CN100579451C - Imaging apparatus, radiation imaging apparatus, and radiation imaging system - Google Patents
Imaging apparatus, radiation imaging apparatus, and radiation imaging system Download PDFInfo
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- CN100579451C CN100579451C CN200710101269A CN200710101269A CN100579451C CN 100579451 C CN100579451 C CN 100579451C CN 200710101269 A CN200710101269 A CN 200710101269A CN 200710101269 A CN200710101269 A CN 200710101269A CN 100579451 C CN100579451 C CN 100579451C
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Abstract
An imaging apparatus includes a sensor array in which a plurality of pixels each including a conversion element and a switching element are arrayed in a row direction and a column direction, signal wiring connected to a plurality of the switching elements provided in the column direction, and a reading-circuit unit connected to the signal wiring, wherein the reading-circuit unit includes a first operational area including a first amplifying circuit and a second operational area including a second amplifying circuit connected to the first operational area, and the first and second amplifying circuits are each arranged to be supplied with power within a range, the maximum of the power-supply voltage range of the first amplifying circuit being larger than the maximum of a power-supply voltage range of the second amplifying circuit.
Description
Technical field
The present invention relates to imaging device, radiation imaging apparatus and radiation imaging system.For the purpose of this description, term " lonizing radiation " also comprises electromagnetic wave, such as X ray and gamma-rays, alpha ray, β ray.
Background technology
In recent years, known dull and stereotyped photoelectric conversion device and radiation imaging apparatus comprise the area sensor array, the unformed silicon or the polysilicon film that are formed in the area sensor array on the dielectric substrate (such as glass substrate) are used as material, and are that two-dimensional array is arranged by the pixel that photo-electric conversion element and thin film transistor (TFT) (TFT) constitute.In these devices,, will in photo-electric conversion element, pass through the charge transfer of opto-electronic conversion to reading circuit unit and reading by with the matrix-style drive TFT.
Device according to correlation technique is described now.A kind of known flat area pick off comprises sensor array, is that two-dimensional array is arranged by being formed on the pixel that unformed silicon PIN photoelectric diode on the glass substrate and TFT constitute in sensor array.Drive this area sensor with matrix-style.Apply bias voltage for the public electrode side of the PIN photodiode of each pixel from power supply.The grid of the TFT of each pixel is connected to public grid line, and public grid line is connected to the grid drive circuit unit that is made of shift register etc.
On the other hand, the source electrode of each TFT is connected to the common signal distribution, and the common signal distribution is connected to the circuit unit that reads that comprises operational amplifier, sampling hold circuit, simulation multiplexer, relief area amplifier etc.
, and handle from reading the analog signal digital of circuit unit output by A/D converter by the graphics processing unit that constitutes with memorizer, processor etc.Signal after will handling then outputs to display device (such as monitor) or is stored in the recording equipment (such as hard disk).
European Patent Publication No 0796000, U.S. Patent number 5184018 and the Japan Patent spy number of opening 2004-031658 describe in detail by using aforesaid circuit unit and the grid drive circuit of reading, and obtain the dull and stereotyped photoelectric conversion device and the lonizing radiation photographic attachment of picture signal with matrix-style drive area sensor array.
All patent documentations have not only been described the basic operation of area sensor, and have described such configuration, wherein read circuit unit and comprise the first order amplifier that is connected to each common signal distribution, multiplexer etc.In some document, read circuit unit and also comprise multistage amplifier etc.In addition, these documents also disclose the example of the amplifier that is made of crystalline semiconductor.
Summary of the invention
The radiation imaging apparatus that is used for medical x-ray imaging system etc. is compared the more excellent performance of aspects such as general required power consumption characteristics, noise characteristic, dynamic range characteristics with the consumption imaging device.
Especially, in order to realize carrying out the medical x-ray imaging system of fluoroscopic image (moving image) and static imaging, although power consumption is very low, x-ray imaging system must have low noise grade and enough dynamic ranges.Yet, in the example of known technology, not necessarily satisfy all these characteristics.
For the minimizing that realizes power consumption and the minimizing of noise grade, for example, the Japan Patent spy number of opening 2004-031658 has described a kind of configuration, wherein can following change and control read supply current in each circuit region of the multistage amplifier circuit in the circuit unit.
That is, in order to reduce noise grade, in fluoroscopic image (moving image), the electric current that control offers multistage amplifier circuit increases, and in static imaging, the electric current that control offers multistage amplifier circuit reduces.According to the configuration of describing among the Japan Patent spy number of the opening 2004-031658, and in fluoroscopic image and static imaging, all provide the configuration of constant current to compare, can reduce whole power consumption.
Yet, usually, be considered to the required time of picture, that is, read the actuation duration of circuit unit, because the existence relation " time that fluoroscopic image is required " the required time of static imaging ", effect is not enough in some cases.
Especially, when top configuration is applied to mainly carry out the system of fluoroscopic image, because the heat that power consumption produces is very important, this causes because image quality decrease that the temperature increase causes or because the adverse effect that the device size that the increase cooling body brings increases.
