TWI480022B - Radiation photographing apparatus - Google Patents

Description

Radiographic apparatus

The present invention relates to a radiographic apparatus that performs a radiography by acquiring a tomographic image based on a plurality of projection images.

The radiographic apparatus will be described using an X-ray inspection apparatus as an example. As shown in FIG. 7 , such an X-ray inspection apparatus includes a stage S on which an object O is placed, an X-ray tube T (radiation irradiation unit), and an X-ray detector D (radiation detection unit). The X-ray tube T (radiation irradiation unit) and the X-ray detector D (radiation detection unit) are disposed to face each other across the stage S. The platform S is a rotating platform including a rotating mechanism that rotationally drives the rotating platform about the axis of the rotating shaft Ax.

Further, as an object of the X-ray inspection, there are a through hole/pattern/solder joint portion of the mounting substrate and the multilayer substrate, and an integrated circuit disposed on a pallet (IC: An electronic component such as an integrated circuit, a cast of a metal or the like, and a molded article such as a video cartridge recorder.

In particular, when X-ray inspection is performed on an object having a very fine structure such as a ball grid array (BGA) or wiring by tomography, it is necessary to increase the magnification and perform imaging. However, in order to increase the amplification factor, it is necessary to connect the radiation source represented by the X-ray tube to the object. Photographing has recently been carried out, and therefore, when the object is in a large planar shape, the X-ray tube and the object may interfere with each other. As a result, in order to avoid interference, it is almost impossible to increase the magnification.

Therefore, as shown in FIG. 8, the rotating platform S is disposed, and the X-ray tubes T and X are arranged in an axial direction inclined at a fixed angle (lamino angle) with respect to the rotational axis Ax that rotationally drives the rotating platform S. The radiation detector D (for example, refer to Patent Document 1). In the case of Fig. 8, the X-ray tube T is fixedly arranged to rotationally drive the rotary table S around the axis of the rotation axis Ax. When the data is acquired, the X-ray detector D tilts the oblique direction of the tomographic angle, detects the X-rays that are irradiated by the X-ray tube T and transmits the object O, and acquires the projection to the X-ray based on the X-rays. A projected image of the detection surface of the detector D. Each time the rotary table S is rotationally driven, a projection image is acquired, thereby obtaining a projection image of a plurality of angles.

In this manner, the X-ray tube and the X-ray detector are disposed in an oblique direction in which the tomographic angle is inclined, and the image is taken from the oblique direction. This has the advantage that the X-ray tube can be brought close to the rotating platform, and thus the X-ray tube can be made closer to the rotating platform. The X-ray tube is close to the object, and a projection image of high magnification can be obtained without interfering with the X-ray tube and the object. However, since there is a restriction on the degree of freedom of the drive system, it is difficult to obtain a projection image of an object from an arbitrary position, and the use is limited to Computed Tomography (CT).

Therefore, for example, as shown in FIG. 9, a method of performing photographing from a tilt direction using a device in which the platform S of the above apparatus does not include a special rotating mechanism is known (for example, refer to Patent Document 2, Patent Literature). Offer 3). In FIG. 9, the platform S is horizontally moved (straight forward movement) together with the object O in such a manner that a circular orbit is drawn in a plane perpendicular to the rotation axis Ax (horizontal plane in FIG. 9), and the platform S is Simultaneously, the X-ray detector D is rotationally driven around the axis of the same rotation axis Ax, thereby acquiring a plurality of projection images, and acquiring a tomographic image based on the plurality of projection images.

In this way, the geometric relationship between the relative characteristics of the X-ray tube, the object, and the X-ray detector at the time of photographing in FIG. 9 and the case of FIG. 8 (the case where the object and the rotating platform are rotationally driven around the axis of the rotation axis Ax) In the same manner, the above-described respective members are driven in synchronization, whereby photographing is performed from the oblique direction. Further, in the case of Fig. 9, the orientation of the stage S can be kept fixed unlike in Fig. 8. Further, the device configuration for realizing photographing from the oblique direction includes a plurality of device configurations in addition to FIG. 9, and for example, a method of driving the X-ray tube and the X-ray detector to fix the platform (and the object) Etc. (for example, refer to Patent Document 4).

Prior technical literature

Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2005-106515

Patent Document 2: Japanese Patent Laid-Open Publication No. 2010-2221

Patent Document 3: Japanese Patent Laid-Open Publication No. 2006-162335

Patent Document 4: Japanese Patent No. 4409043

However, as shown in FIG. 9, when CT photography is performed from the oblique direction, The CT-dedicated device has only one degree of freedom in the rotation of the platform. In comparison with this, the degree of freedom of the drive system is large, and the drive accuracy of each drive system becomes important. In particular, since the platform and the X-ray detector are independent drive mechanisms, there is a problem in that in order to obtain a desired scan track of tomography, high-precision positioning, synchronizable mechanism and control are required, and expensive.

Specifically, the more the X-ray tube is photographed at a high magnification close to the platform, the greater the influence of the driving accuracy of the platform on the projected image. Therefore, when CT imaging is performed from the oblique direction at a high magnification, the platform must operate in such a manner that the circular orbit is drawn with high precision. In order to achieve high-precision driving of such a platform, the machine must have high rigidity, and must be capable of performing minute position control (positioning), and there is a problem that the cost rises.

Further, in order to operate the platform so as to draw a circular orbit, as shown in FIG. 10, the drive systems of the two orthogonal axes (the X-axis and the Y-axis of the orthogonal coordinate system) have a phase deviation of 90°. The sine wave (sin wave) method can be used to control each position. P _{X in} Fig. 10 is the X coordinate value, and P _Y is the Y coordinate value. However, in the case of performing sampling at equal intervals at a certain rotation angle, the position at which the gain of the sin wave becomes large for the driving amount (the angle θ of the Y coordinate in FIG. 10) When the angle of the X coordinate is around 90° and around 270° in the vicinity of 0°, 180°, and 360°, the driving amount of each axis must be small, and the driving direction must be reversed. As described above, since the micro drive is performed at the position where the drive direction is reversed, there is a problem in that the influence of static friction or backlash becomes large, and it is difficult to ensure the drive accuracy.

