JP5584250B2 - Medical X-ray imaging system - Google Patents

Description

  The present invention relates to a medical X-ray imaging system.

  In X-ray imaging for medical use, in recent years, an X-ray imaging system using an X-ray imaging apparatus has been widely used instead of an X-ray photosensitive film. Such an X-ray imaging system does not require development like an X-ray photosensitive film, can be confirmed in real time and can be confirmed in real time, and is superior in terms of data storage and ease of handling. It has a point. In X-ray imaging for dental diagnosis, such an X-ray imaging system is being used in various imaging modes such as panorama, cephalo, and CT.

  For example, Patent Document 1 discloses an X-ray imaging apparatus for dental diagnosis that includes an X-ray generation unit and an X-ray detection unit. In this X-ray imaging apparatus, X-rays are irradiated through a narrow slit or a rectangular slit so that an X-ray slit beam and an X-ray wide-area beam can be selectively switched and generated. The X-ray slit beam is used for panoramic imaging, cephalometric imaging, and the like, and the X-ray wide-area beam is used for CT imaging and the like. And this patent document 1 describes image | photographing both the X-ray slit beam which passed the narrow groove-shaped slit, and the X-ray wide range beam which passed the rectangular slit with one solid-state image sensor. .

  As a solid-state imaging device used in such a medical X-ray imaging system, a device using CMOS technology is known, and among them, a passive pixel sensor (PPS) type is known. It has been. The PPS type solid-state imaging device includes a light receiving unit in which PPS pixels including photodiodes that generate an amount of electric charge corresponding to incident light intensity are two-dimensionally arranged in M rows and N columns, and light incident on each pixel. Accordingly, the charge generated in the photodiode is accumulated in the capacitive element in the integrating circuit, and a voltage value corresponding to the amount of accumulated charge is output.

  In general, the output ends of each of the M pixels in each column are connected to the input ends of the integration circuits provided corresponding to the columns via readout wirings provided corresponding to the columns. ing. Then, the charges generated in the photodiodes of each pixel are sequentially input from the first row to the M-th row for each row through the readout wiring corresponding to the corresponding column to the integration circuit. A voltage value corresponding to is output.

International Publication No. 2006/109808 Pamphlet

  In a solid-state imaging device used for medical X-ray imaging, for example, a row selection wiring arranged for each row of a light receiving unit from a scanning shift register or a readout wiring for reading out charges for each column is disconnected. Occasionally, an abnormal pixel may occur in the light receiving unit. When such pixels occur continuously in a row or column, the following inconvenience occurs. That is, when the column direction or the row direction of the light receiving unit and the moving direction of the solid-state imaging device are orthogonal, the continuous direction of abnormal pixels and the moving direction of the solid-state imaging device are parallel to each other. Therefore, in the reconstructed image obtained after the solid-state imaging device is photographed while turning around the subject, a portion corresponding to an abnormal pixel appears as a so-called artifact.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an X-ray imaging system capable of reducing artifacts in a reconstructed image.

A medical X-ray imaging system according to the present invention is a medical X-ray imaging system including a solid-state imaging device that captures an X-ray image while moving around a subject. The solid-state imaging device includes a photodiode. A light-receiving unit having a rectangular light-receiving surface in which M × N pixels (M and N are integers of 2 or more) each included are two-dimensionally arranged in M rows and N columns, and each column is arranged to correspond. The N readout wirings connected to the photodiodes included in the pixels of the column to be connected via the readout switch, and the voltage value corresponding to the amount of charge input through the readout wiring are held and held. The signal readout unit that sequentially outputs the voltage value and the opening / closing operation of the readout switch of each pixel are controlled, and the output operation of the voltage value in the signal readout unit is controlled to control the charge generated in the photodiode of each pixel. A voltage value according to the amount from the signal readout unit And a scintillator that generates scintillation light according to incident X-rays, converts the X-ray image into an optical image, and outputs the optical image to the light receiving unit. Both the row direction and the column direction of the light receiving unit are inclined with respect to the direction, the number of rows M in the light receiving unit is smaller than the number of columns N, and the shape of the light receiving surface is a rectangular shape whose longitudinal direction is the row direction, The direction along the diagonal line of the rectangle intersects with the moving direction of the solid-state imaging device, and the control unit selectively selects a voltage value from pixels constituting an imaging region having a predetermined direction as a longitudinal direction among the M × N pixels. The output operation of the signal reading unit is controlled such that the predetermined direction is inclined with respect to both the row direction and the column direction of the light receiving unit and intersects the moving direction of the solid-state imaging device. To do.

  In the medical X-ray imaging system according to the present invention, both the row direction and the column direction of the light receiving unit are inclined with respect to the moving direction of the solid-state imaging device. In this case, the continuous direction of abnormal pixels continuously generated in a row or column and the moving direction of the solid-state imaging device are inclined with respect to each other and are not parallel to each other. Therefore, when the solid-state imaging device is rotated and photographed around the subject, an image portion corresponding to a pixel that is not normal can be supplemented by subsequent frame data, and artifacts in the reconstructed image can be reduced. Is possible.

  In addition, this medical X-ray imaging system is characterized in that the number M of rows in the light receiving portion is smaller than the number N of columns, and the shape of the light receiving surface is a rectangular shape whose longitudinal direction is the row direction. In this medical X-ray imaging system, since the readout wiring is arranged for each column, the arrangement of the readout wiring and the short direction of the light receiving surface can be achieved by configuring the light receiving portion in this way. Will match. Accordingly, since the number of pixels (photodiodes) that are targets for reading out charges from the readout wiring in each frame can be reduced, the frame rate can be further increased.

The medical X-ray imaging system is a medical X-ray imaging system including a solid-state imaging device that captures an X-ray image while moving around a subject, and the solid-state imaging device includes a photodiode. A light receiving unit having a rectangular light receiving surface in which M × N pixels (M and N are integers of 2 or more) are two-dimensionally arranged in M rows and N columns, and corresponding columns are arranged. N readout wirings connected to the photodiodes included in the pixel via the readout switch, and a voltage value corresponding to the amount of charge input through the readout wiring is held, and the held voltage value Are controlled in order to control the output operation of the voltage value in the signal reading unit and the amount of charge generated in the photodiode of each pixel. The corresponding voltage value is output from the signal readout unit. And a scintillator that generates scintillation light in accordance with incident X-rays, converts the X-ray image into an optical image, and outputs the optical image to the light receiving unit, and the moving direction of the solid-state imaging device In contrast, both the row direction and the column direction of the light receiving portion are inclined, the number M of rows in the light receiving portion is smaller than the number N of columns, and the shape of the light receiving surface is a rectangular shape whose longitudinal direction is the row direction. The direction along the diagonal line intersects the moving direction of the solid-state imaging device, and after the voltage value of the pixel is read from the signal reading unit and stored as data, an imaging region having a predetermined direction as a longitudinal direction is formed. The image corresponding to the pixels is selectively used to form an image, and the predetermined direction is inclined with respect to both the row direction and the column direction of the light receiving unit and intersects with the moving direction of the solid-state imaging device. Features.

In the medical X-ray imaging system, when the output operation of the signal reading unit is controlled in this way, it is preferable that the predetermined direction is orthogonal to the moving direction of the solid-state imaging device, and the imaging region is the light receiving unit. A region on a diagonal line is preferable.

In addition, in the medical X-ray imaging system, when the control unit controls the output operation of the signal reading unit, among the voltage values held corresponding to the N columns of the light receiving unit, N ₁ columns ( The voltage value held corresponding to N ₁ <N) is output from the signal reading unit, and the position of the N ₁ column in the light receiving unit is constant every time the voltage value corresponding to one or a plurality of rows is read. A feature may be that each column is shifted. By controlling the output operation of the signal reading unit in this way, for example, the control unit can selectively read out the voltage value from the pixels constituting the imaging region having the predetermined direction as the longitudinal direction.

  The medical X-ray imaging system may be characterized in that the length of the imaging region in a predetermined direction is 15 cm or more. Thereby, it is possible to photograph from the jaw to the upper and lower dentition by one photographing.

  Further, in the medical X-ray imaging system, the solid-state imaging device further includes a pixel formed around the light receiving unit and an X-ray shielding unit that covers the pixel, and the region serving as the light receiving unit is an X-ray shielding unit. The rectangular opening may be defined, and each side of the opening may be inclined with respect to the moving direction.

  Further, in the medical X-ray imaging system, the signal readout unit accumulates the charges input through the N number of readout wirings, and outputs N integration circuits that output voltage values corresponding to the amount of accumulated charges. And the gain of each integrating circuit can be changed in accordance with the amount of charge input through each readout wiring. This makes it possible to select a suitable gain according to the amount of charge, and to increase the frame rate (the number of frame data output per unit time).

  The X-ray imaging system according to the present invention can reduce artifacts in a reconstructed image.

