JP2021074400A - Radiography apparatus and radiography system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an advantageous technique for detecting the presence or absence of irradiation of radiation with higher accuracy. SOLUTION: A bias potential is applied to a first pixel group and a second pixel group each composed of pixels including a conversion element and a switch element, and a conversion element of pixels included in the first pixel group via a first bias line. Controls the first bias power supply to be supplied, the second bias power supply to supply the bias potential to the conversion element of the pixels included in the second pixel group via the second bias line different from the first bias line, and the switch element. The drive circuit includes a drive circuit and a detection unit, and the drive circuit turns on the switch element of the pixel included in the first pixel group and the switch element of the pixel included in the second pixel group at different timings for detection. The unit detects the presence or absence of irradiation of radiation based on the first signal value indicating the current flowing through the first bias line and the second signal value indicating the current flowing through the second bias line. [Selection diagram] Fig. 1

Description

The present invention relates to a radiation imaging device and a radiation imaging system.

In medical image diagnosis and non-destructive inspection, a radiation imaging device using a plane detector (FPD) made of a semiconductor material is widely used. Patent Document 1 discloses a radiation imaging apparatus that detects the start and end of irradiation of radiation from a current flowing through a bias line for applying a bias voltage to a radiation detection element. Further, in Patent Document 1, in the reset process performed until the start of irradiation of radiation is detected, the noise when switching the on / off of the switch (TFT) that emits the dark charge generated by the detection element is a bias line. It has been shown that it is superimposed on the current flowing through. Patent Document 1 shows a method of suppressing the influence of noise when switching the TFT on and off in order to detect the start of irradiation of radiation.

Japanese Unexamined Patent Publication No. 2010-268171

The noise superimposed on the bias line when switching the TFT on and off includes a component due to the parasitic capacitance between the scan line and the bias line for controlling the on or off of the TFT. Since each scanning line intersects many bias lines, noise when switching the TFT on and off becomes large with respect to the current flowing through the bias lines due to irradiation of radiation, and the method shown in Patent Document 1 , It may not be possible to sufficiently suppress the influence of noise.

An object of the present invention is to provide a technique advantageous for detecting the presence or absence of radiation irradiation with higher accuracy.

In view of the above problems, the radiation imaging device according to the embodiment of the present invention is a first pixel group composed of pixels including a conversion element that converts radiation into electric charge and a switch element that connects the conversion element to a column signal line. And the second bias power supply that supplies the bias potential to the conversion element of the pixels included in the first pixel group and the second pixel group via the first bias line, and the conversion element of the pixels included in the second pixel group. A radiation imaging device including a second bias power supply that supplies a bias potential via a second bias line different from the first bias line, a drive circuit that controls a switch element, and a detection unit. The switch element of the pixel included in the first pixel group and the switch element of the pixel included in the second pixel group are turned on at different timings, and the detection unit is a first signal indicating a current flowing through the first bias line. It is characterized in that the presence or absence of irradiation of radiation is detected based on the value and the second signal value indicating the current flowing through the second bias line.

By the above means, a technique advantageous for detecting the presence or absence of radiation irradiation with higher accuracy is provided.

The figure which shows the structural example of the radiation imaging system using the radiation imaging apparatus which concerns on this invention. The figure which shows the structural example of the radiation imaging apparatus of FIG. The flow chart explaining the operation of the radiation imaging apparatus of FIG. The timing diagram explaining the operation of the radiation imaging apparatus of FIG. A plan view and a cross-sectional view showing a configuration example of pixels of the radiation imaging apparatus of FIG. The figure which shows the structural example of the radiation imaging apparatus of FIG. The timing diagram explaining the operation of the radiation imaging apparatus of FIG. FIG. 5 is a plan view showing a configuration example of pixels of the radiation imaging apparatus of FIG. A plan view and a cross-sectional view showing a configuration example of pixels of the radiation imaging apparatus of FIG. The figure which shows the structural example of the radiation imaging apparatus of FIG. The timing diagram explaining the operation of the radiation imaging apparatus of FIG. A plan view and a cross-sectional view showing a configuration example of pixels of the radiation imaging apparatus of FIG.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiment, not all of the plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the attached drawings, the same or similar configurations are designated by the same reference numbers, and duplicate explanations are omitted.

Further, the radiation in the present invention includes beams having the same or higher energy, for example, X, in addition to α rays, β rays, γ rays, etc., which are beams produced by particles (including photons) emitted by radiation decay. It can also include lines, particle beams, cosmic rays, etc.

First Embodiment The radiation imaging apparatus according to this embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 is a diagram showing a configuration example of a radiation imaging system SYS using the radiation imaging device 100 according to the first embodiment. The radiation imaging system SYS of the present embodiment includes a radiation imaging device 100, a control computer 120, a radiation generator 130, and a radiation control device 140.

The radiation generator 130 exposes the radiation imaging device 100 to radiation according to the control from the radiation control device 140. The control computer 120 can control the entire radiation imaging system SYS. Further, the control computer 120 acquires a radiation image generated by the radiation emitted from the radiation generator 130 to the radiation imaging device 100 via the subject.

The radiation imaging device 100 includes an imaging unit 110 including a pixel unit 101, a reading 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. A plurality of pixels for detecting radiation are arranged in the pixel unit 101 in a two-dimensional array. The read circuit 102 reads charge information from the pixel unit 101. The reference power supply 103 supplies a reference voltage to the read circuit 102. The bias power supply unit 104 supplies the bias potential to the pixel conversion element arranged in the pixel unit 101. The power supply unit 105 supplies electric power to each power source including the reference power supply 103 and the bias power supply unit 104. The detection unit 106 acquires current information from the bias power supply unit 104. More specifically, the detection unit 106 acquires information on the current flowing through the bias line for the bias power supply unit 104 to supply the bias potential to each pixel of the pixel unit 101 from the bias power supply unit 104. The detection unit 106 calculates the current information output from the bias power supply, and outputs the radiation information including the time variation of the intensity of the radiation incident on the pixel unit 101. As the detection unit 106, a digital signal processing circuit such as an FPGA, a DSP, or a processor can be used. Further, the detection unit 106 may be configured by using an analog circuit such as a sample hold circuit or an operational amplifier. Further, in the configuration shown in FIG. 1, the detection unit 106 is arranged in the radiation imaging device 100, but the control computer 120 may have the function of the detection unit 106. In this case, the radiation imaging device 100 shown in FIG. 1 and the portion of the control computer 120 that functions as the detection unit 106 are included, and can be said to be the “radiation imaging device” of the present embodiment. The imaging unit 110 will be described later with reference to FIG. The control unit 107 controls the entire radiation imaging device 100, such as driving the radiation imaging device 100. The control unit 107 controls the image pickup unit 110 by a drive method transmitted from the control computer 120 according to a user setting or the like. Further, the driving method of the imaging unit 110 may be changed by using the radiation information output by the detection unit 106.

FIG. 2 is an equivalent circuit diagram showing a configuration example of the imaging unit 110 of the radiation imaging apparatus 100. FIG. 2 shows a pixel portion 101 having pixel PIXs of 6 rows × 6 columns for the sake of simplicity of description. However, the pixel portion 101 of the actual radiation imaging device 100 may have more pixels, for example, a 17-inch radiation imaging device 100 may have a pixel PIX of about 2800 rows × about 2800 columns.

