JP2011035215A - Radiation image photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image photographing device that accurately reduces electric noise of bias voltage transmitted to a signal line side. <P>SOLUTION: The radiation image photographing device 1 includes a plurality of scanning lines 5 and signal lines 6 disposed so that those are crossed each other, a detection part P having a plurality of radiation detecting elements 7 disposed in a shape of a two-dimensional plane on each region r which is sectioned by the plurality of scanning lines 5 and signal lines 6, bias lines 9 and 10 which are connected to each radiation detecting element 7 and in which the bias voltage supplied from a bias power supply 14 is supplied to each radiation detecting element 7, and a flattened layer 80a laminated on an incidence surface side of the radiation of each radiation detecting element 7. In the radiation image photographing device, the flattened layer 80a extended at least to a crossing portion Q of the signal line 6 and each bias line 9, 10 is disposed between the signal line 6 and bias lines 9, 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiographic image capturing apparatus, and more particularly, to a radiographic image capturing apparatus configured such that a bias line and its connection intersect with a signal line.

  A so-called direct type radiographic imaging device that generates electric charges with a detection element according to the dose of irradiated X-rays, etc., reads it as an electrical signal and converts it into image data, and the irradiated radiation is visible with a scintillator or the like A so-called indirect type that converts charges to electromagnetic waves of other wavelengths, such as light, and then generates charges in photoelectric conversion elements such as photodiodes according to the energy of the converted and irradiated electromagnetic waves, reads them as electrical signals, and converts them into image data Various radiographic imaging apparatuses have been developed. In the present invention, the detection element in the direct type radiographic imaging apparatus and the photoelectric conversion element in the indirect type radiographic imaging apparatus are collectively referred to as a radiation detection element.

  This type of radiographic imaging apparatus is known as an FPD (Flat Panel Detector), and conventionally formed integrally with a support base (or a bucky apparatus) (see, for example, Patent Document 1). A portable radiographic imaging device in which an element or the like is housed in a housing has been developed and put into practical use (see, for example, Patent Documents 2 and 3).

  By the way, in a radiation detection element used in a radiographic imaging apparatus, upon receiving irradiation of radiation or irradiation of electromagnetic waves converted by a scintillator or the like, a charge generated inside thereof, that is, an electron-hole pair is converted into an image signal. Is done. At that time, if the electron-hole pairs generated in the radiation detection element are not separated, they recombine and disappear. Therefore, a reverse bias (also referred to as reverse bias) is applied to the radiation detection element so that electron-hole pairs are stored separately in a pair of electrodes of the radiation detection element. (For example, refer to Patent Document 4).

  In order to achieve this, one electrode of the radiation detection element is connected to a signal line via a switching means such as a TFT (Thin Film Transistor), and a bias line is connected to the other electrode, so that the bias line A bias voltage (reverse bias voltage) is applied from the bias power source via the, and a potential gradient is formed so that electron-hole pairs are separated inside the radiation detection element.

  That is, if the bias voltage is lower than the voltage applied to the signal line, electrons are separated and accumulated on one electrode side and holes are applied to the other electrode side, and the bias voltage is applied to the signal line. If the voltage is higher, holes are separated on one electrode side and electrons are separated and accumulated on the other electrode side. When reading out image data, electrons and holes accumulated on one electrode side are read out as an electric signal.

JP-A-9-73144 JP 2006-058124 A JP-A-6-342099 JP 2006-5077 A

  However, when the signal line and the bias line intersect each other as in the radiographic image capturing apparatus described in Patent Document 4 (see FIG. 1), the electrical noise of the bias voltage applied to the bias line is insulated. The electric voltage of the bias voltage is transferred to the electric signal that is transmitted to the signal line from the radiation detection element through the capacitor-like part formed at the intersection of the signal line and the bias line through the layer. There is a possibility that the influence of noise is superimposed and the noise of the electric signal increases.

  If the noise of the electric signal increases in this way, the granularity of the converted image data may deteriorate, and the image quality of the finally obtained radiographic image may deteriorate.

