JP2008251389A - Discharge tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge tube capable of reducing dispersion of a discharge characteristic by stabilizing the condition of a coating film formed on the inside surface of each hole part on a surface of a discharge electrode. <P>SOLUTION: An airtight envelope 16 is formed by sealing openings at both ends of a case member 12 with a pair of lid member 14, 14 doubling as discharge electrodes; a discharge space 22 is formed between discharge electrode parts 18, 18 of the lid members 14, 14; a discharge gas is filled in the airtight envelope 16; a plurality of trigger discharge films 28 having both their ends arranged by being spaced apart from the lid members 14, 14 with minute discharge spaces 26 are formed on the inside surface 24 of the case member 12; multiple nearly-hemispherical hole parts 29 are formed on the discharge electrode parts 18; and a coating film 30 containing a substance having an excellent electron emission characteristic is formed on the inside surface of each hole part 29. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge tube, and 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. 3125263.
As shown in FIGS. 14 to 17, the discharge tube 60 is formed by sealing a cylindrical case member 62 made of an insulating material having both ends open 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 pairs of trigger discharge films 78 and 78 are formed in the circumferential direction of the inner wall surface 74 of the case member 62 so as to face each other with a minute discharge gap 76 therebetween. Of the pair of trigger discharge films 78, 78, one trigger discharge film 78 is electrically connected to one discharge electrode portion 68, and the other trigger discharge film 78 is electrically connected to the other discharge electrode portion 68. It is connected.

As shown in FIG. 15, a large number of bottomed holes 79 are formed on the surface of the discharge electrode portion 68, and cesium bromide (CsBr) or the like is formed on the inner surface of the hole 79 and the surface of the discharge electrode portion 68. A film 80 containing a material having good electron emission characteristics is formed. The coating 80 can be formed by applying a powder of a substance having good electron emission characteristics such as cesium bromide to a binder made of a sodium silicate solution and pure water, and coating the surface of the discharge electrode portion 18. it can.
A margin portion 81 where the coating film 80 is not formed is provided along the peripheral edge of the surface of the discharge electrode portion 68.

The discharge gas sealed in the hermetic envelope 66 corresponds to, for example, a discharge gas configured by mixing hydrogen (H ₂ ) in a mixed gas of neon (Ne) and argon (Ar).

  In the conventional discharge tube 60, 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 serving also as discharge electrodes, both ends of the trigger discharge film 78 are applied. Then, the electric field concentrates in the minute discharge gap 76 between the lid members 64 and 64, and thereby 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, the 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.

Thus, in the discharge tube 60, a large number of holes 79 are formed on the surface of the discharge electrode portion 68, and a substance having good electron emission characteristics is formed on the inner surface of the hole 79 and the surface of the discharge electrode portion 68. By forming the coating film 80 contained, the adhesion between the coating film 80 and the discharge electrode portion 68 is improved, the sputtering of the coating film 80 due to impact during discharge can be suppressed, and fluctuations in the discharge start voltage can occur. A long-life discharge tube can be realized.
Utility model registration No. 3125263

  By the way, in the conventional discharge tube 60, the hole 79 formed on the surface of the discharge electrode portion 68 is formed in a “substantially rectangular parallelepiped shape”. Therefore, the state of the coating film 80 formed on the inner surface of the hole 79 is As a result, the discharge characteristics were not uniform. The reason for this is that when the hole 79 is formed in a “substantially rectangular parallelepiped shape” as in the conventional discharge tube 60, surface tension is applied from the four directions of the hole 79, and as a result, the coating 80 is applied in any direction. This is because the state of the film 80 is not stable.

  The present invention has been made in view of the above-described conventional problems, and its object is to stabilize the state of the coating formed on the inner surface of the hole on the surface of the discharge electrode and reduce variations in discharge characteristics. It is to realize a discharge tube that can be used.

  In order to achieve the above object, a discharge tube according to the present invention includes a plurality of discharge electrodes arranged with a discharge gap therebetween, which is enclosed in a hermetic envelope together with a discharge gas, and a large number of discharge electrodes are formed on the surface of the discharge electrode. A discharge tube formed by forming a coating containing a substance having a good electron emission property on the inner surface of the hole, wherein the hole is substantially hemispherical. .

