CN1957388A - Image display device and driving method thereof - Google Patents
Image display device and driving method thereof Download PDFInfo
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- CN1957388A CN1957388A CN 200580016077 CN200580016077A CN1957388A CN 1957388 A CN1957388 A CN 1957388A CN 200580016077 CN200580016077 CN 200580016077 CN 200580016077 A CN200580016077 A CN 200580016077A CN 1957388 A CN1957388 A CN 1957388A
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- light
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Abstract
An image display device is provided with a light emitting element; a driving transistor wherein a gate electrode, a source electrode and a drain electrode are provided and one edge of the light emitting element is electrically connected with one of the electrodes of the source electrode and the drain electrode; a first switching transistor, which short-circuits the gate electrode of the driving transistor and the one electrode of the driving transistor in response to a scanning signal; a capacitor element wherein a first electrode and a second electrode are provided and the gate electrode of the driving transistor is connected with the first electrode; a signal line connected with the second electrode of the capacitor element; a signal line driving circuit, which supplies the signal line with a brightness potential and a reference potential indicating a standard of the brightness potential; and a power source supplying circuit, which controls a potential of the other electrode of the source electrode and the drain electrode of the driving transistor.
Description
Technical field
[0001]
The present invention relates to image display apparatus, particularly can improve the image display apparatus of contrast.
Background technology
[0002]
In the prior art, use has hole and the electron luminescence scheme of the image display apparatus of organic EL (Electonic Luminescent) element of the function of combination generation light, the appearance already again that utilizes the injection luminescent layer.
[0003]
This image display apparatus for example possesses: a plurality of pixel circuits of ranks shape configuration; Do media by a plurality of signal wires, supply with the signal-line driving circuit of the luminance signal of hereinafter telling about to a plurality of pixel circuits; Supply is intended to select to do media by a plurality of sweep traces, supplies with the scan line drive circuit of sweep signal of the pixel circuit of luminance signal to pixel circuit.
[0004]
In addition, above-mentioned pixel circuit (a pixel unit) possesses: have injection current and above-mentioned organic EL---the light-emitting component of luminous function; Be intended to control the driver element of the electric current that flows into light-emitting component; 2 or 3 on-off elements.These driver elements and on-off element are thin film transistor (TFT) (TFT).Like this, the image display apparatus of prior art just becomes 3TFT structure or 4TFT structure that each pixel circuit has 3 (1 driver element+2 on-off element) or 4 (1 driver element+3 on-off element) thin film transistor (TFT)s.
[0005]
Figure 15-the 1st, the figure of the structure at the main position (a pixel unit) of the image display apparatus that proposes in the expression non-patent literature 1.In the image display apparatus shown in this figure, signal wire supply circuit 102 possesses by signal wire 101, supplies with the function of luminance signal.Scan line drive circuit 104 possesses and supplies with the function of sweep signal be intended to select supply with by sweep trace 103 pixel circuit of brightness current potentials.Current potential power-supply circuit 105 possesses function from the high level current potential to the electrode of electrode of electrostatic condenser 112 and on-off element 108 that supply with.Reset control circuit 114 is done media by reset line 115, supplies with reset potential to on-off element 109.Drive and Control Circuit 116 is done media by drive controlling line 117, supplies with control signal to on-off element 118.
[0006]
In addition, in image display apparatus, light-emitting component 107, on-off element 108, on-off element 109, electrostatic condenser 112, on-off element 118, electrostatic condenser 119 and on-off element 122, the pixel circuit of a pixel of formation.Light-emitting component 107 has that electric current injects and luminous function is formed by above-mentioned organic EL.On-off element 108 has the function that is intended to control the electric current that flows into light-emitting component 107.
[0007]
Here, light-emitting component 107 has the threshold voltage of generation V shown in Figure 16-1
Th, i-vAfter the above potential difference (PD) (potential difference (PD) between the anode-cathode), the I-E characteristic that just has electric current to flow through.In addition, light-emitting component 107 also shown in Figure 16-2, has the threshold voltage of generation V
Th, L-vAfter the above potential difference (PD) (potential difference (PD) between the anode-cathode), with regard to the brightness-voltage characteristic of luminous (brightness＞0).
[0008]
In addition, threshold voltage V
Th, i-vValue, be lower than threshold voltage V
Th, L-vLike this, the potential difference (PD) between the anode-cathode of light-emitting component 107 is threshold voltage V
Th, L-vWhen above, become at electric current and flow into light-emitting component 107 simultaneously, the state that light-emitting component 107 is luminous.In addition, the potential difference (PD) between the anode-cathode of light-emitting component 107 is threshold voltage V
Th, i-vMore than, less than threshold voltage V
Th, L-vThe time, flow into light-emitting component 107, the non-luminous state of light-emitting component 107 though then become electric current.
[0009]
Specifically, driver element 108 has according to the potential difference (PD) more than the drive threshold that adds to outward between the 1st terminal and the 2nd terminal, and control flows into the function of the electric current of light-emitting component 107, with added this potential difference (PD) during, make electric current continue flow into the function of light-emitting component 107.Driver element 108 is formed by p type thin film transistor (TFT), according to adding to the gate electrode that is equivalent to the 1st terminal outward and being equivalent to potential difference (PD) between the source electrode of the 2nd terminal, the luminosity of control light-emitting component 107.
[0010]
In said structure, carry out following 4 steps repeatedly: reset process, threshold voltage detect step, data write step and luminous step.Below, tell about initial reset process.
[0011]
As initial step, carry out the reset process that the outer current potential that adds to the gate electrode of driver element 108 when in the past luminous is resetted.In this reset process, shown in Figure 15-2, signal wire 101 becomes the high level current potential, and reset line 115 becomes the low level current potential, and drive controlling line 117 becomes the low level current potential, and sweep trace 103 becomes the low level current potential.
[0012]
Here, the potential difference (PD) between the anode-cathode of light-emitting component 107 when on-off element 118 is conducting state, is the poor of Va and 0 current potential (cathode potential of light-emitting component 107).
[0013]
Figure 17 is the figure of the transition response characteristics in the expression reset process.In other words, in the figure, express the current potential Va shown in Figure 15-1, current potential Vb, flow through the current i of light-emitting component 107
D, OLEDThe transition response characteristics.
[0014]
As known in the figure: after Time=0.00 carries out reset process, the current potential of the source electrode of driver element 108 is high level current potentials, so when current potential Vb sharply descends, current potential Va rises, potential difference (PD) between the anode-cathode of light-emitting component 107 sharply uprises, and becomes the threshold voltage V shown in Figure 16-2
Th, L-vMore than.Like this, in current i
D, OLEDWhen flowing into light-emitting component 107, also luminous.In addition, luminous in reset process as described later, is unwanted originally.
[0015]
Then, after the end reset process, after the above-mentioned threshold voltage of process detected step, data write step, in luminous step, light-emitting component 107 was luminous.
[0016]
We know: in image display apparatus, the quantity of the thin film transistor (TFT) of each pixel circuit is many more, and fineness is low more.So, compare the fineness height of 2TFT structure with 3TFT structure or 4TFT structure.
[0017]
Figure 18-the 1st, the figure of the structure at the main position (pixel) of the image display apparatus of the 2TFT structure that proposes in the expression non-patent literature 2.In addition, Figure 18-the 2nd, the sequential chart of its action is told about in expression.Image display apparatus shown in Figure 18-1, on-off element T1, driver element T2, electrostatic condenser CCs and light-emitting component OLED connect as shown in figure, become 2TFT structure (on-off element T1 and driver element T2).On-off element T1 and driver element T2 are thin film transistor (TFT)s.
[0018]
In said structure, as t during Figure 18-2
1And shown in Figure 19-1, in preparation process, the current potential of sweep trace Select is V
GL, data line Data current potential be that 0 current potential, common line COM are V
GGAfter, on-off element T1 becomes cut-off state, and driver element T2 becomes conducting state, and the current potential a of the source electrode of driver element T2 becomes V
GG+ V
OLED(voltage drop of light-emitting component OLED)+V
Data' (data voltage)+V
t(threshold voltage of driver element T2), the current potential b of the anode of light-emitting component OLED becomes V
GG+ V
OLEDLike this, current i flows, and current potential a is by V
GG+ V
OLED+ V
Data'+V
tBecome V
Data'+V
t, current potential b is by V
GG+ V
OLEDBecome 0 current potential.
