JP5263204B2 - X-ray inspection apparatus and X-ray inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To heighten speed of X-ray inspection by simplifying a mechanism for moving an X-ray detector. <P>SOLUTION: This X-ray inspection device following a form of one execution includes: the X-ray detector 23.1 for imaging by using an X-ray; an X-ray detector driving part 22 for moving the X-ray detector; an X-ray source 10 for outputting an X-ray so that the X-ray transmitted through an inspection object domain enters the X-ray detector; an operation part 70 for controlling operation of the X-ray inspection device; and a sensor driving control part for controlling the X-ray detector driving part 22 so that each of a plurality of positions for imaging by the X-ray detector 23.1 exists on the same plane, and that each direction of the X-ray detector on each position becomes constant. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an X-ray inspection method and an X-ray inspection apparatus. In particular, the present invention relates to an imaging method for inspecting an object using X-ray irradiation, and relates to a technique applicable to an X-ray inspection method and an X-ray inspection apparatus.

  In recent years, high integration of LSI (Large-Scale Integration) has progressed with sub-micron microfabrication technology, and it has become possible to load functions previously divided into a plurality of packages into one LSI. The conventional QFP (Quad Flat Package) and PGA (Pin Grid Array) cannot cope with the increase in the number of pins by incorporating the functions required for one package, and recently, especially BGA (Ball Grid Array) and CSP. (Chip Size Package) Package LSI is used. In addition, BGA packages are used even when the number of pins is not so much required for devices such as mobile phones that require ultra-miniaturization.

  LSI BGA and CSP packages greatly contribute to miniaturization, but have a feature that solder parts and the like are not visible from the outside after assembly. Therefore, when inspecting a printed circuit board or the like on which a BGA or CSP package is mounted, quality determination is performed by analyzing a fluoroscopic image obtained by irradiating an inspection target product with X-rays.

  For example, Patent Document 1 discloses an X-ray tomographic plane inspection apparatus that can obtain a clear X-ray image by using an X-ray flat panel detector to detect transmitted X-rays.

  Patent Document 2 discloses a method for reconstructing an image in inclined three-dimensional X-ray CT (Computed Tomography) by arbitrarily selecting an X-ray irradiation angle.

  In Patent Document 3, two-dimensional inspection is performed based on an X-ray image acquired by a parallel X-ray detection apparatus, and three-dimensional inspection is performed based on an X-ray image acquired by an inclined X-ray detection means. An X-ray inspection apparatus capable of performing both inspections at high speed by performing the above is disclosed. Here, there is a reference to a technique for reconstructing a three-dimensional image of an inspection target product based on a plurality of X-ray images. As a reconstruction method, for example, a “filtered back projection method” is cited.

  Patent Document 4 discloses a mechanism that can be driven by a single motor when the X-ray tomography apparatus moves the X-ray source in a linear or circular or spiral orbit to perform tomography. ing. However, since the X-ray source is moved, the X-ray source is heavy and designed to be driven by one motor, so that high-speed movement is difficult. Furthermore, in order to realize three types of movement modes of rotation, straight line, and spiral movement in one imaging system, it has a complicated mechanism, and it is necessary to improve many mechanisms to improve the moving speed. It is difficult to speed up the mechanism.

  Further, in a general industrial X-ray fluoroscopic apparatus, it is desirable that an X-ray fluoroscopic image enlarged as much as possible is obtained when the inspection object is very small. For this purpose, the size of the focal point, which is an X-ray generation region, must be extremely small. Therefore, a microfocus X-ray source which is a transmission X-ray source having a focal size of several μm is used. In such a microfocus X-ray source in order to improve the image quality of the fluoroscopic image, if the electron beam current (X-ray source current) for generating X-rays is increased, the target is heated by the heat generated by the electron collision portion (focus) of the target. In order to melt locally, it is common that an allowable limit value (allowable load) is set. Patent Document 5 discloses a microfocus X-ray source that is a disk in which an anode (target) rotates in order to increase such an allowable load.

  On the other hand, in Patent Document 6, pulsed X-rays are generated by defocusing an electron beam intermittently using a deflection electromagnetic coil for the purpose of extending the life of the X-ray source. A possible pulsed X-ray source is disclosed.

[X-ray CT image reconstruction method]
As described above, in X-ray CT, after passing through an object, at least a cross-sectional image of the object is reconstructed based on an observation value detected by an X-ray detector. Since a three-dimensional X-ray absorption distribution is obtained for the object or a part of the object, as a result, an arbitrary cross-sectional image of the object or a part of the object, that is, X-ray detection. It is possible to reconstruct an image of the surface that intersects the light receiving surface of the device. As such a reconstruction method, an “analytic method” and an “iterative method” are known. Hereinafter, such an image reconstruction method will be briefly summarized.

(Explanation of X-ray projection data)
FIG. 57 is a diagram for explaining an image reconstruction method. X-ray image reconstruction is performed by measuring how much X-rays irradiated from the outside of the inspection object are absorbed (attenuated) by the inspection object from a plurality of angles, thereby obtaining an X-ray absorption coefficient inside the inspection object. This is a technique for obtaining the distribution of.

  In the following description, it is assumed that measurement is performed using a so-called scanning X-ray source as the X-ray source.

  Referring to FIG. 57, the X-rays emitted from the X-ray focal point Fa corresponding to the X-ray detector Da pass through the inspection target (not shown) and reach the pixel Pa of the X-ray detector Da. As the X-rays pass through the inspection object, the X-ray dose (X-ray intensity) is attenuated by an amount corresponding to the inherent X-ray absorption coefficient of each of the components constituting the inspection object. The attenuation amount of the X-ray intensity is recorded as the pixel value of the detector pixel Pa.

  The X-ray intensity emitted from the X-ray focal point Fa is I, the path through which X-rays pass from the X-ray focal point Fa to the detector pixel Pa is t, and the X-ray absorption coefficient distribution in the inspection object is f (x, y, z), the intensity Ia of the X-ray that has reached the detector pixel Pa is expressed by the following equation (1).

  Taking the logarithm of both sides of this equation, the X-ray absorption coefficient distribution along the path t is represented by a line integral value as in the following equation (2). A value obtained by measuring this X-ray absorption coefficient distribution with an X-ray detector is referred to as projection data. That is, the X-ray detector detects an X-ray attenuation distribution (which may be replaced with an X-ray intensity distribution).

(Explanation of analytical method (for example, FBP method: Filtered Back-Projection method: filtered back projection method))
As shown in FIG. 57, when an analytical method is used, an X that is arranged at a position different from the arrangement of the X-ray detector Da with respect to one inspection object (or one part of the inspection object). Projection data for the X-ray intensity Ib emitted from the focal point Fb and reaching the line detector Db is detected. By actually detecting such projection data for a plurality of arrangements for one inspection object (or one part of the inspection object), a cross-sectional image of the inspection object from these projection data Will be reconfigured.

  58 is a top view of the arrangement of the reconstructed pixel V, the X-ray focal points Fa and Fb, and the X-ray detectors Da and Db to be reconstructed among the visual field FOV and the visual field FOV in the inspection target shown in FIG. It is the figure seen from. X-rays that have passed through the reconstructed pixel V form (distance from the focal point to the reconstructed pixel V) pair (distance from the focal point to the X-ray detector) when forming an image on the X-ray detectors Da and Db. An enlarged image is formed according to the ratio of.

  Feldkamp et al. Proposed a reconstruction algorithm for performing three-dimensional image reconstruction based on the equation (2). Since this algorithm (so-called Feldkamp method) is a known technique as shown in Non-Patent Document 1, it will not be described in detail here. Hereinafter, a filtered back projection method, which is one of general methods, will be briefly described.

  An operation for adding the projection data along the path t through which the X-rays pass from the projection data to obtain the X-ray absorption coefficient distribution f (x, y, z) is called back projection. However, if projection data is simply added, blurring occurs due to the point spread function of the imaging system, and thus the projection data is filtered. As this filter, for example, a high-frequency emphasis filter such as a Shepp-Logan filter is used. The direction of filtering is preferably perpendicular to the direction of the X-ray transmission path, but the Feldkamp method performs filtering by approximating the transmission path direction of the projection data to be all the same. Images can be reconstructed.

  The procedure for image reconstruction in the present embodiment will be described below. First, the value pa ′ obtained by filtering the projection data pa of the detector pixel Pa of the X-ray detector Da is added to the pixel value v of the reconstructed pixel V. Further, the value pb ′ obtained by filtering the projection data pb of the detector pixel Pb of the X-ray detector Db is added to the pixel value v of the reconstructed pixel V. Then, v = pa ′ + pb ′. By performing this back projection operation on all X-ray detectors or a part of X-ray detectors, the final pixel value v of the reconstructed pixel V is expressed according to the following equation (3).

  By performing this operation on all the reconstruction pixels V in the reconstruction area (field of view) FOV, the X-ray absorption coefficient distribution to be inspected is obtained and reconstruction image data is obtained.

FIG. 59 is a flowchart showing the processing procedure of such a filter-corrected back projection method.
Referring to FIG. 59, when the processing by the analytical method is started (S5002), first, projection data to be processed is selected from a plurality of projection data captured (S5004). Next, a process for filtering the selected projection data is performed (S5006).

  Further, an unprocessed reconstruction pixel V in the reconstruction field FOV is selected (S5008), and a detector pixel corresponding to the reconstruction pixel V is obtained (S5010).

  Subsequently, the filtered pixel value is added to the reconstructed pixel V (S5012), and it is determined whether all reconstructed pixels have been added (S5014). If the process has not been completed for all the reconstructed pixels, the process returns to step S5008. If the process has been completed, the process proceeds to step S5016.

  In step S5016, it is determined whether all projection data have been processed. If all the projection data has not been completed, the process returns to step S5004. On the other hand, if all the projection data have been completed, the reconstructed image generation ends (S5018).

(Explanation of iterative method (SART))
In the iterative method, the X-ray absorption coefficient distribution f (x, y, z) to be examined and the projection data ln (I / Ia) are regarded as equations and reconstructed.

  FIG. 60 is a conceptual diagram showing the concept of processing in an iterative method when a scanning X-ray source is used. On the other hand, FIG. 61 is a top view of the conceptual diagram of FIG. 60 viewed from above.

  Hereinafter, a procedure for reconfiguration by an iterative method will be described with reference to FIGS. 60 and 61. A vector ν in which the pixel values of the reconstructed image are arranged in a line (the head is attached to represent the vector: hereinafter referred to as “ν” in the text body), and a vector p in which the projection data is arranged in a line (vector) Is represented by the following formula (4) and formula (5).

  In the following, for example, the pixel for the image calculated when the X-ray from the X-ray focal point Fa is connected to the X-ray detector Da when the value of the reconstructed pixel V is assumed to be a certain value is referred to as the intermediate projection pixel Qa. A pixel actually observed on the X-ray detector Da is called a detector pixel Pa. The X-ray detector Db is also referred to as an intermediate projection pixel Qb and a detector pixel Pb, respectively.

  In an iterative approach, for the assumed reconstructed pixel vector ν and the corresponding intermediate projection data vector q, the intermediate projection data vector q is the actual measured detector pixel value, as described below. The solution ν is obtained by an iterative operation that updates the assumed vector ν until Pa or Pb can be regarded as coincident with the projection data.

  Here, J is the number of pixels in the reconstruction area (field of view), and I is the number of pixels in the projection data. T represents transposition. A projection operation relating ν and p is represented by an I × J coefficient matrix of the following equation (6).

  At this time, the image reconstruction by the iterative method can be formulated as a problem for obtaining ν by solving the following linear equation (7).

  In other words, the contribution of vj to pi is wij. Note that W represents how much the pixel value ν of the reconstructed image contributes to the pixel value p of the projection data, and can be obtained from the geometric position of the X-ray focal point and the X-ray detector, Sometimes called detection probability or weight.

  As the iterative method, a method of algebraically solving an equation, a method considering statistical noise, and the like have been devised. ). Details are described in Non-Patent Document 2.

In SART, first, an initial reconstructed image ν ⁰ represented by the following equation (8) is assumed (the head is attached to represent a vector: hereinafter referred to as “ν ⁰ ” in the text body). .

The initial reconstructed image ν ⁰ may be all zero data, or data acquired from CAD (Computer Aided Design) data or the like may be assumed.

Next, using the projection operation W, intermediate projection data q ⁰ represented by the following expression (9) is attached to the head to represent a vector: hereinafter referred to as “q ⁰ ” in the text body. Generate.

The generation of the intermediate projection data q ⁰ may be performed for one projection data or a plurality of projection data. In the following description, it is assumed that the process is performed on one piece of projection data.

The generated intermediate projection data q ⁰ is compared with the projection data p acquired from the X-ray detector. The comparison method includes a method of taking a difference and a method of dividing, but in SART, a difference (p−q ⁰ ) is taken.

The initial reconstructed image ν ⁰ is updated. The formula used for updating (iteration formula) is as shown in formula (10).

Note that the following calculation formulas (11) and (12) in the formula (10) can be calculated in advance to reduce the update calculation time.

Reconstructed image data is obtained by substituting the reconstructed image generated by the above calculation as an initial image and repeating the same process a plurality of times.

FIG. 62 is a flowchart for explaining the process of the iterative method.
Referring to FIG. 62, first, when processing by an iterative method is started (S5102), an initial reconstructed image is set (S5104). As described above, as the initial reconstructed image, for example, all values may be zero. Next, projection data to be processed is selected from a plurality of projection data corresponding to a plurality of X-ray detector positions (S5106).

  Intermediate projection data is generated. The method for generating the intermediate projection data is as described above. (S5108).

Further, an unprocessed reconstruction pixel V in the reconstruction field of view FOV is selected (S5110).
A detector pixel corresponding to the reconstructed pixel is obtained (S5112).

Based on the iterative formula, the value of the reconstructed pixel V is updated (S5114).
Next, it is determined whether or not all the reconstructed pixels have been updated (S5116). If the process has not been completed for all the reconstructed pixels, the process returns to step S5110. If the process has been completed, the process proceeds to step S5110. The process moves to S5118.

  In step S5118, it is determined whether all projection data have been processed. If all the projection data has not been completed, the process returns to step S5106. On the other hand, if the processing has been completed for all projection data, the process proceeds to step S5120.

  In step S5120, it is determined whether the process has been performed a predetermined number of times. If the process has not been repeated, the process returns to step S5104, the current reconstructed pixel value is adopted as the initial reconstructed image, and the process is repeated. Is repeated a predetermined number of times, the reconstructed image generation ends (S5022).

  As described above, a three-dimensional image of the inspection object can be reconstructed from the projection data acquired by the X-ray detector.

  However, in the analytical method, in order to obtain each of the plurality of projection data for reasons such as the ease of calculation when the filtering process is performed on each pixel of the X-ray detector, the X-ray detector and the focus are acquired. Even when the relative position between the object and the object is changed, it is desirable that the relative arrangement of the X-ray focal point and the X-ray detector maintain a certain relationship. In other words, when the X-ray detector is viewed from the focal point, even if the angle of the portion included in the field of view of the target object within the solid angle to be seen, the position in the target object, and the like change, It is desirable that the positional relationship of be kept constant. Moreover, when performing the back projection method as described above, in order to reduce artifacts and the like, it is desirable that a plurality of projection data be acquired for each equiangular portion of the portion included in the field of view of the object.

  In contrast, in the iterative method, there is no such restriction on the relative arrangement of the X-ray focus and the X-ray detector.

JP 2000-46760 A JP 2003-344316 A JP 2006-162335 A Japanese Patent Publication No. 5-86218 JP 2001-273860 A JP 2005-347174 A

L. A. Feldkamp, L.M. C. Davis and J.M. W. Kress, “Practical cone-beam algorithm”, Journal of the Optical Society of Famerica. A, 612-619 (1984). A. H. Anderson and A.M. C. Kak, “SIMULTANEUS ALGEBRAIC RECONSTRUCTIONTECHNIQUE (SART): A SUPERRIOR IMPLEMENTATION OF THE ALGOITHM”, ULTRASONIC IMAGEING 6, 81-94 (1984)

  However, in-line inspection in a factory requires that all products are inspected, and therefore, from the viewpoint of manufacturing efficiency, it is necessary to shorten the time required for X-ray inspection.

  Further, in the conventional X-ray imaging technology related to the X-ray inspection described above, if the area of the inspection area that can be reconfigured is increased, it takes time to perform imaging and 3D (reconstruction) calculation. For example, in order to inspect a printed circuit board or the like as described above, it is often sufficient to obtain images of a plurality of specific parts instead of the entire inspection target. In such a case, when the part to be inspected with respect to the inspection object is arranged in the form of an enclave, an X-ray detector that can make the inspection object the area (or volume) encompassing the whole is an apparatus. It is not efficient from the viewpoint of increasing the size of the system and increasing the calculation load.

  Further, in the conventional X-ray imaging technique related to the X-ray inspection described above, it is necessary to move the imaging system or the workpiece to be inspected to change the inspection area, and the number of movable parts increases. This is related not only to the problem of the time required for the X-ray inspection described above, but also to the cost for manufacturing the drive part, maintainability, and reliability. For example, when inspecting a printed board or the like as described above, the part to be inspected is often a part of the printed board placed on the stage. Moreover, in such a case, in order to make the obtained X-ray image an enlarged image, the X-ray detector is driven at a position relatively far from the inspection object, but the portion to be inspected is Since it is a minute portion, it is necessary to control the driving of the imaging system with extremely high accuracy. For this reason, the drive mechanism of the image pickup system must be able to pick up necessary images with as few degrees of freedom as possible.

  The present invention has been made to solve the above-described problems, and an object thereof is an X-ray inspection apparatus capable of selectively inspecting a predetermined inspection area of an inspection object at high speed, and this An X-ray inspection method using such an X-ray imaging method is provided.

  Another object of the present invention is to provide an X-ray inspection apparatus with reduced movable parts, low cost, excellent maintainability and reliability, and an X-ray inspection method using such an X-ray imaging method. It is.

  Still another object of the present invention is to provide an X-ray inspection apparatus capable of inspecting a plurality of parts of an inspection object at high speed without moving the inspection object, and an X-ray using such an X-ray imaging method. It is to provide a line inspection method.

  According to one aspect of the present invention, an X-ray inspection apparatus for executing an image reconstruction process on an inspection target region by receiving X-rays transmitted through the inspection target region of the target object on a plurality of detection surfaces. A plurality of X-ray detectors for imaging on a plurality of detection planes, detector driving means for independently moving each X-ray detector, and a plurality of X-rays transmitted through the examination region X-ray output means for outputting X-rays correspondingly so as to be incident on a plurality of X-ray detectors moved to the position, and control means for controlling the operation of the X-ray inspection apparatus. Image acquisition control means for controlling the exposure timing of the X-ray detector and detector driving means, X-ray output control means for controlling the X-ray output means, and inspection target areas detected by a plurality of detection surfaces Inspection target based on X-ray intensity distribution data transmitted through Image reconstruction processing means for reconstructing the image data of the area, and the image acquisition control means and the X-ray output control means are configured such that a part of the plurality of X-ray detectors is a first of the plurality of imaging positions. The process of exposing at this position and the process of moving another part different from the part to the second position among the plurality of imaging positions are executed in parallel.

