Invention content
The purpose of the present invention is to provide a kind of dot structures, to improve sensitivity and the dynamic range of imaging sensor.
In order to achieve the above object, the present invention provides a kind of pel arrays, including the multiple pixel lists to line up rows and columnsMember, each pixel unit include：
Multiple photodiodes, for accumulating the charge of photoelectric effect generation to respond incident light；
Multiple transmission transistors, drain electrode are respectively connected to respective photodiode, and source electrode is commonly connected to floating diffusionNode, according to respective transmission of control signals by the electric charge transfer of respective photodiode to the floating diffusion nodes；
Reset transistor is connected between fixed power source and the floating diffusion nodes, is reset according to reseting controling signalThe current potential of the floating diffusion nodes；
Reading circuit is connected to the floating diffusion nodes, reads the picture signal of the floating diffusion nodes and outputTo alignment；
Wherein, the multiple transmission transistor in each pixel unit corresponds to respective transmission control letter respectivelyNumber, multiple pixel units in same a line share the transmission of control signals.
Optionally, each pixel unit includes four photodiodes and four transmission transistors, and fourA photodiode is symmetrical arranged with 2 × 2 arrangement modes.
Optionally, the picture signal of multiple pixel units in same row is exported to an alignment or twoThe alignment.
Optionally, if the picture signal of multiple pixel units in same row is exported to an alignment,The playback mode of the pel array reads for hemistich.
Optionally, if the picture signal of multiple pixel units in same row is exported to two alignments,The playback mode of the pel array is that double hemistich are read.
Optionally, the reading circuit includes output amplifier and row selecting transistor.
Optionally, the output amplifier is casacade multi-amplifier or one-stage amplifier.
Optionally, the one-stage amplifier is source following transistor, and the grid of the source following transistor is connected toThe floating diffusion nodes, drain electrode are connected to the fixed power source, and source electrode is connected to the drain electrode of the row selecting transistor, describedThe source electrode of row selecting transistor is connected to the alignment.
Optionally, the pixel unit further includes capacitance, one end of the capacitance be connected to the floating diffusion nodes withBetween the input terminal of the reading circuit, other end ground connection.
Optionally, the capacitance is between fixed capacity or the floating diffusion nodes and the input terminal of the reading circuitThe parasitic capacitance that generates over the ground of node.
In order to achieve the above object, the present invention also provides a kind of imaging sensors, including as described in above-mentioned any onePel array, the exposure mode of described image sensor includes rolling exposure mode and global exposure mode, and described image passesSensor further includes：
Control module, the control module are used to control the reset, selection and output of the photodiode；
Memory module, the output signal for storing the photodiode under global exposure mode.
Optionally, under the global exposure mode, multiple photodiodes of each pixel unit expose simultaneouslyAnd reading.
Optionally, described image sensor is standard RGB pattern image sensors, HDR pattern image sensors or RGB-IR pattern image sensors.
Compared with prior art, in the pel array of the present invention, multiple photodiodes in each pixel unit are eachBe connected to floating diffusion nodes from by a corresponding transmission transistor, and reset transistor and reading circuit be connected to it is floatingDynamic diffusion node so that multiple photodiodes share reset circuit and reading circuit, effectively increase the filling of dot structureThe factor, to increase sensitivity and signal-to-noise ratio；And multiple transmission transistors in each pixel unit correspond to respectively it is respectiveTransmission of control signals, can freedom and flexibility select the Exposure mode and reading manner of each pixel unit, be suitable for rolling exposure orThe image sensor architecture of overall situation exposure, in the imaging sensor using above-mentioned pel array, by multiple in pel arrayThe combination of pixel unit or the reading control of pixel unit internal photo, can properly increase the dynamic model of imaging sensorIt encloses, sensitivity and frame per second, while the image application demand of black and white or colored various modes can be met, effectively enhance the pixel battle arrayThe practicability and portability of row.
Specific implementation mode
The specific implementation mode of the present invention is described in more detail below in conjunction with schematic diagram.According to following description andClaims, advantages and features of the invention will become apparent from.It should be noted that attached drawing is all made of very simplified form andUsing non-accurate ratio, only for the purpose of facilitating and clarifying the purpose of the embodiments of the invention.
Inventor has found when studying the structure of imaging sensor, as cmos image sensor is in monitoring safety-security areaExtensive popularization and application, to the sensitivity of cmos image sensor, signal-to-noise ratio, dynamic range, resolution ratio, power consumption and integrated level etc.It is required that being continuously improved, especially sensitivity and dynamic range performance.
