JP6444713B2 - X-ray generator - Google Patents

Description

The present invention relates to X-ray generating equipment, and more specifically, relates to a high operability X-ray generating equipment.

  Conventionally, X-ray imaging is used for diagnosis in the medical field and non-destructive inspection in the industrial equipment field.

  An X-ray generator that generates X-rays includes an electron source that emits electrons, a lens electrode that focuses the electrons emitted from the electron source, and a target that generates X-rays when the electrons collide. . The X-ray generator collides electrons emitted from an electron source with a target, and generates X-rays from the target by the collision energy. The generated X-ray is radiated to an external object through the window. There are two types of X-ray generators, a transmission type and a reflection type. The transmission type is a method of extracting X-rays from the same direction as the traveling direction of the electron beam from the electron source toward the target. The reflection type is a method of extracting X-rays from a direction different from the traveling direction of the electron beam from the electron source toward the target.

  FIG. 9 is a cross-sectional view schematically showing a configuration in the vicinity of a window of a conventional transmission X-ray generator. In the drawing of the present application, the width of X-rays irradiated from the target is indicated by a dotted line.

  Referring to FIG. 9, the conventional transmission X-ray generator includes a vacuum container 131 and a head 110. The head 110 is fixed to the upper part of the vacuum container 131 in FIG. The vacuum vessel 131 and the head 110 constitute a vacuum (reduced pressure) space. The head 110 has a cylindrical shape and has a uniform width along a direction (direction indicated by an arrow AR2) for guiding X-rays to the target 113. The head 110 includes a case 111, a window 112, and a target 113. The case 111 includes an opening at the top thereof. The window 112 is fixed to the upper part of the case 111 so as to close the opening of the case 111. The window 112 has a flat plate shape. The target 113 is deposited on the surface of the window 112 on the inner side (lower side in FIG. 9) of the X-ray generator. The target 113 is made of a substance that generates X-rays when irradiated with an electron beam.

  The conventional transmission X-ray generator generates X-rays from the target 113 by irradiating the target 113 with an electron beam as indicated by an arrow AR1. The generated X-rays are irradiated through the window 112 in the direction indicated by the arrow AR2.

  A conventional transmission X-ray generator is disclosed in, for example, Patent Document 1 below. Patent Document 1 below discloses an electron emission source, a flat target that generates X-rays by irradiation of electrons emitted from the electron emission source, a shielding member that shields X-rays emitted from the target, An X-ray generation device including a temperature sensor for detecting temperature is disclosed. The target includes a target substrate and a target film provided on the surface of the target substrate on the electron emission source side.

JP 2012-186111 A

  However, the conventional transmission X-ray generator has a problem of low performance. This will be described below.

  FIG. 10 is a diagram for explaining a problem of a conventional transmission X-ray generator. In the drawings of the present application, two arbitrary directions orthogonal to each other in a planar table are referred to as an x-axis and a y-axis, and a normal direction of the table is referred to as a z-axis.

  Referring to FIG. 10, the transmission X-ray generator irradiates work WK arranged on table 140 with X-rays. The X-ray irradiation position on the work WK can be changed by moving the transmission X-ray generator (or table 140) in the xy plane while keeping the distance between the tip of the head 110 and the work WK constant. is there. Further, by tilting the transmissive X-ray generator (or table 140), the X-ray irradiation angle with respect to the z-axis can be changed. Further, the transmission X-ray generator can change the magnification of X-ray imaging by moving the X-ray generator (or table 140) in the z-axis direction.

  When the X-ray irradiation angle is 0 (when the X-ray irradiation direction coincides with the z-axis direction), the transmission X-ray generator has a distance between the tip of the head 110 and the workpiece WK. The table 140 can be approached until the state ST1 where d1 is reached. As a result, the transmission X-ray generator can perform X-ray imaging at a high magnification.

  On the other hand, when the X-ray irradiation angle is greater than 0 (when the X-ray irradiation direction does not match the z-axis direction), the transmission X-ray generator and the table 140 interfere at the position PO. Therefore, the distance between the tip of the head 110 and the work WK cannot be reduced to the distance d1. The transmission X-ray generator can only approach the table 140 until the state ST2 where the distance between the tip of the head 110 and the workpiece WK is a distance d2 (> d1). As a result, X-ray imaging can be performed only at a lower magnification than when the X-ray irradiation angle is zero.

