JP3404788B2 - High pressure discharge lamp and light source device using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-pressure discharge lamp in which an arc tube made of quartz glass is provided with an ultraviolet ray cutting means, and a light source device using this discharge lamp.

[0002]

2. Description of the Related Art A high pressure discharge lamp in which mercury, a metal halide, xenon gas or the like is enclosed in an arc tube made of quartz glass has advantages such as high efficiency and long life. It is used widely in various fields. In particular, in recent years, in view of the downsizing of the apparatus, in order to downsize the lamp, the quartz arc tube is exposed without using an outer bulb (outer bulb less lamp), and the arc length is shortened. Since the short arc discharge lamp described above is close to a point light source, it is used as a light source device such as a projector, a projector and an exposure device in combination with an optical system such as a reflecting mirror and a lens.

By the way, the high-pressure discharge lamp of this kind has a good spectral rendering of the emission spectrum over a wide range from the ultraviolet region to the infrared region and has a good color rendering property. But 20
Ultraviolet rays of 0 nm or less have a property of reacting with oxygen in the air to generate ozone. This ozone is sometimes used for chemical treatment such as cleaning and sterilization, but it is harmful to the human body. It is said that it is desired to block ultraviolet rays.

Conventionally, so-called ozone-free quartz, in which titanium oxide TiO ₂ is mixed and dispersed in quartz glass, has been used as a means for cutting off ultraviolet rays of 200 nm or less emitted from an arc tube. TiO ₂ is an excellent substance that absorbs ultraviolet rays and transmits visible light.

[0005]

However, the above-mentioned conventional ozone-free quartz is one in which TiO ₂ is mixed with SiO ₂ which is a silica glass component and dispersed, and this dispersion is not uniform, and TiO ₂ is locally dispersed. May be unevenly distributed. Such ozone-free quartz is liable to cause local distortion, and there is a concern that it may be damaged when used in the arc tube of a short arc discharge lamp in which the internal pressure of the arc tube during lighting reaches several tens of atmospheres.

As another means for cutting off ultraviolet rays that escapes from such a problem, as described in Japanese Utility Model Publication No. 50-36865, a coating film made of tin oxide SnO is formed on the outer surface of an arc tube made of quartz glass. A proposal has been made to do so. Such SnO coating has an advantage that it absorbs and reflects ultraviolet rays having a wavelength of 200 nm or less and thus does not irradiate the outside of the arc tube with ultraviolet rays. However, in this case, since the SnO coating is formed on the outer surface of the arc tube, the ultraviolet light emitted from the discharge space passes through the wall of the arc tube. That is, the quartz glass itself is irradiated with ultraviolet rays, the OH groups in the quartz glass are decomposed, the quartz glass becomes brittle with the passage of lighting time, and the strain in the quartz glass increases and cracks occur during the life of the quartz glass. I have something to do.

Further, as another means, it is conceivable to form a coating film made of tin oxide SnO on the inner surface of the arc tube made of quartz glass. However, when such a lamp was prototyped and evaluated, the SnO coating formed on the inner surface of the arc tube was exposed in the discharge space, so the temperature of this tin oxide SnO increased during lighting, and it also received ultraviolet rays. It may deteriorate or come off. Further, in the case of such a lamp, the light output tended to decrease as the lighting time passed, as compared with the conventional lamp. The cause is that the SnO coating formed on the inner surface of the arc tube was scattered from the electrode (B
It was found that the a, Sr, Ca) ₃ WO ₆ -based emitter reacts and becomes cloudy, which reduces the luminous flux. Further, in the case where titanium oxide TiO ₂ used in the conventional ozone-free quartz is applied to the inner surface of the arc tube, the luminous flux is similarly reduced.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent emission of ultraviolet rays, suppress an increase in distortion of quartz glass, and keep good light over the life of the lamp. An object of the present invention is to provide a high pressure discharge lamp capable of maintaining output and a light source device using the same.

[0009]

According to the invention of claim 1, tantalum oxide Ta ₂ O ₅ and cerium oxide CeO ₂ are provided on the inner surface of an arc tube made of quartz glass with electrodes sealed at the ends.
A metal oxide film made of at least one selected from neodymium oxide Nd ₂ O ₃ , tin oxide SnO, zirconium oxide ZrO ₂ , zinc oxide ZnO, iron oxide Fe ₂ O ₃ , and vanadium oxide V ₂ O ₅ is formed. Luminescence above by heating
It is characterized in that a layer in which the metal oxide is diffused is formed in the tube . In the invention of claim 2, the electrode is thorium oxide.
Is characterized in that the emitter is impregnated . The invention of claim 3 is characterized in that the arc tube is exposed without being surrounded by the outer tube.

