X-ray tube manufacturing method and X-ray imaging device

Abstract

To provide a manufacturing method of an X-ray tube capable of suppressing an influence of a distortion aberration generated on a target by an electron beam ejected from an electron discharge part.SOLUTION: A manufacturing method of an X-ray tube 1 comprises the steps of: acquiring a correction arrangement pattern in which an electrode discharge part is arranged so as to correct a distortion aberration on the basis of a shape of the distortion aberration generated on the target in the X-ray tube including a plurality of electron discharge parts 12 that are arranged in an array like in an arrangement region 36 on a substrate 31 and irradiate an electron beam 9, and a lens 14 that is arranged between the electron discharge part and the target 11 and is constructed so as to focus the electron beam so that an imaging point I where an outer shape T of the whole of the plurality of electron discharge parts is imaged onto the target; and forming the electron discharge part onto the substrate on the basis of the acquired correction arrangement pattern.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an X-ray tube and an X-ray imaging device, and more particularly to a method for manufacturing an X-ray tube including an electron-emitting portion and an X-ray imaging device. [Background technology]

[0002] BACKGROUND ART Conventionally, an X-ray tube including an electron emitting portion is known (see, for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses an X-ray tube equipped with a cathode that emits electron beams. X-rays are generated when the electron beams emitted from the cathode collide with a target. The above-mentioned Patent Document 1 discloses a Spindt-type cold cathode (Spindt-type field emission electron source) as the cathode. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-256441 Summary of the Invention [Problem to be solved by the invention]

[0005] Although not disclosed in Patent Document 1, field emission electron sources have a large angular spread of electron beams generated from the electron source. Furthermore, while field emission electron sources can generate electron beams with a much higher current density than thermoelectron emission electron sources, the amount of current obtainable from a single field emission electron source is limited. Therefore, in the case of field emission electron sources, a certain number of field emission electron sources are arranged in parallel to increase the emission area of ​​the electron beams from the field emission electron sources. Although not disclosed in Patent Document 1, by employing a back-focus optical system for focusing the electron beams, it is possible to focus the electron beams to a single point on the target even when the emission area of ​​the electron source is large. In this specification, the back-focus optical system is an optical system configured to focus the electron beams so that the position of the back focus of the lens coincides with the position of the surface of the target on which the electron beams impinge. However, while the back-focus optical system can focus the electron beams to a single point on the target even when the emission area of ​​the electron source is large, it is unable to focus electron beams with a large angular spread using a lens. As described above, the field emission electron source has a large angular spread of the electron beam, and therefore blurring may occur on the target in accordance with the angular spread of the electron beam.

[0006] The aforementioned Patent Document 1 discloses a Spindt-type field emission electron source fabricated by forming an emitter and an insulating layer using a sputtering deposition method and a lithography method. Although not disclosed in the aforementioned Patent Document 1, the Spindt-type field emission electron source allows multiple field emission electron sources to be arranged in a small area. Therefore, an imaging optical system for focusing electron beams with a large angular spread can be employed without employing a back-focus optical system for focusing electron beams emitted from a large emission area. In this specification, the imaging optical system refers to an optical system configured to focus the angular spread of electron beams emitted from the electron source using a lens and to focus the electron beams so as to form an image point on a target at which the overall outer shape of the multiple field emission electron sources is imaged. This allows electron beams with a large angular spread emitted from the electron source to be focused. Furthermore, the imaging optical system allows a real focal shape, in which the overall outer shape of the multiple field emission electron sources is approximately reduced and projected onto the target.

[0007] However, even when an imaging optical system that focuses an electron beam with a large angular spread emitted from an electron source is used, distortion may occur at the real focal point formed on the target by the emitted electron beam. As a result, distortion due to the distortion may occur in the acquired X-ray image. Therefore, it is desirable to suppress the influence of distortion that occurs on the target due to the electron beam emitted from the electron source (electron emitter).

[0008] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a method for manufacturing an X-ray tube and an X-ray imaging device that are capable of suppressing the influence of distortion aberration that occurs on a target due to an electron beam emitted from an electron emitter. [Means for solving the problem]

[0009] A method for manufacturing an X-ray tube in a first aspect of the present invention includes the steps of: obtaining a corrective arrangement pattern in which the electron emitters are arranged so as to correct distortion aberration, based on the shape of distortion aberration occurring on the target, for an X-ray tube including a plurality of electron emitters arranged in an array in an arrangement area on a substrate and irradiating electron beams; and a lens arranged between the electron emitters and a target and configured to focus the electron beam so as to form an imaging point on the target at which the overall external shape of the plurality of electron emitters is imaged; and forming the electron emitters on the substrate based on the obtained corrective arrangement pattern.

[0010] An X-ray imaging apparatus according to a second aspect of the present invention comprises an X-ray tube including a plurality of electron emitters arranged in an array in an arrangement area on a substrate and emitting electron beams, and a lens arranged between the electron emitters and a target and configured to focus the electron beams so as to form an imaging point on the target at which the overall external shape of the plurality of electron emitters is imaged, a detector for detecting X-rays emitted from the X-ray tube, and a detector vessel an image processing unit that generates an image based on a detection signal output from the X-ray tube; and an arrangement pattern of the electron emitting units in an arrangement area on the substrate of the X-ray tube is Based on the shape of the distortion that occurs on the target, The electron-emitting portions are arranged in a corrective arrangement pattern so as to correct distortion occurring on the target. In addition, an X-ray imaging device in a third aspect of the present invention comprises an X-ray tube including a plurality of electron emitters arranged in an array in an arrangement area on a substrate and emitting electron beams, and a lens arranged between the electron emitters and a target and configured to focus the electron beams so as to form an image point on the target at which the outer shape of the entire plurality of electron emitters is imaged; a detector that detects X-rays emitted from the X-ray tube; and an image processing unit that generates an image based on a detection signal output from the detector, wherein the arrangement pattern of the electron emitters in the arrangement area on the substrate of the X-ray tube is configured to be a corrective arrangement pattern in which the electron emitters are arranged so as to correct distortion aberration occurring on the target, and when the shape of the distortion aberration occurring on the target is a pincushion shape, the corrective arrangement pattern is configured to be a first corrective arrangement pattern in which no electron emitters are arranged at least in the four corners of the rectangular arrangement area. In addition, an X-ray imaging device in a fourth aspect of the present invention comprises an X-ray tube including a plurality of electron emitters arranged in an array in an arrangement area on a substrate and emitting electron beams, and a lens arranged between the electron emitters and a target and configured to focus the electron beams so as to form an imaging point on the target at which the outer shape of the entire plurality of electron emitters is imaged; a detector that detects X-rays emitted from the X-ray tube; and an image processing unit that generates an image based on a detection signal output from the detector, wherein the arrangement pattern of the electron emitters in the arrangement area on the substrate of the X-ray tube is configured to be a corrective arrangement pattern in which the electron emitters are arranged so as to correct distortion aberration occurring on the target, and when the shape of the distortion aberration occurring on the target is barrel-shaped, the corrective arrangement pattern is configured to be a second corrective arrangement pattern in which no electron emitters are arranged at least in the center of each of the four sides of the rectangular arrangement area. [Effects of the Invention]