In order to obtain higher sensitivity, it is contemplated that the photodiode photosensitive region for pursuing bigger, in dot structureOne timing of area, can take multiple photodiodes to share the dot structure of reset circuit and reading circuit, to improve the pixelThe fill factor of structure increases sensitivity and the signal-to-noise ratio of the dot structure.
In addition, form pel array using above-mentioned dot structure, by the combination of multiple dot structures in pel array orThe reading control of dot structure internal photo can further increase photosensitive area, to increase based on the pel arrayThe sensitivity of imaging sensor entirety and dynamic range.
Based on this, the embodiment of the present invention proposes that a kind of pel array, the pel array include the multiple pictures to line up rows and columnsPlain unit, each pixel unit include：
Multiple photodiodes, for accumulating the charge of photoelectric effect generation to respond incident light；
Multiple transmission transistors, source electrode are respectively connected to respective photodiode, and drain electrode is commonly connected to floating diffusionNode, according to respective transmission of control signals by the electric charge transfer of respective photodiode to the floating diffusion nodes；
Reset transistor is connected between fixed power source and the floating diffusion nodes, is reset according to reseting controling signalThe current potential of the floating diffusion nodes；
Reading circuit is connected to the floating diffusion nodes, reads the picture signal of the floating diffusion nodes and outputTo alignment；
Wherein, the multiple transmission transistor in each pixel unit corresponds to respective transmission control letter respectivelyNumber, multiple pixel units in same a line share the transmission of control signals.
As shown in Figure 1, m*n pixel unit is in matrix distribution, the picture element matrix of a m rows n row is constituted, m, n are just wholeNumber.M*n pixel unit can be identical structure, and each pixel unit is denoted as cell (k, j) successively, wherein k be less than etc.In the positive integer of m, j is the positive integer less than or equal to n.
In one embodiment, as shown in Fig. 2, each pixel unit includes：
Four photodiode PD, for accumulating the charge of photoelectric effect generation to respond incident light, two pole of each photoelectricityOne end of pipe PD connects respective transmission transistor, other end ground connection, in conjunction with Fig. 1, four photodiode PD (P (0,0), P(0,1), p (1,0), p (1,1)) it is symmetrical arranged with 2 × 2 arrangement modes, it is arranged in arrays；
Four transmission transistors m0, m1, m2 and m3, the source electrode of each transmission transistor are respectively connected to respective photoelectricity twoPole pipe PD, a transmission transistor is corresponding with a photodiode, and drain electrode is commonly connected to floating diffusion nodes FD, according to eachFrom transmission of control signals tx00, tx01, tx10 and tx11 by the electric charge transfer of respective photodiode PD to floating diffusion sectionPoint FD；
Reset transistor K1 is connected to fixed power source VDD(output high level) between floating diffusion nodes FD, according to multipleThe current potential of position control signal rst resetting floating diffusion nodes FD；
Reading circuit is connected to floating diffusion nodes FD, reads the picture signal of floating diffusion nodes FD and exports to rowLine, the reading circuit include output amplifier K2 and row selecting transistor K3.
In one embodiment, output amplifier K2 can be casacade multi-amplifier or one-stage amplifier.For example, with outputAmplifier K2 be one-stage amplifier for, can be source following transistor.As shown in Fig. 2, source following transistor K2Grid is connected to floating diffusion nodes FD, and drain electrode is connected to fixed power source VDD, source electrode is connected to the drain electrode of row selecting transistor K3,The source electrode of row selecting transistor K3 is connected to alignment, and the grid of row selecting transistor K3 meets row selection signal R_sel.
In one embodiment, as shown in Fig. 2, each pixel unit can also include capacitance C0, one end of capacitance C0 connectsIt is connected between floating diffusion nodes FD and the input terminal of the reading circuit, other end ground connection.Capacitance C0 can be fixed capacity,It can also be the parasitic capacitance that the node between floating diffusion nodes FD and the input terminal of the reading circuit generates over the ground.
It is understood that the number of photodiode PD is not limited only to four mentioned by above-described embodiment, it is visual to haveBody needs are adjusted flexibly.And the dot structure of common standard RGB pattern color imaging sensors includes four kinds of basic listsColour vegetarian refreshments R, Gr, Gb and B, therefore, for convenience of the subsequent expansion application of the pixel unit, in an embodiment of the invention,Pixel unit takes the structure of four photodiode PD.
