JP3141150U - Discharge tube - Google Patents

Abstract

Disclosed is a discharge tube that has a stable discharge start voltage and can suppress the occurrence of early firing.
A hermetic envelope 16 is formed by hermetically sealing the opening portions at both ends of a cylindrical case member 12 with a pair of lid members 14 and 14 that also serve as discharge electrodes. A discharge gas composed of neon, argon and hydrogen is sealed in the vessel 16, a discharge gap 22 is formed between the discharge electrode portions 18, 18 of the lid members 14, 14, and the inner wall 24 of the case member 12 is formed. A plurality of trigger discharge films 28 are formed at both ends with the lid members 14 and 14 being spaced from the minute discharge gap 26, and a plurality of holes are formed on the surface of the discharge electrode portion 18. A discharge tube 10 in which a coating 30 containing sodium iodide, cesium molybdate, potassium molybdate and rubidium bromide is formed on the inner surface of the hole, wherein the numerous holes 29 are formed in a cylindrical shape. Ke It was placed on the inner wall surface 24 concentric with the circle of the scan element 12.
[Selection] Figure 1

Description

  The present invention relates to a discharge tube, in particular, as a switching spark gap for supplying a constant voltage for lighting or ignition to a high-pressure discharge lamp such as a projector or a metal halide lamp of an automobile, or an ignition plug of a gas cooker, or The present invention relates to a discharge tube that can be suitably used as a gas arrester for absorbing surge voltage.

As this type of discharge tube, the present applicant has previously proposed Utility Model Registration No. 3133824.
As shown in FIGS. 11 to 13, the discharge tube 60 is formed by sealing a cylindrical case member 62 made of an insulating material having both ends opened with a pair of lid members 64 and 64 serving as discharge electrodes. A hermetic envelope 66 is formed by sealing with a predetermined discharge gas in the hermetic envelope 66.

The lid member 64 includes a flat discharge electrode portion 68 that protrudes greatly toward the center of the hermetic envelope 66, and a joint portion 70 that contacts the end surface of the case member 62. A predetermined discharge gap 72 is formed between the discharge electrode portions 68 and 68.
A plurality of trigger discharge films 78 are formed on the inner wall surface 74 of the case member 62 so that both ends of the case member 62 are spaced apart from the lid members 64 and 64 that also serve as discharge electrodes and a minute discharge gap 76.

A large number of substantially hemispherical holes 79 (see FIG. 12) are formed on the surface of the discharge electrode portion 68, and cesium bromide, titanium, molybdic acid having good electron emission characteristics are formed on the inner surface of each hole 79. A film 80 containing a mixture of potassium and magnesium oxide is formed.
A total of 16 4 × 4 holes 79 are arranged and formed in a matrix.

In the discharge tube 60 having the above-described configuration, when a voltage equal to or higher than the discharge start voltage of the discharge tube 60 is applied between the pair of lid members 64 and 64 that also serve as discharge electrodes, the trigger discharge film 78 is provided. The electric field is concentrated in the minute discharge gap 76 between the both ends of the cover member 64 and the lid members 64, 64, whereby electrons are emitted into the minute discharge gap 76 to generate creeping corona discharge as a trigger discharge. Next, this creeping corona discharge shifts to glow discharge due to an electron priming effect. Then, this glow discharge is transferred to the discharge gap 72 between the discharge electrode portions 68 and 68, and is transferred to arc discharge as the main discharge.
Utility Model Registration No. 3133824

  By the way, since discharge tends to occur at the interface between the discharge electrode portion 68 and the coating 80, the coating 80 is likely to be sputtered by the impact during discharge, and the constituent material of the coating 80 scattered by sputtering (hereinafter referred to as spatter Is attached to and deposited on the inner wall surface 74 and the trigger discharge film 78 of the case member 62, which causes the discharge start voltage to become unstable.

