KR20130057595A - Organic light emitting diode display device and method of driving the same - Google Patents

Abstract

PURPOSE: An OLED(Organic Light-Emitting Diode) display device and a driving method thereof are provided to compensate for the threshold voltage and mobility deviation of a driving transistor. CONSTITUTION: An OLED display device(100) includes a display panel(110), a source driver(120), a scan driver(130), and a timing control part(140). The display panel includes multiple scan lines(GL1-GLm), multiple data lines(DL1-DLn), and multiple light-emission control lines(EL1-ELm), which cross each other and define multiple pixel regions(P). A data driver includes a driver IC(Integrated Circuit) supplying a data signal to the display panel. The data driver generates a data signal by using a converted image signal and multiple data control signals received from the timing control part and supplies the generated data signal to the display panel through the data lines. The timing control part generates multiple data signals, etc. and supplies to each driver IC of the data driver. The scan driver generates a scan signal by using a control signal received from the timing control part and supplies the generated scan signal to the display panel through the scan lines.

Description

Organic light emitting diode display and its driving method {ORGANIC LIGHT EMITTING DIODE DISPLAY DEVICE AND METHOD OF DRIVING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode display and a driving method thereof, and more particularly, to an organic light emitting diode display capable of correcting a threshold voltage and mobility variation of a driving transistor to improve luminance unevenness caused by a difference in transistor characteristics. An apparatus and a driving method thereof are provided.

Recently, as the information society develops, the demand for the display field is increasing in various forms, and in response, various flat panel display devices, for example, liquid crystal, which have features such as thinning, light weight, and low power consumption BACKGROUND Liquid crystal display devices, plasma display panel devices, organic light emitting diode display devices, and the like have been studied.

An organic light emitting diode display device is a display device that emits light by using an organic compound that emits red (R), green (G), and blue (B) light on a transparent substrate. OLED panel and driving circuit are included.

Therefore, the organic light emitting diode display does not require a separate light source, unlike a liquid crystal display device.

As a result, there is no need for a backlight unit, so the manufacturing process is simpler than that of a liquid crystal display and the manufacturing cost can be reduced.

In addition, the organic light emitting diode display device has not only an excellent viewing angle and a contrast ratio, but also a direct current low voltage drive, a fast response speed, strong external shock, and a wide temperature range.

In particular, in an active matrix type, a voltage controlling the current applied to the pixel region is charged in a storage capacitor, and the voltage is maintained until the next frame signal is applied. It is driven to maintain the light emitting state while one screen is displayed regardless of the number of gate wirings.

Therefore, in the active matrix system, the same luminance is achieved even when a low current is applied, which has the advantage of low power consumption and large size.

FIG. 1 is a view schematically showing an equivalent circuit of a pixel region of a conventional organic light emitting diode display, and FIG. 2 is a timing diagram showing a plurality of control signals supplied to a conventional organic light emitting diode display.

As shown in FIG. 1, first to fifth transistors T1 to T5, a driving transistor Tdr, a storage capacitor Cst, and a light emitting diode Del are formed in each pixel area P of FIG. 1. .

The first to fifth transistors T1 to T5 and the driving transistor Tdr may be P-type transistors.

The source electrode and the gate electrode of the first transistor T1 are connected to the data line DL and the first scan line GL, respectively, and the drain electrode of the first transistor T1 is one end of the storage capacitor Cst. It is connected to one node N1.

The first transistor T1 is turned on according to the first scan signal S1 supplied through the first scan line GL to apply the data voltage DATA to the first node N1. It serves as a switching transistor.

The source electrode and the gate electrode of the second transistor T2 are respectively connected to the first node N1 and the emission control wiring EL, and the drain electrode of the second transistor T2 is connected to the reference voltage wiring VL. .

The second transistor T2 is turned on according to the emission control signal Em supplied through the emission control line EL to supply the reference voltage Vref to the first node N1. .

That is, the second transistor T2 serves to prevent the data voltage of the driving transistor Tdr from changing due to the leakage current of the transistors during the light emission period.

The source electrode and the gate electrode of the third transistor T3 are respectively connected to the second node N2 and the first scan line GL, which are the other ends of the storage capacitor Cst, and the drain electrode of the third transistor T3 is It is connected to the drain electrode of the driving transistor Tdr.

The source electrode and the gate electrode of the fourth transistor T4 are connected to the drain electrode and the emission control wiring EL of the driving transistor Tdr, respectively, and the drain electrode of the fourth transistor T4 is an anode of the light emitting diode Del. It is connected to the third node N3 which is an electrode.