In the above-mentioned patent documentation except the Japan Patent spy number of opening 2004-031658, the notion of power consumption characteristic itself is not described.In addition, all above-mentioned patent files are not all described the notion that reads the required dynamic range characteristics of circuit unit that is connected to the area sensor array.
As mentioned above, neither one has been described the notion that is used to improve power consumption characteristic, noise characteristic and dynamic range characteristics in the above-mentioned document, and unexposedly can realize this improved customized configuration.
In view of the foregoing make the present invention, and a kind of imaging device, a kind of radiation imaging apparatus and radiation imaging system are provided, wherein can improve power consumption characteristic, noise characteristic and dynamic range characteristics.
Imaging device of the present invention comprises: sensor array, and with arranged in arrays, each pixel comprises photo-electric conversion element and switch element to wherein a plurality of pixels on line direction and column direction; The signal wiring of a plurality of switch elements that provide on column direction is provided; And the circuit unit that reads that is connected to this signal wiring, wherein read second operating area that circuit unit comprises first operating area that comprises first amplifying circuit and comprises second amplifying circuit that is connected to first operating area, and each of first and second amplifying circuits is arranged as the electricity that is provided with in a scope, and the maximum of the power supply voltage range of first amplifying circuit is greater than the maximum of the power supply voltage range of second amplifying circuit.
Radiation imaging apparatus of the present invention comprises: with arranged in arrays, each pixel comprises conversion element and the switch element that lonizing radiation is converted to the signal of telecommunication on line direction and column direction for sensor array, wherein a plurality of pixels; The signal wiring of a plurality of switch elements that provide on column direction is provided; And the circuit unit that reads that is connected to this signal wiring, wherein read second operating area that circuit unit comprises first operating area that comprises first amplifying circuit and comprises second amplifying circuit that is connected to first operating area, and each of first and second amplifying circuits is arranged as and is provided with an electricity in the scope, and the maximum of the power supply voltage range of first amplifying circuit is greater than the maximum of the power supply voltage range of second amplifying circuit.
According to the present invention, in imaging device or radiation imaging apparatus, can reduce to read the power consumption of circuit unit, and can reduce the power consumption of whole imaging device or whole radiation imaging apparatus in addition.In addition, can reduce because the thermogenetic while that power consumption causes is realized enough dynamic ranges with low noise grade.
With reference to the accompanying drawings, from following description, will understand other features of the present invention to example embodiment.
Description of drawings
Fig. 1 is the schematic circuit diagram according to the radiation imaging apparatus of the first embodiment of the present invention;
Fig. 2 is the schematic circuit diagram that reads circuit unit that uses in the radiation imaging apparatus according to the first embodiment of the present invention;
Fig. 3 is the sectional view of the pixel of the area sensor array that uses in the radiation imaging apparatus according to the first embodiment of the present invention;
Fig. 4 A and 4B show the figure according to the operation of the radiation imaging apparatus of the first embodiment of the present invention;
Fig. 5 is the schematic circuit diagram that reads circuit unit that uses in according to a second embodiment of the present invention the radiation imaging apparatus;
Fig. 6 is the schematic circuit diagram that reads circuit unit that uses in the radiation imaging apparatus of a third embodiment in accordance with the invention;
Fig. 7 is the schematic circuit diagram of the radiation imaging apparatus of a fourth embodiment in accordance with the invention;
Fig. 8 is the schematic circuit diagram of radiation imaging apparatus according to a fifth embodiment of the invention;
Fig. 9 is the schematic circuit diagram that reads circuit unit that uses in according to a fifth embodiment of the invention the radiation imaging apparatus;
Figure 10 is the sectional view of the pixel of the area sensor array that uses in according to a fifth embodiment of the invention the radiation imaging apparatus;
Figure 11 is the schematic circuit diagram of radiation imaging apparatus according to a sixth embodiment of the invention;
Figure 12 is the view according to the x-ray imaging system of the eighth embodiment of the present invention;
Figure 13 A and 13B show the figure of the problem that will consider in radiation imaging apparatus of the present invention;
Figure 14 A each in the 14C shows the figure that reads the amplifying circuit that uses in the circuit unit according to the radiation imaging apparatus of the first embodiment of the present invention;
Figure 15 is the schematic circuit diagram of radiation imaging apparatus according to a seventh embodiment of the invention; With
Figure 16 shows the figure of the operation of radiation imaging apparatus according to a seventh embodiment of the invention.
The specific embodiment
First embodiment
Describe by what the inventor found referring now to Figure 13 A and 13B and to read the required dynamic range characteristics of circuit unit.Figure 13 A shows the pixel of sensor array and is connected to the equivalent circuit that reads circuit unit of holding wire.A plurality of pixels are connected to each signal wiring in side circuit, but have been omitted in the drawings for simplicity.The actual circuit unit that reads also comprises a plurality of amplifiers etc., but these also have been omitted.
In the drawings, the on-state voltage that the Von representative applies for the grid of TFT (switch element) from the grid drive circuit unit, and Voff represents the cut-off state voltage of applying for the grid of TFT from the grid drive circuit unit.In being connected to the operational amplifier of holding wire, represent reference voltage by Vref, and by Vdd/GND () represent supply voltage.Operational amplifier comprises capacitor C f, and the formation electric charge reads circuit.Cgs among the figure represents grid-source parasitic capacitance of TFT.