  The above problem is not limited to the transmission X-ray generator, but may occur in all X-ray generators including the reflective X-ray generator.

The present invention is intended to solve the above problems, its object is to provide a high-performance X-ray generating equipment.

An X-ray generator according to an aspect of the present invention includes an X-ray generator head that guides X-rays generated inside the X-ray generator to an object disposed outside the X-ray generator, and the X together with the head. A main body that forms an internal space for decompression in the line generator, the main body extending in a first direction for guiding X-rays to an object, and at a position closer to the head than the side surface in the first direction An end surface that extends in a direction orthogonal to the first direction, and an inclined surface that is provided between the side surface and the end surface, and is inclined with respect to each of the side surface and the end surface. A case including a fixed end fixed to the main body , the fixed end having a width narrower than a width of a side surface perpendicular to the first direction, and an X-ray transmission higher than that of the case has a rate, and a window attached to the case, X The when viewed in cross-section including the direction that leads to the object, the width of the f head decreases as the distance from the fixed end in the direction to guide the X-ray to the object.

Oite preferably in the X-ray generating equipment provides a target for generating X-rays by irradiation of electron beam, when the case is fixed to the main body, the fixed end than the window along the first direction It further comprises a target arranged on the near side.

Preferably Oite above X-ray generating equipment, the target is in contact with the window.

Oite preferably in the X-ray generating equipment, window, if the case is fixed to the main body, includes a protrusion that protrudes in the first direction than the case.

Preferably Oite above X-ray generating equipment, projection, and a top, and a shoulder present on the case side than the top portion, the flatness of each of the top and shoulders, in the following larger than 0 1 mm is there.

Oite preferably in the X-ray generating equipment, when viewed in cross-section including the direction directing X-rays to an object, the width of the case decreases as the distance from the fixed end, the window is a flat plate, It is attached at a position farthest from the fixed end of the case.

According to the present invention, it is possible to provide a high-performance X-ray generating equipment.

It is sectional drawing which shows typically the structure of the X-ray imaging apparatus in one embodiment of this invention. 2 is a cross-sectional view showing a first configuration of a head 10. FIG. 4 is a cross-sectional view showing a second configuration of the head 10. FIG. 4 is a cross-sectional view showing a third configuration of the head 10. FIG. 6 is a cross-sectional view showing a fourth configuration of the head 10. FIG. 6 is a cross-sectional view showing a fifth configuration of the head 10. FIG. It is a 1st figure explaining the effect of the X-ray generator in one embodiment of this invention. It is a 2nd figure explaining the effect of the X-ray generator in one embodiment of this invention. It is sectional drawing which shows typically the structure of the window vicinity of the conventional transmission X-ray generator. It is a figure explaining the problem of the conventional transmission X-ray generator.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing a configuration of an X-ray imaging apparatus according to an embodiment of the present invention. In FIG. 1, a part of the configuration is shown by blocks.

  Referring to FIG. 1, the X-ray imaging apparatus according to the present embodiment includes an X-ray generation apparatus 1, a table 40, an X-ray detection apparatus 50, a control unit 80, an operation unit 90, and the like. The X-ray imaging apparatus may further include a vacuum pump (decompression apparatus) for decompressing the inside of the X-ray generation apparatus 1.

  The X-ray generator 1 includes a head 10 (an example of an X-ray generator head), a vacuum container 31, an electron beam generator 32, and a focusing electrode 33. The X-ray generator 1 generates X-rays from the target by irradiating the target, which is a part of the head 10, with an electron beam in the direction indicated by the arrow AR1. X-rays generated inside the X-ray generator 1 are guided by the head 10 to the work WK arranged outside the X-ray generator 1 as indicated by an arrow AR2.

  The vacuum vessel 31 preferably includes an inclined surface 31a at the end on the table 40 side. The inclined surface 31a is inclined with respect to both the end surface (upper and lower end surfaces in FIG. 1) and the side surface extending between the end surfaces.