The third transistor T3 and the fourth transistor T4 serve to sense the characteristics of the driving transistor Tdr.

The source electrode and the gate electrode of the fifth transistor T5 are connected to the reference voltage wiring VL and the second scan wiring SL, respectively, and the drain electrode of the fifth transistor T5 is connected to the third node N3. do.

The fifth transistor T5 prevents light emission of the light emitting diode Del while sensing the characteristics of the driving transistor Tdr.

The source electrode and the gate electrode of the driving transistor Tdr are connected to the high potential voltage ELVDD terminal and the second node N2, respectively, and the drain electrode of the driving transistor Tdr is connected to the drain electrode of the third transistor T3. Connected.

While the driving transistor Tdr is turned on, current flows to the light emitting diode Del to serve as a current source so that the light emitting diode Del emits light.

In this case, the intensity of light emitted by the light emitting diode Del is proportional to the amount of current flowing through the light emitting diode Del, and the amount of current flowing through the light emitting diode Del is applied to the gate electrode of the driving transistor Tdr. It is proportional to the magnitude of the voltage DATA.

As a result, the organic light emitting diode display may display an image by applying different data voltages DATA to each pixel area P to display different gray levels.

The storage capacitor Cst is connected between the first node N1 and the second node N2 and stores the gate node voltage of the driving transistor Tdr.

That is, the storage capacitor Cst maintains the data voltage DATA for one frame to maintain a constant amount of current flowing through the light emitting diode Del and to maintain a constant gray level displayed by the light emitting diode Del. Play a role.

Hereinafter, the operation of the pixel area of the conventional organic light emitting diode display as described above will be described.

As shown in Fig. 2, during the first time t1, the high level first scan signal S1 is applied, the low level second scan signal S2 and the low level light emission control signal Em Are applied respectively.

Accordingly, the fifth transistor T5 is turned on and initializes the third node N3 to the reference voltage Vref. At this time, the second transistor T2 and the fourth transistor T4 are turned on.

Here, the voltage difference between the third node N3 and the ground GND may be equal to or less than the threshold voltage Vth of the light emitting diode Del. As a result, a current through the light emitting diode Del is generated during the first time t1. Does not flow.

During the second time t2, the first scan signal S1 is applied while changing from the high level to the low level, the second scan signal S2 of the low level is applied, and the emission control signal Em is at the low level. It is applied while changing from high level to.

As a result, the first transistor T1 and the third transistor T3 are turned on and are turned on using the off delay time of the fourth transistor T4 and the second node N2 and the third node N3. Is initialized to the reference voltage Vref. In this case, since the fifth transistor T5 maintains a turn-on state, the third node N3 maintains the reference voltage Vref.

Therefore, since the voltage of the third node N3 maintains the reference voltage Vref, a non-light emitting state in which no current flows through the light emitting diode Del is maintained even during the second time t2.

During the third time t3, the low level first scan signal S1, the low level second scan signal S2, and the high level emission control signal Em are applied.

Therefore, the threshold voltage Vth of the driving transistor Tdr is stored in the storage capacitor Cst. In this case, the fourth transistor T4 maintains a turn-off state and the third node N3 maintains a reference voltage Vref.

During the fourth time t4, the emission control signal Em is applied while changing from the high level to the low level, and the first scan signal S1 and the second scan signal S2 change from the low level to the high level. Is approved.

As a result, the second transistor T2 and the fourth transistor T4 are turned on, and the first transistor T1, the third transistor T3, and the fifth transistor T5 are turned off. (Turn-Off), the light emitting diode Del emits light for one frame.

The pixel region of the organic light emitting diode display device is driven while compensating the threshold voltage Vth and the high potential voltage VDD of the driving transistor Tdr through repetition of the first to fourth times t1 to t4.

In this case, the current I _OLED flowing through the light emitting diode Del is defined as in Equation 1.

[Equation 1]

Here, k is a proportional constant that is determined by the structure and physical characteristics of the driving transistor Tdr, and the mobility of the driving transistor Tdr and the channel width W and channel length of the driving transistor Tdr. It can be determined by the ratio (W / L) of (L).

That is, the current I _OLED flowing through the light emitting diode Del in the pixel region of the conventional organic light emitting diode display device is independent of the variation of the threshold voltage Vth and the high potential voltage VDD of the driving transistor Tdr. It may be determined by the data voltage DATA and the reference voltage Vref.

