Patent Publication Number: US-2016223693-A1

Title: Radiographic image capturing apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of U.S. patent application Ser. No. 14/717,300, filed on May 20, 2015, the entire contents of which are incorporated herein by reference. The Ser. No. 14/717,300 application claimed the benefit of the date of the earlier filed Japanese Patent Application No. 2014-105793 filed May 22, 2014, priority to which is also claimed herein, and the contents of which are also incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a radiographic image capturing apparatus, and especially to a radiographic image capturing apparatus including a plurality of radiation detecting elements two-dimensionally arranged. 
     2. Description of Related Art 
     Heretofore, various kinds of radiographic image capturing apparatuses have been developed, such as a so-called direct type radiographic image capturing apparatus which causes detecting elements to generate electric charges depending on a dose of irradiated radiation such as X-ray and converts the electric charges into electrical signals, and a so-called indirect type radiographic image capturing apparatus which causes a scintillator or the like to convert irradiated radiation into other wavelength light such as visible light and then causes photoelectric conversion elements such as photodiodes to generate electric charges depending on energy of converted and irradiated light and converts the electric charges into electrical signals (i.e. image data). With regard to the present invention, the detecting elements of the direct type radiographic image capturing apparatus and the photoelectric conversion elements of the indirect type radiographic image capturing apparatus are correctively referred to as radiation detecting elements. 
     The radiographic image capturing apparatus of this type has been known as a Flat Panel Detector (FPD), and has been heretofore configured as a so-called exclusive-machine type (also called as a fixed type, etc.) configured integrally with a support base. Recently, there has been developed and come into practical use a portable radiographic image capturing apparatus which houses the radiation detecting elements and the like in a housing so that those elements and the like become portable. 
     In such a radiographic image capturing apparatus, as illustrated in  FIG. 3  to be mentioned later for example, generally a plurality of radiation detecting elements  7  are arranged in the state of a two-dimensional matrix on a detecting section P. When the radiographic image capturing apparatus is irradiated with radiation through a not-illustrated patient as an object at the time of imaging, the radiation detecting elements  7  generate the electric charges. To each of the radiation detecting elements  7 , a switch element composed of a Thin Film Transistor (hereinafter referred to as a TFT)  8  and the like is connected. In a readout processing of image data D after the imaging, when the TFT  8  is turned on so that the electric charges accumulated in the radiation detecting elements  7  are discharged into signal lines  6 , the electric charges flow into readout circuits  17  through the signal lines  6 , and are read out as electric charge data D in the readout circuits  17 . The readout processing of the image data D will be described later. 
     Meanwhile, in the case that imaging using the radiographic image capturing apparatus is not performed at least for a while, the power applied to respective functional sections such as the readout circuits  17  of the radiographic image capturing apparatus is wasted. Especially in the above-described portable radiographic image capturing apparatus including a battery, if the power is thus wasted, the battery would be consumed earlier, the number of time of the imaging on one battery charge would be reduced, and imaging efficiency would be reduced. Those have been problems. 
     For this reason, there have been not a little radiographic image capturing apparatuses configured to have an imaging mode including at least: a wake up mode in which the power is applied to the respective functional sections so that the imaging can be performed; and a sleep mode in which the power is applied to required minimum functional sections and the imaging cannot be performed, wherein the imaging mode can be switched between these modes (e.g. see Japanese Patent Application Laid-open No. 2010-268171). The above-described readout circuits  17  consume relatively large power at the time of the readout operation of the image data D and the like. For this reason, in the sleep mode, generally the radiographic image capturing apparatus does not perform at least the readout operations in the readout circuits  17 . 
     In the meantime, according to the research by the inventor, it has been found that when the imaging is performed after the power mode of the radiographic image capturing apparatus  1  is switched to the sleep mode and then switched to the imagable mode again, sometimes image unevenness and/or stripe pattern appear, though only slightly, in a radiographic image I generated based on the image data D which has been read out after the imaging (see  FIG. 7 ). In  FIG. 7 , the image unevenness and the stripe pattern appearing in the radiographic image I are emphatically illustrated. 
     As described later, generally a predetermined number (e.g. 128, 256, etc.) of the readout circuits  17  are provided in one readout IC  16  (see  FIG. 3  to be mentioned later), and a necessary number of readout ICs  16  are arranged in parallel depending on the number of signal lines  6  or the like. According to the research of the inventor, as illustrated in  FIG. 7 , the image unevenness in the radiographic image I appears in each of regions R 1 , R 2 , R 3 , R 4 , . . . corresponding to the readout ICs  16 , respectively, and the strip pattern appears in positions corresponding to the readout circuits  17 . 
