JP4993794B2 - Radiation imaging apparatus, control method therefor, and radiation imaging system - Google Patents

Description

  The present invention relates to a radiation imaging apparatus that detects radiation including subject information, a control method thereof, and a radiation imaging system.

  The prior art will be described below with reference to the drawings. Conventionally, imaging methods used in medical image diagnosis are roughly classified into general imaging for obtaining a still image and fluoroscopic imaging for obtaining a moving image. Each photographing method is selected including a photographing device as necessary.

  In general photography, that is, a method for obtaining a still image, a screen film system in which a fluorescent plate and a film are combined is used. In this method, a method of fixing after exposing and developing a film, or a method of reading a radiation image by scanning a laser after recording a radiation image as a latent image on a photostimulable phosphor is generally used.

  However, in the above method, the workflow for obtaining the radiographic image is complicated and sometimes lacks immediacy.

  Also, an image intensifier is mainly used in fluoroscopic imaging, that is, a method for obtaining a moving image. However, in this method, since an electron tube is used, there are cases where the apparatus becomes large-scale, the visual field region is limited, distortion is large, and crosstalk is large.

  With such a background, a radiographic apparatus that obtains a good image in a large area is expected.

  In recent years, with the advancement of liquid crystal TFT technology, a flat panel type sensor has been proposed in which pixels made up of conversion elements and TFTs are two-dimensionally arranged using amorphous silicon or polysilicon formed on a glass substrate as a material. ing. The possibility of meeting the above expectations has emerged with flat panel sensors.

  This flat panel sensor can instantaneously read a radiation image and display it on a display. In addition, since images can be handled as digital information, data storage, processing, and transfer are convenient.

  A flat panel type sensor generally reads and transfers charges to a reading unit by performing matrix driving using a switching element such as a TFT on the charges converted by a conversion element. Further, examples of the conversion element used in the flat panel type sensor include a photoelectric conversion element such as a pin type photodiode or an MIS type sensor formed using amorphous silicon. When a photoelectric conversion element is used as the conversion element, it is used in combination with a phosphor as a scintillator for converting radiation into light in a wavelength band that can be sensed by the photoelectric conversion element. Another conversion element is an element capable of directly converting radiation using amorphous selenium or the like into electric charge. Here, as a conventional technique, a flat panel sensor using a MIS sensor as a photoelectric conversion element will be described.

  First, a cross-sectional structure of a pixel of a flat panel sensor 1300 used in a conventional radiation imaging apparatus will be described with reference to FIG. The MIS sensor 1301 of each pixel has a structure in which a lower electrode layer 1305, an insulating layer 1306, a semiconductor layer 1307, an impurity semiconductor layer 1308, and an upper electrode layer 1309 are stacked on an insulating substrate 1304 such as glass. The insulating layer 1306 can be formed using, for example, an amorphous silicon nitride film. The semiconductor layer 1307 can be formed using, for example, an amorphous silicon layer. The impurity semiconductor layer 1308 can be formed using, for example, an amorphous silicon n layer. The TFT 1302 serving as a switch element has a structure in which a gate electrode layer (lower electrode) 1310, an insulating layer 1306, a semiconductor layer 1307, an impurity semiconductor layer 1308, a drain electrode layer 1311, and a source electrode layer 1312 (upper electrode) are stacked. Similarly, an insulating layer 1306, a semiconductor layer 1307, an impurity semiconductor layer 1308, and a wiring (upper electrode) layer 1314 are stacked on the insulating substrate 1304 except that the lower electrode layer 1305 is not formed in the wiring portion 1303. Have a configuration. The lower electrode layer 1305 of the MIS type sensor 1301 and the drain electrode layer 1311 of the TFT 1302 are connected by a wiring layer or a contact hole (not shown). Above the MIS type sensor 1301 and the TFT 1302, a protective layer 1313 such as an amorphous silicon nitride film or polyimide covers the whole. According to this structure, since the MIS type sensor 1301 and the TFT 1302 have the same layer structure, the manufacturing method is simple.

  Here, the operation of the MIS sensor 1301 shown in FIG. 13 will be described with reference to the schematic circuit diagram of FIG. 14, the timing diagram of FIG. 15, and the energy band diagram of FIG.

  As shown in FIG. 14, the upper electrode 1309 of the MIS sensor 1301 is connected to a power source 1401 that can switch the potentials of Vs and Vr. Here, Vs is a potential applied to the MIS type sensor 1301 in order to make the MIS type sensor 1301 ready for a photoelectric conversion operation. Vr is a potential applied to the MIS sensor 1301 in order to remove either electrons or holes accumulated in the MIS sensor 1301 from the MIS sensor 1301. The lower electrode layer 1305 is connected to the drain electrode 1311 of the TFT 1302. A source electrode 1312 of the TFT 1302 is connected to an input of a read amplifier 1402 having a reset function. Further, the gate electrode 1310 of the TFT 1302 is connected to a gate driving device 1403 that controls on / off of the TFT 1302.

  Further, the operation of the MIS type sensor 1301 shown in FIG. 13 will be described with reference to FIGS. 14, 15, and 16 together. One of the features of the operation of the MIS type sensor 1301 is that two operations of a photoelectric conversion operation and a refresh operation are repeated.

  First, the photoelectric conversion operation will be described. As shown in the period a of FIG. 15 and FIG. 16A, the upper electrode layer 1309 of the MIS sensor 1301 is set to Vs, and the TFT 1302 is in the off state. When light is incident in this state, charges generated in the semiconductor layer 1307 are guided to each electrode by an electric field. That is, electrons are guided to the upper electrode layer 1309 and holes are guided to the lower electrode layer 1305 side, and remain at the interface of the insulating layer 1306. The potential of the lower electrode layer 1305 is increased by holes accumulated at the interface of the insulating layer 1306. This potential increase can be read by turning on the TFT 1302, as shown in a period b in FIG.

  On the other hand, when a large amount of light is incident on the MIS type sensor 1301 in the photoelectric conversion operation in the period a in FIG. 15, the holes accumulated in the interface of the insulating layer 1306 as shown in FIG. The electric field is weakened. As a result, the charge generated in the semiconductor layer 1307 is recombined without being guided to each electrode. That is, the photoelectric conversion operation cannot be performed. By performing a refresh operation, which will be described later, from this state, an electric field is applied to the semiconductor layer 1307 again, and a photoelectric conversion operation becomes possible.

  Next, the refresh operation will be described. As shown in the period c of FIG. 15 and FIG. 16C, the upper electrode layer 1309 of the MIS sensor 1301 is set to Vr. At the same time, since the TFT 1302 is turned on and the readout amplifier 1402 is reset, the lower electrode layer 1305 of the MIS sensor 1301 is fixed to the GND potential.

  In the refresh operation, the upper electrode 1309 is given a negative potential with respect to the lower electrode 1305. Accordingly, holes accumulated at the interface between the semiconductor layer 1307 and the insulating layer 1306 by the photoelectric conversion operation are guided to the upper electrode 1309 side and removed from the semiconductor layer 1307. Again, as shown in the period d in FIG. 15, by applying the Vs potential to the upper electrode 1309, the photoelectric conversion operation can be performed.

  The MIS sensor 1301 can continuously perform photoelectric conversion by repeating the photoelectric conversion operation and the refresh operation shown in the periods a to d in FIG.

  Next, the operation of a radiation imaging apparatus using a sensor array that performs matrix driving by two-dimensionally arranging pixels composed of MIS sensors and TFTs will be described. FIG. 17 is a schematic circuit diagram of a radiation imaging apparatus using a conventional flat panel sensor. FIG. 18 is a timing chart for explaining the operation of the conventional radiation imaging apparatus.

  As shown in FIG. 17, a conventional radiographic apparatus using a flat panel type sensor has two-dimensional pixels including MIS type sensors S11 to S33 and thin film transistors (TFTs) T11 to T33 formed using amorphous silicon. It has an array of sensor arrays. Matrix driving is performed with such a configuration. A power supply capable of switching between Vs during photoelectric conversion and Vr during refresh operation is connected to the common electrode (corresponding to the upper electrode 1309) side of the MIS type sensor of each pixel. Further, the gate electrodes of the TFTs T11 to T33 of each pixel are connected to common gate lines Vg1 to Vg3, and the common gate line is connected to a gate driving unit including a shift register (not shown). On the other hand, the source electrodes of the TFTs T11 to T33 are connected to the common signal lines Sig1 to Sig3, and are converted into output signals by a reading unit including a preamplifier, an analog multiplexer, a buffer amplifier, an A / D converter, and the like. The output signal is processed by an image processing unit including a memory, a processor (not shown), and is output to a monitor (not shown) or stored in a recording device such as a hard disk.