The pixel unit 101 is a two-dimensional detector having a plurality of pixels PIX arranged in a matrix. The pixel PIX includes a conversion element S (S11 to S66) that converts radiation into an electric charge, and a switch element T (T11 to T66) that connects the conversion element S to a column signal line Sigma and outputs an electric signal according to the electric charge. ,including. In the present embodiment, the conversion element S is an indirect type including a photoelectric conversion element and a wavelength converter that converts radiation into light in a wavelength band that can be detected by the photoelectric conversion element on the incident side of the radiation of the photoelectric conversion element. It is a conversion element. As a photoelectric conversion element that converts light into electric charges, a MIS-type photodiode that is arranged on an insulating substrate such as a glass substrate and whose main material is a semiconductor material such as amorphous silicon may be used. Further, as the photoelectric conversion element, not only a MIS type photodiode but also a PIN type photodiode, for example, may be used. Further, as the conversion element S, a direct type conversion element that directly converts radiation into electric charge may be used. A transistor having a control terminal and two main terminals may be used for the switch element T. In this embodiment, a thin film transistor (TFT) is used as the switch element T.

One electrode of the conversion element S is electrically connected to one of the two main terminals of the switch element T, and the other electrode of the conversion element S is connected to the bias power supply unit 104 via the bias wire Bs. It is electrically connected to the bias power supply 203. Among the conversion elements S arranged in the row direction (horizontal direction in the drawing), for example, in the conversion elements S11, S13, S15, one electrode is connected to the switch elements T11, T13, T15, respectively, and the other electrode is common. It is electrically connected to the bias power supply 203a via the bias wire Bsa. Further, in the conversion elements S12, S14 and S16, one electrode is commonly connected to the switch elements T12, T14 and T16, and the other electrode is connected to the bias power supply 203b via a common bias line Bsb different from the bias line Bsa. It is electrically connected.

The bias line Bsa to which the electrodes on the opposite sides of the switch elements T11, T13, and T15 of the conversion elements S11, S13, and S15 are connected, and the drive line Vg1-2 that controls the operation of the switch elements T12, 14, and 16. Capacities C11, C13, and C15 are formed between them. Similarly, the bias line Bsb to which the electrodes on the opposite sides of the switch elements T12, T14, and T16 of the conversion elements S12, S14, and S16 are connected, and the drive line Vg1-1 that controls the operation of the switch elements T11, 13, and 15. The capacitances C12, C14, and C16 are formed between the and. The capacity formed will be described later.

The control terminals of the plurality of switch elements T arranged in the row direction, for example, the switch elements T11, 13 and 15, are electrically connected to the drive line Vg1-1 of the first line in common, and the switch elements are connected to the drive circuit 214. A drive signal for controlling the conduction state of T is given via the drive line Vg1-1. The drive circuit 214 controls the switch element T of the pixel PIX via a plurality of drive lines Vg arranged along the row direction. In a plurality of switch elements T arranged along the column direction (vertical direction in the drawing), for example, switch elements T11 to T61, the other main terminal of the two main terminals is charged with the signal line Sigma1 in the first row. While the switch element T is in a conductive state, an electric signal corresponding to the electric charge of the conversion element S is output to the read circuit 102 via the signal line. The signal lines Sigma1 to Sigma6 can transmit the electric signals output from the plurality of pixels PIX to the read circuit 102 in parallel for each row.

The read circuit 102 is provided with an amplifier circuit 206 for amplifying an electric signal output in parallel from the pixel unit 101 corresponding to each signal line. The amplifier circuit 206 includes an integrator amplifier 205 that amplifies the output electric signal, a variable amplifier 204 that amplifies the electric signal output from the integrator amplifier 205, a sample hold circuit 207 that samples and holds the amplified electric signal, and a buffer amplifier. 209 is included. The integrating amplifier 205 includes an operational amplifier that amplifies and outputs an electric signal read from the pixel PIX, an integrating capacitance, and a reset switch. The integrating amplifier 205 can change the amplification factor by changing the value of the integrating capacitance. The electric signal output from the pixel PIX is input to the inverting input terminal of the integrating amplifier 205, the reference potential Vref is input from the reference power supply 103 to the forward rotation input terminal, and the amplified electric signal is output from the output terminal. To. Further, the integrated capacitance is arranged between the inverting input terminal and the output terminal of the operational amplifier. The sample hold circuit 207 is provided for each amplifier circuit 206, and is composed of a sampling switch and a sampling capacitance. Further, the reading circuit 102 includes a multiplexer 208 that sequentially outputs electric signals read in parallel from the amplifier circuit 206 and outputs them as an image signal of a series signal. The image signal Vout, which is an analog electric signal output from the buffer amplifier 209, is converted into digital image data by the A / D converter 210 and output to the control computer 120 shown in FIG.

The power supply unit 105 (omitted in FIG. 2) transforms the power from the battery and the outside into each power supply, and supplies power to the reference power supply 103, the bias power supply unit 104, and the like of the amplifier circuit shown in FIG. The reference power supply 103 supplies a reference voltage Vref to the forward rotation input terminal of the operational amplifier.

The bias power supplies 203a and 203b of the bias power supply unit 104 commonly supply the bias potentials Vsa and Vsb to the conversion element S via the bias lines Bsa and Bsb, respectively. Further, the bias power supplies 203a and 203b of the bias power supply unit 104 output current information including time variation of the amount of current flowing through the bias lines Bsa and Bsb to the detection unit 106. In the present embodiment, the bias power supplies 203a and 203b include a current-voltage conversion circuit 215 including an operational amplifier and a resistor as a circuit for outputting current information, but the circuit is not limited to this configuration. For example, the bias power supplies 203a and 203b may include a current-voltage conversion circuit using a shunt resistor. Further, the bias power supplies 203a and 203b may further include an A / D conversion circuit that converts the output voltage of the current-voltage conversion circuit into a digital value, and output current information as a digital value. Further, the bias power supplies 203a and 203b may output an appropriate physical quantity corresponding to the amount of current supplied (flowed) to the bias line Bs to the detection unit 106.

The drive circuit 214 has a conduction voltage Vcom and non-conduction (off) that bring the switch element T into a conduction (on) state in response to the control signals D-CLK, OE, and DIO input from the control unit 107 shown in FIG. A drive signal including the non-conducting voltage Vss to be in the state is output to each drive line. As a result, the drive circuit 214 controls the on / off of the switch element T and drives the pixel unit 101. The control signal D-CLK is a shift clock of the 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 end of the shift register. The required driving time and scanning direction are set by the above control signals.

Further, the control unit 107 controls the operation of each component of the read circuit 102 by giving the control signals RC, SH, and CLK to the read circuit 102. Here, the control signal RC controls the operation of the reset switch of the integrating amplifier 205. The control signal SH controls the operation of the sample hold circuit 207. The control signal CLK controls the operation of the multiplexer 208.

