JP2006128645A - Imaging apparatus, radiation imaging apparatus, and radiation imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an imaging apparatus and a radiation imaging apparatus in which the reset method of a conversion element is improved and a numerical aperture is enhanced while simplifying the wiring. <P>SOLUTION: The imaging apparatus comprises a plurality of pixels arranged on an insulating substrate wherein each pixel includes a conversion element, a first switching element connected with the conversion element in order to transfer an electric signal obtained from the conversion element, and a second switching element connected with the conversion element in order to reset the conversion element by applying a constant potential. The second switching element has a gate electrode and a source or a drain electrode being connected electrically with the gate electrode. A radiation imaging apparatus is also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus that converts an image into an electrical signal, and more particularly to a radiation imaging apparatus that detects radiation such as X-rays and γ-rays. Radiation imaging apparatuses are applied to medical image diagnostic apparatuses, nondestructive inspection apparatuses, analyzers using radiation, and the like.

  Conventionally, imaging methods used in medical image diagnosis are roughly classified into general imaging for obtaining still images and fluoroscopic imaging for obtaining moving images. Each photographing method is selected including a photographing device as necessary.

  General photography, that is, a method of obtaining a still image includes a method of fixing a film after exposing and developing the film using a screen film system (hereinafter abbreviated as S / F) in which a fluorescent plate and a film are combined. Alternatively, after recording a radiographic image as a latent image on the photostimulable phosphor, the photostimulable phosphor is scanned with a laser, and the output light output information is read by a sensor (computing radiography, hereinafter referred to as CR). (Abbreviation) The method is general. However, both methods have a drawback that the workflow for obtaining the radiation image is complicated. In both methods, digitization of radiographic images is possible indirectly but lacks immediacy. Furthermore, considering the digitized environment such as CT and MRI used in other medical image diagnosis, it is difficult to say that both methods are sufficiently consistent with CT and MRI.

  In addition, an image intensifier (hereinafter abbreviated as I.I) using an electron tube is mainly used for fluoroscopic imaging, that is, a moving image. However, since the electron tube is used, not only the apparatus becomes large-scale, but also the visual field region, that is, the detection area is small, and there is a strong demand for a large area in the medical image diagnostic field. Furthermore, due to problems in the apparatus configuration, the obtained moving image has a lot of crosstalk, and an improvement to a clear image is expected.

  On the other hand, the following proposals have been made in Patent Document 1 at the present time when the progress of liquid crystal TFT technology and the improvement of information infrastructure have been enhanced. A sensor array including a photoelectric conversion element using non-single crystal silicon, for example, amorphous silicon (hereinafter abbreviated as a-Si) and a switch TFT is used. A flat panel detector (hereinafter abbreviated as FPD) has been proposed as a radiation imaging apparatus in which the sensor array is combined with a phosphor that converts radiation into visible light or the like. With such FPD, the possibility of digitizing large-area radiation images has emerged.

  This FPD can read a radiation image instantly and display it on a display instantly, and the image can be directly taken out as digital information. Therefore, it has a feature that it is convenient to store, process, and transfer image data. In addition, although various characteristics such as sensitivity depend on imaging conditions, it has been confirmed that they are equivalent to or higher than conventional S / F imaging methods and CR imaging methods.

  FIG. 16 is a schematic equivalent circuit diagram of the FPD.

  In the figure, 101 is a photoelectric conversion element portion, 102 is a transfer TFT, 103 is a transfer TFT drive wiring, 104 is a signal line, 105 is a sensor bias wiring, 106 is a signal processing circuit, 107 is a TFT drive circuit, and 108 is an A / D. It is a conversion unit.

  Radiation such as X-rays enters from the top of the page and is converted into visible light by a phosphor (not shown). The converted visible light is converted into electric charge by the photoelectric conversion element unit 101 and accumulated in the photoelectric conversion element unit 101. After that, the TFT driving circuit 107 operates the transfer TFT 102 from the TFT driving wiring, transfers the accumulated charge to the signal line 104, is processed by the signal processing circuit 106, and is further A / D converted by 108 and output. The

  Basically, the element configuration as described above is common, and in particular, the photoelectric conversion element is proposed by various elements such as a PIN photodiode or an MIS photosensor employed by the present inventors. Has been.