  Preferably, the image acquisition control unit and the X-ray output control unit divide imaging at a predetermined number of imaging positions with respect to the reconstruction of the image data into a plurality of times for the inspection target region of one target object. In order to perform, a process of exposing a part of the plurality of X-ray detectors at an imaging position to be imaged this time among the first positions, a process of moving to an imaging position corresponding to imaging after the second time, a plurality of The process of moving the other part of the X-ray detector to the imaging position corresponding to the next imaging in the second position and the process of exposing at the next imaging position are alternately executed in parallel.

  Preferably, the detector driving means includes uniaxial driving means for independently moving a plurality of X-ray detectors along a predetermined uniaxial direction.

Preferably, the uniaxial driving means moves the plurality of X-ray detectors in parallel within a predetermined plane.
Preferably, the X-ray output control means sets, for a plurality of detection surfaces, each of the X-ray emission start positions so that the X-rays pass through the inspection target region and enter each detection surface. X-ray output means generates X-rays by moving the X-ray focal point position of the X-ray source to each starting point position.

  Preferably, the X-ray output means has a plurality of X-ray focus positions respectively corresponding to a plurality of X-ray detectors that are simultaneously exposed among the plurality of X-ray detectors arranged at the imaging position. X-rays are generated from the X-ray output means, and the X-rays from the X-ray output means pass through the inspection target region from the corresponding X-ray focal position to each of the X-ray detectors that are simultaneously exposed to each detection. The apparatus further includes a shielding member that transmits X-rays incident on the surface while shielding X-rays from X-ray focal positions that do not correspond to each other.

  Preferably, the X-ray output means moves the X-ray source focal position by deflecting an electron beam irradiated onto a target surface which is a continuous surface of the X-ray source, and the X-ray output control means The X-ray output means is controlled so that the X-rays are incident on each X-ray detector in a time division manner.

  Preferably, the detector driving means includes parallel driving means for moving the plurality of X-ray detectors in parallel within a predetermined plane.

  Preferably, the detector driving means includes biaxial driving means for independently moving a plurality of X-ray detectors along a predetermined biaxial direction.

  Preferably, the detection surfaces of the plurality of X-ray detectors each have a rectangular shape, and the detector driving means has a direction in which one end of the detection surfaces of the plurality of X-ray detectors faces the X-ray output means at each imaging position. Rotating means for rotating a plurality of X-ray detectors so as to intersect with each other.

  Preferably, the image reconstruction processor reconstructs the image data of the inspection target area by an iterative method.

  Preferably, the image reconstruction processing unit reconstructs the image data of the inspection target region by an analytical method.

  According to another aspect of the present invention, an X-ray inspection apparatus for performing an image reconstruction process on an inspection target region by receiving X-rays transmitted through the inspection target region of an object on a plurality of detection surfaces. A plurality of X-ray detectors for imaging on a plurality of detection surfaces, detector driving means for moving each X-ray detector along a predetermined one-axis direction, and X-rays that have passed through the inspection target region Includes X-ray output means for outputting X-rays so as to be incident on a plurality of X-ray detectors moved to a plurality of imaging positions, and control means for controlling the operation of the X-ray inspection apparatus. The control means includes an image acquisition control means for controlling the exposure timing of each X-ray detector and the detector driving means, an X-ray output control means for controlling the X-ray output means, and a plurality of detection surfaces. Detected X-ray intensity distribution data transmitted through the inspection area Hazuki, and an image reconstruction processing means for reconstructing the image data of the inspection area.

Preferably, the uniaxial driving means moves the plurality of X-ray detectors in parallel within a predetermined plane.
Preferably, the X-ray output control means sets, for a plurality of detection surfaces, each of the X-ray emission start positions so that the X-rays pass through the inspection target region and enter each detection surface. X-ray output means generates X-rays by moving the X-ray focal point position of the X-ray source to each starting point position.

  Preferably, the X-ray output means has a plurality of X-ray focus positions respectively corresponding to a plurality of X-ray detectors that are simultaneously exposed among the plurality of X-ray detectors arranged at the imaging position. X-rays are generated from the X-ray output means, and the X-rays from the X-ray output means pass through the inspection target region from the corresponding X-ray focal position to each of the X-ray detectors that are simultaneously exposed to each detection. The apparatus further includes a shielding member that transmits X-rays incident on the surface while shielding X-rays from X-ray focal positions that do not correspond to each other.

  Preferably, the X-ray output means moves the X-ray source focal position by deflecting an electron beam irradiated onto a target surface which is a continuous surface of the X-ray source, and the X-ray output control means The X-ray output means is controlled so that the X-rays are incident on each X-ray detector in a time division manner.

  Preferably, the image reconstruction processing unit reconstructs the image data of the inspection target area by an iterative method.

  According to still another aspect of the present invention, X-rays transmitted through the inspection target region of the object are received by X-ray detectors corresponding to the plurality of detection surfaces, respectively, thereby performing an image reconstruction process on the inspection target region. An X-ray inspection method for performing a step of independently moving each X-ray detector to a corresponding imaging position, and a plurality of X-rays that have passed through the inspection target area and moved to a plurality of imaging positions, respectively A step of outputting X-rays so as to enter the X-ray detector, a process of exposing a part of the plurality of X-ray detectors at a first position among the plurality of imaging positions, and a part A step of executing a process of moving another different part to the second position of the plurality of imaging positions in parallel, and an intensity distribution of the X-rays transmitted through the examination region detected by the plurality of detection surfaces Based on the data of And a step of configuring.

  Preferably, the step executed in parallel is performed in a plurality of times at a predetermined number of imaging positions with respect to the reconstruction of the image data for the inspection target region of one target object. A process for exposing a part of the plurality of X-ray detectors at the current imaging position in the first position and a process for moving to an imaging position corresponding to imaging after the second time; and a plurality of X-ray detectors A step of alternately executing a process of moving the second part of the second position to an image pickup position corresponding to the next image pickup and a process of exposing at the next image pickup position in parallel in the second position is included.

  Preferably, in the step of outputting X-rays, the X-ray source focal position is moved by deflecting an electron beam irradiated onto a target surface which is a continuous surface of the X-ray source, and at the same time, the X-ray is in an exposure state. The method includes outputting X-rays so that the X-rays are incident on each detector in a time division manner.

  According to still another aspect of the present invention, X-rays transmitted through the inspection target region of the object are received by X-ray detectors corresponding to the plurality of detection surfaces, respectively, thereby performing an image reconstruction process on the inspection target region. An X-ray inspection method for performing a plurality of steps in which each X-ray detector is moved to a corresponding imaging position along a predetermined one-axis direction, and a plurality of X-rays transmitted through the inspection target region Based on the step of outputting X-rays so as to be incident on the plurality of X-ray detectors moved to the position and the intensity distribution data of the X-rays transmitted through the inspection region detected on the plurality of detection surfaces Reconstructing the image data.

  Preferably, among a plurality of X-ray detectors, in order to perform imaging at a predetermined number of imaging positions with respect to reconstruction of image data in a plurality of times for an inspection target region of one target object A part of the X-ray detector, a process of exposing at a current imaging position, a process of moving to an imaging position corresponding to imaging after the second time, and an imaging corresponding to the next imaging of the other part of the plurality of X-ray detectors A step of alternately executing the process of moving to the position and the process of exposing at the next imaging position in parallel is further provided.

  Preferably, in the step of outputting X-rays, the X-ray source focal position is moved by deflecting an electron beam irradiated onto a target surface which is a continuous surface of the X-ray source, and at the same time, the X-ray is in an exposure state. The method includes outputting X-rays so that the X-rays are incident on each detector in a time division manner.

  According to the X-ray inspection method and the X-ray inspection apparatus according to the present invention, a predetermined inspection area of an inspection object can be selectively inspected at high speed.

  Alternatively, according to the X-ray inspection method and the X-ray inspection apparatus according to the present invention, it is possible to perform an X-ray inspection excellent in maintainability and reliability at a low cost by reducing the movable parts.

  Alternatively, according to the X-ray inspection method and the X-ray inspection apparatus according to the present invention, it is possible to inspect a plurality of portions of an inspection object at high speed.

1 is a schematic block diagram of an X-ray inspection apparatus 100 according to the present invention. 2 is a cross-sectional view showing a configuration of a scanning X-ray source 10. FIG. It is a conceptual diagram which shows the example of a 1st moving mechanism. It is a conceptual diagram which shows the example of a 2nd moving mechanism. It is a conceptual diagram which shows the example of a 3rd moving mechanism. It is a flowchart of the whole test | inspection for a reconfiguration | reconstruction image test | inspection for the moving mechanism in any one of FIGS. It is a timing chart of the whole test | inspection according to the flowchart demonstrated in FIG. FIG. 7 is a flowchart showing processing for CT imaging of one field of view described in FIG. 6. FIG. FIG. 9 is a timing chart of a process of performing imaging in a plurality of directions in the process of CT imaging of one field of view described in FIG. 8. It is a figure for demonstrating the structure of the X-ray inspection apparatus 100 of Embodiment 1. FIG. In the configuration of the X-ray inspection apparatus 100 shown in FIG. 10, the movement trajectory between the X-ray detector 23 and the scanning X-ray source is a top view. 3 is a flowchart of the entire inspection for a reconstructed image inspection performed by the X-ray inspection apparatus 100 according to the first embodiment. 13 is a flowchart of CT imaging of one field of view in step S310 described in FIG. FIG. 14 is a timing chart showing the operations of the X-ray detector and the X-ray focal position along the inspection time in the inspection flow shown in FIG. 13. It is a figure explaining the structure of the X-ray inspection apparatus 102 of the modification of Embodiment 1. FIG. FIG. 16 is a top view showing movement trajectories of the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 102 shown in FIG. 15. FIG. 16 is a top view showing another movement locus of the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 102 shown in FIG. 15. FIG. 18 is a flowchart of inspection when the X-ray detector 23 is moved and inspected as shown in FIG. 16 or FIG. 17. FIG. 19 is a timing chart illustrating operations of an X-ray detector and an X-ray focal position along the inspection time in the inspection flow illustrated in FIG. 18. It is a figure explaining the structure of the X-ray inspection apparatus 104 of Embodiment 2. FIG. 4 is a top view of a shield 66. FIG. In the configuration of the X-ray inspection apparatus 104 shown in FIG. 20, the movement trajectory between the X-ray detector 23 and the scanning X-ray source is a top view. FIG. 21 is a top view showing another movement locus of the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 104 shown in FIG. 20. It is a figure which shows the flowchart of the test | inspection at the time of test | inspecting by moving the X-ray detector 23 like FIG. 22 or FIG. FIG. 25 is a timing chart showing operations of the X-ray detector and the X-ray focal position along the inspection time in the inspection flow shown in FIG. 24. It is a conceptual diagram for demonstrating the area | region which can be made into a test | inspection area | region by CT imaging about one visual field in order to perform image reconstruction using an analytical method. It is a timing chart of the conventional imaging system in which a visual field (inspection object) rotates. It is a figure explaining CT imaging time of 1 visual field. It is a figure explaining the structure of the X-ray inspection apparatus 106 of Embodiment 3. FIG. In the configuration of the X-ray inspection apparatus 106 shown in FIG. 29, the movement trajectory between the X-ray detector 23 and the visual field to be inspected is a top view. It is CT imaging flowchart of an imaging system using a translational detector. It is a conceptual diagram which shows the test | inspection area | region of the imaging system using a translation X-ray detector. It is a timing chart of an imaging system using a translation X-ray detector. It is a figure which shows the structure of the X-ray inspection apparatus which performs the imaging using four detectors and a scanning X-ray source. It is CT imaging flowchart of the X-ray inspection apparatus 900 shown in FIG. FIG. 36 is a timing chart showing operations of the X-ray detector and the X-ray focal position along the inspection time in the inspection flow shown in FIG. 35. It is a block diagram for demonstrating the structure of the X-ray inspection apparatus 110 of Embodiment 4. FIG. 2 is a conceptual diagram showing a configuration of a detector used as an X-ray detector 23. FIG. FIG. 38 is a top view showing movement trajectories of the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 110 shown in FIG. 37. It is a flowchart of 1 visual field imaging by the structure of the X-ray inspection apparatus 110 shown in FIG. It is a timing chart for demonstrating scanning X-ray source operation | movement at the time of using four X-ray detectors 23.1-23.4. It is a timing chart of 1 visual field imaging in the X-ray inspection apparatus 110 shown in FIG. It is a conceptual diagram which shows the structure of a scanning X-ray source. It is a block diagram for demonstrating the structure of the X-ray inspection apparatus 120 of Embodiment 5. FIG. It is a figure which shows the operation example of the imaging system using a translation X-ray detector. FIG. 46 is a flowchart of inspection processing for one field of view of the imaging system described in FIGS. 44 and 45. FIG. FIG. 46 is an inspection timing chart for one visual field of the imaging system described with reference to FIGS. 44 and 45. FIG. 46 is an inspection timing chart for the entire inspection of the imaging system described in FIG. 44 and FIG. 45. It is a figure explaining the structure of the X-ray inspection apparatus 122 of the modification of Embodiment 5. FIG. It is a figure which shows the operation example of the imaging system using the translation X-ray detector of the X-ray inspection apparatus 122. FIG. 51 is a flowchart of an inspection process for one field of view of an imaging system using the linear movement detector described in FIGS. 49 and 50. FIG. FIG. 51 is an inspection timing chart for one visual field of the imaging system described in FIGS. 49 and 50. It is a figure explaining the structure of the X-ray inspection apparatus 130 of Embodiment 6. FIG. FIG. 56 is a top view showing the movement trajectory between the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 130 shown in FIG. 53. FIG. 55 is a flowchart of an imaging system inspection process using the linear movement detector described in FIGS. 53 and 54. FIG. FIG. 55 is an inspection timing chart of imaging with respect to one visual field by the imaging system described in FIGS. 53 and 54. FIG. It is a figure for demonstrating the image reconstruction method. It is the figure which looked at the arrangement | positioning of the reconstruction pixel V, X-ray focus Fa, Fb and X-ray detector Da, Db of the calculation object of reconstruction of the visual field FOV from the upper surface. It is a flowchart which shows the process sequence of a filter correction | amendment back projection method. It is a conceptual diagram which shows the concept of the process by an iterative method at the time of using a scanning X-ray source. FIG. 61 is a top view of the conceptual diagram of FIG. 60 viewed from above. It is a flowchart for demonstrating the process of an iterative method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Embodiment 1]
(1. Configuration of the present invention)
FIG. 1 is a schematic block diagram of an X-ray inspection apparatus 100 according to the present invention.

  An X-ray inspection apparatus 100 according to the present invention will be described with reference to FIG. However, the configurations, dimensions, shapes, and other relative arrangements described below are not intended to limit the scope of the present invention only to those unless otherwise specified.

  The X-ray inspection apparatus 100 includes a scanning X-ray source 10 that outputs X-rays with a central axis as an axis 21, and a plurality of X-ray detectors 23.1 to 23. N is attached and, as will be described later, each X-ray detector 23.1-23. And an X-ray detector driving unit 22 for driving N to a designated position. Further, the scanning X-ray source 10 and the X-ray detectors 23.1 to 23. An inspection object 20 is arranged between N and N. Furthermore, the X-ray inspection apparatus 100 includes X-ray detectors 23.1 to 23.X by the X-ray detector driving unit 22. N drive and X-ray detectors 23.1 to 23. An image acquisition control mechanism 30 for controlling acquisition of image data from N, an input unit 40 for receiving an instruction input from a user, and an output unit 50 for outputting measurement results and the like to the outside. . The X-ray inspection apparatus 100 further includes a scanning X-ray source control mechanism 60, a calculation unit 70, and a memory 90. In such a configuration, the calculation unit 70 executes a program (not shown) stored in the memory 90 to control each unit, and performs predetermined calculation processing.

  The scanning X-ray source 10 is controlled by the scanning X-ray source control mechanism 60 and irradiates the inspection target 20 with X-rays.

FIG. 2 is a cross-sectional view showing the configuration of the scanning X-ray source 10.
Referring to FIG. 2, in scanning X-ray source 10, electron beam 16 is irradiated onto target 11 such as tungsten from electron gun 19 controlled by electron beam control unit 62. Then, X-rays 18 are generated and emitted (output) from the place where the electron beam 16 collides with the target (X-ray focal position 17). The electron beam system is housed in the vacuum vessel 9. The inside of the vacuum vessel 9 is kept in a vacuum by a vacuum pump 15, and an electron beam 16 accelerated by a high voltage power source 14 is emitted from an electron gun 19.

  In the scanning X-ray source 10, the electron beam 16 is converged by the electron beam converging coil 13, and then deflected by the deflection yoke 12, so that the location where the electron beam 16 collides with the target 11 is arbitrarily determined. Can be changed. For example, the electron beam 16a deflected by the deflection yoke 12 collides with the target 11, and the X-ray 18a is output from the X-ray focal position 17a. Similarly, the electron beam 16b deflected by the deflection yoke 12 collides with the target 11, and an X-ray 18b is output from the X-ray focal position 17b. Unless otherwise specified, in the present invention, the scanning X-ray source 10 is a transmissive type. Further, as will be described later, X-rays are emitted from a position (hereinafter referred to as “X-ray emission starting position”) that should be the starting point of X-ray emission set according to the inspection target portion of the inspection object. In order to generate the target, it is desirable that the target is not a ring but a continuous surface so that the degree of freedom in setting the position can be increased. Further, in the following description, when the positions are not particularly distinguished and described, they are simply indicated as the X-ray focal position 17 as a generic name.

  In addition, in order to move the X-ray focal point position to each starting point position of the X-ray radiation described above, for example, the position of the X-ray source itself can be mechanically moved each time. However, in the configuration as shown in FIG. 2, when the X-ray focal point position is moved to the X-ray emission starting position, the X-ray source is mechanically moved within a certain range. An X-ray inspection apparatus excellent in maintainability and reliability can be realized without necessity. As will be described later, a plurality of X-ray sources can be provided and switched according to the starting point position.

  In other words, the “starting position of X-ray radiation” refers to the X-ray detector 23. If the spatial position of i (i is one specified from 1 to N) and the spatial position of the inspection target part of the inspection target 20 are specified, the spatial position that can be specified The X-ray focal position means the position on the target where X-rays are actually output. Therefore, in order to bring the X-ray focal position to the “X-ray emission starting position”, it is possible to scan the electron beam with a scanning X-ray source, or mechanically move the X-ray source itself. It may be moved.

  Returning to FIG. 1, the scanning X-ray source control mechanism 60 includes an electron beam control unit 62 that controls the output of the electron beam. The electron beam control unit 62 receives an X-ray focal position and X-ray energy (tube voltage, tube current) designation from the calculation unit 70. X-ray energy varies depending on the configuration of the inspection object.

  The inspection object 20 is a scanning X-ray source 10 and an X-ray detector 23 (hereinafter, when “X-ray detectors 23.1 to 23.N” are collectively referred to as “X-ray detector 23”). It is arranged between. When the position of the inspection object 20 is moved, it may be moved to an arbitrary position on the XYZ stage, or arranged in a position for inspection by moving in one direction like a belt conveyor. You may do it. If the inspection target is small like a printed circuit board, the scanning X-ray source 10 and the X-ray detector 23 may be fixed and the inspection target may be moved as described above. When the object has a large area and it is difficult to arbitrarily move the inspection object side, the relative position between the scanning X-ray source 10 and the X-ray detector 23 is fixed and the scanning X-ray source 10 is fixed. The X-ray detector 23 may be moved.