  In the discharge tube according to the present invention, the hole formed in the surface of the discharge electrode is formed in a “substantially hemispherical shape”, thereby stabilizing the state of the coating 30 and reducing variations in discharge characteristics. it can. That is, as in the discharge tube 10 of the present invention, when the hole 29 is formed to be “substantially hemispherical”, the surface tension is uniformly applied from all directions of the hole 29, and as a result, the coating 30 is omnidirectional. Since it is formed uniformly, the state of the coating 30 can be stabilized and variations in discharge characteristics can be reduced.

  As shown in FIGS. 1 and 2, a discharge tube 10 according to the present invention has a pair of lids 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 the members 14 and 14.

The lid member 14 has, on its inner surface, a discharge electrode portion 18 having a flat surface protruding toward the center of the hermetic envelope 16, and a joint portion 20 in contact with the end surface of the case member 12 on its outer surface side. A predetermined discharge gap 22 is formed between the surfaces of the discharge electrode portions 18, 18 of the lid members 14, 14. The discharge electrode portion 18 has a cylindrical cross section (FIG. 2). Although details will be described later, a rectangular convex portion 21 is formed on the outer surface of the lid members 14 and 14.
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.

Further, the inner wall surface 24 of the case member 12 constituting the hermetic envelope 16 has a linear shape in which both ends thereof are arranged with a small discharge gap 26 therebetween and the lid members 14 and 14 that also serve as discharge electrodes. A plurality of trigger discharge films 28 are formed. 1 and 2 exemplify a case where eight trigger discharge films 28 are formed at 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.

  As shown in FIGS. 3 to 5, a large number of substantially hemispherical hole portions 29 are formed on the surface of the discharge electrode portion 18, and the inner surface of each hole portion 29 contains a substance having good electron emission characteristics. The coated film 30 is formed. In the present embodiment, a total of 16 4 × 4 hole portions 29 are arranged and formed in a matrix, but the present invention is not limited to this.

The coating film 30 containing a substance having good electron emission characteristics can be formed of, for example, the coating film 30 containing cesium bromide (CsBr). The coating 30 can be formed by applying a powder of cesium bromide added to a binder composed of a sodium silicate solution and pure water to the surface of the discharge electrode portion 18.
In this case, cesium bromide is mixed at a blending ratio of 0.01 to 70% by weight and binder is 99.99 to 30% by weight.
The blending ratio of the sodium silicate solution and pure water in the binder is such that the sodium silicate solution is 0.01 to 70% by weight and the pure water is 99.99 to 30% by weight.

A predetermined discharge gas is sealed in the hermetic envelope 16. As this discharge gas, for example, a discharge gas configured by mixing hydrogen (H ₂ ) in a mixed gas of neon (Ne) and argon (Ar) is applicable.

  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 also serving 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.

  Thus, in the discharge tube 10 of the present invention, a large number of hole portions 29 are formed on the surface of the discharge electrode portion 18, and the coating 30 containing a substance having good electron emission characteristics is formed on the inner surface of the hole portion 29. As a result, the adhesion between the coating film 30 and the discharge electrode portion 18 is improved, and the sputtering of the coating film 30 due to impact during discharge can be suppressed, and as a result, the discharge start voltage does not fluctuate. A long-life discharge tube can be realized.

In the discharge tube 10 of the present invention, the hole portion 29 formed on the surface of the discharge electrode portion 18 is formed in a “substantially hemispherical shape”, so that the hole portion 79 is “substantially similar to the conventional discharge tube 60”. Compared with the case of “cuboid”, the state of the coating 30 is stabilized, and variations in discharge characteristics can be reduced.
That is, as in the conventional discharge tube 60, when the hole 79 has a “substantially rectangular parallelepiped shape”, surface tension is applied from the four directions of the hole 79, and as a result, the coating 80 is biased in any direction. Therefore, the state of the film 80 was not stable.
On the other hand, when the hole 29 is formed to be “substantially hemispherical” like the discharge tube 10 of the present invention, the surface tension is applied uniformly from all directions of the hole 29, and as a result, the coating film 30 is entirely applied. Since it is formed evenly in the direction, the state of the coating 30 can be stabilized, and variations in discharge characteristics can be reduced.

