JP2016115519A - Hot cathode grid control discharge tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot cathode grid control discharge tube capable of stabilizing the operation by enhancing the effect to prevent an oxide which is evaporated from hot cathode from adhering onto grid electrode.SOLUTION: The hot cathode grid control discharge tube 10 includes: a hot cathode 11; a shield electrode 12; an anode 14; a grid electrode 15; and a baffle 13. The shield electrode 12 has a cylindrical shape enclosing the hot cathode 11 and has an opening 22. The anode 14 opposes the opening 22 of the shield electrode 12. The grid electrode 15 is disposed being interposed between the opening 22 of the shield electrode 12 and the anode 14. The baffle 13 is formed to have a larger diameter than that of the opening 22 of the shield electrode 12, and is disposed in an area where the hot cathode 11 and the grid electrode 15 are faced to each other via the opening 22.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to a hot cathode grid controlled discharge tube used as a switch in a high voltage, high power circuit.

  Conventionally, a hot cathode grid controlled discharge tube has been used as a switch for a high voltage, high power circuit. In this hot cathode grid controlled discharge tube, the hot cathode is surrounded by a shielding electrode, the anode is opposed to the hot cathode, and the grid electrode is interposed between the hot cathode and the anode.

  In general, a hot cathode of a hot cathode lattice controlled discharge tube is one in which an oxide is applied to the surface of a metal plate, which is heated to emit thermoelectrons. In the hot cathode, the oxide applied to the surface of the metal plate evaporates due to heating during operation and impact of cations, and the oxide adheres to the shielding electrode and the grid electrode. Since the lattice electrode is heated to high temperatures due to radiation and discharge from the hot cathode, if an oxide is attached, electrons are emitted from the lattice electrode, resulting in unstable operation.

  Therefore, a baffle is provided between the hot cathode and the grid electrode so as to suppress the adhesion of oxide to the grid electrode.

JP-A-3-25833

  However, since it is necessary to form a discharge path through which thermionic electrons pass between the hot cathode and the grid electrode, the region where the hot cathode and the grid electrode are opposed cannot be completely blocked by the baffle. The effect of suppressing the adhesion of oxide to the grid electrode is limited.

  The problem to be solved by the present invention is to provide a hot cathode lattice controlled discharge tube capable of enhancing the effect of suppressing the adhesion of oxide evaporated from the hot cathode to the lattice electrode and stabilizing the operation.

  The hot cathode grid controlled discharge tube of this embodiment includes a hot cathode, a shield electrode, an anode, a grid electrode, and a baffle. The shielding electrode is cylindrical and surrounds the hot cathode and has an opening. The anode faces the opening of the shielding electrode. The grid electrode is interposed between the opening of the shielding electrode and the anode. The baffle is formed to have a larger diameter than the opening of the shielding electrode, and is interposed in a region where the hot cathode and the grid electrode face each other through the opening.

It is the perspective view which made a part of hot cathode lattice control discharge tube which shows one embodiment into a section. It is the perspective view which made a part of hot cathode lattice control discharge tube which shows a comparative example into the section.

  Hereinafter, an embodiment will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a perspective view in which a part of a hot cathode grid controlled discharge tube 10 showing a preferred embodiment is shown in cross section.

  The hot cathode lattice controlled discharge tube 10 includes a hot cathode 11, a shielding electrode 12 coaxially surrounding the hot cathode 11, a baffle 13 provided with the shielding electrode 12, an anode 14 disposed coaxially with the hot cathode 11, And a lattice electrode 15 interposed between the hot cathode 11 and the anode 14. And these are accommodated in an envelope and gas is enclosed in the envelope.

  The hot cathode 11 is formed in a substantially cylindrical shape, and a metal plate whose surface is coated with an oxide is used. Thermal electrons are emitted by heating.

  The shield electrode 12 includes a body portion 20 that coaxially surrounds the hot cathode 11, and a cylindrical portion 21 that is disposed on the end side of the hot cathode 11. An opening 22 is formed at the center of the tube portion 21. The opening portion 22 is formed in a circular shape having a smaller diameter than the body portion 20, and the cylindrical portion 21 is formed in a conical shape so that the outer diameter decreases toward the opening portion 22. The anode 14 and the grid electrode 15 are opposed to the opening 22 of the shielding electrode 12.

  The baffle 13 is disposed inside the opening 22 of the shielding electrode 12, and is supported by the shielding electrode 12 by a support 23. The baffle 13 is formed to have a larger diameter than the opening 22 of the shielding electrode 12, and is interposed so as to cover the entire region where the hot cathode 11 and the grid electrode 15 directly face each other through the opening 22. Specifically, the baffle 13 is formed in a conical shape so that the outer diameter is larger than the opening 22 of the shielding electrode 12 and the diameter decreases toward the grid electrode 15. A discharge path 24 between the hot cathode 11 and the anode 14 is formed between the tube portion 21 and the inner surface of the tube portion 21 in parallel.