In the conventional discharge tube 60, since the holes 79 in which the coating 80 is formed are arranged in a matrix on the surface of the discharge electrode portion 68, the inner wall surface 74 of the cylindrical case member 62 and The distance from each hole 79 was different.
For this reason, the amount of spatter scattered on the inner wall surface 74 / trigger discharge film 78 of the case member 62 where the distance from the hole 79 is small increases, while the case where the distance from the hole 79 is large. The amount of spatter scattered on the inner wall surface 74 and the trigger discharge film 78 of the member 62 was small.
As described above, the amount of spatter scattered is different for each portion of the inner wall surface 74 and the trigger discharge film 78 of the case member 62, which has been a major factor for promoting instability of the discharge start voltage. .

  Further, in the discharge tube 60, there is a case where an early ignition that discharges at a voltage lower than a specified voltage may occur.

  The present invention has been made in view of the above-described conventional problems, and its object is to provide a long-life discharge tube that has a stable discharge start voltage and can suppress the occurrence of early firing. Is to realize.

As a result of various investigations on the material to be contained in the coating, the composition of the discharge gas, the arrangement of the holes where the coating is applied, the inventors have found that sodium iodide (NaI), cesium molybdate ( When Cs ₂ MoO ₄ ), potassium molybdate (K ₂ MoO ₄ ) and rubidium bromide (RbBr) are contained, the discharge gas is composed of a mixed gas of neon (Ne), argon (Ar) and hydrogen (H ₂ ). In this case, when the hole for coating the coating is arranged on a circle concentric with the inner wall surface of the cylindrical case member, the discharge start voltage is stable and the occurrence of early firing is suppressed. It has been found that it is possible to complete this invention.
That is, the discharge tube according to the present invention forms an airtight envelope by hermetically sealing the opening portions at both ends of a cylindrical case member with a pair of lid members that also serve as discharge electrodes, and A discharge gas composed of neon, argon and hydrogen is enclosed in the envelope, and a discharge gap is formed between the discharge electrode portions of the lid member disposed in the hermetic envelope, and the case member Forming a plurality of trigger discharge films whose both ends are spaced apart from the lid member by a minute discharge gap, and forming a plurality of holes on the surface of the discharge electrode portion, and A discharge tube in which a coating containing sodium iodide, cesium molybdate, potassium molybdate and rubidium bromide is formed on the inner surface of the hole, wherein the numerous holes are formed on the inner wall surface of the cylindrical case member On a concentric circle Characterized in that the location is formed.

  The hole is preferably substantially hemispherical.

The content of sodium iodide contained in the coating is 0.01 to 40% by weight, the content of cesium molybdate is 0.01 to 40% by weight, and the content of potassium molybdate is 0.01 to 40% by weight. The content ratio of rubidium bromide is preferably 0.01 to 40 wt.
Further, it is preferable that the mixing ratio of neon in the discharge gas is 0.1 to 70% by volume, the mixing ratio of argon is 0.1 to 70% by volume, and the mixing ratio of hydrogen is 0.1 to 70% by volume.

  In the discharge tube according to the present invention, the coating film contains sodium iodide, cesium molybdate, potassium molybdate and rubidium bromide, and the discharge gas is composed of neon, argon and hydrogen. By arranging and forming many holes to be formed on a circle concentric with the inner wall surface of the cylindrical case member, the discharge starting voltage is stable and the long life can be suppressed. A discharge tube can be realized.

  When the hole is formed in a substantially hemispherical shape, the state of the coating is stabilized, and variations in discharge characteristics can be reduced. In other words, when the hole is made “substantially hemispherical”, the surface tension is applied uniformly from all directions of the hole, and as a result, the film is formed uniformly in all directions, so the state of the film is stable. Thus, variation in discharge characteristics can be reduced.

  A discharge tube 10 according to the present invention shown in FIGS. 1 to 5 includes a pair of lid members 14 that serve as discharge electrodes at both ends of a cylindrical case member 12 made of ceramic as an insulating material having both ends open. The hermetic envelope 16 is formed by hermetically sealing with 14.