As shown in Figure 1, and Fig. 2, four transmission transistor PD in each pixel unit is combined to correspond to respective biography respectivelyDefeated control signal tx00, tx01, tx10 and tx11 control signal (such as kth in multiple pixel unit common transmitteds with a lineAll pixel unit cell (k, 1) of row, cell (k, 2) ..., the transmission of control signals tx00 (k) of cell (k, n) shares, passesDefeated control signal tx01 (k) shares, transmission of control signals tx10 (k) is shared and transmission of control signals tx11 (k) is shared)；It is inWith a line multiple pixel units share reseting controling signal and row selection signal (all pixel unit cell of such as row k (k,1), cell (k, 2) ..., cell (k, n) share reseting controling signal rst<k>And row selection signal R_sel<k>).
In the pel array, transmission of control signals tx00 (k), the tx01 of all pixels unit in row k(k), tx10 (k) and tx11 (k), reseting controling signal rst<k>And row selection signal R_sel<k>By the row of pel arraySelection line selectively exports.
Optionally, the picture signal of multiple pixel units in same row is exported to an alignment or two alignments.
Specifically, as shown in Figure 1, the m rows n row pel array include 2n alignment, be denoted as P (0), P (1), P respectively(2)、P(3)、…、P(2n-2)、P(2n-1).Wherein, alignment P (2j-2) and row selection in the pixel unit of jth row odd-numbered line are brilliantThe source electrode of body pipe K3 is connected, the source electrode phase of alignment P (2j-1) and row selecting transistor K3 in the pixel unit of jth row even number lineEven.
Wherein, alignment P (2j-2) and alignment P (2j-1) can be same alignment or mutually independent alignment.OneIn a embodiment, if the picture signal of multiple pixel units in same row is exported to an alignment, the pel arrayPlayback mode be hemistich read；If the picture signal of multiple pixel units in same row is exported to two alignments, instituteThe playback mode for stating pel array is that double hemistich are read.
Specifically, when alignment P (2j-2) and alignment P (2j-1) is same alignment, that is, it is in same row (jth row)The picture signal of multiple pixel units is exported to an alignment, is read every time by alignment P (2j-2) (that is, alignment P (2j-1))Jth arranges the charge of photodiode PD inductions in the pixel unit of certain a line, reads the pixel unit of jth row line by line, every time onlyThe pixel unit of " hemistich " can be read, the playback mode of the pel array reads for hemistich；As alignment P (2j-2) and alignment PWhen (2j-1) is mutually independent alignment, that is, the picture signal for being in multiple pixel units of same row (jth row) is exported to twoAlignment can read jth by alignment P (2j-2) and alignment P (2j-1) simultaneously every time and arrange light in the pixel unit of certain two rowThe charge of electric diode PD inductions, can read the pixel unit of 2 " hemistich ", the playback mode of the pel array simultaneously every timeIt is read for double hemistich so that the reading rate of the pel array doubles, so that the frame per second of image doubles.
The embodiment of the present invention also provides a kind of imaging sensor, which includes above-mentioned pel array, the figureExposure mode and global Exposure mode are rolled as the Exposure mode of sensor can be divided into, described image sensor further includes controlModule and memory module：Control module includes control circuit and driving circuit, for in pel array pixel unit (inPhotodiode PD) resetted, selected and exported；Memory module is connected to drain electrode and the source electrode of row selecting transistor K3,Output information for storing photodiode PD in global exposure mode.
In the imaging sensor, each pixel unit all has row address and column address.The row of each pixel unitAddress corresponds to the row select line of driving circuit driving, and the column address of each pixel unit corresponds to the row of driving circuit drivingLine.Driving circuit is controlled by control circuit to selectively read out the corresponding pixel unit of row and column appropriate in pel arrayOutput signal.
Due to all pixels units shared transmission of control signals, reseting controling signal and row selection letter in same a lineNumber, so the exposure and reading per one-row pixels unit synchronize.
In addition, the reading manner for four photodiode PD in each pixel unit includes the mode that is successively read and sameWhen reading manner.Wherein, the mode that is successively read is successively read light in four photodiode PD of each pixel unitThe sequential of the charge that electrical effect generates, four transmission of control signals tx00, tx01, tx10 and tx11 in each pixel unit canTo differ or part is identical；Described while reading manner is while reading in four photodiode PD of each pixel unitThe charge that photoelectric effect generates, the sequential of four transmission of control signals tx00, tx01, tx10 and tx11 in each pixel unitIt is just the same.
Optionally, as shown in figure 3, reading four of each pixel unit in same one-row pixels unit using the mode of being successively readThe charge of a photodiode PD.Reading timing control signal as shown in Figure 3, four transmission of control signals tx00, tx01,The sequential of tx10 and tx11 is different, is read out successively to four photodiodes in each pixel unit of same a line.
