JP2004152534A - Discharge tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge tube enhancing luminescent intensity by a simple structure. <P>SOLUTION: In this discharge tube, a first substrate 12 made of ultraviolet ray transmission glass is faced to a second substrate 14 made of an insulating material, an envelope 18 is formed by sealing peripheries of both the substrates 12, 14, a discharge space 20 is formed by filling ultraviolet ray emission gas in the envelop 18, an outer electrode 22 is installed on the outer surface of the second substrate 14, an inner electrode 24 is installed on the inner surface 12a of the first substrate 12, a through hole 26 passing through the second substrate 14 and the outer electrode 22 is formed, the through hole 26 is covered with a cap-like glass tube whose one end is sealed for airtightly blocking, and the outer electrode 22 is airtightly communicated with the discharge space 20 through the through hole 26. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a discharge tube that emits light such as ultraviolet rays by generating a discharge in a discharge space filled with a discharge gas by applying a voltage to a pair of electrodes. Discharge tube which can be improved.
[0002]
[Prior art]
FIG. 5 shows an example of a conventional discharge tube for emitting ultraviolet light. The discharge tube 60 includes a first substrate 62 made of an ultraviolet transmitting glass and a second substrate 64 made of an insulating material. The two substrates 62 and 64 are opposed to each other with a predetermined gap therebetween, and the peripheral edges of both substrates 62 and 64 are hermetically sealed via a sealing material 66 such as low-melting glass to form an envelope 68. A discharge space 70 is formed in the envelope 68 by filling an ultraviolet radiation gas obtained by mixing argon and mercury or an ultraviolet radiation gas mainly composed of xenon.
On the inner surface 64a of the second substrate 64, a pair of band-shaped internal electrodes 72, 72 are juxtaposed with a predetermined gap.
[0003]
In the discharge tube 60, when a DC voltage is applied between the pair of internal electrodes 72, 72, a discharge is generated in the discharge space 70 and electrons are emitted, and the electrons collide with the ultraviolet radiation gas. Ultraviolet light of various wavelengths is generated. The generated ultraviolet light is transmitted through the first substrate 62 made of ultraviolet transmitting glass and is emitted to the outside of the envelope 68.
[0004]
By the way, in the discharge tube 60, a DC voltage is applied between the internal electrodes 72, 72 arranged in the discharge space 70 to generate a discharge, but the discharge is generated on all surfaces of the internal electrodes 72, 72. Since it is necessary to pass a large current in order to generate, a high DC voltage had to be applied. In this case, if a high-voltage DC voltage is continuously applied, the power consumption becomes too large and it is not practical. Therefore, conventionally, a DC pulse voltage having a large peak voltage value is applied to the internal electrodes 72 and 72. Was producing a discharge.
However, in the driving method in which a DC pulse voltage is applied to generate a discharge, no discharge is generated during a period in which the DC pulse voltage is not applied. Also, while the DC pulse voltage is being applied, the discharge is generated on the entire surfaces of the internal electrodes 72 and 72 only for a moment (for example, 1 μS) when the DC pulse voltage is applied. Only a partial discharge is generated between the internal electrodes 72,72. For this reason, the discharge tube 60 of the direct-current drive system necessarily has a low luminous intensity of ultraviolet rays radiated from the discharge tube 60.
[0005]
Further, in the discharge tube 60, since the internal electrodes 72, 72 are disposed in the discharge space 70, the internal electrodes 72, 72 are sputtered by charged particles such as ions discharged by the discharge and deteriorate. And the service life was poor.
Further, since the sputtered material (internal electrode constituent material) spattered and scattered from the internal electrodes 72, 72 adheres to the inner surface of the first substrate 62, the transmission of ultraviolet rays to the outside of the envelope 68 is inhibited, and the emission of ultraviolet rays is performed. This resulted in a decrease in strength.
[0006]
For this reason, as disclosed in Japanese Patent Application Laid-Open No. Hei 10-222033, an AC-driven discharge tube having lower power consumption and longer life than the DC-driven discharge tube 60 is conventionally used. I have.
