CN101996581A - Pixel circuit of organic light emitting display - Google Patents
Pixel circuit of organic light emitting display Download PDFInfo
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- CN101996581A CN101996581A CN2010105645781A CN201010564578A CN101996581A CN 101996581 A CN101996581 A CN 101996581A CN 2010105645781 A CN2010105645781 A CN 2010105645781A CN 201010564578 A CN201010564578 A CN 201010564578A CN 101996581 A CN101996581 A CN 101996581A
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Abstract
The invention relates to a pixel circuit of an organic light emitting display, comprising three transistors, a capacitor and an organic light emitting diode. The pixel circuit is characterized in that the three transistors are serially connected according to an annular structure and are respectively a first switch transistor, a second switch transistor and a third switch transistor. The first switch transistor and the second switch transistor are NMOS, and the third switch transistor is PMOS, wherein the grid of the first switch transistor is connected with a scanning wire; the first pole of the first switch transistor is connected with a data wire; and the second pole of the first switch transistor is connected with the organic light emitting diode. The grid of the second switch transistor is connected with a control wire; the first pole of the second switch transistor is connected with the organic light emitting diode and the second pole of the first switch transistor; and the second pole of the second switch transistor is connected with the first pole of the third switch transistor. The pixel circuit overcomes the uneven brightness phenomenon caused by the nonuniformity of the transistor.
Description
Technical field
The invention belongs to display technique field, plane, especially belong to the image element circuit of a kind of organic light emitting display (OLED, Organic Light-Emitting Display).
Background technology
Usually, organic light emitting display is to be combined according to matrix structure by N * M (N is capable, and M is listed as, and N and M are natural number) light emitting pixel unit, and each light emitting pixel unit all comprises a corresponding image element circuit.As shown in Figure 1, existing image element circuit comprises two PMOS transistors, an electric capacity and an Organic Light Emitting Diode, one of them PMOS transistor is switching transistor T1, another PMOS transistor is driving transistors T2, the grid of switching transistor T1 is connected with data line (DATA) with sweep trace (SCAN) respectively with source electrode, and the drain electrode of switching transistor T1 is connected with the grid of driving transistors T2; The source electrode of driving transistors T2 is connected with power voltage line (VDD), thereby drain electrode is connected with Organic Light Emitting Diode D1 and is provided for the luminous electric current of light emitting diode D1; Keeping capacitor C 1 is connected between the source electrode of driving transistors T2 and the grid and is used for keeping in the given time the voltage that applies.The operational process of the image element circuit of said structure is: when switching transistor T1 is switched on according to the selection voltage signal that puts on the sweep trace (SCAN) of its grid, be applied in the grid of driving transistors T2 and keep on the capacitor C 1 from the data voltage signal of data line (DATA), the electric current that is complementary with the data voltage signal of data line (DATA) is stored in to be kept in the capacitor C 1, when driving transistors T2 is switched on, is stored in the electric current of keeping in the capacitor C 1 and is released the light emitting diode D1 that flows through and makes it luminous.
Image element circuit as shown in Figure 1, provide electric current I oled to light emitting diode D1 corresponding to applying data voltage VDATA, and the D1 emission is corresponding to the light of providing electric current I oled, in this case, the multistage value that the data voltage VDATA that is applied has in preset range makes it can represent gray scale.
Yet, there are the following problems for existing image element circuit, the skew of the electron transfer (electron mobility) that causes owing to the skew (deviation) of the threshold voltage VTH of driving transistors T2 and by the heterogeneity (non-uniformity) of integrating process makes that the luminosity of each pixel is inhomogeneous.For example, in the situation of the driving transistors T2 that passes through 3 volts of (3V) driven image element circuits, (=3V/256) voltage makes its gray scale that can represent 8 bits (256 rank), and if cause the threshold voltage V of driving transistors T2 owing to the heterogeneity of integrating process to provide each to be spaced apart 12mV to the grid of driving transistors T2
THBe offset, make that the luminosity of each pixel is inhomogeneous, thereby be difficult to represent accurately high gray scale.
Summary of the invention
The objective of the invention is shortcoming for non-uniform light between the different pixels circuit of the driving circuit that overcomes existing OLED.
