JP5120458B2 - Light or radiation imaging device - Google Patents

Description

  The present invention relates to a light or radiation imaging apparatus used in the medical field, industrial fields such as non-destructive inspection, RI (Radio Isotope) inspection, and optical inspection, and more particularly, charge from a detection element that detects light or radiation. The present invention relates to a light or radiation imaging apparatus including a circuit for reading a signal.

  Conventionally, a light or radiation imaging apparatus is provided with a light or radiation detector for detecting light or radiation. Here, light refers to infrared rays, visible rays, ultraviolet rays, radiation, γ-rays, and the like. In particular, an X-ray detector will be described as an example. The X-ray detector includes an X-ray sensitive X-ray conversion layer. The X-ray conversion layer generates a carrier (charge signal) by the incidence of X-rays, and reads the generated charge signal to read X Detect lines.

  When X-ray imaging is performed by irradiating the subject with X-rays, carriers (charge signals) proportional to the intensity of the X-ray intensity transmitted through the subject are generated in the X-ray conversion layer. After that, the carriers (charge signals) generated in the X-ray conversion layer are collected on the two-dimensionally arranged carrier collecting electrodes and accumulated for a predetermined time, and then the data are transmitted through the thin film transistor (TFT). Read out through line. Further, in order to manufacture such an X-ray detector, an X-ray conversion type is formed on an insulating substrate on which a switching element made up of thin film transistors (TFTs) arranged in a two-dimensional manner and the above-described carrier collection electrode are patterned. It is obtained by evaporating the semiconductor film.

The X-ray detector further includes, for example, a charge detection amplification circuit (CSA) that converts a charge signal generated in the X-ray conversion layer into a voltage signal, and a signal amplification circuit that amplifies the voltage signal from the charge detection amplification circuit. There is a sample hold circuit that samples a voltage signal output from a signal amplifier circuit, holds (holds) the sampled voltage signal, and outputs the sampled signal (for example, see Patent Document 1). The voltage signal output from the sample hold circuit is time-divided by a multiplexer, and the time-divided voltage signal is converted to a digital signal by an A / D converter.
JP 2007-306481 A

  However, in the method disclosed in Patent Document 1, the read operation of each data line is a procedure of clearing the charge detection amplifier circuit and the signal amplifier circuit, charge accumulation, and voltage hold. On the other hand, there is a problem that the ratio of the clear time of the charge detection amplifier circuit and the signal amplifier circuit increases. Furthermore, since the number of gate lines increases as the number of pixels of the radiation detector increases, the readout time of one line is also a cause. For these reasons, there is a limit in reading out a high-speed voltage signal, and it is difficult to create a radiation transmission image with a moving image, especially as the screen becomes larger.

  The present invention has been made in view of such circumstances, and is a light or radiation imaging apparatus capable of performing a series of readings for converting a charge signal generated in a light or radiation conversion layer into a voltage signal at high speed. The purpose is to provide.

In order to achieve such an object, the present invention has the following configuration.
That is, the first invention of the present invention is a light or radiation imaging apparatus, wherein a plurality of detection elements that generate charge signals in response to light or radiation are arranged in a two-dimensional matrix. Means, a switching signal operating means for sending a switching signal for reading out the charge signal for each row of the two-dimensional matrix of the light or radiation detection means, and a feedback capacitor, from the light or radiation detection means via a data line Charge voltage conversion means for converting the read charge signal into a voltage signal, voltage signal amplification means for amplifying the voltage signal converted by the charge voltage conversion means, and the voltage signal amplified by the voltage signal amplification means Voltage signal holding means for sampling for a predetermined time and holding for a predetermined time; and first switching means for connecting or disconnecting the data lines; Second switching means for switching to either the connection between the data line and the charge-voltage conversion means or the connection between the ground line and the charge-voltage conversion means, and the data is controlled by the first switching means. By connecting the lines, the charge signals from the detection elements connected on a plurality of data lines can be read simultaneously, and the ground line and the charge voltage conversion means are connected by the second switching means. The feedback capacitor is reset while the charge signal of the charge voltage conversion means is erased .

  According to the first aspect of the present invention, any one of the first switching means for connecting or disconnecting the data lines, the connection between the data line and the charge voltage conversion means, and the connection between the ground line and the charge voltage conversion means. And a second switching means for switching connection to each other, so that the charge signal from the detection element can be added and read via a plurality of data lines. In addition, since the charge voltage conversion means and voltage signal amplification means connected to the data line need only operate, the charge voltage conversion means and voltage signal amplification means not connected to the data line can be initialized. As described above, the charge voltage conversion means and the voltage signal amplification means that are operating and the charge voltage conversion means and the voltage signal amplification means to be initialized can be simultaneously processed in parallel by the switching connection of the second switching means. it can. Thereby, a light or radiation imaging apparatus capable of reading out a charge signal at high speed is obtained.