In the following, a method for forming the coating 30 on the inner surface of the hole 29 on the surface of the discharge electrode portion 18 will be described with reference to FIGS.
6 and 7, reference numeral 31 denotes an electrode forming jig according to the present invention. The electrode forming jig 31 includes a flat base portion 33 and a protrusion standing from the upper surface of the base portion 33. A portion 35 and a needle-like portion 37 suspended from the lower surface of the base portion 33 are provided.
As shown in FIG. 9, the needle-like portion 37 is provided with 16 pieces as many as the number of the holes 29 of the discharge electrode portion 18, and as shown in FIGS. 6 and 7, an electrode forming jig 31 is provided. Is disposed above the hole 29 of the discharge electrode 18, the needles 37 are arranged in a matrix so as to have a one-to-one correspondence with the holes 29 of the discharge electrode 18. . Note that the diameter of at least the tip of the needle-like portion 37 is set to a dimension equal to or smaller than the diameter of the hole 29.
Incidentally, the diameter of the hole 29 is about 0.2 mm, and the diameter of the needle-like part 37 is about 0.18 mm.

In order to form the coating 30 on the inner surface of the hole 29, first, a liquid binder made of a sodium silicate solution to which a powder made of a material having a good electron emission characteristic such as cesium bromide (CsBr) is added and pure water is prepared. .
The lid member 14 is arranged so that the hole 29 on the surface of the discharge electrode portion 18 is on the upper side.
Next, the needle-shaped part 37 of the electrode forming jig 31 is immersed in the binder, and the binder 39 is attached to the surface of the needle-shaped part 37.
Next, the electrode forming jig 31 is disposed above the hole 29 of the discharge electrode portion 18 so that the needle-like portion 37 to which the binder 39 is attached and the hole 29 of the discharge electrode portion 18 are made to correspond one-to-one. After that, the binder 39 is dropped from the tip of the needle-shaped portion 37 into the hole 29 (FIG. 7). As a result, a binder 39 to which a powder made of a substance having good electron emission characteristics is applied is applied to the inner surface of the hole 29, and when this binder 39 is dried, a coating 30 is formed on the inner surface of the hole 29 as shown in FIG. Is formed.

  In the above-described method for forming the coating film 30 of the present invention, an electrode forming jig 31 provided with a needle-like portion 37 having a one-to-one correspondence with the hole portion 29 of the discharge electrode portion 18 is used. A needle-shaped part 37 to which a liquid binder to which a powder made of a substance having a good release property is added is attached to a hole part 29 of the discharge electrode part 18 in a one-to-one correspondence. Since it is dropped into the hole 29 from the tip of the portion 37, the thickness and amount of the binder applied to the inner surface of each hole 29 are substantially uniform, and as a result, the coating 30 on the inner surface of each hole 29 formed after drying The thickness and amount can be made substantially uniform.

In addition, in the method of applying a binder using a microdispenser (microdispensing device) like the conventional discharge tube 60, the binder is also applied to the surface of the discharge electrode portion 68 other than the inner surface of the hole portion 79, and as a result. The dried coating 80 was formed not only on the inner surface of the hole 79 but also on the surface of the discharge electrode 68 (FIGS. 14 to 17). Thus, the coating film 80 formed on the surface of the discharge electrode portion 68 is thin, and the adhesive force with the discharge electrode portion 68 is weaker than the coating film 80 on the inner surface of the hole 79. Spatter could occur due to the impact of time.
On the other hand, in the method for forming the coating film 30 according to the present invention, the coating electrode 30 is disposed in a positional relationship corresponding to the hole 29 of the discharge electrode portion 18 on a one-to-one basis, and the diameter of the tip portion is the hole. Using the electrode forming jig 31 provided with a needle-shaped portion 37 having a size equal to or smaller than the diameter of the portion 29, the needle-shaped portion 37 to which a liquid binder added with a powder made of a substance having a good electron emission property is attached; Since the binder 39 is dropped into the hole 29 from the tip of the needle-shaped part 37 after the hole part 29 of the discharge electrode part 18 is made to correspond one-to-one, the binder 39 is applied only to the inner surface of the hole part 29. Can be applied. Therefore, the coating film 30 formed after drying can also be formed only on the inner surface of the hole 29.

