JP2007306481A - Light or radiation imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light or radiation imaging apparatus capable of providing an image with high accuracy on the basis of digital signal the effect of noise on which is reduced. <P>SOLUTION: The light or radiation imaging apparatus is provided with an arithmetic section 37 for executing arithmetic operations by using each voltage signal of digital time division signals converted by an A/D converter 4, and the arithmetic section 37 subtracts voltage signals of all offset signals from voltage signals of all principal signals in each voltage signal of the digital time division signals converted by the A/D converter 4. That is, the arithmetic section 37 can reduce signals of the noise components included in the principal signals, and the image with high accuracy can be obtained on the basis of the digital signals the effect of noise on which is reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

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 in particular, charge from a detection element that detects light or radiation. The present invention relates to a technique for reading a signal.

  2. Description of the Related Art Conventionally, an imaging apparatus that performs imaging based on detected light or radiation includes a light or radiation detector that detects light or radiation. Here, an X-ray detector will be described as an example. The X-ray detector includes an X-ray sensitive X-ray conversion layer (X-ray conversion film). The X-ray conversion layer is converted into a carrier (charge signal) by the incidence of X-rays, and the converted charge signal X-rays are detected by reading. As this X-ray conversion layer, an amorphous selenium (a-Se) film is used.

  When X-ray imaging is performed by irradiating the subject M with X-rays, an X-ray image transmitted through the subject M is projected onto the amorphous selenium film, and a charge signal proportional to the density of the image is generated in the film. appear. After that, the charge signal generated in the film is collected by the two-dimensionally arranged carrier collecting electrodes, integrated for a predetermined time (called “accumulation time”), and then passed through the thin film transistor (TFT). And read out to the outside. Further, in order to manufacture such an X-ray detector, on a glass substrate (insulating substrate) on which a switching element composed of two-dimensionally arranged thin film transistors (TFTs) or the above-described carrier collecting electrode is patterned, It can be obtained by depositing an amorphous selenium film.

Further, the X-ray detector is, for example, a charge detection amplifier circuit (CSA: Charge Sensitive Amplifier) that converts a charge signal converted in the X-ray conversion layer into a voltage signal, and a signal that amplifies the voltage signal from the charge detection amplifier circuit. There is an amplifier circuit, a sample hold circuit that samples a voltage signal output from the signal amplifier circuit, holds (holds) the sampled voltage signal, and outputs the sampled signal (for example, see Patent Document 1). In addition, the image signals output from multiple amplifiers of the X-ray detector (two-dimensional solid state sensor) are time-divided by an analog multiplexer, and the analog signals thus time-divided are converted into digital signals by an A / D converter. There is something to do.
Japanese Patent Laying-Open No. 2004-23750 (page 7, FIG. 6)

  However, the conventional light or radiation imaging apparatus has the following problems. That is, when an analog voltage signal including noise is input to the A / D converter, a digital signal affected by the noise is output. That is, when image processing is performed based on the digital signal affected by the noise, there is a problem that a highly accurate image cannot be obtained.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a light or radiation imaging apparatus capable of obtaining a highly accurate image based on a digital signal in which the influence of noise is reduced. And

In order to achieve such an object, the present invention has the following configuration.
That is, the invention of the light or radiation imaging apparatus according to claim 1
(A) a plurality of detection means for outputting a charge signal in response to light or radiation, and (B) a plurality of charge-voltage conversion means for converting each charge signal output from the plurality of detection means into a voltage signal. (C) Each voltage signal converted by the plurality of charge voltage conversion means is input, the input voltage signals are temporally switched in a predetermined order, and converted by different charge voltage conversion means. (D) a digital time-division signal obtained by sampling each voltage signal of the time-division signal output from the multiplexer at a predetermined timing. A / D conversion means for converting each of the voltage signals, and (E) calculation means for performing calculation using each voltage signal of the digital time-division signal converted by the A / D conversion means, F) first control means for controlling the detection means to output a charge signal, and (G) the arithmetic means starts control of the detection means by the first control means. Immediately before, the offset signal that is each voltage signal of the digital time-division signal converted by the A / D conversion means, and immediately after the first control means finishes controlling the detection means, The main signal which is each voltage signal of the digital time division signal converted by the A / D conversion means is input, and in each voltage signal of the digital time division signal converted by the A / D conversion means, all The voltage signals of all offset signals are subtracted from the voltage signal of the main signal.

[Operation and Effect] The operation of the invention of claim 1 is as follows.
First, when light or radiation is incident on the detection means, the detection means outputs a charge signal in response to the incident light or radiation. Further, the charge signal output from the detection means is converted into a voltage signal by the charge voltage conversion means. Further, the multiplexer inputs each voltage signal converted by the plurality of charge voltage conversion means, temporally switches each input voltage signal in a predetermined order, and is converted by each of the different charge voltage conversion means. Each voltage signal is output to the A / D conversion means as a time-division signal that is bundled one by one. Furthermore, the A / D conversion means samples each voltage signal of the time division signal output from the multiplexer at a predetermined timing and converts it into each voltage signal of the digital time division signal, and uses each voltage signal. The calculation is performed by the calculation means.

  Here, the first control means performs control for causing the detection means to output a charge signal, and the calculation means performs A / A immediately before the first control means starts control of the detection means. The offset signal, which is each voltage signal of the digital time-division signal converted by the D conversion means, and the digital signal converted by the A / D conversion means immediately after the first control means finishes controlling the detection means. The main signal, which is each voltage signal of the time-division signal, is input, and in each voltage signal of the digital time-division signal converted by the A / D conversion means, all offsets from the voltage signals of all main signals Subtract the voltage signal of the signal.

  Therefore, the voltage signals of all offset signals are subtracted from the voltage signals of all main signals in each voltage signal of the digital time-division signal converted by the A / D conversion means. That is, the noise component signal included in the main signal can be reduced, and a highly accurate image based on the digital signal in which the influence of the noise is reduced can be obtained.

  According to a second aspect of the present invention, there is provided the light or radiation detection apparatus according to the first aspect, further comprising second control means for controlling the multiplexer to output a plurality of time division signals. It is what.

  [Operation / Effect] According to the invention of claim 2, on the basis of the control of the second control means, the multiplexer switches each voltage signal in a predetermined order in time, and each of the different charge voltage conversion means. A plurality of time-division signals obtained by bundling the converted voltage signals one by one are output. Further, the A / D conversion means converts the plurality of time division signals into digital signals. That is, the A / D conversion means inputs voltage signals of a plurality of time-division signals that are separated in time. Therefore, it is possible to reduce the influence of temporally varying noise (low frequency component), and it is possible to obtain a highly accurate image based on the digital signal in which the temporally varying noise is reduced.

