Source: https://patents.google.com/patent/CN101404140B/en
Timestamp: 2020-07-09 06:22:50
Document Index: 753781851

Matched Legal Cases: ['art 209', 'art 209', 'arts 101', 'art 101', 'art 111', 'art 112', 'art 112', 'art 121', 'art 123', 'art 123', 'art 131', 'art 134', 'art 134', 'art 141']

CN101404140B - Display device and electronic equipment - Google Patents
CN101404140B
CN101404140B CN2008102109785A CN200810210978A CN101404140B CN 101404140 B CN101404140 B CN 101404140B CN 2008102109785 A CN2008102109785 A CN 2008102109785A CN 200810210978 A CN200810210978 A CN 200810210978A CN 101404140 B CN101404140 B CN 101404140B
CN2008102109785A
CN101404140A (en
2007-08-15 Priority to JP211623/07 priority
2008-08-15 Application filed by 索尼株式会社 filed Critical 索尼株式会社
2009-04-08 Publication of CN101404140A publication Critical patent/CN101404140A/en
2010-12-15 Publication of CN101404140B publication Critical patent/CN101404140B/en
The present invention relates to a display device and an electronic apparatus with the display device. Disclosed herein is a display device including a pixel array section; power supply lines; and auxiliary electrodes, wherein the pixels each have an auxiliary capacitance, and one of electrodes of the auxiliary capacitance is connected to the source electrode of the drive transistor, and an other electrode connected to the auxiliary electrode for each pixel.
The present invention relates to display device and electronic installation, relate more specifically to flat panel display equipment and have this flat panel display equipment, wherein each has incorporated the electronic installation of the pixel of electrooptic cell into matrix arrangement.
In the field of image display, have with matrix arrangement each flat panel display equipment of having incorporated the pixel of electrooptic cell into and become extensive just rapidly.In flat panel display equipment, use the exploitation and the commercialization of the organic EL display apparatus of organic EL (electroluminescence) element to steer a steady course.Organic EL is the current drive-type electrooptic cell, and its luminosity changes according to the electric current of this element of flowing through.Such element relies on the luminous phenomenon of organic film when being supplied electric field.
Organic EL display apparatus has following feature.That is, its power consumption is low, because can drive organic EL by 10V or littler voltage.In addition, organic EL is self luminous.Therefore, be designed to by to each pixel control of comprising liquid crystal cells from the light intensity of light source (backlight) and the liquid crystal display of display image is compared, organic EL display apparatus provides higher image visibility.In addition, organic EL display apparatus need be such as the required illumination composition backlight (lighting members) of liquid crystal display, therefore feasible easier reduction weight and thickness.And the organic EL response speed is exceedingly fast, perhaps about a few μ second.This provides and the irrelevant mobile image of afterimage.
Organic EL display apparatus can be as employed simple (passive) matrix of liquid crystal display or driven with active matrix.Yet although should be noted that simple in structurely, the simple matrix display device has some problems.This problem comprises and is difficult to realize big high definition display device, because along with the increase of sweep trace quantity (being pixel count), the luminous period of electrooptic cell reduces.
Owing to this reason, in recent years, carrying out the exploitation of active matrix display device enthusiastically.This display device is provided by the active component such as insulated gate FET (typically, thin film transistor (TFT) broad sense TFT) that provides in the image element circuit identical with electrooptic cell by the electric current of the electrooptic cell of flowing through.In active matrix display device, electrooptic cell is kept and is surpassed the luminous of a frame period.As a result, can be easy to realize big high definition display device.
Incidentally, the I-V characteristic (I-E characteristic) of typical known organic EL worsens (the so-called time worsens) in time.In the image element circuit that uses the N channel TFT as the organic EL that is applicable to current drives (hereinafter writing " driving transistors "), organic EL is connected to the source electrode of driving transistors.Therefore, if the I-V characteristic of organic EL worsens in time, then the grid of driving transistors changes to source voltage Vgs, therefore changes the luminosity of this element.
This will more specifically describe below.Determine the source potential of driving transistors by the operating point between driving transistors and the organic EL.If the I-V characteristic degradation of organic EL, then the operating point between driving transistors and the organic EL will change.Therefore this grid that changes driving transistors changes the electric current of the driving transistors of flowing through to source potential Vgs.Therefore, the flow through electric current of organic EL also changes.As a result, light emission luminance changes.
On the other hand, in the image element circuit that uses multi-crystal TFT, except the I-V characteristic worsens in time, because manufacture process conversion (transistor has different characteristics), the mobility [mu] of the semiconductive thin film of the raceway groove of the threshold voltage vt h of driving transistors or formation driving transistors (hereinafter writing " mobility of driving transistors ") is along with the time change or from the pixel to pixel difference.
If the threshold voltage vt h of driving transistors or mobility [mu] are from the pixel to pixel difference, the electric current of the driving transistors of then flowing through changes from pixel to pixel.Therefore, the identical voltage that is applied to the grid of driving transistors causes light emission luminance difference between pixel, has therefore weakened the screen homogeneity.
Therefore, compensation and calibration function are provided in each pixel, the threshold voltage vt h or the mobility [mu] that worsen in time with driving transistors with the I-V characteristic of guaranteeing to resist organic EL change in time, therefore keep light emission luminance constant (for example referring to the open No.2006-133542 (hereinafter being called patent document 1) of Jap.P.).The variation of the characteristic of compensate function compensation organic EL.One of calibration function is proofreaied and correct the variation (hereinafter writing " threshold value correction ") of the threshold voltage vt h of driving transistors.Another calibration function is proofreaied and correct the variation (hereinafter writing " mobility correction ") of the mobility [mu] of driving transistors.
In the prior art that patent document 1 is described, in each pixel, provide the compensate function and the calibration function that is applicable to the variation of corrected threshold voltage Vth and mobility [mu] of the variation of the characteristic that is applicable to the compensation organic EL.This guarantees that I-V characteristic to organic EL worsens threshold voltage vt h and the time dependent opposing of mobility [mu] with driving transistors in time, and it is constant therefore to keep light emission luminance.Yet prior art need be formed each pixel by a plurality of elements, therefore causes overslaugh to reduce Pixel Dimensions, and passes through the more display device of high definition by expansion.
On the other hand, be identified for writing gain (will describe its details after a while) by capacitance component with what vision signal was write pixel such as the factor of the capacitance that is applicable to the maintenance electric capacity that keeps the vision signal write and organic EL.Along with the sharpness raising of display device, it is meticulousr that Pixel Dimensions becomes.As a result, constitute the organic electrode of organic EL and become littler.Thereby the capacitance of the capacitance component of organic EL is littler, therefore causes lower vision signal to write gain.Reduce if writing gain, then keep to keep being suitable in the electric capacity signal potential of vision signal.As a result, may not realize being suitable for the luminosity of vision signal.
Consider abovely, a purpose of embodiments of the invention provides a kind of display device and has the electronic installation of this display device, and each of the pixel of this display device is made of assembly still less, and can guarantee that enough vision signals write gain.
In order to realize above expectation, display device is defined as according to an embodiment of the invention, and it comprises pixel array portion, power lead and auxiliary electrode.Pixel array portion comprises the pixel of arranging with matrix form.Each pixel comprises electrooptic cell and is applicable to the write transistor that writes vision signal and is applicable to the maintenance electric capacity of the vision signal that maintenance is write by write transistor.Each pixel also comprises the driving transistors that is applicable to based on driven electrooptic cell by the vision signal that keeps electric capacity to keep.Power lead is arranged to for pixel array portion with near one of each pixel column that belongs to the capable sweep trace of neighborhood pixels.Power lead selectively is applied to first electromotive force and second electromotive force that is lower than first electromotive force drain electrode of driving transistors.Arrange auxiliary electrode with row with row or with grid configuration for the described pixel array section of arranging with matrix form.Auxiliary electrode has been applied in fixed potential.Each has auxiliary capacitor pixel.One of electrode of auxiliary capacitor is connected to the source electrode of driving transistors.Its another electrode is connected to the auxiliary electrode that is used for each pixel.