The above problem is not limited to the case where the platform and the X-ray detector are driven to perform CT imaging from the oblique direction. For example, even when the X-ray tube is driven by the X-ray detector and the CT image is taken from the oblique direction, the same problem arises, that is, in order to realize the tilt CT function at a high magnification, the X-ray tube must have high precision. To depict the circular orbit.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radiographic apparatus which is low in cost and can maintain driving accuracy.

In order to achieve the object as described above, the present invention adopts the constitution as described below.

In other words, the radiographic apparatus of the present invention includes a platform on which the object is placed, the radiation irradiation unit and the radiation detecting unit are disposed to face each other across the platform, and the arithmetic unit is based on the plurality of projection images. The plurality of projection images are obtained by detecting, by the radiation detecting unit, the radiation irradiated by the radiation irradiation unit and transmitted through the object, and the radiation imaging device includes a synthesis driving unit. a combination comprising two or more rectilinear driving mechanisms, the synthesizing track of each of the rectilinear driving mechanisms is a track according to a circular orbit, and driving at least one of the radiation irradiation unit and the platform; and a control unit for synthesizing the driving The unit performs control, and the control unit makes the absolute value of the movement amount of each unit step or more having a value of a positive real number or more or "0", for each straight-forward drive The mechanism performs control, and each of the rectilinear driving mechanisms is controlled to set the orbit of the range from the small circular orbit to the large circular orbit as the track according to the circular orbit, and the radiation irradiation unit and at least one of the platforms are The small circular orbit is a concentric circle of the circular orbit and has a size of half, and the large circular orbit is a concentric circle of the circular orbit and has a size twice.

Here, the tomographic image in the present invention refers to a three-dimensional tomographic image including a plurality of tomographic images, and of course, a tomographic image is also included.

When a circular orbit is realized by two or more rectilinear drive mechanisms, the micro drive is inevitably performed at a position where the drive direction of the linear drive mechanism is reversed. Therefore, the influence of static friction or kickback becomes large and the drive accuracy cannot be maintained. . Therefore, according to the radiographic apparatus of the present invention, the control unit controls the respective rectilinear driving mechanisms so that the absolute value of the movement amount per unit step is equal to or greater than a predetermined value having a value of a positive real number or "0". By the above control, at the position where the driving direction of the linear drive mechanism is reversed, the minute drive is not performed, the amount of movement is equal to or higher than the predetermined value, or the amount of movement is "0" (that is, the stopped state). Further, in order to exclude the restriction of the circular orbit, the control unit controls each of the direct drive mechanisms to be small since the micro drive is not performed at the position where the drive direction of the linear drive mechanism is reversed. The track in the range from the circular orbit to the large circular orbit is set as the above-described orbit according to the circular orbit, and at least one of the radiation irradiation unit and the platform is driven, and the small circular orbit is concentric with the circular orbit and has a size of half. The above large circular orbit is the above circular orbit Concentric circles and have a size of 2 times. Thereby, the driving accuracy can be maintained without performing minute driving at a position where the driving direction of the linear drive mechanism is reversed. In addition, it is assumed that the movement is a track having a movement amount of “0” (that is, a stop state), and the operation is performed by using only the other rectilinear drive mechanisms, and the following effects are obtained. That is, it is easy to control the position by using each of the straight drive mechanisms (drive systems), and it is also easy to maintain the drive accuracy. Further, since the driving accuracy is improved, the rigidity required for the mechanical condition is alleviated, so that the cost is also lowered, and each of the linear drive mechanisms (drive systems) can achieve low cost.

An example of the above-described invention is to control each of the rectilinear driving mechanisms while maintaining the amount of movement per unit step (a value having a positive real number) to be equal to or higher than the predetermined value, and the amount of movement of each unit step is made positive In the coordinate system, the combined track of the two straight drive mechanisms that are directly driven in advance is the above-described circular track, and the movement amount per unit step of the region in which the driving directions of the respective linear drive mechanisms are reversed is "0". On the straight track, each of the straight drive mechanisms is controlled separately. In other words, the amount of movement per unit step of the region in which the driving direction of each of the rectilinear driving mechanisms is reversed is “0”, and the straight track is set, and in the other regions, the same track as the circular track is used. Thereby, the influence of the artifact generated when the circular orbit is deviated can be reduced as much as possible, and the driving accuracy of the problem region (the region in which the driving direction of the linear drive mechanism is reversed) can be improved.

Another example of the above invention is a track in which the orbit of the circular orbit is a range from the small circular orbit to the large circular orbit, and is a quadrangle The track, the control unit controls only one straight drive mechanism, and the amount of movement per unit step is "0", and controls the remaining straight drive mechanisms, thereby driving on the straight track of the above quadrilateral track. When the amount of movement is "0" (that is, the stop state), the remaining linear drive mechanism is used to operate and the drive is driven straight, thereby realizing the above-described quadrilateral track, whereby the position is easily controlled and the drive accuracy is improved. Moreover, since it is a straight-forward trajectory, it is possible to drive in a shorter time than the circular orbit, and it is possible to shorten the data collection time related to photography.

In the above invention, it is preferable to include a detection drive unit that drives the radiation detecting unit in synchronization with driving of at least one of the radiation irradiation unit and the stage by the combined drive unit. The radiation detecting unit is also operated, whereby the photographic field of view can be ensured, and the tomographic image of a larger area can be calculated.

