JPH11297222A - Vacuum microswitching element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a cathode electrode and a gate electrode from being damaged when discharge is generated between the cathode electrode and an anode electrode in an OFF state by arranging a shielding electrode around a cathode electrode group in a vacuum vessel, and holding the shielding electrode in the same electric potential as the cathode electrode. SOLUTION: In a vacuum microswitching element 20, a cathode electrode substrate 1 on which plural cathode electrodes 2 are formed, a gate electrode 3 and an anode electrode 4 are housed in a vacuum vessel 5. The cathode electrode substrate 1 and the anode electrode 4 are insulated from the vacuum vessel 5 through an insulating bushing 6, and voltage is impressed on the gate electrode 3 through a voltage introducing terminal 7 from a gate driving circuit 8. On the cathode electrode substrate 1, an annular shielding electrode 21 is arranged around a cathode electrode group composed of the plural cathode electrodes 2, and the shielding electrode 21 is electrically connected to the cathode electrode 2 to be held in the same electric potential.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high withstand voltage of a vacuum microswitching element having a field emission cold cathode.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view showing a conventional vacuum micro-switching device disclosed in Japanese Patent Application Laid-Open No. 8-87964. In FIG. 8, reference numeral 1 denotes a cathode electrode substrate, and 2 denotes a cathode electrode formed on the cathode electrode substrate 1 and having a sharp tip for emitting electrons by a field emission effect. Reference numeral 3 denotes a gate electrode which is disposed near the cathode electrode 2 and controls the electric field strength at the tip of the cathode electrode 2. 4
Is an anode electrode for collecting electrons emitted from the cathode electrode 2, 5 is a vacuum container for storing the cathode electrode substrate 1, the gate electrode 3 and the anode electrode 4, and 6 is a vacuum container 5 and the cathode electrode substrate 1 and the anode. This is an insulating bushing for insulating the electrode 4. Reference numeral 7 denotes a voltage introduction terminal for introducing a voltage applied to the gate electrode 3, and reference numeral 8 denotes a gate drive circuit for controlling the voltage applied to the gate electrode 3.

Next, the operation will be described. As one of applications of the field emission type cold cathode to a power element, there is a vacuum microswitching element having a configuration similar to a triode. Since this element is a high-voltage element, a single high-voltage switching element obtained by connecting several tens of thyristors or GTOs having a withstand voltage characteristic of several kV in series is manufactured.

When a positive voltage of several volts is applied to the gate electrode 3 from the gate drive circuit 8 through the voltage introducing terminal 7 with respect to the cathode electrode 2, an extremely high electric field is generated
And electrons are extracted by the tunnel effect. When the electrons emitted from the cathode electrode 2 reach the anode electrode 4, conduction between the cathode electrode 2 and the anode electrode 4 (on state). The amount of current flowing between these electrodes is controlled by the amount of electrons described above, and the amount of electrons is controlled by the voltage applied to the gate electrode 3.

[0005]

Since the conventional vacuum microswitching element is configured as described above, when the cathode electrode 2 and the anode electrode 4 are not electrically connected (off state), the cathode microelectrode 2 is turned off. And anode electrode 4
During this period, an AC high voltage is usually applied. Anode electrode 4
When the voltage phase becomes negative high voltage, the anode electrode 4
A discharge occurs due to minute projections on the surface of the substrate, causing a problem that the cathode electrode 2 and the gate electrode 3 are damaged, and there is a problem that it is difficult to achieve a high withstand voltage.

Further, the vacuum microswitching element is a high-voltage element, and the distance between the electrodes is large. Therefore, when the space between the cathode electrode 2 and the anode electrode 4 is in the ON state, electrons emitted from the cathode electrode 2 are wide. It diverges while traveling between the electrodes. Therefore, the anode electrode 4
In order to completely capture electrons in the method described above, there is a problem that the radial dimension of the anode electrode 4 needs to be larger than that of the cathode electrode substrate 1.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to achieve a high voltage with a single element. It is another object of the present invention to provide an element capable of efficiently collecting electrons on the anode electrode.