As above the configuration display device and have in the electronic installation of this display device, first and second electromotive forces selectively are applied to the drain electrode of driving transistors via power lead.Being supplied driving transistors from the electric current of power lead, to drive electrooptic cell when being supplied first electromotive force luminous.When being supplied second electromotive force, it is luminous that driving transistors does not drive electrooptic cell.As a result, driving transistors has control electrooptic cell ability luminous and not luminous and the current drives electrooptic cell.This has eliminated for being specially adapted to control luminous and non-luminous transistorized needs.
In addition, because the capacitance component by electrooptic cell and the capacitance of maintenance and auxiliary capacitor are determined gain, so one of its end auxiliary capacitor of being connected to the source electrode of driving transistors makes it possible to capacitance by auxiliary capacitor and increases vision signal and write gain.At this, for the pixel array section of arranging with matrix form with row, with row or with the grid configuration step and be applied in fixed potential auxiliary electrode each be connected to one of electrode of the auxiliary capacitor that is used for each pixel.Another electrode that this makes it possible to fixed potential is applied to auxiliary capacitor provides any negative electrode distribution and not be used in the TFT layer, therefore allow to be formed for the auxiliary capacitor of fixed potential.
Fig. 1 is the system layout of the illustrative configurations of the primary active matrix organic EL display apparatus of diagram embodiments of the invention;
Fig. 2 is the circuit diagram of the concrete configuration example of diagram pixel (image element circuit);
Fig. 3 is the timing waveform that is used to describe the operation of the primary active matrix organic EL display apparatus of embodiments of the invention;
Fig. 4 A is the exemplary plot (1) of the circuit operation of the primary active matrix organic EL display apparatus of diagram embodiments of the invention to 4D;
Fig. 5 A is the exemplary plot (2) of the circuit operation of the primary active matrix organic EL display apparatus of diagram embodiments of the invention to 5D;
Fig. 6 A is the exemplary plot (3) of the circuit operation of the primary active matrix organic EL display apparatus of diagram embodiments of the invention to 6C;
Fig. 7 is the performance plot that is used to describe the problem that the threshold voltage vt h by driving transistors causes;
Fig. 8 is the performance plot that is used to describe the problem that the mobility [mu] by driving transistors causes;
Fig. 9 A is the performance plot that is used to describe the relation between the drain-to-source electric current I ds that has and do not have mobility timing video voltage Vsig and driving transistors to 9C;
Figure 10 is the circuit diagram that diagram has the pixel arrangement of auxiliary capacitor;
Figure 11 is the equivalent circuit diagram that illustrates the wiring resistance R that is caused by the negative electrode distribution that operates in the TFT layer;
Figure 12 is the timing waveform that illustrates the variation of the cathode potential that is caused by wiring resistance R;
Figure 13 is the figure that illustrates the horizontal crosstalk that is caused by wiring resistance R;
Figure 14 is the planimetric map that diagram is used for the topology example of the auxiliary electrode arranged with the pixel of matrix form;
Figure 15 is the planimetric map that indicative icon has the pixel arrangement structure of auxiliary capacitor;
Figure 16 is the sectional view of diagram according to the cross-section structure of the pixel of example 1;
Figure 17 is the sectional view of diagram according to the cross-section structure of the pixel of example 2;
Figure 18 is the sectional view of diagram according to the cross-section structure of the pixel of example 3;
Figure 19 is the skeleton view that illustrates the outward appearance of the televisor of using embodiments of the invention;
Figure 20 A and 20B are the skeleton views of the outward appearance of the diagram digital camera of using embodiments of the invention, and Figure 20 A is the skeleton view of looking from the front side, and Figure 20 B is the skeleton view of looking from rear side.
Figure 21 is the skeleton view that illustrates the outward appearance of the laptop PC of using embodiments of the invention;
Figure 22 is the skeleton view that illustrates the outward appearance of the video camera of using embodiments of the invention;
Figure 23 A is the outside figure of mobile phone that diagram is used embodiments of the invention to 23G, and Figure 23 A is the front view of the mobile phone when being shown in an open position, Figure 23 B is its side view, Figure 23 C is in the front view that closes the mobile phone when closing the position, Figure 23 D is its left hand view, Figure 23 E is its right part of flg, and Figure 23 F is its top view, and Figure 23 G is its backplan.
Embodiments of the invention provide the driving transistors of the ability of luminous and not luminous and this electrooptic cell of current drives with control electrooptic cell.This makes it possible to use assembly still less, and promptly only write transistor and driving transistors are formed each pixel.Simultaneously, except keeping electric capacity,, can obtain enough vision signals and write gain by auxiliary capacitor is provided.
In addition, for each pixel, another electrode of auxiliary capacitor is connected to one of auxiliary electrode, and wherein for the pixel in the pixel array portion of arranging with matrix form, auxiliary electrode is with row, to be listed as or to arrange with grid configuration.This makes it possible to will fixing electromotive force be applied to another electrode and not be used in any negative electrode distribution is provided in the TFT layer.As a result, when suppressing wiring resistance, can form auxiliary capacitor for fixing electromotive force.This has suppressed the horizontal crosstalk that caused by wiring resistance, and therefore the picture quality on the improved screen is provided.
Provide the detailed description of the preferred embodiments of the present invention below with reference to the accompanying drawings.
[display device that the present invention is primary]
Fig. 1 is the system layout of the illustrative configurations of the primary active matrix display device of diagram embodiments of the invention.
At this, will adopt the active matrix organic EL display apparatus to provide description as an example.Organic EL display apparatus uses the light-emitting component of organic EL (organic electroluminescent device) as (image element circuit) of each pixel, wherein the organic EL current drives electrooptic cell that to be luminosity change according to the electric current of the element of flowing through.
As shown in Figure 1, organic EL display apparatus 10 comprises pixel array portion 30 and drive part.Pixel array portion 30 have pixel (PXLCs) 20. drive parts of arranging two-dimensionally with matrix form be disposed in pixel array portion 30 around, and be applicable to and drive pixel 20.Among the drive part that is applicable to driving pixel 20 is to write sweep circuit 40, power supply sweep circuit 50 and horizontal drive circuit 60.
Pixel array portion 30 have the sweep trace 31-1 that arranges for each pixel column to one of 31-m and power lead 32-1 to one of 32-m and for each pixel column signal line disposed 33-1 of the pixel that is listed as arrangement with the capable n of taking advantage of of m to one of 33-n.
Pixel array portion 30 typically be formed on such as on the transparent insulation substrate of glass substrate so that slab construction to be provided.Can use non-crystalline silicon tft (thin film transistor (TFT)) or low temperature polycrystalline silicon TFT to form the pixel 20 of pixel array portion 30.When using low temperature polycrystalline silicon TFT, also can go up and realize writing sweep circuit 40, power supply sweep circuit 50 and horizontal drive circuit 60 at the display board (substrate) that forms pixel array portion 30.
Write sweep circuit 40 comprise shift register or be applicable to time clock ck synchronously in turn displacement (transmissions) begin other assembly of pulse sp.During the pixel 20 to pixel array portion 30 writes vision signal, write sweep circuit 40 and in turn write pulse WS1 is supplied to sweep trace 31-1 respectively to 31-m to WSm (sweep signal), so that with the pixel 20 of basis (progressive scan) continuous sweep pixel array portion 30 line by line.
Power supply sweep circuit 50 comprise shift register or be applicable to time clock ck synchronously in turn displacement (transmissions) begin other assembly of pulse sp.Power supply sweep circuit 50 synchronously is supplied to power lead 32-1 respectively for 32-m with power lead electromotive force DS1 to DSm in turn and optionally with the progressive scan of writing sweep circuit 40, so that control pixel 20 is luminous and not luminous.At the i.e. first electromotive force Vccp and be lower than Switching power line electromotive force DS1 between the second electromotive force Vini of the first electromotive force Vccp of two different electromotive forces to each of DSm.
Horizontal drive circuit 60 select to be suitable for the video voltage Vsig (hereinafter can be abbreviated as " signal voltage ") of monochrome information or from the offset voltage Vofs of signal source (not shown) supply as being fit to, so that for example to 33-m selected voltage is write the pixel 20 of pixel array portion 30 via signal wire 33-1 with basis line by line.That is, horizontal drive circuit 60 adopts and is applicable to that the basis writes the progressive of video voltage Vsig in turn and writes (to pursue line) line by line.
