JP2023171569A

JP2023171569A - Electron gun, x-ray generation tube, x-ray generator, and x-ray imaging system

Info

Publication number: JP2023171569A
Application number: JP2023175930A
Authority: JP
Inventors: 和哉辻野; Kazuya Tsujino
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2021-01-06
Filing date: 2023-10-11
Publication date: 2023-12-01
Also published as: JP2023011740A; JP2021061251A; JP7367165B2; JP7167196B2

Abstract

To provide an X-ray generation tube with high stability in focus size and shape, and high reliability.SOLUTION: An X-ray generation tube including an electron gun has an electron emission unit, a plurality of grid electrodes, and an insulating support member that supports the plurality of grid electrodes. The electron gun has a conductive part that blocks the insulating support member from direct view of electrons emitted from an electron emission part and passing through the grid electrodes.SELECTED DRAWING: Figure 1

Description

本発明は、医療機器および産業機器分野における非破壊Ｘ線撮影等に適用できるＸ線発生装置、および該Ｘ線発生装置を備えるＸ線撮影システムに関する。 The present invention relates to an X-ray generation device that can be applied to non-destructive X-ray photography in the fields of medical equipment and industrial equipment, and an X-ray photography system equipped with the X-ray generation device.

近年半導体デバイス等の微細化や多層化が進み産業分野における半導体集積回路基板に代表される電子デバイス検査においてはＸ線発生管を備えたＸ線検査装置が用いられている。 2. Description of the Related Art In recent years, semiconductor devices and the like have become increasingly miniaturized and multilayered, and in the industrial field, an X-ray inspection apparatus equipped with an X-ray generating tube is used to inspect electronic devices such as semiconductor integrated circuit boards.

ターゲットに電子ビームを照射する電子源として、管軸方向に沿ってターゲットに向けて突出させた電子銃を備えたＸ線発生管が知られている。 2. Description of the Related Art As an electron source for irradiating a target with an electron beam, an X-ray generation tube equipped with an electron gun that projects toward the target along the tube axis direction is known.

特許文献１には、ターゲット側に複数のグリッド電極を備える電子銃とすることにより、ターゲット上に形成される焦点の位置精度とマイクロフォーカス化が図られることが開示されている。 Patent Document 1 discloses that by providing an electron gun with a plurality of grid electrodes on the target side, the positional accuracy and microfocusing of the focal point formed on the target can be achieved.

また、かかる電子銃が備える複数のグリッド電極は、それぞれが絶縁性の部材により支持されることにより、電極間の距離が規定されるとともに、各電極に所定の電位が印加されるように構成されている。 Further, the plurality of grid electrodes included in such an electron gun are each supported by an insulating member, thereby defining the distance between the electrodes and applying a predetermined potential to each electrode. ing.

特許文献２には、微小焦点化を意図して、管軸方向に延びる絶縁性の支柱に複数のグリッド電極が間隔をあけて支持された電子銃を備えたＸ線発生管が開示されている。 Patent Document 2 discloses an X-ray generation tube equipped with an electron gun in which a plurality of grid electrodes are supported at intervals on insulating columns extending in the tube axis direction with the intention of achieving fine focusing. .

特開２００２‐２９８７７２号公報Japanese Patent Application Publication No. 2002-298772 特開２００７‐６６６９４号公報Japanese Patent Application Publication No. 2007-66694

複数のグリッド電極が絶縁部材により支持されたグリッド電極を電子銃に備えるＸ線発生管が適用されたＸ線撮影システムにおいて、撮影画像の品質低下が生じる場合があった。 BACKGROUND ART In an X-ray imaging system to which an X-ray generating tube is applied, in which an electron gun includes a grid electrode in which a plurality of grid electrodes are supported by an insulating member, the quality of the photographed image may deteriorate in some cases.

本願発明者の検討により、Ｘ線発生管の動作履歴に伴い発生する焦点位置または焦点形状の変動が、かかる撮影品質の低下に関係していることが判った。 Through studies conducted by the inventors of the present application, it has been found that fluctuations in the focal position or focal shape that occur with the operation history of the X-ray generating tube are related to such deterioration in imaging quality.

本願発明は、絶縁部材に支持されたグリッド電極を有した電子銃を備え、焦点の位置または形状の変動が抑制された信頼性の高いＸ線発生管、Ｘ線発生装置を提供することを目的とする。また、本願発明は、本願発明に係るＸ線発生装置を備えることにより、高画質のＸ線撮影が可能なＸ線撮影システムを提供することを目的とする。 An object of the present invention is to provide a highly reliable X-ray generation tube and X-ray generation device that includes an electron gun having a grid electrode supported by an insulating member and suppresses fluctuations in the position or shape of the focal point. shall be. Another object of the present invention is to provide an X-ray imaging system capable of performing high-quality X-ray imaging by including the X-ray generator according to the present invention.

本発明に係る第１のＸ線発生管は、電子の照射によりＸ線を発生するターゲットと、
電子を放出する電子放出部と、前記ターゲットに向けて照射される電子ビームを形成するグリッド電極の複数と、前記複数のグリッド電極の少なくとも２つを電気的に絶縁し支持する絶縁支持部材と、を有する電子銃と、を有するＸ線発生管であって、前記電子銃は、前記電子放出部から放出され前記グリッド電極を通過する前記電子からみて前記絶縁支持部材が直視されないように遮る導電部を有していることを特徴とする。 A first X-ray generating tube according to the present invention includes a target that generates X-rays by irradiation with electrons;
an electron emitting part that emits electrons, a plurality of grid electrodes that form an electron beam irradiated toward the target, and an insulating support member that electrically insulates and supports at least two of the plurality of grid electrodes; an electron gun having an electron gun, the electron gun having a conductive part that blocks the insulating support member from being directly viewed from the electrons emitted from the electron emission part and passing through the grid electrode. It is characterized by having the following.

本発明に係る第２のＸ線発生管は、電子の照射によりＸ線を発生するターゲットと、
電子を放出する電子放出部と、前記ターゲットに向けて照射される電子ビームを形成するグリッド電極の複数と、前記複数のグリッド電極の少なくとも２つを電気的に絶縁し支持する絶縁支持部材と、を有する電子銃と、を有するＸ線発生管であって、前記複数のグリッド電極は、前記電子放出部から放出された前記電子が通過される電子通過路を規定し、前記電子銃は、前記電子通過路からみて前記絶縁支持部材が直視されないように遮る導電部を有していることを特徴とする。 The second X-ray generating tube according to the present invention includes a target that generates X-rays by irradiation with electrons;
an electron emitting part that emits electrons, a plurality of grid electrodes that form an electron beam irradiated toward the target, and an insulating support member that electrically insulates and supports at least two of the plurality of grid electrodes; an electron gun having a The electronic device is characterized by having a conductive portion that blocks the insulating support member from being viewed directly from the electron path.

本発明によれば、Ｘ線発生管の電子銃が、電子通過路からみて絶縁支持部材が直視されないように遮る導電部を有することで、焦点の位置または形状の変動が抑制された信頼性の高いＸ線発生管、Ｘ線発生装置を提供することが可能となる。 According to the present invention, the electron gun of the X-ray generating tube has a conductive part that blocks the insulating support member from being directly viewed from the electron passage path, thereby achieving reliability in which fluctuations in the position or shape of the focal point are suppressed. It becomes possible to provide a high quality X-ray generating tube and an X-ray generating device.

本発明の第１の実施形態に係るＸ線発生管を示す概略構成図（ａ）～（ｈ）である。1 is a schematic configuration diagram (a) to (h) showing an X-ray generating tube according to a first embodiment of the present invention. FIG. 参考形態に係るＸ線発生管を示す概略構成図（ａ）～（ｉ）である。1A to 1E are schematic configuration diagrams (a) to (i) showing an X-ray generating tube according to a reference embodiment. 本発明の課題に係る、散乱金属粒子の絶縁支持部材上への推定された堆積過程の概念図（ａ）～（ｆ）である。FIGS. 2A to 2F are conceptual diagrams (a) to (f) of an estimated deposition process of scattered metal particles on an insulating support member, which is a problem of the present invention. 本発明の第２の実施形態に係るＸ線発生管を示す概略構成図（ａ）～（ｊ）である。7A to 7J are schematic configuration diagrams showing an X-ray generating tube according to a second embodiment of the present invention. FIG. 本発明の第３の実施形態に係るＸ線発生管を示す概略構成図（ａ）～（ｈ）である。FIGS. 7A to 7H are schematic configuration diagrams showing an X-ray generating tube according to a third embodiment of the present invention. FIGS. 本発明の第４の実施形態に係るＸ線発生装置を示す概略構成図である。It is a schematic block diagram showing the X-ray generation device concerning the 4th embodiment of the present invention. 本発明の第５の実施形態に係るＸ線撮影システムを示す概略構成図である。FIG. 3 is a schematic configuration diagram showing an X-ray imaging system according to a fifth embodiment of the present invention.

以下に、本発明の好ましい実施形態を、図面を用いて詳細に説明する。これらの実施形態に記載されている構成部材の寸法、材質、形状、その相対配置などは、この発明の範囲を限定する趣旨のものではない。また、本明細書で特に図示又は記載されない部分に関しては、当該技術分野の周知又は公知の技術を適用する。 Below, preferred embodiments of the present invention will be described in detail using the drawings. The dimensions, materials, shapes, relative arrangements, etc. of the constituent members described in these embodiments are not intended to limit the scope of the present invention. Further, for parts not particularly shown or described in this specification, well-known or well-known techniques in the relevant technical field are applied.

＜Ｘ線発生管＞
図１は、本願発明の第１の実施形態に係るＸ線発生管１が示されている。Ｘ線発生管１は、本願発明の基本的な特徴である導電部を備えた透過型のＸ線発生管である。 <X-ray generating tube>
FIG. 1 shows an X-ray generating tube 1 according to a first embodiment of the present invention. The X-ray generating tube 1 is a transmission type X-ray generating tube equipped with a conductive portion, which is a basic feature of the present invention.