  Next, the operation of this radiation imaging apparatus will be described using the timing chart of FIG. Schematically, after performing the photoelectric conversion operation for the entire sensor array, the sequence for performing the refresh operation for the entire sensor array is repeated. First, the period of the photoelectric conversion operation will be described.

  Light including subject information is incident on the sensor array by the Light pulse in the period a, and charges corresponding to the subject information are accumulated at the interface between the semiconductor layer and the insulating layer of each MIS type sensor. In the subsequent period b, the reset switch provided in each preamplifier is turned on by the reset signal RC, and the integration capacitor and each common signal line of the preamplifier are reset. Subsequently, in a period c, a pulse is applied to the common gate line Vg1, the TFTs T11 to T13 connected to the common gate line Vg1 are turned on, and the signal charges generated in the MIS type sensors S11 to S13 are changed to the common signal lines Sig1 to Sig1. The data is transferred to the reading unit via Sig3. The transferred charge is converted into a voltage by a preamplifier connected to each signal line. Next, in the period d, the sample hold signal SH is applied to the sample hold circuit of the reading unit, and the voltage output from the preamplifier is sampled. Thereafter, the voltage sampled in the sample hold capacitor is serial-converted by an analog multiplexer in synchronization with a clock from a timing generator (not shown) and output as an analog signal via a buffer amplifier. The analog signal is input to the A / D converter, A / D converted in synchronization with AD_CLK, and input to an image processing unit (not shown) as a digital signal according to the resolution of the A / D converter.

  Subsequently, the same operation as in the periods b to d is performed on the pixels connected to the common gate line Vg2, and the charges of the MIS sensors S21 to S23 are read out through the TFTs T21 to T23. Further, the same operation is repeated for the pixels connected to Vg3, and the charge of the entire sensor array is read out. In this way, the period of the photoelectric conversion operation ends.

  Next, a refresh operation period will be described. First, in a period e, the read preamplifier is reset by RC, and the potential on the source electrode side of the TFT becomes GND. At the same time, a refresh operation potential Vr is applied to the common electrode of the MIS sensor, and all TFTs are turned on. As a result, the upper electrode of the MIS sensor has a negative potential with respect to the lower electrode, and the holes are refreshed. After that, in a period f, Vs is applied again to the common electrode of the MIS sensor, and a photoelectric conversion operation is possible.

  As described above, in the conventional radiographic apparatus shown in FIGS. 17 and 18, the photoelectric conversion operation of the entire sensor array and the refresh operation of the entire sensor array are alternately and continuously performed.

  The operation of the conventional radiation imaging apparatus that reads out the sensor array in which the MIS type sensor and the TFT are two-dimensionally arranged by matrix driving has been briefly described above.

  A radiation imaging apparatus having such a configuration is disclosed in Patent Document 1.

  On the other hand, since the above-described radiation imaging apparatus has an independent refresh operation period in addition to the photoelectric conversion operation period, it may be difficult to perform high-speed continuous photoelectric conversion. Specifically, the refresh operation of the entire sensor array requires about 10 ms to several tens of ms, and as a result, it may be difficult to apply to a radiographic apparatus used for fluoroscopic imaging.

  In order to improve this, a radiation imaging apparatus as shown in FIG. 19 has been proposed.

  The flat panel type sensor of FIG. 19 is characterized in that the pixel is composed of an MIS type sensor and two switch elements (transfer TFT and refresh TFT) as compared to FIG.

  In each pixel, the upper electrode of the MIS type sensor is connected to a sensor bias power source that applies Vs to the MIS type sensor via a common bias line. The lower electrode of the MIS type sensor is connected to the transfer TFT which is a transfer switch element and the drain electrode of the refresh TFT which is a refresh switch element. The source electrode of the transfer TFT is connected to the common signal lines Sig1 to Sig3, and the source electrode of the refresh TFT is connected to the refresh power supply Vr via the common refresh line. That is, the first switch element for transferring the electric charge converted by the conversion element for each pixel, and the second for initializing the conversion element in order to make the conversion element convertible close to the initial state. A separate switch element is prepared.

  The gate electrode of each transfer TFT is connected to the gate lines Vg1, Vg3, and Vg5. Further, the gate electrode of each refresh TFT is connected to the gate lines Vg2, Vg4, and Vg6, and Vg1 to Vg6 are connected to a gate drive unit including a shift register (not shown).

  Next, the operation of the radiation imaging apparatus of FIG. 19 will be described using the timing chart of FIG. In order to simplify the description, the reset RC pulse of the preamplifier and the sample hold pulse SH are omitted here.

  First, light including subject information enters the sensor array at the timing of the Light pulse, and signal charges are accumulated in each MIS type sensor. Subsequently, a gate pulse is applied to the gate line Vg1, and the signal charges of the MIS sensors S11 to S13 are read by the reading unit. Subsequently, when a gate pulse is applied to the gate line Vg2, refresh operations of S11 to S13 are performed.

  Similarly, gate pulses are sequentially applied to Vg3 to Vg6, and the entire read operation and refresh operation are performed.

  The radiographic apparatus of FIGS. 19 and 20 is characterized in that the refresh operation is performed for each line of each vertical scan without performing the refresh operation for the entire sensor array.

  Compared with the radiographic apparatus shown in FIGS. 17 and 18, the radiographic apparatus of FIGS. 19 and 20 has a small potential fluctuation of the sensor array and is excellent in response because the refresh is partially performed. It was suitable.

  The configuration of the radiation imaging apparatus suitable for high speed as described above is disclosed in Patent Document 2.

  As described above, the structure and operation of a radiation imaging apparatus using a sensor array in which pixels made up of MIS sensors and TFTs are two-dimensionally arranged are disclosed in Patent Document 1 and Patent Document 2, and are generally used in general. It has begun to be used for radiography equipment such as photography.

  However, the conventional radiographic apparatus has a problem that it may be difficult to increase the frame rate exceeding 30 FPS, and is in a situation that is not sufficient particularly for fluoroscopic imaging.

  That is, since the radiographic apparatus as shown in FIGS. 17 and 18 has an independent refresh operation period in addition to the photoelectric conversion operation period, it may be difficult to perform high-speed continuous photoelectric conversion.

  Specifically, considering the potential variation of the sensor array, the refresh operation may require about 10 ms to several tens of ms for each frame. For 30 FPS (30 frames per second) necessary for fluoroscopic imaging, that is, 33 ms / frame Time that cannot be ignored. For this reason, it may be difficult to realize fluoroscopic imaging.

JP 08-116044 A JP 2003-218339 A

  The present invention has been made in view of the above problems, and an object of the present invention is to increase the frame rate of a radiation imaging apparatus.

  A first aspect of the present invention relates to a radiation imaging apparatus, wherein a conversion element that has a semiconductor layer between a first electrode and a second electrode and converts radiation into electric charge, and one of a source and a drain electrode is provided. A first transistor connected to the first electrode for outputting an electric signal corresponding to the electric charge, and one of a source and a drain electrode connected to the first electrode to initialize the conversion element A plurality of pixels including a second transistor, a plurality of pixels arranged in a row direction and a column direction, and a first gate line commonly connected to the gate electrodes of the plurality of first transistors in a row direction. A plurality of second gate lines arranged in the column direction, and a plurality of first gate lines arranged in the direction and a plurality of second gate lines connected in common to the gate electrodes of the plurality of second transistors in the row direction. Gate line and multiple second in column direction A plurality of signal lines in which the other of the source and drain electrodes of the transistors is connected in common and a plurality of signal lines arranged in the row direction, and the second electrodes of the plurality of conversion elements are connected in common. A first power source that supplies a second potential, a second power source that is connected in common to the other of the source and drain electrodes of the plurality of second transistors and supplies a second potential, and is common to the plurality of signal lines Is connected to the plurality of signal lines and can supply a third potential to the plurality of signal lines, and a first driving circuit that is commonly connected to the plurality of first gate lines and drives the first transistor. And a second drive circuit unit that is commonly connected to the plurality of second gate lines and drives the first transistor, and the first and second drive circuit units are independently provided at different timings. A control unit for controlling, In the radiation imaging apparatus, the control unit may turn on the first transistor by the first driving circuit unit and the second transistor by the second driving circuit unit with respect to a predetermined pixel. A first operation for turning off the first transistor, a second operation for turning off the first transistor after the first operation, and a second driving after the second operation. A third operation in which the circuit unit turns on the second transistor; and the first driving circuit unit supplies the third potential after the second operation while the readout circuit unit supplies the third potential. And controlling the first and second drive circuit units to perform a fourth operation of turning on the second transistor and turning off the second transistor by the second drive circuit unit. To do.

