JPH0997595A - Metal halide lamp, lighting device, projecting device, and projector device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal halide lamp and its lighting device, light emitting device and projector device in which a large-sized anode can be arranged within a small discharge space so that stable emission characteristic can be provided. SOLUTION: A metal halide lamp 1 has a light emitting tube 2 forming an elliptic discharge space. A pair of electrodes 21a, 21b are provided within the discharge space so that the distance between the electrodes is 10mm or less, and a discharge medium containing metal halide is sealed therein. The anode 21a has a large-sized electrode head part 21aa on the tip part and also an electrode shaft part 21ab continued to the electrode head part 21ab and formed integrally thereto. The surface of the electrode shaft base end part of the light emitting tube 20 is extended in a quadratic curve form, the anode 21a is arranged within the light emitting tube 20 in such a manner that the distance with the light emitting tube 20 in each point of the inclined part is gradually increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC-lighted metal halide lamp, a lighting device for the lamp, a light projecting device using the lamp as a light source, and a projector device.

[0002]

2. Description of the Related Art Short arc metal halide lamps are used as light sources for light projecting devices in color liquid crystal projector devices, for example. In the color LCD projector bag, a light projector is composed of a lamp which is a light source and a reflector which reflects light emitted from the lamp, and the light projected from the projector irradiates the liquid crystal display panel. The light transmitted through the liquid crystal display panel is controlled by the optical system and projected on the screen surface. In this case, the liquid crystal display panel corresponds to each pixel by R
Since the light passing through the liquid crystal display panel is provided with a GB color filter and is colored by the color filter into one of RGB, the RGB color light rays are projected on the screen surface. Therefore, the liquid crystal display is displayed on the screen surface. A color image of the image controlled by the panel will be displayed.

As a light source for such a color liquid crystal projector bag, it is desired that the light source be close to a point light source in terms of easiness of control in an optical system, and a large amount of light can be obtained for a low power, and abundant light can be obtained. There is a need for a lamp capable of satisfying the conditions that it emits, in addition, efficiently radiates red, blue, and green components, and that it generates less heat. As a lamp satisfying such a condition, a short arc metal halide lamp is preferable.

The short arc metal halide lamp is
Electrodes are provided at both ends of an arc tube made of quartz glass, and a metal halide as a light emitting metal and a rare gas such as mercury and argon as a buffer metal are sealed inside the arc tube. Such a lamp has an interelectrode distance L
Is 10 mm or less, preferably 3 to 7 mm, and it is called a short arc type because the arc discharge generated between these electrodes is short. And 150 during lighting
The tube wall load (value obtained by dividing the input power W by the inner surface area of the arc tube) with electric power of W to 350 W is used under a large load condition of about 30 to 100 W / cm 2.

Therefore, in the case of such a metal halide lamp, since the arc is short, it becomes close to a point light source,
Moreover, a large amount of light can be obtained for the low power point.

Further, as metal halides to be enclosed in this kind of short arc metal halide lamp, dysprosium Dy, neodymium Nd, holmiwham Ho,
At least one rare earth metal halide selected from thulium Tm, indium ln, and thallium Tm
1, at least one halide selected from gallium Ga, zinc Zn, and cadmium Cd is selected and used.

At least one halide of a rare earth metal selected from dysprosium Dy, neodymium Nd, holmium Ho, and thulium Tm emits a continuous spectrum light output over all visible light, thus improving color rendering. At least one halide selected from indium ln, thallium T1, gallium Ga, zinc Zn, and cadmium Cd is effective, and RG is the three primary colors of light.
B has a peak wavelength in each wavelength range, and these RGB
It is suitable for efficiently emitting the light of.

However, in such a metal halide lamp, the metal halide easily reacts with quartz to cause devitrification, and particularly when the metal halide lamp is lit in a state where the load on the tube is high, the reaction between quartz and halogen is promoted and a luminous flux is produced early. There is a problem of decrease. In order to solve this, recent short arc metal halide lamps are lit by direct current.

When the metal halide lamp is lit by direct current,
The metal halide contained in the discharge space is attracted to the anode and mercury is attracted to the cathode, so that the metal halide and mercury are separated by a so-called catalysis phenomenon. Therefore, the metal halide is prevented from being attracted by the anode and existing near the quartz wall, and therefore the reaction with quartz is suppressed, premature devitrification is prevented, and the luminous flux maintenance factor is improved. .