  According to a third aspect of the present invention, there is provided the light or radiation imaging apparatus according to the first or second aspect, wherein the plurality of charge voltage conversion units are provided between the plurality of charge voltage conversion units and the multiplexer. For each converted voltage signal, the passage of the signal of the high frequency band component is restricted, a low pass filter having a capacitor, a plurality of signal amplifying means for amplifying each voltage signal passing through the low pass filter, and the plurality of signal amplifications And third control means for performing control to bring the means into either the initialization state or the amplification state.

  [Operation / Effect] According to the invention of claim 3, the analog signal, which is each voltage signal converted by the voltage conversion means, is restricted from passing high-frequency noise (frequency band component signal) by the low-pass filter, and the signal is amplified. It will be amplified by means. Further, the signal amplifying means can be changed from the initialized state to the amplified state under the control of the third control means. Here, in the initialized state of the signal amplifying means, the noise electric signal input to the signal amplifying means is accumulated (stored) by the capacitor. When the signal amplifying means is set in an amplified state, a voltage signal including noise converted by the charge voltage converting means is input to the signal amplifying means. Here, the signal amplifying means outputs a signal obtained by taking the difference between the electric signals accumulated in the initialization state of the signal amplifying means from the voltage signal converted by the charge voltage converting means including noise. Therefore, the signal amplifying means can remove noise from the voltage signal including noise converted by the charge voltage converting means, and the influence of the noise included in the analog voltage signal output from the charge voltage converting means can be reduced. The image can be reduced and a highly accurate image can be obtained.

  According to a fourth aspect of the present invention, there is provided a light or radiation imaging device according to a fourth aspect of the present invention, wherein a plurality of detection means for outputting a charge signal in response to light or radiation, and the respective charge signals output from the plurality of detection means. A plurality of charge-voltage conversion means for converting to a voltage signal; a low-pass filter having a capacitor for restricting the passage of a signal of a high-frequency band component for each voltage signal converted by the plurality of charge-voltage conversion means; and the low-pass filter A plurality of signal amplifying means for amplifying each voltage signal that has passed through, a third control means for controlling the plurality of signal amplifying means to either an initialization state or an amplification state, and the signal amplification means A plurality of holding means for sampling, holding and outputting each voltage signal amplified at a predetermined time, and each voltage signal held by the plurality of holding means Each of the input voltage signals is temporally switched in a predetermined order, and a multiplexer that outputs each of the voltage signals converted by different charge voltage conversion means as a time-division signal, Each voltage signal of the time division signal output from the multiplexer is sampled at a predetermined timing and converted into a digital time division signal voltage signal, and converted by the A / D conversion means. And a first control means for controlling the detection means to output a charge signal using each voltage signal of the digital time-division signal. The calculation means comprises: The digital signal converted by the A / D conversion unit based on each voltage signal held by the holding unit immediately before the first control unit starts controlling the detection unit. Based on the offset signal, which is each voltage signal of the time-division signal, and each voltage signal held by the holding means immediately after the first control means finishes controlling the detection means. The main signal, which is each voltage signal of the digital time-division signal converted by the / D conversion means, is input, and in each voltage signal of the digital time-division signal converted by the A / D conversion means, The voltage signals of all offset signals are subtracted from the voltage signal of the main signal.

[Operation / Effect] According to the invention of claim 4,
First, when light or radiation is incident on the detection means, the detection means outputs a charge signal in response to the incident light or radiation. Further, the charge signal output from the detection means is converted into a voltage signal by the charge voltage conversion means. This voltage signal passes through the low-pass filter, and each voltage signal is amplified by the signal amplification means. The holding means samples each voltage signal amplified by the signal amplifying means, holds the voltage signal for a predetermined time, and outputs it to the multiplexer. The multiplexer inputs each voltage signal held by a plurality of holding means, temporally switches the inputted voltage signals in a predetermined order, and converts each voltage signal converted by each of different charge voltage conversion means. A time-division signal that is bundled one by one is output. In the A / D conversion means, each voltage signal of the time division signal output from the multiplexer is sampled at a predetermined timing and converted into each voltage signal of a digital time division signal, and an operation is performed using each voltage signal. Calculation is performed by means.

  Here, the first control means performs control to output a charge signal to the detection means, and the calculation means further holds the holding means immediately before the first control means starts control of the detection means. Based on each voltage signal held in step 1, the offset signal which is each voltage signal of the digital time-division signal converted by the A / D conversion means, and the first control means finishes the control on the detection means Immediately after, the main signal, which is each voltage signal of the digital time-division signal converted by the A / D conversion means, is input based on each voltage signal held by the holding means, and the A / D conversion is performed. In each voltage signal of the digital time-division signal converted by the means, the voltage signals of all offset signals are subtracted from the voltage signals of all main signals.

  Accordingly, since the holding means is provided between the plurality of signal amplifying means and the multiplexer, each voltage signal held by the holding means is set immediately before the first control means starts controlling the detection means. Based on this, it can be converted into digital voltage signals by the A / D conversion means. That is, the A / D conversion means converts each voltage signal held by the holding means into each digital voltage signal during the period from when the first control means starts to control the detection means until the end. can do. Therefore, the operation can be multiplexed (pipelined), and the period can be used effectively after the first control means starts controlling the detection means until it ends, and the A / D conversion means Processing can be performed quickly.

  The analog signal, which is each voltage signal converted by the voltage conversion means, is restricted by the low-pass filter from passing high-frequency noise (frequency band component signal) and amplified by the signal amplification means. Further, the signal amplifying means can be changed from the initialized state to the amplified state under the control of the third control means. Here, in the initialized state of the signal amplifying means, the noise electric signal input to the signal amplifying means is accumulated (stored) by the capacitor. When the signal amplifying means is set in an amplified state, a voltage signal including noise converted by the charge voltage converting means is input to the signal amplifying means. Here, the signal amplifying means outputs a signal obtained by taking the difference between the electric signals accumulated in the initialization state of the signal amplifying means from the voltage signal converted by the charge voltage converting means including noise. Therefore, the signal amplifying means can remove noise from the voltage signal including noise converted by the charge voltage converting means, and the influence of the noise included in the analog voltage signal output from the charge voltage converting means can be reduced. The image can be reduced and a highly accurate image can be obtained.

  According to a fifth aspect of the present invention, there is provided the optical or radiation imaging apparatus according to any one of the first to fourth aspects, wherein the A / D converter is a voltage signal of the time-division signal output from the multiplexer. Is characterized by performing a plurality of samplings at a predetermined timing.

  [Operation and Effect] According to the invention of claim 5, the A / D conversion means performs a plurality of samplings at a predetermined timing for each voltage signal of the time-division signal output from the multiplexer. That is, the A / D conversion means performs a plurality of samplings of voltage signals that are close in time. Therefore, it is possible to reduce the influence of noise (high-frequency component) that fluctuates in a short time, and it is possible to obtain a highly accurate image based on a digital signal in which the noise that fluctuates in a short time is reduced.