At this point, if the picture signal of multiple pixel units in same row is exported to an alignment, certain is read every timeA photodiode PD of each pixel unit in one-row pixels unit reads the pixel unit of " hemistich ", when readingSequence is as shown in Figure 3；If the picture signal of multiple pixel units in same row is exported to two alignments, can read simultaneously every timeThe photodiode PD of each pixel unit in certain two row pixel unit is taken, that is, reads the pixel unit of bis- " hemistich ", is readSequential improves the frame per second of imaging sensor, it can be achieved that 2 as shown in figure 4, the row reading circuit of i.e. imaging sensor doublesTimes frame per second.
The pel array that mode is successively read after above-mentioned exposure can be applied in black white image sensor architecture, i.e., the described figureAs sensor can be used as not requiring the black white image sensor of color.
Optionally, the above-mentioned pel array for being successively read mode applies also in standard RGB pattern image sensors, such asShown in Fig. 5, each dot structures of standard RGB pattern image sensors include four kinds of basic monochromatic pixel R, Gr, Gb andB, four kinds of monochromes pixel R, Gr, Gb and B obtain the optoelectronic induction charge component of different colours respectively, then are calculated using linear interpolationMethod calculates the rgb value of each dot structure.Therefore, the pel array being successively read after above-mentioned exposure can be used for standard RGB patternsIn the framework of imaging sensor, to covering a corresponding color (R on each photodiode PD in each pixel unit：It is redColor, Gr：Green 1, Gb：Green 2, B：Blue) optical filter, using each photodiode PD monochromatic pixels basic as onePoint a, so that pixel unit can be as a dot structure of RGB pattern image sensors, to each pixel unit pointFour readings, i.e., be successively read four photodiode PD, obtains the optoelectronic induction of the corresponding four kinds of colors of R, Gr, Gb and BCharge component, then the rgb value of each pixel unit is calculated using linear interpolation algorithm.
In addition, the mode that is successively read of each pixel unit is not limited only to Fig. 3 and four photodiode PD shown in Fig. 4It is successively read mode, the reading manner that two of which or three photodiode PD can also be used to read simultaneously can be with viewAs the demand of sensor does flexible selection.
Four photodiode PD of each pixel unit can also use two of which photodiode PD or three lightThe reading manner that electric diode PD is read simultaneously, this pel array can be applied to HDR (high dynamic range) mode image sensingIn device.
As shown in fig. 6, in HDR pattern image sensors, to four kinds of monochromatic pixel R, Gr, Gb for constituting dot structureAnd B has carried out correction extension respectively, has obtained four kinds of monochrome correction pixel R ', Gr ', Gb ', B ', each dot structure includesEight kinds of monochromatic pixel R, R ', Gr, Gr ', Gb, Gb ', B, B ', it can be considered to by the corresponding correction of monochromatic pixelMonochromatic pixel framework is in the pixel unit of the embodiment of the present invention.
Based on this, as shown in fig. 6, the pel array of the embodiment of the present invention is applied to a kind of HDR pattern image sensorsIn, by the optical filter for covering different colours so that two photodiode PD in each pixel unit on a diagonal lineIt is and the monochromatic pixel pair for two photodiode PD on same monochromatic pixel (such as R), another diagonal lineThe monochrome correction pixel (such as R ') answered, four pixel units constitute a basic dot structure.In each pixel unit,It being read out at twice, two monochrome pixel such as R are read simultaneously, and two monochrome correction pixel such as R ' are read simultaneously, in conjunction withThe output information of twi-read calculates the rgb value of each dot structure in four pixel units, by increasing each dot structureThe number of middle monochrome pixel increases the monochromatic photosensitive area of each dot structure, can effectively improve the dynamic of imaging sensorRange.
The pel array that two photodiode PD are read simultaneously in four photodiode PD of each pixel unit is alsoAccommodation can be done, HDR pattern image sensor structures are still applied to.As shown in Figures 7 and 8, water in each pixel unitIt is flat adjacent or vertically adjacent to two photodiode PD be same monochromatic pixel (R, Gr, Gb, B), remaining two lightElectric diode PD is monochrome correction pixel corresponding with the monochrome pixel, and four pixel units constitute a basic picturesPlain structure.In each pixel unit, it is read out at twice：Two identical monochrome pixel such as R ' are read simultaneously, twoMonochrome correction pixel is read simultaneously, and each dot structure is calculated in conjunction with the output information of twi-read in four pixel unitsRgb value constitutes double PD image sensor architectures in HDR pattern image sensors.