  A second aspect of the present invention relates to a radiation imaging apparatus, wherein a conversion element that has a semiconductor layer between the first electrode and the second electrode and converts radiation into electric charge, and one of the source and drain electrodes is A first transistor connected to the first electrode for outputting an electric signal corresponding to the electric charge, and one of a source and a drain electrode connected to the first electrode to initialize the conversion element A plurality of pixels including a second transistor, a plurality of pixels arranged in a row direction and a column direction, and a first gate line commonly connected to the gate electrodes of the plurality of first transistors in a row direction. A plurality of second gate lines arranged in the column direction, and a plurality of first gate lines arranged in the direction and a plurality of second gate lines connected in common to the gate electrodes of the plurality of second transistors in the row direction. Gate line and multiple second in column direction A plurality of signal lines in which the other of the source and drain electrodes of the transistors is connected in common and a plurality of signal lines arranged in the row direction, and the second electrodes of the plurality of conversion elements are connected in common. A first power source that supplies a second potential, a second power source that is connected in common to the other of the source and drain electrodes of the plurality of second transistors and supplies a second potential, and is common to the plurality of signal lines Is connected to the plurality of signal lines and can supply a third potential to the plurality of signal lines, and a first driving circuit that is commonly connected to the plurality of first gate lines and drives the first transistor. And a second drive circuit unit that is commonly connected to the plurality of second gate lines and drives the first transistor, and the first and second drive circuit units are independently provided at different timings. A control unit for controlling, In the radiation imaging apparatus, for the predetermined pixel, the control unit turns on the first transistor and the second drive circuit unit turns on the second transistor for a predetermined pixel. The first driving circuit unit turns off the first transistor and the second driving circuit unit turns on the second transistor after the first operation. A second operation in which the second power supply supplies the second potential; and after the second operation, the first driver circuit unit turns off the first transistor and performs the second drive. A third operation in which the circuit portion turns on the second transistor and the second power source supplies the third potential; and the plurality of first gate lines and the plurality of gate lines For the second gate line of the first to the front The second power source, the first drive circuit unit, and the second drive circuit unit are controlled so that the third set of operations is repeated one by one or plural.

  According to a third aspect of the present invention, there is provided a radiation imaging system, comprising: a radiation generating apparatus that generates radiation; and the radiation imaging apparatus described above.

  A fourth aspect of the present invention relates to a method for controlling a radiation imaging apparatus, a conversion element that has a semiconductor layer between a first electrode and a second electrode and converts radiation into electric charges, and source and drain electrodes. One of the transistors connected to the first electrode and outputting an electric signal corresponding to the electric charge, and one of the source and drain electrodes connected to the first electrode and the conversion element is initially And a first gate commonly connected to the gate electrodes of the plurality of first transistors in the row direction. The conversion unit includes a plurality of pixels including a second transistor for forming the first transistor in the row direction and the column direction. A plurality of first gate lines in which a plurality of lines are arranged in the column direction and a plurality of second gate lines commonly connected to the gate electrodes of the plurality of second transistors in the row direction are arranged in the column direction. Second gate line and column direction A plurality of signal lines in which the other of the source and drain electrodes of the plurality of first transistors are connected in common are connected in common to the plurality of signal lines arranged in the row direction and the second electrodes of the plurality of conversion elements. A first power source that supplies a first potential; a second power source that is commonly connected to the other of the source and drain electrodes of the plurality of second transistors and supplies a second potential; A readout circuit portion that is commonly connected to a signal line and can supply a third potential to the plurality of signal lines, and a first circuit that is commonly connected to the plurality of first gate lines and drives the first transistor. 1. A control method for a radiation imaging apparatus, comprising: one drive circuit unit; and a second drive circuit unit that is commonly connected to the plurality of second gate lines and drives the first transistor, For a given pixel, the first A first operation in which the driving circuit unit turns on the first transistor and the second driving circuit unit turns off the second transistor; and the first operation is performed on the predetermined pixel. A second operation in which the first driver circuit unit turns off the first transistor later, and the second driver circuit unit performs the second operation on the predetermined pixel after the second operation. A third operation for turning on the transistor, and the first drive circuit unit while the readout circuit unit supplies the third potential to the predetermined pixel after the second operation. Performs a fourth operation of turning on the first transistor and turning off the second transistor by the second driver circuit portion.

  A fifth aspect of the present invention relates to a control method for a radiation imaging apparatus, a conversion element that has a semiconductor layer between a first electrode and a second electrode and converts radiation into electric charges, and source and drain electrodes. One of the transistors connected to the first electrode and outputting an electric signal corresponding to the electric charge, and one of the source and drain electrodes connected to the first electrode and the conversion element is initially And a first gate commonly connected to the gate electrodes of the plurality of first transistors in the row direction. The conversion unit includes a plurality of pixels including a second transistor for forming the first transistor in the row direction and the column direction. A plurality of first gate lines in which a plurality of lines are arranged in the column direction and a plurality of second gate lines commonly connected to the gate electrodes of the plurality of second transistors in the row direction are arranged in the column direction. Second gate line and column direction A plurality of signal lines in which the other of the source and drain electrodes of the plurality of first transistors are connected in common are connected in common to the plurality of signal lines arranged in the row direction and the second electrodes of the plurality of conversion elements. A first power source that supplies a first potential; a second power source that is commonly connected to the other of the source and drain electrodes of the plurality of second transistors and supplies a second potential; A readout circuit portion that is commonly connected to a signal line and can supply a third potential to the plurality of signal lines, and a first circuit that is commonly connected to the plurality of first gate lines and drives the first transistor. 1. A control method for a radiation imaging apparatus, comprising: one drive circuit unit; and a second drive circuit unit that is commonly connected to the plurality of second gate lines and drives the first transistor, For a given pixel, the first A first operation in which a moving circuit section turns on the first transistor and a second driving circuit section turns off the second transistor; and the first driving circuit section after the first operation. Turns off the first transistor, the second driver circuit portion turns on the second transistor, and the second power source supplies the second potential; After the above operation, the first driver circuit portion turns off the first transistor, the second driver circuit portion turns on the second transistor, and the second power source supplies the third potential. A third operation is performed, and one or a plurality of sets of the first to third operations are performed for each of the plurality of first gate lines and the plurality of second gate lines. It is characterized by repetition.

  In the column of the form for carrying out the invention below, in addition to the above-mentioned invention, the first drive for driving the first switch element connected to the conversion element for converting the radiation into the electric charge is related to the radiographic apparatus. A circuit unit, a second drive circuit unit that drives a second switch element connected to the conversion element, and a control unit that independently controls the first and second drive circuit units at different timings, respectively. The present invention relates to a radiation imaging system, a radiation generating apparatus that generates radiation, and the radiation imaging apparatus described above, and a method for controlling the radiation imaging apparatus that detects radiation. A first control step for controlling a first drive circuit unit that drives a first switch element connected to a conversion element that converts a charge into a charge; and a second switch element connected to the conversion element is driven First A second control step of controlling the drive circuit unit, wherein the first and second control steps control the first and second drive circuit units independently at different timings, respectively. The present invention relates to an invention, a program, an invention that causes a computer to execute the above control method, and an invention that relates to a computer-readable storage medium and stores the above program.

  According to the present invention, the frame rate of the radiation imaging apparatus can be increased.

