connected to the sealing portions 22 and 2 respectively.
It is connected to the metal foil conductors 23, 23 sealed in 2. The metal foil conductors 23, 23 are Mo foil and have a width of 3 m.
m and the thickness is 30 μm.

One metal foil conductor 23 connected to one electrode 21 is electrically connected to a base 24 connected to the end of the sealing portion 22 via an external lead wire, and the other electrode is also connected. The other metal foil conductor 23 connected to 21 is connected to the external lead wire 25.

The outer lead wire 25 is made of a metal wire having a diameter of 0.8 mm.

22 mg of mercury is filled as a buffer metal in the arc tube 20 and a rare earth metal such as Dy, Nd, T1, ln, S is used as a light emitting metal.
2.0 mg of iodide and bromide such as n, Cs, etc. are enclosed, and argon gas of 40 k is used as a rare gas.
Pa is included.

The discharge lamp 1 is attached to the reflector 2. The reflector 2 is made of glass or metal, and a reflecting surface 31 made of a vapor-deposited film such as Ti02-Si02 is formed on the inner surface of the rotating curved surface having the focal point F.

This reflector 2 is used in a posture in which the optical axis 02-02 is substantially horizontal, and the front light projecting portion on one end side, that is, the opening is formed with an opening diameter of about 90 to 130 mm. A lamp support tube portion 32 is formed on the top of the reflector 2. The base 25 portion of the discharge lamp 1 is fixed to the support cylindrical portion 32 with an adhesive 33 such as insulating cement.

As a result, the discharge lamp 1 has the lamp shaft 0
1-01 is the central axis of the reflector 2, that is, the optical axis 02-10
The discharge lamp 1 is housed in the reflector 2 so as to be substantially coincident with 2, and the discharge lamp 1 is lit substantially horizontally.

The discharge lamp 1 has a pair of electrodes 21, 21.
Should be arranged so that the middle part of the above-mentioned is almost coincident with the focal position F of the reflector 2.

An introduction hole 34 is formed in the reflector 2, and the external lead wire 25 of the discharge lamp 1 penetrates through the introduction hole 34 and is guided to the back side.

In the discharge lamp 1, the base 24 and the external lead wire 25 are connected to a high frequency power source 60. The high frequency power supply 60 is adapted to apply a voltage, for example, of a no-load voltage of about 280V to the discharge lamp 1. By applying such a voltage, the lamp is lit by alternating current, the lamp current becomes 2.9 A, the lamp voltage is 85 V, and the lamp power is 250 W.

In such a discharge lamp 1, a heat insulating film 27 is formed on the outer surface of the arc tube 20 so as to surround the other electrode 21 located on the opening side of the reflector 2. The heat-retaining film 27 is formed by dissolving fine powder such as aluminum oxide in a solvent and vaporizing the solvent after coating, and depositing the heat-retaining film 27 on the reflector 2 beyond the focus position F, that is, the maximum outer diameter portion of the arc tube 20. It covers the discharge space located on the opening side.

A light diffusing portion 28 is formed on the outer surface of the wall forming the discharge space of the arc tube 20. The light diffusing section 28 is formed up to the end of the discharge space facing the top side of the reflector 2 with a gap from the heat retaining film 27. A transparent portion 29 is formed between the heat retaining film 27 and the light diffusion portion 28. As shown in FIG. 2, the light diffusing unit 28 of the present embodiment is formed of a finely textured surface having a satin finish by sandblasting. The light diffusing section 28 diffuses and transmits the light emitted from the arc tube 20. In this case, the light diffusing section 28 has a light diffusing rate α1 on the boundary side with the transparent section 29, and a light diffusing rate α1. Is small (the linear transmittance is high), and the light diffusivity α1 increases (the linear transmittance decreases) as it approaches the top side of the reflector 2, so that the light diffusivity is reduced along the lamp axis 01-101. It is formed so as to change sequentially and continuously.

Therefore, if the light diffusing portion is equally divided into the transparent portion 29 side portion and the reflector 2 top portion, the top portion has a higher average light diffusivity than the transparent portion 29 side. ing.

In this case, the portion on the top side is the first light diffusing portion and the portion on the transparent portion 29 side is the second light diffusing portion.