図１（ａ）、（ｂ）は、Ｘ線発生管１の基本的な構成を示す２面図であり、図１（ｂ）は、図１（ａ）のＸ線発生管１を陽極側から見た正面図である。また、図１（ｃ）は、本実施形態のＸ線発生管１を駆動した際に、ターゲット上に形成される焦点が示されている図１（ｂ）の部分拡大図である。また、図１（ｄ）は、図１（ａ）に示すＸ線発生管１の電子銃４ｂを拡大した断面図である。さらに、また、図１（ｅ）～（ｈ）は、図１（ｄ）に示す仮想平面Ａ－Ａ、Ｂ－Ｂ、Ｃ－Ｃ、Ｄ－Ｄにおける、電子銃４ｂの断面を示す断面図である。 1(a) and (b) are two-sided views showing the basic configuration of the X-ray generating tube 1, and FIG. 1(b) shows the X-ray generating tube 1 of FIG. 1(a) on the anode side. FIG. Further, FIG. 1(c) is a partially enlarged view of FIG. 1(b) showing the focal point formed on the target when the X-ray generating tube 1 of this embodiment is driven. Further, FIG. 1(d) is an enlarged cross-sectional view of the electron gun 4b of the X-ray generating tube 1 shown in FIG. 1(a). Furthermore, FIGS. 1(e) to (h) are cross-sectional views showing the cross sections of the electron gun 4b on virtual planes AA, BB, CC, and DD shown in FIG. 1(d). It is.

本実施形態では、電子放出部４０から放出された電子ビームをターゲット層５ｃに照射することによりターゲット５ｂからＸ線を発生させる。このため、ターゲット層５ｃは支持基板５ｄが電子銃４ｂに向いている面に配置されている。即ち、電子放出部４０はターゲット５ｂに対向するように陰極４に配置されている。電子放出部４０から放出された電子は、Ｘ線発生管１に印加された管電圧により陰極４と陽極５との間に形成された加速電場により、ターゲット層５ｃでＸ線を発生させる為に必要な入射エネルギーまで加速される。 In this embodiment, X-rays are generated from the target 5b by irradiating the target layer 5c with an electron beam emitted from the electron emitter 40. Therefore, the target layer 5c is arranged on the surface of the support substrate 5d facing the electron gun 4b. That is, the electron emitting section 40 is arranged on the cathode 4 so as to face the target 5b. The electrons emitted from the electron emission section 40 are used to generate X-rays in the target layer 5c by an accelerating electric field formed between the cathode 4 and the anode 5 by the tube voltage applied to the X-ray generation tube 1. It is accelerated to the required incident energy.

陽極５はターゲット５ｂとターゲット５ｂに接続される陽極部材５ａとを備え、Ｘ線発生管１の陽極電位を規定する電極として機能している。 The anode 5 includes a target 5b and an anode member 5a connected to the target 5b, and functions as an electrode that defines the anode potential of the X-ray generating tube 1.

陽極部材５ａは、導電性材料からなりターゲット層５ｃと電気的に接続される。陽極部材５ａは、図１に示すように、支持基板５ｄの周囲に接続されターゲット５ｂを保持している。 The anode member 5a is made of a conductive material and is electrically connected to the target layer 5c. As shown in FIG. 1, the anode member 5a is connected around the support substrate 5d and holds the target 5b.

また、ターゲット層５ｃは、高い原子番号、高融点、高比重の金属元素として、タンタル、モリブデン、タングステン等のターゲット金属が含有されている。一方、支持基板５ｄは、Ｘ線の透過性が高く、熱伝導性が高い材料が好ましく、例えば、ダイヤモンド、窒化ケイ素、炭化ケイ素、窒化アルミ、グラファイト、ベリリウム等を用いることができる。特に、ダイヤモンドは、ｓｐ３結合に由来する高い熱伝導性と、放射線に対する高い透過性とを有している点において透過型ターゲットの支持基板材料として好ましい。 Further, the target layer 5c contains a target metal such as tantalum, molybdenum, and tungsten as a metal element having a high atomic number, high melting point, and high specific gravity. On the other hand, the supporting substrate 5d is preferably made of a material with high X-ray transparency and high thermal conductivity, and examples thereof include diamond, silicon nitride, silicon carbide, aluminum nitride, graphite, beryllium, and the like. In particular, diamond is preferable as a support substrate material for a transmission target because it has high thermal conductivity derived from sp3 bonds and high transparency to radiation.

Ｘ線発生管１の内部は、電子線の平均自由行程を確保することを目的として、真空となっている。Ｘ線発生管１の内部の真空度は、１×１０^－４Ｐａ以下であることが好ましく、電子放出部４０の電子放出特性の安定化の観点からは、１×１０^－６Ｐａ以下であることがより一層好ましい。本実施形態においては、電子放出部４０およびターゲット層５ｃは、それぞれ、Ｘ線発生管１の内部空間または内面に配置されている。 The inside of the X-ray generating tube 1 is a vacuum for the purpose of ensuring the mean free path of the electron beam. The degree of vacuum inside the X-ray generating tube 1 is preferably 1×10 ⁻⁴ Pa or less, and from the viewpoint of stabilizing the electron emission characteristics of the electron emitting section 40, it is 1×10 ⁻⁶ Pa or less. It is even more preferable. In this embodiment, the electron emitting section 40 and the target layer 5c are arranged in the internal space or inner surface of the X-ray generating tube 1, respectively.

Ｘ線発生管１の内部の真空は、不図示の排気管および真空ポンプを用いて排気された後、かかる排気管を封止することにより、形成される。Ｘ線発生管１の内部には、真空度の維持を目的として、不図示のゲッタが配置される場合もある。 A vacuum inside the X-ray generating tube 1 is created by evacuating the interior of the X-ray generating tube 1 using an exhaust pipe and a vacuum pump (not shown), and then sealing the exhaust pipe. A getter (not shown) may be arranged inside the X-ray generating tube 1 for the purpose of maintaining the degree of vacuum.

Ｘ線発生管１は、陰極電位に規定される電子放出部４０と、陽極電位に規定されるターゲット層５ｃとの間の電気的絶縁を図る目的において、陽極部材５ａと陰極部材４ａとの間に絶縁管２が狭持されている。即ち、絶縁管２は、管軸方向において一端と他端とが、それぞれ陽極部材５ａと陰極部材４ａとに接続されている。 The X-ray generating tube 1 is provided between an anode member 5a and a cathode member 4a for the purpose of electrically insulating the electron emitting section 40 defined by the cathode potential and the target layer 5c defined by the anode potential. An insulating tube 2 is sandwiched between the two. That is, the insulating tube 2 has one end and the other end connected to the anode member 5a and the cathode member 4a, respectively, in the tube axis direction.

絶縁管２は、ガラス材料やセラミクス材料等の絶縁性材料で構成される。セラミクスからなる絶縁管２は、強度を担保する意図において、外周面を０．１μｍ～１００μｍ厚のガラス層で保護される。 The insulating tube 2 is made of an insulating material such as a glass material or a ceramic material. The outer peripheral surface of the insulating tube 2 made of ceramics is protected with a glass layer having a thickness of 0.1 μm to 100 μm in order to ensure strength.

本実施形態において、絶縁管２、電子放出部４０を備えた陰極４、ターゲット５ｂを備えた陽極５は、真空度を維持するための気密性と大気圧に耐える堅牢性とを有する外囲器を構成している。従って、陰極４及び陽極５は、絶縁管２の管軸方向の両端にそれぞれ接続されることにより、外囲器の部分を構成する。同様にして、支持基板５ｄは、ターゲット層５ｃで発生したＸ線をＸ線発生管１の外に取り出す透過窓の役割を担うとともに、外囲器の部分を構成していると言える。 In this embodiment, the insulating tube 2, the cathode 4 equipped with the electron emitting section 40, and the anode 5 equipped with the target 5b are packaged in an envelope having airtightness to maintain the degree of vacuum and robustness to withstand atmospheric pressure. It consists of Therefore, the cathode 4 and the anode 5 are respectively connected to both ends of the insulating tube 2 in the tube axis direction, thereby forming a portion of the envelope. Similarly, the support substrate 5d plays the role of a transmission window for taking out the X-rays generated in the target layer 5c to the outside of the X-ray generation tube 1, and can also be said to constitute a part of the envelope.

＜電子銃＞
次に本願発明のＸ線発生管の特徴である電子銃について、図１（ａ）、（ｄ）、（ｅ）～（ｈ）を用いて説明する。 <Electron gun>
Next, the electron gun, which is a feature of the X-ray generating tube of the present invention, will be explained using FIGS. 1(a), (d), and (e) to (h).

陰極４は、電子放出部４０、グリッド電極４２、および、グリッド電極を支持する絶縁支持部材４１と、を備える電子銃４ｂと陰極部材４ａを備え、ターゲット５ｂと電子放出部４０とが対向するように配置されている。 The cathode 4 includes an electron gun 4b that includes an electron emission section 40, a grid electrode 42, and an insulating support member 41 that supports the grid electrode, and a cathode member 4a, so that the target 5b and the electron emission section 40 face each other. It is located in

電子放出部４０は、タングステンフィラメント、含浸型カソード、酸化物カソードなどの熱陰極電子源や、モリブデンからなるｓｐｉｎｄｔ型カソード等の冷陰極電子源が適用される。 For the electron emission section 40, a hot cathode electron source such as a tungsten filament, an impregnated cathode, or an oxide cathode, or a cold cathode electron source such as a spindt cathode made of molybdenum is applied.

本実施形態の電子銃４ｂは、図１（ａ）に示す通り、陰極部材４ａより陽極５の側に向かって突出している。このように陽極５の側に電子銃４ｂを突出させた配置とすることは、絶縁耐圧を低下させずに焦点位置精度を担保することと意図するものである。即ち、陰極４と陽極５の間を接続する絶縁管２の沿面経路を所定距離以上に離す、一方で、電子銃４ｂとターゲット５ｂとの距離を所定距離以下とすることにより、電子放出部４０より放出された電子線が管径方向の電場の影響を受け難くされている。 As shown in FIG. 1(a), the electron gun 4b of this embodiment protrudes from the cathode member 4a toward the anode 5 side. The arrangement in which the electron gun 4b protrudes from the anode 5 side in this way is intended to ensure focal position accuracy without lowering the dielectric strength. That is, by separating the creepage path of the insulating tube 2 that connects the cathode 4 and the anode 5 by a predetermined distance or more, and by setting the distance between the electron gun 4b and the target 5b to a predetermined distance or less, the electron emitting part 40 The emitted electron beam is made less susceptible to the influence of the electric field in the tube diameter direction.