In the case of including the detection drive unit, it is preferable that the detection drive unit drives the radiation detection unit in such a manner that the radiation irradiated by the radiation irradiation unit passes through the attention point of the object and is detected by radiation. The central portion of the unit is used to detect the above radiation. The gaze point is captured by the central portion of the radiation detecting unit, whereby when the tomographic image is calculated, a tomographic image of a sufficiently large range can be obtained, and the tomographic image can be at substantially the same position (gazing point) It is again configured (back projection) and is based on the center of the photographic field of view.

According to the radiographic apparatus of the present invention, the system of the circular orbit is excluded According to the following constraints, that is, in the position where the driving direction of the linear drive mechanism is reversed, the control unit separately controls each of the linear drive mechanisms to rotate the small circular track to the large circular track. The track of the range is set as the track according to the circular orbit, and at least one of the radiation irradiation unit and the platform is driven. The small circular orbit is a concentric circle of the circular orbit and has a size of half, and the large circular orbit is the circular orbit. Concentric circles and have a size of 2 times. As a result, the cost is low and the driving accuracy can be maintained.

Example

Hereinafter, embodiments of the invention will be described with reference to the drawings. 1 is a schematic configuration diagram of an X-ray inspection apparatus according to an embodiment, and FIG. 2 is a block diagram of an X-ray inspection apparatus according to an embodiment. In the present embodiment, a radiographic apparatus will be described using an X-ray inspection apparatus as an example.

As shown in Fig. 1, the X-ray inspection apparatus 1 includes a stage 2 on which an object O is placed, an X-ray tube 3 and an X-ray detector 4, and the X-ray tube 3 and the X-ray detector 4 are interposed. The above-described platforms 2 are arranged in such a manner as to face each other. The X-ray detector 4 is not particularly limited as exemplified by an image intensifier (I.I) or a flat panel type X-ray detector (FPD: Flat Panel Detector). In the present embodiment, the X-ray detector 4 will be described using a flat panel X-ray detector (FPD) as an example. The stage 2 corresponds to the stage in the present invention, the X-ray tube 3 corresponds to the radiation irradiation unit in the present invention, and the X-ray detector 4 corresponds to the radiation detecting unit in the present invention.

The FPD includes a plurality of detecting elements, and the plurality of detecting elements are arranged vertically and horizontally corresponding to the pixels, the detecting elements detect X-rays, and output the detected X-ray data (charge signals) as X-ray detecting signals. In this way, the X-ray detector 4 including the FPD detects the X-rays that are irradiated by the X-ray tube 3 and transmitted through the object O, and outputs the X-ray detection signals, and corresponding to the pixels, the X-ray detection signals are used. The pixel values are arranged separately, whereby a projection image projected onto the detection surface of the X-ray detector 4 is obtained.

Further, as shown in FIG. 1, the X-ray inspection apparatus 1 comprises: a detector rotation mechanism 5, the X-ray detector 4 is rotationally driven around _an arrow R < a detector and a tilting mechanism 6, the X-ray detector 4 in the direction of the arrow The R ₂ direction moves obliquely. The detector tilting movement mechanism 6 includes an arc-shaped guide portion 6a that supports the X-ray detector 4, and a rotation motor 6b (see FIG. 2), and the rotation motor 6b is rotationally driven, whereby the X-ray detector 4 is inclined to move in the direction of the arrow R ₂ along the guide portion 6a. The detector rotating mechanism 5 corresponds to the detecting drive unit in the present invention.

Detector rotation mechanism 5 comprises a rotary motor 5a (refer to FIG. 2), a motor rotation detector 5a that the inclined guide portion moving means 6 in _rotation about a drive 6a arrow R, whereby the guide support portion 6a of the X-ray detector 4 It is also rotationally driven around the arrow R ₁ . Further, in the present embodiment, the detector rotation mechanism 5 is driven in synchronism with the platform 2, the X-ray detector 4 is rotationally driven around the arrow R _1. In particular, the detector rotating mechanism 5 rotationally drives the X-ray detector 4 around the arrow R ₁ in such a manner that the X-rays irradiated by the X-ray tube 3 pass through the gaze point of the object O, and are detected by radiation. The central portion of the device 4 detects the above X-rays.

Further, as shown in FIG. 2, the X-ray inspection apparatus 1 includes a platform drive mechanism 7, which drives the platform 2 in a straight line by orthogonal coordinate systems X, Y, and Z (refer to FIG. 1); the tomographic image calculation unit 8, Computation and calculation of the tomographic image based on the plurality of projection images; controller 9 for collective control of the above components; and image output unit 10, tomographic map obtained by the tomographic image calculation unit 8 Like output (display output to monitor or print output to printer). The platform driving mechanism 7 comprises: an X-axis straight-feeding motor 7a, which drives the platform 2 in the X direction (here, horizontal driving); the Y-axis straight-feeding motor 7b causes the platform 2 to drive straight in the Y direction (here, horizontal driving) And the Z-axis straight-moving motor 7c causes the platform 2 to drive straight in the Z direction (here, the lift drive). In the present embodiment, the combined track of each of the X-axis straight-moving motor 7a and the Y-axis straight-moving motor 7b is based on the track of the circular track on which the platform 2 is driven. The track based on the circular orbit will be described in detail later. The stage drive mechanism 7 corresponds to the combined drive unit in the present invention, and the X-axis straight feed motor 7a, the Y-axis straight feed motor 7b, and the Z-axis straight feed motor 7c correspond to the linear drive mechanism in the present invention, and the tomographic image calculation unit 8 corresponds to the present invention. In the arithmetic unit of the invention, the controller 9 corresponds to the control unit in the present invention.

The tomographic image calculation unit 8 calculates and calculates a tomographic image based on a plurality of projection images. The controller 9 performs overall control of the respective components constituting the X-ray inspection apparatus 1, in particular, the rotation motor 5a of the detector rotation mechanism 5, the rotation motor 6b of the detector tilt movement mechanism 6, and the platform drive. The X-axis straight feed motor 7a, the Y-axis straight-feed motor 7b, and the Z-axis straight-feed motor 7c of the moving mechanism 7 are controlled. In Fig. 1, the X-ray tube 3 is in a fixed position, but can also be controlled by the controller 9 to enable the X-ray tube 3 to be tilted in accordance with the tilting movement of the X-ray detector 4. The specific control of the controller 9 will be described later in detail. The tomographic image calculation unit 8 or the controller 9 includes a central processing unit (Central Processing Unit (CPU)) or the like.

