JP2001319618A - Ultrahigh-pressure mercury lamp and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrahigh-pressure mercury lamp having a long lifetime without lowering radiation intensity of light caused by blackening of inner wall of the luminescent bulb even when a halogen is introduced into an extremely small luminescent bulb in the form of an organic halide, and its manufacturing method. SOLUTION: Halogen is enclosed as an organic halide, and carbon 5 produced by decomposing the organic halide is made to deposit by pretreatment only on an inner wall of unused region B, where transmitting light is not used, out of the whole region transmitting light of the luminescent bulb 11. Besides, in the pretreatment, the unused region B of the luminescent bulb is locally heated to decompose the organic halide, and produced carbon is made to deposit only on the inner wall of unused region B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-high pressure mercury lamp used as a light source for a projector such as a liquid crystal projector or a DLP, and a method of manufacturing the lamp.

[0002]

2. Description of the Related Art As a projector device such as a liquid crystal projector device or a DLP, a light source device in which a short arc type discharge lamp is mounted in a concave reflecting mirror made of borosilicate glass is usually used. On top of that, it is required to project an image with uniform and sufficient color rendering properties, and as a light source lamp, a metal halide lamp with good color rendering properties in which mercury and a metal halide are sealed has conventionally been used. Was. In addition, since a reduction in the size and weight of the device is strongly required, the discharge lamp must also be reduced in size.

Recently, further miniaturization and the use of point light sources have been promoted, and a discharge lamp having an extremely short distance between electrodes has been required. However, in a metal halide lamp in which a metal whose excitation energy is lower than that of mercury is enclosed, when the distance between the electrodes becomes smaller than a certain level, the concentration of discharge is limited, and it is difficult to cope with a smaller point light source.

For this reason, recently, instead of the metal halide lamp, a short arc type ultra-high pressure mercury lamp which has a very high mercury vapor pressure, for example, 20 MPa or more at the time of lighting, has been used. In order to make the mercury vapor pressure at the time of lighting such a high value, for example, the internal volume is 300
0.15 mg / mm ³ or more of mercury is sealed in a small arc tube of ³ mm or less.
The spread of the arc can be suppressed, and the light output and the color rendering can be further improved. JP-A-2-148562 and JP-A-6-52830 disclose such ultra-high pressure mercury lamps.

[0005]

An ultra-high pressure mercury lamp used as a light source of a projector apparatus is required to have a large light output, excellent color rendering properties, and a long lamp life. Specifically, it is desirable that the radiation intensity of the light from the extra-high pressure mercury lamp be kept as constant as possible without decreasing or fluctuating during the use period of the projector device.

[0006] It is known to enclose a halogen together with mercury and a rare gas in an arc tube in order to prolong the lamp life of an ultra-high pressure mercury lamp. That is, at the time of lighting, a halogen cycle is generated in the arc tube, and the blackening of the inner wall of the arc tube due to the halogen cycle is suppressed, so that the radiation intensity of light can be kept constant for a long time.

Here, when enclosing halogen, for example, bromine, together with mercury and a rare gas in the arc tube, since the arc tube is extremely small, it is difficult to encapsulate bromine gas alone as halogen. Thus, the halogen is encapsulated as an organic halide. However, when bromine is encapsulated as an organic halide, the organic halide decomposes into carbon, hydrogen, hydrogen bromide, bromine, etc. at the time of high-temperature operation during lighting. A thin film adheres to the inner wall of the arc tube. Since the amount of organic substances mainly composed of carbon is not so large, if the conventional arc tube has a large arc tube, the amount of adhesion per unit area of the inner wall of the arc tube is small, which is not a problem.
^{In the case of} a small arc tube of ³ or less, the amount of adhesion per unit area of the inner wall of the arc tube becomes large and the light transmittance is reduced, so that the radiation intensity of light is reduced and the amount of adhesion becomes a nonnegligible level. is there.

For this reason, it is conceivable to enclose the halogen in the form of pellets such as mercury halide. Although carbon does not contribute to the emission characteristics of the discharge lamp at all, pellets such as mercury halide do not contain carbon, so that organic substances mainly containing carbon do not adhere to the inner wall of the arc tube. Here, in order to enclose in the form of a pellet, the arc tube has an internal volume of 300 mm ³ or less and is extremely small, so an ultra-small pellet is required. When encapsulating in the form of pellets, a large amount of halogen is encapsulated.
When the amount of halogen is more than 10 ⁻³ μmol / mm ³ , the transport speed of tungsten by the halogen cycle increases, and the electrode made of tungsten may be corroded at an early stage. The encapsulation would be much larger than the encapsulation limit described above. For this reason, the fact is that the only way to enclose halogen in an extremely small arc tube is to enclose it in the form of an organic halide.

Therefore, the present invention provides a method for reducing the emission intensity of light by blackening the inner wall of an arc tube even when halogen is sealed together with mercury and a rare gas in the form of an organic halide in an extremely small arc tube having an internal volume of 300 mm ³ or less. It is an object of the present invention to provide an ultra-high pressure mercury lamp having a long lamp life without a decrease and a method for manufacturing the same.