電子銃４ｂは、陽極５の側に突出している部分に電子放出部４０、グリッド電極４２が配置される、かかる部分をヘッド部と称する。また、ヘッド部を陰極部材４ａに対して支えている部分をネック部と称する。本実施形態のネック部には、図１（ｄ）～（ｈ）に示すように、電子放出部４０を支えるカソード支持部４５、引き出しグリッド電極４３に引き出し電位を給電する給電部４３ｄ、集束グリッド電極４４に集束電位を給電する給電部４４ｄ、が配置されている。 In the electron gun 4b, an electron emitting section 40 and a grid electrode 42 are disposed in a portion protruding toward the anode 5, and this portion is referred to as a head section. Further, the portion that supports the head portion with respect to the cathode member 4a is referred to as a neck portion. As shown in FIGS. 1(d) to 1(h), the neck portion of this embodiment includes a cathode support portion 45 that supports the electron emitting portion 40, a power feeding portion 43d that feeds an extraction potential to the extraction grid electrode 43, and a focusing grid. A power feeding section 44d that feeds a focused potential to the electrode 44 is arranged.

電子銃４ｂは、図１（ｄ）～（ｈ）に示す様に、電子通過孔４３ｆ、電子通過孔４４ｆを備えた引き出しグリッド電極４３、集束グリッド電極４４と、かかるグリッド電極４３、集束グリッド電極４４を支持する絶縁支持部材４１と、を備えている。グリッド電極４３、集束グリッド電極４４が備える電子通過孔４３ｆ、４４ｆは、電子放出部４０からターゲット５ｂに向かう方向に電子通過路７を規定する。 As shown in FIGS. 1(d) to 1(h), the electron gun 4b includes an electron passing hole 43f, an extraction grid electrode 43 having an electron passing hole 44f, a focusing grid electrode 44, and the grid electrode 43 and the focusing grid electrode. and an insulating support member 41 that supports 44. Electron passing holes 43f and 44f provided in the grid electrode 43 and the focusing grid electrode 44 define an electron passing path 7 in the direction from the electron emission section 40 toward the target 5b.

引き出しグリッド電極４３および、集束グリッド電極４４のいずれも、電子通過路７を通過する電子の運動を規制し、電子ビームのビーム径を規定するという点において共通するため、本願発明においては、グリッド電極４２と、まとめて称する。 Both the extraction grid electrode 43 and the focusing grid electrode 44 are common in that they regulate the movement of electrons passing through the electron passage 7 and define the beam diameter of the electron beam, so in the present invention, the grid electrode They are collectively referred to as 42.

また、引き出しグリッド電極４３は、電子放出部４０から放出された電子が電子通過孔４３ｆを通過する電子の通過量を経時的に制御することを意図して設けられており、不図示の電圧源より複数の電位が切り替えられて印加される。一方、集束グリッド電極４４は、電子に対して集束電場を形成しターゲット５ｂ上に形成する焦点８の大きさを規定することを意図して設けられ、電子放出部４０に対して所定の電位差を有した集束グリッド電位が不図示の電圧源より印加される。 Further, the extraction grid electrode 43 is provided with the intention of controlling over time the amount of electrons emitted from the electron emission section 40 passing through the electron passage hole 43f, and is provided with a voltage source (not shown). A plurality of potentials are switched and applied. On the other hand, the focusing grid electrode 44 is provided with the intention of forming a focusing electric field for electrons and defining the size of the focal point 8 formed on the target 5b, and applies a predetermined potential difference to the electron emitting section 40. A focused grid potential is applied from a voltage source (not shown).

なお、本願明細書における電子通過路７は、電子放出部４０から放出された電子が集束グリッド電極４４を通過するまでの通過経路に対応する。 Note that the electron passage path 7 in this specification corresponds to a passage path through which electrons emitted from the electron emission section 40 pass through the focusing grid electrode 44.

引き出しグリッド電極４３は、電子通過孔４３ｆが設けられ管径方向および周方向に延在する環状部４３ａを備えており、環状部４３ａの外縁において電子通過路７の周囲に９０度間隔で４つ配置された絶縁支持部材４１ａ～４１ｄにより支持されている。 The extraction grid electrode 43 includes an annular portion 43a provided with electron passage holes 43f and extending in the tube radial direction and circumferential direction, and has four annular portions arranged at 90 degree intervals around the electron passage path 7 at the outer edge of the annular portion 43a. It is supported by disposed insulating support members 41a to 41d.

絶縁支持部材４１ａ～４１ｄは、グリッド電極４２との接続部における熱応力を緩和するために、グリッド電極４２と線膨張係数の整合がはかられる。グリッド電極４２がモリブデン（３００Ｋにおけるα＝４．８×１０^－６Ｋ^－１）で構成されている場合は、アルミナ（３００Ｋにおけるα＝７．０×１０^－６Ｋ^－１）が適用される。グリッド電極４２と絶縁支持部材４１ａ～４１ｄとは不図示のろう材を介して接合されている。 The insulating support members 41a to 41d are matched in linear expansion coefficient with the grid electrode 42 in order to relieve thermal stress at the connection portion with the grid electrode 42. If the grid electrode 42 is made of molybdenum (α=4.8×10 ⁻⁶ K ⁻¹ at 300K), alumina (α=7.0×10 ⁻⁶ K ⁻¹ at 300K) is applied. . The grid electrode 42 and the insulating support members 41a to 41d are joined via a brazing material (not shown).

なお、グリッド電極４３、集束グリッド電極４４のそれぞれが複数配置される形態も本願発明の実施態様（不図示）に含まれる。従って、グリッド電極４２が、３以上である形態も本願発明の実施態様（不図示）に含まれる。かかる態様においては、絶縁支持部材４１は、複数のグリッド電極４２の少なくとも２つを電気的に絶縁するとともに支持する。 Note that a configuration in which a plurality of each of the grid electrodes 43 and the focusing grid electrodes 44 are arranged is also included in the embodiment (not shown) of the present invention. Therefore, an embodiment in which the number of grid electrodes 42 is three or more is also included in the embodiment (not shown) of the present invention. In this embodiment, the insulating support member 41 electrically insulates and supports at least two of the plurality of grid electrodes 42.

また、集束グリッド電極４４は、図１（ｄ）、（ｈ）に示す様に、引き出しグリッド電極４３の電子通過孔４３ｆを通過した電子が通過可能な電子通過孔４４ｆが設けられ管径方向および周方向に延在する環状部４４ａを備えている。 Further, as shown in FIGS. 1(d) and 1(h), the focusing grid electrode 44 is provided with an electron passing hole 44f through which electrons that have passed through the electron passing hole 43f of the extraction grid electrode 43 can pass. It includes an annular portion 44a extending in the circumferential direction.

なお、環状部４３ａ、４４ａは、管径方向（ｙｚ平面）に平行である必要は無く、電子通過路７を規定するだけの電場が形成する形態であればよく、すり鉢状（コーン状）であっても良い。また、環状部４３ａ、４４ａは、メッシュ状グリッド、スパイラル状グリッド電極、多重環状電極等の不連続な形状であっても良い。 Note that the annular portions 43a and 44a do not need to be parallel to the tube diameter direction (yz plane), and may have a shape that forms an electric field sufficient to define the electron passage path 7, and may be mortar-shaped (cone-shaped). It's okay. Further, the annular portions 43a and 44a may have a discontinuous shape such as a mesh grid, a spiral grid electrode, or multiple annular electrodes.

＜第１の実施形態＞
次に、本願発明の特徴である導電部を備えた第１の実施形態に係るＸ線発生管について、図１（ａ）～（ｈ）の各図を用いてより詳細に説明する。 <First embodiment>
Next, the X-ray generating tube according to the first embodiment equipped with a conductive part, which is a feature of the present invention, will be described in more detail with reference to FIGS. 1(a) to 1(h).

本実施形態のグリッド電極４２は、電子放出部４０に近い側に引き出しグリッド電極４３、電子放出部４０から遠い側に集束グリッド電極４４を備えている。引き出しグリッド電極４３は、さらに、管軸方向に延在する管状部４３ｂ、４３ｃを備えている。管状部４３ｂ、４３ｃは、管径方向と交差する方向に延在しているとも言える。管状部４３ｂおよび４３ｃは、電子放出部４０の側と、集束グリッド電極４４の側と、に環状部４３ａからそれぞれ突出している管状の突出部である。管状部４３ｂ、４３ｃは、引き出しグリッド電極４３の部分であり、環状部４３ａとともに、不図示の電圧源に電気的に接続されて電位規定されている。 The grid electrode 42 of this embodiment includes an extraction grid electrode 43 on the side closer to the electron emission part 40 and a focusing grid electrode 44 on the side far from the electron emission part 40. The extraction grid electrode 43 further includes tubular portions 43b and 43c extending in the tube axis direction. It can also be said that the tubular portions 43b and 43c extend in a direction intersecting the tube diameter direction. The tubular portions 43b and 43c are tubular protrusions that protrude from the annular portion 43a on the electron emitting portion 40 side and the focusing grid electrode 44 side, respectively. The tubular portions 43b and 43c are part of the extraction grid electrode 43, and together with the annular portion 43a, are electrically connected to a voltage source (not shown) to regulate the potential.

また、集束グリッド電極４４は、環状部４４ａの外縁において、電子通過路７の周りに９０度間隔で４つ配置された絶縁支持部材４１ａ～４１ｄにより支持されている。環状部４４ａは、ターゲット５ｂに対向するように配置されている。 Further, the focusing grid electrode 44 is supported by four insulating support members 41a to 41d arranged at 90 degree intervals around the electron passage 7 at the outer edge of the annular portion 44a. The annular portion 44a is arranged to face the target 5b.

なお、環状部４４ａは、環状部４３ａと同様にして、電子通過路７を規定するだけの電場が形成されればよく、すり鉢状（コーン状）やメッシュ状の形態であっても良い。 Note that the annular portion 44a only needs to form an electric field sufficient to define the electron passage path 7, similar to the annular portion 43a, and may have a mortar-like (cone-like) or mesh-like form.

