WO2007135812A1

WO2007135812A1 - X-ray tube

Info

Publication number: WO2007135812A1
Application number: PCT/JP2007/057571
Authority: WO
Inventors: Tomoyuki Okada; Toru Fujita; Tooru Yamamoto; Tatsuya Nakamura
Original assignee: Hamamatsu Photonics K.K.
Priority date: 2006-05-18
Filing date: 2007-04-04
Publication date: 2007-11-29
Also published as: JP2007311195A; TW200746214A

Abstract

An X-ray tube for irradiating X-rays, especially, an X-ray tube having a structure suitable for irradiating X-rays over a wide range. An X-ray tube (1) comprises a vacuum enclosure (5), an electron source including metal wires (7a, 7b, 7c) having carbon based electron emission materials (6a, 6b, 6c) and arranged in the vacuum enclosure (5) by being held, at the opposite ends thereof, by the vacuum enclosure (5), a target material (15) provided in the vacuum enclosure (5) opposite to the electron source for generating X-rays in response to incidence of electrons from the electron source, a through hole (13) for taking out the X-rays generated from the target material (15) to the outside and a silicon thin film (14) fixed to the vacuum enclosure (5), and an extraction electrode (11) provided between the electron source and the target material (15) on the inner surface (3a) of the vacuum enclosure (5).

Description

Specification

X-ray tube

Technical field

The present invention relates to an X-ray tube that irradiates X-rays, and particularly relates to an X-ray tube having a structure suitable for irradiating X-rays over a wide range.

Background art

An X-ray tube is a device that generates X-rays by generating electrons using an electron source in a high-vacuum tube and causing the electrons to enter a target. An example of such an X-ray tube is an X-ray apparatus disclosed in Patent Document 1 below. In this X-ray apparatus, the electron beam emitted by the planar cathode force collides with the planar anode as a target, and X-rays generated from the planar anode are extracted outside through the extraction window.

Patent Document 1: Japanese Patent Laid-Open No. 2003-288853

Disclosure of the invention

Problems to be solved by the invention

Meanwhile, the X-ray tube having the above-described planar electron source is advantageous for downsizing, while an X-ray tube that can irradiate a wider range is desired. For example, in a situation where X-rays are irradiated to an object that moves relative to the tube, X-rays are irradiated over a wide area so as to extend in the direction intersecting the moving direction (for example, the vertical direction). A possible X-ray tube is preferable, and it is conceivable to use a linear member as an electron source used in such an X-ray tube. In addition, a linear member as an electron source of a cold cathode having an electron emitting material provided on the surface in this way is controlled by an electric field formed mainly with the extraction electrode. The positioning of the member in the vacuum tube is important. In order to realize a wider range of irradiation using such a linear member, since the linear member is arranged over a wide range, its positioning is not easy, so control of electron emission is possible. Tend to be difficult.

[0004] Therefore, the present invention has been made in view of the problems to be solved, and X-ray irradiation characteristics can be stabilized over a wide range by reliably positioning the electron source. The purpose is to provide a tube. Means for solving the problem

[0005] In order to solve the above problems, an X-ray tube of the present invention includes a vacuum envelope including an insulating member at least in part, and a linear member having a carbon-based electron emission material on its surface, Both ends of the member are held by the vacuum envelope so that the electron source disposed in the vacuum envelope and the electron source in the vacuum envelope are opposed to the electron source. Depending on the target, an X-ray extraction window for taking out X-rays generated from the target and attached to the vacuum envelope, and an inner surface of the insulating member of the vacuum envelope. And an extraction electrode provided between the electron source and the target.

[0006] According to such an X-ray tube, the linear members constituting the electron source are held by the vacuum envelope having sufficient strength to hold the vacuum at both ends thereof. In addition to being positioned in the envelope, an extraction electrode is provided between the electron source and the target on the inner surface of the insulating member of the vacuum envelope. In such a configuration, the carbon-based electron emission material force on the surface of the linear member generates X-rays when the emitted electrons enter the target, and these X-rays are extracted through the X-ray extraction window. Stable X-ray irradiation characteristics can be obtained over a wide range by stabilizing the positional relationship between the shape member and the extraction electrode.

[0007] Preferably, the insulating member is provided with an opening so as to face the target, and the X-ray extraction window is provided so as to cover the opening. In this case, when a so-called reflective target that extracts X-rays in a direction different from the incident direction of electrons is used, X-rays can be irradiated over a wide area outside.

[0008] Further, a groove portion corresponding to the linear member is formed on the inner surface of the flat insulating member, the linear member is disposed in a space surrounded by the groove portion, and the extraction electrode is formed of the insulating member. It is also preferable that it is laid along the inner surface across the groove. In this way, positioning with respect to the extraction electrode is facilitated over the entire linear members constituting the electron source, and electron emission from the electron source is made more uniform.

Furthermore, a groove corresponding to the linear member is formed on the inner surface of the flat insulating member, the linear member is disposed in a space surrounded by the groove, and the extraction electrode is insulated. Formed so that the central axis side perpendicular to the inner surface of the target is lower across the groove of the member. It is also preferable that it is laid along the inner surface. Such a configuration facilitates positioning with respect to the extraction electrode over the entire linear members constituting the electron source, makes electron emission from the electron source more uniform, and efficiently distributes electrons to the target. It is possible to make it incident on.

[0010] Furthermore, it is also preferable that both ends of the linear member are held by insulating members of the vacuum envelope. By doing so, it is possible to prevent insulation failure in the linear member.