  In order to avoid such a problem, for example, it is possible to avoid the signal line and arrange the bias line and its connection so that the bias line does not cross the signal line. A bias line or a connection must be provided on the outer periphery of the sensor panel in which the radiation detection elements are arranged two-dimensionally (matrix), which may increase the size of the sensor panel. However, there is a case where such a configuration cannot be adopted within an allowable range of dimensions required for the sensor panel.

  Therefore, there is a case where the signal line and the bias line must be configured to cross each other. In such a case, the bias voltage transmitted to the signal line side through the crossing portion between the signal line and the bias line may be reduced. A structure that reduces electrical noise as much as possible is required.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a radiographic imaging apparatus capable of accurately reducing electrical noise of a bias voltage transmitted to a signal line side.

In order to solve the above-described problem, the radiographic imaging device of the present invention includes:
A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other; a plurality of radiation detecting elements arranged in a two-dimensional manner in each region partitioned by the plurality of scanning lines and the plurality of signal lines; A detector comprising:
A bias line connected to each radiation detection element and supplying a bias voltage supplied from a bias power source to each radiation detection element;
A planarization layer laminated on the radiation incident side of each of the radiation detection elements;
With
The planarization layer is extended to at least an intersection of the signal line and the bias line, and is disposed so as to be interposed between the signal line and the bias line.

  According to the radiographic imaging apparatus of the system as in the present invention, the planarization layer laminated on the radiation incident surface side of each radiation detection element is extended to at least the intersection of each signal line and the bias line. The signal line and the bias line are arranged so as to be interposed, and the distance between each signal line and the bias line is increased, so that the signal line side passes through the intersection of each signal line and the bias line. The generated electrical noise can be greatly reduced.

  Further, since the electrical noise is remarkably reduced as described above, even if the electrical noise is superimposed on the electrical signal read out from each radiation detection element via the signal line, the influence is reduced and occurs in the image data. Noise can be reduced. Therefore, the image quality of the finally obtained radiographic image can be further improved, for example, by improving the granularity of the image data.

It is a perspective view which shows the radiographic imaging apparatus which concerns on this embodiment. It is sectional drawing which follows the AA line in FIG. It is an enlarged view of a scintillator, and is a figure showing the state by which a scintillator is stuck on a glass substrate. It is a top view which shows the structural example of the board | substrate of a radiographic imaging apparatus. It is a top view which shows the structural example of the board | substrate of a radiographic imaging apparatus. It is a top view which shows the structural example of the board | substrate of a radiographic imaging apparatus. It is an enlarged view which shows the structure of the radiation detection element, TFT, etc. which were formed on the board | substrate. It is sectional drawing which follows the XX line in FIG. FIG. 5 is a cross-sectional view taken along an extension direction of a connection at an intersection between a signal line and a connection of a bias line shown in FIG. FIG. 10 is a cross-sectional view taken along the signal line extending direction at the intersection of FIG. 9. It is a side view explaining the board | substrate with which COF, a PCB board | substrate, etc. were attached. It is a block diagram showing a part of equivalent circuit of a radiographic imaging device. It is sectional drawing in alignment with the extension direction of a signal wire | line in the cross | intersection part of the signal wire | line and the connection of a bias line in the conventional radiographic imaging apparatus.

  Embodiments of a radiographic image capturing apparatus according to the present invention will be described below with reference to the drawings.

  In the following description, the radiographic imaging device is a so-called indirect radiographic imaging device that includes a scintillator or the like and converts the irradiated radiation into electromagnetic waves of other wavelengths such as visible light to obtain an electrical signal. As will be described, the present invention can also be applied to a direct radiographic imaging apparatus. Although the case where the radiographic image capturing apparatus is portable will be described, the present invention is also applicable to a radiographic image capturing apparatus formed integrally with a support base or the like.

  FIG. 1 is an external perspective view of the radiographic image capturing apparatus according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line AA in FIG. As shown in FIGS. 1 and 2, the radiation image capturing apparatus 1 according to the present embodiment is configured by housing a scintillator 3, a substrate 4, and the like in a housing 2.

  The housing 2 is formed of a material such as a carbon plate or plastic that at least the radiation incident surface R transmits radiation. 1 and 2 show a case in which the housing 2 is a so-called lunch box type formed by the frame plate 2A and the back plate 2B. However, the housing 2 is integrally formed in a rectangular tube shape. It is also possible to use a so-called monocoque type.