FIG. 6 shows an example of such an AC-driven discharge tube. In the discharge tube 80, a pair of strip-shaped external electrodes 82, 82 are provided on an outer surface 62 a of a first substrate 62 with a predetermined gap. They are arranged side by side.
In the discharge tube 80, when an AC voltage is applied to the pair of external electrodes 82, a discharge is generated in the discharge space 70 via the first substrate 62, which is a dielectric, and electrons are emitted. The electrons collide with the ultraviolet emitting gas to generate ultraviolet rays of various wavelengths. The generated ultraviolet light passes through the first substrate 62 made of the ultraviolet transmitting glass and is emitted to the outside of the envelope 68.
[0007]
The discharge tube 80 generates a discharge by applying an AC voltage to the external electrodes 82, 82 arranged with a dielectric (a first substrate 62) having electric charges accumulated on the surface thereof, The discharge can be generated at a lower voltage than the discharge tube 60 of the DC drive system. Therefore, unlike the discharge tube 60 of the DC drive system, the discharge tube 80 of the AC drive system does not need to apply a pulse current for reducing power consumption, and can continuously generate a discharge. Therefore, it is possible to increase the emission intensity of the ultraviolet light radiated as compared with the discharge tube 60.
In addition, since no electrodes are arranged in the discharge space 70, the electrodes are not deteriorated by sputtering and have a long life, and the sputtered substance does not adhere to the inner surface of the first substrate 62. The transmission of ultraviolet rays to the outside of the enclosure 68 is not hindered.
[0008]
FIG. 7 is a graph showing, with time, the ultraviolet light emission intensity of the discharge tube 10 according to the present invention, the discharge tube 60 of the DC drive system, and the discharge tube 80 of the AC drive system, which will be described later. As is clear from FIG. 7, the discharge tube 80 of the AC drive system (FIG. 7B) can obtain a higher emission intensity than the discharge tube 60 of the DC drive system (A in FIG. 7).
[Patent Document 1]
JP-A-10-222093
[Problems to be solved by the invention]
As described above, by using the discharge tube 80 of the AC drive system, it is possible to realize a relatively large emission intensity.
However, the emission intensity of the discharge tube 80 of the AC drive system is not always at a satisfactory level, and a discharge tube having a higher emission intensity has been desired.
[0010]
SUMMARY OF THE INVENTION The present invention has been made to meet the above-mentioned demands, and an object of the present invention is to realize a discharge tube capable of improving light emission intensity with a simple structure.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a discharge tube according to the present invention forms a discharge space by filling a discharge gas into an envelope made of a dielectric, and forms an external electrode on an outer surface of the envelope. At the same time, an internal electrode is formed on the inner surface of the envelope, a through hole is formed through the envelope, and the external electrode and the discharge space are air-tightly communicated through the through hole. It is characterized by.
[0012]
In the discharge tube according to the present invention, the external electrode is formed on the outer surface of the envelope, the internal electrode is formed on the inner surface of the envelope, and the external electrode is formed through the through hole formed in the envelope. The discharge space can be communicated with the discharge space in an airtight state, so that the emission intensity can be improved as compared with the conventional discharge tubes 60 and 80.
That is, first, the external electrodes are formed on the outer surface of the envelope, and the internal electrodes are formed on the inner surface of the envelope. A DC discharge with good efficiency is generated. In this case, the discharge is generated on substantially the entire surface of the internal electrode while the voltage is applied, so that the emission intensity of the discharge tube can be improved.
In addition, by communicating one of the external electrodes and the discharge space in a gas-tight manner through the through hole formed in the envelope, a large amount of electric charge is accumulated on the inner wall of the through hole, and as a result, Since the discharge current at the time of applying the voltage is increased, the light emission intensity of the discharge tube can be improved.