[0010]

However, in such a DC lighting type short arc metal halide lamp, when the lamp is lit in a horizontal position, the temperature of the anode becomes high because thermoelectrons collide with the electrode serving as the anode during lighting. There is a problem that this winning anode is eroded and deformed. In order to prevent this, the anode is usually made larger than the cathode.

However, since the discharge space of the short arc metal halide lamp is small, there is a limit to the size of the anode, and the temperature of the anode becomes higher than that of the cathode.
The heat of the anode is transferred as radiant heat and conduction heat to the sealed part where the anode is sealed, and the temperature of the arc tube wall on the anode side rises as compared with the cathode side in the entire arc tube, so that the temperature difference as a whole appear.

When a temperature difference occurs on the wall of the arc tube, not only is there a concern about the occurrence of thermal strain, but also a temperature difference occurs on the inner surface of the discharge space, which makes the evaporation of the metal halide unstable and affects the light emission characteristics. I am worried about troubles such as causing damage.

In particular, when a rare earth metal halide containing dysprosium is used as the light emitting substance, it is necessary to raise the vapor pressure of the rare earth metal halide of this kind sufficiently, so that the coldest part temperature is raised. It is considered. As one of the means, lighting is performed by increasing the tube wall load to increase the tube wall temperature. However, if there is a temperature difference on the arc tube wall, the coldest part will be generated, and the temperature of this coldest part will not rise, and sufficient vapor pressure may not be obtained, which causes problems such as variations in luminous efficiency. There is.

Further, when the temperature on the cathode side becomes low, when the light is turned off, the metal halide aggregates in the coldest portion to cover the cathode, and when restarting, the emission of electrons is hindered and the starting voltage is reduced. There is also concern about problems such as raising the height and causing discharge at the base of the cathode.

The present invention has been made in view of the above circumstances. An object of the present invention is to prevent a temperature difference in an airtight container and to obtain a stable light emitting characteristic, a metal halide lamp, a lighting device for the same, and a lighting device. It is intended to provide an optical device and a projector device.

[0016]

According to a first aspect of the present invention, there is provided an airtight container having a discharge space formed therein; and a bulging shape having a large diameter with a cathode which is sealed in the airtight container and has an interelectrode distance of 10 mm or less. A pair of an electrode main body, a small-diameter electrode shaft portion that is embedded in an airtight container, and an anode that has an inclined portion that continuously decreases in diameter from the base end of the bulging portion to the tip of the electrode shaft portion. An electrode; a discharge medium containing a metal halide enclosed in the discharge space; and the surface of the base end of the electrode shaft of the airtight container is expanded into a quadratic curve, and the anode is The metal halide lamp is arranged in the airtight container so that the distance to the airtight container at each point gradually increases.

In the present invention and the following claims, the bulge means a bulge with respect to the electrode shaft. The inclined portion is a portion that connects the bulging portion and the electrode shaft so as not to form an acute angle portion.

In each claim, the fact that the base end portion of the airtight container expands in a quadratic curve in cross section means that the gap is small at the deepest part and gradually expands in a quadratic function.

If the distance between the electrodes is 10 mm or less, it approaches the point light source, but the range of 3 to 5 mm is preferable.

As the airtight container, not only quartz but also ceramics can be used. What is essential is that it has translucency and fire resistance and can hermetically seal the discharge medium.

According to the first aspect of the present invention, the structure is such that the inclined portion of the anode is inserted into the expanded portion of the base end portion of the airtight container.
The size of the electrode can be made larger than that of the conventional one in a small discharge space. Therefore, it is possible to provide a suitable metal halide lamp with an increased temperature capacity of the anode.

Claims 2 and 3 have the function of claim 1.

According to the invention of claim 4, the pipe wall load is 30.
Since the light is turned on at W / cm 2 or more, the temperature of the tube wall becomes high, and evaporation of the luminescent metal is promoted to improve the luminous efficiency.

A fifth aspect of the present invention is the metal halide lamp according to any one of the first to fourth aspects, wherein the lamp is horizontally lit so that the lamp shaft is substantially horizontal.