  FIG. 17 is a schematic plan view of one pixel when the photoelectric conversion element is an MIS photosensor.

  201 is a MIS type photosensor, 202 is a transfer TFT, 203 is a transfer TFT drive wiring, 204 is a signal line, 205 is a sensor bias wiring, 211 is a transfer TFT gate electrode, and 212 is a transfer TFT source / drain electrode (hereinafter referred to as SD electrode). (Abbreviation) 213 is a contact hole.

  FIG. 18 is a cross-sectional view schematically showing the elements in one pixel shown in FIG.

  Reference numeral 301 denotes an insulating substrate such as a glass substrate, 302 denotes a transfer TFT drive wiring, 303 denotes a lower electrode of a MIS type photosensor, 304 denotes a transfer TFT gate electrode, 305 denotes a gate insulating film, 306 denotes an intrinsic a-Si film, and 307 denotes A hole blocking layer, 308 is a sensor bias wiring, 309 is an SD electrode of a transfer TFT, 310 is a signal line, 320 is a protective film, 321 is an organic resin layer, and 322 is a phosphor layer.

  As is apparent from FIGS. 17 and 18, since the MIS type photosensor and the TFT that is the transfer switching element have the same layer structure, the manufacturing method is simple, and there is an advantage that a high yield and a low price can be realized. Furthermore, it is evaluated that various characteristics such as sensitivity can be sufficiently satisfied. For this reason, as a device used for general photography, the above-described FPD has been adopted instead of the conventional S / F method and CR method.

  However, the above-mentioned FPD has a large area and is completely digitized, and is starting to be used mainly for general photography. However, it is still sufficient in terms of reading speed for fluoroscopic photography. It is not a situation.

  FIG. 19 is a 1-bit equivalent circuit diagram of an FPD using a MIS type photosensor.

In the figure, C ₁ is a combined capacitance of the MIS type photosensor, C ₂ is a parasitic capacitance formed on the signal line, Vs is a sensor bias potential, Vr is a sensor reset potential, and SW ₁ is Vs / Vr switching of the MIS type photosensor. SW, SW ₂ is an ON / OFF switch for the transfer TFT, SW ₃ is a signal line reset switch, and Vout is an output voltage.

The MIS type photosensor is supplied with a potential Vs by SW ₁ so that the semiconductor layer is depleted as a bias potential. In this state, when converted light from the phosphor enters the semiconductor layer, positive charges blocked by the hole blocking layer are accumulated in the a-Si layer, and a potential difference Vt is generated. Thereafter, the ON voltage of the transfer TFT is applied from SW _{2 and} is output as voltage Vout. The output Vout is read by a reading circuit (not shown), and then the signal wiring is reset by SW _{3 and} reading is sequentially performed.

By sequentially turning on the transfer TFT for each line (row) in accordance with the above-described driving method, all reading of one frame is completed. Thereafter, the reset potential Vr is applied from the SW ₁ to the MIS type photosensor, reset is performed, the bias potential Vs is applied again, and the image reading accumulation operation starts.

For example, in an FPD having a pixel size of 160 μm and a pixel area of 43 cm × 43 cm, the combined capacitance C ₁ of the MIS photosensor is about ₁ pf, and the parasitic capacitance C ₂ is about 50 pf. transfer the remaining about 2% is generated in C _1. Therefore, at the time of shooting, the above-described reset operation is indispensable for maintaining the image quality.

  Specifically, this reset operation requires about 10 msec to several tens msec for each frame. Of course, it depends on the reset condition. In other words, in order to realize fluoroscopic imaging that requires high-speed reading of about 30 frames per second (hereinafter abbreviated as 30 FPS) or more, reading processing of all lines within one frame 33 msec (30 FPS) It is necessary to perform reset processing and the like.

