JPH05157708A - Laminograph - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a laminograph in which a tomographic image can be obtained only by focusing on a focusing surface without using a focus scanning X-ray tube and by a simple image addition process. [Structure] While the subject 3 and the X-ray detector 4 are revolved around the revolution axis 13 in synchronization, the X-rays from the X-ray tube 1 are emitted toward the subject 3 and transmitted through the subject 3. X-rays are detected by the X-ray detector 4, and the detected transmission images of the subject 3 are added by the image adding device 9 and displayed on the image display device 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminograph, which is a tomographic apparatus for detecting radiation that has passed through an object to obtain a tomographic image of the object, and more particularly to the inside of an object such as a multilayer wiring board. Non-destructive inspection of laminographs.

[0002]

2. Description of the Related Art This type of laminograph has recently started to be noticed as one that can be used for inspecting a pattern of an internal layer of a multilayer wiring board or the like, and is basically popularized for medical purposes. Although it is the same as the tomography device used in the present invention, a tomographic image obtains a tomographic image that is a transmission image in which one surface is in focus using an X-ray film, whereas a laminograph uses a surface sensor output as a digital image. The difference is that a tomographic image is created by image processing.

FIG. 7 is a diagram showing a conventional laminograph, which is described in Japanese Patent Publication No. 2-501411.
In the figure, the focus is scanned circularly by the focus scanning X-ray tube 91. The rotary X-ray detector 94, which is a two-dimensional surface sensor, rotates in synchronization with the focal point, and a large number of transmission images transmitted through the subject 92 during the rotation are added by digital processing to obtain one tomographic image. Created. The tomographic image is determined by the turning radius of the focus and the turning radius of the rotation detector 94.
The image is focused on one focal plane 93.

FIG. 8 shows "Industry's New Vision" Bio-Im.
It is a figure which shows the conventional laminograph described in aging Research, Inc. issue page 6. In the figure, a subject 97 is provided in a pyramidal X-ray beam 96 emitted from an X-ray tube 95, and a two-dimensional X-ray detector 98 is provided behind it. The subject 97 is reciprocally rotated as indicated by an arrow with respect to one rotation axis O parallel to the detector 98, and transmission image data is collected during this period. A cross-sectional image in focus on one focal plane E is created from a large number of transmission image data by expansion / contraction processing and addition processing. Further, by changing the parameter of the expansion / contraction process from the same collected transmission image group, it is possible to create a sectional image in focus on any other focused surface F.

[0005]

In the conventional laminograph described above, since the focus scanning X-ray tube is used, the focus position is apt to deviate from the determined trajectory, and the image is often unclear. There is a problem that it becomes expensive.

Further, since the diameter of the focus scan cannot be made too large due to the restriction of the X-ray tube, there is a problem that the depth of focus of the tomographic photograph cannot be made shallow and the pattern out of the focus plane cannot be sufficiently blurred.

Further, since the pattern blur on the surface deviating from the focus surface is in one direction, there is a problem that the linear pattern orthogonal to the rotation axis is not blurred and is easily confused with the focus surface pattern. Further, since complicated processing such as image expansion / contraction processing is performed at the time of image addition, it takes a long processing time, requires an expensive computer, and is uneconomical.

The present invention has been made in view of the above,
It is an object of the present invention to provide a laminograph in which only a focus plane is well focused without using a focus scanning X-ray tube and a tomographic image can be obtained only by a simple image addition process.

[0009]

In order to achieve the above object, the laminograph of the present invention comprises a radiation source that generates radiation and emits it toward a subject, and a planar surface for detecting the radiation that has passed through the subject. A radiation surface detector, detector revolving means for revolving the radiation surface detector around a predetermined axis, and an object for revolving the subject around the axis in synchronization with the radiation surface detector. The gist of the present invention is to have a specimen revolving means, an image adding means for adding the transmission images of the object detected by the radiation surface detector, and a display means for displaying the image data from the image adding means.

Further, the laminograph of the present invention includes a radiation source that generates radiation and emits it toward a subject, a radiation surface detector provided in a plane for detecting the radiation transmitted through the subject, A rotation unit that rotates the sample and the radiation surface detector in synchronization with each other about their respective rotation axes that are parallel to each other, and an image addition unit that adds transmission images of the subject detected by the radiation surface detector. The gist is to have a display means for displaying the image data from the image addition means.

