CN1956490B

CN1956490B - Solid-state imaging device, method of driving solid-state imaging device and imaging apparatus

Info

Publication number: CN1956490B
Application number: CN2006101503855A
Authority: CN
Inventors: 大池祐辅; 户田淳
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 2005-10-28
Filing date: 2006-10-30
Publication date: 2012-06-20
Anticipated expiration: 2026-10-30
Also published as: JP5223953B2; JP2011259492A; CN1956490A

Abstract

A solid-state imaging device includes a pixel array area in which an unit pixel including a photoelectric conversion element converting optical signals to signal charges and a transfer gate transferring the signal charges which have been photoelectrically converted in the photoelectric conversion element is two-dimensionally arranged in a matrix form, a supply voltage control means for supplying plural first control voltages sequentially to a control electrode of the transfer gate, and a driving means for performing driving of reading out signal charges transferred by the transfer gate when the plural first control voltages are sequentially applied twice and more.

Description

The method and the imaging device of solid imaging element, driving solid imaging element

Technical field

The present invention relates to the method and the imaging device of solid imaging element, driving solid imaging element.

Background technology

In the last few years; In the CCD that is called as solid imaging element (charge coupled device) imageing sensor that is applicable to video camera, digital still video camera etc. and scale-up version imageing sensor; Through increasing the quantity of pixel under the situation that perhaps reduces picture size in high sensitivity, carried out the miniaturization of Pixel Dimensions.On the other hand, in general, the solid imaging element such as ccd image sensor or CMOS (complementary metal oxide semiconductors (CMOS)) imageing sensor often is used to various environment; Such as indoor and outdoors, day and night, therefore; Electronic shutter operations etc. usually are necessary, wherein, and according to the charge storage time in the control photo-electric conversion elements such as variation of extraneous light; Regulate the time for exposure, make that sensitivity is optimum value.

As the method for the dynamic range of extended CMOS imageing sensor, known following several method: the method for regulating the time for exposure through the high speed opening electronic shutter; To obtain at a high speed a plurality of frames and with the method for its stack; The light transfer characteristic that allows light receiving area is the method for logarithmic response etc.

But; When using the method for high speed opening electronic shutter in the image capture scene with the high-contrast of wherein area pellucida and dark space mixing mutually, be difficult to guarantee enough time for exposure, especially in the dark space; Promptly in the low-light level scene, so S/N deterioration and image quality decrease.Obtaining in a plurality of frames and the method at a high speed with its stack, compare with the method for opening electronic shutter simply, can improve S/N through superimposed image; But; Read the noise that causes owing to accumulating corresponding to repeatedly reading of multiframe, therefore, deterioration also takes place in S/N in the low-light level scene.Through logarithmic response characteristic diffusion dynamic range is that effectively still, the fixed mode noise that is caused by the transistorized changes of threshold in sub-threshold region work becomes obviously, especially in low brightness area.For example, when the window bystander being photographed from the room, if regulate sensitivity to the people, then the scene of window be saturated white and be difficult to reproduced.If the scene to window is regulated sensitivity, then the people of picked-up is dark, even because also be difficult to fully guarantee signal level and be difficult to obtain high-quality image through the amplification after the photography, so S/N reduces.

In the photography scene, necessary is, at the high S/N that realizes through time exposure in pixel with a spot of incident light on the imageing sensor, and through avoiding saturated and dynamic range expanded in the pixel that a large amount of incident lights cause.

In correlation technique; As the method that realizes high S/N (it almost is equivalent to routine operation in the pixel under the low-light level and dynamic range expanded in the pixel under the high brightness); Known a kind of IEEE International Solid-State Circuits Conference (ISSCC) 2005 that is recorded in; Pp.354, the technology in February, 2005 (non-patent document 1).Particularly; Shown in figure 40; In scale-up version imageing sensor (wherein pixel 100 is arranged to matrix form, and it comprises photodiode 101, transfering transistor 102, reset transistor 103, amplifier transistor 1104 and selects transistor 105), when transfering transistor 102 is turned off; If the electronics of storage surpasses a certain level; The voltage that then is applied to control electrode is set to level Vtrg, rather than makes the level that transistor turn-offs fully usually, and wherein unnecessary electronics is allowed to overflow to FD district 106.

When electronics is stored in the photodiode 101 and surpasses level Vtrg, then start to the leakage current in FD district 106 in the subthreshold value zone.Because leakage current is logarithmic response in the operation of subthreshold value zone so be retained in the quantity of the electronics in the photodiode 101.

Shown in figure 41, after the reset operation at period t0 place, carry out storage, voltage Vtrg is applied to the control electrode of transfering transistor 102 simultaneously.In the state of the period t1 of the negligible amounts of stored electronics, all electronics all are stored in the photodiode 101 therein, and still, when the quantity of stored electronics surpassed level Vtrg, electronics began to leak into FD district 106, as shown in the period t2.

Because the electronics leakage current in the subthreshold value zone, even when storage is proceeded (t3), electronics also is stored with the log characteristic with respect to incident intensity.At period t4, the electronics of overflow is reset in the FD district 106, and all electronics that are stored in the photodiode 101 are read through shifting fully.Relation between the quantity of incident intensity and output electronics is shown among Figure 42.Under the situation of incident intensity above the upper limit Qlinear of the range of linearity of being set by voltage Vtrg, the quantity of output electronics is confirmed by logarithmic response.

Yet, though it is reported the dynamic range that has realized 124dB in the correlation technique of in non-patent document 1, being put down in writing, the saturated level of the range of linearity of wherein realizing high S/N half the less than conventional saturated level Qs.In addition, though utilize logarithmic response to realize extremely wide dynamic range, the logarithmic response circuit often receives the influence of changes of threshold etc.; Therefore; In wide dynamic region area, still there is big fixed mode noise, wherein, even after the elimination operation of having carried out for changes of threshold; When the fixed mode noise in the range of linearity is 0.8mV, be 5mV at fixed mode noise described in the logarithm zone.

Therefore; It is desirable to, a kind of solid imaging element, a kind of method and a kind of imaging device that drives this solid imaging device are provided, wherein; Can realize under the situation of the conventional saturated level of constriction not that under low-light level the signal with linear and high S/N obtains; Simultaneously, can be dynamic range expanded with respect to incident light greater than conventional saturated level, also in the range of linearity, realize good S/N simultaneously.

Summary of the invention

According to one embodiment of present invention; A kind of solid imaging element is provided, has comprised: imaging region wherein is furnished with a plurality of pixels; Each pixel comprises photoelectric conversion section; TG transfer gate and storage area, said photoelectric conversion section are arranged to and receive incident light and produce signal charge, and said TG transfer gate is arranged to from said photoelectric conversion section read output signal electric charge; The signal that said storing section stores is read from said TG transfer gate; Wherein said TG transfer gate is read first signal charge to said storage area through incomplete transfer, and wherein said first signal charge is sent out from said storage area, and second electric charge that wherein will when said incomplete the transfer, be retained in said photoelectric conversion section is added in said photoelectric conversion section the tricharged that light produced through entering said incomplete conversion after; Wherein, read into said storage area through electric charge by said TG transfer gate with said second electric charge and tricharged addition acquisition.

According to another embodiment of the invention; A kind of imaging device is provided, has comprised: solid imaging element, said solid imaging element has imaging region; Be furnished with a plurality of pixels in the said imaging region; Each pixel comprises photoelectric conversion section, TG transfer gate and storage area, and said photoelectric conversion section is arranged to and receives incident light and produce signal charge; Said TG transfer gate is arranged to from said photoelectric conversion section read output signal electric charge, the signal that said storing section stores is read from said TG transfer gate; And control element; Be used to control said solid imaging element; Wherein said control element is to said solid imaging element supply control signal; Wherein said TG transfer gate is by the pulsed drive that produces based on said control signal; Wherein said TG transfer gate is read first signal charge to said storage area through incomplete transfer; Wherein said first signal charge is sent out from said storage area, and second electric charge that wherein will when said incomplete the transfer, be retained in said photoelectric conversion section is added to the tricharged that light produced through said incomplete conversion after, getting in said photoelectric conversion section, is wherein read into said storage area through the electric charge with said second electric charge and tricharged addition acquisition by said TG transfer gate.

Description of drawings

Fig. 1 shows the system configured allocation plan of cmos image sensor according to an embodiment of the invention;

Fig. 2 shows the circuit diagram of the instance of the circuit arrangement of supplying voltage control circuit;

Fig. 3 shows the sequential chart of the sequential relationship of the input and output in the supply voltage control circuit;

Fig. 4 A and 4B are the sequential charts that is used to explain each operation, and wherein Fig. 4 A is the situation that routine is read, and Fig. 4 B is to be the situation of target with high S/N and wide dynamic range;

Fig. 5 shows the potential energy diagram of the instance of the electromotive force in pixel when a plurality of being selected property of voltage are fed to the control electrode of transfering transistor;

Fig. 6 shows the potential energy diagram of the variation of electromotive force when a little less than the incident light;

Fig. 7 shows the potential energy diagram of the variation of electromotive force when incident intensity;

Fig. 8 is a key-drawing of after shifting for the second time, eliminating the reason of changes of threshold;

Fig. 9 shows the figure line of the relation between the quantity of time for exposure and the store electrons in light receiving area;

Figure 10 shows and is added to the figure line of experimental result that its saturated electrons quantity Qe is the quantity of the electronics that when supply voltage Vtrg, in photodiode, keeps of the supply voltage Vtrg-of control electrode of transfering transistor of the photodiode of 8800e;

Figure 11 shows the sequential chart of another instance of supply sequential of the voltage of the control electrode that is supplied to transfering transistor;

Figure 12 shows the sequential chart of another instance of supply sequential of the voltage of the control electrode that is supplied to transfering transistor;

Figure 13 is for making S/N uprise and making the key-drawing that dynamic range broadens;

Figure 14 shows the figure line of the experimental result under the predetermined condition;

Figure 15 shows the sum of the electronics that is produced that indicates incident intensity in the superincumbent experiment and the figure line through the relation between each intermediate transfer and the last quantity that shifts the electronics that is shifted as output fully;

Figure 16 A and Figure 16 B show the circuit diagram of other practical circuit of unit pixel;

Figure 17 shows the sequential chart of the operational instances when use comprises three transistorized image element circuits;

Figure 18 shows and is shifting period and the electronic shutter electromotive force relation in the period and the sequential chart of concrete sequential relationship fully;

Figure 19 shows at the electromotive force relation of intermediate transfer in the period and the sequential chart of concrete sequential relationship;

