阅读说明：本技术 图像取得系统和图像取得方法 (Image acquisition system and image acquisition method ) 是由 杉山元胤 大西达也 于 2019-01-10 设计创作，主要内容包括：图像取得系统具备：放射线源,其向对象物输出放射线；旋转平台,其以在旋转轴线周围使对象物旋转的方式构成；放射线相机,其具有输入透过了对象物的放射线的输入面和能够进行TDI控制的图像传感器；以及图像处理装置,其基于图像数据生成对象物的摄像面(P)上的放射线图像。旋转平台的旋转轴线与放射线相机的输入面所成的角度根据作为放射线源与对象物内的摄像面的距离的FOD来设定。放射线相机以与由旋转平台得到的对象物的旋转速度同步地进行图像传感器中的TDI控制的方式构成。(The image acquisition system includes: a radiation source that outputs radiation to a subject; a rotation platform configured to rotate an object around a rotation axis; a radiation camera having an input surface for inputting radiation transmitted through an object and an image sensor capable of TDI control; and an image processing device which generates a radiation image on an imaging plane (P) of the object based on the image data. An angle formed by the rotation axis of the rotation platform and the input surface of the radiation camera is set according to FOD which is a distance between the radiation source and the imaging surface in the subject. The radiation camera is configured to perform TDI control in the image sensor in synchronization with the rotation speed of the object obtained by the rotation stage.)

1. An image acquisition system in which, in a case where,

the disclosed device is provided with:

a radiation source that outputs radiation to a subject;

a rotating platform configured to rotate the object around a rotation axis;

a radiation camera which has an input surface to which the radiation transmitted through the object is input and an image sensor capable of TDI control, and which captures the input radiation and outputs image data, wherein TDI is time delay integration; and

an image processing device that generates a radiation image on an imaging surface of the object based on the image data,

an angle formed by the rotation axis of the rotation platform and the input surface of the radiation camera is an acute angle and is set according to FOD which is a distance between the radiation source and an imaging surface in the object,

the radiation camera is configured to perform TDI control in the image sensor in synchronization with the rotational speed of the object obtained by the rotation stage.

2. The image acquisition system according to claim 1,

the radiation source is configured to be capable of moving the rotating table in the direction of the rotation axis, and the target is moved toward and away from the radiation source.

3. The image acquisition system according to claim 1 or 2,

the radiation imaging apparatus further includes an angle adjusting unit configured to hold the rotation platform or the radiation camera and adjust an angle formed between the rotation axis of the rotation platform and the input surface of the radiation camera.

4. The image acquisition system according to claim 3,

the angle adjusting unit is configured to adjust an angle formed by the rotation axis of the rotation platform and the input surface of the radiation camera, based on FOD which is a distance between the radiation source and an imaging surface in the object.

5. The image acquisition system according to claim 3 or 4,

the angle adjustment unit holds the radiation camera such that the input surface of the radiation camera is tilted with respect to the rotation axis.

6. The image acquisition system according to claim 3 or 4,

the angle adjustment unit holds the rotation platform such that the rotation axis is tilted with respect to the input surface of the radiation camera.

7. The image acquisition system according to any one of claims 1 to 6,

the radiation camera includes a scintillator having the input surface, and the image sensor captures scintillation light emitted by the scintillator in response to input of the radiation.

8. The image acquisition system according to any one of claims 1 to 6,

the image sensor is a direct conversion type radiation image sensor having the input surface.

9. An image acquisition method, wherein,

comprises the following steps:

a rotation step of rotating the object at a predetermined speed around the rotation axis by using the rotation platform;

a radiation output step of outputting radiation from a radiation source to the rotating object;

a radiation imaging step of imaging the input radiation and outputting image data using a radiation camera having an input surface to which the radiation transmitted through the object is input and an image sensor capable of TDI control, where TDI is time delay integration; and

an image generation step of generating a radiation image on an imaging surface of the object based on the image data,

an angle formed by the rotation axis of the rotation platform and the input surface of the radiation camera is an acute angle and is set according to FOD which is a distance between the radiation source and an imaging surface in the object,

in the radiation imaging step, TDI control in the image sensor is performed in synchronization with the rotational speed of the object obtained by the rotating stage.

10. The image acquisition method according to claim 9,

further comprising: a moving step of controlling the rotation stage to move in the rotation axis direction so that the object approaches or moves away from the radiation source.

11. The image acquisition method according to claim 9 or 10,

further comprising: an adjustment step of adjusting an angle formed by the rotation axis of the rotation platform and the input surface of the radiation camera by rotating the rotation platform or the radiation camera.

12. The image acquisition method according to claim 11,

in the adjusting step, an angle formed by the rotation axis of the rotation platform and the input surface of the radiation camera is adjusted according to FOD which is a distance between the radiation source and an imaging surface in the subject.

13. The image acquisition method according to claim 11 or 12,

in the adjusting step, the radiation camera is rotated such that the input surface of the radiation camera is tilted with respect to the rotation axis.

14. The image acquisition method according to claim 11 or 12,

in the adjusting step, the rotation platform is rotated so that the rotation axis is tilted with respect to the input surface of the radiation camera.

15. The image acquisition method according to any one of claims 9 to 14,

the radiation camera includes a scintillator having the input surface, and in the radiation imaging step, the radiation camera images scintillation light emitted by the scintillator in response to the input of the radiation.

16. The image acquisition method according to any one of claims 9 to 14,

the image sensor is a direct conversion type radiation image sensor having the input surface.

Technical Field

The present invention relates to an image acquisition system and an image acquisition method.

