WO2009084581A1 - X線検査装置およびx線検査方法 - Google Patents
X線検査装置およびx線検査方法 Download PDFInfo
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- WO2009084581A1 WO2009084581A1 PCT/JP2008/073587 JP2008073587W WO2009084581A1 WO 2009084581 A1 WO2009084581 A1 WO 2009084581A1 JP 2008073587 W JP2008073587 W JP 2008073587W WO 2009084581 A1 WO2009084581 A1 WO 2009084581A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
- G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
- G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/46—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment with special arrangements for interfacing with the operator or the patient
- A61B6/461—Displaying means of special interest
- A61B6/466—Displaying means of special interest adapted to display 3D data
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
- G01T1/2914—Measurement of spatial distribution of radiation
- G01T1/2985—In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis)
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/30—Accessories, mechanical or electrical features
- G01N2223/33—Accessories, mechanical or electrical features scanning, i.e. relative motion for measurement of successive object-parts
- G01N2223/3302—Accessories, mechanical or electrical features scanning, i.e. relative motion for measurement of successive object-parts object and detector fixed
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/40—Imaging
- G01N2223/419—Imaging computed tomograph
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/60—Specific applications or type of materials
- G01N2223/611—Specific applications or type of materials patterned objects; electronic devices
- G01N2223/6113—Specific applications or type of materials patterned objects; electronic devices printed circuit board [PCB]
Definitions
- the present invention relates to an X-ray inspection method and an X-ray inspection apparatus.
- 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.
- LSI BGA and CSP packages greatly contribute to ultra-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.
- Patent Document 1 discloses an X-ray tomographic surface 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.
- 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.
- a “filtered back projection method” is cited as a reconstruction method.
- 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.
- 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.
- it 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.
- 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.
- 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.
- 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.
- 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.
- 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
- 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).
- the X-ray absorption coefficient distribution along the path t is expressed 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).
- FIG. 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 3D image reconstruction based on this 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.
- the operation for obtaining the X-ray absorption coefficient distribution f (x, y, z) by adding the projection data along the path t through which the X-ray has passed from the projection data is called back projection.
- projection data is simply added, blurring occurs due to the point spread function of the imaging system, and thus the projection data is filtered.
- 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 image reconstruction procedure in this embodiment is shown below.
- 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.
- 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.
- v pa ′ + pb ′.
- This operation is performed on all the reconstruction pixels V in the reconstruction area (field of view) FOV, whereby 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.
- S5002 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).
- an unprocessed reconstruction pixel V in the reconstruction field of view FOV is selected (S5008), and a detector pixel corresponding to the reconstruction pixel V is obtained (S5010).
- 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.
- 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).
- FIG. 60 is a conceptual diagram showing the concept of processing in an iterative method when a scanning X-ray source is used.
- FIG. 61 is a top view of the conceptual diagram of FIG. 60 viewed from above.
- a vector ⁇ 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 “ ⁇ ” 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).
- 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.
- the intermediate projection data vector q is the actual measured detector pixel value, as described below.
- the solution ⁇ is obtained by an iterative operation that updates the assumed vector ⁇ until Pa or Pb can be regarded as coincident with the projection data.
- J is the number of pixels in the reconstruction area (field of view)
- I is the number of pixels in the projection data.
- T represents transposition.
- a projection operation relating ⁇ and p is represented by an I ⁇ J coefficient matrix of the following equation (6).
- the image reconstruction by the iterative method can be formulated as a problem of obtaining ⁇ by solving the following equation (7) linear equation.
- vj be the contribution of vj to pi.
- W represents how much the pixel value ⁇ 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.
- Non-Patent Document 2 As an iterative method, a method of algebraically solving an equation, a method considering statistical noise, and the like have been devised, but SART (Simultaneous Algebraic Reconstruction Technique) which is a commonly used algebraic method is described below. ). Details are described in Non-Patent Document 2.
- the initial reconstructed image ⁇ 0 may be all zero data, or data acquired from CAD (Computer Aided Design) data or the like may be assumed.
- CAD Computer Aided Design
- intermediate projection data q 0 represented by the following formula (9) (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 ⁇ 0 is updated.
- the formula used for updating (iteration formula) is as shown in formula (10).
- the reconstructed image data generated by the above calculation is substituted as an initial image, and reconstructed image data is obtained by repeating the same process a plurality of times.
- FIG. 62 is a flowchart for explaining the process of the iterative method.
- an iterative method is started (S5102)
- an initial reconstructed image is set (S5104).
- the initial reconstructed image for example, all values may be zero.
- projection data to be processed is selected from a plurality of projection data corresponding to a plurality of X-ray detector positions (S5106).
- 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).
- the value of the reconstructed pixel V is updated (S5114).
- 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.
- 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).
- a three-dimensional image of the inspection object can be reconstructed from the projection data acquired by 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.
- 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.
- an X-ray inspection apparatus capable of inspecting a plurality of portions of an inspection object at high speed without moving the inspection object, and an X-ray inspection method using such an X-ray imaging method. ing.
- an X-ray inspection apparatus for performing reconstruction processing of an image of an inspection target region by imaging X-rays transmitted through the inspection target region of an object with a plurality of detection surfaces.
- the This X-ray inspection apparatus includes a plurality of X-ray detectors for imaging with a plurality of detection surfaces, the number of which is smaller than the number of detection surfaces, and a part of the plurality of X-ray detectors and the other part.
- the X-rays are output in association with the detector drive unit that moves independently and the X-rays that have passed through the inspection target area so that they are incident on a plurality of X-ray detectors that have moved to a plurality of imaging positions serving as detection surfaces.
- An X-ray output unit that controls the operation of the X-ray inspection apparatus.
- the control unit captures an image with a plurality of detection planes, an image acquisition control unit for controlling the exposure timing of each X-ray detector and a detector driving unit, an X-ray output control unit for controlling the X-ray output unit, and the like.
- an image reconstruction processing unit for reconstructing image data of the inspection target area based on the intensity distribution data of the X-rays transmitted through the inspection target area.
- the image acquisition control unit and the X-ray output control unit include a process of imaging a part of the plurality of X-ray detectors at a first position among the plurality of imaging positions, and a plurality of X-ray detectors. A process of moving another part to a second position different from the first position among the plurality of imaging positions is executed in parallel.
- 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.
- a process of imaging a part of the plurality of X-ray detectors at the first position, and a process of moving to the next first position different from the first position after the imaging For the other part of the plurality of X-ray detectors, the first position, the next first position, and the previous second position in parallel with the process of imaging a part at the first position.
- the process of moving a part to the next first position which is different from both, and the process of imaging at the second position Let it run.
- the X-ray output control unit 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.
- the X-ray output unit generates an X-ray by moving the X-ray focal point position of the X-ray source to each starting point position.
- the X-ray output unit moves the focal point of the X-ray source by deflecting an electron beam irradiated onto a target surface that is a continuous surface of the X-ray source.
- an X-ray inspection apparatus for performing an image reconstruction process of an inspection target region by imaging X-rays that have passed through the inspection target region of an object with a plurality of detection surfaces. Is done.
- a plurality of X-ray detectors having a number smaller than the number of detection surfaces for imaging with a plurality of detection surfaces and a part of the plurality of X-ray detectors along a predetermined one-axis direction X-rays are output in association with the uniaxial drive unit to be moved and the X-rays that have passed through the region to be inspected so as to be incident on a plurality of X-ray detectors that have moved to a plurality of imaging positions serving as detection surfaces.
- a line output unit, and a control unit that controls the operation of the X-ray inspection apparatus captures an image with a plurality of detection planes, an image acquisition control unit for controlling the exposure timing of each X-ray detector and a detector driving unit, an X-ray output control unit for controlling the X-ray output unit, and the like. And an image reconstruction processing unit for reconstructing image data of the inspection target area based on the intensity distribution data of the X-rays transmitted through the inspection target area.
- the uniaxial driving unit moves the plurality of X-ray detectors in parallel within a predetermined plane.
- the detection surfaces of the plurality of X-ray detectors each have a rectangular shape.
- the detector driving unit includes a rotation unit that rotates the plurality of X-ray detectors so that one end of the detection surface of the plurality of X-ray detectors intersects the direction toward the X-ray output unit at each imaging position.
- the image reconstruction processing unit reconstructs the image data of the inspection target area by an iterative method.
- the image reconstruction processing unit reconstructs the image data of the inspection target area by an analytical method.
- an X-ray inspection apparatus for performing an image reconstruction process of an inspection target region by imaging X-rays that have passed through the inspection target region of an object with a plurality of detection surfaces. Is done.
- This X-ray inspection apparatus has a plurality of X-ray detectors for imaging on a plurality of detection surfaces, a plurality of X-ray detectors that are fewer than the number of detection surfaces, and a plurality of imagings in which X-rays that have passed through the inspection target area are detection surfaces.
- An X-ray output unit that outputs X-rays so as to be incident on a plurality of X-ray detectors moved to a position and a control unit that controls the operation of the X-ray inspection apparatus.