  According to the present invention, the voltage signals of all offset signals are subtracted from the voltage signals of all main signals in each voltage signal of the digital time-division signal converted by the A / D conversion means. That is, the noise component signal included in the main signal can be reduced, and a highly accurate image based on the digital signal in which the influence of the noise is reduced can be obtained.

  In this embodiment, an X-ray imaging apparatus will be described as an example of a light or radiation imaging apparatus. Hereinafter, the X-ray imaging apparatus will be described in detail with reference to the drawings.

  As an example of the light or radiation imaging apparatus of Example 1, an X-ray imaging apparatus will be described. Hereinafter, the X-ray imaging apparatus will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the X-ray imaging apparatus. FIG. 2 is a block diagram showing the X-ray detector. FIG. 3 is a cross-sectional view showing the configuration of the X-ray detection element. FIG. 4 is a block diagram illustrating the charge detection unit according to the first embodiment.

  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. An X-ray detector 3 which converts the charge signal into a charge signal corresponding to the X-ray dose (detects the X-ray as a charge signal), converts the charge signal into a voltage signal and outputs the voltage signal, and is output from the X-ray detector 3 An A / D converter 4 that converts a voltage signal into a digital voltage signal, an image processing unit 5 that processes and images the digital voltage signal converted by the A / D converter 4, and various X-ray imaging-related images A main control unit 6 that controls 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 by the main control unit 6, and input settings related to X-ray imaging. An input unit 8 that can be performed, and a display unit 9 that displays an X-ray image obtained by processing by the image processing unit 5 Storage unit 10 for storing X-ray image obtained is processed by the image processing unit 5, and a like. Further, the configuration of each part of the X-ray imaging apparatus will be described in detail. The A / D converter 4 described above corresponds to the A / D conversion means in the present invention.

  The X-ray tube 1 is disposed so as to face the X-ray detector 3 with the subject M placed on the top 2 interposed therebetween. Further, as shown in FIG. 2, the X-ray detector 3 includes a plurality of X-ray detection elements 11, an X-ray detection control unit 12, a gate driver unit 13, an amplifier array unit 14, and a multiplexer 36. The plurality of X-ray detection elements 11 are connected to the gate driver unit 13 through gate lines GL1 to GL5, and are connected to the amplifier array unit 14 through data lines DL1 to DL5. Furthermore, the amplifier array unit 14 is connected to the multiplexer 36. The X-ray detection control unit 12 is connected to the gate driver unit 13 and the amplifier array unit 14.

  The X-ray detection element 11 outputs a charge signal in response to incident X-rays, and is arranged in a two-dimensional vertical and horizontal two-dimensional matrix on the X-ray detection surface S on which X-rays are incident. It has become. For example, an actual X-ray detection surface S is used in which the X-ray detection elements 11 are arranged in a two-dimensional matrix of about 4096 × width 4096. In FIG. 2, the X-ray detection elements 11 arranged in a two-dimensional matrix of 5 × 5 are shown as an example. In addition, as shown in FIG. 3, the X-ray detection element 11 includes a common electrode 15 for applying a high bias voltage, an X-ray conversion layer 16 that converts incident X-rays into a charge signal, and X-rays And an active matrix substrate 17 that collects, stores, and reads (outputs) the charge signals converted by the conversion layer 16.

  The X-ray conversion layer 16 is made of an X-ray sensitive semiconductor. For example, amorphous selenium (a-Se) is laminated on the surface of the X-ray conversion layer 16 in a planar shape. In addition, when X-rays enter the X-ray conversion layer 16, 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 17 is provided with a glass substrate 18, and on the glass substrate 18, an X-ray conversion layer 16 is applied based on a bias voltage applied from the common electrode 15. The collecting electrode 19 that collects the charge signal converted by the above, the capacitor 20 that accumulates the charge signal collected by the collecting electrode 19, the thin film transistor (TFT) 21 as a switching element, and the thin film transistor 21 from the gate driver unit 13. Gate lines GL1 to GL5 for control and data lines DL1 to DL5 from which charge signals are read out from the thin film transistor 21 are provided. The X-ray detection element 11 described above corresponds to the detection means in the present invention.

  Next, the X-ray detection control unit 12 is controlled by the main control unit 6 (see FIG. 1) and controls the gate driver unit 13, the amplifier array unit 14, and the multiplexer 36 as shown in FIG. In other words, control is performed so that the charge signals detected by all the X-ray detection elements 11 are selectively and sequentially extracted from the amplifier array section 14 and further output from the multiplexer 36 sequentially. Specifically, the X-ray detection control unit 12 includes a gate operation signal for starting the operation of the gate driver unit 13, an amplifier operation signal for starting the operation of the amplifier array unit 14, and a multiplexer control signal for controlling the operation of the multiplexer 36. Is output. The X-ray detection control unit 12 described above includes a first control unit that controls the X-ray detection element 11 to output a charge signal by starting the operation of the gate driver unit 13 in the present invention, and a multiplexer. 36 corresponds to a second control unit that performs control to output a plurality of time-division signals.

  Next, the gate driver unit 13 operates the thin film transistor 21 of each X-ray detection element 11 in order to selectively extract the charge signals detected by all the X-ray detection elements 11 sequentially. More specifically, the gate driver unit 13 sequentially operates the gate lines GL1 to GL5 for each row of the X-ray detection elements 11 based on the gate operation signal from the X-ray detection control unit 12, and this operation is performed. The thin film transistors 21 of the X-ray detection elements 11 in the column are simultaneously switched on, and the charge signal accumulated in the capacitor 20 is output to the amplifier array section 14 through the data lines DL1 to DL5. .

  Next, as shown in FIG. 2, the amplifier array unit 14 includes a number (five in FIG. 2) of charge detection units 30 corresponding to the data lines DL <b> 1 to DL <b> 5 for each column of the X-ray detection elements 11. Yes. Further, as shown in FIG. 4, each charge detection unit 30 inputs a charge signal output from each X-ray detection element 11 and converts a charge detection amplifier circuit (CSA: Charge Sensitive Amplifier) 31 that converts the signal into a voltage signal. I have. The above-described charge detection amplifier circuit 31 corresponds to the charge voltage conversion means in the present invention.

  The charge detection unit 30 in the amplifier array unit 14 shown in FIG. 2 is configured to operate based on an amplifier operation signal from the X-ray detection control unit 12. Specifically, based on the amplifier operation signal from the X-ray detection control unit 12, the charge detection amplification circuit 31 of the charge detection unit 30 shown in FIG. 4 converts the charge signal into a voltage signal and outputs it to the multiplexer 36. It is.

Furthermore, the electrical configuration of the charge detection unit 30 will be described in detail with reference to FIG. As shown in FIG. 4, the charge detection amplification circuit 31 of the charge detection unit 30 is an amplification element, an operational amplifier A1 whose inverting input terminals are connected to the data lines DL1 to DL5, and an inverting input terminal of the operational amplifier A1. And a feedback capacitor Cf ₁ provided between the output terminals, and a switch SW ₁ provided in parallel with the feedback capacitor Cf ₁ . A reference voltage Vref is applied to the non-inverting input terminal of the operational amplifier A1. The reference voltage Vref is at the ground level (0 [V]).