Figure 20 A shows the potential energy diagram of the electromotive force relation when each sequential to Figure 20 F;

Figure 21 A is the potential energy diagram in the intermediate transfer to Figure 21 D;

Figure 22 shows the figure line of the corresponding relation between the incident intensity and signal charge in intermediate transfer;

Figure 23 shows the sequential chart according to the operational instances 1 of an application of the present invention;

Figure 24 shows in the situation of operational instances 1 at the electromotive force relation of intermediate transfer in the period and the sequential chart of concrete sequential relationship;

Figure 25 shows in the situation of operational instances 1 and to shift period and the electronic shutter electromotive force relation in the period and the sequential chart of concrete sequential relationship fully;

Figure 26 shows the sequential chart according to the operational instances 2 of application of the present invention;

Figure 27 has gone out in the situation of operational instances 2 at intermediate transfer period and the electronic shutter electromotive force relation in the period and the sequential chart of concrete sequential relationship;

Figure 28 shows the sequential chart according to the operational instances 3 of application of the present invention;

Figure 29 shows the sequential chart according to the operational instances 4 of application of the present invention;

Figure 30 is the sequential chart that forces operated in saturation;

Figure 31 A is the potential energy diagram in utilizing the reading of intermediate transfer to Figure 31 D;

Figure 32 A is the potential energy diagram in forcing operated in saturation and intermediate transfer to Figure 32 E;

Figure 33 shows the block diagram of the system configuration of the compensate function that comprises pixel fixed mode noise;

Figure 34 A and Figure 34 B show the potential energy diagram of the instance when being applied to ccd image sensor;

Figure 35 is the sketch map of improvement instance 1 of the present invention;

Figure 36 shows the figure line of the instance of incandescent lamp spectrum;

Figure 37 is the sketch map of improvement instance 2 of the present invention;

Figure 38 is the sketch map of improvement instance 3 of the present invention;

Figure 39 shows the block diagram of the profile instance of imaging device according to an embodiment of the invention;

Figure 40 is the circuit diagram of instance of the circuit arrangement of pixel;

Figure 41 is the potential energy diagram in the correlation technique of in non-patent document 1, putting down in writing; With

Figure 42 shows in non-patent document 1 figure line of the relation between the quantity of incident intensity and output electronics in the correlation technique of record.

Embodiment

Below with reference to accompanying drawing illustrated in detail embodiments of the invention.

Fig. 1 shows the system configured allocation plan of solid imaging element according to an embodiment of the invention (for example, cmos image sensor).

As shown in Figure 1, comprise pixel array region 11 according to the cmos image sensor of this embodiment, wherein, comprise that unit pixel (after this, the abbreviating " pixel " sometimes as) 20 of photo-electric conversion element is arranged in this pixel array region 11 with matrix form two-dimentionally; Cmos image sensor also comprises vertical scanning circuit 12, supply voltage control circuit 13, voltage supply circuit 14, timing generator circuit (TG) 15, a plurality of column circuits 16, horizontal scanning circuit 17 and column signal selection circuit 18 as its peripheral circuit.

In the arranged of the pixel 20 in pixel array region 11, arrange vertical signal line 111, arrange the drive controlling line, for example shift control line 112, the control line 113 that resets, select control line 114 at each row at each row.In addition, each unit pixel 20 is arranged the reset line 115 of supply resetting voltage Vrst.

(unit pixel)

The instance of the circuit arrangement of unit pixel 20 has been shown in Fig. 1.Unit pixel 20 according to practical circuit has image element circuit, and this image element circuit comprises the for example photo-electric conversion element of photodiode 21, comprises transfering transistor 22, reset transistor 23, amplifier transistor 24 in addition and selects 25 4 transistors of transistor.In the case, for example the N-channel MOS transistor is used as such transistor 22-25.

Transfering transistor 22 is equal to the TG transfer gate in the claim, and it is connected the cathode electrode of photodiode 21 and as the FD district (floating diffusion region) of charge/voltage transducer between 26.Transfer to FD district 26 by photodiode 21 opto-electronic conversion and signal charge that be stored in transfering transistor 22 (electronics in the case) through the transfer pulse TRG that offers gate electrode (control electrode).

At signal charge before the transfer in photodiode 21 to FD districts 26; The reset pulse RST of reset transistor 23 through offering gate electrode resets to resetting voltage Vrest with the electromotive force in FD district 26; Wherein in reset transistor 23; Drain electrode is connected to reset line 115, and the source electrode is connected to FD district 26.

The electromotive force in the amplifier transistor 24 FD districts 26 of output after being resetted by reset transistor 23 is as reset level; And the electromotive force in the FD district 26 of output after signal charge is shifted by transfering transistor 22 is as signal level; Wherein in amplifier transistor 24; Gate electrode is connected to FD district 26, and drain electrode is connected to pixel power supply Vdd.

Select transistor 25 to become conducting state through strobe pulse SEL is provided to gate electrode; And make pixel 20 become selected state; To output to vertical signal line 111 from the signal of amplifier transistor 24 outputs; Wherein in selecting transistor 25, drain electrode is connected to the source electrode of amplifier transistor 24, and the source electrode is connected to vertical signal line 111.

Further preferably, select transistor 25 to use following configuration, wherein this transistor is connected between the drain electrode of pixel power supply Vdd and amplifier transistor 24.

Vertical scanning circuit 12 comprises shift register, address decoder etc.; It is through suitably generating reset pulse RST, shift pulse TRG and strobe pulse SEL etc., to each electronic shutter capable with read vertically each pixel in the scanning element array region 11 line by line of row.Capable for electronic shutter, carry out the electronic shutter operation of the signal of the pixel 20 be used for removing this row, for reading row, carry out the read operation of the signal of the pixel 20 that is used for reading this row.

Though not this illustrate; But vertical scanning circuit 12 is in the pixel of selecting successively with behavior unit 20; Has the reading scan system; Be used for carrying out the read operation of the signal of reading each capable pixel 20, and have the electronic shutter scanning system, be used for carrying out electronic shutter operation for same delegation (electronic shutter is capable) than Zao time of the reading scan of being undertaken by the reading scan system corresponding to shutter speed.

Then; From when by the unnecessary electric charge of electronic shutter scanning system through shutter scan reset photodiode 21 the time be carved into when the period that read the moment of the signal in the pixel 20 by the reading scan system through reading scan, become the storing time intervals (exposure period) of the signal charge in the pixel 20.In other words, electronic shutter operation is represented following operation, this operation reset (removing) be stored in the signal charge and the new signal charge of beginning after accumulation resets of photodiode 21.

The control voltage of the gate electrode (control electrode) of the transfering transistor 22 of supply voltage control circuit 13 control supply (applying) in the unit pixel 20.The concrete configuration of supply voltage control circuit 13 will be described later.

Voltage supply circuit 14 be in to the supply of supply voltage control circuit 13 a plurality of voltages (control voltage) the centre position voltage (after this; Be sometimes referred to as " intermediate voltage "), said a plurality of voltages (control voltage) have the different voltages with different value, specifically are; Be in the voltage (after this being called " H " level) of high level; It is pixel power source voltage level Vdd, and low level voltage (after this being called " L " level), and it is a ground level.The voltage that mediates (intermediate voltage) is to be stored in wherein that part of charge in the photodiode 21 is held and the remainder of stored charge is partly transferred to the voltage in FD district 26.

Timing sequencer (TG) 15 generates clock signal PTRG1, PTRG2, PTRG3 (with reference to figure 2), is used for confirming the timing of supply voltage control circuit 13 to the gate electrode supply control voltage of transfering transistor 22.

Each pixel column in pixel array region 11; Promptly arrange column circuits 16 correspondingly with respect to pixel column; To signal processing, and after signal processing, keep picture element signal provisionally from putting rules into practice through the selected signal of reading each pixel 20 process vertical signal lines 11 outputs the row of vertical scanning by vertical scanning circuit 12.

As column circuits 16; There is the circuit arrangement that comprises sample-hold circuit; Wherein said sample-hold circuit sampling and maintenance are through the signal of vertical signal line 111 outputs; And having the circuit arrangement that comprises sample-hold circuit and noise suicide circuit, wherein said noise suicide circuit is handled through correlated-double-sampling (CDS) and is eliminated the distinctive fixed mode noise such as the changes of threshold of amplifier transistor 24 of pixel or the noise that resets.Notice that these only are instances, and said circuit is not limited to these.For example, further preferably, column circuits 16 has A/D (analog to digital) translation function, to adopt the configuration through the digital signal output signal level.

Horizontal scanning circuit 17 comprises shift register, address decoder etc., and sequential scanning flatly is arranged in the column circuits 16 of each pixel column in the pixel array region 11.Column signal selects circuit 18 to comprise horizontal selector switch, horizontal signal lines etc., and output sequentially is stored in the picture element signal in the column circuits 16 temporarily, and makes the horizontal sweep of itself and horizontal scanning circuit 17 synchronous.

Constant-current source 19 is connected to each end of vertical signal line 111.For example, can use biased transistor to replace constant-current source 19.To in the sequential control circuit that does not illustrate, produce as the clock signal and the control signal of the operation standard of vertical scanning circuit 12, timing generator circuit 15, column circuits 16, horizontal scanning circuit 17 etc.

(supply voltage control circuit)

Supply voltage control circuit 13 utilizes address signal ADR as input; It drives the row of being selected and being scanned by vertical scanning circuit 12; And through selecting voltage based on clock signal PTRG1, PTRG2, PTRG3 from timing generator circuit 15 supplies; The voltage of the gate electrode supply of the transfering transistor 22 in unit pixel 20 from a plurality of first control voltages of voltage supply circuit 14 supply, said a plurality of first control voltages for example are four voltage Vtrg1, Vtrg2, Vtrg3 and Vtrg4 (Vtrg1＞Vtrg2＞Vtrg3＞Vtrg4).

Fig. 2 shows the circuit diagram of the profile instance of supply voltage control circuit 13.As shown in Figure 2, comprise four circuit block 131-134 according to the supply voltage control circuit 13 of this embodiment, it is corresponding to four voltages (intermediate voltage) Vtrg1, Vtrg2, Vtrg3 and Vtrg4, and comprises the NOR circuit 135 with three inputs.Address signal ADR together is provided to circuit block 131-134 from vertical scanning circuit 12.Clock signal PTRG1, PTRG2, PTRG3 are provided for NOR circuit 135, as three inputs from voltage supply circuit 14.