  Therefore, the shielding electrode 12 including the baffle 13 is formed such that the end side including the opening 22 and the discharge path 24 has a double cylindrical structure.

  In the hot cathode lattice controlled discharge tube 10, the hot cathode 11 is heated, and the potential of the grid electrode 15 is controlled in a state where a voltage is applied between the hot cathode 11 and the anode 14, whereby the hot cathode 11 The hot electrons are extracted from the hot cathode 11, the discharge is generated between the hot cathode 11 and the anode 14, and the switch is closed.

  In the hot cathode 11, the oxide applied to the surface of the metal plate evaporates due to heating during operation and impact of cations. The shielding electrode 12 provided with the baffle 13 suppresses the oxide evaporated from the hot cathode 11 from adhering to the grid electrode 15.

  Here, a hot cathode grid controlled discharge tube 10 of a comparative example will be described with reference to FIG. The same reference numerals as those of the hot cathode grid controlled discharge tube 10 of the present embodiment are used.

  The cylindrical portion 21 of the shielding electrode 12 is provided in a cylindrical shape. The baffle 13 has a smaller diameter than the opening 22 of the cylindrical portion 21 and is disposed at the center of the opening 22. An opening 22 (discharge path 24) is formed between the tube portion 21 and the baffle 13. The hot cathode 11 and the grid electrode 15 are directly opposed to each other through the opening 22 (discharge path 24).

  Therefore, some of the oxide evaporated from the hot cathode 11 toward the grid electrode 15 adheres to the baffle 13, but the other part of the oxide remains in the opening 22 (discharge path 24). It adheres to the grid electrode 15 through.

  Since it is necessary to form an opening 22 (discharge path 24) between the tube portion 21 and the baffle 13, the region where the hot cathode 11 and the grid electrode 15 directly face each other cannot be completely blocked by the baffle 13. In other words, the effect of suppressing the adhesion of oxide to the grid electrode 15 by the baffle 13 is limited.

  On the other hand, in the hot cathode lattice controlled discharge tube 10 of the present embodiment shown in FIG. 1, the baffle 13 is formed larger in diameter than the opening 22 of the shielding electrode 12, and the hot cathode 11 and the lattice electrode are passed through the opening 22. 15 is interposed so as to cover the entire area directly facing, so that the effect of suppressing the adhesion of oxide evaporated from the hot cathode 11 to the grid electrode 15 is enhanced, and the operation of the hot cathode grid controlled discharge tube 10 is stabilized. Can be planned.

  More specifically, the baffle 13 is formed in a conical shape so that the outer diameter is larger than the opening 22 of the shielding electrode 12 and the diameter decreases toward the grid electrode 15, and the inner surface of the cylindrical portion 21 And a discharge path 24 through which thermionic electrons pass from the hot cathode 11 toward the opening 22 is formed between the hot cathode 11 and the grid electrode 15 through the opening 22. Are not directly opposed to each other, the effect of suppressing the adhesion of oxide evaporated from the hot cathode 11 to the grid electrode 15 can be enhanced, and the operation of the hot cathode grid control discharge tube 10 can be stabilized.

  Further, since the shielding electrode 12 including the baffle 13 has a double cylindrical structure on the end side including the opening 22 and the discharge path 24, the discharge path 24 between the hot cathode 11 and the grid electrode 15 is formed. It is possible to ensure that the oxide evaporated from the hot cathode 11 is not directed straight to the grid electrode 15.

  The baffle 13 is not limited to being formed in a conical shape, and may be formed in a curved surface shape or a flat plate shape. In any shape, the baffle 13 is formed to have a larger diameter than the opening 22 of the shielding electrode 12, and is interposed so as to cover the entire region where the hot cathode 11 and the grid electrode 15 directly face each other through the opening 22. That's fine.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10 Hot cathode grid controlled discharge tube
11 Hot cathode
12 Shielding electrode
13 Baffle
14 Anode
15 Grid electrode
21 Tube
22 opening
24 discharge path

Claims (3)

A hot cathode;
A cylindrical shielding electrode surrounding the hot cathode and having an opening;
An anode facing the opening of the shielding electrode;
A grid electrode interposed between the opening of the shielding electrode and the anode;
A hot cathode grid controlled discharge, comprising: a baffle formed in a larger diameter than the opening of the shielding electrode and interposed in a region where the hot cathode and the grid electrode face each other through the opening. tube. The hot cathode grid controlled discharge tube according to claim 1, wherein the baffle is disposed inside the opening of the shielding electrode. The shielding electrode has a cylindrical portion whose diameter decreases toward the opening,
The baffle is formed in a conical shape so as to decrease in diameter toward the lattice electrode, and is opposed to an inner surface of the cylinder part and forms a discharge path between the cylinder part. Item 3. The hot cathode grid controlled discharge tube according to Item 1 or 2.

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