[0011] A method for manufacturing an X-ray tube according to a first aspect of the present invention includes, as described above, a step of acquiring a corrective arrangement pattern in which electron emitters are arranged so as to correct distortion, based on the shape of distortion occurring on the target, in an X-ray tube including a lens configured to focus an electron beam so as to form an imaging point on the target where the overall outer shape of a plurality of electron emitters is imaged. The lens configured as described above allows a real focal shape to be obtained, in which the overall outer shape (planar shape) of a plurality of electron emitters is approximately reduced and projected onto the target. In other words, the real focal shape formed on the target can be adjusted by adjusting the overall outer shape of the electron emitters. Therefore, by correcting the arrangement pattern of a plurality of electron emitters on a substrate based on the shape of distortion occurring, a corrective arrangement pattern can be acquired in advance that can approximate a desired real focal shape on the target with reduced distortion. This allows the electron emitters to be arranged based on the acquired corrective arrangement pattern. Therefore, the influence of distortion occurring on the target due to the electron beams emitted from the electron emitters can be suppressed.

[0012] In a second aspect of the present invention, the X-ray imaging apparatus includes an X-ray tube including a lens configured to focus electron beams so as to form an image point on the target where the overall outer shape of a plurality of electron emitters is imaged, and the arrangement pattern of the electron emitters in the arrangement area on the substrate of the X-ray tube is configured as a corrective arrangement pattern in which the electron emitters are arranged so as to correct distortion occurring on the target. The lens configured as described above allows a real focal shape to be obtained on the target, in which the overall outer shape (planar shape) of the plurality of electron emitters is approximately reduced and projected. In other words, the real focal shape formed on the target can be adjusted by adjusting the overall outer shape of the electron emitters. Therefore, by correcting the arrangement pattern of the plurality of electron emitters on the substrate based on the shape of the distortion occurring, a corrective arrangement pattern can be obtained in advance that can approximate a desired real focal shape on the target with reduced distortion. This allows the arrangement of the electron emitters to be the corrective arrangement pattern. Therefore, the influence of distortion occurring on the target due to the electron beams emitted from the electron emitters can be suppressed. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing the overall configuration of an X-ray imaging apparatus according to an embodiment. [Figure 2] 1 is a schematic diagram illustrating a configuration of an X-ray tube according to an embodiment. [Figure 3] 10A and 10B are diagrams illustrating an example of pincushion distortion and an example of a first correction arrangement pattern. [Figure 4] 10A and 10B are diagrams illustrating an example of barrel distortion and an example of a second correction arrangement pattern. [Figure 5] 3A and 3B are schematic diagrams for explaining the configuration of a field emission electron source included in an electron emission portion. [Figure 6] FIG. 2 is a schematic diagram for explaining an imaging optical system. [Figure 7] FIG. 2 is a schematic diagram for explaining a back-focus optical system. [Figure 8] FIG. 2 is a schematic diagram showing a substantially rectangular real focal shape. [Figure 9] 10 is a flowchart illustrating a method for manufacturing an X-ray tube. [Figure 10] FIG. 10 is a diagram showing an example of a first correction arrangement pattern according to a modified example. [Figure 11] FIG. 10 is a diagram showing an example of a second correction arrangement pattern according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0015] (Overall configuration of X-ray imaging device 100) First, with reference to FIG. 1, the overall configuration of an X-ray imaging apparatus 100 according to an embodiment will be described.

[0016] 1, an X-ray imaging apparatus 100 is an apparatus that captures an X-ray CT image of a subject 90. The X-ray imaging apparatus 100 of this embodiment is used, for example, for non-destructive testing. The subject 90 is a sample to be inspected.

[0017] The X-ray imaging apparatus 100 includes an X-ray tube 1, a detector 2, a subject placement unit 3, a rotation mechanism 4, an image processing unit 5, and an imaging control unit 6.

[0018] The X-ray tube 1 is configured to irradiate X-rays 10 onto a subject 90 placed on a subject placement unit 3. The X-ray tube 1 is configured to generate X-rays 10 when a high voltage is applied to it. The X-ray tube 1 faces the detector 2 via the subject placement unit 3. In this embodiment, the X-ray tube 1, the subject placement unit 3, and the detector 2 are arranged side by side in the horizontal direction. Details of the X-ray tube 1 will be described later.

[0019] The detector 2 is configured to detect X-rays 10 emitted from the X-ray tube 1. The X-rays 10 emitted from the X-ray tube 1 pass through the subject 90 and are incident on the detection surface of the detector 2. The detector 2 is configured to convert the detected X-rays 10 into an electrical signal. This allows an X-ray image to be obtained that reflects the transmission of the X-rays 10 through the subject 90. The detector 2 is, for example, an FPD (Flat Panel Detector). The detector 2 is configured with a plurality of conversion elements (not shown) and pixel electrodes (not shown) arranged on the plurality of conversion elements. The plurality of conversion elements and pixel electrodes are arranged in a matrix on the detection surface at a predetermined period (pixel pitch). A detection signal (image signal) from the detector 2 is sent to an image processing unit 5.