[0008]

According to the present invention, there is provided a vacuum microswitching device comprising: a cathode electrode for emitting electrons;
A gate electrode for controlling the emission of electrons, an anode electrode for collecting emitted electrons, and a shield electrode disposed around a cathode electrode group composed of the plurality of cathode electrodes are placed in a vacuum vessel. Wherein the shield electrode is maintained at the same potential as the cathode electrode, and discharge occurs between the cathode electrode and the anode electrode when the anode electrode is off.

Further, the shield electrode is provided on the cathode electrode substrate on which the cathode electrode is formed so as to surround the cathode electrode group.

Further, the shield electrode is constituted by an insulating shield electrode provided on a cathode electrode substrate on which a cathode electrode is formed so as to surround the cathode electrode group and via an insulating member. .

Further, the shield electrode is provided so as to surround the cathode electrode group, and is supported on an inner wall of the vacuum vessel.

Further, the above-mentioned shield electrode is characterized by comprising an insulating shield electrode provided so as to surround the cathode electrode group and supported on the inner wall of the vacuum vessel via an insulating member.

Further, the insulating shield electrode is connected to a control power supply for supplying a potential to the shield electrode independently of the cathode electrode, and supplies a potential different from the potential of the cathode electrode to the insulating shield electrode. And

Further, the control power source is characterized in that when the space between the cathode electrode and the anode electrode is in an on state, the insulating shield electrode is kept at a lower potential than the cathode electrode.

Further, the insulation shield electrode is divided in the circumferential direction, and the control power supply can supply different voltages to the divided insulation shield electrodes.

Further, a central shield electrode maintained at the same potential as the cathode electrode is further provided at the center of the cathode electrode group.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram schematically showing a configuration of a vacuum micro-switching device according to a first embodiment of the present invention. In FIG. 1, the vacuum microswitching element 20 includes a plurality of cathode electrodes 2.
A cathode electrode substrate 1 on which is formed, a gate electrode 3,
And an anode electrode 4, which are stored in a vacuum vessel 5. Cathode electrode substrate 1 and anode electrode 4
Are insulated from the vacuum vessel 5 via an insulating bushing 6. A voltage is applied to the gate electrode 3 from the gate drive circuit 8 via the voltage introduction terminal 7. On the cathode electrode substrate 1, an annular shield electrode 21 is arranged around a cathode electrode group constituted by a plurality of cathode electrodes 2. The shield electrode 21 is electrically connected to the cathode electrode 2, and these are kept at the same potential.

Since minute projections on the surface of the anode electrode 4 cause dielectric breakdown in a vacuum, the surface of the anode electrode 4 is evacuated while the vacuum container 5 is evacuated or after the vacuum container 5 is vacuum-sealed. In order to eliminate the protrusion, a negative voltage having a large absolute value is applied to the anode electrode 4 to forcibly generate a spark discharge between the anode electrode 4 and the shield electrode 21. Thereby, the protrusion on the surface of the anode electrode 4 can be eliminated, and a high withstand voltage as a switching element can be achieved.

When the vacuum microswitching element 20 is operating in a system and the space between the cathode electrode 2 and the anode electrode 4 is off, a negative voltage is applied to the anode electrode 4 side. Also, the anode electrode 4
Since discharge occurs only between the shield electrode 21 and
It is possible to prevent the cathode electrode 2 or the gate electrode 3 from being damaged by a discharge generated when the space between the cathode electrode 2 and the anode electrode 4 is in an off state.

As described above, according to the vacuum microswitching device according to the first embodiment of the present invention, when the space between the cathode electrode 2 and the anode electrode 4 is in the off state, the negative voltage is applied to the anode electrode 4 side. Is applied, the occurrence of damage to the cathode electrode 2 or the gate electrode 3 can be suppressed, and a high withstand voltage as a switching element can be achieved.

