Abstract:
A radiographic imaging apparatus, comprising: a photoelectric conversion substrate including a pixel area where there are arranged a plurality of pixels each formed of a photoelectric conversion element and a switching element connected to the photoelectric conversion element in a matrix formed on an insulating substrate, a bias line for applying a bias to the photoelectric conversion element, a gate line for supplying a driving signal to the switching element, and a signal line for reading electric charges converted in the photoelectric conversion element; a wavelength conversion element for converting radiation to light that can be detected by the photoelectric conversion element, the wavelength conversion element being disposed according to a region including the pixel area; and connection wiring having a photoelectric conversion layer connected to at least a plurality of lines of one type, that one type being, the bias lines, the signal lines, and the gate lines, wherein at least a part of the connection wiring is arranged between the region on the insulating substrate and an edge of the insulating substrate. With this arrangement, it becomes possible to provide a panel for a radiographic imaging apparatus and a radiographic imaging apparatus free from deterioration in device performance and device destruction caused by a static electricity even if a substrate is electrically charged in a manufacturing process.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a photoelectric conversion substrate, a photoelectric converter, a radiographic imaging substrate, and a radiographic imaging apparatus applied to a medical diagnostic imaging system, a non-destructive inspection device, a radiographic analyzer, or the like. It is assumed in this specification that radiation includes electromagnetic waves including visible light, X-rays, and gamma rays, as well as alpha and beta radiation. 
     2. Description of the Related Art 
     As a conventional typical radiographic imaging apparatus, there is a radiographic imaging apparatus constructed of a combination of a radiographic imaging substrate, on which there are arranged optical sensors of MIS-TFT structure each formed of an MIS-type photoelectric conversion element and a switching TFT, and phosphors for converting radiation to visible light. This type of radiographic imaging apparatus is disclosed in U.S. Pat. No. 6,075,256. 
       FIGS. 13 ,  14 , and  15  show a schematic diagram, an equivalent circuit diagram, and a plan view of a conventional radiographic imaging apparatus, respectively.  FIGS. 16 and 17  show a cross section of a single pixel and an enlarged view of a portion close to a cut section of the radiographic imaging substrate. 
     References P 11  to P 44  designate photoelectric conversion elements or other semiconductor conversion elements and references T 11  to T 44  designate thin film transistors (TFTs), and each pair of them forms a pixel. While a pixel area  2  of 4×4 pixels is shown here, for example, 1000×2000 pixels are practically arranged on a radiographic imaging substrate (insulating substrate)  1 . 
     As shown in  FIGS. 14 and 15 , the photoelectric conversion elements P 11  to P 44  are connected to common bias lines Vs 1  to Vs 4  and a readout device  5  applies a given bias to them. The respective gate electrodes of the TFTs are connected to common gate lines Vg 1  to Vg 4  and a gate drive unit makes an ON-OFF control of the TFT gates. Source or drain electrodes of the TFTs are connected to common signal lines Sig 1  to Sig 4  and Sig 1  to Sig 4  are connected to the readout device  5 . 
     X-rays emitted to a subject are attenuated by, pass through the subject and are converted to visible light in a phosphor layer  19  arranged via a adhesive layer  18  shown in  FIG. 16 . Then, the visible light is incident on the photoelectric conversion elements P 11  to P 44  and converted to electric charges. These charges are transferred to signal lines Sig 1  to Sig 4  via the TFTs T 11  to T 44  by means of gate drive pulses applied by a gate drive unit  4  and then read out to the outside by a readout device  5 . Thereafter, the common bias lines remove residual charges that have been generated in the photoelectric conversion elements P 11  to P 44 , but have not been transferred. 
     The conventional radiographic imaging apparatus has a radiographic imaging substrate  1  cut in a cut section indicated by a dashed line in  FIG. 17 , with the signal lines Sig 1  to Sig 4  and the bias lines Vs 1  to Vs 4  connected to the readout device  5  and the gate lines Vg 1  to Vg 4  connected to the gate drive unit  4  via a printed circuit board such as tape carrier packages (TCPs)  6  and  7 , respectively. It is assumed here that TCP-A 6  is a TCP connected to the readout device  5  and that TCP-D 7  is a TCP connected to the gate drive unit  4 . 