1 is a configuration diagram of an X-ray imaging system 100 according to a first embodiment. It is a figure which shows a mode that the solid-state imaging device 1 turns around the to-be-photographed object A seeing from the upper direction of the to-be-photographed object A (examinee's jaw). 2 is a plan view showing a part of the solid-state imaging device 1 cut away. FIG. It is a sectional side view of the solid-state imaging device 1 along the IV-IV line of FIG. 2 is a diagram illustrating an angular position of the solid-state imaging device 1 according to an imaging mode and an imaging region in the light receiving unit 10. FIG. (A) It is a figure which shows the angle position of the solid-state imaging device 1, and the imaging area 10a of the light-receiving part 10 in imaging modes (1st imaging mode), such as CT imaging. (B) It is a figure which shows the angle position of the solid-state imaging device 1, and the imaging area 10b of the light-receiving part 10 in imaging modes (2nd imaging mode), such as panoramic imaging and cephalometric imaging. It is a figure which shows the imaging area 10b shown in FIG.5 (b) in more detail. (A) It is a figure which shows a mode that square imposition was performed for the light-receiving part 10 in the silicon wafer W. FIG. (B) It is a figure which shows a mode that the rectangular imposition was performed for the light-receiving part 10 in the silicon wafer W. FIG. Disconnection Q ₁ to the row selecting wiring arranged for each row of the light receiving unit 10 is generated from the scanning shift register 40, a disconnection Q ₂ is generated from the signal readout section 20 to the readout wiring disposed in each column FIG. (A) When the rotation angle of the solid-state imaging device 1 is controlled so that the row direction of the light-receiving unit 10 and the moving direction B of the solid-state imaging device 1 are orthogonal, the defective pixel Pd ₁ in a certain row of the light-receiving unit 10 occurs, is a diagram showing a state in which defective pixels Pd ₂ occurs in a certain sequence. (B) When the rotation angle of the solid-state imaging device 1 is controlled so that both the row direction and the column direction of the light receiving unit 10 are inclined with respect to the moving direction B of the solid-state imaging device 1, the same as in FIG. FIG. 6 is a diagram showing a state in which defective pixels Pd ₁ and Pd ₂ are generated. It is a figure which shows the electric charge read-out system in the conventional solid-state imaging device used without rotating a light-receiving part. (A) The case where the signal reading part 120 is arrange | positioned along the longitudinal direction of the imaging region 110a is shown. (B) The case where the signal reading part 120 is arrange | positioned along the longitudinal direction of the imaging area 110b is shown. (A) It is a figure which shows the electric charge reading system at the time of arrange | positioning the signal reading part 140 along the transversal direction of the light-receiving part 130. FIG. (B) It is a figure which shows the electric charge read-out system of the solid-state imaging device 1 which concerns on 1st Embodiment. It is a figure which shows the mode of rotation of the light-receiving part 10 according to the position of the rotation center (axis C shown in FIG. 1) of the solid-state imaging device. (A) The case where the center E of the light receiving unit 10 is the rotation center of the solid-state imaging device 1 is shown. (B) One corner F of the four corners of the rectangular light receiving unit 10 is set as the rotation center of the solid-state imaging device 1, and the corner F is set to the other corner through the first imaging mode and the second imaging mode. On the other hand, the case where the solid-state imaging device 1 is rotated so as to be positioned below is shown. It is a top view which shows the square-shaped light-receiving part 10 and the linear imaging area 10b. It is a top view which shows the square-shaped light-receiving part 10 and the planar imaging area 10b. It is the figure which looked at the mode of the imaging by the light-receiving part 10 shown in FIG. It is a figure which shows the internal structure of the solid-state imaging device 1 which concerns on 1st Embodiment. 3 is a circuit diagram of each of a pixel P _{m, n} , an integration circuit _Sn and a holding circuit H _{n of the} solid-state imaging device 1 according to the first embodiment. FIG. 3 is a timing chart for explaining the operation of the solid-state imaging device 1 according to the first embodiment. 3 is a timing chart for explaining the operation of the solid-state imaging device 1 according to the first embodiment. It is a figure which shows the modification of a structure of the solid-state imaging device 1 which concerns on 1st Embodiment.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram showing a configuration of a medical X-ray imaging system 100 as an embodiment of the present invention. The X-ray imaging system 100 of this embodiment mainly includes imaging modes such as panoramic imaging, cephalometric imaging, and CT imaging in dental care, and images an X-ray image of a subject's jaw. The X-ray imaging system 100 includes a solid-state imaging device and an X-ray generation device, and X-rays output from the X-ray generation device and transmitted through the subject A (that is, the subject's jaw) are transmitted by the solid-state imaging device. Take an image.

  The X-ray imaging system 100 shown in this figure includes a solid-state imaging device 1, an X-ray generation device 106, and a rotation control unit 108 that rotatably supports the solid-state imaging device 1.

  The X-ray generator 106 generates X-rays toward the subject A. The irradiation field of X-rays generated from the X-ray generator 106 is controlled by the primary slit plate 106b. The X-ray generator 106 incorporates an X-ray tube, and the amount of X-ray irradiation to the subject A is controlled by adjusting conditions such as tube voltage, tube current, and energization time of the X-ray tube. The The X-ray generator 106 outputs an X-ray at a predetermined divergence angle in a certain imaging mode by controlling the opening range of the primary slit plate 106b, and this predetermined divergence in another imaging mode. X-rays can be output with a divergence angle narrower than the angle.

  The solid-state imaging device 1 is a CMOS solid-state imaging device having a plurality of pixels arranged two-dimensionally, and converts an X-ray image that has passed through the subject A into electrical image data D. A secondary slit plate 107 that restricts the X-ray incident area is provided in front of the solid-state imaging device 1. The rotation control unit 108 supports the solid-state imaging device 1 so as to be rotatable around an axis C perpendicular to the light receiving surface 11 of the solid-state imaging device 1, and has a predetermined angle corresponding to an imaging mode such as CT imaging, panoramic imaging, or cephalometric imaging. The solid-state imaging device 1 is rotated to a position.

  The X-ray imaging system 100 further includes a turning arm 104. The turning arm 104 holds the X-ray generator 106 and the solid-state imaging device 1 so as to face each other, and turns them around the subject A during CT imaging, panoramic imaging, or cephalometric imaging. Further, a slide mechanism 113 for linearly displacing the solid-state imaging device 1 with respect to the subject A is provided at the time of linear tomography. The turning arm 104 is driven by an arm motor 109 constituting a rotary table, and the rotation angle is detected by an angle sensor 112. The arm motor 109 is mounted on the movable part of the XY table 114, and the center of rotation is arbitrarily adjusted in the horizontal plane.

  Image data D output from the solid-state imaging device 1 is once captured by a CPU (central processing unit) 121 and then stored in the frame memory 122. From the image data stored in the frame memory 122, a tomographic image or a panoramic image along an arbitrary tomographic plane is reproduced by a predetermined calculation process. The reproduced tomographic image and panoramic image are output to the video memory 124, converted into an analog signal by the DA converter 125, and then displayed on the image display unit 126 such as a CRT (cathode ray tube), and used for various diagnoses. The

  A work memory 123 necessary for signal processing is connected to the CPU 121, and an operation panel 119 provided with a panel switch, an X-ray irradiation switch, and the like is further connected. The CPU 121 also controls the motor drive circuit 111 that drives the arm motor 109, slit control circuits 115 and 116 that control the opening ranges of the primary slit plate 106 b and the secondary slit plate 107, and the X-ray generator 106. Each is connected to the control circuit 118 and further outputs a clock signal for driving the solid-state imaging device 1. The X-ray control circuit 118 feedback-controls the amount of X-ray irradiation to the subject based on the signal imaged by the solid-state imaging device 1.

  FIG. 2 is a diagram illustrating a state in which the solid-state imaging device 1 pivots around the subject A when viewed from above the subject A (the subject's jaw). In this figure, the locus of the solid-state imaging device 1 is indicated by a one-dot chain line. The solid-state imaging device 1 captures an X-ray image that has passed through the subject A while moving in the circumferential direction (arrow B in the drawing) along the horizontal plane with the subject A as a center by the swivel arm 104. At this time, the orientation of the solid-state imaging device 1 is set so that the light receiving surface 11 of the solid-state imaging device 1 always faces the subject A.

  3 and 4 are diagrams illustrating the configuration of the solid-state imaging device 1 according to the present embodiment. FIG. 3 is a plan view showing a part of the solid-state imaging device 1 by cutting away, and FIG. 4 is a side sectional view of the solid-state imaging device 1 taken along line IV-IV in FIG. 3 and 4 also show an XYZ orthogonal coordinate system for easy understanding.

  As shown in FIG. 3, the solid-state imaging device 1 includes a light receiving unit 10, a signal reading unit 20, an A / D conversion unit 30, and a scanning shift register 40 that are built in the main surface of the semiconductor substrate 3. The light receiving unit 10, the signal reading unit 20, the A / D conversion unit 30, and the scan shift register 40 may be formed on separate semiconductor substrates. As shown in FIG. 4, the solid-state imaging device 1 includes a flat substrate 2, a scintillator 4, and an X-ray shield 5 in addition to the semiconductor substrate 3. The semiconductor substrate 3 is attached to the base material 2, and the scintillator 4 is disposed on the semiconductor substrate 3. The scintillator 4 generates scintillation light according to the incident X-ray, converts the X-ray image into an optical image, and outputs this optical image to the light receiving unit 10. The scintillator 4 is installed so as to cover the light receiving unit 10 or is provided on the light receiving unit 10 by vapor deposition. The X-ray shielding part 5 is made of a material such as lead having a very low X-ray transmittance. The X-ray shield 5 covers the peripheral edge of the semiconductor substrate 3 and prevents X-rays from entering the signal readout unit 20 and the like.

  The light receiving unit 10 is configured by two-dimensionally arranging M × N pixels P in M rows and N columns. In FIG. 3, the column direction coincides with the X-axis direction, and the row direction coincides with the Y-axis direction. Each of M and N is an integer of 2 or more, and preferably satisfies M <N. In other words, the number of pixels P in the row direction in the light receiving unit 10 is preferably larger than the number of pixels P in the column direction. In this case, the light receiving surface of the light receiving unit 10 has a rectangular shape in which the row direction (Y-axis direction) is the longitudinal direction and the column direction (X-axis direction) is the short direction. The pixels P are arranged at a pitch of 100 μm, for example, and are of the PPS system and have a common configuration.

  In the semiconductor substrate 3, pixels are also formed around the light receiving unit 10, but such pixels are covered with the X-ray shielding unit 5, and light is not incident and no charge is generated. Does not contribute. The light receiving unit 10 of the present embodiment includes M × N pixels P that are two-dimensionally arranged in M rows and N columns as effective pixels for imaging. In other words, the region that becomes the light receiving portion 10 in the semiconductor substrate 3 of the present embodiment is defined by the opening 5 a of the X-ray shielding portion 5.

  The signal reading unit 20 holds a voltage value corresponding to the amount of charge output from each pixel P of the light receiving unit 10 and sequentially outputs the held voltage value. The AD conversion unit 30 receives the voltage value output from the signal reading unit 20, performs A / D conversion processing on the input voltage value (analog value), and outputs a digital value corresponding to the input voltage value. Output. The scan shift register 40 controls each pixel P so that the electric charge accumulated in each pixel P is sequentially output to the signal reading unit 20 for each row.

  As described above, the X-ray imaging system 100 including such a solid-state imaging device 1 includes imaging modes such as CT imaging, panoramic imaging, and cephalometric imaging. The solid-state imaging device 1 is supported by the rotation control unit 108 so as to be rotatable about an axis perpendicular to the light receiving surface, and is controlled to a predetermined angular position corresponding to the imaging mode. Further, the solid-state imaging device 1 has a function of changing an imaging region in the light receiving unit 10 (a region contributing to imaging data in the light receiving unit 10) according to the imaging mode.