Background

Conventionally, there is known an apparatus for obtaining an X-ray image of an object by irradiating the object to be transported with X-rays, detecting the X-rays having passed through the object, and performing TDI (time delay integration) control (see patent documents 1 and 2). In the apparatus described in patent document 1, the object is conveyed by a belt conveyor. The X-ray sensor has a structure in which element rows each including a plurality of detection elements arranged in a direction orthogonal to the conveyance direction are arranged in multiple stages in the conveyance direction. In the device described in patent document 2, a container containing a sample (object) is moved in the X direction, and the container is rotated. The TDI camera performs imaging in synchronization with the transfer speed of the sample. The angular velocity of the container is set to be equal to the ratio of the moving speed in the TDI integration direction to the distance from the focal point of the X-ray source to the rotation center.

Disclosure of Invention

Technical problem to be solved by the invention

In the present invention, an apparatus is discussed that irradiates an object rotating around a rotation axis with radiation and obtains a radiation image using a TDI-controllable camera. In this device, the rotation axis intersects a light receiving surface (or an extension thereof) of a sensor of the camera. The velocity of the inner periphery of the object is different from the velocity of the outer periphery of the object. In the case where TDI control is performed based on the speed of the inner peripheral portion, the acquired radiographic image may become unclear at the outer peripheral portion. That is, when TDI control is performed based on the speed of an arbitrary portion in the radial direction of the object, the acquired radiographic image may become unclear in other portions. In this way, the difference in velocity (peripheral velocity) due to the difference in radius makes it difficult to obtain a sharp radiographic image by TDI control.

The present invention describes an image acquisition system and an image acquisition method that can acquire a sharp radiographic image even in any portion in the radial direction of an object.

Means for solving the problems

An image acquisition system according to an aspect of the present invention includes: a radiation source that outputs radiation to a subject; a rotation platform configured to rotate an object around a rotation axis; a radiation camera which has an input surface for inputting radiation transmitted through an object and an image sensor capable of TDI (time delay integration) control, and which captures the input radiation and outputs image data; and an image processing device that generates a radiographic image on an imaging surface of the object based on the image data, wherein an angle formed by a rotation axis of the rotation platform and an input surface of the radiation camera is an acute angle, and is set according to FOD which is a distance between the radiation source and the imaging surface in the object, and the radiation camera is configured to perform TDI control in the image sensor in synchronization with a rotation speed of the object obtained by the rotation platform.

An image acquisition method according to another aspect of the present invention includes: a step (rotation step) of rotating the object at a predetermined speed around the rotation axis by using the rotation platform; a step of outputting radiation from a radiation source to the rotating object (radiation output step); a step (radiation imaging step) of imaging the input radiation and outputting image data using a radiation camera having an input surface to which the radiation transmitted through the object is input and an image sensor capable of TDI (time delay integration) control; and a step (image generation step) of generating a radiographic image on the imaging plane P of the object based on the image data, wherein an angle formed by the rotation axis of the rotation platform and the input plane of the radiation camera is an acute angle, and is set according to FOD which is a distance between the radiation source and the imaging plane in the object, and in the step of outputting the image data, TDI control in the image sensor is performed in synchronization with the rotation speed of the object obtained by the rotation platform.

According to the image acquisition system and the image acquisition method described above, TDI in the image sensor is controlled in synchronization with the rotation speed of the object obtained by the rotating platform. In the imaging plane of the object, the speed of the inner peripheral portion (portion closest to the rotation axis) is slower than the speed of the outer peripheral portion (portion farthest from the rotation axis). An angle as an acute angle is formed between the rotation axis of the rotation platform and the incident surface of the radiation camera. Therefore, the distance between the radiation source and the portion of the input surface to which radiation transmitted through the inner peripheral portion is input is longer than the distance between the radiation source and the portion of the input surface to which radiation transmitted through the outer peripheral portion is input. This means that the magnification in the inner peripheral portion is greater than the magnification in the outer peripheral portion. The transport speed in TDI control, which is adapted to a predetermined linear velocity, is inversely proportional to the magnification. The influence of the speed difference between the inner peripheral portion and the outer peripheral portion is mitigated by the magnitude relation of the magnification. In addition, the angle formed by the rotation axis of the rotary platform and the incident surface of the radiation camera is set according to TOD which is the distance between the radiation source and the imaging surface in the object, so that the ratio of the magnification becomes the reciprocal of the velocity ratio in the inner peripheral portion and the outer peripheral portion, and focusing is possible. As a result, focusing can be performed at any portion between the inner peripheral portion and the outer peripheral portion. Therefore, a sharp radiographic image can be obtained for any portion in the radial direction of the object.

In some embodiments, the image acquisition system further includes a stage movement control unit configured to control the movement of the rotating stage in the rotation axis direction so as to move the object closer to and away from the radiation source. The distance between the radiation source and the object can be adjusted by the stage movement control unit. In other words, an imaging surface based on the FOD described above can be set at an arbitrary position in the rotation axis direction (i.e., thickness direction) of the object. In this case, if the source is stationary, FOD is considered constant. A radiation image of an arbitrary position in the thickness direction of the object can be acquired.

In some embodiments, the image acquisition system further includes an angle adjustment unit configured to hold the rotary table or the radiation camera and adjust an angle formed between a rotation axis of the rotary table and an input surface of the radiation camera. In this case, the angle between the rotation axis of the rotation platform and the input surface of the radiation camera can be adjusted to an appropriate angle corresponding to the FOD by the angle adjusting unit.

In some aspects of the image acquisition system, the angle adjuster is configured to adjust an angle formed by the rotation axis of the rotation platform and the input surface of the radiation camera, based on FOD which is a distance between the radiation source and the imaging surface in the object. In this case, focusing can be performed on any FOD.