The X-ray tube 3, the object O, and the X-ray detector 4 are arranged as shown in Fig. 1, whereby the X-ray tube 3 and the X-ray detector can be arranged in an oblique direction in which the tomographic angle is inclined, similarly to Fig. 9 4, thereby taking pictures from the oblique direction. Further, the X-ray tube 3 can be brought close to the stage 2, and the X-ray tube 3 can be brought close to the object O, and a projection image of high magnification can be obtained without interfering with the X-ray tube 3 and the object O. When the stage 2 is driven on the orbit according to the circular orbit, a projection image is obtained, thereby obtaining projection images of a plurality of angles, and the tomographic image calculation unit 8 shown in FIG. 2 is based on a plurality of projection images. For example, the tomographic image is calculated and operated.

Here, the range of the track according to the circular orbit will be described with reference to FIGS. 3(a) and 3(b). Fig. 3(a) is a diagram showing a small circular orbit, a large circular orbit, an inscribed triangle which is inscribed with the circular orbit and circumscribing the small circular orbit, and an inscribed with the large circular orbit and the circle. A schematic diagram of an equilateral triangle circumscribing the track, the small circular orbit is a concentric circle of a circular orbit and has a size of half. The large circular orbit is a concentric circle of a circular orbit and has a size of 2 times. FIG. 3(b) is in addition to the illustration. In addition to circular orbits, Also shown are a regular hexagon which is inscribed with a large circular orbit, an equilateral triangle, a diagonal which connects the diagonal of the regular hexagon, and which does not pass through the circular orbit, the center of the large circular orbit, and a rectangular triangle, the above-mentioned equilateral triangle It is obtained by dividing a diagonal of a regular hexagon and passing a circle of a circular orbit and a center of a large circular orbit, and dividing the regular hexagon by the side of the center of the large orbit that does not pass the circular orbit. The sides of the triangle are formed by the sides of the center of the large circular orbit.

The track according to the circular orbit is not unlimited. In the present specification, if the following circular orbit is defined as a "small circular orbit", the circular orbit is a concentric circle as a standard circular orbit and has a half size, and will be as follows The circular orbit is defined as a "major circular orbit" which is a concentric circle of a standard circular orbit and has a size twice as large. The orbit from the small circular orbit to the large circular orbit is set as a orbit according to the circular orbit. Therefore, the following track becomes a track based on a circular orbit, and the above-described track is not drawn on the inner side of the small round track, and is not depicted on the outer side of the large round track. Here, for the following reason, the small circular orbit is a circular orbit which is a concentric circle of a (standard) circular orbit and has a size of half, and the large circular orbit is set as a circular orbit as follows. The circular orbit is a concentric circle of (as a standard) circular orbit and has a size of 2 times.

If a regular polygon inscribed with a (as standard) circular orbit is considered, the smallest circle inscribed with the regular polygon is that the regular polygon is an equilateral triangle and the circle is inscribed with the equilateral triangle. Conversely, if a regular polygon circumscribing a circular orbit (as a standard) is considered, the largest case of a circle circumscribing the regular polygon is that the regular polygon is an equilateral triangle and the circle is circumscribed with the equilateral triangle. As shown in Fig. 3(a), a circular track as a standard is set to C, an equilateral triangle inscribed with a circular track C (as a standard) is set to TR ₁ , and a circle inscribed with the equilateral triangle TR ₁ is set. The track is set to C _S , the equilateral triangle circumscribing the (as standard) circular orbit C is set to TR ₂ , and the circular orbit circumscribing the equilateral triangle TR ₂ is set to C _B .

Only the relationship between the diameter of the circular track C (as a standard) and the diameter of the circular orbit C _B circumscribing the regular triangle TR ₂ is focused. As shown in FIG. 3(b), if the regular hexagon inscribed in the circular orbit C _B is HEX, the equilateral triangle is set to TR ₃ , and the equilateral triangle is connected by diagonally connecting the regular hexagon HEX and When the regular hexagon HEX is divided by the sides of the circular orbits C and C _B , the regular hexagon HEX is divided into six regular triangles TR ₃ . On the other hand, as shown in Fig. 3(b), the following side is set to AB, which connects the diagonals of the regular hexagon HEX and does not pass through the center of the circular orbits C and C _B , and the following right triangle is used. Let TR _{4 be} the right triangle formed by the side AB, the side of the equilateral triangle TR ₃ , and the side passing through the center of the circular orbit C _B (see the thick frame of FIG. 3( b )).

The right triangle TR ₄ is a triangle which is equally divided into the following lines, which is a line in which a vertical line (a part of the side AB) is dropped from the vertex of the regular triangle TR ₃ , and the length of the hypotenuse of the right triangle TR ₄ It is the radius of the circular orbit C _B , and the length of the side orthogonal to the perpendicular is the radius of the circular track C (as a standard). The length of the hypotenuse of the right triangle TR ₄ : the length of the side orthogonal to the perpendicular is 2:1. Therefore, as shown in FIG. 3(b), if the radius of the circular rail C (as a standard) is r, the length of the side orthogonal to the perpendicular is equal to the radius r of the circular orbit C, and the inclination of the right triangle TR ₄ The length of the side is 2r, and as a result, the radius of the circular track C _B is equal to the length 2r of the oblique side of the right triangle TR ₄ .