Embodiment 2 FIG. FIG. 2 is a top view schematically showing a main part of a vacuum cathode electrode switching element according to Embodiment 2 of the present invention. In FIG. 2, 22 is
This is a central shield electrode provided at the center of a cathode electrode group composed of a plurality of cathode electrodes 2. The center shield electrode 22 is electrically connected and mounted on the cathode electrode substrate 1. Reference numeral 23 denotes a shield electrode provided on the cathode electrode substrate 1 around a cathode electrode group including a plurality of cathode electrodes. The shield electrode 23 is divided in the circumferential direction of the cathode electrode substrate 1, but may be an undivided annular shield electrode as in the first embodiment.

When the outer diameter of the cathode electrode substrate 1 is considerably larger than the electrode spacing between the anode electrode 4 and the cathode electrode 2 (D> 3d, where D: cathode electrode outer diameter,
d: electrode spacing), the shield effect of the shield electrode 23 is reduced, and there is a possibility that discharge occurs inside the cathode electrode substrate 1. In order to prevent this, in the vacuum microswitching element according to the second embodiment of the present invention, a central shield electrode 22 is provided at the center of cathode electrode substrate 1 so that the discharge at the time of off is shielded by shield electrode 23 or central shield. It is possible to prevent the cathode electrode 2 or the gate electrode 3 from being generated between the electrode 22 and the discharge, thereby preventing the discharge from occurring.

As described above, according to the vacuum micro-switching device according to the second embodiment of the present invention, when the space between cathode electrode 2 and anode electrode 4 is in the off state, a negative voltage is applied to anode electrode 4 side. Even if the voltage is applied, a discharge is generated between the anode electrode 4 and the central shield electrode 22 and the shield electrode 23, so that damage to the cathode electrode 2 or the gate electrode 3 can be suppressed, and the outer diameter of the cathode electrode substrate 1 is reduced. However, even when the distance between the anode electrode 4 and the cathode electrode 2 is considerably larger than that between the anode electrode 4 and the cathode electrode 2, a high withstand voltage as a switching element can be achieved.

Embodiment 3 FIG. FIG. 3 is a diagram schematically showing a configuration of a vacuum microswitching device according to Embodiment 3 of the present invention. In FIG. 3, an insulating shield electrode 24 is provided around a cathode electrode group constituted by a plurality of cathode electrodes 2 on a cathode electrode substrate 1 via an insulating spacer 25 which is an insulating member. , A voltage is applied from the insulating shield electrode control circuit 26 via the voltage introduction terminal 7.

When the same voltage as that of the cathode electrode substrate 1 is applied from the insulating shield electrode control circuit 26 to the insulating shield electrode 24, a discharge caused by minute projections on the surface of the anode electrode 4 causes a discharge between the insulating shield electrode 24 and the insulating shield electrode 24. Therefore, the cathode electrode 2 or the gate electrode 3 can be prevented from being damaged by the discharge. Also, if a negative potential is applied to the potential of the cathode electrode 2 during operation of the vacuum microswitching element, the electron orbit works in a direction converging to the center. Can be smaller.

As described above, according to the vacuum microswitching device according to the third embodiment of the present invention, even if a negative voltage is applied to the anode electrode 4 side, the cathode electrode 2 or the gate electrode 3 is not damaged. It is possible to suppress the occurrence and to achieve high withstand voltage as a switching element. Further, since the region of the electrons collected by the anode electrode 4 can be reduced, a switching element having a small anode area can be provided.

Embodiment 4 FIG. 4 is a top view showing a main part of a vacuum microswitching element according to Embodiment 4 of the present invention. 4, reference numeral 24 denotes an insulating shield electrode mounted on the cathode electrode substrate 1 via an insulating spacer (similar to the insulating spacer 25 in FIG. 3). According to such a configuration, Embodiment 4 of the present invention
In the vacuum microswitching device according to the above, an independent voltage is applied from the insulating shield electrode control circuit 26 to each of the divided insulating shield electrodes 24.

