Radiation imaging device and radiation imaging system

Abstract

To provide a technology advantageous for detecting presence or absence of irradiation with radiation with higher accuracy.SOLUTION: A radiation imaging device includes a plurality of pixel groups and a plurality of bias sources that have one-to-one correspondence, a drive circuit, and a detection unit. Each pixel group includes a pixel including a conversion element converting radiation into electric charges and a switch element. Each bias source supplies a bias potential to the conversion element of the pixel via a bias line. The drive circuit controls the switch element of each pixel. The detection unit acquires a first signal value and a second signal value so that sampling timings are overlapped with each other at least partially, the first signal value representing a current flowing in a first bias line connected with a first pixel group including the pixel whose switch element is turned on by the drive circuit, the second signal value representing a current flowing in a second bias line connected with a second pixel group whose switch element is in an off state. Presence or absence of irradiation with radiation is determined on the basis of the first and second signal values. Time constants of the first and second bias lines are substantially the same.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radiation imaging apparatus and a radiation imaging system. [Background technology]

[0002] Radiation imaging devices using flat panel detectors (FPDs) made of semiconductor materials are widely used in medical image diagnosis and non-destructive testing. Patent Document 1 discloses a radiation imaging device that detects the presence or absence of radiation irradiation by utilizing the fact that, when radiation is irradiated to the radiation imaging device, a current (bias current) flows through a bias line that supplies a bias potential to a pixel, in order to synchronize with a radiation generator. Furthermore, the radiation imaging device of Patent Document 1 acquires, from the same pixel, the bias current when the switch element is in a conductive state as an effective value and the bias current when the switch element is in a non-conductive state as a noise value, and detects the presence or absence of radiation irradiation based on the effective value and the noise value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-168203 Summary of the Invention [Problem to be solved by the invention]

[0004] Current may flow in the bias wire due to reasons other than radiation irradiation, such as when the radiation imaging device is subjected to an impact. If the current flowing due to noise is large, there is a possibility that radiation irradiation may be erroneously detected even when radiation irradiation is not occurring. Patent Document 1 discloses that the influence of noise can be reduced by detecting the presence or absence of radiation irradiation based on an effective value and a noise value. However, there is a possibility that this method cannot deal with noise with high frequency components that may occur when the radiation imaging device is subjected to an impact.

[0005] An object of the present invention is to provide a technique that is advantageous for detecting the presence or absence of radiation irradiation with higher accuracy. [Means for solving the problem]

[0006] In view of the above-described problems, a radiation imaging apparatus according to an embodiment of the present invention is a radiation imaging apparatus including a plurality of pixel groups, each of which is arranged so that one pixel group corresponds to one bias source, a plurality of bias sources, a drive circuit, and a detection unit, wherein each of the plurality of pixel groups is configured by a pixel including a conversion element that converts radiation into an electric charge and a switch element that connects the conversion element to a signal line, and each of the plurality of bias sources supplies a bias potential to the conversion element of the pixel via at least one bias line among a plurality of bias lines that are electrically independent for each bias source, and the drive circuit controls the switch element of the pixel, and The detection unit acquires a first signal value representing a current flowing through a first bias line among the plurality of bias lines connected to a first pixel group among the plurality of pixel groups, the first pixel group including the pixel whose switch element has been turned on by the drive circuit, and a second signal value representing a current flowing through a second bias line among the plurality of bias lines connected to a second pixel group among the plurality of pixel groups whose switch element is in an off state, so that the sampling timings overlap at least partially, and determines whether radiation is being irradiated based on the first signal value and the second signal value, and is characterized in that the time constant of the first bias line and the time constant of the second bias line are approximately the same. [Effects of the Invention]

[0007] The above means provides a technique that is advantageous for detecting the presence or absence of radiation irradiation with higher accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of the configuration of a radiation imaging system using a radiation imaging apparatus according to the present invention. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of the radiation imaging apparatus of FIG. 1. [Figure 3] FIG. 2 is a flowchart illustrating the operation of the radiation imaging apparatus of FIG. [Figure 4] FIG. 2 is a schematic diagram showing the drive timing of the radiation imaging apparatus of FIG. 1. [Figure 5] 2 is a schematic diagram showing the driving timing for detecting radiation in the radiation imaging device of FIG. 1; [Figure 6] 2 is a detailed diagram showing the driving timing for detecting radiation in the radiation imaging device of FIG. 1. [Figure 7] FIG. 2 is a schematic diagram showing the drive timing of the radiation imaging apparatus of FIG. 1. [Figure 8] FIG. 2 is a schematic diagram showing an example of the configuration of the radiation imaging apparatus of FIG. [Figure 9] FIG. 2 is a schematic diagram showing a comparative example of the configuration of the radiation imaging apparatus of FIG. 1. [Figure 10] 9 is a schematic diagram showing an example of the configuration of a bias line of the radiation imaging apparatus of FIG. 8. [Figure 11] 11 is a schematic cross-sectional view illustrating an example of the layer configuration of the bias line in FIG. 10. [Figure 12] FIG. 3 is a diagram showing a modified example of the configuration of the bias source in FIG. 2. [Figure 13] FIG. 3 is a diagram showing a modified example of the configuration of the radiation imaging apparatus of FIG. [Figure 14] 14 is a schematic diagram showing the driving timing for detecting radiation of the radiation imaging device of FIG. 13. [Figure 15] FIG. 7 is a diagram showing a modified example of the detailed diagram of the drive timing in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the scope of the claimed invention. Although the embodiments describe multiple features, not all of these features are necessarily essential to the invention, and multiple features may be combined in any desired manner. Furthermore, in the accompanying drawings, the same or similar components are denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, radiation in the present invention may include beams of particles (including photons) emitted by radioactive decay, such as α-rays, β-rays, and γ-rays, as well as beams of similar or higher energy, such as X-rays, particle beams, and cosmic rays.

[0010] A radiation imaging apparatus according to this embodiment will be described with reference to Figures 1 to 10. Figure 1 is a diagram showing an example of the configuration of a radiation imaging system SYS using a radiation imaging apparatus 100 according to this embodiment. The radiation imaging system SYS according to this embodiment includes the radiation imaging apparatus 100, a control computer 120, a radiation generation apparatus 130, and a radiation control apparatus 140.

[0011] The radiation generating device 130 irradiates the radiation imaging device 100 with radiation under the control of the radiation control device 140. The control computer 120 can control the entire radiation imaging system SYS. The control computer 120 also acquires a radiation image generated by radiation irradiated from the radiation generating device 130 to the radiation imaging device 100 via the subject.