In the present embodiment, the pixel PIX arranged in the pixel unit 101 includes a pixel group in which the bias potential Vsa is supplied from the bias power supply 203a to the conversion element S, and a bias potential Vsb supplied from the bias power supply 203b to the conversion element S. It includes a pixel group. That is, two pixel groups each composed of a pixel PIX including a conversion element S that converts radiation into electric charges and a switch element T that connects the conversion element S to the column signal line Sigma are arranged in the pixel unit 101. The bias power supply 203a supplies the bias potential Vsa to the pixel group including the pixel PIX including the conversion elements S11, S13, and S15 via the bias line Bsa. Further, the bias power supply 203b supplies the bias potential Vsb to the pixel group including the pixel PIX including the conversion elements S12, S14, and S16 via the bias line Bsb. Further, the switch elements T of different pixel groups are connected to different drive lines Vg. For example, the switch elements T11, T13, and T15 are connected to the drive line Vg1-1, and the switch elements T12, T14, and T16 are connected to the drive line Vg1-2. Therefore, in the present embodiment, the pixel unit 101 has a configuration capable of driving the pixel PIX for each pixel group connected to different bias power supplies 203. In the present embodiment, the switch element T of the pixel PIX to which the bias potential is supplied from the bias power supply 203a via the bias line Bsa is connected to the drive line Vgn − “1”. Further, the switch element T of the pixel PIX to which the bias potential is supplied from the bias power supply 203b via the bias line Bsb is connected to the drive line Vgn− “2”.

Further, in the configuration shown in FIG. 2, the pixel PIX of the pixel group including the pixel PIX including the conversion elements S11, S13, and S15 and the conversion elements S12, S14, and S16 are provided in the row direction intersecting the column signal line Sigma. Pixels PIX of a pixel group including pixel PIX are arranged alternately. At this time, in the column direction in which the column signal line Sigma extends, the pixels included in the pixel group including the pixel PIX including the conversion elements S11, S13, S15 or the pixel group including the pixel PIX including the conversion elements S12, S14, S16. PIX may be arranged continuously. Further, in the column direction as well, the pixel PIXs arranged in different pixel groups may be arranged alternately.

FIG. 3 is a flow chart showing an operation example of the radiation imaging device 100 according to the present 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 the radiation image, first, in S301, the detection unit 106 acquires radiation information from the current information flowing through the bias line Bs acquired from the bias power supply unit 104, and obtains radiation information. Determine the start of irradiation. More specifically, the detection unit 106 detects the presence or absence of radiation irradiation based on the difference between the signal value indicating the current flowing through the bias line Bsa and the signal value indicating the current flowing through the bias line Bsb. The determination of the start of irradiation is performed when the amount of charge accumulated in the conversion element S of the pixel PIX is obtained from the radiation information and the radiation intensity obtained from the amount of charge exceeds a predetermined threshold value. A method of determining that the irradiation of radiation has started may be used. When the detection unit 106 determines that the irradiation of radiation has not been started (NO in S301), the radiation imaging device 100 transitions to S302, and the control unit 107 tells the drive circuit 214 that the pixel PIX is converted by a dark current. A reset drive (hereinafter, may be referred to as blank reading) for removing the charge accumulated in S is performed. The blank reading is performed in order from the first line (drive line Vg1-1) to the last line (drive line Vg6-2), and when the last line is reached, the process returns to the first line.

When the detection unit 106 determines that the irradiation of radiation has started (YES in S301), the radiation imaging device 100 transitions to S303, and the control unit 107 determines the end of irradiation of radiation. As a determination of the end of the irradiation of radiation, a method of determining that the irradiation of radiation has been completed may be used when a predetermined time has elapsed after the start of irradiation of radiation is determined. Further, the control unit 107 acquires the amount of electric charge accumulated in the conversion element S of the pixel PIX from the radiation information acquired by the detection unit 106, and the radiation intensity obtained from the amount of electric charge falls below a predetermined threshold value. In some cases, the end of radiation may be determined. When the end of radiation irradiation is not determined (NO in S303), in S304, the drive circuit 214 causes the switch element T of the pixel PIX for acquiring the radiation image to be in a non-conducting state, and from the radiation. The drive for accumulating the converted signal (hereinafter, may be referred to as accumulation) is performed. When the end of radiation irradiation is determined (YES in S303), the radiation imaging device 100 transitions to S305, and the drive circuit 214 and the read circuit 102 are driven to read out the electric charge generated in the conversion element T of the pixel PIX (hereinafter,). , May be referred to as book reading.) The main reading can be performed in order from the first line (drive line Vg1-1) to the last line (drive line Vg6-2) of the pixel PIX arranged in the pixel unit 101. When the main reading reaches the last line, a series of imaging operations ends.

FIG. 4 is a schematic view of the drive timing of the radiation imaging device 100. The control unit 107 drives the switch element S to conduct in order from the first line (drive line Vg1-1) to the last line (drive line VgY-2) of the pixel unit 101 until the irradiation of radiation is started (drive line Vg1-1). (Blank reading) is repeatedly performed by the drive circuit 214. In the configuration shown in FIG. 2, an example in which the pixel unit 101 includes 6 rows of pixel rows is shown, but in FIG. 4, it is described as having Y rows of pixel rows. If the blank reading reaches the last line until the irradiation of radiation is started, the blank reading is repeated by returning to the first line.

When the detection unit 106 detects (determines) the start of irradiation of radiation, the control unit 107 transmits the switch element T in the row to which all the pixels PIX for acquiring the radiation image are connected via the drive circuit 214. Shift to drive (accumulation) to turn off. Here, in the radiation imaging apparatus 100, the pixel row that determines the start of irradiation of radiation will be described as row Ys-1 (drive line VgYs-1). Details of the determination of the presence or absence of radiation will be described later. Accumulation continues until it is determined that the irradiation of radiation is complete. When the irradiation of radiation is completed, the control unit 107 controls the drive circuit 214 and the read circuit 102, sequentially conducts the switch element T from the first row to the last row, and performs a main reading to read a signal from the pixel PIX.

Next, the currents flowing through the bias lines Bsa and Bsb when detecting the presence or absence of radiation irradiation and determining the start of radiation irradiation will be described. First, when a voltage for turning on (conducting) the switch element T is applied to the drive line Vgn-1 (n is an integer of 1 to Y), between the drive line Vgn-1 and the bias line Bsa at that timing. A current flows through the bias wiring Bsa via the parasitic capacitance existing in the pixel PIX (for example, the pixel including the switch element T13). For example, as the parasitic capacitance, the capacitance between the control electrode and the main electrode of the switch element T can be mentioned. When this parasitic capacitance is charged, no current flows. In FIG. 4, the current caused by the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa is shown as spike-like noise in the positive direction of the bias line Bsa. Next, when a voltage for turning off (non-conducting) the switch element T is applied to the drive line Vgn-1, the parasitic capacitance existing in the pixel PIX between the drive line Vgn-1 and the bias line Bsa at that timing. A current flows through the bias wiring Bsa. When this parasitic capacitance is charged, no current flows. In FIG. 4, the current caused by the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa is shown as spike-like noise in the negative direction of the bias line Bsa. The same applies to the drive line Vgn-2. When a voltage for turning on (conducting) the switch element T is applied to the drive line Vgn-2, a pixel between the drive line Vgn-2 and the bias line Bsb is applied at that timing. A current flows through the bias wiring Bsb via the parasitic capacitance existing in the PIX (for example, the pixel including the switch element T14). In FIG. 4, the current due to the parasitic capacitance between the drive line Vgn-2 and the bias line Bsb is shown as spike-like noise in the positive direction of the bias line Bsb. Next, when a voltage for turning off (non-conducting) the switch element T is applied to the drive line Vgn-2, the parasitic capacitance existing in the pixel PIX between the drive line Vgn-2 and the bias line Bsb at that timing. A current flows through the bias wiring Bsa. In FIG. 4, the current due to the parasitic capacitance between the drive line Vgn-2 and the bias line Bsb is shown as spike-like noise in the negative direction of the bias line Bsb.