That is, the radius of the circular orbit C _B circumscribing the equilateral triangle TR _{2 of} FIG. 3(a) is 2r, and is twice the radius r of the circular orbit C (as a standard), and the circular orbit C _B is a large circular orbit. The large circular orbit is a concentric circle of the circular orbit C and has a size twice. Thereby, the large circular orbit C _{B is} set as a circular orbit which is a concentric circle of the circular track C (as a standard) and has a size twice. For the same reason, when the (as standard) circular orbit C is replaced with a circular orbit C _{S (} inscribed with the equilateral triangle TR ₁ of Fig. 3(a)), the large circular orbit C _{B is} replaced with (as a standard) In the case of the circular orbit C, the circular orbit C is a circular orbit which is a concentric circle of the circular orbit C _S and has a size twice. In other words, the circular orbit C _S is a small circular orbit which is a concentric circle of the circular orbit C and has a size of half.

Next, an example of a track depending on a specific circular orbit will be described with reference to FIGS. 4(a) to 4(c). Fig. 4(a) is a general circular orbit for comparison of Fig. 4(b) and Fig. 4(c), and an X coordinate value and a Y coordinate value when the circular orbit is realized, and Fig. 4(b) is a sectional view of the circular orbit. The short track and the X coordinate value and the Y coordinate value when the track is realized, and FIG. 4(c) is the quadrilateral track and the X coordinate value and the Y coordinate value when the track is realized. The horizontal axis of Figs. 4(a) to 4(c) is the starting point (θ = 0°) from the black dots in Figs. 4(a) to 4(c) to Fig. 4(a) to Fig. 4 ( The angle axis of θ in Figs. 4(a) to 4(c) obtained at the end point (θ=360°) indicated by the arrow in c), and the vertical axis in Fig. 4(a) to Fig. 4(c) It is the X coordinate value and the Y coordinate value. Further, the X coordinate value and the Y coordinate value at the time of realizing the circular orbit of Fig. 4(a) and the X shown in Fig. 10 The coordinate value and the Y coordinate value are the same.

As shown in Fig. 4(a), the X coordinate value P _X and the Y coordinate value P _Y depict a circular orbit as in the case of Fig. 10, and therefore, the previous normal circular orbit is a sine wave (sin wave) ). Therefore, the driving amount (the absolute value of the movement amount per unit step) is in the region where the gain of the sin wave becomes large (the angle θ of the Y coordinate in FIG. 4(a) is 0°, 180°, 360°). In the vicinity, the angle θ of the X coordinate is 90° and the vicinity of 270°, respectively, and the drive directions of the X-axis straight motor 7a and the Y-axis straight motor 7b (see FIG. 1) are reversed. Therefore, the platform 2 is driven linearly by the X-axis straight motor 7a and the Y-axis straight motor 7b. If the combined track of the X-axis straight motor 7a and the Y-axis straight motor 7b is a circular track as shown in Fig. 4(a), Then, the influence of the above static friction or kickback becomes large, and it is difficult to ensure the driving accuracy.

Therefore, as shown in FIG. 4 other than FIG. 4(a), the constraint of the circular orbit is excluded, and at least a part of the track adopts a linear track (straight-forward drive). Further, there are a plurality of examples of tracks that can eliminate the micro-driving at the following positions, and these tracks are referred to as "tracks according to the circular orbit", and the positions are positions indicating that the driving direction on the circular orbit is reversed. In addition, if it is excessively deviated from a circular orbit as a standard (for example, in the case of an ellipse having a long axis that is longer than 4 times the short axis), a plurality of projection images obtained when the distance is excessively deviated from the circular orbit is used. When the tomographic image is calculated and calculated, the correct value cannot be obtained with respect to the tomographic image reconstructed by the standard circular orbit. It is also known that the reason is that the CT is different from the tomographic image of the oblique CT in consideration of an extreme example.

Therefore, as described above, the trajectory according to the circular orbit is not unlimited, and the trajectory of the range from the small circular orbit C _S (see FIG. 3( a )) to the large circular orbit C _B (see FIG. 3( a )) is set. According to the orbit of the circular orbit, the small circular orbit C _S is a concentric circle of the circular orbit C (refer to FIG. 3( a )) and has a half size, and the large circular orbit C _B is a concentric circle of the circular orbit C and has twice the size. Further, it is known that when a tomographic image is calculated and calculated based on a plurality of projection images obtained on each of the tracks shown in FIG. 4 other than FIG. 4(a), the result is compared with a circle as a standard. The tomographic image reconstructed by the orbit is approximately the same.

For example, as shown in FIG. 4(b), when the X coordinate value P _X and the Y coordinate value P _Y depict a track in which the circular orbit is truncated, the following predetermined value is set, which is larger than the driving direction. A small amount of drive at the position of the turn, and has a value of a positive real number. Further, the drive amount (the absolute value of the movement amount per unit step) is equal to or higher than the predetermined value or "0", and the controller 9 (refer to FIG. 2) respectively feeds each of the X-axis straight-in motor 7a and the Y-axis straight-in motor 7b. Take control.

More specifically, the two X-axis rectilinear motors 7a and the Y-axis rectilinear motors 7b are controlled while maintaining the following driving amount to be equal to or higher than the predetermined value, and the driving amounts are respectively made in the orthogonal coordinate system. The combined track of the two X-axis straight-feed motors 7a and the Y-axis straight-feed motors 7b that are driven in a straight-forward drive is the above-described circular track, and only the driving amount of the region in which the driving directions of the respective X-axis straight-in motors 7a and Y-axis straight-forward motors 7b are reversed is reversed. It is "0", and is controlled on each of the X-axis straight-in motor 7a and the Y-axis straight-feed motor 7b on the straight track. In other words, the driving amount of the region in which the driving directions of the respective X-axis rectilinear motors 7a and Y-axis rectilinear motors 7b are reversed is "0". It is assumed that the straight track (which is obtained by shortening the circular track) is the same track as the above-described circular track in other areas. Therefore, as shown on the right side of the figure, only the region where the driving direction is reversed is "0", and the other region is the sin wave. In this way, only the driving amount of the region in which the driving direction is reversed is "0", and the straight track is formed. In other regions, the same track as the circular track is used, whereby the circular orbit can be made as far as possible. The influence of the artifact generated at the time is reduced, and the driving accuracy of the problem region (the region in which the driving directions of the X-axis rectilinear motor 7a and the Y-axis rectilinear motor 7b are reversed) can be improved.