At this, offset voltage Vofs is the reference voltage voltage of black level (for example, corresponding to) as the reference of video voltage Vsig.On the other hand, the second electromotive force Vinin is set to be lower than the electromotive force of offset voltage Vofs.For example, suppose that the threshold voltage of moving transistor 22 is represented that by Vth then second electromotive force is set to be lower than the electromotive force of Vofs-Vth, and preferably enough be lower than the electromotive force of Vofs-Vth.
(image element circuit)
Fig. 2 is the circuit diagram of the object lesson of diagram pixel (image element circuit) 20 configuration.
As shown in Figure 2, pixel 20 comprises that the organic EL 21 of the current drive-type electrooptic cell that luminosity for example changes according to the electric current of the element of flowing through is as light-emitting component.Except organic EL 21, pixel 20 comprises driving transistors 22, write transistor 23 and keeps electric capacity 24 as its assembly.That is, pixel 20 is made up of two transistors (Tr) and a capacitor (C).
In configuration pixel 20 as above, use the N channel TFT as driving transistors 22 and write transistor 23.Yet, should be noted that the combination of the conduction type of driving transistors 22 given herein and write transistor 23 only is an example, and embodiments of the invention are not limited thereto combination.
The cathode electrode of organic EL 21 is connected to the public power wire 34 that all pixels 20 are arranged publicly.The source electrode of driving transistors 22 is connected to the anode electrode of organic EL 21, and its drain electrode is connected to power lead 32 (32-1 is to one of 32-m).
The gate electrode of write transistor 23 is connected to sweep trace 31 (31-1 is to one of 31-m).One of the source electrode of write transistor 23 and drain electrode are connected to signal wire 33 (33-1 is to one of 33-m), and another of source electrode and drain electrode is connected to the gate electrode of driving transistors 22.
One of electrode that keeps electric capacity 24 is connected to the gate electrode of driving transistors 22.Another electrode of maintenance electric capacity 24 is connected to the source electrode (anode electrode of organic EL 21) of driving transistors 22.
In the pixel of being made up of two transistors and capacitor 20, write transistor 23 is in response to being applied to the sweep signal of its gate electrode via sweep trace 31 and conducting electricity by writing sweep circuit 40.Along with write transistor 23 conductions, its sampling is suitable for the video voltage Vsig of monochrome information or the offset voltage Vofs that supplies from horizontal drive circuit 60 via signal wire 33, and the voltage of sampling is write pixel 20.
Signal voltage Vsig that writes or offset voltage Vofs are applied to the gate electrode of driving transistors 22, and simultaneously by keeping electric capacity 24 to keep.When the electromotive force DS of power lead 32 (32-1 is to one of 32-m) was in the first electromotive force Vccp, driving transistors 22 had been supplied the electric current from power lead 32.As a result, driving transistors 22 is supplied its level to organic EL and is suitable for drive current by the voltage level of the signal voltage Vsig that keeps electric capacity 24 to keep, so current drives organic EL 21 is with luminous.
(circuit operation of organic EL display apparatus)
Next will and use the operation example figure shown in Fig. 4 to 6 to provide the description of circuit operation of the organic EL display apparatus 10 of above-mentioned configuration based on the timing waveform of Fig. 3.Should be noted that in the operation example figure shown in Fig. 4 to 6,, represent write transistor 23 by switch symbols in order to simplify.Shall also be noted that because organic EL 21 has capacitance component, therefore also show its EL electric capacity 25.
Timing waveform among Fig. 3 illustrates electromotive force (write pulse) WS of sweep trace 31 (31-1 is to one of 31-m), electromotive force Ds (Vccp/Vini) and the grid potential Vg of driving transistors 22 and the variation of source potential Vs of power lead 32 (32-1 is to one of 32-m).
＜luminous the period 〉
In the sequential chart of Fig. 3, organic EL 21 (luminous period) before time t1 is luminous.In the luminous period, the electromotive force DS of power lead 32 is in the first electromotive force Vccp, and write transistor 23 is non-conductive.
At this moment, because driving transistors 22 is designed to operate in the saturation region, therefore be suitable for the grid of driving transistors 22 and be supplied to organic EL 21 from power lead 32 via driving transistors 22, shown in Fig. 4 A to drive current (drain-to-source electric current) Ids of source voltage Vgs.As a result, organic EL 21 emission brightness are suitable for the light of the level of drive current Ids.
＜be used for the preparation period that threshold value is proofreaied and correct 〉
Then, at time t1, new one progressive scan begins.The electromotive force DS of power lead 32 changes to second electromotive force (hereinafter writing " low potential ") Vini (Vofs: the offset voltage of signal wire 33) that enough is lower than Vofs-vth from first electromotive force (hereinafter writing " high potential ") Vccp.
At this, suppose to represent the threshold voltage of organic EL 21, and represent the electromotive force of public power wire 34, and supposition is for low potential Vini, Vini＜Vel+Vcath, then the source potential Vs of driving transistors 22 low potential Vini no better than by Vcath by Vel.As a result, organic EL 21 is reverse biased, and it is luminous to cause it to stop.
Next, at time t2, the electromotive force WS of sweep trace 31 changes to high potential from low potential, makes write transistor 23 conductions, shown in Fig. 4 C.At this moment, horizontal drive circuit 60 is supplied to signal wire 33 with offset voltage Vofs.Therefore, the grid potential Vg of driving transistors 22 becomes and equals offset voltage Vofs.In addition, the source potential Vs of driving transistors 22 is in the low potential Vini that enough is lower than offset voltage Vofs.
At this moment, the grid of driving transistors 22 is Vofs-Vini to source voltage Vgs.At this, can not carry out the threshold value correct operation, unless Vini is greater than the threshold voltage vt h of driving transistors 22.Therefore, need set up the electromotive force relation of Vofs-Vini＞Vth.Therefore, the threshold value preparatory function of proofreading and correct comprises the grid potential Vg of driving transistors 22 and source potential Vs be respectively fixed to and is used for initialized offset voltage Vofs and low potential Vini.
＜first threshold is proofreaied and correct the period 〉
Next, at time t3, along with the electromotive force DS of power lead 32 changes to high potential Vccp from low potential Vini, shown in Fig. 4 D, the source potential Vs of driving transistors 22 begins to raise, and the beginning first threshold is proofreaied and correct the period.Proofread and correct in the period in first threshold, along with the source potential Vs rising of driving transistors 22, the grid of driving transistors 22 reaches given electromotive force Vx1 to source potential Vgs.Electromotive force Vx1 is by keeping electric capacity 24 to keep.
Next, at time t4, in the horizontal interval (1H) back half, horizontal drive circuit 60 is supplied to signal wire 33 with video voltage Vsig, shown in Fig. 5 A, the electromotive force of signal wire 33 is changed to signal voltage Vsig from offset voltage Vofs.In the section, signal voltage Vsig is written to the pixel in another row at this moment.
At this moment, be written to oneself capable pixel in order to prevent signal voltage Vsig, the electromotive force WS of sweep trace 31 changes to low potential from high potential, makes write transistor 23 non-conductive.This gate electrode and signal wire 33 with driving transistors 22 disconnects, and gate electrode is floated.
At this, if the gate electrode of driving transistors 22 floats, if and owing to cause that in the disconnection of the grid of driving transistors 22 and the maintenance electric capacity 24 between the source electrode source potential Vs of driving transistors 22 changes, then the grid potential Vg of driving transistors 22 also changes (follow this variation and change) along with the variation of source potential Vs.This is the bootstrapping action that keeps electric capacity 24.
At time t4 and afterwards, the source potential Vs of driving transistors 24 Va1 (VS=Vofs-Vx1+Va1) that continues to have raise.At this moment, because bootstrapping action, along with the rising of the source potential Vs of driving transistors 22, the grid potential Vg of driving transistors 22 Va1 (Vg=Vofs+Va1) that also raise.
＜the second threshold value is proofreaied and correct the period 〉
At time t5, next horizontal interval begins.Shown in Fig. 5 B, the electromotive force WS of sweep trace 31 changes to high potential from low potential, makes write transistor 23 conductions.Simultaneously, horizontal drive circuit 60 is supplied to signal wire 33 with offset voltage Vofs rather than signal voltage Vsig, begins second threshold value and proofreaies and correct the period.