When the trajectory of the electrons emitted from the cathode electrode 2 is eccentric, an optimum voltage is applied to each of the insulating shield electrodes 24 from the insulating shield electrode control circuit 26 so that the electrons converge toward the center. Because it works
A switching element having a small anode area can be provided. When the same voltage as that of the cathode electrode 2 is applied to each of the divided insulating shield electrodes 24,
Since a discharge caused by the minute protrusion on the anode electrode 4 is generated between the insulating shield electrode 24 and the cathode electrode 2, the gate electrode 3 or the gate electrode 3 can be protected from damage due to the discharge.

As described above, according to the vacuum micro-switching device according to the fourth embodiment of the present invention, even when a negative voltage is applied to the anode electrode 4 side, the trajectory of electrons emitted from the cathode electrode 2 Electrons are collected by the anode electrode 4 without eccentricity, so that a switching element having a small anode area can be provided.

Embodiment 5 FIG. 5 is a top view showing a main part of a vacuum microswitching element according to Embodiment 5 of the present invention. In FIG. 5, reference numeral 22 denotes a central shield electrode which is electrically connected and mounted on the cathode electrode substrate 1.

When the outer diameter of the cathode electrode substrate 1 is considerably larger than the electrode distance between the anode electrode 4 and the cathode electrode 2 (D> 3d), the outer diameter of the cathode electrode group composed of a plurality of cathode electrodes 2 is increased. The shielding effect of the disposed insulating shield electrode 24 is reduced, and a discharge occurs at the center of the cathode electrode substrate 1. In order to prevent such a discharge, a central shield electrode 22 is provided at the center of the cathode electrode substrate 1 so that a discharge at the time of off is generated between the insulating shield electrode 24 or the central shield electrode 22 and the cathode by the discharge is generated. Damage to the electrode 2 or the gate electrode 3 can be prevented.

As described above, according to the vacuum microswitching device of the fifth embodiment of the present invention, even if a negative voltage is applied to the anode electrode 4 side, the trajectory of electrons emitted from the cathode electrode 2 Electrons are collected by the anode electrode 4 without eccentricity, so that damage to the cathode electrode 2 or the gate electrode 3 can be suppressed. In this case, a high withstand voltage as a switching element can be achieved even when the distance between the electrodes is considerably larger than that between the electrodes.

Embodiment 6 FIG. FIG. 6 is a diagram schematically showing a configuration of a vacuum micro-switching element according to Embodiment 6 of the present invention. In FIG. 6, the shield electrode 27
Is fixed to the inner wall of a metal vacuum vessel 5 so as to be disposed around a cathode electrode group composed of a plurality of cathode electrodes 2. The shield electrode 27 is electrically connected to the cathode electrode 2 via the metal vacuum vessel 5, and these are kept at the same potential.

After evacuating or vacuum-sealing the vacuum microswitching element, a negative high voltage is applied to the anode electrode 4 to forcibly prevent the projection on the surface of the anode electrode 4, and the shield electrode 27 is forcibly applied. And a spark discharge is generated. With such a configuration, high withstand voltage as a switching element can be achieved. Further, when the switching element is operating in the system and the discharge is generated by applying a high negative voltage to the anode electrode 4 when the space between the cathode electrode 2 and the anode electrode 4 is off, Since only discharge occurs with the shield electrode 27, the discharge does not damage the cathode electrode 2 or the gate electrode 3.

As described above, according to the vacuum microswitching device according to the sixth embodiment of the present invention, even if a negative voltage is applied to the anode electrode 4 side, the cathode electrode 2 or the gate electrode 3 is not damaged. It is possible to suppress the occurrence and to achieve high withstand voltage as a switching element.