[0011] Furthermore, the extraction electrode is preferably divided into a plurality of portions along the longitudinal direction of the linear member. If a powerful extraction electrode is provided, the electron extraction amount can be controlled for each divided region along the longitudinal direction of the linear member, and any X-ray can be generated within the divided region along the longitudinal direction of the linear member. Irradiation characteristics can be obtained.

The invention's effect

[0012] According to the X-ray tube of the present invention, the X-ray irradiation characteristics can be stabilized over a wide range by reliably positioning the electron source.

Brief Description of Drawings

FIG. 1 is a plan view of an X-ray tube according to a first embodiment of the present invention.

2 is a plan view showing a state where an upper face plate of the X-ray tube of FIG. 1 is removed.

3 is a cross-sectional view of the X-ray tube of FIG. 1 taken along line III-III.

4 is a cross-sectional view of the X-ray tube of FIG. 1 taken along line IV-IV.

FIG. 5 is a plan view showing a state in which an upper face plate of an X-ray tube according to a second embodiment of the present invention is removed.

FIG. 6 is a cross-sectional view taken along line VI-VI in the state including the upper face plate of the X-ray tube of FIG.

FIG. 7 is a plan view showing a state where an upper face plate of an X-ray tube according to a third embodiment of the present invention is removed.

8 is a cross-sectional view taken along line VIII-VIII in a state including the upper face plate of the X-ray tube in FIG.

FIG. 9 is a cross-sectional view taken along the line IX—IX in the state including the upper face plate of the X-ray tube of FIG. The

[10] FIG. 10 is a plan view of an X-ray tube according to a fourth embodiment of the present invention.

FIG. 11 is a plan view showing a state where the upper face plate of the X-ray tube of FIG. 10 is removed.

12 is a cross-sectional view of the X-ray tube of FIG. 10 taken along line XII-XII.

FIG. 13 is a cross-sectional view of the X-ray tube of FIG. 10 taken along line XIII-XIII.

FIG. 14] A plan view showing a state in which the upper face plate of the X-ray tube according to the fifth embodiment of the present invention is removed.

FIG. 15 is a sectional view taken along line XV—XV in a state including the upper face plate of the X-ray tube of FIG.

FIG. 16 is a cross-sectional view taken along line XVI--XVI in a state including the upper face plate of the X-ray tube of FIG.

[17] FIG. 17 is a plan view showing a state in which an upper face plate of an X-ray tube as a modification of the present invention is removed.

[18] FIG. 18 is a plan view showing a state in which an upper face plate of an X-ray tube as a modification of the present invention is removed.

[19] FIG. 19 is a plan view showing a state in which an upper face plate of an X-ray tube which is a modification of the present invention is removed.

FIG. 20 is a plan view showing a state where an upper face plate of an X-ray tube as a modification of the present invention is removed.

21] FIG. 21 is a plan view showing a state in which an upper face plate of an X-ray tube which is a modification of the present invention is removed.

FIG. 22 is a cross-sectional view of the X-ray tube of FIG. 21 taken along line XXII-XXII.

圆 23] (a) is a plan view showing the main part of an X-ray tube which is a modification of the present invention, and (b) is a cross-sectional view along the axial direction of the electron source of the X-ray tube of (a). is there.

圆 24] (a) is a plan view showing the main part of an X-ray tube which is a modification of the present invention, and (b) is a cross-sectional view along the axial direction of the electron source of the X-ray tube of (a). is there.

25] A sectional view of an X-ray tube which is a modification of the present invention.

Explanation of symbols [0014] 1, 21, 41, 61, 81, 101, 121, 141, 161, 181 ··· Wire tube, 2 ··· Upper face plate, 3 ··· Lower face plate, 3a… Inner surface, 4… Side wall, 5 ... Vacuum envelope, 6a, 6b, 6c ... Carbon-based electron emission material, 7a, 7b, 7c ... Metal wire (linear member), 8a, 8b, 8c ... Electron source, 10a, 10b, 10c, 50a, 50b, 50c, 70a, 70b, 190a, 190b, 190c ... groove, 11, 31, 51, 71, 91, 111, 1 31, 151, 171 · · · Extraction electrode, 13 · · Through hole, 15 , 75 ··· Target material, 56, 76 ··· Projection (inner surface), 73… Through hole (opening).

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of an X-ray 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 will be denoted by the same reference numerals, and redundant description will be omitted. Each drawing is made for the purpose of explanation, and is drawn so as to particularly emphasize the target part of the explanation. Therefore, the dimensional ratio of each member in the drawing does not necessarily match the actual one.

[0016] [First embodiment]

FIG. 1 is a plan view of the X-ray tube 1 according to the first embodiment of the present invention, FIG. 2 is a plan view showing a state in which the upper face plate of the X-ray tube 1 of FIG. 1 is removed, and FIG. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 1. As shown in these figures, the X-ray tube 1 is composed of an upper face plate 2 and a lower face plate 3 which are insulating member forces such as flat glass, and a square columnar side wall 4 which is also an insulating member such as glass. The vacuum envelope 5 is provided. The upper face plate 2, the lower face plate 3, and the side wall 4 are made of glass, and the upper face plate 2 and the lower face plate 3 are sealed with the opening end of the side wall 4 by frit glass or the like, thereby allowing the inside of the vacuum envelope 5 to be sealed. The part is kept airtight.