  As shown in FIG. 1, the side surface of the housing 2 is opened and closed to replace a power switch 36, an indicator 37 made up of LEDs, etc., and a battery 41 (not shown) (see FIG. 12 described later). A possible lid member 38 and the like are arranged. In the present embodiment, an antenna device 39 that is a communication unit for wirelessly communicating with an external device (not shown) is embedded in the side surface of the lid member 38.

  As shown in FIG. 2, a base 31 is disposed inside the housing 2 via a thin lead plate (not shown) on the lower side of the substrate 4. The base 31 has a readout IC 16 ( A PCB substrate 33 on which electronic parts 32 such as FIG. In the present embodiment, a glass substrate 35 for protecting the substrate 4 and the radiation incident surface R of the scintillator 3 is disposed. In the present embodiment, a sensor panel is constituted by the substrate 4, the scintillator 3, the radiation detection element 7 described later, and the like.

  In the present embodiment, as shown in the enlarged view of FIG. 3, the scintillator 3 is formed on a support film 3b formed of various polymer materials such as a cellulose acetate film, a polyester film, and a polyethylene terephthalate film. The phosphor 3a is grown by the phase growth method, and is made of a columnar crystal of the phosphor 3a. As the vapor phase growth method, an evaporation method, a sputtering method, or the like is preferably used.

  The phosphor 3a of the scintillator 3 is, for example, one that converts and outputs an electromagnetic wave having a wavelength of 300 to 800 nm, that is, an electromagnetic wave centered on visible light when receiving radiation.

  In the present embodiment, the scintillator 3 in which the phosphor 3a is formed as a columnar crystal in this way is arranged so that the acute tip Pa of the columnar crystal of the phosphor 3a faces the lower side, that is, the substrate 4 side described above. The scintillator 3 is fixed to the glass substrate 35 by attaching the support film 3b to the glass substrate 35.

  In the present embodiment, as described above, the scintillator 3 is made of a columnar crystal of the phosphor 3a. In addition to this, for example, a paste containing the phosphor is applied to the glass substrate 35 or the like. For example, the scintillator 3 can be formed in layers, and the configuration and properties of the scintillator 3 are not particularly limited.

  In the present embodiment, the substrate 4 is formed of a glass substrate. As shown in FIG. 4, a plurality of scanning lines 5 and a plurality of signal lines are provided on a surface 4 a of the substrate 4 facing the scintillator 3. 6 are arranged so as to cross each other. In each small region r defined by the plurality of scanning lines 5 and the plurality of signal lines 6 on the surface 4 a of the substrate 4, radiation detection elements 7 are respectively provided.

  Thus, the entire region r in which a plurality of radiation detection elements 7 arranged in a two-dimensional manner are provided in each small region r partitioned by the scanning line 5 and the signal line 6, that is, shown by a one-dot chain line in FIG. The region is a detection unit P.

  In the present embodiment, each signal line 6 is divided at a midway portion such as an intermediate point in the extending direction. As will be described later, a readout circuit 17 is connected to an end of each signal line 6 on the opposite side of the halfway portion, and in this embodiment, each radiation detection element 7 is connected. From FIG. 4, it is set as the structure for what is called a both-sides reading which reads an electrical signal in the upward direction and the downward direction in FIG.

  As described above, when the electric signal from each radiation detection element 7 is configured to be read in the upward and downward directions in FIG. 4, the reading process of the electric signal (image data) from each radiation detection element 7 is performed as follows. It is possible to perform at higher speed than in the case of single-side reading. Hereinafter, in the present embodiment, a case will be described in which the sensor panel has the configuration for reading both sides shown in FIG.

  However, if the sensor panel is configured such that each signal line 6 and a connection line 10 of a bias line 9 described later intersect as in the present embodiment, for example, as shown in FIG. 5 is continuously provided without being divided in the middle, and is connected to the upper portion in FIG. 5 by a readout circuit 17 connected via an input / output terminal 11 provided at one end of each signal line 6. The present invention can also be applied to a case of a so-called one-side reading configuration in which an electric signal is read in the direction.