  Further, when the ground line and the charge / voltage converting means are connected by the second switching means, the charge signal of the charge / voltage converting means may be erased. As a result, the charge signal of the charge-voltage conversion means can be erased reliably and initialized.

  When the second switching means connects the ground line and the charge / voltage conversion means, the voltage signal amplification means starts to be initialized, and the second switching means causes the data line and the charge to be initialized. After the voltage converting means is connected, the initialization of the voltage signal amplifying means may be finished. As a result, the initialization of the voltage signal amplifying means can be performed reliably, and the initialization of the voltage signal amplifying means is completed after the data line and the charge voltage converting means are connected, so that the voltage The base potential of the signal amplification means can be matched with the potential of the data line.

  The first switching unit may connect or block the data lines two by two. Thereby, the charge signals of two pixels in the row direction of the two-dimensional matrix of the light or radiation detector can be added. Thus, the charge signal can be read out at high speed.

  According to a second aspect of the present invention, there is provided a light or radiation imaging apparatus, comprising: a light or radiation detection means in which a plurality of detection elements that generate a charge signal in response to light or radiation are arranged in a two-dimensional matrix. A switching signal operating means for sending a switching signal for reading out the charge signal for each row of the two-dimensional matrix of the light or radiation detection means, and a charge signal read out from the light or radiation detection means via a data line as a voltage signal. Charge voltage conversion means for conversion, voltage signal amplification means for amplifying the voltage signal converted by the charge voltage conversion means, and voltage signal amplified by the voltage signal amplification means for a predetermined time after sampling Voltage signal holding means for holding, and first switching means for connecting or disconnecting each of the data lines with one of two connection lines. A second switching means for switching between the connection line and the charge voltage conversion means, or a connection between the ground line and the charge voltage conversion means, and one data line. The charge voltage conversion means, the voltage signal amplification means, and the voltage signal holding means are provided in two sets in parallel.

  According to the second aspect of the present invention, the first switching means for connecting or disconnecting one of the two connection lines with respect to one data line, the connection between the connection line and the charge voltage conversion means, and the ground The second switching means that switches to one of the connection between the line and the charge voltage converting means, and the charge voltage converting means, the voltage signal amplifying means, and the voltage signal holding means are connected in parallel to one data line. Since two sets are provided, the charge signals from the detection elements can be alternately read. In addition, since the charge voltage conversion means and voltage signal amplification means connected to the data line need only operate, the charge voltage conversion means and voltage signal amplification means not connected to the data line can be initialized. As described above, the switching operation of the first switching means and the second switching means allows the charge voltage conversion means and the voltage signal amplification means that are operating and the charge voltage conversion means and the voltage signal amplification means to be initialized at the same time in parallel. Can be processed. Thereby, a light or radiation imaging apparatus capable of reading out a charge signal at high speed is obtained.

  According to the radiation or optical imaging apparatus of the present invention, the charge voltage conversion means and the voltage signal amplification means connected to the data line only need to operate, so the charge voltage conversion means and the voltage signal not connected to the data line. The amplification means can be initialized. As described above, the charge voltage conversion means and the voltage signal amplification means that are operating and the charge voltage conversion means and the voltage signal amplification means to be initialized can be simultaneously processed in parallel by the switching connection of the second switching means. it can. Thus, a series of readings for converting the charge signal generated by the light or radiation detection means into a voltage signal can be performed at high speed.

It is a block diagram which shows the whole structure of the X-ray imaging device which concerns on an Example. It is a circuit diagram which shows the structure of the X-ray detector which concerns on an Example. It is a schematic longitudinal cross-sectional view of the X-ray conversion layer periphery part of the X-ray detector which concerns on an Example. It is a block diagram which shows the structure of the amplifier array part which concerns on an Example. It is a timing chart figure of the X-ray detection control part which concerns on an Example. It is a circuit diagram which shows the structure of the X-ray detector which concerns on the other Example of this invention. It is a circuit diagram which shows the structure of the X-ray detector which concerns on the other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... X-ray tube 3 ... X-ray plane detector 4 ... A / D converter 5 ... Image processing part 11 ... X-ray detection control part 12 ... Gate drive circuit 13 ... 1st switching part 14 ... 2nd switching part 15 ... Amplifier array section 16 ... multiplexer 23 ... voltage signal detection section 24 ... charge detection amplification circuit 25 ... low-pass filter 26 ... signal amplification circuit 27 ... sample hold circuit DU ... detection element SC ... detection surface G1 to G10 ... gate lines D1 to D10 ... Data line

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the X-ray imaging apparatus according to the embodiment, FIG. 2 is a circuit diagram showing the configuration of the X-ray detector, and FIG. 3 is the periphery of the X-ray conversion layer of the X-ray detector. FIG. 4 is a block diagram showing the configuration of the amplifier array section. In the present embodiment, X-rays will be described as an example of incident light or radiation, and an X-ray imaging apparatus will be described as an example of light or radiation imaging apparatus.