The vacuum container 31 is made of glass or ceramics. The vacuum vessel 31 and the head 10 constitute a vacuum (reduced pressure) internal space. The space formed by the vacuum vessel 31 and the head 10 is at least a degree of vacuum (for example, 1 × 10 ⁻⁴ Pa or less) that allows electrons to fly between the electron beam generator 32 and the target of the head 10. (Degree of vacuum). The degree of vacuum in the space formed by the vacuum vessel 31 and the head 10 is preferably set as appropriate in consideration of the type of the electron beam generator 32 used, the operating temperature of the electron beam generator 32, and the like.

  The electron beam generator 32 generates an electron beam. The electron beam generator 32 may be a hot cathode type or a cold cathode type. The electron beam generator 32 is disposed so as to penetrate the vacuum vessel 31. The electron beam generator 32 is electrically connected to the controller 80 via a current introduction terminal 32a exposed to the outside of the vacuum vessel 31. Thereby, the intensity of the electron beam in the electron beam generator 32 is controlled by the X-ray generation controller 81.

  The focusing electrode 33 is arranged at a predetermined distance from the electron beam generator 32 at a position closer to the head 10 than the electron beam generator 32. When a predetermined voltage is applied to the focusing electrode 33, an electric field is generated from the focusing electrode 33. Due to this electric field, electrons generated from the electron beam generator 32 are drawn out into a vacuum and become an electron beam. Further, due to the lens effect of this electric field, the electron beam generated from the electron beam generator 32 is focused and irradiated onto the target of the head 10.

  The table 40 is for placing a work WK (an example of an object).

  The X-ray detection apparatus 50 receives the X-ray that has passed through the workpiece WK, and transmits a signal indicating the intensity of the received X-ray to the control unit 80.

  The control unit 80 is electrically connected to each of the X-ray generation apparatus 1, the X-ray detection apparatus 50, and the operation unit 90, and controls the entire X-ray imaging apparatus. The control unit 80 includes an X-ray generation control unit 81, a position angle adjustment unit 82, and an image generation unit 83.

  The X-ray generation control unit 81 controls the voltage applied to the electron beam generation unit 32 and the focusing electrode 33, the degree of vacuum inside the X-ray generation device 1, and the like to generate X-rays generated from the X-ray generation device 1. Control.

  The position angle adjustment unit 82 moves the X-ray generator 1 to move the position of the X-ray generator 1 with respect to the table 40 (the respective positions in the x-axis direction, the y-axis direction, and the z-axis direction) and the angle (z X-ray irradiation angle with respect to the axis) is adjusted. The position angle adjustment unit 82 may adjust the position and angle of the X-ray generator 1 with respect to the table 40 by moving the table 40 instead of the X-ray generator 1.

  The image generation unit 83 generates an X-ray image of the work WK based on the signal received from the X-ray detection device 50.

  The operation unit 90 receives various operations related to the X-ray detection apparatus from the operator, and transmits a signal based on the received operation to the control unit 80.

  The head 10 is fixed to the upper part of the vacuum vessel 31 in FIG. The head 10 may be detachable with respect to a portion of the X-ray generator 1 excluding the head 10 (hereinafter sometimes referred to as an X-ray generator main body), or may be detachable. The head 10 has, for example, any one of first to fifth configurations described below.

  FIG. 2 is a cross-sectional view showing a first configuration of the head 10. Each of the cross-sectional views in FIGS. 2 to 6 is a cross-sectional view including a direction including an X-ray guide direction to the workpiece WK. 2 to 6, a direction (side) for guiding X-rays to the workpiece WK (that is, an upward direction (side) in FIGS. 2 to 6) is referred to as an external direction (side), and a direction for guiding X-rays to the workpiece WK. The direction (side) opposite to (i.e., the downward direction (side) in FIGS. 2 to 6) may be referred to as the internal direction (side).

  With reference to FIG. 2, the head 10 having the first configuration includes a case 11, a window 12, and a target 13.

  The case 11 is fixed to the X-ray generator main body (here, the vacuum vessel 31). The case 11 is made of, for example, glass or ceramics.