[0020] The subject placement unit 3 is disposed between the X-ray tube 1 and the detector 2, and is configured to support the subject 90. In this embodiment, the subject placement unit 3 is configured by a subject stage on which the subject 90 is placed.

[0021] The rotation mechanism 4 rotates the X-ray tube 1 and the detector 2 relative to the subject placement unit 3. In this way, the rotation mechanism 4 is configured to change the imaging angle of the subject 90.

[0022] The image processing unit 5 is provided in a control device 20. The control device 20 is configured by, for example, a PC (personal computer). The control device 20 includes a main control unit 21, the image processing unit 5, a storage unit 22, and an input / output unit 23. The control device 20 is connected to a display device 24 and an input device 25.

[0023] The main control unit 21 is composed of, for example, a processor such as a CPU (Central Processing Unit) or a circuit, and executes application programs stored in the memory unit 22 to set the imaging conditions in the X-ray imaging device 100 and control the start and stop of imaging.

[0024] The image processing unit 5 is configured by a processor such as a GPU (Graphics Processing Unit) or an FPGA (Field-Programmable Gate Array) configured for image processing.

[0025] The image processing unit 5 acquires a plurality of projection image data at each of a plurality of imaging angles from the detector 2. The image processing unit 5 is configured to generate a CT image based on the acquired plurality of projection image data. The image processing unit 5 generates the CT image by executing reconstruction processing on a set of a plurality of projection image data for each imaging angle of 360 degrees. A CT image is an image that reflects the three-dimensional structure of the subject 90, and is reconstructed by arithmetic processing from a plurality of X-ray images (projection image data) captured at various imaging angles. The CT image may be in the form of a tomographic image of the subject 90, a three-dimensional stereoscopic image, or the like.

[0026] The storage unit 22 includes a volatile storage device and a non-volatile storage device. The storage unit 22 stores programs, various setting information related to CT imaging by the X-ray imaging device 100, and the like. The storage unit 22 stores a plurality of acquired projection image data and CT images generated based on the projection image data.

[0027] The input / output unit 23 is composed of various interfaces for inputting and outputting signals to and from the control device 20. The input / output unit 23 is connected to a display device 24 and an input device 25. The display device 24 is, for example, a liquid crystal display device 24. The input device 25 includes a keyboard, a mouse, and the like. The image processing unit 5 acquires a detection signal (image signal) from the detector 2 via the input / output unit 23. The main control unit 21 transmits instructions to start or stop imaging to the imaging control unit 6 via the input / output unit 23.

[0028] The imaging control unit 6 controls the operation of the X-ray tube 1. The imaging control unit 6 also controls the operation of the rotation mechanism 4. The imaging control unit 6 is made up of a control device for the X-ray tube 1, a control device for the rotation mechanism 4, etc.

[0029] (Configuration of X-ray tube 1) 2, in this embodiment, the X-ray tube 1 includes a plurality of electron emitters 12, a target 11, and an electromagnetic lens 14. The plurality of electron emitters 12, the target 11, and the electromagnetic lens 14 are housed in a vacuum vessel 13.

[0030] The X-ray tube 1 is configured to emit electrons from the electron emitting section 12 by applying a voltage between the cathode, which is an electron emitting section, and the anode, which is a target 11, and to generate X-rays from the target 11 by causing the emitted electrons to collide with the target 11.

[0031] As shown in FIGS. 3 and 4, the plurality of electron emitting sections 12 are arranged according to a corrective arrangement pattern, which will be described later. The corrective arrangement pattern is either a first corrective arrangement pattern 61 (see FIG. 3) or a second corrective arrangement pattern 62 (see FIG. 4). The plurality of electron emitting sections 12 are arranged in an array in an arrangement region 36 on the substrate 31. The array refers to a state in which the electron emitting sections 12 are arranged in a plurality of rows and a plurality of columns according to a predetermined pattern. Each of the plurality of electron emitting sections 12 is configured to irradiate an electron beam 9 (see FIG. 2). The arrangement region 36 is an area that includes at least an area in which a cathode electrode 32 (see FIG. 5), which will be described later, is formed.

[0032] The arrangement region 36 on the substrate 31 has a rectangular shape. In this embodiment, the arrangement region 36 on the substrate 31 has a rectangular shape. The number of electron emitters 12 arranged in the arrangement region 36 is not particularly limited. For convenience of explanation, a predetermined number of electron emitters 12 are shown in FIGS. 2 to 4, but the number of electron emitters 12 can be, for example, 10 or more, 100 or more, or 1000 or more.

[0033] The electron emitter 12 includes a field emission electron source 30 (see FIG. 5). The field emission electron sources 30 are formed in an array on a substrate 31 by applying semiconductor manufacturing technology. The substrate 31 is a flat plate made of silicon, glass, or the like. The multiple electron emitters 12, each including the multiple field emission electron sources 30, are arranged at equal intervals. Note that the multiple electron emitters 12 do not have to be arranged at equal intervals.

[0034] One electron emitter 12 includes one field emission electron source 30 (see FIG. 5). An electron beam 9 is emitted from each field emission electron source 30 of the plurality of electron emitters 12. The electron beam 9 is irradiated onto a focal position on the target 11. When the electron beam 9 collides with the target 11, X-rays 10 (see FIG. 2) are generated from the focal point on the target 11.

[0035] 5, the field emission electron source 30 emits electrons by the tunneling effect from an emitter 33 to which an electric field is applied. The field emission electron source 30 is, for example, a Spindt type electron source. The Spindt type electron source includes a cathode electrode 32 formed on a substrate 31, a tapered emitter 33 formed on the cathode electrode 32, and an insulating layer 34 surrounding the emitter 33, and a gate electrode 35 formed on the insulating layer 34. When a predetermined extraction voltage is applied between the cathode electrode 32 and the gate electrode 35, a high electric field is generated at the tip of the emitter 33, and electrons are emitted from the tip of the emitter 33.

[0036] In the Spindt-type electron source, the emitter 33 is formed by etching a hole penetrating the gate electrode 35 and the insulating layer 34, and depositing the material of the emitter 33 in the formed hole. The field emission electron source 30 may have a structure other than the Spindt-type. For example, the emitter 33 can be formed of a needle-shaped body such as a carbon nanotube.