<X-ray imaging device>
The X-ray imaging apparatus according to the present embodiment performs imaging by irradiating a subject with X-rays. Specifically, an X-ray image transmitted through the subject is projected onto an X-ray conversion layer (in this embodiment, an amorphous selenium film), and carriers (charge signals) proportional to the density of the image are generated in the layer. Thus, it is converted into a charge signal.

  As shown in FIG. 1, the X-ray imaging apparatus transmits an X-ray tube 1 that irradiates a subject M to be imaged with X-rays, a top plate 2 on which the subject M is placed, and the subject M. Generates a charge signal corresponding to the X-ray dose (detects X-rays as a charge signal), converts the charge signal into a voltage signal and outputs it, and outputs from the X-ray flat detector 3 An A / D converter 4 for converting the converted voltage signal from analog to digital, an image processing unit 5 for processing the digital voltage signal converted by the A / D converter 4 to form an image, and X-ray imaging A main control unit 6 that performs various controls on the X-ray tube, an X-ray tube control unit 7 that controls the X-ray tube 1 by generating a tube voltage and a tube current based on the control of the main control unit 6, and inputs related to X-ray imaging An X-ray image obtained by processing by the input unit 8 and the image processing unit 5 that can be set is displayed. Display unit 9 for, and a storage unit 10 for storing X-ray image obtained is processed by the image processing unit 5. Further, the configuration of each part of the X-ray imaging apparatus will be described in detail.

  As shown in FIG. 2, the X-ray flat panel detector 3 includes a plurality of X-ray detection elements DU, an X-ray detection control unit 11, a gate drive circuit 12, a first switching unit 13, a second switching unit 14, and an amplifier array unit. 15 and a multiplexer 16. The plurality of X-ray detection elements DU are connected to the gate drive circuit 12 through the gate lines G1 to G10, and are connected to the amplifier array unit 15 through the first switching unit 13 and the second switching unit 14 through the data lines D1 to D10. Has been. The X-ray detection control unit 11 is connected to the gate drive circuit 12, the first switching unit 13, the second switching unit 14, the amplifier array unit 15, and the multiplexer 16.

  The X-ray detection elements DU output charge signals in response to incident X-rays, and are arranged in a vertical and horizontal two-dimensional matrix on the X-ray detection surface SC on which X-rays are incident. On the actual X-ray detection surface SC, X-ray detection elements DU are used, for example, arranged in a two-dimensional matrix in a length of about 4096 × width 4096. In FIG. 2, an X-ray detection element DU arranged in a two-dimensional matrix of 10 × 10 is shown as an example. The X-ray detection surface SC corresponds to the light or radiation detection means in the present invention.

  Further, as shown in FIG. 3, the X-ray detection element DU includes a voltage application electrode 17 for applying a high bias voltage Va, an X-ray conversion layer 18 for converting incident X-rays into charge signals, and X-ray conversion. And an active matrix substrate 19 that collects, stores, and reads (outputs) the charge signals converted in the layer 18.

  The X-ray conversion layer 18 is made of an X-ray sensitive semiconductor, and is formed of, for example, an amorphous amorphous selenium (a-Se) film. Further, when X-rays enter the X-ray conversion layer 18, a predetermined number of carriers (charge signals) proportional to the energy of the X-rays are directly generated (direct conversion type).

  As shown in FIG. 3, the active matrix substrate 19 is provided with an insulating glass substrate 20, and an X-ray conversion is performed on the glass substrate 20 based on the application of the bias voltage Va to the voltage application electrode 17. A collecting electrode 21 for collecting the charge signal converted by the layer 18, a capacitor Ca for accumulating the charge signal collected by the collecting electrode 21, a TFT 22 as a switching element, and a gate line G1 for controlling the TFT 22 from the gate drive circuit 12 To G10 and data lines D1 to D10 from which charge signals are read out from the TFTs 22 are provided.

  Next, the X-ray detection control unit 11 is controlled by the main control unit 6 (see FIG. 1). As shown in FIG. 2, the gate drive circuit 12, the first switching unit 13, the second switching unit 14, and the amplifier array unit 15 are used. And the multiplexer 16 are controlled in an integrated manner, and the charge signals detected by the X-ray detection element DU are selectively and sequentially taken out to the amplifier array unit 15 and further outputted from the multiplexer 16 in sequence. Specifically, the X-ray detection control unit 11 includes a gate operation signal for starting the operation of the gate drive circuit 12, a first switching signal for turning on / off the switch S <b> 1 of the first switching unit 13, and the second switching unit 14. The second switching signal for turning ON / OFF the switches S2 and S3, the amplifier reset signal for starting the amplifier reset of the amplifier array unit 15, and the multiplexer control signal for controlling the operation of the multiplexer 16 are output. .