     Concretely, the signal lines  6  are connected to the readout circuits  17 , respectively, and the predetermined number of the signal lines  6  are connected to each of the readout ICs  16 , as described above. When paying attention to each of regions R 1 , R 2 , R 3 , R 4 , . . . in the radiographic image I corresponding to the respective readout ICs  16 , a certain offset is superimposed on the image data D of pixels within each one of the regions R. The certain offset is different according to each of the readout ICs  16 . The superimposed offset appears as the image unevenness in each of regions R 1 , R 2 , R 3 , R 4 , . . . . Additionally, it has also been found that offsets are superimposed on the image data D of pixels correspondingly to the signal lines  6  connected to the readout circuits  17 , respectively, which offsets appear as the stripe pattern in the radiographic image I. 
     As a result of accumulation of research by the inventor, the cause of superimposition of the offset which causes image unevenness and/or stripe pattern on the image data D has been found, and also the configuration to prevent such a phenomenon from occurring has been found. 
     SUMMARY OF THE INVENTION 
     The present invention is made in view of the foregoing problems, and an object of the present invention is to provide a radiographic image capturing apparatus which can accurately prevent an offset causing image unevenness and/or stripe pattern from being superimposed on image data even when the power mode is switched from the sleep mode to the imagable mode and then an imaging is performed. 
     In order to achieve the above object, according to one aspect of a preferred embodiment of the present invention, there is provided a radiographic image capturing apparatus including: a plurality of radiation detecting elements arranged two-dimensionally; a plurality of signal lines each connected to each of the radiation detecting elements; a readout IC equipped with a plurality of readout circuits connected to the signal lines, respectively; a power source circuit which supplies a power to the readout IC; and a discharge circuit disposed on a path through which the power source circuit supplies the power to the readout IC, the discharge circuit being capable of connecting the path and a GND to each other, wherein the radiographic image capturing apparatus is configured so that an imaging mode can be switched at least between a wake up mode in which the power is supplied to at least one functional section so that an imaging can be performed, and a sleep mode in which the power is supplied to a required minimum functional section of the functional section and the imaging cannot be performed, and the discharge circuit connects the path and the GND to each other during the sleep mode. 
     According to the radiographic image capturing apparatus 
     having such a system, the electric charges remaining in the power source circuit, readout IC and sensor panel can proactively flow out toward the GND and can be accurately removed via the discharge circuit during the sleep mode. Therefore, even when the power mode is subsequently switched from the sleep mode to the imagable mode and then the imaging is performed, the offsets due to the residual electric charges can be accurately prevented from being superimposed on the image data, and the image unevenness and/or stripe pattern can be accurately prevented from appearing in the radiographic image I generated based on the read-out image data and the like. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the appended drawings, and thus are not intended as a definition of the limits of the present invention, and wherein: 
         FIG. 1  is a cross-section view of a radiographic image capturing apparatus; 
         FIG. 2  is a plan view illustrating a configuration of a substrate of the radiographic image capturing apparatus; 
         FIG. 3  is a block diagram illustrating an equivalent circuit of the radiographic image capturing apparatus; 
         FIG. 4  is a block diagram illustrating an equivalent circuit for one pixel constituting a detecting section; 
         FIG. 5A  is a block diagram illustrating a configuration example of a discharge circuit; 
         FIG. 5B  is a block diagram illustrating a configuration example of a part including the discharge circuit, a power source circuit, etc. of the radiographic image capturing apparatus according to this embodiment; 
         FIG. 6  is a graph illustrating a time shift of a voltage applied to each radiation detecting element in the case of Variation  1 - 2 ; and 
         FIG. 7  is a diagram for explaining about image unevenness and/or stripe pattern appearing in a generated radiographic image. 
     
    
    
     PREFERRED EMBODIMENT OF THE PRESENT INVENTION 
     Hereinafter embodiments of a radiographic image capturing apparatus according to the present invention will be described with reference to the drawings. 
     Incidentally, as a radiographic image capturing apparatus of the present invention, a so-called indirect type radiographic image capturing apparatus which is equipped with a scintillator or the like and converts irradiated radiation into other wavelength light such as visible light to obtain an electrical signal will hereinafter be described. However, the present invention can also be applied to a so-called direct type radiographic image capturing apparatus which directly detects radiation with radiation detecting elements without the scintillator or the like. 
     Moreover, a case that the radiographic image capturing apparatus is a so-called portable type will be described, but the present invention can be applied to a so-called exclusive-machine type radiographic image capturing apparatus integrally formed with a support base and the like. 
     Basic Configuration 
     First, a basic configuration and the like of the radiographic image capturing apparatus of this embodiment will be described.  FIG. 1  is a cross-section view of the radiographic image capturing apparatus of the embodiment, and  FIG. 2  is a plan view illustrating the configuration of the substrate of the radiographic image capturing apparatus. 
     In the embodiment, the radiographic image capturing apparatus  1  has a housing  2  including a radiation incident surface R on a radiation irradiation side, the housing  2  containing a sensor panel SP composed of a scintillator  3 , a sensor substrate  4 , etc. Although illustration is omitted in  FIG. 1 , an antenna  41  (see  FIG. 3  to be mentioned later) for transmitting/receiving data, signals, etc. to/from external devices/apparatuses in a wireless system, and a connector for transmitting/receiving them in a wire system are provided on a side surface or the like of the housing  2 . 