In some aspects of the image acquisition system, the angle adjuster holds the radiation camera in such a manner that an input surface of the radiation camera is tilted with respect to the rotation axis. In this case, the posture of the radiation camera may be adjusted, and the angle formed by the rotation axis of the rotation platform and the input surface of the radiation camera may be adjusted to an appropriate angle corresponding to the FOD.

In some aspects of the image acquisition system, the angle adjuster holds the rotation platform in such a manner that the rotation axis is inclined with respect to the input surface of the radiation camera. In this case, the posture of the rotary table may be adjusted, and the angle formed by the rotation axis of the rotary table and the input surface of the radiation camera may be adjusted to an appropriate angle corresponding to the FOD.

In some aspects of the image acquisition system, the radiation camera includes a scintillator having an input surface, and the image sensor captures scintillation light emitted by the scintillator in response to input of radiation. In this case, a sharp radiographic image of the object can be acquired.

In some aspects of the image acquisition system, the image sensor is a direct conversion type radiation image sensor having an input surface. In this case, a sharp radiographic image of the object can be acquired.

In some embodiments, the image acquisition method further includes a step (moving step) of controlling movement of the rotating table in the direction of the rotation axis so that the object approaches or separates from the radiation source. According to this step, the distance between the radiation source and the object can be adjusted. In other words, an imaging surface based on the FOD described above can be set at an arbitrary position in the rotation axis direction (i.e., thickness direction) of the object. In this case, if the source is stationary, FOD is considered constant. A radiation image of an arbitrary position in the thickness direction of the object can be acquired.

In some aspects, the image acquisition method further includes a step of adjusting an angle formed by a rotation axis of the rotation platform and an input surface of the radiation camera by rotating the rotation platform or the radiation camera (adjustment step). In this case, the angle formed by the rotation axis of the rotation platform and the input surface of the radiation camera can be adjusted to an appropriate angle corresponding to the FOD by the step of adjusting the angle.

In some aspects of the image acquisition method, in the adjusting step, an angle formed by a rotation axis of the rotation platform and an input surface of the radiation camera is adjusted in accordance with FOD which is a distance between the radiation source and an imaging surface in the object. In this case, focusing can be performed on any FOD.

In some aspects of the image acquisition method, in the adjusting step, the radiation camera is rotated such that an input surface of the radiation camera is tilted with respect to the rotation axis. In this case, the posture of the radiation camera may be adjusted, and the angle formed by the rotation axis of the rotation platform and the input surface of the radiation camera may be adjusted to an appropriate angle corresponding to the FOD.

In some aspects of the image acquisition method, in the adjusting step, the rotation platform is rotated such that the rotation axis is inclined with respect to the input surface of the radiation camera. In this case, the posture of the rotary table may be adjusted, and the angle formed by the rotation axis of the rotary table and the input surface of the radiation camera may be adjusted to an appropriate angle corresponding to the FOD.

In some aspects of the image acquisition method, the radiation camera includes a scintillator having an input surface, and in the radiation imaging step, scintillation light emitted by the scintillator in response to input of radiation is imaged. In this case, a sharp radiographic image of the object can be acquired.

In some forms of the image acquisition method, the image sensor is a direct conversion type radiation image sensor having an input surface. In this case, a sharp radiographic image of the object can be acquired.

ADVANTAGEOUS EFFECTS OF INVENTION

According to some aspects of the present invention, a sharp radiographic image can be acquired for any radial portion of the object.

Drawings

Fig. 1 is a diagram showing a schematic configuration of an image acquisition apparatus according to a first embodiment of the present invention.

Fig. 2 is a diagram for explaining a positional relationship among the radiation source, the subject, and the radiation camera in the image acquisition apparatus of fig. 1.

Fig. 3 is a diagram FOR explaining the FOR, FDD, and inclination of the radiation camera in the image acquisition apparatus of fig. 1.

Fig. 4 is a diagram for explaining the speed of the inner peripheral portion and the speed of the outer peripheral portion of the rotating object.

Fig. 5 (a) to 5 (d) are diagrams illustrating the movement of the imaging surface by the stage movement control unit.

Fig. 6 is a flowchart showing a procedure of an image acquisition method using the image acquisition apparatus of fig. 1.

Fig. 7 is a diagram showing a schematic configuration of a modification of the first embodiment.

Fig. 8 is a diagram showing a schematic configuration of an image acquisition apparatus according to a second embodiment of the present invention.

Fig. 9 is a flowchart showing a procedure of an image acquisition method using the image acquisition apparatus of fig. 8.

Fig. 10 is a diagram showing a schematic configuration of an image acquisition apparatus according to a third embodiment of the present invention.

Fig. 11 is a diagram for explaining a positional relationship among the radiation source, the subject, and the radiation camera in the image acquisition apparatus of fig. 10.

Fig. 12 is a diagram for explaining each condition of the simulation.

Fig. 13 is a graph showing the simulation result of comparative example 1.

Fig. 14 is a graph showing the simulation result of comparative example 2.

Fig. 15 is a graph showing the simulation result according to the embodiment.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description thereof will be omitted. Each drawing is created for the purpose of explanation, and is drawn so as to particularly emphasize a part to be explained. Therefore, the dimensional ratios of the respective members in the drawings are not necessarily in agreement with reality.