     A layer structure is shown in  FIG. 16 . An MIS-type photoelectric conversion element is formed of an under electrode (first electrode layer  11 ), an insulating layer (first insulating layer  12 ), a photoelectric conversion layer (first semiconductor layer  13 ), a hole blocking layer (doping semiconductor layer  14 ), and an upper electrode (second electrode layer  15 ), with the under electrode (first electrode layer  11 ) connected to a TFT source-drain electrode (second electrode layer  15 ). The TFT includes a gate electrode (first electrode layer  11 ), a gate insulating layer (first insulating layer  12 ), a semiconductor layer (first semiconductor layer  13 ), an ohmic contact layer (doping semiconductor layer  14 ), and a source-drain electrode (second electrode layer  15 ). Each Vg line and each Sig line are connected to the electrode layer where the TFT gate electrode  11  is formed and to the layer where the source-drain electrode  15  is formed, respectively. Moreover, the photoelectric conversion element and the TFT are coated with and protected by a second insulating layer  16  and an organic protective layer  17 . It should be noted here that the first semiconductor layer  13  is formed of an intrinsic semiconductor and that the doping semiconductor layer  14  is formed of an n- or p-type semiconductor to which impurities such as phosphorus or boron have been introduced. 
     SUMMARY OF THE INVENTION 
     In recent years, TFT panels can be produced in large quantities due to developments in technologies of manufacturing liquid crystal panels using TFTs and the expansion of the fields into which there have been introduced area sensors having photoelectric conversion elements (for example, am X-ray imaging apparatus). 
     At the same time, a radiographic imaging apparatus has a characteristic of subjecting minute signals to digital conversion and graphically outputting them, unlike the liquid crystal panels. 
     Therefore, if a substrate is electrically charged in a manufacturing process, and for example, a potential difference occurs between a signal line and a gate line, a Vth shift occurs in a readout TFT and thereby minute signals cannot be read out. 
     In the case of a large potential difference in the above condition, it causes device destruction and thus leads to deterioration of a yield in a manufacturing line for the mass production. 
     The present invention provides a radiographic imaging substrate and a radiographic imaging apparatus free from deterioration in device performance and device destruction caused by static electricity even if a substrate is electrically charged in a manufacturing process. 
     According to one aspect of the present invention, there is provided a radiographic imaging apparatus, comprising: a photoelectric conversion substrate including a pixel area where there are arranged a plurality of pixels each formed of a photoelectric conversion element and a switching element connected to the photoelectric conversion element in a matrix formed on an insulating substrate, a bias line for applying a bias to the photoelectric conversion element, a gate line for supplying a driving signal to the switching element, and a signal line for reading electric charges converted in the photoelectric conversion element; a wavelength conversion element for converting radiation to light that can be detected by the photoelectric conversion element, the wavelength conversion element being arranged according to a region including the pixel area; and connection wiring having a photoelectric conversion layer connected to at least a plurality of lines of one type that one type being the bias lines, the signal lines, and the gate lines, wherein at least a part of the connection wiring is arranged between the region on the insulating substrate and an edge of the insulating substrate. 
     Furthermore, preferably the connection wiring connects all of the bias lines, the gate lines, and the signal lines. 
     Still further, preferably the photoelectric conversion element includes at least an under electrode layer, an upper electrode layer, a photoelectric conversion element semiconductor layer arranged between the under electrode layer and the upper electrode layer, and a doping semiconductor layer arranged between the photoelectric conversion element semiconductor layer and the upper electrode layer. The switching element includes at least a first electrode layer, a second electrode layer, a switching element semiconductor layer arranged between the first electrode layer and the second electrode layer, and an ohmic contact layer arranged between the switching element semiconductor layer and the second electrode layer. The connection wiring further includes the doping semiconductor layer or the ohmic contact layer. If it is defined that Ra is a wiring resistance of the bias line, Rb is a wiring resistance of the gate line, Rc is a wiring resistance of the signal line, Rp is a wiring resistance of the photoelectric conversion layer of the connection wiring between the lines under incident light, Rd is a wiring resistance of the photoelectric conversion layer of the connection wiring between the lines under no incident light, Re is a wiring resistance of the doping semiconductor layer of the connection wiring between the lines, and Rf is a wiring resistance of the ohmic semiconductor layer of the connection wiring between the lines, the following relations are satisfied:
     Ra, Rb, Rc&lt;Re, Rf&lt;Rd   Ra, Rb, Rc&lt;Re, Rf≦Rp   or Ra, Rb, Rc≦Rp&lt;Re, Rf   

     According to another aspect of the present invention, there is provided a panel for a radiographic imaging apparatus, comprising: a photoelectric conversion substrate including a pixel area where there are arranged a plurality of pixels each formed of a photoelectric conversion element and a switching element connected to the photoelectric conversion element in a matrix formed on an insulating substrate, a bias line for applying a bias to the photoelectric conversion element, a gate line for supplying a driving signal to the switching element, and a signal line for reading electric charges converted in the photoelectric conversion element; and a conductive member having a photoelectric conversion layer connected to at least a plurality of lines of one type, that one type being of the bias lines, the signal lines, and the gate lines, wherein at least a part of the conductive member is arranged between a region including a pixel area where there is arranged a wavelength conversion element on the insulating substrate and an edge of the insulating substrate. 