     As illustrated in  FIG. 1 , a base  31  is disposed in the housing  2 , and the sensor substrate  4  is disposed on a radiation-incident-surface R side (hereinafter simply referred to as an upper-surface side, etc., in conformity to a vertical direction in the drawings) of the base  31  through a not-illustrated lead thin film or the like. Additionally, radiation detecting elements  7  and the like are disposed on the upper-surface side of the sensor substrate  4 , and furthermore the scintillator  3  is disposed on them, the scintillator  3  converting the irradiated radiation into light such as visible light so as to emit the light to the radiation detecting elements  7 . Incidentally, the scintillator  3  is attached to a scintillator substrate  34 . 
     On a lower surface side of the base  31 , there are disposed a PCB substrate  33  on which electronic components  32  and the like are arranged, a battery  24 , and so on. The sensor panel SP is thus composed of the base  31 , the sensor substrate  4 , and so on. Furthermore, in the embodiment, a cushioning  35  is provided between the sensor panel SP and each of the sides of the housing  2 . 
     The sensor substrate  4  of the embodiment is composed of a glass substrate, and as illustrated in  FIG. 2 , a plurality of scanning lines  5  and a plurality of signal lines  6  are arranged so as to cross each other on the upper surface  4 A (i.e. the surface facing the scintillator  3 ) of the sensor substrate  4 . In small areas S divided by the scanning lines  5  and the signal lines  6  on the surface  4 A of the sensor substrate  4 , the radiation detecting elements  7  are disposed, respectively. 
     The whole of the small areas S divided by the scanning lines  5  and signal lines  6  and including the radiation detecting elements  7  arranged in the state of a two-dimensional matrix, namely a region indicated with chain lines in  FIG. 2 , is defined as a detecting section P. In the embodiment, photodiodes are used as the radiation detecting elements  7 , but, for example, also phototransistors or the like may be used. 
     Here, a circuit configuration of the radiographic image capturing apparatus  1  will be described.  FIG. 3  is a block diagram illustrating an equivalent circuit of the radiographic image capturing apparatus  1  of the embodiment, and  FIG. 4  is a block diagram illustrating an equivalent circuit of one pixel constituting the detecting section P. 
     To a first electrode  7 A of each of the radiation detecting elements  7 , a source electrode  8 S (see “S” in  FIGS. 3 and 4 ) of the TFT  8  as the switch element is connected. A drain electrode  8 D and a gate electrode  8 G (see “D” and “G” in  FIGS. 3 and 4 ) of the TFT  8  are connected to each of the signal lines  6  and each of the scanning lines, respectively. 
     The TFT  8  becomes on-state when an ON voltage is applied to the gate electrode  8 G from a later-described scan driving member  15  via each of the scanning lines  5 , and causes the electric charge accumulated in the radiation detecting member  7  to be discharged to each of the signal lines  6  via the source electrode  8 S and the drain electrode  8 D. The TFT  8  becomes off-state when an OFF voltage is applied to the gate electrode  8 G via each of the scanning lines  5 , and stops the discharge of the electric charge to each of the signal lines  6  from the radiation detecting member  7  so that the electric charge is accumulated in the radiation detecting element  7 . 
     In the embodiment, as illustrated in  FIGS. 2 and 3 , a bias line  9  is provided for each column of the radiation detecting members  7  and connected to a second electrode  7 B of each of the radiation detecting members  7 . A plurality of bias lines  9  are connected to a tie line  10  at the outside of the detecting section P of the sensor substrate  4 . The tie line  10  is connected to a bias power source  14  (see  FIGS. 3 and 4 ) via an input/output terminal  11  (also referred to as a pad, etc.; see  FIG. 2 ) so that a reverse bias voltage is applied to the second electrode  7 B of each of the radiation detecting members  7  from the bias power source  14  via the tie line  10  and each of the bias lines  9 . 
     Incidentally, in the embodiment, a not-illustrated flexible circuit substrate is connected to each of the input/output terminals  11 , the flexible circuit substrate including a chip such as a later-described readout IC  16  and a gate IC constituting a gate driver  15 B of the scan driving member  15 , the chip being incorporated on a film. The scanning lines  5 , the signal lines  6 , and the tie line  10  of the bias lines  9  on the sensor substrate  4  are electrically connected to electronic components  32  and the like (see  FIG. 1 ) disposed on the back side of the sensor panel SP via the flexible circuit substrate. 
     In the scan driving member  15 , the ON and OFF voltages are supplied to the gate driver  15 B from the power source circuit  15 A via a wiring  15 C. The voltage to be applied to each of lines L 1  to Lx of the scanning lines  5  is switched between the ON voltage and the OFF voltage by the gate driver  15 B. 
     Each of the signal lines  6  is connected to each of the readout circuits  17  contained in each of the readout ICs  16  via each of the input/output terminals  11 . The readout circuit  17  of the embodiment is mainly composed of an amplifier circuit  18 , a correlated double sampling circuit  19 , etc. The readout IC  16  further includes an analog multiplexer  21  and an A/D convertor  20 . In  FIGS. 3 and 4 , the correlated double sampling circuit  19  is written as “CDS”. 