The drive line Vgn-1 and the bias line Bsb are not connected via a pixel PIX (for example, a pixel including the switch element T14). However, when a voltage for turning on (conducting) the switch element T is applied to the drive line Vgn-2, at that timing, the bias wiring Bsa and the drive line Vgn-described with reference to FIG. 2 are applied to the bias wiring Bsa. A current starts to flow through the capacitance C (for example, the capacitance C13) formed between the two. When this capacity C is charged, no current flows. In FIG. 4, the current caused by the capacitance C formed between the drive line Vgn-2 and the bias line Bsa is shown as spike-like noise of a broken line in the positive direction of the bias line Bsa. Similarly, when a voltage for turning off (non-conducting) the switch element T is applied to the drive line Vgn-2, a capacitance C formed between the bias wiring Bsa and the drive line Vgn-2 is applied at that timing. A current starts to flow through the bias wiring Bsa. When this capacity C is charged, no current flows. In FIG. 4, the current caused by the capacitance C formed between the drive line Vgn-2 and the bias line Bsa is shown as spike-like noise of a broken line in the negative direction of the bias line Bsa. The same applies to the current flowing through the bias line Bsb due to the capacitance C (for example, the capacitance C14) formed between the drive line Vgn-1 and the bias line Bsb.

In the present embodiment, as shown in FIG. 4, the drive circuit 214 turns on the switch element T of the pixel PIX included in the different pixel groups at different timings. Here, turning on the switch element T is an operation from applying a voltage for turning on the switch element T to the drive line Vg to applying a voltage for turning off the switch element T to the drive line Vg. Therefore, as compared with the case where one system of bias lines is used as in Patent Document 1, the influence of the parasitic capacitance between the drive lines Vg and the bias lines Bs in one blank reading drive becomes smaller. That is, the current flowing through the bias line Bs is reduced due to the parasitic capacitance. As a result, the noise when switching the switch element T on and off with respect to the current flowing through the bias line Bs due to the irradiation of radiation becomes relatively small, and the influence of noise is suppressed as compared with the structure shown in Patent Document 1. it can. As a result, the detection unit 106 improves the accuracy of detecting the presence or absence of irradiation based on the difference between the signal value indicating the current flowing through the bias line Bsa and the signal value indicating the current flowing through the bias line Bsb. Can be done.

Furthermore, the inventors have found the following characteristics regarding the current of noise caused by the parasitic capacitance or the capacitance formed between the drive line Vg and the bias line Bs, and the current due to irradiation of radiation. The amount of noise current is the parasitic capacitance between the drive line Vg and the bias line Bs connected via the switch element T, or the drive line Vg and the bias line Bs not connected via the switch element T. It is proportional to the capacitance C formed between them (I = dQ / dt = C · dV / dt). Therefore, by adjusting the parasitic capacitance and the formed capacitance C equivalently, when the switch element T is turned on or off on the drive line Vg, the current of noise that is in phase with the bias line Bsa and the bias line Bsb is equivalent. Will be able to flow. Further, by taking the difference between the currents flowing through the bias line Bsa and the bias line Bsb, it is possible to cancel and suppress the noise current. At this time, by turning on the switch elements T connected to different pixel groups at different timings as described above, the current flowing through the bias lines Bsa and Bs2 due to the irradiation of radiation is shown in FIG. Not counteracted as shown in. That is, by equalizing the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa and the capacitance C formed between the drive line Vgn-1 and the bias line Bsb, further irradiation of radiation is performed. It is possible to improve the accuracy of detecting the presence or absence. For example, the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa is 70% or more and 130% or less of the capacitance C formed between the drive line Vgn-1 and the bias line Bsb. Each pixel PIX may be designed. Further, for example, each pixel PIX so that the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa is the same as the capacitance C formed between the drive line Vgn-1 and the bias line Bsb. May be designed.

Here, the signal value indicating the current flowing through the bias line Bsa and the signal value indicating the current flowing through the bias line Bsb are analog values, and the detection unit 106 detects based on the difference between the analog values of the respective signal values. The unit 106 may determine the presence or absence of irradiation. At this time, the detection unit 106 may acquire the difference as an analog value, or may acquire the difference between the analog values as an analog / digitally converted digital value. By performing the difference processing between the signal value indicating the current flowing through the bias line Bsa and the signal value indicating the current flowing through the bias line Bsb as analog values, it becomes easier to cancel the noise current than by sampling at predetermined intervals.

The capacitance C formed between the drive line Vg and the bias line Bs not connected via the switch element T will be described in detail with reference to FIGS. 5 (a) and 5 (b). FIG. 5A shows a plan view of eight pixels PIX for two rows and four columns of the pixel unit 101. 5 (b) is a cross-sectional view between A and A'shown in FIG. 5 (a).

As shown in FIG. 5A, the signal lines Sigma2m, Sigma2m + 1, Sigma2m + 2, Sigma2m + 3, ... Are provided corresponding to each of the rows 2m, 2m + 1, 2m + 2, 2m + 3, .... Bias lines Bsa and Bsb are also provided corresponding to the rows 2m, 2m + 1, 2m + 2, 2m + 3, ....

In the configuration shown in FIG. 5B, the substrate 400 on which the pixel PIX is provided is an insulating substrate such as glass or plastic. The switch element T is formed on the main surface of the substrate 400 and includes a control electrode 401, a main electrode 402, a main electrode 403, and an insulating layer 404. The control electrode 401 and the drive line Vg may be integrally formed of a common conductor such as a metal. Similarly, the main electrode 402 and the signal line Sigma may be integrally formed of a common conductor such as a metal. The insulating layer 404 functions as a gate insulating film of the switch element T. The switch element T may have a light-shielding layer (not shown). The conversion element S includes a lower electrode 411 arranged on the main surface of the substrate 400, a semiconductor layer 412 arranged on the lower electrode 411, and an upper electrode 414 arranged on the semiconductor layer 412. The semiconductor layer 412 is a stack of an impurity semiconductor layer 4121, an intrinsic semiconductor layer 4122, and an impurity semiconductor layer 4123 in this order. In the present embodiment, the main electrode 403 of the switch element T and the lower electrode 411 of the conversion element S are integrally formed of a common conductor such as a metal, but may be made of another conductive material.

