JP2004178979A - High-pressure discharge lamp and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-pressure discharge lamp wherein a proper amount of halogen elements can be accurately filled. <P>SOLUTION: A pair of electrodes 2a, 2b are disposed in an airtightly sealed quartz bulb 101 to form this high-pressure discharge lamp, and as to the electrodes 2a, 2b, halogen elements are struck in the portions having prescribed depths from the surfaces of the respective tip parts 21a, 21b of the electrodes. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a discharge lamp, and more particularly, to a high-pressure discharge lamp using a halogen cycle and a method for manufacturing the same.
[0002]
[Prior art]
High-pressure discharge lamps, such as xenon lamps, high-pressure mercury lamps, and metal halide lamps, are widely used as light sources for copiers and projectors because of their high luminance and good color rendering properties.
[0003]
Normally, a high pressure discharge lamp has a structure in which a halogen cycle is used to prevent blackening of a bulb wall (see Patent Document 1). FIG. 4 shows a schematic configuration of the high-pressure discharge lamp. Hereinafter, the configuration and operation of the high-pressure discharge lamp and the principle of the halogen cycle will be described.
[0004]
Referring to FIG. 4, this high-pressure discharge lamp has a structure in which a pair of electrodes 102a and 102b made of, for example, tungsten are opposed to each other in a tubular quartz glass bulb (hereinafter referred to as "quartz bulb") 101. Has become. The electrodes 102a and 102b are provided with cooling coils 104a and 104b at the distal ends, and the base sides are joined to Mo (molybdenum) foils 103a and 103b. Both ends of the quartz bulb 101 are hermetically sealed together with the bases of the electrodes 102a and 102b and the Mo foils 103a and 103b. The electrodes 102a, 102b and the Mo foils 103a, 103b are joined by, for example, welding. In the quartz bulb 101, a small amount of halogen gas is previously sealed together with, for example, mercury (Hg) and an inert gas necessary for maintaining discharge light emission.
[0005]
In the above-mentioned high-pressure discharge lamp, external lead wires (not shown) are bonded to Mo foils 103a and 103b sealed at both ends of the quartz bulb 101, and a predetermined trigger voltage is applied to these external lead wires. . When a trigger voltage is applied, a glow discharge is induced between the two electrodes 102a and 102b in an atmosphere of an inert gas in the quartz bulb 101, whereby the enclosed mercury is vaporized, and a plasma is generated in a high-pressure mercury gas. Discharge occurs.
[0006]
In the above operation state, a sputtering phenomenon occurs due to mercury ions and electrons at the time of plasma discharge, and tungsten atoms (ionized state) are released from both electrodes 102a and 102b. When the tungsten atoms thus released adhere to the inner wall of the quartz bulb 101, the bulb wall becomes black.
[0007]
In the halogen cycle, tungsten atoms (ionized state) released from both electrodes 102a and 102b are combined with previously sealed halogen atoms to form tungsten halide. This tungsten halide floats in the quartz bulb 101 by thermal convection, and is exposed to a high temperature near the electrodes 102a and 102b, thereby being separated into tungsten atoms and halogen atoms. The separated tungsten atoms adhere to the electrodes 102a and 102b, whereby the electrodes are regenerated. On the other hand, the separated halogen atoms again contribute to tungsten halide formation. The repetition of this series of reactions is a halogen cycle, which prevents the above-described blackening of the valve wall.
[0008]
[Patent Document 1]
JP, 2002-124210, A
[Problems to be solved by the invention]
However, the conventional high-pressure discharge lamp described above requires a large-sized gas supply device and abatement equipment in order to handle halogen gas. For this reason, the manufacturing equipment has become very expensive.
[0010]
The efficiency of the halogen cycle is
(1) The amount of halogen atoms is smaller than the amount of released tungsten atoms.
[0011]
(2) Since the amount of the impurity gas in the quartz bulb is large, the probability that tungsten atoms are bonded to halogen atoms is reduced.
[0012]
(3) Depending on operating conditions, the amount of sputtered tungsten atoms increases.
And other factors. In order to carry out the halogen cycle efficiently, it is necessary to accurately enclose an appropriate amount of a halogen element in the quartz bulb. At present, encapsulation of a halogen element in a quartz bulb is performed by mixing the halogen element with an inert gas and encapsulating the mixed gas in the quartz bulb using a known exhaust stand device. At present, the amount of halogen gas sealed in the quartz bulb varies by several% due to poor mounting accuracy of the quartz bulb to the exhaust stand apparatus and accuracy of enclosing the mixed gas. For this reason, it has been difficult to seal an appropriate amount of halogen gas into a small-sized lamp such as an ultra-high pressure mercury lamp with high accuracy.