[0037] The structure of the target 11 is not particularly limited. In this embodiment, the target 11 is a reflective type (see FIG. 2). As shown in FIG. 2, the reflective target 11 has a surface 11a that is inclined obliquely with respect to the electron beam, and emits X-rays 10 so that the X-rays 10 are reflected by the inclined surface 11a in a direction different from the direction in which the electron beam 9 travels. The target 11 may also be a transmissive target. The target 11 may be fixedly provided in the vacuum chamber 13, or may be rotated by a drive source such as a motor. In other words, the target 11 may have a so-called rotating anode structure.

[0038] One or more field emission electron sources 30 (see FIG. 5) are provided with one or more electromagnetic lenses 14 for focus control to focus electrons from emitters 33 (see FIG. 5). The electromagnetic lens 14 is an electromagnet that uses a coil, and has a magnetic pole (pole piece) (not shown) that is formed to protrude toward the center of a hole in the coil. The electron beam 9 emitted from the field emission electron source 30 passes through the area (hole) surrounded by the pole piece and collides with the target 11. Note that the lens for focus control does not have to be the electromagnetic lens 14, but may be an electrostatic lens or another known lens.

[0039] (imaging optical system) The imaging optical system will now be described. The X-ray tube 1 does not use a back-focus optical system, but rather uses an imaging optical system including an electromagnetic lens 14 configured to focus the electron beam 9 so as to form an image point I on the target 11 at which the overall outer shape T of the plurality of electron emitters 12 (see FIGS. 3 and 4) is imaged. FIG. 6 is a schematic diagram for explaining the imaging optical system. The imaging optical system focuses the electron beams 9 emitted at different angles from the electron emitters 12 on the substrate 31 to a single point at the image point I formed on the target 11. The imaging optical system also focuses the electron beams 9 so as to form an image point I on the target 11 at which the overall outer shape T of the plurality of electron emitters 12 is imaged. The imaging optical system cannot focus the electron beams 9 emitted from a large emission area, but it can focus the angular spread of the electron beams 9 emitted from the electron emitters 12.

[0040] 7 is a schematic diagram illustrating a post-focus optical system. The post-focus optical system focuses the electron beams 9 emitted from different positions on the substrate 31 to a single point at a focal point F formed on the target 11. The post-focus optical system cannot focus the angular spread of the electron beams 9 emitted from the electron emitter 12, but can focus the electron beams 9 emitted from a large emission area.

[0041] By adopting the imaging optical system shown in Figure 6, the angular spread of the electron beam 9 emitted from the electron emitting section 12 can be suppressed, and assuming that no distortion aberration occurs, a real focal shape 53 can be obtained in which the outer shape T of the entire plurality of electron emitting sections 12 is approximately projected onto the target 11 in a reduced size.

[0042] (Distortion) Distortion will now be described. Even when an imaging optical system that focuses the angular spread of the electron beam 9 emitted from the electron emitter 12 is employed, distortion of a so-called pincushion or barrel shape may occur at the real focal point formed on the target 11 by the emitted electron beam 9. FIG. 3 shows an example of pincushion distortion 51. With pincushion distortion 51, the real focal point shape 53 formed on the target 11 is distorted so that it extends in the diagonal direction of a rectangle. In other words, with pincushion distortion 51, the central portions 53a of each of the four sides of the real focal point shape 53 are distorted so that they are recessed inward.

[0043] 4 shows an example of barrel distortion 52. In barrel distortion 52, real focal shape 53 formed on target 11 is distorted so that it shrinks in the diagonal direction of the rectangle. In other words, in barrel distortion 52, real focal shape 53 is distorted so that center portions 53a of each of the four sides bulge outward. Whether the distortion generated on target 11 is pincushion distortion 51 or barrel distortion 52 is determined by the positional relationship between electromagnetic lens 14 and aperture stop (not shown).

[0044] The shape of the distortion aberration occurring on the target 11 is acquired based on the design information of the X-ray tube 1, which includes a plurality of electron emitters 12 arranged in an array in the arrangement region 36, the target 11, and an imaging optical system including the electromagnetic lens 14. Specifically, simulations and experiments are performed based on the design information of the X-ray tube 1, and the shape of the distortion aberration occurring on the target 11 is acquired.

[0045] (correction placement pattern) The correction arrangement pattern will now be described. The correction arrangement pattern is a correction arrangement pattern in which the electron emitters 12 are arranged so as to correct distortion occurring on the target 11. The correction arrangement pattern utilizes the characteristics of the imaging optical system (see FIG. 6 ) that enable a real focal shape 53 to be obtained by approximately reducing and projecting the overall outer shape T of the plurality of electron emitters 12 onto the target 11. The correction arrangement pattern is obtained based on the shape of distortion obtained based on design information. Specifically, simulations and experiments are performed based on the acquired shape of distortion, and a correction arrangement pattern in which the electron emitters 12 are arranged so as to correct distortion occurring on the target 11 is obtained. Here, the overall outer shape T of the plurality of electron emitters 12 refers to the outline connecting the outlines of the electron emitters 12 arranged at the outermost periphery, which is the smallest outline of the surrounding outlines.

[0046] 3 shows a first corrective arrangement pattern 61 when the distortion has a pincushion shape. In the first corrective arrangement pattern 61, no electron emitters 12 are arranged at least in the four corners 63 of the rectangular arrangement region 36. In other words, the first corrective arrangement pattern 61 is a pattern in which at least the electron emitters 12 are missing from the four corners 63 of the rectangular arrangement region 36. The first corrective arrangement pattern 61 is also a corrective arrangement pattern in which a plurality of electron emitters 12 are arranged within a contour formed by connecting the long and short sides of the outer shape T of the entire electron emitter 12 via an L-shaped recess.

[0047] 3 illustrates, for convenience, a pattern in which one electron emitter 12 is missing from each of the four corners 63. However, the number of electron emitters 12 that are not arranged in each of the four corners 63 is not limited to one and may be multiple. The specific arrangement of the electron emitters 12 in the first corrective arrangement pattern 61, including the number of electron emitters 12 that are not arranged in each of the four corners 63, can be set appropriately so as to achieve a real focal shape 53 (see FIG. 8) that is closer to a rectangle in order to further reduce the influence of pincushion distortion 51.