  Next, the gate drive circuit 12 operates the TFT 22 of each X-ray detection element DU in order to selectively extract the charge signals detected by the X-ray detection elements DU sequentially. Based on the gate operation signal from the X-ray detection control unit 11, the gate driving circuit 12 sequentially selects the gate lines G1 to G10 connected in common for each row of the X-ray detection elements DU and sends the gate signal. . At this time, as a method for selecting the gate lines G1 to G10, there are a normal mode for selecting one line at a time and a double mode for selecting two lines together. The TFTs 22 of the X-ray detection elements DU in the selected row are switched on simultaneously by the gate signal, and carriers (charge signals) accumulated in the capacitor Ca pass through the data lines D1 to D10 to the first switching unit 13. Is output. The gate drive circuit 12 corresponds to the switching signal operating means in the present invention, and the gate signal corresponds to the switching signal in the present invention.

  Next, the first switching unit 13 connects the data lines D1 to D10 for each line via the switch S1. That is, as shown in FIG. 2, the data lines D1 and D2, D3 and D4, D5 and D6, D7 and D8, and D9 and D10 are connected via the switch S1, respectively. The switch S <b> 1 is controlled to be turned ON / OFF by the first switching signal from the X-ray detection control unit 11. In the normal mode, the switch S1 is always in the OFF state, and in the double mode, the switch S1 is always in the ON state. The first switching unit 13 corresponds to the first switching unit in the present invention.

  Next, the second switching unit 14 connects the data lines D1 to D10 and the voltage signal detection unit 23 in the amplifier array unit 15 via switches S2 and S3. The switch S2 is connected to the data lines D1, D3, D5, D7, D9 whose data lines D1 to D10 are odd-numbered lines, and the switch S3 is the data line D2, D4 whose data lines D1 to D10 are even-numbered lines. , D6, D8, and D10. When the switches S2 and S3 are in the ON state, the data lines D1 to D10 and the voltage signal detection unit 23 are connected and are in a conductive state. When the switch S2 and the switch S3 are in the OFF state, the ground line GR and the voltage signal detector 23 are connected. The switches S2 and S3 are ON / OFF controlled by the second switching signal from the X-ray detection control unit 11. The second switching unit 14 corresponds to the second switching unit in the present invention.

  Next, the amplifier array unit 15 includes a number (10 in FIG. 2) of voltage signal detection units 23 corresponding to the data lines D1 to D10 for each column of the X-ray detection elements DU. The voltage signal detection unit 23 includes a charge detection amplifier circuit (CSA: Charge Sensitive Amplifier) 24, a low-pass filter 25, a signal amplification circuit 26, and a sample hold circuit 27. The voltage signal detection unit 23 converts the charge signal read through the data lines D1 to D10 into a voltage signal, and outputs a stable voltage signal to the multiplexer 16. Detailed explanation will be given later.

  Next, the number of switches corresponding to the number of sample and hold circuits 27 is provided in the multiplexer 16. Further, the multiplexer 16 sequentially switches one of the switches to the ON state based on the multiplexer control signal from the X-ray detection control unit 11 and bundles the voltage signals output from the sample hold circuits 27 one by one. Is output to the A / D converter 4 as a time-division signal.

  Next, the A / D converter 4 samples each voltage signal of the time division signal from the multiplexer 16 at a predetermined timing, converts it to each voltage signal of a digital time division signal, and outputs it to the image processing unit 5. To do.

<Voltage signal detector>
Hereinafter, the electrical configuration of the voltage signal detector 23 will be described in detail with reference to FIG.
The voltage signal detection unit 23 receives a charge signal output from each X-ray detection element DU and converts it into a voltage signal, and a voltage signal converted by the charge detection amplification circuit 24. , A low-pass filter 25 that restricts the passage of a signal of a high-frequency band component, and a capacitor Cs1 that is a part of the low-pass filter 25, and a signal that amplifies the voltage signal that has passed through the low-pass filter 25 using the amplification element A2. An amplifier circuit 26 and a sample hold circuit 27 that samples, holds and outputs the voltage signal amplified by the signal amplifier circuit 26 at a predetermined time are provided.

  The charge detection amplifying circuit 24 is an amplifying element, and an operational amplifier A1 whose inverting input terminal is connected to the data lines D1 to D10, and a feedback capacitor Cf1 provided between the inverting input terminal and the output terminal of the operational amplifier A1. And a switch SW1 provided in parallel with the feedback capacitor Cf1. A reference voltage Vref is applied to the non-inverting input terminal of the operational amplifier A1. The reference voltage Vref is a ground level (0 [V]). The charge detection amplification circuit 24 corresponds to charge voltage conversion means in the present invention.

