JP2005183046A - Gas discharge tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas discharge tube capable of obtaining an elongated life of an electrode and stable discharge. <P>SOLUTION: The gas discharge tube DT is provided with a glass bulb 1, lead-in wires 3 sealed at either end of the glass bulb 1, and electrodes 11 mounted on a tip of each lead-in wire 3. A discharge space S is formed between the electrodes in the gas discharge tube DT. The electrode 11 has coiled coils 13, metal oxide 15 as easily electron-emitting substance, and a linear member 17. The metal oxide 15 is held by the coiled coils 13 and fitted in contact with the linear member 17. The linear member 17 is fitted in electric contact with a plurality of coil parts of the coiled coils 13 along a length direction of the coiled coils 13. Each of the electrodes 11 is mounted on the lead-in wire 3 so that the linear member 17 face the discharge space S. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gas discharge tube.

As this type of gas discharge tube, there is known a gas discharge tube including a tubular container hermetically sealed with gas, and an electrode mounted at the leading end of an introduction line sealed at both ends of the container. (For example, see Patent Documents 1 to 3).
JP-A-4-58449 JP-A-4-73854 JP-A-6-203800

  However, in the gas discharge tube having the configuration described in Patent Documents 1 to 3 described above, an electric field concentrates at the tip of the electrode serving as a discharge surface during discharge, resulting in local discharge (uneven distribution of discharge positions). ) Will occur. The local discharge causes scraping (sputtering) of the cathode material (metal oxide as an easy-electron emitting material), that is, a decrease in thermionic emission capability, and the discharge position is the next position with good thermionic emission characteristics. Move to. Thus, the electrode surface is deteriorated while repeating local thermionic emission deterioration. Further, the discharge itself becomes unstable due to the movement of the discharge position described above.

  This invention is made | formed in view of the above-mentioned point, and makes it the subject to provide the gas discharge tube which can prolong the lifetime of an electrode and can obtain the stable discharge.

  A gas discharge tube according to the present invention includes a tubular container in which a gas is hermetically sealed, and an electrode attached to a distal end portion of an introduction line sealed at both ends of the container, and a discharge space between the electrodes. Each of the electrodes includes a coil member wound in a coil shape, a metal oxide as an easy-electron emitting material held by the coil member, and the coil member and the metal oxide. An electric conductor disposed on the outer side of the coil member so as to be in contact with the coil member, and the electric conductor is mounted so as to face the discharge space. .

  In the gas discharge tube according to the present invention, since the equipotential surface is effectively formed on the electrode surface by the electric conductor, the discharge area increases because thermionic emission occurs in a wide region of the formed equipotential surface, The amount of electron emission per unit area (electron emission density) increases, and the load at the discharge position is reduced. As a result, it is possible to suppress metal oxide sputtering, which is a deterioration factor, and stabilization (mineralization) due to oxidation with a reduced metal, that is, a decrease in thermionic emission ability, thereby extending the life of the electrode. . Further, since the movement of the discharge position is also suppressed, a stable discharge can be obtained for a long time. In addition, in relation to the increase in the discharge area, the current density is slightly increased to slightly increase the load, that is, even if the discharge current is increased, the damage can be reduced compared to the conventional one, and is almost the same as the conventional one. With the shape, an electrode with a large discharge current can be provided, and a pulse operation and a large current operation can be realized.

  In the present invention, each electrode is attached to the leading end of the lead-in wire so that the electric conductor faces the discharge space, so that the electric conductors face each other so that they can look over each other. As a result, the potential area of the equipotential surface is widened and the discharge is dispersedly generated, so that the increase in the discharge density is suppressed and the local concentration of the discharge can be prevented. As a result, the electrode load is reduced and the life of the electrode can be further extended.

  Moreover, in this invention, since the metal oxide as an easily electron emission substance is hold | maintained at the coil member, drop-off | omission of a metal oxide can be suppressed. Further, a large amount of metal oxide can be retained, and there is an effect of replenishing the disappeared metal oxide content accompanying deterioration with time during discharge.