Further, the laminograph of the present invention comprises a radiation source which generates radiation and emits it toward a subject, a radiation surface detector provided in a plane for detecting the radiation transmitted through the subject, Rotating means for rotating the sample and the radiation surface detector in synchronization with each other about their respective rotation axes that are parallel to each other, and a common revolving axis that is fixed to the subject and the radiation surface detector. Revolution means for revolving the subject and the radiation surface detector so as to revolve in synchronization with the axis, image adding means for adding transmission images of the subject detected by the radiation surface detector, and the image The gist is to have a display means for displaying the image data from the addition means.

[0012]

In the laminograph of the present invention, while the object and the radiation surface detector are revolved around the predetermined axis in synchronism with each other, the radiation is emitted toward the object and the radiation transmitted through the object is detected. The transmission images of the detected subject are added and displayed.

Further, in the laminograph of the present invention, while the subject and the radiation surface detector are rotated about the rotation axes parallel to each other in synchronization with each other, the radiation is emitted toward the subject and transmitted through the subject. Radiation is detected by the radiation surface detector, and the detected transmission images of the subject are added and displayed.

Further, in the laminograph of the present invention, the subject and the radiation surface detector are caused to rotate in synchronization with each other about their respective rotation axes parallel to each other, and at the same time, fixed to the subject and the radiation surface detector respectively. While rotating the subject and the radiation surface detector so that the rotation axis is revolved in synchronism with the common revolution axis, the radiation is emitted toward the subject and the radiation that passes through the subject is emitted. Detected by the detector, the detected transmission images of the subject are added and displayed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

1 (a) and 1 (b) are a side view and a plan view, respectively, showing the structure of a laminograph according to an embodiment of the present invention. As shown in both figures, the laminograph of the present embodiment has an X-ray tube 1 for emitting an X-ray beam 2 toward a subject 3 below, and the X-ray tube 1 is controlled by an X-ray controller 6. Has been done. The subject 3 is provided on the upper part of the revolution mechanism 5, and an X-ray detector 4 is attached near the lower part of the revolution mechanism 5, whereby the subject 3 and the X-ray detector 4 are shared by the revolution mechanism 5. It is configured to revolve around the revolution axis 13 of. In this case, the subject 3 and the X-ray detector 4 do not rotate. Also,
The revolution mechanism 5 is controlled by a mechanism controller 7.

The X-ray detector 4 is a two-dimensional surface sensor,
The X-ray intensity distribution on the detection surface of the X-ray detector 4 can be detected with spatial resolution. The X-ray detector 4 may be of a commonly used image pickup tube type. This type of X-ray detector 4 detects on the principle that charges charged on the detection surface in proportion to the X-ray dose are scanned and read with an electron beam.

The X-ray detector 4 is connected to a detector controller 8, the electron beam is controlled by the detector controller 8, and the detection output signal from the X-ray detector 4 is amplified. There is. The detection output signal from the X-ray detector 4 amplified by the detector controller 8 is supplied to the image addition device 9 as a video signal. The image addition device 9 receives one scan of the detection output of the X-ray detector 4, converts it into a digital signal, and forms a digital image.
Then, the detection output signals sent one after another are sequentially converted into digital images, and the digital image signals are arithmetically averaged to generate an average image, which is stored in the internal memory.

The image information stored in the internal memory of the image adding device 9 is supplied to the image display device 10 which is a normal CRT display and is displayed on the image display device 10.

The operation of the laminograph configured as described above will be described with reference to the geometrical relationship shown in FIG.

The subject 3 and the X-ray detector 4 revolve around the common revolution axis 13 with revolution radii R1 and R2, respectively. As described above, in this case, the rotation is not performed. The detection surface 12 of the X-ray detector 4 is set perpendicular to the revolution axis 13.

The X-ray focal point S of the X-ray tube 1 is set at a position on the revolution axis 13 and at a distance L2 from the detection surface 12. As a result, the focus surface 11 is formed at the position of the distance L1 from the X-ray focal point S such that L1: L2 = R1: R2. As can be seen from FIG. 2, the focus surface 11 is perpendicular to the revolution axis 13, and the X-ray beam passing through one point in the focus surface 11 of the subject 3 always hits the same point on the detection surface 12 during the revolution. Is becoming The intersection of the X-ray beam passing through a point above or below the focus plane 11 and the detection plane 12 moves on a small circle on the detection plane 12 during revolution.

As described above, the X generated from the X-ray tube 1
While radiating the rays toward the subject 3, the subject 3 and the X-ray detector 4 are continuously revolved by the revolution mechanism 5, and the X-rays transmitted through the subject 3 are detected by the X-ray detector 4. ,
In this case, the detector controller 8 scans one screen in a cycle sufficiently shorter than the revolution cycle, and the transmission image data of one screen is supplied to the image adding device 9 as a video signal. Scanning immediately shifts to the scanning of the next screen after the end of one screen,
Video signals are successively supplied to the image adding device 9 one after another. The image adding device 9 converts the image information continuously supplied one after another into a digital signal to form a digital image, and stores it in an internal memory. Then, the stored image information is constantly displayed on the image display device 10.