[0017] On the inner surface 3a of the lower face plate 3 constituting a part of the vacuum envelope 5, carbon-based electron emission materials 6a, 6b, 6c are formed on the peripheral surface by a CVD method, a spray method, a printing method, or the like. Electron sources 8a, 8b, and 8c each composed of a coated metal wire (linear member) 7a, 7b, and 7c are arranged. Here, the carbon-based electron emission materials 6a, 6b, and 6c are represented by carbon nanotubes, carbon nanotubes, carbon nanofibers, diamond, diamond-like carbon, and the like, and have a property of emitting electrons to the outside by the action of an electric field. It is a field emission type electron emission material. In each electron source 8a, 8b, 8c, metal wires 7a, 7 Carbon-based electron emission materials 6a, 6b, and 6c are coated over the entire peripheral surface excluding both ends of b and 7c. Hereinafter, the inner surface 3a refers to a surface facing the vacuum side of the lower face plate 3 and including a joint portion with the side wall 4.

[0018] In the electron sources 8a, 8b, and 8c having the above-described configuration, both ends of the metal wires 7a, 7b, and 7c had a constant tension on the entire metal wires 7a, 7b, and 7c, respectively. By being fitted in the grooves 9a, 9b, 9c of the inner surface 3a of the lower face plate 3 in this state, they are held at equal intervals in parallel with each other along the longitudinal direction of the side wall 4 (see FIG. 3). The grooves 9a, 9b, and 9c are formed with substantially the same width as the diameters of the metal wires 7a, 7b, and 7c at the joint portion between the inner wall 3a and each of the walls along the lateral direction of the side wall 4. The positioning of the electron sources 8a, 8b and 8c inside the vacuum envelope 5 is ensured. At this time, the bottom surfaces of the grooves 9a, 9b, 9c are formed so as to have a certain depth with respect to the inner surface 3a, and the metal wires 7a, 7b, 7c come into contact with the bottom surfaces, so that the metal wires 7a, 7b, The distance from the inner surface 3a over the entire length of 7c is kept stable. Further, the both ends of the metal wires 7a, 7b, and 7c are fitted into the grooves 9a, 9b, and 9c, and then the grooves 9a, 9b, and 9c are sealed with frit glass or the like, so that the vacuum envelope 5 Keeps the inside airtight. When the metal wires 7a, 7b, and 7c are fixed to the grooves 9a, 9b, and 9c using frit glass, it is preferable to use a jig for preventing misalignment.

[0019] Further, in the central portion excluding the joint portion of the inner surface 3a of the lower face plate 3 with the side wall 4, it corresponds to the metal wires 7a, 7b, 7c so as to be connected on the same line as each of the groove portions 9a, 9b, 9c. Grooves 10a, 1 Ob, 10c are formed. The groove portions 10a, 10b, and 10c have widths larger than the diameters of the metal wires 7a, 7b, and 7c including the carbon-based electron emission materials 6a, 6b, and 6c, and are formed deeper than the groove portions 9a, 9b, and 9c, respectively. ing. The metal wires 7a, 7b, and 7c are formed in the groove portions 9a and 9b in the vacuum envelope 5 so that the carbon-based electron emission materials 6a, 6b, and 6c do not contact the side surfaces and the bottom surface of the groove portions 10a, 10b, and 10c, respectively. , 9c is stretched in a straight line in the space surrounded by 9c.

[0020] At the central portion of the inner surface 3a of the lower face plate 3, a mesh-shaped extraction electrode 11 is formed so as to cover the electron sources 8a, 8b, 8c disposed in the grooves 10a, 10b, 10c. It is installed over the inner surface 3a that sandwiches both sides of 10b and 10c (Fig. 2). The extraction electrode 11 is divided into three parts along the longitudinal direction of the metal wires 7a, 7b, and 7c, and an applied voltage is applied to each of the divided extraction electrodes 11. A plurality of external connection pins 12 that are independently connected to each of the divided extraction electrodes 11 are provided through the vacuum envelope 5 so as to be adjustable. The extraction electrode 11 having such a configuration is positioned in the vacuum envelope 5 between the electron sources 8a, 8b, 8c and a target material 15 described later.

[0021] The upper face plate 2 functions as an X-ray extraction window for extracting X-rays to the outside by forming a substantially rectangular through-hole 13 at a position facing each of the electron sources 8a, 8b, 8c. (Figure 1). These through-holes 13 are divided into two along the longitudinal direction of the electron sources 8a, 8b, 8c, and a total of six are arranged. In addition, a silicon thin film 14 is bonded to the outer surface of the upper face plate 2 by anodic bonding so as to cover all the through holes 13, thereby realizing hermetic sealing inside the vacuum envelope 5. Further, a target material 15 such as tungsten is formed by vapor deposition in a portion exposed from the through hole 13 on the inner surface of the silicon thin film 14 (FIG. 4). This target material 15 has the property of generating X-rays in response to the incidence of electrons from the electron sources 8a, 8b, 8c. In this way, the target material 15 is provided in the vacuum envelope 5 so as to face the electron sources 8a, 8b, 8c, so that each of the electron sources 8a, 8b corresponds to the voltage applied to the extraction electrode 11. , 8c are incident on the target material 15, and X-rays generated from the target material 15 are transmitted through the silicon thin film 14 and extracted outside. Note that a conductive member such as tungsten is deposited on the vacuum side of the upper face plate 2 including the inner wall of the through hole 13. The electrons from the electron source 8 are also incident on the upper face plate 2 which is an insulating member, and therefore the upper face plate 2 may be charged and affect the electric field formed in the vacuum envelope 5. . Therefore, charging is prevented by covering the electron incident side with a conductive member. In the present embodiment, vapor deposition is formed integrally with the target material 15. In addition, the voltage supply to the target material 15 is also performed through a conductive member that comes into contact with the external connection pin 17 provided through the vacuum envelope 5 to the outside.

