X-ray pipe and x-ray inspection device

Abstract

To provide an X-ray pipe which can expand a radiation range of an X-ray, and to provide an X-ray inspection device.SOLUTION: An X-ray pipe includes: a center package having an opening on a side surface and housing an anode and a cathode; a window frame joined to the outer side of the opening of the center package and having a window frame opening at the opposite side of the opening; and a window plate ring which is joined to the window frame and to which an X-ray transmission window is joined. The window frame opening is larger than the opening.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an X-ray tube and an X-ray inspection apparatus using the same, and more particularly to a technique for widening the X-ray irradiation angle of the X-ray tube. [Background technology]

[0002] X-ray tubes are used in a wide range of fields, including non-destructive testing and medicine. In the field of non-destructive testing, X-ray tubes are installed in X-ray inspection equipment used to inspect food for foreign objects.

[0003] In food foreign body inspection, the inspection target is transported on a conveyor belt or the like, so the X-ray inspection equipment uses a line sensor positioned perpendicular to the transport direction, meaning that only X-rays perpendicular to the tube axis are used.

[0004] For example, the X-ray tube used in the X-ray inspection apparatus disclosed in Patent Document 1 includes a vacuum envelope, a cathode, an anode having a target surface, and an X-ray transmission assembly. In this X-ray tube, the X-ray transmission assembly includes a first bonding member, a window frame, an X-ray transmission window made of beryllium, and a second bonding member connecting the first bonding member and the window frame. To prevent relative positional deviation between the target surface and the X-ray transmission window, the second bonding member is made more flexible than the first bonding member and the window frame. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-087727 Summary of the Invention [Problem to be solved by the invention]

[0006] In non-destructive inspections such as food foreign substance inspections, the installation space within facilities is limited, so there is a demand for miniaturization of X-ray inspection devices and X-ray sources including X-ray tubes. Therefore, it is desirable to expand the irradiation range of the X-rays from the X-ray tube, but with the structure of Patent Document 1, it is difficult to expand the irradiation range.

[0007] The present invention has been made in view of the above circumstances, and has an object to provide an X-ray tube and an X-ray inspection apparatus that can widen the irradiation range of X-rays. [Means for solving the problem]

[0008] The X-ray tube of the first embodiment includes a center envelope having an opening on a side thereof and accommodating an anode and a cathode, a window frame joined to the outside of the opening of the center envelope, the window frame having a window frame opening on the opposite side to the opening, and a window plate ring joined to the window frame, the window plate ring having an X-ray transmissive window joined thereto, the window frame opening being larger than the opening.

[0009] In the X-ray tube of the second embodiment, the X-ray focal point of the anode is offset to the X-ray transmission window side in the first embodiment.

[0010] The X-ray tube of the third aspect is the X-ray tube of the first or second aspect, wherein a flange portion having a flange opening is attached to a window frame.

[0011] The X-ray tube of the fourth embodiment is the X-ray tube of the third embodiment, wherein the flange opening is larger than the window frame opening.

[0012] The X-ray tube of the fifth aspect is the X-ray tube of the third or fourth aspect, in which the window frame and the flange portion are integrally formed.

[0013] The X-ray tube of a sixth aspect is any one of the first to fifth aspects, wherein the window frame is joined to the outer periphery of the opening of the center envelope, and the window plate ring is joined to the inner periphery of the window frame.

[0014] The X-ray tube of a seventh aspect is any one of the first to sixth aspects, in which the X-ray irradiation angle is 60° or more.

[0015] In the X-ray tube of the eighth aspect, in any one of the first to seventh aspects, the joint position between the center envelope and the window frame, the joint position between the X-ray transparent window and the window plate ring, and the joint position between the window frame and the window plate ring are arranged in this order, and are spaced further away from the opening.

[0016] The X-ray inspection apparatus of the ninth aspect is an X-ray inspection apparatus that inspects an item being inspected by irradiating the item being transported with X-rays and detecting the X-rays that pass through the item being inspected, and includes an X-ray generating source having an X-ray tube of any one of the first to eighth aspects, and an X-ray detector arranged opposite the X-ray generating source with respect to the item being inspected.