[0019]
Then, as t during Figure 18-2
2And shown in Figure 19-2, detect in the step at threshold voltage, the current potential of sweep trace Select is V
GH, data line Data current potential be that on-off element T1 became conducting state after 0 current potential, common line COM were 0 current potential, driver element T2 becomes conducting state, the current potential a of the source electrode of driver element T2 becomes 0 current potential, current potential b is become-α (V by 0 current potential
Data'+V
t)-(1-α) V
GGThen, current i flows, and current potential b is by-α (V
Data'+V
t)-(1-α) V
GGBecome-V
tHere, α is CC
S/ (CC
S+ C
OLED).CC
SBe electrostatic condenser CC
SValue.C
OLEDIt is the value of light-emitting component OLED electrostatic capacitance.
[0020]
Follow again, as t during Figure 18-2
3And shown in Figure 19-3, in the data write step, the current potential of sweep trace Select is V
GH, data line Data current potential be data current potential V
Data, after common line COM is 0 current potential, on-off element T1 becomes conducting state, driver element T2 becomes conducting state, the current potential a of the source electrode of driver element T2 becomes V by 0
Data, current potential b is by-V
tBecome α V
Data-V
tThen, current i flows.Here, current potential b is at V
DataLess than V
tThe time, by-V
tBecome V
Data-V
tOn the other hand, at V
DataGreater than V
tThe time, current potential b becomes 0 current potential.
[0021]
Follow again, as t during Figure 18-2
4And shown in Figure 19-4, in luminous step, the current potential of sweep trace Select is V
GL, data line Data current potential be that 0 current potential, common line COM are-V
EEAfter, on-off element T1 becomes cut-off state, and driver element T2 becomes conducting state, and the current potential a of the source electrode of driver element T2 becomes V
t+ V
OLED+ V
EEOr V
Data+ V
OLED+ V
EE
[0022]
Here, current potential a becomes V
t+ V
OLED+ V
EEThe time, current potential b and the V shown in Figure 19-3
Data-V
t(V
Data＜V
t) correspondence.At this moment, in light-emitting component OLED, current i
d(=0) does not flow through (i
d=0).On the other hand, current potential a becomes V
Data+ V
OLED+ V
EEThe time, current potential b shown in Figure 19-3 and 0 (V
Data＞V
t) correspondence.At this moment, current i
d(=(β/2) (V
Data-V
t)
2) inflow light-emitting component OLED.In other words.Light-emitting component OLED is because at V
DataAnd V
tThe effect of magnitude relationship under, flow through or do not flow through current i
dSo, luminous or not luminous.In other words, the luminance of light-emitting component OLED exists with ... the threshold voltage V of driver element T2
t
[0023]
Non-patent literature 1:Dawson etc., " using the new pixel circuit design (Design Of an Improved Pixel forPolysilicon Active-Matrix Organic LED Display) of the active array type organic LED display of polysilicon " information display association 1998 digests (Society ofInformation Display1998 Digest), 1998, p.11-14
Non-patent literature 2:J.L.Sanford et al., Proc.of IDRC 03p.38
[0024]
; in the sort of image display apparatus that non-patent literature 1 proposes; because the current potential of the source electrode of the driver element 108 shown in Figure 53-1 is current potentials of high level, so in reset process, the potential difference (PD) between the anode-cathode of light-emitting component 107 just becomes the threshold voltage V shown in Figure 16-2
Th, L-vMore than, so in reset process, cause light-emitting component 107 luminous,, become white pixel although original hope is black pixel, exist the problem that contrast descends.
[0025]
In addition, above-mentioned image display apparatus is because in reset process, driver element becomes conducting state, so it is big to flow into the electric current quantitative change of light-emitting component in reset process.Therefore it is big to exist in reset process the luminous quantitative change of light-emitting component, the problem that contrast further descends.
[0026]
As the image display apparatus of prior art, in order to improve fineness, though the image display apparatus of the 2TFT structure told about with reference to Figure 18-2 and Figure 19-1～Figure 19-4 has been proposed, as telling about, because at V with reference to Figure 19-3 and Figure 19-4
DataAnd V
tThe effect of magnitude relationship under, current i
dSometimes flow into light-emitting component OLED, do not flow into light-emitting component OLED sometimes, so the luminance instability of light-emitting component OLED.In other words, the image display apparatus of this 2TFT structure can't be made for practicality.
[0027]
Like this, the image display apparatus of prior art remains 3TFT structure or 4TFT structure in the practical stage, exists the problem that is difficult to improve fineness.
Summary of the invention
[0028]
The present invention is at the problems referred to above development, and its purpose is to provide the image display apparatus that can improve contrast.
[0029]
In order to solve above-mentioned problem, to achieve the goal, the image display apparatus that the present invention relates to possesses: light-emitting component; Driving transistors, this driving transistors has gate electrode, source electrode and drain electrode, and an end of described light-emitting component is electrically connected with a electrode in described source electrode and the described drain electrode; The 1st switching transistor, the 1st switching transistor make the described gate electrode of described driving transistors and an above-mentioned electric pole short circuit of described driving transistors according to sweep signal; Capacitor element, capacitor element have the 1st electrode and the 2nd electrode, and the described gate electrode of described driving transistors is connected with described the 1st electrode; Signal wire, this signal wire is connected with described the 2nd electrode of described capacitor element; Signal-line driving circuit, this signal-line driving circuit are supplied with the reference potential of brightness current potential and this brightness current potential benchmark of expression to described signal wire; Power-supply circuit, this power-supply circuit are controlled other the current potential of electrode of the described source electrode of described driving transistors and described drain electrode.
[0030]
In addition, the image display apparatus that the present invention relates to possesses a plurality of pixels, and these pixels have light-emitting component, the driving transistors that is electrically connected with an end of described light-emitting component, the capacitor element that is connected with described driving transistors, for the area S of a pixel
1, the area S of driving transistors
2Shared ratio (S in each pixel
2/ S
1), and/or for the area S of a pixel
1, the area S of capacitor element
3Shared ratio (S in each pixel
3/ S
1), be more than 0.05.
[0031]
In addition, the driving method of the image display apparatus that the present invention relates to, be to possess light-emitting component, (this driving transistors has gate electrode to driving transistors, source electrode and drain electrode, described light-emitting component is electrically connected with a electrode in described source electrode and the described drain electrode), (this switching transistor is according to sweep signal for switching transistor, make the described gate electrode of described driving transistors and a described electric pole short circuit of described driving transistors) the driving method of image display apparatus in, comprise the 1st step, this step is at the current potential of the described gate electrode that passes through the described switching transistor of control, set described switching transistor for conducting, and by the described source electrode of the described driving transistors of control and the current potential of another electrode in the described drain electrode, described driving transistors is set under the state that ends, supplied with current potential to the described gate electrode of the driving transistors of described each pixel; The 2nd step, this step is at the current potential of the described gate electrode that passes through the described switching transistor of control, set described switching transistor for conducting, and the current potential of described another electrode by the described driving transistors of control, set described driving transistors for conducting, thereby make current potential electric current be higher than drive threshold for the described gate electrode of described another electrode of described driving transistors, do media by described switching transistor then, by the gate electrode of described driving transistors described another electrode supplying electric current to described driving transistors, thereby will be for the current potential of the described gate electrode of described another electrode of described driving transistors, as drive threshold.
[0032]
In addition, the driving method of the image display apparatus that the present invention relates to, it is characterized in that: be that (these pixels possess light-emitting component possessing a plurality of pixels, (this driving transistors has gate electrode to driving transistors, source electrode and drain electrode, described light-emitting component is electrically connected with a electrode in described source electrode and the described drain electrode), (this switching transistor is according to sweep signal for switching transistor, make the described gate electrode of described driving transistors and a described electric pole short circuit of described driving transistors)) the driving method of image display apparatus in, doing media by described light-emitting component and described switching transistor, supply with in the reset process of current potential to the described gate electrode of the described driving transistors of each pixel, adding to the potential difference (PD) at the two ends of described light-emitting component outward, is that electric current begins to flow into more than the 1st threshold voltage of this light-emitting component in the described light-emitting component, described light-emitting component begins below the 2nd threshold voltage of this luminous light-emitting component.
[0033]
After adopting the present invention, in reset process, electric current flows into light-emitting component, and supply makes the current potential of the non-luminous regulation of light-emitting component, even so do media, the current potential of the gate electrode of driving transistors is resetted, also can reduce the unnecessary luminous time of light-emitting component by light-emitting component, compared with prior art, can obtain further to improve the effect of contrast.