  Further, in the present embodiment, as shown in FIG. 4, the bias line 9 is also divided at an intermediate portion, and is configured to be bound to the connection 10 at the upper and lower portions in FIG. Even in the same double-sided readout configuration, as shown in FIG. 6, the bias line 9 may be bound to the connection 10 at the upper or lower portion in FIG. In this case, the present invention can be applied.

  In the present embodiment, a photodiode is used as the radiation detection element 7, but other than this, for example, a phototransistor or the like can also be used. Each radiation detection element 7 is connected to the source electrode 8s of the TFT 8 serving as a switch means, as shown in the enlarged views of FIG. 4 and FIG. The drain electrode 8 d of the TFT 8 is connected to the signal line 6.

  The TFT 8 is turned on when a turn-on voltage is applied to the connected scanning line 5 by the scanning drive means 15 described later and applied to the gate electrode 8g, and is generated and accumulated in the radiation detection element 7. The charged electric charge is discharged to the signal line 6. Further, the TFT 8 is turned off when the off voltage is applied to the connected scanning line 5 and the off voltage is applied to the gate electrode 8g, and the emission of the charge from the radiation detecting element 7 to the signal line 6 is stopped. The charges generated in the radiation detection element 7 are held and accumulated in the radiation detection element 7.

  Here, the structure of the radiation detection element 7 and the TFT 8 in this embodiment will be briefly described with reference to a cross-sectional view shown in FIG. FIG. 8 is a sectional view taken along line XX in FIG.

A gate electrode 8g of a TFT 8 made of Al, Cr or the like is formed on the surface 4a of the substrate 4 so as to be integrally laminated with the scanning line 5, and silicon nitride (laminated on the gate electrode 8g and the surface 4a). The first electrode 74 of the radiation detecting element 7 is connected to the upper portion of the gate electrode 8g on the gate insulating layer 81 made of SiN _x ) or the like via the semiconductor layer 82 made of hydrogenated amorphous silicon (a-Si) or the like. The formed source electrode 8s and the drain electrode 8d formed integrally with the signal line 6 are laminated.

The source electrode 8s and the drain electrode 8d are divided by a first passivation layer 83 made of silicon nitride (SiN _x ) or the like, and the first passivation layer 83 covers both electrodes 8s and 8d from above. In addition, ohmic contact layers 84a and 84b formed in an n-type by doping hydrogenated amorphous silicon with a group VI element are stacked between the semiconductor layer 82 and the source electrode 8s and the drain electrode 8d, respectively. The TFT 8 is formed as described above.

  In the radiation detecting element 7, an auxiliary electrode 72 is formed by laminating Al, Cr, or the like on the insulating layer 71 formed integrally with the gate insulating layer 81 on the surface 4 a of the substrate 4. A first electrode 74 made of Al, Cr, Mo or the like is laminated on the auxiliary electrode 72 with an insulating layer 73 formed integrally with the first passivation layer 83 interposed therebetween. The first electrode 74 is connected to the source electrode 8 s of the TFT 8 through a hole Ha formed in the first passivation layer 83.

  On the first electrode 74, an n layer 75 formed in an n-type by doping a hydrogenated amorphous silicon with a group VI element, an i layer 76 which is a conversion layer formed of hydrogenated amorphous silicon, and a hydrogenated amorphous A p layer 77 formed by doping a group III element into silicon and forming a p-type layer is formed by laminating sequentially from below.

  When radiation enters from the radiation incident surface R of the housing 2 of the radiographic imaging apparatus 1 and is converted into an electromagnetic wave such as visible light by the scintillator 3, and the converted electromagnetic wave is irradiated from above in the figure, the electromagnetic wave is detected by radiation. The electron hole pair is generated in the i layer 76 by reaching the i layer 76 of the element 7. In this way, the radiation detection element 7 converts the electromagnetic waves irradiated from the scintillator 3 into electric charges (electron hole pairs).

  On the p layer 77, a second electrode 78 made of a transparent electrode such as ITO is laminated and formed so that the irradiated electromagnetic wave reaches the i layer 76 and the like. In the present embodiment, the radiation detection element 7 is formed as described above. The order of stacking the p layer 77, the i layer 76, and the n layer 75 may be reversed. Further, in the present embodiment, a case where a so-called pin-type radiation detection element formed by sequentially stacking the p layer 77, the i layer 76, and the n layer 75 as described above is used as the radiation detection element 7. However, it is not limited to this.