- the control unit captures an image with a plurality of detection planes, an image acquisition control unit for controlling the exposure timing of each X-ray detector and a detector driving unit, an X-ray output control unit for controlling the X-ray output unit, and the like. And an image reconstruction processing unit for reconstructing image data of the inspection target area based on the intensity distribution data of the X-rays transmitted through the inspection target area.
- the image acquisition control unit and the X-ray output control unit include a process of imaging a part of the plurality of X-ray detectors at a first position among the plurality of imaging positions, and a plurality of X-ray detectors. A process of moving another part to a second position different from the first position among the plurality of imaging positions is executed in parallel.
- the X-ray output unit outputs X-rays from a plurality of X-ray focal positions corresponding respectively to a plurality of X-ray detectors simultaneously in an imaging state among a plurality of X-ray detectors arranged at the imaging position. Is generated.
- the X-ray inspection apparatus transmits X-rays from the X-ray output unit to the X-ray detectors that are in the imaging state at the same time from the corresponding X-ray focal position through the inspection target region, and each detection surface. X-rays incident on the X-rays are transmitted, while X-rays from X-ray focal positions that do not correspond are further shielded.
- the X-ray output unit moves the focal point of the X-ray source by deflecting an electron beam irradiated onto a target surface that is a continuous surface of the X-ray source.
- the X-ray output control unit controls the X-ray output unit so that the X-rays are incident on each of the X-ray detectors that are in the exposure state at the same time.
- an X-ray inspection apparatus for performing an image reconstruction process of an inspection target region by imaging X-rays that have passed through the inspection target region of an object with a plurality of detection surfaces. Is done.
- This X-ray inspection apparatus has a plurality of X-ray detectors for imaging on a plurality of detection surfaces, and a parallel drive for moving the plurality of X-ray detectors in parallel within a predetermined plane.
- An X-ray output unit that outputs X-rays in correspondence with X-rays transmitted through the inspection target region so as to be incident on a plurality of X-ray detectors moved to a plurality of imaging positions serving as detection surfaces, And a control unit that controls the operation of the X-ray inspection apparatus.
- the control unit captures an image with a plurality of detection planes, an image acquisition control unit for controlling the exposure timing of each X-ray detector and a detector driving unit, an X-ray output control unit for controlling the X-ray output unit, and the like. And an image reconstruction processing unit for reconstructing image data of the inspection target area based on the intensity distribution data of the X-rays transmitted through the inspection target area.
- the detector driving unit includes a biaxial driving unit that independently moves a plurality of X-ray detectors along a predetermined biaxial direction.
- an image of the inspection target area is reconstructed by imaging X-rays that have passed through the inspection target area of the object with X-ray detectors corresponding to a plurality of detection surfaces, respectively.
- An X-ray inspection method is provided. This X-ray inspection method includes a step of independently moving each X-ray detector to an imaging position serving as a corresponding detection surface, and a plurality of X-rays in which X-rays transmitted through the inspection target area have moved to a plurality of imaging positions, respectively. The step of outputting X-rays so as to be incident on the line detector is different from the process of imaging a part of the plurality of X-ray detectors at the first position among the plurality of imaging positions.
- 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 of imaging a part of the plurality of X-ray detectors at the first position, a process of moving to the next first position different from the first position after the imaging, and the plurality of X-ray detectors The second part is different from any one of the first position, the next first position, and the previous second position in parallel with the process of capturing an image of the part at the first position.
- a process of performing imaging at the second position is included.
- the step of outputting X-rays includes a step of moving 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.
- the X-ray inspection method and X-ray inspection apparatus according to the present invention can selectively inspect a predetermined inspection area of an inspection object at high speed.
- 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.
- the X-ray inspection method and the X-ray inspection apparatus according to the present invention it is possible to inspect a plurality of parts of an inspection object at high speed.
- FIG. 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.
- FIG. 6 is a flowchart of the entire inspection for reconstructed image inspection of any of the moving mechanisms of FIGS. It is a timing chart of the whole test
- FIG. 7 is a flowchart showing processing for CT imaging of one field of view described in FIG. 6.
- 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. 10 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. 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.
- FIG. 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. 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
- 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
- FIG. 29 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
- FIG. 2 is a conceptual diagram showing a configuration of a detector used as an X-ray detector 23.
- FIG. 2 is a conceptual diagram showing a configuration of a detector used as an X-ray detector 23.
- FIG. 2 is a conceptual diagram showing a configuration of a detector used as an X-ray detector 23.
- 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. 6 is a timing chart for explaining the operation of a scanning X-ray source when four X-ray detectors 23.1 to 23.4 are used.
- 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.
- 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. 46 is a flowchart of inspection processing for one field of view of the imaging system described in FIGS. 44 and 45.
- 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. 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.
- 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
- 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.
- FIG. 1 is a schematic block diagram of an X-ray inspection apparatus 100 according to the present invention.
- the X-ray inspection apparatus 100 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. Further, the X-ray inspection apparatus 100 includes the X-ray detectors 23.1 to 23. 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- the scanning X-ray source 10 is a transmissive type.
- 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.
- X-ray emission starting position a position that should be the starting point of X-ray emission set according to the inspection target portion of the inspection object.
- the target is not a ring but a continuous surface so that the degree of freedom in setting the position can be increased.
- the positions are not particularly distinguished and described, they are simply indicated as the X-ray focal position 17 as a generic name.
- the position of the X-ray source itself can be mechanically moved each time.
- 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.
- a plurality of X-ray sources can be provided and switched according to the starting point position.
- the “X-ray emission starting position” is the X-ray detector used for imaging 23. If the spatial position of i (i is the specified one of 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.
- 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.
- X-ray detectors 23.1 to 23.N are collectively referred to as “X-ray detector 23”. It is arranged between.
- the inspection object 20 When moving the position of the inspection object 20, 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.
- 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.
- 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.
- a CCD (Charge Coupled Device) camera I.D. I. (Image Intensifier).
- I.D. I. Image Intensifier
- a space-efficient FPD flat panel detector
- 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 driving unit 22 can be known by a position sensor (not shown), and can be taken into the calculation unit 70 via the detector driving control unit 32.
- the X-ray detector driving unit 22 can be moved up and down in order to adjust the enlargement ratio.
- 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.
- 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 quality 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 3D data from a plurality of image data acquired by the image acquisition control unit 74.
- the pass / fail judgment unit 78 judges pass / fail of the inspection object 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 symmetrical position control unit 80 controls a mechanism (not shown) for moving the inspection object 20, for example, a stage.
- the X-ray focal position calculation unit 82 calculates an X-ray focal position, an irradiation angle, and the like for the inspection area when inspecting an inspection area where the inspection object 20 is present. 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.
- 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).
- the X-ray inspection apparatus 100 can reduce this idle time that does not contribute to the speeding up of the entire system.
- FIG. 3 is a conceptual diagram showing an example of the first moving mechanism.
- the X-ray source 35 and the X-ray detector 36 are fixed, and the visual field 37 is mechanically moved (rotated) on the stage 38, thereby obtaining a plurality of imaging numbers necessary for reconstruction.
- FIG. 4 is a conceptual diagram showing an example of the second moving mechanism.
- the X-ray detector 36 is mechanically translated in the XY plane and rotated in the ⁇ direction, and the field of view 37 (inspected portion to be inspected) is also translated in the XY plane. By doing so, a plurality of image pickup numbers necessary for reconstruction are obtained.
- FIG. 5 is a conceptual diagram showing an example of the third moving mechanism.
- the X-ray detector 36 is mechanically rotated in the ⁇ direction, and the field of view 37 (inspection portion to be inspected) is also translated in the XY plane, thereby obtaining a plurality of images necessary for reconstruction. Get the number.
- FIG. 6 is a diagram showing a flowchart of the entire inspection for reconstructed image inspection using any one of the moving mechanisms shown in FIGS.
- 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.
- a fluoroscopic image is captured (S104), the fluoroscopic image is inspected, and the quality of the field of view to be inspected (range captured by the fluoroscopic image) is determined from the acquired fluoroscopic image (S106).
- CT imaging for one field of view is subsequently performed (S110).
- the visual field reconstruction region or region similar to the above-described fluoroscopic image imaging range
- the inspection object is imaged from a plurality of directions.
- 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).
- 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 taken as CT images. The definitions of symbols are shown below.
- 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
- imaging X Let Ts be the exposure time of the line detector.
- 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).
- FIG. 8 is a flowchart showing the process of CT imaging of one field of view described in FIG.
- 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.
- 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.
- the image data captured by the X-ray detector is transferred to the arithmetic 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.
- the specified number of images is 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 a process of performing imaging in a plurality of directions in the process of CT imaging of one field of view described with reference to FIG.
- 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).
- Tv NTs + (N / S-1) Tm
- Tv NTs + (N-1) Tm (14)
- 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.
- At least two or more X-ray detectors 23 are provided, and the X-ray detector driving unit 22 is configured to be independently movable.
- the other X-ray detector 23.2 is moved to a predetermined position in preparation for imaging.
- the X-ray detector 23.2 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.