Further, the switch SW1 changes to a conductive state and a cut-off state based on the control from the X-ray detection control unit 12. Specifically, the switch SW1 becomes conductive for a predetermined time based on an amplifier operation signal from the X-ray detection control unit 12. Here, when the switch SW1 is conductive, the charge accumulated in the feedback capacitor Cf ₁ (charge signal) is discharged, a state in which the feedback capacitor Cf ₁ is reset, the charge detection amplifier circuit 31 is initialized It becomes a state. Furthermore, after a lapse of a predetermined time, charge signals input from the data lines DL1 to DL5 are accumulated after the switch SW1 is turned off, that is, after the initialization state is released. Therefore, the charge detection amplifier circuit 31 is configured to output a voltage corresponding to the charge signal input after the time point when the initialization state is released.

  Next, as shown in FIG. 2, the multiplexer 36 is provided with a number of switches S <b> 1 to S <b> 5 (five in FIG. 2) corresponding to the number of charge detection units 30. Further, on the basis of the multiplexer control signal from the X-ray detection control unit 12, any one of the switches S1 to S5 is sequentially switched to the ON state, and each output from the charge detection unit 30 (here, five) is output. The voltage signal (CH1 to CH5) is output to the A / D converter 4 shown in FIG.

  Next, the A / D converter 4 samples each voltage signal of the time-division signal from the multiplexer 36 at a predetermined timing and converts it into each voltage signal of a digital time-division signal. This is output to the unit 37.

  The arithmetic unit 37 has a memory inside, and temporarily stores each voltage signal of the digital time-division signal output from the A / D converter 4 in this memory, and each of the stored digital time-division signals. Calculation is performed using the voltage signal. Specifically, the arithmetic unit 37 causes the X-ray detection control unit 12 to output a gate operation signal for starting the operation of the gate driver unit 13, and the gate driver unit 13 starts controlling the X-ray detection element 11. Immediately before the output, an offset signal that is each voltage signal of the digital time-division signal converted by the A / D converter 4 and a gate operation signal that causes the X-ray detection control unit 12 to start the operation of the gate driver unit 13 are output. Immediately after the gate driver section 13 finishes controlling the X-ray detection element 11, the main signal which is each voltage signal of the digital time-division signal converted by the A / D converter 4 is input. Then, in each voltage signal of the digital time-division signal converted by the A / D conversion means, the voltage signals of all offset signals are subtracted from the voltage signals of all main signals. In addition, the calculating part 37 mentioned above is corresponded to the calculating means in this invention.

  Next, operations when X-ray imaging is executed by the X-ray imaging apparatus according to the first embodiment will be described with reference to FIGS. FIG. 5 is a diagram illustrating the control of the X-ray detection control unit according to the first embodiment and the timing at which the voltage signal is input to the A / D converter. First, as shown in FIGS. 1 to 3, when an instruction to start X-ray imaging is given at the input unit 8, the main control unit 6 controls the X-ray detection of the X-ray tube control unit 7 and the X-ray detector 3. The unit 12 is controlled. 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. Further, 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 11 of the X-ray detector 3 and accumulated by the capacitor 20.

  Next, as shown in FIG. 2, the X-ray detection control unit 12 of the X-ray detector 3 first performs charge detection amplification of the amplifier array unit 14 based on the control from the main control unit 6 (see FIG. 1). Control for causing the circuit 31 to output an amplifier operation signal is performed, and then the X-ray detection control unit 12 performs control for causing the gate driver unit 13 to output a gate operation signal. Here, in a period from when the amplifier operation signal is output to immediately before the output of the gate operation signal is started, the X-ray detection control unit 12 outputs the multiplexer control signal to the multiplexer 36, and the multiplexer shown in FIG. The operation of sequentially switching any one of the switches S1 to S5 to the ON state is repeated a plurality of times (for example, twice), and the multiplexer 36 is all shown in “multiplexer CH selection” in FIG. Two time-division signals obtained by bundling each of the voltage signals (CH1 to CH5) output from the charge detection unit 30 (for example, five indicated by numbers 1 to 5), A / D Output to the converter 4.

  Further, in the A / D converter 4, a plurality of (for example, two times) sampling is performed at a predetermined timing for each voltage signal of the two time-division signals output from the multiplexer 36. For example, sampling is performed at the timing of “x” shown in “A / D converter IN” shown in FIG. 5, sampling is performed twice for each voltage signal, and each analog voltage signal subjected to this sampling is sampled. Are sequentially converted into voltage signals of digital time-division signals and output to the calculation unit 37 of the image processing unit 5. Each voltage signal of the digital time-division signal input to the calculation unit 37 is temporarily stored in the memory of the calculation unit 37 as an offset signal.

  Next, the X-ray detection control unit 12 of the X-ray detector 3 is based on the control from the main control unit 6 (see FIG. 1), as shown in FIG. Control for outputting a gate operation signal for starting the operation of 13 is performed. Here, in the period from the end of the output of the gate operation signal to the output of the next amplifier operation signal, the gate driver unit 13 generates the X-ray based on the gate operation signal from the X-ray detection control unit 12. Any one of the gate lines GL1 to GL5 for each row of the detection elements 11 is operated, and the charge signal detected by the X-ray detection elements 11 (for example, five) corresponding to the operated gate lines is an amplifier array. The signal is input to the unit 14, further converted into a voltage signal by the charge detection amplifier circuit 31 of the amplifier array unit 14, and output to the multiplexer 36.

  Further, the X-ray detection control unit 12 outputs a multiplexer control signal to the multiplexer 36, and performs control to repeat twice the operation of sequentially switching any one of the switches S1 to S5 of the multiplexer 36 shown in FIG. The multiplexer 36 bundles one of each voltage signal (CH1 to CH5) output from all the charge detection units 30 (for example, five) shown in the “multiplexer CH selection” of FIG. Two time division signals are output to the A / D converter 4.

  Further, in the A / D converter 4, a plurality of (for example, two times) sampling is performed at a predetermined timing for each voltage signal of the two time-division signals output from the multiplexer 36. For example, sampling is performed at the timing of “x” shown in “A / D converter IN” shown in FIG. 5, sampling is performed twice for each voltage signal, and each analog voltage signal subjected to this sampling is sampled. Are sequentially converted into voltage signals of digital time-division signals and output to the calculation unit 37 of the image processing unit 5. Each voltage signal of the digital time-division signal input to the calculation unit 37 is temporarily stored in the memory of the calculation unit 37 as a main signal.