[0012] The radiation imaging device 100 includes a detection unit 110 including a pixel unit 101, a readout circuit 102, a reference power supply 103, and a bias power supply unit 104, a power supply unit 105, a detection unit 106, and a control unit 107. The pixel unit 101 has a plurality of pixels arranged in a two-dimensional array for detecting radiation. The readout circuit 102 reads charge information from the pixel unit 101. The reference power supply 103 supplies a reference voltage to the readout circuit 102. The bias power supply unit 104 supplies a bias potential to the conversion elements of the pixels arranged in the pixel unit 101. The power supply unit 105 supplies power to each power supply including the reference power supply 103 and the bias power supply unit 104. The detection unit 106 obtains current information from the bias power supply unit 104. More specifically, the detection unit 106 obtains, from the bias power supply unit 104, information about the current flowing through a bias line through which the bias power supply unit 104 supplies a bias potential to each pixel of the pixel unit 101. The detection unit 106 calculates information on the current output from the bias power supply and outputs radiation information including time fluctuations in the intensity of radiation incident on the pixel unit 101. The detection unit 106 can be a digital signal processing circuit such as an FPGA, DSP, or processor. Alternatively, the detection unit 106 may be configured using analog circuits such as a sample-and-hold circuit or an operational amplifier. While the detection unit 106 is provided in the radiation imaging apparatus 100 in the configuration shown in FIG. 1 , the control computer 120 may also have the function of the detection unit 106. In this case, the radiation imaging apparatus 100 shown in FIG. 1 and the portion of the control computer 120 that functions as the detection unit 106 constitute the "radiation imaging apparatus" of this embodiment. The detection unit 110 will be described in detail in the description of FIG. 2. The control unit 107 controls the entire radiation imaging apparatus 100, including driving the radiation imaging apparatus 100. The control unit 107 controls the detection unit 110 using a driving method transmitted from the control computer 120 in accordance with user settings, etc. Furthermore, the radiation information output by the detection unit 106 may be used to change the driving method of the detection unit 110.

[0013] Fig. 2 is an equivalent circuit diagram showing an example of the configuration of the detection unit 110 of the radiation imaging device 100. For ease of explanation, Fig. 2 shows the pixel unit 101 having 6 rows x 6 columns of pixels PIX. However, the pixel unit 101 of an actual radiation imaging device 100 may have more pixels; for example, a 17-inch radiation imaging device 100 may have approximately 2800 rows x approximately 2800 columns of pixels PIX.

[0014] The pixel unit 101 is a two-dimensional detector having a plurality of pixels PIX arranged in a matrix. Each pixel PIX includes a conversion element S (S11 to S66) that converts radiation into electric charges and a switch element T (T11 to T66) that connects the conversion element S to a signal line Sig and outputs an electric signal corresponding to the electric charge. In this embodiment, the conversion element S is an indirect conversion element including a photoelectric conversion element and a wavelength converter that converts radiation into light in a wavelength band that can be sensed by the photoelectric conversion element on the radiation incident side of the photoelectric conversion element. The photoelectric conversion element that converts light into electric charges may be an MIS photodiode arranged on an insulating substrate such as a glass substrate and made primarily of a semiconductor material such as amorphous silicon. In addition to an MIS photodiode, a PIN photodiode, for example, may also be used as the photoelectric conversion element. The conversion element S may also be a direct conversion element that directly converts radiation into electric charges. The switch element T may be a transistor having a control terminal and two main terminals. In this embodiment, the switch element T is a thin film transistor (TFT).

[0015] One electrode of the conversion element S is electrically connected to one of two main terminals of the switch element T, and the other electrode of the conversion element S is electrically connected to a bias source 203 of the bias power supply unit 104 via a bias line Bs. A plurality of switch elements T arranged in the row direction (horizontal direction in the drawing), for example, switch elements T11, T13, and T15, have their control terminals electrically connected in common to a drive line Vg1-1 in the first row, and a drive signal for controlling the conduction state of the switch elements T is applied from a drive circuit 214 via the drive line Vg. The drive circuit 214 controls the switch elements T of the pixels PIX via a plurality of drive lines Vg arranged in the row direction. A plurality of switch elements T arranged in the column direction (vertical direction in the drawing), for example, switch elements T11 to T61, have the other of their two main terminals electrically connected to a signal line Sig1 in the first column. Then, while the switch element T is in a conductive state, an electrical signal corresponding to the charge of the conversion element S is output via the signal line to the readout circuit 102. The signal lines Sig1 to Sig6 can transmit the electrical signals output from the multiple pixels PIX to the readout circuit 102 in parallel for each column.

[0016] The readout circuit 102 includes an amplifier circuit 206 for amplifying the electrical signals output in parallel from the pixel unit 101, corresponding to each signal line. The amplifier circuit 206 includes an integrating amplifier 205 for amplifying the output electrical signal, a variable amplifier 204 for amplifying the electrical signal output from the integrating amplifier 205, a sample-and-hold circuit 207 for sampling and holding the amplified electrical signal, and a buffer amplifier 209. The integrating amplifier 205 includes an operational amplifier for amplifying and outputting the electrical signal read from the pixel PIX, an integral capacitor, and a reset switch. The integrating amplifier 205 can change its amplification factor by changing the value of the integral capacitor. The electrical signal output from the pixel PIX is input to the inverting input terminal of the integrating amplifier 205, a reference potential Vref is input to the non-inverting input terminal from the reference power supply 103, and the amplified electrical signal is output from the output terminal. An integral capacitor is also disposed between the inverting input terminal and output terminal of the operational amplifier. A sample-and-hold circuit 207 is provided for each amplifier circuit 206 and is composed of a sampling switch and a sampling capacitor. The readout circuit 102 also includes a multiplexer 208 that sequentially outputs the electrical signals read out in parallel from the amplifier circuit 206 as a serial image signal. The image signal Vout, which is an analog electrical signal output from the buffer amplifier 209, is converted into digital image data by an A / D converter 210 and output to the control computer 120 shown in FIG.

