JP2001167723A - X-ray image tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an x-ray image tube wherein the stability of electron orbit is aimed at and a clearer picture is obtained. SOLUTION: In addition to an anode 4 constituting an electronic lens system within a side tube 2 of the x-ray image tube 1, a barrel shape of electrode 11 is disposed in front of a micro channel plate(MCP) 10 so that a stability of electron orbits between the anode and the MCP is aimed at. Since the MCP has a function for multiply increasing photoelectrons, when unstable electron images are formed on the MCP, the disturbance of images is increased several times. The tubular electrode is disposed between the anode and the MCP, an electron incidence surface 10a of the anode and the MCP becomes identical electric potential through the barrel shape of electrode, and as a result, the stability of electron orbit can be realized between the anode and the MCP. Further as a result of disposing the barrel shape electrode, it is expected that an influence of an electric field invading into the tubular electrode on the electron orbit is reduced by the tubular electrode, and a clearer picture can be obtained even from a feeble x-ray.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray image tube for converting X-rays into an optical image.

[0002]

2. Description of the Related Art Conventionally, there is Japanese Patent Publication No. 7-62988 as a technique in such a field. The image intensifier described in this publication has an electron lens inside, and this electron lens forms an image of a photoelectron that has jumped out of a photocathode on a microchannel plate. The photoelectrons incident on the microchannel plate are multiplied and then converted into light on the phosphor screen to form a visualized image. Then, this image is observed as an image on a monitor via a lens.

[0003]

The above-mentioned conventional image intensifier has the following problems. In other words, photoelectrons must be reliably incident on the microchannel plate by the electron lens system, and at the same time, in order to obtain a clear image, the trajectory of the photoelectrons until they reach the microchannel plate is stabilized. Need to be done. However, the document disclosed in this publication merely suggests using a microchannel plate to detect both X-rays and neutrons, and does not mention any measures for stabilizing the electron orbit. Not.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and more particularly, to provide an X-ray image tube capable of stabilizing an electron trajectory to obtain a clearer image. And

[0005]

According to a first aspect of the present invention, there is provided an X-ray image tube fixed to an opening end on one side of a side tube.
A photoelectric conversion unit for converting X-rays into photoelectrons, an anode unit fixed to the other open end of the side tube to form an electron lens system in the side tube, and photoelectrons passing through the electron lens system to light. In an X-ray image tube having an output section for conversion, a microchannel plate is arranged between the anode section and the output section, a cylindrical electrode is arranged between the microchannel plate and the anode section, One end is electrically connected to the anode portion, and the other end of the cylindrical electrode is electrically connected to the electron incident surface of the microchannel plate.

In this X-ray image tube, a cylindrical electrode is arranged in front of a microchannel plate separately from an anode portion for creating an electron lens system in a side tube, and the anode portion and the microchannel plate are arranged by the cylindrical electrode. Stabilization of the electron orbit between the two. This is because, when an unstable electron image is formed on the microchannel plate, the disturbance of the image is multiplied by the electron multiplication function of the microchannel plate. Therefore, when using a microchannel plate, stabilization of the electron orbit is a particularly important factor. Therefore, the cylindrical electrode is positively arranged between the anode part and the microchannel plate, and at the same time, the anode part and the electron incident surface of the microchannel plate are made to have the same potential through this cylindrical electrode. The effect of stabilizing the electron trajectory between the anode part and the microchannel plate and further arranging the cylindrical electrode, as a result of the electric field intruding into the cylindrical electrode from the outside, affecting the electron trajectory, It is expected to be reduced by the shape electrode, and a clear image can be obtained even with weak X-rays.

[0007] In the X-ray image tube according to claim 2,
A first cylindrical electrically insulating member is disposed outside the cylindrical electrode, a first conductive member electrically connected to one end of the cylindrical electrode and extending outward, and electron emission from the microchannel plate. It is preferable that a cylindrical first electrical insulating member is interposed between the second electrically conductive member and the second electrically conductive member which is electrically connected to the surface and extends outward. A first conductive member having a large potential difference and a second conductive member;
The first electrically insulating member can appropriately separate the conductive member from the conductive member, and thus a discharge phenomenon that easily occurs between these members can be reliably prevented.