  Next, the calculation unit 37 uses the offset signal and the main signal stored in the memory of the calculation unit 37 to each voltage signal (CH1 to CH5) of the digital time-division signal converted by the A / D converter 4. ), The voltage signals of all offset signals are subtracted from the voltage signals of all main signals. Here, the main signal is a digital signal converted by the A / D converter 4 based on the charge signal detected by the X-ray detection element 11 when the subject M is irradiated with X-rays from the X-ray tube 1. In addition, a digital signal converted by the A / D converter 4 based on a noise component signal generated between the X-ray detection element 11 and the A / D converter 4 is included. The offset signal is a digital signal converted by the A / D converter 4 in a state where the charge signal detected by the X-ray detection element 11 is not output, and is a signal containing only noise components. That is, the noise component signal included in the main signal is removed by subtracting the offset signal from the main signal.

Specifically, the offset signals stored in the memory of the calculation unit 37 are X ₁ [1,1], X ₁ [2,1]... X ₅ [1,1], shown in FIG. X ₅ [2, 1] is assumed, and the main signal stored in the memory of the calculation unit 37 is Y ₁ [1, 1], Y ₁ [2, 1]... Y ₅ [1] shown in FIG. , 1], Y ₅ [2, 1], for example, in CH1,
Z = (Y ₁ [1,1] + Y ₁ [2,1] + Y ₁ [1,2] + Y ₁ [2,2]) / 4- (X ₁ [1,1] + X ₁ [2,1] + X ₁ [1,2] + X ₁ [2,2]) / 4
By performing the calculation based on the following equation, the voltage signals of all offset signals can be subtracted from the voltage signals of all main signals in CH1. Further, for CH2 to CH5 other than CH1, by substituting voltage signals corresponding to CH2 to CH5 into the above arithmetic expression, the voltage of all offset signals from the voltage signals of all main signals in CH2 to CH5. The signal can be subtracted. For example, in X ₁ [2, 1], “X” indicates an offset signal, and “ ₁ ” as a subscript of “X ₁ ” is a voltage signal of CH1 among CH1 to CH5. "2," in [2,1] indicates the second sampling of the two samplings within the same CH1 to CH5, and "1," in [2,1] It shows that it is the 1st time division signal among two time division signals. In addition, “Y” instead of “X” indicates a main signal.

  The calculation voltage signal calculated by the calculation unit 37 is further processed to be imaged by the image processing unit 5, input to the main control unit 6 as an image signal, and further subjected to image processing under the control of the main control unit 6. The image signal processed by the unit 5 is stored in the storage unit 10, and an X-ray image based on the image signal is displayed on the display unit 9.

  As described above, according to the X-ray imaging apparatus, when X-rays are incident on the X-ray detection element 11 of the X-ray detector 3, the X-ray detection element 11 is sensitive to the incident X-rays. Outputs a charge signal. Further, the charge signal output from the X-ray detection element 11 is converted into a voltage signal by the charge detection amplification circuit 31. Further, the multiplexer 36 receives the voltage signals converted by the five charge detection amplifier circuits 31, and sends the input voltage signals (CH 1 to CH 5) to any one of the switches S 1 to S 5 of the multiplexer 36. The operation of sequentially switching to the ON state is controlled, and each voltage signal converted by each of the different charge detection amplifier circuits 31 is output to the A / D converter 4 as a time division signal that is bundled. Further, the multiplexer 36 repeats the control of the operation of sequentially switching any one of the switches S1 to S5 of the multiplexer 36 to the ON state, and outputs two time division signals to the A / D converter 4. Further, the A / D converter 4 samples each voltage signal of the time division signal output from the multiplexer 36 twice at a predetermined timing and converts it into each voltage signal of a digital time division signal. Calculation is performed by the calculation unit 37 using the signal.

  Here, the X-ray detection control unit 12 performs control to output a charge signal to the X-ray detection element 11, and further, the calculation unit 37 is operated by the X-ray detection control unit 12 to the X-ray detection element 11. Immediately before starting the control, the offset signal, which is each voltage signal of the digital time-division signal converted by the A / D converter 4, and the X-ray detection control unit 12 finish controlling the X-ray detection element 11. Immediately after the input, the main signal which is each voltage signal of the digital time-division signal converted by the A / D converter 4 is input, and the digital time-division signal converted by the A / D converter 4 is input. In each voltage signal, the voltage signals of all offset signals are subtracted from the voltage signals of all main signals.

  Therefore, in each voltage signal of the digital time division signal converted by the A / D converter 4, the voltage signals of all offset signals are subtracted from the voltage signals of all main signals. That is, the noise component signal included in the main signal can be reduced, and a highly accurate image based on the digital signal in which the influence of the noise is reduced can be obtained.

  Further, based on the control of the X-ray detection control unit 12, each voltage signal is switched from the multiplexer 36 in a predetermined order in time, and one of each voltage signal converted by each of the different charge detection amplifier circuits 31. Two time-division signals that are bundled one by one are output. Further, the A / D converter 4 converts these two time division signals into digital signals. That is, the A / D converter 4 inputs the voltage signals of a plurality of time-division signals that are separated in time. Therefore, it is possible to reduce the influence of temporally varying noise (low frequency component), and it is possible to obtain a highly accurate image based on the digital signal in which the temporally varying noise is reduced.

  The A / D converter 4 samples the voltage signal of the time division signal output from the multiplexer 36 twice at a predetermined timing. That is, the A / D converter 4 performs a plurality of samplings of voltage signals that are close in time. Therefore, it is possible to reduce the influence of noise (high-frequency component) that fluctuates in a short time, and it is possible to obtain a highly accurate image based on a digital signal in which the noise that fluctuates in a short time is reduced.

  An example of the light or radiation imaging apparatus of Example 2 will be described using an X-ray imaging apparatus. Hereinafter, the X-ray imaging apparatus will be described in detail with reference to the drawings. FIG. 6 is a block diagram illustrating the charge detection unit according to the second embodiment. Detailed description of the same configuration as that of the first embodiment will be omitted.

As shown in FIG. 6, the charge detection unit 30 according to the second embodiment receives a charge signal output from each X-ray detection element 11 and converts it into a voltage signal, and the charge detection amplification circuit. Among the voltage signals converted at 31, the low-pass filter 34 that restricts the passage of the high-frequency band component signal and the capacitor CS ₁ that is a part of the low-pass filter 34, and each voltage signal that has passed through the low-pass filter 34. Are amplified using the amplification element A2, and an X-ray detection control unit 12 that controls the signal amplification circuit 32 to be in either the initialization state or the amplification state. The signal amplification circuit 32 described above corresponds to the signal amplification means in the present invention.

Furthermore, the low-pass filter 34 is formed by a resistor R _S1 connected in series with the output terminal of the operational amplifier A1 of the charge detection amplifier circuit 31, and an input capacitor C _S1 connected in series with the resistor R _S1. The low-pass filter 34 is configured to output a voltage signal to the signal amplifier circuit 32 in a state where the passage of the signal of the high frequency band component is restricted. The input capacitor C _S1 is a part of the configuration of the low-pass filter 34 and the signal amplifier circuit 32.