[0048] 4 shows a second corrective arrangement pattern 62 when the distortion is barrel-shaped. In the second corrective arrangement pattern 62, no electron emitters 12 are arranged at least in the center 64 of each of the four sides of the rectangular arrangement region 36. In other words, the second corrective arrangement pattern 62 is a pattern in which at least the electron emitters 12 are missing from the center 64 of each of the four sides of the rectangular arrangement region 36. The second corrective arrangement pattern 62 is also a corrective arrangement pattern in which a plurality of electron emitters 12 are arranged within a contour that has inwardly recessed depressions at the centers of the four sides of the overall external shape T of the electron emitters 12.

[0049] 4 illustrates, for convenience, a pattern in which two electron emitters 12 are missing from the center portion 64 of each of the four sides. However, the number of electron emitters 12 that are not arranged in the center portion 64 of each of the four sides is not limited to two, and may be one, or three or more. The specific arrangement of the electron emitters 12 in the second corrective arrangement pattern 62, including the number of electron emitters 12 that are not arranged in the center portion 64 of each of the four sides, can be set appropriately so as to achieve a real focal shape 53 (see FIG. 8) that is closer to a rectangular shape in order to further reduce the influence of barrel distortion 52.

[0050] 8, by arranging the plurality of electron emitters 12 in a rectangular arrangement region 36 on the substrate 31 based on the corrected arrangement pattern, the real focal shape 53 formed on the target 11 can be made substantially rectangular. In this case, the rectangular outer shape T of the entire plurality of electron emitters 12 in the arrangement pattern of the design information before correcting the arrangement of the plurality of electron emitters 12 and the real focal shape 53 formed on the target 11 by the corrected arrangement pattern are similar shapes. By making the real focal shape 53 formed on the target 11 substantially rectangular, the effective area of ​​the focal point on the target 11 can be increased compared to when it is substantially square. This allows the allowable current of the electron beam 9 that generates X-rays from the X-ray tube 1 to be increased.

[0051] (Method of manufacturing X-ray tube 1) Next, a method for manufacturing the X-ray tube 1 according to this embodiment will be described with reference to FIG.

[0052] In step S1, design information is obtained for the X-ray tube 1, which includes a plurality of electron emitters 12 arranged in an array in the arrangement region 36, the target 11, and an imaging optical system including the electromagnetic lens 14. Then, the process proceeds to step S2.

[0053] In step S2, the shape of the distortion occurring on the target 11 is obtained based on the acquired design information of the X-ray tube 1. More specifically, either a pincushion shape or a barrel shape is obtained as the shape of the distortion occurring on the target 11 based on the design information of the X-ray tube 1. Then, the process proceeds to step S3.

[0054] In step S3, a corrective arrangement pattern in which the electron emitters 12 are arranged so as to correct the distortion is obtained based on the shape of the distortion obtained. More specifically, if the shape of the distortion is a pincushion shape, a first corrective arrangement pattern 61 is obtained. If the shape of the distortion is a barrel shape, a second corrective arrangement pattern 62 is obtained. Then, the process proceeds to step S4.

[0055] In step S4, the electron emitting portions 12 are formed on the substrate 31 based on the acquired corrected arrangement pattern.

[0056] (Effects of the manufacturing method of the X-ray tube 1 according to this embodiment) The manufacturing method of the X-ray tube 1 of this embodiment can provide the following effects.

[0057] In this embodiment, as described above, the method for manufacturing the X-ray tube 1 includes the steps of: acquiring a corrected arrangement pattern in which the electron emitters 12 are arranged so as to correct distortion, based on the shape of distortion occurring on the target 11, for the X-ray tube 1 including a plurality of electron emitters 12 arranged in an array in an arrangement region 36 on the substrate 31 and irradiating an electron beam 9; and a lens arranged between the electron emitters 12 and the target 11 and configured to focus the electron beam 9 so as to form an image point I on the target 11 at which the overall outer shape T of the plurality of electron emitters 12 is imaged. The steps include: acquiring a corrected arrangement pattern in which the electron emitters 12 are arranged so as to correct distortion, based on the shape of distortion occurring on the target 11; and forming the electron emitters 12 on the substrate 31 based on the acquired corrected arrangement pattern. The lens configured as described above allows a real focal shape 53 to be obtained by approximately reducing and projecting the overall outer shape T of the plurality of electron emitters 12 onto the target 11. In other words, the real focal shape 53 formed on the target 11 can be adjusted by adjusting the overall outer shape T of the electron emitters 12. Therefore, by correcting the arrangement pattern of the plurality of electron emitters 12 on the substrate 31 based on the shape of the distortion that occurs, it is possible to obtain in advance a corrected arrangement pattern that can bring the shape closer to the desired real focal shape 53 with reduced distortion on the target 11. This allows the electron emitters 12 to be arranged based on the obtained corrected arrangement pattern. Therefore, it is possible to suppress the influence of distortion that occurs on the target 11 due to the electron beams 9 emitted from the electron emitters 12.

[0058] Furthermore, in this embodiment, as described above, the shape of the distortion occurring on target 11 is either a pincushion shape or a barrel shape. This makes it possible to obtain a correction arrangement pattern that appropriately corrects distortion based on either a pincushion shape or a barrel shape, which are typical shapes of distortion.

[0059] Furthermore, in this embodiment, as described above, in the step of acquiring the correction arrangement pattern, when the distortion has a pincushion shape, the correction arrangement pattern is configured to become a first correction arrangement pattern 61 in which no electron emitters 12 are arranged at least in the four corners 63 of the rectangular arrangement region 36. The electron emitters 12 arranged in the four corners 63 of the arrangement region 36 correspond to the electron emitters 12 irradiated with the electron beam 9 in a portion where the image is distorted so as to extend in the diagonal direction of the rectangle. By not arranging the electron emitters 12 in the four corners 63 of the arrangement region 36, it is possible to suppress pincushion distortion 51, which distorts the image so as to extend in the diagonal direction of the rectangle.