When the addition start button is operated, the image addition device 9 updates the internal memory while successively digitizing the image information supplied one after another and adding and averaging them. Then, when the revolution is rotated once, the addition is stopped, and the image display device 10 displays a transmission image (tomographic image) of the subject in focus on the focus surface 11.

In the present embodiment, at the time of image addition processing, the orbit and the scan are combined to shift the image into a circle (that is,
It is also possible to shift the focus plane by performing addition processing while revolving the image with respect to one point.

3 (a) and 3 (b) are a side view and a plan view, respectively, showing the structure of a laminograph according to another embodiment of the present invention. The laminograph of this embodiment shown in both figures shows the same X-ray tube 1 as in the embodiment shown in FIG.
The subject 3, the X-ray detector 4, the X-ray control device 6, the detector controller 8, the image addition device 9, and the image display device 10 are provided, but the subject 3 and the X-ray detector 4 are replaced by an X-ray tube. 1 is tilted at a predetermined angle with respect to the central axis 23, and the central axes of the subject 3 and the X-ray detector 4 are rotation axes 14 and 15, respectively. The line detector 4 is configured to rotate, and the rotation mechanism 25 and the mechanism control device 27 are provided in place of the revolution mechanism 5 and the mechanism control device 7 for this rotation. The elements and configuration are the same as shown in FIG. The rotation axes 14 and 15 of the subject 3 and the X-ray detector 4 are set to be parallel to each other, and are kept parallel to each other during scanning so as to rotate in synchronization with each other.

The operation of the laminograph shown in FIG. 3 constructed as above will be described with reference to the geometrical relationship shown in FIG. 4 (a) and 4 (b) respectively show geometrical relations in rotation with different rotation scanning.

The X-ray focal point S is set on the plane formed by the two rotation axes 14 and 15. The point where the detection surface 12 on the X-ray detector 4 and the rotation axis 15 of the X-ray detector 4 intersect is O ′.
Then, the intersection of the center line 23 connecting the point O ′ and the X-ray focal point S and the rotation axis 14 of the subject 3 is defined as O. Then, a plane that passes through the point O and is parallel to the detection plane 12 becomes the focusing plane 11. That is, 1 fixed to the subject 3 within the focus surface 11
The projection of the point A is always the same point A ′ on the detection surface 12 during scanning.
It is supposed to hit. Points above or below the focus plane 11 move over a small circle on the sensing plane 12 during scanning.

While radiating the X-ray generated from the X-ray tube 1 toward the subject 3, the subject 3 and the X-ray detector 4 are continuously rotated in synchronization with each other by the rotation mechanism 25, and the X-ray detector The X-rays transmitted through the subject 3 are detected by the detector 4. In this case, the detector controller 8 scans one screen in a cycle sufficiently shorter than the rotation cycle, and the transmission image data of one screen is converted into a video signal. It is supplied to the adder 9. The scanning immediately shifts to the scanning of the next screen after the completion of one screen, and the video signals are successively supplied to the image adding device 9. The image adding device 9 converts the image information continuously supplied one after another into a digital signal to form a digital image, and stores it in an internal memory. Then, the stored image information is constantly displayed on the image display device 10.

When the addition start button is operated, the image adding device 9 updates the internal memory while digitalizing the image information supplied one after another and averaging them. Then, when the rotation is rotated once, the addition is stopped, and the image display device 10 displays a transmission image (tomographic image) of the subject in focus on the focus surface 11.

In this embodiment, since only the rotation is performed, the direction in which X-rays are incident on the subject can be greatly changed, the depth of focus can be made shallow, and the blurring of the pattern deviated from the focus surface can be increased, and only the focus surface can be made. A well-focused tomographic image can be obtained. Further, since only the rotation is performed, the X-ray beam can be always used at the position where the X-ray intensity is strong in front of the X-ray tube, and the image quality is improved.