As shown in fig. 1 and 2, the image acquisition system 1 is an apparatus for acquiring a radiation image of an object 20. The image acquisition system 1 acquires a radiation image of a certain portion of the object 20, for example, along a radial direction. The object 20 includes, for example, a cylindrical wheel (wheel) portion 22 centered on the rotation axis L, and a roller (roll) portion 21 wound around the wheel portion 22. An annular boundary surface 23 is formed between the wheel portion 22 and the roller portion 21. The image acquisition system 1 may be configured such that the wheel portion 22 is not included in the radiographic image. That is, the image acquisition system 1 may be configured to acquire a radiographic image of only the roller portion 21. The roller portion 21 is, for example, a sheet capacitor wound in a roll shape. The roller portion 21 may be a spacer wound in a roll shape. The object 20 may not have the wheel portion 22, and the object 20 may be a single disk or the like. In this case, the object 20 has a rotation axis L. The shape and size of the object 20 are not particularly limited. The object 20 may be a circular object (a cylindrical or disc-shaped object), a non-circular object, or an object having an angle such as a box shape. The object 20 may be a fixed-shape object or a deformable object made of a soft material. When the image acquisition system 1 is used for inspecting the object 20, the roller portion 21 is an inspection portion which is a portion to be inspected.

The image acquisition system 1 acquires a radiation image on an imaging surface located at a predetermined position in the thickness direction, that is, in the direction of the rotation axis L in the roller portion 21. In other words, the image acquisition system 1 acquires a radiation image focused on the imaging surface in the roller portion 21. The image acquisition system 1 can detect, for example, a foreign substance, a defect, or the like that may exist in the roller portion 21 of the object 20 by acquiring a radiation image. The image acquisition system 1 can detect an object made of, for example, a polyamide fiber, a polyolefin fiber, a split composite fiber, a single fiber, or a core-sheath composite fiber, and a foreign substance made of a metal that may be present in the object.

The image acquisition system 1 includes a radiation generating apparatus 3 that generates radiation such as white X-rays. The radiation generating apparatus 3 includes a radiation source 2 that outputs radiation to the subject 20. The radiation source 2 emits (outputs) cone beam X-rays from the X-ray emission unit. The radiation source 2 may be, for example, a microfocus X-ray source or a millifocal X-ray source. The X-rays emitted from the radiation source 2 form a radiation beam 2 a. The region where the radiation beam 2a exists is an emission region of the radiation source 2. The shape or structure of the X-ray emitting section may be designed such that the wheel section 22 of the object 20 is not included in the radiographic image. The radiation source 2 is configured to be capable of adjusting a tube voltage and a tube current.

The image acquisition system 1 includes: a rotation platform 6 configured to hold the object 20 and rotate the object 20 around the rotation axis L; and a radiation camera 4 that receives radiation output from the radiation source 2 and transmitted through the object 20 and captures an image. The rotary table 6 may include, for example, a motor driven by supplying power, a gear portion coupled to the motor, and a table main body rotated via the gear portion. The rotary table 6 rotates the table main body at a constant speed, for example. That is, the rotary platform 6 (or its platform body) can be said to have the rotation axis L. The rotation speed of the rotary platform 6 can be appropriately adjusted.

The radiation camera 4 has, for example: a scintillator 11 including an input surface 11a to which radiation having passed through the object 20 is input, and generating scintillation light in response to the input of the radiation; a FOP (Fiber Optic Plate) 12 that transmits scintillation light generated by the scintillator 11; and an image sensor 13 including a light receiving surface 13a to which the flare light transmitted through the FOP12 is input, and configured to pick up the flare light and output image data. The radiation camera 4 is, for example, an indirect conversion type camera in which the FOP12 with the scintillator 11 attached thereto is coupled to the image sensor 13. The radiation camera 4 indirectly images the radiation input to the input surface 11a of the scintillator 11, and outputs image data.

The scintillator 11 is a plate-like (e.g., flat plate-like) wavelength conversion member. The scintillator 11 converts radiation that has passed through the object 20 and entered the entrance surface 11a into scintillation light. Radiation of relatively low energy is converted on the input surface 11a side, and is emitted (output) from the input surface 11 a. The radiation of relatively high energy is converted at the back surface of the scintillator 11, and is emitted (output) from the back surface.

The FOP12 is a plate-like (e.g., flat plate-like) optical device. The FOP12 is made of, for example, glass fiber, and transmits flare light or the like with high efficiency. The FOP12 shields radiation such as white X-rays.

The image sensor 13 is an area image sensor capable of TDI (time delay integration) driving. The image sensor 13 is, for example, a CCD area image sensor. The image sensor 13 has a structure in which a plurality of CCD elements are arranged in a row in the pixel direction, and a plurality of CCD elements are arranged in a plurality of stages in the integration direction in accordance with the moving direction of the object 20. The integration direction means a direction orthogonal to the pixel direction, and corresponds to a paper surface vertical direction in fig. 1 and 3. The image sensor 13 is controlled by a timing control unit 16 described below so as to perform charge transfer in accordance with the speed (peripheral speed) of the object 20. That is, the image sensor 13 transfers electric charge on the light receiving surface 13a in synchronization with the rotation speed of the object 20 obtained by the rotating platform 6. Thus, a radiation image having a good S/N ratio can be obtained.

The image sensor 13 may be a CMOS area image sensor capable of TDI (time delay integration) driving. In addition, the image sensor 13 may be a CCD-CMOS image sensor capable of TDI (time delay integration) driving. For example, the CCD-CMOS image sensor is the one described in japanese patent laid-open nos. 2013 and 098420 or 2013 and 098853. Note that the meaning of "capable of TDI driving" is the same as that of "capable of TDI control".

The image acquisition system 1 includes: an image processing apparatus 10 that generates a radiation image on an imaging plane P of the object 20 based on image data output from the radiation camera 4; a display device 15 that displays the radiographic image generated by the image processing device 10; and a timing control unit 16 that controls imaging timing in the radiation camera 4. In the image acquisition system 1, the radiation generating apparatus 3 and the radiation camera 4 are fixed, while the object 20 rotates. The imaging plane P is, for example, a portion set at a predetermined position in the object 20 or on the object 20, and is a fixed stationary region after being set once.