  Moreover, it is preferable that the electric conductors face each other with the discharge space interposed therebetween. When comprised in this way, the equipotential surface which contributes to discharge will expand further, and discharge efficiency can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the gas discharge tube which can prolong the lifetime of an electrode and can obtain the stable discharge can be provided.

  A gas discharge tube according to an embodiment of the present invention will be described with reference to the drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  First, the gas discharge tube DT according to the present embodiment will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing a gas discharge tube according to the present embodiment. FIG. 2 is a schematic cross-sectional view showing electrodes included in the gas discharge tube according to the present embodiment, and FIG. 3 is a schematic perspective view showing electrodes included in the gas discharge tube according to the present embodiment. In FIG. 3, illustration of a metal oxide as an easily electron-emitting substance is omitted.

  As shown in FIG. 1, the gas discharge tube DT includes a glass bulb 1 as a tubular container, an introduction line (introduction pin) 3 sealed at both ends of the glass bulb 1, and a tip portion of the introduction line 3. And an electrode 11 attached to the. A phosphor film (not shown) is formed on the inner surface of the glass bulb 1. The glass bulb 1 is hermetically sealed with a rare gas such as argon, or a rare gas such as argon and mercury. In the gas discharge tube DT, a discharge space S is formed between the electrodes 11. The lead-in wire 3 is electrically connected to a discharge drive circuit 5 for lighting the gas discharge tube DT. The electrode 11 operates as a cold cathode.

  2 and 3, the electrode 11 includes a double coil 13 as a coil member, a metal oxide 15 as an easily radiating substance, and a linear member 17 as an electric conductor. ing. Here, the double coil 13 and the metal oxide 15 as the easy electron emitting material constitute an electron emitting portion that emits electrons.

  The double coil 13 is a multiple coil composed of coils wound in a coil shape. The double coil 13 is formed, for example, by forming a tungsten wire having a diameter of 0.0465 mm as a primary coil having a diameter of 0.1 mm and a pitch of 0.07 mm, and further using a double coil having a diameter of 0.85 mm and a pitch of 0.27 mm. What was formed in the coil can be used.

  The linear member 17 formed in a linear shape is a rigid body (metal conductor) having conductivity, belonging to groups IIIa to VIIa, VIII, and Ib of the periodic table, specifically tungsten, tantalum, molybdenum, rhenium, Niobium, osmium, iridium, iron, nickel, cobalt, titanium, zirconium, manganese, chromium, vanadium, rhodium, a rare earth metal or other high-melting point metal (melting point of 1000 ° C. or higher), or an alloy thereof. In this embodiment, a linear member made of tungsten is used. The diameter of the linear member 17 is set to about 0.1 mm. The linear member 17 has a predetermined length, and is disposed outside the double coil 13 so as to be substantially orthogonal to the discharge direction over the longitudinal direction of the double coil 13.

  The linear member 17 is provided in electrical contact with a plurality of coil portions of the double coil 13 along the longitudinal direction of the double coil 13. Preferably, the double coil 13 is provided in electrical contact over the entire length in the longitudinal direction. The linear member 17 is provided on the outermost surface side portion of the electron emission portion including the double coil 13 and the metal oxide 15 as the electron emission material. Note that the number of the linear members 17 is not limited to one and may be two or more. Further, each contact point between the linear member 17 and the double coil 13 may be welded.

  The metal oxide 15 is held by the double coil 13 and provided in contact with the linear member 17. The metal oxide 15 and the linear member 17 are exposed to the outside of the electrode 11 so that the surface of the metal oxide 15 and the surface of the linear member 17 serve as a discharge surface. The linear member 17 comes into contact.

  The linear member 17 is electrically connected to the lead rod 19 by welding or the like and fixed to the lead rod 19. The lead rod 19 is electrically connected to the lead-in wire 3 by welding or the like, and is fixed to the lead-in wire 3. The lead-in wire 3 is connected to a discharge AC power source. The linear member 17 is connected to the discharge AC power source via the lead rod 19. Thus, when a voltage is applied and discharge is started, the discharge current passes through the lead rod 19 via the lead-in wire 3 to the double coil 13, the linear member 17, and the metal oxide 15 as an electron emission material. A discharge current supply circuit to the electrode 11 is formed. The double coil 13 may be electrically connected to the lead rod 19 and fixed to the lead rod 19.