Proofread and correct in the period in second threshold value, along with write transistor 23 conductions, offset voltage Vofs is written into.Therefore, the grid potential Vg of driving transistors 22 is initialized to offset voltage Vofs once more.At this moment, source potential Vs falls along with the whereabouts of grid potential Vg.Then, the source potential Vs of driving transistors 22 begins to raise once more.
Then, raise along with the source potential Vs of driving transistors 22 proofreaies and correct in the period in second threshold value, the grid of driving transistors 22 reaches given electromotive force Vx2 to source voltage Vgs.Electromotive force Vx2 is by keeping electric capacity 24 to keep.
Next, at time t6, the horizontal interval back half, horizontal drive circuit 60 is supplied to signal wire 33 with signal voltage Vsig, shown in Fig. 5 C, makes the electromotive force of signal wire 33 change to signal voltage Vsig from offset voltage Vofs.Section at this moment, signal voltage Vsig is written to pixel (the then row of the row that was written into last time of pixel) of another row.
At this moment, be written to self capable pixel in order to prevent signal voltage Vsig, the electromotive force WS of sweep trace 31 changes to low potential from high potential, makes write transistor 23 non-conductive.This gate electrode and signal wire 33 with driving transistors 22 disconnects, and gate electrode is floated.
At time t6 and afterwards, the source potential Vs of driving transistors 22 Va2 (Vs=Vofs-Vx1+Va2) that continues to have raise.At this moment, because bootstrapping action, along with the source potential Vs of driving transistors 22 raises, the grid potential Vg of driving transistors 22 Va2 (Vg=Vofs+Va2) that also raise.
＜the three threshold value is proofreaied and correct the period 〉
At time t7, next horizontal interval begins.Shown in Fig. 5 D, the electromotive force WS of sweep trace 31 changes to high potential from low potential, makes write transistor 23 conductions.Simultaneously, horizontal drive circuit 60 is supplied to signal wire 33 with offset voltage Vofs rather than signal voltage Vsig, begins the 3rd threshold value and proofreaies and correct the period.
Proofread and correct in the period in the 3rd threshold value, along with write transistor 23 conductions, offset voltage Vofs is written into.Therefore, the grid potential Vg of driving transistors 22 is initialized to offset voltage Vofs once more.At this moment, source potential Vs falls along with the whereabouts of grid potential Vg.Then, the source potential Vs of driving transistors 22 begins to raise once more.
Along with the source potential Vs rising of driving transistors 22, in the near future, the grid of driving transistors 22 will be assembled the threshold voltage vt h of driving transistors 22 to source voltage Vgs.As a result, the voltage corresponding to threshold voltage vt h is kept by maintenance electric capacity 24.
Owing to above-mentioned the 3rd threshold value correct operation, detect the threshold voltage vt h of the driving transistors 22 in each pixel, and keep by maintenance electric capacity 24 corresponding to the voltage of threshold voltage vt h.Should be noted that in the 3rd threshold value is proofreaied and correct the period electromotive force Vcath that public power wire 34 is set makes organic EL 21 reach to end.Do like this to guarantee that electric current only flows to and keep electric capacity 24, and do not flow to organic EL 21.
＜signal writes the period and mobility is proofreaied and correct the period 〉
Next, at time t8, the electromotive force WS of sweep trace 31 changes to low potential, makes write transistor 23 non-conductive, as shown in Figure 6A.Simultaneously, the electromotive force of signal wire 33 changes to video voltage Vsig from offset voltage Vofs.
Along with write transistor 23 stops conduction, the gate electrode of driving transistors 22 is placed in unsteady.Yet the grid of driving transistors 22 equals the threshold voltage vt h of driving transistors 22 to source voltage Vgs.Therefore, driving transistors 22 is in and ends.As a result, the drain-to-source electric current I ds driving transistors 22 of not flowing through.
Next, at time t9, the electromotive force WS of sweep trace 31 changes to high potential, makes write transistor 23 conductions, shown in Fig. 6 B.As a result, write transistor 23 sample video signal voltage Vsig, and this voltage write pixel 20.Write transistor 23 write signal voltage Vsig make the grid potential Vg of driving transistors 22 equal signal voltage Vsig.
Then, when driving transistors 22 usefulness video voltage Vsig drive organic EL 21, the threshold voltage vt h of driving transistors 22 by by keep electric capacity 24 that keep, eliminate corresponding to the voltage of threshold voltage vt h, realize that therefore threshold value proofreaies and correct.The principle that threshold value is proofreaied and correct will be described after a while.
At this moment, organic EL 21 at first is in by (high impedance status).Therefore, flow to the EL electric capacity 25 of organic EL 21, therefore begin the charging of EL electric capacity 25 according to the electric current (drain-to-source electric current I ds) that flows to driving transistors 22 from power lead 32 of video voltage Vsig.
Because the charging of EL electric capacity 25, the source potential Vs of driving transistors 22 raises in time.At this moment, the variation of the threshold voltage vt h of driving transistors 22 is corrected (passing threshold correction).As a result, the drain-to-source electric current I ds of driving transistors 22 only depends on the mobility [mu] of driving transistors 22.
When the source potential Vs of driving transistors 22 in the near future is elevated to when equaling Vofs-Vth+ Δ V electromotive force, the grid of driving transistors 22 becomes to source voltage Vgs and equals Vsig-Vofs+Vth-Δ V.That is, the increment Delta V of source potential Vs works and makes it from by deducting the voltage (Vsig-Vofs+Vth) that keeps electric capacity 24 to keep, so that will keep in the electric capacity 24 charge stored to discharge.This means and used negative feedback.Therefore, the increment Delta V of the source potential Vs of driving transistors 22 is degenerative feedback quantity.
As mentioned above, the grid that the drain-to-source electric current I ds of driving transistors 22 is got back to driving transistors 22 by negative feedback if flow through is imported, and promptly grid can be eliminated the dependence of the drain-to-source electric current I ds of driving transistors 22 to mobility [mu] to source voltage Vgs.That is the variation of the mobility [mu] between, can correction pixels.
More specifically, video voltage Vsig is big more, and drain-to-source electric current I ds is big more, so the absolute value of amount of negative feedback (correcting value) Δ V is big more.As a result, proofread and correct mobility according to luminosity.If it is constant that video voltage Vsig keeps, then the mobility [mu] of driving transistors 22 is big more, and the absolute value of amount of negative feedback Δ V is big more.This makes it possible to eliminate the variation of the mobility [mu] between the pixel.The principle that mobility is proofreaied and correct will be described after a while.
Next, at time t10, the electromotive force WS of sweep trace 31 changes to low potential, makes write transistor 23 non-conductive, shown in Fig. 6 C.This gate electrode and signal wire 33 with driving transistors 22 disconnects, and makes gate electrode float.
When being placed in, the gate electrode of driving transistors 22 floats and when the drain-to-source electric current I ds of driving transistors 22 began to flow into organic EL 21 simultaneously, the anode potential of organic EL 21 raise according to the drain-to-source electric current I ds of driving transistors 22.
The rising of the anode potential of organic EL 21 only is the rising of the source potential Vs of driving transistors 22.Along with the source potential Vs rising of driving transistors 22, because the bootstrapping action, the grid potential Vg of driving transistors 22 also will raise.
At this moment, suppose that the bootstrapping gain is unified (ideal value), then the increment of grid potential Vg equals the increment of source potential Vs.Therefore in the luminous period, the grid of driving transistors 22 is kept the constant Vsig-Vofs+Vth-Δ V that is to source voltage Vgs.Then, at time t11, the electromotive force of signal wire 33 changes to offset voltage Vofs from video voltage Vsig.
As very clear from the foregoing description of operation, threshold value is proofreaied and correct the period and has been crossed over three horizontal intervals, promptly carries out signal therebetween and writes horizontal interval and two horizontal intervals before this horizontal interval of proofreading and correct with mobility.This proofreaies and correct the period for threshold value time enough is provided, and therefore allows the threshold voltage vt h of reliable detection driving transistors 22, and this voltage remained on keeps being used for this reliable threshold value correct operation in the electric capacity 24.