  FIG. 20 is a schematic diagram illustrating a driving method.

In the figure, T ₁ is one line read like processing time, T ₂ is read like processing time of all the lines, T ₃ is reset or the like processing time, T is a 1-frame processing time.

As described above, if necessary the following one-frame processing time T is 33 msec, if the reset or the like processing time _{T 3} and 15 msec, _{T 2} is next to 18 msec, reading assigned to one line when the load 1500 lines, etc. processing time _{T 1} becomes 12μsec. The radiation exposure time, i.e., put a sensor accumulation time, further, reading such processing time T ₁ is limited. As a result, it is necessary to improve the capability of the transfer TFT, which leads to an increase in the size of the TFT at the expense of the aperture ratio, and conversely problems such as a decrease in sensitivity, a decrease in image quality, and an increase in radiation dose. Many points occur.

  That is, high-speed moving image driving and image quality are in a trade-off relationship, and at present, high-quality high-speed moving images cannot be obtained.

  Although the case where the MIS type photosensor is used has been described above, basically, the processing time such as reset is a problem for moving image driving in the PIN type photodiode as well.

Therefore, a plurality of pixels including a conversion element that converts radiation into an electrical signal, a signal transfer element connected to the conversion element, and a reset element that performs a reset operation by applying a constant potential to the conversion element are provided. Yes. Patent Document 2 discloses an FPD in which a signal transfer element and a reset element are both connected to a pixel electrode of a conversion element. This is intended to improve the sensor reset method in the conventional FPD and achieve a large area and complete digitization not only in general photography but also in fluoroscopic photography. In addition, an object of the present invention is to provide a highly reliable radiation imaging apparatus, in particular, an optimal sensor reset switch arrangement by improving the aperture ratio and realizing reliable high-speed moving image reading.
JP 08-116044 A JP 2003-218339 A

  In the apparatus disclosed in Patent Document 2, resetting is performed for each line of a plurality of pixels, and it becomes possible to reset the sensor of the already read line during reading of one line, thereby improving the aperture ratio. And high-speed video drive. However, it is further desired to improve the aperture ratio and realize high functionality such as reliable high-speed moving image drive at a low price.

  An object of the present invention is to simplify the wiring and improve the aperture ratio when improving the sensor reset method and realizing high-speed moving image reading.

  The imaging device of the present invention is an imaging device having a plurality of pixels arranged on an insulating substrate, and each of the pixels transfers the electrical signal obtained by the conversion element and the conversion element. A first switching element connected to the conversion element; and a second switching element connected to the conversion element to reset the conversion element by applying a constant potential to the conversion element, The switching element 2 has a gate electrode and a source or drain electrode, and one of the source or drain electrode and the gate electrode are electrically connected.

  The radiation imaging apparatus of the present invention is a radiation imaging apparatus having a plurality of pixels arranged on an insulating substrate, wherein each of the pixels converts the incident radiation into an electrical signal corresponding to the radiation. An element, a first switching element connected to the conversion element for transferring the electrical signal, and connected to the conversion element to reset the conversion element by applying a constant potential to the conversion element A second switching element, wherein the second switching element has a gate electrode and a source or drain electrode, and one of the source or drain electrode and the gate electrode are electrically connected. It is what.

  According to the present invention, reset is performed for each line of a plurality of pixels, and it becomes possible to reset a sensor of a line that has already been read out during reading of one line. At the same time, the reset switching element supplies the reset voltage from the gate wiring because one of the gate electrode and the source electrode or the drain electrode is connected. As a result, the wiring can be simplified to improve the aperture ratio, and high functionality such as high-speed moving image driving can be realized at a low price.

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

  Hereinafter, each embodiment is an example in which the radiation imaging apparatus is applied as an FPD. However, Embodiments 1, 2, and 4 can also be applied as a solid-state imaging apparatus that converts an optical image other than radiation into an electrical signal. Further, the present invention can be applied to a solid-state imaging device in which pixels having signal conversion elements, transfer TFTs, and reset TFTs are arranged in a two-dimensional shape (matrix shape).