     The amplifier circuit  18  of the embodiment is composed of a charge amplifier circuit including an operational amplifier  18 A, and a capacitor  18 B and electric-charge reset switch  18 C each of which is connected in parallel with respect to the operational amplifier  18 A. To an inverted input terminal on an input side of the operational amplifier  18 A of the amplifier circuit  18 , each of the signal lines  6  is connected. The electric-charge reset switch  18 C of the amplifier circuit  18  is connected to a control member  22 , and controlled to be turned on/off by the control member  22 . Incidentally, the power source circuit  51  supplies the power to the operational amplifier  18 A and the like. This point will be described later. 
     At the time of the readout processing of the image data D from the radiation detecting elements  7  after imaging, when the TFTs  8  of the radiation detecting elements  7  become on-state while the electric-charge reset switch  18 C of the amplifier circuit  18  in the readout circuit  17  is in the off state, the electric charges discharged from the radiation detecting elements  7  via the TFTs  8  pass though the signal lines  6  to flow into the capacitors  18 B of the amplifier circuits  18 , and thereby the electric charges are accumulated in the capacitors  18 B. Then each of the amplifier circuits  18  outputs a voltage value depending on a quantity of the electric charge accumulated in the capacitor  18 B from the output side. 
     The correlated double sampling circuit  19  retains the output values from the amplifier circuit  18  before and after the flow of the electric charges from the radiation detecting elements  7 , and outputs a difference between these output values toward the downstream side as the image data D having an analog value. Then the output image data D is sequentially transmitted to the A/D convertor  20  via the analog multiplexer  21  (see  FIG. 3 ), sequentially converted into the image data D having a digital value by the A/D convertor  20 , and output to a storage member  23  and sequentially stored therein. Thus the readout processing of the image data D is performed. 
     The control member  22  is composed of a computer including a not-illustrated Central Processing Unit (CPU), Read Only Memory (ROM), Random Access Memory (RAM), input/output interface, etc. which are connected to a bus, and a Field Programmable Gate Array (FPGA), and so on. Alternatively, the control member  22  may be composed of a dedicated control circuit. 
     The control member  22  controls the operations of the respective functional sections of the radiographic image capturing apparatus  1 , for example, controls the scan driving member  15  and/or the readout circuit  17  so that the readout processing of the image data D is performed as described above. As illustrated in  FIGS. 3 and 4 , the storage member  23  composed of a Static RAM (SRAM), Synchronous DRAM (SDRAM), or the like is connected to the control member  22 . Moreover, to the control member  22  of the embodiment, the above-described antenna  41  is connected, and also the battery  24  which supplies the necessary power to the functional sections such as the scan driving member  15 , readout circuit  17 , storage member  23 , bias power source  14 , etc. is connected. 
     In the embodiment, the radiographic image capturing apparatus  1  is configured so that the imaging mode can be switched at least between a wake up mode in which the power is supplied to the functional sections such as the control member  22  so that imaging can be performed, and a sleep mode in which the power is applied to required minimum functional sections and the imaging cannot be performed. 
     At that time, the readout circuit  17  consumes relatively large power at the time of the readout operation of the image data D and the like as described above. Accordingly, though the sleep mode can take various forms, at least the readout operation by the readout circuit  17  is not performed in the sleep mode of the embodiment. 
     Configuration and the Like Specific to the Present Invention 
     Next, the configuration specific to the present invention in the radiographic image capturing apparatus  1  of the embodiment will be described. 
     As described above, when the imaging is performed after the power mode of the radiographic image capturing apparatus  1  is switched from the sleep mode to the imagable mode, some offset is superimposed on the image data D which has been read out after the imaging, and sometimes image unevenness and/or stripe pattern appear, though only slightly, in the radiographic image generated based on the image data D (e.g. see  FIG. 7 ). 
     The inventor has been doing the research about the cause of such a phenomenon, and the following things have come to light. Even when the imaging is performed by the radiographic image capturing apparatus  1  in the imagable mode, and after the imaging, the power mode of the radiographic image capturing apparatus  1  is switched to the sleep mode so that the radiographic image capturing apparatus  1  becomes power-saving state, the electric charges in the functional sections of the radiographic image capturing apparatus  1  are not removed immediately, because the electric charges remain in portions, for example, where parasitic capacitance is formed, the portions being, for example, on the side of the detecting section P (see  FIG. 3 ) including the radiation detecting elements  7 , scanning lines  5  and signal lines  6 , on the side of the readout IC  16 , and/or on the side of the after-described power source circuit  51  (see  FIGS. 5A and 5B  to be mentioned later) which supplies the power to the readout IC  16  and the like. 