According to the invention of claim 5, since the lamp is lit horizontally, a temperature difference is likely to occur between the anode side and the cathode side, but the unevenness according to any one of claims 1 to 3 is generated. If adopted, the temperature difference can be reduced even in horizontal lighting. The invention according to claim 6 is the metal halide lamp according to any one of claims 1 to 5, wherein the metal halide is a halide of a rare earth metal containing at least dysprosium. According to the invention of claim 6, since a halide of a rare earth metal containing at least disprom is used as the metal halide, high efficiency and high color rendering can be realized by lighting with a high load on the tube wall.

The invention according to claim 7 is a lighting device comprising: the metal halide lamp according to any one of claims 1 to 6; and a lighting means for lighting the metal halide lamp by direct current. .

According to the invention of claim 7, it is possible to provide a lighting device making the most of the characteristics of the lamp.

According to an eighth aspect of the present invention, there is provided a metal halide lamp according to any one of the first to fifth aspects; and a reflector that houses the metal halide lamp and reflects light emitted from the lamp. It is characterized in that the metal halide lamp is arranged along the optical axis of the lamp axis beam reflector, is arranged on the back side of the anode beam reflector, and is arranged on the opening side of the cathode beam reflector. It is a floodlight road to do.

According to the eighth aspect of the present invention, the metal halide lamp as the light source has a high brightness and is close to a point light source, so that the reflection control by the twist flexure can be facilitated and the light collection rate can be increased. Moreover, since it is arranged on the back side of the anode beam reflector and on the closed side of the cathode beam reflector, it is possible to effectively reflect the high-luminance light emitted from the cathode side on the reflecting surface of the reflector. , The light emission efficiency is improved.

According to a ninth aspect of the present invention, in the light projecting device according to the eighth aspect, the heat insulating coating is not present on a line connecting the tip of the cathode and the outermost line of the effective reflection surface of the reflector. is there.

According to the ninth aspect of the present invention, since the heat insulating coating is not present on the line connecting the tip of the cathode and the outermost line of the effective reflection surface of the reflector, the discharge space of the airtight container is changed to the effective reflection surface of the reflector. The heat-retaining film does not block the emitted light, so that the light projection efficiency is improved.

A tenth aspect of the present invention includes a light projecting device according to the eighth or ninth aspect of the invention; and a display device for projecting light emitted from the light projecting device. It is a device.

According to the invention of claim 10, since the light projecting device of claim 8 or 9 is used, the brightness of the screen surface can be increased.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on an embodiment shown in the drawings.

FIG. 1 shows the structure of a light projecting device 50 in which a short arc metal halide lamp 1 and a reflector 3 are finely combined.

The short arc metal halide lamp 1 has a rated lamp power of 250 W and includes an airtight container made of quartz glass, that is, an arc tube 20. The arc tube 20 has an elliptical discharge space. That is, the arc tube 20 has a wall thickness of 1.2 mm, a major axis a of the discharge space (a distance between inner ends in the direction in which the electrodes face each other) is approximately 14.0 mm,
The minor axis b is about 12 mm, the inner surface of the discharge space is about 5.0 cm 2, and the inner volume is about 0.9 cc. A pair of electrodes 21a and 21b are provided in this discharge space. These electrodes 21a and 21b are an anode 21a and a cathode 21b, respectively.
And the cathode 21b, the distance L between these electrodes is 10 mm or less,
For example, it is installed so as to be 3.0 mm.

The anode 21a has a large-sized electrode head portion 21aa at its tip, and has an electrode shaft portion 21ab continuous with the electrode head portion 21aa. Electrode head portion 21aa
Is made of tungsten having a wire diameter of 2.3 mm and a length of about 6.0 mm, and the electrode shaft portion 21ab is integrally formed with the electrode head portion 21aa and has a wire diameter of about 1.1 mm. The length of protrusion of this anode 21a into the discharge space is 6.5.
It is said to be mm.

The cathode 21b is made of a straight tungsten wire and has a wire diameter of 0.7 mm, for example. The length Hc (mm) of the cathode 21b protruding into the discharge space is the distance between the inner ends of the discharge space in the direction in which the pair of electrodes 21a and 21b face each other, that is, the major axis dimension a (mm) of the ellipse.
The relationship is as follows: 0.2 ≦ Hc / a ≦ 0.4 (1), and Hc (mm) is 4.5 mm in this embodiment.

