WO2013061815A1

WO2013061815A1 - Electron tube

Info

Publication number: WO2013061815A1
Application number: PCT/JP2012/076620
Authority: WO
Inventors: 哲哉齋藤; 寛仁西澤; 水野　到
Original assignee: 浜松ホトニクス株式会社
Priority date: 2011-10-25
Filing date: 2012-10-15
Publication date: 2013-05-02
Also published as: JP2013093172A; JP5864210B2

Abstract

An image intensifier (1) of the present invention is provided with a side tube (2) that constitutes a vacuum container, and the inner surface of the side tube (2) includes inner surfaces on ceramic rings (15A, 15B, 15C, 15D) and inner surfaces on electrodes (9A, 9B, 9C, 9E, 9F), and is formed of an inorganic insulating film (16a). With such configuration, electron emission from the electrode (9A, 9B, 9C, 9E, 9F) portions on the inner surface of the side tube (2) and from boundary surfaces between the electrodes (9A, 9B, 9C, 9E, 9F) and the ceramic rings (15A, 15B, 15C, 15D) is reduced, and output characteristics are excellently maintained. As a result, withstand voltage characteristics of the image intensifier (1) can be sufficiently improved.

Description

Electron tube

The present invention relates to an electron tube having an electrode.

Conventionally, in an electron tube such as an image intensifier, deterioration of withstand voltage characteristics has been a problem. The deterioration of the withstand voltage characteristic may cause a local discharge phenomenon, and such a local discharge causes the output characteristic of the electron tube to deteriorate. In order to prevent such a discharge phenomenon, an image intensifier tube in which a part of the envelope portion is covered with a transparent resistance layer such as oxidized transparent chromium is known (see

Patent Documents

1 and 2 below).

Japanese National Patent Publication No. 2-227946 US Pat. No. 5,059,854

However, in the conventional image intensifier tube described above, the withstand voltage characteristics tend not to be sufficiently improved depending on the voltage applied to the electrodes.

Therefore, the present invention has been made in view of such a problem, and an object thereof is to provide an electron tube capable of sufficiently improving withstand voltage characteristics.

In order to solve the above problems, an electron tube according to one aspect of the present invention is an electron tube including a cylindrical container configured to include a side wall including a ceramic member and / or a glass member and an electrode. The inorganic insulating film is formed including the surface on the side wall and the surface on the electrode. The “cylindrical container” referred to here includes a container having a thin shape with a large width in a direction perpendicular to the central axis, in addition to a container elongated in the central axis direction including the cylindrical member.

According to such an electron tube, electron emission from the electrode portion on the inner surface of the cylindrical container and the boundary surface between the electrode and the side wall is reduced, and the output characteristics are maintained favorably. As a result, the withstand voltage characteristics of the electron tube can be sufficiently improved.

According to the present invention, an electron tube capable of sufficiently improving the withstand voltage characteristic can be provided.

It is a partial sectional view showing an internal configuration of an image intensifier which is an electron tube according to a preferred embodiment of the present invention. It is sectional drawing of the side pipe | tube of FIG.

Hereinafter, preferred embodiments of an electron tube according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is a partial cross-sectional view showing an internal configuration of an image intensifier which is an electron tube according to a preferred embodiment of the present invention, and FIG. 2 is a cross-sectional view of the side tube of FIG. This image intensifier 1 is a proximity type image intensifier tube in which a photocathode, an MCP (microchannel plate: electron multiplier), and a phosphor screen are arranged close to each other inside a vacuum vessel including a ceramic side tube. is there.

As shown in FIG. 1, the inside of the image intensifier 1 has both the opening ends of a substantially hollow cylindrical side tube 2 whose both ends are open at a substantially disc-shaped entrance window 3 and a substantially disc-shaped exit. A high vacuum is maintained by hermetically sealing with the window 4. That is, a vacuum vessel is constituted by the side tube (hollow tube, tube) 2, the entrance window 3, and the exit window 4.

A photocathode 5 is formed in the central area of the vacuum side surface of the entrance window 3. The incident window 3 and the photocathode 5 constitute a photocathode 6. A fluorescent screen 7 is formed in the central region of the vacuum side surface of the exit window 4. Further, a disc-shaped MCP 8 is disposed between the photocathode 5 and the phosphor screen 7 so as to face the photocathode 5 and the phosphor screen 7 and hold a predetermined gap.