     Because a removal efficiency of the residual electric charge is different according to each of the readout ICs  16 , the value of the offset to be superimposed on the image data D, the offset being due to the residual electric charge, becomes different according to each of the readout ICs  16 . Such an offset appears as the image unevenness in each of regions R 1 , R 2 , R 3 , R 4 , . . . of the radiographic image I, the regions corresponding to the readout ICs  16 , respectively. Moreover, because the removal efficiency of the residual electric charge is also different according to each of the readout circuits  17 , the value of the offset to be superimposed on the image data D, the offset being due to the residual electric charge, becomes different according to each of the readout circuits  17 . This seems the reason why the stripe patterns corresponding to the readout circuits  17  appear in the radiographic image I. 
     Consequently, the present invention adopts the configuration where a discharge circuit is provided on a path (hereinafter referred to as a power supplying path) through which the power source circuit  51  supplies the power to the readout IC  16 . The power supplying path can be connected to a GND by the discharge circuit. The discharge circuit makes the power supplying path and the GND connected to each other while the power mode of the radiographic image capturing apparatus  1  is set to the sleep mode. 
     Hereinafter the configuration including the discharge circuit and the power source circuit  51  will be described in detail.  FIG. 5A  is a block diagram illustrating a configuration example of the discharge circuit, and  FIG. 5B  is a block diagram illustrating a configuration example of a part including the discharge circuit, power source circuit, etc. in the radiographic image capturing apparatus of the embodiment. Incidentally, though only the power source circuits  51  and power supplying paths  50  for supplying the power to the readout IC  16  are illustrated in  FIG. 5B , it is needless to say that other power source circuits, power supplying paths and the like for supplying the power to other functional sections of the radiographic image capturing apparatus  1 , such as the bias power source  14  and the power source circuit  15 A of the scan driving member  15 , can be arbitrary provided. 
     As illustrated in  FIG. 5A , the discharge circuit  60  of the embodiment is disposed on the power supplying path  50  through which the after-described power source circuit  51  supplies the power to the readout IC  16 . On a wiring  61  connecting the power supplying path  50  to the GND in the discharge circuit  60 , there is provided a switch element  62  which is composed of, for example, a Field Effect Transistor (FET). The switch element  62  is controlled to be turned on/off by control signals from the control member  22  (see  FIG. 3  and the like). Additionally, a resistance  63  is disposed on the wiring  61  which connects the power supplying path  50  to the switch element  62  so that the electric discharges are prevented from flowing into the GND at once when the switch element  62  is turned on. 
     In the embodiment, as illustrated in  FIG. 5B , the power source circuit  51  is disposed on a power source substrate  52 . The above-described battery  24  which is composed of, for example, a lithium ion capacitor supplies the power to the power source circuit  51 . As the power source circuit  51 , there are provided a power source circuit  51 A for supplying the power to an analog circuit such as the operation amplifier  18 A of the amplifier circuit  18  in the readout IC  16 , and a power source circuit  51 B for supplying the power to a digital circuit such as the A/D convertor  20  (see  FIGS. 3 and 4 ) in the readout IC  16 . In the embodiment, each of the power source circuits  51 A,  51 B is composed of a DC/DC convertor or the like, and outputs a predetermined voltage value to each of the power supplying paths  50 A,  50 B. 
     Additionally, a constant voltage DC power source circuit  53  is disposed on the power supplying path  50 A connected to the power source circuit  51 A. As the constant voltage DC power source circuit, for example, a Low Drop-Out regulator may be used. 
     Incidentally,  FIG. 4  illustrates only the path through which the power source circuit  51  (i.e. the power source circuit  51 A in this case) supplies the power to the operational amplifier  18 A of the amplifier circuit  18  in the readout circuit  17 , and the illustrations of a path through which the power source circuit  51 A supplies the power to other analog circuits in the readout IC  16 , a path through which the power source circuit  51 B supplies the power to the digital circuits in the readout IC  16  such as the A/D convertor  20 , and so on are omitted in  FIG. 4 . Also the constant voltage DC power source circuit  53 , the discharge circuit  60 , etc. are omitted in  FIG. 4 . 
     In the embodiment, a substrate  54  including the constant voltage DC power source circuit  53  is connected to the sensor substrate  4  (see  FIGS. 1 and 2 ) of the sensor panel SP via a flexible circuit substrate  55 . The readout ICs  16  are incorporated on the film of the flexible circuit substrate  55 . The required number of the readout ICs  16  are provided correspondingly to the number or the signal lines  6  or the like, as described above. 
     In the embodiment, the discharge circuit  60  illustrated in  FIG. 5A  is disposed on the power supplying path  50 A connecting the constant voltage DC power source circuit  53  and the readout IC  16  to each other. The discharge circuit  60  is disposed also on the power supplying path  50 B connecting the power source circuit  51 B for supplying the power to the digital circuit and the readout IC  16  to each other. 
     Incidentally, though  FIG. 5B  illustrates the case that the discharge circuit  60  on the power supplying path  50 B is disposed on the substrate  54 , the discharge circuit  60  can also be disposed on the power source substrate  52  (i.e. in the vicinity of the power source circuit  51 B). The discharge circuits  60  are thus disposed on the appropriate positions on the power supplying paths  50 A,  50 B. 