1 is a schematic circuit diagram of a radiation imaging apparatus according to a preferred first embodiment of the present invention. It is a figure which shows the flowchart of the radiography apparatus of this invention. FIG. 5 is a timing diagram (mode 1) according to the preferred first embodiment of the present invention. It is a timing diagram (mode 2) concerning a suitable 1st embodiment of the present invention. FIG. 3 is a timing diagram (mode 3) according to the preferred first embodiment of the present invention. It is a figure which shows the shift register suitable for the radiography apparatus of this invention. It is a schematic circuit diagram of the radiography apparatus which concerns on suitable 2nd Embodiment of this invention. FIG. 9 is a timing diagram (mode 1) according to a preferred second embodiment of the present invention. It is a timing diagram (mode 2) concerning a suitable 2nd embodiment of the present invention. It is a timing diagram (mode 3) concerning a suitable 2nd embodiment of the present invention. It is a pixel sectional view concerning a suitable 3rd embodiment of the present invention. It is a system figure concerning a suitable 4th embodiment of the present invention. It is pixel sectional drawing of the conventional radiography apparatus. It is a typical circuit diagram of the conventional radiography apparatus. It is a timing diagram of the conventional radiography apparatus. It is an energy band figure of a MIS type sensor. It is a typical circuit diagram of the conventional radiography apparatus. It is a timing diagram of the conventional radiography apparatus. It is a typical circuit diagram of the conventional radiography apparatus. It is a timing diagram of the conventional radiography apparatus.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, X-rays will be described as an example of radiation, but the present invention is not limited to this, and may include α rays, β rays, γ rays, and the like.
[First Embodiment]
FIG. 1 is a schematic circuit diagram of a radiation imaging apparatus according to the preferred first embodiment of the present invention. FIG. 2 is a flowchart for explaining the operation of the control unit according to the first embodiment. Further, FIGS. 3, 4, and 5 are timing diagrams for explaining the operation in each mode of the radiation imaging apparatus of FIG. It is.

  As shown in FIG. 1, the radiation imaging apparatus according to the present embodiment includes a configuration that is common to the prior art of FIG. That is, the sensor array used in the radiation imaging apparatus according to the present embodiment includes a MIS type sensor as a conversion element, a transfer TFT as a first switch element, and a refresh TFT as a second switch element. It is configured by arranging two-dimensional pixels. That is, the first switch element for transferring the electric charge converted by the conversion element for each pixel, and the second for initializing the conversion element in order to make the conversion element convertible close to the initial state. The switch element is prepared separately. And the conversion part is comprised by the some pixel arranged in two dimensions.

Here, the configuration of the radiation imaging apparatus according to the present embodiment is different from the prior art as follows.
(1) It has two independent gate drive circuit units, a transfer gate drive circuit unit and a refresh gate drive circuit unit. That is, the first drive circuit unit for driving the first switch element for transferring the charge converted by the conversion element is provided. In addition to the first drive circuit unit, a second drive circuit unit for driving the second switch element for initializing the conversion element to make the conversion element in a convertible state close to the initial state is provided. Have.
(2) It has a plurality of operation modes, and these operation modes can be selected by the mode selection unit.
(3) It has a control unit connected to the mode selection unit, and the control unit can control operations of the transfer gate drive circuit unit and the refresh gate drive circuit unit.
(4) The transfer gate drive circuit unit, which is the first drive circuit unit, and the refresh gate drive circuit unit, which is the second drive circuit unit, are arranged at positions facing each other across the conversion unit. The operation can be controlled independently by each signal.

  The conventional radiographic apparatus described with reference to FIGS. 17, 18, 19, and 20 has no concept of having modes with different speeds and resolutions.

  In particular, there is no concept of arbitrarily setting the scanning speed and resolution in the vertical direction, and since the gate electrode of each TFT of the sensor array is driven by a single gate drive unit, the vertical speed is naturally. Or the resolution can be set arbitrarily.

  Further, the above conventional technique does not have a concept of changing the resolution and scanning speed in the vertical direction arbitrarily while realizing high-speed operation, and a method for solving these is not disclosed. Therefore, it is difficult to arbitrarily set and change the vertical resolution and speed.

  On the other hand, in the present embodiment, the resolution in the vertical scanning direction and the scanning speed can be arbitrarily changed by simultaneously scanning a plurality of gate lines.

  Further, the configuration will be described in detail. A bias voltage Vs is applied from the sensor bias power source to the common electrode (upper electrode) side of the MIS type sensors S11 to S63 of each pixel. The drain electrodes of the transfer TFTs TT11 to TT63 and the refresh TFTs TR11 to TR63 are connected to the individual electrode (lower electrode) side of the MIS type sensors S11 to S63 of each pixel. The source electrodes of the transfer TFTs TT11 to TT63 of each pixel are connected to the common signal lines Sig1 to Sig3, and the common signal lines Sig1 to Sig3 are connected to the input of the preamplifier 102 of the reading unit 101.

  The preamplifier 102 can reset the potentials of the common signal lines Sig1 to Sig3 to GND by an RC pulse.

  Further, the source electrodes of the refresh TFTs TR11 to TR63 of each pixel are connected to a refresh power supply Vr via a common refresh line.

  The gate electrodes of the transfer TFTs TT11 to TT63 are connected to the transfer gate lines VgT1 to VgT6, respectively, and the transfer gate lines VgT1 to VgT6 are constituted by a transfer gate drive circuit unit 103 constituted by a shift register (not shown). It is connected to the.

  The gate electrodes of the refresh TFTs TR11 to TR63 are connected to the refresh gate lines VgR1 to VgR6, respectively. The refresh gate lines VgR1 to VgR6 are connected to a refresh gate drive circuit unit 104 including a shift register (not shown).

  The transfer gate drive circuit unit 103 and the refresh gate drive circuit unit 104 can be independently controlled by a signal from the control unit 105. That is, the pulse applied to the transfer gate lines VgT1 to VgT6 and the pulse applied to the refresh gate lines VgR1 to VgR6 can be applied with different pulse widths and timings.

  Next, the operation of the radiation imaging apparatus according to the present embodiment will be described in detail with reference to the flowchart of FIG. 2 and the timing diagrams of FIGS.

  The radiation imaging apparatus of this embodiment is characterized by having a plurality of operation modes having different resolutions and scanning speeds in the vertical scanning direction.

Specifically, it has three operation modes, and the mode selection unit 106 can set and change the resolution and scanning speed in the vertical scanning direction of the radiation imaging apparatus in three ways. The mode selection unit 106 includes a workstation (not shown).
Here, the three operation modes of this embodiment will be described below.
Mode 1: A high-resolution and low-speed mode in which the transfer gate lines VgT1 to VgT6 and the refresh gate lines VgR1 to VgR6 are scanned one by one.
Mode 2: Medium resolution and medium speed mode in which two transfer gate lines VgT1 to VgT6 and two refresh gate lines VgR1 to VgR6 are scanned Mode 3: transfer gate lines VgT1 to VgT6 and refresh gate lines VgR1 to VgR6 The low-resolution and high-speed mode for scanning three by one The operation of the mode selection unit 106 and the control unit 105 will be described with reference to the flowchart of FIG.

  In step S <b> 201, the control unit 105 determines which mode has been selected by the mode selection unit 106. If the mode selection unit 106 determines that mode 1 has been selected, the process proceeds to step S202, where the control unit 105 performs vertical scanning of the transfer TFTs TT11 to TT63 one by one with respect to the transfer gate drive circuit unit 103. To control. Further, the control unit 105 controls the refresh gate drive circuit unit 104 to perform vertical scanning of the refresh TFTs TR11 to TR63 one by one.

  If the mode selection unit 106 determines that mode 2 has been selected, the process advances to step S203, and the control unit 105 performs control so that two vertical scans are performed. If it is determined that mode 3 has been selected, the process proceeds to step S204, and the control unit 105 controls to perform three vertical scans each.

  Subsequently, the operation of the present embodiment will be described with reference to FIGS. 3, 4, and 5.

  4 is a timing diagram for explaining the operation in mode 1, FIG. 5 is a diagram for explaining the operation in mode 2, and FIG. 6 is a timing diagram for explaining the operation in mode 3.

<Mode 1>
When mode 1 is selected by a mode selection unit 106 including a workstation (not shown), the control unit 105 performs vertical scanning on the transfer gate drive circuit unit 103 and the refresh gate drive circuit unit 104. Control to perform one by one.

  As shown in FIG. 3, first, in period a, X-ray pulses (X-rays) that have passed through the subject are incident on the sensor array, and charges corresponding to the subject information are accumulated in the MIS sensors S11 to S63.

  Subsequently, the potential of each of the signal lines Sig1 to Sig3 is reset to the GND potential by the RC pulse in the period b.