[0022] In the X-ray tube 1 described above, the electrons emitted from the carbon-based electron emitting materials 6a, 6b, 6c on the surfaces of the metal wires 7a, 7b, 7c are incident on the target material 15 to cause X-rays. This X-ray is extracted to the outside through the through hole 13 and the silicon thin film 14. At this time, a stable X-ray irradiation characteristic can be obtained over a wide range by stabilizing the positional relationship between the metal wires 7a, 7b and 7c and the extraction electrode 11 and the target material 15. [0023] Specifically, the lower surface plate 3 of the vacuum envelope 5 in which the metal wires 7a, 7b, 7c constituting the electron sources 8a, 8b, 8c have sufficient strength to hold a vacuum at both ends thereof. Is held in the vacuum envelope 5 in the height direction (direction perpendicular to the inner surface 3a) and in the lateral direction (direction parallel to the inner surface 3a). That is, the distance between the electron sources 8a, 8b, 8c and the inner surface 3a of the lower face plate 3 by fitting the metal wires 7a, 7b, 7c in the grooves 9a, 9b, 9c with a certain tension applied. Is kept constant. On the other hand, the extraction electrode 11 is laid between the electron sources 8a, 8b, 8c and the target material 15 on the inner surface 3a of the lower face plate 3 of the vacuum envelope 5 having the insulating member force, whereby the electron sources 8a, 8b , 8c and the extraction electrode 11 are kept at a distance, so that the amount of electron emission from the electron sources 8a, 8b, 8c is made uniform. In particular, in the X-ray tube 1, the electric field strength between the electron sources 8a, 8b, 8c and the extraction electrode 11 is π! The effect of stabilization of the electron E mission weight for the current density emitted as high as 2～50MAZcm ² order of ~ m about the large instrument carbonaceous electron-emitting material is great. Furthermore, in a general X-ray tube, it is necessary to increase the amount of current, and the metal wires 7a, 7b, 7c constituting the electron sources 8a, 8b, 8c need to be thickened to about 0.5 mm to several mm. Therefore, the effect of stabilizing the position of the electron source by being held by the vacuum envelope 5 is also great.

[0024] Since the electron sources 8a, 8b, 8c are not brought into contact with the bottom surfaces and side surfaces of the groove portions 10a, 10b, 10c by adopting the holding structure at the end portion, the carbon-based electron emission materials 6a, 6b, It is possible to prevent the deterioration of the electron emission characteristics due to the peeling of 6c and the poor insulation due to the peeled carbon-based electron emitting materials 6a, 6b, 6c coming into contact with the electrodes.

[0025] Further, on the inner surface 3a of the lower face plate 3, grooves 10a, 10b, 10c are formed in the direction along the direction in which the metal wires 7a, 7b, 7c extend, and the metal wires 7a, 7b, 7c Arranged in the space surrounded by the grooves 10a, 10b, 10c, and the extraction electrode 11 is laid along the inner surface 3a sandwiching the grooves 10a, 10b, 10c, so that the electron sources 8a, 8b, 8c are configured. The positioning of the metal wires 7a, 7b, and 7c with respect to the extraction electrode 11 is facilitated, and the electron emission from the electron sources 8a, 8b, and 8c is made more uniform.

[0026] Further, since both ends of the metal wires 7a, 7b, 7c are held by the glass lower face plate 3 which is an insulating member, it is possible to further prevent insulation failure in the metal wires 7a, 7b, 7c. it can.

[0027] Further, the extraction electrode 11 is divided into a plurality along the longitudinal direction of the metal wires 7a, 7b, 7c, and the voltage can be adjusted for each of the extraction electrodes 11, so that the metal wires 7a, 7b, As a result of controlling the amount of extracted electrons along the longitudinal direction of 7c, uniform X-ray irradiation characteristics can be obtained along the longitudinal direction of the metal wires 7a, 7b, 7c.

[0028] [Second Embodiment]

Next, a second embodiment of the present invention will be described. FIG. 5 is a plan view showing a state in which the upper face plate of the X-ray tube 21 according to the second embodiment of the present invention is removed, and FIG. 6 is a view of the VI-- in the state including the upper face plate of the X-ray tube 21 in FIG. It is sectional drawing along a VI line. In the X-ray tube 21 according to the present embodiment, the configuration of the extraction electrode provided on the inner surface 3a of the lower face plate 3 is different from that of the first embodiment. The configuration of the upper face plate 2 that functions as the X-ray extraction window of the X-ray tube 21 is the same as that of the first embodiment.

Specifically, as shown in FIGS. 5 and 6, an extraction electrode 31 made of a conductive thin film such as an aluminum metal film or an ITO (Indium Tin Oxide) film is formed on the inner surface 3a of the lower face plate 3. Has been. The lead electrode 31 has grooves 10a and 10c formed on the inner surface 3a sandwiched between the groove 10a and the groove 10b, on the inner surface 3a sandwiched between the groove 10b and the groove 10c, and on the two inner surfaces 3a. On the sandwiched inner surface 3a, the metal wires 7a, 7b, 7c are formed in a strip shape parallel to the portion where the carbon-based electron emission materials 6a, 6b, 6c are applied. Further, an external connection terminal 32 provided through the vacuum envelope 5 to the outside is connected to the extraction electrode 31.