The image Processing apparatus 10 is configured by a computer having, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input/output interface, and the like. The image processing apparatus 10 may have an image processing processor for creating a radiation image of the object 20 based on radiation image data output from the radiation camera 4. The image processing processor inputs, for example, radiation image data, and performs prescribed processing such as image processing on the input radiation image data. The image processing processor outputs the generated radiation image to the display device.

As the display device 15, a known display can be used. An input device not shown may be connected to the image processing apparatus 10. The input device may be, for example, a keyboard or a mouse. The user can input various parameters such as the thickness of the object 20, the position of the boundary surface 23 in the object 20, and the position of the imaging plane P using the input device.

The timing control unit 16 is constituted by a computer having a CPU, a ROM, a RAM, an input/output interface, and the like, for example. The timing control section 16 may have a control processor that controls the imaging timing in the radiation camera 4. The control processor controls the radiation camera 4 and the rotary platform 6 based on, for example, the thickness of the object 20, the position of the boundary surface 23 in the object 20, or the position of the imaging plane P, which are stored by user input or the like. The image processing apparatus 10 and the timing control unit 16 may be configured as a program executed by a single computer, or may be configured as units provided separately.

The image acquisition system 1 further includes: a table lifter 7 for lifting the rotary table 6 in the direction of the rotation axis L; and a table elevation control unit (table movement control unit) 17 configured to control (move control) elevation of the rotary table 6 in the table elevator 7. As the platform lift 7, a known lift can be used. The platform elevator 7 may include, for example, a ball screw and a motor (driving source) disposed on the rotation axis L and penetrating the rotating platform 6 and the object 20. The platform lift 7 is not limited to a screw type, and may be a telescopic type lift using hydraulic pressure or the like as a driving source, for example.

The platform elevation control unit 17 is constituted by a computer having a CPU, ROM, RAM, input/output interface, and the like, for example. The table elevation control unit 17 may have a control processor that controls the movement of the rotating table 6 in the direction of the rotation axis L. The control processor controls the stage lifter 7 based on, for example, the thickness of the object 20 or the position of the imaging plane P stored by the user's input or the like. The table elevation control unit 17 controls the table elevator 7 to move the object 20 toward or away from the radiation source 2. That is, the table elevation control unit 17 is configured to move the object 20 toward and away from the radiation source 2.

The respective components of the image acquisition system 1 described above may be accommodated in a casing, not shown, and fixed in the casing. Further, the above-described structures may be assembled to the base, for example, without being housed in the housing. All or at least one of the radiation source 2, the radiation camera 4, and the rotation platform 6 may be movable so as to be able to adjust the relative positional relationship therebetween. The image processing apparatus 10 may be housed in a casing or may be provided outside the casing. All or at least one of the image processing apparatus 10, the display apparatus 15, the timing control unit 16, and the table elevation control unit 17 may be provided at a position separated from the position where the radiation source 2, the radiation camera 4, and the rotating table 6 are provided. The control by the image processing apparatus 10, the timing control unit 16, and the stage elevation control unit 17 may be remote control using wireless communication.

Next, the arrangement and positional relationship of the radiation source 2, the rotating table 6, and the radiation camera 4 will be described. As shown in fig. 1 and 2, the rotating table 6 is disposed, for example, between the radiation source 2 and the radiation camera 4. More specifically, the rotating platform 6 is provided at a position where the rotation axis L of the rotating platform 6 passes through the side of the radiation source 2. Thereby, the boundary surface 23 of the object 20 is positioned directly below the radiation source 2. In other words, the radiation generating device 3 and the rotating platform 6 are disposed such that an extended surface (a cylindrical surface centered on the rotation axis L in the present embodiment) of the boundary surface 23 passes through the radiation source 2. The emission area of the radiation source 2 includes the roller portion 21 or passes through the roller portion 21. The radiation camera 4 is disposed so that the radiation transmitted through the roller portion 21 of the object 20 is input to the input surface 11a of the radiation camera 4 (see fig. 2). In other words, the input surface 11a of the radiation camera 4 is disposed so as to include an imaginary plane including the radiation source 2 and the rotation axis L.

In the present embodiment, the radiation camera 4 is provided obliquely so that the input surface 11a thereof forms an acute angle with respect to the rotation axis L of the rotation table 6. This alleviates the influence of the speed difference between the inner peripheral portion and the outer peripheral portion of the roller portion 21 in the obtained radiographic image (described in detail later). In this specification, the terms "inner circle", "outer periphery", "radius" and "radial" are used with reference to the rotation axis L. Further, it should be noted that, in the present specification, the term "radial" or "radius" does not necessarily mean that the object 20 is circular. These terms are to be understood as the concept of "a prescribed direction orthogonal to the rotation axis L, or a line extending along the direction".

In the present embodiment, not only the radiation camera 4 is tilted, but also the angle (the above-described acute angle) formed by the rotation axis L and the input surface 11a of the radiation camera 4 is set in accordance with the Distance between the radiation source 2 and the imaging plane P in the Object 20, that is, FOD (Focus-Object Distance). Hereinafter, the detailed description will be given with reference to fig. 3 and 4.

Referring to fig. 3, for FDD on the inner peripheral side_inFDD suitable for outer peripheral part thereof as reference_outAnd calculation of the inclination θ of the radiation camera 4 will be explained. Here, FDD (Focus-Detector Distance) is the Distance between the radiation source 2 and the input surface 11a of the radiation camera 4, and subscripts "in" and "out" respectively refer to an "inner peripheral portion" and an "outer peripheral portion". First, when the radiation camera 4 as the TDI camera is driven at an arbitrary linear velocity, the transport speed adapted to the linear velocity is inversely proportional to the X-ray geometric magnification (i.e., magnification). Magnification M in the inner periphery_inAnd magnification M in the outer peripheral portion_outRepresented by the following formulae (1) and (2).