The second electrode 78 of the radiation detection element 7, the first electrode 74 extended to the TFT 8 side, the first passivation layer 83 of the TFT 8, that is, the upper surface portions of the radiation detection element 7 and the TFT 8 are silicon nitride (from above) A second passivation layer 79 made of SiN _x ) or the like is covered.

  Further, a flattening layer 80a for flattening the unevenness of the radiation detection element 7 and the TFT 8 is provided on the upper surface side of the radiation detection element 7 and the TFT 8, that is, the surface side on which the radiation or the electromagnetic wave converted by the scintillator 3 is incident. It is formed by stacking.

  In the present embodiment, the planarization layer 80a and the second planarization layer 80b are made of acrylic resin so that the electromagnetic waves converted by the scintillator 3 arranged on the upper surface side of the planarization layer 80a reach each radiation detection element 7. It is formed with transparent resin. However, for example, when the radiographic image capturing apparatus 1 is the above-described direct type apparatus and the radiation detection element 7 is a detection element that directly receives radiation irradiated, the planarization layer 80a and the second planarization layer 80b. As long as it does not block radiation, it does not have to be transparent.

  A hole Hb is provided in the flattened layer 80a portion above the second electrode 78 of the radiation detection element 7, and the second electrode 78 of the radiation detection element 7 is made of a conductive material 9a such as a metal embedded in the hole Hb. To the bias line 9 disposed on the upper surface of the planarizing layer 80a. The bias line 9 supplies a bias voltage supplied from a bias power source (see FIG. 12) described later to each radiation detection element 7.

  Further, on the upper surface side of the planarizing layer 80a and the bias line 9, a second planarizing layer 80b for planarizing unevenness on the upper surface of the planarizing layer 80a due to the bias line 9 and the like is formed by being laminated. The top surface of the second planarization layer 80b is arranged so that the tip Pa of the columnar crystal phosphor 3a (see FIG. 3) of the scintillator 3 is in contact with the scintillator 3, and the scintillator 3 The support layer 80b is supported from below.

  Since the second planarization layer 80b supports the scintillator 3 in this manner, the second planarization layer 80b is formed only above the detection unit P indicated by a one-dot chain line in FIGS. 4, 5, and 6.

  As shown in FIG. 4 and the like, in this embodiment, each bias line 9 is arranged in parallel to the signal line 6. Further, each bias line 9 is bound to the connection 10 at a position outside the detection portion P of the substrate 4.

  The planarizing layer 80a is formed so as to extend at least to the intersection Q between the signal lines 6 outside the detection portion P and the connection lines 10 of the bias lines 9, as shown in FIGS. As shown, the planarization layer 80 a is disposed so as to be interposed between the signal line 6 and the connection line 10 of the bias line 9.

  9 is a cross-sectional view along the extending direction of the connection 10 at the intersection Q between the signal line 6 and the connection 10 of the bias line 9 shown in FIG. 4 and the like, and FIG. It is sectional drawing in alignment with the extension direction of the signal wire | line 6 in Q. Further, as described above, the second planarization layer 80b is formed only above the detection unit P, and therefore does not exist on FIG. 9 which is a cross-sectional view of the outer portion of the detection unit P.

  In the present embodiment, as shown in FIG. 10, the planarization layer 80 a is formed so as to extend to the outside of the intersection Q between each signal line 6 and the connection line 10 of the bias line 9. Then, a hole Hc is provided in the upper flattening layer 80a near the end of the signal line 6, and the signal line 6 is flattened through a conductive material 6a such as a metal embedded in the hole Hc. It is connected to an input / output terminal (also referred to as a pad) 11 disposed on the upper surface of the layer 80a.