     In the panel for the radiographic imaging apparatus of the present invention, preferably the conductive member is a guard ring and there is a cutting position between the guard ring and the pixel area. 
     According to still another aspect of the present invention, there is provided a method of manufacturing a radiographic imaging apparatus having: a photoelectric conversion substrate including a pixel area where there are arranged a plurality of pixels each formed of a photoelectric conversion element and a switching element connected to the photoelectric conversion element in a matrix formed on an insulating substrate, a bias line for applying a bias to the photoelectric conversion element, a gate line for supplying a driving signal to the switching element, and a signal line for reading electric charges converted in the photoelectric conversion element; a wavelength conversion element for converting radiation to light that can be detected by the photoelectric conversion element, the wavelength conversion element being arranged according to a region including the pixel area; and connection wiring having a photoelectric conversion layer connected to at least a plurality of lines of one type, that one type being the bias lines, the signal lines, and the gate lines, the method comprising the step of forming at least a part of the connection wiring between the region on the insulating substrate and an edge of the insulating substrate. 
     According to still another aspect of the present invention, there is provided a method of manufacturing a panel for a radiographic imaging apparatus, the panel having: a photoelectric conversion substrate including a pixel area where there are arranged a plurality of pixels each formed of a photoelectric conversion element and a switching element connected to the photoelectric conversion element in a matrix formed on an insulating substrate, a bias line for applying a bias to the photoelectric conversion element, a gate line for supplying a driving signal to the switching element, and a signal line for reading electric charges converted in the photoelectric conversion element; and a conductive member having a photoelectric conversion layer connected to at least a plurality of lines of one type, that one type being, the bias lines, the signal lines, and the gate lines, the method comprising the step of forming at least a part of the conductive member between a region including a pixel area where there is arranged a wavelength conversion element on the insulating substrate and an edge of the insulating substrate. 
     In this method of the present invention, preferably the conductive member is a guard ring and the method further includes the step of cutting the insulating substrate between the guard ring and the pixel area. 
     According to the present invention, there is formed the connection wiring or the conductive member such as the guard ring having at least the photoelectric conversion layer outside the pixel area, and at least two lines of the Vs lines, the Vg lines, and the Sig lines can be connected together via the conductive member, thereby preventing deterioration in device performance and device destruction caused by a static electricity even if the substrate is electrically charged in a manufacturing process. 
     Further features and advantages of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a radiographic imaging apparatus for explaining a first embodiment of a radiographic imaging substrate and a radiographic imaging apparatus according to the present invention. 
         FIG. 2  is an equivalent circuit diagram of the radiographic imaging apparatus for explaining the first embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 3  is an enlarged view of a portion close to a cut section of the radiographic imaging substrate for explaining the first embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 4A  is a cross-section taken on line A—A of  FIG. 3  for explaining the first embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 4B  is a cross-section taken on line B—B of  FIG. 3  for explaining the first embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 5  is a schematic diagram of a radiographic imaging apparatus for explaining a second embodiment of a radiographic imaging substrate and a radiographic imaging apparatus according to the present invention. 