[0013]
In the envelope, for example, a first substrate made of an ultraviolet transmitting glass and a second substrate made of an insulating material are opposed to each other with a predetermined gap therebetween, and the peripheral edges of both substrates are hermetically sealed. In this case, the envelope is filled with an ultraviolet radiation gas as a discharge gas to form a discharge space, and the outer surface of the first substrate and / or the second substrate is formed on the outer surface of the first substrate and / or the second substrate. An electrode is formed, the internal electrode is formed on the inner surface of the first substrate and / or the second substrate, and a through-hole is formed through the substrate on which the external electrode is formed. The external electrode and the discharge space are communicated in an airtight manner through the through hole.
[0014]
The diameter of the through hole is preferably set to 0.2 mm to 1.0 mm.
That is, when the diameter of the through hole is smaller than 0.2 mm, the amount of electric charge accumulated on the inner wall of the through hole is small, so that the emission intensity of the discharge tube cannot be effectively improved. Is larger than 1.0 mm, when a DC discharge is generated, the external electrodes are sputtered by charged particles passing through the through-holes, and the external electrodes are likely to be deteriorated.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a discharge tube according to the present invention will be described with reference to the drawings.
FIGS. 1 and 2 show a discharge tube 10 for emitting ultraviolet light according to the present invention. The discharge tube 10 comprises a first substrate 12 made of an ultraviolet transmitting glass such as quartz glass and an insulating material such as glass. A second substrate 14 made of a material is opposed to the second substrate 14 with a predetermined gap therebetween, and the peripheral edges of the two substrates 12 and 14 are hermetically sealed via a sealing material 16 such as a low melting point glass. By forming an envelope 18 having a shape, and further filling the envelope 18 with an ultraviolet radiation gas obtained by mixing argon and mercury, or an ultraviolet radiation gas mainly containing xenon, The discharge space 20 is formed in the vessel 18.
[0016]
On the outer surface 14a of the second substrate 14, a band-shaped external electrode 22 made of silver paste, a transparent NESA film (SnO ₂ ), or the like is adhered and formed.
On the inner surface 12a of the first substrate 12, a band-shaped internal electrode 24 made of a 42-6 alloy, an Fe-Ni alloy, or the like is formed. As shown in FIG. 2, both ends of the internal electrode 24 penetrate the sealing material 16 and are led out of the envelope 18.
Further, a through-hole 26 penetrating both the second substrate 14 and the external electrode 22 is formed. The through hole 26 is connected to the outer surface of the external electrode 22 and is airtightly closed by being covered with a cap-shaped glass tube 28 having one end sealed. Therefore, the discharge gas in the discharge space 20 does not flow out of the discharge tube 10 through the through hole 26. The glass tube 28 is formed using an exhaust pipe described later.
As a result of the formation of the through-hole 26, the external electrode 22 communicates with the discharge space 20 in an airtight state via the through-hole 26.
[0018]
In the discharge tube 10 of the present invention, when an AC voltage is applied to the external electrode 22 and the internal electrode 24, a discharge is generated in the discharge space 20 through the second substrate 14 which is a dielectric, and electrons are generated. The emitted electrons collide with the ultraviolet emitting gas to generate ultraviolet rays of various wavelengths.
The generated ultraviolet light is transmitted through the first substrate 12 made of the ultraviolet transmitting glass and radiated to the outside of the envelope 18.
[0019]
If ultraviolet rays having a wavelength of less than 220 nm (especially 185 nm) among ultraviolet rays emitted to the outside of the envelope 18 are used, ozone (O ₃ ) can be generated by acting on oxygen in the air. In addition, sterilization can be performed by using ultraviolet light having a wavelength of 254 nm. Furthermore, if ultraviolet rays having a wavelength of 300 to 400 nm are used, it is possible to activate a photocatalyst made of anatase-type titanium oxide (TiO ₂ ) or the like.
[0020]
The internal electrode 24 may be formed on the inner surface of the second substrate 14. In addition, since the first substrate 12 made of ultraviolet transmitting glass is also a dielectric, the external electrodes 22 may be formed on the outer surface of the first substrate 12.
[0021]
Next, a method for manufacturing the discharge tube 10 will be described.