  Thereafter, a pulse is applied from the transfer gate drive circuit unit 103 to the transfer gate line VgT1 to which the gate electrodes of the transfer TFTs T11 to T13 are connected in the period c, and sampled by the sample hold pulse SH of the reading unit 101 in the period d. Is done. The signals S11 to S13 sampled with the SH pulse are converted into analog signals by the analog multiplexer of the reading unit 101 or the like.

  Thereafter, when the RC pulse is applied again in the period e and the refresh TFTs TR11 to TR63 are turned on while the potentials of Sig1 to Sig3 are set to GND, the potentials on the individual electrodes side of the MIS type sensors S11 to S13 become Vr. . Thereby, the MIS type sensors S11 to S13 are refreshed.

  In the subsequent period f, the refresh TFTs TR11 to 13 are turned off while the RC pulse is applied, and the transfer TFTs TT11 to 13 are turned on, so that the individual electrode sides of the MIS type sensors S11 to S63 become the GND potential. A photoelectric conversion operation is possible.

  Subsequently, in the period g, the transfer TFTs TT11 to 13 are turned off, but the electric field of the MIS type sensors S11 to S63 is maintained and can be prepared for a photoelectric conversion operation.

  By repeating the operations of period c to period g one by one for all transfer gate lines and refresh gate lines, the entire sensor array is read and refreshed.

  The feature of mode 1 is that the gate line is scanned one by one, so that the resolution is the highest. On the other hand, since all gate lines are scanned, time is required in terms of speed.

<Mode 2>
Next, the operation of mode 2 will be described with reference to FIG.

  First, when mode 2 is selected by a mode selection unit 106 configured by a workstation or the like (not shown), the control unit 105 causes the transfer gate drive circuit unit 103 and the refresh gate drive circuit unit 104 to Control is performed so that two vertical scans are performed.

  First, an X-ray pulse transmitted through the subject in period a enters the sensor array, and charges corresponding to the subject information are accumulated in the MIS type sensors S11 to S63.

  Subsequently, the potential of each of the signal lines Sig1 to Sig3 is reset to the GND potential by the RC pulse in the period b. Thereafter, a pulse is applied from the transfer gate drive circuit 103 to the transfer gate lines VgT1 and VgT2 to which the gate electrodes of the transfer TFTs TT11 to TT13 and TT21 to TT23 are connected in the period c, and the TFTs TT11 to TT13 and TT21 to TT23 are turned on. To do. At this time, the signals of the MIS type sensors S11 and S21, S12 and S22, and S13 and S23 are superimposed.

  In the period d, when the sample hold pulse SH of the reading unit 101 is applied, the superimposed signal is sampled and converted into an analog signal by an analog multiplexer or the like of the reading unit 101.

  Thereafter, in the period e, the RC pulse is applied again, and the refresh TFTs TR11 to TR13 and TR21 to TR23 are turned on while the potentials of Sig1 to Sig3 are set to GND. Then, the potentials on the individual electrode sides of the MIS sensors S11 to S13 and S21 to S23 become Vr, and the MIS sensors S11 to S13 and S12 to S23 are refreshed.

  In the subsequent period f, the refresh TFTs TR11 to TR13 and TR21 to TR23 are turned off while the RC pulse is applied. Further, the transfer TFTs TT11 to TT13 and TT21 to TT23 are turned on again, and the potentials on the individual electrode sides of the MIS sensors S11 to S13 and S21 to S23 become GND. And MIS type | mold sensors S11-S13 and S21-S23 will be in the state prepared for the next X-ray irradiation.

  Subsequently, in the period g, the transfer TFTs TT11 to TT13 and TT21 to TT23 are turned off, but the electric fields of the MIS sensors S11 to S13 and S21 to S23 are maintained to prepare for the photoelectric conversion operation.

  The entire sensor array is read and refreshed by repeating the operations of period c to period g for each of the transfer gate lines VgT1 to VgT6 and the refresh gate lines VgR1 to VgR6.

  The feature of mode 2 is that since the gate lines are scanned two by two, the resolution is somewhat lowered, while the signal level is increased and the SNR is advantageous, and the time required for vertical scanning is ½ that of mode 1 It is a point.

<Mode 3>
Mode 3 shown in FIG. 5 is characterized in that three gate lines are simultaneously scanned as compared with mode 2. That is, the feature of mode 3 is that since the gate lines are scanned three by three, the resolution is further lowered, while the signal level is further increased, the SNR is further advantageous, and the time required for the vertical scanning is mode 1 It is a point that is 1/3 of.

  FIG. 6A is a circuit diagram exemplarily showing a shift register suitable for the transfer gate drive circuit unit 103 and the refresh gate drive circuit unit 105 of the radiation imaging apparatus according to the present embodiment, and FIG. It is the timing chart.

  As shown in FIG. 6A, the shift register according to this embodiment includes D flip-flops D-FF1 to D-FF4 and AND gates AND1 to AND4. The AND gates AND1 to AND4 receive the signals from the output terminals OUT of the D flip-flops and the enable signal ENB, and give output signals to the transfer gate lines VgT1 to VgT6. The D flip-flop D-FF1 operates according to the shift clock SCLK when the start pulse SIN is applied to the input terminal IN.

  As shown in FIG. 6B, when the start pulse SIN is logic “H” and the shift clock SCLK transitions from logic “L” to logic “H”, the output terminal OUT of the D flip-flop D-FF1 Is activated to logic "H". When the next shift clock SCLK delayed by one clock cycle transitions from logic "L" to logic "H", the output terminal OUT of the D flip-flop D-FF1 is deactivated to logic "L". The AND gate AND1 performs an AND operation on the enable signal ENB and the output signal from the output terminal OUT of the D flip-flop D-FF1, and gives an output signal to the transfer gate line VgT1.

  Similarly, the D flip-flop D-FF2 operates in accordance with the shift clock SCLK with the output signal from the output terminal OUT of the D flip-flop D-FF1 as an input. When the output terminal OUT of the D flip-flop D-FF1 is logic “H” and the shift clock SCLK transitions from logic “L” to logic “H”, the output terminal OUT of the D flip-flop D-FF2 changes to logic “H”. Activated to "H". Then, it is activated until the next shift clock SCLK changes from logic “L” to logic “H”. The AND gate AND2 performs an AND operation on the enable signal ENB and the output signal from the output terminal OUT of the D flip-flop D-FF2, and gives an output signal to the transfer gate line VgT2. Similarly, the D flip-flop D-FF3 and the D flip-flop D-FF4 give output signals to the transfer gate line VgT3 and the transfer gate line VgT4, respectively.

  The control unit 105 according to the present embodiment can be configured to operate at least one of SIN, SCLK, and ENB at different timings between the gate drive circuit unit 103 and the gate drive circuit unit 104. When the transfer gate drive circuit unit 103 and the refresh gate drive circuit unit 104 are configured by the shift register of FIG. 6, the control unit 105 includes SINs having different timings for the respective gate drive circuit units 103 and 104. SCLK and ENB can be applied. Thereby, as shown in FIGS. 3, 4, and 5, the transfer gate lines VgT1 to VgT6 and the refresh gate lines VgR1 to VgR6 can be controlled at different timings.

  As described above, in the first embodiment of the present invention, the mode setting unit, the control unit, the transfer gate drive circuit unit connected to the transfer gate line, and the refresh gate drive connected to the refresh gate line It has a circuit part. Thereby, each gate drive circuit unit can be controlled independently according to the mode, and can be operated by changing the resolution and scanning speed in the vertical direction.

  With this configuration, it is possible to realize a radiation imaging apparatus that can operate by changing the resolution and scanning speed in the vertical scanning direction, which has been a problem of the prior art.

  Furthermore, it is more desirable that the control unit of the radiation imaging apparatus according to the present embodiment can control not only the number of scanning each gate drive circuit unit simultaneously but also the pulse length, timing, and the like.

  It is desirable that the control unit also controls the operation of the reading unit.

  Furthermore, in this embodiment, each gate drive circuit unit is arranged on the opposite side across the conversion unit of the sensor array. Each gate drive circuit unit may be provided on the same side of the sensor array, but this leads to complicated wiring layout and complicated mounting. Further, if each gate drive circuit unit is combined into one drive circuit unit, the design and operation of the drive circuit unit become complicated, and the cost of the apparatus increases. Considering this point, in the present invention, it is desirable to provide each gate drive circuit section on the opposite side across the conversion section of the sensor array.