         FIG. 6  is an equivalent circuit diagram of the radiographic imaging apparatus for explaining the second embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 7  is an enlarged view of a portion close to a cut section of the radiographic imaging substrate for explaining the second embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 8A  is a cross-section taken on line A—A of  FIG. 7  for explaining the second embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 8B  is a cross-section taken on line B—B of  FIG. 7  for explaining the second embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 9  is a schematic diagram of a radiographic imaging apparatus for explaining a third embodiment of a radiographic imaging substrate and a radiographic imaging apparatus according to the present invention. 
         FIG. 10  is an enlarged view of a portion close to a cut section of the radiographic imaging substrate for explaining the third embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 11A  is a cross-section taken on line A—A of  FIG. 10  for explaining the third embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 11B  is a cross-section taken on line B—B of  FIG. 10  for explaining the third embodiment of the radiographic imaging substrate and the radiographic imaging apparatus according to the present invention. 
         FIG. 12  is a schematic diagram for explaining an application in which the radiographic imaging substrate and the radiographic imaging apparatus of the present invention are applied to an X-ray diagnostic apparatus. 
         FIG. 13  is a schematic diagram of a conventional radiographic imaging substrate and radiographic imaging apparatus. 
         FIG. 14  is an equivalent circuit diagram of the conventional radiographic imaging substrate and radiographic imaging apparatus. 
         FIG. 15  is a plan view of the conventional radiographic imaging substrate and radiographic imaging apparatus. 
         FIG. 16  is a cross-section of a single pixel of the conventional radiographic imaging substrate and radiographic imaging apparatus. 
         FIG. 17  is an enlarged view of a portion close to a cut section of the conventional radiographic imaging substrate. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will be described in detail in accordance with the accompanying drawings. 
     [First Embodiment] 
     Hereinafter, a first embodiment of a radiographic imaging substrate and a radiographic imaging apparatus according to the present invention will be described with reference to accompanying drawings. 
     Referring to  FIGS. 1 ,  2 ,  3 , and  4 , there are shown a schematic diagram of the radiographic imaging apparatus of the present invention, an equivalent circuit diagram thereof, an enlarged view of a portion close to a cut section of the radiographic imaging substrate (insulating substrate), and cross sections of a single pixel and connection wiring, respectively. Regarding  FIG. 4 ,  FIG. 4A  shows the cross section of the single pixel (on line A—A of  FIG. 3 ) and  FIG. 4B  shows the cross section of the connection wiring (on line B—B of  FIG. 3 ). 
     The radiographic imaging apparatus of the present invention is constructed of a combination of a radiographic imaging substrate, on which there are arranged optical sensors of MIS-TFT structure each formed of an MIS-type photoelectric conversion element and a switching TFT, and phosphors for converting radiation to visible light, and other elements including a principle of driving are the same as those of the conventional art. Therefore, their description is omitted here. 
     As shown, gate lines Vg 1  to Vg 4  (Vg lines) are formed in a first electrode layer  11  in a pixel area and in a second electrode layer in a TCP-D connection pad portion  10  and are connected together via contact holes. All of bias lines Vs 1  to Vs 4  (Vs lines), gate lines Vg 1  to Vg 4  (Vg lines), and signal lines Sig 1  to Sig 4  (Sig lines) are connected together via connection wiring  3 . The connection wiring  3  is arranged in a region between the region  11  where there is formed a phosphor layer  19  including a pixel area  2  and an edge of the insulating substrate. 
     As shown in  FIG. 3 , the connection wiring  3  is formed of a first semiconductor layer  13  and a doping semiconductor layer  14  similarly to the MIS-type photoelectric conversion element. Moreover, in this embodiment, the doping semiconductor layers  14  are used as a hole blocking layer and an ohmic contact layer. The doping semiconductor layer  14  is formed of an n-type semiconductor into which phosphorus as impurity is introduced. If the photoelectric conversion element is of PIN type, the doping semiconductor layer  14  is formed of a p-type semiconductor into which boron is introduced. 
     It should be noted here that the first semiconductor layer  13  has a characteristic of a high resistance under no incident light and of a low resistance under incident light due to holes and electrons generated in the layer. 