  As the metal oxide 15, any one of barium (Ba), strontium (Sr), calcium (Ca), a mixture of these oxides, or a main constituent is barium, strontium, calcium. Among these, an oxide which is a single oxide or a mixture of these oxides and whose secondary constituent element is a rare earth metal (IIIa in the periodic table) containing a lanthanum series is used. Barium, strontium, and calcium have a small work function, can easily release thermionic electrons, and can increase the supply amount of thermionic electrons. Further, when a rare earth metal (IIIa in the periodic table) is added as a sub-constituent requirement, it is possible to further increase the supply amount of thermoelectrons and to improve the spatter resistance.

  The metal oxide 15 is applied as a cathode material in the form of a metal carbonate (for example, barium carbonate, strontium carbonate, calcium carbonate, etc.), and obtained by subjecting the applied metal carbonate to thermal decomposition under vacuum. According to the vacuum thermal decomposition, it is possible to prevent a decrease in electron emission capability due to adhesion of moisture or the like. As a technique for thermally decomposing metal carbonate, for example, the electrode 11 is attached to the lead-in wire 3 in a state where the metal carbonate is applied, and the glass bulb 1 is vacuum-sealed, and then the gas discharge tube DT (glass There is a method of heating the electrode 11 by high-frequency heating from the outside of the bulb 1). The metal oxide 15 thus obtained finally becomes an electron-emitting material. As shown in FIG. 3, the metal carbonate as the cathode material is applied from the linear member 17 side in a state where the linear member 17 is disposed outside the double coil 13. The metal carbonate does not need to be applied so as to cover the entire circumference of the electrode 11 (double coil 13), and may be applied only to a portion where the linear member 17 is provided. Of course, the metal oxide 15 may be provided by previously forming a metal oxide and applying the metal oxide.

  As shown in FIG. 1, each of the electrodes 11 having the above-described configuration is attached to the lead-in wire 3 and disposed in the glass bulb 1 so that the linear member 17 faces the discharge space S. The electrode 11 is attached to the lead-in wire 3 so that the longitudinal direction of the double coil 13 intersects the longitudinal direction of the glass bulb 1 (in the present embodiment, it is orthogonal). In this case, the discharge path between the electrodes 11 can be made relatively long in the longitudinal direction of the glass bulb 1. Each of the linear members 17 is opposed to each other with the discharge space S interposed therebetween as shown in FIG.

  As shown in FIG. 4, the electrode 11 is attached to the lead-in wire 3 so that the longitudinal direction of the double coil 13 is aligned with the longitudinal direction of the glass bulb 1 (in the present embodiment, it is matched). Also good. In this case, the tube diameter of the glass bulb can be made relatively thin.

  From the above, in the present embodiment, the linear member 17 is provided in contact with the metal oxide 15, and the linear member 17 is in electrical contact with the double coil 13 at a plurality of locations. An equipotential surface is effectively formed on the surface of the electrode 11 by the member 17. When an equipotential surface is formed in this way, thermionic emission occurs in a wide region of the formed equipotential surface, so that the discharge area increases and the amount of electron emission (electron emission density) per unit area increases. The load at the discharge position is reduced. As a result, it is possible to suppress the deterioration (mineralization) of the metal oxide 15 which is a deterioration factor by oxidation with the reduced metal, that is, the decrease in thermionic emission ability, and to extend the life of the electrode. it can. Further, since the movement of the discharge position is also suppressed, a stable discharge can be obtained for a long time.

  Further, in the electrode 11, in relation to the increase in the discharge area, even if the current density is slightly increased and the load is slightly increased, that is, the discharge current is increased, the damage can be reduced as compared with the conventional one. The electrode having a large discharge current can be provided with substantially the same shape as the conventional one, and a pulse operation and a large current operation can be realized.