Circuit block 131 comprises and adopts address signal ADR and the clock signal PTRG1 NAND circuit 1311 as two inputs; Level phase-shifter 1312 and P-channel driver transistors 1313, its selected voltage Vtrg1 (said voltage Vtrg1 is higher than the supply voltage of logical circuit) and it is fed to the gate electrode of transfering transistor 22.

Circuit block 132 comprises and adopts address signal ADR and clock signal PTRG2 AND circuit 1321 and the P-channel driver transistors 1322 as two inputs; Its selected voltage Vtrg2 (said voltage Vtrg2 is identical or lower with the supply voltage of logical circuit, and exceeds the transistorized threshold value of PMOS at least than ground voltage) and it is fed to the gate electrode of transfering transistor 22.

Circuit block 133 comprises and adopts address signal ADR and clock signal PTRG3 NAND circuit 1331 and the N-channel driver transistors 1332 as two inputs; Its selected voltage Vtrg3 (said voltage Vtrg3 is identical or higher with the ground voltage of logical circuit, and hangs down the threshold value of nmos pass transistor at least than supply voltage) and it is fed to the gate electrode of transfering transistor 22.

Circuit block 134 comprises the AND circuit 1341 of the output of employing address signal ADR and NOR circuit 135 as two inputs; Adopt address signal ADR to import and adopt the OR circuit 1342 of the output signal of AND circuit as one (bearing) as another input; Level phase-shifter 1343 and N-channel driver transistors 1344, its selected voltage Vtrg4 (said voltage Vtrg4 hangs down ground voltage) and it is fed to the gate electrode of transfering transistor 22.

Circuit block 134 has the circuit arrangement that is independent of other circuit block 131,132 and 133 operations through the operation of NOR circuit 135, so that the voltage that supply is lower than ground voltage is (for example-0.1V), as the voltage that is used to turn-off transfering transistor 22.

Sequential relationship between the input and output in the supply voltage control circuit 13 has been shown in Fig. 3.Voltage at the gate electrode that will be supplied to transfering transistor 22 is in the situation of Vtrg1, Vtrg2, Vtrg3 and Vtrg4; When through address signal ADR select row; According to clock signal PTRG1, PTRG2 and PTRG3; Voltage Vtrg1, Vtrg2 and Vtrg3 corresponding to each clock signal are supplied, and voltage Vtrg4 is supplied to other row.

Subsequently, with the operation of the sequential chart explanation of using Fig. 4 A and 4B according to the cmos image sensor 10 of the embodiment of top configuration.Fig. 4 A and 4B show the sequential relationship in each operation, are the situation that routine is read among Fig. 4 A wherein, are to be the situation of target with high S/N and wide dynamic range among Fig. 4 B.

At cmos image sensor 10 (wherein; The unit pixel 20 that comprises pixel circuit configuration shown in Figure 1 is arranged with matrix form) in; Generally shown in Fig. 4 A; All is " H " level in the period " t1 " through feasible transfer pulse TRG and reset pulse RST, reset photodiode 21 and FD district 26, and the light that is received in the period " t2 " is the electronics that is stored in the photodiode 21 by opto-electronic conversion.Then, back half the period " t4 " of period " t2 " through making that reset pulse RST is " H " level, FD district 26 resets.Then, through making that strobe pulse SEL is " H " level, the electromotive force of reading FD district 26 is as reset level; After this, be " H " level in the period " t3 " through feasible transfer pulse TRG, the electronics that is stored in the photodiode 21 is transferred to FD district 26; Then; The period " t5 " through making that strobe pulse SEL is " H " level, reads the electromotive force in FD district 26, as signal level.

To top conventional read operation, exist in the present invention to make the needs of the higher and dynamic range broad of S/N.According to embodiments of the invention; In storing time intervals (exposure period); A plurality of control voltages sequentially are fed to the control electrode (gate electrode) of transfering transistor 22, wherein in storing time intervals, through the opto-electronic conversion store electrons; And the signal charge that shifts through transfering transistor 22 at this moment, is read two or more times.

Particularly; Shown in Fig. 4 B; All is " H " level in the period " t10 " through feasible transfer pulse TRG and reset pulse RST, reset photodiode 21 and FD district 26, and the light that is received in the period " t11 " is the electronics that is stored in the photodiode 21 by opto-electronic conversion.Then, back half the period " t12 " of period " t11 " through making that reset pulse RST is " H " level, the FD district 26 that resets, then, through making that strobe pulse SEL is " H " level, the electromotive force of reading FD district 26 is as reset level.

Then, at period " t13 ", voltage Vtrg1 is supplied to the control electrode of transfering transistor 22, and according to the amount (it is determined by incident intensity) of the store electrons in the photodiode 21, electronics is partly transferred to FD district 26.At period t14, through making that strobe pulse SEL is " H " level, read according to the electromotive force in the FD district 26 of the amount that is transferred electronics; As signal level; And if necessary, use the reset level of reading at period t12, for example carrying out the noise eliminating processing in the column circuits 16.

At period t15, continue to carry out storage operation, and at period t16, through making that reset pulse RST is " H " level, the FD district 26 that resets is once more followed, through making that strobe pulse SEL is " H " level, reads reset level.And; At period t17, voltage Vtrg2 is supplied to the control electrode of transfering transistor 22, and the electronics (summation of the electronics that is retained in the electronics in the photodiode 21 and in period t15, stores that is not transferred at period t13) that exceeds the potential voltage Vtrg2 of transfering transistor 22 is transferred to FD district 26; And at period t18; Through making that strobe pulse SEL is " H " level, reads the electromotive force in FD district 26, as signal level.

, under the situation of the control electrode that voltage Vtrg3 is fed to transfering transistor 22, be repeated to carry out during the period t22 at period t19 with top identical operations.In addition, when changing to the supply voltage of transfering transistor 22, the operation from period t11 to period t14 is performed once or repeatedly.After the exposure of period t23, through making that reset pulse RST is " H " level, carry out reset operation at period t24 once more, and through making that strobe pulse SEL is " H " level; Read reset level, then, at period t25; Through make shifting pulse TRG be " H " level, and transfering transistor 22 is by complete conducting and implement the transfer fully in FD district 26, then; At period t26, through making that strobe pulse SEL is " H " level, the read output signal level.

Fig. 5 shows the instance of the electromotive force in the pixel when voltage Vtrg1, Vtrg2 and Vtrg3 are supplied to the control electrode of transfering transistor 22.Electron amount in being stored in photodiode 21 is big and exceed under the situation of electromotive force Φ trgi voltage Vtrg1, and the electronics that is stored in the photodiode 21 is transferred to FD district 26 by part.

Fig. 6 shows the potential energy diagram when the potential change when having the stage supply voltage Vtrg of weak incident light.Under the little situation of electron amount in being stored in photodiode 21; This quantity does not surpass the electromotive force Φ trgi of transfering transistor 22; Therefore; The electronics that is produced by opto-electronic conversion is maintained in the photodiode 21, when final transfer, is transferred to FD district 26, is read as signal level then.

On the other hand, as shown in Figure 7, when incident light was very strong, the electronics that exceeds electromotive force Φ trgi was transferred to FD district 26, is read as signal level then.Therefore; In the situation of low-light level, can read in final transfer place, and can not make Signal Degrade through enough time for exposure, and in the situation of high brightness; Through reading the electronics that exceeds, can finally generate composograph with wide dynamic range with a plurality of stages.

Note, each operation time period t10 in Fig. 6 and 7 to t26 corresponding to each operation time period t10 in the sequential chart of Fig. 4 B to t26.

As stated, when with a plurality of stages a plurality of voltage Vtrg1, Vtrg2 and Vtrg3 being fed to the control electrode of transfering transistor 22, and the electronics that exceeds is when repeatedly being transferred to FD district 26, and after shifting for the second time, changes of threshold has been eliminated.Its reason is following.

As shown in Figure 8, when when shifting for the first time, voltage Vtrg1 being applied to the control electrode of transfering transistor 22, the electromotive force of transfering transistor 22 is by φ _Trg1Expression, the electromotive force of the photodiode 21 before stored charge is by φ _Had0Expression, the quantity that remains on the electronics in the photodiode 21 is by Q _HAD1Expression, the quantitaes that overflows to the electronics in FD district 26 is Q _FD1, when keeping electron amount Q _HAD1The time the electromotive force of photodiode 21 by φ _Had1Expression.When the photoelectric current that in photodiode 21, produces pro rata with incident intensity is Ipd, to the time for exposure of shifting for the first time be Δ T, when the electric capacity of photodiode 21 is Cpd, Q _HAD1And Q _FD1Be expressed from the next:

Q _HAD1＝Cpd·φ _had1

Q _FD1＝Ipd·ΔT-Q _HAD1

φ _had1＝φ _had0-φ _trg1

φ _trg1＝Vtrg1-(Vth+ΔVth)

In the above, Vth is the threshold value of transfering transistor 22, and Δ Vth is the changes of threshold of transfering transistor 22.

In shifting for the second time, after the exposure and storage photoelectric current of the time period that is continuing to carry out Δ T, when different voltages with different Vtrg2 is applied in, similarly, when the electromotive force of transfering transistor 22 is φ _Trg2, the quantity that remains on the electronics in the photodiode 21 is Q _HAD2, the quantity that overflows to the electronics in FD district 26 is Q _FD2, when keeping electron amount Q _HAD2The time the electromotive force of photodiode 21 be φ _Had2The time, can obtain following formula.

Q _HAD2＝Cpd·φ _had2

φ _had2＝φ _had0-φ _trg2

φ _trg2＝Vtrg2-(Vth+ΔVth)

Q _FD2＝(Q _HAD1+Ipd·ΔT)-Q _HAD2

＝Cpd·φ _had1+Ipd·ΔT-Cpd·φ _had2

＝Cpd·(φ _had0-φ _trg1)+Ipd·ΔT-Cpd·(φ _had0-φ _trg2)

＝Cpd·{Vtrg1-(Vth+ΔVth)}+Ipd·ΔT-Cpd·{Vtrg2-(Vth+ΔVth)}

＝Ipd·ΔT-Cpd(Vtrg2-Vtrg1)

As stated; After shifting for the second time; Intermediate transfer to the quantity of the electronics in FD district 26 by incident intensity (promptly; The amount of the photoelectric current that is produced) and be applied to transfering transistor 22 control electrode voltage Vtrg2 and just before difference decision between the voltage Vtrg1 that applies, this can reduce the influence of the changes of threshold Δ Vth of transfering transistor 22.In addition; Because the quantity at each electronics that regularly shifts through transfering transistor 22 has correlation; So also have correlation in the reservation quantity that shifts the electronics that the period is not transferred according to the electron amount that exceeds said electromotive force; As a result, after shifting for the second time, the variation that is caused by the reservation electronics is reduced.