[ formula 1]

[ formula 2]

Here, if the relationship of the following expression (3) is established, the focus is made on both the inner peripheral portion and the outer peripheral portion.

[ formula 3]

From the expressions (1), (2) and (3), and the relational expression (4) between the angular velocity ω and the tangential velocity v (see fig. 4), the expression (5) can be derived.

[ formula 4]

[ formula 5]

If the radiation camera 4 is tilted to adjust FDD so as to satisfy the equation (5), the focus is made on both the inner peripheral portion and the outer peripheral portion. The expression (4) is derived from the following expressions (6) and (7) (see also fig. 4). The FOD can be adjusted by changing the ratio of the linear velocity of the radiation camera 4 and the rotational velocity of the rotary stage 6.

[ formula 6]

[ formula 7]

v＝rω[m/s]...(7)

Then, when the winding thickness w of the roll is determined as in the formula (8), the FDD of the inner peripheral portion_inFDD suitable for outer peripheral part thereof as reference_outAnd the inclination θ of the radiation camera 4 are calculated as the following equations (9) to (11). The inclination θ can also be said to be an angle formed by a plane perpendicular to the rotation axis L and the input surface 11a of the radiation camera 4.

[ formula 8]

w＝r_out-r_in...(8)

[ formula 9]

[ formula 10]

[ formula 11]

In this way, in the present embodiment, the angle β formed by the rotation axis L and the input surface 11a of the radiation camera 4 is set in accordance with FOD (Focus-Object Distance) which is the Distance between the radiation source 2 and the imaging plane P in the Object 20. Further, it is obvious that the angle β is pi/2-angle θ. Basically, since the moving speed of the image on the image sensor 13 also becomes n times when the magnification becomes n times, the TDI control speed (charge transfer speed) also becomes n times. In consideration of the actual magnification, the inclination angle θ needs to be set to 20 ° to 30 °.

Next, the operation of the image acquisition system 1, that is, a method of acquiring a radiation image will be described with reference to fig. 5 and 6. First, the object 20 such as a chip capacitor wound in a roll shape is attached to the rotary table 6 and held by the rotary table 6. Next, as shown in fig. 6, FOD is determined (step S01). The FOD may be determined based on the desired magnification.

Next, the table elevation control part 17 drives the table elevator 7 in accordance with the FOD, and moves the rotary table 6 in the rotation axis L direction (step S02 (moving step)). Next, the object 20 is rotated at a predetermined speed around the rotation axis L using the rotary platform 6 (step S03 (rotation step)). Next, radiation is output/irradiated from the radiation source 2 to the rotating object 20 (step S04 (radiation output step)). The radiation transmitted through the roller portion 21 of the object 20 is input to the input surface 11 a.

Next, the radiation camera 4 performs TDI control in the image sensor 13 in synchronization with the rotation speed of the object 20 obtained by the rotation stage 6 (step S05). That is, the image sensor 13 is driven at a speed synchronized with the rotational speed of the roller. Then, the radiation camera 4 images the imaging surface (step S06), and outputs image data (step S07) (steps S05 to S07 (radiation imaging step)). The image processing apparatus 10 inputs the image data output from the radiation camera 4, and generates a radiation image on the imaging plane P of the object 20 (step S08 (image generating step)).

Through the above series of processing, a radiation image of the imaging plane P is acquired. According to the image acquisition system 1 and the image acquisition method of the present embodiment, the image is acquired in synchronization with the rotation speed of the object 20 obtained by the rotation platform 6TDI control in sensor 13. In the imaging plane P of the object 20, the speed of the inner peripheral portion (portion closest to the rotation axis) is slower than the speed of the outer peripheral portion (portion farthest from the rotation axis). An angle β that is an acute angle is formed between the rotation axis L of the rotary stage 6 and the incident surface 11a of the radiation camera 4. Therefore, the distance FDD between the radiation source 2 and the portion of the input surface 11a through which radiation is input and transmitted through the inner peripheral portion_inA distance FDD from the radiation source 2 to the portion of the input surface 11a through which the radiation transmitted through the outer peripheral portion is input_outLong (see fig. 3). This means that the magnification in the inner peripheral portion is larger than that in the outer peripheral portion (refer to equations (1) and (2)). The transport speed in TDI control, which is adapted to a predetermined linear velocity, is inversely proportional to the magnification. The influence of the speed difference between the inner peripheral portion and the outer peripheral portion is mitigated by the magnitude relation of the magnification. Further, an angle formed by the rotation axis L of the rotary platform 6 and the incident surface 11a of the radiation camera 4 is set in accordance with FOD which is a distance between the radiation source 2 and the imaging plane P in the object 20, so that the ratio of the magnification becomes the reciprocal of the velocity ratio in the inner peripheral portion and the outer peripheral portion, and focusing is possible. As a result, focusing can be performed at any portion between the inner peripheral portion and the outer peripheral portion. Therefore, a sharp radiographic image can be obtained for any portion in the radial direction of the object 20.

Here, the image acquisition method may further include a step of moving the rotating table 6 in the direction of the rotation axis L to move the object 20 closer to or away from the radiation source 2. For example, after the above steps S01 to S08 are completed, the object 20 may be moved in the direction of the rotation axis L (step S02). As shown in fig. 5 (a), in the first generation of the image, the imaging plane P is set near the lower surface of the roller portion 21. Therefore, as shown in fig. 5 (b), the rotary table 6 is lowered by 1/4 (1/n: n is a natural number) corresponding to the thickness in the direction of the rotation axis L. This makes it possible to move the imaging plane P from the lower surface of the roller portion 21 to about 1/4 mm thick, and to obtain a sharp radiographic image of the imaging plane P. Similarly, as shown in fig. 5 (c) and 5 (d), the position of the imaging plane P can be raised in stages by lowering the rotary platform 6.