  Here, FIG. 5 is a diagram illustrating an angular position of the solid-state imaging device 1 according to the imaging mode and an imaging region in the light receiving unit 10. FIG. 5A is a diagram illustrating the angular position of the solid-state imaging device 1 and the imaging region 10a of the light receiving unit 10 in an imaging mode (first imaging mode) such as CT imaging. FIG. 5B is a diagram illustrating the angular position of the solid-state imaging device 1 and the imaging region 10b of the light receiving unit 10 in an imaging mode (second imaging mode) such as panoramic photography or cephalometric photography. In FIGS. 5A and 5B, an arrow B indicates the moving direction of the solid-state imaging device 1 by the swing arm 104 (see FIG. 1).

  As shown in FIG. 5A, in the first imaging mode such as CT imaging, one of the row direction (arrow G1 in the figure) and the column direction (arrow G2 in the figure) of the light receiving unit 10 moves. More preferably, the rotation angle of the solid-state imaging device 1 is controlled so that the longitudinal direction of the light receiving unit 10 (the row direction G1 in the present embodiment) is parallel to the movement direction B along the direction B. In addition, the imaging region 10 a at this time is configured by all the pixels P in M rows and N columns in the light receiving unit 10. That is, the width in the row direction and the column direction of the imaging region 10a is the same as that of the light receiving unit 10, respectively.

  Further, as shown in FIG. 5B, in the second imaging mode such as panoramic imaging or cephalometric imaging, the row direction G1 and the column direction G2 of the light receiving unit 10 with respect to the moving direction B of the solid-state imaging device 1 are used. The rotation angle of the solid-state imaging device 1 is controlled so that both are inclined. That is, in the second imaging mode, the angle θ formed by the row direction G1 or the column direction G2 of the light receiving unit 10 and the turning plane H of the solid-state imaging device 1 is a value that satisfies 0 ° <θ <90 °. Therefore, for example, when shifting from the CT imaging mode to the panoramic imaging mode, the solid-state imaging device 1 rotates by an angle θ.

  More preferably, the rotation angle of the solid-state imaging device 1 may be controlled so that one diagonal line in the light receiving unit 10 is perpendicular to the turning plane H. The angular position of the solid-state imaging device 1 in this case is determined by the ratio between the width of the light receiving unit 10 in the row direction G1 and the width in the column direction G2. For example, when the width in the row direction G1 and the width in the column direction G2 are equal to each other, the angle θ formed with the turning plane H of the solid-state imaging device 1 is preferably 45 °. When the ratio of the width in the row direction G1 to the width in the column direction G2 is 2: 1, the angle θ formed with the turning plane H of the solid-state imaging device 1 is preferably 60 °.

  Further, the imaging region 10b at this time is set as an elongated region having a predetermined direction as a longitudinal direction in the light receiving unit 10. The predetermined direction is a direction that is inclined with respect to both the row direction G1 and the column direction G2 of the light receiving unit 10 and intersects the moving direction B of the solid-state imaging device 1. In the present embodiment, the predetermined direction (longitudinal direction) of the imaging region 10 b is orthogonal to the moving direction B of the solid-state imaging device 1 and is along the diagonal line of the light receiving unit 10. The imaging region 10 b is set on the diagonal line of the light receiving unit 10. Thereby, one end of the imaging region 10b in the vertical direction of the X-ray imaging system 100, that is, the direction perpendicular to the turning plane H coincides with the uppermost portion (the top portion J1 shown in FIG. 5B), and in the same direction. The other end of the imaging region 10b in FIG. 5 coincides with the lowermost portion (the top portion J2 shown in FIG. 5B) of the light receiving unit 10. In the second imaging mode, the signal reading unit 20 is configured so that the voltage value is selectively read from the pixels constituting the imaging region 10b among the M × N pixels of the light receiving unit 10. The output operation is controlled.

Here, FIG. 6 is a diagram showing the imaging region 10b shown in FIG. 5B in more detail. As illustrated in FIG. 6, the imaging region 10 b includes N ₁ columns (2 ≦ N ₁ <N, illustrated as N ₁ = 4 in FIG. 6) among N columns of pixels P in each row of the light receiving unit 10. The position of the consecutive N ₁ columns (for example, the top column number) that is composed of the pixels P is shifted by a fixed number of columns (two columns in FIG. 6) for each row. In the solid-state imaging device 1, the signal reading unit 20 selectively outputs a voltage value corresponding to the charge output from the pixel P included in the imaging region 10b.

The imaging region 10b is not limited to the form shown in FIG. 6. For example, the position of the consecutive N1 columns ( _first column number) may be shifted by a fixed number of columns for each of a plurality of rows. In the form shown in FIG. 6, the imaging region 10 b is configured by N ₁ consecutive columns in rows (first row and M-th row) located at both ends in the column direction. For example, fewer than the number of columns N ₁ constituting the imaging area 10b in the row is located in a column direction at both ends like the shape of both ends of the imaging region 10b may be slightly changed.

  The effects obtained by the X-ray imaging system 100 according to the present embodiment will be described below. In the case of a dental X-ray imaging system, the shape of the imaging region required for the X-ray imaging apparatus may differ depending on the various imaging modes described above. That is, an imaging region (hereinafter referred to as a first imaging region) used for CT imaging is required to have a sufficient width in the horizontal direction and a certain width in the vertical direction. In addition, an imaging region (hereinafter referred to as a second imaging region) used for panoramic photography or cephalometric photography is required to have a sufficient width in the vertical direction. However, when a plurality of X-ray imaging devices that satisfy these requirements are prepared, there is a problem that the X-ray imaging system becomes large or the X-ray imaging device needs to be replaced when changing the imaging mode. . Therefore, it is preferable that these requirements regarding the first and second imaging regions can be solved by one X-ray imaging apparatus.

  In the X-ray imaging system 100 according to the present embodiment, the following effects are obtained by controlling the rotation angle of the solid-state imaging device 1 as described above. As described above, in the X-ray imaging system 100, the light receiving unit 10 of the solid-state imaging device 1 has a rectangular light receiving surface. In the first imaging mode, the rotation angle of the solid-state imaging device 1 is controlled such that the row direction or the column direction of the light receiving unit 10 is aligned with the moving direction B of the solid-state imaging device 1. For example, when the first imaging mode is set to the CT imaging mode, the first imaging mode has a sufficient width in one of the row direction and the column direction (in the present embodiment, the row direction) and also in the other (in the present embodiment, the column direction). The solid-state imaging device 1 having a light-receiving surface having a certain width is used, and the solid-state imaging device 1 has a sufficient width of the row direction and the column direction along the moving direction B of the solid-state imaging device 1. By controlling the rotation angle, the imaging region 10a in the first imaging mode can be suitably realized.

  Further, when the second imaging mode is, for example, a panoramic shooting mode or a cephalometric shooting mode, an imaging region having a sufficient width in the vertical direction is required. In order to satisfy such a requirement without increasing the area of the light receiving unit 10, for example, the above-described solid-state imaging device 1 is rotated by 90 ° so that the longitudinal direction of the light receiving unit 10 (row direction in the present embodiment) is set. It is also conceivable to match the vertical direction. However, the width in the vertical direction required for the imaging region may not be sufficient even if the width in the longitudinal direction of the light receiving unit 10 satisfies the requirement for the first imaging region 10a.

  In the first imaging mode in which CT imaging is performed, since it is necessary to capture the entire width of the dentition in one imaging, for example, the height (that is, the width in the direction orthogonal to the moving direction B) is 8 cm or more as the dimension of the imaging region. The lateral width (width in the direction parallel to the moving direction B) of 12 cm or more is required. Therefore, as shown in FIG. 7A, if the surface of the light receiving portion 10 is made to have a width of 12 cm and a height of 12 cm, for example, by imposing a square surface for the light receiving portion 10 in the substantially circular silicon wafer W. The required dimensions of the first imaging mode are satisfied. However, in the second imaging mode in which panoramic imaging is performed, since it is necessary to photograph from the jaw to the upper and lower dentition in one imaging, for example, a height of 15 cm or more is required as the dimension of the imaging region (note that the lateral width is 7 mm or more is sufficient). Therefore, when both imaging modes are to be realized using one solid-state imaging device, if these imaging areas are allocated without rotating the solid-state imaging device as in the configuration described in Patent Document 1, the height is A light receiving portion having a width of 15 cm or more and a width of 12 cm or more is required, and a larger silicon wafer is required.

  Therefore, in the X-ray imaging system 100, in the second imaging mode, the rotation angle of the solid-state imaging device 1 so that both the row direction and the column direction of the light receiving unit 10 are inclined with respect to the moving direction B of the solid-state imaging device 1. To control. Since the shape of the light receiving unit 10 is rectangular, the light receiving unit 10 is inclined with respect to the moving direction B of the solid-state imaging device 1 in this manner, thereby widening the vertical direction of the light receiving unit 10 (for example, the length of the diagonal line). To). For example, when the size of the light receiving unit 10 is 12 cm × 12 cm, the vertical width of the imaging region 10b can be increased up to 17 cm (that is, the length of the diagonal line of the light receiving unit 10). Thus, even if the longitudinal width of the light receiving unit 10 is shorter than the vertical width required for the imaging region 10b, it is possible to satisfy the required vertical width of the imaging region 10b. Therefore, according to the X-ray imaging system 100 of the present embodiment, the first imaging mode and the second imaging mode can be realized by one solid-state imaging device 1, and are required for the light-receiving surface of the light-receiving unit 10 of the solid-state imaging device 1. Increase in the area of the image can be suppressed.

  As shown in FIG. 7B, for example, if the size of the light receiving unit 10 in the silicon wafer W is a rectangle of 15 cm × 8 cm, the longitudinal direction of the light receiving unit 10 is orthogonal to the moving direction B of the solid-state imaging device 1. By controlling the rotation angle of the solid-state imaging device 1 as described above (that is, without tilting the light receiving unit 10), the required size of the imaging region in the second imaging mode can be satisfied. However, even if the longitudinal dimension of the light receiving unit 10 satisfies the vertical dimension of the imaging region in the second imaging mode, the light receiving unit 10 is inclined with respect to the moving direction B as in the present embodiment. By doing so, the vertical width of the imaging region 10b can be made longer. For example, when the size of the light receiving unit 10 is 15 cm × 8 cm, the vertical width of the imaging region 10b can be increased up to 17 cm (that is, the length of the diagonal line of the light receiving unit 10).