  In the present embodiment, the mode setting can be set in the above three ways. However, in the present invention, more types may be set.

  Further, the TFT and the MIS type sensor may be formed using amorphous silicon, or may be formed using polysilicon or an organic material.

  Further, the conversion element and the TFT may be formed of different materials. In addition, as the conversion element, for example, crystalline silicon, gallium arsenide, amorphous selenium, gallium phosphide, lead iodide, mercury iodide, CdTe, CdZnTe, or the like, a semiconductor material that absorbs radiation such as X-rays and converts it directly into an electric charge. Can be used.

The photoelectric conversion element used as the conversion element is not limited to the MIS type sensor, and a pn type or pin type photodiode may be used. In a pn-type or pin-type photodiode, it is not necessary to perform a refresh operation unlike a MIS-type sensor. However, in order to remove the charge remaining in the photodiode, a second switch element for charge removal is provided for each pixel separately from the first switch element for charge transfer. Then, the present invention may be applied when performing initialization for removing residual charges by using the second switch element to make the photodiode close to the initial state.
[Second Embodiment]
Hereinafter, a preferred second embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 7 is a schematic circuit diagram of a radiation imaging apparatus according to the preferred second embodiment of the present invention. 8, 9, and 10 are timing charts for explaining the operation in each mode of the radiation imaging apparatus of FIG.

  As shown in FIG. 7, the radiation imaging apparatus according to the present embodiment is different from the radiation imaging apparatus according to the first embodiment described with reference to FIG.

  That is, in addition to the configuration of the radiation imaging apparatus of the first embodiment, the refresh power supply connected to the common refresh line of each refresh TFT can switch the refresh potential Vr and GND by a signal from the control unit. It differs in that it is a configuration.

  About another structure, it is the same as that of 1st Embodiment.

  The operation modes selected by the mode selection unit are the same as those in FIG. 2, and the radiation imaging apparatus according to the present embodiment has three operation modes having different resolutions and scanning speeds in the vertical scanning direction. The mode selection unit can set or change the resolution and scanning speed in the vertical scanning direction of the radiation imaging apparatus in three ways. The mode selection unit includes a workstation (not shown).

  Subsequently, the operation of the present embodiment will be described with reference to FIGS. However, description of the same parts as those in the first embodiment will be omitted.

  8 is a timing chart for explaining the operation in mode 1, FIG. 9 is the operation for mode 2, and FIG. 10 is the timing chart for explaining the operation in mode 3.

<Mode 1>
When mode 1 is selected by the mode selection unit 106, the control unit 105 controls the transfer gate drive circuit unit 103 and the refresh gate drive circuit unit 104 to perform vertical scanning one by one.

  As shown in FIG. 8, first, in a period a, an X-ray pulse (X-ray) transmitted through the subject is incident on the sensor array, and charges corresponding to the subject information are accumulated in the MIS sensors S11 to S63.

  Subsequently, the potential of each of the signal lines Sig1 to Sig3 is reset to the GND potential by the RC pulse in the period b.

  Thereafter, a pulse is applied from the transfer gate drive circuit unit 103 to the transfer gate line VgT1 to which the gate electrodes of the transfer TFTs T11 to T13 are connected in the period c, and sampled by the sample hold pulse SH of the reading unit 101 in the period d. Is done. The signals S11 to S13 sampled with the SH pulse are converted into analog signals by the analog multiplexer of the reading unit 101 or the like. The operation up to this point is the same as that of the first embodiment described with reference to FIG.

  Thereafter, the RC pulse is applied again in the period e, and the refresh TFTs TR11 to TR13 are turned on while the potentials of Sig1 to Sig3 are set to GND. At this time, the refresh power supply 104 is set to the Vr potential by the control unit 105. Accordingly, the potential on the individual electrode side of the MIS sensors S11 to S63 becomes Vr, and the MIS sensors S11 to S13 are refreshed.

  In the subsequent period f, the RC pulse is input, the potentials of Sig1 to Sig3 become GND, and the potential of the refresh power supply is returned to GND by the control unit while the refresh TFTs TR11 to TR13 are kept on.

  Thereby, the individual electrode side of the MIS type sensors S11 to S63 becomes the GND potential, and the photoelectric conversion operation becomes possible.

  Subsequently, the refresh TFTs TR11 to TR13 are turned off in the period g, but the electric fields of the MIS sensors S11 to S63 are maintained, and can be prepared for a photoelectric conversion operation.

  In the first embodiment, after the refresh operation, the individual electrode is set to the GND potential via the transfer TFT. In the second embodiment, the individual electrode is set to the GND potential via the refresh TFT.

  By repeating the operations of period c to period g one by one for all transfer gate lines and refresh gate lines, the entire sensor array is read and refreshed.

  The feature of mode 1 is that the gate line is scanned one by one, so that the resolution is the highest. On the other hand, since all gate lines are scanned, time is required in terms of speed.

<Mode 2>
The mode 2 shown in FIG. 9 is characterized in that two gate lines are simultaneously scanned as compared with the mode 1. That is, mode 2 is characterized in that the gate line is scanned two by two, so that the resolution is lowered, but the signal level is increased and SNR is advantageous, and the time required for vertical scanning is ½ that of mode 1. There is a point.

<Mode 3>
Mode 3 shown in FIG. 10 is characterized in that three gate lines are simultaneously scanned as compared with mode 2. That is, mode 3 is characterized in that the gate lines are scanned three by three, so that the resolution is further reduced, while the signal level is further increased, the SNR is advantageous, and the time required for vertical scanning is 1 / The point is 3.

  Also in this embodiment, it is desirable to use a shift register having the configuration shown in FIG. 6 for the transfer gate drive circuit unit and the refresh gate drive circuit unit.

As described above, the radiation imaging apparatus according to the second embodiment of the present invention is configured such that the control unit can control the refresh power supply in addition to the transfer gate drive circuit unit and the refresh gate drive circuit unit. The The gate drive circuit unit and the refresh power supply are controlled in accordance with a plurality of operation modes, and the operation is possible by changing the resolution in the vertical direction and the scanning speed.
[Third Embodiment]
FIG. 11 is a pixel cross-sectional view of a sensor array constituting a radiation imaging apparatus according to the preferred third embodiment of the present invention.

  The cross-sectional structure of the pixel of the sensor array 1100 used in the radiation imaging apparatus according to this embodiment will be described with reference to FIG. In the transfer TFT 1101 and the refresh TFT 1102, a lower electrode 1104, an insulating layer 1105, an amorphous silicon semiconductor layer 1106, an amorphous silicon n layer 1107, a source electrode layer 1108, and an upper electrode 1109 are stacked on a glass substrate 1103. The wiring portion 1121 is also configured in the same manner as the transfer TFT 1101 and the refresh TFT 1102. The upper portions of the transfer TFT 1101 and the refresh TFT 1102 are entirely covered with an insulating layer 1110. According to this structure, the transfer TFT 1101 and the refresh TFT 1102 have the same layer structure, and can be manufactured by the same manufacturing method. A contact hole is formed in the insulating layer 1110, a part of the drain electrode layer 1109 is exposed, and a contact plug 1111 is embedded in the contact hole formed in the insulating layer 1110. The drain electrode layer 1311 of the TFT 1302 is connected by a wiring portion 1303 or a contact hole (not shown).

  A structure in which a lower electrode layer 1113, an insulating layer 1114, a semiconductor layer 1115, a hole blocking layer 1116, and an upper electrode layer 1117 are stacked is formed above the insulating layer 1110 and the contact plug 1111, and the MIS type sensor 1112 of each pixel is formed. Configure. On the top of the MIS type sensor 1112, a protective layer 1118 such as an amorphous silicon nitride film or polyimide covers the whole. FIG. 11 shows an example in the case where an X-ray imaging apparatus is configured, and thus the phosphor layer 1120 is disposed on the protective layer 1118 via the adhesive layer 1119. In general, the amorphous silicon MIS sensor 1112 has little sensitivity to X-rays. For this reason, it is desirable that a phosphor layer 1120 for converting X-rays into visible light is bonded onto the protective layer 1118 via the adhesive layer 1119. As the phosphor layer 1120, a gadolinium-based material or a CsI (cesium iodide) grown columnar shape or the like can be used.