However, in the organic light emitting diode display having such a pixel structure, since the first transistor T1 and the third transistor T3 are driven by the same signal line, the threshold voltage sensing and the data writing of the driving transistor Tdr are performed. Writing will proceed simultaneously.

As a result, when applied to a high-resolution large area panel requiring high-speed driving, there is a problem that the compensating ability is deteriorated due to a lack of threshold voltage sensing time of the driving transistor Tdr.

In addition, there is a problem that luminance unevenness occurs due to the mobility variation because only the compensation of the threshold voltage of the driving transistor Tdr is performed and the correction is not performed according to the mobility variation of the driving transistor Tdr.

The present invention is to solve the above problems, an organic light emitting diode display and a method of driving the organic light emitting diode display that can correct the luminance unevenness caused by the transistor characteristic difference by correcting the threshold voltage and mobility deviation of the driving transistor. It aims to provide.

An organic light emitting diode display for achieving the above object includes: a first transistor connected to a second node, a sensing wiring, and a drain electrode of a driving transistor; A second transistor connected to the data line, the scan line and the first node; A third transistor connected to the first node, the sensing wiring, and a reference voltage wiring; A fourth transistor connected to the drain electrode of the driving transistor, the emission control wiring, and the anode electrode of the light emitting diode; A first capacitor coupled between the first node and the second node; And a second capacitor connected between the first node and the anode electrode of the light emitting diode.

Here, the reference voltage delivered through the reference voltage wiring may be a voltage larger than the data voltage transferred through the data wiring, and may be a high reference voltage or a low reference voltage.

The third transistor may be turned on according to a sensing signal supplied through the sensing wiring to initialize the first node to a high reference voltage.

A method of driving an organic light emitting diode display according to an embodiment of the present invention for achieving the above object, the organic light-emitting comprising a first to fourth transistor, the first and second capacitors, a driving transistor and a light emitting diode. A method of driving a diode display, the method comprising: initializing a first node, one end of the first capacitor, to a high reference voltage while the first transistor and the third transistor are turned on by a sensing signal; Sensing a threshold voltage of the driving transistor while the first transistor and the third transistor are turned on and a low reference voltage is transmitted through a reference voltage wiring; Applying a data voltage to the first node while the second transistor is turned on by a scan signal; And the light emitting diode emits light while the fourth transistor is turned on by the light emission control signal.

In the sensing of the threshold voltage of the driving transistor, the voltage applied to the second node may increase.

The sensing time for sensing the threshold voltage of the driving transistor is preferably longer than one horizontal period.

Also, in the step of applying a data voltage to the first node, the voltage applied to the second node may be reduced by boosting the first capacitor.

In the light emitting diode, the voltage change of the first node caused by the boosting of the first capacitor and the second capacitor is reflected to the second node to increase the voltage applied to the second node. desirable.

In this case, the voltage change amount of the first node may vary according to the data voltage.

As described above, in the organic light emitting diode display according to the present invention, the scan wiring for supplying the scan signal for data writing and the sensing wiring for supplying the sensing signal for sensing the threshold voltage of the driving transistor are separated. As the threshold voltage sensing time increases, the threshold voltage and mobility deviation of the driving transistor may be corrected.

As a result, luminance unevenness caused by difference in transistor characteristics can be improved.

In addition, the luminance variation may be improved by correcting the mobility variation according to the data voltage.

In addition, as the threshold voltage sensing time of the driving transistor increases, luminance uniformity of the high-speed driving / high resolution / large area panel may be improved.

1 is a view schematically showing an equivalent circuit of a pixel area of a conventional organic light emitting diode display.
2 is a timing diagram illustrating a plurality of control signals supplied to a conventional organic light emitting diode display.
3 is a schematic view of an organic light emitting diode display according to the present invention.
4 is a schematic diagram illustrating an equivalent circuit of a pixel area of an organic light emitting diode display according to an exemplary embodiment of the present invention.
5 is a timing diagram schematically illustrating a plurality of control signals supplied to an organic light emitting diode display according to an exemplary embodiment of the present invention, a reference voltage change, and a voltage change of a second node.
FIG. 6 is a view referred to compare a current deviation according to mobility correction of a driving transistor in a conventional organic light emitting diode display and an organic light emitting diode display according to an embodiment of the present invention.
FIG. 7 is a view referred to to compare the correction capability according to the data voltage in the organic light emitting diode display according to the exemplary embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

3 is a view schematically showing an organic light emitting diode display according to the present invention, and FIG. 4 is a view schematically showing an equivalent circuit of a pixel region of an organic light emitting diode display according to an embodiment of the present invention.