In addition, by inclining the row direction and the column direction of the light receiving unit 10 with respect to the movement direction B, the following effects can be further obtained. In FIG. 8, the disconnection Q ₁ is connected to the row selection wiring (wiring for controlling the reading of the charge generated by the photodiode of each pixel P) for each row from the scanning shift register 40 for each row of the light receiving unit 10. It generates, showing how the disconnection Q ₂ is generated from the signal readout section 20 to the wiring read disposed in each column (wiring for transmitting a charge generated in the photodiode of each pixel P to the signal reading section 20) FIG. When these disconnections Q ₁ and Q ₂ occur, a pixel P farther than the disconnection position when viewed from the signal reading unit 20 or the scan shift register 40 in the column or row (pixels hatched with diagonal lines in FIG. 8). ) Is a defective pixel (so-called defect) where charge cannot be read out. These defective pixels are continuously generated in the row or the column of the light receiving unit 10 with the occurrence point of the disconnection Q ₁ , Q ₂ as the starting point.

FIG. 9A shows a defect in a certain row of the light receiving unit 10 when the rotation angle of the solid state imaging device 1 is controlled so that the row direction of the light receiving unit 10 and the moving direction B of the solid state imaging device 1 are orthogonal to each other. pixels Pd ₁ occurs, it is a diagram showing a state in which defective pixels Pd ₂ occurs in a certain sequence. FIG. 9B is a diagram when the rotation angle of the solid-state imaging device 1 is controlled so that both the row direction and the column direction of the light receiving unit 10 are inclined with respect to the moving direction B of the solid-state imaging device 1. 9 (a) similar to the defective pixel _Pd 1, Pd ₂ is a diagram showing a state that occurred. Note that a region 10c in the light receiving unit 10 illustrated in FIG. 9A is a preferable imaging region when the row direction and the moving direction B of the light receiving unit 10 are orthogonal to each other in the second imaging mode.

As shown in FIG. 9A, when the rotation angle of the solid-state imaging device 1 is controlled so that the row direction of the light receiving unit 10 is orthogonal to the moving direction B, the continuous direction of the defective pixel Pd ₂ and the solid-state imaging device 1 The moving direction B is parallel to each other. Therefore, when the defective pixels Pd ₂ are also present in the imaging region 10c, in the reconstructed image which the solid-state imaging device 1 is obtained after taking while rotating around the subject to the defective pixel Pd ₂ The corresponding part appears as a so-called artifact.

In contrast, as shown in FIG. 9B, the rotation angle of the solid-state imaging device 1 is controlled so that both the row direction and the column direction of the light receiving unit 10 are inclined with respect to the moving direction B of the solid-state imaging device 1. In this case, the continuous direction of the defective pixels Pd ₁ and Pd ₂ and the moving direction B of the solid-state imaging device 1 are inclined with respect to each other and never parallel. Therefore, when the solid-state imaging device 1 takes an image while turning around the subject, the image portion corresponding to the defective pixels Pd ₁ and Pd ₂ can be supplemented by the subsequent frame data, and artifacts in the reconstructed image are obtained. Can be avoided.

Further, for example, when the solid-state imaging device is used without being rotated as in the configuration described in Patent Document 1, as illustrated in FIGS. 10A and 10B, the imaging region in the first imaging mode in the light receiving unit 110. The longitudinal direction of 110a and the longitudinal direction of the imaging region 110b in the second imaging mode are orthogonal to each other. In such a configuration, for example, as shown in FIG. 10A, when the signal reading unit 120 is arranged along the longitudinal direction of the imaging region 110a, the number of pixels per row in the imaging region 110a is reduced (FIG. 10 ( The arrow E ₁ ) in a) increases the number of pixels per column in the imaging region 110b (arrow E _{2 in} FIG. 10A), and it takes time to read out charges in the second imaging mode. Conversely, for example, as shown in FIG. 10B, when the signal reading unit 120 is arranged along the longitudinal direction of the imaging region 110b, the number of pixels per line in the imaging region 110b decreases (as shown in FIG. 10B). The arrow E ₃ ) increases the number of pixels per column in the imaging region 110a (arrow E _{4 in} FIG. 10B), and it takes time to read out charges in the first imaging mode. As described above, if each imaging region is assigned without rotating the solid-state imaging device, it takes time to read out charges in either the first imaging mode or the second imaging mode, and the frame rate (output per unit time) is taken. The number of frame data) becomes slow.

Further, as shown in FIG. 11A, even when the shape of the light receiving unit 130 is rectangular and the solid-state imaging device is rotated and used, the number of columns N is smaller than the number of rows M (in other words, When the signal reading unit 140 is disposed along the short direction of the light receiving unit 130), the number of pixels per column increases in the imaging regions of the first imaging mode and the second imaging mode (FIG. 11A ) arrow _E 5 of). In this case, it takes time to read out charges in both the first imaging mode and the second imaging mode, resulting in a slow frame rate.

Therefore, in the solid-state imaging device 1 according to the present embodiment, when the shape of the light receiving surface of the light receiving unit 10 is rectangular as shown in FIG. 11B, the light receiving unit 10 has the row direction as the longitudinal direction, It is preferable that M <N, that is, the number N of columns of the pixels P is larger than the number M of rows. In the solid-state imaging device 1, N readout wirings (described later) for reading out charges from each pixel P are provided for each column. With such a configuration, the first imaging mode and the second imaging mode are arranged. In both cases, since the number of pixels P to be read from the readout wiring can be reduced (arrow E _{6 in} FIG. 11B), the charge readout time can be shortened and the frame rate can be further increased. it can.

  Further, as described above, the solid-state imaging device 1 is supported by the rotation control unit 108 and controlled to an angular position corresponding to the imaging mode. Here, FIG. 12 is a diagram illustrating a state of rotation of the light receiving unit 10 in accordance with the position of the rotation center (the axis C illustrated in FIG. 1) of the solid-state imaging device 1. FIG. 12A shows a case where the center E of the light receiving unit 10 is the rotation center of the solid-state imaging device 1. FIG. 12B shows the corner F as a center of rotation of the solid-state imaging device 1 out of the four corners of the rectangular light receiving unit 10 through the first imaging mode and the second imaging mode. Shows a case in which the solid-state imaging device 1 is rotated so that is positioned below the other corners (that is, the corner F is always located on the lower jaw side with respect to the subject). In FIGS. 12A and 12B, the solid line shows the angular position of the light receiving unit 10 in the first imaging mode such as CT imaging, and the broken line shows panoramic photography or cephalometric photography. The angular position of the light receiving unit 10 in the second imaging mode is shown.

  The rotation center of the solid-state imaging device 1 of the present embodiment can be set at various positions such as the center E of FIG. 12A and the corner F of FIG. 12B, but the corner of FIG. Most preferably, the center of rotation of the solid-state imaging device 1 is set in the part F. When the solid-state imaging device 1 captures an X-ray image while moving around the subject's jaw, the subject's head position is fixed by placing the subject's lower jaw on a support base. In such a case, the reference of the height position of the subject's jaw is the lower end of the jaw. Therefore, if the rotation center of the solid-state imaging device 1 is set at the corner F in FIG. 12B, the height of the lower end of the light receiving unit 10 in the first imaging mode and the second imaging mode is set to the height of the corner F. Can be matched with each other. Therefore, in both the first imaging mode and the second imaging mode, the height of the light receiving unit 10 and the height of the subject's jaw can be accurately matched.

  Further, as described above, according to the solid-state imaging device 1 of the present embodiment, when the size of the light receiving unit 10 is 12 cm × 12 cm, the angle θ formed with the turning plane H of the solid-state imaging device 1 is 45 °. Thus, the vertical width of the imaging region 10b can be increased up to 17 cm (that is, the length of the diagonal line of the light receiving unit 10). Here, FIG. 13 is a plan view showing the light receiving unit 10 having such dimensions, and shows the state of the light receiving unit 10 in the second imaging mode such as panoramic photography and cephalometric photography, and the imaging region 10b. In the second imaging mode, by setting the imaging region 10b on the diagonal line of the light receiving unit 10, the vertical width can be set to 17 cm. In this case, the imaging region 10b may have a width of about 7 mm.

  However, for example, in panoramic photography, the vertical width of the imaging region may be about 15 cm. Further, depending on the configuration of the X-ray imaging system, it may be about 14 cm. In these cases, as shown in FIG. 14, it is preferable to set the horizontal width WT of the imaging region 10b as wide as possible within a range in which the vertical width of the imaging region 10b is 15 cm (or 14 cm) or more.

FIG. 14 is a plan view showing the light receiving unit 10 when the lateral width WT of the imaging region 10b is set wider as described above. The imaging region 10b shown in FIG. 14 is composed of a plurality of pixels P described below. First, among the first row to the Mth row of the light receiving unit 10, in several rows at one end including the first row, the row number increases with a certain column several columns away from the first column. The pixels P in the imaging region 10b are set so that the number of columns gradually increases. Further, in several rows at the other end including the Mth row, the number of columns gradually increases as the row number decreases, centering on a certain column several columns away from the Nth column (in this example, N = M). Pixels P in the imaging region 10b are set so as to increase. And in each remaining row of the first row to the M-th row of the light receiving unit 10, the imaging region 10 b is the maximum column number N ₂ among the number of columns constituting the imaging region 10 b in each row at the end portion described above. It consists pixel P of the same number of N ₂ columns, and the position of the N ₂ columns (e.g. leading column number) shifts by one column for each row.

  In the solid-state imaging device 1, the signal reading unit 20 selectively outputs a voltage value corresponding to the charge output from the pixel P included in the imaging region 10b. Alternatively, after the solid-state imaging device 1 outputs image data including all the pixels P, the CPU 121 illustrated in FIG. 1 may extract data corresponding to the pixels P included in the imaging region 10b. Alternatively, after the image data including all the pixels P is stored in the frame memory 122 by the CPU 121, when a panoramic image is formed, data corresponding to the pixels P included in the imaging region 10b is selectively used to generate an image. It may be configured.

  As shown in FIG. 14, the following advantages can be obtained by setting the horizontal width WT of the imaging region 10b as wide as possible while securing the vertical width of the imaging region 10b necessary in the second imaging mode. . That is, in the second imaging mode, imaging is performed by rotating around the subject A in the vertically long imaging area 10b. In the case of the linear (one-dimensional) imaging region 10b illustrated in FIG. 13, the solid-state imaging device 1 needs to continuously perform imaging operations while rotating around the subject A. In this case, the subject A is continuously irradiated with X-rays. On the other hand, as shown in FIG. 14, by setting the horizontal width of the imaging region 10b as wide as possible and making the imaging region 10b planar (two-dimensional), it corresponds to the horizontal width WT of the imaging region 10b. The solid-state imaging device 1 is stopped for each step, and X-rays can be irradiated for a very short time (in the form of pulses) only during that time.