Further, for example, as shown in FIG. 4(c), when the X coordinate value P _X and the Y coordinate value P _Y depict a quadrilateral track (a square track inscribed in the circular orbit in FIG. 4(c)), similarly A predetermined value is set which has a value of a positive real number. Further, the controller 9 controls each of the X-axis rectilinear motor 7a and the Y-axis rectilinear motor 7b by setting the driving amount (the absolute value of the movement amount per unit step) to the predetermined value or more or "0".

More specifically, the above-described quadrilateral track is a track ranging from the small circular track C _S to the large circular track C _B , and the controller 9 controls only one of the X-axis straight-in motor 7 a and the Y-axis straight-moving motor 7 b. Further, the remaining motors are controlled such that the driving amount is "0", whereby the driving is performed on the straight track of the above-described quadrilateral track. For example, as shown on the right side of the figure, when only the X-axis straight-moving motor 7a is controlled, and the X-coordinate value P _X is changed (straight in the X direction), the driving amount of the Y-axis straight-feeding motor 7b is set to "0". The Y coordinate value P _{Y is} fixed so as to be in a stopped state. Conversely, when only the Y-axis rectilinear motor 7b is controlled, and the Y coordinate value P _Y is changed (straight in the Y direction), the driving amount of the X-axis rectilinear motor 7a is set to "0", and the X coordinate value P _{X is} fixed. So that it is in a stopped state. In this way, the amount of movement is set to "0" (that is, in the stopped state), and only the remaining linear drive mechanism (motor) is used to operate and drive straight, thereby realizing the above-described quadrilateral track, whereby the position is easily controlled and driven. Increased accuracy. Moreover, since it is a straight-forward trajectory, it is possible to drive in a shorter time than the circular orbit, and it is possible to shorten the data collection time related to photography.

As described above, when the circular orbit shown in Fig. 4(a) is realized by two or more rectilinear driving mechanisms (the X-axis rectilinear motor 7a and the Y-axis rectilinear motor 7b in this embodiment), the driving of the linear drive mechanism is achieved. When the direction is reversed, a slight drive is inevitable, so the influence of static friction or kickback becomes large and the drive accuracy cannot be maintained. Therefore, according to the X-ray inspection apparatus of the present embodiment including the above-described configuration, the controller 9 makes the absolute value (drive amount) of the movement amount per unit step a predetermined value or more of a value having a positive real number or "0". Each of the straight drive mechanisms (X-axis straight feed motor 7a, Y-axis straight feed motor 7b) is controlled separately. By the above-described control, the driving direction of the linear drive mechanism (the X-axis linear motion motor 7a and the Y-axis linear motion motor 7b) is reversed, and the minute movement is not performed, and the movement amount is equal to or higher than the predetermined value, or the movement amount is “0”. "(ie, stop state).

Further, in order to eliminate the restriction of the circular orbit, the controller does not perform minute driving at a position where the driving direction of the linear drive mechanism (the X-axis straight feed motor 7a and the Y-axis straight feed motor 7b) is reversed under the constraint that the controller 9 respectively controlling each of the linear drive mechanisms (X-axis straight-feed motor 7a and Y-axis straight-feed motor 7b) so that the track from the small round track to the large circular track is set as the track according to the circular track, and the platform 2 is given Drive, the above small The circular orbit is a concentric circle of the above-mentioned circular orbit and has a size of half, and the large circular orbit is a concentric circle of the circular orbit and has a size twice. Thereby, the driving accuracy can be maintained without performing minute driving at a position where the driving direction of the rectilinear driving mechanism (the X-axis rectilinear motor 7a and the Y-axis rectilinear motor 7b) is reversed.

In addition, it is assumed that the movement is a track having a movement amount of “0” (that is, a stop state), and the operation is performed by using only the other rectilinear drive mechanisms, and the following effects are obtained. That is, it is easy to control the position by using each of the straight drive mechanisms (drive systems), and it is also easy to maintain the drive accuracy. Further, since the driving accuracy is improved, the rigidity required for the mechanical condition is alleviated, so that the cost is also lowered, and each of the linear drive mechanisms (drive systems) can achieve low cost.

In the present embodiment, it is preferable to include a detector rotating mechanism 5 that drives the X-ray detector 4 in synchronization with the driving of the stage 2. The X-ray detector 4 is also operated, whereby the photographic field of view can be secured, and the tomographic image of a larger area can be calculated.

In the case where the detector rotating mechanism 5 is included, it is preferable that the detector rotating mechanism 5 drives the X-ray detector 4 in such a manner that the X-rays irradiated by the X-ray tube 3 are transmitted through the object O. The gaze point is detected by the central portion of the X-ray detector 4. The gaze point is captured by the central portion of the X-ray detector 4, whereby when the tomographic image is calculated, a tomographic image of a sufficiently large range can be obtained, and the tomographic image can be at substantially the same position (the gaze point) ) is constructed again (back projection) and is based on the center of the photographic field of view.

The present invention is not limited to the above embodiment, and can be modified in the following manner.

(1) In the above embodiment, the radiographic apparatus has been described using the X-ray inspection apparatus as an example. However, the apparatus is a device that acquires a tomographic image based on a plurality of projection images to perform radiography. The radiation is not limited to X-rays, and may be radiation other than X-rays (α-rays, β-rays, γ-rays, etc.).