Be fed to transfering transistor 22 voltage Vtrg level by as get off definite.

As shown in Figure 9, when the amount of incident light fixedly the time, the quantity and the time for exposure of the electronics of storage increase pro rata in photodiode 21.For example; When incident intensity be assumed to be under this incident intensity electron amount in standard exposure time T s (such as; When 30 frames/second 1/30 second; When 60 frames/second 1/60 second) the electron amount Qs that reaches capacity, then when voltage Vtrg is supplied to the control electrode of transfering transistor 22, estimated at the quantity Nei of the store electrons of timing Ti.Supply voltage Vtrgi at timing Ti is set as following voltage, and through this voltage, store electrons quantity Nei is stored in the photodiode 21.

At Figure 10, show the experimental result of quantity of supply voltage and the electronics when voltage Vtrg is supplied, stored in the photodiode 21 of the control electrode of the transfering transistor 22 in the photodiode 21 (its saturated electrons quantity for 8800e-).

Voltage Vtrg1, Vtrg2 and the Vtrg3 that will obtain for quantity Ne1, Ne2 and the Ne3 of the store electrons from Fig. 9 in the case, at the supply voltage of timing T1, T2 and T3.For in the practical application with the voltage that is supplied; Preferably; Consider to prevent the allowance that causes by thermal diffusion etc. from the leakage current in photodiode 21 to FD districts 26; At transfering transistor 22 is to apply than top low hundreds of millivolts voltage in the situation of N-channel MOS transistor, and applies than top high hundreds of millivolts voltage in the situation of P-channel MOS transistor at transfering transistor 22.

In Figure 11, show another instance of sequential of the supply voltage of the control electrode that is supplied to transfering transistor 22.

In another example, regularly locating supply voltage Vtrg1 to 1/4 of the time for exposure of shifting fully, voltage Vtrg3 is supplied in 3/4 timing place.The method of confirming each voltage Vtrg1, Vtrg3 is identical with top instance.

Correspondingly, through the interval of control supply voltage Vtrg1, Vtrg3, can control quantity and the relation between the incident intensity of the electronics of intermediate transfer, i.e. sensitivity (sensibility).In other words, through making the execution interval of each intermediate transfer can widen dynamic range with a plurality of sensitivity for a plurality of, and in the dynamic range zone therein the S/N in the more weak zone of luminous intensity can be set to higher.

For example; Shown in figure 11; The time for exposure (t31) of intermediate transfer is 1/4 of a total exposure time when arriving for the first time; And from the first time intermediate transfer be 1/2 o'clock of total exposure time to time for exposure (t35) of the intermediate transfer second time, the quantity of the electronics that in shifting for the first time, will be read will be 1/4 with respect to the sensitivity of incident intensity, this has contribution for Extension of dynamic range.

In shifting for the second time, sensitivity will be 1/2, and dynamic range is narrower than shifting for the first time, but can be implemented in this zone than shifting higher S/N for the first time, up to the zone than wide about twice to conventional zone.In last transfer fully, realize one times sensitivity and dynamic range, that is, be equal to regular situation with respect to this incident intensity, this picture quality of having avoided in low brightness area, being caused by wide dynamic range becomes bad.

In Figure 12, show another instance with the sequential of the supplying electrode of the control electrode that is supplied to transfering transistor 22.

In this example, with arbitrarily once or repeatedly, in the supply of repeatedly voltage Vtrgi, carry out reset operation, and do not read the signal level that is transferred.Through reset operation is moved to be right after shift after and activation selecting signal not, can realize this operation.According to this operation, when signal that the variation that is transferred electron amount that obtains wherein to be caused by changes of threshold reduces, can be omitted in the read operation that has big variation in shifting for the first time.

Through not carrying out read operation, can be so that shift the frame rate that is shorter than cmos image sensor 10 at interval, this has contribution for Extension of dynamic range.For example, in Figure 12, apply voltage Vtrg1, and carry out and reset and read output signal level not in 1/8 timing to the time for exposure of shifting fully.Timing supply voltage Vtrg2 1/4, and read output signal level.Then, the timing supply voltage Vtrg3 3/4, and read output signal level, last, in shifting fully, the read output signal level.

In carrying out 4 times read operation altogether; In reading the first time of shifting, can obtain 1/8 output, therefore corresponding to the time for exposure through voltage Vtrg2; Can maximum guarantee about 8 times dynamic range, and through just having reduced changes of threshold in the transfer of voltage Vtrg1 before.In reading through the second time of voltage Vtrg3, shift and be spaced apart 1/2, therefore, can in for the wide dynamic range of the twice of saturation level, obtain to have signal than reading for the first time high S/N.

In this example, dynamic range is expanded roughly 8 times of its common width, and still, enough is that reading speed is 4 times of its usual speed.Similarly, through make voltage Vtrg1 supply regularly regularly near the supply of voltage Vtrg2, can be dynamic range expanded.As the instance shown in Figure 12, can also be through except the operation of Fig. 4 A, just after the transfer of signal level is perhaps read, carrying out reset operation, the electronics in the FD district 26 that resets in advance.

Locate to shear and superpose at saturation level (its by preestablished) through shown in figure 13, the signal that the intermediate transfer through repeatedly obtains has obtained continuous input and output characteristic.For example, in Figure 13, after the transfer fully in the rotine exposure of reading inferior as " i ", signal is exported with high S/N, up to the saturation level of routine.In " i-1 " inferior transfer in front; 1/2 place through in the time for exposure carries out the dynamic range that intermediate transfer can obtain almost twice; And in " i-2 " inferior transfer, carry out intermediate transfer through 1/8 place and can obtain almost 8 times dynamic range in the time for exposure.Near through saturation level point is sheared and superposed signal signal, can obtain continuous characteristic.

For example in the signal processing circuit (not shown) of the cmos image sensor 10 that follow-up phase provides; Will be through using frame memory; Execution is used for through shearing and stack realizes the processing of high S/N and wide dynamic range, the image that wherein said frame memory storage is repeatedly read.

But; Handling instance only is instance, and if the stored words of the image of repeatedly reading, can handle through using personal computer; And configuration that can be following; Wherein, through on cmos image sensor 10, frame memory being installed, processing in cmos image sensor 10, carries out and only last image is exported.

In Figure 14, show experimental result.In experiment, the voltage Vtrg3 of the voltage Vtrg1 of 0.6V, the voltage Vtrg2 of 1.1V, 1.3V is supplied to the control electrode of transfering transistor 22 by the sequential chart of Figure 12.

Figure 14 is illustrated in from time for exposure that resetting to fully of photodiode 21 shifted situation for 16ms roughly; When carrying out than the slow 2ms of resetting of photodiode 21 through the intermediate transfer of the first voltage Vtrg1; When carrying out than the slow 4ms of resetting of photodiode 21 through the intermediate transfer of the second voltage Vtrg2; When intermediate transfer is for the third time carried out than the slow 12ms of resetting of photodiode 21, the quantity of the electronics that in photodiode 21, keeps respectively.

In Figure 14, t1, t2, t3 and t4 are the exposure period, and t2, t4 and t6 are for shifting the period.The time that voltage Vtrg is applied to the control electrode of transfering transistor 22 is 100ns.Figure line 40-51 represents following condition; Wherein, its intensity makes the total quantity at the electronics that in photodiode 21, produces during the 16ms be respectively the light entering photodiode 21 of 350e-, 1200e-, 2200e-, 4400e-, 6600e-, 8800e-, 11000e-, 17500e-, 25000e-, 35000e-, 44000e-, 53000e-.Preferably, shift the period, make and shift, and more preferably, shifting the period is 100ns or longer near poised state with long enough.

Figure 15 show the total quantity of the electronics that is produced that has shown incident intensity in the superincumbent experiment and the quantity of the electronics that in each intermediate transfer and last shifts fully, shifts as output between relation.In Figure 15, the value the when quantity of the electronics that Figure 60 representes to shift through voltage Vtrg1, error bars are the changes of threshold ± 50mV when transfering transistor 22.

In shifting for the first time, the number change of the metastatic electron that is caused by changes of threshold is big, and still, in the transfer result 61 who is accomplished by the second voltage Vtrg2, the number change of electronics reduces.The transfer result 62 who is accomplished by tertiary voltage Vtrg3 has high sensitivity and big gradient, because shift the period than long by the transfer of voltage Vtrg2 completion.The result 63 who shifts fully has and the identical S/N of conventional transfer, in wherein conventional the transfer, does not carry out intermediate transfer for low-light level.As a result 61,62 have result 63 respectively 1/2 times and 1/8 times gradient, this proof shifts sequential through control, has controlled sensitivity and has allowed wide dynamic range.63 is the wide dynamic range characteristics that obtain through top characteristic synthetic method as a result.It has realized high S/N and the wide dynamic range of linear characteristic under the low-light level situation.

As stated; For example, (wherein, unit pixel 20 is arranged with matrix form two-dimentionally at cmos image sensor 10; Said unit pixel 20 comprises photodiode 21 and transfering transistor 22; Said transfering transistor 22 shifts the signal charge of opto-electronic conversion in the photodiode 21) in, a plurality of first control voltages sequentially are fed to the control electrode of transfering transistor 22 from supply voltage control circuit block 13, simultaneously; Carry out driving operations through vertical scanning circuit 12; In this driving operations, to be read by two or more times ground by the signal charge that transfering transistor 22 shifts, this can allow signal at low-light level lower linear and high S/N to obtain and saturation level that can the constriction routine; And can allow Extension of dynamic range to incident light greater than the saturated level of routine, realize the good S/N in the range of linearity simultaneously.

Therefore; To in various environment (such as indoor and outdoors; The variation of exterior light day and night) can obtain high-quality image with high S/N in the low-light level scene, and in the high brightness scene, obtains to have the high quality graphic than low saturation through linear response.In addition, even in the high contrast scene that low-light level therein and high brightness all exist, saturated can being avoided in the hi-lite kept the high S/N in the low-light level part simultaneously.

In addition; Be disposed in during conventional pixel arranges having highly sensitive pixel; Be used for improving the situation of sensitivity; The S/N that needn't reduce in the conventional pixel makes the time for exposure satisfy the high sensitivity pixel, and can obtain the high S/N image of high sensitivity pixel through the abundant exposure of satisfying conventional pixel, and this will be for will being favourable in follow-up phase for the processing of high image quality.