  FIG. 15 is a diagram of such an imaging state viewed from above the subject A. As shown in FIG. 15, when the subject A is imaged, the X-ray source 150 and the solid-state imaging device 1 are arranged so as to sandwich the subject A. The X-ray source 150 is a pulse wave X-ray source that emits pulsed X-rays for a short time. Then, the solid-state imaging device 1 is stopped for each rotation angle α corresponding to the lateral width WT of the imaging region 10b, and the X-ray pulse is irradiated from the X-ray source 150 only during that time, and the solid-state imaging device 1 performs imaging. By repeating this operation, a panoramic image or a cephalo image can be acquired. According to such an imaging method, the subject A is not imaged while the solid-state imaging device 1 moves, so that the subject A can be moved at a high speed, and the time required to acquire one panoramic image (or cephalo image) is reduced. can do. Therefore, the time during which the subject who is the subject A must be stationary is shortened, and the burden on the subject can be reduced. Moreover, since the solid-state imaging device 1 is stopped for every imaging, the blur of the image resulting from the motion of the subject A can be suppressed, and a clearer image can be acquired. Furthermore, since the solid-state imaging device 1 stops and irradiates X-rays for only a short time for imaging, the exposure dose of the subject can be further reduced.

  In the imaging method shown in FIG. 15, instead of the X-ray source 150 which is a pulse wave X-ray source, a continuous wave X-ray source and X-rays emitted from the continuous wave X-ray source are used for a short time. You may provide the shutter to let it pass. Even if it is such a structure, the effect mentioned above can be acquired effectively.

Subsequently, a detailed configuration of the solid-state imaging device 1 according to the present embodiment will be described. FIG. 16 is a diagram illustrating an internal configuration of the solid-state imaging device 1. The light receiving unit 10 includes M × N pixels P _{1,1 to} P _{M, N} two-dimensionally arranged in M rows and N columns. The pixel P _{m, n} is located in the m-th row and the n-th column. Here, m is an integer from 1 to M, and n is an integer from 1 to N. Each of the N pixels P _{m, 1 to} P _{m, N} in the m-th row is connected to the scan shift register 40 by the m-th row selection wiring LV _{, m} . In FIG. 16, the scan shift register 40 is included in the control unit 6. M pixels _P 1, n _{to P M, n} respective output terminals of the n-th column is for the n-th column readout wiring _{L O,} by _n, and is connected to the integrating circuit _{S n} of the signal readout section 20.

The signal reading unit 20 includes N integration circuits S _{1 to} S _N and N holding circuits H _{1 to} H _N. Each integrating circuit _Sn has a common configuration. Moreover, the holding circuits H _n have a common configuration. Each integrating circuit S _n readout wiring L _{O, n} and has an input terminal connected to, and accumulates charges input to this input terminal, the output terminal a voltage value corresponding to the accumulated charge amount output to the holding circuit _{H n.} N integrating circuits S ₁ to S _N, respectively, connected to the control unit 6 by a reset wiring L _R, and also connected to the control unit 6 by a gain setting wiring L _G. Each holding circuit H _n has an input terminal connected to the output terminal of the integrating circuit S _n , holds a voltage value input to the input terminal, and the held voltage value is connected to the voltage output wiring from the output terminal Output to L _out . The N holding circuits _H 1 to H _N, respectively, are connected to the controlling section 6 by a holding wiring _{L H.} Moreover, each holding circuit H _n is the n column selecting wiring L _H, are connected to the read shift register 41 of the control unit 6 by _n.

The A / D conversion unit 30 inputs a voltage value output from each of the _N holding circuits H _{1 to} H _N to the voltage output wiring L _out, and outputs A / D to the input voltage value (analog value). D conversion processing is performed, and a digital value corresponding to the input voltage value is output as image data D.

Scanning shift register 40 of the control unit 6, the m-th row selecting control signal Vsel (m) the m-th row selecting wiring _{L V,} and outputs the _m, the m-th row selecting control signal Vsel (m) the m Each of the N pixels Pm _{, 1 to} Pm _{, N in the} row is given. The M row selection control signals Vsel (1) to Vsel (M) are sequentially set to significant values. Further, the read shift register 41 of the control unit 6 outputs the nth column selection control signal Hsel (n) to the nth column selection wiring LH _{, n} , and this nth column selection control signal Hsel (n). give the holding circuit _{H n.} N column selection control signals Hsel (1) to Hsel (N) are also sequentially set to significant values.

The control unit 6 outputs a reset control signal Reset to the reset wiring _{L R,} giving the reset control signal Reset to each of the N integrating circuits _S 1 to S _N. Control unit 6 outputs a gain setting signal Gain to the gain setting wiring _{L G,} giving the gain setting signal Gain to each of the N integrating circuits _S 1 to S _N. Control unit 6 outputs a holding control signal Hold to the holding wiring _{L H,} gives the holding control signal Hold to the N holding circuits _H 1 to H _N, respectively. Further, although not shown, the control unit 6 also controls the A / D conversion process in the A / D conversion unit 30.

FIG. 17 is a circuit diagram of each of the pixel P _{m, n} , the integration circuit S _n, and the holding circuit H _n of the solid-state imaging device 1. Here, a circuit diagram of the pixel P _{m, n} is shown on behalf of the M × N pixels P _{1,1 to} PM _{, N,} and the integration circuit S on behalf of the _N integration circuits S _{1 to SN.} It shows a circuit diagram of the _n, also shows a circuit diagram of the holding circuit _{H n} as a representative of the n holding circuits _H 1 to H _n. That is, a circuit portion related to the pixel P _{m, n in the m-} th row and the n-th column and the n-th column readout wiring L _{O, n} is shown.

Pixel _{P m, n} includes a switch SW ₁ for the photodiode PD and a readout. The anode terminal of the photodiode PD is grounded, the cathode terminal of the photodiode PD is connected to the n-th column readout wiring L _O via the readout switch SW _1, and _n. The photodiode PD generates an amount of charge corresponding to the incident light intensity, and accumulates the generated charge in the junction capacitor. Readout switch SW ₁ is the m row selecting wiring _{L V,} m-th row selection control signal Vsel passed through the _m (m) is given from the control unit 6. The m-th row selection control signal Vsel (m) instructs the opening / closing operation of the read switch SW ₁ of each of _{the N} pixels P _{m, 1 to} P _{m, N} in the m-th row in the light receiving unit 10.

In this pixel P _{m, n} , when the m-th row selection control signal Vsel (m) is at a low level, the readout switch SW ₁ is opened, and the charge generated in the photodiode PD is the n-th column readout wiring. Without being output to L _{O, n} , it is accumulated in the junction capacitor. On the other hand, when the m-th row selecting control signal Vsel (m) is at high level, closes the readout switch SW _1, the charges accumulated in the junction capacitance portion is generated in the photodiode PD until it is read The signal is output to the nth column readout wiring L _{O, n} via the switch SW ₁ .

The n-th column readout wiring L _{O, n} is connected to the readout switch SW _{1 of} each of the _M pixels P _{1, n to} P _{M, n} in the n-th column in the light receiving unit 10. The n-th column readout wiring L _{O, n} uses the charge generated in the photodiode PD of any one of the _M pixels P _{1, n to} P _{M, n} to be read by the readout switch SW _{1 of the} pixel. read through by and transferred to the integrating circuit S _n.

The integrating circuit _Sn includes an amplifier A ₂ , an integrating capacitive element C ₂₁ , an integrating capacitive element C ₂₂ , a discharging switch SW ₂₁ and a gain setting switch SW ₂₂ . Integrating capacitive element C ₂₁ and the discharge switch SW ₂₁ is connected in parallel to each other, and provided between an input terminal of the amplifier A ₂ and the output terminal. Moreover, the integrating capacitive element C ₂₂ and the gain setting switch SW ₂₂ is connected in series to each other, the input of the amplifier A ₂ so that the gain setting switch SW ₂₂ is connected to the input terminal side of the amplifier A ₂ It is provided between the terminal and the output terminal. The input terminal of the amplifier A ₂ is connected to the n-th column readout wiring L _{O, n.}

The discharge switch _{SW 21,} the reset control signal Reset passing through the resetting wiring _{L R} given from the control unit 6. The reset control signal Reset instructs the opening / closing operation of the discharge switch SW ₂₁ of each of the _N integration circuits S _{1 to} S _N. Gain setting switch _{SW 22,} the gain setting signal Gain is provided passing through the gain setting wiring _{L G} from the controlling section 6. The gain setting signal Gain instructs the opening / closing operation of the gain setting switch SW ₂₂ of each of the _N integrating circuits S _{1 to} S _N.

In the integrating circuit _Sn , the integrating capacitive elements C ₂₁ and C ₂₂ and the gain setting switch SW ₂₂ form a feedback capacitive unit having a variable capacitance value. That is, when the gain setting signal Gain is at low level the gain setting switch SW ₂₂ is open, the capacitance value of the feedback capacitance section is equal to the capacitance value of the integrating capacitive element C _21. On the other hand, when the gain setting signal Gain is at a high level and the gain setting switch SW ₂₂ is closed, the capacitance value of the feedback capacitance section is equal to the sum of the capacitance values of the integrating capacitive elements C ₂₁ and C ₂₂ . When the reset control signal Reset is at high level, closes the discharge switch SW _21, the feedback capacitance section is discharged, the voltage output from the integrating circuit S _n is initialized. On the other hand, when the reset control signal Reset is at a low level, the discharge switch SW ₂₁ is opened, the charge input to the input terminal is accumulated in the feedback capacitor unit, and the voltage value corresponding to the accumulated charge amount is an integration circuit. is output from the S _n.

The holding circuit H _n includes an input switch SW ₃₁ , an output switch SW _32, and a holding capacitive element C ₃ . One end of the holding capacitive element C ₃ is grounded. The other end of the holding capacitive element C ₃ is connected via an input switch SW ₃₁ is connected to the output terminal of the integrating circuit S _n, and is connected to the voltage output wiring L _out via the output switch SW _32. The input switch _{SW 31,} is given holding control signal Hold passed through the holding wiring _{L H} from the controlling section 6. The holding control signal Hold instructs the opening / closing operation of the input switch SW ₃₁ of each of the _N holding circuits H _{1 to} H _N. The output switch SW ₃₂ is supplied with the n-th column selection control signal Hsel (n) from the control unit 6 through the n-th column selection wiring LH _{, n} . N-th column selecting control signal Hsel (n) is for instructing opening and closing operations of the output switch _{SW 32} of the holding circuit _{H n.}

In the holding circuit H _n , when the holding control signal Hold changes from the high level to the low level, the input switch SW ₃₁ changes from the closed state to the opened state, and the voltage value input to the input terminal at that time is held. It is held in the use capacitive element C _3. Further, when the n-th column selection control signal Hsel (n) is at a high level, the output switch SW ₃₂ is closed, and the voltage value held in the holding capacitive element C ₃ is supplied to the voltage output wiring L _out . Is output.