[Embodiment 1]
In this embodiment, a radiation imaging apparatus using a MIS photosensor will be described.

  FIG. 1 is a schematic equivalent circuit diagram of 3 × 3 pixels in the radiation imaging apparatus of the present embodiment. In the figure, 11 is a conversion element that is a MIS type photosensor, 12 is a transfer switching element such as a TFT, 13 is a drive wiring for the transfer switching element, 14 is a signal wiring, 15 is a sensor bias wiring, and 16 is a signal processing circuit. , 17 is a drive circuit, 18 is an A / D converter, 19 is a reset switching element such as a TFT, and 20 is a drive wiring for the reset switching element.

  Radiation such as X-rays is converted into visible light by a wavelength converter (not shown) and enters the conversion element 11. The wavelength converter is a scintillator such as CsI or GOS. The incident light is photoelectrically converted by the conversion element, and signal charges are accumulated in the conversion element. Thereafter, the transfer switching element 12 is turned on to read an image signal corresponding to the signal charge. Thereafter, the reset switching element 19 is turned on to reset the conversion element.

FIG. 2 is an equivalent circuit diagram of 3 × 1 pixels of the radiation imaging apparatus according to the present embodiment. In the figure, the reference numerals are the same as those in FIG. The ON voltage of the transfer switching element (TT ₁ ) is applied by Vgt (1), and is output as an image signal through the signal wiring 14. Next, the ON voltage of the reset switching element (TR ₁ ) is applied by Vgr (1), and the conversion element is reset. Similarly, the ON voltage of the next transfer switching element (TT ₂ ) is applied by Vgt (2) and is output via the signal wiring 14. Next, the ON voltage of the reset switching element (TR ₂ ) is applied from Vgr (2), and the conversion element is reset. In FIG. 2, the moving image can be read by repeating the above operation from the upper side to the lower side of the drawing.

FIG. 3 is a schematic diagram illustrating a driving method in the present embodiment. In the figure, S ₁ is 1-line readout process or the like time, S ₂ is 1 line reset processing such time, S ₃ is the one-line transfer, reset processing such as time, the accumulation time of the conversion element S ₄ is one line, S is one frame processing time.

  This embodiment can be compared with the conventional method in which all the conversion elements are collectively reset after sequential readout and the radiation exposure is repeated, and readout, conversion elements can be reset and accumulated for each line. Therefore, it can be driven substantially by the total reading time. That is, at the same time that one line is performing a read operation, the sensor of the line that has already been read is reset. As a result, high-speed moving image driving of 30 FPS or higher can be realized without degrading image quality.

  Further, the reset potential Vrr of the pixel electrode of the conversion element is applied by directly connecting the gate electrode and the source or drain electrode of the reset switching element. That is, since one of the gate electrode and the source or drain electrode of the reset switching element has a direct connection structure, it is not necessary to further arrange a reset wiring for applying the reset potential Vrr, and thus it is possible to prevent a decrease in the aperture ratio. Become. Further, the reset potential Vrr may be composed of a plurality of potentials. For example, a high potential Vrr is applied in order to sufficiently reset the conversion element, and then a predetermined Vrr is applied for accumulation, so that the conversion element is composed of a plurality of reset potentials, that is, a driving voltage of a plurality of reset switching elements. There is also a case.

  FIG. 4 is a plan view of one pixel of this embodiment. In the figure, the reference numerals are the same as those in FIG. The transfer switching element 12 and the reset switching element 19 are arranged at pixel diagonal positions from the viewpoint of improving the layout efficiency of the drive wiring and signal wiring.

  FIG. 5 is a schematic cross-sectional view taken along the line AA in FIG.

  Next, a method for manufacturing the FPD of this embodiment will be described.

  6A to 6D are diagrams illustrating a method for manufacturing the FPD in the present embodiment.