3 and 4, the organic light emitting diode display 100 according to the present invention includes a display panel 110, a source driver 120, a scan driver 130, and a source driver for displaying an image. The timing controller 140 may control driving timing of the 120 and the scan driver 130, respectively.

The display panel 110 includes a plurality of scan lines GL1 to GLm and a plurality of data lines DL1 to DLn and a plurality of light emission control lines EL1 to ELm that cross each other to define a plurality of pixel regions P. ) May be included.

In addition, a plurality of sensing lines SL for supplying a control signal for controlling each pixel area P may be formed to be spaced apart in parallel with the plurality of scan lines GL1 to GLm.

Since each pixel area P has the same configuration, hereinafter, for convenience, a plurality of scan wires GL1 to GLm are referred to as scan wires GL, and the first to nth data wires DL1 to DLn are referred to as data wires DL. ), A plurality of light emission control wirings EL1 to ELm will be described as light emission control wirings EL.

Meanwhile, in each pixel area P, first to 54th transistors T1 to T4, a driving transistor Tdr, a first capacitor C1, a second capacitor C2, and a light emitting diode Del may be formed. have.

Here, the first to fourth transistors T1 to T4 and the driving transistor Tdr may be P-type transistors as illustrated, but are not limited thereto, and N-type transistors may be applied.

The source electrode and the gate electrode of the first transistor T1 are respectively connected to the second node N2 and the sensing wiring SL, which are the other ends of the first capacitor C1, and the drain electrode of the first transistor T1 is driven. It is connected to the drain electrode of the transistor Tdr.

The first transistor T1 is turned on according to a sensing signal supplied through the sensing line SL to serve as a switch between the drain node and the gate node of the driving transistor Tdr.

The source electrode and the gate electrode of the second transistor T2 are respectively connected to the data line DL and the scan line GL, and the drain electrode of the second transistor T2 is one end of the first capacitor C1. It is connected to node N1.

The second transistor T2 is turned on according to a scan signal supplied through the scan line GL to serve as a switching transistor for supplying a data voltage Vdata to the first node N1. .

The source electrode and the gate electrode of the third transistor T3 are connected to the first node N1 and the sensing wiring SL, respectively, and the drain electrode of the third transistor T3 is connected to the reference voltage wiring VL.

The third transistor T3 is turned on according to a sensing signal supplied through the sensing line SL to supply a reference voltage to the first node N1.

The source electrode and the gate electrode of the fourth transistor T4 are connected to the drain electrode and the emission control wiring EL of the driving transistor Tdr, respectively, and the drain electrode of the fourth transistor T4 is an anode of the light emitting diode Del. Connected to the electrode.

The fourth transistor T4 is turned on according to the light emission control signal supplied through the light emission control line EL, and thus is connected between the drain node of the driving transistor Tdr and the anode node of the light emitting diode Del. Serves as a switch to control the light emitting timing of the light emitting diode (Del).

The source electrode and the gate electrode of the driving transistor Tdr are connected to the high potential voltage ELVDD terminal and the second node N2, respectively, and the drain electrode of the driving transistor Tdr is connected to the drain electrode of the first transistor T1. Connected.

The driving transistor Tdr controls the amount of current flowing through the light emitting diode Del, and the amount of current flowing through the light emitting diode Del is controlled by the data voltage Vdata applied to the gate electrode of the driving transistor Tdr. Proportional to size.

That is, the organic light emitting diode display 100 may display an image by applying different data voltages to each pixel region P to display different gray levels.

The first capacitor C1 is connected between the first node N1 and the second node N2 and stores the threshold voltage Vth and the data voltage Vdata of the driving transistor Tdr.

The first capacitor C1 maintains the data voltage for one frame to keep the amount of current flowing through the light emitting diode Del constant and to maintain the gray level displayed by the light emitting diode Del. It may be a storage capacitor.

The second capacitor C2 is connected between the first node N1 and the anode electrode of the light emitting diode Del, and the mobility of the driving transistor Tdr depends on the amount of current flowing through the light emitting diode Del during the light emitting period. It is responsible for compensating mobility.