When the control unit 6 outputs a voltage value corresponding to the light reception intensity of each of _{the N} pixels P _{m, 1 to} P _{m, N} in the m-th row in the light receiving unit 10, the N integration is performed by the reset control signal Reset. After instructing the discharge switches SW ₂₁ of the circuits S _{1 to} S _{N to} be closed and then opened, N pixels P _m in the m-th row in the light receiving unit 10 are received by the m-th row selection control signal Vsel (m). _instructs 1 _{to P m,} the readout switch SW _{1 in} the _N respectively for a predetermined period close as. During the predetermined period, the control unit 6 instructs the input switch SW ₃₁ of each of the _N holding circuits H _{1 to} H _N to change from the closed state to the open state by the holding control signal Hold. Then, after the predetermined period, the control unit 6 sequentially sets the output switches SW ₃₂ of each of the _N holding circuits H _{1 to} H _N for a certain period in response to the column selection control signals Hsel (1) to Hsel (N). Instruct to close only. The control unit 6 sequentially performs the above control for each row.

As described above, the control unit 6 controls the opening / closing operation of the readout switch SW ₁ of each of the M × N pixels P _{1,1 to} P _{M, N} in the light receiving unit 10 and the voltage value in the signal readout unit 20. The holding operation and output operation are controlled. As a result, the control unit 6 uses the voltage value corresponding to the amount of charge generated in each of the photodiodes PD of the M × N pixels P _{1,1 to} P _{M, N} in the light receiving unit 10 as frame data as a signal reading unit. 20 to repeatedly output.

As described above, the solid-state imaging device 1 according to the present embodiment has the first imaging mode such as CT imaging and the second imaging mode such as panoramic imaging and cephalometric imaging. As shown in FIG. 5, in the first imaging mode and the second imaging mode, the imaging areas in the light receiving unit 10 are different from each other (in the first imaging mode, the area 10a in FIG. 5A and in the second imaging mode). FIG. 5B shows a region 10b). Therefore, in the first imaging mode, the control unit 6 determines a voltage corresponding to the amount of charge generated in each of the photodiodes PD of the M × N pixels P _{1,1 to} P _{M, N} in the light receiving unit 10. The value is output from the signal reading unit 20. In addition, in the second imaging mode, the control unit 6 out of M × N pixels P _{1,1 to} P _{M, N in} the light receiving unit 10 has a specific range of pixels P _m constituting the imaging region 10b. _{, N} selectively output a voltage value corresponding to the amount of charge generated in each photodiode PD from the signal reading unit 20.

  Further, in the second imaging mode, the control unit 6 makes the readout pixel pitch in the frame data based on the voltage value output from the signal readout unit 20 smaller than that in the first imaging mode, and is output per unit time. The frame rate, which is the number of frame data, is increased, and the gain, which is the ratio of the output voltage value to the input charge amount in the signal reading unit 20, is increased. For example, in the first imaging mode such as CT imaging, the pixel pitch is 200 μm and the frame rate is 30 F / s. In the second imaging mode such as panoramic photography or cephalometric photography, the pixel pitch is 100 μm and the frame rate is 300 F / s.

  Thus, in the second imaging mode, the pixel pitch is small and the frame rate is faster than in the first imaging mode. Therefore, in the first imaging mode, it is necessary to perform binning reading in order to increase the pixel pitch compared to that in the second imaging mode. In addition, since the frame rate is faster in the second imaging mode than in the first imaging mode, the amount of light received by each pixel of each frame data is small.

Therefore, the control unit 6 varies the gain, which is the ratio of the output voltage value to the input charge amount in the signal reading unit 20, between the first imaging mode and the second imaging mode. That is, when each integrating circuit _Sn is configured as shown in FIG. 17, the control unit 6 controls the opening and closing of the gain setting switch SW ₂₂ by the gain setting signal Gain, thereby controlling each integrating circuit _Sn . The capacitance value of the feedback capacitor unit is set as appropriate, and the gain is made different between the first imaging mode and the second imaging mode.

More specifically, by closing the gain setting switch SW ₂₂ in the first imaging mode, the capacitance value of the feedback capacitance unit is set to the capacitance value of each of the integration capacitance element C ₂₁ and the integration capacitance element C _22. Equal to the sum. On the other hand, by opening the gain setting switch SW ₂₂ in the second imaging mode, the capacitance value of the feedback capacitor unit is made equal to the capacitance value of the integrating capacitive element C ₂₁ . In this way, when in the second imaging mode than when in the first imaging mode, by decreasing the capacitance value of the feedback capacitance section of each integrating circuit S _n, to increase the gain. Thereby, pixel data for a certain amount of light can be set to values close to each other in the first imaging mode and the second imaging mode, and a suitable operation can be performed in each imaging mode.

  Next, the operation of the solid-state imaging device 1 according to the first embodiment will be described in detail. In the solid-state imaging device 1 according to the present embodiment, M row selection control signals Vsel (1) to Vsel (M) and N column selection control signals Hsel (1) to Hsel under the control of the control unit 6. (N) Since the reset control signal Reset and the hold control signal Hold each change in level at a predetermined timing, it is possible to capture the image of the light incident on the light receiving unit 10 and obtain frame data.

The operation of the solid-state imaging device 1 in the first imaging mode is as follows. FIG. 18 is a timing chart for explaining the operation of the solid-state imaging device 1 according to the first embodiment. Here, the operation in the first imaging mode in which binning readout of 2 rows and 2 columns is performed will be described. That is, the readout pixel pitch in the frame data is set to twice the pixel pitch. In each integrating circuit _Sn , the gain setting switch SW ₂₂ is closed, the capacitance value of the feedback capacitance unit is set to a large value, and the gain is set to a small value.

This figure shows, in order from the top, (a) N-number of the integrating circuit _S 1 to S _N reset control signal for instructing opening and closing operations of the respective discharging switches _{SW 21} Reset, (b) the first row in the photodetecting section 10 and the second row of the pixel _{P 1,1 ~P 1, N, P} 2,1 ~P 2, the first row selection control signal Vsel instructing _N each opening and closing operation of the readout switch SW ₁ (1) and the 2-row selection control signals Vsel (2), (c) Read-out switches for the pixels P _{3,1 to} P _{3, N} , P _{4,1 to} P _{4, N} in the third and fourth rows in the light receiving unit 10 The third row selection control signal Vsel (3) and the fourth row selection control signal Vsel (4) for instructing the opening / closing operation of the SW ₁ , and (d) an input switch for each of the _N holding circuits H _{1 to} H _N holding control for instructing opening and closing operations of the SW ₃₁ No. Hold is shown.

Further, in this figure, (e) the first column selection control signal Hsel (1) instructing the opening / closing operation of the output switch SW ₃₂ of the holding circuit H ₁ and (f) the holding circuit H ₂ in order. second column selection control signal Hsel for instructing opening and closing operations of the output switch _{SW 32 (2), (g} ) the third column selection control signal Hsel for instructing opening and closing operations of the output switch _{SW 32} of the holding circuit _{H 3} (3 ), (h) the n-th column selection control signal Hsel for instructing opening and closing operations of the output switch _{SW 32} of the holding circuit _{H n} (n), and, (i) opening and closing operation of the output switch _{SW 32} of the holding circuit _{H n} An Nth column selection control signal Hsel (N) is indicated.

The readout of the charges generated in the photodiode PD of each of the 2N pixels P _{1,1 to} P _{1, N} , P _{2,1 to} P _{2, N in} the first row and the second row and accumulated in the junction capacitance portion is as follows: This is done as follows. Before the time _{t 10,} M row selecting control signals Vsel (1) ~Vsel (M) , N pieces of column selection control signal Hsel (1) ~Hsel (N) , the reset control signal Reset, and the holding control signal Hold Each is at a low level.

Period from the time _{t 10} to the time _{t 11,} the reset control signal Reset to be output to the reset wiring _{L R} from the controlling section 6 becomes the high level, thereby, in the N integrating circuits _S 1 to S _N, respectively, the discharge The switch SW ₂₁ is closed, and the integrating capacitive elements C ₂₁ and C ₂₂ are discharged. Further, during a period from the time _{t 12} after the time _{t 11} to time _{t 15,} the first row selecting control output from the control unit 6 to the first row selecting wiring _{L V, 1} signal Vsel (1) a high level Accordingly, the readout switch SW _{1 of} each of _{the N} pixels P _{1,1 to} P _{1, N} in the first row in the light receiving unit 10 is closed. Further, in the same period _(t 12 _{~t 15),} the second row selection control signal Vsel (2) becomes the high level output from the control section 6 to the second row selecting wiring _{L V, 2,} which , the second row of N pixels _P 2,1 _{to P} in the photodetecting section 10 _{2, N} the readout switch SW ₁ in each of closed.

Within this period (t _{12 to} t ₁₅ ), during the period from time t ₁₃ to time t ₁₄ , the holding control signal Hold that is output from the control unit 6 to the holding wiring L _H becomes high level. In each of the holding circuits H _{1 to} H _N , the input switch SW ₃₁ is closed.

Period in _(t 12 _{~t 15)} in the first row and the pixels _P 1, n of the second _{row, P 2, n} the readout switch SW ₁ is closed, the switch discharge of each integrating circuit _{S n} SW ₂₁ is open. Therefore, the charges generated up to now in the photodiode PD of the pixel P _{1, n} and accumulated in the junction capacitance portion are the readout switch SW ₁ and the n-th column readout wiring L _{O of the} pixel P _{1, n. ,} through _n, it is stored after being transferred to the integrating capacitive element _{C 21, C 22} of the integrating circuit _{S n.} At the same time, the charge is also the pixel P _{2, n} readout switch SW ₁ in and the n-th column readout wiring of which was generated in the photodiode PD of the pixel P _{2, n} and accumulated in the junction capacitance portion until then L _O, through _n, is stored after being transferred to the integrating capacitive element _{C 21, C 22} of the integrating circuit _{S n.} Then, a voltage value corresponding to the amount of charges accumulated in the integrating capacitive element C _21, C ₂₂ of each integrating circuit S _n is output from the output terminal of the integrating circuit S _n.