Signal amplifier circuit 32 is one of the amplifying element, an operational amplifier A2 is an inverting amplifier of the capacitor feedback, and the feedback capacitor Cf ₂ which is provided between the inverting input terminal and the output terminal of the operational amplifier A2, the a switch SW2 provided in parallel with the feedback capacitor Cf _2, one end to the inverting input terminal of the operational amplifier A2 is provided with an input capacitor CS ₁ connected. A reference voltage Vref is applied to the non-inverting input terminal of the operational amplifier A2.

The time constant τ = C _S1 R _S1 in the low-pass filter 34 and the signal amplification circuit 32 is such that the time T _RM for reading one time division signal output from the multiplexer 36 is T _RM > = τ.

Further, the switch SW2 changes to a conductive state and a cut-off state based on the control from the X-ray detection control unit 12. Specifically, the switch SW2 is in a conductive state for a predetermined time based on the amplifier operation signal from the X-ray detection control unit 12. Here, when the switch SW2 is in the conducting state, the residual charge in the feedback capacitor Cf ₂ is discharged, a state in which the feedback capacitor Cf ₂ is reset, the signal amplifier circuit 32 and initialized initialization state Become. Further, when the switch SW2 is turned off after a predetermined time has elapsed, the signal amplification circuit 32 enters an amplification state in which the input voltage signal is inverted and amplified and output at a magnification factor MA = | CS ₁ / Cf ₂ |. It has a configuration. The X-ray detection control unit 12 described above corresponds to the third control means in the present invention.

Next, the operation of the charge detection unit 30 in the X-ray imaging apparatus according to the second embodiment will be described with reference to FIGS. The X-ray detection control unit 12 of the X-ray detector 3 performs signal amplification with the charge detection amplification circuit 31 of the charge detection unit 30 as shown in FIG. 6 based on the control from the main control unit 6 (see FIG. 1). The circuit 32 is controlled to output an amplifier operation signal. Here, when the switch SW2 of the signal amplifier circuit 32 becomes conductive state, electrical signals of the noise input to the signal amplifier circuit 32 is accumulated (stored) by the capacitor CS _1, an initialization state. After that, the X-ray detection control unit 12 controls the switch SW2 to be in a cutoff state (amplification state), and the X-ray detection control unit 12 controls the gate driver unit 13 to output a gate operation signal. Is performed, the X-ray tube 1 irradiates the subject M with X-rays, detected by the X-ray detection element 11, and converted into a voltage signal by the charge detection amplification circuit 31. Input to the circuit 32. Here, the signal amplifier circuit 32, when the switch SW2 is conductive, and outputs a minute charge signal increased from electrical signals accumulated noise by the capacitor CS ₁ to the multiplexer 36. That is, the signal amplifying circuit 32 outputs a voltage signal converted by the charge detection amplifying circuit 31 including noise, and a difference between the electric signals accumulated in the initialization state of the signal amplifying circuit 32.

  Further, the analog signal, which is each voltage signal converted by the charge detection amplifier circuit 31, is restricted by the low-pass filter 34 from passing high-frequency noise (frequency band component signal) and amplified by the signal amplifier circuit 32. Become.

  As described above, according to the X-ray imaging apparatus, the analog signal, which is each voltage signal converted by the charge detection amplification circuit 31, is restricted by the low-pass filter 34 from passing high-frequency noise (frequency band component signal). Amplification circuit 32 amplifies. Further, the signal amplification circuit 32 can be changed from the initialized state to the amplified state under the control of the X-ray detection control unit 12. Here, in the initialization state of the signal amplifier circuit 32, the noise electric signal input to the signal amplifier circuit 32 is accumulated (stored) by the capacitor. When the signal amplification circuit 32 is set in an amplification state, a voltage signal including noise converted by the charge detection amplification circuit 31 is input to the signal amplification circuit 32. Here, the signal amplifying circuit 32 outputs a voltage signal converted by the charge detection amplifying circuit 31 including noise and taking a difference between the electric signals accumulated in the initialization state of the signal amplifying circuit 32. Therefore, the signal amplification circuit 32 can remove noise from the voltage signal including noise converted by the charge detection amplification circuit 31, and the noise included in the analog voltage signal output from the charge detection amplification circuit 31. The effect of the above can be reduced, and a highly accurate image can be obtained.

  An example of the light or radiation imaging apparatus of Example 3 will be described using an X-ray imaging apparatus. Hereinafter, the X-ray imaging apparatus will be described in detail with reference to the drawings. FIG. 7 is a block diagram illustrating the charge detection unit according to the third embodiment. FIG. 8 is a diagram for explaining the control of the X-ray detection control unit according to the third embodiment and the timing at which the voltage signal is input to the A / D converter. Detailed description of the same configurations as those of the first and second embodiments will be omitted.

  As shown in FIG. 7, the charge detection unit 30 according to the third embodiment receives a charge signal output from each X-ray detection element 11 and converts it into a voltage signal, and the charge detection amplification circuit. Of the voltage signal converted at 31, a low-pass filter 34 that restricts the passage of high-frequency band component signals and a capacitor that is a part of the low-pass filter 34, and amplifies each voltage signal that has passed through the low-pass filter 34 The signal amplifying circuit 32, the X-ray detection control unit 12 for controlling the signal amplifying circuit 32 to be in either the initialization state or the amplifying state, and each voltage signal amplified by the signal amplifying circuit 32 is sampled. A sample-and-hold circuit 33 that holds and outputs at a predetermined time is provided.

  Further, the sample hold circuit 33 receives the voltage signal amplified by the signal amplifier circuit 32 and from which the high frequency noise has been removed by the low pass filter 34, samples the voltage signal at a predetermined time, and when the predetermined time has elapsed. Is held (holded), and a stable voltage signal is output to the multiplexer 36. The sample hold circuit 33 described above corresponds to the holding means in the present invention.

  Next, the control of the X-ray detection control unit and the timing at which the voltage signal is input to the A / D converter in the X-ray imaging apparatus of Embodiment 3 will be described with reference to FIG.

  First, in FIG. 8, the X-ray detection control unit 12 sends an amplifier operation signal (H level signal in FIG. 5) to the charge detection amplification circuit 31 and the signal amplification circuit 32 of the amplifier array unit 14 during the period from t0 to t1. , And SW1 of the charge detection amplifier circuit 31 and SW2 of the signal amplifier circuit 32 are turned on, whereby the charge detection amplifier circuit 31 and the signal amplifier circuit 32 are initialized (reset). Thereafter, at time t1, the X-ray detection control unit 12 outputs an L level amplifier operation signal to SW1 of the charge detection amplification circuit 31, and sets SW1 of the charge detection amplification circuit 31 to a cutoff state. The initialization state is released. Further, at time t2, the X-ray detection control unit 12 outputs an L level amplifier operation signal also to SW2 of the charge detection amplifier circuit 31, and makes SW2 of the signal amplifier circuit 32 shut off. The initialization state is canceled (amplified state). That is, the charge detection amplifying circuit 31 and the signal amplifying circuit 32 can store a charge signal input via the data lines DL1 to DL5.