[0034]
In addition, behind employing the present invention,, also can obtain to detect the drive threshold of compensation for drive transistor, can improve the effect of fineness even the number of transistors of each pixel is reduced to 2 or 3.
[0035]
In addition, behind employing the present invention, can enlarge shared area or capacity cell the shared area in each pixel of driving transistors in each pixel more than 5%.Like this, the resistance of driving transistors can be reduced, the power consumption of image display apparatus can be reduced.In addition, even the area of a pixel is little of 7000 μ m
2-50000 μ m
2, also guaranteeing easily becomes suitable size with the electric capacity of capacity cell.
Description of drawings
[0036]
Fig. 1 is the integrally-built figure of the image display apparatus that relates to of expression the 1st embodiment of the present invention.
Fig. 2 is for the action of telling about the image display apparatus that the 1st embodiment relates to and represent the sequential chart of sample attitude of the potential change of each inscape.
Fig. 3-the 1st, the figure of the reset process of the image display apparatus that expression the 1st embodiment relates to.
Fig. 3-the 2nd, the threshold voltage of the image display apparatus that expression the 1st embodiment relates to detects the figure of step.
Fig. 3-the 3rd, the figure of the data write step of the image display apparatus that expression the 1st embodiment relates to.
Fig. 3-the 4th, the figure of the luminous step of the image display apparatus that expression the 1st embodiment relates to.
Fig. 4 is the figure that the 1st on-off element 13 shown in the presentation graphs 3-1 becomes conducting state transition response characteristics afterwards.
Fig. 5 is the amplification plan view of the image display apparatus of Fig. 1.
Fig. 6 is the integrally-built figure of the image display apparatus that relates to of expression the 2nd embodiment of the present invention.
Fig. 7 is for the action of telling about the image display apparatus that the 2nd embodiment relates to and represent the sequential chart of sample attitude of the potential change of each inscape.
Fig. 8-the 1st, the figure of the reset process of the image display apparatus that expression the 2nd embodiment relates to.
Fig. 8-the 2nd, the figure of the preparation process of the image display apparatus that expression the 2nd embodiment relates to.
Fig. 8-the 3rd, the threshold voltage of the image display apparatus that expression the 2nd embodiment relates to detects the figure of step.
Fig. 8-the 4th, the figure of the data write step of the image display apparatus that expression the 2nd embodiment relates to.
Fig. 8-the 5th, the figure of the 2nd reset process of the image display apparatus that expression the 2nd embodiment relates to.
Fig. 8-the 6th, the figure of the luminous step of the image display apparatus that expression the 2nd embodiment relates to.
Fig. 9 is the amplification plan view of the image display apparatus of Fig. 6.
Figure 10 is the integrally-built figure of the image display apparatus that relates to of expression the 3rd embodiment of the present invention.
Figure 12-the 1st, the threshold voltage of the image display apparatus that expression the 3rd embodiment relates to detects the figure of step.
Figure 12-the 2nd, the figure of the data write step of the image display apparatus that expression the 3rd embodiment relates to.
Figure 12-the 3rd, the figure of the reset process of the image display apparatus that expression the 3rd embodiment relates to.
Figure 12-the 4th, the figure of the luminous step of the image display apparatus that expression the 3rd embodiment relates to.
Figure 13-the 1st, the figure of the structure of the critical piece of the image display apparatus that expression the 4th embodiment relates to.
Figure 13-the 2nd is for the action of telling about the image display apparatus that the 4th embodiment relates to and the sequential chart of drawing.
Figure 14-the 1st, the figure of the structure of the critical piece of the image display apparatus that expression the 5th embodiment relates to.
Figure 14-the 2nd is for the action of telling about the image display apparatus that the 5th embodiment relates to and the sequential chart of drawing.
Figure 15-the 1st, the figure of the structure at the main position (pixel) of the image display apparatus of expression prior art.
Figure 15-the 2nd is for the action of the image display apparatus of telling about prior art and the sequential chart of drawing.
Figure 16-the 1st, the figure of the I-E characteristic in the expression light-emitting component (organic EL).
Figure 16-the 2nd, the figure of the brightness-voltage characteristic in the expression light-emitting component (organic EL).
Figure 17 is the figure that on-off element 109 shown in the presentation graphs 15-1 and driver element 108 become the transition response characteristics after the conducting state.
Figure 18-the 1st, the figure of the structure at the main position (pixel) of the image display apparatus of the 2TFT structure of expression prior art.
Figure 18-the 2nd is for the action of the image display apparatus of the 2TFT structure of telling about prior art and the sequential chart of drawing.
Figure 19-the 1st, the figure of the preparation process of the image display apparatus shown in the presentation graphs 18-1.
Figure 19-the 2nd, the threshold voltage of the image display apparatus shown in the presentation graphs 18-1 detects the figure of step.
Figure 19-the 3rd, the figure of the data write step of the image display apparatus shown in the presentation graphs 18-1.
Figure 19-the 4th, the figure of the luminous step of the image display apparatus shown in the presentation graphs 18-1.
Symbol description
[0037]
1,20,50 pixel circuits
6 constant potential supply circuits
8 power-supply circuits
10,27,57 light-emitting components
11 the 2nd on-off elements
12,28.58 driver elements
13 the 1st on-off elements
25,55 the 1st power-supply circuits
26,56 the 2nd power-supply circuits
29,59 on-off elements
Embodiment
[0038]
Below, with reference to accompanying drawing, tell about the embodiment of the image display apparatus that the present invention relates in detail.In addition, the present invention is not limited to adopt this embodiment.
[0039]
Fig. 1 is the integrally-built figure of the image display apparatus that relates to of expression the 1st embodiment of the present invention.Image display apparatus shown in Figure 1, have and prevent function luminous in the reset process that should improve contrast, possess a plurality of pixel circuits 1 (these pixel circuits 1 are disposed by the ranks shape), (this signal-line driving circuit 3 is done media by a plurality of signal wires 2 to signal-line driving circuit 3, supply with the luminance signal of hereinafter telling about to a plurality of pixel circuits 1), scan line drive circuit 5 (this scan line drive circuit 5 is done media by a plurality of sweep traces 4, supplies with the sweep signal that is intended to select supply with the pixel circuit 1 of luminance signal to pixel circuit 1).
[0040]
In addition, image display apparatus also possesses: constant potential supply circuit 6, and the anode of the light-emitting component 10 (hereinafter telling about) that this constant potential supply circuit 6 has in pixel circuit 1 is supplied with certain conducting current potential; Drive and Control Circuit 7, this Drive and Control Circuit 7 is done media by control line 9, the driving of the 2nd on-off element 11 (hereinafter telling about) that has in the control pixel circuit 1; Power-supply circuit 8, this power-supply circuit 8 are supplied with the conducting current potential to the source of driver element 12 electrode in reset process, then supply with 0 current potential in other step.
[0041]
[0042]
Light-emitting component 10 has that electric current injects and luminous mechanism is for example formed by organic EL.Organic EL has the structure that possesses following each layer at least: the anode layer and the cathode layer that are formed by Al, Cu, ITO (Indium TinOxide) etc., and the luminescent layer that is formed by organic class materials such as adjacent benzene anthocyanin, three aluminium coordination compoundes, benzene hydroxyquinoline (ベ Application ゾ キ ノ リ ノ ラ ト), beryllium coordination compoundes between anode layer and the cathode layer.Organic EL has hole that utilize to inject luminescent layer and an electronics luminous again in conjunction with and produce the function of light.
[0043]
The 2nd on-off element 11 has the function of the conducting between control light-emitting component 10 and the driver element 12, in the present embodiment, is formed by n type thin film transistor (TFT).In other words, the drain electrode of thin film transistor (TFT) and source electrode, be connected with light-emitting component 10, driver element 12 respectively, has the structure that gate electrode is connected with Drive and Control Circuit 7 electric property on the other hand, according to the current potential that Drive and Control Circuit 7 is supplied with, the conducting state between control light-emitting component 10 and the driver element 12.
[0044]
[0045]
After electrostatic condenser 15 and signal-line driving circuit 3 combinations, form brightness current potential/reference potential supply unit 16.This brightness current potential/reference potential supply unit 16 as brightness current potential feed unit, has function that detects the potential difference (PD) corresponding with the drive threshold of driver element 12 (below be called " threshold voltage ") and the function of supplying with reference potential.