- the X-ray detector driving unit 22 has an XY ⁇ operation mechanism capable of driving the X-ray detectors 23.1 and 23.2 with XY ⁇ degrees of freedom.
- a scanning X-ray source is used.
- an inspection target position drive mechanism 1020 for example, an XY stage
- an inspection target position control unit 80 are provided to move the position of the inspection target.
- 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- ⁇ operation independently. As will be described later, the ⁇ rotation mechanism does not necessarily have to be provided depending on how the X-ray detector 23 is driven.
- the X-ray detector driving 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, if it is configured to enable such movement in the XY direction or ⁇ rotation in the XY plane, and has the same function for movement of the X-ray detector 23, this It is also possible to use mechanisms other than.
- the visual field 37 to be inspected is X-independent of the X-ray detector 23.1 or 23.2 by the inspection target position driving mechanism 1020 controlled by the inspection target position control unit 80 in the calculation unit 70. Y operation 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 1020 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 calculation 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. 11A and FIG. 11B are diagrams showing the 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 100 shown in FIG.
- Operation example 1 shown in FIG. 11A is a top view of the configuration shown in FIG. 10 and represents imaging position movement by the XY ⁇ operation, and images 16 X-ray fluoroscopic images from the same angle.
- An assumed operation example 1 is shown.
- the operation example 1 is suitable for using an analytical method represented by a method by Feldkamp and the like.
- 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 shown in FIG. 11B represents imaging position movement by XY operation, and 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.
- 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.
- FIGS. 11A and 11B The operation example (movement trajectory) shown in FIGS. 11A and 11B will be described in more detail as follows.
- Positions A1 and B1 in FIGS. 11A and 11B 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.
- the X-ray detectors 23.1 and 23.2 move at a constant distance around the origin of the imaging system. 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.
- the X-ray detectors 23.1 and 23.2 are assumed to be stationary at positions A1 and B1, respectively.
- X-rays are generated from the X-ray focal point position a1, and imaging is performed by the X-ray detector 23.1 (position A1).
- 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.
- FIG. 12 is a diagram showing a flowchart of the entire inspection for the reconstructed image inspection performed by the X-ray inspection apparatus 100 according to the first embodiment.
- 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.
- 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.
- it may be automatically determined based on CAD data to be inspected, or may be performed visually by an operator.
- 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.
- 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.
- the arithmetic unit 70 ends the inspection (S318).
- the arithmetic unit 70 subsequently performs CT imaging for one visual field (S310).
- 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.
- the 3D image reconstruction unit 76 of the calculation unit 70 generates a reconstruction image from 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.
- the quality determination unit 78 of the calculation unit 70 performs quality determination using the reconstructed image (S314).
- 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.
- a position of a part (for example, a BGA solder ball) is specified in the reconstructed 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.
- the calculation unit 70 determines whether or not the inspection of all fields 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).
- the inspection is performed with the fluoroscopic image and the reconstructed image, but it is also possible to perform the inspection with the reconstructed image without performing the inspection with the fluoroscopic image.
- 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 showing a flowchart of CT imaging of one field of view in step S310 described in FIG.
- FIG. 14 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.
- the left row is the operation of the X-ray source
- the central row is the operation of the X-ray detector 23.1
- the right row is the operation of the X-ray detector 23.2. This means that the processes arranged in the horizontal direction are performed at the same time.
- the calculation unit 70 moves the inspection object to move the field of view to be inspected to an appropriate position.
- 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 object position may be set using an encoder mounted on the X-ray detector driving unit 22 or the inspection object position driving mechanism (for example, an XY stage). Alternatively, it may be set using a general-purpose detector (laser displacement meter or the like).
- 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
- the imaging time may be set in advance, or the user can set it to a desired time by visual observation.
- 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).
- 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 takes an image with the X-ray detector 23.2 (S424).
- 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).
- 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.
- 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.
- the imaging time for one field of view can be expressed by the following equations (15) and (16).
- Tv NTs
- Tm Time for imaging one field of view
- Tm Time for moving mechanism (stage / X-ray detector) to move
- Ts Imaging (X-ray detector exposure) time
- N Number of images (integer multiple of the number of X-ray detectors)
- Tv Time for imaging one field of view
- Tm Time for moving mechanism (stage / X-ray detector) to move
- Ts Imaging (X-ray detector exposure) time
- FIG. 14 shows a case where Ts ⁇ Tm.
- the exposure time of the X-ray detector necessary for imaging becomes shorter. 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.
- 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.
- FIG. 15 shows an operation mechanism of the X-ray detector drive unit 22 in which the X-ray detector support unit 22.3 can rotate and the rail shape can move in the Y direction.
- 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.
- FIGS. 1 and 10 The same parts as those in FIGS. 1 and 10 are denoted by the same reference numerals. 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.
- the number of X-ray detectors may be two or more.
- 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.
- 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.
- the field of view of the inspection target is the inspection target position drive mechanism 1020 (XY stage on which the inspection target is mounted) controlled by the inspection target position control unit 80 in the calculation unit 70.
- the field of view to be inspected can perform an XY operation independently of the X-ray detectors 23.1, 23.2 and 23.3.
- 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 1020 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 through a detector drive control unit 32 according to a command from the calculation unit 70. 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 calculation 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 of the movement trajectory between the X-ray detector 23 and the scanning X-ray source in the configuration of the X-ray inspection apparatus 102 shown in FIG.
- FIG. 16 is an operation example in which the configuration of FIG. 15 is viewed from above, and it is assumed that 18 X-ray fluoroscopic images are taken from different angles.
- 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.
- 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 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 16 is suitable for using an analytical method typified by the Feldkamp 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.
- 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.
- the X-ray detector drive 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.
- FIG. 18 shows a portion of CT imaging for one field of view in step S310 of FIG.
- FIG. 13 is a diagram illustrating a flowchart of CT imaging of one field of view in step S310 described 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 the operations of the X-ray detector and the X-ray focal position along the inspection time in the inspection flow shown in FIG.
- the arithmetic unit 70 moves the inspection object to move the field of view to be inspected to an appropriate position.
- 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 object position may be set using an encoder mounted on the X-ray detector driving unit 22 or the inspection object position driving mechanism (for example, an XY stage). Alternatively, it may be set using a general-purpose detector (laser displacement meter or the like).
- 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 takes an image 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.
- 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).
- 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). .
- 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.
- the data is transferred to the memory 90 (S526).
- 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.
- 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).
- the calculation unit 70 ends the CT imaging process for one field of view (S542), and the process proceeds to step S312.
- 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.
- Tv NTs
- Tv (N / 3-1) (Ts + Tm) + 3Ts
- N Number of images (integer multiple of the number of X-ray detectors)
- Tv time to image one field of view
- Tm time to move the moving mechanism (stage / X-ray detector)
- Ts time to image (exposure of X-ray detector) Note that the number of images N is easy to understand For this reason, it is an integer multiple of the number of X-ray detectors, but it is not necessarily limited to an integer multiple.
- 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 necessary for reconstruction is 18Ts when 2Ts> Tm, and 8Ts + 5Tm when 2Ts ⁇ Tm. In either case, one detection is performed.
- the imaging time can be shortened compared to (16Ts + 15Tm) when the instrument is used.
- Tm 18Ts + 5Tm when three X-ray detectors are used.
- 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.
- 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.
- the X-ray inspection apparatus 102 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 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.
- 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.
- 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.
- an odd number of five or more X-ray detectors may be provided.
- 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, 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.
- 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 2110, 2120, 2130 are provided and three X-ray sources are operated simultaneously, X-rays from an X-ray source to which X-rays should be incident on one X-ray detector are installed at a position 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.
- 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 not a scanning X-ray source but an imaging system composed of a plurality of, for example, three fixed focus X-ray sources.
- the X-ray detectors 23.1, 23.2 and 23.3 perform a linear operation integrally.
- X-ray detectors 23.1, 23.2 and 23.3 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.
- 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.
- 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.
- 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.
- the X-ray detector drive mechanism can be further simplified, the mechanical mechanism can be speeded up, and the maintainability can be improved.
- Hs Hs / Ho
- Hs represents the height from the X-ray focal point to the X-ray detector
- 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.
- FIG. 24 shows the CT imaging portion for one field of view in step S310 of FIG.
- FIG. 24 is a diagram showing a flowchart of CT imaging of one field of view in step S310 described in FIG.
- FIG. 25 is a timing chart showing the operation of the X-ray detector and the X-ray focal position along the inspection time in the inspection flow shown in FIG.
- 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).
- 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
- 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.
- the data is transferred to the memory 90 for reconstruction processing in the 3D image reconstruction unit 78 (S606).
- the calculation unit 70 determines whether 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.
- 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 X
- the inspection object is divided into M (for example, 4) fields of view and 18 images are taken as CT images.
- 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.
- 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.
- 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.
- 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.
- the tomographic image used for 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 to connect a plurality of fields of view to form a wide area. This is because inspection objects can be included.
- FIG. 26 shows a visual field (inspection object) or X-ray detector 23.