     Therefore, if it is defined that Ra is a wiring resistance of a bias line (Vs line), Rb is a wiring resistance of a gate line (Vg line), Rc is a wiring resistance of a signal line (Sig line), Rp is a wiring resistance of the first semiconductor layer  13  of the connection wiring  3  between the lines under incident light, Rd is a wiring resistance of the first semiconductor layer  13  of the connection wiring between the lines under no incident light, and Re is a wiring resistance of the doping semiconductor layer  14 , the following relations are satisfied:
     Ra, Rb, Rc&lt;Re&lt;Rd
       Ra, Rb, Rc&lt;Re≦Rp or Ra, Rb, Rc≦Rp&lt;Re   
       

     Therefore, for example, even if the insulating substrate  1  is electrically charged in a manufacturing process, the resistance of the connection wiring  3  is low since the product is manufactured in an environment in which light is incident on the insulating substrate  1  and a potential difference between the lines is unlikely to occur since all of the bias lines Vs 1  to Vs 4  (Vs lines), the gate lines Vg 1  to Vg 4  (Vg lines), and the signal lines Sig 1  to Sig 4  (Sig lines) are connected together via the connection wiring  3 . Therefore, it is possible to prevent static electricity generated in the manufacturing process from passing through the lines and damaging the photoelectric conversion elements P 11  to P 41  or the TFTs T 11  to T 41 . 
     Moreover, the radiographic imaging apparatus with the radiographic imaging substrate  1  has the phosphor layer  19  formed on the region including the pixel area  2  as shown in  FIG. 4A  and has no phosphor layer  19  on the region where the connection wiring  3  is formed as shown in  FIG. 4B . Therefore, in the radiographic imaging apparatus housed in a cabinet (not shown), no external light nor light emitted from the phosphor layer  19  will be incident on the connection wiring  3 , and thus the resistance of the connection wiring  3  is high and they have no influence on the operation of the radiographic imaging apparatus. 
     Furthermore, a panel inspection using TCP connection pads  9  and  10  is also performed in an environment in which no light is incident on the panel, and therefore the light has no influence on the inspection. 
     As stated above, the connection wiring  3  having at least a photoelectric conversion layer (first semiconductor layer  13 ) is formed in a region between the region where there is formed the phosphor layer  19  including the pixel area  2  and the edge of the insulating substrate  1  and the bias lines Vs 1  to Vs 4  (Vs lines), the gate lines Vg 1  to Vg 4  (Vg lines), and the signal lines Sig 1  to Sig 4  (Sig lines) are connected together via the connection wiring  3 , thereby offering an effect of preventing deterioration in device performance and device destruction from being caused by static electricity even if the substrate is electrically charged in a manufacturing process. 
     While the same doping semiconductor layers  14  have been used as the hole blocking layer and the ohmic contact layer in this embodiment, either the hole blocking layer or the ohmic contact layer can be used as the connection wiring  3  if these layers are separate from each other. 
     Moreover, while the MIS-type photoelectric conversion element has been used as the semiconductor conversion element in this embodiment, the PIN-type photoelectric conversion element is also applicable. Regarding the pixel structure, either type of the following is applicable: a flat type in which a semiconductor conversion element and a switching element are formed in an identical layer and a stacked type in which a semiconductor conversion element is formed on a layer where a switching element is formed. 
     [Second Embodiment] 
     The following describes a second embodiment of a radiographic imaging substrate and a radiographic imaging apparatus according to the present invention with reference to accompanying drawings. 
     Referring to  FIGS. 5 ,  6 ,  7 , and  8 , there are shown a schematic diagram of the radiographic imaging apparatus of the present invention, an equivalent circuit diagram thereof, an enlarged view of a portion close to a cut section of the radiographic imaging substrate (insulating substrate), and cross sections of a single pixel and a guard ring, respectively. Regarding  FIG. 8 ,  FIG. 8A  shows the cross section of the single pixel (on line A—A of  FIG. 7 ) and  FIG. 8B  shows the cross section of the guard ring (on line B—B of  FIG. 7 ). 
     As shown, references P 11  to P 44  designate photoelectric conversion elements and references T 11  to T 44  designate first switching elements (TFTs). As shown, the photoelectric conversion elements P 11  to P 44  are connected to bias lines Vs 1  to Vs 4  and a first readout device  22  and a second readout device  23  apply biases to them. Gate electrodes of the TFTs are connected to gate lines Vg 1  to Vg 4  and the gate lines are connected to a first gate drive unit  20  and a second gate drive unit  21 . Moreover, as shown, source or drain electrodes of the TFTs are connected to common signal lines Sig 1  to Sig 8 . The Sig 1  to Sig 4  are connected to the first readout device  22  and similarly Sig 5  to Sig 8  are connected to the second readout device  23 . 