[0060] Furthermore, in this embodiment, as described above, in the step of acquiring the correction arrangement pattern, when the distortion is barrel-shaped, the correction arrangement pattern is configured to become a second correction arrangement pattern 62 in which no electron emitters 12 are arranged at least in the center portions 64 of each of the four sides of the rectangular arrangement region 36. The electron emitters 12 arranged in the center portions 64 of each of the four sides of the arrangement region 36 correspond to the electron emitters 12 irradiated with the electron beam 9 in the portion where the center portions of each of the four sides of the rectangle of the image are distorted to bulge outward. By not arranging the electron emitters 12 in the center portions 64 of each of the four sides of the arrangement region 36, it is possible to suppress barrel-shaped distortion 52 in which the center portions of each of the four sides of the rectangle of the image are distorted to bulge outward.

[0061] Furthermore, as described above, this embodiment further includes a step of acquiring the shape of distortion aberration occurring on the target 11 based on design information of the X-ray tube 1 including the plurality of electron emitters 12 and lenses. This makes it possible to accurately and reliably acquire the shape of distortion aberration occurring on the target 11. Therefore, it is possible to more appropriately suppress the influence of distortion aberration occurring on the target 11 due to the electron beam 9 emitted from the electron source.

[0062] Furthermore, in this embodiment, as described above, the plurality of electron emitters 12 are composed of a plurality of field emission electron sources 30, and each of the plurality of field emission electron sources 30 is configured to irradiate the target 11 with the electron beam 9. As a result, unlike the case where a thermionic emission electron source with a large emission area is provided, the angular spread of the electron beam 9 emitted from the electron emitter 12 can be suppressed by employing an imaging optical system. This makes it possible to obtain a real focal shape 53 in which the overall outer shape T of the plurality of field emission electron sources 30 is approximately reduced and projected onto the target 11. Therefore, it is possible to obtain a corrected arrangement pattern in which distortion aberration is appropriately corrected.

[0063] (Effects of the X-ray imaging apparatus 100 according to this embodiment) The X-ray imaging device 100 of this embodiment is an X-ray imaging device 100 including an X-ray tube 1 manufactured by the above-mentioned manufacturing method, and therefore has the same effect as above, that is, it is possible to suppress the influence of distortion aberration that occurs on the target 11 due to the electron beam 9 emitted from the electron emitter 12.

[0064] [Variations] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0065] For example, in the above embodiment, an example of a corrective arrangement pattern in which the electron emitting portions 12 are not arranged at least in the four corners 63 of the rectangular arrangement region 36 is shown as the first corrective arrangement pattern 61, but the present invention is not limited to this.

[0066] 10, when the distortion has a pincushion shape, the first correction arrangement pattern 61 according to the modified example may be configured so that at least at the four corners 63 of the rectangular arrangement region 36, the outermost electron emitters 12 are arranged diagonally with respect to the four sides of the arrangement region 36. This makes it possible to suppress pincushion distortion 51, which distorts the image so as to extend in the diagonal direction of the rectangle.

[0067] In the above embodiment, the electron emitters 12 are arranged in a regular lattice pattern in the first corrective arrangement pattern 61, but the present invention is not limited to this. As shown in Fig. 10, the electron emitters 12 may be arranged in a diagonal lattice pattern in the first corrective arrangement pattern 61. As shown in Fig. 10, the first corrective arrangement pattern 61 in which the electron emitters 12 are arranged so as to correct the pincushion distortion 51 (see Fig. 3) does not have to be symmetrical in the vertical and horizontal directions in a plan view.

[0068] 3, pincushion distortion 51 distorts the image such that central portions 53a of each of the four sides of real focal shape 53 curve inward. Therefore, electron emitters 12 may be arranged so as to correct the inwardly curved distortion at central portions 53a of each of the four sides of the image. In this case, a corrected arrangement pattern can be configured in which electron emitters 12 are not arranged at four corners 63 of arrangement region 36, and electron emitters 12 are arranged so that central portions 64 of each of the four sides of arrangement region 36 curve outward.

[0069] Furthermore, in the above embodiment, an example of the second corrective arrangement pattern 62 is shown in which the electron emitting section 12 is not arranged at least in the central portion 64 of each of the four sides of the rectangular arrangement area 36, ​​but the present invention is not limited to this.

[0070] 11, when the distortion is barrel-shaped, the second correction arrangement pattern 62 according to the modified example may be arranged such that at least the outermost electron emitters 12 on each of the four sides of the rectangular arrangement region 36 are aligned in a slanted manner and recessed toward the center of the arrangement region 36. This makes it possible to suppress barrel-shaped distortion 52, in which the central portions of the four rectangular sides of the image are distorted to bulge outward.

[0071] In the above embodiment, the electron emitters 12 are arranged in a regular lattice pattern in the second corrective arrangement pattern 62, but the present invention is not limited to this. As shown in Fig. 11, the electron emitters 12 may be arranged in a diagonal lattice pattern in the second corrective arrangement pattern 62. As shown in Fig. 11, the second corrective arrangement pattern 62 in which the electron emitters 12 are arranged so as to correct the barrel distortion 52 (see Fig. 4) does not have to be symmetrical in the vertical and horizontal directions in a plan view.

[0072] 4, barrel distortion 52 distorts the image so that the central portions 53a of the four sides of the real focal shape 53 bulge outward. Therefore, electron emitters 12 may be arranged to correct the outwardly curving distortion at the central portions 53a of the four sides of the image. In this case, a corrected arrangement pattern can be configured in which no electron emitters 12 are arranged at the central portions 64 of the four sides of the arrangement region 36, and the electron emitters 12 are arranged so that the central portions 64 of the four sides of the arrangement region 36 curve inward.

[0073] In the above embodiment, the arrangement region 36 on the substrate 31 is rectangular, and the plurality of electron emitters 12 are arranged in an array at equal intervals in the arrangement region 36, but the present invention is not limited to this. The arrangement region 36 may be square or polygonal. The plurality of electron emitters 12 may be arranged in a non-array in the arrangement region 36, or may be arranged at different pitches.