At time _{t 14} in the period _(t 12 _{~t 15)} inside, by holding control signal Hold switches from high level to low level, in the N holding circuits _H 1 to H _N, the input switch _{SW 31} switches from a closed state to an open state, a voltage value being input to the input terminal of the holding circuit H _n are output from the output terminal of the integrating circuit S _n at that time is held in the holding capacitive element C _3.

After the period (t _{12 to} t ₁₅ ), the column selection control signals Hsel (1) to Hsel (N) output from the control unit 6 to the column selection wirings L _{H, 1 to} L _{H, N} are sequentially supplied. The output switch SW _{32 of} each of the _N holding circuits H _{1 to} H _N is sequentially closed for a fixed period and held in the holding capacitor element C ₃ of each holding circuit H _n. The voltage values thus output are sequentially output to the voltage output wiring L _out through the output switch SW ₃₂ . Voltage value _{V out} to be output to the voltage output wiring _{L out,} the pixel _P 1, 1 _{to P} 1 of the 2N first and second _{rows, N,} P 2,1 _{to P 2, N} of each It represents a value obtained by adding the received light intensity in the photodiode PD in the column direction.

The voltage value sequentially output from each of the _N holding circuits H _{1 to} H _N is input to the A / D conversion unit 30 and converted into a digital value corresponding to the input voltage value. Then, among the N digital values output from the A / D converter 30, the digital values corresponding to the first column and the second column are added, and the digital values corresponding to the third column and the fourth column, respectively. Are added, and then two digital values are added.

Subsequently, the charges generated in the photodiode PD of each of the 2N pixels P _{3,1 to} P _{3, N} , P _{4,1 to} P _{4, N} in the third row and the fourth row and accumulated in the junction capacitance portion Is read as follows.

From time t _{20 when the} column selection control signal Hsel (1) becomes high level in the above-described operation, to time t ₂₁ after the time when the column selection control signal Hsel (N) once becomes high level and then becomes low level. period, the reset control signal reset to be output to the reset wiring _{L R} from the controlling section 6 becomes the high level, thereby, in the N integrating circuits _S 1 to S _N, respectively, closes the discharge switch _{SW 21,} The integrating capacitive elements C ₂₁ and C ₂₂ are discharged. Further, the period from the time _{t 22} after the time _{t 21} to time _{t 25,} the third row selection control signal Vsel (3) a high level output from the control section 6 to the third row selecting wiring _{L V, 3} As a result, the readout switch SW _{1 of} each of _{the N} pixels P _{3,1 to} P _{3, N} in the third row in the light receiving unit 10 is closed. Further, in the same period _(t 22 _{~t 25),} the fourth row selection control signal Vsel (4) becomes the high level output from the control section 6 to the fourth row selecting wiring _{L V, 4,} which As a result, the readout switch SW _{1 of} each of _{the N} pixels P _{4,1 to} P _{4, N} in the fourth row in the light receiving unit 10 is closed.

Within this period (t _{22 to} t ₂₅ ), during the period from time t ₂₃ to time t ₂₄ , the holding control signal Hold that is output from the control unit 6 to the holding wiring L _H becomes high level. In each of the holding circuits H _{1 to} H _N , the input switch SW ₃₁ is closed.

After the period (t _{22 to} t ₂₅ ), the column selection control signals Hsel (1) to Hsel (N) output from the control unit 6 to the column selection wirings L _{H, 1 to} L _{H, N} are sequentially supplied. The output switch SW _{32 of} each of the _N holding circuits H _{1 to} H _N is sequentially closed for a certain period. As described above, the received light intensity in the photodiode PD of each of the 2N pixels P _{3,1 to} P _{3, N} , P _{4,1 to} P _{4, N} in the third row and the fourth row is added in the column direction. A voltage value _Vout representing the measured value is output to the voltage output wiring _Lout .

The voltage value sequentially output from each of the _N holding circuits H _{1 to} H _N is input to the A / D conversion unit 30 and converted into a digital value corresponding to the input voltage value. Then, among the N digital values output from the A / D converter 30, the digital values corresponding to the first column and the second column are added, and the digital values corresponding to the third column and the fourth column, respectively. Are added, and then two digital values are added.

In the first imaging mode, following the operations for the first row and the second row as described above, the operations for the third row and the fourth row, and the subsequent operations from the fifth row to the Mth row. Thus, frame data representing an image obtained by one imaging is obtained. When the operation for the Mth row is completed, the same operation is performed again in the range from the first row to the Mth row, and frame data representing the next image is obtained. As described above, by repeating the same operation at a constant period, the voltage value _Vout representing the two-dimensional intensity distribution of the light image received by the light receiving unit 10 is output to the voltage output wiring _Lout , and the frame data is repeatedly generated. Is obtained. The readout pixel pitch in the frame data obtained at this time is twice the pixel pitch.

On the other hand, the operation of the solid-state imaging device 1 in the second imaging mode is as follows. FIG. 19 is a timing chart for explaining the operation of the solid-state imaging device 1 according to the first embodiment. In this second imaging mode, binning readout is not performed. That is, the readout pixel pitch in the frame data is made equal to the pixel pitch. In each integrating circuit _Sn , the gain setting switch SW ₂₂ is open, the capacitance value of the feedback capacitance unit is set to a small value, and the gain is set to a large value.

  FIG. 19 shows operations for the first row and the second row in the light receiving unit 10. In this figure, in order from the top, (a) reset control signal Reset, (b) first row selection control signal Vsel (1), (c) second row selection control signal Vsel (2), (d) holding control. Signal Hold, (e) first column selection control signal Hsel (1), (f) second column selection control signal Hsel (2), (g) third column selection control signal Hsel (3), (h) fourth Column selection control signal Hsel (4), (i) fifth column selection control signal Hsel (5), and (j) sixth column selection control signal Hsel (6) are shown.

Reading of charges generated in the photodiode PD of each of _{the N} pixels P _{1,1 to} P _{1, N in} the first row and accumulated in the junction capacitance portion is performed as follows. Before the time _{t 10,} M row selecting control signals Vsel (1) ~Vsel (M) , N pieces of column selection control signal Hsel (1) ~Hsel (N) , the reset control signal Reset, and the holding control signal Hold Each is at a low level.

Period from the time _{t 10} to the time _{t 11,} the reset control signal Reset to be output to the reset wiring _{L R} from the controlling section 6 becomes the high level, thereby, in the N integrating circuits _S 1 to S _N, respectively, the discharge use the switch _{SW 21} closes, the integrating capacitive element _{C 21} is discharged. Further, during a period from the time _{t 12} after the time _{t 11} to time _{t 15,} the first row selecting control output from the control unit 6 to the first row selecting wiring _{L V, 1} signal Vsel (1) a high level Accordingly, the readout switch SW _{1 of} each of _{the N} pixels P _{1,1 to} P _{1, N} in the first row in the light receiving unit 10 is closed.

Within this period (t _{12 to} t ₁₅ ), during the period from time t ₁₃ to time t ₁₄ , the holding control signal Hold that is output from the control unit 6 to the holding wiring L _H becomes high level. In each of the holding circuits H _{1 to} H _N , the input switch SW ₃₁ is closed.

In the period _(t 12 _{~t 15),} the readout switch SW ₁ in each pixel _{P 1, n} of the first row is closed, the discharge switch _{SW 21} of each integrating circuit _{S n} is open, it The charges generated in the photodiode PD of each pixel P _{1, n} and accumulated in the junction capacitor until then are read switch SW ₁ and n-th column readout wiring L _{O, n of the} pixel P _{1 , n.} through and accumulated are transferred to the integrating capacitive element C ₂₁ of the integrating circuit S _n. Then, a voltage value corresponding to the amount of charges accumulated in the integrating capacitive element C ₂₁ of each integrating circuit S _n is output from the output terminal of the integrating circuit S _n.

At time _{t 14} in the period _(t 12 _{~t 15)} inside, by holding control signal Hold switches from high level to low level, in the N holding circuits _H 1 to H _N, the input switch _{SW 31} switches from a closed state to an open state, a voltage value being input to the input terminal of the holding circuit H _n are output from the output terminal of the integrating circuit S _n at that time is held in the holding capacitive element C _3.

Of the column selection control signals Hsel (1) to Hsel (N) output from the control unit 6 to the column selection wirings L _{H, 1 to} L _{H, N} after the period (t _{12 to} t ₁₅ ), Column selection control signals Hsel (1) to Hsel (N ₁ ) corresponding to the first consecutive N ₁ columns (N ₁ = 4 in this embodiment) are sequentially set to a high level for a certain period. As a result, the output switches SW ₃₂ of the first successive N ₁ columns of the holding circuits H _{1 to} H _N1 are sequentially closed for a certain period and held in the holding capacitive element C ₃ of each holding circuit H _n. The output voltage value is sequentially output to the voltage output wiring L _out through the output switch SW ₃₂ . Voltage value _{V out} to be output to the voltage output wiring _{L out} is representative of the received light intensity in the first row of the _{N 1} pixels _P 1, 1 _{to P 1, N1} respective photodiodes PD.

Subsequently, reading of the second row of N pixels P _{2,1 to P 2, N} charges generated in the photodiodes PD accumulated in the junction capacitance portion is performed as follows.

In time t ₂₁ after the time when the column selection control signal Hsel (N ₁ ) once becomes high level after the time t _{20 when the} column selection control signal Hsel (1) becomes high level in the above-described operation. period up, reset control signal reset to be output to the reset wiring _{L R} from the controlling section 6 becomes the high level, thereby, in the N integrating circuits _S 1 to S _N, respectively, the discharge switch _{SW 21} closes integrating capacitive element _{C 21} is discharged. Further, the period from the time _{t 22} after the time _{t 21} to time _{t 25,} the second row selection control signal Vsel (2) a high level output from the control section 6 to the second row selecting wiring _{L V, 2} next, thereby, the second row of N pixels _P 2,1 _{to P} in the photodetecting section 10 _{2, N} the readout switch SW ₁ in each of closed.