  As shown in FIG. 4 and the like, the input / output terminal 11 is provided in the same manner not only at the end of each signal line 6 but also at the end of each scanning line 5 or the end of the connection 10 of the bias line 9. Each input / output terminal 11 is provided near the edge of the substrate 4. As shown in FIG. 11, each input / output terminal 11 has a COF (Chip On Film) 12 in which a chip such as a gate IC 12a constituting a gate driver 15b of a scanning drive means 15 described later is incorporated. They are connected via an anisotropic conductive adhesive material 13 such as a film (Anisotropic Conductive Film) or an anisotropic conductive paste (Anisotropic Conductive Paste).

  The COF 12 is routed to the back surface 4b side of the substrate 4 and connected to the PCB substrate 33 described above on the back surface 4b side. In this way, the sensor panel of the radiation image capturing apparatus 1 is formed. In FIG. 11, illustration of the electronic component 32 and the like is omitted. Further, the columnar crystals of the phosphor 3a of the scintillator 3 are omitted.

  Here, the circuit configuration of the radiation image capturing apparatus 1 will be described. FIG. 12 is a block diagram showing a part of an equivalent circuit of the radiation image capturing apparatus 1 according to this embodiment. When the sensor panel is configured for reading on both sides as shown in FIGS. 4 and 6, the equivalent circuit shown in FIG. 12 represents an equivalent circuit on one side thereof.

  As described above, each radiation detection element 7 of the detection unit P of the substrate 4 has the bias line 9 connected to the second electrode 78, and each bias line 9 is bound to the connection 10 to the bias power supply 14. It is connected. The bias power supply 14 applies a bias voltage to the second electrode 78 of each radiation detection element 7 via the connection 10 and each bias line 9. The bias power source 14 is connected to a control unit 22 described later, and the control unit 22 controls a bias voltage applied to each radiation detection element 7 from the bias power source 14.

  In the present embodiment, the current detection means 43 for detecting the amount of current flowing through the connection 10 (bias line 9) is provided in the connection 10 of the bias line 9, and the increase / decrease in the current flowing through the connection 10 is detected. The start and end of radiation irradiation can be detected. In addition, when the bias line 9 is bound to a plurality of connections 10 as shown in FIG. 4, the current detection means 43 may be provided for each connection 10. Only one may be provided in the bundled connection.

  As shown in FIG. 12, in this embodiment, the bias line 9 is connected to the p-layer 77 side (see FIG. 8) of the radiation detection element 7 via the second electrode 78, as shown in FIG. From the power source 14, a voltage equal to or lower than the voltage applied to the first electrode 74 side of the radiation detection element 7 as a bias voltage is applied to the second electrode 78 of the radiation detection element 7 via the bias line 9. It is like that.

  The first electrode 74 of each radiation detection element 7 is connected to the source electrode 8s (denoted as S in FIG. 12) of the TFT 8, and the gate electrode 8g of each TFT 8 (denoted as G in FIG. 12). Are connected to the lines L1 to Lx of the scanning line 5, respectively. Further, the drain electrode 8d (denoted as D in FIG. 12) of each TFT 8 is connected to each signal line 6.

  In this embodiment, the scanning drive unit 15 includes a power supply circuit 15a and a gate driver 15b. The power supply circuit 15a applies an on-voltage and an off-voltage applied to the lines L1 to Lx of the scanning line 5 to the gate driver 15b. It comes to supply. In this embodiment, the gate driver 15b is formed by arranging a plurality of the gate ICs 12a described above. The gate driver 15b controls the on / off of each TFT 8 by switching the voltage applied to each of the lines L1 to Lx of the scanning line 5 between an on voltage and an off voltage.

  Each signal line 6 is connected to each readout circuit 17 formed in the readout IC 16. Note that a predetermined number of readout circuits 17 are provided in the readout IC 16, and by providing a plurality of readout ICs 16, readout circuits 17 corresponding to the number of signal lines 6 are provided.

  The readout circuit 17 includes an amplifier circuit 18, a correlated double sampling circuit 19, an analog multiplexer 21, and an A / D converter 20. In FIG. 12, the correlated double sampling circuit 19 is denoted as CDS.

  The readout circuit 17 reads out the electric charge (one electric charge of the electron-hole pairs described above) generated and accumulated in each radiation detection element 7 by radiation irradiation after radiographic imaging as an electric signal, and an amplification circuit Charge voltage conversion is performed at 18 and sampling processing is performed by the correlated double sampling circuit 19 to obtain image data.