[0017] The power supply unit 105 (omitted from FIG. 2 ) transforms power from a battery or external power source into various power supplies and supplies the power to the reference power supply 103, bias power supply unit 104, and other components of the amplifier circuit shown in FIG. 2 . The reference power supply 103 supplies a reference voltage Vref to the non-inverting input terminal of the operational amplifier. The bias source 203 of the bias power supply unit 104 supplies a common bias potential Vs to the other of the two electrodes of the conversion element S via a bias line Bs. The bias source 203 of the bias power supply unit 104 also outputs current information, including time fluctuations in the amount of current flowing through the bias line Bs, to the detection unit 106. In this embodiment, the bias source 203 includes a current-voltage conversion circuit 215 including an operational amplifier and a resistor as a circuit for outputting the current information, but this configuration is not limited thereto. For example, the bias source 203 may include a current-voltage conversion circuit using a shunt resistor. Moreover, the bias source 203 may further include an A / D conversion circuit that converts the output voltage of the current-voltage conversion circuit into a digital value, and may output current information as a digital value. Moreover, the bias source 203 may output to the detection unit 106 an appropriate physical quantity corresponding to the amount of current supplied (flowing) to the bias line Bs. A bias power supply circuit 217 that supplies a bias potential Vs1 is connected to the non-inverting input terminal of the current-voltage conversion circuit 215 of the bias source 203a, and a bias line Bsa is connected to the inverting input terminal. Moreover, a bias power supply circuit 217 that supplies a bias potential Vs2 is connected to the non-inverting input terminal of the current-voltage conversion circuit 215 of the bias source 203b, and a bias line Bsb is connected to the inverting input terminal.

[0018] The drive circuit 214 outputs drive signals including a conductive voltage Vcom that turns the switch element T into a conductive (ON) state and a non-conductive voltage Vss that turns the switch element T into a non-conductive (OFF) state to each drive line in response to control signals D-CLK, OE, and DIO input from the control unit 107 in FIG. 1. In this way, the drive circuit 214 controls the on / off of the switch element T to drive the pixel unit 101. The control signal D-CLK is a shift clock for a shift register used as the drive circuit 214. The control signal DIO is a pulse transferred by the shift register, and the control signal OE is a signal that controls the output terminal of the shift register. The required drive time and scanning direction are set by these control signals.

[0019] Furthermore, the control unit 107 controls the operation of each component of the readout circuit 102 by providing control signals RC, SH, and CLK to the readout circuit 102. Here, the control signal RC controls the operation of the reset switch of the integral amplifier 205. The control signal SH controls the operation of the sample-and-hold circuit 207. The control signal CLK controls the operation of the multiplexer 208.

[0020] FIG. 3 is a flow diagram showing an example of the operation of the radiation imaging apparatus 100 according to this embodiment. As described above, each component of the radiation imaging apparatus 100 is controlled by the control unit 107. When the user sets the imaging conditions for a radiation image, first, in S301, the detection unit 106 acquires radiation information from information on the current flowing through the bias line Bs obtained from the bias source 203, and determines whether radiation irradiation has started. The start of radiation irradiation may be determined by acquiring the amount of charge accumulated in the conversion element S of PIX from the radiation information, and determining that radiation irradiation has started if the radiation intensity calculated from the amount of charge exceeds a predetermined threshold. If the detection unit 106 determines that radiation irradiation has not started (NO in S301), the radiation imaging apparatus 100 proceeds to S302. Then, the control unit 107 causes the drive circuit 214 to perform reset driving (hereinafter, sometimes referred to as blank reading) to remove charge accumulated in the conversion element S of the pixel PIX due to dark current. The blank reading is performed in order from the first line (line 0) to the last line (line Y-1), and when the last line is reached, it returns to the first line.

[0021] If the detection unit 106 determines that radiation irradiation has started (YES in S301), the radiation imaging apparatus 100 transitions to S303, and the control unit 107 determines whether radiation irradiation has ended. The end of radiation irradiation may be determined when a predetermined time has elapsed since the start of radiation irradiation was determined. Alternatively, the control unit 107 may obtain the amount of charge accumulated in the conversion element S of PIX from radiation information obtained by the detection unit 106, and determine the end of radiation when the intensity of radiation calculated from the amount of charge falls below a predetermined threshold. If the end of radiation irradiation has not been determined (NO in S303), the radiation imaging apparatus 100 causes the drive circuit 214 to turn off the switch element T of the pixel PIX for acquiring a radiation image in S304. This causes driving (hereinafter, sometimes referred to as accumulation) to accumulate signals converted from radiation. If it is determined that the radiation irradiation has ended (YES in S303), the radiation imaging device 100 transitions to S305, and the drive circuit 214 and the readout circuit 102 perform drive to read out the charges generated in the conversion elements S of the pixels PIX (hereinafter, this may be referred to as main reading). The main reading can be performed in order from the first row to the last row of the pixels PIX arranged in the pixel unit 101. When the main reading reaches the last row, the series of imaging operations ends.

[0022] 4 is a schematic diagram of the drive timing of the radiation imaging device 100. The control unit 107 causes the drive circuit 214 to repeatedly perform driving (pre-reading) to turn on the switch elements S in order from the first row (row 0) to the last row (row Y-1) of the pixel unit 101 until radiation irradiation is started. When the pre-reading reaches the last row until radiation irradiation is started, the pre-reading is repeated from the first row.

[0023] When the detection unit 106 detects (determines) the start of radiation irradiation, the control unit 107 causes the drive circuit 214 to transition to driving (accumulation) and turn off the switch elements T of the rows to which all pixels PIX for acquiring a radiographic image are connected. Details of determining whether radiation irradiation has occurred will be described later. Accumulation continues until it is determined that radiation irradiation has ended. When radiation irradiation has ended, the control unit 107 controls the drive circuit 214 and readout circuit 102 to sequentially turn on the switch elements T from the first row to the last row, and performs actual reading of signals from the pixels PIX.

[0024] Next, Fig. 5(a) shows the drive timing when the start of radiation irradiation of the radiation imaging device 100 in this embodiment is detected. As a comparative example, Fig. 5(b) shows the drive timing when a malfunction occurs due to an impact or the like. Here, the row where the start of radiation irradiation is determined in the radiation imaging device 100 will be described as row Ys.

[0025] FIG. 5(a) is an enlarged view of the vicinity of row Ys in FIG. 4, where the start of radiation irradiation was determined. FIG. 5(a) shows current information output from the bias source 203, which is used by the detection unit 106 to output radiation information including time fluctuations in the intensity of radiation incident on the pixel unit 101. The detection unit 106 acquires radiation information from information about the current flowing through the bias line Bs obtained from the bias source 203 and determines the start of radiation irradiation. In FIG. 5(a), radiation irradiation starts between the scanning of rows Ys-1 and Ys, and information about the current flowing through the bias line Bs during the scanning of row Ys exceeds a determination threshold, so the detection unit 106 determines that radiation irradiation has started. Based on the result of this determination, the control unit 107 transitions the pixel unit 101 to an accumulation operation for acquiring a radiographic image.