     The radiographic imaging apparatus of the present invention is constructed of a combination of a radiographic imaging substrate  1 , on which there are arranged optical sensors of MIS-TFT structure each formed of an MIS-type photoelectric conversion element and a switching TFT, and phosphors for converting radiation to visible light, and others including a principle of driving are the same as those of the conventional art. Therefore, their description is omitted here. 
     As shown, in the radiographic imaging substrate of this embodiment, gate lines are formed in a first electrode layer  11  in a pixel area  2  and in a second electrode layer in a TCP-D connection pad portion  10  and are connected together via contact holes. In addition, a guard ring  24  is formed in a region between a region where there is formed a phosphor layer  19  including a pixel area  2  and an edge of an insulating substrate  1 . The bias lines Vs 1  to Vs 4  (Vs lines), the gate lines Vg 1  to Vg 4  (Vg lines), and the signal lines Sig 1  to Sig 4  (Sig lines) are connected to the guard ring  24 . In this regard, it is assumed that the guard ring is a conductive member formed substantially in a ring shape around the pixel area  2  for the purpose of preventing an electrostatic destruction of the pixel area in the present invention. 
     Furthermore, as shown in the cross section in  FIG. 8B , the guard ring  24  is formed of a first electrode layer  11 , a first insulating layer  12 , and a first semiconductor layer  13  similarly to the MIS-type photoelectric conversion element, with the lines connected to the guard ring  24  via a doping semiconductor layer  14  and the doping semiconductor layer  14  arranged separately from the lines. 
     It should be noted here that the first semiconductor layer  13  has a characteristic of a high resistance under no incident light and of a low resistance under incident light due to holes and electrons generated in the layer, similarly to the first embodiment. 
     Therefore, for example, even if the insulating substrate  1  is electrically charged in a manufacturing process, the resistance of the connection wiring is low since the product is manufactured in an environment in which light is incident on the insulating substrate  1  and a potential difference between the lines is hard to occur since all of the bias lines Vs 1  to Vs 4  (Vs lines), the gate lines Vg 1  to Vg 4  (Vg lines), and the signal lines Sig 1  to Sig 4  (Sig lines) are connected together via the guard ring  24 . Therefore, it is possible to prevent static electricity generated in the manufacturing process from passing through the lines and damaging the photoelectric conversion elements P 11  to P 41  or the TFTs T 11  to T 41 . 
     Furthermore, a panel inspection using TCP connection pads  9  and  10  is performed in an environment in which no light is incident on the panel, and therefore the light has no influence on the inspection. 
     Furthermore, as shown in  FIG. 7 , there is provided a cut section (indicated by a dashed line in  FIG. 7 ) of the insulating substrate  1  between the pixel area  2  and the guard ring  24 . Therefore, on the radiographic imaging substrate  1  after cutting, the lines are separated from each other and this arrangement has no influence on the operation of the radiographic imaging apparatus. 
     As stated above, the guard ring  24  having at least the photoelectric conversion layer (first semiconductor layer  13 ) is formed in a region between the region where there is formed the phosphor layer  19  including the pixel area  2  and the edge of the insulating substrate  1 . It is then connected to one of the bias lines Vs 1  to Vs 4  (Vs lines), the gate lines Vg 1  to Vg 4  (Vg lines), and the signal lines Sig 1  to Sig 4  (Sig lines) and a cut section of the insulating substrate is provided between the pixel area  2  and the guard ring  24 , thereby offering an effect of preventing deterioration in device performance and device destruction from being caused by static electricity even if the substrate is electrically charged in a manufacturing process. 
     While the lines and the guard ring  24  have been connected via the hole blocking layer (doping semiconductor layer  14 ) in this embodiment, it can be an ohmic contact layer (doping semiconductor layer  14 ) for forming a switching element. 