  The case 11 has a base portion 11a extending along the external direction (upward direction in FIG. 2), and a shoulder that is located farther away from the vacuum vessel 31 than the base portion 11a and extends inclining with respect to the external direction. It includes a portion 11b, a connecting portion 11c provided at the end of the shoulder 11b, and a fixed end 11d fixed to the X-ray generator main body. The base 11a has, for example, a cylindrical shape. The connecting portion 11c has a smaller thickness than the shoulder portion 11b.

  The window 12 projects outward from the case 11 when the case 11 is fixed to the X-ray generator main body. In other words, the entire window 12 is a protruding portion.

  The window 12 includes a top portion 12a and a shoulder portion 12b. The top part 12a exists on the side closest to the workpiece WK in the head 10 (uppermost side in FIG. 2). The surface of the top portion 12a on the side exposed to the outside extends in a direction perpendicular to the external direction (lateral direction in FIG. 2). The shoulder portion 12b is present on the case 11 side (lower side in FIG. 2) from the top portion 12a, and extends inclined with respect to the external direction. The end portion of the shoulder portion 12b is attached to the connection portion 11c by brazing, for example. Both the top 12a and the shoulder 12b are flat. Specifically, the flatness of each of the top portion 12a and the shoulder portion 12b is greater than 0 and 1 mm or less. The flatness here is the flatness specified in JIS (Japan Industrial Standards) B 0621, and is measured by reading the difference between the maximum value and the minimum value of the displacement amount of the window 12 surface with a laser displacement meter. It is.

  The window 12 has a higher X-ray transmittance than the case 11. The window 12 is made of a material having a high X-ray transmittance and a high thermal conductivity and having a strength capable of maintaining a reduced pressure atmosphere in the space. Specifically, the window 12 is made of titanium, diamond-like carbon, beryllium, or the like. Further, the window 12 is preferably made of a conductive material. Although the thickness of the window 12 changes with materials, it is preferable that it is 0.2 mm or more and 2 mm or less.

  The target 13 is disposed closer to the fixed end 11d than the window 12 along the direction in which the X-ray is guided to the work WK when the case 11 is fixed to the X-ray generator main body. The target 13 is in contact with the inner surface of the window 12.

  The target 13 generates X-rays when irradiated with an electron beam. The target 13 is usually made of a metal material having an atomic number of 26 or more. The target 13 preferably has a high thermal conductivity and a high melting point. Specifically, the target 13 is made of a metal such as tungsten, molybdenum, chromium, copper, cobalt, iron, rhodium, or rhenium, or an alloy material thereof. The thickness of the target 13 varies depending on the material, but is preferably 1 μm or more and 15 μm or less. The target 13 is preferably formed by a method such as sputtering or vapor deposition. The target 13 may be formed of a thin film produced by rolling or polishing.

  When viewed in the cross section shown in FIG. 2, the width w of the head 10 decreases as the distance from the fixed end 11d increases in the external direction. This is because the case 11 includes the shoulder portion 11b and the window 12 includes the shoulder portion 12b.

  The head 10 may further include a shielding member that shields X-rays emitted in directions other than the direction in which X-rays are guided to the work WK.

  In addition to the case where the head 10 has the first configuration shown in FIG. 2, for example, the second configuration shown in FIG. 3, the third configuration shown in FIG. 4, the fourth configuration shown in FIG. 5, or FIG. You may have the 5th structure shown.

  FIG. 3 is a cross-sectional view showing a second configuration of the head 10.

  Referring to FIG. 3, when head 10 having the second configuration is viewed in a cross section including top 12a, top 12a has an arcuate cross-sectional shape. Also in the second configuration, the entire window 12 is a protruding portion. The top part 12a and the shoulder part 12b may have a common arcuate cross-sectional shape.

  Since the configuration other than this is the same as that of the head having the first configuration, the same reference numeral is given to the same member, and the description thereof will not be repeated.

  FIG. 4 is a cross-sectional view showing a third configuration of the head 10.