- FIG. 10 is a conceptual diagram for explaining a region that can be formed as an inspection region 2600 by CT imaging for one visual field when N is rotated and imaged;
- the area that can be used for inspection is a circle in a section with a reconstructed image.
- 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.
- a rectangular portion is cut out from the circular reconstruction area 2610 obtained by the analytical method, one visual field area is reduced, and it takes time to inspect a wide inspection area.
- the shape of the reconstruction area is a portion where images captured by a rectangular X-ray detector overlap.
- 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.
- the reconstructed region is a circle with a radius of 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 .
- 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.
- 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.
- 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.
- the inspection object is divided into M (for example, 4) fields of view and N images are taken as CT images.
- M for example, 4
- N images are taken as CT images.
- the symbols are the same as those defined above.
- the CT imaging time Ti of the entire inspection object is the total of (M-1) mechanical movement times when M fields of view are imaged, and is expressed by the following equation (18).
- FIG. 28 is a diagram illustrating the CT imaging time for one field of view.
- 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)
- 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.
- 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.
- the number of X-ray detectors 23 is one or more, and the X-ray detectors 23 are arranged in parallel to rectangular regions required as inspection regions (fields 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.
- 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.
- 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.
- a fixed focus type X-ray source is used as the X-ray source 10.
- an inspection target position drive mechanism 1020 for example, an XY stage
- An inspection target position controller 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.
- any other mechanism can be used as long as it is configured to enable such movement in the XY direction and has the same function as 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 drive mechanism 1020 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 calculation 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 top view showing the movement trajectory between the X-ray detector 23 and the visual field to be inspected in the configuration of the X-ray inspection apparatus 106 shown in FIG.
- the operation example 1 shown in FIG. 30 is a top view of the configuration shown in FIG. 29, and shows an operation example assuming that 16 X-ray fluoroscopic images are taken from the same angle.
- 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.
- 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.
- positions T1 and T2 are visual field positions, which correspond to the 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.
- FIG. 31 is a diagram showing a flowchart of CT imaging of one visual field in step S310 described in FIG.
- the calculation unit 70 moves the inspection object within 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.
- 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
- the imaging time may be set in advance, or the user can set it to a desired time by visual observation.
- 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.
- the data is transferred to the memory 90 (S706).
- 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.
- FIG. 32 is a conceptual diagram showing an inspection region of an imaging system using a translational X-ray detector.
- the reconstruction area (field of view) 3210 has a rectangular X-ray detector 23. This is a portion where the images picked up by N overlap.
- the rectangles overlap from a plurality of angles, the rectangles are circular.
- the overlapping portions are rectangles.
- the reconstruction area is circular, the area to which the inspection algorithm can be applied is rectangular, so only the rectangular part inside the circle can be used, and the area that can be inspected at one time is small.
- the inspection time can be shortened.
- 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.
- the reconstructed region is a square having a side length of 2L. Therefore, when the inspection area 3200 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.
- 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.
- 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.
- 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 expressed by the equation (20) because it is the total of M / 2 mechanical movement times after imaging M / 2 fields of view.
- 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 movement mode of the X-ray detector and the inspection object (stage) is limited to the two axes XY, thereby simplifying the mechanism of the moving means and increasing the moving speed.
- 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 shortening of the inspection time by driving the X-ray source in pulses will be described.
- the X-ray intensity should be as strong as possible.
- 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 electron beam current is increased, the target can be irradiated with the electron beam only for a short time until reaching a temperature at which there is a risk of thermal damage.
- 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.
- 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, illustrations are omitted except for parts that are directly necessary for the description.
- the X-ray inspection apparatus 900 shown in FIG. 34 is configured using a scanning X-ray source 10 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 37 in the inspection target can be moved XY independently of the X-ray detectors 23.1 to 23.4 and the X-ray source by the inspection target position driving mechanism 1020.
- X-rays can be irradiated to one field of view from different angles by scanning the X-ray focal point. Therefore, 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 a straight line connecting the center of each detector and the visual field center intersects with the target.
- the detector driving unit 22 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.
- FIG. 35 is a diagram showing a flowchart of CT imaging of one field of view in step S310 described in FIG.
- FIG. 36 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.
- 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).
- 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).
- 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).
- the calculation unit 70 irradiates the X-ray detector 23.4 with X-rays from the X-ray focal point 17, and images with the X-ray detector 23.4 (S808).
- the arithmetic unit 70 transfers the image data obtained by the X-ray detectors 23.1 to 23.4 to the memory 90, for example, for reconstruction processing by the 3D image reconstruction unit 78 (S810).
- 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 calculation unit 70 ends the CT imaging process for one field of view (S816), and shifts the process to step S312.
- step S814 the arithmetic unit 70 moves the X-ray detector drive mechanism 22 to the next predetermined position (in this case, position 2), and the process proceeds to step S802.
- steps S802 to S810 and S814 is repeated until it is determined in step S812 that the specified number has been reached.
- an inspection target is divided into M (for example, four) fields of view and N images are taken as CT images with reference to the multi-field imaging timing chart of one field of view in FIG.
- N images are taken as CT images with reference to the multi-field imaging timing chart of one field of view in FIG.
- the definitions of symbols are as described above.
- the CT imaging time Ti of the entire inspection object is expressed by the equation (21) since M fields of view are imaged and the total of (M-1) mechanical movement times.
- the CT imaging time Tv for one field of view is expressed by Expression (22) in order to perform N times of imaging using S X-ray detectors and N / S times of movement. At this time, the data transfer of the captured image is performed simultaneously with the mechanical movement.
- the X-ray inspection apparatus 110 has a configuration described below, thereby reducing the time required for imaging.
- 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.
- the scanning X-ray source can move the X-ray focal point position at high speed.
- 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.
- 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.
- the corresponding X-ray focal point position is irradiated with a strong electron beam in multiple times.
- 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.
- a plurality of X-ray detectors can be used for imaging at the same time, the entire imaging time is shortened.
- FIG. 37 is a block diagram for explaining the configuration of the X-ray inspection apparatus 110 of the fourth embodiment.
- X-ray detectors 23.1 to 23.4 are fixed on a circular sensor base 22.6 at an angle of 90 degrees on the same circumference. Has been. As 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.
- 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.
- FIG. 37 the illustration of the portions that are not directly related to the following description in the configuration of FIG. 1 is omitted.
- 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 imaging, the X-ray focal point stops at a plurality of times at focal positions a to d corresponding to the respective X-ray detectors.
- the X-ray detector driving unit 22 moves the four X-ray detector positions simultaneously to the next imaging position.
- 38A and 38B are conceptual diagrams showing a configuration of a detector used as the X-ray detector 23.
- FIG. 38A and 38B are conceptual diagrams showing a configuration of a detector used 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 can be used.
- the X-ray detector 23 converts incident X-rays into electrons by various methods, and then a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide). Semiconductor)
- CCD Charge Coupled Device
- CMOS Complementary Metal Oxide
- 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 the 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 when the configuration of FIG. 37 is viewed from above, assuming 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.
- the positions to which the X-ray detectors 23.1 to 23.4 move when imaging one field of view are A1 to A4, B1 to B4, C1 to C4, and D1 to D4, respectively.
- the X-ray focal positions corresponding to the X-ray detector positions are represented by a1, a2, b1, b2, c1, c2, d1, d2, etc.
- 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. .
- 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.
- the field of view is set on the axis of rotational movement of the X-ray detector.
- Two or more X-ray detectors 23 (four in this example) are used.
- the X-ray detectors move on a circular orbit while maintaining their relative positional relationship. 5) The X-ray detector is stationary during imaging.
- a scanning X-ray source capable of moving the X-ray focal point at high speed is used.
- a shield 66 having a fixed position is installed.
- 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.
- 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.
- the arithmetic unit 70 stops the irradiation of the X-ray source (S822).
- the calculation unit 70 determines whether or not the total number of captured images has reached the prescribed number, and repeats the processing of steps S822 to S824 until the prescribed number is reached (S826).
- 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.
- the time for moving the X-ray focal point position is negligibly short compared with the time required for exposure.
- 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.
- the time Ts required for image acquisition can be reduced to 1/2 Ts.
- 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 the timing chart (b).
- 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.
- the X-ray focal point position is moved at a much shorter time interval than when the target temperature reaches equilibrium.
- a means one of the focal positions a1 to a4 corresponding to the current position of the X-ray detector 23.
- the imaging time for one field of view can be expressed by equation (23).
- the number of images N is an integral multiple of the number of detectors.
- N Number of images (integer multiple of the number of X-ray detectors)
- S Number of X-ray detectors
- Tv Time for imaging one field of view
- Tm Time for moving mechanism (stage / X-ray detector)
- Tss Imaging for simultaneous exposure of S X-ray detectors (X (Exposure time of line detector)
- 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.
- the imaging time can be shortened as compared with (16Ts + 3Tm) when the four detectors described in FIG. 34 are used.
- FIG. 43A and 43B are conceptual diagrams showing the structure of a scanning X-ray source.