[0008] In the X-ray image tube according to claim 3,
It is preferable to join the end of the side tube electrically connected to the anode part and the first conductive member extending from the cylindrical electrode.
When such a configuration is adopted, since the end of the side tube and the first conductive member are joined by welding or the like, X
When assembling the line image tube, it is possible to assemble while aligning the microchannel plate with the side tube. In this way, based on the split structure of the side tube with the anode part and the microchannel plate, it is possible to easily assemble the microchannel plate and accurately align the microchannel plate with the side tube. As a result, the quality of the X-ray image tube can be improved.

An X-ray image tube according to claim 4,
A third conductive member electrically connected to the output portion and extending outwardly, and a second conductive member via a cylindrical second electrical insulating member disposed outside the cylindrical electrode. It is preferable to join the fixed flange portion. When such a configuration is adopted, the flange portion on the micro channel plate side and the third conductive member on the output portion side are joined by welding or the like. Therefore, when assembling the X-ray image tube,
The assembly can be performed while aligning the output unit with the microchannel plate. As a result, the assembling accuracy of the X-ray image tube is improved, and the quality is improved.

The X-ray image tube according to claim 5,
It is preferable to arrange the fluorescent screen of the output unit close to the electron emission surface of the microchannel plate. When such a configuration is employed, a large number of photoelectrons that fly out of the electron emission surface of the microchannel plate can be efficiently incident on the output unit, and the effect on the image when converting the photoelectrons into light is reduced. is there.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A preferred embodiment of the line image tube will be described in detail.

FIG. 1 is a sectional view showing an X-ray image tube according to the present invention. The X-ray image tube 1 shown in FIG. 1 has a glass side tube 2 for constituting a vacuum vessel. One side open end A of the side tube 2 has a photoelectric conversion for converting X-rays into photoelectrons. The part 3 is fixed. An input window 3a is provided outside the photoelectric conversion unit 3 in a curved shape with a light metal (for example, aluminum or beryllium) through which soft X-rays and low-energy γ-rays are easily transmitted.
b and the photocathode 3c are provided.

Therefore, when X-rays enter the photoelectric conversion unit 3, the X-rays transmitted through the entrance window 3a are once converted into light by the input fluorescent screen 3b, and then converted into photoelectrons by the photoelectric screen 3c. Therefore, a predetermined amount of photoelectrons is emitted from the photoelectric conversion unit 3 according to the amount of incident X-rays.

The other side open end B of the side tube 2 has a side tube 2
An anode part 4 for creating an electron lens system is fixed inside. At three places between the anode section 4 and the photoelectric conversion section 3, first to third focus electrodes 5, 6, and 7 for fixing to the side tube 2 and maintaining an appropriate electron lens system are provided. Have been. And, in order to construct a reliable electron lens system,
The aperture diameter of each of the focus electrodes 5, 6, and 7 is gradually reduced as approaching the anode section 4, and finally the anode section 4 is formed.
Has the smallest diameter of the opening 4a.

As an example of configuring an appropriate electron lens system in the X-ray image tube 1, when the anode section 4 is set to 0 V, -14.9 kV is applied to the first focus electrode 5 and the second focus electrode 5 is applied. A voltage of -14.2 kV is applied to the focus electrode 6, and a voltage of -2.7 kV is applied to the third focus electrode 7.

A large number of photoelectrons guided by an appropriate electron trajectory by such an electron lens system form an image at the output unit 8. The output unit 8 includes an output face plate 8b having an output fluorescent screen 8a for converting electrons into light,
This output face plate 8b is formed of a fiber optical plate (commonly called FOP).