From the above, these electrodes 21a, 21
The center position P between b is deviated to the cathode 21b side from the distance between the inner ends of the discharge space in the direction in which the electrodes 21a and 21b face each other, that is, the center of the major axis a of the ellipse.

The electrodes 21a and 21b are connected to metal foil conductors 23 and 23 sealed to the sealing portions 22 and 22 formed at both ends of the arc tube 20. Metal foil conductor 23,
Reference numeral 23 is a molybdenum foil having a thickness of 30 μm and a width of about 3 mm, and one of the gold horizontal foil conductors 23 is electrically connected to a base 24 attached to an end portion thereof via an external lead wire (not shown). The other metal foil conductor 23 is connected to the external lead wire 25.

The arc tube 20 is filled with a metal halide as a light emitting metal, mercury as a buffer metal, and is sealed with a rare gas such as argon.

The above metal halides are dysprosium Dy, neodymium Nd, holmium Ho, and thulium Tm.
A halide of at least one rare earth metal selected from among, indium ln, thallium T1, and gallium G
a, at least one kind of halide selected from zinc Zn and cadmium Cd, and a halide of cesium Cs.

The halides of at least one rare earth metal selected from Dy, Nd, Ho and Tm are iodides and bromides. Specifically, Dy13 is 0.25.
mg, DyBr3 is 1.0 mg. Nd8r3 is 0.2mg
It is. At least one halide selected from In, T1, Ca, Zn, and Cd is also iodide and bromide, and specifically, InBr is 0.44 mg. Further, the halide of cesium Cs is Csl, and 1 mg is included.

The total amount of the above metal halide enclosed is about 2.
It is 0 mg, whereas mercury Hg is encapsulated in 34 mg, and Ar is encapsulated in 500 Torr.

A heat insulating shell 28 is formed on the outer surface of the arc tube 20 on the cathode 21b side.

The heat insulation coating 28 is, for example, alumina A12O3.
And silica SiO2, etc., and is formed by coating the outer surface of the arc tube 20 over a predetermined region. This insulation film 2
No. 8 has one end covering at least a part of the cathode side sealing portion 22, and the pond end covers a predetermined range toward the protruding direction of the cathode 21b, and the pond end boundary of the heat insulation coating 28 is the inner end of the cathode side discharge space. The dimension is M (mm) in the direction in which the cathode 21b projects from the portion, and this boundary M corresponds to the length Hc (mm) in which the cathode 21b projects into the discharge space, 0.5 ≦ M / Hc ≦ 1.0 (2) Specifically, M = 3.6 mm.

The short arc metal halide lamp 1 as described above is attached to the reflector 3 and is attached to the light projecting device 5.
Make up 0. The reflector 3 is made of glass or metal, and has a TiO2-
It has a reflecting surface 31 made of a vapor deposition film such as SiO2. The front light projecting portion of the reflector 3, that is, the opening portion is formed to have a thrombus degree of 90 to 130, and a support cylinder portion 32 is provided on the top of the back portion. The base 24 of the lamp 1 is fixed to the support cylinder 32 with an adhesive 33 such as insulating cement. Thereby, the lamp 1
This lamp 1 is attached to the beam reflector 3 so as to be substantially aligned with the central axis of the lamp axis O1 to O1 beam reflector 3, that is, the optical axis O2 to 02. The optical axes 02-102 are arranged substantially horizontally, so that the lamp 1 is lit horizontally.

The lamp 1 mounted on the reflector 3 is positioned on the anode 21a side of the arc tube 20 and on the support cylinder 32 side of the reflector 3, and the cathode 2
It is attached so as to be located on the front opening side of the side reflector 1b.

In such an assembled state, the heat insulation coating 28 formed on the arc tube 20 connects the tip of the cathode 21b and the outermost line of the effective reflection surface of the reflector 3 as shown in FIG. It does not exist on the line c,
That is, the heat insulating coating 28 should be formed in a region in front of the line c connecting the tip of the cathode 21b and the outermost line of the effective reflection surface of the reflector 3.

A guide hole 34 is formed in the reflector 3, and the external lead wire 25, which is dressed as the cathode 21b of the lamp 1, passes through the guide hole 34 and is guided to the rear side. There is.