  Then, the image data of each radiation detection element 7 output from the correlated double sampling circuit 19 is transmitted to the analog multiplexer 21 and sequentially transmitted from the analog multiplexer 21 to the A / D converter 20. Then, the A / D converter 20 sequentially converts the image data into digital values, which are output to the storage means 40 and sequentially stored.

  As shown in FIGS. 4 and 6, each signal line 6 is divided at an intermediate portion in the extending direction, and electrical signals are read from each radiation detection element 7 in the upward and downward directions in each figure. In other words, the so-called double-sided readout configuration is such that an electrical signal is simultaneously read from the radiation detection element 7 connected to the upper side of the divided portion of each signal line 6 and the radiation detection element 7 connected to the lower side. It becomes possible.

  For this reason, it is possible to perform the reading process of the electric signal from each radiation detection element 7 in substantially half the time of the one-side reading, and the electric signal (image data) reading process is faster than the one-side reading. Can be performed.

  The control means 22 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface connected to the bus, an FPGA (Field Programmable Gate Array), or the like (not shown). It is configured. It may be configured by a dedicated control circuit. And the control means 22 controls operation | movement etc. of each member of the radiographic imaging apparatus 1. The control means 22 is connected to a storage means 40 composed of a DRAM (Dynamic RAM) or the like.

  In the present embodiment, the above-described antenna device 39 is connected to the control unit 22, and each member such as the detection unit P, the scanning drive unit 15, the readout circuit 17, the storage unit 40, the bias power supply 14, and the like. A battery 41 for supplying electric power is connected. In addition, a connection terminal 42 for charging the battery 41 by supplying power from the external device to the battery 41 is attached to the battery 41.

  Next, the operation of the radiation image capturing apparatus 1 according to this embodiment will be described.

  In the sensor panel of the conventional radiographic imaging apparatus, as shown in FIG. 13, in each signal line 6 extending outward from the detection portion P, the upper surface side of each signal line 6 is the insulating layer of the radiation detection element 7. 73 (see FIG. 8) and a first passivation layer 83 formed integrally with the second passivation layer 79 laminated on the upper surface side thereof, and the upper surface side of the first and second passivation layers 83 and 79. Generally, the connection 10 of the bias line 9 is provided.

  For this reason, the interval between the connection 10 of the bias line 9 and each signal line 6 is narrowed, and when the connection 10 of the bias line 9 and the signal line 6 are regarded as two electrodes, they are formed at the intersection Q between them. The capacitance of the capacitor-like portion (that is, parasitic capacitance) increases.

That is, the capacitance C of a normal capacitor having two electrodes (so-called parallel plate capacitor) is as follows. When the electrode area is S, the distance between the electrodes is d, and the dielectric constant of the dielectric interposed between the electrodes is ε,
C = ε · S / d (1)
It is well known that it is calculated by

  In the case of the sensor panel of the conventional radiographic imaging apparatus shown in FIG. 13, the inter-electrode distance d of the capacitor-like portion when the connection 10 of the bias line 9 and the signal line 6 are regarded as two electrodes. Since the distance between the connection 10 of the bias line 9 corresponding to the signal line 6 and the signal line 6 is short, the parasitic capacitance C of the capacitor-like portion is increased.

Further, the bias voltage noise ΔV generated in the bias power supply 14 and the current detection means 43 (see FIG. 12) and transmitted to the connection 10 of the bias line 9 is transmitted to the signal line 6 side through this capacitor-shaped portion. As described above, when the parasitic capacitance C of this portion increases,
ΔQ = C · ΔV (2)
In accordance with the relationship, electrical noise ΔQ is generated on the signal line 6 side.

  When the electrical signal is read out from each radiation detection element 7 via the signal line 6 by the readout circuit 17 as described above, this electrical noise ΔQ is superimposed on the electrical signal at the portion of the signal line 6, and the electrical signal is Noise in image data obtained by charge-voltage conversion or the like increases (that is, the S / N ratio decreases). Therefore, the image quality of the finally obtained radiographic image deteriorates, for example, due to the deterioration of the granularity of the image data.