[0074] In the above embodiment, an example was shown in which the shape of the distortion aberration occurring on the target 11 was acquired based on the design information of the X-ray tube 1, but the present invention is not limited to this. The shape of the distortion aberration occurring on the target 11 may also be acquired based on the X-ray tube 1 manufactured based on the design information.

[0075] In the above embodiment, the X-ray imaging apparatus 100 is used for non-destructive testing, but the present invention is not limited to this. The X-ray imaging apparatus 100 may also be used for medical purposes. In this case, the subject 90 is a living body to be inspected.

[0076] In the above embodiment, examples of the pincushion shape and barrel shape are shown as examples of the shape of distortion occurring on target 11, but the present invention is not limited to these. The shape of distortion occurring on target 11 may be a shape other than those described above.

[0077] [Aspect] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0078] (Item 1) a step of acquiring a corrective arrangement pattern in which the electron emitting units are arranged so as to correct distortion aberration based on the shape of distortion aberration occurring on the target, in an X-ray tube including a plurality of electron emitting units arranged in an array in an arrangement region on a substrate and irradiating an electron beam, and a lens arranged between the electron emitting units and a target and configured to focus the electron beam so as to form an imaging point on the target at which an outline shape of the entire plurality of electron emitting units is imaged; forming the electron emission portions on the substrate based on the acquired corrected arrangement pattern.

[0079] (Item 2) 2. The method for manufacturing an X-ray tube according to item 1, wherein the shape of the distortion generated on the target is either a pincushion shape or a barrel shape.

[0080] (Item 3) 3. The method for manufacturing an X-ray tube according to item 2, wherein, in the step of acquiring the correction arrangement pattern, when the shape of the distortion aberration is the pincushion shape, the correction arrangement pattern is configured to become a first correction arrangement pattern in which the electron emitters are not arranged at least in the four corners of the rectangular arrangement area.

[0081] (Item 4) 3. The method for manufacturing an X-ray tube according to item 2, wherein, in the step of acquiring the correction arrangement pattern, when the shape of the distortion aberration is the pincushion shape, the correction arrangement pattern is configured to become a first correction arrangement pattern in which at least at the four corners of the rectangular arrangement area, the outermost multiple electron emitters are arranged diagonally with respect to the four sides of the arrangement area.

[0082] (Item 5) Item 3. The method for manufacturing an X-ray tube according to item 2, wherein, in the step of acquiring the correction arrangement pattern, when the shape of the distortion aberration is the barrel shape, the correction arrangement pattern is configured to become a second correction arrangement pattern in which the electron emission portion is not arranged at least in the center of each of the four sides of the rectangular arrangement area.

[0083] (Item 6) Item 3. The method for manufacturing an X-ray tube according to item 2, wherein, in the step of acquiring the correction arrangement pattern, when the shape of the distortion aberration is the barrel shape, the correction arrangement pattern is configured to become a second correction arrangement pattern in which the outermost multiple electron emitters on at least each of the four sides of the rectangular arrangement area are arranged side by side so as to be recessed at an angle toward the center of the arrangement area.

[0084] (Item 7) 7. The method for manufacturing an X-ray tube according to any one of items 1 to 6, further comprising a step of acquiring a shape of distortion aberration occurring on the target based on design information of the X-ray tube including the plurality of electron emitters and the lenses.

[0085] (Item 8) 8. The method for manufacturing an X-ray tube according to any one of items 1 to 7, wherein the plurality of electron emitters are configured by a plurality of field emission electron sources, and each of the plurality of field emission electron sources is configured to irradiate the target with the electron beam.

[0086] (Item 9) an X-ray tube including a plurality of electron emitting units arranged in an array in an arrangement area on a substrate, each emitting an electron beam; and a lens arranged between the electron emitting units and a target, configured to focus the electron beam so as to form an image point on the target at which an outline shape of the entire plurality of electron emitting units is imaged; a detector for detecting X-rays emitted from the X-ray tube; an image processing unit that generates an image based on the detection signal output from the detection unit, An X-ray imaging device, wherein the arrangement pattern of the electron emitting units in the arrangement area on the substrate of the X-ray tube is configured to be a corrective arrangement pattern in which the electron emitting units are arranged so as to correct distortion aberration occurring on the target.

[0087] (Item 10) 10. The X-ray imaging apparatus according to item 9, wherein the shape of the distortion occurring on the target is either a pincushion shape or a barrel shape.

[0088] (Item 11) Item 9. The X-ray imaging device according to item 9, wherein when the shape of the distortion aberration is the pincushion shape, the correction arrangement pattern is configured to be a first correction arrangement pattern in which the electron emitting units are not arranged at least at the four corners of the rectangular arrangement area.

[0089] (Item 12) Item 11. The X-ray imaging device according to item 10, wherein when the shape of the distortion aberration is the pincushion shape, the correction arrangement pattern is configured to be a first correction arrangement pattern in which at least at the four corners of the rectangular arrangement area, the outermost multiple electron emitters are arranged diagonally with respect to the four sides of the arrangement area.

[0090] (Item 13) Item 11. The X-ray imaging device according to item 10, wherein when the shape of the distortion aberration is the barrel shape, the correction arrangement pattern is configured to be a second correction arrangement pattern in which the electron emission unit is not arranged at least in the center of each of the four sides of the rectangular arrangement area.

[0091] (Item 14) Item 11. The X-ray imaging device according to item 10, wherein when the shape of the distortion aberration is the barrel shape, the correction arrangement pattern is configured to be a second correction arrangement pattern in which the outermost multiple electron emitters on at least each of the four sides of the rectangular arrangement area are arranged side by side so as to be recessed at an angle toward the center of the arrangement area.