In such a lamp 1, the base 24 and the external lead wire 25 are connected to the power supply means 40 composed of 3 AC / DC converters to form a lighting device. The power supply means 40 applies a DC power of I50W to 250W to the lamp so that the lamp has a wall load of 30 to 100W.
The lamp 1 has a rated power of 250 W and the inner surface area of the arc tube is 5.0 cm2, so that the lamp wall load is about 50 W / cm2. .

The floodlight bag 50 is used, for example, in a color projector device as shown in FIG. 61 of FIG.
Is a housing that serves as the main body of the color projector device, and in the housing 61, the light projecting device 50,
A liquid crystal display panel 62 and an optical system 63 such as a lens are provided, and a power supply means 40 including the AC / DC converter and a liquid crystal driving device 64 are provided. The power supply means 40 and the liquid crystal driving device 64 are connected to the commercial power wave 65.

When the lamp 1 is turned on by the power supply from the power supply means 40, the light emitted from the lamp 1 is reflected by the reflector 3 and illuminates the liquid crystal display panel 62. The liquid crystal display panel 62 is provided with an RGB color filter (not shown) corresponding to each pixel, and the color filter is controlled by the liquid crystal driving device 64.

The light transmitted through the liquid crystal display panel 62 is colored into one of RGB by this color filter, and the colored light is condensed by the optical system 63 such as a lens and projected on the screen 66. Therefore, the color image of the image controlled by the liquid crystal display panel 62 is displayed on the screen 66.

In the metal halide lamp having such a structure, the center position P of the anode 21a and the cathode 21b is deviated to the cathode side from the center of the major dimension a of the discharge space, so that the anode 21a is located in the discharge space. Therefore, the cathode 21b is mounted relatively close to the cathode 21b, so that the anode 21a is attached.
The heat generated from the cathode is transmitted to the cathode side by radiation or conduction. Further, a heat insulating coating 28 is formed on the outer surface of the arc tube 20 on the cathode side.
Since the heat insulating film 28 is formed, the heat insulating film 28 prevents heat from escaping from the surface of the arc tube 20 on the cathode side.
Then, the temperature rise of the surface on the cathode side is promoted.

Therefore, the temperature distribution of the arc tube 20 can be equalized even when the lamp is lit horizontally. Therefore, thermal distortion does not occur in the arc tube 20 and a temperature difference does not occur on the inner surface of the discharge space, so that evaporation of the metal halide is stabilized.

In particular, when dysprosium is used as the light emitting substance and a halide of a rare metal is used, the tube wall load is increased to raise the tube wall temperature and lighting is performed, and a temperature difference occurs on the wall of the arc tube. Since it is not present, evaporation is promoted as a whole to obtain a sufficient vapor pressure, and the luminous efficiency is improved.

Further, when the light is turned off, the metal halide does not agglomerate on the cathode side, the metal halide does not cover the cathode 21b, the electron emission becomes good in the case of restarting, and the starting bright voltage is increased. Lower to make the start smoother.

The relationship between the length of the cathode 21b protruding into the discharge space, HC (mm), and the major axis a of the discharge space,
To satisfy the formula (1), the anode 21a is provided so as to be deviated to the cathode side, so that the heat of the anode 21a is transferred to the cathode side by radiation or conduction, and the temperature difference of the airtight container is reduced. You can

Further, the heat insulation coating 28 has one end covering at least a part of the cathode side sealing portion 22 and the other end having the cathode 21.
This heat insulating film 2 covering a predetermined area in the protruding direction of b
The other end of 8 has a dimension M (mm) directed from the inner end portion of the cathode side discharge space in the protruding direction of the cathode 21b so as to satisfy the expression (2). At 28, the rate of blocking light is reduced.

The above formulas (1) and (2) are the ranges obtained by the experiments by the present inventors, and the experimental examples will be described below.

[0062]

【Example】

[Experiment 1] In the short arc metal halide lamp with the rated lamp power of 250 W of the above-mentioned embodiment, the cathode 21b
The total luminous flux (lm) was measured by variously changing the length HC (mm) protruding into the discharge space and the distance between the inner ends of the discharge space, that is, the major diameter dimension a (mm) of the ellipse. In this case, M / HC was adjusted to be 0.8 in the range where the heat insulating coating 28 was formed.