[0030] With such an X-ray tube 21 as well, the carbon-based electron emission materials 6a, 6b, and 6c on the surfaces of the metal wires 7a, 7b, and 7c are directed toward the target material 15 by the electric field formed by the extraction electrode 31 and the like. Electrons are emitted and X-rays are generated. These X-rays are extracted through the silicon thin film 14 and are broadened by stabilizing the positional relationship between the metal wires 7a, 7b, 7c and the extraction electrode 31. Stable X-ray irradiation characteristics can be obtained over a range. In particular, by using a conductive thin film formed on the inner surface 3a as the extraction electrode 31, it is possible to prevent the electrons emitted from the electron sources 8a, 8b, and 8c from being absorbed by the extraction electrode. In addition, loss of electron emission can be reduced.

[0031] [Third embodiment] Next, a third embodiment of the present invention will be described. FIG. 7 is a plan view showing a state in which the upper face plate of the X-ray tube 41 according to the third embodiment of the present invention is removed, and FIG. 8 shows a state in which the upper face plate of the X-ray tube 41 in FIG. FIG. 9 is a cross-sectional view taken along the line VIII. FIG. 9 is a cross-sectional view taken along the line IX-IX in the state including the upper face plate of the X-ray tube 41 shown in FIG. The X-ray tube 41 according to this embodiment is different from that of the first embodiment in that the electron sources 8a, 8b, 8c are held by grooves formed in the side wall 4 of the vacuum envelope 5. The configuration of the upper face plate 2 that functions as the X-ray extraction window of the X-ray tube 41 is the same as that of the first embodiment.

That is, both end portions of the metal wires 7a, 7b, 7c are bonded to the lower face plate 3 on the side wall 4 with a certain tension applied to the entire metal wires 7a, 7b, 7c. By being fitted into the grooves 49a, 49b and 49c formed at the upper side, the grooves 49a, 49b and 49c are held in parallel with each other at equal intervals (see FIG. 8). The grooves 49a, 49b, 49c are formed with a width substantially the same as the diameter of the metal wires 7a, 7b, 7c, thereby ensuring the positioning of the electron sources 8a, 8b, 8c inside the vacuum envelope 5. ing. At this time, when the metal wires 7a, 7b, and 7c are accommodated in the groove portions 49a, 49b, and 49c, the position in the vertical direction is reached over the entire length of the metal wires 7a, 7b, and 7c by contacting the inner surface 3a. It is kept stable. Further, the both ends of the metal wires 7a, 7b, and 7c are fitted into the grooves 49a, 49b, and 49c, and then the grooves 49a, 49b, and 49c are sealed with frit glass or the like, whereby the vacuum envelope 5 The interior of is kept airtight. When the metal wires 7a, 7b, and 7c are fixed to the groove portions 49a, 49b, and 49c using frit glass, it is preferable to use a jig for preventing displacement.

[0033] Further, in the central portion excluding the joint portion of the inner surface 3a of the lower face plate 3 with the side wall 4, the metal wires 7a, 7b, 7c are respectively connected so as to be connected to the grooves 49a, 49b, 49c. The corresponding grooves 50a, 50b, 50c are formed! The grooves 50a, 50b, 50d are formed to have a width larger than the diameter of the metal wires 7a, 7b, 7c including the carbon-based electron emission materials 6a, 6b, 6c, respectively. The metal wires 7a, 7b, 7c are formed in the groove portions 49a, 49 in the vacuum envelope 5 so that the carbon-based electron emission materials 6a, 6b, 6c do not contact the side surfaces and the bottom surface of the groove portions 5 Oa, 50b, 50c, respectively. b, stretched in a straight line in the space surrounded by 49c! RU

[0034] In the central portion of the inner surface 3a of the lower face plate 3, a conductive thin film extraction electrode 51 is formed on the convex portions 56 sandwiching both sides of the groove portions 50a, 50b, 50c, and the carbon of the metal wires 7a, 7b, 7c. -Based electron emission materials 6a, 6 It is formed in a strip shape parallel to the part where b and 6c are applied (Fig. 9). This extraction electrode 51 is provided separately on both sides of each metal wire 7a, 7b, 7c, and each extraction electrode 51 is divided into two along the longitudinal direction of the metal wires 7a, 7b, 7c. And installed (Fig. 7). Furthermore, in order to adjust the applied voltage for each divided extraction electrode 51, an external connection terminal 52 that is independently connected to each divided extraction electrode 51 penetrates from the vacuum envelope 5 to the outside. Is provided.

[0035] Also with such an X-ray tube 41, the metal envelopes 7a, 7b, 7c constituting the electron sources 8a, 8b, 8c have a vacuum envelope having sufficient strength to hold a vacuum at both ends. Positioned in the height direction (direction perpendicular to the inner surface 3a) and the lateral direction (direction parallel to the inner surface 3a) in the vacuum envelope 5 by being held by the side wall 4 and the lower face plate 3 As a result, the positional relationship between the metal wires 7a, 7b, 7c and the extraction electrode 31 is stabilized, so that stable X-ray irradiation characteristics can be obtained over a wide range.

[0036] The extraction electrode 51 is divided into a plurality of metal wires 7a, 7b, and 7c along the longitudinal direction of the metal wire, and the voltage can be adjusted for each extraction electrode 51. Even if there is a variation in the distance to the extraction electrode between metal wires and a variation in the coating amount of the carbon-based electron-emitting material, the electron extraction amount should be controlled along the longitudinal direction for each of the metal wires 7a, 7b, and 7c. As a result, uniform X-ray irradiation characteristics can be obtained as a whole.