FIGS. 5 (a) and 5 (b) are a side view and a plan view, respectively, showing the structure of a laminograph according to still another embodiment of the present invention. The laminographs of the present embodiment shown in both of the drawings are similar to those of the embodiment shown in FIG. 1 and the embodiment shown in FIG. 3, and are configured to rotate and revolve. And the same X-ray tube 1, subject 3, X-ray detector 4, X as in the embodiment shown in FIG.
Although it has a line control device 6, a detector controller 8, an image addition device 9, and an image display device 10, the subject 3
The X-ray detector 4 and the X-ray detector 4 are tilted at a predetermined angle with respect to the revolution axis 13 from the X-ray tube 1, and the subject 3 and the X-ray detector 4 are rotated about the rotation axes 14 and 15, respectively, and the subject is examined. 3 and the X-ray detector 4 are configured to revolve around the revolution shaft 13, and only a revolution rotation mechanism 35 and a mechanism control device 37 are provided for this rotation and revolution, and other The elements and configuration are the same as shown in FIGS. It should be noted that the rotation axes 14 and 15 of the subject 3 and the X-ray detector 4 are set parallel to each other as in the case of FIG. 3, and are configured to be kept parallel during scanning and to rotate in synchronization with each other. There is.

The operation of the laminograph shown in FIG. 5 constructed in this way will be described with reference to the geometrical relationship shown in FIG. 6 (a) and 6 (b) respectively show the geometrical relationships in the different rotations of the revolution rotation scan.

The revolution shaft 13 is set so as to intersect the revolution shafts 14 and 15 at revolutions O and O ', respectively, and is fixed to the subject 3 and the X-ray detector 4, respectively.
The subject 3 and the X-ray detector 4 are configured to revolve in synchronization with each other so as to rotate the revolving shafts 4 and 15 around the revolution axis 13. The X-ray focal point S is set almost on the revolution axis 13. The detection surface 12 of the X-ray detector 4 is set so as to pass the point O ′ and be substantially orthogonal to the rotation axis 15. Also, X
Seen from the line focus side, the rotation rotates counterclockwise and the revolution rotates clockwise in the same cycle.

In the scanning as described above, the plane that passes through the point O and is parallel to the detection surface 12 becomes the focus surface 11. That is, the projection of one point A fixed on the subject 3 in the focus surface 11 always hits the same point A ′ on the detection surface 12 during scanning. Points above or below the focus plane 11 move over a small circle on the sensing plane 12 during scanning.

While the X-ray generated from the X-ray tube 1 is radiated toward the subject 3, while the subject 3 and the X-ray detector 4 are synchronized by the revolution rotation mechanism 35, the revolution and the rotation are continuously the same. X-ray detector 4
The X-ray transmitted through the subject 3 is detected by the detector 3. In this case, the detector controller 8 scans one screen in a cycle sufficiently shorter than the revolution and rotation cycles, and the transmission image data of one screen is converted into a video signal. It is supplied to the image addition device 9. Scanning immediately shifts to the scanning of the next screen after the end of one screen,
Video signals are successively supplied to the image adding device 9 one after another. The image adding device 9 converts the image information continuously supplied one after another into a digital signal to form a digital image, and stores it in an internal memory. Then, the stored image information is constantly displayed on the image display device 10.

When the addition start button is operated, the image addition device 9 updates the internal memory while digitalizing the image information supplied one after another and averaging them. Then, when the revolution and the rotation are rotated once, the addition is stopped and the image display device 10 displays a transmission image (tomographic image) of the subject in focus on the focus surface 11.

In the present embodiment, since the orbital rotation and the rotation (misorienting motion) are performed, the direction in which the X-rays are incident on the subject can be greatly changed, the depth of focus can be made shallow, and the blur of the pattern deviated from the focus surface can be increased. It is possible to obtain a tomographic image that is well focused only on the focus surface. Further, since it revolves around the axis and rotates, the X-ray beam can always be used at the position where the X-ray intensity is strong in front of the X-ray tube, and the image quality is improved.

In each of the above-mentioned embodiments, since the circular scanning is used, the patterns of the upper layer and the lower layer of the focus surface are blurred in all directions, and a tomographic image with good focus only on the focus surface can be obtained. Further, there is no need to use a focus scanning X-ray tube as in the conventional case.

Further, in the present embodiment, since the image processing is only the simple image averaging, the processing device is fast and inexpensive. Further, since the heavy X-ray tube is not used for scanning and only the light subject and the X-ray detector need be scanned, the structure of the mechanical section is relatively simple.

Further, in this embodiment, an X-ray detector (image pickup tube) is used.
Even if there is distortion in the image obtained in step 1, there is no problem, so a good tomographic image can be obtained. The X-ray detector 4 is X
Other surface sensors such as a line image intensifier (II) + television camera or scintillator + CCD light surface sensor can be used.