  In the first step, on the insulating substrate such as a glass substrate, the drive wiring 13 of the transfer switching element that is a TFT, the gate electrode of the transfer switching element, and the pixel electrode 21 of the conversion element that is an MIS photosensor, Further, a driving wiring 20 for the reset switching element, which is a TFT, and a chromium thin film as a gate electrode of the reset switching element are formed by a sputtering apparatus, and a pattern is formed by photolithography. FIG. 6A shows a schematic plan view of one pixel.

  In the second step, the transfer switching element, which is a TFT, the switching element for reset, and the conversion element, which is a MIS type photosensor, include a gate insulating film made of SiN, a semiconductor layer made of an a-Si film, and a phosphorus-doped n + film. Impurity semiconductor layers are respectively formed by a plasma CVD apparatus.

  In the third step, contact holes 22 and 23 are formed by photolithography using RIE (Reactive Ion Etching) or CDE (Chemical Dry Etching). FIG. 6B shows a schematic plan view of one pixel.

  In the fourth step, an aluminum thin film 1 μm is formed by a sputtering apparatus as SD electrodes 24 and 25, signal wirings 14 and sensor bias wirings 15 of transfer switching elements and reset switching elements which are TFTs, and a pattern is formed by photolithography. Form. FIG. 6C shows a schematic plan view of one pixel.

  In the fifth step, the impurity semiconductor layer in the gap portion of the transfer switching element and the reset switching element which are TFTs is removed by RIE.

  In the sixth step, the elements are separated from each other by photolithography using RIE. FIG. 6D shows a schematic plan view of one pixel.

  In the seventh step, a SiN film is formed as a protective film by a plasma CVD apparatus, and the wiring lead-out portion and the like are exposed by photolithography using RIE.

  In the eighth step, the scintillator is attached on the conversion element by bonding with an adhesive or the like. As described above, the FPD of the present invention is manufactured.

[Embodiment 2]
This embodiment is for improving sensitivity, in other words, improving the aperture ratio and simplifying the TFT drive circuit, compared to the first embodiment.

  FIG. 7 is a schematic equivalent circuit diagram of 3 × 3 pixels in the present embodiment. In the figure, 11 is a conversion element which is a MIS type photosensor, 12 is a transfer switching element made of TFT, 31 is a drive wiring for driving the transfer switching element and the reset switching element, 14 is a signal wiring, Sensor bias wiring, 16 is a signal processing circuit, 17 is a drive circuit, 18 is an A / D converter, and 19 is a reset switching element made of TFT.

  X-rays are converted into visible light by a phosphor (not shown) and enter the conversion element 11. Incident light is photoelectrically converted, and signal charges are accumulated in the conversion element. Thereafter, the transfer switching element 12 is turned on to read an image signal corresponding to the signal charge. Thereafter, the reset switching element 19 is turned ON at the timing when the subsequent transfer switching element operates, and the conversion element is reset.

Next, FIG. 8 is an equivalent circuit diagram of 3 × 1 pixels in the present embodiment. In the figure, the reference numerals are the same as those in FIG. An ON voltage of the transfer switching element (TT ₁ ) is applied from Vg (1), and is output as an image signal through the signal wiring 14. Next, the ON voltage of the reset switching element (TR ₁ ) is applied from Vg (2), and the conversion element is reset. At the same time, an ON voltage is applied to the transfer switching element (TT ₂ ), and similarly, the next image signal is output via the signal wiring 14. Next, the ON voltage of the reset switching element (TR ₂ ) is applied from Vg (3), and the conversion element is reset. By repeating the above operation, the moving image can be read.

FIG. 9 is a schematic diagram illustrating a driving method in the present embodiment. In the figure, S ₁ is 1-line readout process or the like time, S ₂ is 1 line reset processing such time, S ₃ is the one-line transfer, reset processing such as time, the accumulation time of the conversion element S ₄ is one line, S is one frame processing time.

  Compared with the present embodiment and the conventional method, readout, reset, and accumulation are performed for each line, so that the readout time of one image can be driven by the total readout time per row. As a result, high-speed moving image driving of 30 FPS or higher can be realized without degrading image quality. That is, the feature of this embodiment is a configuration in which the former-stage reset switching element and the latter-stage transfer switching element are simultaneously turned on from the same drive wiring as described above, and the gate electrode of the reset switching element The source or drain electrode is directly connected. Therefore, although the structure has two switching elements in one pixel, it is possible to realize the same number of wirings as the structure having one switching element in one pixel. As a result, functional improvement can be achieved without reducing the aperture ratio.

