CN100380428C - Pixel driving method of current driven active matrix organic light-emitting diode - Google Patents
Pixel driving method of current driven active matrix organic light-emitting diode Download PDFInfo
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- CN100380428C CN100380428C CNB031482481A CN03148248A CN100380428C CN 100380428 C CN100380428 C CN 100380428C CN B031482481 A CNB031482481 A CN B031482481A CN 03148248 A CN03148248 A CN 03148248A CN 100380428 C CN100380428 C CN 100380428C
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Abstract
The present invention discloses a pixel driving method for an active array organic light emitting diode driven by current. Before the data of the pixel of the active array organic light emitting diode is updated, a precharge signal is supplied to a driven current source, and a capacitor can discharge through a discharge path to solve the problem of incorrect picture display because of sufficient discharge when the conversion of picture frames is displayed.
Description
Technical field
The present invention relates to a kind of active-matrix organic light-emitting diode pixel; Be particularly related to a kind of active-matrix organic light-emitting diode pixel driving method of current drives.
Background technology
Along with the prosperity of Information technology, of all kinds as information equipments such as computing machine, mobile phone, PDA(Personal Digital Assistant) and digital cameras, all constantly weed out the old and bring forth the new.In these information equipments, display is being played the part of critical role all the time, and flat-panel screens (FlatPanel Display) little by little receives an acclaim owing to have the characteristic of slimming, lightweight and power saving.
In various flat-panel screens, active-matrix Organic Light Emitting Diode (Active MatrixOrganic Emitting Diode, being called for short AMOLED) visual angle is wide, color contrast is effective because of having for display, frivolous, response speed reaches low cost and other advantages soon, is very suitable for the application as displays such as electronic clock, mobile phone, personal digital assistant and digital cameras.
Please referring to shown in Figure 1, it is a kind of active-matrix organic light-emitting diode pixel synoptic diagram of driven.Show among the figure that this active-matrix organic light-emitting diode pixel comprises: change-over switch thin film transistor (TFT) 110, drive thin film transistors 120, electric capacity 130 and Organic Light Emitting Diode 140.Its display gray scale is determined by the voltage on the data line, when sweep trace scans so far pixel, meeting conducting change-over switch thin film transistor (TFT) 110, the voltage on the data line is sent to the grid of drive thin film transistors 120, obtains grid voltage Vg and show, and the electric current I d of the Organic Light Emitting Diode of flowing through (OLED) generally is shown below to drive the required electric current Organic Light Emitting Diode 140 of flowing through:
Id＝(1/2)k(Vgs-Vth)(Vgs-Vth).........(1)
Yet, because the critical voltage Vth of the drive thin film transistors 120 of different pixels can be different because of the inequality of technology with mobility (mobility), so that under same grayscale voltage, the electric current I d of the Organic Light Emitting Diode 140 of flowing through also can be different, cause picture to show uneven situation.
So, just develop the active-matrix organic light-emitting diode pixel that a kind of current drives.Please referring to shown in Figure 2, it is the active-matrix organic light-emitting diode pixel synoptic diagram of a kind of current drives of known technology.Show among the figure that this active-matrix organic light-emitting diode pixel comprises: the first film transistor 210, second thin film transistor (TFT) 220, the 3rd thin film transistor (TFT) 230, electric capacity 240, drive thin film transistors 250 and Organic Light Emitting Diode 260.During operation, at first via the scan control signal of sweep trace with the conducting the first film transistor 210 and second thin film transistor (TFT) 220, the electric current that current source is provided second thin film transistor (TFT) 220 of flowing through, and to electric capacity 240 chargings, at this moment, the grid voltage of storage can impel the electric current of flow through the first film transistor 210 and the 3rd thin film transistor (TFT) 230 to equal the electric current of current source.Then, when the scan control signal of sweep trace cuts off (SCAN OFF), the previous grid voltage that stores of utilization with controlling and driving thin film transistor (TFT) 250, makes the electric current of the Organic Light Emitting Diode 260 of flowing through equal the electric current of current source, and shows required brightness.