Figure 13 B is a sequential chart, shows the signal of various piece when the equivalent circuit shown in Figure 13 A moves.At first, when the RC signal became high level, the switch RC of operational amplifier closed, and the output of signal wiring and amplifier resets to Vref.After switch RC became cut-off state, TFT returned conducting state, and the signal charge that is stored in the photo-electric conversion element is transferred to the capacitor C f that reads circuit unit, and was converted into voltage.
, should be noted that when TFT returns conducting state that parasitic capacitance will be similar to interim injection of the charge Q c that is represented by equation and read circuit unit herein.The charge Q c=Cgs that injects by parasitic capacitance * (Von-Voff).
According to top equation, when the output voltage V out of first order amplifier allows TFT to return conducting state, interim satisfied following equation.
The output voltage V out=Vref-of first order amplifier (Qc/Cf)
Relation explanation by the representative of this equation: be connected to the reading in the circuit unit of area sensor array, unnecessarily reduce supply voltage in order to reduce power consumption and when TFT is returned conducting state, may cause the saturated of amplifying circuit, and make dynamic range characteristics degenerate.Therefore, the supply voltage that must careful selection reads circuit unit.
Describe the first embodiment of the present invention in detail referring now to accompanying drawing.Fig. 1 is the sketch map according to the radiation imaging apparatus of the first embodiment of the present invention.Sensor array 101 comprises positive-intrinsic-negative (PIN) photodiode 102 and thin film transistor (TFT) (TFT) 103.Each TFT comprises grid, source electrode and drain electrode.Gate driver (drive circuit unit) 104 provides voltage for the grid line (driving distribution) of each TFT103.Each reads circuit unit (reading circuit unit) 105 and comprises first area (first operating area) 106 and second area (second operating area) 107, and is connected to the holding wire (signal wiring) 108 in the source that is connected in TFT103.Each first area 106 comprises amplifier 201, and supply voltage V1 is provided (5V) for first area 106.Supply voltage V2 is provided (3.3V) for second area 1107.
Fig. 2 shows the schematic circuit diagram of the customized configuration that reads circuit unit 105 shown in Fig. 1.Fig. 4 A and 4B show the figure of the dynamic range characteristics of first embodiment.Reading circuit unit 105 is made of monolithic integrated optical circuit.First area 106 comprises operational amplifier 201, sampling and holding circuit (S/H) 203, simulation multiplexer 202, charge storage capacitance Cf and switch RC.Second area 107 comprises programmable gain amplifier 211, A/D converter 212 and logical block 213.Supply voltage V1 is provided for operational amplifier 201 and simulation multiplexer 202 in the first area 106.Supply voltage V2 is provided for programmable gain amplifier 211, A/D converter 212 and logical block 213 in the second area 107.
Voltage Von is the on-state voltage that is applied to the grid of TFT103 from gate driver 104.Voltage Voff is the cut-off state voltage that is applied to the grid of TFT103 from gate driver 104.In the operational amplifier 201 that is connected to holding wire 108, represent reference voltage by Vref, and by V1/GND () represent supply voltage.Operational amplifier 201 comprises the integrating condenser Cf that is used for charge storage, and forms the electric charge read-out amplifier.In addition, the capacitor C gs among the figure represents grid-source parasitic capacitance of TFT103.
The source electrode of each TFT103 is connected to common signal line 108, and is connected to by what operational amplifier 201, sampling and holding circuit 203, simulation multiplexer 202, programmable gain amplifier 211, A/D converter 212 etc. constituted and reads circuit unit 105.
Analogue signal is by A/D converter 212 digitizeds, and by the processing of graphics processing unit (not shown), graphics processing unit is made of memorizer, processor etc.Then, the signal after the processing outputs to display device (such as monitor), or is stored in the recording equipment (such as the hard disk (not shown)).
The light that comprises target information (subject information) incides on the area sensor array 101 from radiating element.Photodiode 102 is converted to the signal of telecommunication by opto-electronic conversion with light.In addition, the replacement switch RC that is provided in the operational amplifier 201 returns conducting state by reset signal, so that the integrating capacitor Cf of replacement operational amplifier 201 and each common signal line 108.Subsequently, apply the transmission pulse for first-line public grid line, and the TFT103 that is connected to first-line public grid line return conducting state.Therefore, by common signal line 108 signal charges that produce in the photodiode 102 are delivered to and read circuit unit 105.Charge conversion with transmission in the operational amplifier 201 that is connected to each holding wire 108 is a voltage.
Subsequently, apply sampling and inhibit signal for sampling and holding circuit 203, and to the voltage sample from operational amplifier 201 outputs.Then, the voltage with sampling remains in the electric capacity of sampling and holding circuit 203.In simulation multiplexer 202, this voltage is carried out serial conversion, and pass through programmable gain amplifier 211 as analogue signal input a/d converter 212.Is digital signal according to the resolution of A/D converter 212 with the analog signal conversion of input a/d converter 212, and as digital signal input picture processing unit.