[0026] On the other hand, Figure 5(b) is an enlarged view of the vicinity of the Ysth row in Figure 4 when an impact is applied to the radiation imaging device of the comparative example during a blank scan of the Ysth row. Generally, radiation imaging devices are required to be lighter to improve portability and ease of use. The housings of radiation imaging devices are currently being made of lighter materials, such as carbon, instead of the traditional metals. This reduces the rigidity of the housing, making it easier for impacts and pressure to be transmitted to the internal circuit boards. Similarly, circuit boards are becoming smaller and more densely packed, with trends toward the adoption of small, high-capacity ceramic capacitors and the integration of multiple circuits on a small number of boards. As a result, when impacts or pressure are transmitted to the circuit board, ceramic capacitors generate voltage noise due to the piezoelectric effect. This noise is then transmitted to various circuits due to interference between circuits, leading to malfunctions. In other words, the circuits in radiation imaging devices may become more susceptible to the effects of impacts and pressure. 5(b), an impact is applied during the blank reading scan of row Ys, and the information on the current flowing through bias line Bs exceeds the determination threshold, causing the detection unit 106 to erroneously determine that radiation irradiation has started. Based on this determination, the control unit 107 transitions the pixel unit 101 to accumulation operation.

[0027] Next, a detailed operation of the detection unit 106 in this embodiment for determining the start of radiation irradiation will be described with reference to Fig. 6. In this embodiment, the radiation imaging apparatus 100 may have the following characteristics regarding the bias current flowing through the bias line Bs.

[0028] (1) During radiation irradiation, a current proportional to the radiation dose per unit time flows through the bias line Bs. This current is shown as the "first signal" in Figure 6. This current can flow more when the switch element T of the pixel PIX is in the on (conducting) state than when it is in the off (non-conducting) state, but for simplicity, it is shown as a constant in the figure.

[0029] (2) When the switch element T of the pixel PIX irradiated with radiation is turned on, a current proportional to the amount of charge accumulated in the conversion element S of the pixel PIX up until the time when the switch element T is turned on flows through the bias line Bs. This current is shown as the "second signal" in FIG. 6.

[0030] (3) When the switch element T of the pixel PIX is switched on and off, a current flows through the bias line Bs. This current can be called switching noise (not shown).

[0031] (4) When an impact or a magnetic field is applied to the radiation imaging device 100, a current corresponding to the frequency of the noise applied to the bias line Bs may flow. This current is called external noise, and is shown as "external noise" in FIG. 6. For example, due to the influence of an electromagnetic field generated by a commercial power supply, a current of about 50 to 60 Hz may flow in the bias line Bs. Furthermore, when an impact is applied to the radiation imaging device, a current of several Hz to several kHz may flow in the bias line Bs.

[0032] (5) Even when no magnetic field or impact is applied to the radiation imaging device 100, a current flows through the bias line Bs due to electromagnetic waves generated by the radiation imaging device 100 itself and internal noise of the detection unit 106, etc. This current is called system noise (not shown).

[0033] In the "bias current" in Figure 6, the first signal, second signal, and external noise (as well as switching noise and system noise) are shown as being constant over time. However, Figure 6 only conceptually shows when these signals and noise appear, and they are not necessarily constant over time.

[0034] To detect radiation irradiation, more specifically, the start of radiation irradiation, a sample value of a signal resulting from the current flowing through the bias line Bs may be used as a detection signal, but this may result in an erroneous determination, as shown in Fig. 5(b) above. Therefore, in the radiation imaging device 100 of this embodiment, in order to reduce the influence of external noise due to impacts, magnetic fields, etc., the detection unit 106 calculates radiation information and detects radiation irradiation using the method described below.

[0035] In this embodiment, as shown in FIG. 2, the bias power supply unit 104 includes multiple bias sources 203. The pixels PIX in the pixel unit 101 form multiple pixel groups. More specifically, one bias source 203 is provided corresponding to each pixel group, and each of the multiple bias sources 203 supplies a bias potential to the conversion element S of the pixel PIX via a bias line Bs that is electrically independent for each bias source 203. In the configuration shown in FIG. 2, the bias source 203a supplies a bias potential to the pixel group including the pixel PIXa via the bias line Bsa, and the bias source 203b supplies a bias potential to the pixel group including the pixel PIXb via the bias line Bsb. The detection unit 106 acquires radiation information based on the signals of the currents flowing through the bias lines Bsa and Bsb output from the bias sources 203a and 203b, and detects radiation irradiation. For example, the detection unit 106 determines that radiation is being irradiated when the radiation information or the integrated value of the radiation information exceeds a predetermined threshold.

[0036] As shown in FIG. 6, the drive cycle of the drive circuit 214 is represented by time TI. That is, the radiation imaging apparatus 100 performs one reset operation (empty read) every time TI. Within time TI, the time during which the drive circuit 214 supplies a high-level drive signal (hereinafter sometimes referred to as "on time") is represented by time TH, and the time during which the drive circuit 214 supplies a low-level drive signal (hereinafter sometimes referred to as "off time") is represented by time TL. In this embodiment, as an example, the control unit 107 controls the drive circuit 214 so that time TH = time TL. That is, upon the start of one reset operation, the drive circuit 214 switches the drive signal of a certain drive line Vg from low to high. Then, after time TH has elapsed, the drive signal of the drive line Vg is returned to low, and after a further time TL of the same length has elapsed, the next reset operation is started. For example, time TH = time TL = 16 μsec.

[0037] As shown in FIG. 6 , the period during which the detection unit 106 samples the current flowing from the bias sources 203a and 203b through the bias lines Bsa and Bsb is represented by time TS. In this embodiment, the detection unit 106 samples a signal value representing the current flowing from the bias sources 203a and 203b through the bias lines Bsa and Bsb during the period during which the drive line Vg supplies a high-level drive signal to the switch element T of a pixel PIX, assuming time TH = TS. In the timing diagram shown in FIG. 6 , time TH = time TL = time TS = TI / 2, but this is not limited to these values. Time TH and time TL may be set to any desired time period or ratio. Time TH and time TS do not need to be equal. Time TS may be set to a period shorter than time TH, and the detection unit 106 may perform multiple sampling operations during time TH.