  Further, the switch SW1 changes to a conductive state (ON state) and a cut-off state (OFF state) based on control from the X-ray detection control unit 11. Specifically, the switch SW1 is in a conductive state for a predetermined time based on the first amplifier reset signal from the X-ray detection control unit 11. Here, when the switch SW1 is in the conductive state, the charge accumulated in the feedback capacitor Cf1 is discharged, the feedback capacitor Cf1 is reset, and the charge detection amplifier circuit 24 is initialized. Further, when the switch SW1 is turned off after a lapse of a predetermined time, the initialization state is released, and the charge signals input from the data lines D1 to D10 after this time are accumulated in the feedback capacitor Cf1. Thus, the charge detection amplifier circuit 24 is configured to output a voltage signal corresponding to the charge signal input after the time point when the initialization state is released.

  The low-pass filter 25 includes a resistor R1 connected in series with the output terminal of the operational amplifier A1 of the charge detection amplifier circuit 24, and an input capacitor Cs1 connected in series with the resistor R1. The low-pass filter 25 is configured to output a voltage signal to the signal amplifier circuit 26 in a state where the passage of the high-frequency band component signal is restricted. The input capacitor Cs1 is a part of the configuration of the low-pass filter 25 and the signal amplifier circuit 26.

  The signal amplifying circuit 26 is one of the amplifying circuits. The operational amplifier A2 is an inverting amplifier for capacitor feedback, a feedback capacitor Cf2 provided between the inverting input terminal and the output terminal of the operational amplifier A2, and the feedback. A switch SW2 provided in parallel with the capacitor Cf2 and an input capacitor Cs1 having one end connected to the inverting input terminal of the operational amplifier A2 are provided. A reference voltage Vref is applied to the non-inverting input terminal of the operational amplifier A2. The signal amplifying circuit 26 corresponds to the voltage signal amplifying means in the present invention.

  Further, the switch SW2 changes between a conduction state (ON state) and a cutoff state (OFF state) based on the control from the X-ray detection control unit 11. Specifically, the switch SW2 becomes conductive for a predetermined time based on the second amplifier reset signal from the X-ray detection control unit 11. Here, when the switch SW2 is in the conductive state, the charge accumulated in the feedback capacitor Cf2 is discharged, the feedback capacitor Cf2 is reset, and the signal amplifier circuit 26 is initialized. Further, when the switch SW2 is turned off after a predetermined time has elapsed, the signal amplification circuit 26 enters an amplification state in which the input voltage signal is inverted and amplified at a magnification factor MA = | Cs1 / Cf2 |. The signal amplifier circuit 26 including the input capacitor Cs1 and the feedback capacitor Cf2 is also a CDS (Correlated Double Sampling) circuit.

  The sample hold circuit 27 receives the voltage signal amplified by the signal amplifier circuit 26, samples the voltage signal at a predetermined time based on the sample hold control signal from the X-ray detection control unit 11, and outputs the voltage signal for a predetermined time. Is held (held), and a stable voltage signal is output to the multiplexer 16. The sample hold circuit 27 corresponds to the voltage signal holding means in the present invention.

  Regardless of whether the switch S1 is ON or OFF, a charge detection amplifier circuit (CSA) 24 connected to the data lines D1, D3, D5, D7, D9, which are odd-numbered lines, via the switch S2, a signal amplifier circuit The (CDS) 26 and the sample hold circuit (S / H) 27 are a CSA odd channel, a CDS odd channel, and an S / H odd channel, respectively. Similarly, the charge detection amplification circuit 24, the signal amplification circuit 26, and the sample hold circuit 27 connected to the data lines D2, D4, D6, D8, and D10 that are even-numbered lines via the switch S3 are respectively connected to the CSA even channel. , CDS even channel, S / H even channel.

<X-ray imaging>
Next, an operation when X-ray imaging is executed by the X-ray imaging apparatus according to the present embodiment will be described with reference to FIGS. FIG. 5 is a timing chart of the X-ray detection control unit according to the embodiment.

  First, the input unit 8 instructs to start X-ray imaging in the normal mode or the double mode. In the normal mode, the gate line is selected for each line by the gate driving circuit 12 and the charge signal for each row is read out. It is most suitable for still image shooting with plenty of image processing time.

  On the other hand, the double mode is a pixel addition mode of 2 × 2 pixel addition. A charge detection signal of a total of four pixel regions, two in the row direction and two in the column direction, is added to obtain a radiation detection signal. Since the charge signal is read every two rows and the image processing time is shortened, it is optimal for moving image shooting. Hereinafter, X-ray imaging in the double mode will be described.