Subsequently, by switch RC reset once more the integrating condenser Cf of operational amplifier 201 and each common signal line 108, and apply the transmission pulse for then second-line public grid line.Therefore, read electric charge in the second-line photodiode 102 by TFT103.In the grid line of the three-way and follow-up line, repeat similar operations, thereby read the electric charge of whole sensor array, that is, and the image dateout.
Fig. 3 is the sectional view of pixel of the sensor array 101 of first embodiment.Photodiode 310, TFT311 and distribution part 312 are provided on glass substrate 301.Photodiode 310 comprises top electrode layer 306, n-layer 307, semiconductor layer 309, p-layer 308, lower electrode layer 305.TFT311 comprises grid 302, drain electrode 303 and source electrode 304.Protective layer 313 covers photodiode 310, TFT311 and distribution part 312.Adhesive phase 314 is provided on protective layer 313.Luminescent coating 315 is provided on adhesive phase 314.X ray 316 is from the top incident of luminescent coating 315.Luminescent coating 315 not necessarily is provided on the adhesive phase 314, and can be formed directly on the protective layer 313 by gas deposition etc.Can use the gadolinio material (such as Gd
2O
2S:Tb or Gd
2O
3: Tb) or alkaline halide (such as cesium iodide (CsI)) form luminescent coating 315 as main material.
The PIN photodiode 310 of each pixel has such structure, and wherein lower electrode layer 305, amorphous silicon P-layer 308, amorphous si semiconductor layer 309, amorphous silicon n-layer 307 and top electrode layer 306 are stacked on the glass substrate 301.TFT311 has such structure, wherein piles up grid layer is arranged (lower electrode) 302, insulating barrier (amorphous si nitride film), amorphous si semiconductor layer, amorphous silicon n-layer, source layer (upper electrode) 304 and drain electrode layer (upper electrode) 303.Be deposited on photodiode 310, TFT311 and the distribution part 312 on the glass substrate 301 and provide protective layer 313, thereby cover its whole surface.Protective layer 313 by, for example, the amorphous si nitride film that has high-transmission rate for the lonizing radiation that will detect (X ray) 316 constitutes.Luminescent coating 315 is converted to light with X ray 316.Photodiode 310 is converted to the signal of telecommunication (electric charge) with light.Luminescent coating 315 and photodiode 310 are formed for X ray (lonizing radiation) 316 is converted to the conversion element of the signal of telecommunication.
Figure 14 A shows the sketch map that reads the amplifier that uses in the circuit unit of the radiation imaging apparatus of this embodiment.Figure 14 B and 14C show the particular circuit configuration of the amplifier shown in the sketch map that comprises Figure 14 A.Figure 14 B shows an example, and the mirror of wherein looking in the distance (telescopic) amplifier is configured to combine with MOS transistor.Figure 14 C shows the example of collapsible common source and common grid amplifier.In above-mentioned two kinds of amplifiers any can be used in above-mentioned arbitrary zone with supply voltage V1 and V2 of reading in the circuit unit.Select amplifier shown in Figure 14 B or the amplifier shown in Figure 14 C according to supply voltage, desirable characteristics (gain and dynamic range) etc.Read in the circuit unit and can use dissimilar amplifiers.In addition, can select amplifier except shown in Figure 14 B and the 14C.
With reference now to Fig. 1, the configuration of the radiation imaging apparatus of this embodiment is described.Read circuit unit 105 comprise at least run on supply voltage V1 (herein for+5V)/first area of GND 106 and run on supply voltage V2 (herein for+3.3V)/second area 107 of GND, and satisfy and concern V1＞V2.Amplifier 201 is provided in first area 106, thereby corresponding to each holding wire 108 of area sensor array 101.
In description, provide a plurality of and read circuit unit 105 (be two herein and read circuit unit 105), but this is optional this figure.The number that reads circuit unit 105 can be single or multiple.In this was described, each among supply voltage V1 and the V2 was single 5V or 3.3V power supply, but supply voltage can be a positive and negative voltage.Power range satisfy concern V1 (for example, ± 5V)＞V2 (for example, ± 3.3V).The maximum of the supply voltage scope V1 of first area 106 is greater than the maximum of the supply voltage scope V2 of second area 107.That is, the maximum of the supply voltage scope V1 of operational amplifier 201 is greater than the maximum of the supply voltage scope V2 of programmable gain amplifier 211.
Fig. 2 shows the customized configuration of using that reads circuit unit 105 in the radiation imaging apparatus of first embodiment, and shows in detail first area 106 and second area 107.In the figure, an input of first order amplifier 201 is connected to the holding wire 108 of sensor array 101, provides first order amplifier 201, sampling and holding circuit 203, simulation multiplexer 202 etc. herein in the first area 106 that drives with supply voltage V1 (being 5V).In the second area 107 that drives with supply voltage V2 (being 3.3V), provide the programmable gain amplifier 211 of reception from the output of simulation multiplexer 202, A/D converter 212 herein and for example handle the logical block 213 etc. of high-frequency clock.