Embodiment 7 FIG. 7 is a diagram schematically showing a configuration of a vacuum micro switching device according to Embodiment 7 of the present invention. In FIG. 7, 28 is fixed to the inner wall of the metal vacuum vessel 5 via an insulating spacer 29 as an insulating member so as to be disposed around a cathode electrode group composed of a plurality of cathode electrodes 2. Insulated shield electrode. A voltage is applied to the insulation shield electrode 28 from the insulation shield electrode control circuit 26 via the voltage introduction terminal 7.

The insulating shield electrode 28 is connected to the cathode 2
When the same voltage is applied from the insulating shield electrode control circuit 26, a discharge due to minute projections on the anode electrode 4 is generated between the insulating shield electrode 28 and the cathode electrode 2 or the gate electrode 3 is not damaged by the discharge. Can be prevented. Also, if a negative voltage with respect to the cathode electrode potential is applied to the insulating shield electrode 28 during the operation of the vacuum microswitching element, the electron orbit acts in the direction converging to the center, so that the electrons collected on the anode electrode 4 Region becomes small, and a switching element having a small anode area can be provided.

As described above, according to the vacuum microswitching device according to the seventh embodiment of the present invention, even if a negative voltage is applied to the anode electrode 4 side, the cathode electrode 2 or the gate electrode 3 is not damaged. It is possible to suppress the occurrence and to achieve high withstand voltage as a switching element. Further, since the area of electrons to the anode electrode 4 can be reduced, a switching element having a small anode area can be provided.

[0039]

According to the present invention, there is provided a vacuum microswitching device comprising: a cathode electrode for emitting electrons; a gate electrode for controlling emission of electrons; an anode electrode for collecting emitted electrons; A shield electrode provided around a cathode electrode group composed of an electrode is provided in the vacuum vessel, the shield electrode is held at the same potential as the cathode electrode, and the state between the cathode electrode and the anode electrode is turned off. In this case, a discharge is generated between the anode electrode and the anode electrode, so that the cathode electrode and the gate electrode can be prevented from being damaged by the discharge.

The shield electrode is provided on the cathode electrode substrate on which the cathode electrode is formed so as to surround the cathode electrode group. In some cases, a discharge can be generated between the shield electrode and the anode electrode, and the cathode electrode and the gate electrode can be prevented from being damaged by the discharge.

The above-mentioned shield electrode is constituted by an insulating shield electrode provided on a cathode electrode substrate on which a cathode electrode is formed so as to surround the cathode electrode group and via an insulating member. Therefore, a discharge is generated between the shield electrode and the anode electrode when the cathode electrode and the anode electrode are in the off state, and the cathode electrode and the gate electrode can be prevented from being damaged by the discharge.

Further, the shield electrode is provided so as to surround the cathode electrode group and is supported by the inner wall of the vacuum vessel. Therefore, when the space between the cathode electrode and the anode electrode is off, the shield electrode is shielded. Discharge can be generated between the electrode and the anode electrode, and the cathode electrode and the gate electrode can be prevented from being damaged by the discharge.

Further, the shield electrode is characterized by being constituted by an insulating shield electrode provided so as to surround the cathode electrode group and supported on the inner wall of the vacuum vessel via an insulating member. A discharge is generated between the shield electrode and the anode electrode when the space between the anode electrodes is in an off state, and the cathode electrode and the gate electrode can be prevented from being damaged by the discharge.

The insulating shield electrode is connected to a control power supply that supplies a potential to the shield electrode independently of the cathode electrode, and supplies a potential different from the potential of the cathode electrode to the insulating shield electrode. Therefore, it is possible to work in a direction in which the trajectories of the electrons are converged, and it is possible to provide a switching element having a small anode area.

Further, the control power source is characterized in that when the space between the cathode electrode and the anode electrode is on, the insulating shield electrode is kept at a lower potential than the cathode electrode. In the on state, electrons can be efficiently collected by the anode electrode.