  Moreover, in this embodiment, since each electrode 11 is attached to the front-end | tip part of the introduction wire 3 so that the linear member 17 may face the discharge space S, it faces so that the linear members 17 can look over each other. Become. As a result, the potential area of the equipotential surface formed by the linear member 17 is widened and discharge is generated in a dispersed manner, so that an increase in discharge density can be suppressed and local concentration of discharge can be prevented. As a result, the electrode load is reduced and the life of the electrode 11 can be further extended.

  Moreover, in this embodiment, since the metal oxide 15 as an electron-emitting substance is held by the double coil 13, it is possible to suppress the metal oxide 15 from falling off. In addition, a large amount of the metal oxide 15 can be retained, and there is an effect of replenishing the lost metal oxide content accompanying the deterioration with time during discharge. In particular, a large amount of the metal oxide 15 is held between the pitches of the double coils 13, and the effect of replenishing the lost metal oxide is further enhanced.

  Moreover, in this embodiment, since the linear member 17 is used as an electrical conductor, an electrical conductor having a configuration capable of suppressing the decrease in thermionic emission ability and the movement of the discharge position is realized at a lower cost and more easily. be able to. In addition, since the linear member 17 (electrical conductor) is a rigid body, it is easy to process and can be provided in close contact with the metal oxide 15.

  In the present embodiment, the linear members 17 are opposed to each other with the discharge space S interposed therebetween. As a result, the equipotential surface contributing to the discharge is further expanded, and the discharge efficiency can be increased.

  Next, with reference to FIGS. 5-7, the modification of the electrode contained in the gas discharge tube which concerns on this embodiment is demonstrated. 5 and 6 are schematic cross-sectional views showing modifications of the electrodes included in the gas discharge tube according to the present embodiment. FIG. 7 is a perspective view showing a modification of the electrode included in the gas discharge tube according to the present embodiment.

  As shown in FIG. 5, the modified electrode 21 includes a double coil 23 as a coil member, a metal oxide 15 as an easily radiating substance, and a linear member 17. Here, the double coil 23 and the metal oxide 15 as the easy electron emitting material constitute an electron emitting portion that emits electrons.

  Similar to the double coil 13, the double coil 23 is a multiple coil composed of coils wound in a coil shape, and has a mandrel 24. The linear member 17 is provided outside the double coil 23 so as to be substantially orthogonal to the discharge direction over the longitudinal direction of the double coil 23. The linear member 17 is provided in electrical contact with a plurality of coil portions of the double coil 23 along the longitudinal direction of the double coil 23.

  Thus, in this modification, since the double coil 23 has the mandrel 24, there exists the further effect that it can suppress that the double coil 23 deform | transforms at the time of a process.

  As shown in FIG. 6, the electrode 31 as a modification includes a single coil 33 as a coil member, a metal oxide 15 as an electron-emitting material, and a linear member 17. Here, the single coil 33 and the metal oxide 15 as the easy electron emitting material constitute an electron emitting portion that emits electrons.

  The single coil 33 is a coil member composed of a coil wound in a single coil shape, and is made of a tungsten wire. The linear member 17 is provided outside the single coil 33 so as to be substantially orthogonal to the discharge direction over the longitudinal direction of the single coil 33. The linear member 17 is provided in electrical contact with a plurality of coil portions of the single coil 33 along the longitudinal direction of the single coil 33.

  As shown in FIG. 7, the electrode 41 as a modified example includes a double coil 13 as a coil member, a metal oxide 15 as an electron-emitting material, a linear member 17 as an electric conductor, and a plate shape. And a plate-like member 43 as an electric conductor (including a ribbon shape and a foil shape). Instead of the double coil 13, a double coil 23 or a single coil 33 may be used.

  The plate-like member 43 is a conductive metal (metal conductor), and is made of a simple substance of an iron group metal such as iron, nickel, cobalt, or an alloy thereof. In the present embodiment, a nickel plate-like member is used. The thickness of the plate member 43 is set to about 0.2 μm, and one end of the double coil 13 and both ends of the linear member 17 are joined to the plate member 43 by welding or the like. Thereby, the plate-shaped member 43, the double coil 13, and the linear member 17 are in electrical contact and are in a conductive state. The linear member 17 only needs to be joined to the plate member 43 at least at one end thereof.