[0010]

Means for Solving the Problems To achieve the above object, the invention of claim 1 is to provide a light emitting tube having an inner volume of 300 mm ³ or less in a mercury and a rare gas and 10 ⁻³ μmol / mol.
In an ultra-high pressure mercury lamp in which halogen of not more than ³ mm is sealed, halogen is sealed as an organic halide, and light is transmitted through the light emitting tube, and among the light emitting tube inner walls, a non-use area that does not use transmitted light is used. Only in this case, a thin film of an organic substance mainly composed of carbon generated by decomposition of the organic halogen by the pretreatment is attached.

Further, according to the invention of claim 2, the internal volume is 300
mm ³ to less arc tube, mercury and rare gas and 10,
^{In a} method of manufacturing an ultra-high pressure mercury lamp in which a halogen of ^-3 μmol / mm ³ or less is sealed, an organic halide is sealed in an arc tube, and a light transmitted through the arc tube is not used in a region where light passes through the arc tube. The arc tube in the non-use area is locally heated to decompose the organic halide, and a thin film of an organic substance mainly composed of carbon is deposited only on the inner wall of the non-use area of the arc tube.

[0012]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 shows an optical device comprising an ultra-high pressure mercury lamp and a concave reflecting mirror. In FIG. 1, an arc tube 11 of a short arc type ultra-high pressure mercury lamp 10 is a substantially spherical body made of quartz glass. The product is 300 mm ³ or less. In the arc tube 11, a pair of electrodes, that is, an anode 13 and a cathode 14, are arranged to face each other. Further, in the arc tube 11, halogen of 10 ⁻³ μmol / mm ³ or less is sealed together with mercury and a rare gas. As described later, the halogen is encapsulated in the form of an organic halide at the time of manufacture.

At both ends of the arc tube 11, sealing portions 12 are integrally connected. The sealing portion 12 is formed by melting a quartz glass pipe extending from both ends of the arc tube 11 and depressurizing the inside thereof. Inside the sealing portion 12, electrodes 13 and 14 are provided. A molybdenum foil (not shown) for electrically connecting to the external lead rod 15 is embedded. The polarity of the anode 13 and the cathode 14 of the DC lighting type may be opposite to the state shown in FIG. 1, and further, the AC lighting type may be used.

To give specific numerical values of the ultra-high pressure mercury lamp 10, the amount of enclosed mercury is 0.16 mg / mm ³ ,
Argon as a rare gas is sealed at a pressure of 10 kPa, and bromine as a halogen is sealed at 2 × 10 ⁻⁴ μmol / mm ³ . The distance between the electrodes is 1.5 mm, the internal volume of the arc tube 11 is 120 mm ³ , the rated voltage is 75 V, and the rated power is 150 W. Naturally, the numerical examples are not limited to these, but in order to use the ultra-high pressure mercury lamp 10 as a light source lamp for a liquid crystal projector, the amount of mercury enclosed must be 0.15 mg / mm ³ or more. It is.

The concave reflecting mirror 20 is made of, for example, borosilicate glass, and the inside diameter of the front opening is as small as about 40 to 80 mm. The reflecting surface 21 of the concave reflecting mirror 20 is a rotating curved surface, and the surface thereof is made of titania having excellent reflection characteristics.
A deposited film of silica or the like is formed. A support cylinder 22 is formed on the top of the reflecting mirror 20, and one sealing portion 12 of the ultrahigh-pressure mercury lamp 10 is inserted into the support cylinder 22. The ultra-high pressure mercury lamp 10 has its axis coincident with the optical axis of the concave reflecting mirror 20 and the electrodes 13, 1 at the time of lighting.
The adhesive 2 filled in the support cylinder 22 is placed in a state where the arc luminescent spot formed between the four is located at the first focal point of the concave reflecting mirror 20.
3 is fixed to the concave reflecting mirror 20. Also, the front opening of the concave reflecting mirror 20 is covered with a light-transmitting glass plate 30 made of, for example, borosilicate glass so that when the ultrahigh-pressure mercury lamp 10 ruptures, the fragments do not scatter from the front opening. However, the light transmissive glass plate 30 is not always necessary. Further, the outer surface of the concave reflecting mirror 20 has a high toughness so that even if the concave reflecting mirror 20 is broken by an impact when the ultra-high pressure mercury lamp 10 ruptures, the fragments are not scattered. Anti-scattering film 4 made of molecular material
0 is formed.

As described above, the ultra-high pressure mercury lamp 10 is surrounded by the concave reflecting mirror 20, and light emitted from the ultra-high pressure mercury lamp 10 is reflected by the reflecting surface 21 of the concave reflecting mirror 20.
Not all light transmitted through the arc tube 11 of the ultra-high pressure mercury lamp 10 is used by being reflected by the reflecting surface 21. As shown in FIG. Radiation light within a predetermined emission angle range around a point is used. That is, only the light transmitted through the area A (use area) at the center of the arc tube 11 shown in FIG. 2 is used by being reflected by the reflection surface 21, and the area B (non-use area) at the end of the arc tube 11 is used. The transmitted light is not used.