[0046]
Threshold voltage detecting element 14 is elements that value is intended to detect the threshold voltage of driver element 12.In the present embodiment, threshold voltage detecting element 14 is formed by the 1st on-off element 13 that n type thin film transistor (TFT) constitutes.In other words, a source/drain electrode of the 1st on-off element 13 is connected another source/drain electrode with the drain electrode of driver element 12, be connected with the gate electrode of driver element 12, have the structure that the gate electrode of thin film transistor (TFT) is connected with scan line drive circuit 5 electric property.Like this, threshold voltage detecting element 14 has the current potential of supplying with according to scan line drive circuit 5, makes the function of conducting between the grid leak of the thin film transistor (TFT) that the 1st on-off element 13 constitutes, and also has making between the grid leak when the conducting, detects the function of threshold voltage.
[0047]
The sequential chart of the sample attitude of the potential change of each inscape of the image display apparatus that the 1st embodiment of the present invention related to when Fig. 2 was the expression action.In Fig. 2, sweep trace (n-1) is as a reference, expresses the figure with the sequential chart that is positioned at pixel circuit 1 corresponding scanning line of prime and control line.Fig. 3-1～Fig. 3-4, the expression with shown in Figure 2 during t
1～during t
4The figure of the state of corresponding pixel circuit 1.
[0048]
At first, carry out reset process that the outer current potential that adds to the gate electrode of driver element 12 when in the past luminous is resetted.Specifically, as t during Fig. 2
1And shown in Fig. 3-1, the potential change of power-supply circuit 8, Drive and Control Circuit 7 and sweep trace 4 (scan line drive circuit 5) becomes the conducting current potential.In addition, the current potential of constant potential supply circuit 6 becomes fixing conducting current potential all the time.On the other hand, the current potential of signal wire 2 becomes V
DL
[0049]
In other words, shown in Fig. 3-1, the 2nd on-off element 11 and the 1st on-off element 13 become conducting state.On the other hand, because the current potential of power-supply circuit 8 is conducting current potentials, so driver element 12 becomes cut-off state.Like this, form the current potential of the 1st electrode 17 of electrostatic condenser 15, just become, deduct the value after the voltage drop in the light-emitting component 10 from supplied with the current potential of the anode-side of light-emitting components 10 by constant potential supply circuit 6.In general, because the conducting current potential that constant potential supply circuit 6 is supplied with has very high value, so the current potential of the 1st electrode 17 (being the current potential of the gate electrode of driver element 12) becomes and is retained than threshold voltage V
ThHigh value---V
t
[0050]
On the other hand, as shown in Figure 2, because the current potential of signal wire 2 becomes V
DLSo, form electrostatic condenser 15 another electrode---the current potential of the 2nd electrode 18 becomes V
DLT during Fig. 2 like this, just
1And in the step shown in Fig. 3-1, supply with V to the 1st electrode 17
r(＞V
Th) current potential, supply with V to the 2nd electrode 18
DLCurrent potential.
[0051]
Fig. 4 is that the 1st on-off element 13 shown in the presentation graphs 3-1 becomes conducting state (driver element 12: the cut-off state) figure of transition response characteristics afterwards.In other words, in the figure, express the current potential V of the cathode potential Va ' of light-emitting component 10, the gate electrode of driver element 12 (the 1st electrode 17)
r(＞V
Th), flow through the current i of light-emitting component 10
D, OLEDThe transition response characteristics.
[0052]
As known in the figure:, make the 1st on-off element 13 become conducting state (driver element 12: cut-off state), be accompanied by current potential Vr and rise, rise after current potential Va ' slightly descends at Time=0.00.
[0053]
In the 1st embodiment, set the parameters C in the following formula (1) here,
SAnd C
OLED,, be the threshold voltage V that preamble is told about so that the potential difference (PD) between the anode-cathode of the light-emitting component 10 when current potential Va ' is slightly descended (from the conducting current potential of constant potential supply circuit 6 and current potential Va ' poor)
Th, i-vMore than (Figure 14-1) and less than threshold voltage V
Th, L-v(Figure 14-2).Parameters C
S, be the value of electrostatic condenser 15.Parameters C
OLED, be the electrostatic capacitance composition of light-emitting component 10.
V
th，L-v＞(C
s/(C
s+C
OLBD))·V
th，i-v (1)
Like this, in the 1st embodiment, because in reset process, the potential difference (PD) between the anode-cathode of light-emitting component 10 is threshold voltage V
Th, i-vMore than (Figure 14-1) and less than threshold voltage V
Th, L-vSo, as shown in Figure 4, though current i
D, OLED' flow into a little, but not luminous.
[0054]
Then, as t during Fig. 2
2And shown in Fig. 3-2, the current potential of power-supply circuit 8 becomes 0 current potential from the conducting current potential.In addition, after the current potential of Drive and Control Circuit 7 became stopping potential from the conducting current potential, the 2nd on-off element 11 became cut-off state.In addition, after the current potential of sweep trace 4 was maintained in the conducting current potential, the 1st on-off element 13 was kept conducting state.And then the current potential of signal wire 2 is maintained in 0 current potential.
[0055]
At first, tell about the potential change of the 1st electrode 17.As mentioned above, because driver element 12 is varied to conducting state, so in driver element 12, gate electrode and drain electrode are electrically connected.On the other hand, as previously mentioned, till last one step, the gate electrode of driver element 12 is keeping than threshold voltage V
ThHigh value, the source electrode is supplied with current potential V by power-supply circuit 8
DLSo the potential difference (PD) that becomes between the leakage of source becomes V
r, driver element 12 becomes conducting state.
[0056]
Like this, about driver element 12, become each of drain electrode, source electrode, do media by the 1st on-off element 13, by the state of gate electrode conducting, according to the electric charge that is kept by gate electrode, current i flows.Because this current i flows, till driver element 12 becomes cut-off state, so the potential difference (PD) between the grid leak in the driver element 12 finally becomes and threshold voltage V
ThThe value that equates is because the source electrode is kept 0 current potential, so the current potential of the gate electrode of driver element 12, promptly the current potential of the 1st electrode 17 becomes V
ThOn the other hand, the current potential of the 2nd electrode 18 is done media by signal wire 2, is supplied to V
DLIn addition, in the time of for example will utilizing as driver element by the low element of the such degree of excursion of the thin film transistor (TFT) that uncrystalline silicon constitutes, t during preferably being provided with
2, and resemble the high element of degree of excursion the polysilicon, even t during this period is not set
2, also can make its action.
[0057]
Then, as t during Fig. 2
3And shown in Fig. 3-3, do media by signal wire 2, supply with brightness current potential V by signal-line driving circuit 3
DataAt this moment, the current potential of gate electrode becomes once more and compares V
ThHeight is done media by the 1st on-off element 13 and driver element 12, and electric current flows, and the current potential of the gate electrode of driver element 12 becomes V once more
ThAt last, in luminous step, as t during Fig. 2
4And shown in Fig. 3-4, do media by signal wire 2, supply with reference potential V by signal-line driving circuit 3
DHd, the current potential of the 1st electrode 17 becomes V
Th-V
Data+ V
DH, current i
d(=(β/2) (V
DH-V
Data) 2) inflow light-emitting component 10.In addition, β is the value that is directly proportional with the degree of excursion of the charge carrier of driver element 12, in the driver element 12 of this pixel, is intrinsic value.
[0058]
In sum, after adopting the 1st embodiment, since will be in the past luminous when outside add in the reset process that the current potential of the 1st terminal (gate electrode) of driver element 12 resets, the current potential of supplying with to each one, be to produce to make electric current flow into light-emitting component 10 and the potential difference (PD) in non-luminous specialized range, so not luminous in reset process, can improve contrast.
[0059]
Fig. 5 is the amplification plan view of the image display apparatus that relates to of the 1st embodiment.Fig. 5 expresses especially from the layout of the lower floor of the lower electrode of light-emitting component 10 (non-demonstration).In a pixel, 3 TFT (driver element the 12, the 1st on-off element the 13, the 2nd on-off element 11) and electrostatic condenser 15 are shown.Constitute the layer of each element, from lower floor, successively by lower electrode layer (zone of painting with the round dot pattern among the figure), insulation course (zone beyond the part of painting with black among the figure), active layer (zone of painting with oblique line among the figure) and top electrode layer (surround with solid line among the figure, and not the zone of blacking) formation.In addition, the terminal LT among the figure is connected with an end of light-emitting component 10.