- FIG. 43A shows an example of the internal configuration of an X-ray source using a transmission target
- FIG. 43B shows an example of a reflection target.
- the scanning X-ray source since the scanning X-ray source has such a structure, the operation as in the fourth embodiment is possible.
- the electron beam emitted from the electron gun 4330 passes through the grid 4340, and then the spot diameter of the electron beam is reduced by the converging lens 4350. Further, the electron beam is bent in the X and Y directions by an externally controlled deflector 4360 and collides with an arbitrary position on the X-ray target (the electron beam colliding with the targets 4310 and 4320 is generally converted into a target current). Called).
- the X-ray target has a transmission type (FIG. 43A) and a reflection type (FIG. 43B).
- the transmission type generally tungsten on beryllium or aluminum is deposited.
- 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.
- 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.
- the X-ray inspection apparatus is configured by combining such an eccentric CT imaging and the X-ray detector driving unit 22 as described in the modification of the first embodiment.
- 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).
- the movement from the visual field to the visual field is realized by mechanically moving the inspection object with an XY stage or the like.
- 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.
- the mechanical position can be eliminated and the imaging position can be moved at high speed.
- 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 of the fifth embodiment.
- 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.
- 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.
- the range in which the X-ray detector 23.1 and the X-ray detector 23.2 can operate independently is required to be able to operate as shown in FIG.
- 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.
- 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.
- each has a semicircular locus.
- the movement of the X-ray detector 23 is not limited to the circular orbit.
- 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
- the focal position a2-1 indicates the focal point with respect to the X-ray detector position A1 when imaging the visual field 2.
- the focal positions a1-2, a1-3, and a1-4 are sequentially targeted from the focal position a1-1 according to the X-ray detector positions A1 to A4.
- the focus position a2-1 is sequentially positioned from the focus position a2-1 in accordance with the X-ray detector positions A1 to A4.
- the focal positions a2-2, a2-3, and a2-4 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
- the focal position b2-1 indicates the focal point with respect to the X-ray detector position B1 when imaging the visual field 2.
- the focal position b1-1 and the focal position b2-1 are also circular trajectories like the dotted line in the figure on the target according to the X-ray detector positions B1 to B4. Move to another focus position above.
- the time for moving the visual field 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.
- the imaging is performed so that the imaging angle differs depending on the field of view.
- FIG. 46 is a flowchart of inspection processing for one field of view of the imaging system described in 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.
- the visual field (inspection object) and the X-ray detector 23 are at predetermined initial positions A1 and B1.
- the calculation unit 70 causes the X-ray detector 23.1 to image the inspection target (S902). That is, the calculation unit 70 moves the X-ray focal point to a 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.
- the calculation unit 70 transfers the image data captured by the X-ray detector 23.1 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.
- 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 at the same time, 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.
- the calculation unit 70 transfers the image data captured by the X-ray detector 23.2 to the calculation unit 70 (S912).
- 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.
- 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.
- 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.
- 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.
- Tv (N / S-1) Tm + STs
- Tv (N / S-1) Tm + STs
- 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.
- 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). .
- the X-ray detector 23.1 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.
- 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.
- the CT imaging time for one field of view is obtained and is expressed by Expression (24).
- 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).
- FIG. 48 is an inspection timing chart for the entire inspection of the imaging system described with reference to FIGS. 44 and 45.
- the inspection object is divided into M (for example, 4) fields of view and N images are taken as CT images.
- M for example, 4
- N images are taken as CT images.
- 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.
- Time for imaging the entire inspection object Tv Time for imaging one field of view Te: Time for moving the field of view
- Tv Time for imaging one field of view
- Te Time for moving the field of view
- 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.
- 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.
- 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 or 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.
- the positions A1 to A3, the positions B1 to B3, and the positions C1 to C3 of the X-ray detector are respectively an X-ray detector 23.1, an X-ray detector 23.2, and an X-ray that acquire a fluoroscopic image necessary for image reconstruction. This is the position of the detector 23.3.
- Numbers 1 to 3 of the position codes indicate the order of image capturing. First, the image is captured at the position A1, and finally, the 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 reconstruction 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 inspection processing 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 in FIGS. 49 and 50.
- the visual field (inspection object) and the X-ray detector 23 are at predetermined initial positions A1, B1, and C1.
- 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 a 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.
- the calculation unit 70 transfers the image data captured by the X-ray detector 23.1 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.
- 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.
- 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).
- 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 at the same time, 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.
- 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).
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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).
- the X-ray detector 23.1 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.
- the imaging time Tv for one field of view is expressed by the following equation.
- Te Tf Therefore, it is possible to perform imaging at a higher speed than normal imaging.
- the printed circuit board 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.
- a part can be imaged from a plurality of different directions for reconstructing an image for inspection.
- a fluoroscopic image can be captured with the inspection object placed directly above the X-ray source.
- the arrangement of the X-ray detector 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 perspective imaging and fluoroscopic imaging has a mechanism for moving the X-ray detector to the fluoroscopic imaging position by XY movement, or an X only for fluoroscopic imaging. An additional line detector is required.
- the X-ray inspection apparatus has the following configuration.
- 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.
- 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.
- 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.
- 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.
- 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 of image reconstruction, an image from an imaging position that is not on a circular orbit (on a straight line) is used for reconstruction by performing an iterative method or image reconstruction by tomosynthesis.
- 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.
- a shield 66 similar to that shown in FIG. 21 is provided.
- the shield 66 is made of a material and thickness that sufficiently shields X-rays, and is preferably lead or the like. 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.
- the X-rays incident on the shield 66 generate scattered rays, and when all the X-ray detectors 23 are simultaneously exposed and pulsed, there is a possibility that the captured image is deteriorated.
- 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.
- 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.
- FIG. 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.
- the X-ray detectors 23.1, 23.2, and 23.3 each have a mechanism that can move linearly on the rail.
- the X-ray source 10 is a scanning X-ray source as described above. 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.
- 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 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 X-ray detectors 23.1 and 23.3 at both ends move in synchronization.
- the middle X-ray detector 23.2 moves independently.
- 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.
- the X-ray detector drive mechanism can be further simplified, the mechanical mechanism can be speeded up, and the maintainability can be improved.
- FIG. 55 is a flowchart of the 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 with respect to one visual field by the imaging system described with reference to FIGS. 53 and 54.
- the inspection target position control mechanism converts the inspection portion (field of view) to be inspected into the X-ray source 10. 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.
- 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.
- it may be automatically determined based on CAD data to be inspected, or may be performed visually by an operator.
- the arithmetic 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).
- the pass / fail judgment unit 78 of the calculation unit 70 reconstructs the image of the corresponding part.
- 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.
- the arithmetic unit 70 determines that the inspection has been completed for the entire visual field (S1036), and ends the inspection (S1040).
- the arithmetic unit 70 subsequently performs CT imaging for one visual field.
- 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.
- 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).
- 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.
- the calculation 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 by the 3D image reconstruction unit 78 (S1012).
- 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).
- the processing unit 70 determines that the prescribed number of images for one field of view has not been completed (S1030). If the calculation unit 70 determines that the prescribed number of images for one field of view has not been completed (S1030), the processing unit 70 returns the process to steps S1010 and S1020.
- the calculation unit 70 ends the CT imaging process for one field of view (S1030), and the process proceeds to step S1032.
- 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.
- step S1032 the 3D image reconstruction unit 76 of the calculation unit 70 generates a reconstructed image from the captured images in a plurality of directions.
- the quality determination unit 78 of the calculation unit 70 performs quality determination based on the reconstructed image (S1034).
- 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.
- 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).
- the inspection is performed with the fluoroscopic image and the reconstructed image, but it is also possible to perform the inspection with the reconstructed image without performing the inspection with the fluoroscopic image.
- 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.
- X-ray detectors 23.1 and 23.3 perform simultaneous exposure, and during that time, X-ray detector 23.2 moves to an imaging position where an image necessary for image reconstruction can be acquired.
- 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.
- the imaging time Tv for one field of view is expressed by the following equation.
- 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.
- the X-ray inspection apparatus 130 of Embodiment 6 can exhibit at least one of the following effects or a combination thereof.
- 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.
- the moving mechanism of the X-ray detector 23 can be simplified and the movement can be speeded up.
- 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.
- 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.
- 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.