In the above embodiments, explained that wherein the present invention is applied to the cmos image sensor situation of (wherein, comprising that the unit pixel 20 (with reference to figure 1) of selecting transistor 25 is with matrix arrangement), but the invention is not restricted to this application.

In other words, in cmos image sensor 10 according to an embodiment of the invention, can before the next one makes public the period, reset and transfer to the electronics in FD district 26, and no matter after transfer, whether have read operation; Therefore, the present invention can also be applicable to following cmos image sensor, wherein, does not comprise and selects the unit pixel of transistor 25 to be arranged with matrix form.

Particularly, shown in Figure 16 A, the present invention can also be applicable to the cmos image sensor with following unit pixel; Wherein, Shown in the image element circuit of unit pixel except photodiode 21, also comprise three transistors, transfering transistor 22, reset transistor 23 and amplifier transistor 24, it is made as the electromotive force lower than the threshold value of amplifier transistor 24 through reset transistor 23 with the electromotive force in FD district 26; Promptly select electrical source voltage SELVDD, so that unit pixel is in not selected state.

Shown in Figure 16 B, the present invention can also be applicable to following image element circuit, and this image element circuit also comprises switching transistor 27 except photodiode 21, transfering transistor 22, reset

transistor

23 and 24 3 transistors of amplifier transistor.Image element circuit has following configuration; Wherein, From vertical signal line 111 supplies, therefore, reset transistor 23 is connected between FD district 26 (gate electrode of amplifier transistor 24) and the vertical signal line 111 resetting voltage Vrst by optionally; And resetting voltage Vrst optionally is fed to vertical signal line 111 through switching transistor 27, shown in switching transistor 27 through switching pulse SW conducting.

In addition, the present invention can also be because identical reason be applicable to the pixel arrangement of shared amplifier transistor 24 between a plurality of unit pixel.

The cmos image sensor 10 that utilizes the sequential chart among Figure 17 explanation to be had the unit pixel that comprises three transistorized image element circuits shown in Figure 16 A.

After the period T4 that shifts fully and read of former frame, in period T1, empty the signal electron in photodiode 21 and the FD district 26 through electronic shutter.Then, the electric charge (electronics in this case) that is produced by exposure and opto-electronic conversion is stored in the photodiode 21.Before intermediate transfer, at period T2, intermediate voltage (corresponding to the voltage Vtrg1 among Fig. 4 B) is applied to the control electrode of transfering transistor 22, and the signal electron that in having the pixel of a large amount of incident lights, produces is partly transferred to FD district 26.At this moment, the electric charge of transferring to FD district 26 is not read and is resetted.

At period T3, be applied to the control electrode of transfering transistor 22 with the identical or different intermediate voltage of period T2, and the signal charge that in having the pixel of a large amount of incident lights, produces is transferred to FD district 26 by part once more.At this moment, the signal charge of transferring to FD district 26 is read.Then, proceed exposure, and pass through at the complete conducting transfering transistor 22 of period T4, all signal charges that are stored in the photodiode 21 are transferred to FD district 26, and are read from FD district 26.

At period T4, through applying in the pixel with a small amount of incident light that intermediate transfer does not take place intermediate voltage, signal charge does not reduce and is being stored in wherein therein, therefore, and can be with high S/N read output signal.And in having the pixel of a large amount of incident lights, signal charge is saturated, but they are through applying intermediate voltage and carry out intermediate transfer and being read as signal.

In Figure 18, show in shifting period T4 and electronic shutter period T1 fully the electromotive force relation in photodiode (PD) 21 and FD district 26, and the concrete sequential relationship of selecting electrical source voltage SELVDD, reset pulse RST and transfer pulse TRG.

When selecting electrical source voltage SELVDD to be in the state of " H " level; At period t0; Through making reset pulse RST be " H " level and make reset transistor 23 be in conducting state, the FD district 26 that resets, then; At period t1, the electromotive force of reading FD district 26 through amplifier transistor 24 is as reset level.At period t2, be " H " level through make shifting pulse TRG, the signal charge of photodiode 21 is transferred to FD district 26, and at period t3, and the electromotive force of reading FD district 26 through amplifier transistor 24 is as signal level.

At period t4, through making reset pulse RST be " H " level and make reset transistor 23 be in conducting state (serving as electronic shutter), FD district 26 resets.At period t5, through making selection electrical source voltage SELVDD be " L " level and make the electromotive force in FD district 26 be lower than the threshold value of amplifier transistor 24, amplifier transistor 24 is turned off, so that pixel is in not selected state.

At Figure 19, show in intermediate transfer period T2, T3 the electromotive force relation in photodiode (PD) 21 and FD district 26, and the concrete sequential relationship of selecting electrical source voltage SELVDD, reset pulse RST and transfer pulse TRG.

At period t0, through making reset pulse RST be " H " level and make reset transistor 23 be in conducting state, FD district 26 resets.In the situation of period T3,, read the electromotive force in FD district 26 through amplifier transistor 24, as reset level at period t1.In the situation of period T2, needn't carry out read operation.At period t2, voltage Vfg carries out intermediate transfer to the control electrode of transfering transistor 22 through applying arbitrarily.For free voltage, in the situation of period T2, apply Vfg0, in the situation of period T3, apply Vfg1.

When the amount of incident light hour, the voltage height of photodiode 21 is to shown in the dotted line, and do not occur to the transfer in FD district 26.And when the amount of incident light was big, the voltage of photodiode 21 was low to moderate shown in the solid line, and the signal charge that exceeds the grid electromotive force down of transfering transistor 22 is partly transferred to FD district 26.In the situation of period T3, at period t3, the electromotive force of reading FD district 26 through amplifier transistor 24 is as signal level.In the situation of period T2, needn't carry out read operation.

At period t4; Through making reset pulse RST be " H " level and make reset transistor 23 be in conducting state; The FD district 26 that only resets, and at period t5 selects electrical source voltage SELVDD for " L " level and make the electromotive force in FD district 26 be lower than the threshold value of amplifier transistor 24 through making; Amplifier transistor 24 is turned off, so that pixel is in not selected state.

To Figure 20 F, show the electromotive force relation of each sequential at Figure 20 A.Figure 20 A is the potential energy diagram the during electronic shutter operation at period t4 in as the period T4 that shifts and read the period fully.In electronic shutter operation, the electric charge that is stored in photodiode 21 and the FD district 26 is scavenged into selection electrical source voltage SELVDD side.

Figure 20 B is the potential energy diagram after the reset operation of period t0 in period T2, T3 and T4.After reset operation,, produce the charge storage that causes through exposure according to the incident light intensity.

Figure 20 C is the potential energy diagram when the intermediate transfer operation of period t2 in period T2 and T3.In the intermediate transfer operation; Make that electromotive force under the grid of transfering transistor 22 is the control electrode that the voltage of conducting state and the intermediateness between the off state of transfering transistor 22 is applied to transfering transistor 22; As a result, when incident intensity hour, do not shift because institute's charge stored is few; And only when incident intensity is big, the transfer that produces FD district 26 because the electromotive force of photodiode 21 is higher than the electromotive force under the grid of transfering transistor 22.

Figure 20 D is the potential energy diagram of period t2 among the period T4, and at this moment transfering transistor 22 is in conducting state to execute total transfer, and in shifting fully, the electric charge that is stored in the photodiode 21 is read fully.Figure 20 E is the potential energy diagram of period t3 among period T3, the T4, and at this moment transfering transistor 22 is in off state after shifting read output signal fully.Figure 20 F is the potential energy diagram of period t5 among period T1, T2 and the T3, and at this moment wherein the operation that is not chosen of pixel makes the electromotive force in FD district 26 not be higher than the threshold value of amplifier transistor 24.

In pixel array region, not in the situation of homogeneous in each pixel in electromotive force shape as the photodiode 21 of light receiving area, be different through applying the quantity that intermediate voltage remains on the electronics in the photodiode 21.Therefore, the worry below existing promptly depends on the electromotive force shape variation of photodiode 21, and through reading the output signal in high luminance area of acquisition and have the fixed mode noise by applying intermediate voltage, this causes deterioration of image quality.

Like Figure 21 A to shown in Figure 21 D; Let us is considered the for example state of Figure 21 B; Wherein work as through voltage Vfg0 being applied to the control electrode of transfering transistor 22; When the part of charge Q i0 was removed from the state (wherein, charge Q i0 is stored in the photodiode 21) of Figure 21 A, only charge Q 0 was retained in the photodiode 21.

Through the state (wherein charge Q i1 further is stored in the state of Figure 21 B) that voltage Vfg1 is applied to Figure 21 C; Charge Q fg1 can be transferred to FD district 26 and read as signal, and charge Q 0+Q1 is retained in (state of Figure 21 D) in the photodiode 21 simultaneously.

Shown in figure 22, proportional from the state of Figure 21 B to the charge Q i1 and the incident intensity of the state storage of Figure 21 C.In order to obtain incident intensity by the signal charge Qfg1 that in the state of Figure 21 D, shifts, that is, brightness is necessary to obtain by voltage Vfg0 and the definite charge Q 1 of voltage Vfg1.But, when the electromotive force shape of photodiode 21 in each pixel not simultaneously, for each pixel, charge Q 1 exists and changes, therefore, the image that is obtained by charge Q fg1 comprises the fixed mode noise.

[application]

In order to compensate the fixed mode noise of the above-mentioned electromotive force shape variation that depends on photodiode 21, can adopt following application, and below will make an explanation it.

[operational instances 1]

Figure 23 shows the sequential chart according to the operational instances 1 of application of the present invention.Operational instances 1 is to have the instance under the situation of the unit pixel that comprises three transistorized image element circuits shown in Figure 16 A at the CMOS transistor.

At first, after the reading in former frame, fill electric charges (electronics or hole) at period S1 photodiode 21.Then, at period S2, voltage Vfg1 is applied to the control electrode of transfering transistor 22, and carries out intermediate transfer, and then, electric charge is reset.Then, at period S3, voltage Vfg0 is applied to the control electrode of transfering transistor 22, carries out intermediate transfer and read output signal.At last,, execute total transfer and read output signal, then, in period S5, carry out electronic shutter operation at period S4.

In Figure 24, show at intermediate transfer period S2, S3 the electromotive force relation in photodiode 21 and FD district 26, and the concrete sequential relationship of selecting electrical source voltage SELVDD, reset pulse RST and transfer pulse TRG.