[0013]
SUMMARY OF THE INVENTION An object of the present invention is to provide a high-pressure discharge lamp capable of solving the above-mentioned problems and enclosing an appropriate amount of a halogen element with high accuracy, and a method of manufacturing the same.
[0014]
[Means for Solving the Problems]
The high-pressure discharge lamp of the present invention is a high-pressure discharge lamp in which a pair of electrodes is disposed in a hermetically sealed glass bulb, and the pair of electrodes has a predetermined amount of a halogen element in at least one of the electrodes. It is characterized by being added. According to this configuration, the addition amount of the halogen element to the electrode can be controlled in units of the number of atoms, so that a desired amount of the halogen element can be easily and accurately sealed in the bulb. .
[0015]
In the above case, the pair of electrodes may be arranged such that the tips are opposed to each other, and the halogen element may be implanted into a portion at a predetermined depth from the surface of each tip. According to this configuration, the amount of the halogen element sealed in the bulb can be accurately controlled because there is no thermal desorption of the halogen element during the electrode heat treatment at the time of assembling the lamp.
[0016]
Further, the amount of the halogen element is in the range of 10 ⁻⁸ to 10 ⁻² μmol / mm ³ , more preferably 10 ⁻⁷ to 10 ⁻⁴ μmol / mm ³ when released into the glass bulb. It may be a range. This allows the halogen cycle to function more efficiently.
[0017]
A method of manufacturing a high-pressure discharge lamp according to the present invention is characterized in that a predetermined amount of a halogen element is added to at least one of a pair of electrodes, and then the pair of electrodes is incorporated in a glass bulb. According to this method, since there is no need to handle halogen gas, it is not necessary to introduce a very expensive and large-sized equipment related to halogen gas (for example, a gas supply device or an exclusion device).
[0018]
In the above case, the step of adding the halogen element may include an ion implantation step of implanting the halogen element into a portion at a predetermined depth from the surface of the tip of each of the pair of electrodes by ion implantation. According to this method, the amount of the halogen element sealed in the bulb can be accurately controlled because there is no thermal desorption of the halogen element in the electrode heat treatment at the time of assembling the lamp.
[0019]
Further, the amount of the halogen element is in the range of 10 ⁻⁸ to 10 ⁻² μmol / mm ³ , more preferably 10 ⁻⁷ to 10 ⁻⁴ μmol / mm ³ when released into the glass bulb. It may be a range. This allows the halogen cycle to function more efficiently.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a schematic diagram showing a main part of a high-pressure discharge lamp according to one embodiment of the present invention. The high-pressure discharge lamp of the present embodiment is basically shown in FIG. 4 except that a predetermined amount of a halogen element is added to the surface of each of the tips 21a and 21b of the electrodes 2a and 2b by ion implantation. It is the same as the conventional one. In FIG. 1, the same parts as those of the related art are denoted by the same reference numerals.
[0022]
The electrodes 2a and 2b are made of, for example, tungsten, and are arranged in the quartz bulb 101 such that their tips 21a and 21b face each other. The bases of the electrodes 2a and 2b are joined to Mo foils 103a and 103b, respectively, and both ends of the quartz bulb 101 are hermetically sealed near the joint. Cooling coils 104a and 104b, each of which is formed by densely winding a wire made of, for example, tungsten, are provided adjacent to each of the tips 21a and 21b. The tip portions 21a and 21b are formed by melting a part of an electrode and a part of a cooling coil with a YAG laser or the like, and have a smooth hemispherical (frustoconical shape) surface. I have. Examples of the halogen elements (ions) implanted on the surfaces of the tips 21a and 21b include chlorine (Cl ⁻ ), bromine (Br ⁻ ), and iodine (I ⁻ ).
[0023]
The quartz bulb 101 is filled with, for example, mercury (Hg) and an inert gas (for example, argon (Ar), xenon (Xe), etc.) necessary for maintaining the discharge light emission. Is not encapsulated. Instead of filling the halogen gas, a halogen element is added to the surfaces of the tips 21a and 21b of the electrodes 2a and 2b. The amount of mercury enclosed is desirably in the range of, for example, 0.12 to 0.30 mg / mm ³ . The amount of the inert gas charged is preferably about 20 kPa in partial pressure.