  Next, in the period from t3 to t4, the X-ray detection control unit 12 controls each sample and hold circuit 33 to sample the voltage signal of only noise output from the signal amplification circuit 32, and at time t3. The value of the voltage signal is held and output to the multiplexer 36. Further, the multiplexer 36 performs an operation of sequentially switching any one of the switches S1 to S5 to the ON state during a period from t4 to t5, and bundles the voltage signals (CH1 to CH5) one by one. The divided signal is output to the A / D converter 4. Further, the A / D converter 4 converts each voltage signal of the analog time division signal into each voltage signal of the digital time division signal.

  Similarly, in the period from t6 to t7, the X-ray detection control unit 12 controls each sample and hold circuit 33 to sample the voltage signal of only noise output from the signal amplification circuit 32, and at time t6. The value of the voltage signal is held and output to the multiplexer 36. In addition, the multiplexer 36 performs an operation of sequentially switching any one of the switches S1 to S5 to the ON state during the period from t7 to t9, and bundles the voltage signals (CH1 to CH5) one by one. The divided signal is output to the A / D converter 4. Further, the A / D converter 4 converts each voltage signal of the analog time division signal into each voltage signal of the digital time division signal.

  Next, the X-ray detection control unit 12 outputs a gate operation signal for operating any one of the gate lines GL1 to GL5 for each row of the X-ray detection elements 11 in a period from t8 to t10. Further, charge signals detected by the X-ray detection elements 11 (for example, five) corresponding to the operated gate lines are input to the amplifier array unit 14, and further, the charge detection amplification circuit 31 of the amplifier array unit 14 is used. It is converted into a voltage signal, amplified by the signal amplifier circuit 32, and input to the sample hold circuit 33.

  Therefore, in the period from t6 to t7, the time-division signal sampled by each sample and hold circuit 33 is the time period from t7 to t9 in the period from t8 to t10 when the X-ray detection control unit 12 outputs the gate operation signal. In the period up to, the A / D converter 4 converts the digital signal.

  Next, in the period from t11 to t12, the X-ray detection control unit 12 irradiates the subject M with X-rays from the X-ray tube 1 input to the sample-and-hold circuit 33. The voltage signal including noise detected by the X-ray detection element 11 and converted into a voltage signal by the charge detection amplifier circuit 31 is sampled, and the value of the voltage signal at time t11 is held, and the multiplexer 36 is caused to hold. Is output. In addition, the multiplexer 36 performs an operation of sequentially switching any one of the switches S1 to S5 to the ON state during a period from t12 to t13, and bundles the voltage signals (CH1 to CH5) one by one. The divided signal is output to the A / D converter 4. Further, the A / D converter 4 converts each voltage signal of the analog time division signal into each voltage signal of the digital time division signal.

  Similarly, the X-ray detection control unit 12 samples the voltage signal input by the sample hold circuit 33 during the period from t14 to t15, holds the value of the voltage signal at the time t14, and the multiplexer 36. Is output. In addition, the multiplexer 36 performs an operation of sequentially switching any one of the switches S1 to S5 to the ON state during a period from t15 to t16, and bundles the voltage signals (CH1 to CH5) one by one. The divided signal is output to the A / D converter 4. Further, the A / D converter 4 converts each voltage signal of the analog time division signal into each voltage signal of the digital time division signal. At time t17, the X-ray detection control unit 12 outputs an amplifier operation signal to the charge detection amplification circuit 31 and the signal amplification circuit 32 of the amplifier array unit 14.

  As described above, according to the X-ray imaging apparatus, when X-rays are incident on the X-ray detection element 11 of the X-ray detector 3, the X-ray detection element 11 is sensitive to the incident X-rays. Outputs a charge signal. Further, the charge signal output from the X-ray detection element 11 is converted into a voltage signal by the charge detection amplification circuit 31. This voltage signal passes through the low-pass filter 34 and is amplified by the signal amplification circuit 32. To do. The sample hold circuit 33 samples each voltage signal amplified by the signal amplifier circuit 32, holds the voltage signal for a predetermined time, and outputs the sampled signal to the multiplexer 36. The multiplexer 36 inputs each voltage signal held by the sample hold circuit 33, switches the inputted voltage signals in time in a predetermined order, and converts each voltage converted by each of the different charge detection amplifier circuits 31. A time-division signal obtained by bundling signals one by one is output. In the A / D converter 4, each voltage signal of the time division signal output from the multiplexer 36 is sampled at a predetermined timing and converted into a digital voltage signal of the time division signal, and each voltage signal is used. Thus, the calculation unit 37 performs the calculation.

  Here, the X-ray detection control unit 12 performs control to output a charge signal to the X-ray detection element 11, and further, the calculation unit 37 is operated by the X-ray detection control unit 12 to the X-ray detection element 11. Immediately before starting the control, based on each voltage signal held by the sample hold circuit 33, an offset signal which is each voltage signal of the digital time-division signal converted by the A / D converter 4, and X-ray detection Immediately after the control unit 12 finishes controlling the X-ray detection element 11, the digital time-division signal converted by the A / D converter 4 based on each voltage signal held by the sample hold circuit 33. In the voltage signals of the digital time-division signal converted by the A / D converter 4, the voltages of all the offset signals from all the voltage signals of the main signals are input. Subtract signal.

  Therefore, since the sample hold circuit 33 is provided between the plurality of signal amplifying circuits 32 and the multiplexer 36, the sample hold is performed immediately before the X-ray detection control unit 12 starts controlling the X-ray detection element 11. Based on each voltage signal held in the circuit 33, the A / D converter 4 can convert it into each digital voltage signal. That is, the A / D converter 4 outputs each voltage signal held by the sample hold circuit 33 during the period from when the X-ray detection control unit 12 starts control to the X-ray detection element 11 until it ends. It can be converted into digital voltage signals. Therefore, the operation can be multiplexed (pipelined), and the period can be used effectively after the X-ray detection control unit 12 starts to control the X-ray detection element 11 until it ends. The processing in the converter 4 can be performed quickly.

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

  (1) In the first to third embodiments described above, the X-ray detection control unit 12 performs control to repeat twice the operation of sequentially switching any one of the switches S1 to S5 of the multiplexer 36 shown in FIG. Although it was made to perform, you may be made to perform control repeated several times other than twice.

  (2) In the above-described first to third embodiments, each voltage signal of the two time-division signals is sampled twice at a predetermined timing, but a plurality of samplings other than two times are performed. It may be.