[0038] In this embodiment, as described above, the bias power supply unit 104 is provided with two bias sources 203a and 203b. Therefore, the detection unit 106 can simultaneously acquire two signals representing the currents flowing through the bias lines Bsa and Bsb output from the bias sources 203a and 203b during a single time period TS. Here, a signal value representing the current flowing through the bias line Bs connected to the first pixel group, which includes the pixel PIX whose switch element T is turned on by the drive circuit 214, is referred to as an effective value S. Furthermore, a signal value representing the current flowing through the bias line Bs connected to the second pixel group, whose switch element T is turned off, is referred to as an N value. Furthermore, the bias line connected to the first pixel group is referred to as the first bias line, and the bias line connected to the second pixel group is referred to as the second bias line.

[0039] The detection unit 106 may sample the effective value S and the noise value N at the same timing, as shown in Fig. 6. Because the effective value S and the noise value N are acquired without any time lag, the second signal described above is included only in the effective value S when the switch element T is in the conductive state. On the other hand, the first signal and the external noise are included in approximately the same amounts in the effective value S and the noise value N regardless of the conductive state of the switch element T. Therefore, the detection unit 106 can remove the external noise based on the effective value S and the noise value N, more specifically, based on the difference between the effective value S and the noise value N, and can extract only the second signal as radiation information.

[0040] 2, the current information output from the two bias sources 203a and 203b is an analog value obtained by converting the current flowing through the respective bias lines Bsa and Bsb into a voltage. Therefore, the detection unit 106 is configured to calculate radiation information for determining the presence or absence of radiation irradiation based on a digital value obtained by analog-to-digital conversion of the difference between the analog values ​​of the effective value S and the noise value N. However, this is not limiting. For example, an A / D converter that performs A / D conversion on the output of the current-voltage conversion circuit 215 provided in the bias source 203 may be provided between the bias source 203 and the detection unit 106. In this case, the detection unit 106 may calculate radiation information based on the difference between the A / D converted digital values ​​of the effective value S and the noise value N output from the bias sources 203a and 203b.

[0041] Here, the two sample values ​​acquired in the y-th (y is any natural number) reset operation (empty reading) are defined as the valid value S(y) and the noise value N(y), respectively, and the radiation information used to detect the radiation signal is defined as X(y). The detection unit 106 may calculate the radiation information X(y) by performing an operation such as that shown in equation (1). X(y) = S(y) - N(y) (1)

[0042] Equation (1) represents the difference between the current flowing through the bias line Bs connected to a pixel group including a pixel PIX whose switch element T is turned on and the current flowing through the bias line Bs connected to a pixel group whose switch element T is turned off. Furthermore, if the output characteristics of each pixel PIX differ, radiation information may be calculated using signal values ​​in which S(y) and N(y) are weighted according to the variations between each pixel PIX, as in equation (2). X(y)=a×S(y)―b×N(y) (2)

[0043] When the detector 106 detects the start of radiation irradiation, the controller 107 turns off all switch elements T, causing the pixels PIX to accumulate radiation-induced signals. The controller 107 then performs actual readout upon the end of radiation irradiation. In the configuration shown in FIG. 2, two drive lines are connected to the pixels PIX arranged in the row direction to divide the pixels into respective pixel groups. In the configuration shown in FIG. 2, the pixels PIX include pixels PIXa and PIXb adjacent to each other in the row direction. The pixels PIXa and PIXb are included in different pixel groups among multiple pixel groups and are connected to different drive lines Vg among multiple drive lines Vg. While the circuit diagram shown in Patent Document 1 has Y drive lines Vg, the present embodiment has 2Y drive lines Vg. Therefore, if the actual readout is performed by sequentially turning on the switch elements T from the first row (row 0) to the last row (row Y-1), it takes twice as long to read out signals from all rows if the drive period time TI is the same as in Patent Document 1. Therefore, as shown in Fig. 7, during the actual reading, the control unit 107 controls the drive circuit 214 to simultaneously turn on the drive lines Vg for two rows, thereby suppressing an increase in the actual reading time that accompanies an increase in the drive lines Vg. Specifically, as shown in Fig. 2, the signal line Sig is shared by the pixels arranged in each column among the multiple pixels PIX. Therefore, when acquiring radiation image data, the drive circuit 214 simultaneously turns on the switch elements T of the pixels PIXa and PIXb, thereby suppressing an increase in the actual reading time.

[0044] In this embodiment, by providing two bias sources 203, the effective value S and the noise value N are sampled at the same timing. This makes it possible to provide a radiation imaging apparatus 100 and a radiation imaging system SYS that are highly resistant to noise that occurs when pressure or impact is applied to the housing and that can obtain high-quality image information without requiring a synchronization signal with the radiation generation apparatus 130.

[0045] In this embodiment, two bias sources 203 are provided, but three or more bias sources 203 may be provided. In this case, the effective value S and the noise value N may be sampled appropriately from the currents flowing through three or more bias lines Bs. In addition, in the configuration shown in FIG. 2, the pixels PIX belonging to two pixel groups are alternately arranged in the row direction, and adjacent pixels PIX in the column direction are included in the same pixel group of the two pixel groups, but this is not limited to this. The pixels PIX belonging to each pixel group may be arranged in an appropriate order.

[0046] 6, the effective value S and the noise value N are sampled at the same timing, but this is not limiting. When there is one bias source 203, the effective value S and the noise value N can only be sampled at different timings. Therefore, by having the detection unit 106 acquire the effective value S and the noise value N so that at least a portion of the sampling timing overlaps, it becomes possible to suppress the influence of external noise compared to when there is one bias source 203.

[0047] Furthermore, the difference in the number of pixels PIX included in each of the multiple pixel groups may be within 10% for each pixel group. Also, for example, the number of pixels PIX included in each pixel group may be the same. By making the number of pixels PIX included in each pixel group uniform, the amounts of external noise, switching noise, system noise, and the like flowing through the bias line Bs are made uniform, thereby suppressing the influence of noise when the detection unit 106 detects whether radiation is irradiated.

[0048] The time constants of the bias lines Bsa and Bsb can significantly affect the accuracy of radiation information calculation and image quality. One such effect is crosstalk. Crosstalk occurs when a signal read from a pixel is affected by a signal from another pixel read at a different time. Potential fluctuations caused by parasitic capacitance on the bias lines when reading out a signal from another pixel may not recover by the time the signal from that pixel is read out, and this fluctuation may be superimposed on the signal that should have been read out. The amount of this superimposition depends on the time constant of the bias lines. If the time constants of the bias lines Bsa and Bsb differ significantly, the amount of crosstalk that can occur may differ significantly, which may affect the quality of the resulting radiation image. Another effect is current information, including temporal fluctuations in the amount of current flowing through the bias line Bs. If the time constants of the bias lines Bsa and Bsb differ significantly, the amount of current flowing through the bias line Bs may differ significantly, which may affect the resulting current information. This may affect the accuracy of determining the start of radiation irradiation.