The light source device 50 having such a structure is used for a light projecting device such as a color liquid crystal projector device.
The structure of the liquid crystal projector device will be described with reference to FIG.

A light source device 50 comprising the discharge lamp 1 and a reflector 2 for reflecting the light emitted from the discharge lamp 1.
An optical system 3 for controlling the projected light is provided in front of the optical system 3. The optical system 3 includes, for example, a liquid crystal panel 4 and the like. And a screen 6 is provided in front of the optical system 3.
Is provided. Reference numeral 7 denotes a housing, which houses the optical system 3, the power source 60, and the light source device 50.

The light emitted from the discharge lamp 1 is reflected by the reflecting surface 31 of the reflector 2, and the liquid crystal panel 5 of the optical system 3 is reflected.
The liquid crystal panel 4 is illuminated from the rear side of the screen, and this irradiation light is projected onto the screen 6. Therefore, the image of the liquid crystal panel is projected on the screen 6.

Now, the results of comparing the illuminance distribution on the screen 6 with those of the present invention will be described.
FIG. 4 is a front view showing each position of the screen 6, in which a scale of 0 to 10 is equally divided on the diagonal line of the screen 6.

The illuminance of the screen 6 shown in FIG. 4 was measured using the color liquid crystal projector shown in FIG. 3, and the result is shown in FIG. 5 showing the illuminance distribution.

In FIG. 5, the characteristic B is a case where a transparent arc tube is used without light diffusion treatment on the surface of the arc tube 20. When the arc tube is transparent as described above, the illuminance is large in the central portion of the screen and the illuminance is extremely low in the peripheral portion, and the illuminance imbalance is conspicuous in the entire screen, resulting in uneven illuminance.

In FIG. 5, characteristic C is an example in which uniform light diffusion portions are formed on the entire surface of the arc tube 20. The light diffusivity in this case is the same as the light diffusivity α2 in FIG. In this way, when the light diffusing portion having the light diffusing rate α2 is formed over the entire area, the light emitted from the vicinity of the focal point F is diffused, so that the linear transmittance is reduced and the light amount of the parallel light rays is reduced. More light goes out of the screen, and the illuminance around the screen is reduced. Further, some light is diffused from the back side of the arc tube 20 to the top of the reflector 2. However, the diffused light in this portion spreads from the top of the reflector 2 to the front surface of the reflector 2 and is reflected. Therefore, although the light traveling toward the center of the screen is reduced, the reduction of the amount of light at the peripheral portion of the screen is suppressed. As a result, the amount of light traveling from the front closed portion of the reflector 2 toward the screen 6 is suppressed so much that it is reduced in the peripheral portion. Therefore, as shown by the characteristic C,
In the screen 6, the illuminance is reduced in the central part and is not extremely reduced in the peripheral part, so that the imbalance of the illuminance is corrected in the entire screen C, and the illuminance becomes uniform as a whole.

However, in this case, since the light quantity of the parallel rays is reduced, the light quantity is reduced over the entire surface of the screen 6, and the illuminance of the whole is lowered.

Further, when a light diffusing section is provided on the surface of the reflector of the arc tube 20 and a transparent section is provided on the closing side of the reflector, as in the characteristic D, there is a difference in illuminance between the peripheral section and the central section. Will occur.

On the other hand, in the case of the present invention, the characteristic A is obtained. In the case of the aforesaid example, the linear transmittance is high on the surface of the arc tube 20 in the vicinity of the focus position F, and subsequently the light diffusion rate α1 is close to transparent, and therefore the focus is similar to the case of the characteristic B. The light emitted from the vicinity of the position F is the screen 6
It becomes brighter than the characteristic C in the peripheral portion of. And arc tube 2
The light traveling from the back side of 0 to the top of the reflector 2 is diffused by the light diffusing portion having a large light diffusivity α2, and thus, like the case of the characteristic C, this diffused light is reflected toward the spreading C. . Therefore, the amount of light traveling from the front closed portion of the reflector 2 toward the screen 6 is suppressed from decreasing in the peripheral portion.