[0042]

As described above, according to the present invention,
The subject and radiation surface detector are revolved in synchronism around a predetermined axis, are rotated in synchronism with each other in parallel with each other about rotation axes that are parallel to each other, or are synchronized with each other about respective rotation axes that are parallel to each other. At the same time as rotating the object and the radiation surface detector, while revolving the object and the radiation surface detector so as to revolve the rotation axis fixed to the object and the radiation surface detector in synchronization with the common revolution axis, Radiation is directed toward the subject, the radiation transmitted through the subject is detected by a radiation surface detector, and the transmitted images of the detected subject are added and displayed. Therefore, conventional focus scanning X-rays are used. It is possible to obtain a tomographic image in which only the focus surface is well focused without using a tube by a simple image addition process.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a laminograph according to an embodiment of the present invention.

FIG. 2 is a diagram showing a geometrical arrangement of the laminograph shown in FIG.

FIG. 3 is a configuration diagram of a laminograph according to another embodiment of the present invention.

FIG. 4 is a diagram showing a geometrical arrangement of the laminograph shown in FIG.

FIG. 5 is a configuration diagram of a laminograph according to still another embodiment of the present invention.

6 is a diagram showing the geometrical arrangement of the laminograph shown in FIG.

FIG. 7 is an explanatory diagram showing a conventional laminograph.

FIG. 8 is an explanatory diagram showing another conventional laminograph.

[Explanation of symbols]

 1 X-ray tube 2 X-ray beam 3 Subject 4 X-ray detector 5 Revolution mechanism 6 X-ray control device 7, 27, 37 Mechanism control device 8 Detector controller 9 Image addition device 10 Image display device 25 Rotation mechanism device 35 Revolution Rotation mechanism

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[Procedure amendment]

[Submission date] April 10, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

FIG. 7 is a diagram showing a conventional laminograph, the details of which are described in Japanese Patent Publication No. 2-501411. In the figure, the focus is scanned circularly by the focus scanning X-ray tube 91. The rotary X-ray detector 94, which is a two-dimensional surface sensor, rotates in synchronization with the focal point, and a large number of transmission images transmitted through the subject 92 during the rotation are added by digital processing to obtain one tomographic image. Created. The tomographic image is an image in focus on one focal plane 93 determined by the radius of rotation of the focus and the radius of rotation of the rotation detector 94.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

The operation of the laminograph shown in FIG. 5 constructed in this way will be described with reference to the geometrical relationship shown in FIG. It should be noted that FIGS. 6A and 6B are different in the revolution rotation scanning.
It shows the geometrical relationship in the revolution .

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

The revolving shaft 13 and the revolving shafts 14 and 15 respectively.
The rotation axis 1 is set so as to intersect at the intersection points O and O ′, and is fixedly set to each of the subject 3 and the X-ray detector 4.
The subject 3 and the X-ray detector 4 are configured to revolve in synchronization with each other so as to rotate the revolving shafts 4 and 15 around the revolution axis 13. The X-ray focal point S is set almost on the revolution axis 13. The detection surface 12 of the X-ray detector 4 is set so as to pass the point O ′ and be substantially orthogonal to the rotation axis 15. Also, X
Seen from the line focus side, the rotation rotates counterclockwise and the revolution rotates clockwise in the same cycle.

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

Claims (3)

[Claims] 1. A radiation source that generates radiation and emits the radiation toward a subject, a radiation surface detector provided in a planar shape to detect the radiation that has passed through the subject, and the radiation surface detector is predetermined. Detector revolving means for revolving around the axis of, the object revolving means for revolving the object around the axis in synchronization with the radiation surface detector, and the object detected by the radiation surface detector A laminograph comprising: an image adding means for adding transparent images; and a display means for displaying image data from the image adding means. 2. A radiation source that generates radiation and emits the radiation toward a subject, a radiation surface detector provided in a planar shape to detect the radiation that has passed through the subject, the subject and the radiation surface detection. From the image adding means, and a rotation means for rotating the detectors in synchronism with each other about respective rotation axes parallel to each other, an image adding means for adding the transmission images of the subject detected by the radiation surface detector, A laminograph having a display unit for displaying image data. 3. A radiation source that generates radiation and emits it toward a subject, a radiation surface detector provided in a plane shape to detect the radiation that has passed through the subject, the subject and the radiation surface detection. Means for rotating the detectors around their respective rotation axes parallel to each other in synchronization with each other, and the rotation axes fixed respectively to the subject and the radiation surface detector in synchronization with a common revolution axis. Revolving means for revolving the subject and the radiation surface detector so as to revolve, an image adding means for adding transmission images of the subject detected by the radiation surface detector, and image data from the image adding means And a display means for displaying.