  The plate-like member 43 is joined to the lead-in wire 3 by welding or the like, and is electrically connected to the lead-in wire 3.

  Thus, in this modification, the lead-in wire 3 is joined to the plate-like member 43. When constituted in this way, the electrode intermediate body in which the double coil 13 and the linear member 17 are joined to the plate-like member 43 can be reliably and easily joined to the lead-in wire 3.

  In this modification, the linear member 17 is bent at an intermediate position, and both ends of the linear member 17 are joined to the plate member 43. Thereby, the joining strength of the linear member 17 to the plate-like member 43 can be increased.

  The present invention is not limited to the embodiment described above. For example, although the linear member 17 is used as an electric conductor, the present invention is not limited to this, and an electric conductor formed in a plate shape (including a ribbon shape and a foil shape) may be used.

  Further, although a refractory metal is used as the linear member 17, a porous metal having a small thickness instead of the refractory metal is used as long as it is a rigid body having conductivity and a melting point higher than the operating temperature of the electrode. Carbon fiber or the like may be used. Further, in order to improve the spatter resistance and discharge performance of the metal oxide 15, a nitride or carbide such as tantalum, titanium, niobium, etc. is applied to the surface of the metal oxide 15, or the coil members 13, 23, 33, or linear. You may make it adhere to the member 17. FIG.

  Further, in the present embodiment, the surface of the linear member 17 is exposed, but it is not always necessary to expose them, and if the linear member 17 is in contact with the metal oxide 15, The surface of the linear member 17 may be covered with the metal oxide 15.

  In the present embodiment, the electrodes 11 to 41 are attached to the lead-in wire 3 through the lead rod 19, but the lead wire 19 is not used and the wire 17 or the coil member 13 is connected to the lead-in wire 3. 23 and 33 may be electrically connected and fixed by welding or the like. For example, like the electrode 11 shown in FIG. 8, the end of the coil member (for example, the double coil 13) is extended substantially linearly, and the electric conductor (for example, the linear member 17) is extended to the extended portion. A configuration may be adopted in which the coil member is electrically connected and fixed by welding or the like, and the extended portion of the coil member is electrically connected and fixed to the lead-in wire 3 by welding or the like.

  The gas discharge tube of the present invention can be used for a cold cathode fluorescent lamp or the like.

It is a schematic sectional drawing which shows the gas discharge tube which concerns on this embodiment. It is a schematic sectional drawing which shows the electrode contained in the gas discharge tube which concerns on this embodiment. It is a schematic perspective view which shows the electrode contained in the gas discharge tube which concerns on this embodiment. It is a schematic sectional drawing which shows the modification of the gas discharge tube which concerns on this embodiment. It is a schematic sectional drawing which shows the modification of the electrode contained in the gas discharge tube which concerns on this embodiment. It is a schematic sectional drawing which shows the modification of the electrode contained in the gas discharge tube which concerns on this embodiment. It is a perspective view which shows the modification of the electrode contained in the gas discharge tube which concerns on this embodiment. It is a schematic sectional drawing which shows the modification of the electrode contained in the gas discharge tube which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glass bulb, 3 ... Lead wire, 5 ... Discharge drive circuit 11, 21, 31, 41 ... Electrode, 13 ... Double coil, 15 ... Metal oxide, 17 ... Linear member, 19 ... Lead rod, 23 A double coil, 24 a mandrel, 33 a single coil, 43 a plate member, DT a gas discharge tube, S a discharge space.

Claims (2)

A gas discharge tube comprising a tubular container in which gas is hermetically sealed, and an electrode attached to the leading end of an introduction line sealed at both ends of the container, and a discharge space is formed between the electrodes. There,
Each of the electrodes is
A coil member wound in a coil shape;
A metal oxide as an easy-electron emitting material held by the coil member;
An electrical conductor disposed on the outer side of the coil member so as to be in contact with the coil member and the metal oxide, over the longitudinal direction of the coil member,
A gas discharge tube, wherein the electric conductor is mounted so as to face the discharge space. The gas discharge tube according to claim 1, wherein each of the electric conductors is opposed to each other with the discharge space interposed therebetween.