According to a fourth aspect of the present invention, there is provided a light source device in which the exposed high pressure discharge lamp is used in combination with an optical system for controlling light emitted from the discharge lamp.

[0011]

According to the first aspect of the invention, Ta ₂ O 5, CeO ₂ , Nd ₂ O is formed on the inner surface of the arc tube made of quartz glass.
₃ , SnO, ZrO ₂ , ZnO, Fe ₂ O ₃ , V ₂ O ₅
Of at least one metal oxide selected from
By heating the film, the metal oxide is loaded into the arc tube.
Since a layer for UV obtained by diffusion, UV This UV layer is absorbed or reflected, thus ultraviolet rays not emitted to the outside. Moreover, this UV blocking layer heats the metal oxide film on the inner surface of the quartz arc tube.
As a result , the quartz glass is formed by diffusing the metal oxide in the arc tube , so that the quartz glass is not exposed to ultraviolet rays, the distortion of the quartz glass does not increase, and the ultraviolet ray blocking material is peeled off. Nor.

According to the invention of claim 2, if you have a thorium oxide ThO ₂ to electrodes impregnated, i.e. thorium-
Available in the form of tungsten, this material is stable and therefore less likely to react with UV blocking materials
It is possible to prevent white turbidity and prevent a decrease in light output.
It is stopped and has a long life.

According to the third aspect of the invention, in the case of the double-tube high-pressure discharge lamp in which the arc tube is surrounded by the outer tube bulb, even if ultraviolet rays are transmitted from the arc tube and radiated, the outer tube bulb cuts it. However, in the case of an outer tube-less lamp that does not use an outer tube, it cannot be expected.
This is particularly effective when the lamp of No. 1 is an outer tubeless type. According to the invention of claim 4, since a short arc discharge lamp having a long life and without an outer tube can be used as the light source, the life characteristic of the light source device is improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the first embodiment shown in FIGS.

FIG. 1 shows a short arc xenon lamp 10 for direct current lighting. In this short arc xenon lamp 10, an arc tube 1 made of quartz glass having excellent heat resistance is used without an outer tube. It is (without outer tube). This arc tube 1 has an elliptical discharge space 2 formed at the center and crushed seals 3 and 3 at both ends. These crushed seals 3 and 3 include
Metal foil conductors 4 and 4 each made of molybdenum are sealed. An anode 5 is disposed in the discharge space 1 so as to face each other.
And a cathode 6 are provided. The anode 5 is formed by connecting an electrode head 5a made of tungsten to the tip of an electrode shaft 5b made of tungsten, and the cathode 6 is formed by winding a cathode coil 6a made of tungsten around the tip of the electrode shaft 6b made of tungsten. Configured. The cathode coil 6
A is impregnated with an emitter (not shown) made of thorium oxide ThO ₂ and is used in the form of so-called thorium-tungsten. However, this electrode is not coated with a (Ba, Sr, Ca) ₃ WO ₆ system emitter.

The base ends of the electrode shafts 5b and 6b are guided to the crush seal portions 3 and 3, and are joined to the metal foil conductors 4 and 4 here. External lead wires 8 and 8 are bonded to the metal foil conductors 4 and 4, respectively.
Is guided to the outside from the crushing seals 3 and 3 and connected to the bases 9 arranged at the ends of the crushing seals 3 and 3. Further, the discharge space 1 is filled with a predetermined amount of xenon gas.

The quartz glass arc tube 1 has a diffusion layer 7 for blocking ultraviolet rays formed on the inner surface thereof. The ultraviolet cut diffusion layer 7 is made of tantalum oxide Ta ₂ O ₅ , cerium oxide CeO ₂ , neodymium oxide Nd ₂ O ₃ , tin oxide SnO,
Zirconium oxide ZrO ₂ , zinc oxide ZnO, iron oxide F
It is formed of at least one selected from e ₂ O ₃ and vanadium oxide V ₂ O ₅ . In the case of this embodiment,
A diffusion layer made of tantalum oxide Ta ₂ O ₅ is formed.

A method of forming the diffusion layer 7 made of this tantalum oxide Ta ₂ O ₅ will be described. First, a solution to be applied, for example, an organic tantalum compound (general formula: T
a ₂ (OR) ₅ represented by tantalum alkoxides),
Specifically, for example, pentaalkoxy tantalum is applied to the inner surface of an unprocessed straight quartz tube, which is naturally dried and then heat-treated at a temperature of 200 ° C. or higher for 10 minutes or longer to obtain tantalum oxide Ta _{2 of} 5 to 10 μm. Make a film of O ₅ .