(2) The object is not particularly limited. As described above, for example, a through hole/pattern/solder joint portion of a mounting substrate, a multilayer substrate, an electronic component before assembly such as an integrated circuit (IC) disposed on a pallet, a cast of metal or the like, and A molded article such as a video cassette recorder or the like is exemplified as long as the object is radiographed.

(3) In the above embodiment, the track according to the circular orbit is the track shown in Fig. 4 (b) or Fig. 4 (c), but as long as the combination of two or more direct drive mechanisms is included, each unit step is The absolute value (driving amount) of the amount of movement is a predetermined value or more of a value having a positive real number or "0", and each of the rectilinear driving mechanisms is controlled, and a track from the small circular orbit to the range of the large circular orbit is controlled. The track according to the circular orbit is not limited to this. For example, as shown in FIG. 5( a ), a quadrilateral track having a vertex in the direction of the drive shaft (in this case, the X axis and the Y axis) may be a dome point as shown in FIG. 5( b ). The bulging track has a vertex that has a vertex only in the region where the inversion occurs, and the other region is a circular orbit. In addition, as shown in FIG. 5(c), it may be a quadrilateral track circumscribing the circular orbit (a square track in FIG. 5(c)), as shown in FIG. 5(d), An orthorhombic orbit that is inscribed or circumscribed with a circular orbit.

(4) In the above embodiment, in order to draw the trajectory according to the circular orbit (along the horizontal plane), the two X-axis straight-in motors 7a and the Y-axis straight-moving motors 7b shown in Fig. 2 are respectively controlled, but even if In a vertical posture, that is, in a state in which the platform is maintained in a horizontal posture, a track according to a circular orbit along the vertical plane is drawn as long as the object can be placed on the platform (for example, placed on the platform by the supporting member) Alternatively, as long as the radiation irradiation unit (the X-ray tube 3 in the embodiment) is driven as in the modification (8) to be described later, the horizontal plane may be set to the XY plane as shown in FIG. When the Z axis is a vertical axis, the X-axis linear motor 7a and the Z-axis linear motor 7c (see FIG. 2) are respectively controlled so as to draw a track according to a circular orbit along the vertical plane, or respectively The Y-axis straight feed motor 7b and the Z-axis straight feed motor 7c are controlled.

(5) In the above embodiment, in order to describe the track according to the circular orbit, to describe the track according to the circular orbit along the horizontal plane, respectively, for each of the straight-forward driving mechanisms (in the embodiment, two X-axis straight-in motors) 7a and the Y-axis straight-moving motor 7b) are controlled. However, in the above-described modification (4), each of the rectilinear driving mechanisms may be controlled so as to draw a track according to a circular orbit along the vertical plane. Each of the rectilinear driving mechanisms is separately controlled in accordance with the manner of the track along the circular orbit of the inclined surface.

(6) In the above embodiment, in order to describe the trajectory according to the circular orbit, a combined drive unit including the combination of the two X-axis linear motors 7a and the Y-axis linear motors 7b shown in Fig. 2 is respectively Platform driver The control 7 is controlled, but the combined drive unit including the combination of three or more linear drive mechanisms may be separately controlled. In order to describe the trajectory according to the circular orbit, for example, in addition to the X-axis straight-moving motor 7a and the Y-axis straight-moving motor 7b, the Z-axis straight-moving motor 7c (see FIG. 2) may be combined. Further, the present invention is not limited to the orthogonal coordinate system. For example, at least one of the X-axis straight feed motor 7a, the Y-axis straight feed motor 7b, and the Z-axis straight feed motor 7c may be combined with a motor that is opposite to the motor. In the above shaft, the linear drive is performed along the axis in the oblique direction.

(7) In the above embodiment, as shown in Fig. 1, a radiation irradiation unit (X-ray tube 3 in the embodiment) and a radiation detecting unit from the oblique direction in which the tomographic angle is inclined are disposed (X-ray detection in the embodiment) 4), photographing from the oblique direction, but as shown in each of FIGS. 6(a) to 6(e), the radiation irradiation unit (X-ray tube 3) and the radiation detecting unit (X-ray detector 4) may be disposed. . Moreover, the radiation irradiation unit may be disposed on the upper side, and the radiation detection unit may be disposed on the lower side.

(8) In the above embodiment, as shown in FIG. 1, the stage 2 is driven, but as long as at least one of the radiation irradiation unit (the X-ray tube 3 in the embodiment) and the stage 2 is driven, It is not limited to driving only the platform 2. For example, as shown in FIG. 6(b) or FIG. 6(e), only the radiation irradiation unit (X-ray tube 3) can be driven, and as shown in FIG. 6(e), the radiation irradiation unit (X-ray) can also be used. Both the tube 3) and the platform 2 are driven.

(9) In the above embodiment, as shown in Fig. 1, in synchronization with the driving of the stage 2, the radiation detecting unit (X-ray detector 4 in the embodiment) Although it is driven, as shown in FIG. 6(c) to FIG. 6(e), the radiation detecting unit (X-ray detector 4) may be driven to perform imaging. In this case, there is an effect that the radiation detecting unit (X-ray detector 4) does not require a special driving mechanism.

(10) In the above embodiment, as shown in FIG. 1, a configuration is adopted in which radiation (X-ray in the embodiment) is transmitted through the gaze point of the object O, and the radiation detecting unit (X-ray in the embodiment) is used. The center portion of the detector 4) detects the above-described radiation, but as shown in FIG. 6(d) or FIG. 6(e), as long as the radiation detecting unit (X-ray detector 4) is wide, it is not necessary to use radiation detection. A central portion of the unit (X-ray detector 4) detects radiation (X-rays).