  The X-ray detector 23 is a two-dimensional X-ray detector that detects and images the X-rays output from the scanning X-ray source 10 and transmitted through the inspection object 20. For example, a CCD (Charge Coupled Device) camera, I.D. I. (Image Intensifier) tube. In the present invention, since a plurality of X-ray detectors are arranged in the X-ray detector driving unit 22, a space-efficient FPD (flat panel detector) is desirable. Further, it is desirable to have high sensitivity so that it can be used for in-line inspection, and it is particularly desirable to use a direct conversion FPD using CdTe.

Details of the configuration of the X-ray detector driving unit 22 will be described later.
The image acquisition control mechanism 30 includes a detector drive control unit 32 for controlling the X-ray detector drive unit 22 to move the X-ray detector 23 to a position specified by the calculation unit 70, and a calculation unit 70. And an image data acquisition unit 34 for acquiring image data of the designated X-ray detector 23. Note that there may be one X-ray detector or a plurality of X-ray detectors that are simultaneously designated as acquiring image data from the arithmetic unit 70 depending on the imaging situation, as will be described later.

  The position of the X-ray detector 23 driven by the X-ray detector drive unit 22 can be known by a position sensor (not shown), and can be taken into the calculation unit 70 via the detector drive control unit 32.

  Moreover, it is desirable that the X-ray detector driving unit 22 can be moved up and down in order to adjust the enlargement ratio. In this case, the vertical position of the X-ray detector drive unit 22 can be known by a sensor (not shown), and can be taken into the calculation unit 70 via the detector drive control unit 32.

The input unit 40 is an operation input device for receiving user input.
The output unit 50 is a display for displaying an X-ray image or the like configured by the calculation unit 70.

  That is, the user can execute various inputs via the input unit 40, and various calculation results obtained by the processing of the calculation unit 70 are displayed on the output unit 50. The image displayed on the output unit 50 may be output for visual quality judgment by the user, or may be output as a quality judgment result of a quality judgment unit 78 described later.

  The calculation unit 70 includes a scanning X-ray source control unit 72, an image acquisition control unit 74, a 3D image reconstruction unit 76, a pass / fail determination unit 78, an inspection target position control unit 80, and an X-ray focal position calculation unit 82. And an imaging condition setting unit 84.

  The scanning X-ray source control unit 72 determines the X-ray focal position and X-ray energy, and sends a command to the scanning X-ray source control mechanism 60.

  The image acquisition control unit 74 determines the X-ray detector 23 that acquires an image from among the X-ray detectors 23 driven to the specified position by the X-ray detector driving unit 22, and issues a command to the image acquisition control mechanism 30. send. Further, image data is acquired from the image acquisition control mechanism 30.

  The 3D image reconstruction unit 76 reconstructs three-dimensional data from a plurality of image data acquired by the image acquisition control unit 74.

  The quality determination unit 78 determines the quality of the inspection target based on the 3D image data or the perspective data reconstructed by the 3D image reconstruction unit 76. For example, the quality is determined by recognizing the shape of the solder ball and determining whether or not the shape is within a predetermined allowable range. Note that the algorithm for performing pass / fail judgment or the input information to the algorithm is obtained from the imaging condition information 94 because it differs depending on the inspection target.

  The inspection symmetry position control unit 80 controls a mechanism (not shown) for moving the inspection object 20, for example, a stage.

  When inspecting an inspection area where the inspection object 20 is present, the X-ray focal position calculation unit 82 calculates an X-ray focal position and an irradiation angle with respect to the inspection area. Details will be described later.

  The imaging condition setting unit 84 sets conditions for outputting X-rays from the scanning X-ray source 10 according to the inspection object 20. For example, the applied voltage to the X-ray source and the imaging time.

  The memory 90 relates to X-ray focal position information 92 in which the X-ray focal position calculated by the X-ray focal position calculator 82 is stored, imaging conditions set by the imaging condition setting unit 84, and an algorithm for determining pass / fail. In addition to the imaging condition information 94 in which information and the like are stored, a program for realizing each function executed by the arithmetic unit 70 described above is included. The memory 90 only needs to be able to store data, and includes a storage device such as a RAM (Random Access Memory), an EEPROM (Electrically Erasable and Programmable Read-Only Memory), and an HDD (Hard Disc Drive).

(Configuration of X-ray detector driving unit 22: Configuration for independent detector movement)
In the X-ray inspection apparatus 100, (the number of X-ray detectors) << (the number of images necessary for reconstruction). This is because it is not practical to provide detectors for the required number of images at a time from the viewpoint of cost required for FPD. Therefore, it is necessary to mechanically move (X-ray detector) / (X-ray source (X-ray source)) / (stage with inspection object) at the time of imaging exceeding the number of X-ray detectors. The imaging process cannot be performed during such mechanical movement.

  As will be described below, the X-ray inspection apparatus 100 according to the first embodiment can reduce this idle time that does not contribute to speeding up the entire system.

(Problems of loss of imaging processing time due to mechanical movement)
Hereinafter, as a premise for explaining the configuration and operation of the X-ray inspection apparatus 100 according to the first embodiment, it is possible to mechanically move the imaging system or the inspection target in a configuration that can be assumed as another X-ray inspection apparatus. The outline of the structure of the moving mechanism part to be performed and its problems will be described.

  FIG. 3 is a conceptual diagram illustrating an example of the first moving mechanism. In FIG. 3, the X-ray source (X-ray source) and the X-ray detector are fixed, and the field of view is mechanically moved (rotated), thereby obtaining a plurality of imaging numbers necessary for reconstruction.

  FIG. 4 is a conceptual diagram illustrating an example of the second moving mechanism. In FIG. 4, the X-ray detector is mechanically translated in the XY plane and rotated in the θ direction, and the visual field (inspected portion to be inspected) is also translated in the XY plane. To obtain a plurality of images to be reconstructed.

  FIG. 5 is a conceptual diagram illustrating an example of a third moving mechanism. In FIG. 5, the X-ray detector is mechanically rotated in the θ direction, and the field of view (inspection part to be inspected) is also translated in the XY plane, thereby obtaining a plurality of imaging numbers necessary for reconstruction. obtain.

  As will be described in detail below, in order to obtain a plurality of imaging data in any of the above-described FIGS. 3 to 5, mechanical movement of the imaging system or the inspection target occurs, and imaging is performed during this movement. This travel time hinders system speedup.

  FIG. 6 is a diagram showing a flowchart of the entire inspection for reconstructed image inspection of any one of the moving mechanisms in FIGS. 3 to 5.

  Referring to FIG. 6, first, when the process is started (S100), the inspection portion (field of view) to be inspected is moved to a position where it can be imaged (S102). That is, in order to capture a fluoroscopic image, the stage on which the inspection object is placed and the X-ray detector are moved to a predetermined position.

  Then, a fluoroscopic image is captured (S104), the fluoroscopic image is inspected, and the quality of the visual field to be inspected (the range captured by the fluoroscopic image) is determined from the acquired fluoroscopic image (S106).

Subsequently, it is determined whether or not inspection by a reconstructed image is necessary (S108).
If the inspection using the reconstructed image is not necessary, the inspection ends (S118).

  On the other hand, if inspection by a reconstructed image is necessary, CT imaging for one field of view is subsequently performed (S110). In CT imaging, the visual field (reconstruction region or region similar to the above-described fluoroscopic image imaging range) in the inspection object is imaged from a plurality of directions.

  Next, a reconstructed image is generated from captured images in a plurality of directions (S112). Subsequently, the quality determination by the reconstructed image is performed (S114).

  Further, it is determined whether or not the entire visual field inspection has been completed (S116). If the inspection has not been completed, the process returns to step S102. On the other hand, if the inspection has been completed for the entire visual field, the inspection is ended (S118).

FIG. 7 is a timing chart of the entire inspection according to the flowchart described in FIG.
In the following description, it is assumed that the inspection object is divided into M (for example, 4) fields of view and N images are captured as CT imaging. The definitions of symbols are shown below.

  At this time, the time for imaging the entire inspection target is Ti, the time for imaging one field of view is Tv, the time required for mechanical movement (movement of the stage, X-ray detector, etc.) is Tm, and imaging (X Let Ts be the exposure time of the line detector.

  As shown in FIG. 7, the CT imaging time Ti of the entire inspection object is an image of M fields of view, and is the sum of (M−1) times of mechanical movement time Te (field of view movement time). It is represented by the following formula (13).

Ti = MTv + (M-1) Te (13)
FIG. 8 is a flowchart showing the process of CT imaging of one field of view described in FIG.

  Referring to FIG. 8, when CT imaging of one field of view is started (S200), first, the imaging system and / or inspection object is moved to the imaging position for the current field of view (S202). The imaging position can be automatically calculated from design information such as CAD data. Since the inspection target is on the stage, the visual field can be moved along with the movement or rotation of the stage.

  Next, the field of view to be inspected is imaged (S204). Imaging data to be inspected is obtained by irradiating an X-ray from an X-ray source and exposing an X-ray detector. The exposure time can be determined in advance from the size of the inspection object and the intensity of the X-ray generated by the X-ray source.

  Subsequently, the image data captured by the X-ray detector is transferred to the calculation unit (S206). That is, in order to reconstruct the captured image data, the captured image data is transferred to a calculation unit that performs reconstruction processing.

  Subsequently, it is determined whether or not the specified number of images has been captured (S208). The prescribed number may be determined from design information such as CAD data before inspection, or may be determined visually by an operator. If the specified number is reached, CT imaging is terminated (S210), and image reconstruction processing (S112 in FIG. 6) is performed. On the other hand, if the prescribed number has not been reached, the process returns to step S202, and the imaging system and / or inspection object is moved again to capture the field of view from the next imaging position.

  FIG. 9 is a timing chart of processing for imaging in a plurality of directions in the processing of CT imaging for one field of view described with reference to FIG.

  Here, for example, in the configuration shown in FIG. 5, there are S X-ray detectors attached to one circular rotation mechanism, and these are rotated integrally by the detector rotation mechanism. However, imaging is performed for each X-ray detector in one imaging.

  At this time, as shown in FIG. 9, the CT imaging time Tv for one field of view by the X-ray detector is N times of imaging time Ts (indicated by S1, S2,. For example, it is represented by the following formula (14).

When there are S detectors: Tv = NTs + (N / S-1) Tm
When there is one detector: Tv = NTs + (N-1) Tm (14)
At this time, the data transfer of the captured image is performed simultaneously with the mechanical movement. For example, when it is desired to capture 16 images using one detector, Tv = 16Ts + 15Tm.

(Configuration and operation of X-ray inspection apparatus 100 of Embodiment 1)
Hereinafter, the configuration and operation of the X-ray inspection apparatus 100 according to the first embodiment will be described.

  In the X-ray inspection apparatus 100 according to the first embodiment, as will be described below, the visual field does not move mechanically (during imaging). Therefore, in order to obtain imaging data at a plurality of angles, it is necessary to change the X-ray focal position and the X-ray detector position.

  A scanning X-ray source is used for high-speed movement of the X-ray focal position. A plurality of fixed focus X-ray sources may be used as will be described later in a modification. For the position movement of the X-ray detector 23, the following configuration is used.

  1) At least two X-ray detectors 23 are provided, and the X-ray detector driving unit 22 is configured so as to be independently movable.

  2) During imaging by the X-ray detector 23.1, the other X-ray detector 23.2 is moved to a predetermined position in preparation for imaging.

  As described above, when performing imaging, the X-ray detector 23.2 has already been moved to a predetermined position. Therefore, by moving the X-ray focal point position at a high speed, the time required for mechanical movement is reduced. It becomes possible.

  FIG. 10 is a diagram for explaining the configuration of the X-ray inspection apparatus 100 according to the first embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description is made among the parts directly related to the control of the X-ray focal position, the control of the X-ray detector position, the control of the inspection target position, and the like. The necessary parts are extracted and described.

  Referring to FIG. 10, the X-ray detector driving unit 22 has an XYθ operation mechanism capable of driving the X-ray detectors 23.1 and 23.2 with XYθ degrees of freedom. For example, a scanning X-ray source is used.

  In the configuration shown in FIG. 10, an inspection target position driving mechanism (for example, an XY stage) and an inspection target position control unit 80 are provided to move the position of the inspection target.

  In FIG. 10, two independently movable X-ray detectors are used, but two or more X-ray detectors may be provided.

  The X-ray detector 23.1 and the X-ray detector 23.2 are capable of XY-θ operation independently. As will be described later, the θ rotation mechanism does not necessarily have to be provided depending on how the X-ray detector 23 is driven.

  The X-ray detector drive unit 22 includes an orthogonal type biaxial robot arm 22.1 and a detector support unit 22.2 having a rotation axis, and moves and rotates the X-ray detector 23. However, such a configuration that enables such movement in the XY direction or θ rotation in the XY plane and has the same function for the movement of the X-ray detector 23 is not necessary. It is also possible to use mechanisms other than.

  Further, the visual field of the inspection object is operated in an XY manner independently of the X-ray detector 23.1 or 23.2 by an inspection object position driving mechanism controlled by the inspection object position control unit 80 in the arithmetic unit 70. Is possible. Furthermore, as described above, the scanning X-ray source of the X-ray source 10 can move the X-ray focal point position 17 to an arbitrary position on the X-ray target at high speed.

  The calculation unit 70 sends commands to the detector drive control unit 32, the image data acquisition unit (X-ray detector controller) 34, and the scanning X-ray source control mechanism 60, and is shown in a flowchart for inspection processing as will be described later. Run the program. Further, the operation of the inspection apparatus can be controlled by the input from the input unit 40, and the state of each unit or the inspection result can be output from the output unit 50.

  The inspection object position control mechanism includes an actuator and a mechanism for fixing the inspection object, and moves the inspection object according to a command from the inspection object position control unit 80.

  The X-ray detector drive unit 22 includes an orthogonal type biaxial robot arm 22.1 and a detector support unit 22.2 having a rotation axis, and is supplied from the calculation unit 70 through the detector drive control unit 32. The X-ray detector 23 is moved to a designated position by an instruction. Further, the detector drive control unit 32 sends the position information of the X-ray detector 23 at that time to the calculation unit 70.

  The computing unit 70 acquires an X-ray fluoroscopic image and transfers imaging data at a timing instructed by an instruction passed through the detector drive control unit 32.

  The X-ray source 10 generates an electron beam in accordance with a command from the calculation unit 70 that has passed through the scanning X-ray source control mechanism 60, and the electron beam focusing coil 13 and the deflection yoke 12 generate electrons at a specified position on the target. The lines are converged and the X-ray focal point 17 is moved at high speed.

  FIG. 11 is a top view showing the movement locus of the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 100 shown in FIG.

  Operation example 1 shown in FIG. 11A is a view of the configuration shown in FIG. 10 as viewed from above, and shows operation example 1 assuming that 16 X-ray fluoroscopic images are taken from the same angle. It is. The operation example 1 is suitable for using an analytical method represented by a method by Feldkamp et al. As described above, normally, in the analytical method, the projection data is filtered, but the filtering direction is preferably perpendicular to the direction of the X-ray transmission path. Therefore, in order to use the analytical method, it is preferable to image the X-ray detector perpendicular to the X-ray transmission path, that is, to image the X-ray detector toward the visual field.

  Operation example 2 in FIG. 11B is suitable for using a reconfiguration method such as an iterative method or tomosynthesis. This is because iterative techniques and tomosynthesis can be reconstructed regardless of the orientation of the X-ray detector. In this operation, since it is not necessary to rotate the X-ray detector, the X-ray detector driving mechanism can be further simplified, and the speed of the mechanism of the X-ray detector driving unit 22 can be increased and the maintainability can be improved. it can.

  The operation example (movement locus) shown in FIG. 11 will be described in more detail as follows.

The range in which the X-ray detector 23.1 and the X-ray detector 23.2 can operate independently is divided.
Positions A1 and B1 in FIG. 11 are initial positions of the X-ray detectors 23.1 and 23.2, respectively. Positions A1 to A8 and positions B1 to B8 are positions of X-ray detectors 23.1 and 23.2 that acquire fluoroscopic images necessary for image reconstruction, respectively.

  In the operation example shown in FIG. 11, the X-ray detectors 23.1 and 23.2 move at a constant distance with the origin of the imaging system as the center. As a result, when the imaging system is viewed from above, each has a semicircular locus.

  Positions a1, a2, a3, b1, and b2 are focal positions on the X-ray target, and are linearly connected to the X-ray detector positions A1, A2, A3, B1, and B2 and the visual field.

  When imaging starts, the X-ray detectors 23.1 and 23.2 are assumed to be stationary at positions A1 and B1, respectively.

  i) X-rays are generated from the X-ray focal position a1, and imaging is performed by the X-ray detector 23.1 (position A1).

  ii) Next, X-rays are generated from the X-ray focal point position b1, and imaging is started by the X-ray detector 23.2 (position B1). During imaging at the position B1, the X-ray detector 23.1 starts moving to a predetermined position A2.

  iii) When the imaging at the X-ray detector 23.2 (position B1) and the movement of the X-ray detector 23.1 are completed, the focal position of the X-ray is immediately moved to the position a2, and the X-ray detector 23.1 is moved. Imaging is performed at (position A2). During this imaging, the X-ray detector 23.2 moves to a predetermined position B2.

  By repeating the above, it is possible to reduce the pause time of the X-ray source associated with the moving time of the X-ray detector and obtain the number of images necessary for image reconstruction.

  FIG. 12 is a diagram illustrating a flowchart of the entire inspection for the reconstructed image inspection performed by the X-ray inspection apparatus 100 according to the first embodiment.

  Referring to FIG. 12, first, when the process is started (S300), the inspection target position control mechanism determines the inspection portion (field of view) to be inspected according to a command from inspection target position control unit 80 of operation unit 70. It moves to a position where it can be imaged (S302). That is, in order to capture a fluoroscopic image, the stage on which the inspection object is placed and the X-ray detector are moved to a predetermined position. Usually, in the inspection, an optical camera (not shown) is mounted for specifying the inspection position, so that the position can be determined based on the image of the optical camera. As another method, it may be automatically determined based on CAD data to be inspected, or may be performed visually by an operator.

  In addition, first, a fluoroscopic image is captured (S304), and the pass / fail determination unit 78 of the calculation unit 70 inspects the fluoroscopic image, and the visual field to be inspected (the fluoroscopic image is captured from the acquired fluoroscopic image). (Range) is judged (S306). Various methods have been proposed as the pass / fail judgment method, and since they are publicly known, details are not described here. For example, as the most basic inspection, the fluoroscopic image is binarized with a constant value and compared with design information such as CAD data, and it is determined from the area whether there is a part at a predetermined position on the fluoroscopic image.

  Subsequently, the calculation unit 70 determines whether or not inspection by the reconstructed image is necessary (S308). The criteria for determination can be set in advance based on design information such as CAD data, or can be determined from the pass / fail determination result of the fluoroscopic image. For example, in the inspection of the mounting board, when a component is mounted only on one side, it may not be necessary to perform pass / fail determination using a reconstructed image because it can be determined pass / fail with a fluoroscopic image.