The short arc metal halide lamp 1 having the above structure has an electrode distance of 10 mm or less, preferably 3 mm.
Since it is set in the range of ~ 7mm, the arc length becomes shorter,
This is also a major factor that can approach the point light source.

The lamp 1 has a wall load of 30 W.
Since the light is turned on at a high load of / cm 2 or more, the light emission amount increases, the irradiation amount increases as the light projecting device 50, and the brightness of the screen 66 as the color projector device improves.

Further, since the lamp 1 is lit by direct current, the metal halide and mercury are separated into the anode and the cathode during lighting by the catalysis phenomenon, so that the halide adheres to the bulb wall. It will be difficult. Therefore, it is possible to prevent devitrification and improve the life characteristics.

Further, since the lamp 1 is horizontally lit, a temperature difference is likely to occur between the anode side and the cathode side. However, if the above configuration is adopted, the temperature difference of the arc tube can be reduced even in the horizontal lighting. be able to.

In the light projecting device 50 of the above embodiment, the metal halide lamp 1 as a light source is close to a point light source and has high brightness. Therefore, the reflection control by the reflector 3 is facilitated and the light collection rate is improved. Can be increased.

In the lamp 1 attached to the reflector 3, the heat insulating coating 28 formed on the arc tube 20 in the thinned state is formed on the tip of the cathode 21b and the effective reflection surface of the reflector 3 as shown in FIG. Paper c that connects the outermost line
It does not exist above, and the heat insulating coating 28 is formed in a region in front of the vertical c that connects the tip of the cathode 21b and the outermost line of the effective reflection surface of the upper reflector 3. Therefore, the emission area of the light traveling from the arc tube 20 to the reflector 3 is increased, and the amount of light reflected by the reflector 3 is increased. That is, when the heat insulating clothing 28 is formed so as to cross the paper c that connects the tip of the cathode 21b and the outermost line of the effective reflection surface of the reflector 3, the heat insulating coating 28 shields the light from the arc tube 20. The radiation area of the light directed to the reflector 3 is reduced, and the amount of light reflected by the reflector 3 is reduced. As a result, the illumination of the screen 66 is reduced. On the other hand, the heat insulation coating 28 is formed by a line c connecting the tip of the cathode 21b and the outermost line of the effective reflection surface of the reflector 3.
If it is formed in the range of the front position, the light shielding effect of the heat insulating coating 28 is reduced, and the illuminance of the screen 66 can be increased.

Furthermore, according to the color projector device of this embodiment, the brightness of the screen 66 surface can be increased.

[0070]

According to the present invention, since the inclined portion of the anode is inserted into the expanded portion of the base end portion of the airtight container, the size of the electrode can be increased in a small discharge space as compared with the conventional one. Can be configured into shapes. Therefore, it is possible to provide a suitable metal halide lamp with an increased temperature capacity of the anode.

The second and third aspects can provide a metal halide lamp that achieves the effects of the first aspect.

According to the invention of claim 4, the pipe wall load is 30.
Since the light is turned on at W / cm 2 or more, the temperature of the tube wall becomes high, and evaporation of the luminescent metal is promoted to improve the luminous efficiency.

According to the invention of claim 5, since the lamp is lit horizontally, a temperature difference is likely to occur between the anode side and the cathode side, but the unevenness according to any one of claims 1 to 3 is generated. If adopted, the temperature difference can be reduced even in horizontal lighting. According to the invention of claim 6, since a halide of a rare earth metal containing at least disprom is used as the metal halide, high efficiency and high color rendering can be realized by lighting with a high load on the tube wall.

According to the invention of claim 7, it is possible to provide a lighting device utilizing the characteristics of the lamp.

According to the eighth aspect of the present invention, the metal halide lamp as the light source has a high brightness and is close to a point light source, so that the reflection control by the eccentric flexure can be facilitated and the light collection rate can be increased. Moreover, since it is arranged on the back side of the anode beam reflector and on the closed side of the cathode beam reflector, it is possible to effectively reflect the high-luminance light emitted from the cathode side on the reflecting surface of the reflector. , The light emission efficiency is improved.

According to the ninth aspect of the present invention, since the heat insulating coating is not present on the line connecting the tip of the cathode and the outermost line of the effective reflection surface of the reflector, the discharge space of the airtight container is changed to the effective reflection surface of the reflector. The heat-retaining film does not block the emitted light, so that the light projection efficiency is improved.