The anode electrode of the light emitting diode Del is connected to the drain electrode of the fourth transistor T4, and the cathode electrode is connected to the low potential voltage ELVSS terminal.

The data driver 120 may include at least one driver IC (not shown) for supplying a data signal to the display panel 110.

The data driver 120 generates a data signal using the converted image signal R / G / B received from the timing controller 140 and a plurality of data control signals, and converts the generated data signal into a data wire ( The display panel 110 is supplied to the display panel 110 through DL.

The timing controller 140 controls a plurality of video signals and a plurality of control signals such as a vertical synchronization signal VSY, a horizontal synchronization signal HSY, a data enable signal DE, and the like from a system such as a graphics card through an interface. Can be delivered.

In addition, the timing controller 140 may generate a plurality of data signals and supply the same to each driver IC of the data driver 120.

The scan driver 130 may generate a scan signal using the control signal received from the timing controller 140, and control the scan driver 130 to supply the generated scan signal to the display panel 110 through the scan line GL.

Hereinafter, the operation of the pixel area of the organic light emitting diode display as described above will be described.

5 is a timing diagram schematically illustrating a plurality of control signals supplied to an organic light emitting diode display according to an exemplary embodiment of the present invention, a reference voltage change, and a voltage change of a second node. A description with reference to FIG.

As shown in Fig. 5, during the first time t1, the emission control signal Em is applied while changing from a low level to a high level, and the sensing signal Sen is applied while changing from a high level to a low level. , A high level scan signal Scan may be applied.

In this case, the reference voltage VRef through the reference voltage line VL may be a high reference voltage VRef_H which is a high level reference voltage.

Accordingly, the first transistor T1 is turned on by the low level sensing signal Sen, and the first node N1 is initialized to the high reference voltage VRef_H.

Meanwhile, when the first transistor T1 and the third transistor T3 are turned on, the driving transistor Tdr is also turned on, but before that, the fourth transistor T4 is turned on. ) Is turned off (Turn-Off) can cut off the current flowing to the light emitting diode (Del).

At this time, the second transistor T2 is in a turn-off state.

In more detail, during the first time t1, the first node N1 is initialized to the high reference voltage VRef_H, and the voltage difference Vgs between the gate electrode and the source electrode of the driving transistor Tdr is changed to the driving transistor (T1). It becomes larger than the threshold voltage Vth of Tdr.

While the third transistor T3 is turned on, sensing the threshold voltage Vth of the driving transistor Tdr at the second node N2 which is the source electrode of the driving transistor Tdr. To start.

During the second time t2, a high level emission control signal Em, a low level sensing signal Sen, and a high level scan signal Scan may be applied, respectively.

In this case, the reference voltage VRef through the reference voltage line VL may be a low reference voltage VRef_L, which is a low level reference voltage VRef, and the second time t2 is greater than one horizontal period 1H. It can be a long time, for example 5H, which is five times one horizontal period 1H.

As a result, the first transistor T1 maintains a turn-on state, the first node N1 receives a low reference voltage VRef_L, and is boosted by boosting the first capacitor C1. The voltage V _N2 applied to the second node N2 may be lowered to 'Vg0-VREF_L-VREF_H' by reflecting the voltage change amount VRef_H-VRef_L of the first node N1.

Here, Vg0 may be a gate terminal voltage of the driving transistor Tdr which is increased instantaneously as the fourth transistor T4 is turned off.

In addition, the threshold voltage Vth of the driving transistor Tdr is sensed at the second node N2 for the second time t2, and the voltage V _N2 applied to the second node N2 as time passes is' It is increased to ELVDD-Vth '.

At this time, the second transistor T2 and the fourth transistor T4 are in a turn-off state.

During the third time t3, a high level emission control signal Em, a low level sensing signal Sen, and a low level scan signal Scan may be applied, respectively.

In this case, the reference voltage VRef through the reference voltage wiring VL may be a low reference voltage VRef_L, which is a low level reference voltage, and the third time t3 is, for example, one horizontal period 1H. Can be.

Therefore, while the second transistor T2 is turned on, the second transistor T2 supplies the data voltage Vdata to the first node N1.

Here, the first transistor T1, the third transistor T3, and the fourth transistor T4 are in a turn-off state.

During the third time t3, the voltage V _N1 applied to the first node N1 becomes the data voltage Vdata, and the voltage change amount of the first node N1 becomes 'VRef_L-Vdata'.