本実施形態の集束グリッド電極４４は、さらに、管軸方向に延在す管状部４４ｂ、４４ｃを備えている。管状部４４ｂ、４４ｃは、管径方向と交差する方向に延在しているとも言える。管状部４４ｂおよび４４ｃは、電子放出部４０の側と隣接する陽極５の側とにそれぞれ突出している管状の突出部である。管状部４４ｂ、４４ｃは、集束グリッド電極４４の部分であり、環状部４４ａとともに、不図示の電圧源に電気的に接続されて電位規定されている。 The focusing grid electrode 44 of this embodiment further includes tubular portions 44b and 44c extending in the tube axis direction. It can also be said that the tubular portions 44b and 44c extend in a direction intersecting the tube diameter direction. The tubular portions 44b and 44c are tubular protrusions that protrude toward the electron emitting portion 40 side and the adjacent anode 5 side, respectively. The tubular portions 44b and 44c are part of the focusing grid electrode 44, and together with the annular portion 44a, are electrically connected to a voltage source (not shown) to regulate the potential.

管状部４３ｂは、図１（ｄ）、（ｅ）に示す様に、電子通過路７から絶縁支持部材４１が直視されないように、陰極部材４ｂの側に突出している。ここで、管状部４３ｂは、引き出しグリッド電極４３と電子放出部４０とが短絡しないように、管径方向において電子放出部４０に対して離間している。 As shown in FIGS. 1D and 1E, the tubular portion 43b protrudes toward the cathode member 4b so that the insulating support member 41 is not directly viewed from the electron passage 7. Here, the tubular portion 43b is spaced apart from the electron emitting section 40 in the tube diameter direction so that the extraction grid electrode 43 and the electron emitting section 40 are not short-circuited.

また、管状部４３ｃ、管状部４４ｂは、図１（ｄ）、（ｇ）に示す様に、電子通過路７から絶縁支持部材４１が直視されないように、管軸方向において重なる様に、互いに反対方向に突出している。即ち、グリッド電極４２（４３、４４）同士が短絡しないように、環状部４４ａと環状部４３ａ、及び、管状部４３ｃと管状部４４ｂは、それぞれ離間している。 Further, as shown in FIGS. 1(d) and 1(g), the tubular portion 43c and the tubular portion 44b are arranged opposite to each other so as to overlap in the tube axis direction so that the insulating support member 41 is not directly viewed from the electron passageway 7. protrudes in the direction. That is, the annular portion 44a and the annular portion 43a, and the tubular portion 43c and the tubular portion 44b are spaced apart from each other so that the grid electrodes 42 (43, 44) are not short-circuited.

なお、引き出しグリッド電極４３、集束グリッド電極４４は、図１（ｄ）、（ｇ）に示すように、互いの環状部４３ａ、４４ａが管軸方向に対向し、互いの管状部４３ｃ、４４ｂが管径方向に対向する部分を有する一対のグリッド電極４２であると言える。このような環状部４３ａ、４４ａ（導電部６）を備えることにより、本実施形態の電子銃４ｂは、絶縁支持部材４１ａ～４１ｄ上への管径方向に移動する散乱金属粒子の堆積が抑制される。 As shown in FIGS. 1(d) and 1(g), the extraction grid electrode 43 and the focusing grid electrode 44 have their respective annular portions 43a and 44a facing each other in the tube axis direction, and their respective tubular portions 43c and 44b facing each other in the tube axis direction. It can be said that they are a pair of grid electrodes 42 having portions facing each other in the tube diameter direction. By providing such annular parts 43a and 44a (conductive part 6), the electron gun 4b of this embodiment can suppress the accumulation of scattered metal particles moving in the tube diameter direction on the insulating support members 41a to 41d. Ru.

また、管状部４３ｃは管状部４４ｂより、管径方向において内側に位置している。即ち、環状部４３ａが電子放出部４０に近い側に位置する引き出しグリッド電極４３の管状部４３ｃは、環状部４４ａが電子放出部４０から遠い側に位置する集束グリッド電極４４の管状部４４ｂより、管径方向において内側に位置しているとも言える。 Further, the tubular portion 43c is located inside the tubular portion 44b in the tube diameter direction. That is, the tubular part 43c of the extraction grid electrode 43, in which the annular part 43a is located closer to the electron emitting part 40, has a larger diameter than the tubular part 44b of the focusing grid electrode 44, in which the annular part 44a is located farther from the electron emitting part 40. It can also be said that it is located inside in the pipe radial direction.

導電部６（管状部４３ｂ、４３ｃ、４４ｂ）は、電子通過路７から飛翔する金属粒子が、絶縁支持部材４１に堆積することを抑制し、絶縁支持部材４１の絶縁性を維持する役割を担う。これにより、電子放出部４０、グリッド電極４２（４３、４４）は、安定してそれぞれの所定の電位に規定される。この為、本実施形態に係るＸ線発生管１は、動作履歴に伴う焦点８の大きさ、位置および形状の変動が抑制され高い信頼性を有するものとなる。 The conductive portion 6 (tubular portions 43b, 43c, and 44b) plays a role in suppressing metal particles flying from the electron path 7 from depositing on the insulating support member 41 and maintaining the insulation properties of the insulating support member 41. . As a result, the electron emitting section 40 and the grid electrodes 42 (43, 44) are stably defined at their respective predetermined potentials. For this reason, the X-ray generating tube 1 according to the present embodiment has high reliability because fluctuations in the size, position, and shape of the focal point 8 due to the operation history are suppressed.

導電部６（管状部４３ｂ、４３ｃ、４４ｂ）は、本実施形態においては、グリッド電極４２（４３、４４）の部分であって導電性を有している。従って、隣接する電子放出部４０、グリッド電極４２（４３、４４）が短絡しない範囲において、かかる導電部６（管状部４３ｂ、４３ｃ、４４ｂ）に金属粒子が堆積しても、グリッド電極による電場規定作用の変動が生じない。 In this embodiment, the conductive part 6 (tubular parts 43b, 43c, 44b) is a part of the grid electrode 42 (43, 44) and has conductivity. Therefore, even if metal particles are deposited on the conductive part 6 (tubular parts 43b, 43c, 44b), as long as the adjacent electron emitting part 40 and the grid electrode 42 (43, 44) are not short-circuited, the grid electrode can regulate the electric field. No fluctuation in action occurs.

本実施形態に係るＸ線発生管１によれば、電子通過路７からみて絶縁支持部材４１が直視されないように遮る導電部６（管状部４３ｂ、４３ｃ、４４ｂ）を電子銃４ｂが有することで、絶縁支持部材４１の絶縁性が担保される。このような導電部６（管状部４３ｂ、４３ｃ、４４ｂ）を有する電子銃４ｂを備えることで、焦点８の大きさ、位置および形状の変動が抑制された信頼性の高いＸ線発生管１を提供することが可能となる。 According to the X-ray generating tube 1 according to the present embodiment, the electron gun 4b has the conductive portion 6 (tubular portions 43b, 43c, 44b) that blocks the insulating support member 41 from being viewed directly from the electron passage path 7. , the insulation properties of the insulating support member 41 are ensured. By providing the electron gun 4b having such a conductive portion 6 (tubular portions 43b, 43c, and 44b), a highly reliable X-ray generating tube 1 in which fluctuations in the size, position, and shape of the focal point 8 are suppressed can be obtained. It becomes possible to provide

なお、本実施形態においては、導電部６（４３ｂ、４３ｃ、４４ｂ）は、グリッド電極４２（４３、４４）の部分であったが、グリッド電極４２（４３、４４）とは、電気的に分離した金属材料を配置する形態も本発明に含まれる。一方で、グリッド電極４２（４３、４４）が配置されるスペースにおいて、導電部６とグリッド電極４２との短絡、または導電部６と電子放出部４０との短絡、を抑制する為には、本実施形態のように導電部６がグリッド電極４２の部分であることが好ましい。 In addition, in this embodiment, the conductive part 6 (43b, 43c, 44b) is a part of the grid electrode 42 (43, 44), but it is electrically separated from the grid electrode 42 (43, 44). The present invention also includes a form in which metal materials are arranged. On the other hand, in order to prevent a short circuit between the conductive part 6 and the grid electrode 42 or a short circuit between the conductive part 6 and the electron emitting part 40 in the space where the grid electrode 42 (43, 44) is arranged, it is necessary to It is preferable that the conductive part 6 is a part of the grid electrode 42 as in the embodiment.

また、本実施形態においては、図１（ｅ）、（ｇ）に示す様に導電部６（４３ｂ、４３ｃ、４４ｂ）は、電子通過路７からみて絶縁支持部材４１ａ～４１ｄが直視されないように遮る管状の形態をとっているが、管状であることは必須では無い。例えば、周方向に離散的に配置さている絶縁支持部材４１ａ～４１ｄのそれぞれに対応して、周方向に離散的に導電部を配置する形態（不図示）も本発明の態様に含まれる。 Further, in this embodiment, as shown in FIGS. 1(e) and 1(g), the conductive portions 6 (43b, 43c, 44b) are arranged so that the insulating support members 41a to 41d are not directly viewed from the electron passage path 7. Although it has a tubular shape, it is not essential that it be tubular. For example, an embodiment of the present invention includes a form (not shown) in which conductive parts are arranged discretely in the circumferential direction, corresponding to each of the insulating support members 41a to 41d arranged discretely in the circumferential direction.

電子通過路７から金属粒子が飛翔し、絶縁支持部材４１ａ～４１ｄに堆積する機序については、後述する。 The mechanism by which metal particles fly from the electron path 7 and deposit on the insulating support members 41a to 41d will be described later.

＜参考形態＞
本願発明者は、絶縁支持部材に支持されたグリッド電極を備える電子銃を有するＸ線発生管において、Ｘ線発生管の駆動履歴に伴う焦点径の変動を確認した。 <Reference form>
The inventors of the present application have confirmed that, in an X-ray generating tube having an electron gun including a grid electrode supported by an insulating support member, the focal diameter varies with the drive history of the X-ray generating tube.

図２（ａ）～（ｅ）は、グリッド電極４２、４３が管状部（導電部）を備えていない点において第１の実施形態と相違する参考形態に係るＸ線発生管３０１が図示されている。 FIGS. 2(a) to 2(e) illustrate an X-ray generating tube 301 according to a reference embodiment that differs from the first embodiment in that the grid electrodes 42 and 43 do not have tubular portions (conductive portions). There is.