According to the tenth aspect of the invention, since the light projecting device of the eighth or ninth aspect is used, the brightness of the screen surface can be increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the light emitting device including a metal halide lamp and a reflector and the function of a lighting bag.

FIG. 2 is an enlarged view showing an arc tube of the metal halide lamp of the embodiment.

FIG. 3 is an explanatory diagram showing the principle of a color liquid crystal projector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Metal halide lamp 3 ... Reflector 20 ... Arc tube 21a ... Anode 21b ... Cathode 21aa ... Anode head part 21ab ... Anode side electrode shaft 28 ... Insulating film 31 ... Reflective surface 40 ... DC power supply means 50 ... Projector 62 ... Panel 63 ... Optical system 64 ... Liquid crystal driving device 66 ... Screen

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Tanaka 4-3-1, Higashishinagawa, Shinagawa-ku, Tokyo Inside Toshiba Litec Co., Ltd.

Claims (10)

[Claims] 1. An airtight container in which a discharge space is formed; a main body of an electrode having a bulging shape of a cathode and an airtight container which are sealed in the airtight container and face each other with an interelectrode distance of 10 mm or less. A pair of electrodes consisting of a small-diameter electrode shaft portion embedded and an anode having an inclined portion that continuously decreases in diameter from the base end of the bulging portion to the tip of the electrode shaft portion; enclosed in a discharge space A discharge medium containing a metal halide; and the surface of the base end of the electrode shaft of the airtight container is expanded into a quadratic curve, and the anode has a distance from the airtight container at each point of the inclined portion. A metal halide lamp characterized by being arranged in an airtight container so as to gradually increase. 2. An airtight container having a discharge space formed therein; an electrode main body having a bulging shape with a large diameter, and a cathode which is sealed inside the airtight container and has a distance between electrodes of 10 mm or less. A pair of electrodes consisting of a small-diameter electrode shaft portion embedded and an anode having an inclined portion that continuously decreases in diameter from the base end of the bulging portion to the tip of the electrode shaft portion; enclosed in a discharge space A discharge medium containing a metal halide; the surface of the base end portion of the electrode shaft of the airtight container is expanded into a quadratic curve, and the anode has an inclined portion shape at each point. A metal halide lamp characterized in that the distance is gradually increased. 3. An airtight container in which a discharge space is formed; an electrode main body having a bulging shape with a large diameter, which is sealed in the airtight container and has an electrode distance of 10 mm or less, and is embedded in the airtight container. An electrode having a small diameter and a slanted portion that continuously decreases in diameter from the base end of the bulging portion to the tip of the electrode shaft; and a discharge medium containing a metal halide enclosed in the discharge space. The surface of the base end of the electrode shaft of the airtight container is expanded into a quadratic curve, and the electrode is hermetically sealed so that the distance to the airtight container at each point of the inclined portion gradually increases. A metal halide lamp characterized by being placed inside. 4. The metal halide lamp according to claim 1, wherein the lamp is lit at a tube wall load of 30 W / cm 2 or more. 5. The lamp according to any one of claims 1 to 4, wherein the lamp shaft is horizontally lit with its lamp shaft substantially water-immersed.
The metal halide lamp according to any one of. 6. The metal halide lamp according to claim 1, wherein the metal halide is a halide of a rare earth metal containing at least dysprosium. 7. A lighting device comprising: the metal halide lamp according to any one of claims 1 to 6; and a lighting means for lighting the metal halide lamp by direct current. 8. A metal halide lamp according to any one of claims 1 to 6, and a reflector for accommodating the metal halide lamp and reflecting light emitted from the lamp. The projector is characterized in that the lamp is arranged along the optical axis of the lamp axis beam reflector, is arranged on the back side of the anode beam reflector, and is arranged on the closed side of the cathode beam reflector. . 9. A heat insulating film is formed on the outer surface of the metal halide lamp, and the heat insulating film is not present on the line connecting the tip of the cathode and the outermost line of the effective reflection surface of the reflector. Item 8. The light projecting device according to item 8. 10. A projector device comprising: the light projecting device according to claim 8 or claim 9; and a display device for projecting light emitted from the light projecting device.