The MCP 8 is held in the side tube 2 by being sandwiched by two substantially ring-shaped electrodes made of Kovar

metal

9B, 9C constituting a part of the side tube 2. Specifically, the MCP 8 has a surface on the photocathode 5 side pressed by an electrode 9B via a conductive spacer 10 and a conductive spring 11, and a surface on the phosphor screen 7 side is an electrode via a conductive spacer 12. It is held in the side tube 2 by being pressed down by 9C.

A metal conductive film (not shown) is formed in a state of electrical contact with the photocathode 5 in the peripheral region on the vacuum side surface of the entrance window 3. This conductive film is a substantially ring-shaped Kovar metal member for joining the side tube 2 and the incident window 3, and includes an electrode 9 A constituting a part of the side tube 2 and an indium 13 serving as a joining member. Are in electrical contact.

A metal conductive film (not shown) is formed in electrical contact with the phosphor screen 7 in the peripheral region on the vacuum side surface of the exit window 4. This conductive film is in electrical contact with an electrode 9D, which is a substantially ring-shaped Kovar metal member for joining the side tube 2 and the exit window 4. The electrode 9D is fitted inside an electrode 9E that is a substantially cylindrical Kovar metal member, and the electrode 9D and the electrode 9E are in electrical contact with each other. Further, the electrode 9D and the emission window 4 are sealed with a frit glass 14. These

electrodes

9D and 9E also constitute part of the side tube 2.

An external power source is connected to the

electrodes

9A, 9B, 9C, 9D, and 9E constituting the side tube 2 via lead wires (not shown). Then, a necessary voltage is applied to the photocathode 5, the photocathode side surface and the phosphor screen side surface (electron incident side surface and electron emission side surface) of the MCP 8, and the phosphor screen 7 by an external power source. For example, a potential difference of about 200 V is set between the photocathode 5 and the photocathode side surface of the MCP 8, and a potential difference of about 500 V to about 900 V is established between the photocathode side surface and the phosphor screen side surface of the MCP 8. Is set to be variable, and a potential difference of about 6 kV to about 7 kV is set between the fluorescent screen side surface of the MCP 8 and the fluorescent screen 7.

Further, the side tube 2 is provided with an electrode 9F which is a substantially ring-shaped Kovar metal member, and the inner tip is held so as to be spaced from the side surface of the exit window 4 by a predetermined distance. The electrode 9F is a getter energization electrode (not shown).

The incident window 3 is a glass face plate formed by processing synthetic quartz in a flat shape in the central region of each surface on the atmosphere side and the vacuum side. The exit window 4 is a fiber plate configured by converging a large number of optical fibers into a plate shape. The phosphor screen 7 formed on the exit window 4 is formed by applying a phosphor to the vacuum side surface of the exit window 4.

Turning to FIG. 2, the structure of the side tube 2 will be described in detail. The side tube 2 includes the electrode 9A and the electrode 9B, the electrode 9B and the electrode 9C, the electrode 9C and the electrode 9F, and The

electrodes

9F and 9E have a multi-stage structure in which the ceramic rings (side walls) 15A, 15B, 15C, and 15D, which are ring-shaped ceramic members, are joined to each other. That is, the side tube 2 is configured by combining a ceramic member and a metal electrode. All of the inner surface exposed to the vacuum side of such side tube 2,

electrodes

9A, 9B, 9C, 9E, the inner surface of 9F, and

ceramic rings

15A, 15B, 15C, contains the inner surface of 15D, alumina (Al ₂ It is formed with an inorganic insulating film 16a such as O ₃ ). Further, all the outer surfaces exposed to the atmosphere side of the side tube 2 include the outer surfaces of the

electrodes

9A, 9B, 9C, 9E, 9F and the outer surfaces of the

ceramic rings

15A, 15B, 15C, 15D, and alumina (Al ₂ O ₃ ) or the like. In addition, an inorganic insulating film 16a is formed on the inner surface of the electrode 9A from the top of the indium 13 in a state where indium 13 which is a bonding member for bonding the incident window 3 is accumulated. In order to reliably join the incident window 3 and the side tube 2, the inorganic insulating film 16a on the indium 13 is removed. The thickness of these

inorganic insulating films

16a and 16b is, for example, 20 to 100 mm.

Next, a method for manufacturing the image intensifier 1 will be described. The side rings 2 are assembled by joining the

ceramic rings

15A, 15B, 15C, 15D and the

electrodes

9A, 9B, 9C, 9E, 9F.