[0092] (Item 15) 15. The X-ray imaging apparatus according to any one of items 9 to 14, wherein the plurality of electron emitters are configured by a plurality of field emission electron sources, and each of the plurality of field emission electron sources is configured to irradiate the target with an electron beam. [Explanation of symbols]

[0093] 1 X-ray tube 2. Detector 9 Electron beam 10 X-ray 11 Target 12 Electron emission part 14 Electromagnetic Lens 30 Field emission electron source 31 PCB 36 Placement area 51 Pincushion distortion 52 Barrel distortion 61 First correction arrangement pattern 62 Second Correction Arrangement Pattern 63 Four Corners 64 Center of all four sides 90 Subject 100 X-ray equipment

Claims

1. a step of acquiring a correction arrangement pattern in which the electron emitting units are arranged so as to correct distortion aberration based on the shape of distortion aberration occurring on the target, in an X-ray tube including a plurality of electron emitting units arranged in an array in an arrangement region on a substrate and irradiating an electron beam, and a lens arranged between the electron emitting units and a target and configured to focus the electron beam so as to form an imaging point on the target at which an outline shape of the entire plurality of electron emitting units is imaged; forming the electron emission portions on the substrate based on the acquired corrected arrangement pattern.

2. 2. The method for manufacturing an X-ray tube according to claim 1, wherein the shape of the distortion produced on the target is either a pincushion shape or a barrel shape.

3. 3. The method for manufacturing an X-ray tube according to claim 2, wherein, in the step of acquiring the correction arrangement pattern, when the shape of the distortion aberration is the pincushion shape, the correction arrangement pattern is configured to become a first correction arrangement pattern in which the electron emitters are not arranged at least in four corners of the rectangular arrangement area.

4. 3. The method for manufacturing an X-ray tube according to claim 2, wherein, in the step of acquiring the correction arrangement pattern, when the shape of the distortion aberration is the pincushion shape, the correction arrangement pattern is configured to become a first correction arrangement pattern in which at least at the four corners of the rectangular arrangement area, the outermost plurality of electron emitters are arranged diagonally with respect to the four sides of the arrangement area.

5. 3. The method for manufacturing an X-ray tube according to claim 2, wherein, in the step of acquiring the correction arrangement pattern, when the shape of the distortion aberration is the barrel shape, the correction arrangement pattern is configured to become a second correction arrangement pattern in which the electron emitters are not arranged at least in the center of each of the four sides of the rectangular arrangement area.

6. 3. The method for manufacturing an X-ray tube according to claim 2, wherein, in the step of acquiring the correction arrangement pattern, when the shape of the distortion aberration is the barrel shape, the correction arrangement pattern is configured to become a second correction arrangement pattern in which the outermost plurality of electron emitters on at least each of four sides of the rectangular arrangement area are arranged side by side so as to be recessed at an angle toward the center of the arrangement area.

7. The method for manufacturing an X-ray tube according to claim 1 , further comprising the step of acquiring a shape of distortion occurring on the target based on design information of the X-ray tube including the plurality of electron emitters and the lens.

8. 8. The method for manufacturing an X-ray tube according to claim 1, wherein the plurality of electron emitters are configured by a plurality of field emission electron sources, and each of the plurality of field emission electron sources is configured to irradiate the target with the electron beam.

9. an X-ray tube including: a plurality of electron emitting units arranged in an array in an arrangement area on a substrate, each emitting an electron beam; and a lens arranged between the electron emitting units and a target, configured to focus the electron beam so as to form an image point on the target at which an outline shape of the entire plurality of electron emitting units is imaged; a detector for detecting X-rays emitted from the X-ray tube; an image processing unit that generates an image based on the detection signal output from the detector, an X-ray imaging device, wherein the arrangement pattern of the electron emitters in the arrangement region on the substrate of the X-ray tube is configured to be a corrective arrangement pattern in which the electron emitters are arranged so as to correct distortion aberration occurring on the target, based on the shape of distortion aberration occurring on the target.

10. 10. The X-ray imaging apparatus according to claim 9, wherein the shape of the distortion occurring on the target is either a pincushion shape or a barrel shape.

11. An X-ray tube including a plurality of electron emitting sections arranged in an array in an arrangement area on a substrate and irradiating electron beams, and a lens arranged between the electron emitting sections and a target and configured to focus the electron beams so as to form an image point on the target at which the overall external shape of the plurality of electron emitting sections is imaged; a detector for detecting X-rays emitted from the X-ray tube; an image processing unit that generates an image based on the detection signal output from the detector, an arrangement pattern of the electron emitting units in an arrangement region on the substrate of the X-ray tube is configured to be a corrective arrangement pattern in which the electron emitting units are arranged so as to correct distortion aberration occurring on the target; An X-ray imaging device configured such that, when the shape of the distortion aberration occurring on the target is a pincushion shape, the correction arrangement pattern becomes a first correction arrangement pattern in which the electron emission section is not arranged at least at the four corners of the rectangular arrangement area.

12. 11. The X-ray imaging device according to claim 10, wherein when the shape of the distortion aberration is the pincushion shape, the correction arrangement pattern is configured to be a first correction arrangement pattern in which at least at the four corners of the rectangular arrangement area, the outermost multiple electron emitters are arranged diagonally with respect to the four sides of the arrangement area.

13. An X-ray tube including a plurality of electron emitting sections arranged in an array in an arrangement area on a substrate and irradiating electron beams, and a lens arranged between the electron emitting sections and a target and configured to focus the electron beams so as to form an image point on the target at which the overall external shape of the plurality of electron emitting sections is imaged; a detector for detecting X-rays emitted from the X-ray tube; an image processing unit that generates an image based on the detection signal output from the detector, an arrangement pattern of the electron emitting units in an arrangement region on the substrate of the X-ray tube is configured to be a corrective arrangement pattern in which the electron emitting units are arranged so as to correct distortion aberration occurring on the target; An X-ray imaging device configured such that, when the shape of the distortion aberration occurring on the target is barrel-shaped, the correction arrangement pattern becomes a second correction arrangement pattern in which the electron emission section is not arranged at least in the center of each of the four sides of the rectangular arrangement area.

14. 11. The X-ray imaging device according to claim 10, wherein when the shape of the distortion aberration is the barrel shape, the correction arrangement pattern is configured to be a second correction arrangement pattern in which the outermost multiple electron emitters on at least each of the four sides of the rectangular arrangement area are arranged side by side so as to be recessed at an angle toward the center of the arrangement area.

15. 15. The X-ray imaging apparatus according to claim 9, wherein the plurality of electron emitters are configured by a plurality of field emission electron sources, and each of the plurality of field emission electron sources is configured to irradiate the target with an electron beam.

Images