The switch element T and the conversion element S are covered with an insulating layer 420. The switch element T and the conversion element S may be further covered with the flattening layer 4200. Bias lines Bs are provided on the insulating layer 420 and the flattening layer 4200. An opening 450 is provided in a part of the insulating layer 420 and the flattening layer 4200 on the upper electrode 414 of the conversion element S, and the conductive layer 430 electrically connects the bias wire Bs and the upper electrode 414 through the opening 450. .. The bias wire Bs may be formed of a conductive material such as metal, and the conductive layer 430 may be formed of a transparent conductive material such as ITO. The protective layer 440 covers the entire configuration described above. The insulating layer 404, the insulating layer 420, and the protective layer 440 can be formed of an inorganic insulating film such as silicon nitride. The flattening layer 4200 can be formed of a material having a low relative permittivity (ε / ε _{0 = 2 to 5) such as photosensitive acrylic and polyimide.} Further, on the protective layer 440, a scintillator (not shown) that converts radiation into light having a wavelength that can be detected by a PIN-type photodiode that functions as a conversion element 202 is provided.

In FIG. 5A, attention is paid to the drive line Vgn-1 passing through the nth row, the 2mth column, and the nth row, the 2m + 1st column. The drive line Vgn-1 connected to the pixel PIX including the conversion element S to which the bias potential is supplied by the bias line Bsa is relative to the bias lines Bsa, Bsb and the lower electrode 411 of the conversion element S.
(1) Intersection 461 with bias line Bsa
(2) Intersection 462 with bias line Bsb
(3) The overlapping portion 464 with the lower electrode 411 of the conversion element S of the pixel PIX to which the bias potential is supplied by the bias line Bsb.
Have. Further, in the configuration shown in FIG. 5A, in the normal projection on the main surface of the substrate 400, the portion of the drive line Vgn-1 extending in the row direction is a pixel to which the bias potential is supplied by the bias line Bsa. It does not overlap with the lower electrode 411 of the pixel included in the pixel group composed of PIX. However,
(4) Overlapping portion 463 with the lower electrode 411 of the conversion element S of the pixel PIX to which the bias potential is supplied by the bias line Bsa.
May have. Similarly, the drive line Vgn-2 connected to the pixel PIX including the conversion element S to which the bias potential is supplied by the bias line Bsb
(5) Intersection with bias line Bsb (6) Intersection with bias line Bsa (7) Having an overlap with the lower electrode 411 of the conversion element S of the pixel PIX to which the bias potential is supplied by the bias line Bsa. ,Also,
(8) It may have an overlapping portion with the lower electrode 411 of the conversion element S of the pixel PIX to which the bias potential is supplied by the bias line Bsb.

The drive line Vg is arranged so as to be adjacent to each other via an insulating layer 404 between the layer on the substrate 400 side of the lower electrode 411 of the conversion element S and when the drive line Vg and the lower electrode 411 overlap each other. Therefore, in the above-mentioned (1) to (4), (1) and (4) contribute to the capacitive coupling component between the drive line Vgn-1 and the bias line Bsa. That is, it contributes to the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa. Further, (2) and (3) contribute to the capacitive coupling component between the drive line Vgn-1 and the bias line Bsb, that is, the capacitance C formed between the drive line Vgn-1 and the bias line Bsb described above. To do. The areas and shapes of the intersecting portions 461 and 462 and the overlapping portions 463 and 464, and the film thickness of the constituent material are adjusted. Thereby, it is possible to adjust the capacitance value of each of the parasitic capacitance and the capacitance formed between the drive line Vgn-1 and the bias line Bsb which are not connected via the switch element T.

In the present embodiment, it is assumed that (1) and (2), and (3) and (4) have the same layer structure, respectively. By designing (1) and (2) so that the areas of (1) and (2) are substantially equal to each other, the capacitance values generated in (1) and (2) are also substantially equivalent to each other. It becomes. On the other hand, (3) and (4) are designed so that the area of (3) is larger than the area of (4). That is, in the normal projection on the main surface, the area of the portion (overlapping portion 462) of the drive line Vgn-1 that overlaps with the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsb is driven. It is designed to be larger than the area of the portion (overlapping portion 463) of the line Vgn-1 that overlaps with the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsa. At this time, the capacity value generated in (3) becomes larger than the capacity value generated in (4). As a result, the value of the capacitance C formed between the drive line Vgn-1 and the bias line Bsb can be brought close to the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa.

The same applies to (5) to (8). By designing so that the areas of (5) and (6) are substantially equal to each other, the capacitance values generated in (5) and (6) are also substantially equivalent to each other. On the other hand, (7) and (8) are designed so that the area of (7) is larger than the area of (8). That is, in the normal projection on the main surface, the area of the portion of the drive line Vgn-2 that overlaps with the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsa is the drive line Vgn-2. Of these, the area is designed to be larger than the area of the portion overlapping the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsb. At this time, the capacitance value generated in (7) becomes larger than the capacitance value generated in (8). As a result, the value of the capacitance C formed between the drive line Vgn-2 and the bias line Bsa can be brought close to the parasitic capacitance between the drive line Vgn-2 and the bias line Bsb. In this way, it is possible to adjust the values of the above-mentioned capacitances C11 to C66.

Not limited to the above, in general, "the sum of the capacity generated in (1) and the capacity generated in (4)" is less than "the capacity generated in (2) and the capacity generated in (3)", and "(5) The effect of the present disclosure can be obtained by designing so that "the sum of the capacity generated in (8) and the capacity generated in (8)" is less than "the capacity generated in (6) and the capacity generated in (7)". For example, the area of (3) and the area of (4) may be made substantially equal to each other, and the area of (1) may be made smaller than the area of (2).

Thereby, when the difference between the currents flowing through the bias line Bsa and the bias line Bsb is taken, the noise generated when the switch element T is turned on or off can be effectively suppressed. As a result, the detection unit 106 can improve the accuracy when detecting the presence or absence of radiation irradiation.

When the detection unit 106 detects the start of radiation irradiation, the control unit 107 causes all the switch elements T to be in a non-conducting state, and stores the radiation signal in the pixel PIX. After that, the control unit 107 performs the main reading according to the completion of the irradiation of radiation. In the configuration shown in FIG. 2, two drive lines Vgn-1 and Vgn-2 for two pixel groups are connected to the pixels PIX arranged in the row direction. Here, in the circuit diagram shown in Patent Document 1, there are Y drive lines Vg, whereas in the present embodiment, there are 2 Y drive lines Vg. Therefore, if the switch element T is sequentially conducted from the first row to the last row and the main reading is performed, if the drive cycle time is the same as that of Patent Document 1, it takes twice as long to read the signals of all the rows. .. Therefore, as shown in FIG. 4, the control unit 107 controls the drive circuit 214 so that the drive lines Vg for two lines are conducted together during the main reading, and the main reading time due to the increase in the drive line Vg is increased. The increase may be suppressed. Specifically, as shown in FIG. 2, the signal line Sigma is shared by the pixels arranged in each row among the plurality of pixel PIXs. Therefore, when acquiring the radiographic image data, the drive circuit 214 suppresses an increase in the main reading time by, for example, simultaneously turning on the switch element T connected to the drive line Vg1-1 and the drive line Vg1-2. It becomes possible to do.