[0060]
Lower electrode layer forms on substrate, comprises power lead GL that the gate electrode (control line 9) of the gate electrode of driver element 12, the gate electrode of the 1st on-off element 13 (sweep trace 4), the 2nd on-off element 11 is connected with power-supply circuit 8 and the 1st electrode 17 of electrostatic condenser 15.Whole the upward formation of insulation course 2 openings (part of painting with black among the figure) on lower electrode layer.This insulation course for 3 TFT, plays a role as gate insulating film, for electrostatic condenser 15, plays a role as dielectric layer.Active layer forms on insulation course, comprises the active layer of 3 TFT.Top electrode layer forms on active layer, comprises source/drain electrode, the 2nd electrode 18 of electrostatic condenser 15, the signal wire 2 of 3 TFT.
[0061]
In addition, described insulation course, has the opening that the power lead GL that will be connected with power-supply circuit 8 is connected with the gate electrode of driver element 12, the opening that is connected with the drain electrode of the 1st on-off element with gate electrode with the 1st electrode 17 of electrostatic condenser 15 and driver element 12, use these openings, the conducting levels.
[0062]
In addition, as the constituent material of each layer, lower electrode layer and top electrode layer can be used aluminium or its alloy, and insulating film layer can use silicon nitride film, silicon oxide layer or their potpourri etc., and active layer can use uncrystalline silicon, polysilicon etc.
[0063]
As known in the figure, in the present embodiment, owing to can utilize 3TFT to realize threshold voltage V
Thi-v, compensation, so in the layout of an one pixel, leeway can be arranged, the driver element 12 and area of electrostatic condenser 15 become big.Like this, the resistance of driver element 12 can be reduced, the power consumption of image display apparatus can be reduced.Particularly driver element 12 is when being formed by the big uncrystalline silicon transistor of resistance, and its effect is bigger.In addition, after the employing present embodiment, even the area of a pixel is little of 7000 μ m
2-50000 μ m
2The time, also can guarantee becomes suitable size with the electric capacity of electrostatic condenser 15.
[0064]
In addition, for the area S of a pixel
1, the area S of driver element 12
2Shared ratio (S in each pixel
2/ S
1), and/or for the area S of a pixel
1, the area S of electrostatic condenser 15
3Shared ratio (S in each pixel
3/ S
1), preferably be set at (preferably more than 0.07,0.1 is better) more than 0.05.In the present embodiment, be among 51 μ m * 153 μ m in the size of a pixel, guarantee S
2/ S
1Be 0.1, S
3/ S
1Be 0.12.
[0065]
In addition, S
2/ S
1And S
3/ S
1Preferably below 0.25.Because if S
2And S
3Too big, other the circuit area that can occupy just diminishes so, the become cause of trouble of circuit arrangement.
[0066]
In addition, owing to flow through driver element 12 greater than the electric current of the 1st and the 2nd on-off element 13,11, so preferably will be for the area S of each the 1st and the 2nd on-off element 13,11
4The area S of driver element 12
2(the S of ratio
2/ S
4) set 2～10 for (5～10 are better).
[0067]
In addition, so-called " area S
1", be meant the area that the boundary line of being divided each pixel with the area that equates surrounds.In addition, so-called " area S
2", be meant the source electrode of driver element 12 and drain electrode and the area of the summation of the active layer that clipped by source electrode and drain electrode.In addition, so-called " source electrode and drain electrode " is meant in the electrode layer that constitutes these electrodes the zone that is connected with active layer.And then, so-called " area S
3", the area that the 1st electrode 17 that is meant electrostatic condenser 15 is relative with the 2nd electrode 18.In addition, so-called " area S
4", be meant the source electrode of each on-off element 11,13 and drain electrode and the area of the summation of the active layer that clipped by source electrode and drain electrode.
[0068]
In above-mentioned the 1st embodiment, as shown in Figure 1, told about the example of using function luminous in prevent in each pixel circuit 1, to have 3 thin film transistor (TFT)s reset process of 3TFT structure of (the 2nd on-off element 11, driver element 12 and the 1st on-off element 13).But, also can be applied in the function that the 2TFT structure that has 2 thin film transistor (TFT)s in each pixel circuit 1 relates to.Below, as the 2nd embodiment, tell about this example.
[0069]
Fig. 6 is the integrally-built figure of the image display apparatus that relates to of expression the 2nd embodiment of the present invention.Image display apparatus shown in Figure 6, the same with image display apparatus shown in Figure 1, have and prevent function luminous in the reset process that should improve contrast, possess a plurality of pixel circuits 20 (these pixel circuits 20 are disposed by the ranks shape), (this signal-line driving circuit 22 is done media by a plurality of signal wires 21 to signal-line driving circuit 22, supply with the luminance signal of hereinafter telling about to a plurality of pixel circuits 20), scan line drive circuit 24 (this scan line drive circuit 24 is done media by a plurality of sweep traces 23, supplies with the sweep signal that is intended to select supply with the pixel circuit 20 of luminance signal to pixel circuit 20).
[0070]
In addition, image display apparatus also possesses: the 1st power-supply circuit 25, the 1 power-supply circuits 25 are when resetting, and the anode of the light-emitting component 27 (hereinafter telling about) that has in pixel circuit 20 is supplied with certain conducting current potential; The 2nd power-supply circuit 26, the 2 power-supply circuits 26 are supplied with the conducting current potential to the source of driver element 28 electrode in reset process, then supply with 0 current potential negative potential in other step.
[0071]
Pixel circuit 20 possesses: light-emitting component 27, and the anode of this light-emitting component 27 is electrically connected with the 1st power-supply circuit 25; Driver element 28, the source electrode of this driver element 28 is electrically connected with the 2nd power-supply circuit 26; Threshold voltage detecting element 30, this threshold voltage detecting element 30 is formed by the on-off element 29 of the conducting state between the grid leak of controlling the thin film transistor (TFT) that forms driver element 28.
[0072]
Light-emitting component 27 has that electric current injects and luminous mechanism is for example formed by organic EL.Driver element 28 has the function that control flows into the electric current of light-emitting component 27.Specifically, driver element 28 has according to the potential difference (PD) more than the drive threshold that adds to outward between the 1st terminal and the 2nd terminal, control flows into the function of the electric current of light-emitting component 27, also have added this potential difference (PD) during, make electric current continue the function of inflow light-emitting component 27.In this 2nd embodiment, driver element 28 is formed by n type thin film transistor (TFT), according to adding to the gate electrode that is equivalent to the 1st terminal outward and being equivalent to potential difference (PD) between the source electrode of the 2nd terminal, controls the luminosity of light-emitting component 27.
[0073]
After electrostatic condenser 31 and signal-line driving circuit 22 combinations, form brightness current potential/reference potential supply unit 32.This brightness current potential/reference potential supply unit 32 as brightness current potential feed unit, has the function of supplying with the luminosity voltage corresponding with the luminosity of light-emitting component 27 and the function of supplying with reference potential.
[0074]
The sequential chart of the sample attitude of the potential change of each inscape of the image display apparatus that this 2nd embodiment related to when Fig. 7 was the expression action.In Fig. 7, sweep trace (n-1) is as a reference, expresses the figure with the sequential chart that is positioned at pixel circuit 20 corresponding scanning line of prime and control line.Fig. 8-1, the expression with shown in Figure 7 during t
1～during t
6During t
1, i.e. the figure of the state of the pixel circuit 20 corresponding with reset process.
[0075]
At first, carry out reset process that the outer current potential that adds to the gate electrode of driver element 28 when in the past luminous is resetted.Specifically, as t during Fig. 7
1And shown in Fig. 8-1, the current potential of the 1st power-supply circuit 25 and the 2nd power-supply circuit 26 becomes V
DD, the potential change of sweep trace 23 (scan line drive circuit 24) becomes the conducting current potential.
[0076]
In other words, shown in Fig. 8-1, on-off element 29 becomes conducting state.On the other hand, because the current potential of the 2nd power-supply circuit 26 is V
DD So driver element 28 becomes conducting state.Like this, form the current potential of the 1st electrode 33 of electrostatic condenser 31, just become from supplied with the current potential V of the anode of light-emitting component 27 by the 1st power-supply circuit 25
DD, deduct the voltage drop V in the light-emitting component 27
OLEDAfter value.In general, because the current potential V that the 1st power-supply circuit 25 is supplied with
DDHas very high value, so the current potential of the 1st electrode 33 (being the current potential of the gate electrode of driver element 28) becomes and is retained than threshold voltage V
ThHigh value---(V
DD-V
OLED).