First, a band-shaped internal electrode 24 made of a 42-6 alloy, a Fe—Ni alloy, or the like is connected to the inner surface 12a of the first substrate 12, and a silver paste or a transparent paste is formed on the outer surface 14a of the second substrate 14. A strip-shaped external electrode 22 made of a NESA film (SnO ₂ ) or the like is attached by a method such as printing (not shown).
Next, a through-hole 26 penetrating both the second substrate 14 and the external electrode 22 is formed using an ultrasonic machine, a drill, or the like (not shown).
[0022]
Next, in a state where the first substrate 12 and the second substrate 14 are arranged to face each other with a predetermined gap therebetween, the sealing material 16 such as low-melting glass is heated at a temperature of about 450 ° C. The envelope 18 is formed by hermetically sealing the peripheral edges of both substrates 12 and 14 via the intermediary.
Further, while being heated at a temperature of about 450 ° C., the outer surface of the external electrode 22 in which the through-hole 26 is formed is covered with the through-hole 26 via a sealing material (not shown) such as low-melting glass. Is connected to a glass exhaust pipe 30 (FIG. 3).
[0023]
Thereafter, a vacuum exhaust device (not shown) is connected to the exhaust pipe 30, and the inside of the envelope 18 is evacuated, and then the ultraviolet radiation gas is sealed in the envelope 18 through the exhaust pipe 30 and the through hole 26. As a result, a discharge space 20 is formed in the envelope 18.
Next, as shown in FIG. 4, a middle part of the exhaust pipe 30 is heated and melted by a burner 32 and sealed off, so that the exhaust pipe 30 is formed into a cap-shaped glass tube 28 having one end sealed. Is completed.
As described above, according to the above-described manufacturing method, the glass tube 28 that closes the through hole 26 is formed by using the exhaust pipe 30 that is used to evacuate the envelope 18 and fill the ultraviolet radiation gas. can do.
[0024]
Thus, as shown in the graph of FIG. 7, the discharge tube 10 (FIG. 7C) according to the present invention includes not only the above-described conventional DC-driven discharge tube 60 (FIG. 7A) but also the AC-driven discharge tube 60. Large emission intensity can be obtained even when compared to the discharge tube 80 (FIG. 7B).
Incidentally, the discharge tube 10 according to the present invention, the conventional DC-driven discharge tube 60, and the AC-driven discharge tube 80 are each provided with an ultraviolet radiation gas containing a mixture of argon and mercury in an envelope at 80 Torr. The one sealed under pressure was used. The diameter of the through hole 26 of the discharge tube 10 of the present invention was 0.6 mm. Note that the outer dimensions of the envelope of the discharge tube 10 according to the present invention, the conventional discharge tube 60 of the DC drive system, and the discharge tube 80 of the AC drive system are about 120 mm in width, about 22 mm in depth, and about 22 mm in thickness. The first substrate and the second substrate 14 each have a thickness of about 1 mm.
[0025]
In the discharge tube 10 of the present invention, the external electrodes 22 are formed on the outer surface 14 a of the second substrate 14, and the internal electrodes 24 are formed on the inner surface 12 a of the first substrate 12, and are formed on the second substrate 14. The reason why the light emission intensity of the discharge tube 10 can be improved by communicating the external electrode 22 and the discharge space 20 in a gas-tight manner through the through hole 26 is as follows.
First, the external electrodes 22 are formed on the outer surface 14a of the second substrate 14 and the internal electrodes 24 are formed on the inner surface 12a of the first substrate 12, so that the half-cycle of the AC driving is performed via the dielectric. A DC discharge having a better discharge efficiency than the AC discharge is generated, and in this case, the discharge is generated on substantially the entire surface of the internal electrode 24 while the voltage is being applied. It can be improved.
Further, since the external electrode 22 and the discharge space 20 are connected in an airtight manner through the through hole 26 formed in the second substrate 14, a large amount of electric charges are accumulated on the inner wall of the through hole 26. As a result, the discharge current at the time of voltage application becomes large, so that the light emission intensity of the discharge tube 10 can be improved.
[0026]
In the discharge tube 10 of the present invention, the diameter of the through hole 26 is preferably set to 0.2 mm to 1.0 mm.