Abstract
Description
上述したように、X線CTでは、対象物を透過した後、X線検出器で検出された観測値をもとに、少なくとも対象物の断面画像を再構成する。なお、対象物または対象物の一部について3次元的なX線の吸収率の分布が得られるので、結果的には、対象物または対象物の一部の任意の断面画像、すなわちX線検出器の受光面と交わる面についての画像を再構成することが可能である。このような再構成手法としては、「解析的手法」と「反復的手法」とが知られている。以下、そのような画像再構成手法について、簡単にまとめる。
図57は、画像再構成手法を説明するための図である。X線画像再構成は、検査対象物の外部から照射したX線が、検査対象物によってどれだけ吸収(減衰)されたかを複数の角度から計測することにより、検査対象物内部のX線吸収係数の分布を求める手法である。
図57に示すように、解析的手法を用いるにあたっては、1つの検査対象物(あるいは検査対象物の1つの部分)に対して、X線検出器Daの配置とは異なる位置に配置されたX線検出器Dbに対して、焦点Fbから発せられて到達したX線強度Ibについての投影データを検出する。このような投影データを、実際には、1つの検査対象物(あるいは検査対象物の1つの部分)に対して、複数の配置について検出することで、これらの投影データから検査対象物の断面画像を再構成することになる。
図59を参照して、解析的手法での処理が開始されると(S5002)、まず、複数撮像した投影データのうちから処理対象となる投影データの選択が行なわれる(S5004)。次に、選択された投影データにフィルタをかける処理を行う(S5006)。
反復的手法では、検査対象のX線吸収係数分布f(x,y,z)と投影データln(I/Ia)とを方程式と見なし再構成する手法である。
図62を参照して、まず、反復的手法による処理が開始されると(S5102)、続いて、初期再構成画像の設定が行なわれる(S5104)。上述のとおり、初期再構成画像としては、たとえば、全てが0の値でもよい。次に、複数のX線検出器位置に対応する複数の投影データのうちから処理対象となる投影データを選択する(S5106)。
再構成画素に対応する検出器画素を求める(S5112)。
次に、全ての再構成画素について更新を行ったかが判断され(S5116)、全ての再構成画素について処理が終わっていなければ、処理はステップS5110に復帰し、終了していれば、処理は、ステップS5118に移行する。
好ましくは、複数のX線検出器の検出面はそれぞれ矩形形状である。検出器駆動部は、複数のX線検出器の検出面の一方端が、各撮像位置においてX線出力部に向かう方向と交わるように、複数のX線検出器を自転させる自転部を含む。
(1.本発明の構成)
図1は、本発明に係るX線検査装置100の概略ブロック図である。
図2を参照して、走査型X線源10においては、電子ビーム制御部62によって制御された電子銃19から、タングステンなどのターゲット11に対し電子ビーム16が照射される。そして、電子ビーム16がターゲットに衝突した場所(X線焦点位置17)からX線18が発生し、放射(出力)される。なお、電子ビーム系は、真空容器9の中に収められている。真空容器9の内部は、真空ポンプ15によって真空に保たれており、電子銃19から高圧電源14によって加速された電子ビーム16が発射される。
画像取得制御機構30は、演算部70より指定された位置にX線検出器23を移動させるようにX線検出器駆動部22を制御するための検出器駆動制御部32と、演算部70から指定されたX線検出器23の画像データを取得するための画像データ取得部34とを含む。なお、演算部70から画像データを取得するものとして同時に指定されるX線検出器は、後に説明するように撮像の状況により、1個の場合と複数とがありうる。
出力部50は、演算部70で構成されたX線画像等を表示するためのディスプレイである。
X線検査装置100においては、(X線検出器数)<<(再構成に必要な撮像枚数)である。これは、通常は、FPDに要するコストの観点から、必要な撮像枚数分の検出器を一度に設けるのが現実的ではないからである。したがって、X線検出器数をこえる撮像を行う時点で、(X線検出器)/(X線源(X線源))/(検査対象をのせたステージ)を機械的に移動させる必要があり、このような機械的な移動中は撮像処理を行うことができない。
以下では、実施の形態1に係るX線検査装置100の構成および動作を説明する前提として、他のX線検査装置として想定可能な構成において、撮像系または検査対象の機械的な移動を可能とする移動機構部分の構成の概略とその問題点について、説明しておく。
再構成画像による検査が必要ない場合には、検査は終了する(S118)。
図8は、図6で説明した1視野のCT撮像の処理を示すフローチャートである。
検出器が1枚の場合 : Tv = NTs+(N-1)Tm …(14)
なお、この時、撮像画像のデータ転送は機械的な移動と同時に行うとした。たとえば、1つの検出器を用いて16枚撮像したい場合は、Tv=16Ts+15Tmとなる。
以下、実施の形態1のX線検査装置100の構成および動作について説明する。
図11Aおよび図11B中の位置A1,B1はそれぞれX線検出器23.1および23.2の初期位置とする。位置A1~A8、位置B1~B8はそれぞれ画像再構成に必要な透視画像を取得するX線検出器23.1および23.2の位置とする。
Ts < Tm の場合: Tv = Ts +(N - 1)Tm …(16)
なお、各記号の意味は以下のとおりである。
N :撮像枚数(X線検出器の数の整数倍)
Tv:1つの視野を撮像する時間
Tm:移動機構(ステージ・X線検出器)が移動する時間
Ts:撮像(X線検出器の露光)時間
なお、撮像枚数Nについては、以後の説明のわかりやすさのためにX線検出器の数の整数倍としているが、必ずしも整数倍に限定されるわけではない。
画像の再構成に必要な透視画像の撮像枚数を16枚と仮定し、実施の形態1の撮像方式を用いたとき、再構成に必要な枚数=16枚の画像を得るためにかかる時間は、Ts>Tmの場合には16Ts、Ts<tmの場合にはTs+15Tmとなり、どちらの場合でも、図9で説明した方式を用いて1つの検出器を使用した場合の(16Ts+15Tm)と比較して撮像時間を短縮することが可能である。
図15は、実施の形態1の変形例のX線検査装置102の構成を説明する図である。X線検査装置102は、直線移動型のX線検出器とX線源10として走査型X線源とを用いている。
さらに、最後に、X線検出器23.3での撮像が終了すると、X線検出器23.3による撮像データを、3D画像再構成部78での再構成処理のために、メモリ90に転送する(S514)。
2Ts<Tmの時 : Tv=(N/3-1)(Ts+Tm)+3Ts
なお、各記号の意味は以下のとおりである。
Tv:1つの視野を撮像する時間
Tm:移動機構(ステージ・X線検出器)が移動する時間
Ts:撮像(X線検出器の露光)時間
なお、撮像枚数Nについては、以後の説明のわかりやすさのためにX線検出器の数の整数倍としているが、必ずしも整数倍に限定されるわけではない。
実施の形態1の変形例のX線検査装置102は、直線移動型のX線検出器とX線源10として走査型X線源とを用いる構成であった。
X線検査装置104では、X線検出器23が、X線検出器23.1~23.3の3個設けられていることに対応して、X線源10として3個の固定焦点型のX線源が設けられている。
図22の動作例1も、実施の形態1と同様の理由で、Feldkampの方法に代表される解析的手法を用いるのに適している。
CT再構成する視野の中心を原点とした時、視野の中心からX線焦点までの距離をLf、視野の中心からX線検出器の中心までの距離をLsとすると、以下の関係式が成り立つ。
符号が負なのは、向きが反対であることを表す。ただし、Mは拡大率を示し、拡大率は以下の式で表される。
ただし、HsはX線焦点からX線検出器までの高さ、HoはX線焦点から視野の中心までの高さを表す。この関係自体は、他の実施の形態でも同様に成り立つ。
Tv=(N/S)Ts+(N/S―1)Tt
記号の定義は以下に示す。
Tm:同一視野内で撮像位置(ステージ・X線検出器)を移動する時間
Ts:撮像(X線検出器の露光)時間
Tt:撮像データ転送時間
また、X線検出器を直線移動させることにより、X線検出器の移動時間は短縮され、視野の移動距離はX線検出器の移動と比べ大変短い(拡大率に反比例するため通常10分の1程度)ため、Tm<Ttとする。
したがって、上述した1つの検出器を使用した場合の(16Ts+15Tm)と比較して撮像時間を短縮することが可能である。
以上の説明では、実施の形態1または実施の形態2において、X線検出器駆動部22の構成により、主として、1つの視野についてのCT撮像におけるX線検出器23と検査対象の移動時間の観点から、検査時間を短縮できる効果について説明した。
解析的手法を使った撮像系を考えた場合、X線検出器の向きは、再構成のためのフィルタ処理の関係から再構成領域の中心とする円軌道の沿ったものが好ましい。
なお、検査全体のフローは、たとえば、図6で説明したものと同様である。
次に、図28は、1視野のCT撮像時間について説明する図である。図28を参照すると、1視野のCT撮像時間Tvは、N回の撮像を行い、N回のメカ移動時間の合計であるから、以下の式(19)で表される。この時、撮像画像のデータ転送はメカ移動と同時に行うとした。