Further, the insulating shield electrode is divided in the circumferential direction, and the control power supply is capable of supplying different voltages to each of the divided insulating shield electrodes, so that the anode electrode is more efficiently used. Electrons can be collected.

Further, a central shield electrode maintained at the same potential as the cathode electrode is further disposed at the center of the cathode electrode group, so that the cathode electrode is disposed between the shield electrode and the central shield electrode. Even when the outer diameter is large, it is possible to prevent the cathode electrode and the gate electrode from being damaged by the discharge when the space between the cathode electrode and the anode electrode is in the off state.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a switching element according to a first embodiment of the present invention.

FIG. 2 is a top view schematically showing a main part of a vacuum cathode electrode switching element according to Embodiment 2 of the present invention.

FIG. 3 is a diagram schematically showing a configuration of a vacuum micro switching element according to Embodiment 3 of the present invention.

FIG. 4 is a top view showing a main part of a vacuum microswitching element according to Embodiment 4 of the present invention.

FIG. 5 is a top view showing a main part of a vacuum microswitching element according to Embodiment 5 of the present invention.

FIG. 6 is a diagram schematically showing a configuration of a vacuum microswitching element according to Embodiment 6 of the present invention.

FIG. 7 is a diagram schematically showing a configuration of a vacuum micro-switching element according to Embodiment 7 of the present invention.

FIG. 8 is a sectional view showing a conventional vacuum microswitching device disclosed in Japanese Patent Application Laid-Open No. 8-87964.

[Explanation of symbols]

1 cathode electrode substrate, 2 cathode electrode, 3 gate electrode, 4 anode electrode, 5 vacuum vessels, 21, 23,
27 shield electrode, 22 central shield electrode, 24,
28 Insulation shield electrode, 25, 29 Insulation spacer (insulation member), 26 Insulation shield electrode control circuit.

Claims (9)

[Claims] A cathode electrode for emitting electrons, a gate electrode for controlling emission of electrons, an anode electrode for collecting emitted electrons, and a cathode electrode group comprising a plurality of the cathode electrodes. A shield electrode provided around the inside of the vacuum vessel, wherein the shield electrode is maintained at the same potential as the cathode electrode, and the anode is turned off when the cathode electrode and the anode electrode are in an off state. A vacuum micro-switching device characterized in that a discharge is generated between the electrode and the electrode. 2. The vacuum microswitching device according to claim 1, wherein the shield electrode is provided on the cathode electrode substrate on which the cathode electrode is formed so as to surround the cathode electrode group. 3. The shield electrode is constituted by an insulating shield electrode provided on a cathode electrode substrate on which the cathode electrode is formed so as to surround the cathode electrode group and via an insulating member. The vacuum microswitching device according to claim 1, wherein 4. The vacuum microswitching device according to claim 1, wherein the shield electrode is provided so as to surround the cathode electrode group, and is supported on an inner wall of the vacuum vessel. 5. The shield electrode according to claim 1, wherein the shield electrode is provided so as to surround the cathode electrode group, and is constituted by an insulating shield electrode supported on an inner wall of the vacuum vessel via an insulating member. 3. The vacuum microswitching device according to item 1. 6. The insulating shield electrode is connected to a control power supply that supplies a potential to the shield electrode independently of the cathode electrode, and supplies a potential different from the potential of the cathode electrode to the insulating shield electrode. The vacuum microswitching device according to claim 3 or 5, wherein 7. The control power supply according to claim 6, wherein when the space between the cathode electrode and the anode electrode is in an on state, the insulating shield electrode is kept at a lower potential than the cathode electrode. Vacuum micro switching device. 8. The insulated shield electrode is divided in the circumferential direction, and the control power supply can supply different voltages to the respective divided insulated shield electrodes. A vacuum microswitching device according to claim 7. 9. A cathode shield according to claim 1, further comprising a central shield electrode maintained at the same potential as said cathode electrode, at a central portion of said cathode electrode group.
The vacuum microswitching device according to any one of the above.