The lid member 14 includes a substantially cylindrical discharge electrode portion 18 projecting greatly toward the center of the hermetic envelope 16, and a joint portion 20 in contact with the end surface of the case member 12, and both lid members 14, 14 A predetermined discharge gap 22 is formed between the discharge electrode portions 18 and 18.
The lid member 14 provided with the discharge electrode portion 18 and the joint portion 20 is made of oxygen-free copper or zirconium copper containing oxygen-free copper containing zirconium (Zr). Note that the end surface of the case member 12 and the joint portion 20 of the lid member 14 are hermetically sealed through a sealing material (not shown) such as silver solder.

In addition, a plurality of linear trigger discharge films 28 are formed on the inner wall surface 24 of the case member 12 so that both ends of the case member 12 are spaced apart from the lid members 14 and 14 that also serve as discharge electrodes and a minute discharge gap 26. ing. 1 to 3 exemplify a case where eight trigger discharge films 28 are formed at equal intervals of 45 degrees in the circumferential direction of the inner wall surface 24 of the case member 12.
The trigger discharge film 28 is made of a conductive material such as a carbon-based material. The trigger discharge film 28 can be formed, for example, by rubbing a core material made of a carbon-based material.

A large number of substantially hemispherical holes 29 are formed on the surface of the discharge electrode 18, and sodium iodide (NaI), cesium molybdate (Cs ₂ MoO ₄ ), molybdic acid are formed on the inner surface of each hole 29. A film 30 containing potassium (K ₂ MoO ₄ ) and rubidium bromide (RbBr) is formed.
As shown in FIGS. 3 and 5, the holes 29 are formed at equal intervals on circles X and Y concentric with the inner wall surface 24 of the cylindrical case member 12 (hereinafter referred to as concentric circles). . That is, twelve hole portions 29 are formed on the concentric circle X at equal intervals of 30 degrees, and four hole portions 29 are formed on the concentric circle Y at equal intervals of 90 degrees. A single hole 29 is also arranged and formed at the center of the cylindrical case member 12.
The concentric circles X and Y in FIGS. 3 and 5 are virtual circles shown for convenience of explanation.

The coating 30 is obtained by adding sodium iodide powder, cesium molybdate powder, potassium molybdate powder, and rubidium bromide powder to a binder made of sodium silicate and pure water, on the surface of the discharge electrode portion 18. It can be formed by applying to the inner surface of the hole 29.
In this case, the content of sodium iodide, cesium molybdate, potassium molybdate, and rubidium bromide is 0.01 to 40% by weight for sodium iodide, 0.01 to 40% by weight for cesium molybdate, and potassium molybdate. Is preferably 0.01 to 40% by weight and rubidium bromide is 0.01 to 40% by weight from the viewpoint of stabilizing the discharge start voltage and improving the effect of suppressing early ignition.
The blending ratio of sodium iodide, cesium molybdate, potassium molybdate and rubidium bromide and the binder is 10 to 90% by weight for sodium iodide and cesium molybdate, and 10 to 90% by weight for the binder. The
The blending ratio of sodium silicate and pure water in the binder is such that sodium silicate is 0.01 to 70% by weight and pure water is 99.99 to 30% by weight.

In the hermetic envelope 16, a discharge gas composed of neon (Ne), argon (Ar), and hydrogen (H ₂ ) is enclosed.
In this case, the mixing ratio of neon, argon, and hydrogen is 0.1 to 70% by volume for neon, 0.1 to 70% by volume for argon, and 0.1 to 70% by volume for hydrogen. It is preferable from the viewpoint of stabilizing the heat and improving the effect of suppressing early ignition.

  In the discharge tube 10 of the present invention, when a voltage equal to or higher than the discharge start voltage of the discharge tube 10 is applied between the pair of lid members 14 and 14 that also serve as discharge electrodes, the trigger discharge film 28 The electric field concentrates in the minute discharge gap 26 between the both ends and the lid members 14 and 14, whereby electrons are emitted into the minute discharge gap 26 to generate creeping corona discharge as a trigger discharge. Next, this creeping corona discharge shifts to glow discharge due to an electron priming effect. Then, the glow discharge is transferred to the discharge gap 22 between the discharge electrode portions 18 and 18, and the arc discharge is performed as the main discharge.