Next, indium 13 is diffused and accumulated on the step on the inner surface of the electrode 9A of the side tube 2. In this state,

inorganic insulating films

16a and 16b are formed on the inner surface and the outer surface of the side tube 2 by subjecting the side tube 2 to film formation by atomic layer deposition using an ALD (Atomic Layer Deposition) apparatus. Then, after incorporating the MCP 8 using the

conductive spacers

10 and 12 and the spring 11 inside the side tube 2, the emission window 4 on which the phosphor screen 7 is formed is joined to one end side of the side tube 2. Further, each member in the side tube 2 is connected to the lead wire. Thereafter, after removing the inorganic insulating film 16a on the indium 13, the side tube 2 is sealed by the incident window 3 in which the activated photocathode 5 is formed. Next, the image intensifier 1 including the side tube 2, the entrance window 3, and the exit window 4 is potted so that the outside is surrounded by a resin material and hardened.

The operation of the image intensifier 1 of this embodiment will be described. When a predetermined voltage is applied to the photocathode 5, MCP8, and phosphor screen 7 from an external power source, the gap between the photocathode 5 and MCP8 and the channel between the electron incident side surface and the electron emission side surface of MCP8 Electric fields in the direction from the fluorescent screen 7 toward the photocathode 5 are respectively generated inside the tube and in the gap between the MCP 8 and the fluorescent screen 7. The inorganic

insulating films

16a and 16b are formed on the surfaces of the

electrodes

9A, 9B, 9C, and 9E. Since the inorganic insulating

films

16a and 16b are very thin, each of the inorganic insulating

films

16a and 16b passes through the inorganic insulating

films

16a and 16b. It is possible to apply a voltage to the electrodes, the photocathode 5, the MCP 8, and the phosphor screen 7. At this time, when weak incident light as an optical image is transmitted from the outside through the incident window 3 and is incident on the photocathode 5, the incident light is converted into photoelectrons by the photocathode 5 and emitted into vacuum. The photoelectrons emitted from the photocathode 5 in this way are accelerated by the electric field generated in the gap between the photocathode 5 and the MCP 8 and enter the electron incident side surface of the MCP 8.

Then, the photoelectrons incident on the MCP 8 are accelerated by the electric field generated inside the channel tube of the MCP 8, and are multiplied to secondary electrons by repeatedly colliding with the wall surface of the channel tube. As a result, the multiplied secondary electrons are emitted from the electron emission side surface of the MCP 8 while retaining the two-dimensional position information of the incident light. Secondary electrons emitted from the MCP 8 are accelerated by an electric field generated in the gap between the MCP 8 and the phosphor screen 7 and then enter the phosphor screen 7. On the fluorescent screen 7, fluorescence is emitted according to the incident secondary electrons, and this fluorescence passes through the emission window 4 and is emitted to the outside. Such emitted light becomes an optical image holding the two-dimensional position information of the incident light.

According to the image intensifier 1 described above, the

electrodes

9A, 9B, 9C, 9E, 9F on the inner surface of the side tube 2 constituting the vacuum vessel, the

electrodes

9A, 9B, 9C, 9E, 9F, and the ceramic ring 15A. , 15B, 15C, 15D, the electron emission from the interface is reduced, and the output characteristics are maintained well. In particular, by covering the entire inner surface of the side tube 2 with an inorganic insulating film, electron emission from the inner surface of the side tube 2 can be effectively reduced. As a result, the withstand voltage characteristic of the image intensifier 1 can be sufficiently improved. Furthermore, the withstand voltage characteristic of the image intensifier 1 can be further improved by covering the entire outer surface of the side tube 2 with an inorganic insulating film. For example, there is no possibility of a short circuit due to moisture after the potting process, reliability is improved, and output characteristics can be stabilized even in an environment of high temperature and high humidity.

For example, for the image intensifier 1 including the side tube 2 having a side tube diameter of about 31 mm (photocathode effective diameter of 18 mm), inorganic insulating

films

16a and 16b having a thickness of 20 mm, 50 mm, and 100 mm are formed, and the electrode 9C When a voltage of 18 kV was applied between the electrodes 9D and a voltage was applied between the MCP 8 and the phosphor screen 7, no discharge was observed. On the other hand, when the inorganic insulating

films

16a and 16b were not formed, discharge was confirmed when a voltage of 10.5 kV was applied between the

electrodes

9C and 9D. Similarly, for the image intensifier 1 including the side tube 2 having a side tube diameter of about 43 mm (photocathode effective diameter 25 mm), inorganic insulating

films

16a and 16b having a thickness of 20 mm, 50 mm, and 100 mm are formed, and an electrode 9C is formed. When a voltage of 18 kV was applied between the electrode 9D and a voltage was applied between the MCP 8 and the phosphor screen 7, no discharge was observed. On the other hand, when the inorganic insulating

films

16a and 16b were not formed, discharge was confirmed when a voltage of 11 kV was applied between the

electrodes

9C and 9D. From this result, it was found that the image intensifier 1 can apply a higher voltage, and is advantageous for achieving high resolution and high gain while reducing the size of the apparatus.