As a result, as shown by the characteristic A, the illuminance is high in the central portion of the screen 6 and the illuminance is small in the peripheral portion, so that the unevenness of the brightness of the entire screen 6 is corrected as compared with the characteristic B. And become uniform as a whole. Moreover. In this case, since the amount of parallel rays is large, the amount of light is large over the entire surface of the screen 6, and compared with the characteristic C, the entire illuminance is the same. Further, as compared with the characteristic D, an extreme level difference in illuminance does not occur.

Therefore, in the structure of this embodiment, the illuminance balance of the screen 6 is improved as compared with the characteristics B, C and D.

Therefore, the color liquid crystal projector device using the light source device 50 can improve the uniformity of the illuminance on the screen 6 without dropping the light and increase the average illuminance of the entire screen.

In the case of the above embodiment, the light diffusing section 28
Was formed by a fine uneven surface by blasting, the present invention is not limited thereto, when the frosting or arc tube to which transparent fine particles such as quartz are adhered is made of transparent ceramics, Generally, the surface of the wall is rough because it is fired and molded, but the surface of the arc tube is mechanically shaved or chemically etched to be processed smoothly to produce a transparent part and a light diffusion with a low light diffusion rate. By forming the portion, the same effect as in the above embodiment can be obtained.

Further, the present invention is not limited to the metal halide lamp that is lit by AC, but can be implemented by a discharge lamp of DC lighting type.

Further, although the discharge lamps of the above-mentioned examples are halides of the rare family belonging to which the quality of light emission includes scandium Sc, they are alkali metal halides typified by sodium Na and lithium Li. Good.

Furthermore, the reflector 2 is. The present invention is not limited to the paraboloid of revolution or the ellipsoid of revolution, and can be implemented by a reflector that reflects light in a desired direction.

Further, the heat retaining film 27 may or may not be provided.

Furthermore, the center between the electrodes, which is the emission center of the discharge lamp 1, is not limited to being set at the focal position of the reflector 2. The focal position with the reflector may be close to or close to either electrode.

[0067]

According to the first aspect of the present invention, since the degree of light diffusion of the light diffusing portion is changed, it is possible to eliminate a portion having extremely different light transmittance on the wall forming the internal space. Therefore, for example, when the output surface of the discharge lamp is irradiated with the output light, it is difficult for the extreme step of the illuminance, which has been conventionally generated, to occur.

According to the second aspect, since the second light diffusing portion having a light diffusivity lower than that of the first light diffusing portion is formed between the transparent portion and the first light diffusing portion, the wall forming the internal space is formed. Therefore, it is possible to eliminate a portion where the light transmittance is extremely different. Therefore, for example, when the output light of the discharge lamp is applied to the irradiation surface, it is difficult to cause the extreme step of the illuminance that has been conventionally generated.

According to the third aspect, since the light diffusing portion having a high light diffusing rate in the direction away from the transparent portion is formed, it is possible to eliminate a portion having an extremely different light transmitting rate on the wall forming the internal space. it can. Therefore, for example, when the output light of the discharge lamp is applied to the irradiation surface, it is difficult for the extreme step of illuminance, which has been conventionally generated, to occur.

According to the fourth aspect, in addition to the effect according to any one of the first to third aspects, and since the light diffusing portion is a fine uneven surface, it is not necessary to separately provide a light diffusing film.

According to a fifth aspect of the present invention, in addition to the effect according to any one of the first to third aspects, the surface of the transparent ceramic having a high light diffusivity is smoothed to form the transparent portion and the light diffusing portion. Since it is formed, it is not necessary to separately provide a light diffusion film or the like.

According to the sixth aspect, there is the effect according to any one of the first to fifth aspects.

According to the seventh aspect, there is the effect according to any one of the first to fifth aspects. In addition, since the reflector is spheroidal or paraboloidal in shape, and the arc of the discharge lamp is located at the approximate focus position of the reflector, the reflected light at the reflector has an expected reflection angle from the top toward the closed portion. growing. That is, the reflected light at the top has a high illuminance on the irradiation surface, and the reflected light at the closed portion has a low illuminance on the irradiation surface. According to claim 7, the discharge lamp is arranged in the reflector so that the portion of the light diffusing portion having a high light diffusivity is located on the top side of the portion having a low light diffusing rate. The light that is going on is significantly diffused and reflected by the reflector. Further, in the reflecting surface of the reflector, the light from the discharge lamp toward the reflector is reflected by the reflector without being diffused as it goes from the top to the closed portion.