That is, when the diameter of the through hole 26 is smaller than 0.2 mm, the amount of electric charge accumulated on the inner wall of the through hole 26 is small, so that the emission intensity of the discharge tube 10 cannot be effectively improved. On the other hand, if the diameter of the through-hole 26 is greater than 1.0 mm, the possibility that the external electrode 22 is sputtered and deteriorated by the charged particles passing through the through-hole 26 when a DC discharge is generated increases.
The diameter of the through hole 26 may be appropriately adjusted according to the size of the envelope 18 of the discharge tube 10, the type of the discharge gas, the gas pressure, and the like.
[0027]
As described above, in order to improve the light emission intensity of the discharge tube 10, the external electrode 22 and the discharge space 20 may be connected to each other in an airtight manner via the through hole 26. Therefore, in the above description, the case where the through-hole 26 penetrating both the second substrate 14 and the external electrode 22 is formed has been described as an example, but the through-hole 26 may not be formed in the external electrode 22.
In the above description, the case where the external electrode 22 is formed on the outer surface 14a of the second substrate 14 has been described as an example. However, the present invention is not limited to this. The external electrode 22 may be formed so that the outer surface of the envelope 18 is wound around the outer surface of the second substrate 14. In this case, the external electrodes 22 are formed on the outer surfaces of the first substrate 12 and the second substrate 14.
Furthermore, in the above description, the case where the internal electrode 24 is formed on the inner surface 12a of the first substrate 12 has been described as an example. However, the present invention is not limited to this, and for example, from the inner surface of the first substrate 12 The internal electrode 24 may be formed over the inner surface of the second substrate 14. In this case, the internal electrodes 24 are formed on the inner surfaces of the first substrate 12 and the second substrate 14.
[0028]
【The invention's effect】
In the discharge tube according to the present invention, the external electrode is formed on the outer surface of the envelope, the internal electrode is formed on the inner surface of the envelope, and the external electrode is formed through the through hole formed in the envelope. With a simple structure in which the discharge space and the discharge space communicate with each other in an airtight state, the light emission intensity can be improved as compared with the conventional discharge tubes 60 and 80.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a discharge tube according to the present invention.
FIG. 2 is a bottom view showing a discharge tube according to the present invention.
FIG. 3 is an explanatory view showing a method for manufacturing a discharge tube according to the present invention.
FIG. 4 is an explanatory view showing a method for manufacturing a discharge tube according to the present invention.
FIG. 5 is a sectional view showing a conventional discharge tube.
FIG. 6 is a sectional view showing another conventional discharge tube.
FIG. 7 is a graph showing the intensity of ultraviolet light emitted from the discharge tube according to the present invention and the conventional discharge tube over time.
[Explanation of symbols]
Reference Signs List 10 discharge tube 12 first substrate 14 second substrate 18 envelope 20 discharge space 22 external electrode 24 internal electrode 26 through hole 28 glass tube 30 exhaust tube

Claims (3)

A discharge space is formed by filling a discharge gas inside the envelope made of a dielectric, and an external electrode is formed on the outer surface of the envelope, and an internal electrode is formed on the inner surface of the envelope. A discharge tube, wherein a through hole penetrating the envelope is formed, and the external electrode and the discharge space are communicated in an airtight manner through the through hole. A first substrate made of an ultraviolet transmitting glass and a second substrate made of an insulating material are arranged to face each other with a predetermined gap therebetween, and the outer edges of both substrates are hermetically sealed to form the envelope. Filling the envelope with an ultraviolet radiation gas to form the discharge space, and forming the external electrode on the outer surface of the first substrate and / or the second substrate; The internal electrode is formed on the inner surface of the substrate and / or the second substrate, a through-hole is formed through the substrate on which the external electrode is formed, and the external electrode is discharged through the through-hole. The discharge tube according to claim 1, wherein the discharge tube communicates with the space in an airtight state. The discharge tube according to claim 1, wherein a diameter of the through hole is 0.2 mm to 1.0 mm.

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