[0077]
On the other hand, as shown in Figure 7, because the current potential of signal wire 21 becomes V
DLSo, form electrostatic condenser 31 another electrode---the current potential of the 2nd electrode 34 becomes V
DLT during Fig. 7 like this, just
1And in the step shown in Fig. 8-1, supply with current potential (V to the 1st electrode 33
DD-V
OLED), supply with current potential V to the 2nd electrode 34
DL
[0078]
In Fig. 8-1, on-off element 29 becomes conducting state (driver element 28 becomes cut-off state) afterwards, is accompanied by current potential (V
DD-V
OLED) rise, after slightly descending, the cathode potential Va of light-emitting component 27 rises.
[0079]
Here, light-emitting component 27 has the threshold voltage of generation V shown in Figure 16-1
Th, i-vAfter the above potential difference (PD) (potential difference (PD) between anode-negative electrode), the I-E characteristic that electric current flows through.In addition, light-emitting component 27 also shown in Figure 16-2, has the threshold voltage of generation V
Th, L-vAfter the above potential difference (PD) (potential difference (PD) between the anode-cathode), the brightness-voltage characteristic of luminous (brightness＞0).
[0080]
In addition, threshold voltage V
Th, i-vBe to be lower than threshold voltage V
Th, L-vValue.Like this, the potential difference (PD) between the anode-cathode of light-emitting component 27 is threshold voltage V
Th, L-vWhen above, become and be accompanied by electric current and flow into light-emitting component 27 and luminous state.In addition, the potential difference (PD) between the anode-cathode of light-emitting component 27 is threshold voltage V
Th, i-vMore than, less than threshold voltage V
Th, L-vThe time, flow into light-emitting component 27 non-luminous states though become electric current.
[0081]
Set the parameters C in the above-mentioned formula (1)
SAnd C
OLED, so that make at Fig. 8-1 o'clock, the potential difference (PD) between the anode-cathode of the light-emitting component 27 when current potential Va slightly descends is (from the conducting current potential V of the 1st power-supply circuit 25
DDPoor with current potential Va), be the threshold voltage V that preamble is told about
Th, i-vMore than (Figure 16-1) and less than threshold voltage V
Th, L-v(Figure 16-2).In this 2nd embodiment, parameters C
S, be the value of electrostatic condenser 15.Parameters C
OLED, be the electrostatic capacitance composition of light-emitting component 27.
[0082]
Like this, in Fig. 8-1, because in reset process, the potential difference (PD) between the anode-cathode of light-emitting component 27 is threshold voltage V
Th, i-vMore than (Figure 16-1), less than threshold voltage V
Th, L-vSo, though current i
D, OLEDFlow into a little, but not luminous, so can improve contrast.
[0083]
Then, as t during Fig. 7
2And shown in Fig. 8-2, in preparation process, the current potential of the 1st power-supply circuit 25 is-V
E(＜V
Th), the current potential of signal wire 21 is V
DH, the 2nd power-supply circuit 26 current potential be V
DD, sweep trace 23 current potential be stopping potential after, the current potential of deleting electrode of driver element 28 becomes V
DD-V
OLED(voltage drop of light-emitting component OLED)+V
DH-V
DL, be higher than the threshold voltage V of driver element 28
ThIn addition, on-off element 29 is cut-off states.Like this, driver element 28 becomes conducting state, and current i flows.
[0084]
Then, as t during Fig. 7
3And shown in Fig. 8-3, detect in the step at threshold voltage, the current potential of the 1st power-supply circuit 25 is that the current potential of 0 current potential, signal wire 21 is V
DH, the 2nd power-supply circuit 26 current potential be that on-off element 29 became conducting state after the current potential of 0 current potential, sweep trace 23 was the conducting current potential.Like this, do media by on-off element 29 and driver element 28, current i flows.
[0085]
Follow again, as t during Fig. 7
4And shown in Fig. 8-4, in the data write step, the current potential of the 1st power-supply circuit 25 is 0 current potentials, supplies with brightness current potential V by signal wire 21
DATA, the 2nd power-supply circuit 26 current potential be that on-off element 29 became conducting state after the current potential of 0 current potential, sweep trace 23 was the conducting current potential.Like this, the current potential of deleting electrode of driver element 28 becomes α (V
DATA-V
DH)+V
ThIn addition, α is C
S/ (C
S+ C
OLED).
[0086]
Here, because on-off element 29 becomes conducting state, so the current potential of deleting electrode of the current potential of the cathode electrode of light-emitting component 27 and driver element 28 is idiostatic.
[0087]
Follow again, as t during Fig. 7
5And shown in Fig. 8-5, in the 2nd reset process, the current potential of the 1st power-supply circuit 25 is-V
E, signal wire 21 current potential be V
DH, the 2nd power-supply circuit 26 current potential be-V
E, sweep trace 23 current potential be stopping potential after, on-off element 29 is cut-off states.Like this, the current potential of deleting electrode of driver element 28 becomes (1-α) (V
DH-V
DATA)+V
ThAt t this period
5In, the current potential of the cathode electrode of light-emitting component 27 becomes-V
E, be reset.
[0088]
Follow again, as t during Fig. 7
6And shown in Fig. 8-6, in luminous step, the current potential of the 1st power-supply circuit 25 is V
DD, signal wire 21 current potential be V
DH, the 2nd power-supply circuit 26 current potential be after the current potential of 0 current potential, sweep trace 23 is stopping potential, current i
d(=(β/2) ((1-α) (V
DH-V
Data))
2) flowing into light-emitting component 27, light-emitting component 27 is luminous.Here, current i
dDo not exist with ... threshold voltage V
Th
[0089]
In sum, adopt the 2nd embodiment after owing to have driver element 28 (this driver element 28 be according to the threshold voltage V that is higher than regulation that adds to outward between the 1st terminal and the 2nd terminal
ThPotential difference (PD), control light-emitting component 27) and on-off element 29 (this on-off element 29 detect and the 1st terminal and the 2nd terminal between threshold voltage V
ThCorresponding potential difference (PD)), before making the luminous luminous step of light-emitting component 27, the threshold voltage V during the detecting of the threshold voltage that carries out as the step that was lower than before luminous step
ThCurrent potential, to driver element 28 and light-emitting component 27 supply-V
E(with reference to Fig. 7 and Fig. 8-5) in luminous step (with reference to figure Fig. 8-6), supplies with to be intended to make and do not exist with ... threshold voltage V
ThCurrent i
dThe current potential that flows so can utilize driver element 28 and on-off element 29 this 2TFT structures, improves fineness.
[0090]
Fig. 9 is the amplification plan view of the image display apparatus of the 2nd embodiment.Express the layout of the lower floor of lower electrode (non-demonstration) among the figure from light-emitting component 27.In a pixel, 2 TFT (driver element 28, on-off element 29) and electrostatic condenser 31 are shown.Constitute the layer of each element, from lower floor, successively by lower electrode layer (zone of painting with the round dot pattern among the figure), insulation course (zone beyond the part of painting with black among the figure), active layer (zone of painting with oblique line among the figure) and top electrode layer (surround with solid line among the figure, and not the zone of blacking) formation.In addition, the terminal LT among the figure is connected with an end of light-emitting component 27.
[0091]
Lower electrode layer forms on substrate, comprises the 1st electrode 33 of the gate electrode of driver element 27, the gate electrode of on-off element 29 (sweep trace 24), the power lead GL that is connected with the 2nd power-supply circuit 26 and electrostatic condenser 31.Insulation course forms on whole 2 openings on lower electrode layer.This insulation course for 2 TFT, plays a role as gate insulating film, for electrostatic condenser 31, then plays a role as dielectric layer.Active layer forms on insulation course, comprises the active layer of 2 TFT.Top electrode layer forms on active layer, comprises source/drain electrode, the 2nd electrode 34 of electrostatic condenser 31, the signal wire 21 of 2 TFT.
[0092]
In addition, insulation course, has the opening that the power lead that will be connected with the 2nd power-supply circuit 26 is connected with the source electrode of driver element 12, the opening that is connected with the drain electrode of on-off element 29 with gate electrode with the 1st electrode 33 of electrostatic condenser 31 and driver element 28, use these openings, the conducting levels.In addition, the constituent material of each layer is the same with the 1st embodiment.