[0037] [Fourth embodiment]

The fourth embodiment of the present invention will be described below. FIG. 10 is a plan view of the X-ray tube 61 according to the fourth embodiment of the present invention, FIG. 11 is a plan view showing a state in which the upper face plate of the X-ray tube 61 of FIG. 10 is removed, and FIG. FIG. 13 is a cross-sectional view of the X-ray tube 61 taken along line XII-XII, and FIG. 13 is a cross-sectional view of the X-ray tube 61 shown in FIG. The X-ray tube 61 that works in this embodiment is adapted to emit X-rays emitted from the target material 75 provided on the upper face plate 2 in accordance with the emitted electron source force provided on the lower face plate 3. This is a so-called reflective X-ray tube that irradiates from the X-ray extraction window provided on the face plate 3 side.

Specifically, two electron sources 8a and 8b are provided on the lower face plate 3 in the vacuum envelope 5 so as to be parallel to the longitudinal direction of the side wall 4, and these electron sources 8a , 8b make up both ends of the metal wires 7a, 7b with a certain tension applied to the entire metal wires 7a, 7b. The face plate 3 is fitted in the grooves 69a and 69b on the inner surface 3a (see FIG. 12). The grooves 69a and 69b are formed with substantially the same width as the diameters of the metal wires 7a and 7b at the junctions between the respective walls along the short side direction of the side wall 4 and the inner surface 3a. The positioning of the sources 8a and 8b inside the vacuum envelope 5 is ensured. At this time, the bottom surfaces of the grooves 69a and 69b are formed so as to have a certain depth with respect to the inner surface 3a, and the metal wires 7a and 7b come into contact with the bottom surfaces so that the entire length of the metal wires 7a and 7b is reached. The distance from the inner surface 3a is kept stable. Furthermore, after both ends of the metal wires 7a and 7b are fitted in the grooves 69a and 69b, the grooves 69a and 69b are sealed with frit glass or the like, so that the inside of the vacuum envelope 5 is hermetically sealed. It is kept.

[0039] Further, in the central portion excluding the joint portion with the side wall 4 of the inner surface 3a of the lower face plate 3, the groove portions 70a corresponding to the metal wires 7a and 7b are connected to the same line as the groove portions 69a and 69b, respectively. , 70b (Figs. 11 and 13). The groove portions 70a and 70b have a width larger than the diameter of the metal wires 7a and 7b including the carbon-based electron emission materials 6a and 6b, respectively, and are formed deeper than the groove portions 69a and 69b. The metal wires 7a and 7b are respectively located in the spaces surrounded by the grooves 69a and 69b in the vacuum envelope 5 so that the carbon-based electron-emitting materials 6a and 6b do not contact the side surfaces and the bottom surface of the grooves 7Oa and 70b. It is stretched in a straight line.

[0040] On the inner surface 3a of the lower face plate 3, an extraction electrode 71 made of a conductive thin film is provided.

The extraction electrode 71 is formed on the inner surface 3a on the outer side of the groove part 70a and the groove part 70b (the side close to the wall along the longitudinal direction of the side wall 4) and on the convex part 76 formed on the inner side of the groove part 70a and the groove part 70b. In addition, the metal wires 7a and 7b are formed in a strip shape so as to be parallel to the portions where the carbon-based electron emission materials 6a and 6b are applied. Here, with respect to the height from the bottom surface of the groove portions 69a and 69b, the extraction electrode 71 is close to the inner side of the groove portions 70a and 70b, that is, near the central axis L1 of the target material 75 perpendicular to the inner surface of the target material 75 described later. It arrange | positions so that the side (The through-hole (opening part) 73 side mentioned later) may become lower than the outer side of groove part 70a, 70b. Further, these lead electrodes 31 are connected to terminals 72 for external connection provided through the vacuum envelope 5 to the outside.

[0041] The lower face plate 3 is formed with a substantially rectangular through hole (opening) 73 that is divided into two along the longitudinal direction of the electron sources 8a and 8b at the center thereof. Take out Functions as an X-ray extraction window (Fig. 11). In addition, a silicon thin film 74 is bonded to the outer surface of the lower face plate 3 by anodic bonding so as to cover the through-hole 73, thereby realizing airtight sealing of the inner portion of the vacuum envelope 5. Further, a target material 75 is formed by vapor deposition at a portion facing the through hole 73 on the inner surface of the upper face plate 2 (FIG. 13). In this embodiment, as a conductive member for preventing the upper face plate 2 from being charged, tungsten is vapor-deposited integrally with the target material 75 over almost the entire vacuum side of the upper face plate 2. In addition, the voltage supply to the target material 75 is also performed through a conductive member that comes into contact with the external connection pin 77 provided penetrating from the vacuum envelope 5 to the outside. As described above, the target material 75 is provided in the vacuum envelope 5 so as to face the electron sources 8a and 8b and the through hole 73, so that each electron source 8a, Electrons emitted from 8b are incident on the target material 75, and X-rays generated from the target material 75 are transmitted through the silicon thin film 74 and extracted outside.

[0042] Also in the X-ray tube 61 described above, X-rays are generated by the electrons emitted from the carbon-based electron emitting materials 6a and 6b on the surfaces of the metal wires 7a and 7b being incident on the target material 75. X-rays are extracted to the outside through a through hole 73 and a silicon thin film 74 provided at a position facing the target material 75 of the lower face plate 3. At this time, a stable X-ray irradiation characteristic over a wide range can be obtained by stabilizing the positional relationship between the metal wires 7a, 7b, the extraction electrode 71, and the target material 75.

Further, the extraction electrode 71 is formed so that the through hole 73 side is lowered with the grooves 70a and 70b interposed therebetween, and electrons emitted from the electron sources 8a and 8b are directed toward the center of the target material 75. Therefore, electrons can be efficiently incident on the target material 75 in the reflective X-ray tube. As a result, the amount of X-ray irradiation is improved.