Therefore, the reflected light in the vicinity of the top of the reflector is diffused to reduce the illuminance on the illuminated surface, and the reflected light on the closed portion side of the reflector is hardly diffused. It is possible to improve the uniformity of illuminance.

According to the eighth aspect, there is the effect according to any one of the sixth to seventh aspects.

According to the ninth aspect, there is the effect according to any one of the sixth to seventh aspects.

[Brief description of drawings]

FIG. 1 is a sectional view showing a light source device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an enlarged main part of a discharge lamp according to an embodiment of the present invention.

FIG. 3 is a conceptual diagram showing a configuration of a light projecting device according to an embodiment of the present invention.

FIG. 4 is a diagram showing an illuminance measurement position on a screen.

FIG. 5 is a characteristic diagram showing the relationship between the position on the screen and the relative illuminance in the case of the present invention and the related art.

FIG. 6 is a plan view showing a conventional lamp.

[Explanation of symbols]

1. ． ． Short arc discharge lamp, 2 ... Reflector, 3 ... Liquid crystal panel, 6 ...
Screen, 20 ... Arc tube, 21
・ ・ ・ Electrode 28 ・ ・ ・ Light diffuser 29
... Transparent part.

Front page continuation (72) Inventor Mamoru Furuya 4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo Inside Toshiba Lighting & Technology Corporation

Claims (9)

[Claims] 1. An arc tube having an internal space, a discharge medium sealed in the internal space, and having a pair of electrodes that are sealed so as to be capable of discharging in the internal space; and an arc tube in which the degree of light diffusion is changed. A short arc discharge lamp comprising: a light diffusing portion formed on a wall; 2. An arc tube having an internal space, a discharge medium sealed in the internal space, and a pair of electrodes sealed so as to allow discharge in the internal space; and a wall portion forming the internal space of the arc tube. A second light diffusing portion formed adjacent to the first light diffusing portion of the wall portion forming the internal space of the arc tube and having a light diffusing rate lower than that of the first light diffusing portion; A short arc discharge lamp, comprising: a transparent portion formed adjacent to a second light diffusing portion of a wall portion forming an internal space of the arc tube. 3. An arc tube having an internal space, a discharge medium sealed in the internal space, and a pair of electrodes sealed so as to be capable of discharging in the internal space; and a wall forming the internal space of the arc tube. A transparent portion formed on the inner wall of the arc tube and a light diffusing portion having a higher light diffusivity in a direction away from the transparent portion. A short arc discharge lamp characterized by. 4. The short arc discharge according to any one of claims 1 to 3, wherein the arc tube is made of quartz, and the light diffusing portion is a fine uneven surface formed on the surface of the arc tube. Electric light. 5. The arc tube is made of transparent ceramics,
The short arc discharge lamp according to any one of claims 1 to 3, wherein the transparent portion and the portion of the light diffusion portion having a low light diffusivity form a smooth surface of the arc tube. 6. A short arc discharge lamp according to any one of claims 1 to 5, which has a top portion and a closed portion, is provided with the discharge lamp, and reflects the light output by the discharge of the discharge lamp. A light source device comprising: a reflector for outputting light from a closing part. 7. A short arc discharge lamp according to any one of claims 1 to 5; having a top portion and a closed portion, wherein a portion of the light diffusing portion having a high light diffusivity is lower than a portion having a low light diffusivity. A light source device comprising: the reflector disposed so as to be located on the top side, and a reflector that reflects the light output by the discharge of the discharge lamp and outputs the reflected light from a closed portion. 8. A light source device according to claim 6; a power source for stably lighting a discharge lamp of the light source device; and a housing for housing the light source device and the power source. A characteristic floodlighting device. 9. A light source device according to claim 6; a power supply for stably lighting a discharge lamp of the light source device; a liquid crystal panel for making light output from the light source device incident and controlling the light;
A liquid crystal projector device, comprising: a light source device, a power supply, and a housing containing a liquid crystal panel.