  With reference to FIG. 4, the head 10 having the third configuration further includes a base portion 12 c attached to the upper surface of the cylindrical case 11. The base 12c exists on the case 11 side with respect to the shoulder 12b. The upper surface of the case 11 and the base 12c extend in a direction perpendicular to the electron beam irradiation direction (lateral direction in FIG. 4). The base 12c is attached to the case 11 by brazing, for example. The base 12c is a plane having a surface roughness Ry greater than 0 and 0.5 μm or less when viewed in a cross section including the top 12a. The target 13 is not formed on the base portion 12c, but is formed along the top portion 12a and the shoulder portion 12b. In the third configuration, the top portion 12a and the shoulder portion 12b are protruding portions.

  When viewed in the cross section shown in FIG. 4, the width w of the head 10 decreases as the distance from the fixed end 11d increases in the external direction. This is because the case 11 has a cylindrical shape while the window 12 includes a shoulder 12b.

  Since the configuration other than this is the same as that of the head having the first configuration, the same reference numeral is given to the same member, and the description thereof will not be repeated.

  FIG. 5 is a cross-sectional view showing a fourth configuration of the head 10.

  Referring to FIG. 5, in the head 10 having the fourth configuration, the case 11 has a base portion 11a extending along the external direction (upward direction in FIG. 5), and is further away from the vacuum vessel 31 than the base portion 11a. The shoulder portion 11b that exists at a position and extends while being inclined with respect to the external direction, and a connection portion that extends in a direction perpendicular to the external direction (lateral direction in FIG. 5) at the end of the shoulder portion 11b 11c and a fixed end 11d fixed to the X-ray generator main body.

  The window 12 has a flat plate shape and is attached at a position farthest from the fixed end 11 d in the case 11. The window 12 is fixed on the connection part 11c. The outer diameter of the window 12 is, for example, 10 mm to 1 mm, more preferably 5 mm to 1 mm, and still more preferably 3 mm to 1 mm. The head 10 having the fourth configuration is an electrostatic lens type microfocus X-ray source having a focal diameter of 10 μm to 0.5 μm, more preferably 5 μm to 0.5 μm, and further preferably 3 μm to 0.5 μm. Is suitable.

  The target 13 has a flat plate shape, and is disposed on the inner side of the window 12 when the case 11 is fixed to the X-ray generator main body. The target 13 is in contact with the inner surface of the window 12.

  When viewed in the cross section shown in FIG. 5, the width w of the head 10 (case 11) decreases as the distance from the fixed end 11d increases in the external direction. This is because the case 11 includes the shoulder 11b while the window 12 is flat. In addition, the angle of the shoulder 11b with respect to the external direction is substantially the same inside and outside the case 11. The inside of the case 11 is tapered, and when viewed from the target 13 toward the inside, the inside of the case 11 has a shape that gradually widens.

  Since the configuration other than this is the same as that of the head having the first configuration, the same reference numeral is given to the same member, and the description thereof will not be repeated.

  Each of the heads having the first to fourth configurations is a head for a transmission X-ray generator that extracts X-rays from the same direction as the traveling direction of the electron beam (takes out X-rays that have passed through the target). . The transmission X-ray generator has the advantage that the distance between the target and the workpiece can be reduced, and the magnification of X-ray imaging can be increased.

  On the other hand, the head having the fifth configuration described below is a head for a reflection type X-ray generator that extracts X-rays from a direction different from the traveling direction of the electron beam (takes out X-rays reflected by the target). .

  FIG. 6 is a cross-sectional view showing a fifth configuration of the head 10.

  Referring to FIG. 6, the head 10 having the fifth configuration is obtained by removing the target from the head having the first configuration. The target 13 is disposed away from the window 12 in the internal space formed by the vacuum vessel 31 and the head 10. In this case, the electron beam generating unit 32 irradiates the target 13 with the electron beam from the direction indicated by the arrow AR1, which is a direction inclined with respect to the X-ray irradiation direction indicated by the arrow AR2.

  Since the configuration other than this is the same as that of the head having the first configuration, the same reference numeral is given to the same member, and the description thereof will not be repeated.

  It is also possible to exclude the target from the head having the second, third, or fourth configuration.

  Then, the effect of this Embodiment is demonstrated.