  The main control unit 6 controls the X-ray tube control unit 7 and the X-ray detection control unit 11 of the X-ray flat panel detector 3 according to an instruction to start X-ray imaging from the input unit 8. The X-ray tube control unit 7 controls the X-ray tube 1 by generating tube voltage and tube current based on the control from the main control unit 6, and the subject M is irradiated with X-rays from the X-ray tube 1. Furthermore, the X-ray transmitted through the subject M is converted into a charge signal corresponding to the X-ray dose transmitted through the subject M by the X-ray detection element DU of the X-ray flat panel detector 3 and accumulated by the capacitor Ca.

  Next, referring to FIG. 5, the operation of the gate drive circuit 12 connected to each detection element DU via the gate lines G1 to G10, and the first switching unit 13 connected via the data lines D1 to D10, The operation of the second switching unit 14 and the amplifier array unit 15 and the operation of the X-ray detection control unit 11 that controls them will be described.

  Based on the control from the main control unit 6, the X-ray detection control unit 11 sends a control signal for turning on the switch S1 of the first switching unit in the double mode. As a result, the switch S1 of the first switching unit 13 is turned on, so that the data lines D1 and D2, D3 and D4, D5 and D6, D7 and D8, and D9 and D10 are connected. In this way, charge signals are read simultaneously from two columns from the pixels connected to each data line.

  The X-ray detection control unit 11 also includes switches S2 and S3 of the second switching unit 14, a switch SW1 of the charge detection amplification circuit 24 in the voltage signal detection unit 23 in the amplifier array unit 15, and a switch SW2 of the signal amplification circuit 26. ON / OFF control and sample hold control of the sample hold circuit 27 are commanded.

  First, the X-ray detection control unit 11 outputs the first amplifier reset signal and the second amplifier reset signal to the CSA odd channel and the CDS odd channel connected to the switch S2 of the second switching unit 14. By this first amplifier reset signal, the switch SW1 of the CSA odd-numbered channel is turned on and the feedback capacitor Cf1 is reset, and the CSA odd-numbered channel is initialized as shown in FIG. 5C (t1 to t2). . At this time, as shown in FIG. 5B, the switch S2 is in the OFF state. Thus, when the CSA odd channel is connected to the ground line GR via the switch S2, the CSA odd channel is initialized. Further, the switch SW2 of the CDS odd channel is turned on by the second amplifier reset signal, the feedback capacitor Cf2 is reset, and the CDS odd channel is initialized (t1 to t4). At this time, since it takes more time to initialize the signal amplifier circuit (CDS) 26 than to the charge detection amplifier circuit (CSA) 24, the initialization of the CDS odd channel is performed even after the initialization of the CSA odd channel is completed. continuing.

  Next, the switch S2 of the second switching unit 14 is turned on (t3). At this time, the CSA odd channel converts the charge signal read from the two connected data lines into a voltage signal. However, at this time, initialization of the CDS odd channel is continued. Accordingly, the input capacitor Cs1 of the CDS odd-numbered channel becomes a potential obtained by adding the potentials of the two data lines. That is, the input capacitor Cs1 changes from the ground level to a potential obtained by adding the potentials of the two connected data lines, and this is used as the base potential. As described above, when the CSA odd channel is connected to the ground line GR through the switch S2, the CDS odd channel starts to be initialized, and after the data line and the CSA odd channel are connected, the CDS odd channel is started. End initialization of.

  Next, the X-ray detection control unit 11 outputs a gate operation signal to the gate drive circuit 12. With this gate operation signal, as shown in FIG. 5A, the gate drive circuit 12 sequentially selects the gate lines every two lines. In this embodiment, description will be made assuming that two lines are selected in the order of the gate lines G1 and G2, G3 and G4,..., G9 and G10.

  First, the gate drive circuit 12 selects the gate lines G1 and G2, and each detection element DU connected to the gate lines G1 and G2 is designated. A voltage is applied to the gate of the TFT 22 of each designated detection element DU when a gate signal is sent from the gate drive circuit 12, and the ON state (t4 to t6) is obtained. Thus, carriers (charge signals) accumulated in the capacitor Ca connected to each designated TFT 22 are read out to the data lines D1 to D10 via the TFT 22.

  Further, as shown in FIGS. 5B and 5F, the switches S2 and S3 of the second switching unit 14 are alternately turned on and off for each one-line readout period Ts. When S2 is in the ON state (t3 to t8, t13 to t18), S3 is in the OFF state, and when S2 is in the OFF state (t8 to t13, t18 to t23), S3 is in the ON state. As a result, the connected voltage signal detectors 23 are alternately switched every one line readout period Ts.

  Furthermore, the switch S1 of the first switching unit 13 is in the ON state, and the voltage signal detecting unit 23 to be connected is alternately switched every one line reading period Ts in the second switching unit 14, so that for each data line The read charge signal is added every two columns.