In this embodiment, the circuit unit 105 that reads that comprises first area 106 and second area 107 is characterised in that reading circuit unit 105 is the integrated circuits that are monolithically formed on crystalline silicon substrate, and A/D converter 212 is provided in the second area 107, so that combine digital output.
As shown in FIG.,, compare, can significantly reduce power consumption with the situation that drives the entire portion that reads circuit unit 105 with supply voltage V1 by first area 106 that drives with supply voltage V1 and the second area 107 that drives with supply voltage V2 are provided.
In addition, when satisfying when concerning V1＞V2, can increase the gain of the first order amplifier 201 that is connected to holding wire 108.Therefore, can be configured in the noise characteristic aspect favourable read circuit unit 105.In addition, the noise characteristic aspect that is configured in that comprises the A/D converter 212 that is directly connected to programmable gain amplifier 211 also is favourable.
In addition, concern that V1＞V2 can prevent to inject cause saturated by the electric charge to first order amplifier when TFT returns conducting state, thereby realize gratifying dynamic range characteristics.
In the drawings, first order amplifier 201, sampling and the holding circuit 203, the simulation multiplexer 202 that are connected to holding wire 108 are provided in the first area 106, and programmable gain amplifier 211 and A/D converter 212 after the simulation multiplexer 202 are provided in the second area 107.This is the example of configuration favourable aspect power consumption, but the border of 107 of first area 106 and second areas is not limited to this example.In addition, as shown in Figure 2, forming high speed logic unit 213 (such as clocks) in second area 1 07 also is favourable aspect power consumption.
For simplicity, in Fig. 2, be described with circuit corresponding to two holding wires 108 (2 passage).Yet, can be monolithically formed circuit corresponding to 64 to 256 holding wires (that is 64 to 256 passages).
On the other hand, needn't be monolithically formed first area 106 and second area 107.First area 106 and second area 107 can be formed on the silicon substrate separately, and can hybrid mode form integrated circuit then.When in single encapsulation, forming integrated circuit, and on separate chip, form these regional situations and compare and to shorten distribution with hybrid mode.This is configured in external noise and the reliability aspect is favourable.
The photo-electric conversion element 102 of sensor array 101 is not limited to the amorphous silicon PIN photodiode.Photo-electric conversion element 102 can mainly be formed by polysilicon or organic material.The conversion element that is made of photo-electric conversion element 102 and luminescent coating 315 can be the conversion element of direct type, its lonizing radiation of directly changing such as X ray are electric charge, and by, for example, amorphous selenium, GaAs, gallium phosphide, lead iodide, mercuric iodixde, CdTe or CdZnTe make.
The material of TFT103 is not limited to be formed on the amorphous silicon film on the dielectric substrate.TFT (switch element) 103 can mainly be made of polysilicon or organic material.
Referring now to Fig. 4 A and 4B an embodiment is described.As shown in Fig. 4 B, the output of holding wire 108 and amplifier 201 is reset to voltage Vref by the conducting state signal of switch RC.Subsequently, when TFT103 returns conducting state, inject following charge Q c, and represent the output voltage V out of first order amplifier 201 with following equation temporarily by parasitic capacitance Cgs.
Qc＝Cgs×(Von-Voff)
Vout＝Vref-(Qc/Cf)
That is, Δ V=Qc/Cf=Cgs * (Von-Voff)/Cf is corresponding to the influence of parasitic capacitance to output.The dynamic range of supposing to be connected to the first order amplifier 201 of holding wire 108 is approximately voltage V1 (being 5V herein).In this case, read electric charge from photo-electric conversion element 102, between the supply voltage V1 of first area 106 and Δ V, satisfy relation of plane down in order to read circuit unit 105:
V1＞ΔV＝Cgs×(Von-Voff)/Cf
In addition, so that produce satisfied image, satisfy relation of plane down in order to obtain enough dynamic ranges:
V1/2≥ΔV＝Cgs×(Von-Voff)/Cf
Second embodiment
Fig. 5 is the schematic circuit diagram of radiation imaging apparatus according to a second embodiment of the present invention.The basic configuration of this embodiment is identical to those shown in Fig. 1.Only be to read the internal configurations of circuit unit 105 with different with reference to first embodiment of figure 2 descriptions.
One is not both significantly with the number corresponding to the number of holding wire 108 programmable gain amplifier 211 and A/D converter 212 is provided between this embodiment and first embodiment, and changes so that export this data with 501 pairs of numerical datas after the A/D conversion of interleaver.Replace the simulation multiplexer 202 shown in Fig. 2 interleaver 501 is provided.Interleaver 501 will be a serial signal from the conversion of signals of two A/D converters, 212 outputs, and export this signal.Supply voltage V2 is provided in second area 07, for interleaver 501.
In this embodiment, be monolithically formed first area 106 and second area 107.Electric charge read-out amplifier that is made of the operational amplifier 201 that is connected to holding wire 108 and sampling and holding circuit 203 are provided in the first area 106 that drives with supply voltage V1 (being 5V) herein.Programmable gain amplifier 211, A/D converter 212 and interleaver 501 are provided in the second area 107 that drives with supply voltage V2 (being 3.3V) herein.