In the present embodiment, by using the two bias lines Bsa and Bsb, the current flowing through the bias line Bs when the switch element T due to the parasitic capacitance existing between the drive line Vg and the bias line Bs is turned on or off is generated. Suppress. Further, the capacitance formed between the drive line Vg and the bias line Bs not connected via the switch element T is parasitic on the drive line Vg and the bias line Bs connected via the switch element T. Get closer to capacity. This makes it possible to reduce erroneous detection and detection delay of radiation due to the current of noise generated during "blank reading drive".

Here, for example, the difference in the number of pixel PIXs included in each pixel group may be within 10% for each pixel group. That is, the number of pixel PIXs connected to the bias line Bsa may be 90% or more and 110% or less of the number of pixel PIXs connected to the bias line Bsb. Further, for example, the number of pixel PIXs included in each pixel group may be the same. By aligning the number of pixel PIXs included in the pixel group, the amount of noise current flowing through the bias line Bs can be aligned, and the influence of noise when the detection unit 106 detects the presence or absence of radiation irradiation can be suppressed.

Second Embodiment The radiation imaging apparatus in this embodiment will be described with reference to FIGS. 6 to 9. FIG. 6 is an equivalent circuit diagram showing a configuration example of the imaging unit 110 of the radiation imaging apparatus 100 according to the second embodiment. The configuration of the imaging unit 110 of the present embodiment is different from the configuration of the pixel unit 101 and the configuration of the amplifier circuit 206 of the reading circuit 102 as compared with the configuration shown in FIG. Specifically, two pixel PIXs that are adjacent to each other in the row direction intersecting the column signal line Sig among the pixel PIXs and whose switch element T is controlled by different drive lines among the plurality of drive lines Vg are signals. The line Sigma is shared. At this time, as shown in FIG. 6, one of the two pixel PIXs adjacent to each other is included in the pixel group to which the bias potential is supplied via the bias line Bsa, and the other is included in the pixel group to which the bias potential is supplied via the bias line Bsb. The bias potential may be included in the supplied pixel group. By sharing the column signal line Sigma between two pixels PIX adjacent to each other in the row direction, the number of signal line sig is halved as compared with the configuration shown in FIG. Along with this, the number of amplifier circuits 206 arranged in the read circuit 102 is halved as compared with the configuration shown in FIG. As a result, in the configuration shown in FIG. 2, the amplifier circuit 206 of the read circuit 102 can be reduced to solve the problem that the scale of the drive circuit 214 increases as compared with the configuration of Patent Document 1. As a result, it is possible to suppress an increase in cost due to an increase in the number of ICs in the entire radiation imaging device 100 including the drive circuit 214 and the read circuit 102, and to reduce the wiring in the pixel unit 101. The configuration of the radiation imaging apparatus 100 other than this may be the same as that of the first embodiment described above, and the description thereof will be omitted here.

FIG. 7 is a schematic view of the drive timing of the radiation imaging device 100 according to the present embodiment. The drive for detecting the presence or absence of irradiation of radiation during blank reading may be the same as the drive described with reference to FIG. Therefore, as in the first embodiment described above, it is possible to suppress the influence of parasitic capacitance and improve the accuracy of detecting the presence or absence of radiation. Further, in the present embodiment, since two pixel PIXs adjacent to each other are connected to the same signal line Sigma, as described above, turning on the switch element T together in two lines in the main reading drive is read. This is not possible because the signals for the two pixels are added. Therefore, as shown in FIG. 9, when acquiring the radiographic image data, the drive circuit 214 turns on the switch element T of the pixel PIX connected to the same signal line Sigma at different timings. As a result, the electric charge accumulated in each pixel PIX can be read out.

FIG. 8 is a plan view of the pixel PIX in the present embodiment. Further, the cross-sectional view between A and A'shown in FIG. 8 may be the same as that in FIG. 5 (b). In the present embodiment, the pixels PIX adjacent to each other share the column signal line Sigma. For example, the row signal line Sigma 2m and the row signal line Sigma 2m + 1 in FIG. 5A described above are replaced with a common row signal line Sigma. As a result, the number of amplifier circuits 206 can be suppressed as compared with the first embodiment, the number of column signal lines Sigma arranged in the pixel unit 101 can be reduced, and the cost increase can be suppressed. Between the capacitance C formed between the drive line Vg not connected via the switch element T and the bias line Bs, and between the drive line Vg connected via the switch element T and the bias line Bs. The method of adjusting the parasitic capacitance of the above may be the same as that described with reference to FIGS. 5 (a) and 5 (b) described above.

Next, using FIGS. 9A and 9B, the capacitance C formed between the drive line Vg and the bias line Bs not connected via the switch element T and the switch element Another example of how to adjust the parasitic capacitance between the drive line Vg and the bias line Bs connected via T will be described. 9 (a) is a plan view of the pixel PIX, and FIG. 9 (b) is a cross-sectional view between A and A'shown in FIG. 9 (a). In the configuration shown in FIG. 9B, the structure of the switch element T is almost the same as that of the switch element T shown in FIG. 5B described above, but an opening provided in a part of the main electrode 403. Except for 450, it differs in that it is covered by an insulating layer 4201 and a flattening layer 4202. The insulating layer 4201 may be formed of an inorganic insulating film such as silicon nitride. The flattening layer 4202 may be formed of photosensitive acrylic, polyimide, or the like. The lower electrode 411 of the conversion element S is formed on the flattening layer 4202. The lower electrode 411 is formed of a conductor different from the main electrode 403 of the switch element T. The lower electrode 411 and the main electrode 403 are electrically connected to each other through the opening 450. Bias lines Bs are provided on the upper electrode 414 along the row direction in which the row signal line Sigma extends. A flattening layer 4204 is provided between the bias line Bs and the upper electrode 414 except for the portion of the opening 451. The bias wire Bs and the upper electrode 414 are electrically connected to each other through an opening 451 provided in a part of the flattening layer 4204. The protective layer 440 covers the entire configuration described above.

In FIG. 9A, attention is paid to the drive line Vgn-1 passing through the nth row, the 2mth column, and the nth row, the 2m + 1st column. The drive line Vgn-1 connected to the pixel PIX including the conversion element S to which the bias potential is supplied by the bias line Bsa is directed to the lower electrode 411 of the conversion element S with respect to the lower electrode 411 of the conversion element S.
(9) The overlapping portion 468 with the lower electrode 411 of the conversion element S of the pixel PIX to which the bias potential is supplied by the bias line Bsa.
(10) Overlapping portion 469 with the lower electrode 411 of the conversion element S of the pixel PIX to which the bias potential is supplied by the bias line Bsb.
Have. Similarly, the drive line Vgn-2 connected to the pixel PIX including the conversion element S to which the bias potential is supplied by the bias line Bsb
(11) Overlapping portion with the lower electrode 411 of the conversion element S of the pixel PIX to which the bias potential is supplied by the bias line Bsb (12) (The lower electrode of the conversion element S of the pixel PIX to which the bias potential is supplied by the bias line Bsa) It has an overlapping portion with 411.

In (9) to (12) described above, (9) and (12) contribute to the capacitive coupling component between the drive line Vgn-1 and the bias line Bsa. That is, it contributes to the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa. Further, (10) and (11) contribute to the capacitive coupling component between the drive line Vgn-1 and the bias line Bsb, that is, the capacitance C formed between the drive line Vgn-1 and the bias line Bsb described above. To do. The area and shape of these overlapping portions 468 and 469 and the film thickness of the constituent material are adjusted. Thereby, it is possible to adjust the capacitance value of each of the parasitic capacitance and the capacitance formed between the drive line Vgn-1 and the bias line Bsb which are not connected via the switch element T.

In the present embodiment, it is assumed that (9) to (12) each have the same layer structure. In this case, in the normal projection on the main surface, the area of the portion (overlapping portion 469) of the drive line Vgn-1 that overlaps with the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsb is determined. It is designed to be larger than the area of the portion (overlapping portion 468) of the drive line Vgn-1 that overlaps with the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsa. This makes it possible to bring the value of the capacitance C formed between the drive line Vgn-1 and the bias line Bsb close to the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa. For example, as shown in FIG. 9A, in the normal projection on the main surface of the substrate 400, a pixel extending in the row direction of the drive line Vgn-1 and to which the bias potential is supplied by the bias line Bsb. The portion of the drive line Vgn-1 that overlaps the lower electrode 411 of the pixel PIX included in the group extends in the row direction, and the lower portion of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsa. It may include a portion wider than the portion overlapping the electrode 411. Similarly, for the drive line Vgn-2, the area of the drive line Vgn-2 that overlaps with the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsa in the normal projection on the main surface. Is designed to be larger than the area of the portion of the drive line Vgn-2 that overlaps with the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsb. For example, as shown in FIG. 9A, in the normal projection on the main surface of the substrate 400, a pixel extending in the row direction of the drive line Vgn-2 and to which the bias potential is supplied by the bias line Bsa. The portion of the drive line Vgn-2 that overlaps the lower electrode 411 of the pixel PIX included in the group extends in the row direction, and the lower portion of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsb. It may include a portion wider than the portion overlapping the electrode 411. In this way, it is possible to adjust the values of the above-mentioned capacitances C11 to C66.

Thereby, when the difference between the currents flowing through the bias line Bsa and the bias line Bsb is taken, the noise generated when the switch element T is turned on or off can be effectively suppressed. As a result, the detection unit 106 can improve the accuracy when detecting the presence or absence of radiation irradiation. Further, in the present embodiment, the number of the amplifier circuits 206 arranged in the read circuit 102 can be suppressed as compared with the first embodiment described above. As a result, the cost increase of the radiation imaging apparatus 100 can be suppressed, the wiring pattern of the pixel portion 101 can be reduced, and the pixel aperture ratio can be increased.

Third Embodiment The radiation imaging apparatus according to this embodiment will be described with reference to FIGS. 10 to 12. FIG. 10 is an equivalent circuit diagram showing a configuration example of the imaging unit 110 of the radiation imaging apparatus 100 according to the third embodiment. The configuration of the imaging unit 110 of the present embodiment is different from the configuration of the pixel unit 101 as compared with the configuration shown in FIG. In the configuration shown in FIG. 2, in the row direction, the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsa and the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsb alternate. It was arranged in. On the other hand, in the configuration shown in FIG. 10, the pixel group to which the bias potential is supplied by the bias line Bsa or the pixel group to which the bias potential is supplied by the bias line Bsb is included in the row direction intersecting the column signal line Sigma. Pixels are arranged consecutively. Further, the switch elements T of the pixels PIX arranged in the row direction are driven by the same drive line Vg. Further, in the column direction in which the column signal line Sigma extends, the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsa and the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsb. Are arranged alternately. By wiring in this way, the number of column signal lines Sigma is equal to that of the first embodiment, and the number of drive lines Vg is halved. Further, as compared with the second embodiment, the number of row signal line Sigmas is doubled, but the number of drive lines Vg is halved, and the total number of wirings is substantially the same.

FIG. 11 is a schematic view of the drive timing of the radiation imaging device 100 according to the present embodiment. The drive for detecting the presence or absence of irradiation of radiation during blank reading may be the same as the drive described with reference to FIG. Therefore, as in the first embodiment described above, it is possible to suppress the influence of parasitic capacitance and improve the accuracy of detecting the presence or absence of radiation. Further, in the present embodiment, since the number of drive lines is halved, the time required for the main reading causes the two drive line Vg switch elements T of the first embodiment shown in FIG. 4 to be turned on at the same time. Equivalent to drive. Further, the time required for the main reading is halved with respect to the driving of the second embodiment shown in FIG. 7 described above.

Next, using FIGS. 12 (a) to 12 (c), the capacitance C formed between the drive line Vg and the bias line Bs, which are not connected via the switch element T, and the switch element. An example of a method of adjusting the parasitic capacitance between the drive line Vg and the bias line Bs connected via T will be described. 12 (a) is a plan view of the pixel PIX, FIG. 12 (b) is a sectional view between A and A'shown in FIG. 12 (a), and FIG. 12 (c) is shown in FIG. 12 (a). It is sectional drawing between BB'shown.

As shown in FIG. 12A, in the normal projection on the main surface of the substrate 400, the bias lines Bsa and Bsb are in the row direction in which the row signal line Sigma extends between the conversion elements S of the adjacent pixels PIX. It is provided along. The layer structure and cross-sectional structure are almost the same as those of the second embodiment shown in FIG. 9B described above, but the conductive layer connecting the bias line Bsa on the n-1 line and the upper electrode 414 of the conversion element S. The 430 is arranged so as to extend from the bias line Bsa on both sides in the row direction, and is connected to the upper electrode 414 via an opening 451 respectively. Similarly, the conductive layer 430 on the nth row is arranged so as to extend from the bias line Bsb on both sides in the row direction, and is connected to the upper electrode 414 of the conversion element S via an opening 451. As described above, in the odd-numbered rows / even-numbered rows, the upper electrode 414 of the photodiode has a structure in which the bias lines Bsa and Bsb are alternately connected.

Further, the drive line Vgn that controls the switch element T of the pixel PIX in the nth row extends in the row direction mainly under the lower electrode 411 of the pixel PIX in the n-1th row, not in the nth row. It extends from the portion extending in the direction to the switch element T in the nth row so as to project in the column direction. In FIG. 12A, paying attention to the drive line Vgn connected to the pixel PIX including the conversion element S to which the bias potential is supplied by the bias line Bsb.
(13) The overlapping portion 471 of the pixel PIX (pixel in the n-1th row) to which the bias potential is supplied by the bias line Bsa with the lower electrode 411 of the conversion element S.
(14) The overlapping portion 472 of the pixel PIX (pixel in the nth row) to which the bias potential is supplied by the bias line Bsb with the lower electrode 411 of the conversion element S.
Have. Similarly, for the drive line Vgn + 1, (15) the overlapping portion 473 of the pixel PIX (pixel in the nth row) to which the bias potential is supplied by the bias line Bsb with the lower electrode 411 of the conversion element S.
(16) The overlapping portion 474 of the pixel PIX (pixel in the n + 1th row) to which the bias potential is supplied by the bias line Bsa with the lower electrode 411 of the conversion element S.
Have.