[0024]
In the high-pressure discharge lamp of the present embodiment, when a predetermined trigger voltage is applied to the external lead wires (not shown) connected to the Mo foils 103a and 103b, both of them are placed under an inert gas atmosphere in the quartz bulb 101. A glow discharge is induced between the electrodes 2a and 2b, whereby the enclosed mercury is vaporized and a plasma discharge occurs in a high-pressure mercury gas. Simultaneously with the application of the trigger voltage, both electrodes 2a and 2b are instantaneously heated to a predetermined temperature (2000 ° C. or higher), and halogen elements (ions) are emitted from the respective tips 21a and 21b. A halogen cycle is performed by the halogen element (ion) thus released, and blackening of the bulb wall is prevented.
[0025]
The amount of the halogen element (ion) released into the quartz bulb 101 is in a range that allows the halogen cycle to function efficiently, for example, in the range of 10 ⁻⁸ to 10 ⁻² μmol / mm ³ , more preferably, in the range of 10 ⁻⁷ to 10 ⁻⁷ μmol / mm ^3. It is in the range of 10 ⁻⁴ μmol / mm ³ . If the emission amount of the halogen element (ion) is out of the range, blackening occurs, and stable lamp operation becomes difficult. In the present embodiment, by controlling the ion implantation of the halogen element into the electrodes 2a and 2b, the emission amount of the halogen element (ion) in such a preferable range is realized.
[0026]
Hereinafter, ion implantation of a halogen element into the electrodes 2a and 2b will be described.
[0027]
Since the halogen element added to the electrodes 2a and 2b is desorbed by heat, when the halogen element is ion-implanted into the electrodes 2a and 2b, it is necessary to consider a heat treatment performed at the time of assembling the lamp. Specifically, since the electrode heat treatment temperature in such a heat treatment step is about 1100 ° C. at the maximum, the ion-implanted halogen element is sufficiently higher than the electrode heat treatment temperature and the temperature during lamp operation ( For example, it is necessary to release most of them below about 2000 ° C.).
[0028]
When a halogen element is ion-implanted, for example, to a depth of about 50 nm from the surface, the implanted halogen element is not emitted at a temperature of about 1100 ° C. Released. However, when the implantation depth of the halogen element is 20 nm or less from the surface, the implanted halogen element is desorbed at a temperature of about 1100 ° C. Experimentally, the critical point of the implantation depth at which the desorption of the halogen element does not occur at a temperature of about 1100 ° C. is 30 to 40 nm when the electrode material is tungsten, and at least at the implantation depth above this critical point. It is necessary to ion-implant a halogen element. For example, when bromine (Br) ions are implanted into a tungsten electrode at an implantation depth of 50 nm, the implanted bromine (Br) ions may remain in the electrode with a probability of 99.9% after the electrode heat treatment. Confirmed in experiments up to.
[0029]
The implantation depth can be controlled by the ion implantation voltage (acceleration voltage). FIG. 2 shows the relationship between implantation voltage and implantation depth when bromine (Br) is ion-implanted into a tungsten electrode. As can be seen from the relationship shown in FIG. 2, if the injection voltage is low, the injection depth becomes shallow, and if the injection voltage is high, the injection depth becomes deep. As described above, by controlling the implantation voltage, the halogen element can be ion-implanted at a desired implantation depth. For example, by setting the implantation voltage to about 300 keV, the implantation depth can be reduced to about 50 nm from the surface.
[0030]
In the high-pressure discharge lamp of the present embodiment, the implantation depth of the halogen element implanted into the tips 21a, 21b of the electrodes 2a, 2b is about 50 nm from the surface. For this reason, the ion-implanted halogen element does not desorb even at the electrode heat treatment temperature in the lamp assembling process, and almost all of the halogen element is released at the temperature during lamp operation (for example, about 2000 ° C.). In this case, the amount of the halogen element (ion) released into the quartz bulb 101 is determined according to the amount of the ion-implanted halogen element. Therefore, if the injection amount of the halogen element is controlled in accordance with the volume of the quartz bulb 101, the amount of the halogen element (ion) released into the quartz bulb 101 is in the range of 10 ⁻⁸ to 10 ⁻² μmol / mm ³ ( More preferably, it can be suppressed within the range of 10 ⁻⁷ to 10 ⁻⁴ μmol / mm ³ ).
[0031]
For example, when manufacturing a high-pressure discharge lamp using a quartz bulb 101 having a volume of 150 mm ³ , 9 × 10 ¹³ pieces (this is expressed in terms of moles) are provided at the tips 21 a and 21 b of the electrodes 2 a and 2 b made of tungsten. (Corresponding to 1.5 × 10 ⁻⁴ μmol) of bromine (Br) ions at a depth of 50 nm from the surface to reduce the halogen element content in the quartz bulb 101 to approximately 1 × 10 4 during lamp operation. ⁻⁴ μmol / mm ³ .