図２（ａ）～（ｈ）は、第１の実施形態に係る図１（ａ）～（ｈ）に対応して示されている。一方、図２（ｉ）は、１０^４回の曝射動作後のＸ線発生管３０４に認められた焦点３０８を模式的に示すものであって、第１の実施形態と相違し焦点径の拡大が見て取れる。 FIGS. 2A to 2H are shown corresponding to FIGS. 1A to 1H according to the first embodiment. On the other hand, FIG. 2(i) schematically shows a focal point 308 observed in the X-ray generating tube 304 after 10 ⁴ exposure operations, and differs from the first embodiment in that the focal point diameter is You can see the expansion.

本願発明者の鋭意なる検討の結果、絶縁支持部材に支持されたグリッド電極を備える電子銃を有するＸ線発生管において、駆動履歴に伴う焦点径の変動に関し以下の５点の観測事実を確認した。
・焦点径の変動は、休止期間により回復が無く、不可逆的であったこと。
・焦点径の変動量に対する相関係数の二乗Ｒ^２は、管電圧＜曝射強度≒電子線の照射量＜電子放出源のフィラメント電流、の順であったこと。
・変動量が大きかったＸ線発生管の電子銃を解析したところ、グリッド電極間、グリッド電極と電子銃との間のノード間抵抗の減少が認められたこと。
・変動量が大きかったＸ線発生管の電子銃を分析したところ、絶縁支持部材の表面組成に特定の金属の増加が認められたこと。
・増加が認められた金属は、電子放出部由来の成分Ｂａが支配的であったこと。 As a result of intensive studies by the inventor of the present application, the following five observations were confirmed regarding fluctuations in the focal diameter due to drive history in an X-ray generation tube having an electron gun equipped with a grid electrode supported by an insulating support member. .
・The change in focal diameter did not recover during the rest period and was irreversible.
- The square ^R2 of the correlation coefficient with respect to the amount of variation in the focal diameter was in the following order: tube voltage<exposure intensity≒electron beam irradiation amount<filament current of the electron emission source.
- When analyzing the electron gun of an X-ray generator tube, which had a large amount of fluctuation, it was found that the resistance between nodes between the grid electrodes and between the grid electrode and the electron gun decreased.
- When analyzing the electron gun of the X-ray generator tube, which had large fluctuations, an increase in the amount of a specific metal was found in the surface composition of the insulating support member.
- The metal in which an increase was observed was dominated by Ba, a component derived from the electron-emitting region.

かかる観測事実に基づき本願発明者は、「焦点径の変動要因は、Ｘ線発生管の動作に伴う絶縁支持部材３４１への散乱金属粒子の堆積にある」ものと推定するに至った。 Based on these observational facts, the inventor of the present application has come to the conclusion that "the cause of the variation in the focal spot diameter is the accumulation of scattered metal particles on the insulating support member 341 accompanying the operation of the X-ray generating tube."

＜散乱金属粒子発生の素過程＞
次に、図３（ａ）～（ｆ）を用いて、本願発明の課題に係る散乱金属粒子の発生と絶縁支持部材上への堆積に係る、本願発明者が推敲した素過程を説明する。 <Elementary process of scattering metal particle generation>
Next, with reference to FIGS. 3(a) to 3(f), the elementary process elaborated by the inventor of the present invention regarding the generation of scattered metal particles and the deposition on the insulating support member, which is the object of the present invention, will be explained.

Ｘ線発生管３０１の内部は、不可避に残留するガスと共に、金属粒子が浮遊している。かかる金属粒子は、電子放出部３４０、ターゲット層３０５ｃの構成材料の一部が真空空間に放出された成分と考えられる。金属粒子の放出過程は、Ｘ線発生管の曝射動作、電子銃の電子放出動作に依拠していた観測結果から、図３（ａ）に示す様に、電子放出部３４０からの蒸発、ターゲット層３０５ｃ、グリッド電極３４２に対するスパッタリング等が考えられる。 Inside the X-ray generating tube 301, metal particles are floating along with unavoidably remaining gas. Such metal particles are considered to be components that are part of the constituent materials of the electron emitting portion 340 and the target layer 305c and are emitted into the vacuum space. The emission process of metal particles is based on the observation results that depend on the exposure operation of the X-ray generator tube and the electron emission operation of the electron gun. As shown in FIG. Sputtering, etc. for the layer 305c and the grid electrode 342 can be considered.

浮遊している金属粒子は数ｅＶ以下程度の運動エネルギーである為、大半は発生箇所またはその近傍に捕獲されるが、残部は、図３（ｂ）、（ｃ）に示す様に、電子、Ｘ線の照射を受けて、陽イオン化する。 Since the floating metal particles have a kinetic energy of several eV or less, most of them are captured at or near the point where they are generated, but the rest are electrons, It becomes a positive ion when exposed to X-rays.

酸化バリウムが含侵された含浸型の電子放出部３４０を例に、電子放出部３４０から蒸散したＢａ粒子のイオン化過程を［化１］、［化２］に示す。
Ｂａ（Ｘ－ｒａｙ入射）→ Ｂａ^＋＋ｅ^― ［化１］
Ｂａ（＋ｅ^－入射） → Ｂａ^＋＋２ｅ^― ［化２］ [Chemical formula 1] and [Chemical formula 2] show the ionization process of Ba particles evaporated from the electron-emitting part 340, taking as an example the impregnated type electron-emitting part 340 impregnated with barium oxide.
Ba (X-ray incident) → Ba ⁺ + e ^- [Chemical formula 1]
Ba (+e ^- incident) → Ba ⁺ + 2e ^- [Chemical formula 2]

一方、発生した金属イオンは、電子銃３０４ｂまたはＸ線発生管３０１内部の電場から受ける静電力により、図３（ｄ）に示す様に、陰極部材３０４の側に移動し、その大半が、陰極３０４に捕獲される。捕獲された金属イオンは、［化３］のように、陰極３０４上で電子を受け渡され金属層として堆積すると考えられる。
Ｂａ^＋＋ｅ^－ → Ｂａ［化３］ On the other hand, the generated metal ions move toward the cathode member 304 as shown in FIG. 3(d) due to the electrostatic force received from the electric field inside the electron gun 304b or the Captured in 304. It is thought that the captured metal ions receive electrons on the cathode 304 and are deposited as a metal layer, as shown in [Chemical formula 3].
Ba ⁺ + e ^- → Ba [Chemical formula 3]

なお、陰極３０４に堆積する金属は、陰極３０４を構成する陰極部材３０４ａ、電子放出部３４０の電場規定性能に影響を与えないため許容される。 Note that metal deposited on the cathode 304 is allowed because it does not affect the electric field regulating performance of the cathode member 304a and the electron emitting section 340 that constitute the cathode 304.

一方、金属イオンの残部は、陰極３０４に捕獲される前に、図３（ｅ）に示す様に、散乱電子、電子ビームと再結合し、電子ビーム、散乱電子の運動エネルギーの一部を受け取り、中性の散乱金属粒子となる。 On the other hand, before being captured by the cathode 304, the remaining metal ions recombine with the scattered electrons and the electron beam, and receive part of the kinetic energy of the electron beam and the scattered electrons. , resulting in neutral scattering metal particles.

かかる散乱金属粒子は、電場の影響を受けない為に、管径方向（ｙｚ平面）への移動が可能であり、図３（ｆ）に示す様に、絶縁支持部材３４１の表面に金属粒子が固定化され、金属層を堆積させる。この結果、導電部６（管状部）を有さない電子放出部３０４ｂを有するＸ線発生管３０１は、グリッド電極３４３、３４４の電場規定性能が駆動履歴に伴い低下する。この結果、Ｘ線発生管３０１の動作履歴に伴い、図２（ｃ）に示す初期の焦点８から図２（ｉ）に示すデフォーカスされた焦点３０８への焦点サイズの変動が観測されるものと考えられる。 Since such scattered metal particles are not affected by the electric field, they can move in the tube diameter direction (yz plane), and as shown in FIG. Immobilized and deposits a metal layer. As a result, in the X-ray generating tube 301 having the electron emitting part 304b without the conductive part 6 (tubular part), the electric field regulation performance of the grid electrodes 343 and 344 deteriorates with driving history. As a result, a change in focal spot size from the initial focal point 8 shown in FIG. 2(c) to the defocused focal point 308 shown in FIG. 2(i) is observed with the operation history of the X-ray generating tube 301. it is conceivable that.

＜第２の実施形態＞
図４は、第２の実施形態に係るＸ線発生管１を示すものである。図４（ａ）～（ｈ）の各図は、図１（ａ）～（ｈ）の呈示の方法に準じている。本実施形態は、図４（ｄ）及び図４（ｅ）～（ｈ）に示す様に、絶縁支持部材４１の外側から見て絶縁支持部材４１ａ～４１ｄを隠す外周管状部４４ｅを備えている点において第１の実施形態と相違する。 <Second embodiment>
FIG. 4 shows an X-ray generating tube 1 according to a second embodiment. Each of the figures in FIGS. 4(a) to 4(h) is presented in accordance with the method of presentation in FIGS. 1(a) to (h). As shown in FIGS. 4(d) and 4(e) to (h), this embodiment includes an outer peripheral tubular portion 44e that hides the insulating supporting members 41a to 41d when viewed from the outside of the insulating supporting member 41. This embodiment differs from the first embodiment in this point.

なお、本実施形態においては、外周管状部４４ｅは、集束グリッド電極４４の給電部４４ｄを兼ねており、集束グリッド電極４４（グリッド電極４２）の部分であるとも言える。 In addition, in this embodiment, the outer circumferential tubular part 44e also serves as the power feeding part 44d of the focusing grid electrode 44, and can also be said to be a part of the focusing grid electrode 44 (grid electrode 42).

電子銃４ｂの内側に位置する導電部６（管状部４３ｂ、４３ｃ、４４ｂ）は、電子通過路７からみて絶縁支持部材４１ａ～４１ｄを遮蔽している。これに対して、電子銃４ｂの外側に位置する導電部６（管状部４４ｅ）は、電子銃４ｂと絶縁管２に挟まれた領域から見て絶縁支持部材４１ａ～４１ｄを遮蔽している。 The conductive portion 6 (tubular portions 43b, 43c, and 44b) located inside the electron gun 4b shields the insulating support members 41a to 41d when viewed from the electron passage 7. On the other hand, the conductive portion 6 (tubular portion 44e) located outside the electron gun 4b shields the insulating support members 41a to 41d when viewed from the region sandwiched between the electron gun 4b and the insulating tube 2.