Next, the inner surface of the quartz tube is heated by a heating means such as a laser or a burner to melt the inner surface. As a result, the tantalum oxide Ta ₂ O ₅ coating on the surface diffuses inside the wall of the quartz tube, and thus the diffusion layer 7 can be formed.

As a method other than the above, when the arc tube 1 is heated while applying internal pressure to the quartz tube, the tube expands when the tube becomes soft, so that an elliptical discharge space can be formed. Therefore, if a film made of tantalum oxide Ta ₂ O _{5 is} formed on the inner surface of the quartz tube in advance and expansion processing is performed by the heating and softening,
The tantalum oxide Ta ₂ O ₅ coating film diffuses into the inside of the wall of the quartz tube by receiving the heat of heating at this time.
You can also make Such a diffusion layer 7 is provided in the arc tube 1.
Diffuses within a range of several tens of μm from the inner surface.

The short arc xenon lamp 10 constructed as described above constitutes a light source device in combination with an optical system, as shown in FIG. Although a lens or the like may be used as the optical system, this embodiment shows an example in which it is applied to a light source of a light projecting device, and a reflecting mirror is used as the optical system, and the xenon lamp 10 is housed in a reflector 20. Has been done. The reflector 20 is formed of a rotating curved surface, has a reflecting surface 21 formed on the inner surface thereof, and has a cylindrical support portion 22 at the top of the inner portion. The lamp 10 is incorporated in the reflector 20 by inserting the one crushable sealing portion 3 into the support portion 22 of the reflector 20, and in this case, the center line of the lamp coincides with the optical axis of the reflector 20. It is arranged to.
Then, the lamp is fixed to the reflector 20 by, for example, the position adjusting screw 23 screwed into the support portion 22. The lamp 10 shown in FIG. 2 is arranged so that its left and right are reversed from the posture shown in FIG. Further, 25 is a power supply line connected to the base 9.

With such a structure, when the lamp 10 is turned on, visible light and ultraviolet rays are emitted from the xenon enclosed in the arc tube 1. However, since the diffusion layer 7 for blocking ultraviolet rays is formed on the inner surface of the arc tube 1, 2
Ultraviolet rays having a wavelength of 00 nm or less are prevented from leaving the arc tube 1. Therefore, ultraviolet rays are prevented from reacting with oxygen in the air to generate ozone. Moreover, since the diffusion layer 7 for blocking ultraviolet rays is formed by diffusing on the inner surface of the arc tube 1 made of quartz glass, the ultraviolet rays are blocked before passing through the wall of the arc tube 1. The glass itself is not irradiated with ultraviolet rays, and the OH groups in the silica glass are decomposed to prevent problems such as the silica glass becoming brittle and cracks occurring. Furthermore, since the diffusion layer 7 for cutting off the ultraviolet rays is diffused and formed on the inner surface of the arc tube 1 made of quartz glass, it is difficult to peel it off.

Also, in the case of this embodiment, the electrodes 5, 6 are
Since the (Ba, Sr, Ca) ₃ WO ₆ -based emitter is not coated on, the reaction between the (Ba, Sr, Ca) ₃ WO ₆ -based emitter and the oxide forming the diffusion layer 7 occurs. There is no white turbidity. As a result, the light output does not decrease, and a high luminous flux maintenance factor can be maintained for a long period of time. When the electrode shaft or the electrode coil is impregnated with thorium oxide ThO ₂ , that is, when it is composed of triated tungsten, thorium oxide ThO ₂ can improve the starting ability as an emitter, and in the case of such an impregnated structure, Since the reaction with the oxide forming the diffusion layer 7 is small, it is possible to prevent clouding.

FIG. 3 is a graph showing the results of measuring the relationship between the light output and the lighting time. As can be seen from this characteristic, as in the conventional case, the SnO coating formed on the inner surface of the arc tube and the electrode carrying the (Ba, Sr, Ca) ₃ WO ₆ -based emitter (Characteristic B) is lit 2000 Although the light output may decrease to 50 to 60% with the passage of time, the diffusion layer 7 for ultraviolet ray cutting is formed on the inner surface of the arc tube 1 made of quartz glass as in the above-mentioned embodiment of the present invention. In addition, the lamp (Characteristic A) that does not use the (Ba, Sr, Ca) ₃ WO ₆ -based emitter can maintain the light output of about 75 to 80% even after 2000 hours of lighting, and the luminous flux maintenance factor. It can be seen that

Therefore, such a short arc xenon lamp 10 is harmless to the human body because it does not emit ultraviolet rays of 200 nm or less even if it is lit in the state of being directly exposed to the outside air without using the outer bulb, and is harmless to the human body. Since it is not used, it is small and compact, and is close to a point light source.
As shown in FIG. 2, it is convenient to construct the light source device by attaching it to the reflecting mirror 20 and the like, and it has a long life.