  In this embodiment, a transfer TFT 1101 and a refresh TFT 1102 are provided below the MIS sensor 1112. That is, the TFT portion and the photoelectric conversion portion have a laminated structure. In the case where two TFTs, a transfer TFT 1101 and a refresh TFT 1102, are used for a pixel, the aperture ratio, that is, the area of the photoelectric conversion portion is reduced by forming the TFT portion and the photoelectric conversion portion in a stacked structure as in this embodiment. There is an advantage that it can be enlarged.

X-rays pass through the subject, enter the phosphor layer 1120, are converted into visible light, and enter the MIS type sensor 1112. The charges generated in the semiconductor layer 1115 of the MIS sensor 1112 are sequentially transferred to the reading unit 101 by the transfer TFT 1101, read out, and refreshed.
[Fourth Embodiment]
FIG. 12 is a system diagram in which the radiation imaging apparatus according to the preferred embodiment of the present invention is applied to a radiation imaging system.

  The features of this radiation imaging system are as follows. That is, X-rays 1260 generated by an X-ray tube 1250 as an X-ray generation source pass through an observation portion 1262 such as a chest of a patient or a subject 1261 and enter an image sensor 1240. This incident X-ray includes information inside the subject 1261. In response to the incidence of X-rays, the image sensor 1240 obtains electrical information. This information is converted into a digital signal, image-processed by an image processor 1270, and can be observed on a display 1280 in a control room (control room).

  Further, the information subjected to image processing in this way can be transferred to a remote place or the like by a transmission unit such as a telephone line or wireless 1290. Then, it can be displayed on the display 1281 or outputted on a film or the like, so that a doctor in a remote place such as a doctor room other than the control room can make a diagnosis. In this way, information obtained in the doctor room is recorded on a recording medium 1210 such as a recording medium using various recording materials such as an optical disk, a magneto-optical disk, and a magnetic disk by a recording unit 1200 such as a film processor. It can also be recorded and saved.

  The radiation imaging apparatus according to the preferred embodiment of the present invention is provided inside the image sensor 1240, and the digital output subjected to A / D conversion is subjected to image processing or the like according to the purpose by an image processor 1270. . The mode selection unit 106 includes a workstation (not shown) and the like, and the image processor 1270 is provided with a control unit 105. The control unit 105 not only operates each component of the radiation imaging apparatus but also controls the radiation generation apparatus 1250. Can be controlled.

  In the present embodiment, it is desirable that the radiation generating apparatus can be controlled so as to irradiate the subject with X-rays in a pulsed manner. It is further desirable that the control unit 105 can control the display units 1280 and 1281.

Since the radiographic apparatus of the present invention can be operated by arbitrarily setting and changing the resolution and speed in vertical scanning, it is suitable for the radiographic system shown in FIG.
[Other embodiments]
The preferred embodiment of the present invention may be applied to a system constituted by a plurality of devices (for example, a host computer, an interface device, etc.) or an apparatus constituted by a single device.

  The object of the present invention can also be achieved by a storage medium that records a program code of software that implements the functions of the above-described embodiments as follows. That is, it can also be achieved by supplying this recording medium to a system or apparatus, and reading and executing the program code stored in the storage medium by the computer (or CPU or MPU) of the system or apparatus.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.

  As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like is used. be able to.

  In addition, the functions of the above-described embodiments are not only realized by executing the program code read by the computer. This includes the case where the OS (operating system) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. .

  Further, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU provided in the function expansion board or function expansion unit performs part or all of the actual processing. The case where the function of the above-described embodiment is realized by such processing is also included.

S11 to S63 Conversion elements TT11 to TT63 Transfer TFT
TR11-TR63 Refresh TFT
103 Transfer gate drive circuit unit 104 Refresh gate drive circuit unit 105 Control unit

Claims (18)