(実施の形態3のX線検査装置106の構成)
以下に説明するように、実施の形態3のX線検査装置106では、まず第1に、X線検出器23を平行配置した上で、反復的手法を用いることにより、X線検出器の円軌道の制約を外し、高速化を図る。第2に、X線検査装置106では、X線検出器23を平行配置した上で、反復的手法を用いることにより、有効矩形領域を大きくし、視野分割数を少なくすることでシステムの高速化を図る。第3には、反復的手法を用いることにより、少ない撮像枚数からでも高精度な再構成画像を生成することで、システムの高速化を図るものである。
なお、図1と同一部分には、同一符号を付しており、かつ、X線焦点位置の制御、X線検出器位置の制御、検査対象位置の制御等に直接関係のある部分のうち説明に必要な部分を抜き出して記載している。
ここでも、検査全体のフローは、図12に示したものと同様であるので、図31では、図12のステップS310の1視野のCT撮像の部分を示す。
再構成領域(視野)3210の形状は、矩形のX線検出器23.Nで撮像された画像が重なる部分である。図26の撮像系では、矩形が複数の角度から重なるため円形となるが、図32では、X線検出器が全て同一方向を向いているため、重なる部分は矩形となる。
以下の説明では、撮像系において検査対象をM個の視野に分割し、CT撮像としてN枚の撮像を行うとする。記号の定義は上述のとおりである。
以上説明したとおり、実施の形態3のX線検査装置では、CT再構成に用いる撮像する際に、X線検出器の移動する範囲が同一平面内で撮像され、X線検出器の向きは同一方向とされる。そして、X線検出器および検査対象(ステージ)の移動モードをX-Yの2軸に限定することにより、移動手段の機構を簡素化し、移動速度の高速化が図られる。さらに、X線検出器と検査対象を相対的に平行移動させることで、CT再構成される視野を矩形にし、自動検査に有効な範囲を広げることにより、自動検査システムの高速化が図られる。
以上説明した実施の形態1~3では、X線検出器23または検査対象を機械的に移動させる時間による検査時間のロスを低減することが可能なX線検査装置について説明した。
以下では、実施の形態4のX線検出装置の構成および動作を説明するための前提として、複数のX線検出器と走査型X線源とを用いてCT撮像する場合の問題点について説明する。
1つのX線検出器23での撮像中は、X線焦点位置17を移動させない。4つのX線検出器23.1~23.4で順次撮像し、そのときX線焦点17はそれぞれの検出器中心と視野中心を結ぶ直線とターゲットが交わる点に位置する。
ここでも、検査全体のフローは、図12に示したものと同様であるので、図35では、図12のステップS310の1視野のCT撮像の部分を示す。
次に、1視野のCT撮像時間について説明する。
よって、図34に示す従来法で1視野を異なる角度から16枚撮像するために要する時間Tvは、Tv=16Ts+3Tmである。
以下に説明するように、実施の形態4のX線検査装置110では、以下に説明する構成を有することで、撮像に要する時間を短縮する。
1)ターゲット電流を増やす。
3)ターゲット上の一箇所への電子ビーム照射時間を短くする。
X線検出器23.1~23.4が同時に一回の透視画像撮影を行う間に、X線焦点はそれぞれのX線検出器に対応した焦点位置a~dで複数回静止する。
Semiconductor)デバイスに蓄積する機能によってX線の入射位置を記録する。
図39を参照して、1つの視野を撮像する際に、X線検出器23.1~23.4が移動する位置をそれぞれA1~A4、B1~B4、C1~C4、D1~D4とする。また、X線検出器位置に対応したX線焦点位置をa1,a2,b1,b2,c1,c2,d1,d2等で表している。
3)2つ以上のX線検出器23(この例では4個)を使用する。
5)X線検出器は、撮像時には静止している。
7)X線源に対しては、位置を固定した遮蔽体66を設置している。
なお、各記号の意味は以下のとおりである。
S :X線検出器の数
Tv:1つの視野を撮像する時間
Tm:メカ(ステージ・X線検出器)が移動する時間
Tss:S個のX線検出器の同時露光のための撮像(X線検出器の露光)時間
なお、撮像枚数Nについては、以後の説明のわかりやすさのためにX線検出器の数の整数倍としているが、必ずしも整数倍に限定されるわけではない。
図43Aは、透過型ターゲット使用のX線源の内部構成例であり、図43Bは反射型ターゲットの例を示している。以下に説明するように、走査型X線源がこのような構造であることにより、実施の形態4のような動作が可能となる。
以上の説明では、検査対象の視野を変更する場合は、検査対象を検査対象位置制御機構により移動させるものとして説明してきた。
図45では、4つの視野をX線検出器23や検査対象の機械的な移動なしで再構成する例を示している。図45は、図44の構成を上から見たものであり、8枚の透視画像を等角度から撮像することを想定した動作例を示したものである。
Tv=(N/S-1)Tm+STs
各処理の時間を下記のように定義する。
Ts:撮像(X線検出器の露光)時間
S個(例えば2個)のX線検出器23による1視野のCT撮像時間Tvは、N回の撮像時間と、N/S回のメカ移動時間の合計である。ただし、各処理のかかる時間により、Tvは変化する。以下では、一般的な撮像時間を考慮して、Tm>Ts>>Tf(X線焦点の移動時間)(X線焦点は他処理と比較して十分高速であるため無視できる)として計算を行う。
まず、X線検出器23.1で撮像するため、Tsの時間がかかる。次に、X線焦点を移動するため、Tfの時間がかかるが、同時にX線検出器23.1を次の撮像位置A2に移動する。X線検出器23.2は既に所定位置に配置されているため、移動時間は発生せずに撮像できるため、Tsの時間がかかる。X線検出器23.2で撮像後、X線検出器23.2を移動させる。次に、X線検出器23.1にて撮像を行うが、移動がまだ終了してない。移動が終了するのが、撮像開始からTs+Tm後となり、位置A2にてX線検出器23.1の撮像を行う。次に、X線検出器23.2の撮像を行うが移動が終了していないため、撮像の開始時間は、Ts+Tm後である。X線検出器23.2で最初に撮像を開始したのが、Ts後であるから、1周期の撮像時間はTmとなる。よって、1周期の撮像時間Tmが(N/2-1)回あり、X線検出器23.1の最初の撮像(A1)時間TsとX線焦点移動時間TfとX線検出器23.2の最後の撮像を加算すると、1視野のCT撮像時間が求まり、式(24)で表される。
また、次の視野への移動時間は、X線検出器23.1が次の視野の撮像位置に移動する時間から、X線検出器23.2の撮像時間Tsを引いた時間となるため、式(25)で表される。
図48は、図44および図45で説明した撮像系の検査全体についての検査タイミングチャートである。
ただし、記号に意味は以下の通りである。
Tv:1つの視野を撮像する時間
Te:視野の移動時間
X線検査装置120では、視野の移動時間Teは、ほぼ、移動時間Tmと撮像時間Tsとの差となるため、移動時間が大幅に短縮される。
図49は、実施の形態5の変形例のX線検査装置122の構成を説明する図である。X線検査装置122は、直線移動型のX線検出器とX線源10として走査型X線源とを用いている。
S個(例えば3個)のX線検出器による1視野のCT撮像時間Tvは、N回の撮像時間と、N/S回のメカ移動時間の合計である。ただし、各処理のかかる時間により、Tvは変化する。以下では、一般的な撮像時間を考慮して、2Ts>Tm>>Tf(X線焦点の移動は他処理と比較して十分高速である)として計算を行う。
まずX線検出器23.1で撮像するため、Tsの時間がかかる。次に、X線焦点を移動するため、Tfの時間がかかるが、同時にX線検出器23.1を次の撮像位置A2に移動する。X線検出器23.2は既に所定位置に配置されているため、移動時間は発生せずに撮像できるため、Tsの時間がかかる。X線検出器23.2で撮像後、X線検出器23.2を移動させる。次に、X線検出器23.3で撮像する。X線検出器23.3は既に所定位置に配置されているため、移動時間は発生せずに撮像できるため、Tsの時間がかかる。
また、次の視野への移動時間は、X線焦点の移動時間のみであるから、以下の式のようになる。
よって、通常の撮像よりも高速な撮像が可能となる。
部品が半田付けされたプリント基板をX線で検査する際、プリント基板にはBGAのような再構成画像による検査が必要な部品と、透視画像のみの検査で事足りる部品が混在しているため、次の二種類の方法で撮像が可能なX線検査装置が望ましい。
2)検査物をX線源の真上に置いての透視画像撮像できる。
図53は、実施の形態6のX線検査装置130の構成を説明する図である。X線検査装置130は、直線移動型のX線検出器とX線源10として走査型X線源とを用いている。1つの視野について撮像中の検査対象の移動は必要ない。
Ts>Tmの場合: Tv=2/3NTs
Ts<Tmの場合: Tv=(N/3-1)(Ts+Tm)+2Ts
例として、18枚の撮像に要する時間は、Ts>Tmの場合は12Ts、Ts<Tmの場合は7Ts+5Tmであり、撮像時間を大幅に高速化することができる。
Claims (16)
- 対象物の検査対象領域を透過したX線を複数の検出面で撮像することにより、前記検査対象領域の像の再構成処理を実行するためのX線検査装置であって、