Although threshold value is proofreaied and correct the period and crossed over three horizontal intervals, this only is an example.Write the horizontal interval of proofreading and correct to proofread and correct the period for threshold value enough if carry out signal therebetween, then do not need to provide the threshold value of the horizontal interval before crossing over to proofread and correct the period with mobility.On the other hand, if owing to provide higher sharpness thereby horizontal interval to become shorter, and if to proofread and correct the period for threshold value not enough three horizontal intervals, and then this period can cross over four horizontal intervals or longer.
(principle that threshold value is proofreaied and correct)
At this, the description of the principle that the threshold value that provides driving transistors 22 is proofreaied and correct.Driving transistors 22 is designed to operate in the saturation region.Therefore, driving transistors 22 runnings are constant current source.As a result, constant drain-to-source electric current (drive current) Ids that is provided by following formula (1) is supplied to organic EL 21 from driving transistors 22:
Ids＝(1/2)·μ(W/L)Cox(Vgs-Vth) 2 (1)
Wherein W is a channel width, and L is a channel length, and Cox is the grid capacitance of per unit area.
Fig. 7 illustrates the characteristic of the grid of the drain-to-source electric current I ds of driving transistors 22 and driving transistors 22 to source voltage Vgs.
So shown in the performance plot, unless proofreaied and correct the variation of the threshold voltage vt h of the driving transistors 22 between the pixel, otherwise when threshold voltage vt h is Vth1, being suitable for grid is Ids1 to the drain-to-source electric current I ds of source voltage Vgs.
On the contrary, when threshold voltage be that (during Vth2＞Vth1), be suitable for grid is Ids2 (Ids2＜Ids) to the drain-to-source electric current I ds of source voltage Vgs to Vth2.That is, even grid remains unchanged to source voltage Vgs, drain-to-source electric current I ds is also along with the change of the threshold voltage vt h of driving transistors 22 and change.
On the other hand, in the pixel (image element circuit) 20 of as above configuration, as described above, the grid of driving transistors 22 is Vsig-vofs+Vth-Δ V to source voltage Vgs between light emission period.This is substituted in the equation (1), and drain-to-source electric current I ds is expressed as follows:
Ids＝(1/2)·μ(W/L)Cox(Vsig-Vofs-ΔV) 2 (2)
That is, cancellation the item of threshold voltage vt h of driving transistors 22.Self-driven transistor 22 is supplied to the drain-to-source electric current I ds of organic EL 21 and the threshold voltage vt h of driving transistors 22 has nothing to do.As a result, change still change in time no matter change the threshold voltage vt h that causes driving transistors 22 owing to manufacture craft from pixel to pixel, drain-to-source electric current I ds remains unchanged.This luminosity that makes it possible to keep organic EL 21 is constant.
(principle that mobility is proofreaied and correct)
Next will provide the description of the principle that the mobility of driving transistors 22 proofreaies and correct.The family curve of the pixel A that Fig. 8 illustrates the mobility [mu] that relatively has relatively large driving transistors 22 and the pixel B of mobility [mu] with relative less driving transistors 22.If driving transistors 22 comprises for example polycrystalline SiTFT, then inevitably, for pixel A and B, mobility [mu] changes from pixel to pixel.
If for example be applied to pixel A and B when there is the video voltage Vsig that will be in same level when changing in mobility [mu] between two pixel A and B, then very big-difference will be arranged, unless proofread and correct mobility [mu] in one or another kind of mode at the drain-to-source electric current I ds1 ' of the pixel A of flowing through with between the drain-to-source electric current I ds2 ' of the pixel B of flowing through with less mobility [mu] with big mobility [mu].Therefore, since the variation of mobility [mu] between the pixel cause having weakened the screen homogeneity under the situation of very big-difference of drain-to-source electric current I ds.
As very clear from the above transistor characteristic formula (1) that provides, mobility [mu] is big more, and drain-to-source electric current I ds is big more.Therefore, mobility [mu] is big more, and amount of negative feedback Δ V is big more.As shown in Figure 8, has the amount of negative feedback Δ V1 of pixel A of big mobility [mu] greater than the amount of negative feedback Δ V2 of pixel B with less mobility [mu].
Owing to this reason, if by the mobility correct operation, the drain-to-source electric current I ds of driving transistors 22 is got back to video voltage Vsig by negative feedback, and then mobility [mu] is big more, and it is big more to use degenerative scope.This has suppressed the variation of mobility [mu] from pixel to pixel.
More specifically, if proofread and correct the pixel A with big mobility [mu] with amount of negative feedback Δ V1, then drain-to-source electric current I ds significantly drops to Ids1 from Ids1 '.On the other hand, it is very little to have an amount of negative feedback Δ V2 of pixel B of less mobility [mu].Therefore, drain-to-source electric current I ds only drops to Ids2 from Ids2 ', and this is not remarkable landing.As a result, therefore the drain-to-source electric current I ds1 of the pixel A drain-to-source electric current I ds2 of pixel B no better than that becomes proofreaies and correct the variation of mobility [mu] from pixel to pixel.
More than the summary, if pixel A has different mobility [mu] with B, the amount of negative feedback Δ V1 of pixel A that then has big mobility [mu] is greater than the amount of negative feedback Δ V2 of the pixel B with less mobility [mu].That is, mobility [mu] is big more, and amount of negative feedback Δ V is big more, and comes to many more under the drain-to-source electric current I ds.
Therefore, by video voltage Vsig is got back in the drain-to-source electric current I ds negative feedback of driving transistors 22, can be unified so that have a drain-to-source electric current I ds of the driving transistors 22 between the pixel of different mobility [mu].This makes it possible to proofread and correct the variation of mobility [mu] from pixel to pixel.
At this, will provide the description of the relation between the drain-to-source electric current I ds of the driving transistors 22 in vision signal electromotive force (sampling electromotive force) Vsig and the pixel (image element circuit) 20 shown in Figure 2 to 9C with reference to figure 9A.To under the different situations of carrying out and not carrying out the correction of threshold value and mobility, describe with co-relation.
9A in transit is in 9C, and Fig. 9 A illustrates and neither carries out the situation that the mobility correction is not carried out in the threshold value correction yet.Fig. 9 B illustrates the situation of carrying out the threshold value correction and not carrying out the mobility correction.Fig. 9 C illustrates the situation that threshold value is proofreaied and correct and mobility is proofreaied and correct of carrying out.Shown in Fig. 9 A, do not carry out the mobility correction if neither carry out the threshold value correction yet, because the threshold voltage vt h between two pixels and the variation of mobility [mu], the drain-to-source electric current I ds between pixel A and the B will have very big difference.
On the contrary, proofread and correct iff carrying out threshold value, passing threshold is proofreaied and correct, and drain-to-source electric current I ds can be lowered to certain scope, shown in Fig. 9 B.Yet pixel A that is caused by the variation of the mobility [mu] between two pixels and the difference of the drain-to-source electric current I ds between the B still exist.
Threshold value is proofreaied and correct and mobility is proofreaied and correct both if carry out, and then pixel A that is caused by the variation of threshold voltage vt h between two pixels and mobility [mu] and the difference of the drain-to-source electric current I ds between the B almost can be eliminated fully, shown in Fig. 9.This guarantees and changes constant luminance irrelevant, organic EL 21, therefore high-quality screen epigraph is provided.
In addition, except that threshold value and mobility calibration function,, can obtain following beneficial effect by described not long ago bootstrapping function is provided for pixel shown in Figure 2 20.
That is, even the source potential Vs of driving transistors 22 changes with the I-V characteristic change in time of organic EL 21, owing to keep the bootstrapping action of electric capacity 24, the grid of driving transistors 22 is still kept constant to source voltage Vgs.As a result, the flow through electric current of organic EL 21 still changes.Therefore, the luminosity of organic EL 21 is kept constant.Even providing under the situation that the I-V of organic EL 21 characteristic changes in time, this also worsens irrelevant screen epigraph with brightness.
[capacitance of the capacitance component of organic EL reduces the problem that causes]
As mentioned above, in the organic EL display apparatus 10 with threshold value and mobility calibration function, along with owing to provide higher sharpness Pixel Dimensions to become meticulousr, the electrode size that forms organic EL 21 becomes littler.As a result, the capacitance of the capacitance component of organic EL 21 becomes littler.This capacitance that causes the decline of writing gain of video voltage Vsig to reach as the capacitance component of organic EL element 21 descends as many.