In addition, the shape of the hole 29 formed on the surface of the discharge electrode portion 18 is not limited to the above-described “substantially hemispherical”, and as shown in the modification of the discharge tube 10 in FIGS. 6 and 7, It may be “substantially rectangular parallelepiped”.
However, the case where the hole 29 is formed to be “substantially hemispherical” is preferable because the state of the coating 30 can be stabilized and variations in discharge characteristics can be reduced. That is, when the hole portion 29 is formed to be “substantially hemispherical”, the surface tension is uniformly applied from all directions of the hole portion 29, and as a result, the coating film 30 is formed uniformly in all directions. This stabilizes the state and can reduce variations in discharge characteristics.

Thus, in the discharge tube 10 of the present invention, the coating 30 contains sodium iodide, cesium molybdate, potassium molybdate and rubidium bromide, and the discharge gas is composed of neon, argon and hydrogen. Furthermore, since a large number of holes 29 in which the coating 30 is formed are arranged on the circles X and Y concentric with the inner wall surface 24 of the cylindrical case member 12, the discharge start voltage is stable. The occurrence of early firing can be suppressed.
The fact that the numerous holes 29 where the coating film 30 is formed is arranged on the circles X and Y concentric with the inner wall surface 24 of the cylindrical case member 12 contributes to the stability of the discharge start voltage. For the following reasons. That is, when a large number of holes 29 in which the coating 30 is formed are arranged on the circles X and Y concentric with the inner wall surface 24 of the cylindrical case member 12, each of the holes 29 arranged on the same circle X or Y is arranged. The distances between the hole 29 and the inner wall surface 24 of the case member 12 are all the same.
For this reason, it is possible to suppress the occurrence of a slight difference in the amount of spatter scattered in a specific portion of the inner wall surface 24 of the case member 12 and a specific trigger discharge film 28, and the inner wall surface 24 and trigger discharge of the case member 12 can be suppressed. Since the amount of spatter scattered on the film 28 is leveled, the discharge start voltage is stabilized.

FIG. 8 is a graph showing the relationship between the number of discharges in the dark and the initial discharge start voltage in the discharge tube 10 according to the present invention and the discharge tube of the comparative example. Each of these discharge tubes uses a discharge start voltage set to 800 V. In this case, when the initial discharge start voltage exceeds 980 V (maximum limit voltage), or the initial discharge start voltage is 720 V. It is evaluated as unsuitable for use when the value is below (minimum limit voltage).
As the discharge tube 10 according to the present invention, the content ratio of sodium iodide, cesium molybdate, potassium molybdate and rubidium bromide in the coating 30 is 5: 1: 1: 1, and neon and argon in the discharge gas. The mixture ratio of hydrogen is 50% by volume of neon, 30% by volume of argon, and 20% by volume of hydrogen.
Further, as a discharge tube of a comparative example, like the conventional discharge tube 60, holes where a film is formed are arranged and formed in a matrix on the surface of the discharge electrode part, and the film contains sodium iodide. Further, a discharge gas composed of 77% by volume of argon, 3% by volume of krypton, and 20% by volume of hydrogen was used.
The initial discharge start voltage refers to the first discharge start voltage when the discharge tube is repeatedly operated, and the second and subsequent discharge start voltages subsequent to the initial discharge start voltage are referred to as follow-up discharge start voltages.
As shown in the graph of FIG. 8, in the case of the discharge tube of the comparative example (graph B of FIG. 8), the initial discharge start voltage gradually increases when the number of discharges exceeds 100,000, In the case of the discharge tube 10 of the present invention (graph A in FIG. 8), it can be seen that the initial discharge start voltage is substantially constant and stable even when the number of discharges reaches 200,000.