以下に図４（ａ）～（ｊ）を用いて、外周管状部４４ｅが導電部として発現する技術的意義を説明する。 The technical significance of the outer circumferential tubular portion 44e acting as a conductive portion will be explained below using FIGS. 4(a) to (j).

＜＜後方散乱電子に係る散乱金属粒子＞＞
実質的に初速度０で電子放出部４０から放出された電子は、電子通過路７を経た後、管電圧Ｖａの静電ポテンシャルを受けて加速され、運動エネルギーＶａ（ｅＶ）でターゲット５ｂに入射する。 <<Scattered metal particles related to backscattered electrons>>
After passing through the electron passage 7, the electrons emitted from the electron emitting unit 40 with an initial velocity of substantially 0 are accelerated by the electrostatic potential of the tube voltage Va, and enter the target 5b with kinetic energy Va (eV). do.

ターゲット５ｂでは、ターゲット層５ｃの内部で熱エネルギー、二次電子、オージェ電子に変換され、残部がＸ線に変換される。ターゲット層５ｃ内部でターゲット金属と相互作用し減速した成分である二次電子、オージェ電子は、０－５００（ｅＶ）の運動エネルギーしか有さずにターゲット層５ｃの後方に放出されるため、殆どが、陽極５に再入射し捕獲される。 In the target 5b, the energy is converted into thermal energy, secondary electrons, and Auger electrons inside the target layer 5c, and the remainder is converted into X-rays. Secondary electrons and Auger electrons, which are components that interact with the target metal and decelerate inside the target layer 5c, have only kinetic energy of 0 to 500 (eV) and are emitted behind the target layer 5c, so almost no enters the anode 5 again and is captured.

一方、ターゲット層５ｃの表面で、入射電子のうち２０％～４０％程度は弾性散乱する。ターゲット層５ｃの表面で弾性散乱した後方散乱電子は、運動エネルギーＶａ（ｅＶ）を有しており、電子放出部４０の等電位面上にある領域まで到達しうる。 On the other hand, about 20% to 40% of the incident electrons are elastically scattered on the surface of the target layer 5c. The backscattered electrons elastically scattered on the surface of the target layer 5c have kinetic energy Va (eV) and can reach a region on the equipotential surface of the electron emission section 40.

陽極５の側に陰極部材４ａから突出した電子銃４ｂを備えたＸ線発生管１は、陰極４陽極５の間の電場は、図４（ｉ）の様に、陰極４の側において電子銃４ｂによる変形を受けている。 In the X-ray generating tube 1 equipped with the electron gun 4b protruding from the cathode member 4a on the side of the anode 5, the electric field between the cathode 4 and the anode 5 is as shown in FIG. 4(i). 4b.

ターゲット層５ｃから弾性散乱した後方散乱電子は、散乱角度分布を有しており、電子銃４ｂに向かって散乱する成分ばかりでなく、電子銃４ｂと絶縁管２との間の空間にも到達する成分が存在する。 Backscattered electrons elastically scattered from the target layer 5c have a scattering angle distribution, and reach not only components scattered toward the electron gun 4b but also the space between the electron gun 4b and the insulating tube 2. Ingredients are present.

図４（ｉ）には、管径方向に異なるＹ座標を有する管軸方向Ｘ０（ｙ＝－Ψ／２）、Ｘ１（ｙ＝０）および、Ｘ２（ｙ＝－Ψ／４）が示されている。また、図４（ｊ）には、管軸方向Ｘ０（ｙ＝－Ψ／２）、Ｘ１（ｙ＝０）および、Ｘ２（ｙ＝－Ψ／４）に沿った仮想線状の電位分布が示されている。ここで、陽極部材５ａの直径Ψ（ｍ）である。 In FIG. 4(i), tube axis directions X0 (y=-Ψ/2), X1 (y=0), and X2 (y=-Ψ/4) having different Y coordinates in the tube radial direction are shown. ing. In addition, in FIG. 4(j), virtual linear potential distributions along the tube axis directions X0 (y=-Ψ/2), X1 (y=0), and X2 (y=-Ψ/4) are shown. It is shown. Here, it is the diameter Ψ (m) of the anode member 5a.

電子放出部４０の静電ポテンシャルは、カソード電位－Ｖａ（ｅＶ）であるため、Ｘ２（ｙ＝－Ψ／４）に沿って移動する後方散乱電子は、電子放出部４０より陰極部材４ａの側に到達する。 Since the electrostatic potential of the electron emitting section 40 is the cathode potential -Va (eV), the backscattered electrons moving along X2 (y=-Ψ/4) are closer to the cathode member 4a than the electron emitting section 40. reach.

従って、電子銃４ｂと絶縁管２との間の空間に到達する後方散乱電子は、Ｘ線発生管１の内部空間に微量に含まれる金属（陽）イオンと再結合し、中性の散乱金属粒子に変化する。即ち、電子銃４ｂと絶縁管２との間の空間に到達する後方散乱電子は、電子銃４ｂと絶縁管２との間の空間に散乱金属粒子を発生させ、絶縁支持部材４１に金属粒子を堆積させる要因となると考えられる。 Therefore, the backscattered electrons that reach the space between the electron gun 4b and the insulating tube 2 recombine with the metal (positive) ions contained in a trace amount in the internal space of the X-ray generating tube 1, and are converted into neutral scattered metals. Change into particles. That is, the backscattered electrons that reach the space between the electron gun 4b and the insulating tube 2 generate scattered metal particles in the space between the electron gun 4b and the insulating tube 2, and the metal particles are deposited on the insulating support member 41. This is thought to be a factor that causes the accumulation.

本実施形態の外周管状部４４ｅ（導電部）は、かかる電子銃４ｂと絶縁管２との間の空間に発生する散乱金属粒子が絶縁支持部材４１ａ～４１ｄに堆積し絶縁支持部材４１を低抵抗化することを抑制するものである。これにより、電子放出部４０、グリッド電極４２（４３、４４）は、それぞれの所定の電位に安定して規定される。この為、本実施形態に係るＸ線発生管１は、図４（ｃ）に示す様に、動作履歴に伴う焦点８の大きさ、位置および形状の変動が、より一層抑制され高い信頼性を有するものとなる。 In the outer peripheral tubular portion 44e (conductive portion) of this embodiment, scattered metal particles generated in the space between the electron gun 4b and the insulating tube 2 are deposited on the insulating support members 41a to 41d, and the insulating support member 41 has a low resistance. This is to prevent the situation from becoming more difficult. Thereby, the electron emitting section 40 and the grid electrodes 42 (43, 44) are stably defined at their respective predetermined potentials. Therefore, in the X-ray generating tube 1 according to this embodiment, as shown in FIG. 4(c), fluctuations in the size, position, and shape of the focal point 8 due to the operation history are further suppressed, and high reliability is achieved. Become what you have.

外周管状部４４ｅは、管径方向の外側から絶縁支持部材４１ａ～４１ｄ上に散乱金属粒子が堆積する事を抑制するために絶縁支持部材４１ａ～４１ｄの外側に設けられた導電部であるとも言える。 It can be said that the outer peripheral tubular portion 44e is a conductive portion provided outside the insulating support members 41a to 41d in order to suppress the accumulation of scattered metal particles on the insulating support members 41a to 41d from the outside in the tube diameter direction. .

第１および第２の実施態様に係るＸ線発生管は、透過型のターゲットを備えた透過型Ｘ線発生管に適用した例を示した。しかしながら、絶縁支持部材にグリッド電極が支持された電子銃を備えているＸ線発生管に適用され、反射型のターゲットを備えた反射型Ｘ線発生管も本発明の態様に含まれる。 The X-ray generating tubes according to the first and second embodiments are examples in which the X-ray generating tubes are applied to a transmission-type X-ray generating tube equipped with a transmission-type target. However, the present invention also includes a reflection type X-ray generation tube that is applied to an X-ray generation tube equipped with an electron gun in which a grid electrode is supported on an insulating support member, and equipped with a reflection type target.

＜第３の実施形態＞
図５は、第３の実施形態に係るＸ線発生管１を示すものである。図５（ａ）～（ｈ）の各図は、図１（ａ）～（ｈ）の呈示の方法に準じている。本実施形態は、図５（ｄ）及び図５（ｇ）に示す様に、導電部を構成する環状部４３ｃ、４４ｂの管径方向における位置関係において第１の実施形態、第２の実施形態と相違する。即ち、管径方向において、互いに対向する環状部４３ｃ、４４ｂは、陰極４の側に位置する引き出しグリッド電極４３の管状部４３ｃが、陽極５の側に位置する集束グリッド電極４４の管状部４４ｂより、管径方向において外側に位置している。また、陰極４の側に位置する引き出しグリッド電極４３の管状部４３ｃは、陽極５の側に位置する集束グリッド電極４４の管状部４４ｂにより、電子通過路７から直視されないように配置されているとも言える。 <Third embodiment>
FIG. 5 shows an X-ray generating tube 1 according to a third embodiment. Each of the figures in FIGS. 5(a) to 5(h) is presented in accordance with the method of presentation in FIGS. 1(a) to (h). As shown in FIGS. 5(d) and 5(g), this embodiment is different from the first embodiment and the second embodiment in terms of the positional relationship in the pipe diameter direction of the annular parts 43c and 44b that constitute the conductive part. It differs from That is, in the tube diameter direction, the annular portions 43c and 44b facing each other are such that the tubular portion 43c of the extraction grid electrode 43 located on the cathode 4 side is closer to the tubular portion 44b of the focusing grid electrode 44 located on the anode 5 side. , located on the outside in the tube radial direction. Further, the tubular portion 43c of the extraction grid electrode 43 located on the side of the cathode 4 is arranged so as not to be directly viewed from the electron passage path 7 due to the tubular portion 44b of the focusing grid electrode 44 located on the side of the anode 5. I can say it.

このような配置をとることにより、集束グリッド電極４４の環状部４４ａで後方散乱した不図示の反射電子が、引き出しグリッド電極４３の管状部４３ｃに入射する現象が抑制され、引き出しグリッド電極４３の電位変動が抑制される。 By adopting such an arrangement, a phenomenon in which reflected electrons (not shown) backscattered by the annular portion 44a of the focusing grid electrode 44 enter the tubular portion 43c of the extraction grid electrode 43 is suppressed, and the potential of the extraction grid electrode 43 is reduced. Fluctuations are suppressed.