     Operations 
     Next, the operations of the radiographic image capturing apparatus  1  of the embodiment will be described. 
     When the imaging is performed by the radiographic image capturing apparatus  1  while the power mode of the radiographic image capturing apparatus  1  is set to the imagable mode, if the power supplying path  50  is connected to the GND, the power, which is to be supplied to the readout IC  16  from the power source circuit  51 , would be released to the GND. As a result, the readout IC  16  cannot accurately function, the image data D cannot be read out from the radiation detecting elements  7 , and the imaging cannot be accurately performed. 
     For this reason, the discharge circuit  60  does not connect the power supplying path  50  to the GND when the power mode of the radiographic image capturing apparatus  1  is set to the imagable mode. Concretely, the control member  22  controls the switch element  62  (see  FIG. 5A ) of the discharge circuit  60  so that it becomes off-state in the imagable mode. 
     The control member  22  switches the power mode of the radiographic image capturing apparatus  1  from the imagable mode to the sleep mode at the appropriate timing, such as the timing when the imaging is completed, and the timing when non-imaging state continues for a predetermined time. At that time, the control member  22  executes the control so that the switch element  62  of the discharge circuit  60  is turned on, and thereby the power supplying path  50  is connected to the GND. 
     When the discharge circuit  60  connects the power supplying path  50  to the GND, the electric charges remaining on the side of the power source circuit  51  (see  FIG. 5B ) flow into the discharge circuit  60  from the power supplying path  50 , and flow out toward the GND through the switch element  62 . The electric charges remaining on the side of the power source circuit  51  are thus removed, by the discharge circuit  60 , from the side of the power source circuit  51  accurately. 
     Moreover, when the discharge circuit  60  connects the power supplying path  50  to the GND, the electric charges remaining on the side of the readout IC  16  (see  FIG. 5B ) flow into the discharge circuit  60  from the power supplying path  50 , and flow out toward the GND through the switch element  62 . The electric charges remaining on the side of the readout IC  16  are thus removed, by the discharge circuit  60 , from the side of the readout IC  16  accurately. 
     In the meantime, the sensor panel SP has the configuration where at least one insulating layer is disposed between adjacent components among the scanning lines  5 , signal lines  6 , radiation detecting elements  7 , TFT  8 , bias lines  9 , and so on (see  FIGS. 2 and 3 ) and the parasitic capacitances are formed in various portions. For this reason, even when the power mode of the radiographic image capturing apparatus  1  is switched to the sleep mode, the electric charges are trapped in the portions of the parasitic capacitances and remain therein, and cannot always be removed easily. 
     However, when the discharge circuit  60  connects the power supplying path  50  to the GND at the time of shift of the power mode from the imagable mode to the sleep mode as the embodiment, the electric charges remaining in the sensor panel SP flow into the readout IC  16  from the sensor panel SP via the signal lines  6  as illustrated in  FIG. 5B , and the electric charges, which has flowed into the readout IC  16 , flow into the discharge circuit  60  via the power supplying path  50  and flow out toward the GND. 
     Accordingly, the configuration of the embodiment can accurately remove the electric charges remaining not only in the power source circuit  51  and/or the readout IC  16  but also in the sensor panel SP so that the electric charges flow out toward the GND via the discharge circuit  60  and can be accurately removed. 
     As described above, because the removal efficiency of the residual electric charges in the sleep mode is different according to each of the readout ICs  16  or each of the readout circuits  17 , a conventional radiographic image capturing apparatus reaches the state that a residual amount of the electric charges which have not been removed during the sleep mode is different according to each of the readout ICs  16  or each of the readout circuits  17 . 
     If the power mode is switched from the sleep mode to the imagable mode and then the imaging is performed during the radiographic image capturing apparatus is in the above state, the offset to be superimposed on the image data D, the offset being due to the residual electric charge, would become different according to each of the readout ICs  16  so that the image unevenness appears in the radiographic image I, and/or the offset to be superimposed on the image data D, the offset being due to the residual electric charge, would become different according to each of the readout circuits  17  so that the stripe pattern appears in the radiographic image I (see  FIG. 7 ). 
     On the contrary, the radiographic image capturing apparatus  1  of the embodiment has the configuration where the discharge circuits  60  are provided on the power supplying paths  50 , and the discharge circuit  60  connects the power supplying path  50  to the GND while the power mode of the radiographic image capturing apparatus  1  is set to the sleep mode so that the electric charges remaining in the power source circuit  51 , readout IC  16 , sensor panel SP, and so on are proactively removed toward the GND. 
     According to the configuration, even when the removal efficiency of the residual electric charges in the sleep mode is different according to each of the readout ICs  16  or each of the readout circuits  17 , the discharge circuit  60  proactively makes the residual electric charges flow out toward the GND, and thereby the electric charges are removed from the apparatus. Accordingly, the radiographic image capturing apparatus  1  can maintain the state that the electric charges hardly remain in the power source circuit  51 , readout IC  16 , sensor panel SP, and so on while the sleep mode is continued. 