Here, the X-ray image tube 1 has a weak X-ray image.
In order to be able to detect even lines, the anode section 4 and the output section 8
The microchannel plate 10 having an electron multiplying function is provided between the two. The microchannel plate 10 is arranged at an electron imaging position of the electron lens system so as to be arranged close to the output fluorescent screen 8 a and to be separated from the anode section 4. Further, as means for stabilizing the electron orbit, the microchannel plate 10
A cylindrical tubular electrode 11 made of stainless steel is disposed between the anode and the anode section 4, and the tubular electrode 11 is arranged so as to stand on the edge of the electron incident surface 10 a of the microchannel plate 10. Fixed.

Therefore, the lower end of the cylindrical electrode 11 is electrically connected to the electron incident surface 10a of the micro channel plate 10, so that appropriate conductivity is secured.
A flange-shaped first conductive member 12 extending outward is fixed to the upper end of the cylindrical electrode 11.
Is electrically connected to a flange-shaped metal end 2 a provided on the side tube 2 via a lead portion 13.

The end 2a of the side tube 2 and the first conductive member 12 are joined by welding or the like.
When assembling the line image tube 1, it is possible to assemble the micro channel plate 10 while aligning the micro channel plate 10 with the anode portion 4 of the side tube 2. As described above, based on the divided structure of the side tube 2 having the anode part 4 and the microchannel plate 10, the assembling of the microchannel plate 10 is facilitated, and at the same time, the microchannel plate 10 is accurately attached to the side tube 2. Positioning can be performed, which contributes to quality improvement of the X-ray image tube 1.

When the end portion 2a of the side tube 2 and the first conductive member 12 are welded based on such an assembling operation, the anode 4 and the microchannel plate 10 are electrically connected to each other with the cylindrical electrode 11 interposed therebetween. The same potential as that of the incident surface 10a can be obtained. Further, by extending the upper end of the cylindrical electrode 11 to the vicinity of the anode 4, an appropriate electron trajectory is secured in the cylindrical electrode 11 between the anode 4 and the microchannel plate 10.

As described above, apart from the focus electrodes 5, 6, 7 and the anode 4 for creating an appropriate electron lens system in the side tube 2, in front of the microchannel plate 10,
A concentrically arranged cylindrical electrode 11 is provided.
The anode part 4 and the microchannel plate 10
Stabilization of the electron orbit is achieved. On the other hand, if the electron trajectory cannot be stabilized in front of the microchannel plate 10, an unstable electron image is formed on the microchannel plate 10, and the microchannel plate 10 having the electron multiplying function is used. This is because the disturbance of the image is increased many times.

Therefore, when using a microchannel plate having an electron multiplying function, stabilization of the electron orbit is an important factor. Therefore, the cylindrical electrode 11 is positively arranged between the anode part 4 and the microchannel plate 10, and the anode part 4 and the electron incident surface 10 a of the microchannel plate 10 are made the same through the cylindrical electrode 11. When the potential is set to a potential, the electron orbit is stabilized between the anode part 4 and the microchannel plate 10, and at the same time, the influence of the electric field that enters the cylindrical electrode 11 from the outside on the electron orbit is reduced. The reduction is expected by the cylindrical electrode 11, and a clear image can be obtained even with a weak X-ray.

An outwardly extending flange-shaped second conductive member 14 is fixed to the electron emission surface 10 b of the microchannel plate 10. The conductive member 14 is connected to the electron emission surface of the microchannel plate 10. 10b is electrically connected, and appropriate conductivity is ensured. Then, with the first conductive member 12 set to 0 V, a voltage of 0.9 to 1.2 kV is applied to the electron incident surface 10 b via the second conductive member 14.

Therefore, a first electric insulating member 15 is disposed between the first conductive member 12 and the second conductive member 14,
The first electrical insulating member 15 is formed as a glass or ceramic cylindrical body surrounding the outside of the cylindrical electrode 11. As a result of adopting such a configuration, the member 1
A discharge phenomenon that easily occurs between the second member and the member is appropriately prevented.