[0049] Therefore, the time constant of the bias line Bsa and the time constant of the bias line Bsb, i.e., the time constant of the first bias line and the time constant of the second bias line, need to be approximately the same. First, referring to FIG. 8, a schematic configuration of an example of the configuration of the detection unit 110 of the radiation imaging device 100 will be described. As shown in FIG. 8, pixels PIXa and PIXb, drive lines Vg, signal lines Sig, and bias lines Bs that constitute the pixel unit 101 are arranged on an insulating substrate 803. Meanwhile, ICs that constitute the readout circuit 102 and ICs that constitute the bias power supply unit 104 are arranged on the printed circuit board 801. The readout circuit 102 is electrically connected to the signal line Sig of the insulating substrate 803 via a flexible circuit board 802, and the bias power supply unit 104 is electrically connected to the bias line Bs of the insulating substrate 803 via the flexible circuit board 802. As shown in FIG. 8 , the bias line Bsa and the bias line Bsb are arranged as a pair, with one pair located at one end of the wiring group of the signal lines Sig connected to the flexible circuit board 802 and the other pair located at the other end. Alternatively, as shown in FIG. 9 , it is also possible to arrange the bias line Bsa at one end of the wiring group of the signal lines Sig and the bias line Bsb at the other end. The arrangement shown in FIG. 9 results in differences in the wiring lengths of the bias lines Bsa and Bsb from the flexible circuit board 802 to each pixel PIX, which can result in differences in the resistance and capacitance of the wiring. The arrangement shown in FIG. 8 makes it easier to align the lengths of the bias lines Bsa and Bsb connected to the flexible circuit board 802 from each pixel PIX compared to the arrangement shown in FIG. 9 . This reduces the difference in the time constants of the bias lines Bsa and Bsb.

[0050] Next, an example configuration of the bias line Bsa and bias line Bsb shown in FIG. 8 will be described using FIG. 10. The bias line Bsa has a plurality of individual wiring sections 1006, a routing wiring section 1003, and a connection wiring section 1001. The individual wiring section 1006 is a wiring section for connecting to the conversion elements S of a plurality of pixels PIXa arranged in the column direction of the first pixel group, and the routing wiring section 1003 is a wiring section for electrically connecting the plurality of individual wiring sections 1006. The connection wiring section 1001 is a wiring section for connecting the routing wiring section 1003 to the flexible circuit board 802. The bias line Bsb has a plurality of individual wiring sections 1007, a routing wiring section 1004, and a connection wiring section 1002. The individual wiring section 1007 is a wiring section for connecting to the conversion elements S of a plurality of pixels PIXb arranged in the column direction of the second pixel group, and the routing wiring section 1004 is a wiring section for electrically connecting the plurality of individual wiring sections 1007. The connection wiring section 1002 is a wiring section for connecting the drawn wiring section 1004 and the flexible circuit board 802 .

[0051] Next, the cross-sectional structure of each bias line Bs shown in FIG. 10 will be described using FIGS. 11(a) and 11(b). FIG. 11(a) is a cross-section taken along line A-A' in FIG. 10, and FIG. 11(b) is a cross-section taken along line B-B' in FIG. 10. Each bias line has a first wiring layer 1118, a second wiring layer 1115, and a third wiring layer 1112. The first wiring layer 1118 is a wiring layer that can form the drive line Vg and extends in the row direction. The second wiring layer 1115 is a wiring layer that can form the signal line Sig and extends in the column direction. The third wiring layer 1112 is a wiring layer that can form the connection wiring section 1001, the connection wiring section 1002, the routing wiring section 1003, the routing wiring section 1004, the individual wiring section 1006, and the individual wiring section 1007. The second wiring layer 1115 can be provided on the first wiring layer 1118 with insulating layers 1117 and 1116 sandwiched therebetween. The third wiring layer 1112 can be provided on the second wiring layer 1115 with insulating layers 1114 and 1113 sandwiched therebetween. The third wiring layer 1112 can be covered and insulated by an insulating layer 1111 except for the portion connected to the flexible circuit board 802. The first wiring layer 1118, the second wiring layer 1115, and the third wiring layer 1112 can be electrically connected via contact holes 1005 shown in FIG.

[0052] As shown in FIGS. 10, 11(a), and 11(b), the bias line Bsa and the bias line Bsb are matched in width, thickness, length, and number of contact holes of corresponding layers. This allows the bias line Bsa and the bias line Bsb to have approximately the same time constant. In particular, it is preferable to match the width, thickness, length, and number of contact holes of each layer in the wiring portion 1003 of the bias line Bsa and the wiring portion 1004 of the bias line Bsb. It is also preferable to match the width, thickness, length, and number of contact holes of each layer in the connection wiring portion 1001 of the bias line Bsa and the connection wiring portion 1002 of the bias line Bsb. In other words, it is desirable that the resistance and capacitance of the wiring portion 1003 and the connection wiring portion 1001 of the bias line Bsa are approximately the same as the resistance and capacitance of the wiring portion 1004 and the connection wiring portion 1002 of the bias line Bsb.

[0053] Next, the substantially same range will be explained below. The magnitude of the image artifact caused by crosstalk is proportional to the ratio of the difference Δτ between the time constant of the bias line Bsa and the time constant of the bias line Bsb to the time constant τ of the pixel PIX. Here, the time constant τ of the pixel PIX is τ, where τ is the time constant when the switch element T of the pixel PIX is on. ON , the time constant of the signal line Sig is τ sig , the time constant τ of the bias line bs , the time constant τ for pixel PIX is τ=τ ON +τ sig +τ bs ···(1) The difference in time constants Δτ is expressed as the time constant τ of the signal line Sig. sig and the time constant τ of the switch element T when it is on ON is considered to be the same within the pixel unit 101, Δτ=|τ bsa -τ bsb |···(2) Here, the resistance of the bias line Bsa is R bsa , the capacitance of the bias line Bsa is C bsa , the resistance of the bias line Bsb is R bsb , the capacitance of the bias line Bsa is C bsb , the capacitance of the conversion element S of each pixel is C S , the resistance of the switch element T when it is on is R ON Then, Δτ / τ=|(R bsa C bsa -R bsb C bsb )| / C S ·R ON ···(3) It is expressed as:

[0054] It has been verified that if Δτ / τ given by formula (3) is 0.1% or less, artifacts in radiographic images caused by crosstalk do not cause problems in radiographic image diagnosis. Therefore, the range in which Δτ / τ is 0.1% or less is approximately the same range as in the present invention.