FIG. 9 is a graph showing the relationship between the number of discharges in the dark and the follow-up discharge start voltage in the discharge tube 10 according to the present invention and the discharge tube of the comparative example. In this case, when the follow-up discharge start voltage exceeds 920 V (maximum limit voltage), or when the follow-up discharge start voltage falls below 720 V (minimum limit voltage), it is evaluated as unsuitable for use.
As shown in the graph of FIG. 9, in the case of the discharge tube of the comparative example (graph B of FIG. 9), the number of discharges is about 200,000 times, and the follow-up discharge start voltage is reduced to 720 V, which is the lowest limit voltage. .
On the other hand, in the case of the discharge tube 10 of the present invention (graph A in FIG. 9), even if the number of discharges is 200,000 times, the follow-up discharge start voltage has moved above the minimum limit voltage of 720V. It can be seen that a long life is realized.

FIG. 10 is a chart showing the transition of the discharge start voltage when the discharge tube 10 of the present invention in which the discharge start voltage is set to 800 V is operated at intervals of 10 ms.
As shown in the chart of FIG. 10, in the discharge tube 10 of the present invention, a stable discharge start voltage is obtained without causing early firing.

It is a schematic sectional drawing which shows the discharge tube which concerns on this invention. It is BB schematic sectional drawing of FIG. It is CC schematic sectional drawing of FIG. It is an important section expanded sectional view of a discharge tube concerning the present invention. It is an enlarged view which shows the discharge electrode part surface of the discharge tube which concerns on this invention. It is an enlarged view which shows the discharge electrode part surface of the modification of the discharge tube which concerns on this invention. It is a principal part expanded sectional view of the modification of the discharge tube which concerns on this invention. It is a graph which shows the relationship between the frequency | count of discharge and the initial stage discharge start voltage in the discharge tube which concerns on this invention, and the discharge tube of a comparative example. It is a graph which shows the relationship between the frequency | count of discharge and a follow-up discharge start voltage in the discharge tube which concerns on this invention, and the discharge tube of a comparative example. It is a chart which shows transition of the discharge start voltage at the time of operating the discharge tube concerning this invention at intervals of 10 ms. It is a schematic sectional drawing which shows the conventional discharge tube. It is a principal part expanded sectional view of the conventional discharge tube. It is AA schematic sectional drawing of FIG.

Explanation of symbols

10 discharge tube
12 Case material
14 Lid member
16 Airtight envelope
18 Discharge electrode
20 joints
22 Discharge gap
24 Inner wall surface of case member
26 Micro discharge gap
28 Trigger discharge membrane
29 holes
30 Coating X Circle concentric with the inner wall surface of the cylindrical case member Y Circle concentric with the inner wall surface of the cylindrical case member

Claims (4)

  A hermetic envelope is formed by hermetically sealing the opening portions at both ends of the cylindrical case member with a pair of lid members that also serve as discharge electrodes, and neon, argon, and hydrogen are formed in the hermetic envelope. And a discharge gap is formed between the discharge electrode portions of the lid member disposed in the hermetic envelope, and both ends of the lid are formed on the inner wall surface of the case member. Forming a plurality of trigger discharge films arranged with a gap between the member and the minute discharge gap, and further forming a plurality of holes on the surface of the discharge electrode part, and sodium iodide, molybdenum on the inner surface of the hole part; A discharge tube in which a film containing cesium oxide, potassium molybdate and rubidium bromide is formed, wherein the numerous holes are arranged and formed on a circle concentric with the inner wall surface of the cylindrical case member. Discharge characterized by .   The discharge tube according to claim 1, wherein the hole portion has a substantially hemispherical shape.   The sodium iodide content is 0.01 to 40% by weight, the cesium molybdate content is 0.01 to 40% by weight, the potassium molybdate content is 0.01 to 40% by weight, and rubidium bromide. The discharge tube according to claim 1 or 2, wherein the content ratio is 0.01 to 40 weight.   The neon mixing ratio is 0.1 to 70% by volume, the argon mixing ratio is 0.1 to 70% by volume, and the hydrogen mixing ratio is 0.1 to 70% by volume. Item 4. The discharge tube according to any one of Items 1 to 3.

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