[0032]
As described above, according to the high-pressure discharge lamp of the present embodiment, the content of the halogen element in the quartz bulb 101 during the lamp operation can be controlled by the amount of the halogen element ion-implanted. In this case, since the injection amount can be controlled in the unit of the number of atoms, a desired amount of a halogen element can be easily and precisely sealed in the quartz bulb 101.
[0033]
Next, a method for manufacturing the high-pressure discharge lamp of the present embodiment will be specifically described. FIG. 3 shows a manufacturing process of the high-pressure discharge lamp shown in FIG. Hereinafter, the manufacturing process will be described with reference to FIGS.
[0034]
(Bulb forming step: S1)
Using a quartz glass tube, a quartz bulb 101 having a bulge at the center is manufactured. At this point, both ends of the quartz bulb 101 have not yet been sealed.
[0035]
(Electrode assembly process: S2)
Cooling coils 104 and 104b made of a predetermined metal are attached to the rod-like electrodes 2a and 2b made of tungsten near the respective tips 21a and 21b, and the bases are welded to the Mo foils 103a and 103b. Further, a lead wire is connected to each of the Mo foils 103a and 103b. Then, a halogen element is ion-implanted into the respective tips 21a and 21b of the electrodes 2a and 2b from the surface to a depth of 50 nm using an existing ion implantation apparatus. Thus, a pair of electrode assemblies into which the halogen element is ion-implanted is manufactured. Note that the step of ion-implanting a halogen element may be performed at any timing as long as there is no thermal problem (desorption due to heat).
[0036]
(First electrode assembling step: S3)
One of the pair of electrode assemblies (hereinafter, referred to as a first electrode assembly) manufactured in the electrode assembling step is inserted through an opening (hereinafter, referred to as an opening A) at one end of the quartz bulb 101 and arranged at a predetermined position. I do.
[0037]
(First exhaust step: S4)
The opening A of the quartz bulb 101 in which the first electrode assembly is disposed is attached to a well-known evacuation table, and evacuation is performed to, for example, a vacuum of 10 ⁻² Pa or less. Thereafter, an inert gas is introduced, and the end of the opening A is completely closed.
[0038]
(First sealing step: S5)
The sealed portion of the quartz bulb 101, which has been sealed off in the first evacuation step, is heated by a local heating jig such as a gas burner, and the lead wire, Mo foil, and electrode base of the first electrode assembly are sealed. Buried in
[0039]
(Mercury introduction step: S6)
A predetermined amount of mercury (Hg) is introduced from an opening at the other end of the quartz bulb 104 (hereinafter referred to as opening B) using a dedicated jig.
[0040]
(Second electrode assembling step: S7)
The other electrode assembly (hereinafter, referred to as a second electrode assembly) is inserted through the opening B of the quartz bulb 101, and the electrodes (electrodes 2a, 2b) of the first and second electrode assemblies are inserted using a known jig. Are arranged at predetermined intervals.
[0041]
(Second exhaust step: S8)
The opening B side of the quartz valve 101 is attached to an exhaust table, and the exhaust is performed until the oxygen partial pressure in the valve reaches, for example, 2.0 × 10 ⁻³ Pa.
[0042]
(Inert gas introduction step: S9)
Through the opening B of the quartz bulb 101, an inert gas, for example, an argon gas having a partial pressure of 20 kPa is introduced as an inert gas. Conventionally, a halogen gas is introduced after the inert gas introduction step, but such a halogen gas introduction step is unnecessary in the production of the high-pressure discharge lamp of the present embodiment. After the introduction of the inert gas, the end of the opening B of the quartz bulb 101 is sealed off with a gas burner.
[0043]
(Second sealing step: S10)
The sealed portion (opening B side) of the quartz bulb 101 is heated by a local heating jig such as a gas burner, and the lead wire, Mo foil, and electrode base of the second electrode assembly are embedded in the sealed portion.
[0044]
In the above-described manufacturing process, the respective tips 21a and 21b of the electrodes 2a and 2b receive a thermal history of 1000 ° C. or less several times, but the halogen element is ion-implanted to a depth of about 50 nm from the surface. Almost no thermal desorption occurs in their thermal history.
[0045]
According to the above-described manufacturing process, there is no need to handle halogen gas at the time of assembling the lamp, and therefore, equipment related to a very expensive and large halogen gas used conventionally (for example, a gas supply device and an exclusion device). Need to be introduced. Therefore, production on a very compact production line becomes possible.