Next, a method for forming the coating film 30 on the inner surface of the hole 29 on the surface of the discharge electrode portion 18 of a large number of lid members 14 using a pallet will be described.
As shown in FIG. 10, a convex portion 21 as a rectangular positioning portion is formed on the outer surface of the lid member 14.
Further, as shown in FIG. 11, the pallet 41 is formed with a large number of concave portions 43 for accommodating the convex portions 21 of the lid member 14. The concave portion 43 is formed in a rectangular shape that is substantially the same shape as the outer shape of the convex portion 21 of the lid member 14, and the convex portion 21 of the lid member 14 and the concave portion 43 of the pallet 41 are fitted to each other, so that the lid member 14 Is supposed to be fixed.

First, the convex portions 21 of the lid member 14 are fitted and fixed to the concave portions 43 of the pallet 41, respectively. As a result, a large number of lid members 14 are arranged on the pallet 41 in a state where the hole 29 on the surface of the discharge electrode 18 is arranged on the upper side (FIG. 12).
Thereafter, in the same manner as described above, the electrode forming jig 31 is disposed above the hole 29 of the discharge electrode portion 18 of each lid member 14, and the needle-like portion 37 to which the binder 39 is adhered and the hole of the discharge electrode portion 18 are disposed. After associating the portion 29 with the one-to-one correspondence, the binder 39 is dropped from the tip of the needle-like portion 37 into the hole portion 29 (see FIG. 13). As a result, a binder 39 to which a powder made of a substance having a good electron emission characteristic is added is applied to the inner surface of the hole 29, and the coating film 30 is formed on the inner surface of the hole 29 by drying the binder 39.

In the method of the present invention, a pallet 41 in which a large number of concave portions 43 are formed is used, and the convex portions 21 of the lid member 14 are stored and fixed in the concave portions 43 of the pallet 41. Since the coating film 30 is formed on the inner surface of the hole 29 of each discharge electrode portion 18 in the state of being aligned on the top, the coating film formation of a large number of discharge electrode portions 18 can be performed in a short time.
Moreover, as a result of the projection 21 of the lid member 14 and the recess 43 of the pallet 41 being fitted together, the lid member 14 is fixed, so that the orientation of the holes 29 of the numerous lid members 14 arranged on the pallet 41 is constant. Therefore, the operation of applying the binder 39 using the electrode forming jig 31 can be easily performed.

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 a principal part expanded sectional view of the discharge tube which concerns on this invention. It is CC schematic sectional drawing of FIG. It is an enlarged view which shows the discharge electrode part surface of the discharge tube which concerns on this invention. It is explanatory drawing which shows the method of forming a film in the hole inner surface of the discharge electrode part surface. It is explanatory drawing which shows the method of forming a film in the hole inner surface of the discharge electrode part surface. It is explanatory drawing which shows the method of forming a film in the hole inner surface of the discharge electrode part surface. It is a bottom view which shows the jig for electrode formation which concerns on this invention. It is explanatory drawing which shows the outer surface shape of a cover member. It is explanatory drawing which shows the method of forming a film in the hole inner surface of many discharge electrode parts. It is explanatory drawing which shows the method of forming a film in the hole inner surface of many discharge electrode parts. It is explanatory drawing which shows the method of forming a film in the hole inner surface of many discharge electrode parts. It is sectional drawing which shows the conventional discharge tube. It is a principal part expanded sectional view of the conventional discharge tube. It is an AA schematic sectional drawing of FIG. It is an enlarged view which shows the discharge electrode part surface of the conventional discharge tube.

Explanation of symbols

10 discharge tube
12 Case material
14 Lid member
16 Airtight envelope
18 Discharge electrode
21 Convex
22 Discharge gap
26 Micro discharge gap
28 Trigger discharge membrane
29 holes
30 coating
31 Electrode forming jig
37 Needle-shaped part
39 binder
41 palettes
43 recess

Claims (1)

  A plurality of discharge electrodes are arranged with a discharge gap therebetween, and this is enclosed in a hermetic envelope together with a discharge gas to form a large number of holes on the surface of the discharge electrode, and electrons are emitted to the inner surface of the holes. A discharge tube formed by forming a film containing a substance having good characteristics, wherein the hole portion is substantially hemispherical.

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