  If the inspection using the reconstructed image is not necessary, the arithmetic unit 70 ends the inspection (S318).

  On the other hand, when the inspection by the reconstructed image is necessary, the arithmetic unit 70 subsequently performs CT imaging for one visual field (S310). In CT imaging, the visual field (reconstruction region or region similar to the above-described fluoroscopic image imaging range) in the inspection object is imaged from a plurality of directions. Detailed description of CT imaging will be described later.

  Next, the 3D image reconstruction unit 76 of the calculation unit 70 generates a reconstruction image from the captured images in a plurality of directions (S312). Various methods have been proposed for the reconstruction process. For example, the Feldkamp method described above can be used.

  Subsequently, the quality determination unit 78 of the calculation unit 70 performs quality determination using the reconstructed image (S314). As a method for determining pass / fail, a method of directly using three-dimensional data, a method of using two-dimensional data (tomographic image), or one-dimensional data (profile) can be considered. Since these pass / fail determination methods are well known, a pass / fail determination method suitable for the inspection item may be used, and detailed description thereof will not be repeated here. Hereinafter, an example of the pass / fail determination will be described. First, the three-dimensional reconstructed image is binarized with a constant value. From a design information such as CAD data, a position of a part (for example, a BGA solder ball) is specified in the reconstructed image. From the binarized image, the volume of a pixel adjacent to a certain position of the part can be calculated, and the presence or absence of the part can be determined.

  Further, the calculation unit 70 determines whether or not the inspection of the entire field of view has been completed (S316), and if not completed, returns the processing to step S102. On the other hand, if the inspection has been completed for the entire visual field, the arithmetic unit 70 ends the inspection (S318).

  In FIG. 12, the inspection is performed using the fluoroscopic image and the reconstructed image. However, it is also possible to perform only the inspection using the reconstructed image without performing the inspection using the fluoroscopic image. However, since the reconstruction process usually takes a relatively long time, the entire inspection time can be shortened by performing pass / fail judgment on the fluoroscopic image before the inspection using the reconstructed image.

  FIG. 13 is a diagram illustrating a flowchart of CT imaging for one field of view in step S310 described in FIG.

  FIG. 14 is a timing chart showing the operations of the X-ray detector and the X-ray focal position along the inspection time in the inspection flow shown in FIG.

  In FIG. 13, regarding the portion where the flowchart branches into three, the left row is the operation of the X-ray source, the middle row is the operation of the X-ray detector 23.1, and the right row is the X-ray detector 23. .2 indicates that the processes arranged in the horizontal direction are performed simultaneously.

  Hereinafter, referring to FIG. 13 and FIG. 14, first, when the CT imaging process for one field of view is started (S400), the calculation unit 70 moves the inspection object to move the field of view to be inspected to an appropriate position. Let Further, the calculation unit 70 also moves the X-ray detector 23 to the initial position. The position of the X-ray detector 23 and the position of the inspection target may be set using an encoder mounted on the X-ray detector driving unit 22 or the inspection target position driving mechanism (for example, an XY stage). Alternatively, a general-purpose detector (laser displacement meter or the like) may be used.

  Subsequently, the calculation unit 70 moves the X-ray focal point to a position corresponding to the X-ray detector 23.1, irradiates the X-ray (S402), and images with the X-ray detector 23.1 (S412). The X-ray focal position can be set by the above method. The imaging time (exposure time of the detector) may be set in advance, or the user can set it to a desired time by visual observation. In parallel, the arithmetic unit 70 moves the X-ray detector 23.2 to the next imaging position and converts the imaging data obtained by the X-ray detector 23.1 into the reconstruction process in the 3D image reconstruction unit 78. Therefore, for example, the data is transferred to the memory 90 (S422).

  Next, the calculation unit 70 moves the X-ray focal point to a position corresponding to the X-ray detector 23.2, irradiates the X-ray (S404), and images with the X-ray detector 23.2 (S424). In parallel, the calculation unit 70 moves the X-ray detector 23.1 to the next imaging position and converts the imaging data obtained by the X-ray detector 23.2 into the reconstruction process in the 3D image reconstruction unit 78. Therefore, the data is transferred to the memory 90 (S414).

  Subsequently, the calculation unit 70 determines whether the imaging has reached the specified number (S430). If the prescribed number for image reconstruction has not been reached, the arithmetic unit 70 returns the process to steps S402, 412, and 422. On the other hand, if the specified number has been reached, the calculation unit 70 ends the CT imaging process for one field of view (S432), and shifts the process to step S312.

  In the flowchart, it is determined whether the specified number of images has been captured after the data transfer, but it is preferable to determine the number of images to be captured simultaneously with the data transfer. This is because the data transfer takes about 200 ms, for example, so that the movement to the next imaging position is delayed. Therefore, a delay occurs every time an image is taken. In order to reduce the delay time and increase the speed, it is preferable to determine the prescribed number and move the inspection object / X-ray detector simultaneously with the data transfer.

  Furthermore, as shown in FIG. 14, when the imaging method of Embodiment 1 is used, the imaging time for one field of view can be expressed by the following equations (15) and (16).

When Ts> Tm: Tv = NTs (15)
When Ts <Tm: Tv = Ts + (N-1) Tm (16)
The meaning of each symbol is as follows:
N: Number of images (integer multiple of the number of X-ray detectors)
Tv: Time to image one field of view
Tm: Time for moving mechanism (stage / X-ray detector)
Ts: Imaging (exposure of X-ray detector) time The number of images N is an integer multiple of the number of X-ray detectors for the sake of easy understanding of the following description, but is not necessarily limited to an integer multiple. Absent.

FIG. 14 shows a case where Ts <Tm.
Assuming that the number of fluoroscopic images required for image reconstruction is 16, and using the imaging method of the first embodiment, the number of images required for reconstruction = time required to obtain 16 images is: In the case of Ts> Tm, it is 16Ts, and in the case of Ts <tm, it is Ts + 15Tm. In either case, the method described in FIG. Thus, the imaging time can be shortened.

  As the X-ray intensity of the X-ray source is improved and the sensitivity of the X-ray detector is increased, the exposure time of the X-ray detector necessary for imaging is shortened. Accordingly, in order to move another X-ray detector to a predetermined imaging position during imaging of a certain X-ray detector, a high-speed mechanical mechanism is required. In some cases, imaging of a certain X-ray detector is finished. However, the movement of the X-ray detector may not be completed.

  However, in any case, during an X-ray detector imaging process, another X-ray detector is moved to a predetermined imaging position or the imaging data transfer process of the X-ray detector to be moved is performed in parallel. As a result, the overall processing time can be shortened. Moreover, the processing time for one visual field can be shortened by repeatedly executing such parallel processing for the entire processing for one visual field.

[Modification of Embodiment 1]
FIG. 15 is a diagram for explaining the configuration of an X-ray inspection apparatus 102 according to a modification of the first embodiment. The X-ray inspection apparatus 102 uses a linear movement type X-ray detector and a scanning X-ray source as the X-ray source 10.

  That is, in the X-ray inspection apparatus 102, the three X-ray detectors 23.1, 23.2, and 23.3 can be independently moved in Y and rotated by θ. FIG. 15 shows an operation mechanism of the X-ray detector driving unit 22 in which the X-ray detector support unit 22.3 can rotate and the rail can move in the Y direction. However, any mechanism other than that shown in FIG. Further, as will be described later, the rotation mechanism is not essential.

  The scanning X-ray source that is the X-ray source 10 can move the X-ray focal point position to an arbitrary position on the X-ray target at high speed.

  In addition, the same code | symbol is attached | subjected to the same part as FIG. 1, FIG. Also in FIG. 15, portions necessary for explanation are extracted from the portions directly related to the control of the X-ray focal position, the control of the X-ray detector position, the control of the inspection target position, and the like.

  In FIG. 15, three independently movable X-ray detectors are used, but the number of X-ray detectors may be two or more. When the number of X-ray detectors is an odd number, there are advantages described below. Therefore, it is more desirable to provide an odd number of three or more X-ray detectors. That is, by providing an odd number of X-ray detectors, an X-ray detector moving on the middle rail can pick up an image of the inspection object from directly above. This is suitable for photographing a fluoroscopic image, for example, when operating according to the flowchart described in FIG. However, three is preferable from the viewpoint of cost in terms of minimizing the number of detectors and the number of moving mechanisms.

  In the configuration shown in FIG. 15, the X-ray detector driving unit 22 includes a detector support 22.3 that can move the X-ray detector in the Y direction in the rail shape and can rotate about the rotation axis. The line detector 23 is moved and rotated.

  Further, similarly to the configuration shown in FIG. 10, the field of view of the inspection target is an inspection target position drive mechanism (such as an XY stage on which the inspection target is mounted) controlled by the inspection target position control unit 80 in the calculation unit 70. ), The X-Y operation of the visual field to be inspected can be performed independently of the X-ray detectors 23.1, 23.2 and 23.3. Furthermore, as described above, the scanning X-ray source of the X-ray source 10 can move the X-ray focal point position 17 to an arbitrary position on the X-ray target at high speed.

  The calculation unit 70 sends commands to the detector drive control unit 32, the image data acquisition unit (X-ray detector controller) 34, and the scanning X-ray source control mechanism 60, and is shown in a flowchart for inspection processing as will be described later. Run the program. Further, the operation of the inspection apparatus can be controlled by the input from the input unit 40, and the state of each unit or the inspection result can be output from the output unit 50.

  The inspection object position control mechanism includes an actuator and a mechanism for fixing the inspection object, and moves the inspection object according to a command from the inspection object position control unit 80.

  The X-ray detector driving unit 22 moves the X-ray detector 23 to a designated position by a command from the arithmetic unit 70 through the detector driving control unit 32. Further, the detector drive control unit 32 sends the position information of the X-ray detector 23 at that time to the calculation unit 70.

  The computing unit 70 acquires an X-ray fluoroscopic image and transfers imaging data at a timing instructed by an instruction passed through the detector drive control unit 32.

  The X-ray source 10 generates an electron beam in accordance with a command from the calculation unit 70 that has passed through the scanning X-ray source control mechanism 60, and the electron beam focusing coil 13 and the deflection yoke 12 generate electrons at a specified position on the target. The lines are converged and the X-ray focal point 17 is moved at high speed.

  FIG. 16 is a top view showing the movement locus of the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 102 shown in FIG.

  Operation example 1 shown in FIG. 16 is a view of the configuration of FIG. 15 as viewed from above, and is an operation example assuming that 18 X-ray fluoroscopic images are taken from different angles.

  In FIG. 16, as described above, the X-ray detectors 23.1, 23.2, and 23.3 each have a mechanism that can move linearly on the rail. Furthermore, the X-ray detectors 23.1, 23.2, and 23.3 each have a rotation mechanism that can rotate around the center of the X-ray detector.

  The X-ray source 10 is a scanning X-ray source. Further, the imaging position of the X-ray detector 23 is not limited to the arrangement shown in FIG. Furthermore, the number of images to be imaged is not limited to 18, and the number of images that can be inspected may be designated. The designation of the number of captured images may be calculated from design information such as CAD data, or may be determined visually by an operator.

  In FIG. 16, positions A1 to A6, B1 to B6, and C1 to C6 are positions of X-ray detectors 23.1, 23.2, and 23.3 that acquire fluoroscopic images necessary for image reconstruction, respectively. The numbers 1 to 6 assigned to the positions mean the order of imaging, and the first image is taken at the position A1, and the last image is taken at the position A6.

  Also, the positions a1, a2, b1, b2, c1, c2 are focal positions on the X-ray target, and the X-ray detector positions correspond to the positions A1, A2, B1, B2, C1, C2, respectively. To do.

  The operation example 1 in FIG. 16 is suitable for using an analytical method typified by the Feldkamp method. As in the case of FIG. 11 (a), normally, in the analytical method, the projection data is filtered, but the filtering direction is preferably perpendicular to the direction of the X-ray transmission path. Therefore, in order to use the analytical method, it is preferable to image the X-ray detector perpendicular to the X-ray transmission path, that is, to image the X-ray detector toward the visual field.

  FIG. 17 is a top view showing another movement locus of the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 102 shown in FIG.

  In the operation example 2 shown in FIG. 17, the X-ray detector 23 does not rotate and moves in parallel in the XY plane. Such an operation example 2 is suitable for using a reconstruction method such as an iterative method or tomosynthesis. This is because iterative techniques and tomosynthesis can be reconstructed regardless of the orientation of the X-ray detector.

  In this operation, since it is not necessary to rotate the X-ray detector, the X-ray detector driving mechanism can be further simplified, the mechanical mechanism can be speeded up, and the maintainability can be improved.

  FIG. 18 is a view showing a flowchart of the inspection when the X-ray detector 23 is moved and inspected as shown in FIG. 16 or FIG.

  Since the flow of the entire examination is the same as that shown in FIG. 12, FIG. 18 shows a portion of CT imaging for one field of view in step S310 of FIG.

  It is a figure which shows the flowchart of CT imaging of 1 visual field of step S310 demonstrated in FIG. 18, the leftmost row is the operation of the X-ray source, the row from the center left is the operation of the X-ray detector 23.1, and the row from the center right is the X-ray. The operation of the detector 23.2, the rightmost row represents the operation of the X-ray detector 23.3, and indicates that the processes arranged in the horizontal direction are performed simultaneously.

  FIG. 19 is a timing chart showing operations of the X-ray detector and the X-ray focal position along the inspection time in the inspection flow shown in FIG.

  Hereinafter, referring to FIG. 18 and FIG. 19, first, when the CT imaging process for one field of view is started (S500), the arithmetic unit 70 moves the inspection object to move the field of view to be inspected to an appropriate position. Let Further, the calculation unit 70 also moves the X-ray detector 23 to the initial position. The position of the X-ray detector 23 and the position of the inspection target may be set using an encoder mounted on the X-ray detector driving unit 22 or the inspection target position driving mechanism (for example, an XY stage). Alternatively, it may be set using a general-purpose detector (laser displacement meter or the like).

  Therefore, in the timing chart of FIG. 19, it is assumed that the X-ray detectors 23.1, 23.2, and 23.3 start from the states at the initial positions A1, B1, and C1, respectively.

  Subsequently, the calculation unit 70 moves the X-ray focal point to a position corresponding to the X-ray detector 23.1, irradiates the X-ray (S502), and images with the X-ray detector 23.1 (S512). The X-ray focal position can be set by the above method. The setting of the imaging time (exposure time of the X-ray detector) is the same as in the first embodiment.

  Next, the calculation unit 70 moves the X-ray focal point to a position where the X-ray detector 23.1 is imaged three times later, and the 3D image reconstruction unit 78 converts the image data captured by the X-ray detector 23.1. For example, the data is transferred to the memory 90 (S514).

  In parallel, the calculation unit 70 moves the X-ray focal point to a position corresponding to the X-ray detector 23.2, emits X-rays (S504), and captures an image with the X-ray detector 23.2 (S524). . Next, the calculation unit 70 moves the X-ray focal point to a position where the X-ray detector 23.2 is imaged three more times later, and converts the imaging data obtained by the X-ray detector 23.2 into a 3D image reconstruction unit 78. For reconfiguration processing in FIG. 5, for example, the data is transferred to the memory 90 (S526).

  In parallel, the calculation unit 70 moves the X-ray focal point to a position corresponding to the X-ray detector 23.3, irradiates the X-ray (S506), and captures an image with the X-ray detector 23.3 (S534). .

  The calculation unit 70 determines whether or not the imaging has reached the specified number (S540), and if not, returns the processing to step S532.

  Next, the arithmetic unit 70 moves the X-ray focal point to a position where the X-ray detector 23.3 is imaged three more times later, and converts the image data obtained by the X-ray detector 23.3 into a 3D image reconstruction unit 78. The data is transferred to the memory 90 for reconfiguration processing in (S532).

Thereafter, the processing is repeated in the same manner until a prescribed number of images are captured.
Furthermore, finally, when imaging by the X-ray detector 23.3 is completed, imaging data by the X-ray detector 23.3 is transferred to the memory 90 for reconstruction processing by the 3D image reconstruction unit 78. (S514).

  If the number of captured images reaches the specified number, the calculation unit 70 ends the CT imaging process for one field of view (S542), and the process proceeds to step S312.

  In the flowchart of FIG. 18, for convenience of description of the flow, the calculation unit 70 is described as determining whether a specified number of images have been captured after data transfer. The number of captured images is determined.

  Further, as shown in the timing chart of FIG. 19, assuming that the imaging time and the time taken to move the detector are Ts and Tm, respectively, the following is obtained.

When 2Ts => Tm: Tv = NTs
When 2Ts <Tm: Tv = (N / 3-1) (Ts + Tm) + 3Ts
The meaning of each symbol is as follows:
N: Number of images (integer multiple of the number of X-ray detectors)
Tv: Time to image one field of view
Tm: Time for moving mechanism (stage / X-ray detector)
Ts: Imaging (exposure of X-ray detector) time The number of images N is an integer multiple of the number of X-ray detectors for the sake of easy understanding of the following description, but is not necessarily limited to an integer multiple. Absent.

  Here, assuming that the number of fluoroscopic images required for image reconstruction is 18, the imaging method of the X-ray inspection apparatus 102 shown in FIG. 15 (three X-ray detectors are used alternately) was used. The time required to obtain the 18 images required for reconstruction is 18Ts if 2Ts> Tm, and 8ts + 5tm if 2Ts <tm, and in either case one detection The imaging time can be shortened compared to (16Ts + 15Tm) when the instrument is used. Furthermore, in the method shown in FIG. 9, the speed is higher than Tv = NTs + (N / S-1) Tm = 18Ts + 5Tm when three X-ray detectors are used.

  In the modification of the first embodiment, as in the first embodiment, when the imaging time is shortened, the X-ray detector and the inspection object that can be moved relatively quickly are moved instead of the large and heavy X-ray source. Let Furthermore, since the movement of each component is a simple mechanical mechanism called a straight line, the distance that the X-ray detector moves to a predetermined position is shortened and the moving speed is increased, so the mechanical moving time is shortened. As a result, high-speed inspection can be realized.

[Embodiment 2]
The X-ray inspection apparatus 102 according to the modification of the first embodiment has a configuration using a linear movement type X-ray detector and a scanning X-ray source as the X-ray source 10.

  The X-ray inspection apparatus 104 according to the second embodiment uses a plurality of fixed focus type X-ray sources as the X-ray source 10 instead of the scanning X-ray source.

FIG. 20 is a diagram for explaining the configuration of the X-ray inspection apparatus 104 according to the second embodiment.
In the X-ray inspection apparatus 104, three X-ray detectors 23 are provided as the X-ray source 10 corresponding to the three X-ray detectors 23.1 to 23.3. An x-ray source is provided.

  Then, X-rays are simultaneously applied to the same visual field to be inspected from these three fixed focus type X-ray sources. At this time, a shield 66 is provided so that X-rays from an X-ray source to which X-rays should enter one X-ray detector do not enter other X-ray detectors, In order to control the X-ray source, an X-ray source control mechanism 64 is provided instead of the scanning X-ray source control mechanism 60. The X-ray source control mechanism 64 is different from the scanning X-ray source control mechanism 60 in that it does not control the deflection of the electron beam, but instead controls three X-ray sources simultaneously.