  FIG. 10 is a plan view of one pixel in the present embodiment. In the figure, the reference numerals are the same as those in FIG. The transfer switching element 12 and the reset switching element 19 made of TFTs are arranged at pixel diagonal positions in terms of the layout of drive wiring, signal wiring, and the like. In addition, because of the structural features, the transfer switching element and the reset switching element have the same operation time, and therefore, the operation capabilities of the transfer switching element and the reset switching element are not necessarily the same, and the operation is performed with at least two types of operation voltages. There is a need.

  FIG. 11 is a diagram illustrating an example of an operating voltage profile of a TFT serving as each switching element. In the figure, the A region is a voltage considered for the transfer switching element, and the B region is a voltage considered for the reset switching element. This is for setting the lower electrode of the MIS type photosensor, which is a conversion element, to a predetermined potential Vrr as described in the first embodiment. Of course, it is not necessarily stepwise so that the predetermined voltage is finally obtained. Basically, any voltage profile can be used as long as the reset switching element can realize a predetermined voltage following the voltage profile for operating the transfer switching element.

  In the present embodiment, the number of drive wirings for driving the switching elements is the same as that of the conventional one, high-speed moving images can be made without greatly changing the peripheral circuit, and the manufacturing method is the same as in the first embodiment. It is simple.

[Embodiment 3]
In the present embodiment, a case will be described where the radiation is directly converted into electric charges by a radiation direct conversion unit, stored, and read out using a transfer switching element, which is applied to a so-called direct conversion method.

  FIG. 12 is a schematic equivalent circuit diagram of 3 × 3 pixels in the present embodiment. In the figure, 41 is an individual electrode for collecting charges generated in a conversion element that directly converts radiation, 43 is a storage capacitor, 42 is a transfer switching element made of TFT, 45 is a transfer switching element and a reset switching element. A driving wiring for driving, 44 a signal wiring, 46 a signal processing circuit, 47 a driving circuit, 48 an A / D converter, and 49 a reset switching element made of a TFT.

  FIG. 13 shows a schematic cross-sectional view in the present embodiment. Reference numeral 51 denotes an insulating substrate such as a glass substrate, 52 denotes GaAs which is a conversion element for directly converting radiation, 60 denotes a common electrode, and 41 denotes an individual electrode. 53 is a bump connection portion made of a conductive resin, 61 is a gate electrode of a transfer switching element and a reset switching element, 55, 56 and 57 are gate insulating films, semiconductor layers, impurity semiconductor layers of both switching elements, Reference numeral 62 denotes a lower electrode of the storage capacitor. 54 is an interlayer insulating film, and 58 and 59 are source or drain electrodes of a transfer switching element and a reset switching element.

  The X-rays are directly converted into electric charges by the conversion element 52, collected by the individual electrodes 41, and stored in the storage capacitor 43 via the bump connection portion 53. Thereafter, the signal is read from the signal wiring 44 by turning on the transfer switching element 42. After that, the transfer switching element 42 in the subsequent stage is turned ON, and at the same time, the reset switching element 49 is turned ON to reset the conversion element and the storage capacitor. In addition, you may use amorphous selenium as a radiation direct conversion part.

  This embodiment also has the same effect as the first and second embodiments, and a high-quality moving image can be easily obtained.

[Embodiment 4]
In this embodiment, an X-ray detection apparatus using a PIN photodiode as a conversion element will be described. The same effect as in the case of the MIS type photosensor can be obtained. In this embodiment, a PIN photodiode is stacked on a switching element array made of TFTs. The equivalent circuit is the same as that of the second embodiment, and has a structure in which the transfer switching element and the reset switching element in the previous row are connected by the same drive wiring.