According to this step, the distance between the radiation source 2 and the object 20 can be adjusted. In other words, the imaging plane P based on the above-described FOD can be set at an arbitrary position in the direction of the rotation axis L of the object 20 (i.e., in the thickness direction). In this case, if the radiation source 2 is stationary, FOD is regarded as constant. A radiation image of an arbitrary position in the thickness direction of the object 20 can be acquired.

A radiographic image of the object 20 can be acquired by the radiation camera 4 including the scintillator 11 having the input surface 11a and the image sensor 13 that captures scintillation light emitted by the scintillator 11 in response to input of radiation.

In the image acquisition method using the image acquisition system 1, for example, in a stage in which the input of the first parameters (FOD and the like) is completed, the image processing apparatus 10, the timing control unit 16, the stage elevation control unit 17, and the display device 15 are set so that the above-described steps S02 to S08 are automatically performed. Further, after one radiographic image is acquired for a certain imaging plane P, the stage elevation control unit 17 may perform 1/n movement to acquire a radiographic image for the next imaging plane P. By acquiring radiation images at different positions in the thickness direction, information on, for example, a foreign object to be found (position information in the radial direction or the thickness direction, etc.) can be fed back to the manufacturing process.

A modification of the first embodiment will be described with reference to fig. 7. As shown in fig. 7, the table lifter 7 and the table elevation control unit 17 may be omitted, and instead, the image acquisition system 1A including a mechanism for raising and lowering (moving in the direction of the rotation axis L) the radiation generating apparatus 3 (radiation source 2) may be provided. In fig. 7, the elevation mechanism of the radiation generating apparatus 3 is not shown. The image processing apparatus 10, the display device 15, and the timing control unit 16 are not illustrated (this is the same in fig. 10 and 11 described below).

Even with such an image acquisition system 1A, the inclination θ of the radiation camera 4 corresponding to the FOD can be calculated by the following expression (12).

[ formula 12]

Next, an image acquisition system 1B according to a second embodiment will be described with reference to fig. 8 and 9. The image acquisition system 1B is different from the image acquisition system 1 of the first embodiment in that the stage lifter 7 and the stage lifter controller 17 are omitted, and instead, a rotation mechanism 18 and an angle adjuster 19 configured to adjust the angle formed by the rotation axis L of the rotation stage 6 and the input surface 11a of the radiation camera 4 by rotating the radiation camera 4 are provided. The rotation mechanism 18 includes a rotation shaft 18a coupled to the radiation camera 4, and has a motor, a gear, and the like, not shown, to rotate the radiation camera 4. The rotation mechanism 18 holds the radiation camera 4 such that the input surface 11a of the radiation camera 4 is inclined with respect to the rotation axis L. The rotation axis 18a of the rotation mechanism 18 may also be perpendicular to an imaginary plane including the rotation axis L and the radiation source 2.

As shown in fig. 9, the image acquisition method using the image acquisition system 1B is different from the image acquisition method using the image acquisition system 1 in that, before the determination of the FOD (step S01), FDD is determined (step S10), the object 20 is set by the FDD (step S11), then, after the determination of the FOD (step S01), the inclination angle θ is calculated based on the FDD, the FOD, and the winding thickness w (step S12, see equations (11) and (12)), and the angle of the radiation camera 4 is adjusted by controlling the rotation mechanism 18 by the angle adjuster 19 so as to be the inclination angle θ (step S13 (adjustment step)). The movement of the stage in the image acquisition system 1 is not performed (step S02, see fig. 6).

The image acquisition system 1B also has the same operation and effects as those of the image acquisition systems 1 and 1A described above. In addition, by the angle adjusting step, the angle formed by the rotation axis L of the rotation platform 6 and the input surface 11a of the radiation camera 4 can be adjusted to an appropriate angle corresponding to the FOD.

In the angle adjustment step, the angle formed by the rotation axis L of the rotation platform 6 and the input surface 11a of the radiation camera 4 is adjusted in accordance with FOD, which is the distance between the radiation source 2 and the imaging plane P in the object 20, and therefore, focusing can be performed on any FOD.

In the step of adjusting the angle, since the radiation camera 4 is rotated so that the input surface 11a of the radiation camera 4 is inclined with respect to the rotation axis L, the posture of the radiation camera 4 can be adjusted, and the angle formed by the rotation axis L of the rotating table 6 and the input surface 11a of the radiation camera 4 can be adjusted to an appropriate angle corresponding to the FOD.

Next, an image acquisition system 1C according to a third embodiment will be described with reference to fig. 10 and 11. The image acquisition system 1C differs from the image acquisition system 1 of the first embodiment in that the platform lift 7 and the platform lift control unit 17 are omitted; tilting the rotary platform 6 and the object 20 so that the extension of the boundary surface 23 does not pass through the radiation source 2; and the radiation camera 4 is disposed so that an end edge (optical axis) of the radiation beam 2a corresponding to the inner peripheral portion of the imaging plane P is orthogonal to the input surface 11a of the radiation camera 4.

In the image acquisition system 1C, the inclination angle θ of the object 20 can be calculated by the following equation (13) as in the above equations (1) to (5). In the image acquisition system 1C, it is obvious that the angle β formed by the rotation axis L and the input surface 11a is a relationship of pi/2 — angle θ.