  7 and 8 are diagrams for explaining the effects of the X-ray generator in one embodiment of the present invention.

  Referring to FIG. 7, when the X-ray irradiation angle is 0 (when the X-ray irradiation direction coincides with the z-axis direction), X-ray generation apparatus 1 uses the tip of head 10 and the workpiece. The table 40 can be approached until the state ST1 where the distance from the WK is the distance d1. As a result, X-ray imaging can be performed at a high magnification.

  Even when the X-ray irradiation angle is greater than 0 (when the X-ray irradiation direction and the z-axis direction do not match), the X-ray generation apparatus 1 can detect the tip of the head 10 and the workpiece WK. The table 40 can be approached until the state ST3 where the distance becomes the distance d1 (or a distance substantially equal to the distance d1). This is because the width of the head 10 in this embodiment decreases as the distance from the fixed end 11d increases along the external direction. As a result, the X-ray irradiation direction can be tilted with respect to the z-axis while maintaining a high magnification that can be realized when the X-ray irradiation angle is 0, thereby improving the performance of the X-ray generator. You can plan.

  Referring to FIG. 8A, in the conventional apparatus, the window 112 is configured with a large plane, and the concave portion of the work WK (here, the circuit board on which electronic components are mounted) having an uneven surface is formed. Thus, the head 110 could not be brought closer. According to the present embodiment, as shown in FIG. 8B, the head 10 can be brought closer to the recessed portion of the workpiece WK having an uneven surface. As a result, X-ray imaging at a high magnification can be performed. In FIG. 8B, the head 10 having the first configuration is shown, but the same effect can be obtained with the head 10 having another configuration.

  The above-described embodiment is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 X-ray generator 10,110 Head 11,111 Case 11a Case base 11b Case shoulder 11c Case connection part 11d Case fixed end 12,112 Window 12a Window top part 12b Window shoulder part 12c Window base part 13 , 113 Target 31, 131 Vacuum vessel 31a Inclined surface of vacuum vessel 32 Electron beam generator 32a Current introduction terminal of electron beam generator 33 Focusing electrode 40, 140 Table 50 X-ray detector 80 Controller 81 X-ray generator controller 82 Position angle adjustment unit 83 Image generation unit 90 Operation unit PO Interfering position ST1, ST2, ST3 X-ray generator state WK Work d1, d2 Distance between head end and work w Head width

Claims (6)

An X-ray generator,
An X-ray generator head for guiding X-rays generated inside the X-ray generator to an object disposed outside the X-ray generator ;
A main body that constitutes an internal space of reduced pressure in the X-ray generator together with the head,
The body is
A side surface extending in a first direction for directing the X-rays to the object;
An end surface provided at a position closer to the head than the side surface in the first direction and extending in a direction orthogonal to the first direction;
An inclined surface provided between the side surface and the end surface, the inclined surface inclined with respect to each of the side surface and the end surface,
The head is
A case including a fixed end fixed to the main body , the fixed end having a width narrower than a width of the side surface in a direction orthogonal to the first direction ;
Having a higher X-ray transmittance than the case, and a window attached to the case ,
When viewed in cross-section including the direction for guiding the X-ray to the object, the width of the front Kihe head decreases as the distance from the fixed end along a direction for guiding the X-ray to the object, X-ray generator. A target that generates X-rays by irradiation with an electron beam, and the target is disposed closer to the fixed end than the window along the first direction when the case is fixed to the main body. The X-ray generator according to claim 1, further comprising: The X-ray generator according to claim 2, wherein the target is in contact with the window . The X-ray generator according to claim 1, wherein the window includes a protruding portion that protrudes in the first direction from the case when the case is fixed to the main body . The protrusion includes a top and a shoulder that is closer to the case than the top,
The X-ray generator according to claim 4, wherein the flatness of each of the top portion and the shoulder portion is greater than 0 and equal to or less than 1 mm . When viewed in a cross-section including a direction that guides the X-ray to the object, the width of the case decreases with increasing distance from the fixed end,
The X-ray generator according to any one of claims 1 to 3, wherein the window has a flat plate shape and is attached to a position farthest from the fixed end of the case .