[0055] 2, bias source 203 includes a current-voltage conversion circuit 215 including an operational amplifier and a resistor as a circuit for outputting current information, but this configuration is not limited to this. For example, as shown in FIG. 12, a common bias power supply circuit 1217 may be connected to the non-inverting input terminal of current-voltage conversion circuit 1215 of bias source 1203a and the non-inverting input terminal of current-voltage conversion circuit 1215 of bias source 1203b. This allows noise components that may be mixed in from bias power supply circuit 1217 to be shared between the two systems, and noise components that can be reduced by differential processing are also shared, thereby improving accuracy. Alternatively, the output terminals of each current-voltage conversion circuit 1215 may be input to a differential amplifier, which outputs a differential analog signal as a circuit for outputting current information.

[0056] Next, a modified example of the configuration of the detection unit 110 of the radiation imaging device 100 shown in FIG. 2 will be described with reference to FIG. 13. FIG. 13 is an equivalent circuit diagram showing an example of the configuration of the detection unit 110 of the radiation imaging device 100. The configuration of the detection unit 110 of FIG. 8 differs from the configuration of FIG. 2 in the configuration of the pixel unit 101 and the configuration of the amplifier circuit 206 of the readout circuit 102. Specifically, pixels PIXa and PIXb that are adjacent to each other in the row direction and that are included in different pixel groups and connected to different drive lines Vg share a signal line Sig. Therefore, the number of signal lines Sig is halved compared to the configuration shown in FIG. 2. Accordingly, the number of amplifier circuits 206 arranged in the readout circuit 102 is halved compared to the configuration shown in FIG. 2. As a result, the configuration shown in FIG. 2 can reduce the number of amplifier circuits 206 in the readout circuit 102, which addresses the issue of a larger drive circuit 214 compared to the configuration of Patent Document 1. This makes it possible to suppress an increase in cost due to an increase in the number of ICs in the entire radiation imaging apparatus 100 including the drive circuit 214 and the readout circuit 102, and to reduce the number of wires in the pixel section 101.

[0057] As described above with reference to FIG. 6, the presence or absence of radiation irradiation can be detected by connecting the pixels PIX to different bias sources 203 via electrically independent bias lines Bs, allowing the effective value S and noise value N to be sampled at the same timing. Furthermore, similar to the configuration shown in FIG. 2, the pixels PIX that acquire the effective value S and noise value N are arranged adjacent to each other. Therefore, even if a localized impact is applied as noise to the housing of the radiation imaging device 100, it can be assumed that the same noise is applied at the same timing for the pitch at which the pixels PIX are arranged. Therefore, the operation described with reference to FIG. 6 enables noise removal in the configuration shown in FIG. 13 as well, enabling more accurate detection of the start of radiation irradiation.

[0058] FIG. 14 is a schematic diagram showing the drive timing of the detection unit 110 shown in FIG. 13. The drive for detecting the presence or absence of radiation irradiation during pre-reading is the same as the drive described using FIG. 6, and therefore will not be described here. In this embodiment, adjacent pixels PIXa and PIIXb are connected to the same signal line Sig. Therefore, as described above, it is impossible to turn on the switch elements T for two rows simultaneously during main reading, because the signals from the two read pixels would be added together. For this reason, as shown in FIG. 9, when acquiring radiation image data, the drive circuit 214 turns on the switch elements T of pixels PIX connected to the same signal line Sig at different times. This makes it possible to read out the charges accumulated in each pixel PIX.

[0059] In this embodiment, too, by providing two bias sources 203, the effective value S and the noise value N are sampled at the same timing. This makes it possible to provide a radiation imaging apparatus 100 and a radiation imaging system SYS that are highly resistant to noise that occurs when pressure or impact is applied to the housing and that can obtain high-quality image information without requiring a synchronization signal with the radiation generation device 130. Furthermore, by sharing the signal line Sig through which adjacent pixels PIX in the row direction output signals, it is possible to reduce the number of amplifier circuits 206 in the readout circuit 102. This makes it possible to offset the increase in cost due to the increase in circuit scale in the drive circuit 214.

[0060] Next, a method for suppressing a decrease in the frame rate of blank reading that accompanies an increase in the number of drive lines Vg will be described with reference to Fig. 15. As described above with reference to Fig. 3, the drive cycle TI of the drive circuit 214 includes two periods: an on time (time TH) and an off time (time TL). That is, the multiple drive lines Vg include a first drive line (e.g., drive line Vg1-1) and a second drive line (e.g., Vg1-2) that is different from the first drive line, and when determining whether or not radiation is being irradiated, the drive circuit 214 turns on the switch element T connected to the drive line Vg1-2 after a predetermined time has elapsed since the switch element T connected to the drive line Vg1-1 was turned off.

[0061] On the other hand, the detection unit 110 of the radiation imaging apparatus 100 of this embodiment includes multiple (two systems in this embodiment) bias sources 203, and therefore can simultaneously sample the effective value S and the noise value N during time TH. In other words, the configuration of this embodiment does not necessarily require an off time (time TL). Therefore, when determining whether or not radiation is being irradiated, the drive circuit 214 controls the switch element T connected to drive line Vg1-1 so that the timing at which it changes from on to off and the timing at which it changes from off to on for the switch element T connected to drive line Vg1-2 overlap.

[0062] It is generally known that a current flows through the bias line Bs when the switch element T is switched on and off. This current is called switching noise. As shown in FIG. 10, the falling edge of the drive signal to the switch element T in one pixel row and the rising edge of the drive signal to the switch element T in the next pixel row can be made to overlap, thereby canceling out the switching noise. In other words, the driving of the detection unit 110 shown in FIG. 15 is effective when the switching noise of the switch element T is large.

[0063] 15, the off time (time TL) during the blank readout is not required, and the drive cycle per row can be shortened by setting time TI = time TH. In the configuration of the radiation imaging device 100 of this embodiment, the number of drive lines Vg increases compared to the configuration shown in Patent Document 1. However, by providing multiple bias sources 203, it is possible to shorten time TI, which is the drive cycle during blank readout, and the readout time for one frame per row can be maintained.