Further, it is also possible to which as shown in figure 9, a photodiode PD is monochromatic pixel, residue in each pixel unitThree photodiode PD be monochrome correction pixel corresponding with the monochromatic pixel, four pixel units constitute oneBasic dot structure.In each pixel unit, it is read out at twice：One monochrome pixel such as R is individually read, threeMonochrome correction pixel such as R ' corresponding with the monochrome pixel is read simultaneously, in conjunction with twi-read in four pixel unitsOutput information calculates the rgb value of each dot structure, the HDR pattern image sensors in the form of this constitutes another.
Similar, three photodiode PD are read simultaneously in four photodiode PD of above-mentioned each pixel unitPel array apply also in RGB-IR pattern image sensors, as shown in Figure 10, a photoelectricity in each pixel unitDiode PD is near-infrared pixel IR, remaining three photodiode PD are same monochromatic pixel (R, Gr, Gb, B),Four pixel units constitute a basic dot structure.In each pixel unit, it is read out at twice：One near-infraredPixel IR is individually read, and three identical monochrome pixel such as R ' are read simultaneously, in conjunction with twi-read in four pixel unitsOutput information calculate the rgb value of each dot structure, a kind of imaging sensor of RGB-IR patterns is constituted with this.
Optionally, photoelectricity in four photodiodes of each pixel unit can also be read using reading manner simultaneously to imitateThe charge that should be generated, the sequential complete one of four transmission of control signals tx00, tx01, tx10 and tx11 in each pixel unitSample.As shown in figure 11, four two poles of photoelectricity with each pixel unit in one-row pixels unit are read using reading manner simultaneouslyThe charge of pipe PD.
Four photodiode PD in each pixel unit in every row are read simultaneously, it is each in corresponding every a lineAs seen in figures 11 or 12, four photodiode PD of each pixel unit are simultaneously turned on the timing control signal of pixel unitIt reads, compared to four photodiode PD are successively read achievable 4 times of frame per second, and increase the photosurface of single pixel pointProduct, improves sensitivity and the dynamic range of dot structure, is suitble to the application scenarios in dark.
Optionally, pel array that is above-mentioned while reading can be applied to black white image sensor and RGB addition scheme imagesIn sensor.As shown in figure 13, in RGB addition scheme imaging sensors, each dot structure includes four kinds of basic monochromesPixel R, Gr, Gb and B, and in each dot structure each monochromatic pixel number more than one.
Based on this, a kind of optical filter of color can be covered on each pixel unit of the embodiment of the present invention, is madeFor the base pixel unit of RGB addition scheme imaging sensors, as shown in figure 13.Four two poles of photoelectricity in each pixel unitPipe PD is one kind in monochromatic pixel R, Gr, Gb or B, and four pixel units constitute a basic dot structure.To eachFour photodiode PD in pixel unit gate reading simultaneously, and the output information read in conjunction with four pixel units calculates everyThe rgb value of a dot structure constitutes the imaging sensor of RGB addition schemes with this, while also effectively increasing the frame of imageRate and dynamic range.
It should be noted that under the global exposure mode of pel array, four photodiodes in each pixel unitThe reading of PD can only be read simultaneously, i.e., under global exposure mode, four photodiode PD of each pixel unit are simultaneouslyExposure and reading, and four photodiode PD read obtained output signal and preserve in a storage module simultaneously.
In conclusion in pel array provided in an embodiment of the present invention, two pole of multiple photoelectricity in each pixel unitPipe is connected to floating diffusion nodes each by a corresponding transmission transistor, and reset transistor and reading circuit are all connected withTo floating diffusion nodes so that multiple photodiodes share reset circuit and reading circuit, effectively increase dot structureFill factor, to increase sensitivity and signal-to-noise ratio；And multiple transmission transistors in each pixel unit are corresponding each respectivelyFrom transmission of control signals, can freedom and flexibility select the Exposure mode and reading manner of each pixel unit, be suitable for rolling and exposeLight or the image sensor architecture of global exposure, in the imaging sensor using above-mentioned pel array, by pel arrayThe combination of multiple pixel units or the reading control of pixel unit internal photo, can properly increase the dynamic of imaging sensorState range, sensitivity and frame per second, while the image application demand of black and white or colored various modes can be met, effectively enhance the pictureThe practicability and portability of pixel array.
The preferred embodiment of the present invention is above are only, does not play the role of any restrictions to the present invention.Belonging to anyThose skilled in the art, in the range of not departing from technical scheme of the present invention, to the invention discloses technical solution andTechnology contents make the variations such as any type of equivalent replacement or modification, belong to the content without departing from technical scheme of the present invention, stillWithin belonging to the scope of protection of the present invention.