In addition, the present embodiment is a reflection type X-ray tube, and the X-ray extraction window (silicon thin film 74) and the target material 75 are provided separately. The heat generated by electron incidence has little effect on the silicon thin film 74. In particular, in the present embodiment, the X-ray extraction window (silicon thin film 74) and the target material 75 are arranged so as to face each other. In particular, it is difficult to be affected by the large distance. In addition, since there is no need to take out X-rays through the target material 75, The thickness of the get material 75 can be increased. For this reason, it is particularly preferred when increasing the electron flow to obtain a large amount of X-rays.

[0045] [Fifth Embodiment]

Next, a fifth embodiment of the present invention will be described. FIG. 14 is a plan view showing a state in which the upper face plate of the X-ray tube 81 according to the fifth embodiment of the present invention is removed, and FIG. 15 shows an XV-- state including the upper face plate of the X-ray tube 81 in FIG. FIG. 16 is a cross-sectional view taken along the line XVI--XVI in a state including the upper face plate of the X-ray tube 81 shown in FIG. In the X-ray tube 81 that works in this embodiment, there is one linear electron source, and the central portion of the electron source is accommodated in the through-hole 73 that is the X-ray extraction window. Different from that. The configuration of the upper face plate 2 on which the target material 75 is formed is the same as that of the fourth embodiment.

That is, both end portions of the metal wire 7a constituting the electron source 8a are held in parallel with the side wall 4 by being fitted into the groove portion 89a formed on the inner surface 3a of the lower face plate 3 (FIG. 14). And Figure 15). The portion of the metal wire 7a where the carbon-based electron emission material 6a is formed is held in the through hole 73 of the lower face plate 3 so as not to contact the side wall of the through hole 73 and the silicon thin film 74 (FIG. 16). .

On the other hand, on the inner surface 3a of the lower face plate 3, a mesh-like extraction electrode 91 is laid so as to cover the opening of the through hole 73 and the carbon-based electron emission material 6a formed on the peripheral surface of the metal wire 7a. And Since the lead electrode 91 and the metal wire 7a are disposed in the X-ray passing region, if a light metal element having a smallest atomic number is used, the generated X-rays are easily transmitted. This is preferable because the X-ray dose does not decrease.

[0048] Also with such an X-ray tube 81, electrons emitted from the carbon-based electron emitting material 6a on the surface of the metal wire 7a are incident on the target material 75, and X-rays are generated. The lower face plate 3 is taken out through a through hole 73 and a silicon thin film 74 provided at a position facing the target material 75. At this time, by stabilizing the positional relationship between the metal wire 7a, the extraction electrode 91, and the target material 75, stable X-ray irradiation characteristics can be obtained over a wide range.

Note that the present invention is not limited to the above-described embodiment. For example, the extraction electrode may be divided and provided corresponding to each electron source, or in the longitudinal direction of the electron source. You may divide and provide along. At this time, a terminal for external connection may be connected to each of the divided extraction electrodes.

Specifically, like the X-ray tube 101 shown in FIG. 17, with respect to the X-ray tube 21 according to the second embodiment, the electron source 8a is formed on the inner surfaces 3a on both sides of the grooves 10a, 10b, 10c. , 8b, 8c may be divided and provided with the extraction electrode 111, and the terminal 112 may be connected to each extraction electrode 111 corresponding to the electron sources 8a, 8b, 8c. Further, like the X-ray tube 121 shown in FIG. 18, an extraction electrode 131 divided in the longitudinal direction of the electron sources 8a, 8b, and 8c is further provided, and a terminal 132 is connected to each of the divided extraction electrodes 131. May be. By dividing the extraction electrode in this way, there is a deviation in the positional relationship between the electron sources and the extraction electrode in the longitudinal direction of one electron source, or between the electron sources and one electron source. Even when there is a variation in the coating amount of the electron emission material in the electron source, the electron emission amount can be made uniform even if the electron source is powerful. In order to improve the voltage resistance between the divided extraction electrodes, it is preferable to arrange ribs having an appropriate thickness between the extraction electrodes.

FIG. 19 shows an X-ray tube 141 having an extraction electrode 151 that is divided into two along the longitudinal direction of the electron source 8a with respect to the X-ray tube 81. In the X-ray tube 141, ribs 157 are provided between the divided extraction electrodes 151 along a direction perpendicular to the electron source 8a. FIG. 20 shows an X-ray tube 161 having an extraction electrode 171 divided into two along the longitudinal direction of the electron sources 8a and 8b with respect to the X-ray tube 61.