     Moreover, while the MIS-type photoelectric conversion element has been used as the semiconductor conversion element in this embodiment, the PIN-type photoelectric conversion element is also applicable. Regarding the pixel structure, either type of the following is applicable: a flat type in which a semiconductor conversion element and a switching element are formed in an identical layer and a stacked type in which a semiconductor conversion element is formed on a layer where a switching element is formed. 
     [Third Embodiment] 
     The following describes a third embodiment of a radiographic imaging substrate and a radiographic imaging apparatus according to the present invention with reference to accompanying drawings. 
     Referring to  FIGS. 9 ,  10 , and  11 , there are shown a schematic diagram of the radiographic imaging apparatus of the present invention, an enlarged view of a portion close to a cut section of the radiographic imaging substrate (an insulating substrate), and cross sections of a single pixel and connection wiring  1 , respectively. Regarding  FIG. 11 ,  FIG. 11A  shows the cross section of the single pixel (on line A—A of  FIG. 10 ) and  FIG. 11B  shows the cross section of the connection wiring  3  (on line B—B of  FIG. 10 ). An equivalent circuit is the same as for the second embodiment and therefore its description is omitted here. 
     The radiographic imaging apparatus of the present invention is constructed of a combination of a radiographic imaging substrate, on which there are arranged optical sensors of MIS-TFT structure each formed of an MIS-type photoelectric conversion element and a switching TFT, and phosphors for converting radiation to visible light, and other elements including a principle of driving are the same as those of the conventional art. Therefore, their description is omitted here. 
     Regarding the layer structure of the radiographic imaging apparatus of this embodiment, as shown in  FIGS. 11A and 11B , the TFT includes a gate electrode (first electrode layer  11 ), a gate insulating layer (first insulating layer  12 ), a first semiconductor layer  13 , an ohmic contact layer (doping semiconductor layer  14 ), and a source-drain electrode (second electrode layer  15 ). Each gate line Vg 1  to Vg 3  (Vg line) is connected to the first electrode layer  11  where the gate electrode of the TFT is formed and each signal line Sig 2  to Sig 4  (Sig line) is connected to the second electrode layer  15  where the source-drain electrode is formed. A second insulating layer  16  is disposed on the TFT and an MIS-type photoelectric conversion element is formed thereon. The MIS-type photoelectric conversion element is formed of an under electrode (third electrode layer  27 ), an insulating layer (third insulating layer  28 ), a photoelectric conversion layer (second semiconductor layer  29 ), a hole blocking layer (second doping semiconductor layer  30 ), a bias line (fourth electrode layer  31 ), and an upper electrode (transparent electrode layer  32 ), with the under electrode  27  connected to the source-drain electrode  15  of the TFT. The photoelectric conversion element and the TFT are then coated with and protected by a fourth insulating layer  33  and an organic protective layer  17 . 
     In the radiographic imaging substrate of this embodiment, bias lines (Vs lines) in both end portions connected to a first readout device  22  and to a second readout device  23  are connected to all gate lines Vg 1  to Vg 3  (Vg lines) via first connection wiring  25  in a region where there is formed a phosphor layer  19  including a pixel area  2 . In this regard, the gate lines (Vs lines) are connected via Vs connection wiring  25 ′ in a region outside the pixel area  2  and within a region where a phosphor layer  19  is formed. In other words, in this embodiment, all the Vs lines are connected to all the Vg lines via the first connection wiring  25  and the Vs connection wiring  25 ′ in the region where there is formed the phosphor layer  19  including the pixel area  2 . Moreover, all the gate lines (Vg lines) are connected together via the first connection wiring  25  in a region between the region where there is formed the phosphor layer  19  including the pixel area  2  and an edge of the insulating substrate  1 . Each bias line Vg 1  to Vg 3  (Vg line) and each signal line Sig 2  to Sig 4  (Sig line) form a contact hole outside the pixel area  2  and connected to the fourth electrode layer  31  forming the bias line (Vg line) via the third electrode layer  27 , thereby forming TCP connection pads  9  and  10  in the fourth electrode layer  31 . Furthermore, as shown in the cross section, the first connection wiring  25  is formed of the first semiconductor layer  13  and the ohmic contact layer (doping semiconductor layer  14 ) similarly to the TFT. While second connection wiring  26  is divided at contact holes of the bias lines (Vg lines) here, it may not be divided. 