[ formula 13]

Note that the same mechanisms as the rotating mechanism 18 and the angle adjusting unit 19 in the image acquisition system 1B described above may be applied to the rotating platform 6 of the image acquisition system 1C. In this case, the posture of the rotary platform 6 can be adjusted, and the angle formed by the rotation axis L of the rotary platform 6 and the input surface 11a of the radiation camera 4 can be adjusted to an appropriate angle corresponding to the FOD.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For example, in the above-described embodiment, the radiation camera 4 is described as an indirect conversion type camera in which the FOP12 with the scintillator 11 attached is coupled to the image sensor 13, but the radiation camera is not limited to this embodiment. For example, the FOP12 may be omitted, and an indirect conversion type radiation camera in which the scintillator 11 is coupled to the image sensor 13 may be used. In this case, the input surface 11a of the scintillator 11 is an input surface of the radiation camera, and serves as a reference of the above-described angle. Further, a direct conversion type radiation camera constituted only by the image sensor 13 may be employed. In this case, the light receiving surface 13a of the image sensor 13 is an input surface of the radiation camera, and serves as a reference of the above-described angle. Even in a direct conversion type radiation camera, TDI control can be performed by the image sensor 13. Further, a direct conversion type radiation camera in which FOP is coupled to the image sensor 13 may be used. In this case, the surface of the FOP is an input surface of the radiation camera, and serves as a reference of the above-described angle. Even when these direct conversion type radiation image sensors are used, a sharp radiation image of the object can be obtained.

The angle formed by the rotation axis L of the rotary platform 6 and the incident surface 11a of the radiation camera 4 may be set according to FOD, and does not necessarily correspond to the above equations (11), (12), and (13). Even at angles slightly different from the above-described equations (11), (12), and (13), a sharp radiographic image can be obtained for any radial portion. Further, not limited to the image acquisition system in which the rotary table 6 or the radiation camera 4 is rotatable, as one embodiment of the present invention, an image acquisition system in which the rotary table 6 or the radiation camera 4 is fixed at an angle "set according to FOD" and thereafter the angle adjustment is not possible may be provided.

Further, a configuration may be adopted in which both the rotation table 6 and the radiation camera 4 can be angularly adjusted. Further, in the case of tilting the rotation platform 6, the radiation camera 4 needs to be tilted more.

An image acquisition system in which any two or more of the above-described embodiments are combined may be provided. For example, an image acquisition system may be provided in which any two or more of the inclination of the radiation camera in the image acquisition system 1 and the elevation of the rotating platform 6, the elevation of the radiation generating apparatus 3 in the image acquisition system 1A, the rotation (angle adjustment) of the radiation camera 4 in the image acquisition system 1B, and the inclination of the rotating platform 6 and the object 20 in the image acquisition system 1C are combined.

(test examples)

In order to verify the effect of the image acquisition system 1 according to the first embodiment, a simulation was performed. Assuming that the radius of the inner peripheral portion is r_in120mm, and a radius of the outer peripheral portion of r_out150 mm. As shown in fig. 12, the velocity ratio of the foreign matter No. 2 (indicated by the symbol F2) located at the center in the winding thickness direction is 1.125 times, and the velocity ratio of the foreign matter No. 3 (indicated by the symbol F3) located at the outer periphery is 1.25, based on the foreign matter No. 1 (indicated by the symbol F1) located at the inner periphery.

As comparative example 1, simulation was performed under the condition that the radiation camera 4 was not tilted, that is, under the condition that the input surface 11a of the radiation camera 4 was orthogonal to the rotation axis L in the image acquisition system 1. As comparative example 2, the simulation was performed under the condition that the radiation camera 4 was tilted and the input surface 11a of the radiation camera 4 was at an acute angle with respect to the rotation axis L, but was about half of an appropriate angle corresponding to FOD. In comparative examples 1 and 2, the TDI transfer rate was set so as to match the transport rate of the foreign matter No. 1 in the inner peripheral portion. The embodiment performs the simulation under the condition that the input face 11a of the radiation camera 4 is at an acute angle with respect to the rotation axis L and is at an appropriate angle corresponding to FOD. Further, the inclination angle in the example was about 34 °, and the inclination angle in comparative example 2 was about 17 °. The simulation conditions were FDD: 300mm, FOD: 100 mm. The simulation results of comparative example 1, comparative example 2, and example are shown in fig. 13, 14, and 15, respectively. In each figure, the conveying direction D is also shown.

As shown in fig. 13, the radiographic image of the foreign matter No. 1 is sharp without tilting the radiation camera 4, but the foreign matters No. 2 and No. 3 become blurred images in the conveyance direction D due to the speed mismatch, and the contrast deteriorates. Further, as shown in fig. 14, even when the radiation camera 4 is tilted but the angle is not appropriate, the speeds of No. 2 and No. 3 are not matched with each other with respect to the foreign matter, and therefore, a blurred image is formed in the transport direction D, and the contrast is deteriorated.

As shown in fig. 15, in the case where the radiation camera 4 is tilted and an appropriate angle corresponding to FOD is set, it is possible to absorb a speed difference (speed ratio) and image an object without blurring at all positions in the radial direction.

Industrial applicability of the invention

According to some aspects of the present invention, a sharp radiographic image can be acquired for any radial portion of the object.

Description of the symbols

1 … … image acquisition system; 2 … … radiation source; 3 … … a radiation generating device; 4 … … radiation camera; 6 … … rotating platform; 7 … … landing elevator; 10 … … image processing means; 11 … … scintillator; 11a … … input face; 13 … … image sensor; 13a … … a light receiving surface; 15 … … display device; 16 … … timing control part; 17 … … a platform elevation control part (platform movement control part); 20 … … target object; 21 … … roller part; 22 … … wheel portion; 23 … … boundary surface; the L … … axis of rotation; p … … image pickup surface.