In addition, the central portion of the electron source is not limited to being disposed in the groove on the lower face plate 3, and the extraction electrode is not limited to being disposed on the lower face plate 3. 21 is a plan view of an X-ray tube 181 that is a modification of the X-ray tube 41, and FIG. 22 is a cross-sectional view of the X-ray tube 181 in FIG. 21 taken along the line XXII-XXII. As shown in these figures, in the side wall 4, three mutually parallel grooves 190a, 190b, 190c penetrating toward the lower face plate 3 are formed, and the central portions of the electron sources 8a, 8b, 8c are respectively grooved. In the space surrounded by 190a, 190b, 190c and the inner surface 3a, it is held so as not to contact the side wall 4 and the inner surface 3a. In the X-ray tube 181, the extraction electrode 51 is laid on the inner surface of the side wall 4 sandwiching the grooves 190 a, 190 b, 190 c so as to be parallel to the electron sources 8 a, 8 b, 8 c. The inner surface of the side wall 4 here refers to the surface facing the vacuum side of the side wall 4. In addition, the X-ray tube of the present invention is not limited to the configuration in which the electron source is held at the end of the vacuum envelope 5. In FIG. 23, (a) is a plan view showing the main part of an X-ray tube which is a modification of the present invention, and (b) is a cross section along the axial direction of the electron source of the X-ray tube of (a). FIG. In the X-ray tube shown in these figures, the entire electron source 8a is disposed so as to be accommodated in the groove 10a of the lower face plate 3, and the end of the metal wire 7a is a flat surface formed on the bottom surface of the groove 10a. Is placed on the convex portion 203a having Further, lead wires 207a having a certain degree of strength are connected to the upper portions of both ends of the metal wire 7a by welding or the like, and the lead wires 207a are penetrated from the lower face plate 3 to the outside through the groove portions 9a. At this time, by sealing the groove 9a using frit glass or the like, tension is applied to the entire metal wire 7a and the inside of the vacuum envelope 5 is kept airtight.

[0054] With such a configuration, it is possible to prevent positional deviation of several to several tens of μm in the vertical direction of the electron source 8a by directly sealing the metal wire 7a to the vacuum envelope 5 with frit glass. Thus, the X-ray emission amount of the entire X-ray tube can be made uniform and the difference in individual X-ray tube characteristics can be reduced. This is because the electron source 8a can be placed on the convex portion 203a formed on the bottom surface of the groove 10a, so that the electron source can be positioned with high accuracy in the vacuum envelope 5. is there. Also, as shown in FIGS. 24 (a) and (b), the carbon-based electron emission material 6a is applied in the middle of the metal wire 7a, and an intermediate portion is provided, and the downward force of the intermediate portion is also reduced by the metal wire. In order to support 7a, a convex portion 203b is further formed between the convex portions 203a on the bottom surface of the groove portion 10a.

[0055] The configuration of the X-ray tube 61 may be applied to a so-called transmission X-ray tube having an X-ray extraction window on the upper face plate 2 side. That is, as in the X-ray tube 221 shown in FIG. 25, the through-hole 233 is formed in the central portion of the upper face plate 2 in the short direction, and the silicon thin film 14 is disposed outside the upper face plate 2 so as to cover the through-hole 233. Then, the target material 235 may be formed in a portion exposed from the through hole 13 on the inner surface of the silicon thin film 14. Even in such a configuration, with respect to the height of the bottom force of the groove portions 69a and 69b, the extraction electrode 71 is located on the inner side of the groove portions 70a and 70b, that is, the central axis of the target material 235 perpendicular to the inner surface of the target material 235. By arranging the side closer to L2 to be lower than the outside of the groove portions 70a and 70b, electrons can be efficiently incident on the target material 235. In addition, electron beams from multiple electron sources can be output to one X-ray extraction window. The X-ray emission amount per X-ray extraction window can be increased.

[0056] In addition, when the extraction electrode is divided and provided, it is only necessary to set the applied voltage so that the electron emission amount in each divided region is uniform. As such, the applied voltage to each divided region of the extraction electrode may be changed.

Further, although the electron source is arranged along the longitudinal direction of the vacuum envelope 5, it may be arranged along the short direction. In this case, it is preferable to arrange a plurality of electron sources in the longitudinal direction.

[0058] In addition, the vacuum envelope 5 may have the same length in the longitudinal direction and the lateral direction.

[0059] The members constituting the vacuum envelope 5 are not limited to insulating materials, and for example, a conductive member may be used for the upper face plate 2. The window material covering the through-hole 13 is not limited to silicon, and a material having good X-ray transmission such as beryllium may be used.

[0060] Further, the conductive member deposited on the vacuum side of the upper face plate 2 is not limited to being formed integrally with the target material, but is made of a conductive material different from the target material, such as aluminum or the like. A thin film made of ITO (Indium Tin Oxide) or the like may be used.

Claims

The scope of the claims

[1] a vacuum envelope including an insulating member at least in part;

An electron source disposed in the vacuum envelope by including a linear member having a carbon-based electron emission material on a surface thereof, and both ends of the linear member being held by the vacuum envelope;

A target that is provided opposite to the electron source in the vacuum envelope and generates X-rays in response to the incidence of electrons from the electron source;

An X-ray extraction window attached to the vacuum envelope for extracting X-rays generated from the target to the outside;

An extraction electrode provided between the electron source and the target on the inner surface of the insulating member of the vacuum envelope;

An X-ray tube characterized by comprising:

[2] The insulating member is provided with an opening so as to face the target,

The X-ray extraction window is provided so as to cover the opening.

The X-ray tube according to claim 1, wherein:

[3] On the inner surface of the flat insulating member, a groove corresponding to the linear member is formed,

The linear member is disposed in a space surrounded by the groove,

The extraction electrode is laid along the inner surface of the insulating member across the groove.

The X-ray tube according to claim 1 or 2, wherein

[4] On the inner surface of the flat insulating member, a groove corresponding to the linear member is formed,

The linear member is disposed in a space surrounded by the groove,

2. The lead electrode is laid along an inner surface formed so that a central axis side perpendicular to the inner surface of the target is lowered across the groove portion of the insulating member. Or the X-ray tube as described in 2.

[5] Both ends of the linear member are held by the insulating member of the vacuum envelope, The

The X-ray tube according to any one of claims 1 to 4, wherein:

The X-ray tube according to any one of claims 1 to 5, wherein the extraction electrode is divided into a plurality along the longitudinal direction of the linear member.