     After that, when the power mode is switched from the sleep mode to the imagable mode and then the imaging is performed, the offsets due to the residual electric charges are not superimposed (or are hardly superimposed) on the image data D. Accordingly, the radiographic image I generated based on the read-out image data D does not include the image unevenness caused by a difference in the removal efficiency of the residual electric charges according to each of the readout ICs  16 , or the stripe pattern caused by a difference in the removal efficiency of the residual electric charges according to each of the readout circuits  17 . 
     Effects 
     As described above, according to the radiographic image capturing apparatus  1  of the embodiment, the discharge circuits  60  capable of connecting the power supplying path  50  and the GND to each other are disposed on the power supplying paths  50  through which the power source circuits  51  supply the power to the readout IC  16 , and the discharge circuit  60  connects the power supplying path  50  and the GND to each other while the power mode of the radiographic image capturing apparatus  1  is set to the sleep mode. 
     Thus, the electric charges remaining in the power source circuit  51 , readout IC  16  and sensor panel SP can be accurately removed because the discharge circuit  60  proactively makes the electric charges flow out toward the GND during the sleep mode. Even when the power mode is switched from the sleep mode to the imagable mode and the imaging is performed after that, the offsets due to the residual electric charges can be accurately prevented from being superimposed on the image data D, and the image unevenness and/or stripe pattern can be prevented from appearing in the radiographic image I generated based on the read-out image data D. 
     Incidentally, according to the research of the inventor, it has been confirmed that the radiographic image I includes no image unevenness or stripe pattern, or at least the image unevenness and/or stripe pattern cannot be visually confirmed in the radiographic image I, when the radiographic image capturing apparatus  1  is actually configured to have the configuration of the embodiment. 
     Others Such as Variations 
     The configuration of the part including the discharge circuit  60 , power source circuit  51 , etc. of the radiographic image capturing apparatus  1  illustrated in  FIG. 5B  is a mere example, and it is needless to say that other necessary configurations such as a low pass filter can be arbitrary provided. 
     In the above embodiment, there is described the case that the control member  22  transmits the control signals to the switch element  62  (see  FIG. 5A ) of the discharge circuit  60  so as to turn on/off the switch element  62 , when the power mode of the radiographic image capturing apparatus  1  is switched to the sleep mode or the imagable mode, so that the discharge circuit  60  connects the power supplying path  50  and the GND to each other and/or cuts the connection theirbetween. 
     Alternatively, for example, the configuration where the discharge circuit  60  itself switches on/off of the switch element  62 , on the basis of the signals for switching the power mode to the sleep or imagable mode transmitted from the control member,  22  so as to connect the power supplying path  50  and the GND to each other or cut the connection theirbetween, may be adopted. 
     Some radiographic image capturing apparatuses  1  are configured so that the power is not supplied also to the control member  22  in the sleep mode. In such a case, for example, a configuration where the switch element  62  of the discharge circuit  60  is automatically turned on/off in accordance with the stop (in the case of the sleep mode) or the activation (in the case of the imagable mode) of the control member  22  may be adopted, instead of controlling the on/off of the switch element  62  of the discharge circuit  60  by the control section  22  as described above. 
     Variation 1 
     As described above, according to the configuration where the discharge circuits  60  are disposed on the power supplying paths  50  through which the power source circuits  51  supply the power to the readout IC  16 , and where the discharge circuit  60  connects the power supplying path  50  to the GND during the sleep mode, the electric charges remaining in the power source circuit  51 , readout IC  16 , sensor panel SP, and so on are removed. 
     Additionally, in order to remove the electric charges remaining in the sensor panel SP more accurately, it is possible to adopt a configuration where the bias power source  14  (see  FIGS. 3 and 4 ) applies the reverse bias voltages to each of the radiation detecting elements  7  via each of the bias lines  9  also in the sleep mode. According to the configuration, the electric charges remaining in the radiation detecting elements  7  can flow out toward the side of the bias power source  14  via the bias lines  9  in the sleep mode, and thereby the electric charges can be accurately removed from the radiation detecting elements  7 . 
     Variation 1-1 
     In this regard, it is possible to adopt a configuration where the bias power source  14  continues to apply the reverse bias voltage to the radiation detecting elements  7  during the sleep mode. According to the configuration, the reverse bias voltage can be continuously applied from the bias power source  14  to the radiation detecting elements  7  during the sleep mode. Therefore, the electric charges remaining in the radiation detecting elements  7  can flow out toward the side of the bias power source  14  so as to be accurately removed from the radiation detecting elements  7 . 
     Variation 1-2 
     It is also possible to adopt a configuration where the bias power source  14  applies the reverse bias voltage Vbias to each of the radiation detecting elements  7  only for a predetermined time At every time the voltage V applied from the bias power source  14  to each of the radiation detecting elements  7  rises and reaches a set threshold Vth. 