(3) In Examples 2 and 3 described above, with the input capacitor C _S1 and the signal amplifier circuit 32 of the low-pass filter 34, the signal amplifier circuit 32, from the voltage signal including the converted noise charge detection amplifier circuit 31 Only noise removal may be performed, and noise removal by calculation in the calculation unit 37 may not be performed. That is, even when noise removal is performed on the analog signal and noise removal is not performed on the digital signal, the influence of noise included in the analog voltage signal output from the charge detection amplification circuit 31 can be reduced, and the accuracy can be reduced. A high image can be obtained.

  (4) In the first to third embodiments described above, when the variation of each voltage signal in the offset signal is small, the A / D converter 4 does not sample each voltage signal in the offset signal, Only the sampling of the voltage signal may be performed.

  (5) Although the holding means of the above-described third embodiment has been described as the sample hold circuit 33 that holds the analog signal input at the rising timing of the control signal, the analog signal input at the falling timing of the control signal. A track hold circuit for holding the signal may be used.

  (6) In the above-described first to third embodiments, in the calculation used by the calculation means, processing is performed such that simple averaging is performed for each voltage signal, but simple addition may be performed. Further, the arithmetic means may perform frequency processing (weighting processing) on the main signal and the offset signal.

  (7) In Embodiments 1 to 3 described above, the apparatus is described as a medical device. However, the present invention may be applied to industrial fields such as non-destructive inspection, RI (Radio Isotope) inspection, and optical inspection. it can.

  (8) In the first to third embodiments described above, an X-ray imaging device is used as an example of a light or radiation imaging device. However, the present invention is not limited to X-rays, but visible light, radiation (neutron rays, γ rays, β The present invention can also be applied to an apparatus using a line or the like.

  (9) In the first to third embodiments described above, the X-ray detection elements 11 of the X-ray detector 3 have been described as being arranged in a two-dimensional matrix in the vertical and horizontal directions on the X-ray detection surface S. The detection element 11 may be a one-dimensional array of a plurality of X-ray detection elements 11.

  (10) In the first to third embodiments described above, the X-ray detection element 11 of the X-ray detector 3 has been described as a direct conversion type that converts X-rays directly into a charge signal. Alternatively, an indirect conversion type that converts light into a charge signal may be used.

It is a block diagram which shows the whole structure of an X-ray imaging device. It is a block diagram which shows an X-ray detector. It is sectional drawing which shows the structure of a X-ray detection element. FIG. 3 is a block diagram illustrating a charge detection unit according to the first embodiment. FIG. 3 is a timing chart of the voltage signal input to the control of the X-ray detection control unit and the A / D converter according to the first embodiment. FIG. 6 is a block diagram illustrating a charge detection unit according to a second embodiment. FIG. 9 is a block diagram illustrating a charge detection unit according to a third embodiment. FIG. 10 is a timing chart when a voltage signal is input to the control of the X-ray detection control unit and the A / D converter according to the third embodiment.

Explanation of symbols

4 A / D converter (A / D conversion means)
11 ... X-ray detection element (detection means)
12 ... X-ray detection control unit (first control means, second control means, third control means)
31 ... Charge detection amplification circuit (charge voltage conversion means)
32... Signal amplification circuit (signal amplification means)
33. Sample hold circuit (holding means)
34 ... Low-pass filter 36 ... Multiplexer 37 ... Calculation unit (calculation means)

Claims (5)

(A) a plurality of detection means for outputting a charge signal in response to light or radiation, and (B) a plurality of charge-voltage conversion means for converting each charge signal output from the plurality of detection means into a voltage signal. (C) Each voltage signal converted by the plurality of charge voltage conversion means is input, the input voltage signals are temporally switched in a predetermined order, and converted by different charge voltage conversion means. (D) a digital time-division signal obtained by sampling each voltage signal of the time-division signal output from the multiplexer at a predetermined timing. A / D conversion means for converting each of the voltage signals, and (E) calculation means for performing calculation using each voltage signal of the digital time-division signal converted by the A / D conversion means, F) first control means for controlling the detection means to output a charge signal, and (G) the arithmetic means starts control of the detection means by the first control means. Immediately before, the offset signal that is each voltage signal of the digital time-division signal converted by the A / D conversion means, and immediately after the first control means finishes controlling the detection means, The main signal which is each voltage signal of the digital time division signal converted by the A / D conversion means is input, and in each voltage signal of the digital time division signal converted by the A / D conversion means, all A light or radiation imaging apparatus characterized by subtracting the voltage signals of all offset signals from the voltage signal of the main signal.   2. The light or radiation imaging apparatus according to claim 1, further comprising a second control unit configured to control the multiplexer to output a plurality of time-division signals.   3. The optical or radiation imaging apparatus according to claim 1, wherein each voltage signal converted by the plurality of charge voltage conversion units has a high frequency between the plurality of charge voltage conversion units and the multiplexer. Limiting the passage of band component signals, a low-pass filter having a capacitor, a plurality of signal amplifying means for amplifying each voltage signal passing through the low-pass filter, and the plurality of signal amplifying means in an initialization state and an amplification state A light or radiation imaging apparatus, comprising: a third control unit configured to perform control to be brought into any state.   A plurality of detection means for outputting a charge signal in response to light or radiation; a plurality of charge-voltage conversion means for converting each charge signal output from the plurality of detection means into a voltage signal; and the plurality of charges For each voltage signal converted by the voltage conversion means, the low-pass filter having a capacitor for limiting the passage of the signal of the high-frequency band component, a plurality of signal amplification means for amplifying each voltage signal passed through the low-pass filter, Third control means for controlling the plurality of signal amplifying means to be in one of an initialization state and an amplification state, and each voltage signal amplified by the signal amplifying means is sampled and held for a predetermined time. A plurality of holding means for outputting, and each voltage signal held by the plurality of holding means is inputted, and the inputted voltage signals are temporally arranged in a predetermined order. In other words, a multiplexer that outputs each voltage signal converted by each of the different charge voltage conversion means as a time-division signal, and a predetermined timing for each voltage signal of the time-division signal output from the multiplexer. A / D conversion means that samples and converts each voltage signal of a digital time-division signal, and each voltage signal of the digital time-division signal converted by the A / D conversion means performs an operation. Computing means and first control means for controlling the detection means to output a charge signal, wherein the computing means starts control of the detection means by the first control means. Immediately before, based on each voltage signal held by the holding means, an offset signal which is each voltage signal of a digital time-division signal converted by the A / D conversion means, and Each voltage of the digital time-division signal converted by the A / D conversion unit based on each voltage signal held by the holding unit immediately after the one control unit finishes controlling the detection unit. The main signal, which is a signal, is input, and the voltage signals of all offset signals are subtracted from the voltage signals of all main signals in each voltage signal of the digital time-division signal converted by the A / D conversion means. A light or radiation imaging apparatus. 5. The optical or radiation imaging apparatus according to claim 1, wherein the A / D conversion unit performs a plurality of samplings at a predetermined timing for each voltage signal of the time-division signal output from the multiplexer. A light or radiation imaging apparatus characterized in that it performs.

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