本実施形態のＸ線発生管１によれば、曝射動作履歴に伴い、絶縁支持部材４１ａ～ｄの絶縁性の低下が抑制されるだけでなく、グリッド電極に入射する反射電子の影響が抑制されている。図５（ｂ）、（ｃ）に示すように、焦点８の中心８ｃの位置がより一層安定した、より一層信頼性の高いＸ線発生管提供することが可能となる。 According to the X-ray generating tube 1 of this embodiment, not only is the deterioration of the insulation properties of the insulating support members 41a to 41d caused by the exposure operation history suppressed, but also the influence of reflected electrons incident on the grid electrodes is suppressed. has been done. As shown in FIGS. 5(b) and 5(c), it is possible to provide an even more reliable X-ray generating tube in which the position of the center 8c of the focal point 8 is even more stable.

＜Ｘ線発生装置＞
次に、図６を用いて、本発明のＸ線発生管を備えたＸ線発生装置の構成例について説明する。 <X-ray generator>
Next, an example of the configuration of an X-ray generator equipped with the X-ray generator tube of the present invention will be described with reference to FIG.

図６には、第４の実施形態に係るＸ線発生装置１０１が示されている。Ｘ線発生装置１０１は、第１または第２の実施形態に係るＸ線発生管１、および、Ｘ線発生管１を駆動するための駆動回路１０６と、Ｘ線発生装置１０２および駆動回路１０６を収納する収納容器１０７と、を備えている。 FIG. 6 shows an X-ray generator 101 according to a fourth embodiment. The X-ray generator 101 includes an X-ray generator 1 according to the first or second embodiment, a drive circuit 106 for driving the X-ray generator 1, and an X-ray generator 102 and a drive circuit 106. A storage container 107 for storing the storage.

駆動回路１０６は、陰極および陽極の間に管電圧を印加する管電圧回路１０６ａと、電子銃４ｂの電子放出量を制御する電子量制御回路１０６ｂとを有している。管電圧回路１０６ａにより、ターゲット層５ｃと電子放出部４０との間に加速電場が形成される。ターゲット層５ｃの層厚と金属種とに対応して、管電圧Ｖａを適宜設定することにより、撮影に必要な線種を選択することができる。 The drive circuit 106 includes a tube voltage circuit 106a that applies a tube voltage between the cathode and the anode, and an electron amount control circuit 106b that controls the amount of electrons emitted from the electron gun 4b. An accelerating electric field is formed between the target layer 5c and the electron emitting section 40 by the tube voltage circuit 106a. By appropriately setting the tube voltage Va in accordance with the layer thickness and metal type of the target layer 5c, the line type required for imaging can be selected.

Ｘ線発生管１及び駆動回路１０６を収納する収納容器１０７は、容器としての十分な強度を有し、かつ放熱性に優れたものが望ましく、その構成材料として、例えば真鍮、鉄、ステンレス等の金属材料が用いられる。 The storage container 107 that houses the X-ray generating tube 1 and the drive circuit 106 is preferably one that has sufficient strength as a container and has excellent heat dissipation properties, and its constituent materials include, for example, brass, iron, stainless steel, etc. Metal materials are used.

本実施形態の収納容器１０７は、Ｘ線発生管１の陽極５と電気的に接続され、接地電位に規定されている。 The storage container 107 of this embodiment is electrically connected to the anode 5 of the X-ray generating tube 1, and is set to a ground potential.

一方、収納容器１０７内のＸ線発生管１と駆動回路１０６以外の余空間には、絶縁性流体１０８が充填されることにより、収納容器１０７の収納されている部材と収納容器１０７との電気的絶縁が担保される。収納容器１０７に収納されている部材には、Ｘ線発生管１、駆動回路１０６、及び、不図示の配線等が含まれる。 On the other hand, the remaining space in the storage container 107 other than the X-ray generating tube 1 and the drive circuit 106 is filled with an insulating fluid 108, so that the electrical connection between the components stored in the storage container 107 and the storage container 107 is insulation is guaranteed. The members stored in the storage container 107 include the X-ray generating tube 1, the drive circuit 106, wiring (not shown), and the like.

絶縁性流体１０８は、電気絶縁性を有する液体で、収納容器１０７の内部の電気的絶縁性を維持する役割と、Ｘ線発生管１の冷却媒体としての役割とを有する。絶縁性流体１０８としては、鉱油、シリコーン油、パーフロオロ系オイル等の電気絶縁油、ＳＦ６等の絶縁性ガス等が用いられる。 The insulating fluid 108 is a liquid having electrical insulation properties, and has the role of maintaining electrical insulation inside the storage container 107 and the role of a cooling medium for the X-ray generating tube 1. As the insulating fluid 108, electrical insulating oil such as mineral oil, silicone oil, perfluoro oil, insulating gas such as SF6, etc. are used.

本実施形態のＸ線発生装置１０１は、少なくとも第１～第３の実施形態いずれかに係るＸ線発生管１が適用されることにより、電子線の集束性能における安定性が担保された電子銃を備えるため、焦点８の変動が抑制された信頼性の高いものとなる。 The X-ray generator 101 of the present embodiment is an electron gun in which stability in electron beam focusing performance is ensured by applying the X-ray generator tube 1 according to at least one of the first to third embodiments. As a result, fluctuations in the focal point 8 are suppressed and highly reliable.

＜Ｘ線撮影システム＞
次に、図７を用いて、本発明のＸ線発生装置を備えたＸ線撮影システムの構成例について説明する。 <X-ray imaging system>
Next, an example of the configuration of an X-ray imaging system including the X-ray generator of the present invention will be described with reference to FIG.

図７には、第５の実施形態に係るＸ線撮影システム２００が示されている。Ｘ線撮影システム２００は、Ｘ線発生装置１０１から放出され被検体２０４を透過したＸ線を検出するＸ線検出装置２０１と、Ｘ線発生装置１０１とＸ線検出装置２０１とを連携して制御するシステム制御装置２０１と、を備えている。 FIG. 7 shows an X-ray imaging system 200 according to a fifth embodiment. The X-ray imaging system 200 includes an X-ray detection device 201 that detects X-rays emitted from the X-ray generation device 101 and transmitted through the subject 204, and controls the X-ray generation device 101 and the X-ray detection device 201 in cooperation with each other. A system control device 201 is provided.

駆動回路１０６は、システム制御装置２０２による制御の下に、Ｘ線発生管１に各種の制御信号を出力する。駆動回路１０６が出力する制御信号により、Ｘ線発生装置１０１から放出されるＸ線束の放出状態が制御される。 The drive circuit 106 outputs various control signals to the X-ray generating tube 1 under the control of the system control device 202. The emission state of the X-ray flux emitted from the X-ray generator 101 is controlled by the control signal output by the drive circuit 106.

Ｘ線発生装置１０１から放出されたＸ線束は、被検体２０４を透過して検出器２０６で検出される。検出器２０６は、検出したＸ線を画像信号に変換して信号処理部２０５に出力する。 The X-ray flux emitted from the X-ray generator 101 passes through the subject 204 and is detected by the detector 206 . The detector 206 converts the detected X-rays into an image signal and outputs it to the signal processing unit 205.

信号処理部２０５は、システム制御装置２０２による制御の下に、画像信号に所定の信号処理を施し、処理された画像信号をシステム制御装置２０２に出力する。 The signal processing unit 205 performs predetermined signal processing on the image signal under the control of the system control device 202 and outputs the processed image signal to the system control device 202.

システム制御装置２０２は、処理された画像信号に基づいて、表示装置２０３に画像を表示させるための表示信号を表示装置２０３に出力する。表示装置２０３は、表示信号に基づく画像を、被検体２０４の撮影画像としてスクリーンに表示する。 Based on the processed image signal, the system control device 202 outputs a display signal to the display device 203 for causing the display device 203 to display an image. The display device 203 displays an image based on the display signal as a photographed image of the subject 204 on a screen.

本実施形態のＸ線撮影システム２００は、第４の実施形態に係るＸ線発生装置１０１を備えることにより、焦点８の変動が抑制され高品質の撮影画像を再現性良く取得することができる。なお、Ｘ線撮影システムは、工業製品の非破壊検査や人体や動物の病理診断に適用される。 By including the X-ray generation device 101 according to the fourth embodiment, the X-ray imaging system 200 of this embodiment can suppress fluctuations in the focal point 8 and acquire high-quality captured images with good reproducibility. Note that the X-ray imaging system is applied to non-destructive inspection of industrial products and pathological diagnosis of humans and animals.

１Ｘ線発生管
２絶縁管
４陰極
４ｂ電子銃
５陽極
５ｂターゲット
６導電部
７電子通過路
４０電子放出部
４１絶縁支持部材
４２グリッド電極
４３引き出しグリッド電極
４４集束グリッド電極 1 X-ray generating tube 2 Insulating tube 4 Cathode 4b Electron gun 5 Anode 5b Target 6 Conductive part 7 Electron passage 40 Electron emission part 41 Insulating support member 42 Grid electrode 43 Extraction grid electrode 44 Focusing grid electrode

本発明の実施形態に係る第１の電子銃は、電子の照射によりＸ線を発生するターゲットを含む陽極と、前記ターゲットに電子を照射する陰極と、前記陽極と前記陰極とを絶縁し前記陽極、前記陰極とともに真空容器を構成する絶縁管と、を備えるＸ線発生管に適用される電子銃であって、電子を放出する電子放出部と、前記ターゲットに向けて照射される電子ビームを形成するグリッド電極の複数と、前記複数のグリッド電極の少なくとも２つを電気的に絶縁し支持するために管周方向に離散的に設けられた複数の絶縁支持部材と、を有し、
前記引出電極と前記集束電極は、いずれも、前記電子放出部から前記ターゲットに向かう電子通過路を規定する電子通過孔を有するとともに、前記電子通過路から管径方向の外側に見て前記絶縁支持部材が直視される部分を前記複数の絶縁支持部材のいずれもが有さないように前記引出電極と前記集束電極のそれぞれが前記複数の絶縁支持部材を遮る導電性の遮蔽部を有していることを特徴とする。 A first electron gun according to an embodiment of the present invention includes an anode including a target that generates X-rays by irradiating electrons , a cathode that irradiates the target with electrons, and an anode that insulates the anode and the cathode. , an insulating tube that forms a vacuum vessel together with the cathode, and an electron emitting section that emits electrons; and an electron emitting section that forms an electron beam that is irradiated toward the target. a plurality of grid electrodes, and a plurality of insulating support members provided discretely in the tube circumferential direction to electrically insulate and support at least two of the plurality of grid electrodes ,
The extraction electrode and the focusing electrode each have an electron passage hole that defines an electron passage from the electron emission section to the target, and the insulating support when viewed from the electron passage toward the outside in the tube radial direction . Each of the extraction electrode and the focusing electrode has a conductive shielding portion that blocks the plurality of insulating support members so that none of the plurality of insulating support members has a portion where the member is directly viewed. It is characterized by