[0017] The X-ray inspection apparatus of a tenth aspect is the ninth aspect, wherein the X-ray detector is configured with a line sensor that is arranged in a direction intersecting the tube axis of the X-ray tube. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide an X-ray tube and an X-ray inspection device that can widen the irradiation range of X-rays. [Brief explanation of the drawings]

[0019] [Figure 1] Figure 1 is a conceptual diagram of an X-ray inspection device. [Figure 2] FIG. 2 is a cross-sectional view of an X-ray tube. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a partially enlarged view of the X-ray tube of FIG. [Figure 5] FIG. 5 is a schematic diagram of the X-ray inspection device. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, the same reference numerals are assigned to the same components, and redundant descriptions are omitted. Further, when a plurality of components are exemplified in the following embodiments, it can be interpreted as including at least one of the plurality of components. Hereinafter, preferred embodiments of the X-ray tube and the X-ray inspection apparatus of the present invention will be described.

[0021] FIG. 1 is a conceptual diagram of an X-ray inspection apparatus 1. The X-ray inspection apparatus 1 includes a belt conveyor 2 for conveying an inspection object W, and a detection device 3. The detection device 3 has an X-ray source 4 that irradiates the inspection object W with X-rays, and an X-ray detector 5 that detects X-rays. The X-ray source 4 and the X-ray detector 5 are arranged to face each other on opposite sides with respect to the belt conveyor 2 (or the inspection object W). In this example, the X-ray source 4 is arranged above the belt conveyor 2 and separated by a predetermined distance L. The X-ray detector 5 is arranged below the belt conveyor 2.

[0022] The X-ray source 4 has an X-ray tube 6, and the X-ray tube 6 has a filament 7 on the cathode side and a target 8 on the anode side. The X-ray tube 6 irradiates an electron beam from the filament 7 onto the target 8 to generate X-rays. The X-ray tube 6 is immersed in insulating oil inside the housing that constitutes the X-ray source 4.

[0023] In the detection device 3, the inspection object W conveyed by the belt conveyor 2 is irradiated with X-rays from the X-ray tube 6, and the X-rays transmitted through the inspection object W are detected by the X-ray detector 5. In the X-ray inspection apparatus 1, in order to inspect the conveyed inspection object W, a line sensor arranged at a position orthogonal to the tube axis A (or the conveying direction) of the X-ray tube 6 is applied as the X-ray detector 5.

[0024] By increasing the irradiation angle θ of the X-rays irradiated from the X-ray tube 6, the distance L from the inspection object W can be reduced, and the detection device 3 can be miniaturized. Also, the X-ray source 4 can be miniaturized. As a result, the X-ray inspection apparatus 1 can be miniaturized.

[0025] <X-ray tube> Next, the structure of the X-ray tube 10 according to the embodiment will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a cross-sectional view of the X-ray tube. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Fig. 4 is a partially enlarged view of the X-ray tube in Fig. 2.

[0026] As shown in FIG. 2, the X-ray tube 10 is composed of a cathode 12 that generates an electron beam 22, an anode 14 equipped with a target 26 that generates X-rays 38 when struck by the electron beam 22 from the cathode 12, and an envelope 16 that supports and insulates the cathode 12 and anode 14 so that they face each other and enclose them in a vacuum-tight manner.

[0027] The cathode 12 is composed of a filament 18 that emits thermoelectrons, a focusing electrode 20 that focuses the thermoelectrons to form a thin beam-like electron beam 22 directed toward the target 26 of the anode 14, a focusing electrode support 21 that supports the focusing electrode 20, and a stem 24 that insulates and supports the focusing electrode support 21. The filament 18 is made of tungsten wire or the like wound in a coil shape. The filament 18 is supported within a focusing groove 20A of the focusing electrode 20. The filament 18 is electrically insulated from the support within the focusing groove 20A.

[0028] The focusing electrode 20 is made of a metal material such as iron or stainless steel. The focusing electrode 20 is disposed opposite the target 26 of the anode 14, and has a focusing groove 20A for attaching the filament 18 on the side facing the target 26. The shape and dimensions of the focusing groove 20A are configured so that a focusing electric field is created to focus the thermoelectrons emitted from the filament 18 when a high voltage is applied between the cathode 12 and the anode 14.

[0029] The longitudinal center position of the focusing groove 20A is offset toward the beryllium plate 36 that constitutes the X-ray transmission window with respect to the tube axis A of the X-ray tube 10. As a result, the electron beam 22 emitted from the filament 18 travels at a position offset from the tube axis A. The electron beam 22 collides with the beryllium plate 36 on the target 26 of the anode 14 at a position closer to the beryllium plate 36 that is offset from the tube axis A, and an X-ray focal point 40 is formed.