  FIG. 14 is a schematic cross-sectional view in the present embodiment. In the figure, 71 is an insulating substrate such as a glass substrate, 72 is a gate electrode of a TFT as a transfer switching element, 73 is a gate electrode of a TFT as a reset switching element, 74 is a gate insulating film, and 75 is a-Si. , An impurity semiconductor layer, 77 and 78 source and drain electrodes of the transfer switching element and the reset switching element, 79 an interlayer insulating film, 80 a lower electrode of the conversion element, 81 an n layer, and 82 The i layer, 83 is a p layer, 84 is a protective film, 85 is a sensor bias wiring, 86 is a protective film, and 87 is a phosphor.

  In the present embodiment, considering the operation of the reset switching element, the lower electrode of the conversion element has an NIP structure, and the structure is limited by the driving method. In addition, because of the laminated structure, it is basically possible to arrange the conversion element on the wiring or the switching element, and a high aperture ratio can be achieved, but a low dielectric constant and a thick film interlayer can be achieved. This is because the parasitic capacitance is reduced by disposing an insulating film. As a result, there is a problem in reducing the price due to restrictions on materials and thick films. However, by reducing the number of wires as in this embodiment, the parasitic capacitance can be reduced, the degree of freedom in designing the interlayer insulating film is increased, and the parasitic capacitance is also reduced, resulting in higher functionality and lower cost. It can be achieved at the same time.

[Embodiment 5]
FIG. 15 is a diagram illustrating the radiation imaging system of the present embodiment. The radiation imaging system is an example in which the radiation imaging apparatus according to the first to fourth embodiments is applied as a radiation imaging system.

  The X-ray 6060 generated by the X-ray tube 6050 passes through the chest 6062 of the patient or subject 6061 and enters the radiation imaging apparatus 6040 that captures a radiation image. This incident X-ray includes information inside the body of the patient 6061. The scintillator (phosphor layer) of the radiation imaging apparatus 6040 emits light in response to the incidence of X-rays, and this is photoelectrically converted to obtain electrical information. This information can be digitally converted, image-processed by an image processor 6070, and observed on a display 6080 as display means in a control room.

  Further, this information can be transferred to a remote place by transmission means such as a telephone line 6090, and can be displayed on a display 6081 in a doctor room or the like in another place, or stored in a storage means such as an optical disk. Can also be diagnosed. It can also be recorded on the film 6110 by the film processor 6100.

  INDUSTRIAL APPLICABILITY The present invention is suitably used for an electromagnetic wave detection device for detecting electromagnetic waves including light such as visible light and infrared light, and radiation such as X-rays and γ-rays, in particular, a radiation detection device for detecting radiation such as X-rays and γ-rays. And applied to medical image diagnostic apparatuses, nondestructive inspection apparatuses, analyzers using radiation, and the like.

FIG. 3 is a schematic equivalent circuit diagram of 3 × 3 pixels in Embodiment 1 of the present invention. FIG. 3 is an equivalent circuit diagram of 3 × 1 pixels in Embodiment 1 of the present invention. It is a schematic diagram explaining the drive method in Embodiment 1 of this invention. It is a top view of 1 pixel of Embodiment 1 of the present invention. FIG. 5 is a schematic cross-sectional view taken along line AA in FIG. 4. It is a figure explaining the manufacturing method in Embodiment 1 of this invention. It is a typical equivalent circuit schematic of 3x3 pixel in Embodiment 2 of this invention. It is an equivalent circuit diagram of 3x1 pixel in Embodiment 2 of this invention. It is a schematic diagram explaining the drive method in Embodiment 2 of this invention. It is a top view of 1 pixel in Embodiment 2 of the present invention. It is a figure explaining the operating voltage profile of TFT in Embodiment 2 of this invention. It is a typical equivalent circuit schematic of 3x3 pixel in Embodiment 3 of this invention. It is typical sectional drawing in Embodiment 3 of this invention. It is typical sectional drawing in Embodiment 4 of this invention. It is a figure which shows the radiation imaging system of Embodiment 5 of this invention. It is a typical equivalent circuit schematic of conventional FPD. It is a typical top view of 1 pixel of the conventional MIS type photosensor (photoelectric conversion element). FIG. 18 is a cross-sectional view schematically showing elements in one pixel shown in FIG. 17. It is a 1-bit equivalent circuit diagram of a conventional FPD. It is the schematic diagram explaining the drive method of the conventional FPD.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Conversion element 12 Transfer switching element 13 Drive wiring of transfer switching element 14 Signal wiring 15 Sensor bias wiring 16 Signal processing circuit 17 Drive circuit 18 A / D converter 19 Reset switching element 20 Drive wiring of reset switching element