The number of the A/D converter 212 among this embodiment is greater than the number among first embodiment, and therefore circuit is more complicated.Yet, because the circuit of this embodiment can reduce the speed of A/D conversion, this circuit to be configured in the noise characteristic aspect more favourable.
The 3rd embodiment
Fig. 6 is the schematic circuit diagram of the radiation imaging apparatus of a third embodiment in accordance with the invention.The basic operation of this embodiment is identical to those shown in Fig. 1.Only be the internal configurations and first embodiment that describes with reference to figure 2 and different that reads circuit unit 105 with reference to second embodiment of figure 5 descriptions.
Significantly be not both the circuit unit 105 that reads that is monolithically formed does not comprise A/D converter 212 between this embodiment and first and second embodiment one, and has the configuration of simulation output.
The 4th embodiment
Fig. 7 is the schematic circuit diagram of the radiation imaging apparatus of a fourth embodiment in accordance with the invention.The basic configuration of first embodiment is similar shown in the basic configuration of this embodiment and Fig. 1, but aspect following difference.
A bit is that radiation imaging apparatus also comprises control unit 701 except the configuration of first embodiment shown in Fig. 1 significantly in the configuration of this embodiment, and control unit 701 can carry out control, so that change supply voltage V1 and/or V2.Yet, maintain down relation of plane in this embodiment.
Be connected to each holding wire 108 of sensor array 101 with the first area 106 of supply voltage V1 driving.
Satisfy and concern V1＞V2.
Based on from for example intervalometer, temperature sensor, X ray monitor or read the signal of the output monitor (not shown) of circuit unit 105, control unit 701 can change at least one among supply voltage V1 and the V2.For example, when x-ray dose is little, or when the temperature increase of the radiation imaging apparatus that is detected by temperature sensor was big, control unit 701 control supply voltage V1 reduced.
The 5th embodiment
Fig. 8,9 and 10 is figure and views of radiation imaging apparatus according to a fifth embodiment of the invention.Fig. 8 is a schematic circuit diagram, and Fig. 9 shows the schematic circuit diagram of the details that reads circuit unit 105, and Figure 10 is the sectional view of the pixel of the area sensor array 101 that uses among the 5th embodiment.
Similar shown in Fig. 1 of the basic operation of this embodiment and first embodiment, 2 and 3, but this embodiment is different with first embodiment aspect following.
More specifically, should be noted that in this embodiment that the photo-electric conversion element of area sensor array 101 is metal-insulator semiconductor (MIS) photo-electric conversion elements 801 that formed by amorphous silicon.In addition, as shown in Figure 9, the electromotive force that should be noted that the input that is not connected to holding wire 108 in the input of operational amplifier 201 can be changed and be voltage VA or VB.
As shown in Figure 9, when driving comprises the area sensor array 101 of MIS photo-electric conversion element 801, can carry out and refresh driving, wherein the input electromotive force of the input that is not connected to holding wire 108 of operational amplifier 201 be changed into voltage VA or VB.
In this case, supply voltage V1, voltage VA and voltage VB are satisfied to concern V1 〉=VA＞VB, and wishes bigger electric potential difference between voltage VA and voltage VB.From this visual angle, the supply voltage V1 that offers first area 106 is set to be higher than the supply voltage V2 that offers second area 107.
With reference now to the sectional view of Figure 10, describes the area sensor array 101 that uses in the radiation imaging apparatus of the 5th embodiment in detail.MIS pick off 1001 has hierarchy, wherein lower electrodes (metal) layer 1002, insulating barrier 1003 (such as the amorphous si nitride film), amorphous si semiconductor layer 1004, amorphous silicon n
+-layer 1005, upper electrode (metal) layer 1006 and protective layer 313 (such as the amorphous si nitride film) with this sequence stack on glass substrate 301.
Because this embodiment describes the example of x-ray imaging device, and luminescent coating 315 is provided on protective layer 313, is adhesive phase 314 between them.Luminescent coating 315 is made by gadolinio material, cesium iodide etc.Luminescent coating 315 not necessarily is provided on the adhesive phase 314, and can be formed directly on the protective layer 313 by gas deposition etc.
The 6th embodiment
Figure 11 is the schematic circuit diagram of radiation imaging apparatus according to a sixth embodiment of the invention.In this embodiment, the pixel of area sensor array 101 comprises PIN photodiode 1101, replacement TFT1104, source follower TFT1102 and transmits TFT1103.The grid of replacement TFT1104 replacement PIN photodiode 1101 and source follower TFT1102 are so that initialisation image.The holding wire 108 of source electrode that is connected to the transmission TFT1103 of each pixel is connected to the first area of reading circuit unit 105 106 that drives with supply voltage V1.As above-mentioned other embodiment, read circuit unit 105 and also comprise the second area 107 that drives with supply voltage V2, and the satisfied V1＞V2 that concerns.