Here, in the ultra-high pressure mercury lamp 10 of the present invention, only the inner wall of the non-use area B of the arc tube 11 is subjected to the pretreatment, as shown by a dotted line in FIG.
The organic thin film 5 mainly composed of carbon, which is generated when the enclosed organic halide is decomposed, is slightly blackened. However, the thin film 5 does not adhere to the inner wall of the use region A of the arc tube 11, and the light transmitted through the use region A of the arc tube 11, that is, the light substantially radiated from the ultrahigh pressure mercury lamp 10 is a thin film. 5, the light can pass through the arc tube 11 with a large transmittance.

FIG. 3 shows a pretreatment method for attaching the thin film 5 only to the inner wall of the non-use area B of the arc tube 11. That is, the ultra-high pressure mercury lamp 10 in which the organic halide is sealed before the first lighting is set to the vertical position, the lower part is cooled with the cooling water W, and the vicinity of the base of the upper electrode, that is, the unused area of the arc tube 11 is used. Gas burner GB above B
For local heating. When the encapsulated organic halide is, for example, CH ₂ Br ₂ , it is heated at about 950 ° C., and this heating decomposes CH ₂ Br ₂ , and the generated organic matter mainly composed of carbon emits light as shown in FIG. It adheres only to the non-use area B of the tube 11 and does not adhere to the use area A that is remote from the heating site. The reason that the lower part of the ultrahigh pressure mercury lamp 10 is cooled with the cooling water W is that when the gas is heated by the gas burner GB, the mercury staying below the arc tube evaporates and the pressure inside the arc tube is prevented from increasing remarkably. That's why.

Next, the ultra-high pressure of the above-described embodiment, in which a thin film of an organic substance mainly composed of carbon generated when an organic halide is decomposed is deposited only on the non-use area B of the arc tube 11 by the above pretreatment. The mercury lamp 10 and, as a comparative example, the organic halide is decomposed by lighting aging to deposit this thin film on the entire inner wall of the arc tube 11, and the other conditions are the same as those of the above-described embodiment. Was examined for the spectral transmittance when transmitted through the use area A of the arc tube 11. FIG. 4 shows the results.

As can be seen from FIG. 4, in the visible light range, the transmittance of the lamp of the embodiment is about 93% or more.
The difference in transmittance from the lamp of the comparative example is about 2 to 4%.
And a significant difference was clearly recognized. That is, since the lamp of the example has a higher initial transmittance than the lamp of the comparative example, it takes a longer time for the transmittance to decrease to a transmittance (for example, 80%) which is regarded as the limit of the lamp life, and accordingly, the lamp Long life.

[0021]

As described above, according to the first aspect of the present invention, even if the halogen is sealed together with mercury and a rare gas in the form of an organic halide in an extremely small arc tube having an inner volume of 300 mm ³ or less. An ultra-high pressure mercury lamp with a long lamp life can be obtained without reducing the radiation intensity of light due to blackening of the inner wall of the arc tube. Claim 2
According to the invention, the ultra-high pressure mercury lamp of the invention of claim 1 can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an optical device including an extra-high pressure mercury lamp and a concave reflecting mirror.

FIG. 2 is a sectional view of the first embodiment.

FIG. 3 is an explanatory view of an embodiment according to claim 2;

FIG. 4 is a diagram showing spectral transmittance curves of an example lamp and a comparative example lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ultra-high pressure mercury lamp 11 Arc tube 12 Sealing tube 13 Anode 14 Cathode 16 Thin film 20 Concave reflector A Use area B Non-use area GB Gas burner W Cooling water

Claims (2)

[Claims] To 1. A light emitting inner volume of 300 mm ³ or less tubes, mercury and rare gas, and at ^{10 -3 μmol} / mm ³ or less of the extra-high pressure mercury lamp halogen is enclosed, the halogen enclosed as an organic halide In the region where light passes through the arc tube, only the inner wall of the arc tube, which does not use the transmitted light, is used only for the inner wall of the arc tube. An ultra-high pressure mercury lamp having a thin film attached. To 2. A light-emitting inner volume of 300 mm ³ or less tubes, in mercury and gas diluted, and ^{10 -3 μmol} / mm ³ the following method for producing ultra-high pressure mercury lamp halogen is enclosed, organic in the arc tube A halide is sealed, and in a region where light passes through the arc tube, an arc tube in a non-use area that does not use transmitted light is locally heated to decompose the organic halide and mainly generate carbon. A method for manufacturing an ultra-high pressure mercury lamp, characterized in that a thin film of an organic substance is adhered only to the inner wall of the unused area of the arc tube.