An outwardly extending flange-shaped third conductive member 16 is fixed to the output face plate 8b of the output portion 8 disposed close to the microchannel plate 10. The conductive member 16 is connected to the output face plate 8b. It is electrically connected, and appropriate conductivity is secured. Then, with the first conductive member 12 set to 0 V, the output unit 8
A voltage of 5 to 6 kV is applied via the third conductive member 16.

On the other hand, a metal flange 18 is fixed to the second conductive member 14 via a cylindrical second electric insulating member 17 made of glass or ceramics. The second electric insulating member 17 is aligned with the first electric insulating member 15 so as to surround the cylindrical electrode 11.
Since the flange portion 18 is joined to the third conductive member 16 by welding or the like, when assembling the X-ray image tube 1, the micro channel plate 1
0 can be assembled while the output unit 8 is positioned. As a result, the assembling accuracy of the X-ray image tube 1 is improved, and the quality of the X-ray image tube is improved.

[0027]

As described above, the X-ray image tube according to the present invention has the following effects. That is, a photoelectric conversion unit that is fixed to an opening end on one side of the side tube and converts X-rays into photoelectrons, and is fixed to another opening end on the other side of the side tube to form an electron lens system in the side tube. An X-ray image tube having an anode part and an output part for converting photoelectrons that have passed through the electron lens system into light, wherein a microchannel plate is arranged between the anode part and the output part, and the microchannel plate and the anode part And a cylindrical electrode is arranged between them, one end of the cylindrical electrode is electrically connected to the anode part,
By electrically connecting the other end of the cylindrical electrode to the electron incidence surface of the microchannel plate, the electron trajectory is stabilized, and the effect of the electric field entering the cylindrical electrode from the outside on the electron trajectory Is expected to be reduced by the cylindrical electrode, and a clearer image can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an X-ray image tube according to the present invention.

[Explanation of symbols]

1 ... X-ray image tube, 2 ... side tube, 2a ... end of side tube, 3
... photoelectric conversion part, 4 ... anode part, 8 ... output part, 8a ... output fluorescent screen (fluorescent screen), 10 ... microchannel plate,
10a: electron incidence surface, 10b: electron emission surface, 11: cylindrical electrode, 12: first conductive member, 14: second conductive member,
15: first electrically insulating member, 16: third conductive member, 1
7: second electrical insulating member, 18: flange portion, A, B ...
Open end.

Claims (5)

[Claims] 1. A photoelectric conversion unit fixed to one opening end of a side tube to convert X-rays into photoelectrons, and an electron lens fixed to another opening end of the side tube in the side tube. In an X-ray image tube having an anode part for constituting a system and an output part for converting photoelectrons passing through the electron lens system to light, a microchannel plate is arranged between the anode part and the output part. And disposing a cylindrical electrode between the microchannel plate and the anode part, electrically connecting one end of the cylindrical electrode to the anode part, and connecting the other end of the cylindrical electrode to the microchannel plate. An X-ray image tube electrically connected to an electron incidence surface. 2. A first electrically insulating member having a cylindrical shape disposed outside the cylindrical electrode, and electrically connected to the one end of the cylindrical electrode to extend outward. And a second electrically conductive member that is electrically connected to the electron emission surface of the microchannel plate and extends outward, and the first electrically insulating member having a cylindrical shape is interposed therebetween. The X-ray image tube according to claim 1, wherein 3. The end portion of the side tube to which the anode portion is electrically connected, and the first conductive member extending from the cylindrical electrode is joined. 2. The X-ray image tube according to 2. 4. A third electrically conductive member which is electrically connected to the output portion and extends outwardly, and a second electrically insulating tubular member arranged outside the tubular electrode. The X-ray image tube according to any one of claims 1 to 3, wherein a flange portion fixed to the second conductive member is joined. 5. The X according to claim 1, wherein a fluorescent screen of the output unit is arranged close to the electron emission surface of the microchannel plate.
Line image tube.