When control according to gate driver 104a, when replacement TFT1104 returns conducting state, the electric charge of replacement photodiode 1101.Photodiode 1101 produces electric charge by opto-electronic conversion, and stores this electric charge.Source follower TFT1102 output is corresponding to the voltage that is stored in the quantity of electric charge in the photodiode 1101.The control of response gate driver 104b is transmitted TFT1103 and is returned conducting state, and will be delivered to holding wire 108 from the voltage of source follower TFT1102 output.
Such aspect that is configured in of this embodiment is favourable, that is, the area sensor array 101 that has source follower TFT1102 in pixel has a large amount of output charges.
The 7th embodiment
Figure 15 is the schematic circuit diagram of radiation imaging apparatus according to a seventh embodiment of the invention.In Figure 15, with identical reference number distribute to the foregoing description in the identical assembly of assembly described, and omit detailed description to these assemblies.
The 5th embodiment shown in this embodiment and Fig. 8 is similar, but different with the 5th embodiment aspect following.
In the 5th embodiment, each pixel comprises MIS photo-electric conversion element 801 and transmits TFT103.In the present embodiment, each pixel also comprises and refreshes TFT1503.Refresh TFT1503 and refresh the MIS photo-electric conversion element, and initialisation image.As the 5th embodiment, be connected to gate driver (first drive circuit) 104 with being connected to grid line (first the drives distribution) VgT (n) that transmits TFT103 jointly.In the present embodiment, further be connected to gate driver (second drive circuit) 1504 with being connected to grid line (second the drives distribution) VgR (n) that refreshes TFT1503 jointly.
Figure 16 shows the sequential chart of the operation of present embodiment.As shown in Figure 16, in the present embodiment, provide the driving signal like this, make on-state voltage is applied to grid line VgR (n) and the interior grid line VgT (n+1) of next line in the predetermined row simultaneously.Yet, the invention is not restricted to this.The driving signal can be provided like this, make on-state voltage to be applied to grid line VgR (n) in the predetermined row and the grid line VgT (n+1) in the next line in different timings.
In the present embodiment, should be noted that following content.Compare with the 5th embodiment, parasitic capacitance CA appears at the place, cross point of the grid line VgR that is used to refresh and holding wire 108, and when refreshing TFT1503 and return conducting state, by the further iunjected charge of parasitic capacitance CA.Therefore, satisfiedly provide more obvious effect to what concern V1＞V2 in the present embodiment.
Transmit on-state voltage and the cut-off state voltage of TFT103 herein, respectively by Von1 and Voff1 representative.Represent on-state voltage and the cut-off state voltage that refreshes TFT1503 by Von2 and Voff2 respectively.When on-state voltage being applied to grid line VgR (n) in the predetermined row and the grid line VgT (n+1) in the next line in different timings, V1 being set making and satisfy relation of plane down:
V1＞Δ V1=Cgs * (V0n1-Voff1)/Cf and
V1＞ΔV2＝CA×(Von2-Voff2)/Cf
In addition, so that produce satisfied image, satisfy relation of plane down in order to obtain enough dynamic ranges:
V1/2 〉=Δ V1=Cgs * (Von1-Voff1)/Cf and
V1/2≥ΔV2＝CA×(Von2-Voff2)/Cf
When on-state voltage being applied to simultaneously grid line VgR (n) in the predetermined row and the grid line VgT (n+1) in the next line, V1 being set making and satisfy following relationship:
V1＞ΔV1+ΔV2＝(Cgs×(Von1-Voff1)/Cf)+(CA×(Von2-Voff2)/Cf)
In addition, so that produce satisfied image, satisfy relation of plane down in order to obtain enough dynamic ranges.
V1/2≥ΔV＝(Cgs×(Von1-Voff1)/Cf)+(CA×(Von2-Voff2)/Cf)
Present embodiment has been described and has been used the example of MIS photo-electric conversion element, but the invention is not restricted to this.Replacedly, can use PIN photodiode.In this case, thus TFT1503 operation replacement PIN photodiode so that initialisation image.
The 8th embodiment
Figure 12 is the system diagram according to the x-ray imaging device of the eighth embodiment of the present invention.In this embodiment, the radiation imaging apparatus of any one among first to the 7th embodiment is applied to x-ray imaging system.This x-ray imaging system is characterised in that: by area sensor array 101, gate driver 104 or gate driver 104a and 104b, read the dull and stereotyped radiation imaging apparatus that circuit unit 105 etc. constitutes and be provided in the imageing sensor 6040.Image processor 6070 control X-ray tubes (radiation source) 6050, imageing sensor 6040, display device 6080 and communication equipment 6090.
In X-ray room, X-ray tube (radiation source) 6050 produces X ray (lonizing radiation) 6060, and shines imageing sensors 6040 with X ray (lonizing radiation) 6060 by target 6062.Imageing sensor 6040 produces the image information of target 6062.
In the control room, image processor 6070 can show this image information in display device 6080, or by communication equipment 6090 image information is delivered to film processor 6100.
In medical officer's cabin, film processor 6100 can show this image information on display 6081, or prints this image information with laser printer on film 6110.
The application of the radiation imaging apparatus of any one can realize a kind of have low power consumption and the good noise characteristic and the medical x-ray imaging system of dynamic range characteristics among first to the 7th embodiment.