  On the other hand, in the radiographic image capturing apparatus 1 according to the present embodiment, as shown in FIG. 10, at least each signal line includes a planarization layer 80 a for planarizing unevenness on the upper surface side of the radiation detection element 7 and the TFT 8. 6 and the connection line 10 of the bias line 9 are extended to the intersection Q, and are arranged so as to be interposed between the signal lines 6 and the connection line 10 of the bias line 9.

  Therefore, not only the conventional first and second passivation layers 83 and 79 but also the planarization layer 80a are interposed between each signal line 6 and the connection 10 of the bias line 9, and the connection of the bias line 9 is performed. The distance between the signal line 6 and the signal line 6 can be made sufficiently large. Therefore, when the connection 10 of the bias line 9 and the signal line 6 are regarded as two electrodes, the inter-electrode distance d of the capacitor-like portion increases, and as can be seen from the above equation (1), The parasitic capacitance C is much smaller than in the conventional case.

  And since the parasitic capacitance C of the capacitor-like part becomes very small in this way, as can be seen from the above equation (2), it is caused by the bias voltage noise ΔV generated in the bias power supply 14 and the current detection means 43. The electrical noise ΔQ generated on the signal line 6 side is very small.

  As described above, in the radiographic imaging apparatus 1 according to the present embodiment, the planarization layer 80a laminated on the radiation incident surface side of each radiation detection element 7 (that is, the upper surface side of each radiation detection element 7 in FIG. 8). Is extended to at least the intersection Q between the signal lines 6 and the connection 10 of the bias line 9 and arranged so as to be interposed between the signal lines 6 and the connection 10 of the bias lines 9. The electrical noise ΔQ generated on the signal line 6 side through the intersection portion Q between each signal line 6 and the connection line 10 of the bias line 9 is remarkably reduced by increasing the distance between the connection line 6 and the connection line 10 of the bias line 9. It becomes possible.

  In addition, since the electrical noise ΔQ is remarkably reduced in this way, even if the electrical noise ΔQ is superimposed on the electrical signal read out from each radiation detection element 7 via the signal line 6, the influence is reduced. It is possible to reduce noise generated in the image data. Therefore, the image quality of the finally obtained radiographic image can be further improved, for example, by improving the granularity of the image data.

  In FIG. 9 and FIG. 10 and the like, it is described that the connection 10 of the bias line 9 is arranged on the upper surface side of the flattening layer 80a so as to be exposed. It is comprised so that it may be coat | covered with an insulating layer etc. Further, in FIG. 10 and the like, it is described that the planarization layer 80a is provided up to the periphery of the sensor panel. However, as described above, the planarization layer 80a is connected to at least the signal lines 6 and the bias lines 9. As long as it extends to the intersection Q with the signal line 10 and is interposed between the signal line 6 and the connection line 10 of the bias line 9, the configuration of the other part is determined as appropriate. The

DESCRIPTION OF SYMBOLS 1 Radiographic imaging apparatus 3 Scintillator 5 Scan line 6 Signal line 7 Radiation detection element 9 Bias line 10 Bias line connection (bias line)
14 Bias power supply 17 Read circuit 80a Flattening layer P Detection part Q Intersection r region

Claims (3)

A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other; a plurality of radiation detecting elements arranged in a two-dimensional manner in each region partitioned by the plurality of scanning lines and the plurality of signal lines; A detector comprising:
A bias line connected to each radiation detection element and supplying a bias voltage supplied from a bias power source to each radiation detection element;
A planarization layer laminated on the radiation incident side of each of the radiation detection elements;
With
The planarizing layer extends to at least an intersection between the signal line and the bias line, and is disposed so as to be interposed between the signal line and the bias line. Shooting device. A scintillator that converts the irradiated radiation into electromagnetic waves,
The radiographic image capturing apparatus according to claim 1, wherein the flattening layer is disposed between each radiation detection element and the scintillator and is formed of a transparent resin.   Each signal line is divided at a midway portion in the extending direction, and a readout circuit that reads an electrical signal from each radiation detection element at each end on the opposite side of the midway portion of each signal line The radiographic imaging apparatus according to claim 1, wherein each of the radiographic imaging apparatuses is provided.

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