Within this period (t _{22 to} t ₂₅ ), during the period from time t ₂₃ to time t ₂₄ , the holding control signal Hold that is output from the control unit 6 to the holding wiring L _H becomes high level. In each of the holding circuits H _{1 to} H _N , the input switch SW ₃₁ is closed.
Of the column selection control signals Hsel (1) to Hsel (N) output from the control unit 6 to the column selection wirings L _{H, 1 to} L _{H, N} after the period (t _{22 to} t ₂₅ ), Column selection control signals Hsel (3) to Hsel corresponding to the consecutive N ₁ columns whose positions are shifted from the N ₁ column of the _first row by a fixed number of columns (2 columns in this embodiment). (N ₁ +2) sequentially becomes a high level only for a certain period. Thus, _{N 1} pieces of holding circuit _H 3 _{~H N1 + 2} respective output switch _{SW 32} is sequentially for a predetermined period close. As described above, the voltage value _{V out} indicating the received light intensity in the second row of the _{N 1} pixels _P 2,3 _{to P 2, N1 + 2} each photodiode PD is output to the voltage output wiring _{L out.}

In the second imaging mode, following the operations for the first row and the second row as described above, the positions of consecutive N ₁ columns that are voltage value output targets from the third row to the M-th row thereafter. The same operation is performed while shifting a certain number of columns for each row, and frame data representing an image obtained by one imaging is obtained. When the operation for the Mth row is completed, the same operation is performed again in the range from the first row to the Mth row, and frame data representing the next image is obtained. As described above, by repeating the same operation at a constant period, the voltage value _Vout representing the two-dimensional intensity distribution of the light image received by the light receiving unit 10 is output to the voltage output wiring _Lout , and the frame data is repeatedly generated. Is obtained.

  By the way, in this embodiment, in order to read out pixel data at high speed, the signal reading unit 20 and the A / D conversion unit 30 are divided into a plurality of sets, and pixel data is output from each set in parallel. Also good.

For example, as shown in FIG. 20, N integrating circuits S _{1 to} S _N and N holding circuits H _{1 to} H _N are divided into four sets, and integrating circuits S _{1 to} S _i and holding circuit H ₁ are divided. ˜H _i is a first set, the signal reading unit 22 consisting of integrating circuits S _{i + 1 to} S _j and holding circuits H _{i + 1 to} H _j is a second set, and integrating circuits S _{j + 1 to} S _k and The signal reading unit 23 including the holding circuits H _{j + 1 to} H _k is a third group, and the signal reading unit 24 including the integrating circuits S _{k + 1 to SN} and the holding circuits H _{k + 1 to} H _N is a fourth group. Here, “1 <i <j <k <N”. The voltage values sequentially output from the holding circuits H _{1 to} H _i of the signal reading unit 21 are converted into digital values by the A / D conversion unit 31, and the holding circuits H _{i + 1 to} H _{j of the} signal reading unit 22 are respectively converted. Are sequentially converted into digital values by the A / D converter 32, and voltage values sequentially output from the holding circuits H _{j + 1 to} H _{k of} the signal reading unit 23 are converted into A / D converters 33. Are converted into digital values, and voltage values sequentially output from the holding circuits H _{k + 1 to} H _{N of} the signal reading unit 24 are converted into digital values by the A / D conversion unit 34. In addition, A / D conversion processing in each of the four A / D conversion units 31 to 34 is performed in parallel. In this way, pixel data can be read out at a higher speed.

For example, in consideration of binning reading of 2 rows and 2 columns, a holding circuit corresponding to an odd number column among _N holding circuits H _{1 to} H _N is set as a first set, and a holding circuit corresponding to an even number column It is also preferable that an A / D converter is provided for each of the first and second sets, and the two A / D converters are operated in parallel. In this case, a voltage value is simultaneously output from the holding circuit corresponding to the odd-numbered column and the holding circuit corresponding to the adjacent even-numbered column, and these two voltage values are simultaneously subjected to A / D conversion processing to obtain a digital value. Is done. When the binning process is performed, these two digital values are added. In this way, pixel data can be read out at high speed.

  Note that the above-described division cannot be performed for the scanning process in the column direction by the scanning shift register 40. This is because in the scanning process in the column direction, it is necessary to sequentially scan from the first pixel to the last pixel. Therefore, by increasing the number of columns N to the number of rows M in the solid-state imaging device 1, the effect of speeding up the reading by dividing the signal reading unit as described above can be obtained more remarkably.

  The medical X-ray imaging system according to the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, in the above embodiment, the imaging region in the second imaging mode is an imaging region that is inclined with respect to both the row direction and the column direction of the light receiving unit and has a direction that intersects the moving direction of the solid-state imaging device as the longitudinal direction. Although illustrated, the imaging area in the second imaging mode may be an area other than this, or the entire surface of the light receiving unit may be used as the imaging area. Further, the first imaging mode is not limited to the mode in which the entire surface of the light receiving unit is used as the imaging region as in the above embodiment, and an arbitrary region in the light receiving unit may be used as the imaging region as necessary.

DESCRIPTION OF SYMBOLS 1 ... Solid-state imaging device, 3 ... Semiconductor substrate, 4 ... Scintillator, 5 ... X-ray shielding part, 6 ... Control part 10, 110, 130 ... Light receiving part, 10a, 10b ... Imaging area, 11 ... Light receiving surface, 20, DESCRIPTION OF SYMBOLS 120,140 ... Signal reading part, 30,31-34 ... A / D conversion part, 40 ... Scanning shift register, 41 ... Reading shift register, 100 ... X-ray imaging system, 104 ... Swivel arm, 106 ... X-ray generator , 108 ... rotation controller, A ... subject, A 2 _{... amplifier, C} 21, C _{22 ...} integrating capacitive element, C 3 _... holding capacitive _{element, H} 1 to H N _... holding circuit, for L G _... gain setting Wiring, L _H ... holding wiring, L _{H, n} ... n-th column selection wiring, L _{O, n} ... n-th column reading wiring, L _out ... voltage output wiring, L _R ... reset wiring, L _{V , M} to m-th row selection wiring, P, P _{m, n} ... Reset, reset control signal, S _{1 to} S _N ... integration circuit, SW ₁ ... read switch, SW ₂₁ ... discharge switch, SW ₂₂ ... gain setting switch, SW ₃₁ ... input switch, SW ₃₂ ... output Switch, W ... silicon wafer.

Claims (8)

A medical X-ray imaging system including a solid-state imaging device that captures an X-ray image while moving around a subject,
The solid-state imaging device is
A light receiving unit having a rectangular light receiving surface in which M × N pixels (M and N are integers of 2 or more) each including a photodiode are two-dimensionally arranged in M rows and N columns;
N readout wirings arranged for each column and connected via the readout switch to the photodiodes included in the pixels of the corresponding column;
A signal reading unit that holds a voltage value corresponding to the amount of charge input through the read wiring and sequentially outputs the held voltage value;
In addition to controlling the opening / closing operation of the readout switch of each pixel, the output operation of the voltage value in the signal readout unit is controlled, and the voltage value corresponding to the amount of charge generated in the photodiode of each pixel is set to the signal. A control unit for outputting from the reading unit;
A scintillator that generates scintillation light according to incident X-rays, converts the X-ray image into an optical image, and outputs the optical image to the light receiving unit;
Both the row direction and the column direction of the light receiving unit are inclined with respect to the moving direction of the solid-state imaging device,
The number M of rows in the light receiving section is smaller than the number N of columns, the shape of the light receiving surface is a rectangular shape whose longitudinal direction is the row direction, and the direction along the diagonal of the rectangle intersects the moving direction of the solid-state imaging device. And
The control unit controls an output operation of the signal reading unit so that a voltage value is selectively read from the pixels constituting an imaging region having a predetermined direction as a longitudinal direction among the M × N pixels. ,
The medical X-ray imaging system , wherein the predetermined direction is inclined with respect to both a row direction and a column direction of the light receiving unit and intersects a moving direction of the solid-state imaging device . A medical X-ray imaging system including a solid-state imaging device that captures an X-ray image while moving around a subject,
The solid-state imaging device is
A light receiving unit having a rectangular light receiving surface in which M × N pixels (M and N are integers of 2 or more) each including a photodiode are two-dimensionally arranged in M rows and N columns;
N readout wirings arranged for each column and connected via the readout switch to the photodiodes included in the pixels of the corresponding column;
A signal reading unit that holds a voltage value corresponding to the amount of charge input through the read wiring and sequentially outputs the held voltage value;
In addition to controlling the opening / closing operation of the readout switch of each pixel, the output operation of the voltage value in the signal readout unit is controlled, and the voltage value corresponding to the amount of charge generated in the photodiode of each pixel is set to the signal. A control unit for outputting from the reading unit;
A scintillator that generates scintillation light in accordance with incident X-rays, converts the X-ray image into an optical image, and outputs the optical image to the light receiving unit;
Have
Both the row direction and the column direction of the light receiving unit are inclined with respect to the moving direction of the solid-state imaging device,
The number M of rows in the light receiving unit is smaller than the number N of columns, and the shape of the light receiving surface is a rectangular shape whose longitudinal direction is the row direction. And
After the voltage value of the pixel is read from the signal reading unit and stored as data,
An image is constructed by selectively using the data corresponding to the pixels constituting the imaging region having a predetermined direction as a longitudinal direction,
The medical X-ray imaging system , wherein the predetermined direction is inclined with respect to both a row direction and a column direction of the light receiving unit and intersects a moving direction of the solid-state imaging device . Medical X-ray imaging system according to claim 1 or 2, wherein the predetermined direction is perpendicular to the moving direction of the solid-state imaging device, it is characterized. The medical X-ray imaging system according to any one of claims 1 to 3 , wherein the imaging region is a region on the diagonal line of the light receiving unit. When the control unit controls the output operation of the signal reading unit, among the voltage values held corresponding to the N columns of the light receiving unit, it corresponds to consecutive N ₁ columns (N ₁ <N). the voltage value held by the output from the signal readout section, and the position of the N ₁ columns in the light receiving portion, is shifted by a predetermined number of columns each time of reading a voltage value corresponding to one or more rows The medical X-ray imaging system according to claim 1 . The medical X-ray imaging system according to any one of claims 1 to 5 , wherein a length of the imaging region in the predetermined direction is 15 cm or more. The solid-state imaging device further includes a pixel formed around the light receiving unit and an X-ray shielding unit that covers the pixel, and a region serving as the light receiving unit is formed by a rectangular opening of the X-ray shielding unit. Is defined,
The medical X-ray imaging system according to any one of claims 1 to 6 , wherein each side of the opening is inclined with respect to the moving direction. The signal readout unit has N integration circuits for accumulating charges inputted through the N readout wirings and outputting a voltage value corresponding to the amount of the accumulated charges;
The medical X-ray imaging according to any one of claims 1 to 7 , wherein a gain of each integration circuit can be changed in accordance with the amount of the electric charge input through each readout wiring. system.

Images