  As in the case of the X-ray inspection apparatus 102 in FIG. 15, an odd number of five or more X-ray detectors may be provided. By providing an odd number of X-ray detectors, the X-ray detector moving on the middle rail can image the inspection object from directly above. This is suitable for photographing a fluoroscopic image, for example, when operating according to the flowchart described in FIG.

  The mechanism for driving the X-ray detectors 23.1 to 23.3 is basically the same as that of the X-ray inspection apparatus 102 according to the modification of the first embodiment described with reference to FIG. However, in the X-ray inspection apparatus 104, as described below, the manner of movement of the X-ray detectors 23.1 to 23.3 is different from that of the X-ray inspection apparatus 102 described in FIG.

  However, in the X-ray inspection apparatus 104 according to the second embodiment, similarly to the X-ray inspection apparatus 102 according to the modification of the first embodiment, the movement of each component is made a simple mechanical mechanism called a straight line. Since the distance that the line detector moves to a predetermined position is shortened and the moving speed is increased, the mechanical moving time is shortened, and high-speed inspection can be realized.

  FIG. 21 is a top view of the shield 66. As described above, when three X-ray detectors 23 are provided and three openings are provided and three X-ray sources operate simultaneously, one X-ray detection is performed. X-rays from an X-ray source to which X-rays should be incident on the detector are placed at positions where they do not enter other X-ray detectors.

  The shield 66 is made of a material and thickness that sufficiently shields X-rays, and lead or the like is preferable. Since the X-ray detector moves linearly, the opening of the shield is rectangular (or slit). The size of the shield 66 is such that the X-rays of the X-ray source CA do not enter the X-ray detector CC.

  The size of the opening of the shield 66 is large enough to allow the X-ray of the X-ray source CA to enter the X-ray detector 23.1. However, the X-ray to the X-ray detector 23.2 is shielded. Is the size of

  FIG. 22 is a top view showing the movement trajectory between the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 104 shown in FIG.

  Operation example 1 shown in FIG. 22 is an operation example in which the configuration of FIG. 20 is viewed from above, and it is assumed that 18 X-ray fluoroscopic images are taken from different angles.

  In FIG. 22, as described above, X-ray detectors 23.1, 23.2, and 23.3 each have a mechanism that can move linearly on the rail. Furthermore, the X-ray detectors 23.1, 23.2, and 23.3 each have a rotation mechanism that can rotate around the center of the X-ray detector.

  As described above, the X-ray source 10 is not a scanning X-ray source but an imaging system including a plurality of, for example, three fixed focus X-ray sources.

  Unlike the X-ray inspection apparatus 102 in FIG. 15, the X-ray detectors 23.1, 23.2, and 23.3 perform a linear operation integrally.

  After being simultaneously imaged by X-ray detectors 23.1, 23.2 and 23.3 with X-rays from three X-ray sources, X-ray detectors 23.1, 23.2 and 23.3 Together, it moves linearly to the next imaging position. Further, the inspection object is moved from the position T1 to the position T6 in synchronization with the X-ray detectors 23.1, 23.2 and 23.3 so that the reconstruction areas are the same.

  Furthermore, the number of images to be imaged is not limited to 18, and the number of images that can be inspected may be designated. The designation of the number of captured images may be calculated from design information such as CAD data, or may be determined visually by an operator.

  In FIG. 22, positions A1 to A6, B1 to B6, and C1 to C6 are positions of X-ray detectors 23.1, 23.2, and 23.3 that acquire fluoroscopic images necessary for image reconstruction, respectively. The numbers 1 to 6 assigned to the positions mean the order of imaging, and the first image is taken at the position A1, and the last image is taken at the position A6.

Positions Sa, Sb, and Sc are focal positions of the X-ray sources CA, CB, and CC, respectively.
The operation example 1 in FIG. 22 is also suitable for using an analytical method represented by the Feldkamp method for the same reason as in the first embodiment.

  FIG. 23 is a top view showing another movement locus of the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 104 shown in FIG.

  In the operation example 2 shown in FIG. 23, the X-ray detector 23 does not rotate and moves in parallel in the XY plane. Such an operation example 2 is suitable for using a reconstruction method such as an iterative method or tomosynthesis for the same reason as in the first embodiment.

  In this operation, since it is not necessary to rotate the X-ray detector, the X-ray detector driving mechanism can be further simplified, the mechanical mechanism can be speeded up, and the maintainability can be improved.

Here, the positional relationship between the X-ray focal point position and the X-ray detector will be described.
When the center of the field of view to be reconstructed is the origin, the following relational expression is established, where Lf is the distance from the center of the field of view to the X-ray focal point and Ls is the distance from the center of the field of view to the center of the X-ray detector. .

Ls =-Lf × (M-1)
A negative sign indicates that the direction is opposite. However, M represents an enlargement ratio, and the enlargement ratio is expressed by the following formula.

M = Hs / Ho
Here, Hs represents the height from the X-ray focal point to the X-ray detector, and Ho represents the height from the X-ray focal point to the center of the visual field. This relationship itself holds similarly in other embodiments.

  FIG. 24 is a diagram showing a flowchart of the inspection when the X-ray detector 23 is moved and inspected as shown in FIG. 22 or FIG.

  Again, since the flow of the entire examination is the same as that shown in FIG. 12, FIG. 24 shows the CT imaging portion for one field of view in step S310 of FIG.

  Therefore, FIG. 24 is a diagram illustrating a flowchart of CT imaging of one field of view in step S310 described in FIG.

  FIG. 25 is a timing chart showing operations of the X-ray detector and the X-ray focal position along the inspection time in the inspection flow shown in FIG.

  Hereinafter, referring to FIG. 24 and FIG. 25, first, when the CT imaging process for one field of view is started (S600), the calculation unit 70 sets the inspection target to X to move the field of view to be inspected to an appropriate position. -Move in the Y plane. Further, the arithmetic unit 70 also linearly moves the X-ray detectors 23.1, 23.2 and 23.3 to the initial position (S602).

  Subsequently, the calculation unit 70 irradiates each of the X-ray detectors 23.1, 23.2, and 23.3 with X-rays from the X-ray focal points Fa, Fb, and Fc at the same time, and the X-ray detector 23.1. , 23.2 and 23.3 (S604). The imaging time (X-ray detector exposure time) may be set in advance, or the user can set it to a desired time by visual observation.

  Subsequently, the arithmetic unit 70 moves the X-ray detectors 23.1, 23.2, and 23.3 to the next imaging position and performs imaging by the X-ray detectors 23.1, 23.2, and 23.3. For example, the data is transferred to the memory 90 for reconstruction processing in the 3D image reconstruction unit 78 (S606).

  Next, the calculation unit 70 determines whether or not the imaging has reached the specified number (S608). If the prescribed number for image reconstruction has not been reached, the arithmetic unit 70 returns the process to step S602. On the other hand, if the specified number has been reached, the computing unit 70 ends the CT imaging process for one field of view (S610), and the process proceeds to step S312.

  In this case as well, in the flowchart, it is determined whether the specified number of images has been captured after the data transfer. However, for the same reason as in the first embodiment, it is preferable to determine the number of captured images simultaneously with the data transfer.

  Furthermore, as shown in FIG. 25, the imaging time for one field of view when the imaging method of the second embodiment is used will be further described.

In general, the following equation holds.
Tv = (N / S) Ts + (N / S-1) Tt
The definitions of symbols are shown below.

Tv: Time to capture one field of view
Tm: Time to move the imaging position (stage / X-ray detector) within the same field of view
Ts: Imaging (X-ray detector exposure) time
Tt: Imaging data transfer time Also, by moving the X-ray detector linearly, the movement time of the X-ray detector is shortened, and the moving distance of the visual field is very short compared to the movement of the X-ray detector (inversely proportional to the magnification rate). Therefore, Tm <Tt.

  In the following description, it is assumed that the inspection object is divided into M (for example, 4) fields of view and 18 images are captured as CT imaging.

  Regarding the CT imaging time for one field of view, in the case of a multi-X-ray source, three captured images can be acquired simultaneously by one imaging. Therefore, the CT imaging time Tv for one field of view is represented by the following formula (17) because it is the total of the imaging data transfer times of five times when imaging is performed six times. At this time, the data transfer of the captured image is performed simultaneously with the mechanical movement of the X-ray detector 23 and the inspection target.

Tv = 6Ts + 5Tt (17)
Therefore, it is possible to shorten the imaging time as compared with (16Ts + 15Tm) when one detector described above is used.

  As the X-ray source of the X-ray source is improved and the sensitivity of the X-ray detector is increased, the exposure time of the X-ray detector required for imaging is shortened. Therefore, as a CT method, the Feldkamp method is used. It is the same in that the iterative method is preferable.

[Embodiment 3]
In the above description, in the first embodiment or the second embodiment, the configuration of the X-ray detector driving unit 22 is mainly based on the viewpoint of the moving time of the X-ray detector 23 and the inspection target in CT imaging for one field of view. Therefore, the effect of shortening the inspection time was explained.

  Next, in the third embodiment, shortening of the inspection time when sequentially inspecting a plurality of visual fields (inspection portions) of the same inspection object will be described.

(Problem when the field of view (inspection object) or X-ray detector rotates to capture images)
When an imaging system using an analytical method is considered, the direction of the X-ray detector is preferably along a circular orbit centered on the reconstruction area because of the filter processing for reconstruction.

  For this reason, regarding the movement of the X-ray detector for imaging from a plurality of angles, i) moving in a circular orbit around the reconstructed portion, ii) moving on an XY-θ stage, etc. can be considered. For this reason, the mechanism becomes complicated, and the cost tends to be relatively high in increasing the speed of movement of the X-ray detector and the stage.

  Furthermore, the tomographic image used for the inspection is preferably rectangular. This is because the inspection algorithm is designed on the assumption that the image is rectangular. Furthermore, since the inspection object is wider than the reconstruction area (field of view) obtained by one CT imaging, the field of view is divided into a wide area by connecting multiple fields of view, so it is efficient by connecting rectangular fields of view. This is because inspection objects can be included.

  FIG. 26 shows an examination region obtained by CT imaging of one field of view when the field of view (inspection object) or the X-ray detector is rotated to perform image reconstruction using an analytical technique. It is a conceptual diagram for demonstrating an area | region.

  When reconstruction is performed using an analytical method, the area that can be used for inspection is a circle in a cross-section with a reconstructed image. This is because, for example, the analytical algorithm uses a method called backprojection as described above. Therefore, when an image detected by the X-ray detector at each imaging position is backprojected, it is effectively backprojected. This is because the area becomes a circle. At this time, if a rectangular portion is cut out from the circular reconstruction area obtained by the analytical method, one field of view is reduced, and it takes time to inspect a wide inspection area.

  The shape of the reconstruction area (field of view) is a portion where images captured by a rectangular X-ray detector overlap. In the imaging system in which the field of view (inspection object) rotates, the rectangles are circular because they overlap from a plurality of angles. Since the area to which the inspection algorithm can be applied is a rectangle, if the reconstruction area is a circle, only the rectangular portion inside the circle can be inspected, and the area that can be inspected at a time is a rectangle inscribed in the circle.

For example, if the length of one side of the cross section of the field of view that can be imaged by the X-ray detector is 2L, the reconstructed region is a circle with a radius L. The square inscribed in the circle is a square having a side length of √2L. This square is an area that can be inspected. Therefore, the area of the inspectable region in the conventional imaging system is 2L ² .

  Therefore, the image reconstructed by the conventional imaging system uses only a part of the image data captured by the X-ray detector. Therefore, the size of one field of view becomes small, and it is necessary to image a large number of fields of view.

  Furthermore, from the viewpoint of speeding up for in-line inspection, the speeding up can be achieved as the number of CT images picked up decreases. However, the analytical method has a problem that when a small number of images are taken, many noises such as artifacts are generated, which is inappropriate as an image used for inspection.

  Here, for example, in the arrangement of the X-ray detector and the X-ray source as shown in FIG. 3, that is, the X-ray source and the X-ray detector are fixed, and the visual field is mechanically moved (rotated). When obtaining a plurality of number of images necessary for reconstruction, the time required for the entire inspection is considered as follows.

FIG. 27 is a timing chart of a conventional imaging system in which the visual field (inspection target) rotates.
Note that the flow of the entire inspection is the same as that described in FIG. 6, for example.

  In the following description, it is assumed that the inspection target is divided into M (for example, four) fields of view and N images are captured as CT imaging. The symbols are the same as those defined above.

  The CT imaging time Ti of the entire inspection object is expressed by Equation 1 because it is the total of (M−1) mechanical movement times after imaging M fields of view.

Ti = M (Tv + Te) (18)
Next, FIG. 28 is a diagram illustrating the CT imaging time for one field of view. Referring to FIG. 28, the CT imaging time Tv for one field of view is represented by the following equation (19) because N times of imaging are performed and N times of mechanical movement time are total. At this time, the data transfer of the captured image is performed simultaneously with the mechanical movement.

Tv = NTs + (N-1) Tm (19)
(Configuration of X-ray inspection apparatus 106 of Embodiment 3)
As will be described below, in the X-ray inspection apparatus 106 according to the third embodiment, first, the X-ray detector 23 is arranged in parallel, and then an iterative method is used. Remove the restrictions on the orbit and increase the speed. Second, in the X-ray inspection apparatus 106, the X-ray detector 23 is arranged in parallel and the iterative method is used to increase the effective rectangular area and reduce the number of field divisions, thereby increasing the system speed. Plan. Thirdly, by using an iterative method, a high-accuracy reconstructed image is generated even from a small number of captured images, thereby speeding up the system.

  That is, in the X-ray inspection apparatus 106, the number of X-ray detectors 23 is one or more, and they are arranged in parallel in a rectangular area required as each inspection area (field of view) to be inspected. The X-ray detector 23 translates in the same plane as the detection surface of the X-ray detector. The reconstruction method for image reconstruction uses an iterative method.

  Here, the X-ray source as the X-ray source 10 may not be a scanning X-ray source. One fixed-focus X-ray source or a plurality of X-ray sources may be used.

FIG. 29 is a diagram illustrating the configuration of the X-ray inspection apparatus 106 according to the third embodiment.
The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description is made among the parts directly related to the control of the X-ray focal position, the control of the X-ray detector position, the control of the inspection target position, and the like. The necessary parts are extracted and described.

  Referring to FIG. 29, the X-ray detector drive unit 22 includes a robot arm that can drive the X-ray detector 23.1 in parallel in the XY plane. In the example of FIG. 29, a fixed focus type X-ray source is used as the X-ray source 10.

  In the configuration shown in FIG. 29, in order to move the position of the inspection object in the XY plane independently of the X-ray detector 23.1, an inspection object position drive mechanism (for example, an XY stage), an inspection A target position control unit 80 is provided.

  The X-ray detector drive unit 22 includes an orthogonal type biaxial robot arm 22.1 and a detector support unit 22.2, and detects X-rays according to a command from the calculation unit 70 through the detector drive control unit 32. The device 23 is moved to the designated position. Further, the detector drive control unit 32 sends the position information of the X-ray detector 23 at that time to the calculation unit 70. However, any other mechanism can be used as long as it is configured to enable such movement in the XY direction and has a similar function to the movement of the X-ray detector 23. .

  The calculation unit 70 sends commands to the detector drive control unit 32, the image data acquisition unit (X-ray detector controller) 34, and the scanning X-ray source control mechanism 60, and executes a program for inspection processing as will be described later. To do.

  The inspection object position control mechanism includes an actuator and a mechanism for fixing the inspection object, and moves the inspection object according to a command from the inspection object position control unit 80.

  The computing unit 70 acquires an X-ray fluoroscopic image and transfers imaging data at a timing instructed by an instruction passed through the detector drive control unit 32.

  FIG. 30 is a diagram showing a movement trajectory between the X-ray detector 23 and the visual field to be inspected as a top view in the configuration of the X-ray inspection apparatus 106 shown in FIG.

  Operation example 1 shown in FIG. 30 is a view of the configuration shown in FIG. 29 as viewed from above, and shows an operation example assuming that 16 X-ray fluoroscopic images are taken from an equal angle. As described above, this operation example is suitable for using a reconstruction method such as an iterative method or tomosynthesis. This is because iterative methods and tomosynthesis can be reconfigured regardless of the orientation of the X-ray detector.

  In the case of this operation, it is not necessary to rotate the X-ray detector 23, so that the configuration of the X-ray detector driving unit 22 can be simplified, the mechanical mechanism can be speeded up, and the maintainability can be improved.

  The X-ray detector 23.1 moves at a constant distance with the focal point 17 of the X-ray source as the origin. As a result, when the imaging system is viewed from above, the locus of the center of the X-ray detector 23.1 is a circle.

  In FIG. 30, positions T1 and T2 are visual field positions, and correspond to X-ray detector positions S1 and S2, respectively.

FIG. 31 is a CT imaging flowchart of an imaging system using a translation detector.
Again, since the flow of the entire examination is the same as that shown in FIG. 12, FIG. 31 shows the CT imaging portion for one field of view in step S310 of FIG.

  Therefore, FIG. 31 is a diagram illustrating a flowchart of CT imaging of one field of view in step S310 described in FIG.

  First, when the CT imaging process for one field of view is started (S700), the calculation unit 70 moves the inspection object in the XY plane in order to move the field of view to be inspected to an appropriate position. Further, the calculation unit 70 also moves the X-ray detector 23.1 to the initial position (S702). The imaging position can be automatically calculated from design information such as CAD data. Since the inspection target is on the stage, it is possible to move the visual field as the stage moves.

  Subsequently, the calculation unit 70 irradiates the X-ray detector 23.1 with X-rays from the X-ray focal point 17, and images the X-ray detector 23.1 (S704). The imaging time (X-ray detector exposure time) may be set in advance, or the user can set it to a desired time by visual observation.

  Subsequently, the arithmetic unit 70 moves the X-ray detector 23.1 to the next imaging position, and uses the 3D image reconstruction unit 78 to reconstruct the imaging data obtained by the X-ray detector 23.1. For example, the data is transferred to the memory 90 (S706).

  Next, the calculation unit 70 determines whether the imaging has reached the specified number (S708). The prescribed number may be determined from design information such as CAD data before inspection, or may be determined visually by an operator. If the prescribed number for image reconstruction has not been reached, the arithmetic unit 70 returns the process to step S702. On the other hand, if the prescribed number has been reached, the calculation unit 70 ends the CT imaging process for one field of view (S710), and shifts the process to step S312.

  In this case as well, in the flowchart, it is determined whether the specified number of images has been captured after the data transfer. However, for the same reason as in the first embodiment, it is preferable to determine the number of captured images simultaneously with the data transfer.

FIG. 32 is a conceptual diagram showing an inspection region of an imaging system using a translational X-ray detector.
The shape of the reconstruction area (field of view) is a portion where images captured by a rectangular X-ray detector overlap. In the imaging system of FIG. 26, since the rectangles overlap from a plurality of angles, the rectangles are circular. However, in FIG. 32, since the X-ray detectors all face the same direction, the overlapping portions are rectangles.