     It should be noted here that the first semiconductor layer  13  has a characteristic of a high resistance under no incident light and of a low resistance under incident light due to holes and electrons generated in the layer. Therefore, if it is defined that Ra is a wiring resistance of a bias line (Vs line), Rb is a wiring resistance of a gate line (Vg line), Rp is a wiring resistance of the first semiconductor layer  13  of each connection wiring under incident light, Rd is a wiring resistance of the first semiconductor layer  13  between the gate lines under no incident light, and Rf is a wiring resistance of the ohmic contact layer not divided, the following relations are satisfied:
     Ra, Rb&lt;Rf&lt;Rd
       Ra, Rb&lt;Rf≦Rp
 
Since the connection wiring has the relation Rf&lt;Rp between the gate lines, the first connection wiring and the second connection wiring are arranged to achieve Rf≦Rp.
   
       

     Therefore, for example, even if the insulating substrate  1  is electrically charged in a manufacturing process, the resistance of the connection wiring  3  is low since the product is manufactured in an environment in which light is incident on the insulating substrate  1  and a potential difference between the lines is unlikely to occur since all of the bias lines (Vs lines) and the gate lines (Vg lines) are connected via the first connection wiring  25 , the Vs connection wiring  25 ′, and the second connection wiring  26 . Therefore, it is possible to prevent static electricity generated in the manufacturing process from passing through the lines and damaging the photoelectric conversion elements or the TFTs. 
     Moreover, the radiographic imaging apparatus with the radiographic imaging substrate has the phosphor layer  19  formed on the region including the pixel area  2  as shown in  FIG. 10  and has no phosphor layer  19  on the region where the second connection wiring  26  is formed. Therefore, in the radiographic imaging apparatus housed in a cabinet (not shown), no external light nor light emitted from the phosphor layer  19  will be incident on the second connection wiring  26 , and thus the resistance of the second connection wiring  26  is high and practically the connection wiring has the relations Rf&lt;Rd and Rf&lt;Rp between the gate lines. Therefore, they have no influence on the operation of the radiographic imaging apparatus. 
     As stated above, a part of the connection wiring (the second connection wiring  26  in this embodiment) having at least the photoelectric conversion layer (first semiconductor layer  13 ) is formed in the region between the region where there is formed the phosphor layer  19  including the pixel area  2  and the edge of the insulating substrate  1 , and the bias lines (Vs lines) and the gate lines (Vg lines) are connected together via the connection wiring (the first connection wiring  25 , the Vs connection wiring  25 ′, and the second connection wiring  26 ), thereby offering an effect of preventing deterioration in device performance and device destruction from being caused by static electricity even if the substrate is electrically charged in a manufacturing process. 
     Moreover, while the MIS-type photoelectric conversion element has been used as the semiconductor conversion element in this embodiment, the PIN-type photoelectric conversion element is also applicable. Regarding the pixel structure, either type of the following is applicable: a stacked type in which a semiconductor conversion element is formed on a layer where a switching element is formed and a flat type in which a semiconductor conversion element and a switching element are formed in an identical layer. 
     [Fourth Embodiment] 
     Referring to  FIG. 12 , there is shown an application in which a radiographic imaging substrate and a radiographic imaging apparatus according to the present invention are applied to an X-ray diagnostic system. 
     X-rays  6060  generated in an X-ray tube  6050  pass through a chest  6062  of a patient or subject  6061  and impinge on a radiographic imaging apparatus  6040  provided with a scintillator in its upper portion. 
     The incident X-rays include information on the inside of the body of the patient  6061 . The scintillator emits light in response to the incidence of the X-rays and photoelectrically converts them to acquire electrical information. This information is subjected to digital conversion and then to image processing using an image processor  6070  as signal processing means, whereby it can be observed on a display  6080  as display means in a control room. 
     Furthermore, the information can be transferred to a remote location by using transmission processing means such as a telephone line  6090  and can be displayed on a display  6081  as display means in a doctor room in another place or stored in recording means such as an optical disk, whereby a doctor in a remote location can diagnose the patient. 
     Still further, a film processor  6100  as the recording means can record the information into a film  6110  as a recording medium. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims priority from Japanese Patent Application No. 2004-177009 filed Jun. 15, 2004, which is hereby incorporated by reference herein.