Claims (13)

An imaging device having a plurality of pixels arranged on an insulating substrate,
Each of the pixels includes a conversion element, a first switching element connected to the conversion element for transferring an electric signal obtained by the conversion element, and a constant potential applied to the conversion element. A second switching element connected to the conversion element for resetting
The imaging device, wherein the second switching element includes a gate electrode and a source or drain electrode, and one of the source or drain electrode and the gate electrode are electrically connected.   The imaging device according to claim 1, wherein the conversion element includes at least a first electrode, a second electrode, and a semiconductor layer disposed between the first electrode and the second electrode.   The imaging apparatus according to claim 1, wherein the first switching element includes a gate electrode and a source or drain electrode.   The imaging apparatus according to claim 3, wherein one of the source and drain electrodes of the first switching element and the other of the source and drain electrodes of the second switching element are connected to the first electrode of the conversion element.   The first switching element and the second switching element are disposed on the insulating substrate, and the conversion element is disposed on the first switching element and the second switching element with an insulating layer interposed therebetween. The imaging device according to claim 4.   The plurality of pixels are arranged in an array having a plurality of rows, and a gate electrode of the first switching element in a predetermined row and a gate electrode of the second switching element in a previous row are on the same drive wiring The imaging device according to claim 4 connected.   The imaging apparatus according to claim 6, wherein the drive voltage applied to the drive wiring has a plurality of on-voltage values.   2. The conversion element is a photoelectric conversion element using non-single crystal silicon for the semiconductor layer, and the first switching element and the second switching element are thin film transistors made of non-single crystal silicon. 8. The imaging device according to any one of items 7.   The imaging device according to any one of claims 1 to 7, wherein the conversion element uses a semiconductor material capable of directly converting radiation into electric charge in the semiconductor layer. A radiation imaging apparatus having a plurality of pixels arranged on an insulating substrate,
Each of the pixels includes a conversion element that converts incident radiation into an electrical signal corresponding to the radiation, a first switching element connected to the conversion element to transfer the electrical signal, and a constant in the conversion element. A second switching element connected to the conversion element to reset the conversion element by applying a potential;
The radiation imaging apparatus, wherein the second switching element includes a gate electrode and a source or drain electrode, and one of the source or drain electrode and the gate electrode are electrically connected.   The conversion element includes at least a first electrode, a second electrode, and a semiconductor layer disposed between the first electrode and the second electrode, and the first switching element includes a gate electrode and a source or drain. 11. The apparatus according to claim 10, further comprising an electrode, wherein one of the source and drain electrodes of the first switching element and the other of the source and drain electrodes of the second switching element are connected to the first electrode of the conversion element. The radiation imaging apparatus described.   The conversion element includes a photoelectric conversion element using non-single crystal silicon for the semiconductor layer, and a wavelength converter that converts incident radiation into light in a wavelength band that can be sensed by the photoelectric conversion element. The radiation imaging apparatus according to claim 10, wherein the switching element and the second switching element are thin film transistors made of non-single crystal silicon. A radiation imaging apparatus according to any one of claims 10 to 12, processing means for processing a signal from the radiation imaging apparatus, storage means for storing a signal from the processing means, and from the processing means A radiation imaging system comprising: transmission means for transmitting a signal; display means for displaying a signal from the processing means as an image; and a radiation source for generating the radiation irradiated to the radiation imaging apparatus.

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