本発明の実施形態に係る第２の電子銃は、陽極と、陰極と、前記陽極と前記陰極とを絶縁し前記陽極、前記陰極とともに真空容器を構成する絶縁管と、を備える真空管に適用される電子銃であって、The second electron gun according to the embodiment of the present invention is applied to a vacuum tube including an anode, a cathode, and an insulating tube that insulates the anode and the cathode and forms a vacuum vessel together with the anode and the cathode. An electron gun,
電子を放出する電子放出部と、前記陽極に向けて照射される電子ビームを形成するグリッド電極の複数と、前記複数のグリッド電極の少なくとも２つを電気的に絶縁し支持するために管周方向に離散的に設けられた複数の絶縁支持部材と、を有し、an electron emitting part that emits electrons, a plurality of grid electrodes that form an electron beam irradiated toward the anode, and a tube circumferential direction for electrically insulating and supporting at least two of the plurality of grid electrodes. a plurality of insulating support members provided discretely in the
前記引出電極と前記集束電極は、いずれも、前記電子放出部から前記ターゲットに向かう電子通過路を規定する電子通過孔を有するとともに、Each of the extraction electrode and the focusing electrode has an electron passage hole that defines an electron passage from the electron emission part to the target, and
前記電子通過路から管径方向の外側に見て前記絶縁支持部材が直視される部分を前記複数の絶縁支持部材のいずれもが有さないように前記引出電極と前記集束電極のそれぞれが前記複数の絶縁支持部材を遮る導電性の遮蔽部を有している。Each of the extraction electrode and the focusing electrode is arranged so that none of the plurality of insulating support members has a portion where the insulating support member is directly viewed when viewed from the outside in the radial direction of the tube from the electron passageway. It has a conductive shielding part that shields the insulating support member.

Claims

A target that generates X-rays by irradiating electrons,
an electron emitting part that emits electrons, a plurality of grid electrodes that form an electron beam irradiated toward the target, and an insulating support member that electrically insulates and supports at least two of the plurality of grid electrodes; An electron gun having an X-ray generating tube,
An X-ray generating tube characterized in that the electron gun has a conductive part that blocks the insulating support member from being directly viewed from the electrons emitted from the electron emitting part and passing through the grid electrode.

The X-ray generating tube according to claim 1, wherein the electric potential of the conductive portion is regulated by a voltage source.

the grid electrode is electrically connected to the voltage source;
The X-ray generating tube according to claim 2, wherein the conductive portion is a portion of the grid electrode.

The grid electrode includes an annular portion provided with an electron passage hole defining the electron passage and extending in the tube diameter direction, and a tubular portion connected to the annular portion and extending along the electron passage. have,
The X-ray generating tube according to claim 1, wherein the conductive part is at least a part of the tubular part.

The grid electrode is characterized in that it includes an extraction grid electrode in which the annular part is arranged to face the electron emitting part and the tubular part is arranged to overlap with the electron emitting part in the tube axis direction. The X-ray generating tube according to claim 4.

The plurality of grid electrodes include at least one pair of grid electrodes, the annular portions of which are opposite to each other in the axial direction of the tube, and the tubular portions of each of which are opposite to each other in the radial direction of the tube. 5. The X-ray generating tube according to 4 or 5.

In the pair of grid electrodes, the tubular portion of the grid electrode in which the annular portion is located on the side closer to the electron emitting portion is the tubular portion of the grid electrode in which the annular portion is located on the side farther from the electron emitting portion. 7. The X-ray generating tube according to claim 6, wherein the X-ray generating tube is located on the outer side of the tube in the tube radial direction.

The plurality of grid electrodes include a focusing grid electrode having an annular portion facing the target and defining the size of a focal point formed on the target,
X according to any one of claims 1 to 7, characterized in that the electron passage corresponds to a passage of the electrons emitted from the electron emitting section until they pass through the focusing grid electrode. line generator tube.

The electron gun has an outer circumferential tubular portion on the outer side of the insulating support member in the tube diameter direction so that the insulating support member is not seen directly when viewed from the outside in the tube diameter direction, and the conductive portion is connected to the outer circumferential tubular portion. The X-ray generating tube according to any one of claims 1 to 8, characterized in that it is a section.

The X-ray generating tube according to claim 9, wherein the outer circumferential tubular portion is a part of the grid electrode.

The X-ray generating tube is
an anode member connected to the target and included in the anode together with the target;
a cathode member connected to the electron gun and included in the cathode together with the electron emission source;
X according to any one of claims 1 to 10, characterized in that one end and the other end in the tube axis direction have an insulating tube connected to the anode member and the cathode member, respectively. line generator tube.

The X-ray generating tube is
an anode member connected to the target and included in the anode together with the target;
a cathode member connected to the electron gun and included in the cathode together with the electron emission source;
an insulating tube having one end and the other end in the tube axis direction connected to the anode member and the cathode member, respectively,
The X-ray generating tube according to claim 9 or 10, wherein the outer peripheral tubular portion is fixed to the cathode member.

The conductive portion is located between the electron passageway and the insulating support member so as to suppress scattering metal particles moving from the electron passageway side from being deposited on the insulating support member. The X-ray generating tube according to any one of claims 1 to 12.

14. The target is a transmission type target having a target layer that generates X-rays when irradiated with electrons, and a support substrate that supports the target layer and transmits the X-rays. The X-ray generating tube according to any one of the above.

The X-ray generating tube according to any one of claims 1 to 14 is electrically connected to each of the target and the electron emitting section, and is applied between the target and the electron emitting section. An X-ray generator comprising: a drive circuit that outputs a tube voltage.

The X-ray generator according to claim 15;
an X-ray detection device that detects the X-rays emitted from the X-ray generation device and transmitted through the subject;
a system control device that cooperatively controls the X-ray generator and the X-ray detector;
An X-ray imaging system comprising:

A target that generates X-rays by irradiating electrons,
an electron emitting part that emits electrons, a plurality of grid electrodes that form an electron beam irradiated toward the target, and an insulating support member that electrically insulates and supports at least two of the plurality of grid electrodes; An electron gun having an X-ray generating tube,
The plurality of grid electrodes define an electron passage through which the electrons emitted from the electron emission section pass,
An X-ray generating tube characterized in that the electron gun has a conductive portion that blocks the insulating support member from being directly viewed from the electron passage path.

the grid electrode is electrically connected to a voltage source;
The X-ray generating tube according to claim 17, wherein the conductive part is a part of the grid electrode.

The grid electrode includes an annular portion provided with an electron passage hole defining the electron passage and extending in the tube diameter direction, and a tubular portion connected to the annular portion and extending along the electron passage. have,
The X-ray generating tube according to claim 17 or 18, wherein the conductive part is at least a part of the tubular part.

The grid electrode is characterized in that it includes an extraction grid electrode in which the annular part is arranged to face the electron emitting part and the tubular part is arranged to overlap with the electron emitting part in the tube axis direction. The X-ray generating tube according to claim 19.

The plurality of grid electrodes include at least one pair of grid electrodes, the annular portions of which are opposite to each other in the axial direction of the tube, and the tubular portions of each of which are opposite to each other in the radial direction of the tube. 21. The X-ray generating tube according to 19 or 20.

In the pair of grid electrodes, the tubular portion of the grid electrode in which the annular portion is located on the side closer to the electron emitting portion is the tubular portion of the grid electrode in which the annular portion is located on the side farther from the electron emitting portion. 22. The X-ray generating tube according to claim 21, wherein the X-ray generating tube is located on the outer side of the tube in the tube radial direction.

The plurality of grid electrodes include a focusing grid electrode having an annular portion facing the target and defining the size of a focal point formed on the target,
X according to any one of claims 17 to 22, characterized in that the electron passage corresponds to a passage of the electrons emitted from the electron emitting section until they pass through the focusing grid electrode. line generator tube.

The electron gun has an outer circumferential tubular portion on the outer side of the insulating support member in the tube diameter direction so that the insulating support member is not seen directly when viewed from the outside in the tube diameter direction, and the conductive portion is connected to the outer circumferential tubular portion. The X-ray generating tube according to any one of claims 17 to 23, characterized in that the tube is a portion.

The X-ray generating tube according to claim 24, wherein the outer circumferential tubular portion is a part of the grid electrode.

The X-ray generating tube is
an anode member connected to the target and included in the anode together with the target;
a cathode member connected to the electron gun and included in the cathode together with the electron emission source;
X according to any one of claims 17 to 25, characterized in that one end and the other end in the tube axis direction have an insulating tube connected to the anode member and the cathode member, respectively. line generator tube.

The X-ray generating tube is
an anode member connected to the target and included in the anode together with the target;
a cathode member connected to the electron gun and included in the cathode together with the electron emission source;
an insulating tube having one end and the other end in the tube axis direction connected to the anode member and the cathode member, respectively,
The X-ray generating tube according to claim 24 or 25, wherein the outer peripheral tubular portion is fixed to the cathode member.

The conductive portion is located between the electron passageway and the insulating support member so as to suppress scattering metal particles moving from the electron passageway side from being deposited on the insulating support member. The X-ray generating tube according to any one of claims 17 to 27.

29. The target is a transmission type target having a target layer that generates X-rays when irradiated with electrons, and a support substrate that supports the target layer and transmits the X-rays. The X-ray generating tube according to any one of the above.

The X-ray generating tube according to any one of claims 17 to 29 is electrically connected to each of the target and the electron emitting section, and is applied between the target and the electron emitting section. An X-ray generator comprising: a drive circuit that outputs a tube voltage.

The X-ray generator according to claim 30;
an X-ray detection device that detects the X-rays emitted from the X-ray generation device and transmitted through the subject;
a system control device that cooperatively controls the X-ray generator and the X-ray detector;
An X-ray imaging system comprising: