JP7398931B2 - Radiation imaging devices and radiation imaging systems - Google Patents

Description

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

2. Description of the Related Art Radiation imaging devices using flat panel detectors (FPD) made of semiconductor materials are widely used in medical image diagnosis and non-destructive testing. Patent Document 1 discloses a radiation image capturing apparatus that detects the start and end of radiation irradiation from a current flowing through a bias line for applying a bias voltage to a radiation detection element. Furthermore, in Patent Document 1, in a reset process that is performed until the start of radiation irradiation is detected, noise generated when switching on and off of a switch (TFT) that releases dark charges generated in a detection element is caused by a bias line. It has been shown that the current flowing through the Patent Document 1 shows a method of suppressing the influence of noise when switching between on and off of a TFT in order to detect the start of radiation irradiation.

Japanese Patent Application Publication No. 2010-268171

Noise superimposed on the bias line when switching the TFT on and off includes a component due to parasitic capacitance between the scanning line and the bias line for controlling on or off of the TFT. Since each scanning line intersects with many bias lines, the noise generated when switching the TFT on and off increases with respect to the current flowing through the bias line due to radiation irradiation. , there is a possibility that the influence of noise cannot be sufficiently suppressed.

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

In view of the above problems, a radiation imaging device according to an embodiment of the present invention is a circuit for detecting radiation, and includes a conversion element that is capable of accumulating electric charge and includes a first electrode and a second electrode. and a plurality of pixels arranged in a matrix including a switch element that connects the conversion element to a column signal line, and a plurality of drive lines for controlling each switch element of the plurality of pixels, the plurality of drive lines for controlling each switch element of the plurality of pixels. The circuit has a multilayer structure including a plurality of drive lines extending along the row direction of the matrix and a plate-shaped base material, and the plurality of pixels are arranged in a predetermined row of the matrix and are called first pixels. a second pixel, and the plurality of drive lines include at least a first drive line connected to the switch element of the first pixel and a second drive line connected to the switch element of the second pixel. , in the orthogonal projection onto the main surface of the base material, the area of the portion of the first drive line that overlaps with the second electrode of the second pixel is the area of the portion of the first drive line that overlaps with the second electrode of the one pixel. It is characterized by being larger than the area of the overlapped part .

The above means provides an advantageous technique for detecting the presence or absence of radiation irradiation with higher accuracy.

1 is a diagram showing a configuration example of a radiation imaging system using a radiation imaging apparatus according to the present invention. FIG. 2 is a diagram showing a configuration example of the radiation imaging apparatus shown in FIG. 1. FIG. FIG. 3 is a flow diagram illustrating the operation of the radiation imaging apparatus of FIG. 2. FIG. FIG. 3 is a timing diagram illustrating the operation of the radiation imaging apparatus shown in FIG. 2. FIG. 3A and 3B are a plan view and a cross-sectional view showing an example of the configuration of a pixel of the radiation imaging apparatus shown in FIG. 2. FIG. FIG. 2 is a diagram showing a configuration example of the radiation imaging apparatus shown in FIG. 1. FIG. FIG. 7 is a timing diagram illustrating the operation of the radiation imaging apparatus shown in FIG. 6; FIG. 7 is a plan view showing an example of the configuration of pixels of the radiation imaging apparatus shown in FIG. 6; 7A and 7B are a plan view and a cross-sectional view showing a configuration example of a pixel of the radiation imaging apparatus shown in FIG. 6. FIG. FIG. 2 is a diagram showing a configuration example of the radiation imaging apparatus shown in FIG. 1. FIG. 11 is a timing diagram illustrating the operation of the radiation imaging apparatus of FIG. 10. FIG. 11A and 10B are a plan view and a cross-sectional view showing a configuration example of a pixel of the radiation imaging apparatus shown in FIG. 10.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the claimed invention. Although a plurality of features are described in the embodiments, not all of these features are essential to the invention, and the plurality of features may be arbitrarily combined. Furthermore, in the accompanying drawings, the same or similar components are designated by the same reference numerals, and redundant description will be omitted.

In addition, radiation in the present invention includes not only α-rays, β-rays, and γ-rays, which are beams produced by particles (including photons) emitted by radioactive decay, but also beams having the same or higher energy, such as X-rays. It can also include rays, particle rays, and cosmic rays.

First Embodiment A radiation imaging apparatus according to the present 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 a radiation imaging apparatus 100 according to the first embodiment. The radiation imaging system SYS of this embodiment includes a radiation imaging apparatus 100, a control computer 120, a radiation generation apparatus 130, and a radiation control apparatus 140.

The radiation generating device 130 irradiates the radiation imaging device 100 with radiation according to 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 radiation irradiated from the radiation generation device 130 to the radiation imaging device 100 via the subject.

The radiation imaging apparatus 100 includes an imaging section 110 including a pixel section 101, a readout circuit 102, a reference power supply 103, and a bias power supply section 104, a power supply section 105, a detection section 106, and a control section 107. In the pixel section 101, a plurality of pixels for detecting radiation are arranged in a two-dimensional array. The readout circuit 102 reads charge information from the pixel portion 101. A reference power supply 103 supplies a reference voltage to the readout circuit 102 . The bias power supply section 104 supplies a bias potential to a conversion element of a pixel arranged in the pixel section 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 acquires current information from the bias power supply unit 104. More specifically, the detection unit 106 acquires, from the bias power supply unit 104, information about the current flowing through the 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 current information output from the bias power supply and outputs radiation information including temporal fluctuations in the intensity of 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 using an analog circuit such as a sample and hold circuit or an operational amplifier. Further, in the configuration shown in FIG. 1, the detection unit 106 is arranged in the radiation imaging apparatus 100, but the control computer 120 may have the function of the detection unit 106. In this case, it includes the radiation imaging apparatus 100 shown in FIG. 1 and a portion of the control computer 120 that functions as the detection unit 106, and can be said to be the "radiation imaging apparatus" of this embodiment. The imaging unit 110 will be described later using FIG. 2. The control unit 107 controls the entire radiation imaging apparatus 100, such as driving the radiation imaging apparatus 100. The control unit 107 controls the imaging unit 110 using a driving method transmitted from the control computer 120 according to user settings and the like. Further, the driving method of the imaging unit 110 may be changed using the radiation information output by the detection unit 106.

FIG. 2 is an equivalent circuit diagram showing a configuration example of the imaging section 110 of the radiation imaging apparatus 100. In FIG. 2, a pixel unit 101 having 6 rows by 6 columns of pixels PIX is shown for the sake of simplicity. However, the pixel unit 101 of the actual radiation imaging device 100 may have a larger number of pixels; for example, the 17-inch radiation imaging device 100 may have approximately 2800 rows x approximately 2800 columns of pixels PIX.

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 electric charge, and a switch element T (T11 to T66) that connects the conversion element S to the column signal line Sig and outputs an electric signal according to the electric charge. ,including. In this embodiment, the conversion element S is an indirect type that includes a photoelectric conversion element and a wavelength converter on the radiation incident side of the photoelectric conversion element that converts the radiation into light in a wavelength band that can be detected by the photoelectric conversion element. It is a conversion element. As a photoelectric conversion element that converts light into charge, an MIS photodiode, which is disposed 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. Furthermore, as the conversion element S, a direct type conversion element that directly converts radiation into charges may be used. As the switch element T, a transistor having a control terminal and two main terminals may be used. 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 section 104 via the bias line Bs. It is electrically connected to the bias power supply 203. Among the conversion elements S arranged in the row direction (horizontal direction of the drawing), for example, conversion elements S11, S13, and S15 have one electrode connected to the switch elements T11, T13, and T15, respectively, and the other electrode connected to a common It is electrically connected to a bias power supply 203a via a bias line Bsa. Furthermore, one electrode of the conversion elements S12, S14, and S16 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. electrically connected.

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

A plurality of switch elements T arranged in the row direction, for example, switch elements T11, 13, 15, have their control terminals electrically connected in common to the drive line Vg1-1 in the first row, and the switch elements A drive signal for controlling the conduction state of T is applied via 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. A plurality of switch elements T arranged along the column direction (vertical direction in the drawing), for example, switch elements T11 to T61, have two main terminals whose other main terminal is electrically connected to the signal line Sig1 in the first column. While the switching element T is in a conductive state, an electric signal corresponding to the charge of the conversion element S is output to the readout circuit 102 via the signal line. The signal lines Sig1 to Sig6 can transmit electrical signals output from a plurality of pixels PIX to the readout circuit 102 in parallel for each column.

The readout circuit 102 includes an amplifier circuit 206 for each signal line that amplifies the electrical signals output in parallel from the pixel portion 101. The amplifier circuit 206 includes an integrating amplifier 205 that amplifies the output electrical signal, a variable amplifier 204 that amplifies the electrical signal output from the integrating amplifier 205, a sample hold circuit 207 that samples and holds the amplified electrical signal, and a buffer amplifier. 209 included. The integrating amplifier 205 includes an operational amplifier that amplifies and outputs the electrical signal read out from the pixel PIX, an integrating capacitor, and a reset switch. Integrating amplifier 205 can change the amplification factor by changing the value of the integrating capacitance. The electrical signal output from the pixel PIX is input to the inverting input terminal of the integrating amplifier 205, the reference potential Vref from the reference power supply 103 is input to the normal input terminal, and the amplified electrical signal is output from the output terminal. Ru. Also, an integrating capacitor is placed between the inverting input terminal and the output terminal of the operational amplifier. The sample hold circuit 207 is provided together with the amplifier circuit 206, and is composed of a sampling switch and a sampling capacitor. Further, the readout circuit 102 includes a multiplexer 208 that sequentially outputs the electrical signals read out in parallel from the amplifier circuit 206 and outputs the electrical signals 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 the A/D converter 210 and output to the control computer 120 shown in FIG.

A power supply section 105 (omitted in FIG. 2) converts power from a battery or an external source into each power source, and supplies power to the reference power source 103, bias power source section 104, etc. 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.

Bias power supplies 203a and 203b of bias power supply unit 104 commonly supply bias potentials Vsa and Vsb to conversion element S via 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 fluctuations in the amount of current flowing through the bias lines Bsa and Bsb to the detection unit 106. In this embodiment, as a circuit that outputs current information, the bias power supplies 203a and 203b include a current-voltage conversion circuit 215 including an operational amplifier and a resistor, but the configuration is not limited to this. 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 may output current information as a digital value. Further, the bias power supplies 203a and 203b may output to the detection unit 106 an appropriate physical quantity corresponding to the amount of current supplied (flowed) to the bias line Bs.

The drive circuit 214 switches between a conduction voltage Vcom that makes the switch element T conductive (on) and a non-conductive (off) state according to control signals D-CLK, OE, and DIO input from the control unit 107 shown in FIG. A drive signal including a non-conducting voltage Vss to make the state non-conductive is output to each drive line. Thereby, the drive circuit 214 controls on or off of the switch element T and drives the pixel portion 101. Control signal D-CLK is a shift clock for a shift register used as 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 time required for driving and the scanning direction are set using the above control signals.

Further, 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 integrating amplifier 205. Control signal SH controls the operation of sample and hold circuit 207. Control signal CLK controls the operation of multiplexer 208.

In this embodiment, the pixel PIX arranged in the pixel portion 101 includes a pixel group in which a bias potential Vsa is supplied to the conversion element S from the bias power supply 203a, and a bias potential Vsb is supplied to the conversion element S from the bias power supply 203b. A pixel group. That is, in the pixel portion 101, two pixel groups each configured by pixels PIX including a conversion element S that converts radiation into charges and a switch element T that connects the conversion element S to the column signal line Sig are arranged. Bias power supply 203a supplies bias potential Vsa to a pixel group including pixels PIX including conversion elements S11, S13, and S15 via bias line Bsa. Further, the bias power supply 203b supplies a 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, switch elements T of different pixel groups are connected to different drive lines Vg. For example, switch elements T11, T13, and T15 are connected to drive line Vg1-1, and switch elements T12, T14, and T16 are connected to drive line Vg1-2. Therefore, in this embodiment, the pixel unit 101 has a configuration that can drive the pixels PIX for each pixel group connected to different bias power supplies 203. In this embodiment, the switch element T of the pixel PIX to which a 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 a bias potential is supplied from the bias power supply 203b via the bias line Bsb is connected to the drive line Vgn-“2”.

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

FIG. 3 is a flow diagram showing an example of the operation of the radiation imaging apparatus 100 in 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 the current information flowing through the bias line Bs acquired from the bias power supply unit 104, and detects radiation. Determine whether to start 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. To determine the start of radiation irradiation, the amount of charge accumulated in the conversion element S of the pixel PIX is obtained from the radiation information, and if the intensity of the radiation determined from the amount of charge exceeds a predetermined threshold, A method of determining that radiation irradiation has started may be used. If the detection unit 106 determines that radiation irradiation has not started (NO in S301), the radiation imaging apparatus 100 transitions to S302, and the control unit 107 causes the drive circuit 214 to control the conversion element of the pixel PIX by dark current. A reset drive (hereinafter sometimes referred to as idle reading) for removing the charge accumulated in S is performed. Idle reading is performed in order from the first row (drive line Vg1-1) to the last row (drive line Vg6-2), and when the last row is reached, the process returns to the first row.

When 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. To determine whether the radiation irradiation has ended, a method may be used in which it is determined that the radiation irradiation has ended when a predetermined time has elapsed since the start of the radiation irradiation was determined. Further, the control unit 107 acquires the amount of charge accumulated in the conversion element S of the pixel PIX from the radiation information acquired by the detection unit 106, and the intensity of the radiation determined from the amount of charge falls below a predetermined threshold. The end of radiation may be determined if If it is not determined that the radiation irradiation has ended (NO in S303), in S304, the drive circuit 214 of the radiation imaging apparatus 100 makes the switch element T of the pixel PIX for acquiring a radiation image non-conductive, and removes the radiation from the radiation. Driving for accumulating the converted signal (hereinafter sometimes referred to as accumulation) is performed. If it is determined that the radiation irradiation has ended (YES in S303), the radiation imaging apparatus 100 transitions to S305, and the drive circuit 214 and readout circuit 102 perform a drive (hereinafter referred to as , sometimes referred to as Honyomi). The main reading can be performed in order from the first row (drive line Vg1-1) to the last row (drive line Vg6-2) of the pixels PIX arranged in the pixel unit 101. When the main reading reaches the final line, the series of imaging operations ends.

FIG. 4 is a schematic diagram of the drive timing of the radiation imaging apparatus 100. The control unit 107 drives (drives) which sequentially turns on the switch elements S from the first row (drive line Vg1-1) to the last row (drive line VgY-2) of the pixel unit 101 until radiation irradiation is started. The drive circuit 214 is caused to repeatedly perform idle reading. In the configuration shown in FIG. 2, an example is shown in which the pixel unit 101 includes six pixel rows, but in FIG. 4, it is described as including Y pixel rows. If the blank reading reaches the last line until radiation irradiation is started, the blank reading is repeated by returning to the first line.

When the detection unit 106 detects (determines) the start of radiation irradiation, the control unit 107 controls, via the drive circuit 214, the switch elements T in the row to which all pixels PIX for acquiring a radiation image are connected. Shifts to drive (accumulation) to turn off. Here, in the radiation imaging apparatus 100, the pixel row in which the start of radiation irradiation is determined will be described as row Ys-1 (drive line VgYs-1). The details of determining whether or not radiation is irradiated will be described later. Accumulation continues until it is determined that radiation irradiation has ended. When the radiation irradiation is completed, the control unit 107 controls the drive circuit 214 and the readout circuit 102, sequentially turns on the switch elements T from the first row to the last row, and performs main reading to read out signals from the pixels PIX.

Next, a description will be given of the current flowing through the bias lines Bsa and Bsb when detecting the presence or absence of radiation irradiation and determining the start of radiation irradiation. First, when a voltage that turns on (conducts) the switch element T is applied to the drive line Vgn-1 (n is an integer from 1 to Y), at that timing a voltage is applied between the drive line Vgn-1 and the bias line Bsa. A current flows to the bias wiring Bsa via the parasitic capacitance existing in the pixel PIX (for example, the pixel including the switch element T13). For example, the parasitic capacitance includes the capacitance between the control electrode and the main electrode of the switching element T. When this parasitic capacitance is charged, current no longer flows. In FIG. 4, the current caused by the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa is illustrated as spike-like noise as a solid line in the positive direction of the bias line Bsa. Next, when a voltage is applied to the drive line Vgn-1 to turn off (non-conducting) the switch element T, the parasitic capacitance existing in the pixel PIX between the drive line Vgn-1 and the bias line Bsa at that timing is applied to the drive line Vgn-1. A current flows through the bias wiring Bsa. When this parasitic capacitance is charged, current no longer flows. In FIG. 4, the current caused by the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa is illustrated as a spike-like noise shown by a solid line in the negative direction of the bias line Bsa. The same goes for the drive line Vgn-2; when a voltage that turns on (conducts) the switch element T is applied to the drive line Vgn-2, the pixel between the drive line Vgn-2 and the bias line Bsb is turned on at that timing. A current flows to the bias wiring Bsb via the parasitic capacitance present in PIX (for example, a pixel including the switch element T14). In FIG. 4, the current caused by the parasitic capacitance between the drive line Vgn-2 and the bias line Bsb is illustrated as spike-like noise as a solid line in the positive direction of the bias line Bsb. Next, when a voltage is applied to the drive line Vgn-2 to turn off (non-conduct) the switch element T, the parasitic capacitance existing in the pixel PIX between the drive line Vgn-2 and the bias line Bsb is reduced at that timing. A current flows through the bias wiring Bsa. In FIG. 4, the current caused by the parasitic capacitance between the drive line Vgn-2 and the bias line Bsb is illustrated as a spike-like noise shown by a solid line in the negative direction of the bias line Bsb.

The drive line Vgn-1 and the bias line Bsb are not connected via the pixel PIX (for example, a pixel including the switch element T14). However, when a voltage that turns on (conducts) the switch element T is applied to the drive line Vgn-2, the bias wiring Bsa and the drive line Vgn-2, which were explained using FIG. A current begins to flow through the capacitor C (for example, capacitor C13) formed between the capacitor 2 and the capacitor C13. When this capacitor C is charged, current no longer flows. In FIG. 4, the current caused by the capacitance C formed between the drive line Vgn-2 and the bias line Bsa is illustrated as a spike-like noise indicated by a broken line in the positive direction of the bias line Bsa. Similarly, when a voltage is applied to the drive line Vgn-2 to turn off (non-conduct) the switch element T, at that timing, the capacitance C formed between the bias wiring Bsa and the drive line Vgn-2 is A current begins to flow through the bias wiring Bsa. When this capacitor C is charged, current no longer flows. In FIG. 4, the current caused by the capacitance C formed between the drive line Vgn-2 and the bias line Bsa is illustrated as a spike-like noise indicated by 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 (eg, capacitance C14) formed between the drive line Vgn-1 and the bias line Bsb.

In this embodiment, as shown in FIG. 4, the drive circuit 214 turns on the switch elements T of pixels PIX included in different pixel groups at different timings. Here, turning on the switch element T is an operation in which the drive circuit 214 applies a voltage to the drive line Vg that turns the switch element T on until it applies a voltage that turns it off. Therefore, compared to the case where one system of bias lines is used as in Patent Document 1, the influence of the parasitic capacitance between the drive line Vg and the bias line Bs in one idle reading drive is reduced. In other words, the current flowing through the bias line Bs due to the parasitic capacitance is reduced. As a result, the noise generated when the switching element T is turned on and off relative to the current flowing through the bias line Bs due to radiation irradiation becomes relatively small, and the influence of noise is suppressed more than in the structure shown in Patent Document 1. can. As a result, the detection unit 106 can improve accuracy in detecting 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. I can do it.

Furthermore, the inventors discovered the following characteristics regarding the noise current caused by the parasitic capacitance or the formed capacitance between the drive line Vg and the bias line Bs, and the current caused by radiation irradiation. The amount of noise current is caused by the parasitic capacitance between the drive line Vg and bias line Bs that are connected through the switch element T, or the parasitic capacitance between the drive line Vg and the bias line Bs that are not connected through the switch element T. It is proportional to the capacitance C formed between them (I=dQ/dt=C·dV/dt). For this reason, by adjusting the parasitic capacitance and the formed capacitance C to be equivalent, when turning on or off the switching element T on the drive line Vg, the bias line Bsa and the bias line Bsb have an in-phase and equivalent noise current. This will allow the flow of Furthermore, by calculating the difference between the currents flowing through the bias line Bsa and the bias line Bsb, it becomes possible to cancel out 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 radiation irradiation is calculated as shown in FIG. is not canceled as shown in . In other words, by making the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa equal to the capacitance C formed between the drive line Vgn-1 and the bias line Bsb, radiation irradiation can be further reduced. It becomes possible to improve the accuracy of detecting the presence or absence. For example, so that 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 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 the current based on the difference between the analog values of the respective signal values. The unit 106 may determine whether or not radiation is irradiated. At this time, the detection unit 106 may obtain the difference as an analog value, or may obtain the difference between analog values as a digital value obtained by analog/digital conversion. By performing differential processing on 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 sampling at predetermined intervals.

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

As shown in FIG. 5A, signal lines Sig2m, Sig2m+1, Sig2m+2, Sig2m+3, . . . are provided corresponding to columns 2m, 2m+1, 2m+2, 2m+3, . Bias lines Bsa and Bsb are also provided corresponding to the columns 2m, 2m+1, 2m+2, 2m+3, . . . , respectively.

In the configuration shown in FIG. 5(b), the substrate 400 on which the pixel PIX is provided is an insulating substrate made of glass, plastic, or the like. 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 metal. Similarly, the main electrode 402 and the signal line Sig may be integrally formed of a common conductor such as 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 disposed on the main surface of the substrate 400, a semiconductor layer 412 disposed on the lower electrode 411, and an upper electrode 414 disposed on the semiconductor layer 412. The semiconductor layer 412 has an impurity semiconductor layer 4121, an intrinsic semiconductor layer 4122, and an impurity semiconductor layer 4123 stacked in this order. In this 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 metal, but may be formed of different conductive materials.

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 a planarization layer 4200. Bias line Bs is provided on insulating layer 420 and planarization layer 4200. An opening 450 is provided in a part of the insulating layer 420 and the planarization layer 4200 on the upper electrode 414 of the conversion element S, and the conductive layer 430 electrically connects the bias line Bs and the upper electrode 414 via the opening 450. . The bias line 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 entirety of each of the above-mentioned structures. The insulating layer 404, the insulating layer 420, and the protective layer 440 may be formed of an inorganic insulating film such as silicon nitride. The planarization layer 4200 may be formed of a material with a low dielectric constant (ε/ε ₀ =2 to 5), such as photosensitive acrylic or polyimide. Furthermore, a scintillator (not shown) is provided on the protective layer 440 to convert radiation into light having a wavelength that can be detected by the PIN photodiode functioning as the conversion element 202.

In FIG. 5A, attention is paid to the drive line Vgn-1 passing through the nth row, 2mth column, and the nth row, 2m+1th column. The drive line Vgn-1 connected to the pixel PIX including the conversion element S to which a bias potential is supplied by the bias line Bsa is connected 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) 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
has. Furthermore, in the configuration shown in FIG. 5A, in orthogonal projection onto the main surface of the substrate 400, the portion of the drive line Vgn-1 extending in the row direction corresponds to the pixel to which the bias potential is supplied by the bias line Bsa. It does not overlap with the lower electrode 411 of the pixels included in the pixel group formed by 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
It may have. Similarly, the drive line Vgn-2 connected to the pixel PIX including the conversion element S to which a bias potential is supplied by the bias line Bsb is
(5) Intersection with bias line Bsb (6) Intersection with bias line Bsa (7) Overlap with lower electrode 411 of conversion element S of pixel PIX to which bias potential is supplied by 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 a bias potential is supplied by the bias line Bsb.

The drive line Vg is arranged in a layer closer to the substrate 400 than the lower electrode 411 of the conversion element S, and when the drive line Vg and the lower electrode 411 overlap, they are arranged adjacent to each other with an insulating layer 404 interposed therebetween. Therefore, in (1) to (4) above, (1) and (4) contribute to the capacitive coupling component between the drive line Vgn-1 and the bias line Bsa. In other words, it contributes to the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa. Furthermore, (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. do. The areas and shapes of these intersecting portions 461, 462, overlapping portions 463, 464, and the thickness of the constituent materials are adjusted. Thereby, it is possible to adjust the capacitance values of the parasitic capacitances and the capacitances formed between the drive line Vgn-1 and the bias line Bsb which are not connected via the switch element T.

In this embodiment, it is assumed that (1) and (2) and (3) and (4) have the same layer structure. Regarding (1) and (2), by designing so that the areas of (1) and (2) are approximately equal to each other, the capacitance values generated in (1) and (2) are also approximately equal to each other. becomes. On the other hand, regarding (3) and (4), the area of (3) is designed to be larger than the area of (4). That is, in the orthogonal projection onto 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 the area of the drive line Vgn-1. The area of the line Vgn-1 is designed to be larger than the area of the portion (overlapping portion 463) overlapping 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 capacitance value occurring in (3) becomes larger than the capacitance value occurring in (4). 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.

The same applies to (5) to (8). By designing so that the areas of (5) and (6) are approximately equal to each other, the capacitance values generated in (5) and (6) are also approximately equal to each other. On the other hand, regarding (7) and (8), the area of (7) is designed to be larger than the area of (8). That is, in the orthogonal projection onto 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 area of the drive line Vgn-2. Among them, the area is designed to be larger than the area of the portion overlapping 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. At this time, the capacitance value occurring at (7) becomes larger than the capacitance value occurring at (8). This makes it possible to bring the value of the capacitance C formed between the drive line Vgn-2 and the bias line Bsa 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 capacitances C11 to C66 described above.

Not limited to the above, in general, if the "total 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)," "(5) The effects of the present disclosure can be obtained if the design is made such that the sum of the capacitance generated in (8) and the capacitance generated in (8) is less than the capacitance generated in (6) and (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 calculated, it is possible to effectively suppress noise that occurs when the switching element T is turned on or off. As a result, the detection unit 106 can improve accuracy in detecting the presence or absence of radiation irradiation.

When the detection unit 106 detects the start of radiation irradiation, the control unit 107 makes all the switch elements T non-conductive and causes the pixels PIX to accumulate signals due to the radiation. Thereafter, the control unit 107 performs the main reading in response to the completion of radiation irradiation. In the configuration shown in FIG. 2, two drive lines Vgn-1 and Vgn-2 for two pixel groups are connected to 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 this embodiment, there are 2Y drive lines Vg. Therefore, if the main reading is performed by sequentially turning on the switch elements T from the first row to the last row, it will take twice as long to read out the signals of all rows if the drive cycle time is the same as in Patent Document 1. . Therefore, as shown in FIG. 4, during main reading, the control unit 107 controls the drive circuit 214 so that the drive lines Vg for two rows are brought into conduction at once, thereby shortening the main reading time as the number of drive lines Vg increases. The increase may be suppressed. Specifically, as shown in FIG. 2, the signal line Sig is shared by the pixels arranged in each column among the plurality of pixels PIX. Therefore, when acquiring radiographic image data, the drive circuit 214 suppresses the increase in main reading time by turning on the switch elements T connected to the drive line Vg1-1 and the drive line Vg1-2 at the same time, for example. It becomes possible to do so.

In this embodiment, by using two bias lines Bsa and Bsb, the current flowing through the bias line Bs when turning on or off the switch element T due to the parasitic capacitance existing between the drive line Vg and the bias line Bs is reduced. suppress. Furthermore, the capacitance formed between the drive line Vg and the bias line Bs which are not connected through the switch element T is considered to be the parasitic capacity between the drive line Vg and the bias line Bs which are connected through the switch element T. Close to capacity. This makes it possible to reduce radiation detection errors and detection delays due to noise currents that occur during "idle reading drive."

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

Second Embodiment A radiation imaging apparatus according to 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 section 110 of the radiation imaging apparatus 100 in the second embodiment. The configuration of the imaging unit 110 of this embodiment differs from the configuration shown in FIG. 2 in the configuration of the pixel unit 101 and the configuration of the amplifier circuit 206 of the readout circuit 102. Specifically, two pixels PIX that are adjacent to each other in the row direction intersecting the column signal line Sig and whose switch elements T are controlled by different drive lines among the plurality of drive lines Vg receive the signal. They share the line Sig. At this time, as shown in FIG. 6, one of the two adjacent pixels PIX 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. It may be included in a pixel group to which a bias potential is supplied. Since two pixels PIX adjacent in the row direction share the column signal line Sig, the number of signal lines Sig is halved compared to the configuration shown in FIG. Additionally, the number of amplifier circuits 206 arranged in the readout circuit 102 is reduced by half compared to the configuration shown in FIG. 2. As a result, in the configuration shown in FIG. 2, the number of amplifier circuits 206 in the readout circuit 102 can be reduced, in response to the problem that the scale of the drive circuit 214 is increased compared to the configuration of Patent Document 1. Thereby, it is 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 wirings in the pixel section 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 diagram of the drive timing of the radiation imaging apparatus 100 in this embodiment. The driving involved in detecting the presence or absence of radiation irradiation during idle reading may be the same as the driving described using FIG. 4 . Therefore, similarly to the first embodiment described above, it is possible to suppress the influence of parasitic capacitance and increase the accuracy of detecting the presence or absence of radiation irradiation. In addition, in this embodiment, since the two pixels PIX adjacent to each other are connected to the same signal line Sig, turning on the switch elements T in two rows at once in the main reading drive as described above is This is not possible because the signals for the two pixels added would be added. Therefore, as shown in FIG. 9, when acquiring radiation image data, the drive circuit 214 turns on the switch elements T of the pixels PIX connected to the same signal line Sig at different timings. This allows the charges accumulated in each pixel PIX to be read out.

FIG. 8 is a plan view of the pixel PIX in this embodiment. Further, the cross-sectional view along A-A' shown in FIG. 8 may be the same as that in FIG. 5(b). In this embodiment, mutually adjacent pixels PIX share a column signal line Sig. For example, the column signal line Sig2m and the column signal line Sig2m+1 in FIG. 5A described above are replaced with a common column signal line Sigm. This makes it possible to suppress the number of amplifier circuits 206 and reduce the number of column signal lines Sig arranged within the pixel section 101 compared to the first embodiment, thereby suppressing cost increases. A capacitance C formed between the drive line Vg and the bias line Bs that are not connected via the switch element T, and between the drive line Vg and the bias line Bs that are connected via the switch element T. The method for adjusting the parasitic capacitance may be the same as that described using FIGS. 5(a) and 5(b) above.

Next, using FIGS. 9(a) and 9(b), 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 Another example of a method for adjusting 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 sectional view taken along line A-A' shown in FIG. 9(a). In the configuration shown in FIG. 9(b), the structure of the switch element T is almost the same as the switch element T shown in FIG. Except for 450, they are different in that they are covered with an insulating layer 4201 and a planarization layer 4202. The insulating layer 4201 may be formed of an inorganic insulating film such as silicon nitride. The planarization layer 4202 may be formed of photosensitive acrylic, polyimide, or the like. A lower electrode 411 of the conversion element S is formed on the planarization layer 4202. The lower electrode 411 is formed of a conductor different from the main electrode 403 of the switch element T. Lower electrode 411 and main electrode 403 are electrically connected through opening 450. A bias line Bs is provided above the upper electrode 414 along the column direction in which the column signal line Sig extends. A planarization layer 4204 is provided between the bias line Bs and the upper electrode 414 except for the opening 451 portion. The bias line Bs and the upper electrode 414 are electrically connected through an opening 451 provided in a part of the planarization layer 4204. The protective layer 440 covers the entirety of each of the above-mentioned structures.

In FIG. 9A, attention is paid to the drive line Vgn-1 passing through the nth row, 2mth column, and the nth row, 2m+1th column. The drive line Vgn-1 connected to the pixel PIX including the conversion element S to which a bias potential is supplied by the bias line Bsa is connected to the lower electrode 411 of the conversion element S.
(9) 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
has. Similarly, the drive line Vgn-2 connected to the pixel PIX including the conversion element S to which a bias potential is supplied by the bias line Bsb is
(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 411.

In (9) to (12) above, (9) and (12) contribute to the capacitive coupling component between the drive line Vgn-1 and the bias line Bsa. In other words, it contributes to the parasitic capacitance between the drive line Vgn-1 and the bias line Bsa. Furthermore, (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. do. The area and shape of these overlapping portions 468 and 469 and the thickness of the constituent material are adjusted. Thereby, it is possible to adjust the capacitance values of the parasitic capacitances and the capacitances formed between the drive line Vgn-1 and the bias line Bsb which are not connected via the switch element T.

In this embodiment, it is assumed that (9) to (12) each have the same layer structure. In this case, in the orthogonal projection onto 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 as follows: 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 a 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 orthogonal projection onto the main surface of the substrate 400, pixels extending in the row direction of the drive line Vgn-1 and to which a bias potential is supplied by the bias line Bsb A portion of the drive line Vgn-1 that overlaps with the lower electrode 411 of the pixel PIX included in the group extends in the row direction, and the lower part of the pixel PIX included in the pixel group is supplied with a bias potential by the bias line Bsa. It may include a portion wider than the portion overlapping the electrode 411. Similarly, regarding the drive line Vgn-2, in the orthogonal projection onto 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 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 a bias potential is supplied by the bias line Bsb. For example, as shown in FIG. 9A, in orthogonal projection onto the main surface of the substrate 400, pixels extending in the row direction of the drive line Vgn-2 and to which a bias potential is supplied by the bias line Bsa A portion of the drive line Vgn-2 that overlaps with the lower electrode 411 of the pixel PIX included in the group extends in the row direction, and the lower part of the pixel PIX included in the pixel group is supplied with a bias potential 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 capacitances C11 to C66 described above.

Thereby, when the difference between the currents flowing through the bias line Bsa and the bias line Bsb is calculated, it is possible to effectively suppress noise that occurs when the switching element T is turned on or off. As a result, the detection unit 106 can improve accuracy in detecting the presence or absence of radiation irradiation. Furthermore, in this embodiment, the number of amplifier circuits 206 arranged in the readout circuit 102 can be suppressed compared to the above-described first embodiment. Thereby, it is possible to suppress an increase in the cost of the radiation imaging apparatus 100, and furthermore, it is possible to reduce the wiring pattern of the pixel section 101, and it is possible to increase the pixel aperture ratio.

Third Embodiment A radiation imaging apparatus in 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 section 110 of the radiation imaging apparatus 100 in the third embodiment. The configuration of the imaging unit 110 of this embodiment differs from the configuration shown in FIG. 2 in the configuration of the pixel unit 101. In the configuration shown in FIG. 2, in the row direction, pixels PIX included in the pixel group to which a bias potential is supplied by the bias line Bsa and pixels PIX included in the pixel group to which the bias potential is supplied by the bias line Bsb are alternately arranged. It was placed in On the other hand, in the configuration shown in FIG. 10, in the row direction intersecting the column signal line Sig, the pixel group that is supplied with the bias potential by the bias line Bsa or the pixel group that is supplied with the bias potential by the bias line Bsb is 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. In addition, in the column direction in which the column signal line Sig extends, a pixel PIX included in a pixel group to which a bias potential is supplied by the bias line Bsa and a pixel PIX included in a pixel group to which a bias potential is supplied by the bias line Bsb. are arranged alternately. By wiring in this manner, the number of column signal lines Sig is equal to that of the first embodiment, and the number of drive lines Vg is reduced to 1/2. Furthermore, compared to the second embodiment, the number of column signal lines Sig is doubled, but the number of drive lines Vg is halved, and the total number of wiring lines is approximately the same.

FIG. 11 is a schematic diagram of the drive timing of the radiation imaging apparatus 100 in this embodiment. The driving involved in detecting the presence or absence of radiation irradiation during idle reading may be the same as the driving described using FIG. 4 . Therefore, similarly to the first embodiment described above, it is possible to suppress the influence of parasitic capacitance and increase the accuracy of detecting the presence or absence of radiation irradiation. Furthermore, in this embodiment, since the number of drive lines is reduced to 1/2, the time required for main reading is reduced by turning on the two drive line Vg switch elements T of the first embodiment shown in FIG. 4 at the same time. It is equivalent to driving. Furthermore, the time required for main reading is reduced to 1/2 compared to the drive 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 for 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 cross-sectional view along line AA' shown in FIG. 12(a), and FIG. 12(c) is a plan view of the pixel PIX. FIG. 3 is a sectional view taken along line BB' shown in FIG.

As shown in FIG. 12A, in the orthogonal projection onto the main surface of the substrate 400, the bias lines Bsa and Bsb extend between the conversion elements S of adjacent pixels PIX in the column direction in which the column signal line Sig extends. It is located along the The layer structure and cross-sectional structure are almost the same as those of the second embodiment shown in FIG. 430 are arranged so as to extend from the bias line Bsa to both sides in the row direction, and are connected to the upper electrode 414 through the openings 451, respectively. Similarly, the conductive layer 430 in the n-th row is arranged so as to spread from the bias line Bsb to both sides in the row direction, and is connected to the upper electrode 414 of the conversion element S through the opening 451, respectively. In this way, the upper electrodes 414 of the photodiodes are alternately connected to the bias lines Bsa and Bsb in odd-numbered rows and even-numbered rows.

Further, the drive line Vgn that controls the switch element T of the pixel PIX in the n-th row mainly extends in the row direction under the lower electrode 411 of the pixel PIX in the n-1th row, not in the n-th row. It extends to the n-th row switch element T so as to protrude in the column direction from the portion extending in the direction. In FIG. 12(a), when focusing on the drive line Vgn connected to the pixel PIX including the conversion element S to which a bias potential is supplied by the bias line Bsb,
(13) Overlapping portion 471 with the lower electrode 411 of the conversion element S of the pixel PIX (pixel on the n-1st row) to which a bias potential is supplied by the bias line Bsa
(14) Overlapping portion 472 with the lower electrode 411 of the conversion element S of the pixel PIX (n-th row pixel) to which a bias potential is supplied by the bias line Bsb
has. Similarly, for the drive line Vgn+1 (15), the overlapped portion 473 with the lower electrode 411 of the conversion element S of the pixel PIX (n-th row pixel) to which the bias potential is supplied by the bias line Bsb.
(16) Overlapping portion 474 with the lower electrode 411 of the conversion element S of the pixel PIX (pixel on the n+1st row) to which a bias potential is supplied by the bias line Bsa
has.

In (13) and (14) above, (13) contributes to the capacitive coupling component between the drive line Vgn and the bias line Bsa. In other words, it contributes to the capacitance C formed between the drive line Vgn and bias line Bsa described above. Further, (14) contributes to the capacitive coupling component between the drive line Vgn and the bias line Bsb, that is, the 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 thickness of the constituent materials are adjusted. Thereby, the capacitance values of the capacitances C formed between the drive line Vgn and the bias line Bsa which are not connected via the parasitic capacitance or the switch element T can be adjusted. The same applies to (15) and (16).

In this embodiment, it is assumed that (13) to (16) each have the same layer structure. In this case, in the orthogonal projection onto 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 area of Vgn is designed to be larger than the area of the portion (overlapping portion 472) overlapping 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, regarding 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 orthogonal projection onto the main surface, the pixel group of the drive line Vgn+1 to which the bias potential is supplied by the bias line Bsb is The area of the portion of the included pixel PIX that overlaps with the lower electrode 411 is larger than the area of the portion of the drive line Vgn+1 that overlaps with the lower electrode 411 of the pixel PIX that is included in the pixel group to which the bias potential is supplied by the bias line Bsa. Design as follows. In this way, it is possible to adjust the values of the capacitances C11 to C66 described above.

Also in this embodiment, when the difference between the currents flowing through the bias line Bsa and the bias line Bsb is calculated, it is possible to effectively suppress the noise that occurs when the switch element T is turned on or off. As a result, the detection unit 106 can improve accuracy in detecting the presence or absence of radiation irradiation. Furthermore, since the number of drive lines Vg is halved compared to the first embodiment, the scale of the drive circuit 214 can be reduced. can be reduced, and the pixel aperture ratio can be increased. Furthermore, compared to the second embodiment, the read speed when performing the main read drive can be doubled.

The invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the following claims are hereby appended to disclose the scope of the invention.

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

Claims (33)

A pixel which is a circuit for detecting radiation and includes a conversion element that is capable of accumulating charge and includes a first electrode and a second electrode, and a switch element that connects the conversion element to a column signal line. a plurality of pixels arranged in a matrix, a plurality of drive lines for controlling each switch element of the plurality of pixels and extending along the row direction of the matrix, and a plate-shaped base. It has a multilayer structure circuit including material and
The plurality of pixels include at least a first pixel and a second pixel as pixels arranged in a predetermined row of the matrix,
The plurality of drive lines include at least a first drive line connected to the switch element of the first pixel and a second drive line connected to the switch element of the second pixel,
In the orthogonal projection onto the main surface of the base material, the area of the portion of the first drive line that overlaps with the second electrode of the second pixel is the area of the portion of the first drive line that overlaps with the second electrode of the first pixel. A radiation imaging device characterized in that the area is larger than the area of the overlapped portion . a first bias power supply that supplies a bias potential to the conversion element of the first pixel via a first bias line;
a second bias power source that supplies a bias potential to the conversion element of the second pixel via a second bias line different from the first bias line;
a detection unit that detects the presence or absence of radiation irradiation based on a first signal value indicating a current flowing through the first bias line and a second signal value indicating a current flowing through the second bias line; The radiation imaging device according to claim 1. The conversion element includes the first electrode , the second electrode, and a semiconductor layer located between the first electrode and the second electrode,
A portion of the first drive line that overlaps with the second electrode of the second pixel is formed in a layer closer to the base material than the second electrode of the second pixel,
The radiation imaging device according to claim 1 or 2 , wherein an insulating layer is formed between the second electrode and the first drive line . The radiation imaging apparatus according to claim 2, wherein the first signal value and the second signal value are analog values . In orthogonal projection onto the main surface of the base material , a region of the first drive line overlapping with the second pixel includes a portion wider than a region of the first drive line overlapping with the first pixel. The radiation imaging apparatus according to claim 1 , characterized in that: The first pixel is connected to a first column wiring among column wirings extending along the column direction of the matrix, and the second pixel is connected to a second column wiring among the column wirings,
A parasitic capacitance between the first drive line and the first column wiring is 70% or more and 130% or less of the capacitance formed between the first drive line and the second column wiring. The radiation imaging apparatus according to any one of claims 1 to 5, characterized in that: A parasitic capacitance between the first drive line and the first column wiring is the same as a capacitance formed between the first drive line and the second column wiring . Item 6. The radiation imaging device according to item 6 . 6. The first pixel and the second pixel are adjacent to each other, and the first pixel and the second pixel are connected to a common column signal line. The radiation imaging device according to item 1. The plurality of pixels are a first group of pixels that are supplied with a bias potential via the first bias line, and include a first group of pixels that includes the first pixel, and a bias potential is supplied via the second bias line. The radiation imaging apparatus according to claim 2 , further comprising a second group of pixels to which a potential is supplied, the second group of pixels including the second pixel . The radiation imaging apparatus according to claim 9 , wherein the first group of pixels and the second group of pixels are alternately arranged in the predetermined row . The column in which the first pixel is arranged in the matrix is a column in which a plurality of pixels of the first group are consecutively arranged,
The radiation imaging apparatus according to claim 9 , wherein the column in which the second pixel is arranged in the matrix is a column in which a plurality of pixels of the second group are consecutively arranged . The radiation imaging according to claim 9 , wherein pixels included in the first group and pixels included in the second group are alternately arranged in a predetermined column of the matrix. Device. In the predetermined row , another pixel of the first group is arranged adjacent to the first pixel, and another pixel of the second group is arranged adjacent to the second pixel. The radiation imaging device according to claim 9 , characterized by: The radiation imaging apparatus according to claim 2 , wherein the detection unit determines whether or not radiation is irradiated based on a difference between the first signal value and the second signal value. The radiation imaging according to claim 2 , wherein the number of 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. Device. 16. The radiation imaging apparatus according to claim 1, wherein the conversion element is a PIN type or MIS type element. The radiation imaging device according to any one of claims 1 to 16,
a radiation generating device that irradiates the radiation imaging device with radiation;
A radiation imaging system comprising: A pixel which is a circuit for detecting radiation and includes a conversion element that is capable of accumulating charge and includes a first electrode and a second electrode, and a switch element that connects the conversion element to a column signal line. a plurality of pixels arranged in a matrix, a plurality of drive lines for controlling each switch element of the plurality of pixels and extending along the row direction of the matrix, and a plate-shaped base. It has a multilayer structure circuit including material and
The plurality of pixels include at least a first pixel and a second pixel as pixels arranged in a predetermined row of the matrix,
The plurality of drive lines include at least a first drive line connected to the switch element of the first pixel and a second drive line connected to the switch element of the second pixel,
In the orthogonal projection onto the main surface of the base material, the first drive line has a region overlapping with the second electrode of the second pixel and does not have a region overlapping with the second electrode of the first pixel. Characteristic radiation imaging device. The conversion element includes the first electrode, the second electrode, and a semiconductor layer located between the first electrode and the second electrode,
A portion of the first drive line that overlaps with the second electrode of the second pixel is formed in a layer closer to the base material than the second electrode of the second pixel,
The radiation imaging device according to claim 18, wherein an insulating layer is formed between the second electrode and the first drive line. The first pixel is connected to a first column wiring among column wirings extending along the column direction of the matrix, and the second pixel is connected to a second column wiring among the column wirings,
The parasitic capacitance between the first drive line and the first column wiring is 70% or more and 130% or less of the capacitance formed between the first drive line and the second column wiring. The radiation imaging device according to claim 18 or 19. 20. A parasitic capacitance between the first drive line and the first column wiring is the same as a capacitance formed between the first drive line and the second column wiring. The radiation imaging device described in . 22. The first pixel and the second pixel are adjacent to each other, and the first pixel and the second pixel are connected to a common column signal line. The radiation imaging device according to item 1. a first bias power supply that supplies a bias potential to the conversion element of the first pixel via a first bias line;
a second bias power source that supplies a bias potential to the conversion element of the second pixel via a second bias line different from the first bias line;
A detection unit that detects the presence or absence of radiation irradiation based on a first signal value indicating a current flowing through the first bias line and a second signal value indicating a current flowing through the second bias line. The radiation imaging apparatus according to any one of claims 18 to 22. The plurality of pixels are a first group of pixels that are supplied with a bias potential via the first bias line, and include a first group of pixels that includes the first pixel, and a bias potential is supplied via the second bias line. 24. The radiation imaging apparatus according to claim 23, further comprising a second group of pixels to which a potential is supplied, the second group of pixels including the second pixel. 25. The radiation imaging apparatus according to claim 24, wherein the first group of pixels and the second group of pixels are alternately arranged in the predetermined row. The column in which the first pixel is arranged in the matrix is a column in which a plurality of pixels of the first group are consecutively arranged,
25. The radiation imaging apparatus according to claim 24, wherein the column in which the second pixel is arranged in the matrix is a column in which a plurality of pixels of the second group are consecutively arranged. 25. The radiation imaging apparatus according to claim 24, wherein pixels included in the first group and pixels included in the second group are alternately arranged in a predetermined column of the matrix. In the predetermined row, another pixel of the first group is arranged adjacent to the first pixel, and another pixel of the second group is arranged adjacent to the second pixel. The radiation imaging device according to claim 24. 29. The radiation imaging apparatus according to claim 23, wherein the first signal value and the second signal value are analog values. The radiation according to any one of claims 23 to 29, wherein the detection unit determines whether or not radiation is irradiated based on a difference between the first signal value and the second signal value. Imaging device. Any one of claims 23 to 30, wherein the number of 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 device according to item 1. 32. The radiation imaging apparatus according to claim 18, wherein the conversion element is a PIN type or MIS type element. The radiation imaging device according to any one of claims 18 to 32;
a radiation generating device that irradiates the radiation imaging device with radiation;
A radiation imaging system comprising:

Images