[0064] 15 also uses two bias sources 203, so that the effective value S and the noise value N are sampled at the same time. This makes it possible to provide a radiation imaging device 100 and a radiation imaging system SYS that are highly resistant to noise that occurs when pressure or impact is applied to the housing and that can obtain high-quality image information without requiring a synchronization signal with the radiation generation device 130. As described above, in the pre-reading, switching noise caused by the on / off of the switch element T can be reduced, thereby improving the accuracy of determining the start of radiation irradiation. Furthermore, by omitting the time TL in the pre-reading, the sampling rate for acquiring the current flowing through the bias line Bs for determining the presence or absence of radiation irradiation can be improved, thereby improving the time resolution for determining the presence or absence of radiation irradiation.

[0065] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0066] 106 Detection unit 203 Bias Source 214 Drive circuit Bs bias line PIX S conversion circuit T switch element

Claims

1. A radiation imaging device including a plurality of pixel groups, each of which is arranged to correspond to one bias source, a plurality of bias sources, a drive circuit, and a detection unit, each of the plurality of pixel groups is configured by a pixel including a conversion element that converts radiation into an electric charge and a switch element that connects the conversion element to a signal line; each of the plurality of bias sources supplies a bias potential to the conversion element of the pixel via at least one bias line among a plurality of bias lines electrically independent for each bias source; the drive circuit controls the switch element of the pixel; The detection unit acquiring a first signal value representing a current flowing through a first bias line among the plurality of bias lines connected to a first pixel group among the plurality of pixel groups, the first pixel group including the pixel whose switch element has been turned on by the drive circuit, and a second signal value representing a current flowing through a second bias line among the plurality of bias lines connected to a second pixel group among the plurality of pixel groups, the switch element of which is in an off state, so that sampling timings at least partially overlap; determining whether radiation has been irradiated or not based on the first signal value and the second signal value; A radiation imaging apparatus, wherein the time constant of the first bias line and the time constant of the second bias line are substantially the same.

2. The radiation imaging apparatus according to claim 1 , wherein the detection unit samples the first signal value and the second signal value at the same timing.

3. a pixel section in which the plurality of pixel groups are arranged is configured by a plurality of the pixels arranged in a matrix; a plurality of drive lines for the drive circuit to control the switch elements are arranged along a row direction; the plurality of pixels include a first pixel and a second pixel adjacent to each other in a row direction, 3. The radiation imaging device according to claim 1, wherein the first pixel and the second pixel are included in different pixel groups among the plurality of pixel groups and are connected to different drive lines among the plurality of drive lines.

4. the signal line is shared by pixels arranged in each column among the plurality of pixels, 4. The radiation imaging apparatus according to claim 3, wherein, when acquiring radiation image data, the drive circuit simultaneously turns on the switch elements of the first pixel and the second pixel.

5. 4. The radiation imaging apparatus according to claim 3, wherein the first pixel and the second pixel share the signal line.

6. 6. The radiation imaging device according to claim 4, wherein, when acquiring radiation image data, the drive circuit turns on the switch elements of pixels connected to the same signal line among the plurality of pixels at different timings.

7. 7. The radiation imaging apparatus according to claim 3, wherein pixels adjacent to each other in the column direction among the plurality of pixels are included in the same pixel group among the plurality of pixel groups.

8. the plurality of drive lines include a first drive line and a second drive line different from the first drive line, 8. The radiation imaging device according to claim 3, wherein, when determining whether radiation is being irradiated or not, the drive circuit controls the switch element connected to the first drive line so that the timing at which the switch element is turned from on to off and the timing at which the switch element connected to the second drive line is turned from off to on overlap.

9. the plurality of drive lines include a first drive line and a second drive line different from the first drive line, 8. The radiation imaging device according to claim 3, wherein, when determining whether radiation is irradiated or not, the drive circuit turns on the switch element connected to the second drive line after a predetermined time has elapsed since the switch element connected to the first drive line was turned from on to off.

10. 10. The radiation imaging device according to claim 8, wherein the pixel including the switch element connected to the first drive line and the pixel including the switch element connected to the second drive line are included in different pixel groups among the plurality of pixel groups.

11. 11. The radiation imaging apparatus according to claim 1, wherein the plurality of pixel groups are two pixel groups.

12. 12. The radiation imaging apparatus according to claim 1, wherein the detection unit determines whether radiation is irradiated or not based on a difference between the first signal value and the second signal value.

13. the first signal value and the second signal value are each analog values; The radiation imaging device according to claim 12, wherein the detection unit determines whether radiation is irradiated or not based on a digital value obtained by analog-to-digital conversion of a difference between the analog values ​​of the first signal value and the second signal value.

14. 14. The radiation imaging apparatus according to claim 1, wherein a difference in the number of pixels included in each of the plurality of pixel groups is within 10%.

15. the plurality of pixel groups, the signal lines, and the plurality of bias lines are disposed on an insulating substrate; a readout circuit that outputs an electrical signal corresponding to the charge of the conversion element via the signal line, and the plurality of bias sources are disposed on a printed circuit board; the plurality of bias lines and the plurality of signal lines are connected to the printed circuit board via a flexible circuit board; 15. The radiation imaging device according to claim 1, wherein the first bias line and the second bias line are arranged as a pair, one pair being located at one end of the wiring group of the signal lines connected to the flexible circuit board, and the other pair being located at the other end.

16. each of the plurality of bias lines includes an individual wiring section that is a wiring section connected to conversion elements of a plurality of pixels in a column direction of the pixel group; a wiring route section that is a wiring section that electrically connects the plurality of individual wiring sections; and a connection wiring section that is a wiring section for connecting the wiring route section and the flexible circuit board; 16. The radiation imaging device according to claim 15, wherein the resistance and capacitance of the wiring portion and the connecting wiring portion of the first bias line are substantially the same as the resistance and capacitance of the wiring portion and the connecting wiring portion of the second bias line.

17. The resistance of the first bias line is R ｂｓａ , the capacitance of the first bias line is C ｂｓａ , the resistance of the second bias line is R ｂｓｂ , the capacitance of the second bias line is C ｂｓｂ , the capacitance of the conversion element is C Ｓ , the resistance of the switch element when it is on is R ＯＮ Then, Δt / t=|(R ｂｓａ ・C ｂｓａ -R ｂｓｂ ・C ｂｓｂ )| / C Ｓ ・R ＯＮ ・・・(3) 17. The radiation imaging apparatus according to claim 1, wherein if Δτ / τ expressed by the following formula is 0.1% or less, the time constant of the first bias line and the time constant of the second bias line are substantially the same.

18. A radiation imaging apparatus according to any one of claims 1 to 17; a radiation generating device that irradiates the radiation imaging device with radiation; A radiation imaging system comprising:

Images