[0093]
As known in the figure, in this 2nd embodiment, owing to can utilize 2 TFT to realize threshold voltage V
ThCompensation, so compare, can enlarge driver element 28 and with the area of electrostatic condenser 31 with the 1st embodiment.In addition, in this 2nd embodiment, be among 51 μ m * 153 μ m in the size of a pixel, guarantee S
2/ S
1Be 0.15, S
3/ S
1Be 0.14.
[0094]
Figure 10 is the integrally-built figure of the image display apparatus that relates to of expression the 3rd embodiment of the present invention.Image display apparatus shown in Figure 10, possess a plurality of pixel circuits 50 (these pixel circuits 50 are disposed by the ranks shape), (this signal-line driving circuit 52 is done media by a plurality of signal wires 51 to signal-line driving circuit 52, supply with the luminance signal of hereinafter telling about to a plurality of pixel circuits 50), scan line drive circuit 54 (this scan line drive circuit 54 is done media by a plurality of sweep traces 53, supplies with the sweep signal that is intended to select supply with the pixel circuit 50 of luminance signal to pixel circuit 50).This image display apparatus adopts the 2TFT structure.
[0095]
In addition, image display apparatus also possesses: the 1st power-supply circuit 55, the 1 power-supply circuits 55, and the drain electrode of the driver element 58 (hereinafter telling about) that has in pixel circuit 50 is supplied with current potential; The 2nd power-supply circuit 56, the 2 power-supply circuits 56 are supplied with current potential to the negative electrode of light-emitting component 57.
[0096]
[0097]
Light-emitting component 57 has electric current and injects and luminous mechanism, and the organic EL of being told about by preamble forms.Driver element 58 has the function that control flows into the electric current of light-emitting component 57.Specifically, driver element 58 has according to the potential difference (PD) more than the drive threshold that adds to outward between the 1st terminal and the 2nd terminal, control flows into the function of the electric current of light-emitting component 57, also have added this potential difference (PD) during, make electric current continue the function of inflow light-emitting component 57.In this 3rd embodiment, driver element 58 is formed by n type thin film transistor (TFT), according to adding to the gate electrode that is equivalent to the 1st terminal outward and being equivalent to potential difference (PD) between the source electrode of the 2nd terminal, controls light-emitting component 57.
[0098]
After electrostatic condenser 61 and signal-line driving circuit 52 combinations, form brightness current potential/reference potential supply unit 64.This brightness current potential/reference potential supply unit 64 as brightness current potential feed unit, has the function of supplying with the luminosity voltage corresponding with the luminosity of light-emitting component 57 and the function of supplying with reference potential.
[0099]
The sequential chart of the sample attitude of the potential change of each inscape of the image display apparatus that this 3rd embodiment related to when Figure 11 was the expression action.In Figure 11, sweep trace (n-1) is as a reference, expresses the figure with the sequential chart that is positioned at pixel circuit 50 corresponding scanning line of prime and control line.Figure 12-1, with shown in Figure 11 during t
1～during t
4During t
1, promptly to detect step corresponding with threshold voltage.
[0100]
In other words, as t during Figure 11
1And shown in Figure 12-1, detect in the step at threshold voltage, the current potential of the 1st power-supply circuit 55 is that the current potential of 0 current potential, signal wire 51 is V
DH, the 2nd power-supply circuit 56 current potential be V
E2, sweep trace 53 current potential be the conducting current potential after, on-off element 59 becomes conducting state.Like this, do media by on-off element 59 and driver element 58, current i flows.
[0101]
Then, as t during Figure 11
2And shown in Figure 12-2, in the data write step, the current potential of the 1st power-supply circuit 55 is 0 current potentials, supplies with brightness current potential V by signal wire 51
DATA, the 2nd power-supply circuit 56 current potential be V
E2, sweep trace 53 current potential be the conducting current potential after, on-off element 59 becomes conducting state.Like this, the current potential of deleting electrode of driver element 58 becomes α (V
DATA-V
DH)+V
ThIn addition, α is C
S/ (C
S+ C
OLED).
[0102]
Follow again, as t during Figure 11
3And shown in Figure 12-3, in reset process, the current potential of the 1st power-supply circuit 55 is-V
E1The V of (＜-
Th), the current potential of signal wire 51 is V
DH, the 2nd power-supply circuit 56 current potential be V
E2, sweep trace 53 current potential be stopping potential after, on-off element 59 is cut-off states.Like this, the current potential of deleting electrode of driver element 58 becomes (1-α) (V
DH-V
DATA)+V
ThAt t this period
3In, the current potential of the negative electrode of light-emitting component 57 becomes-V
E1, be reset.
[0103]
Follow again, as t during Figure 11
4And shown in Figure 12-4, in luminous step, the current potential of the 1st power-supply circuit 55 is that the current potential of 0 current potential, signal wire 51 is V
DH, the 2nd power-supply circuit 56 current potential be-V
EE, sweep trace 53 current potential be stopping potential after, current i
d(=(β/2) ((1-α) (V
DH-V
DATA)-(V
EE+ V
OLED))
2) flowing into light-emitting component 57, light-emitting component 57 is luminous.Here, current i
dDo not exist with ... threshold voltage V
Th
[0104]
In addition, in the image display apparatus of the structure shown in Figure 13-1 and Figure 14-1, also can use the function that prevents that reset process is luminous.Image display apparatus shown in Figure 13-1 (the 4th embodiment), on-off element T1, on-off element T2, on-off element T3, driver element T4, electrostatic condenser C1, electrostatic condenser C2 and light-emitting component OLED, connect as shown in figure, move according to the sequential chart shown in Figure 13-2.
[0105]
On-off element T1～T3 and driver element T4 are p type thin film transistor (TFT)s.In reset process, Power (stopping potential) is driven device elements T 4 and supplies with.At this moment, because the negative electrode of light-emitting component OLED is grounded, become stopping potential, so driver element T4 becomes cut-off state, on-off element T2 becomes conducting state.At this moment, the same with the 1st embodiment, though it is not optical element OLED has electric current to flow through, luminous.
[0106]
In addition, in the image display apparatus shown in Figure 14-1 (the 5th embodiment), on-off element T1 ', on-off element T2 ', on-off element T3 ', driver element T4 ', electrostatic condenser C1 ', electrostatic condenser C2 ' and light-emitting component OLED ', connect as shown in figure, move according to the sequential chart shown in Figure 14-2.
[0107]
On-off element T1 '～T3 ' and driver element T4 ' are n type thin film transistor (TFT)s.In reset process, Power (stopping potential) is driven device elements T 4 ' and supplies with.At this moment, because the negative electrode of light-emitting component OLED ' is supplied to conducting current potential V
DDSo driver element T4 ' becomes cut-off state, on-off element T2 ' becomes conducting state.At this moment, the same with the 1st embodiment, optical element OLED ' though have electric current to flow through, not luminous.
[0108]
In sum, adopt the 4th and the 5th embodiment after, can obtain the effect same with the 1st embodiment.In addition, in the 1st～the 5th above-mentioned embodiment, told about the situation that satisfies above-mentioned formula (1).But in the 1st～the 5th above-mentioned embodiment, when not satisfying formula (1), also because in reset process, driver element is a cut-off state, so can make by the magnitude of current of light-emitting component littler than prior art, can reduce the luminous quantity of light-emitting component, can make contrast than prior art height.
[0109]
Other effect and variation can be derived at an easy rate by the people in the industry.Therefore, the attitude of sample widely of the present invention is not limited to above specific detailed content of telling about and representational embodiment.So, can carry out various changes without prejudice to the spirit and scope of the notion of the recapitulative invention of additional " claims " and equal document definition thereof.
[0110]
For example, in this 1st～the 2nd embodiment, in reset process, supply with than drive threshold V to the gate electrode of driving transistors
ThHigh current potential V
rBut this current potential V
rMay not leave no choice but than drive threshold V
ThHeight cans be compared to drive threshold V most
ThHigh.Current potential V
rBe lower than drive threshold V
ThThe time, adjust threshold voltage and detect the source potential of initial driving transistors of step and signal wire current potential etc., thereby make threshold voltage detect potential difference (PD) between the grid source of initial driving transistors of step greater than drive threshold V
Th
[0111]
In sum, the image display apparatus that the present invention relates to is of great use as the display device of using organic EL, is particularly suitable for requiring the image of high meticulous demonstration to show.