Yet, when the active-matrix organic light-emitting diode pixel of this kind current drives before and after display gray scale changes greatly during picture frames (frame), the grid voltage discharge that but may meet with storage on the electric capacity 240 is too late, causes picture to show incorrect situation.For example, suppose when n picture frame, required current source current is 20 micromicroamperes, thereby on electric capacity 240, store a voltage Vn, but when n+1 picture frame, required current source current is 1 micromicroampere only, so the voltage that stores on the electric capacity 240 must discharge into Vn+1 in the extremely short time, causes the too late situation of discharge.
Summary of the invention
In view of this, the invention provides a kind of active-matrix organic light-emitting diode pixel driving method of current drives, it can be before the Data Update of active-matrix organic light-emitting diode pixel, provide a precharge signal to the current source that drives, electric capacity can be discharged via discharge path, produce with the problem of avoiding discharging too late.
For reaching above-mentioned and other purpose, the invention provides a kind of active-matrix organic light-emitting diode pixel driving method of current drives, this method comprises the following steps: to upgrade the current value of a current source that drives the active-matrix organic light-emitting diode pixel; The conducting current source is to the charge path of an electric capacity of active-matrix organic light-emitting diode pixel; In charge path one very first time interval of conducting current source to the electric capacity of active-matrix organic light-emitting diode pixel, provide a precharge signal to current source, make capacitor discharge; And, in the charge path conduction period of this electric capacity, in second time interval behind this very first time interval, begin and finish charging electric capacity; Cut off the charge path of current source to the electric capacity of active-matrix organic light-emitting diode pixel.
Wherein, the precharge signal that provides can be set at and make capacitor discharge to preset potential value.
By in the above-mentioned explanation as can be known, use the active-matrix organic light-emitting diode pixel driving method of a kind of current drives provided by the present invention, then can be before the Data Update of active-matrix organic light-emitting diode pixel, provide a precharge signal to the current source that drives, electric capacity can be produced with the problem of avoiding discharging too late via discharge path discharge in advance.
For above and other objects of the present invention, feature and advantage can be become apparent, hereinafter special with preferred embodiment, and conjunction with figs., elaborate.
Description of drawings
Fig. 1 is a kind of active-matrix organic light-emitting diode pixel synoptic diagram of driven;
Fig. 2 is a kind of active-matrix organic light-emitting diode pixel synoptic diagram of current drives;
Fig. 3 is the active-matrix organic light-emitting diode pixel driving method process flow diagram of a kind of current drives of preferred embodiment of the present invention;
Fig. 4 is the scan control signal and the precharge signal sequential chart of preferred embodiment of the present invention.
110 change-over switch thin film transistor (TFT)s
120,250 drive thin film transistors
130,240 electric capacity
140,260 Organic Light Emitting Diodes
210 the first film transistors
220 second thin film transistor (TFT)s
230 the 3rd thin film transistor (TFT)s
S310～S340 method step
Embodiment
Please refer to shown in Figure 3ly, it is the active-matrix organic light-emitting diode pixel driving method process flow diagram of a kind of current drives of the preferred embodiment according to the present invention.As previously mentioned, for fear of the active-matrix organic light-emitting diode pixel of this kind current drives before and after display gray scale changes greatly during picture frames (frame), because of the grid voltage of storing discharges too late, cause picture to show incorrect problem, therefore, step S330 in the process flow diagram provides a precharge signal to current source, so that can make electric capacity discharge in advance, its method flow will cooperate the circuit of Fig. 2 to illustrate.
As shown in Figure 2, because the display gray scale of the active-matrix organic light-emitting diode pixel of this kind current drives is to be represented by the size of current of current source, therefore when picture shows, must upgrade the current value (S310) of the current source that drives the active-matrix organic light-emitting diode pixel, to upgrade the video data value of active-matrix organic light-emitting diode pixel.
Afterwards, via the scan control signal Scan-On of sweep trace with the conducting the first film transistor 210 and second thin film transistor (TFT) 220, the just charge path of conducting electric capacity 240 (S320).At this moment, control system also provides a precharge signal Pre-Charge to current source in addition, makes electric capacity 240 can in advance discharge (S330).This step preferably can be set at and make electric capacity 240 be discharged to a preset potential value, is beneficial to finishing of subsequent charge work.