In addition, because low power consumption and low quantity of heat production can be realized a kind of x-ray imaging system of having restrained the image quality decrease that causes owing to heat, it does not need large-scale cooling mechanism, have high reliability, cheap and have splendid picture quality.Can reduce power consumption.In addition, can realize that a kind of being suitable for for example has enough dynamic ranges, low noise grade and restraining the radiation imaging apparatus that uses in the x-ray imaging system because the medical radiation line that the heat that power consumption causes produces is taken pictures.
Though reference example embodiment has described the present invention, be to be understood that to the invention is not restricted to disclosed example embodiment.The scope of following claim is consistent with the wideest explanation, thereby comprises all modifications, equivalent structure and function.
Claims (13)
1. imaging device comprises:
Sensor array, with arranged in arrays, each in the described pixel comprises photo-electric conversion element and switch element to wherein a plurality of pixels on line direction and column direction;
The signal wiring of a plurality of described switch elements that provide on column direction is provided; And
Be connected to the circuit unit that reads of described signal wiring,
The wherein said circuit unit that reads comprises first operating area that comprises first amplifying circuit and second operating area that comprises second amplifying circuit that is connected to first operating area, and
Each of first and second amplifying circuits is arranged as the power supply that is provided with in a scope, and the maximum of the power supply voltage range of first amplifying circuit is greater than the maximum of the power supply voltage range of second amplifying circuit.
2. imaging device as claimed in claim 1, wherein first amplifying circuit is connected to described signal wiring, and has charge storage capacitance Cf; Described switch element comprises grid, source electrode and drain electrode; Described signal wiring is connected to source electrode or the drain electrode that is arranged in a plurality of described switch elements on the column direction; And when representing the grid of described switch element and the parasitic capacitance between the source with Cgs, the on-state voltage of representing described switch element with Von, and when representing the cut-off state voltage of described switch element with Voff, the supply voltage V1 of first operating area satisfies relation of plane down:
V1＞Cgs×(Von-Voff)/Cf。
3. imaging device as claimed in claim 1, wherein first operating area and second operating area provide the integrated circuit on single silicon substrate.
4. imaging device as claimed in claim 1, wherein first operating area and second operating area provide the integrated circuit on the silicon substrate that separates.
5. imaging device as claimed in claim 1, wherein first operating area comprises operational amplifier as first amplifying circuit, the input of this operational amplifier is connected to described signal wiring.
6. imaging device as claimed in claim 5, wherein said operational amplifier constitutes the electric charge read-out amplifier, and this electric charge read-out amplifier is connected with integrating condenser.
7. imaging device as claimed in claim 5, wherein second operating area comprises the amplifier as second amplifying circuit different with the described operational amplifier in first operating area at least.
8. imaging device as claimed in claim 1, wherein second operating area comprises at least one A/D converter.
9. imaging device as claimed in claim 8 wherein provides described A/D converter with the number corresponding to the number of described signal wiring.
10. imaging device as claimed in claim 1 also comprises control unit, and this control unit can change the supply voltage of first operating area and/or the supply voltage of second operating area at least.
11. imaging device as claimed in claim 2, wherein the supply voltage V1 of first operating area satisfies relation of plane down:
V1/2≥Cgs×(Von-Voff)/Cf。
12. a radiation imaging apparatus comprises:
With arranged in arrays, each in the described pixel comprises conversion element and the switch element that lonizing radiation is converted to the signal of telecommunication on line direction and column direction for sensor array, wherein a plurality of pixels;
The signal wiring of a plurality of switch elements that provide on column direction is provided; And
Be connected to the circuit unit that reads of described signal wiring,
The wherein said circuit unit that reads comprises first operating area that comprises first amplifying circuit and second operating area that comprises second amplifying circuit that is connected to first operating area, and
Each of first and second amplifying circuits is arranged as the power supply that is provided with in a scope, and the maximum of the power supply voltage range of first amplifying circuit is greater than the maximum of the power supply voltage range of second amplifying circuit.
13. a radiation imaging system comprises:
Radiation imaging apparatus as claim 12; With
Produce the radioactive source of lonizing radiation.
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| WO2010041198A1 (en) * | 2008-10-10 | 2010-04-15 | Koninklijke Philips Electronics N.V. | Light directionality sensor |
| DE102010027791A1 (en) * | 2010-04-15 | 2011-10-20 | Siemens Aktiengesellschaft | Radiation detector for use in e.g. C-arm system for measuring incident doses of ionizing radiations, has non-marginal detector pixels distributed such that passive detector pixel is adjacently opposite to sensitive detector pixel |
| KR101916485B1 (en) * | 2011-01-17 | 2018-11-07 | 하마마츠 포토닉스 가부시키가이샤 | Solid imaging device |
| JP6494204B2 (en) * | 2014-07-17 | 2019-04-03 | キヤノン株式会社 | Radiation imaging apparatus and radiation imaging system |
| DE112016006788B4 (en) * | 2016-04-25 | 2023-12-21 | Mitsubishi Electric Corporation | Integrated semiconductor circuit, sensor reading device and sensor reading process |
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