At this, suppose to represent the capacitance of EL electric capacity 25 by Cel, the capacitance by Cs represents to keep electric capacity 24 then is expressed as follows by the voltage Vgs that keeps electric capacity 24 to keep when writing video voltage Vsig:
Vgs＝Vsig×{1-Cs/(Cs+Cel)} (3)
Therefore, by the ratio of pressing between voltage Vgs that keeps electric capacity 24 to keep and the signal voltage Vsig, promptly write gain G (=Vgs/Vsig) can be expressed as follows:
G＝1-Cs/(Cs+Cel) (4)
As very clear from this formula (4), if the capacitance Cel of the capacitance component of organic EL 21 descends, then write gain G with decline reach wherein decline as many.
In order to compensate the decline of writing gain G, only need auxiliary capacitor is attached to the source electrode of driving transistors 22.Suppose that the capacitance of auxiliary capacitor represented by Csub, then write gain G and can be expressed as follows:
G＝1-Cs/(Cs+Cel+Csub) (5)
As very clear from formula (5), the capacitance Csub of auxiliary capacitor that be attached is big more, writes the approaching more unification of gain G.Voltage Vgs near the video voltage that is written to pixel 20 can be by keeping electric capacity 24 to keep.This makes it possible to provide the luminosity of the video voltage that is suitable for being written to pixel 20.
As from above-mentioned very clear, can adjust the gain G of writing of video voltage Vsig by the capacitance Csub that adjusts auxiliary capacitor.On the other hand, depend on the glow color of organic EL 21, the size difference of driving transistors 22.Therefore, by the glow color according to organic EL 21, promptly the size of driving transistors 22 is adjusted the capacitance Csub of auxiliary capacitor, can realize white balance.
On the other hand, the drain-to-source electric current of hypothesis driven transistor 22 is represented by Ids, and is represented by Δ V that by the voltage increment that mobility is proofreaied and correct the mobility correction period t that then will carry out above-mentioned mobility correction betwixt is confirmed as follows:
T＝(Cel+Csub)×ΔV/Ids (6)
As very clear,, can adjust mobility and proofread and correct period t by adjusting the capacitance Csub of auxiliary capacitor from formula (6).
[pixel arrangement] with auxiliary capacitor
Figure 10 is the circuit diagram that diagram has the pixel arrangement of auxiliary capacitor.In Figure 10, similar assembly is represented by the reference marker identical with Fig. 2.
As shown in figure 10, pixel 20 comprises that organic EL 21 is as light-emitting component.Except that organic EL 21, pixel 20 also comprises: driving transistors 22, write transistor 23 and maintenance electric capacity 24.As above Pei Zhi pixel also comprises auxiliary capacitor 26.One of electrode of auxiliary capacitor 26 is connected to the source electrode of driving transistors 22, and another electrode is connected to the public power wire 34 as fixed potential.
At this,, the negative electrode distribution forms auxiliary capacitor 26 if being arranged at TFT layer (corresponding to the TFT layer 207 among Figure 16 to 18), the problem of the horizontal crosstalk that generation such as limited layout area or the wiring resistance in the pixel 20 by pixel 20 cause.The horizontal crosstalk that caused by wiring resistance takes place owing to following reason.
If the negative electrode distribution is arranged in the TFT layer, wiring resistance R is between the cathode electrode and public power wire 34 of organic EL 21, as shown in figure 11.As a result, the variation of the electromotive force of the cathode potential of organic EL 21 and signal wire 33 is synchronously fluctuateed, as shown in figure 12.When showing black window, for example, as shown in figure 13, the fluctuation of this cathode potential visually be designated on the display screen than black window more than and following regional bright crosstalking (horizontal crosstalk).
Therefore present embodiment is defined as, and forms auxiliary capacitor 26 by clearly using auxiliary electrode 35.Each is electrically connected to auxiliary electrode 35 public power wire 34. as the cathode electrode of organic EL 21 and is in the identical layer (anode layer) of the anode electrode of organic EL 21, auxiliary electrode 35 is in fixing electromotive force (cathode potential), and for example arrange (one of each pixel column) with row, as shown in figure 14 for the pixel of the pixel array portion 30 of arranging with matrix form.Another electrode of auxiliary capacitor 26 be electrically connected to be used for pixel 20 each auxiliary electrode 35 (during set up contact).
In Figure 14, for the pixel 20 of pixel array portion 30, auxiliary electrode 35 is arranged with row.Yet this only is an example.For the pixel 20 of pixel array portion 30, auxiliary electrode 35 can be arranged with row (one of each pixel column) or with grid configuration (of each pixel column and each pixel column).And in these cases,, can arrange with row as auxiliary electrode 35 and between another electrode of auxiliary electrode 35 and auxiliary capacitor 26, set up contact for pixel 20 each.
(pixel arrangement structure)
Figure 15 is the planimetric map of the pixel arrangement structure of the pixel 20 of indicative icon with auxiliary capacitor 26.
As shown in figure 15, arrange sweep trace 31 (31-1 is to one of 31-m) along the row that approaches pixel column (on the line direction of pixel).From middle part arranged beneath power lead 32 (32-1 is to one of 32-m).Arrange auxiliary electrode 35 along the row more than the following pixel column.In addition, arrange signal wire 33 (33-1 is to one of 33-n) along the row (on the column direction of pixel) that approach the left pixel row.
Driving transistors 22, write transistor 23 and maintenance electric capacity 24 are formed in the sweep trace 31 and the zone between the power lead 32 of pixel 20.Auxiliary capacitor 26 is formed in the power lead 32 and the zone between the auxiliary electrode 35 of pixel 20.For each of pixel, between another electrode of auxiliary capacitor 26 and auxiliary electrode 35, set up contact (electrical connection) by contact portion 36.Apply fixed potential (cathode potential) from public power wire 34 for auxiliary electrode 35.
As mentioned above, apply fixed potential from public power wire 34 for auxiliary electrode 35 as the cathode electrode of organic EL 21.For the pixel of arranging, with row, with row or with grid configuration layout auxiliary electrode 35 with matrix form.For the organic EL display apparatus of configuration as mentioned above, will describe below how conduct connects between another electrode of auxiliary capacitor 26 and auxiliary electrode 35 for each of pixel 20 so that the object lesson that fixed potential is applied to another electrode of auxiliary capacitor 26 and how is formed for the auxiliary capacitor 26 of this fixed potential.
Figure 16 is the sectional view of diagram according to the cross-section structure of the pixel 20A of example 1.The sectional view of Figure 16 is the sectional view that the line A-A along Figure 15 takes.
As shown in figure 16, pixel 20 has the gate electrode of the driving transistors 22 that forms as first distribution 202 on glass substrate 201.On first distribution 202, form gate insulating film 203.For example on gate insulating film 203, form semiconductor layer 204 with polysilicon.Semiconductor layer 204 forms the source electrode and the drain region of driving transistors 22.Power lead 32 is formed via second distribution 206 of barrier isolation film 205 on semiconductor layer 204.
At this, the layer that comprises first distribution 202, gate insulating film 203, semiconductor layer 204 and barrier isolation film 205 is as TFT layer 207.In addition, at barrier isolation film 205 and second distribution, 20 input horizons) form insulation planar film 208 and window dielectric film 209 on 2126 continuously.Organic EL 21 is formed among the sunk part 209A that provides in the window dielectric film 209.
The anode electrode 211 that organic EL 21 is included in is that the bottom of the sunk part 209A of window dielectric film 209 forms, made by metal or other materials.Organic EL 211 also is included in the organic layer (electron transfer layer, luminescent layer and hole transport/input horizon) 212 that forms on the anode electrode 211.Organic EL 21 also is included in for the cathode electrode 213 (public power wire 34) that forms on the public organic layer 212 of all pixels, made by for example transparent conductive film.At this, the layer that comprises second distribution 206 and insulation planar film 208 is as anode layer 210.
In organic EL 21, form organic layer 212 by successive sedimentation electron transfer layer, luminescent layer and hole transport/input horizon on anode electrode 211 (these layers are not shown).Because by driving transistors shown in Figure 2 22 current drives organic ELs 21, so electric current flows to organic layer 212 from driving transistors 22 via anode electrode 211.This causes the combination again in the luminescent layer of organic layer 212 of electronics and hole, therefore causes luminous.