In the above-described embodiment, the MCP 8 is incorporated using the

conductive spacers

10 and 12 and the spring 11 after the inorganic insulating

films

16a and 16b are formed. However, the

conductive spacers

10 and 12 and the spring 11 are connected to the side tube. The inorganic insulating film may be formed while being fixed inside, or the MCP 8 may be incorporated using the

conductive spacers

10 and 12 and the spring 11 on which the inorganic insulating film is formed. By doing in this way, the effect of preventing discharge is further improved.

Note that the present invention is not limited to the embodiment described above. For example, the subject of the present invention is not limited to an image intensifier, and other electron tubes may be used. For example, a device including an electron tube or a vacuum tube such as a photomultiplier tube, an electron multiplier tube, an X-ray image intensifier, an X-ray tube, and various light source devices may be used.

Further, as the inorganic insulating film formed on the side tube 2 of the present embodiment, a nitride film such as Si ₃ N ₄ may be used in addition to the oxide film such as alumina. Further, the method for forming the inorganic insulating film is not limited to the gas phase ALD method, and a film forming method such as a liquid phase MOD (Metal Organic Deposition) method may be used. Good. However, the ALD method is more preferable because an inorganic insulating film having a more uniform film thickness and no pinholes can be formed. The ALD method is also preferable because the manufacturing process can be made more efficient.

In addition, the vacuum container of the present embodiment is not limited to the case where the shape of both end faces, that is, the both open ends of the side tube 2, the shape of the entrance window 3, and the exit window 4 are circular, and there are many shapes such as a square. It may be square.

Moreover, although the side tube 2 of the present embodiment is configured by combining a ceramic member and a metal electrode, a glass member may be used as a side wall instead of the ceramic member. Or you may comprise a side wall combining both a ceramic member and a glass member with respect to a metal electrode.

Here, in this embodiment, the outer surface of the cylindrical container may be formed of an inorganic insulating film including the surface on the side wall and the surface on the electrode. In this way, the withstand voltage characteristic of the outer surface of the electron tube can be improved, and for example, the characteristic can be stabilized even in an environment of high temperature and high humidity.

The electron tube also has a photocathode that converts incident light into photoelectrons, an electron multiplier that multiplies photoelectrons emitted from the photocathode, and a fluorescence that emits fluorescence upon receiving electrons multiplied by the electron multiplier. And an image intensifier. In the image intensifier, the electron emission in the container tends to affect the output, but the output characteristics can be sufficiently stabilized by forming the inner surface of the cylindrical container with an inorganic insulating film.

The present invention uses an electron tube having electrodes, and can sufficiently improve withstand voltage characteristics.

DESCRIPTION OF SYMBOLS 1 ... Image intensifier, 2 ... Side tube, 3 ... Incident window, 4 ... Outgoing window, 5 ... Photocathode, 6 ... Photocathode, 7 ... Phosphor screen, 8 ... MCP (electron multiplication part), 9A, 9B , 9C, 9D, 9E, 9F ... electrodes, 15A, 15B, 15C, 15D ... ceramic rings (ceramic members, side walls), 16a, 16b ... inorganic insulating films.

Claims

In an electron tube including a cylindrical container configured to include a side wall and an electrode including a ceramic member and / or a glass member,
The inner surface of the cylindrical container is formed of an inorganic insulating film including the surface on the side wall and the surface on the electrode.
An electron tube characterized by that.
The outer surface of the cylindrical container is also formed of an inorganic insulating film including the surface on the side wall and the surface on the electrode.
The electron tube according to claim 1, wherein:
The electron tube is
A photocathode for converting incident light into photoelectrons;
An electron multiplier for multiplying photoelectrons emitted from the photocathode;
A fluorescent screen that emits fluorescence in response to electrons multiplied by the electron multiplier;
An image intensifier with
The electron tube according to claim 1 or 2, wherein