[0030] The focusing electrode support 21 is usually cylindrical and made of a metal material such as stainless steel. The stem 24 is mainly made of an insulating material such as heat-resistant glass. The stem 24 is roughly cylindrical and has a cylindrical portion that connects to the focusing electrode support 21 and a flared portion that connects to the end of the envelope 16. The stem 24 has a lead wire encapsulation portion inside the cylindrical portion in which multiple lead pins 25 are vacuum-tightly encapsulated. The lead pins 25 are connected to the filament 18 and focusing electrode 20 and are used to supply filament heating voltage and cathode potential. They are also used to support the focusing electrode support 21.

[0031] The anode 14 is composed of a target 26 and an anode base material 28 in which the target 26 is embedded. The target 26 is made of a high-electron-number, high-melting-point metal material such as tungsten or an alloy thereof, and is a rectangular or circular plate. The anode base material 28 is made of a metal material with high thermal conductivity such as copper, and is a roughly cylindrical rod. The surface of the anode base material 28 facing the cathode 12 includes a surface perpendicular to the tube axis A and an inclined surface (hereinafter referred to as the inclined surface) 15. The target 26 is embedded in the inclined surface 15. A radiator 29 is connected to the end of the anode base material 28 opposite the inclined surface 15. The radiator 29 is made of a material with excellent thermal conductivity and voltage resistance. The radiator 29 can promote heat transfer to the outside of the X-ray tube 10.

[0032] The envelope 16 is composed of a metal center envelope 30, an insulating cathode envelope 32 made of glass or the like, and an insulating anode envelope 33 made of glass or the like. The center envelope 30 has a roughly cylindrical shape. The center envelope 30 houses the focusing electrode 20 of the cathode 12 and the target 26 of the anode 14. In other words, the center envelope 30 houses parts of the cathode 12 and the anode 14. The center envelope 30 is arranged parallel to the tube axis A.

[0033] The center envelope 30 is made of stainless steel, copper, or the like, and one end of the cathode envelope 32 and one end of the anode envelope 33 are connected to both ends of the center envelope 30. The cathode envelope 32 and the anode envelope 33 are roughly cylindrical and made of an insulator such as heat-resistant glass. Thin-walled cylinders 30A and 30B made of a metal material such as Kovar that is thermally compatible with the insulator are inserted between the center envelope 30 and the cathode envelope 32 and anode envelope 33. Because the center envelope 30 is made of metal, it can achieve a long life.

[0034] The other end of the cathode envelope 32 is joined to the flared portion of the stem 24 of the cathode 12. The other end of the anode envelope 33 is joined to the base of the anode base material 28 of the anode 14 via a metallic cylinder 28A. This cylinder 28A is made of a metal material such as Kovar that is thermally compatible with the insulator of the envelope 16. The center envelope 30 and the cylinders 30A, 30B, and the anode base material 28 and the cylinder 28A are joined by brazing, for example.

[0035] An opening 50 is formed on one side of the center envelope 30. The opening 50 is formed in a position close to the target 26 and facing the X-ray focal point 40. X-rays from the target 26 are irradiated onto the inspection item W through the opening 50. The opening 50 is defined by a boss portion 52 that protrudes from the side of the center envelope 30 in the direction of X-ray irradiation. The boss portion 52 is, for example, cylindrical in shape.

[0036] A window frame 60 is bonded to the outer periphery of the opening 50. A window plate ring 70 is bonded to the inner periphery of the window frame 60. A beryllium plate 36 constituting the X-ray transmissive window is bonded to the inner periphery of the window plate ring 70. A flange portion 80 is bonded to the window frame 60. The flange portion 80 has a flat surface 80A on the side opposite to the side bonded to the window frame 60. The flat surface 80A is used for fixing the X-ray tube 10 to the X-ray generation source 4, etc. A flange opening 80B is defined by the flat surface 80A.

[0037] However, X-rays may be attenuated or beam hardened due to the blocking of low-energy X-rays, resulting in a radiation quality that does not provide contrast for foreign body inspection. For this reason, an X-ray transmission window is required that contains low-energy soft X-rays, and a beryllium plate 36 with high X-ray transmittance is desirable as the shielding material.

[0038] Next, the window structure of the embodiment will be described with reference to FIG.

[0039] 4, an opening 50 is defined by a boss portion 52 on the side surface of the center envelope 30. The boss portion 52 protrudes from the surface of the center envelope 30 in the direction of X-ray irradiation.