Essential structure has comprised the pixel 20 of organic EL 21, driving transistors 22, write transistor 23 and maintenance electric capacity 24 as mentioned above.
In this base pixel structure, has following structure according to the auxiliary capacitor 26 of the pixel 20A of example 1.That is, use the semiconductor layer of being made by polysilicon 204 to form one of electrode 261, wherein semiconductor layer 204 forms the source electrode and the drain region of driving transistors 22.With identical metal material and by with form another electrode 262 for the identical process of second distribution 206 so that another electrode 262 is relative with one of electrode 261 via barrier isolation film 205.Between the opposed area of the parallel-plate of electrode 261 and 262, form auxiliary capacitor 26.
Between another electrode 262 of auxiliary capacitor 26 and auxiliary electrode 35, set up contact by contact portion 36.This has guaranteed each pixel at another electrode 262 of auxiliary capacitor 26 with for for example electrical connection to go between the auxiliary electrode of arranging 35 of the pixel of arranging with matrix form.As a result, apply fixed potential from public power wire 34 via auxiliary electrode 35.
As mentioned above, form auxiliary capacitor 26 with electrode 261 and 262.One of electrode 261 is made by the polysilicon of the semiconductor layer 204 that is used for driving transistors 22.Another electrode 262 is made by the metal material identical with being used for second distribution 206.For each pixel, another electrode 262 is electrically connected to the auxiliary electrode of for example arranging with row for the pixel of arranging with matrix form 35.Another electrode 262 that this makes it possible to fixed potential is applied to auxiliary capacitor 26 provides any negative electrode distribution and not be used in the TFT layer 207, therefore allow to be formed for the auxiliary capacitor 26 of fixed potential.As a result, can solve the problem of the horizontal crosstalk that causes such as limited layout area or the wiring resistance in the pixel 20 by pixel 20.
Under the situation of example 1, by following, promptly the concrete permittivity (inductive capacity) of area, the gap between the electrode 261 and 262 (film thickness of barrier isolation film 205) and the insulator between electrode 261 and 262 of the opposed area of electrode 261 and 262 parallel-plate is determined the capacitance of auxiliary capacitor 26.
Figure 17 is the sectional view of diagram according to the cross-section structure of the pixel 20B of example 2.In Figure 17, represent similar assembly by the reference marker identical with Figure 16.The sectional view of Figure 17 is the sectional view that the line A-A along Figure 15 takes.
Has base pixel structure described in example 1 according to the pixel 20B of example 2.The auxiliary capacitor 26 of pixel 20B has following structure.That is, the polysilicon of semiconductor layer 204 of at first using the metal material identical with first distribution 202 and forms another electrode 262. usefulness formation driving transistors 22 by identical process on glass substrate 201 is via one of gate insulating film 203 formation electrodes 261.Form one of electrode 261 at comparative electrode 262 places.Between the opposed area of the parallel-plate of electrode 261 and 261, form auxiliary capacitor 26.
Between another electrode 262 of auxiliary capacitor 26 and second distribution 206, set up contact by contact portion 37.Also between another electrode 262 of auxiliary capacitor 26 and auxiliary electrode 35, set up contact by contact portion 36.This guarantees for each pixel at another electrode 262 of auxiliary capacitor 26 with for for example electrical connection to go between the auxiliary electrode of arranging 35 of the pixel of arranging with matrix form.As a result, apply fixed potential from public power wire 34 via auxiliary electrode 35.
As mentioned above, form auxiliary capacitor 26 with electrode 261 and 262.Make another electrode 262 by the metal material identical with being used for first distribution 202.By making one of electrode 261 with the polysilicon of the semiconductor layer 204 that is used for driving transistors 22.For each pixel, another electrode 262 is electrically connected to the auxiliary electrode of for example arranging with row for the pixel of arranging with matrix form 35.Another electrode 262 that this makes it possible to fixed potential is applied to auxiliary capacitor 26 provides any negative electrode distribution and not be used in the TFT layer 207, therefore allow to be formed for the auxiliary capacitor 26 of fixed potential.As a result, can solve the problem of the horizontal crosstalk that causes such as limited layout area or the wiring resistance in the pixel 20 by pixel 20.
Under the situation of example 2, by following, promptly the concrete permittivity of area, the gap between the electrode 261 and 262 (film thickness of gate insulating film 203) and the insulator between electrode 261 and 262 of the opposed area of electrode 261 and 262 parallel-plate is determined the capacitance of auxiliary capacitor 26.
At this, comparative example 1 and example 2.The area of opposed area of supposing concrete permittivity and parallel-plate is identical, can obtain as follows.That is, gate insulating film 203 is typically thin than barrier isolation film 205.That therefore, the gap between the parallel-plate can be made than in the example 1 in example 2 is little.What as a result, the capacitance of auxiliary capacitor 26 can be provided with than in the example 1 in example 2 is big.
On the contrary, compare with example 2, the advantage of example 1 is, because barrier isolation film 205 is thinner than gate insulating film 203, and the therefore more unlikely generation of leakage that causes by the interlayer short circuit.
Figure 18 is the sectional view of diagram according to the cross-section structure of the pixel 20C of example 3.In Figure 18, because identical reference marker is represented similar assembly among Figure 16 and 17.The sectional view of Figure 18 is the sectional view that the line A-A along Figure 15 takes.
Has base pixel structure described in example 1 according to the pixel 20C of example 3.The auxiliary capacitor 26 of pixel 20C has following structure.That is, at first use the metal material identical and on glass substrate 201, form another first electrode 262A by identical process with first distribution 202.Polysilicon with the semiconductor layer 204 that forms driving transistors 22 forms one of electrode 261 via gate insulating film 203.Form one of electrode 261 at comparative electrode 262 places.In addition, use the metal material identical and form another second electrode 262B so that it is relative with electrode 261 via barrier isolation film 205 by identical process with being used for second distribution 206.Electrode 262A, 261 and the opposed area of the parallel-plate of 262B between parallel electronic ground form auxiliary capacitor 26.
Between auxiliary capacitor 26 another first electrode 262A and another second electrode 262B, set up contact by contact portion 37.Also between another the first electrode 262A of auxiliary capacitor 26 and auxiliary electrode 35, set up contact by contact portion 36.This has guaranteed for each pixel being electrically connected between another first and second electrodes 262A of auxiliary capacitor 26 and 262B and the auxiliary electrode of for example arranging with row for the pixel of arranging with matrix form 35.As a result, apply fixed potential from public power wire 34 via auxiliary electrode 35.In addition, the electric capacity in electric capacity that forms between electrode 262A and 262 and formation between electrode 262B and 261 is electrically connected concurrently so that auxiliary capacitor 26 is formed the combination capacitor of these two electric capacity.
As mentioned above, form auxiliary capacitor 26 with another electrode 262A and one of 262B and electrode 262.Respectively by be used for first and second distributions 202 and 206 identical metal materials are made another electrode 262A and 262B.Polysilicon by the semiconductor layer 204 that is used for driving transistors 22 is made one of electrode 261.For each pixel, another electrode 262A and 262B are electrically connected to the auxiliary electrode of for example arranging with row for the pixel of arranging with matrix form 35.Another electrode 262A and 262B that this makes it possible to fixed potential is applied to auxiliary capacitor 26 provide any negative electrode distribution and not be used in the TFT layer 207, therefore allow to be formed for the auxiliary capacitor 26 of fixed potential.As a result, can solve the problem of the horizontal crosstalk that causes such as limited layout area or the wiring resistance in the pixel 20 by pixel 20.
Particularly, between one of another first electrode 262A and electrode 261, form electric capacity, and between one of electrode 261 and another second electrode 262B, form another electric capacity.Therefore, suppose that example 1 is identical with capacitance in 2, can form then that to have approximately be the auxiliary capacitor 26 of the big capacitance of twice in example 1 and 2.In other words, if only need to have almost with example 1 and 2 in identical capacitance, then can reduce the size of the electrode 261,262A and the 262B that form auxiliary capacitor 26.As a result, compare with 2, can in pixel 20, form auxiliary capacitor 26, and need not increase the size of pixel 20C with example 1.