     In this case, for example, if the power mode of the radiographic image capturing apparatus  1  is switched from the imagable mode to the sleep mode at time t 0  as illustrated in  FIG. 6 , the voltage V applied from the bias power source  14  to each of the radiation detecting elements  7  gradually rises from the reverse bias voltage Vbias. When the voltage V reaches the threshold Vth, the bias power source  14  applies the reverse bias voltage Vbias, which has been set to a voltage value lower than the threshold Vth, to each of the radiation detecting elements  7  only for the predetermined time At. Thus, the voltage V applied from the bias power source  14  to each of the radiation detecting elements  7  rises and falls between the reverse bias voltage Vbias and the threshold Vth. 
     According to such a configuration, the voltage V applied from the bias power source  14  to each of the radiation detecting elements  7  becomes the low voltage value within the range from the reverse bias voltage Vbias to the threshold Vth during the sleep mode, and thereby it becomes possible to continuously apply the voltage having such a low voltage value to each of the radiation detecting elements  7  during the sleep mode. Therefore, the electric charges remaining in the radiation detecting elements  7  can flow out toward the side of the bias power source  14  so as to be accurately removed from the radiation detecting elements  7 . Moreover, compared with the case of continuously applying the reverse bias voltage as Variation  1 - 1 , electric power consumption can be further reduced. 
     Variation 1-3 
     Incidentally, it is also possible to adopt a configuration where the bias power source  14  applies the reverse bias voltage Vbias to each of the radiation detecting elements  7  only for the predetermined time At, at every predetermined time AT during the sleep mode, regardless of the voltage V applied from the bias power source  14  to each of the radiation detecting elements  7 , instead of applying the reverse bias voltage Vbias from the bias power source  14  to each of the radiation detecting elements  7  only for the predetermined time At every time the voltage V applied from the bias power source  14  to each of the radiation detecting elements  7  reaches the set threshold Vth during the sleep mode as Variation 1-2. In this case, the predetermined time AT is set to a time according to which the voltage V applied from the bias power source  14  to each of the radiation detecting elements  7  does not become equal to or more than the threshold Vth. 
     According to such a configuration, the voltage V applied from the bias power source  14  to each of the radiation detecting elements  7  can be suppressed to be the low voltage value during the sleep mode, and thereby the electric charges remaining in the radiation detecting elements  7  can flow out toward the side of the bias power source  14  so as to be accurately removed from the radiation detecting elements  7 . Moreover, the reverse bias voltage Vbias only have to be applied from the bias power source  14  to each of the radiation detecting elements  7  only for the predetermined time At every time the predetermined time AT has passed during the sleep mode, the processing can be easily performed. Furthermore, compared with the case of continuously applying the reverse bias voltage Vbias as Variation 1-1, electric power consumption can be further reduced. 
     Variation 2 
     Alternatively, in order to more proactively remove the residual electric charges from the radiation detecting elements  7  during the sleep mode, for example, it is also possible to adopt a configuration where the gate driver  15 B (see  FIG. 3 ) of the scan driving member  15  sequentially or simultaneously applies ON voltages to lines L 1  to Lx of the scanning lines  5  during the sleep mode so that the electric charges are removed from the radiation detecting elements  7 . 
     Similarly to the case of the readout IC  16  illustrated in  FIG. 5B , the battery  24  supplies the power also to the power source circuit  15 A of the scan driving member  15  as illustrated in  FIG. 3 . When the power mode of the radiographic image capturing apparatus  1  is set to the imagable mode, the power source circuit  15 A supplies the ON and OFF voltages to the gate driver  15 B, and the gate driver  15 B switches the power to be applied to each of lines L 1  to Lx of the scanning lines  5  between the ON and OFF voltages. Thus, the ON or OFF voltage is applied to each of lines L 1  to Lx of the scanning lines  5 . 
     Because the supply of the power from the battery  24  to the power source circuit  15 A of the san driving member  15  is stopped in the sleep mode, the voltage applied from the gate driver  15 B to each of lines L 1  to Lx of the scanning lines  5  is in a floating state. The TFTs  8  do not completely become off-state because the gate driver  15 B does not apply at least the OFF voltage to the scanning lines  5  in the sleep mode. Accordingly, the electric charges can outflow toward the side of the signal lines  6  or the side of the bias lines  9  via the TFTs  8  in the above-described state. However, the residual electric charges can be removed from the radiation detecting elements  7  during the sleep mode by the configurations of the above embodiments and Variations. 
     By proactively performing the removing process of the electric charges from the radiation detecting elements  7  during the sleep mode, the residual electric charges can be more accurately removed from the radiation detecting elements  7 . Moreover, according to such a configuration, by more accurately removing the electric charges remaining in the radiation detecting elements  7 , the image unevenness and/or stripe pattern caused by the offsets due to the residual electric charges can be prevented from appearing in the radiographic image I. 
     Incidentally, it is indisputable that the present invention is not limited to the above embodiments and variations, and can be arbitrary changed without departing from the spirit of the present invention. 
     The present U.S. patent application claims a priority under the Paris Convention of Japanese patent application No. 2014-105793 filed on May 22, 2014, in which all contents of this application are disclosed, and which shall be a basis of correction of an incorrect translation.