At period t0, through making reset pulse RST be " H " level and make reset transistor 23 be in conducting state, FD district 26 resets.In the situation of period S3,, read the electromotive force in FD district 26 through amplifier transistor 24, as reset level at period t1.In the situation of period S2, needn't carry out read operation.At period t2, voltage Vfg carries out intermediate transfer to the control electrode of transfering transistor 22 through applying arbitrarily.For free voltage Vfg, in the situation of period S2, apply Vfg1, in the situation of period S3, apply Vfg0.In this case, Vfg0 can be identical magnitude of voltage with Vfg1.

When the amount of incident light hour, the voltage height of photodiode 21 is to shown in the dotted line, and do not occur to the transfer in FD district 26.And when the amount of incident light was big, the voltage of photodiode 21 was low to moderate shown in the solid line, and the signal charge that exceeds the grid electromotive force down of transfering transistor 22 is partly transferred to FD district 26.In the situation of period S3, at period t3, the electromotive force of reading FD district 26 through amplifier transistor 24 is as signal level.In the situation of period T2, needn't carry out read operation.

In Figure 25, show in shifting period S4 and electronic shutter period S5 fully the electromotive force relation in photodiode 21 and FD district 26, and the concrete sequential relationship of selecting electrical source voltage SELVDD, reset pulse RST and transfer pulse TRG.

[operational instances 2]

Figure 26 shows the sequential chart according to the operational instances 2 of application of the present invention.Operational instances 2 also is to have the instance under the situation of the unit pixel that comprises three transistorized image element circuits at the CMOS transistor.

Operational instances 2 be wherein last in the operational instances 1 shift fully read the instance that is omitted.Through omitting last reading of shifting fully; Contrast with operational instances 1; The necessary time of a series of processes that is used to obtain compensating signal is shortened, wherein, shown in the compensating signal compensation depend on the fixed mode noise of the electromotive force shape variation of photodiode 21.Through with one in a plurality of voltages or all be made as to be different from and make transfering transistor 22, can omit reading of shifting fully by the voltage of the voltage that turn-offs fully.

In Figure 27; Show in the situation of operational instances 2; In intermediate transfer period S3 ' and electronic shutter period S5, the electromotive force relation in photodiode 21 and FD district 26, and the concrete sequential relationship of selecting electrical source voltage SELVDD, reset pulse RST and transfer pulse TRG.In operational instances 2, shown in the sequential chart among Figure 27, after read the centre, the operation of selected state was performed shutter operation with being used for not in electronic shutter period S5.

[operational instances 3]

Figure 28 shows the sequential chart according to the operational instances 3 of application of the present invention.Operational instances 3 also is to have the instance under the situation of the unit pixel that comprises three transistorized image element circuits at the CMOS transistor.

Operational instances 3 is following instances, wherein, and forcing operated in saturation, can be shortened at interval at period S1 in the operation of the intermediate transfer of period S2 with in the intermediate transfer of period S3 and between the read operation each.Through shortening each interval between period S1, period S2 and the period S3,, can reduce the influence that incident light or dark current cause with the contrast of operational instances 1.

[operational instances 4]

Figure 29 shows the sequential chart according to the operational instances 4 of application of the present invention.Operational instances 4 also is to have the instance under the situation of the pixel that comprises three transistorized image element circuits at cmos image sensor.

Operational instances 4 is wherein sequentially repeatedly to carry out the instance that the signal accomplished through intermediate transfer is read, and through beginning to apply the control electrode of a plurality of voltages to transfering transistor 22 from rudimentary, can obtain the compensating signal corresponding to the compensation rate of each voltage.

Figure 30 show as above the sequential relationship of forcing operated in saturation of photodiode 21 among the operational instances 1-4 that explained.In Figure 30, period S1 shows the sequential relationship of forcing operated in saturation.

Through making (in this case as the resetting voltage of the initial voltage in FD district 26; Select electrical source voltage SELVDD) equal the voltage of photodiode 21 when saturated; And make that transfer pulse TRG and reset pulse RST are " H " level, transfering transistor 22 is switched on reset transistor 23.Therefore, photodiode 21 is in wherein electric charge with the maintained state of the mode identical with saturation condition.In other words, through making FD district (transfer electric capacity) 26 electromotive force equal the electromotive force of photodiode 21 in the saturation condition, transfering transistor 22 is switched on, the result, and photodiode 21 is full of electronics or hole.

As stated, be filled electric charge (electronics or hole) afterwards at photodiode 21, a plurality of intermediate voltages (the second control voltage) sequentially are applied to the control electrode of transfering transistor 22; Shift with operating part; In other words, the maintained while of the part of charge in being stored in photodiode 21, the stored charge of reservation is partly transferred to FD district 26; As a result, can obtain through one or all the signal charge that shifted of intermediate voltage as voltage signal.Voltage signal comprises the electromotive force shape variation component of photodiode 21, and therefore, it becomes the compensating signal that is used to compensate the fixed mode noise that depends on the electromotive force shape variation.

Be that the order that applies a plurality of intermediate voltages (the second control voltage) is opposite with the order that when obtaining image, applies a plurality of control voltages (the second control voltage) from what the explanation of top operational instances 4 was seen clearly.In other words; In obtaining the situation of image; When applying a plurality of control voltage with high-tension order; Through with the order of low-voltage apply a plurality of intermediate voltages, to obtain compensating signal, this compensating signal is used to compensate the fixed mode noise of the electromotive force shape variation that depends on photodiode 21.

[obtaining the principle of compensating signal]

Then, explain the principle that obtains compensating signal, this compensating signal is used to compensate the fixed mode noise of the electromotive force shape variation that depends on photodiode 21.

Figure 31 A is respectively the potential energy diagram that utilizes in the reading of intermediate transfer to Figure 31 D.At Figure 31 A in 31D; Figure 31 A shows the electromotive force of the period t1 of intermediate transfer period S2; Figure 31 B shows the electromotive force of the period t2 of intermediate transfer period S2; Figure 31 C shows the electromotive force of the period t1 of intermediate transfer period S3, and Figure 31 D shows the electromotive force of the period t2 of intermediate transfer period S3.

Through in period S2-t2, applying voltage Vfg0 (Figure 31 B) to transfering transistor 22, the charge Q i0 (Figure 31 A) that in period S2-t1, is stored in the photodiode 21 is transferred to FD district 26 by part, and charge Q 0 is retained in the photodiode 21.The Qfd0 that transfers to FD district 26 is reset.

The voltage Vfg0 that passes through to be applied controls charge Q 0; But; Charge Q 0 comprises quantity of electric charge changes delta Qvth that is caused by the characteristic variations of transfering transistor 22 (changes of threshold) and the quantity of electric charge changes delta Qpot0 that is caused by the electromotive force shape variation, as the fixed mode noise in each pixel.When the mean value of charge Q 0 was Qhad0, charge Q 0 was expressed from the next:

Q0＝Qhad0+ΔQvth+ΔQpot0 (1)

In the reading of period S3, be added at the charge Q i1 that during the exposure period of period S2, produces, and electric charge (Qi1+Q0) is maintained in the photodiode 21 through opto-electronic conversion.In this state, apply intermediate voltage Vfg1 through control electrode to transfering transistor 22, the part of charge Q i1 is transferred to FD district 26.At this moment, when the reservation electric charge among the charge Q i1 was Q1, electric charge (Q0+Q1) was maintained in the photodiode 21.

Electric charge (Q0+Q1) also comprises the electron amount changes delta Qvth that the changes of threshold by transfering transistor 22 causes, and charge Q 1 comprises the changes delta Qpot1 of the electron amount that is caused by the electromotive force shape variation.When the mean value of charge Q 1 was Qhad1, electric charge (Q0+Q1) was expressed from the next:

Q0+Q1＝(Qhad0+ΔQpot0)+(Qhad1+ΔQpot1)+ΔQvth (2)

In this case, charge Q 1 is expressed from the next:

Q1＝Qhad1+ΔQpot1 (3)

The signal that to be read, the charge Q fg1 that promptly transfers to the FD district is expressed from the next:

Qfg1＝Qi1-Q1

＝Qi1-(Qhad1+ΔQpot1) (4)

Like what can find out, be necessary to eliminate the quantity of electric charge that causes by electromotive force change of shape and change Qpot1 as the characteristic variations of pixel from formula (4).

Figure 32 A is the potential energy diagram that forces in operated in saturation and the intermediate transfer to 32E.At Figure 32 A in 32E; Figure 32 A shows the electromotive force of the period t4 that forces saturated period S1; Figure 32 B show the period t5 that forces saturated period S1 electromotive force; Figure 32 C shows the electromotive force of the period t2 of intermediate transfer period S2, and Figure 32 D shows the electromotive force of the period t2 of intermediate transfer period S3, and Figure 32 E shows the electromotive force of the period t2 of intermediate transfer period S4.

At S1-t4 period (Figure 32 A), force photodiode 21 to be in saturation condition, and at S1-t5 period (Figure 32 B), saturated electrons quantity Qs0 is maintained in the photodiode 21.At S2-t2 period (Figure 32 C), apply voltage Vfg1 through control electrode to transfering transistor 22, the electric charge of being represented by formula (2) (Q0+Q1) can be maintained in the photodiode 21.The electric charge of transferring to FD district 26 is reset.

In the S3-t3 period, when voltage Vfg0 is applied to the control electrode of transfering transistor 22, be maintained in the photodiode 21, and keep charge Q 1 and be transferred to FD district 26 by the charge Q 0 of formula (1) expression, it is read as signal.Therefore, charge Q 1 can obtain the deviant by item Δ Qpot1 (it is the fixed mode noise as the characteristic variations of pixel, and its deterioration picture quality) expression by formula (3) expression.

Sequentially execute in period in the situation of total transfer at S4-t2, the charge Q 0 of formula (1) is read as signal, can also obtain deviant (Δ Qvth+ Δ Qpot0).Through reading this signal, can eliminate the fixed mode noise that the changes of threshold by transfering transistor 22 causes.

(compensation of fixed mode noise)

From cmos image sensor shown in Figure 1 10, read charge Q fg1 (comprising electric charge (quantity of electric charge) Qi1 that depends on incident light quantity) as signal.The mean value Qhad1 of the reservation charge Q 1 that is caused by intermediate transfer is can be by the value of intermediate voltage Vfg1 control, and still, the changes delta Qpot1 of the quantity of electric charge that is caused by the electromotive force change of shape is as the fixed mode noise of pixel, deterioration picture quality.