  When the reconstruction area is circular, since the area to which the inspection algorithm can be applied is a rectangle, only the rectangular portion inside the circle can be used, and the range that can be inspected at a time is small. On the other hand, in the case shown in FIG. 32, since the reconstruction area is rectangular, the inspectable range in the reconstruction area is relatively wide. Therefore, since the total number of images can be reduced, the inspection time can be shortened. Furthermore, arranging the rectangles without gaps is fewer than arranging the circles without gaps. That is, since the total number of images is reduced, the inspection time can be shortened.

Assuming that the length of one side of the cross section of the field of view that can be imaged by the X-ray detector is 2L, the reconstructed region is a successful form with the length of one side being 2L. Therefore, when the inspection area is arranged as shown in FIG. 32, the area of the inspectable area is 4L ² . Since the area of the inspectable region in the imaging system of FIG. 26 is 2L ² , it is possible to inspect a region having an area twice that of the conventional imaging system in one field of view. In other words, the number of divided visual fields can be halved.

  The above effect may be linear movement or a plurality of X-ray detectors as long as the X-ray detector moves in parallel. Of course, the X-ray source may be a fixed focus X-ray source or a scanning X-ray source.

FIG. 33 is a timing chart of an imaging system using a translational X-ray detector.
In the following description, it is assumed that the inspection target is divided into M fields of view in the imaging system, and N images are captured as CT imaging. The definition of the symbols is as described above.

  In the X-ray inspection apparatus 106 in FIG. 29, the number of divided visual fields can be halved with respect to the imaging system described with reference to FIG. 26, so the number of visual fields is M / 2.

  The CT imaging time Ti of the entire inspection object is represented by the equation (20) because M / 2 fields are imaged and the total of M / 2 mechanical movement times.

Ti = M / 2 (Tv + Te) (20)
As described above, in the X-ray inspection apparatus of the third embodiment, when imaging is performed for CT reconstruction, the moving range of the X-ray detector is imaged in the same plane, and the direction of the X-ray detector is the same. The direction. The movement mode of the X-ray detector and the inspection object (stage) is limited to two axes XY, thereby simplifying the mechanism of the moving means and increasing the moving speed. Furthermore, the relative speed of the X-ray detector and the object to be inspected translates into a rectangular field of view to be reconstructed by CT, and the effective range for automatic inspection is widened, thereby speeding up the automatic inspection system.

[Embodiment 4]
In the first to third embodiments described above, the X-ray inspection apparatus capable of reducing the loss of the inspection time due to the time for mechanically moving the X-ray detector 23 or the inspection object has been described.

  In the fourth embodiment, shortening of the inspection time by driving the X-ray source in pulses will be described.

That is, in order to perform high-speed imaging, the intensity of X-rays should be as strong as possible. However, if the electron beam current is increased to increase the X-ray intensity, the target is thermally damaged by the collision of the electron beam. Therefore, when the current of the electron beam is increased, the electron beam can be applied to the target only for a short time until reaching a temperature at which there is a risk of thermal damage. In the X-ray inspection apparatus according to the fourth embodiment, as will be described below, the “multiple X-ray detectors” and the “focus scanning X-ray source” are used to solve the thermal problem and increase the X-ray intensity. Therefore, high-speed imaging is achieved.
(Problem when CT imaging is performed using a plurality of X-ray detectors and a scanning X-ray source)
Hereinafter, as a premise for explaining the configuration and operation of the X-ray detection apparatus according to the fourth embodiment, problems in the case of performing CT imaging using a plurality of X-ray detectors and a scanning X-ray source will be described. .

  FIG. 34 is a diagram showing a configuration of an X-ray inspection apparatus that performs imaging using four detectors and a scanning X-ray source. The same parts as those in FIG. 1 are denoted by the same reference numerals, and in FIG. 34, parts other than those directly necessary for explanation are not shown.

  An X-ray inspection apparatus 900 shown in FIG. 34 is configured using a scanning X-ray source and four X-ray detectors 23.1 to 23.4.

  The X-ray detectors 23.1 to 23.4 are fixed to the detector driving mechanism 22. Since it is assumed in FIG. 34 that 16 images are captured, the detector drive mechanism 22 rotates from position 1 to position 4 as the image is captured.

  The visual field in the inspection object can be moved XY independently of the X-ray detectors 23.1 to 23.4 and the X-ray source by the inspection object position control mechanism. In the configuration of FIG. 34, X-rays can be irradiated to one field of view from different angles by scanning the X-ray focal point, so that fluoroscopic images from a plurality of directions of one field of view can be obtained without moving the inspection object. An image can be taken.

The operation at the time of imaging is as follows.
During imaging by one X-ray detector 23, the X-ray focal point position 17 is not moved. Images are sequentially picked up by the four X-ray detectors 23.1 to 23.4. At that time, the X-ray focal point 17 is located at a point where the straight line connecting the center of each detector and the center of the field of view and the target intersect.

  When imaging with the four X-ray detectors 23.1 to 23.4 is completed, the detector driving unit 22 simultaneously moves the four detector positions to the next imaging position.

FIG. 35 is a CT imaging flowchart of the X-ray inspection apparatus 900 shown in FIG.
Again, since the overall flow of the examination is the same as that shown in FIG. 12, FIG. 35 shows the CT imaging portion for one field of view in step S310 of FIG.

  Therefore, FIG. 35 is a diagram illustrating a flowchart of CT imaging of one field of view in step S310 described in FIG.

  FIG. 36 is a timing chart showing operations of the X-ray detector and the X-ray focal position along the inspection time in the inspection flow shown in FIG.

  Hereinafter, referring to FIG. 35 and FIG. 36, first, when the CT imaging process for one field of view is started (S800), the calculation unit 70 sets the inspection object X to move the field of view to be inspected to an appropriate position. -Move in the Y plane. Further, the calculation unit 70 also moves the X-ray detector drive mechanism 22 to a predetermined position (position 1 in this case), and irradiates the X-ray detector 23.1 with X-rays from the X-ray focal point 17. Then, an image is taken with the X-ray detector 23.1 (S802).

  Next, the calculation unit 70 irradiates the X-ray detector 23.2 with X-rays from the X-ray focal point 17, and images the X-ray detector 23.2 (S804).

  Next, the calculation unit 70 irradiates the X-ray detector 23.3 with X-rays from the X-ray focal point 17, and images the X-ray detector 23.3 (S806).

  Next, the calculation unit 70 irradiates the X-ray detector 23.4 with X-rays from the X-ray focal point 17, and images the X-ray detector 23.4 (S808).

  Subsequently, the arithmetic unit 70 transfers the image data obtained by the X-ray detectors 23.1 to 23.4 to, for example, the memory 90 for reconstruction processing in the 3D image reconstruction unit 78 (S810).

  Next, the calculation unit 70 determines whether the imaging has reached the specified number (S812). If the prescribed number for image reconstruction has not been reached, the arithmetic unit 70 moves the process to step S814. On the other hand, if the specified number has been reached, the computing unit 70 ends the CT imaging process for one field of view (S816), and the process proceeds to step S312.

  In step S814, the arithmetic unit 70 moves the X-ray detector drive mechanism 22 to the next predetermined position (position 2 in this case), and the process proceeds to step S802.

  Thereafter, the processes in steps S802 to S810 and S814 are repeated until it is determined in step S812 that the specified number has been reached.

  With reference to the multi-directional imaging timing chart of one field of view in FIG. 36, it is assumed that the inspection target is divided into M (for example, four) fields of view and N images are captured as CT imaging. The definitions of symbols are as described above.

  At this time, the CT imaging time Ti of the entire inspection object is obtained by imaging the M fields of view and is the sum of the (M−1) times of the mechanical movement time, and is expressed by Expression (21).

Ti = MTv + (M−1) Tm (21)
Next, the CT imaging time for one field of view will be described.

  The CT imaging time Tv for one field of view is expressed by Expression (22) because N times of imaging are performed using S X-ray detectors and N / S times of movement are performed. At this time, the data transfer of the captured image is performed simultaneously with the mechanical movement.

Tv = NTs + (N / S-1) Tm (22)
Therefore, the time Tv required to capture 16 images of one field of view from different angles in the conventional method shown in FIG. 34 is Tv = 16Ts + 3Tm.

(Configuration of X-ray Inspection Apparatus 110 of Embodiment 4)
As described below, the X-ray inspection apparatus 110 according to the fourth embodiment has a configuration described below, thereby reducing the time required for imaging.

  That is, the imaging method using the focus scanning X-ray source as described in FIG. 34 is effective in reducing the mechanical movement time of the X-ray detector, but from the viewpoint of speeding up imaging, There is room for improvement as follows.

  i) The scanning X-ray source can move the X-ray focal point position at high speed. However, in order to image one target region from different angles, a single X-ray detector cannot sufficiently utilize its characteristics. This is because the mechanical movement of the X-ray detector requires much longer time than the X-ray focal point movement.

  ii) On the other hand, when there are a plurality of X-ray detectors, an X-ray detector other than the X-ray detectors used for imaging is used in order to acquire the imaging data of the X-ray detectors in order with a scanning X-ray source. Since the instrument is not in operation, it cannot be said that a plurality of X-ray detectors contributes effectively to speeding up.

  iii) In order to increase the X-ray intensity, it is necessary to increase the target current, but the target is thermally damaged. Therefore, when a large target current is used, it is necessary to move the focal point before the temperature rise of the target reaches a temperature at which the target is damaged, that is, to shorten the irradiation time for one point. However, in this case, since the time during which X-rays are emitted is short, the dose is insufficient to obtain image data with the X-ray detector.

In the X-ray inspection apparatus of the fourth embodiment, the following points are changed from the configuration of FIG.
1) Increase the target current.

2) Use multiple X-ray detectors simultaneously.
3) Shorten the electron beam irradiation time to one place on the target.

  4) During a single exposure time of the X-ray detector, the corresponding X-ray focal position is irradiated with a strong electron beam in a plurality of times.

  By irradiating a single X-ray focal point with an electron beam in a plurality of times in a pulsed manner, the portion irradiated with the X-ray beam on the target can be radiated and cooled during the time when the electron beam is not applied. it can. Therefore, even an electron beam that is strong enough to reach a temperature at which the target is damaged by irradiation for a certain period of time can be used by moving the target temperature to the next X-ray focal point position within the allowable time. In addition, since a plurality of X-ray detectors can be used simultaneously for imaging, the entire imaging time is shortened.

  FIG. 37 is a block diagram for explaining the configuration of the X-ray inspection apparatus 110 according to the fourth embodiment.

  Referring to FIG. 37, in X-ray inspection apparatus 110, four X-ray detectors 23.1 to 23.4 are fixed on a circular sensor base 22.6 at the same angle of 90 degrees on the same circumference. Has been. When the sensor base 22.6 is rotated by a predetermined angle by the X-ray detector driving unit 22, the detector arrangement is moved to positions 1 to 4 as in FIG.

  Further, as will be described later, the four X-ray detectors 23.1 to 23.4 are simultaneously activated, and in order to perform X-ray sensing, detectors corresponding to X-ray irradiation and X-ray focal points respectively. A shield 66 is provided to limit the direction only.

  In addition, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will not be repeated. Also, in FIG. 37, portions that are not directly related to the following description in the configuration of FIG. 1 are omitted.

  In FIG. 37, a system is assumed in which four X-ray detectors move on the same circle while maintaining the positional relationship with each other. However, a mechanism capable of independently controlling the position of each detector may be provided. good. Further, the number of X-ray detectors 23 may be four or more or the following. Similarly, the number of X-ray focal positions may be four or more or the following depending on the number of X-ray detectors 23.

The operation will be described below.
While the X-ray detectors 23.1 to 23.4 simultaneously perform one fluoroscopic image capturing, the X-ray focal point is stopped a plurality of times at focal positions a to d corresponding to the respective X-ray detectors.

  When imaging by the X-ray detector 23 is completed, the X-ray detector driving unit 22 moves the four X-ray detector positions simultaneously to the next imaging position.

FIG. 38 is a conceptual diagram showing a configuration of a detector used as the X-ray detector 23.
As the X-ray detector 23, a charge storage type X-ray detector represented by a flat panel detector as shown in FIG. 38A or an image intensifier as shown in FIG. 38B is used. Can be used. The X-ray detector 23 converts the incident X-rays into electrons by various methods, and records the incident position of the X-rays by a function of storing the electrons in a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) device.

  Since the charge accumulation time becomes the exposure time of the X-ray detector, if the irradiation dose during a single exposure time is the same, even X-rays that are continuously incident are X-rays that have been irradiated in multiple pulses. Even if it exists, the same output (image data) can be taken out. With this characteristic, the inspection method of the X-ray inspection apparatus 110 is realized.

  FIG. 39 is a diagram showing a movement trajectory between the X-ray detector 23 and the scanning X-ray source as a top view in the configuration of the X-ray inspection apparatus 110 shown in FIG.

  The operation example shown in FIG. 39 is an operation example in which the configuration of FIG. 37 is viewed from above, and it is assumed that 16 X-ray fluoroscopic images are taken from different angles.

The shield 66 and the X-ray detector driving unit 22 are not shown.
Referring to FIG. 39, when imaging one visual field, the positions to which the X-ray detectors 23.1 to 23.4 move are A1 to A4, B1 to B4, C1 to C4, and D1 to D4, respectively. . Further, the X-ray focal positions corresponding to the X-ray detector positions are represented by a1, a2, b1, b2, c1, c2, d1, d2, etc.

  Since the X-ray detector driving unit 22 is a circular sensor base, in FIG. 39, the X-ray detector 23 always moves in the same direction with respect to the rotation axis of the X-ray detector driving unit 22. . However, for example, when the X-ray detector driving unit 22 is constituted by a two-axis robot arm or the like and an iterative method or tomosynthesis is used as the image reconstruction method, the same orientation with respect to the XY axes of the moving plane is maintained. You can leave it alone.

  FIG. 40 is a flowchart of one-field imaging according to the configuration of the X-ray inspection apparatus 110 shown in FIG.

  As a premise for explaining the operation in this flowchart, the following is confirmed.

  1) Generation of a reconstructed image requires X-ray fluoroscopic images of a field of view taken from a plurality of different angles.

2) The field of view is set on the axis of rotational movement of the X-ray detector.
3) Two or more X-ray detectors 23 (four in this example) are used.

4) The X-ray detectors move on a circular orbit while maintaining their relative positional relationship.
5) The X-ray detector is stationary during imaging.

6) As the X-ray source, a scanning X-ray source capable of moving the X-ray focal point at high speed is used.
7) For the X-ray source, a shield 66 having a fixed position is installed.

Referring to FIG. 40, when calculation unit 70 determines that inspection by a reconstructed image of the visual field is necessary and starts CT imaging of one visual field (S820), all operations are performed in accordance with a command from calculation unit 70. X-ray detectors 23.1 to 23.4 start exposure. At the same time, the scanning X-ray source performs pulse irradiation from a plurality of locations corresponding to the respective positions of the X-ray detectors 23.1 to 23.4 in accordance with a command from the arithmetic unit 70. When the imaging (exposure) is completed, the calculation unit 70 stops the irradiation of the X-ray source (S822).
Subsequently, all the X-ray detectors 23.1 to 23.4 move their positions on a circular orbit around the rotation axis of the sensor base 22.6 according to a command from the calculation unit 70. At this time, the X-ray detector 23 transfers the imaging data acquired immediately before to the memory 90 via the remaining circle portion 70 and releases the electric charge, thereby enabling imaging again (S824).

  Subsequently, the calculation unit 70 determines whether or not the total number of captured images has reached the specified number, and repeats the processes of steps S822 to S824 until the specified number of images is reached (S826).

  When the arithmetic unit 70 determines that the imaging has been completed up to the specified number, the imaging is terminated, and the process proceeds to the image reconstruction process (S312).

  FIG. 41 is a timing chart for explaining the operation of the scanning X-ray source when the four X-ray detectors 23.1 to 23.4 are used.

  In FIG. 41, the time for moving the X-ray focal position is so short as to be negligible compared to the time required for exposure.

  As shown in FIG. 41 (a), using the imaging method described with reference to FIG. 34, the exposure time required to acquire a single fluoroscopic image with a sufficient amount of information and durability can be achieved when the equilibrium temperature is reached. The target currents are Ts and I, respectively.

  As shown in FIG. 41 (b), since the intensity of X-rays is proportional to the target current, when the target current I is doubled, the time Ts required for image acquisition can be reduced to 1 / 2Ts. However, use of a strong electron beam causes target damage due to temperature rise, and therefore, in practice, an X-ray source cannot be used as shown in FIG. The temperature of the target rises by irradiating the electron beam, and reaches an equilibrium state by irradiating for a certain time. This difficulty arises because the temperature at this time is proportional to the amount of current of the irradiating electron beam.

  Therefore, as shown in FIG. 41C, the X-ray focal point position is moved at a much shorter time interval than when the target temperature reaches equilibrium. In FIG. 41, a means one of the focal positions a1 to a4 corresponding to the current position of the X-ray detector 23. The same applies to the other b, c, d. When the electron beam is allowed to flow in a pulse form as shown in FIG. 41 (c), in the state of FIG. 41 (b), it is possible to perform imaging that effectively uses a large current that cannot be used.

  When driving an electron beam as shown in FIG. 41 (c), if the target current at each X-ray focal position at the moment when X-rays are emitted is 2I, X in 4Ts in the example of FIG. 41 (a). The exposure time required to capture a fluoroscopic image having the same information amount as that obtained by the line detectors 23.1 to 23.4 is 2Ts. The total exposure time of the X-ray detectors 23.1 to 23.4 is the same as the example of FIG. 41B, but imaging can be performed without damaging the target.

  FIG. 42 is a timing chart of single-field imaging in the X-ray inspection apparatus 110 shown in FIG.

  As shown in FIG. 42, the imaging time for one field of view can be expressed by Expression (23). The number of images N is an integral multiple of the number of detectors.

Tv = (N / S) Tss + (N / S-1) Tss (23)
The meaning of each symbol is as follows.

N: Number of images (integer multiple of the number of X-ray detectors)
S: Number of X-ray detectors
Tv: Time to image one field of view
Tm: Time for moving the mechanism (stage / X-ray detector)
Tss: Imaging time for simultaneous exposure of S X-ray detectors (exposure of X-ray detectors) Note that the number of images N is an integral multiple of the number of X-ray detectors for easy understanding of the following explanation. However, it is not necessarily limited to an integer multiple.

  For example, assuming that the number of fluoroscopic images required for image reconstruction is 16, and using the imaging method described with reference to FIGS. 37 to 41, 16 images that are the number required for reconstruction are obtained. The time required for this is 4Tss + 3Tm. As described above, since Tss can increase the intensity of X-rays, 4Ts> Tss. Therefore, the imaging time can be shortened as compared with (16Ts + 3Tm) when the four detectors described in FIG. 34 are used.

FIG. 43 is a conceptual diagram showing the structure of a scanning X-ray source.
FIG. 43A shows an internal configuration example of an X-ray source using a transmission target, and FIG. 43B shows an example of a reflection target. As described below, since the scanning X-ray source has such a structure, the operation as in the fourth embodiment is possible.

  In the scanning X-ray source, the spot diameter of the electron beam emitted from the electron gun is reduced by a converging lens. The electron beam is bent in the X direction and the Y direction by a deflector controlled from the outside, and collides with an arbitrary position on the X-ray target (the electron beam that collides with the target is generally called a target current).