前記複数の検出面で撮像するための、検出面の数よりも少ない複数のX線検出器と、
前記複数のX線検出器のうちの一部と他の一部とを独立に移動させる検出器駆動部と、
前記検査対象領域を透過したX線が、それぞれ前記検出面となる複数の撮像位置に移動した前記複数のX線検出器に入射するように対応させてX線を出力するX線出力部と、
前記X線検査装置の動作の制御を行う制御部とを備え、
前記制御部は、
各前記X線検出器の露光タイミングと、前記検出器駆動部とを制御する画像取得制御部と、
前記X線出力部を制御するためのX線出力制御部と、
複数の前記検出面で撮像した、前記検査対象領域を透過したX線の強度分布のデータに基づき、前記検査対象領域の像データを再構成する画像再構成処理部とを含み、
前記画像取得制御部および前記X線出力制御部は、
前記複数のX線検出器のうちの前記一部を前記複数の撮像位置のうちの第1の位置で撮像させる処理と、前記複数のX線検出器のうちの前記他の一部を前記複数の撮像位置のうちの前記第1の位置とは異なる第2の位置に移動させる処理とを並行して実行する、X線検査装置。 - 前記画像取得制御部および前記X線出力制御部は、
1つの前記対象物の検査対象領域について、前記画像データの再構成に対して予め設定された個数の前記撮像位置での撮像を複数回に分けて行うために、
前記複数のX線検出器のうちの前記一部について、
前記第1の位置で撮像させる処理、および、当該撮像後に前記第1の位置とは異なる次の第1の位置へ移動させる処理と、
前記複数のX線検出器のうちの前記他の一部について、
前記一部を前記第1の位置で撮像させる処理と並行して、前記第1の位置、次の第1の位置および先の前記第2の位置のいずれとも異なる、次回の撮像に対応する前記第2の位置へ移動させる処理、および、前記一部を前記次の第1の位置へ移動させる処理と並行して、前記第2の位置で撮像させる処理と、
を実行させる、請求の範囲第1項に記載のX線検査装置。 - 前記X線出力制御部は、前記複数の検出面について、前記X線が前記検査対象領域を透過して各前記検出面に対して入射するように前記X線の放射の起点位置の各々を設定する起点設定部を含み、
前記X線出力部は、各前記起点位置にX線源のX線焦点位置を移動させて、前記X線を発生させる、請求の範囲第1項に記載のX線検査装置。 - 前記X線出力部は、X線源の連続面であるターゲット面上に照射する電子ビームを偏向させることで前記X線源焦点位置を移動させる、請求の範囲第3項に記載のX線検査装置。
- 対象物の検査対象領域を透過したX線を複数の検出面で撮像することにより、前記検査対象領域の像の再構成処理を実行するためのX線検査装置であって、
前記複数の検出面で撮像するための、検出面の数よりも少ない複数のX線検出器と、
前記複数のX線検出器の一部を所定の1軸方向に沿って移動させる1軸駆動部と、
前記検査対象領域を透過したX線が、それぞれ前記検出面となる複数の撮像位置に移動した前記複数のX線検出器に入射するように対応させてX線を出力するX線出力部と、
前記X線検査装置の動作の制御を行う制御部とを備え、
前記制御部は、
各前記X線検出器の露光タイミングと、前記検出器駆動部とを制御する画像取得制御部と、
前記X線出力部を制御するためのX線出力制御部と、
複数の前記検出面で撮像した、前記検査対象領域を透過したX線の強度分布のデータに基づき、前記検査対象領域の像データを再構成する画像再構成処理部とを含む、X線検査装置。 - 前記1軸駆動部は、前記複数のX線検出器を所定の平面内で平行に移動させる、請求の範囲第5項に記載のX線検査装置。
- 前記複数のX線検出器の前記検出面はそれぞれ矩形形状であり、
前記検出器駆動部は、前記複数のX線検出器の前記検出面の一方端が、各前記撮像位置において前記X線出力部に向かう方向と交わるように、前記複数のX線検出器を自転させる自転部を含む、請求の範囲第5項または第6項に記載のX線検査装置。 - 画像再構成処理部は、反復的手法により前記検査対象領域の画像データを再構成する、請求の範囲第5項に記載のX線検査装置。
- 画像再構成処理部は、解析的手法により前記検査対象領域の画像データを再構成する、請求の範囲第8項に記載のX線検査装置。
- 対象物の検査対象領域を透過したX線を複数の検出面で撮像することにより、前記検査対象領域の像の再構成処理を実行するためのX線検査装置であって、
前記複数の検出面で撮像するための、検出面の数よりも少ない複数のX線検出器と、
前記検査対象領域を透過したX線が、それぞれ前記検出面となる複数の撮像位置に移動した前記複数のX線検出器に入射するように対応させてX線を出力するX線出力部と、
前記X線検査装置の動作の制御を行う制御部とを備え、
前記制御部は、
各前記X線検出器の露光タイミングと、前記検出器駆動部とを制御する画像取得制御部と、
前記X線出力部を制御するためのX線出力制御部と、
複数の前記検出面で撮像した、前記検査対象領域を透過したX線の強度分布のデータに基づき、前記検査対象領域の像データを再構成する画像再構成処理部とを含み、
前記画像取得制御部および前記X線出力制御部は、
前記複数のX線検出器のうちの前記一部を前記複数の撮像位置のうちの第1の位置で撮像させる処理と、前記複数のX線検出器のうちの前記他の一部を前記複数の撮像位置のうちの前記第1の位置とは異なる第2の位置に移動させる処理とを並行して実行し、
前記X線出力部は、前記撮像位置に配置されている複数のX線検出器のうち同時に撮像状態となっている複数のX線検出器に対して、それぞれ対応する複数のX線焦点位置からX線を発生させ、
前記X線出力部からのX線が、前記同時に撮像状態となっているX線検出器のそれぞれに対して、対応するX線焦点位置から前記検査対象領域を透過して各前記検出面に対して入射するX線は透過する一方、対応しないX線焦点位置からのX線は遮蔽する遮蔽部材をさらに備える、X線検査装置。 - 前記X線出力部は、X線源の連続面であるターゲット面上に照射する電子ビームを偏向させることで前記X線源焦点位置を移動させ、
前記X線出力制御部は、前記同時に露光状態となっているX線検出器のそれぞれに対して、前記X線が時分割で入射するように、前記X線出力部を制御する、請求の範囲第10項に記載のX線検査装置。 - 対象物の検査対象領域を透過したX線を複数の検出面で撮像することにより、前記検査対象領域の像の再構成処理を実行するためのX線検査装置であって、
前記複数の検出面で撮像するための、検出面の数よりも少ない複数のX線検出器と、
前記複数のX線検出器を所定の平面内で平行に移動させる平行駆動部と、
前記検査対象領域を透過したX線が、それぞれ前記検出面となる複数の撮像位置に移動した前記複数のX線検出器に入射するように対応させてX線を出力するX線出力部と、
前記X線検査装置の動作の制御を行う制御部とを備え、
前記制御部は、
各前記X線検出器の露光タイミングと、前記検出器駆動部とを制御する画像取得制御部と、
前記X線出力部を制御するためのX線出力制御部と、
複数の前記検出面で撮像した、前記検査対象領域を透過したX線の強度分布のデータに基づき、前記検査対象領域の像データを再構成する画像再構成処理部とを含む、X線検査装置。 - 前記検出器駆動部は、前記複数のX線検出器を所定の2軸方向に沿ってそれぞれ独立移動させる2軸駆動部を含む、請求項1記載のX線検査装置。
- 対象物の検査対象領域を透過したX線を複数の検出面にそれぞれ対応するX線検出器で撮像することにより、前記検査対象領域の像の再構成処理を実行するためのX線検査方法であって、
各前記X線検出器を対応する前記検出面となる撮像位置に独立に移動させるステップと、
前記検査対象領域を透過したX線が、それぞれ複数の前記撮像位置に移動した複数の前記X線検出器に入射するようにX線を出力するステップと、
前記複数のX線検出器のうちの一部を前記複数の撮像位置のうちの第1の位置で撮像させる処理と、前記一部とは異なる他の一部を前記複数の撮像位置のうちの前記第1の位置とは異なる第2の位置に移動させる処理とを並行して実行するステップと、
複数の前記検出面で撮像した、前記検査対象領域を透過したX線の強度分布のデータに基づき、前記検査対象領域の像データを再構成するステップとを備える、X線検査方法。 - 前記並行して実行するステップは、1つの前記対象物の検査対象領域について、前記画像データの再構成に対して予め設定された個数の前記撮像位置での撮像を複数回に分けて行うために、
前記複数のX線検出器のうちの前記一部について、前記第1の位置で撮像させる処理および当該撮影後に前記第1の位置とは異なる次の第1の位置へ移動させる処理と、
前記複数のX線検出器のうちの前記他の一部について、前記一部を前記第1の位置で撮像させる処理と並行して、前記第1の位置、次の第1の位置および先の前記第2の位置のいずれとも異なる、前記第2の位置へ移動させる処理、および、前記一部を前記次の第1の位置へ移動させる処理と並行して、前記第2の位置で撮像させる処理と、
を実行させるステップを含む、請求の範囲第14項に記載のX線検査方法。 - 前記X線を出力するステップは、X線源の連続面であるターゲット面上に照射する電子ビームを偏向させることで前記X線源焦点位置を移動させるステップを含む、請求の範囲第14項に記載のX線検査方法。
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