Technical scheme of the present invention is: a kind of image element circuit of organic light emitting display, comprise three transistors, an electric capacity and an Organic Light Emitting Diode, it is characterized in that, three transistors are connected successively according to ring texture, be respectively first switching transistor, second switch transistor and the 3rd switching transistor, described first switching transistor and second switch transistor are NMOS, and the 3rd switching transistor is PMOS; The grid of described first switching transistor is connected with sweep trace, and its first utmost point is connected with data line, and its second utmost point is connected with Organic Light Emitting Diode; The transistorized grid of described second switch is connected with control line, and its first utmost point is connected with second utmost point of the Organic Light Emitting Diode and first switching transistor, and first utmost point of its second utmost point and the 3rd switching transistor is connected; The grid of described the 3rd switching transistor is connected with control line, and second utmost point of its first utmost point and driving transistors and an end of electric capacity are connected, and its second utmost point is connected with data line; One end of electric capacity is connected between second utmost point and transistorized first utmost point of capacitance switch of driving transistors, and the other end is connected the common electrical pressure side.
The invention has the beneficial effects as follows: because the transistor among the present invention is all as the switching tube of image element circuit, drive the data-signal that the luminous electric current of Organic Light Emitting Diode is directed to the drive IC generation of OLED display, therefore driving the luminous electric current of Organic Light Emitting Diode can not influenced by transistor and change, thereby has overcome because the brightness irregularities phenomenon that transistorized nonuniformity problem is brought.
Description of drawings
Fig. 1 is the circuit theory diagrams of the image element circuit of existing organic light emitting display.
Fig. 2 is the circuit theory diagrams of the image element circuit of organic light emitting display of the present invention.
Fig. 3 is drive waveforms figure of the present invention.
Embodiment
The invention will be further described below in conjunction with the drawings and specific embodiments.
Because the source electrode of NMOS is to the direction and the current opposite in direction of drain electrode, the source electrode of PMOS is identical with direction of current to the direction of drain electrode, and the direction of the drive current of image element circuit is constantly to change, for convenience of description, we do following regulation: when the grid of PMOS and NMOS is in the top, no matter being positioned at the electrode source electrode or the drain electrode in grid left side is first utmost point by unified Definition, be second utmost point by unified Definition no matter be positioned at the electrode source electrode or the drain electrode on grid right side.
As shown in Figure 2, a kind of image element circuit of organic light emitting display, comprise three transistors, a capacitor C 1 and an Organic Light Emitting Diode D1, three transistors are connected successively according to ring texture, be respectively the first switching transistor T1, second switch transistor T 2 and the 3rd switching transistor T3, described first switching transistor T1 and second switch transistor T 2 are NMOS, and the 3rd switching transistor T3 is PMOS; The grid of the described first switching transistor T1 is connected with sweep trace SCAN, and its first utmost point is connected with data line DATA, and its second utmost point is connected with Organic Light Emitting Diode D1; The grid of described second switch transistor T 2 is connected with control line EMC, and its first utmost point is connected with second utmost point of the first switching transistor T1 with Organic Light Emitting Diode D1, and its second utmost point is connected with first utmost point of the 3rd switching transistor T3; The grid of described the 3rd switching transistor T3 is connected with control line EMC, and second utmost point of its first utmost point and driving transistors T2 and an end of capacitor C 1 are connected, and its second utmost point is connected with data line DATA; One end of capacitor C 1 is connected between first utmost point of second utmost point of driving transistors T2 and capacitance switch transistor T 3, and the other end is connected common electrical pressure side Vcom.
According to the drive waveforms of Fig. 3, driving process of the present invention is described, drive waveforms is respectively the sweep signal that sweep trace SCAN produces among Fig. 3, the data-signal that data line DATA produces, the control signal that control line EMC produces.Be divided into two stages in a drive cycle, the phase one sweep signal is a high level, and data-signal and control signal are low level, and the subordinate phase sweep signal becomes low level, and data-signal and control signal become high level.In phase one, sweep signal is a high level, and control signal is a low level, and T2 ends, T1, T3 conducting, and data-signal is input to D1 through T1, and D1 is a luminance, and data-signal charges to C1 simultaneously; Subordinate phase, sweep signal are low level, and control signal is a high level, and T1, T3 end, the T2 conducting, and the electric charge that is stored on the C1 is released by T2, and it is luminous to continue to promote D1.By above-mentioned process, periodically drive image element circuit of the present invention.