[0040] The window frame 60 has a first joint portion 60A that is generally J-shaped (or generally U-shaped) in cross section and a second joint portion 60B that is generally trapezoidal in cross section. A first opening 60C is defined by the first joint portion 60A. The first opening 60C is larger than the opening 50, and the boss portion 52 is inserted into the first opening 60C.

[0041] On the outer peripheral surface of the window frame 60, the second joint portion 60B has a tapered surface that increases in diameter in the direction away from the first opening 60C as it moves away from the first joint portion 60A in a cross-sectional view. On the inner peripheral surface of the window frame 60, the inner surface of the first joint portion 60A (the side opposite the side defining the first opening 60C) and the inner surface of the second joint portion 60B are connected in a substantially straight line. A protrusion 60D is provided on the inner surface of the second joint portion 60B. This protrusion 60D defines the second opening 60E.

[0042] The inner surface of the second joint portion 60B extends linearly from the protrusion 60D outward (on the radially away side of the opening 50) and connects to a flat surface 60F. This flat surface 60F defines a third opening 60G. The first opening 60C, the second opening 60E, and the third opening 60G of the window frame 60 are larger than the opening 50, and the sizes increase in this order. As a result, the window frame 60 does not obstruct the emission of X-rays from the opening 50. The first opening 60C, the second opening 60E, and the third opening 60G are examples of window frame openings of the present invention. In other words, all openings formed in the window frame 60 are larger than the opening 50 of the center envelope 30.

[0043] The end of the boss portion 52 and the end of the first joint portion 60A are joined by, for example, welding. This position value constitutes the joint position P1.

[0044] The window plate ring 70 has a cylindrical shape, and the outer diameter of the window plate ring 70 is smaller than the inner diameter of the window frame 60 (the inner surface formed by the first joint portion 60A and the second joint portion 60B). The window plate ring 70 is housed on the inner circumferential side of the window frame 60.

[0045] The window plate ring 70 has a main body portion 70A, a support portion 70B, and a protrusion portion 70C. The support portion 70B is provided at the end of the main body portion 70A on the opening 50 side and extends inward from the main body portion 70A. The main body portion 70A and the support portion 70B form a generally L-shape. The protrusion portion 70C is provided at the end of the main body portion 70A opposite the support portion 70B and protrudes in a direction away from the opening 50. The protrusion portion 70C is located opposite the protrusion portion 60D of the window frame 60. The ends of the protrusion portion 70C and the protrusion portion 60D are generally flush with each other. The support portion 70B supports the beryllium plate 36. The beryllium plate 36 and the window plate ring 70 are joined together by, for example, brazing. This position value constitutes the joining position P2.

[0046] In this example, an irradiation angle of 60 degrees or more is achieved by joining the window frame 60 to the outer periphery of the center envelope 30 and the beryllium plate 36 to the inner periphery of the window frame 60. In this structure, the distance between the ends of the opposing support members 70B is greater than the opening 50 and the first opening 60C. In addition, the beryllium plate 36 supported by the support members 70B is also greater than the opening 50 and the first opening 60C. The window plate ring 70 does not obstruct the irradiation of X-rays from the opening 50.

[0047] The protruding portion 70C of the window plate ring 70 and the protruding portion 60D of the window frame 60 are joined by, for example, welding. This position value constitutes the joining position P3.

[0048] The joining position P1 between the window frame 60 and the center envelope 30, the joining position P2 between the beryllium plate 36 and the window plate ring 70, and the joining position P3 between the window frame 60 and the window plate ring 70 are located in this order, in order of increasing distance from the opening 50. By arranging them in this order, the window frame 60 and the window plate ring 70 do not obstruct the X-ray irradiation from the opening 50. A wide X-ray irradiation angle can be achieved without making the opening 50 larger than the center envelope 30. Furthermore, as described above, the X-ray focal point 40 is offset toward the beryllium plate 36, making it possible to achieve a wide X-ray irradiation angle.

[0049] The outer peripheral surface of the flange portion 80 expands in diameter in a direction away from the opening 50 in a cross-sectional view. The inner peripheral surface of the flange portion 80 has an abutment portion 80C that extends inward. The abutment portion 80C has a flat plate shape with parallel upper and lower surfaces. The lower surface of the abutment portion 80C and the flat surface 60F of the window frame 60 are joined.

[0050] The inner peripheral surface of the flange portion 80 extends linearly above the abutment portion 80C and has a tapered surface that expands in diameter toward the flange opening 80B. The flange opening 80B is larger than the third opening 60G (the largest opening in the window frame 60) of the window frame 60. Even when the flange portion 80 is provided, a wide X-ray irradiation angle can be achieved. The flange portion 80 and the window frame 60 may be configured as one unit.

[0051] In FIG. 4, the directions of “up” and “down” are described such that the direction away from the opening 50 is up and the direction approaching the opening 50 is down.

[0052] <X-ray inspection apparatus> Next, an X-ray inspection apparatus 1 including the X-ray tube 10 of the embodiment will be described. The X-ray inspection apparatus 1 includes a housing 90 and an operation unit 91 provided on the outer surface of the housing 90. Inside the housing 90, a detection device 3 including a belt conveyor 2, an X-ray source 4, and an X-ray detector 5, and a control device 92 are arranged. The X-ray source 4 includes the X-ray tube 10 of the embodiment. The X-ray inspection apparatus 1 inspects (for example, checks for foreign matter) the inspected item W while transporting it. The housing 90 has a loading port (not shown) at a downstream position in the transport direction of the inspected item W by the belt conveyor 2, and has an unloading port (not shown) at a downstream position in the transport direction. The X-ray detector 5 is a line sensor extending in a direction intersecting the tube axis A, specifically, in a perpendicular direction.

[0053] The operation unit 91 is, for example, configured by a touch panel, and receives input and displays information. A user can input inspection conditions from the operation unit 91. Also, the user can confirm various information such as inspection results from the operation unit 91.

[0054] The control device 92 controls the overall operation of the X-ray inspection apparatus 1. The control device 92 is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a storage device, etc. The control device 92 operates the X-ray inspection apparatus 1 according to the conditions input from the operation unit 91. The control device 92 generates an X-ray image based on the detection signal from the X-ray detector 5 and displays it on the operation unit 91. The control device 92 determines the presence or absence of foreign matter from the X-ray image.

[0055] By including the X-ray tube 10, the X-ray source 4 can be miniaturized. Also, by including the X-ray tube 10, the X-ray source 4 can be brought closer to the inspected item W, and the entire X-ray inspection apparatus 1 can be miniaturized.

[0056] Furthermore, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications are possible. [Explanation of symbols]

[0057] 1 X-ray inspection equipment 10 X-ray tube 12 Cathode 14 Anode 30 Center Enclosure 36 Beryllium Plate 50 Opening 60 Window Frame 60G 3rd opening 70 Window Plate Ring 80 flange 80B flange opening A tube shaft θ Irradiation angle

Claims

1. a center envelope having an opening on a side surface and accommodating an anode and a cathode; a window frame joined to the outside of the opening of the center envelope, the window frame having a window frame opening on the opposite side to the opening; a window plate ring joined to the window frame, the window plate ring having an X-ray transmissive window joined thereto; The window frame opening is larger than the opening.

2. 2. The X-ray tube of claim 1, wherein the X-ray focal point of the anode is offset to a side of the X-ray transmissive window.

3. 3. The X-ray tube of claim 1, wherein a flange portion having a flange opening is attached to the window frame.

4. 4. The x-ray tube of claim 3, wherein the flange opening is larger than the window frame opening.

5. 4. The X-ray tube according to claim 3, wherein the window frame and the flange portion are integrally formed.

6. 3. The X-ray tube according to claim 1, wherein the window frame is joined to an outer periphery of the opening of the center envelope, and the window plate ring is joined to an inner periphery of the window frame.

7. 3. The X-ray tube according to claim 1, wherein the X-ray irradiation angle is 60 degrees or more.

8. 3. The X-ray tube according to claim 1, wherein a joint position between the center envelope and the window frame, a joint position between the X-ray transmissive window and the window plate ring, and a joint position between the window frame and the window plate ring are arranged in this order, and are spaced apart from the opening.

9. An X-ray inspection apparatus that inspects an inspection target product by irradiating the inspection target product with X-rays and detecting X-rays that pass through the inspection target product, 3. An X-ray inspection apparatus comprising: an X-ray generation source having the X-ray tube according to claim 1; and an X-ray detector disposed opposite the X-ray generation source across the inspected product.

10. 10. The X-ray inspection apparatus according to claim 9, wherein the X-ray detector is configured by a line sensor arranged in a direction intersecting a tube axis of the X-ray tube.

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