Therefore, obtain the charge Q 1 in the formula (3) through the method for obtaining compensating signal (offset).When execution formula (5) charge Q 1 is added with charge Q fg1 and computing the time, can obtain result of calculation.

Qfg1+Q1＝Qi1-(Qhad1+ΔQpot1)+Qhad1+ΔQpot1

＝Qi1 (5)

The changes delta Qpot1 of the quantity of electric charge that is caused by the electromotive force shape variation is eliminated, and can only obtain to depend on the charge Q i1 of incident light quantity.

In other words; Addition process through execution formula (5); Through utilizing the compensating signal that is obtained by top acquisition methods, the changes delta Qpot1 of the quantity of electric charge that is caused by the electromotive force shape variation of photodiode 21 is eliminated, and can obtain to indicate the charge Q i1 of incident light quantity; As a result, through reducing the picture quality that the fixed mode noise can improve the imaging picture.

Shown in figure 33, the addition process of formula (5) is carried out in the digital processing circuit 50 of the follow-up phase that is provided in cmos image sensor 10.In this case, imaging signal is exported with digital signal form from cmos image sensor 10.Digital signal processing circuit 50 for example comprises that frame memory, the compensating signal that obtains to each pixel through top acquisition methods are stored in the frame memory by each pixel; And be stored in the compensating signal in the frame memory through use; When conventional imaging, carry out the addition process of formula (5), compensate the fixed mode noise that the electromotive force shape variation of optical receiving region (photodiode) causes for each pixel.

For obtaining of compensating signal, can consider following method: carry out in the fabrication stage and once obtain processing, and the compensating signal of each pixel is stored in the nonvolatile memory as fixed value; When to system power-up, carry out and once obtain processing, and the compensating signal of each pixel is stored in the frame memory as fixed value; Whenever the fixing period (for example, the period of number frame or tens of frames) repeats and obtains processing, and in each period, the compensating signal that is stored in the frame memory is updated; Repeat by each frame and to obtain processing, and the compensating signal that is stored in the frame memory is updated; And some other method.The increase of obtaining along with compensating signal can obtain following advantage: can be by compensation reliably by the fixed mode noise that causes over time.

As stated; After photodiode 21 is filled electric charge; A plurality of intermediate voltages (the second control voltage) sequentially are applied to the control electrode of transfering transistor 22, and partly transfer is performed, and is read by the signal charge of one of transfer of accomplishing through intermediate voltage or all transfer acquisitions; And signal charge is used as compensation term; Be used for eliminating the fixed mode noise of (when conventional imaging sequentially apply through the control electrode to transfering transistor 22 a plurality of control voltages are obtained) image, the result can obtain following operation and effect.Promptly; In the output signal under the high brightness of dynamic range when widening; One of in the electromotive force shape variation through photodiode 21 and the changes of threshold of photodiode 21 or the fixed mode noise of both images of causing can be eliminated; Therefore, can be so that the imaging picture has high quality.

In this embodiment, explained following situation as an example, wherein; The compensating signal that is obtained by top acquisition methods is applied to imaging signal; This imaging signal sequentially applies a plurality of control voltages through the control electrode to transfering transistor 22 and obtains, and still, it is not limited thereto application.

The embodiment that explains in the above with use, explained that as an example wherein the present invention is applied to the situation of cmos image sensor, still; The invention is not restricted to be applied to cmos image sensor; And relate to all scale-up version solid imaging elements, in addition, relate to read-out element from the signal charge of photoelectric cell; Therefore, the present invention can also be applied to the charge transfer type solid imaging element by the ccd image sensor representative.

The instance that wherein the present invention is applied to ccd image sensor has been shown in Figure 34 A and 34B.In ccd image sensor, carry out opto-electronic conversion at photodiode (light receiving area) 31, and the signal charge that is stored in wherein transfers to vertical CCD (vertical transitions district) 33 through TG transfer gate (reading grid) 32, read by vertical CCD33 according to vertical transitions.In ccd image sensor,, can control the quantity of the electronics that will be transferred to vertical CCD33 through apply above-mentioned control voltage Vtrg to TG transfer gate 32.

When a little less than the incident light (Figure 34 A); Because it is little by the amount of the electronics of opto-electronic conversion; Even so when control voltage Vtrg was applied to TG transfer gate 32, the store electrons in the photodiode 31 was difficult to exceed the electromotive force under the TG transfer gate 32, and store electrons is maintained in the photodiode 31.And when incident intensity (Figure 34 B); Because it is big by the amount of the electronics of opto-electronic conversion; So through apply control voltage Vtrg to TG transfer gate 32, the store electrons in the photodiode 31 exceeds the electromotive force under the TG transfer gate 32, and is transferred to vertical CCD33 by part.

Then; Through with the situation of cmos image sensor in identical control timing apply control voltage Vtrg; With the mode identical with cmos image sensor, can be under high brightness carry out signal and obtain according to intermediate transfer, and under low-light level the inhibit signal electric charge.

[improvement instance]

As above in the instance explained; For all pixels 20 in the pixel array region 11; Sequentially supply a plurality of control voltages to the control electrode of transfering transistor 22, simultaneously, read two or more times by the signal charge that transfering transistor 22 shifts; Yet, the invention is not restricted to wherein all pixels 20 all carried out the application of above-mentioned driving operations.To explain other application below, as improving

instance

1,2 and 3.

[improving instance 1]

Figure 35 is the sketch map of improvement instance 1 of the present invention.In improving instance 1, at solid imaging element (wherein, colored transmitting filter; Be disposed on the pixel such as the primary color filters of R (redness), G (green) and B (blueness) or the complementary color filter of Cy (cyan), Mg (magenta) and Y (yellow); To obtain coloured image) in, pixel 36 arranged partly, shown in pixel 36 do not have colored transmitting filter and its highly sensitive in the pixel with colored transmitting filter 35; And for highly sensitive pixel 36; A plurality of control voltages sequentially are fed to the control electrode of transfering transistor, and simultaneously, are read two or more times through the signal charge that transfering transistor shifts.

Figure 36 shows the figure of the instance of incandescent lamp spectrum.In general; Incandescent lamp comprise a large amount of infrared lights and with wide wavelength band; Shown in the character among Figure 36 " W ", and its intensity decays shown in character " B ", " G " and " R " after transmission is through blue, green and red colored transmitting filter.Do not have the light sensitive pixels 36 of colored transmitting filter to receive the light with wide wavelength band, therefore, their remolding sensitivity comprises the pixel 35 high several times of colored transmitting filter.

Exist therein and comprise the muting sensitivity pixel 35 of colored transmitting filter and do not comprise in both solid imaging elements of high sensitivity pixel 36 of colored transmitting filter; For high sensitivity pixel 36; Sequentially supply a plurality of control voltages to the control electrode of transfering transistor, simultaneously, read two or more times by the signal charge that transfering transistor shifts; The result; In the pixel that comprises colored transmitting filter 35, keep in the high S/N, can obtain signal, even when in high sensitivity pixel 36, surpassing conventional levels.

The signal that in not comprising the high sensitivity pixel 36 of colored transmitting filter, obtains has edge clearly.Therefore; As an example; The signal that in not comprising the high sensitivity pixel 36 of colored transmitting filter, obtains is reflected on the signal that obtains in the muting sensitivity pixel 35 that is comprising colored transmitting filter, and the result can obtain to have the imaging picture of sharp edge.

[improving instance 2]

Figure 37 is the sketch map of improvement instance 2 of the present invention.Existence comprises the muting sensitivity pixel of colored transmitting filter and does not comprise on high sensitivity pixel 36 this point of colored transmitting filter at the same time; Improve instance 2 and be similar to improvement instance 1, still, their difference is; In improving instance 1; High sensitivity pixel 36 is provided with partly, and in improving instance 2, high sensitivity pixel 36 is provided with behavior unit.

High sensitivity pixel 36 is difficult to through select scanning that muting sensitivity pixel 35 and high sensitivity pixel 36 are distinguished with behavior unit by in the improvement instance 1 that scatters therein.Yet, in the improvement instance 2 that high sensitivity pixel 36 exists with behavior unit therein, can muting sensitivity pixel 35 and high sensitivity pixel 36 be distinguished, drive with the selectivity of carrying out with behavior unit.In other words, the row of high sensitivity pixel 36 can be by selectivity driving individually.

Drive the row of high sensitivity pixel 36 for selectivity individually; In the vertical scanning circuit 12 in Fig. 1; Be provided be used for selective scanning comprise colored transmitting filter muting sensitivity pixel 35 row scanning system be used for the scanning system of row that selective scanning does not comprise the high sensitivity pixel 36 of colored transmitting filter, and carry out scanning independently by each scanning system.

Therefore, in improving instance 2, can optionally drive the row of high sensitivity pixel 36 individually; Therefore; Can carry out driving operations with respect to high sensitivity pixel 36, wherein, a plurality of control voltages sequentially are fed to the control electrode of transfering transistor; Simultaneously, the signal charge that is shifted by transfering transistor is read two or more times with service speed fast.Simultaneously; Can carry out conventional read operation to muting sensitivity pixel 35 with low speed, the result is with improvement instance 1 (wherein high speed operation is with inevitable for muting sensitivity pixel 35 equally with the same way as of high sensitivity pixel 36); This embodiment has following advantage; That is, because muting sensitivity pixel 35 can be driven with low speed, so can reduce power consumption.

[improving instance 3]

Figure 38 is the sketch map of improvement instance 3 of the present invention.In improving instance 3; For example; In the pixel arrangement of improving instance 2, infrared light is cut down filter 37 and is arranged on the pixel except that the high sensitivity pixel 36 that does not comprise colored transmitting filter as pixel cell, promptly is arranged on the muting sensitivity pixel 35 that comprises colored transmitting filter.

In order on muting sensitivity pixel 35, to arrange infrared light reduction filter 37 as pixel cell, for example, the dielectric multilayer film can be overlayed on the muting sensitivity pixel 35.In addition; Can remove the infrared reduction filter the earlier stage that generally is arranged in image device from high sensitivity pixel 36; Perhaps use to eliminate to have the more filter of long wavelength's infrared light, the result, infrared light is cut down filter 37 and can be disposed on the muting sensitivity pixel 35.

Therefore; Cut down filter 37 through on muting sensitivity pixel 35, arranging infrared light; High sensitivity pixel 36 also can receive infrared light, and this makes that high sensitivity pixel 36 can be sensitiveer, therefore; In high sensitivity pixel 36, can obtain signal, and can deterioration not comprise the signal of the muting sensitivity pixel 35 of colored transmitting filter greater than conventional saturated level.