Claims (17)
1, a kind of image display apparatus is characterized in that, possesses:
A plurality of pixels, this pixel has:
Light-emitting component;
Driving transistors, this driving transistors has gate electrode, source electrode and drain electrode, and an end of described light-emitting component is electrically connected with side's electrode in described source electrode and the described drain electrode;
The 1st switching transistor, the 1st switching transistor make the described gate electrode of described driving transistors and described side's electric pole short circuit of described driving transistors according to sweep signal; And
The described gate electrode that capacitor element, this capacitor element possess the 1st electrode and the 2nd electrode, described driving transistors is connected with described the 1st electrode;
Signal wire, this signal wire is connected with described the 2nd electrode of described capacitor element;
Signal-line driving circuit, this signal-line driving circuit are supplied with the reference potential of brightness current potential and this brightness current potential benchmark of expression to described signal wire; And
Power-supply circuit, this power-supply circuit are controlled the current potential of described the opposing party's electrode of the described source electrode of described driving transistors and described drain electrode.
2, image display apparatus as claimed in claim 1 is characterized in that, possesses: the 1st power-supply circuit, and the 1st power-supply circuit is connected jointly with the other end of the described light-emitting component of described each pixel, supplies with the 1st current potential to the described other end; With
The 2nd power-supply circuit, the 2nd power-supply circuit is supplied with the 2nd current potential to described the opposing party's electrode of described driving transistors, utilizes the 2nd current potential, controls the conduction and cut-off of described driving transistors, described the 2nd power-supply circuit is described power-supply circuit.
3, image display apparatus as claimed in claim 1, it is characterized in that: also possess the 2nd switching transistor, the 2nd switching transistor is according to driving current potential, controls the conducting between described side's electrode of the described end of described light-emitting component and described driving transistors.
4, image display apparatus as claimed in claim 3 is characterized in that: described the 1st power-supply circuit, with fixing current potential, supply with described the 1st current potential.
5, image display apparatus as claimed in claim 2 is characterized in that: described the 1st power-supply circuit, according to described the 2nd current potential, control described the 1st current potential.
6, as each described image display apparatus of claim 1～5, it is characterized in that: described light-emitting component is an organic EL.
7, image display apparatus as claimed in claim 6 is characterized in that: if the 1st threshold voltage of this organic EL that electric current begins to flow in described organic EL is V
Th, i-v, the 2nd threshold voltage of luminous this organic EL of beginning is V in described organic EL
Th, L-v, described organic EL electrostatic capacitance value be C
OLBD, described capacitor element capacitance be C
s, then satisfy the following relationship formula:
V
th，L-v＞(C
s/(C
s+C
OLBD))·V
th，i-v。
8, a kind of driving method of image display apparatus is characterized in that: described image display apparatus possesses:
Light-emitting component;
Driving transistors, this driving transistors has gate electrode, source electrode and drain electrode, and described light-emitting component is electrically connected with side's electrode in described source electrode and the described drain electrode; And
Switching transistor, this switching transistor make the described gate electrode of described driving transistors and described side's electric pole short circuit of described driving transistors according to sweep signal,
The driving method of described image display apparatus comprises:
The 1st step, this step is at the current potential of the described gate electrode that passes through the described switching transistor of control, set described switching transistor for conducting, and by the described source electrode of the described driving transistors of control and the current potential of the opposing party's electrode in the described drain electrode, described driving transistors is set under the state that ends, supplied with current potential to the described gate electrode of the driving transistors of described each pixel; With
The 2nd step, this step is by the current potential of the described gate electrode of the described switching transistor of control, set described switching transistor for conducting, and the current potential of described the opposing party's electrode by the described driving transistors of control, set described driving transistors for conducting, thereby make current potential be higher than drive threshold for the described gate electrode of described the opposing party's electrode of described driving transistors, then, from the gate electrode of described driving transistors through the described the opposing party electrode supplying electric current of described switching transistor to described driving transistors, thereby will be for the current potential of the described gate electrode of described the opposing party's electrode of described driving transistors, as drive threshold.
9, the driving method of image display apparatus as claimed in claim 8, it is characterized in that: described image display apparatus, also possess capacitor element, this capacitor element has the 1st electrode and the 2nd electrode, and the described gate electrode terminal of described driving transistors is connected with described the 1st electrode;
The driving method of described image display apparatus, also comprise the 3rd step, this step is by the current potential of the described gate electrode of the described switching transistor of control, described switching transistor set for end, and by described capacitor element, control the current potential of the described gate electrode of described driving transistors, set described driving transistors for conducting, thereby make described light-emitting component luminous.
10, the driving method of image display apparatus as claimed in claim 8 or 9, it is characterized in that: described light-emitting component is an organic EL.
11, the driving method of image display apparatus as claimed in claim 8, it is characterized in that: in described the 1st step, through described light-emitting component, the current potential that supply is supplied with to the gate electrode of described driving transistors, and in described the 1st step, make the outer potential difference (PD) that adds to the two ends of described light-emitting component, the 1st threshold voltage that is in this light-emitting component that electric current begins to flow in the described light-emitting component is above, in described light-emitting component below the 2nd threshold voltage of luminous this light-emitting component of beginning.
12, a kind of image display apparatus, it is characterized in that: possess a plurality of pixels, these pixels have light-emitting component, the driving transistors that is electrically connected with an end of described light-emitting component and the capacitor element that is connected with described driving transistors, are S as if the area of a pixel
1, the shared area of driving transistors is S in the pixel
2, the shared area of capacitor element is S in the pixel
3, ratio S then
2/ S
1And/or ratio S
3/ S
1Be more than 0.05.
13, image display apparatus as claimed in claim 12 is characterized in that: described driving transistors is the amorphous silicon transistor.
14, image display apparatus as claimed in claim 13 is characterized in that: the area of a described pixel is 7000 μ m
2～50000 μ m
2
15, as claim 12 or 13 described image display apparatus, it is characterized in that: described ratio S
2/ S
1And/or described ratio S
3/ S
1, be below 0.25.
16, as claim 12 or 13 described image display apparatus, it is characterized in that: described a plurality of pixels also possess other transistor beyond the described driving transistors, for this other transistorized area S
4, the area S of described driving transistors
2Ratio S
2/ S
4, be 2～10.
17, a kind of driving method of image display apparatus is characterized in that: described image display apparatus possesses a plurality of pixels, and these pixels possess:
Light-emitting component;
Driving transistors, this driving transistors has gate electrode, source electrode and drain electrode, and described light-emitting component is electrically connected with side's electrode in described source electrode and the described drain electrode; And
Switching transistor, this switching transistor make the described gate electrode of described driving transistors and described side's electric pole short circuit of described driving transistors according to sweep signal,
Through described light-emitting component and described switching transistor, supply with in the reset process of current potential to the described gate electrode of the described driving transistors of each pixel, adding to the potential difference (PD) at the two ends of described light-emitting component outward, is that the 1st threshold voltage of this light-emitting component that electric current begins to flow in the described light-emitting component is above, described light-emitting component begins below the 2nd threshold voltage of this luminous light-emitting component.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004151041 | 2004-05-20 | ||
| JP151041/2004 | 2004-05-20 | ||
| JP151042/2004 | 2004-05-20 |
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| Publication Number | Publication Date |
|---|---|
| CN1957388A true CN1957388A (en) | 2007-05-02 |
| CN100481180C CN100481180C (en) | 2009-04-22 |
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ID=38063750
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005800160777A Active CN100481180C (en) | 2004-05-20 | 2005-05-20 | Image display device and driving method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8823693B2 (en) | 2009-12-09 | 2014-09-02 | Panasonic Corporation | Display device and method of controlling the same |
| CN108231036A (en) * | 2018-01-10 | 2018-06-29 | 广东欧珀移动通信有限公司 | Display panel, display screen, electronic device, display control method and storage device |
-
2005
- 2005-05-20 CN CNB2005800160777A patent/CN100481180C/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8823693B2 (en) | 2009-12-09 | 2014-09-02 | Panasonic Corporation | Display device and method of controlling the same |
| CN102349098B (en) * | 2009-12-09 | 2015-11-25 | 株式会社日本有机雷特显示器 | Display device and control method thereof |
| CN108231036A (en) * | 2018-01-10 | 2018-06-29 | 广东欧珀移动通信有限公司 | Display panel, display screen, electronic device, display control method and storage device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN100481180C (en) | 2009-04-22 |
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