[0046]
Note that the above-described manufacturing process is an example, and the process may be appropriately replaced. For example, the order of the mercury introduction step and the inert gas introduction step may be reversed.
[0047]
In the embodiment described above, the electrode for performing ion implantation may be only one of the pair of electrodes.
[0048]
If a predetermined amount of a halogen element is added to the electrode and the content of the halogen element in the quartz bulb 101 can be controlled to a desired value, any addition method other than ion implantation may be used. May be used. For example, a predetermined amount of a halogen element may be added to the electrode by using a thermal method often used in a semiconductor manufacturing process (such as addition in a molten state or thermal diffusion). In this case, since the halogen element is added to the entire electrode, the amount of the halogen element released at the time of lamp operation after the halogen element released by heat in the assembly process is released is determined in advance by an experiment. It is necessary to obtain it and estimate the optimum amount of addition from the result.
[0049]
Further, the pair of electrodes is not limited to the structure shown in FIG. 1, but may be applied to a high-pressure discharge lamp, and may have any shape and structure as long as a halogen element can be added. May be used.
[0050]
【The invention's effect】
As described above, according to the present invention, a desired amount of a halogen element is easily and precisely enclosed in a quartz bulb by controlling the addition amount of a halogen element to an electrode in units of the number of atoms. be able to. As a result, it is possible to provide a high-pressure discharge lamp with a stable operation, which has a very small variation in troubles such as blackening.
[0051]
Furthermore, according to the present invention, since there is no need to handle halogen gas, it is not necessary to introduce very expensive and large-sized equipment related to halogen gas (for example, a gas supply device or an exclusion device). Therefore, the production of the lamp can be performed with a more compact and less expensive manufacturing equipment than the conventional one.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a main part of a high-pressure discharge lamp according to an embodiment of the present invention.
FIG. 2 is a graph showing a relationship between an injection voltage and an injection depth in the high-pressure discharge lamp shown in FIG.
FIG. 3 is a process chart showing a series of manufacturing procedures of the high-pressure discharge lamp shown in FIG.
FIG. 4 is a cross-sectional view schematically showing a schematic configuration of a conventional high-pressure discharge lamp.
[Explanation of symbols]
2a, 2b, 102a, 102b Electrodes 21a, 21b Tip 101 Quartz bulb 103a, 103b Mo foil 104a, 104b Cooling coil

Claims (10)

A high-pressure discharge lamp in which a pair of electrodes are arranged in a hermetically sealed glass bulb,
The high-pressure discharge lamp according to claim 1, wherein a predetermined amount of a halogen element is added to at least one of the pair of electrodes. The said pair of electrodes are arrange | positioned so that the said front-end | tip part may mutually oppose, The said halogen element is implanted in the part of predetermined depth from the surface of each front-end | tip part, The said 1st element | device The high-pressure discharge lamp according to claim 1. ^3. The high-pressure discharge lamp according to claim 1, wherein the amount of the halogen element is in a range of 10 ⁻⁸ to 10 ⁻² μmol / mm ³ when released into the glass bulb. 4. ^3. The high-pressure discharge lamp according to claim 1, wherein the amount of the halogen element is in a range of 10 ⁻⁷ to 10 ⁻⁴ μmol / mm ^{3 when} the halogen element is released into the glass bulb. ⁴ . The high-pressure discharge lamp according to any one of claims 1 to 4, wherein the halogen element is one of chlorine, bromine, and iodine. A method for manufacturing a high-pressure discharge lamp, comprising adding a predetermined amount of a halogen element to at least one of a pair of electrodes, and then incorporating the pair of electrodes into a glass bulb. 7. The method according to claim 6, wherein the step of adding the halogen element includes an ion implantation step of implanting the halogen element by ion implantation into a portion at a predetermined depth from a surface of each of the pair of electrodes. A method for manufacturing the high-pressure discharge lamp according to the above. 8. The high-pressure discharge lamp according to claim 6, wherein the amount of the halogen element is in a range of 10 ⁻⁸ to 10 ⁻² μmol / mm ³ when released into the glass bulb. 9. Production method. 8. The high-pressure discharge lamp according to claim 6, wherein the amount of the halogen element is in a range of 10 ⁻⁷ to 10 ⁻⁴ μmol / mm ³ when released in the glass bulb. 9. Production method. The method according to any one of claims 6 to 9, wherein the halogen element is any of chlorine, bromine, and iodine.

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