In (13) and (14) described above, (13) contributes to the capacitive coupling component between the drive line Vgn and the bias line Bsa. That is, it contributes to the capacitance C formed between the drive line Vgn and the bias line Bsa described above. Further, (14) contributes to a capacitive coupling component between the drive line Vgn and the bias line Bsb, that is, a parasitic capacitance formed between the drive line Vgn and the bias line Bsb. The area and shape of these overlapping portions 471 to 474 and the film thickness of the constituent material are adjusted. Thereby, it is possible to adjust the capacitance values of the parasitic capacitance and the capacitance C formed between the drive line Vgn and the bias line Bsa which are not connected via the switch element T, respectively. The same applies to (15) and (16).

In the present embodiment, it is assumed that (13) to (16) each have the same layer structure. In this case, in the normal projection on the main surface, the area of the portion (overlapping portion 471) of the drive line Vgn that overlaps with the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsa is the drive line. It is designed to be larger than the area of the portion (overlapping portion 472) of Vgn that overlaps with the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsb. This makes it possible to bring the value of the capacitance C formed between the drive line Vgn and the bias line Bsa close to the parasitic capacitance between the drive line Vgn and the bias line Bsb. Similarly, for the drive line Vgn + 1 connected to the conversion element S to which the bias potential is supplied from the bias line Bsa, in the normal projection on the main surface, the pixel group to which the bias potential is supplied by the bias line Bsb among the drive lines Vgn + 1 The area of the portion overlapping the lower electrode 411 of the included pixel PIX is larger than the area of the portion of the drive line Vgn + 1 overlapping the lower electrode 411 of the pixel PIX included in the pixel group to which the bias potential is supplied by the bias line Bsa. Design to. In this way, it is possible to adjust the values of the above-mentioned capacitances C11 to C66.

Also in this embodiment, when the difference between the currents flowing through the bias line Bsa and the bias line Bsb is taken, the noise generated when the switch element T is turned on or off can be effectively suppressed. As a result, the detection unit 106 can improve the accuracy when detecting the presence or absence of radiation irradiation. Further, since the scale of the drive circuit 214 can be reduced by halving the number of drive lines Vg as compared with the first embodiment, the cost increase of the drive circuit 214 can be suppressed, and the wiring pattern of the pixel unit 101 can be suppressed. Can be reduced and the pixel aperture ratio can be increased. Further, as compared with the second embodiment, the reading speed at the time of performing the main reading drive can be doubled.

The invention is not limited to the above embodiments, and various modifications and modifications can be made without departing from the spirit and scope of the invention. Therefore, a claim is attached to make the scope of the invention public.

100: Radiation imaging device, 106: Detection unit, 203: Bias power supply, 214: Drive circuit, Bs: Bias line, PIX: Pixel, S: Conversion element, Sigma: Column signal line, T: Switch element

Claims (17)

A first pixel group and a second pixel group each composed of a conversion element that converts radiation into an electric charge and a switch element that connects the conversion element to a column signal line, and the pixel included in the first pixel group, respectively. A first bias power supply that supplies a bias potential to the conversion element via the first bias line, and a second bias line different from the first bias line to the conversion element of the pixel included in the second pixel group. A radiation imaging device including a second bias power supply that supplies a bias potential via a device, a drive circuit that controls the switch element, and a detection unit.
The drive circuit turns on the switch element of the pixel included in the first pixel group and the switch element of the pixel included in the second pixel group at different timings.
The detection unit detects the presence or absence of radiation irradiation based on the first signal value indicating the current flowing through the first bias line and the second signal value indicating the current flowing through the second bias line. A radiation imaging device characterized by. The first signal value and the second signal value are analog values, respectively, and are
The radiation imaging apparatus according to claim 1, wherein the detection unit determines the presence or absence of irradiation of radiation based on the difference between the analog values of the first signal value and the second signal value. The conversion element includes a lower electrode arranged on the main surface of the substrate, a semiconductor layer arranged on the lower electrode, and an upper electrode arranged on the semiconductor layer.
The drive circuit controls the switch element of the pixel via a plurality of drive lines.
The plurality of drive lines include a first drive line for controlling the switch element of the pixel included in the first pixel group.
In the normal projection on the main surface, the area of the portion of the first drive line that overlaps with the lower electrode of the pixel included in the second pixel group is included in the first pixel group of the first drive line. The radiation imaging apparatus according to claim 1 or 2, wherein the area of the pixel is larger than the area of the portion overlapping the lower electrode. The first drive line controls the switch element of the pixel included in the first pixel group arranged in the row direction intersecting the column signal line.
The third aspect of the present invention is characterized in that, in the normal projection on the main surface, a portion of the first drive line extending in the row direction does not overlap with the lower electrode of the pixel included in the first pixel group. The radiation imaging device described. The first drive line controls the switch element of the pixel included in the first pixel group arranged in the row direction intersecting the column signal line.
In the normal projection on the main surface, the portion of the first drive line extending in the row direction and overlapping the lower electrode of the pixel included in the second pixel group is the first drive line. The radiation imaging apparatus according to claim 3, further comprising a portion extending in the row direction and having a width wider than a portion of the pixel included in the first pixel group that overlaps with the lower electrode. The parasitic capacitance between the first drive line and the first bias line is 70% or more and 130% or less of the capacitance formed between the first drive line and the second bias line. The radiation imaging apparatus according to any one of claims 3 to 5, which is characterized. Claims 3 to 6 are characterized in that the parasitic capacitance between the first drive line and the first bias line is the same as the capacitance formed between the first drive line and the second bias line. The radiation imaging apparatus according to any one of the above items. Two pixels of the pixels that are adjacent to each other in the row direction intersecting the column signal line and whose switch element is controlled by different drive lines among the plurality of drive lines share the column signal line. The radiation imaging device according to any one of claims 3 to 7, wherein the radiation imaging device is characterized by the above. 8. The eighth aspect of the present invention is characterized in that one of the two adjacent pixels is included in the first pixel group, and the other of the two adjacent pixels is included in the second pixel group. The radiation imaging device described. Claims 1 to 9, wherein the pixels included in the first pixel group and the pixels included in the second pixel group are alternately arranged in a row direction intersecting the column signal line. The radiation imaging apparatus according to any one item. Any one of claims 1 to 10, wherein the pixels included in the first pixel group or the second pixel group are continuously arranged in the row direction in which the row signal lines extend. The radiation imaging device according to the section. Claims 1 to 9 are characterized in that the pixels included in the first pixel group and the pixels included in the second pixel group are alternately arranged in the row direction in which the row signal lines extend. The radiation imaging apparatus according to any one of the above items. Claims 1 to 9 and 12, wherein the pixels included in the first pixel group or the second pixel group are continuously arranged in a row direction intersecting with the column signal line. The radiation imaging apparatus according to any one of the following items. The radiation according to any one of claims 1 to 13, wherein the detection unit determines the presence or absence of radiation irradiation based on the difference between the first signal value and the second signal value. Imaging device. Any of claims 1 to 14, wherein the number of the pixels connected to the first bias line is 90% or more and 110% or less of the number of pixels connected to the second bias line. The radiation imaging apparatus according to item 1. The radiation imaging device according to any one of claims 1 to 15, wherein the conversion element is a PIN type or MIS type element. The radiation imaging apparatus according to any one of claims 1 to 16.
A radiation generator that irradiates the radiation imaging device with radiation,
A radiation imaging system characterized by being equipped with.

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