A conversion element that has a semiconductor layer between the first electrode and the second electrode and converts radiation into electric charge, and one of the source and drain electrodes is connected to the first electrode and an electric signal corresponding to the electric charge And a second transistor for initializing the conversion element with one of a source and a drain electrode connected to the first electrode, and a pixel including a first transistor for outputting A plurality of conversion units arranged in a direction;
A plurality of first gate lines in which a plurality of first gate lines commonly connected to the gate electrodes of the plurality of first transistors in the row direction are arranged in the column direction;
A plurality of second gate lines in which a plurality of second gate lines commonly connected to the gate electrodes of the plurality of second transistors in the row direction are arranged in the column direction;
A plurality of signal lines in which a plurality of signal lines in which the other of the source and drain electrodes of the plurality of first transistors in the column direction are connected in common are arranged in the row direction;
A first power source commonly connected to the second electrodes of the plurality of conversion elements and supplying a first potential;
A second power source connected in common to the other of the source and drain electrodes of the plurality of second transistors and supplying a second potential;
A readout circuit portion connected in common to the plurality of signal lines and capable of supplying a third potential to the plurality of signal lines;
A first drive circuit unit that is connected in common to the plurality of first gate lines and drives the first transistor;
A second drive circuit unit that is connected in common to the plurality of second gate lines and drives the first transistor;
A radiation imaging apparatus comprising: a control unit that independently controls the first and second drive circuit units at different timings,
The control unit includes a first operation in which the first driving circuit unit turns on the first transistor and the second driving circuit unit turns off the second transistor with respect to a predetermined pixel. A second operation in which the first driving circuit section turns off the first transistor after the first operation; and a second driving circuit section in the second transistor after the second operation. The first drive circuit unit turns on the first transistor and the first transistor while the readout circuit unit supplies the third potential after the second operation. The radiation imaging apparatus, wherein the first and second drive circuit units are controlled such that the second drive circuit unit performs a fourth operation of turning off the second transistor.   The control unit repeats the first to fourth operation groups one by one or a plurality of times for the plurality of first gate lines and the plurality of second gate lines. The radiation imaging apparatus according to claim 1, wherein the first and second driving circuit units are controlled. A mode selection unit capable of selecting a plurality of operation modes;
When the operation mode selected by the mode selection unit is the first operation mode, the control unit is configured such that the first drive circuit unit includes one of the first transistors among the plurality of first transistors. The plurality of first transistors connected in common to the gate line are simultaneously driven for each row, and the second drive circuit unit includes one of the plurality of second transistors. Controlling the first and second driving circuit units so as to sequentially drive second transistors commonly connected to the second gate line for each row;
When the operation mode selected by the mode selection unit is a second operation mode different from the first operation mode, the control unit is configured such that the first drive circuit unit includes the plurality of first transistors. Of these, the plurality of first transistors commonly connected to at least two of the first gate lines are simultaneously driven every two rows at the same time, and the second drive circuit section includes the plurality of first transistors. A plurality of second transistors commonly connected to at least two of the second transistors among the second transistors are simultaneously driven for each of the at least two rows. The radiation imaging apparatus according to claim 2, wherein the radiation driving apparatus controls the second drive circuit unit. The first and second transistors are thin film transistors formed on a substrate using any of amorphous silicon, polycrystalline silicon, and organic semiconductors,
The conversion element is disposed on an insulating layer covering the plurality of first and second transistors,
The contact plug embedded in the insulating layer electrically connects one of the source and drain electrodes of the first transistor, one of the source and drain electrodes of the second transistor, and the first electrode of the conversion element. The radiation imaging apparatus according to any one of claims 1 to 3, wherein the radiation imaging apparatus is provided. The conversion element includes an insulating layer disposed between the first electrode and the semiconductor layer, and an impurity semiconductor layer disposed between the second electrode and the semiconductor layer. Have a sensor,
A voltage at which the MIS sensor performs a refresh operation by the first potential and the second potential is applied to the conversion element, and the MIS sensor performs a photoelectric conversion operation by the first potential and the third potential. The radiation imaging apparatus according to claim 4, wherein a voltage for performing is applied to the conversion element.   The radiation imaging apparatus according to claim 5, wherein the semiconductor layer is configured using amorphous silicon, and the conversion element further includes a phosphor layer that converts radiation into visible light.   The radiation imaging apparatus according to claim 4, wherein the conversion element is a PIN photodiode. The radiation imaging apparatus according to any one of claims 1 to 7,
A radiation imaging system including a radiation generator. A conversion element that has a semiconductor layer between the first electrode and the second electrode and converts radiation into electric charge, and one of the source and drain electrodes is connected to the first electrode and an electric signal corresponding to the electric charge And a second transistor for initializing the conversion element with one of a source and a drain electrode connected to the first electrode, and a pixel including a first transistor for outputting A plurality of conversion units arranged in the direction; a plurality of first gate lines in which a plurality of first gate lines commonly connected to the gate electrodes of the plurality of first transistors in the row direction are arranged in the column direction;
A plurality of second gate lines in which a plurality of second gate lines commonly connected to the gate electrodes of the plurality of second transistors in the row direction are arranged in the column direction;
A plurality of signal lines in which a plurality of signal lines in which the other of the source and drain electrodes of the plurality of first transistors in the column direction are connected in common are arranged in the row direction;
A first power source commonly connected to the second electrodes of the plurality of conversion elements and supplying a first potential; and a second power source connected to the other of the source and drain electrodes of the plurality of second transistors; A second power source that supplies a potential of 2; a readout circuit portion that is connected in common to the plurality of signal lines and can supply a third potential to the plurality of signal lines;
A first drive circuit unit that is connected in common to the plurality of first gate lines and drives the first transistor;
And a second drive circuit unit that is connected in common to the plurality of second gate lines and drives the first transistor, and a method for controlling a radiation imaging apparatus comprising:
A first operation in which the first driving circuit unit turns on the first transistor and the second driving circuit unit turns off the second transistor for a predetermined pixel;
A second operation in which the first driver circuit unit turns off the first transistor after the first operation with respect to the predetermined pixel;
A third operation in which the second driver circuit unit turns on the second transistor after the second operation with respect to the predetermined pixel;
For the predetermined pixel, the first driver circuit unit turns on the first transistor and the first transistor while the readout circuit unit supplies the third potential after the second operation. A fourth operation in which the second drive circuit portion turns off the second transistor;
A control method for a radiation imaging apparatus.   10. The radiation according to claim 9, wherein the first to fourth operations are repeated one by one or a plurality for the plurality of first gate lines and the plurality of second gate lines. Control method of imaging apparatus. A conversion element that has a semiconductor layer between the first electrode and the second electrode and converts radiation into electric charge, and one of the source and drain electrodes is connected to the first electrode and an electric signal corresponding to the electric charge And a second transistor for initializing the conversion element with one of a source and a drain electrode connected to the first electrode, and a pixel including a first transistor for outputting A plurality of conversion units arranged in a direction;
A plurality of first gate lines in which a plurality of first gate lines commonly connected to the gate electrodes of the plurality of first transistors in the row direction are arranged in the column direction;
A plurality of second gate lines in which a plurality of second gate lines commonly connected to the gate electrodes of the plurality of second transistors in the row direction are arranged in the column direction;
A plurality of signal lines in which a plurality of signal lines in which the other of the source and drain electrodes of the plurality of first transistors in the column direction are connected in common are arranged in the row direction;
A first power source commonly connected to the second electrodes of the plurality of conversion elements and supplying a first potential;
A second power source connected in common to the other of the source and drain electrodes of the plurality of second transistors and supplying a second potential;
A readout circuit portion connected in common to the plurality of signal lines and capable of supplying a third potential to the plurality of signal lines;
A first drive circuit unit that is connected in common to the plurality of first gate lines and drives the first transistor;
A second drive circuit unit that is connected in common to the plurality of second gate lines and drives the first transistor;
A radiation imaging apparatus comprising: a control unit that independently controls the first and second drive circuit units at different timings,
The control unit performs a first operation in which the first driving circuit unit turns on the first transistor and the second driving circuit unit turns off the second transistor for a predetermined pixel. And after the first operation, the first drive circuit unit turns off the first transistor, the second drive circuit unit turns on the second transistor, and the second power supply A second operation for supplying a second potential; and after the second operation, the first driver circuit portion turns off the first transistor and the second driver circuit portion is the second transistor. And the third operation in which the second power supply supplies the third potential, and for the plurality of first gate lines and the plurality of second gate lines. One or more of the first to third operation sets are To repeat by the radiation imaging device and controls the second power source and said first driving circuit unit and the second driving circuit portion. A mode selection unit capable of selecting a plurality of operation modes;
When the operation mode selected by the mode selection unit is the first operation mode, the control unit is configured such that the first drive circuit unit includes one of the first transistors among the plurality of first transistors. The plurality of first transistors connected in common to the gate line are simultaneously driven for each row, and the second drive circuit unit includes one of the plurality of second transistors. Controlling the first and second driving circuit units so as to sequentially drive second transistors commonly connected to the second gate line for each row;
When the operation mode selected by the mode selection unit is a second operation mode different from the first operation mode, the control unit is configured such that the first drive circuit unit includes the plurality of first transistors. Of these, the plurality of first transistors commonly connected to at least two of the first gate lines are simultaneously driven every two rows at the same time, and the second drive circuit section includes the plurality of first transistors. The plurality of second transistors commonly connected to at least two of the second transistors among the second transistors are simultaneously driven for each of the at least two rows. The radiation imaging apparatus according to claim 11, wherein the radiation control apparatus controls the second drive circuit unit. The first and second transistors are thin film transistors formed on a substrate using any of amorphous silicon, polycrystalline silicon, and organic semiconductors,
The conversion element is disposed on an insulating layer covering the plurality of first and second transistors,
The contact plug embedded in the insulating layer electrically connects one of the source and drain electrodes of the first transistor, one of the source and drain electrodes of the second transistor, and the first electrode of the conversion element. The radiation imaging apparatus according to claim 11, wherein the radiation imaging apparatus is connected. The conversion element includes an insulating layer disposed between the first electrode and the semiconductor layer, and an impurity semiconductor layer disposed between the second electrode and the semiconductor layer. Having a sensor,
A voltage at which the MIS sensor performs a refresh operation by the first potential and the second potential is applied to the conversion element, and the MIS sensor performs a photoelectric conversion operation by the first potential and the third potential. The radiation imaging apparatus according to claim 13, wherein a voltage for performing is applied to the conversion element.   The radiation imaging apparatus according to claim 14, wherein the semiconductor layer is configured using amorphous silicon, and the conversion element further includes a phosphor layer that converts radiation into visible light.   The radiation imaging apparatus according to claim 13, wherein the conversion element is a PIN photodiode. A radiation imaging apparatus according to any one of claims 11 to 16,
A radiation imaging system including a radiation generator. A conversion element that has a semiconductor layer between the first electrode and the second electrode and converts radiation into electric charge, and one of the source and drain electrodes is connected to the first electrode and an electric signal corresponding to the electric charge And a second transistor for initializing the conversion element with one of a source and a drain electrode connected to the first electrode, and a pixel including a first transistor for outputting A plurality of conversion units arranged in a direction;
A plurality of first gate lines in which a plurality of first gate lines commonly connected to the gate electrodes of the plurality of first transistors in the row direction are arranged in the column direction;
A plurality of second gate lines in which a plurality of second gate lines commonly connected to the gate electrodes of the plurality of second transistors in the row direction are arranged in the column direction;
A plurality of signal lines in which a plurality of signal lines in which the other of the source and drain electrodes of the plurality of first transistors in the column direction are connected in common are arranged in the row direction;
A first power source commonly connected to the second electrodes of the plurality of conversion elements and supplying a first potential;
A second power source connected in common to the other of the source and drain electrodes of the plurality of second transistors and supplying a second potential;
A readout circuit portion connected in common to the plurality of signal lines and capable of supplying a third potential to the plurality of signal lines;
A first driver circuit portion that is commonly connected to the plurality of first gate lines and drives the first transistor; and a first driver circuit portion that is commonly connected to the plurality of second gate lines; A second drive circuit unit for driving;
A method for controlling a radiation imaging apparatus comprising:
A first operation in which the first driving circuit unit turns on the first transistor and the second driving circuit unit turns off the second transistor for a predetermined pixel;
After the first operation, the first driver circuit unit turns off the first transistor, the second driver circuit unit turns on the second transistor, and the second power source is the second power source. A second operation for supplying a potential of
After the second operation, the first driver circuit portion turns off the first transistor, the second driver circuit portion turns on the second transistor, and the second power source is the third power source. And a third operation for supplying a potential of
Control of radiation imaging apparatus, wherein one or a plurality of sets of the first to third operations are repeated for each of the plurality of first gate lines and the plurality of second gate lines. Method.

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