Under the situation of example 3, determine the capacitance of auxiliary capacitor 26 by the combination capacitor value of two electric capacity.The distance between area, electrode 261 and the 262A of the opposed area of the parallel-plate by one of electrode 261 and another first electrode 262A and the concrete permittivity of the insulator between electrode 261 and 262A (being gate insulating film 203 in this example) are determined one of electric capacity.The distance between area, electrode 261 and the 262B of the opposed area of the parallel-plate by one of electrode 261 and another second electrode 262B and the concrete permittivity of the insulator between electrode 261 and 262B (being barrier isolation film 205 in this example) are determined another electric capacity.
(beneficial effect of present embodiment)
As mentioned above, each of the pixel 20 of organic EL display apparatus has auxiliary capacitor 26 and enough writes gain with what guarantee vision signal.In this organic EL display apparatus, each of unit pixel 20, another electrode of auxiliary capacitor 26 or two electrodes 262 (262A and 262B) be connected to for the pixel of arranging with matrix form for example with row, with row or with grid configuration arrange and be applied in fixed potential auxiliary electrode 35.This makes it possible to fixed potential is applied to other electrodes 262, provides any negative electrode distribution in the TFT layer 207 and not be used in, and therefore allows to be formed for the auxiliary capacitor 26 of fixed potential, suppresses wiring resistance simultaneously.As a result, can suppress the horizontal crosstalk that causes by wiring resistance, therefore the picture quality on the improved screen is provided.
In above embodiment, adopt to apply the present invention to use organic EL to provide description as an example as the situation of the organic EL display apparatus of the electrooptic cell of image element circuit.Yet embodiments of the invention are not limited thereto example application, but can be applicable to generally to use the display device of the current drives electrooptic cell (light-emitting component) that luminosity changes along with the change of the electric current of this element of flowing through.
Above-mentioned display device according to an embodiment of the invention is applicable as and comprises those electronic installations shown in Figure 19 to 23, i.e. the display device across the electronic installation of all spectra of the mobile terminal device of digital camera, laptop PC such as mobile phone and video camera.These parts of device are designed to show and are supplied to electronic installation or at the inner image that generates of electronic installation or the video of vision signal.
As mentioned above, if be used as display device across the electronic installation of all spectra, as very clear from previous embodiment, according to an embodiment of the invention display device can prevent because for pixel 20 each another electrode of auxiliary capacitor 26 and for the pixel of arranging with matrix form for example with row, set up contact between with row or the auxiliary electrode 35 arranged with grid configuration and the horizontal crosstalk that causes by wiring resistance.As a result, display device provides picture quality on the fabulous screen in the various electronic installations according to an embodiment of the invention.
Should be noted that display device according to an embodiment of the invention comprises the display device with the kit form (modular form) with seal arrangement.This display device will be corresponding to by being attached to the display module that pixel array portion 30 forms by the relative part that for example clear glass is made.Except such as color filter and the diaphragm, can also on transparent relative part, provide above-mentioned photomask.Shall also be noted that can provide on the display module be applicable to allow externally to install and pixel array portion between the circuit part of switching signal or other message, FPC (flexible print circuit) or other circuit.
The object lesson of the electronic installation of using embodiments of the invention will be described below.
Figure 19 is the skeleton view that diagram is used the televisor of embodiments of the invention.According to comprising the video display screen part of forming by for example front panel 102, filtrator glass 103 and other parts 101 with the televisor of example.Make televisors by using according to an embodiment of the invention display device as video display screen part 101.
Figure 20 A and 20B are the skeleton views that diagram is used the digital camera of embodiments of the invention.Figure 20 A is the skeleton view of digital camera of looking from the front side, and Figure 20 B is from rear side its skeleton view of looking.According to comprising flash of light part 111, display part 112, menu switch 113, shutter release button 114 and other parts with the digital camera of example.Make digital cameras by using according to an embodiment of the invention display device as display part 112.
Figure 21 is the skeleton view that diagram is used the laptop PC of embodiments of the invention.According to comprising with the laptop PC of example: the keyboard 122 in the main part 121 is applicable to and is handled to key in text or other information; Display part 123 is applicable to display image; And other parts.Make laptop PCs by using according to an embodiment of the invention display device as display part 123.
Figure 22 is the skeleton view that diagram is used the video camera of embodiments of the invention.According to should comprise main part 131 with the video camera of example, be provided at being used for camera lens 132, imaging to target imaging and beginning of front face side/shutdown switch 133, display part 134 and other parts.Make video cameras by using according to an embodiment of the invention display device as display part 134.
Figure 23 A is the skeleton view such as the mobile terminal device of mobile phone that diagram is used embodiments of the invention to 23G.Figure 23 A is the front view of the mobile phone when being shown in an open position.Figure 23 B is its side view.Figure 23 C is in the front view that closes the mobile phone when closing the position.Figure 23 D is its left hand view.Figure 23 E is its right part of flg.Figure 23 F is a top view.Figure 23 G is a backplan.According to comprising upper-part 141, lower member 142, coupling part (being hinge fraction in this example) 143, display 144, sub-display 145, picture light 146, camera 147 and other parts with the mobile phone of example.Make mobile phones by using according to an embodiment of the invention display device as display 144 and sub-display 145.
It will be appreciated by those skilled in the art that as long as in the scope of claims or its equivalent, depend on designing requirement and other factors, various modifications, combination, sub-portfolio and change can take place.
The present invention comprises the relevant theme of submitting in Jap.P. office with on August 15th, 2007 of Japanese patent application JP2007-211623, by reference its full content is herein incorporated.
Pixel array portion,
Described pixel array portion has the pixel of arranging with matrix form, and each described pixel comprises:
Electrooptic cell,
Write transistor is applicable to write vision signal,
Keep electric capacity, be applicable to the described vision signal that maintenance is write by described write transistor, and
Driving transistors is applicable to based on the vision signal that is kept by described maintenance electric capacity to drive described electrooptic cell;
Power lead, for each of each pixel column of pixel array portion is arranged one, and belonging near the capable sweep trace of neighborhood pixels, described power lead is applicable to selectively the drain electrode that first electromotive force and second electromotive force that is lower than first electromotive force is applied to described driving transistors; And
Auxiliary electrode arranges that with row, column or grid configuration described auxiliary electrode has been applied in fixed potential, wherein for the described pixel array section of arranging with matrix form
Each has auxiliary capacitor described pixel, and
An electrode of described auxiliary capacitor is connected to the source electrode of described driving transistors, and another electrode is connected to the described auxiliary electrode that is used for each pixel,
An electrode of wherein said auxiliary capacitor adopts the source electrode of the described driving transistors of formation and the semiconductor layer of drain region to form, and
Another electrode of described auxiliary capacitor adopts metal material to form, so that relative with described semiconductor layer.
2. display device as claimed in claim 1, wherein
Described another electrode is formed at the wiring layer identical with being used for described power lead, and
Described another electrode is relative with a described electrode via the barrier isolation film between described wiring layer and described semiconductor layer.
3. display device as claimed in claim 1, wherein
Described another electrode is formed at the wiring layer identical with the gate electrode that is used for described driving transistors, and
Described another electrode is relative with a described electrode via the gate insulating film between described wiring layer and gate electrode.
4. display device as claimed in claim 1, wherein
Described another electrode comprises first and second electrodes that are electrically connected to each other,
Described first electrode is formed at the wiring layer identical with the gate electrode that is used for described driving transistors, so that described first electrode is relative with a described electrode via the gate insulating film between described wiring layer and gate electrode, and
Described second electrode is formed at the wiring layer identical with being used for described power lead, so that described second electrode is relative with a described electrode via the barrier isolation film between described wiring layer and semiconductor layer.
5. electronic installation with display device, described display device comprises:
Wherein, an electrode of described auxiliary capacitor adopts the source electrode of the described driving transistors of formation and the semiconductor layer of drain region to form, and
CN2008102109785A 2007-08-15 2008-08-15 Display device and electronic equipment CN101404140B (en)
JP211623/07 2007-08-15
CN101404140A CN101404140A (en) 2009-04-08
CN101404140B true CN101404140B (en) 2010-12-15
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