The present invention is for driving OLED, the drive IC of utilizing the OLED display is in order to produce sweep signal, data-signal and control signal, wherein data-signal is the continuous current signal, the type of drive of this programme can not utilize transistor (as the T1 among Fig. 2, T2 and T3) own in the image element circuit to generate electric current, therefore the solution of the present invention is provided by drive IC fully in order to the electric current that drives D1, size of current, direction and variation are all by the drive IC decision, and TFT uses as just switching tube can not influence drive current; And traditional pixel-driving circuit is determined by the driving transistors (as the T2 among Fig. 1) inside the image element circuit in order to the electric current that drives D1, therefore size, direction and the variation of electric current can be subjected to transistorized influence own, therefore and transistor is difficult on manufacturing process guarantee that TFT has consistance, causes transistor output current in the AMOLED panel inhomogeneous and cause the problem of brightness irregularities.
Because the transistor among the present invention such as T1, T2 and T3 are all as the switching tube of image element circuit, drive the data-signal that the luminous electric current of D1 is directed to the drive IC generation of OLED display, therefore driving the luminous electric current of D1 can not influenced by transistor such as T1, T2 and T3 and change, thereby has overcome the brightness irregularities phenomenon of bringing because of the nonuniformity problem of transistor such as T2.
Those of ordinary skill in the art will appreciate that embodiment described here is in order to help reader understanding's principle of the present invention, should to be understood that protection scope of the present invention is not limited to such special statement and embodiment.Those of ordinary skill in the art can make various other various concrete distortion and combinations that do not break away from essence of the present invention according to these technology enlightenments disclosed by the invention, and these distortion and combination are still in protection scope of the present invention.
Claims (1)
1. the image element circuit of an organic light emitting display, comprise three transistors, an electric capacity (C1) and an Organic Light Emitting Diode (D1), it is characterized in that, three transistors are connected successively according to ring texture, be respectively first switching transistor (T1), second switch transistor (T2) and the 3rd switching transistor (T3), described first switching transistor (T1) and second switch transistor (T2) are NMOS, and the 3rd switching transistor (T3) is PMOS; The grid of described first switching transistor (T1) is connected with sweep trace (SCAN), and its first utmost point is connected with data line (DATA), and its second utmost point is connected with Organic Light Emitting Diode (D1); The grid of described second switch transistor (T2) is connected with control line (EMC), and its first utmost point is connected with second utmost point of Organic Light Emitting Diode (D1) with first switching transistor (T1), and its second utmost point is connected with first utmost point of the 3rd switching transistor (T3); The grid of described the 3rd switching transistor (T3) is connected with control line (EMC), second utmost point of its first utmost point and driving transistors (T2) is connected with an end of electric capacity (C1), its second utmost point is connected with data line (DATA), and its second utmost point is connected with data line (DATA); One end of electric capacity (C1) is connected between first utmost point of second utmost point of driving transistors (T2) and capacitance switch transistor (T3), and the other end is connected common electrical pressure side (Vcom).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010105645781A CN101996581A (en) | 2010-11-29 | 2010-11-29 | Pixel circuit of organic light emitting display |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2010105645781A CN101996581A (en) | 2010-11-29 | 2010-11-29 | Pixel circuit of organic light emitting display |
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| CN101996581A true CN101996581A (en) | 2011-03-30 |
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| CN2010105645781A Pending CN101996581A (en) | 2010-11-29 | 2010-11-29 | Pixel circuit of organic light emitting display |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016000346A1 (en) * | 2014-07-03 | 2016-01-07 | 京东方科技集团股份有限公司 | Pixel circuit and driving method therefor, and display device |
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- 2010-11-29 CN CN2010105645781A patent/CN101996581A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016000346A1 (en) * | 2014-07-03 | 2016-01-07 | 京东方科技集团股份有限公司 | Pixel circuit and driving method therefor, and display device |
| US10204555B2 (en) | 2014-07-03 | 2019-02-12 | Boe Technology Group Co., Ltd. | Pixel circuit and driving method thereof, and display device |
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Application publication date: 20110330 |