Then, electric current second thin film transistor (TFT) 220 of flowing through that control provides current source, and to electric capacity 240 chargings, so that the grid voltage of storage impels the electric current of flow through the first film transistor 210 and the 3rd thin film transistor (TFT) 230 to equal the electric current of current source, and the scan control signal (SCAN OFF) of cut-out sweep trace, just close the first film transistor 210 and second thin film transistor (TFT) 220, to cut off the charge path (S340) of electric capacity 240, and use previously stored grid voltage, controlling and driving thin film transistor (TFT) 250, make the electric current of the Organic Light Emitting Diode 260 of flowing through equal the electric current of current source, and show required brightness.About the time sequential routine of scan control signal Scan-On and precharge signal Pre-Charge, can be with reference to shown in the sequential chart of figure 4.
The present invention is because of before the Data Update of active-matrix organic light-emitting diode pixel, can provide a precharge signal Pre-Charge to the current source that drives, and makes the electric capacity 240 can be via discharge path discharge in advance, the generation of the too late problem of can avoiding discharging.
Though the present invention with preferred embodiment openly as above, it is not in order to limiting the present invention, anyly is familiar with this operator, and without departing from the spirit and scope of the invention, various changes and the retouching done all belong to protection scope of the present invention.
Claims (2)
1. the active-matrix organic light-emitting diode pixel driving method of a current drives comprises the following steps:
Upgrade the current value of a current source that drives this active-matrix organic light-emitting diode pixel;
This current source of conducting is to the charge path of an electric capacity of this active-matrix organic light-emitting diode pixel;
In charge path one very first time interval of this current source of conducting to this electric capacity of this active-matrix organic light-emitting diode pixel, provide a precharge signal to this current source, make this capacitor discharge;
In the charge path conduction period of this electric capacity, in second time interval behind this very first time interval, begin and finish charging this electric capacity; Cut off the charge path of this current source to this electric capacity of this active-matrix organic light-emitting diode pixel.
2. the active-matrix organic light-emitting diode pixel driving method of current drives according to claim 1, it is characterized in that: this precharge signal can make this capacitor discharge to one preset potential value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031482481A CN100380428C (en) | 2003-06-27 | 2003-06-27 | Pixel driving method of current driven active matrix organic light-emitting diode |
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| Application Number | Priority Date | Filing Date | Title |
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| CNB031482481A CN100380428C (en) | 2003-06-27 | 2003-06-27 | Pixel driving method of current driven active matrix organic light-emitting diode |
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| Publication Number | Publication Date |
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| CN1567415A CN1567415A (en) | 2005-01-19 |
| CN100380428C true CN100380428C (en) | 2008-04-09 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB031482481A Expired - Lifetime CN100380428C (en) | 2003-06-27 | 2003-06-27 | Pixel driving method of current driven active matrix organic light-emitting diode |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105225649A (en) * | 2015-10-27 | 2016-01-06 | 南京中电熊猫液晶显示科技有限公司 | A kind of pixel charging modes of display panels |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5714968A (en) * | 1994-08-09 | 1998-02-03 | Nec Corporation | Current-dependent light-emitting element drive circuit for use in active matrix display device |
| US6229508B1 (en) * | 1997-09-29 | 2001-05-08 | Sarnoff Corporation | Active matrix light emitting diode pixel structure and concomitant method |
| CN1388951A (en) * | 2000-07-07 | 2003-01-01 | 精工爱普生株式会社 | Current sampling circuit for organic electroluminescent display |
| US20030030382A1 (en) * | 2001-08-10 | 2003-02-13 | Semiconductor Energy Laboratory Co., Ltd. | Display device and electronic equipment using the same |
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2003
- 2003-06-27 CN CNB031482481A patent/CN100380428C/en not_active Expired - Lifetime
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5714968A (en) * | 1994-08-09 | 1998-02-03 | Nec Corporation | Current-dependent light-emitting element drive circuit for use in active matrix display device |
| US6229508B1 (en) * | 1997-09-29 | 2001-05-08 | Sarnoff Corporation | Active matrix light emitting diode pixel structure and concomitant method |
| CN1388951A (en) * | 2000-07-07 | 2003-01-01 | 精工爱普生株式会社 | Current sampling circuit for organic electroluminescent display |
| US20030030382A1 (en) * | 2001-08-10 | 2003-02-13 | Semiconductor Energy Laboratory Co., Ltd. | Display device and electronic equipment using the same |
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| CN1567415A (en) | 2005-01-19 |
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