  At this time, 99% of the kinetic energy of the electron beam colliding with the X-ray target is heat, and about 1% is braking X-ray.

  As described above, the X-ray target has a transmission type (FIG. 43A) and a reflection type (FIG. 43B). In the case of the transmission type, generally tungsten on beryllium or aluminum is deposited.

  In order to prevent exposure during X-ray focal point movement, the electron beam may be stopped when changing the position of the electron beam (X-ray focal point position). For example, the electron beam is turned ON / OFF by controlling the grid voltage of the electron gun.

[Embodiment 5]
In the above description, when changing the visual field of the inspection object, the inspection object is moved by the inspection object position control mechanism.

  However, when a scanning X-ray source is used, the field of view can be adjusted without moving the inspection object by adjusting the relative positional relationship between the X-ray focal point position 17 and the X-ray detector 23 within a certain range. It is possible to change.

  In this case, the center of the focal locus on the X-ray target when capturing a plurality of images necessary for image reconstruction in one field of view is deviated from the target center. Therefore, such CT imaging is hereinafter referred to as “eccentric CT imaging” in this specification.

  The X-ray inspection apparatus according to the fifth embodiment has a configuration in which such an eccentric CT imaging is combined with the X-ray detector driving unit 22 described in the modification of the first embodiment.

  That is, in general, since the examination area is wider than the CT image reconstruction area, it is necessary to divide the examination area into a plurality of fields of view (reconstruction areas in one CT imaging). Usually, the movement from the visual field to the visual field is realized by mechanically moving the inspection object on an XY stage or the like. In the X-ray inspection apparatus of the fifth embodiment, the speed of the system is increased by realizing the movement from the visual field to the visual field without motion by electronic movement of the X-ray focal point position.

  Therefore, by using the scanning X-ray source and moving the X-ray focal position by electrical control, the imaging position can be moved at high speed without mechanical movement. The mechanical movement time of the X-ray detector 23 is shortened by arranging a plurality of X-ray detectors 23 at predetermined positions in advance. By moving the visual field only by moving the X-ray focal position, the visual field is moved at high speed.

  FIG. 44 is a block diagram for explaining the configuration of the X-ray inspection apparatus 120 according to the fifth embodiment.

  However, the configuration of the X-ray inspection apparatus 120 is the same as that described below with reference to FIG. 10 except for the control of the movement of the position of the X-ray detector 23 and the movement of the position of the X-ray focal point 17 as described below. Since the configuration is the same as that of apparatus 100, description of the configuration will not be repeated. As described below, the configuration for rotating the X-ray detector 23 is not necessary in the present embodiment, and the X-ray detector 23 moves in parallel in the XY plane. .

FIG. 45 is a diagram illustrating an operation example of an imaging system using a translational X-ray detector.
FIG. 45 shows an example in which four fields of view are reconstructed without mechanical movement of the X-ray detector 23 and the inspection object. FIG. 45 is a top view of the configuration of FIG. 44, and shows an operation example assuming that eight perspective images are taken from the same angle.

  The operation example of FIG. 45 is suitable for using a reconstruction method such as an iterative method or tomosynthesis. This is because iterative techniques and tomosynthesis can be reconstructed regardless of the orientation of the X-ray detector. In this operation, it is not necessary to rotate the X-ray detector, so that the X-ray detector driving mechanism can be further simplified, the mechanical mechanism can be speeded up, and the maintainability can be improved.

  In order to be able to operate as shown in FIG. 45, the range in which the X-ray detector 23.1 and the X-ray detector 23.2 can operate independently needs to be separated.

  In FIG. 45, positions A1 and B1 are initial positions of the X-ray detector 23.1 and the X-ray detector 23.2, respectively. Positions A1 to A4 and B1 to B4 are positions of an X-ray detector 23.1 and an X-ray detector 23.2 that acquire a fluoroscopic image necessary for image reconstruction, respectively.

  In the example of FIG. 45, the X-ray detector 23.1 and the X-ray detector 23.2 move at a constant distance with the origin of the imaging system as the center. As a result, when the imaging system is viewed from above, each has a semicircular locus. However, the movement of the X-ray detector 23 is not limited to the circular orbit.

  In FIG. 45, positions a1-1, a2-1, b1-1, and b2-1 are focal positions 17 on the X-ray target. The focal position a1-1 indicates the focal point with respect to the X-ray detector position A1 when imaging the visual field 1, and the focal position a2-1 indicates the focal point with respect to the X-ray detector position A1 when imaging the visual field 2. When imaging the visual field 1, the focus positions a1-2, a1-3, and a1-4 (not shown) are sequentially targeted from the focus position a1-1 according to the X-ray detector positions A1 to A4. Positioned on a circular orbit like the dotted line in the above figure, similarly, the focal position a2-1 is also sequentially changed from the focal position a2-1 in accordance with the X-ray detector positions A1 to A4. The focal positions a2-2, a2-3, and a2-4 (not shown) are positioned on a circular orbit like a dotted line in the drawing on the target. The focal position b1-1 indicates the focal point with respect to the X-ray detector position B1 when imaging the visual field 1, and the focal position b2-1 indicates the focal point with respect to the X-ray detector position B1 when imaging the visual field 2. Similarly to the focal positions a1-1 and a2-1, the focal position b1-1 and the focal position b2-1 are also circular trajectories such as dotted lines in the drawing on the target according to the X-ray detector positions B1 to B4. Move to another focus position above.

  As shown in FIG. 45, the overall flow of the inspection involving the movement of the X-ray detector 23 and the X-ray focal point position is the same as that shown in FIG.

  However, in the X-ray inspection apparatus 120 of the fifth embodiment, for the second and subsequent visual fields, the visual field movement time is shortened. This is because the last X-ray detector is moved to the imaging position of the next visual field at the same time as the final imaging for one visual field is started. At this time, only the X-ray focal point position is changed so that it is not necessary to move the stage. That is, as shown in the operation example of FIG. 45, the imaging is performed so that the imaging angle differs depending on the field of view. However, although such a non-equal-interval imaging may cause the reconstructed image to deteriorate, it is possible to reduce the deterioration by using an iterative method.

  FIG. 46 is a flowchart of the inspection process for one field of view of the imaging system described with reference to FIGS. 44 and 45.

  FIG. 47 is an inspection timing chart for one field of view of the imaging system described with reference to FIGS. 44 and 45.

  Hereinafter, with reference to FIG. 46 and FIG. 47, the inspection process for one visual field of the X-ray inspection apparatus 120 of the fifth embodiment will be described.

  First, before starting CT imaging, it is assumed that the visual field (inspection target) and the X-ray detector 23 are at predetermined initial positions A1 and B1.

  When CT imaging for one field of view is started (S900), first, the computing unit 70 causes the X-ray detector 23.1 to image the examination target (S902). That is, the calculation unit 70 moves the X-ray focal point to the position a1-1 corresponding to the X-ray detector 23.1 and images it. Note that the movement of the X-ray focal point is performed electronically, so that it is so fast that it can be ignored compared to the exposure time and mechanical movement time. The imaging (detector exposure) time may be set in advance, or may be set to an arbitrary time visually. Imaging data to be inspected is obtained by irradiating an X-ray from an X-ray source and exposing an X-ray detector. The exposure time can be determined in advance from the size of the inspection object and the intensity of the X-ray generated by the X-ray source.

  Next, the calculation unit 70 causes the image data captured by the X-ray detector 23.1 to be transferred to the calculation unit 70 (S906). The imaging data is transferred to the memory 90 used by the calculation unit 70 by the image acquisition control mechanism 30.

  In parallel with this data transfer, the calculation unit 70 irradiates X-rays at the focal position b1-1 and images the inspection object with the X-ray detector 23.2 (S904) and simultaneously with the X-ray detector 23.1. Is moved to the next imaging position (S906). Imaging of the X-ray detector 23.2 is performed in the same manner as the imaging of the X-ray detector 23.1 described above. At this time, in order to capture an image with the X-ray detector 23.2, it is necessary to move the X-ray focal point 17, but this is faster than other processes. The next imaging position (A2) of the X-ray detector 23.1 needs to be determined before inspection. Usually, the position to be imaged by the X-ray detector can be determined when the number of images to be imaged is determined from design information such as CAD data.

  Subsequently, when the prescribed number of images for one visual field has not been reached (S910), the calculation unit 70 transfers the image data captured by the X-ray detector 23.2 to the calculation unit 70 (S912). In parallel with this data transfer, the calculation unit 70 irradiates X-rays at the focal position a1-2 and images the inspection object with the X-ray detector 23.1 (S910), and at the same time, the X-ray detector 23.2. Is moved to the next imaging position (B2) (S912). Similarly, it is necessary to determine the next imaging position (B2) before the inspection.

  Thereafter, in the same manner, the imaging by the X-ray detector 23.2 and the transfer of imaging data from the X-ray detector 23.1 or the movement of the X-ray detector 23.1 to the next imaging position are performed in parallel. Or imaging in the X-ray detector 23.1 and transfer of imaging data from the X-ray detector 23.2 or movement of the X-ray detector 23.2 to the next imaging position is performed in parallel. This is repeated until the number of captured images reaches a specified number. In this respect, it is basically the same as the operation of the first embodiment described with reference to FIG.

  When the prescribed number of images is completed (S908), the calculation unit 70 transfers the imaging data from the X-ray detector 23.2 and moves the X-ray detector 23.2 to the next imaging position. (S914) The imaging process for one field of view is terminated (S916), and the process proceeds to step S312.

Next, the time required for CT imaging of one field of view in FIG. 47 is estimated as follows.
Tv = (N / S-1) Tm + STs
The time for each process is defined as follows.

Tm: time for moving the mechanism (X-ray detector) Ts: imaging (X-ray detector exposure) time CT imaging time Tv for one visual field by S (for example, two) X-ray detectors 23 is N times. The total imaging time and N / S mechanical movement times. However, Tv varies depending on the time required for each process. In the following, in consideration of general imaging time, calculation is performed as Tm >> Ts >> Tf (X-ray focal point moving time) (X-ray focal point is sufficiently faster than other processes and can be ignored). .

Further, a case where there are two X-ray detectors will be described.
First, since the image is taken by the X-ray detector 23.1, it takes time Ts. Next, it takes time Tf to move the X-ray focal point, but at the same time, the X-ray detector 23.1 is moved to the next imaging position A2. Since the X-ray detector 23.2 is already arranged at a predetermined position, it takes time Ts because it can be imaged without generating a moving time. After imaging with the X-ray detector 23.2, the X-ray detector 23.2 is moved. Next, although imaging is performed by the X-ray detector 23.1, the movement has not been completed yet. The movement ends after Ts + Tm from the start of imaging, and the X-ray detector 23.1 is imaged at position A2. Next, since the imaging of the X-ray detector 23.2 is performed but the movement is not completed, the imaging start time is Ts + Tm later. Since the X-ray detector 23.2 first starts imaging after Ts, the imaging time for one cycle is Tm. Therefore, the imaging time Tm of one cycle is (N / 2-1) times, the first imaging (A1) time Ts of the X-ray detector 23.1, the X-ray focal point moving time Tf, and the X-ray detector 23.2. When the last imaging is added, the CT imaging time for one field of view is obtained and is expressed by Expression (24).

Tv = (N / 2-1) Tm + 2Ts (24)
Further, the moving time to the next visual field is a time obtained by subtracting the imaging time Ts of the X-ray detector 23.2 from the time when the X-ray detector 23.1 moves to the imaging position of the next visual field. It is represented by Formula (25).

Te = Tm−Ts (25)
FIG. 48 is an inspection timing chart for the entire inspection of the imaging system described with reference to FIGS. 44 and 45.

  In FIG. 48, it is assumed that the inspection target is divided into M (for example, 4) fields of view and N images are captured as CT imaging. The definitions of symbols are shown below.

  The CT imaging time Ti of the entire inspection object is expressed by the equation (26) because it is the total of (M−1) field-of-view movement times when M fields of view are imaged.

Ti = MTv + (M−1) Te (26)
However, the meaning of the symbols is as follows.

Ti: Time for imaging the entire inspection object Tv: Time for imaging one field of view Te: Time for moving the field of view In the X-ray inspection apparatus 120, the field of view movement time Te is almost the difference between the movement time Tm and the imaging time Ts. Therefore, the travel time is greatly shortened.

[Modification of Embodiment 5]
FIG. 49 is a diagram for explaining the configuration of an X-ray inspection apparatus 122 according to a modification of the fifth embodiment. The X-ray inspection apparatus 122 uses a linear movement type X-ray detector and a scanning X-ray source as the X-ray source 10.

  However, the configuration of the X-ray inspection apparatus 122 is the same as that described with reference to FIG. 15 except for the control of the movement of the position of the X-ray detector 23 and the movement of the position of the X-ray focal point 17 as described below. Since the configuration is the same as that of device 102, the description of the configuration will not be repeated. As will be described below, the configuration for rotating the X-ray detector 23 is not necessary in the modification of the present embodiment, and the X-ray detector 23 moves in parallel in the XY plane. Shall.

  FIG. 50 is a diagram illustrating an operation example of the imaging system using the parallel movement X-ray detector of the X-ray inspection apparatus 122.

  FIG. 50 shows an example in which four fields of view are reconstructed without mechanical movement of the X-ray detector 23 and the inspection object. FIG. 50 is a top view of the configuration of FIG. 49 and shows an operation example assuming that nine X-ray fluoroscopic images are taken from different distances at equal intervals.

  X-ray detector positions A1 to A3, positions B1 to B3, and positions C1 to C3 are an X-ray detector 23.1, an X-ray detector 23.2, and an X-ray respectively for obtaining a fluoroscopic image necessary for image reconstruction. This is the position of the detector 23.3. Numbers 1 to 3 among the position codes indicate the order of imaging, and the first image is captured at the position A1, and the last image is captured at the position A3. However, the imaging order may not be this.

  The locus on the target of the focus corresponding to the positions A1 to A3 of the X-ray detector is a straight line like the focus locus 1 and the locus on the target of the focus corresponding to the positions B1 to B3 of the X-ray detector is The locus on the target of the focal point corresponding to the positions C1 to C3 of the X-ray detector becomes a straight line such as the focal locus 3.

  Such an arrangement of the X-ray detectors is also suitable for using a reconstructing method such as an iterative method or tomosynthesis. In this operation, it is not necessary to rotate the X-ray detector 23, so that the X-ray detector driving unit 22 can be simplified, and the mechanical mechanism can be speeded up and the maintainability can be improved.

  FIG. 51 is a flowchart of the inspection process for one field of view of the imaging system using the linear movement detector described in FIGS. 49 and 50.

  FIG. 52 is an inspection timing chart for one field of view of the imaging system described with reference to FIGS. 49 and 50.

  Hereinafter, with reference to FIG. 51 and FIG. 52, an inspection process for one visual field of the X-ray inspection apparatus 122 according to the modification of the fifth embodiment will be described.

  First, before starting CT imaging, it is assumed that the visual field (inspection object) and the X-ray detector 23 are at predetermined initial positions A1, B1, and C1.

  When CT imaging for one field of view is started (S920), first, the calculation unit 70 causes the X-ray detector 23.1 to image the examination target (S922). That is, the calculation unit 70 moves the X-ray focal point to the position a1-1 corresponding to the X-ray detector 23.1 and images it. Note that the movement of the X-ray focal point is performed electronically, so that it is so fast that it can be ignored compared to the exposure time and mechanical movement time. The imaging (detector exposure) time may be set in advance, or may be set to an arbitrary time visually. Imaging data to be inspected is obtained by irradiating an X-ray from an X-ray source and exposing an X-ray detector. The exposure time can be determined in advance from the size of the inspection object and the intensity of the X-ray generated by the X-ray source.

  Next, the calculation unit 70 causes the image data captured by the X-ray detector 23.1 to be transferred to the calculation unit 70 (S926). The imaging data is transferred to the memory 90 used by the calculation unit 70 by the image acquisition control mechanism 30.

  In parallel with this data transfer, the calculation unit 70 irradiates X-rays at the focal position b1-1 and images the inspection object with the X-ray detector 23.2 (S924) and at the same time, the X-ray detector 23.1. Is moved to the next imaging position (A2) (S926). Imaging of the X-ray detector 23.2 is performed in the same manner as the imaging of the X-ray detector 23.1 described above. At this time, in order to capture an image with the X-ray detector 23.2, it is necessary to move the X-ray focal point 17, but this is faster than other processes. The next imaging position (A2) of the X-ray detector 23.1 needs to be determined before inspection. Usually, the position to be imaged by the X-ray detector can be determined when the number of images to be imaged is determined from design information such as CAD data.

  Next, the calculation unit 70 transfers the image data captured by the X-ray detector 23.2 to the memory 90 used by the calculation unit 70 (S930).

  In parallel with this data transfer, the calculation unit 70 irradiates X-rays at the focal position c1-1 and images the inspection object with the X-ray detector 23.3 (S928) and simultaneously the X-ray detector 23.2. Is moved to the next imaging position (B2) (S930). Imaging of the X-ray detector 23.3 is performed in the same manner as the imaging of the X-ray detector 23.1 described above.

  Subsequently, when the prescribed number of images for one field of view has not been reached (S932), the calculation unit 70 transfers the image data captured by the X-ray detector 23.3 to the memory 70 used by the calculation unit 70 ( S936). In parallel with this data transfer, the calculation unit 70 irradiates X-rays at the focal position a1-2 and images the inspection object with the X-ray detector 23.1 (S934), and at the same time, the X-ray detector 23.3. Is moved to the next imaging position (C2) (S936). Similarly, the next imaging position (C2) needs to be determined before inspection.

  Thereafter, in the same manner, the imaging by the X-ray detector 23.2 and the transfer of imaging data from the X-ray detector 23.1 or the movement of the X-ray detector 23.1 to the next imaging position are performed in parallel. Or imaging in the X-ray detector 23.3 and transfer of imaging data from the X-ray detector 23.2 or movement of the X-ray detector 23.2 to the next imaging position is performed in parallel. Alternatively, the imaging by the X-ray detector 23.1 and the transfer of imaging data from the X-ray detector 23.3 or the movement of the X-ray detector 23.3 to the next imaging position are performed in parallel. Repeat until the number of images reaches the specified number. In this respect, it is basically the same as the operation of the first embodiment described with reference to FIG.

  When the prescribed number of images is completed (S932), the arithmetic unit 70 transfers the imaging data from the X-ray detector 23.3 and moves the X-ray detector 23.3 to the next imaging position. (S938) The imaging process for one field of view is terminated (S940), and the process proceeds to step S312.

  Next, as shown in FIG. 52, the time required for CT imaging of one field of view in the imaging system using the linear movement detector is estimated as follows.

In addition, the definition of the time of each process is as above-mentioned.
The CT imaging time Tv for one field of view by S (for example, 3) X-ray detectors is the total of N imaging times and N / S mechanical movement times. However, Tv varies depending on the time required for each process. In the following, in consideration of general imaging time, the calculation is performed as 2Ts >> Tm >> Tf (the movement of the X-ray focal point is sufficiently faster than other processes).