The present invention can be applied not only to the short arc xenon lamp of the above-mentioned embodiment but also to other quartz arc tubes of high pressure discharge lamps such as short arc high pressure mercury discharge lamps and small metal halide lamps. is there. Further, the lighting is not limited to direct current lighting, and may be alternating current lighting.

Further, the lamp is not limited to the short arc type and can be implemented by a long arc type, and FIG. 4 shows an example applied to a long arc type high pressure mercury discharge lamp. In FIG. 4, the portions having the same names as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. However, this example is an AC lighting type, and the electrodes 12 and 12 sealed at both ends are electrode shafts, respectively. An electrode coil 12a is wound around 12b. Further, the arc tube 1 is filled with mercury and argon gas.

In such a long arc type high pressure mercury discharge lamp, tantalum oxide Ta ₂ O ₅ , cerium oxide CeO ₂ , neodymium oxide Nd ₂ O ₃ , tin oxide SnO, is formed on the inner surface of the arc tube 1 made of quartz glass. Zirconium oxide Zr
The diffusion layer 7 for ultraviolet ray shielding is formed of at least one selected from O ₂ , zinc oxide ZnO, iron oxide Fe ₂ O ₃ , and vanadium oxide V ₂ O ₅ . Also in the case of such a configuration, the same effect as that of the first embodiment can be obtained.
Further, in the present invention, the arc tube is not limited to the both-end sealed type, and may have a one-end sealed type structure. Further, the high pressure discharge lamp of the present invention can be implemented not only in the light source device of the light projecting device but also in an ultraviolet irradiation device.

[0029]

As described above, according to the invention of claim 1, the inside of the arc tube is heated by heating the film of the selected metal oxide formed on the inner surface of the arc tube made of quartz glass.
The metal oxide UV layer is allowed to diffuse into
It absorbs or reflects ultraviolet rays and blocks them from going out. In addition, since the ultraviolet cut layer is formed by diffusing on the inner surface of the quartz arc tube, the ultraviolet cut material is not peeled off and the quartz glass is not exposed to ultraviolet rays, so that the distortion of the quartz glass does not increase.

According to the second aspect of the invention, the electrode is impregnated with thorium oxide ThO ₂ , and since this material is stable, it can be less likely to react with the ultraviolet blocking material, resulting in white turbidity. Is prevented, a decrease in light output is prevented, and the life is extended.

Further, according to the third aspect of the present invention, since the ultraviolet ray is not emitted from the arc tube, the outer tube having the ultraviolet ray blocking function is not required, and the outer tube-less lamp can be obtained. It is possible.

According to the invention of claim 4, since a short arc discharge lamp having a long life and without an outer tube can be used as a light source, it is effective as a point light source and the life characteristic of the light source device is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a short arc xenon lamp showing a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a light source device configured by incorporating the short arc xenon lamp into a reflector.

FIG. 3 is a characteristic diagram showing a relationship between light output and lighting time.

FIG. 4 is a configuration diagram of a long arc high pressure mercury discharge lamp showing a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bulb 2 ... Discharge space 3 ... Crushing sealing part 4 ... Metal foil conductor 5, 6 ... Electrode 7 ... Diffusion layer 20 ... Reflector

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01J 61/30 H01J 61/073

Claims (4)

(57) [Claims] 1. An arc tube made of quartz glass, an electrode sealed at the end of the arc tube, and tantalum oxide, cerium oxide, neodymium oxide, tin oxide, zirconium oxide formed on the inner surface of the arc tube. , By heating a metal oxide film of at least one selected from zinc oxide, iron oxide, and vanadium oxide.
A high-pressure discharge lamp comprising: a layer in which the metal oxide is diffused in the arc tube . 2. The electrode made of thorium oxide
The high pressure discharge lamp according to claim 1, wherein the high pressure discharge lamp is impregnated with a battery. 3. The high pressure discharge lamp according to claim 1, wherein the arc tube is an outer tube-less lamp which is not surrounded by an outer tube. 4. A light source device comprising: the high pressure discharge lamp according to claim 3; and an optical system for controlling and irradiating light emitted from the discharge lamp.