  Then, at the time (t4) when the CDS odd channel shifts to the base potential, the switch SW2 of the CDS odd channel is turned OFF to shut off. As a result, the voltage signal converted in the CSA odd channel is amplified in the CDS odd channel.

  At this time (t4), the switches of the CSA even channel and the CDS even channel are ON, and initialization is started. The CSA even channel is initialized between t4 and t5, and the CDS even channel is initialized between t4 and t9. Thus, when the CSA even channel is connected to the ground line GR via the switch S3, the CSA even channel is initialized. In addition, when the CSA even channel is connected to the ground line GR via the switch S3, the CDS even channel starts to be initialized, and after the data line and the CSA even channel are connected, the CDS even channel is initialized. End conversion. The CSA even channel is turned off from t5 and accumulates a charge signal. However, since the switch S3 is connected to the ground line and no charge flows into the CSA even channel, the charge signal is not accumulated.

  The CDS even channel is initialized while the CDS odd channel accumulates the voltage signal. Thus, by alternately initializing the signal amplifier circuit (CDS) 26, a sufficient time for initialization is secured.

  Then, after stopping the gate operation signal to the gate drive circuit 12 (t6), the X-ray detection control unit 11 sends a sample hold control signal to the odd-numbered S / H channel. With this signal, in the S / H odd channel, as shown in FIG. 5E, the potential of the difference between the potential of the voltage signal amplified in the CDS odd channel and the base potential is sampled (t7 to t8) and once. Hold.

  Thereafter, the X-ray detection control unit 11 sends a multiplexer control signal to the multiplexer 16 (t8). With this signal, as shown in FIG. 5 (j), the voltage signal held in the odd-numbered S / H channel is output from the multiplexer 16 as a time-division signal (t8 to t11). The output voltage signal is converted from an analog value to a digital value by the A / D converter 4. Based on the converted digital signal, the image processing unit 5 performs signal processing to form a two-dimensional captured image.

  Next, after the switch S2 of the second switching unit 14 is turned off and the switch S3 is turned on (t8), the gate drive circuit 12 selects the gate lines G3 and G4 (t9). Thereafter, in the same procedure, each detection element DU connected to the gate lines G3 and G4 is designated, and carriers (charge signals) accumulated in the capacitor Ca of each designated detection element DU are represented by the data lines D1 to D1. Read to D10 (t9 to t11).

  Thus, in the next one-line readout period Ts, the CSA odd channel and the CDS odd channel are initialized, and the CSA even channel and the CDS even channel respectively perform voltage conversion and voltage signal amplification in the same manner as described above. .

  When the gate lines are selected two by two, the switches S2 and S3 of the second switching unit 14 are switched ON / OFF, whereby the charge detection amplification circuit 24 and the signal amplification circuit 26 can be initialized alternately. As a result, in the double mode, the charge signal and voltage signal added and accumulated via the two data lines can be initialized.

  Similarly, the remaining gate lines G5 to G10 are sequentially selected to read out charge signals in a two-dimensional manner. Thus, the gate driving circuit 12 sequentially selects the gate lines G1 to G10 line by line, so that the detection element DU connected to each gate line is designated, and the capacitor Ca of each designated detection element DU is specified. The accumulated carriers (charge signals) are read out to the data lines D1 to D10.

  As described above, according to this embodiment, the charge signal converted by the X-ray detection element DU can be added and read via the data line. In addition, since the voltage signal detection unit 23 connected to the data line only needs to operate, the charge detection amplification circuit 24 and the signal amplification circuit 26 in the voltage signal detection unit 23 not connected to the data line are initialized. be able to. As described above, the switching connection of the second switching unit 14 causes the operating voltage signal detection unit 23 and the charge detection amplification circuit 24 and the signal amplification circuit 26 in the voltage signal detection unit 23 to be initialized at the same time in parallel. Can be processed. Thus, the charge signal can be read out at high speed.

  Further, since the addition of the charge signal is not performed after the conversion to the voltage signal but before the conversion to the voltage signal, noise generated in the charge detection amplification circuit 24 is added to the voltage signal, and this is added to the signal amplification circuit 26. Will not amplify. As described above, since the charge signal is added before being input to the voltage signal detection unit 23, noise can be reduced as compared with the case where the voltage signal output from the voltage signal detection unit 23 is added.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In the above-described embodiment, the 2 × 2 pixel addition double mode is used. However, in order to connect or disconnect the three data lines in the first switching unit 31, the three data lines are interposed between the three data lines. Two switches S1 may be connected to implement a triple mode of 3 × 3 pixel addition. As shown in FIG. 6, the data lines D1 to D3, D4 to D6, and D7 to D9 are connected to each other, and charge signals for three pixels can be added in the row direction of the two-dimensional matrix. If gate signals are sent simultaneously from the gate drive circuit 12 to the gate lines G1 to G3, the charge signals for three pixels can be added in the column direction of the two-dimensional matrix. The gate lines G4 to G9 may be sent in order by grouping three gate lines in order. In this way, 3 × 3 pixel addition can be performed. As a result, the readout of the charge signal becomes faster, so that the image processing can be made faster. Further, if the number of switches S1 to be connected in the first switching unit 31 is increased, 4 × 4 pixel addition and more pixel additions are possible. Alternatively, the normal mode, the double mode, or the triple mode may be selected and implemented by connecting or disconnecting all the data lines with the switch S1.