1‧‧‧X-ray inspection device

2. S‧‧‧ platform

3. T‧‧‧X-ray tube

4, D‧‧‧X-ray detector

5‧‧‧Detector rotation mechanism

5a, 6b‧‧‧ rotating motor

6‧‧‧Detector tilting movement mechanism

6a‧‧‧Guidance

7‧‧‧ platform drive mechanism

7a‧‧‧X-axis straight-in motor

7b‧‧‧Y-axis straight-in motor

7c‧‧‧Z-axis straight-in motor

8‧‧‧ tomographic image calculation department

9‧‧‧ Controller

10‧‧‧Image Output Department

AB‧‧‧ side

Ax‧‧‧Rotary axis

C‧‧‧ as a standard circular orbit

C _B ‧‧‧ large circular orbit / circular orbit

C _S ‧‧‧Small circular orbit

HEX‧‧‧正六形

O‧‧‧Objects

P _X ‧‧‧X coordinate value

P _Y ‧‧‧Y coordinate value

R ₁ , R ₂ ‧‧‧ arrows

R‧‧‧ Radius

2r‧‧‧ Length/radius of the bevel

TR ₁ , TR ₂ , TR ₃ ‧‧‧正三角

TR ₄ ‧‧‧Right triangle

X, Y, Z‧‧‧Orthogonal coordinate system

Θ‧‧‧ angle

Fig. 1 is a schematic configuration diagram of an X-ray inspection apparatus according to an embodiment.

Fig. 2 is a block diagram of an X-ray inspection apparatus of the embodiment.

Fig. 3(a) is a diagram showing a small circular orbit, a large circular orbit, an inscribed triangle which is inscribed with the circular orbit and circumscribing the small circular orbit, and an inscribed with the large circular orbit and the circle. A schematic diagram of an equilateral triangle circumscribing the track, the small circular orbit is a concentric circle of a circular orbit and has a size of half. The large circular orbit is a concentric circle of a circular orbit and has a size of 2 times. FIG. 3(b) is in addition to the illustration. In addition to the circular orbit and the large circular orbit, a regular hexagon, an equilateral triangle, a diagonal connecting the regular hexagon, a side that does not pass the circular orbit, the center of the large circular orbit, and A schematic diagram of a right triangle in which the above-mentioned equilateral triangle is connected by a diagonal of a regular hexagon and passes through a center of a circular orbit and a large circular orbit. The right-angled triangle is formed by the above-described right-angled triangle, the side that does not pass the circular orbit, the center of the large circular orbit, the side of the equilateral triangle, and the side that passes through the center of the large circular orbit.

Fig. 4(a) is a general circular orbit for comparison of Fig. 4(b) and Fig. 4(c), and an X coordinate value and a Y coordinate value when the circular orbit is realized, and Fig. 4(b) is a sectional view of the circular orbit. The short track and the X coordinate value and the Y coordinate value when the track is realized, and FIG. 4(c) is the quadrilateral track and the X coordinate value and the Y coordinate value when the track is realized.

5(a) to 5(d) show various aspects of the trajectory according to the circular orbit according to the modification.

6(a) to 6(e) show the respective driving forms for performing oblique imaging in the modification.

Fig. 7 is a schematic view of a previous photographing.

Fig. 8 is a schematic view of a prior oblique photographing.

Fig. 9 is a schematic view showing a previous oblique photographing when the stage is moved in parallel and the X-ray detector is rotationally driven in synchronization with the movement of the stage.

Fig. 10 is an X coordinate value and a Y coordinate value when a normal circular orbit is realized.

2‧‧‧ platform

P _X ‧‧‧X coordinate value

P _Y ‧‧‧Y coordinate value

X, Y‧‧‧Orthogonal coordinate system

Θ‧‧‧ angle

Claims (5)

A radiographic apparatus comprising: a stage on which an object is placed; a radiation irradiation unit and a radiation detecting unit disposed to face each other across the platform; and an arithmetic unit, wherein the radiation detecting unit detects the radiation irradiation unit A plurality of projection images are obtained by irradiating and transmitting radiation of the object, and the calculation unit calculates a tomographic image based on the plurality of projection images, and the radiographic apparatus includes a synthesis drive unit including two or more a combination of the linear drive mechanisms, the composite track of each of the linear drive mechanisms is a track based on a circular track, and the radiation irradiation unit and at least one of the platforms are driven; and a control unit controls the synthetic drive unit The control unit controls each of the linear drive mechanisms so that the absolute value of the movement amount per unit step is equal to or greater than a predetermined value of a value having a positive real number, and is "0" from the circular orbit. Small round rail of half the size of a concentric circle a track in a range up to a large circular orbit of twice the concentric circle of the circular orbit as the track according to the circular orbit, and each of the linear drive mechanisms is controlled to control at least the radiation irradiation unit and the platform One is driven. A radiographic apparatus according to claim 1, wherein The control unit controls each of the rectilinear driving mechanisms while maintaining the movement amount of each unit step to be equal to or higher than the predetermined value, and the movement amount of each unit step is such that the orthogonal movement is directly driven in the orthogonal coordinate system. The combined track of the two straight forward drive mechanisms is the above-described circular track, and the movement amount of each of the unit steps of the region in which the driving directions of the respective linear drive mechanisms are reversed is "0", on the straight track, Each of the above-mentioned straight drive mechanisms is separately controlled. The radiographic apparatus according to claim 1, wherein the track according to the circular orbit is a track ranging from the small circular track to the large circular orbit, and is a quadrilateral track, and the control unit only advances one of the above-mentioned The drive mechanism performs control so that the amount of movement of each unit step described above is "0", and the remaining straight drive mechanisms are controlled, thereby driving on the straight track of the quadrilateral track. The radiographic apparatus according to any one of claims 1 to 3, further comprising a driving unit for detecting, wherein the driving unit for detecting is at least the radiation irradiation unit of the synthetic driving unit and at least one of the platforms The driving of one is synchronized, and the above-described radiation detecting unit is driven in this manner. The radiographic apparatus of claim 4, wherein The detection drive unit drives the radiation detecting unit to transmit the radiation irradiated by the radiation irradiation unit to the fixation point of the object, and to detect the radiation by the central portion of the radiation detection unit.