Further, a case where there are three X-ray detectors will be described below.
First, since the image is taken by the X-ray detector 23.1, it takes time Ts. Next, it takes time Tf to move the X-ray focal point, but at the same time, the X-ray detector 23.1 is moved to the next imaging position A2. Since the X-ray detector 23.2 is already arranged at a predetermined position, it takes time Ts because it can be imaged without generating a moving time. After imaging with the X-ray detector 23.2, the X-ray detector 23.2 is moved. Next, an image is picked up by the X-ray detector 23.3. Since the X-ray detector 23.3 is already arranged at a predetermined position, it takes time Ts because it can be imaged without generating a moving time.

  Next, imaging is performed by the X-ray detector 23.1. Since the movement has already been completed, the imaging time for one cycle is 3 Ts. Therefore, the imaging time Tv for one field of view is expressed by the following equation.

Tv = NTs
Further, since the moving time to the next visual field is only the moving time of the X-ray focal point, the following equation is obtained.

Te = Tf
Therefore, it is possible to perform imaging at a higher speed than normal imaging.

[Embodiment 6]
When inspecting a printed circuit board with soldered parts with X-rays, the printed circuit board contains components that require inspection using a reconstructed image, such as BGA, and components that can be inspected using only a fluoroscopic image. An X-ray inspection apparatus capable of imaging by the following two methods is desirable.

1) A part can be imaged from a plurality of different directions for reconstructing an image for inspection.
2) A fluoroscopic image can be captured with the inspection object placed directly above the X-ray source.

  However, the arrangement of the X-ray detectors suitable for the analytical image reconstruction method is on a circular orbit separated from the vertical axis to be inspected by a certain distance, and is not suitable for the fluoroscopic image inspection in the vertical direction. Therefore, an apparatus that enables both vertical fluoroscopic imaging and fluoroscopic imaging is provided with a mechanism for moving the X-ray detector to the fluoroscopic imaging position by XY movement, or X dedicated to fluoroscopic imaging. An additional line detector is required.

  However, even when the X-ray detector has a mechanism for moving the X-ray detector to the fluoroscopic image capturing position by XY movement, such a moving mechanism should have a mechanically simple configuration as long as the movement accuracy, maintenance, etc. From the viewpoint of. In addition, if an X-ray detector dedicated to fluoroscopic image capturing is provided, an extra cost for this detector is required.

  Therefore, as described below, the X-ray inspection apparatus according to the sixth embodiment has the following configuration.

  i) Three X-ray detector moving mechanisms that can move the position of the X-ray detector independently on a straight line and three X-ray detectors (detectors) corresponding to the X-ray detector moving mechanism are installed. To do. Note that the number of X-ray detectors may be two or more. If the number of X-ray detectors is an odd number, there is an advantage that an X-ray detector moving on the middle rail can take an image of the inspection object from directly above, so that X-ray detection is possible. More preferably, an odd number of three or more units are provided. However, three is preferable from the viewpoint of cost in terms of minimizing the number of detectors and the number of moving mechanisms.

  ii) One of the three X-ray detector moving mechanisms is installed in a moving mechanism that can position the X-ray detector directly above the X-ray source and the inspection object.

  As described above, by providing an odd number of X-ray detectors, the X-ray detector moving on the middle rail can image the inspection object from directly above. This is suitable, for example, for photographing a fluoroscopic image for determining whether or not an inspection using a reconstructed image is necessary when operating according to a flowchart described later.

  iii) During imaging, while exposing the central X-ray detector, the X-ray detectors at both ends not exposed are moved to the next imaging position. Further, while exposing the two X-ray detectors at both ends, the center X-ray detector that is not exposed is moved to the next imaging position.

  iv) When two X-ray detectors are exposed at the same time, the X-ray focus is irradiated in a time-sharing manner (pulse irradiation) at a position corresponding to the two detectors at a short time interval with respect to the exposure time.

  v) As a method for image reconstruction, an image from an imaging position (on a straight line) that is not on a circular orbit is used for reconstruction by performing an iterative method or image reconstruction by tomosynthesis.

Hereinafter, the configuration and operation of the X-ray inspection apparatus according to the sixth embodiment will be described.
FIG. 53 is a diagram for explaining the configuration of the X-ray inspection apparatus 130 according to the sixth embodiment. The X-ray inspection apparatus 130 uses a linear movement type X-ray detector and a scanning X-ray source as the X-ray source 10. It is not necessary to move the inspection target during imaging for one field of view.

  Furthermore, as will be described later, in order to cause the X-ray source 10 to perform a pulse operation, a shield 66 similar to that shown in FIG. 21 is provided.

  As in the case of FIG. 21, the shield 66 is made of a material and thickness that sufficiently shields X-rays, and lead or the like is preferable. Since the X-ray detector 23 moves linearly, the opening of the shield 66 is rectangular (or slit). The size of the shield 66 is such that X-rays from the focal position for the X-ray detector 23.1 do not enter the X-ray detector 23.3. The size of the opening of the shield 66 is such that the X-ray from the focal position for the X-ray detector 23.1 can sufficiently enter the X-ray detector 23.1. The X-rays to 23.2 are large enough to be shielded. The relationship between the size of the shield 66 and the size of the opening is the same for the other X-ray detectors 23.2 and 23.3.

  Even when X-rays are emitted from a plurality of positions with a plurality of X-ray detectors exposed at the same time by installing a slit-shaped shield 66 suitable for the inspection target area, magnification, and size of the X-ray detector. An X-ray fluoroscopic image only from a specific angle of the inspection object region can be acquired by the X-ray detector 23 installed in a straight line passing through the X-ray focal point and the inspection object.

  The X-rays incident on the shield 66 generate scattered rays, and when all the X-ray detectors 23 are subjected to simultaneous exposure and pulse imaging, there is a possibility that the captured image is deteriorated. For example, when X-ray detectors 23.1, 23.2, and 23.3 are exposed simultaneously, scattered X-rays emitted toward X-ray detector 23.1 are emitted from X-ray detector 23.2. May affect the imaging. Therefore, as will be described later, the X-ray detector 23 is operated by shifting the exposure time between the two X-ray detectors 23.1 and 23.3 at the both ends and the central X-ray detector 23.2. Even with the same imaging time, it is possible to perform imaging while suppressing the influence of scattered radiation.

  However, the configuration of the X-ray inspection apparatus 130 is excluding control of movement of the position of the X-ray detector 23, movement of the position of the X-ray focal point 17, and control of pulse operation of the X-ray source 10 as described below. Since this is the same as the configuration of the X-ray inspection apparatus 102 described with reference to FIG. 15, the description of the configuration will not be repeated. As will be described below, the configuration for rotating the X-ray detector 23 is not necessary in the modification of the present embodiment, and the X-ray detector 23 moves in parallel in the XY plane. Shall.

  54 is a top view showing the movement trajectory between the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 130 shown in FIG.

  In FIG. 54, X-ray detectors 23.1, 23.2, and 23.3 each have a mechanism that can move linearly on the rail.

  As described above, the X-ray source 10 is a scanning X-ray source. Further, the imaging position of the X-ray detector 23 is not limited to the arrangement shown in FIG. 54. Further, the number of images to be imaged is not limited to 18, and the number of images that can be inspected may be specified. The designation of the number of captured images may be calculated from design information such as CAD data, or may be determined visually by an operator.

  In FIG. 54, positions A1 to A6, B1 to B6, and C1 to C6 are positions of X-ray detectors 23.1, 23.2, and 23.3 that acquire fluoroscopic images necessary for image reconstruction, respectively. The numbers 1 to 6 assigned to the positions mean the order of imaging, and the first image is taken at the position A1, and the last image is taken at the position A6.

  Also, the positions a1, a2, b1, b2, c1, c2 are focal positions on the X-ray target, and the X-ray detector positions correspond to the positions A1, A2, B1, B2, C1, C2, respectively. To do.

  As described above, in the present embodiment, the X-ray detectors 23.1 and 23.3 at both ends move in synchronization. The middle X-ray detector 23.2 moves independently.

  In the operation example shown in FIG. 54, the X-ray detector 23 does not rotate and moves in parallel in the XY plane. Such an operation example is suitable for using a reconstruction method such as an iterative method or tomosynthesis as described above. This is because iterative techniques and tomosynthesis can be reconstructed regardless of the orientation of the X-ray detector.

  In this operation, since it is not necessary to rotate the X-ray detector, the X-ray detector driving mechanism can be further simplified, the mechanical mechanism can be speeded up, and the maintainability can be improved.

  FIG. 55 is a flowchart of an imaging system inspection process using the linear movement detector described with reference to FIGS. 53 and 54.

  FIG. 56 is an inspection timing chart of imaging for one field of view by the imaging system described with reference to FIGS. 53 and 54.

  Hereinafter, with reference to FIG. 55 and FIG. 56, the inspection process of the X-ray inspection apparatus 130 according to the modification of the sixth embodiment will be described.

  Referring to FIG. 55, first, before starting the inspection, according to a command from the inspection target position control unit 80 of the arithmetic unit 70, the inspection target position control mechanism converts the inspection part (field of view) to be inspected into the X-ray source It is assumed that the inspection is started by imaging with the X-ray detector 23.2 after being placed on a vertical axis passing through the center of the X-ray target. That is, in order to capture a fluoroscopic image, the stage on which the inspection object is placed is moved to a predetermined position, and the X-ray detector 23.2 is moved to an initial position (intermediate position between B3 and B4). The X-ray detectors 23.1 and 23.3 move to the initial positions A1 and C1, respectively. Usually, in the inspection, an optical camera (not shown) is mounted for specifying the inspection position, so that the position can be determined based on the image of the optical camera. As another method, it may be automatically determined based on CAD data to be inspected, or may be performed visually by an operator.

  When the inspection process is started (S1000), immediately after the start of the inspection, the calculation unit 70 positions the X-ray detector 23.2 directly above the X-ray focal point and performs imaging (S1002). The captured image data is transferred to the memory 70 used by the calculation unit 70 (S1004), and the pass / fail determination unit 78 of the calculation unit 70 reconstructs the image of the corresponding part from the X-ray fluoroscopic image obtained in this way. The necessity of configuration inspection is determined (S1006). Again, various methods for determining the necessity (good / bad determination) have been proposed and have already been described above, so the details will not be repeated here.

  If it is determined that the inspection has been completed for the entire field of view (S1036), the arithmetic unit 70 ends the inspection (S1040).

  On the other hand, when the inspection by the reconstructed image is necessary, the calculation unit 70 subsequently performs CT imaging for one visual field.

  Referring to FIGS. 55 and 56, in CT imaging for one visual field, a visual field (reconstruction region or region similar to the above-described fluoroscopic image imaging range) in an inspection object is imaged from a plurality of directions.

  The computing unit 70 moves the X-ray focal point to positions corresponding to the X-ray detectors 23.1 and 23.3 at both ends in a time-sharing manner and emits X-rays, and the X-ray detectors 23.1 and 23.3. (S1010). In parallel with this imaging, the arithmetic unit 70 moves the X-ray detector 23.2 to the next imaging position (B1) (S1020). At this point, the X-ray detector 23.2 only moves and does not transfer imaging data.

  Subsequently, the arithmetic unit 70 transfers the image data obtained by the X-ray detectors 23.1 and 23.3 to, for example, the memory 90 for reconstruction processing in the 3D image reconstruction unit 78 (S1012). In parallel with this, the calculation unit 70 moves the X-ray focal point to a position corresponding to the X-ray detector 23.2, emits X-rays, and images the X-ray detector 23.2 (S1022).

  If it is determined that the prescribed number of images for one field of view has not been completed (S1030), operation unit 70 returns the process to steps S1010 and S1020.

  On the other hand, if the specified number has been reached, the calculation unit 70 ends the CT imaging process for one field of view (S1030), and shifts the process to step S1032.

  In the flowchart, it is determined whether the specified number of images has been captured after the data transfer, but it is preferable to determine the number of images to be captured simultaneously with the data transfer. This is because the data transfer takes about 200 ms, for example, so that the movement to the next imaging position is delayed. Therefore, a delay occurs every time an image is taken. In order to reduce the delay time and increase the speed, it is preferable to determine the prescribed number and move the inspection object / X-ray detector simultaneously with the data transfer.

  Next, the 3D image reconstruction unit 76 of the calculation unit 70 generates a reconstructed image from captured images in a plurality of directions in step S1032.

  Subsequently, the quality determination unit 78 of the calculation unit 70 performs quality determination using the reconstructed image (S1034). Here again, as described above, the quality determination method is well known, and therefore a quality determination method suitable for the inspection item may be used, and detailed description thereof will not be repeated here.

  Further, the calculation unit 70 determines whether or not the inspection of the entire visual field has been completed (S1036), and if not completed, the visual field is moved to the next position and the X-ray detector 23 is also set to the initial position. (S1038), and the process returns to step S1002. On the other hand, if the inspection has been completed for the entire visual field, the arithmetic unit 70 ends the inspection (S1040).

  In FIG. 12, the inspection is performed using the fluoroscopic image and the reconstructed image. However, it is also possible to perform only the inspection using the reconstructed image without performing the inspection using the fluoroscopic image. However, since the reconstruction process usually takes a relatively long time, the entire inspection time can be shortened by performing pass / fail judgment on the fluoroscopic image before the inspection using the reconstructed image.

  As shown in FIG. 56, the X-ray detectors 23.1 and 23.3 perform simultaneous exposure, and the X-ray detector 23.2 moves to an imaging position where an image necessary for image reconstruction can be acquired. When the imaging of the X-ray detectors 23.1 and 23.3 and the movement of the X-ray detector 23.2 are completed, imaging is started by the X-ray detector 23.2, and the X-ray detector 23. 1 and 23.3 move to the next imaging position. By repeating these operations, it is possible to capture a plurality of fluoroscopic images from different angles necessary for image reconstruction without the non-operation time of the X-ray source 10 and the movement of the imaging target.

The imaging time Tv for one field of view is expressed by the following equation.
When Ts> Tm: Tv = 2 / 3NTs
When Ts <Tm: Tv = (N / 3-1) (Ts + Tm) + 2Ts
As an example, the time required for imaging 18 images is 12Ts when Ts> Tm, and 7Ts + 5Tm when Ts <Tm, and the imaging time can be significantly increased.

  With the above configuration, the X-ray inspection apparatus 130 according to the sixth embodiment can exhibit at least one of the following effects or a combination thereof.

  1) The X-ray detectors 23 operate independently, and the non-operation time of the X-ray source 10 in the X-ray detector 23 can be reduced.

  2) Increasing the target current and exposing a plurality of X-ray detectors 23 at the same time enables efficient use of strong X-rays.

  3) By limiting the operation of the X-ray detector to a straight line, the moving mechanism of the X-ray detector 23 can be simplified, and the movement can be speeded up.

  4) A rectangular image captured by the X-ray detector 23 moving in the same direction (moving in parallel) is reconstructed using an iterative image reconstruction algorithm to obtain a wide range of reconstructed images.

  5) In addition, an odd number, for example, one of the three X-ray detectors is configured to pass right above the X-ray source 10 so that it can be used for both fluoroscopic image capturing and reconstructed image capturing. be able to.

  6) When there are three X-ray detectors 23, the X-ray detectors at both ends at the time of central imaging are exposed by shifting the timing between the central X-ray detector and the two X-ray detectors at both ends. Image degradation due to scattered X-rays and scattered X-rays to the center X-ray detector during both-end imaging can be avoided. For example, when an odd number of five or more X-ray detectors 23 are provided, the central X-ray detector, every other X-ray detector, and the remaining X-ray detectors are used. Thus, exposure can be performed by shifting the timing.

  The embodiment disclosed this time should 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.

  10 scanning X-ray source, 11 target, 12 deflection yoke, 13 electron beam converging coil, 14 high-voltage power supply, 15 vacuum pump, 19 electron gun, 16 electron beam, 17 X-ray focal position, 18 X-ray, 20 inspection object, 22 sensor base, 23 X-ray detector, 24 slider, 25 X-ray module, 26 X-ray light receiving unit, 27 data cable, 28 power supply cable, 29 data processing unit, 30 image acquisition control mechanism, 32 rotation angle control unit, 34 Image data acquisition unit, 40 input unit, 50 output unit, 60 scanning X-ray source control mechanism, 62 electron beam control unit, 70 calculation unit, 72 scanning X-ray source control unit, 74 image acquisition control unit, 76 3D image reconstruction Part, 78 pass / fail judgment part, 80 stage control part, 82 X-ray focal position calculation part, 84 imaging condition setting part, 90 memory, 92 X Focus position information, 94 image pickup condition information, 100 X-ray inspection apparatus.

Claims (7)

An X-ray inspection apparatus for performing a reconstruction process of an image of the inspection target region by receiving X-rays transmitted through the inspection target region of the object by a plurality of detection surfaces on the same plane,
An object moving mechanism for moving the object in the XY plane;
An X-ray source that outputs X-rays;
A rectangular X-ray detector for receiving and imaging X-rays at the plurality of detection surfaces with a rectangular field of view;
Detector driving means for moving the X-ray detector to each position corresponding to each detection surface in an XY plane parallel to the plane in which the object moves;
Control means for controlling the operation of the X-ray inspection apparatus,
The detector driving means moves the X-ray detector so that the center of the X-ray detector at each position is located on a circumference with the X-ray source as an origin,
The control means includes
Control is performed to translate the X-ray detector in the XY plane so that the sides of the rectangle of the X-ray detector at each position face the same direction with respect to the detector driving means,
An X-ray inspection apparatus that controls the X-ray source so that X-rays pass through the inspection target region and enter the X-ray detector at an irradiation angle corresponding to each detection surface. The control means includes
A moving mechanism that controls the object moving mechanism to move the object in the XY plane in order to position the object between the X-ray detector and the X-ray source at each position. The X-ray inspection apparatus according to claim 1, further comprising a control unit.   The detector driving means moves the X-ray detector in the XY plane while maintaining the posture of the X-ray detector so that the X-ray detector faces the same direction. The X-ray inspection apparatus according to 1 or 2.   4. The detector according to claim 1, wherein the detector driving unit moves the X-ray detector so that a distance from a focal point of the X-ray source to the X-ray detector at an imaging position is constant. X-ray inspection apparatus as described in the paragraph. The X-ray source includes a fixed focus type X-ray source, X-ray inspection apparatus according to any one of claims 1 to 4. The X-ray detector comprises one or more X-ray detectors, X-ray inspection apparatus according to any one of claims 1 to 5. An X-ray inspection method by an X-ray inspection apparatus that performs an image reconstruction process of an image of an inspection object region by receiving X-rays transmitted through the inspection object region of the object by a plurality of detection surfaces on the same plane. ,
Moving the object in an XY plane;
Outputting X-rays;
Controlling the operation of the X-ray inspection apparatus;
Receiving and imaging X-rays on the detection surface by a rectangular X-ray detector,
The controlling step includes
Moving the X-ray detector to each position corresponding to each detection surface in an XY plane parallel to the plane in which the object moves;
Translating the X-ray detector in the XY plane so that each side of the rectangle of the X-ray detector at each position faces the same direction;
See containing and controlling the X-ray source as X-ray at an irradiation angle corresponding to each of said detection surface is incident on the X-ray detector and transmitted through the inspection target region,
The step of moving the X-ray detector includes the step of moving the X-ray detector so that the center of the X-ray source at each of the positions is located on a circumference having the X-ray source as an origin. X-ray inspection method.

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