(2) In the above-described embodiment, the data line is connected by the first switching unit 13 so that the initialization of the voltage signal detection unit 23 can be alternately performed every time the gate line is selected. Therefore, as shown in FIG. 7, two voltage signal detectors 23 may be provided for each data line. That is, in the first switching unit 41, one of the two connection lines 42 is connected to one data line by the switch S4. In the second switching unit 43,
The switch S5 switches the connection line 42 to the charge signal detection unit 23 and the connection between the ground line GR and the charge signal detection unit 23.

  According to this configuration, since two sets of the charge detection amplification circuit 24, the signal amplification circuit 26, and the sample hold circuit 27 are provided in parallel for one data line, the charge signal from the X-ray detection element DU is alternated. Can be read. In addition, since the charge detection amplification circuit 24 and the signal amplification circuit 26 connected to the data line need only operate, the charge detection amplification circuit 24 and the signal amplification circuit 26 not connected to the data line are initialized. Can do. In this way, by the switching connection of the first switching unit 41 and the second switching unit 43, the charge detection amplification circuit 24 and the signal amplification circuit 26 that are operating, the charge detection amplification circuit 24 and the signal amplification circuit 26 to be initialized, Can be processed simultaneously in parallel. Thus, the charge signal can be read out at high speed. Even if the gate lines are selected line by line, the voltage signal detectors 23 can be initialized alternately, so that higher quality image processing can be performed.

  (3) In the above-described embodiments, the detection element DU is an X-ray sensitive semiconductor that is sensitive to X-rays. However, if a light-sensitive semiconductor is used, an optical imaging device that can perform high-speed readout with the same configuration. Can be produced.

Claims (4)

A light or radiation imaging device,
A light or radiation detection means in which a plurality of detection elements that generate charge signals in response to light or radiation are arranged in a two-dimensional matrix;
Switching signal operating means for sending a switching signal for reading out the charge signal for each row of the two-dimensional matrix of the light or radiation detection means;
A charge-voltage converter having a feedback capacitor and converting a charge signal read from the light or radiation detector through a data line into a voltage signal;
Voltage signal amplification means for amplifying the voltage signal converted by the charge voltage conversion means;
Voltage signal holding means for sampling the voltage signal amplified by the voltage signal amplification means for a predetermined time and holding it for a predetermined time;
First switching means for connecting or blocking between the data lines;
A second switching means for switching and connecting to either the connection between the data line and the charge voltage conversion means or the connection between the ground line and the charge voltage conversion means;
By connecting the data lines by the first switching means, it is possible to simultaneously read out charge signals from the detection elements connected on a plurality of data lines ,
Light or radiation imaging characterized by resetting the feedback capacitor and erasing the charge signal of the charge voltage conversion means when the ground line and the charge voltage conversion means are connected by the second switching means apparatus. The light or radiation imaging apparatus according to claim 1 .
When the second switching means connects the ground line and the charge voltage conversion means, the voltage signal amplification means starts to be initialized,
The light or radiation imaging apparatus, wherein the initialization of the voltage signal amplifying unit is terminated after the data line and the charge voltage converting unit are connected by the second switching unit. The light or radiation imaging apparatus according to claim 1 or 2 ,
The first switching means connects or blocks the data lines two lines at a time. A light or radiation imaging device,
A light or radiation detection means in which a plurality of detection elements that generate charge signals in response to light or radiation are arranged in a two-dimensional matrix;
Switching signal operating means for sending a switching signal for reading out the charge signal for each row of the two-dimensional matrix of the light or radiation detection means;
Charge voltage conversion means for converting a charge signal read from the light or radiation detection means via a data line into a voltage signal;
Voltage signal amplification means for amplifying the voltage signal converted by the charge voltage conversion means;
Voltage signal holding means for sampling the voltage signal amplified by the voltage signal amplification means for a predetermined time and holding it for a predetermined time;
First switching means for connecting each of the data lines to one of two connection lines;
Second switching means for switching and connecting to either the connection line and the charge voltage conversion means or the ground line and the charge voltage conversion means;
An optical or radiation imaging apparatus comprising two sets of the charge voltage conversion means, the voltage signal amplification means, and the voltage signal holding means in parallel for one data line.

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