[suitable examples]

Preferably, the cmos image sensor according to the foregoing description (comprise and improve instance 1-3) is used as such as the image device in the imaging device of digital still video camera and video camera (image entering apparatus).

Imaging device refers to that camara module (for example; Be used to be installed in such as cellular electronic equipment); With camara module be mounted above that camera chain (such as; Digital still video camera and video camera), shown in camara module comprise solid imaging element, the image light of object focused on optical system and the signal processing circuit of solid imaging element on the imaging surface (optical receiving surface) of solid imaging device as image device.

Figure 39 shows the block diagram of the profile instance of imaging device according to an embodiment of the invention.Shown in figure 39, comprise optical system, image device 42 and the camera signal treatment circuit 43 etc. that comprise lens 41 according to the imaging device of this embodiment.

Lens 41 will focus on the imaging surface of image device 42 from the image light of object.Image device 42 output image signals, this picture signal converts electronic signal to and obtains through in pixel cell, focusing on image light on the imaging surface by lens 41.Cmos image sensor 10 according to embodiment is used as image device 42.43 pairs of picture signals from image device 42 outputs of camera signal processing unit are carried out various signal processing.

As stated; At imaging device (such as video camera, digital still video camera and be used for camara module) such as cellular mobile device; Through using cmos image sensor 10 according to embodiment as image device 42, cmos image sensor 10 can allow the signal of linearity and high S/N under low-light level to obtain and the saturated level of constriction routine not, simultaneously; For incident light greater than conventional saturated level; Can also realize the good S/N in the range of linearity the dynamic range expanded while, the result, can further improve the imaging picture picture quality.

According to embodiments of the invention, under low-light level, can realize that signal obtains and the saturated level of constriction routine not with linear and high S/N; And for incident light greater than conventional saturated level; Can also realize the good S/N in the range of linearity the dynamic range expanded while, therefore, for the variation of exterior light under the various environment; In the low-light level scene, can obtain high quality graphic with high S/N; And in the high brightness scene, can obtain high-quality too late saturated image by linear response, in addition, even exist in the high contrast scene of low-light level and high brightness therein simultaneously; Also can in high-brightness region, avoid saturated, in low brightness area, keep high S/N simultaneously.

Those skilled in the art should understand that according to designing requirement and other factors and can carry out various modifications, combination, son combination and replacement, as long as it is in the scope of accompanying claims or its equivalent.

Cross-reference to related applications

The present invention comprises the theme of Japanese patent application JP 2005-313755 that relates on October 28th, 2005 and submit and the Japanese patent application JP 2006-124699 that submitted on April 28th, 2006, and the full content of these japanese publication is in this article involved by reference.

Claims

1. solid imaging element comprises:

Pixel array region; Wherein, Unit pixel is arranged in the said pixel array region with matrix form two-dimentionally; Said unit pixel comprises photo-electric conversion element and TG transfer gate, and said photo-electric conversion element converts light signal into signal charge, and said TG transfer gate shifts in said photo-electric conversion element by the said signal charge of opto-electronic conversion;

The supply voltage-operated device is used for controlling the control electrode that voltages sequentially are fed to said TG transfer gate with a plurality of first; With

Drive unit is used to carry out the driving operations that two or more times read out in the signal charge that said a plurality of first control voltage shifts by said TG transfer gate when sequentially applying,

Control device, be used for carrying out a plurality of second control voltages one of or shift by said TG transfer gate when all being applied in and the control of reading of the signal charge that obtains, wherein

Said a plurality of first control voltage is applied to the said control electrode of said TG transfer gate in exposure period of said photo-electric conversion element with order from high to low,

Said a plurality of second control voltage is applied to the said control electrode of said TG transfer gate with order from low to high after said photo-electric conversion element is full of electronics or hole.

2. solid imaging element according to claim 1; Wherein, Said a plurality of first control voltage comprises the voltage that at least one is following; This voltage can shift the remainder in institute's stored charge by said TG transfer gate in the part in keeping being stored in the electric charge of said photo-electric conversion element.

3. solid imaging element according to claim 1, wherein, said unit pixel comprises amplifier transistor, the signal charge that said amplifier transistor amplifies and output is shifted from said photo-electric conversion element by said TG transfer gate, as signal voltage, and

Wherein, said drive unit is carried out and is read the driving operations of being transferred to the signal charge of said amplifier transistor by said TG transfer gate through said amplifier transistor.

4. solid imaging element according to claim 1 also comprises:

Charge transfer region is transferred to the said charge transfer region from the signal charge that said photo-electric conversion element shifts by said TG transfer gate, and

Wherein, said drive unit is carried out and is read the driving operations of being transferred to the signal charge of said charge transfer region by said TG transfer gate through said charge transfer region.

5. solid imaging element according to claim 1, wherein, said drive unit is carried out and is resetted when said a plurality of first control voltages driving operations by the signal charge of said TG transfer gate transfer when sequentially supplying, and does not carry out once or repeatedly reading.

6. solid imaging element according to claim 1, wherein, in the exposure period of said unit pixel, said supply voltage-operated device is supplied said a plurality of first control voltage with different intervals.

7. solid imaging element according to claim 1, wherein, said pixel array region comprises the pixel with colored transmitting filter, said pixel is sensitiveer than the pixel with colored transmitting filter.

8. solid imaging element according to claim 7, wherein, said high sensitivity pixel is arranged with behavior unit; And

Wherein, said drive unit is carried out two or more times driving operations that reads out in the signal charge that said a plurality of first control voltage shifts by said TG transfer gate when sequentially being applied to said high sensitivity pixel.

9. solid imaging element according to claim 7, wherein, the said pixel of colored transmitting filter that comprises comprises infrared light reduction filter, and

Wherein, the light signal of infrared light is drawn together in the packet receiving of said high sensitivity pixel-by-pixel basis.

10. solid imaging element according to claim 1; Wherein, Said a plurality of second control in the voltage one of or all be such voltage; Said voltage can be shifted the remainder of institute's stored charge by said TG transfer gate when keeping being stored in the part of charge in the said photo-electric conversion element.

11. solid imaging element according to claim 10; Wherein, When said a plurality of first control voltages with by high voltage when the order of low-voltage is sequentially applied, said a plurality of second controls voltages sequentially to be applied to high-tension order by low-voltage.

12. solid imaging element according to claim 1; Wherein, Electric charge through said TG transfer gate shifts from said photo-electric conversion element is transferred to the transfer electric capacity; Electromotive force under the saturation condition that the feasible electromotive force that shifts electric capacity is said photo-electric conversion element is so that said TG transfer gate is a conducting state.

13. solid imaging element according to claim 1 also comprises:

Signal processing apparatus is used for through utilizing the signal of the signal charge that obtains based on the control by said control device, carries out the processing based on the fixed mode noise of the signal removal of images of the signal charge that is obtained by said drive unit.

14. solid imaging element according to claim 13, wherein, said signal processing apparatus with said signal based on the signal charge that obtains by the control of said control device with said based on signal plus by the signal charge of said drive unit acquisition.

15. method that drives solid imaging element; Wherein in said solid imaging element; Unit pixel arranges two-dimentionally that with matrix form said unit pixel comprises photo-electric conversion element and TG transfer gate, and said photo-electric conversion element converts light signal into signal charge; By the said signal charge of opto-electronic conversion, said method comprises the steps: in said photo-electric conversion element in said TG transfer gate transfer

A plurality of control voltages sequentially are fed to the control electrode of said TG transfer gate;

Two or more times read out in the signal charge that said a plurality of control voltage is shifted by said TG transfer gate when sequentially applying; Wherein said a plurality of control voltage is applied to the said control electrode of said TG transfer gate with order from high to low in the exposure period of said photo-electric conversion element

Read the secondary signal electric charge; Said secondary signal electric charge a plurality of second controls in the voltages one of or shift by said TG transfer gate when all being applied in and obtain; Wherein said a plurality of second control voltage is applied to the said control electrode of said TG transfer gate with order from low to high after said photo-electric conversion element is full of electronics or hole.

16. the method for driving solid imaging element according to claim 15; Wherein, Said a plurality of second control voltage comprises the voltage that at least one is following; This voltage can shift the remainder in institute's stored charge by said TG transfer gate in the part in keeping being stored in the electric charge of said photo-electric conversion element.

17. method that drives solid imaging element; Wherein in said solid imaging element; Unit pixel arranges two-dimentionally that with matrix form said unit pixel comprises photo-electric conversion element and TG transfer gate, and said photo-electric conversion element converts light signal into signal charge; By the said signal charge of opto-electronic conversion, said method comprises the steps: in said photo-electric conversion element in said TG transfer gate transfer

A plurality of first control voltages sequentially are fed to the control electrode of said TG transfer gate;

Two or more times read out in first signal charge that said a plurality of first control voltage is shifted by said TG transfer gate when sequentially applying, and wherein said a plurality of first control voltages are applied to the said control electrode of said TG transfer gate with order from high to low in the exposure period of said photo-electric conversion element;

Read the secondary signal electric charge; Said secondary signal electric charge a plurality of second controls in the voltages one of or shift by said TG transfer gate when all being applied in and obtain; Wherein said a plurality of second control voltage is applied to the said control electrode of said TG transfer gate with order from low to high after said photo-electric conversion element is full of electronics or hole; And

Through utilizing signal, carry out processing based on the fixed mode noise of the signal removal of images of said first signal charge based on said secondary signal electric charge.

18. an imaging device comprises:

Solid imaging element; Wherein, Unit pixel is arranged in the said solid imaging element with matrix form two-dimentionally; Said unit pixel comprises photo-electric conversion element and TG transfer gate, and said photo-electric conversion element converts light signal into signal charge, and said TG transfer gate shifts in said photo-electric conversion element by the said signal charge of opto-electronic conversion;

Optical system is directed to light the imaging surface of said solid imaging element from object;

Wherein, said solid imaging element comprises:

Supply voltage-operated device, be used for a plurality of control voltages sequentially are fed to the control electrode of said TG transfer gate; With

Drive unit is used to carry out the driving operations that two or more times read out in the signal charge that said a plurality of control voltage shifts by said TG transfer gate when sequentially applying,

Control device, be used for carrying out a plurality of second control voltages one of or shift by said TG transfer gate when all being applied in and the control of reading of the signal charge that obtains,, wherein

Said a plurality of control voltage is applied to the said control electrode of said TG transfer gate in exposure period of said photo-electric conversion element with order from high to low,