In addition, the voltage V _N2 applied to the second node N2 is reflected by the voltage change amount VRef_L-Vdata of the first node N1 due to the boosting of the first capacitor C1, and thus 'ELVDD-Vth + Vdata-'. VRef_L '.

That is, the voltage V _N2 applied to the second node N2 becomes 'ELVDD-Vth + Vdata-VRef_L' by boosting the first capacitor C1.

During the fourth time t4, the low level emission control signal Em, the high level sensing signal Sen, and the high level scan signal Scan may be applied.

In this case, the reference voltage VRef through the reference voltage line VL may be a high reference voltage VRef_H which is a high level reference voltage VRef.

As a result, the fourth transistor T4 and the driving transistor Tdr are turned on, and the current I _OLED flows through the light emitting diode Del to become a light emitting state.

Here, the first to third transistors T1 to T3 are in a turn-off state.

When the voltage V _N2 applied to the second node N2 becomes 'ELVDD-Vth + Vdata-VRef_L' during the fourth time t4, a current flows in the driving transistor Tdr, whereby the anode of the light emitting diode Del Voltage changes occur at the nodes.

The voltage change at the anode node of the light emitting diode Del generates a voltage change ΔV at the first node N1 by boosting the second capacitor C2.

As a result, the voltage V _N2 applied to the second node N2 becomes 'ELVDD-Vth + Vdata-VRef_L + ΔV' by reflecting the voltage change amount? V of the first node N1 and driving transistor Tdr. The mobility of is compensated.

In this case, the current I _OLED flowing through the light emitting diode Del may be defined as in Equation 2.

&Quot; (2) "

Here, k is a proportional constant that is determined by the structure and physical characteristics of the driving transistor Tdr, and the mobility of the driving transistor Tdr and the channel width W and channel length of the driving transistor Tdr. It can be determined by the ratio (W / L) of (L).

Vsg denotes a voltage between a source node and a gate node of the driving transistor Tdr, and Vth denotes a threshold voltage of the driving transistor Tdr.

Therefore, since Vsg is Vs-Vg, it becomes' ELVDD- (ELVDD-Vth + Vdata-VRef_L + ΔV) 'and' ELVDD 'is erased, and (Vsg-Vth) is' (Vth-Vdata + VRef_L-ΔV) -Vth 'Vth' is erased. (Vs: ELVDD, Vg: ELVDD-Vth + Vdata-VRef_L + ΔV)

Thus, the current I _OLED flowing through the light emitting diode Del is not affected by the change of the high potential voltage ELVDD and the threshold voltage Vth of the driving transistor Tdr.

In addition, the amount of current flowing to the light emitting diode Del varies according to the data voltage Vdata applied to each pixel region P input to the current I _OLED flowing through the light emitting diode Del, and the light emitting diode Del As the amount of current flowing in the V1 varies, the voltage change ΔV also changes at the first node N1, and thus has different mobility correction capability according to the data voltage Vdata.

As a result, the current I _OLED flowing through the light emitting diode Del during the fourth time t4 is independent of the high potential voltage ELVDD and the threshold voltage Vth of the driving transistor Tdr, and the data voltage Vdata and It may be determined by the row reference voltage VRef_L.

In the conventional organic light emitting diode display device, since the first transistor (T1 in FIG. 1) and the third transistor (T3 in FIG. 1) are driven by the same signal line, the threshold voltage sensing and data writing of the driving transistor Tdr are performed. (Writing) will proceed simultaneously.

As a result, when applied to a high-resolution large area panel requiring high-speed driving, there is a problem that the compensating ability is deteriorated due to a lack of threshold voltage sensing time of the driving transistor Tdr.

In addition, there is a problem that luminance unevenness occurs due to the mobility variation because only the threshold voltage Vth of the driving transistor Tdr is compensated and the correction is not performed according to the mobility variation of the driving transistor Tdr.

However, in the organic light emitting diode display according to the present invention, the sensing line SL for supplying a sensing signal for sensing the scan line GL for supplying the scan signal Scan and the threshold voltage Vth of the driving transistor Tdr. As a result of increasing the threshold voltage sensing time of the driving transistor Tdr, the threshold voltage Vth and mobility deviation of the driving transistor Tdr may be corrected.

As a result, luminance unevenness caused by difference in transistor characteristics can be improved.

In addition, since the voltage change ΔV varies at the first node N1 according to the data voltage Vdata, the luminance variation may be corrected by correcting the mobility variation according to the data voltage Vdata.

In addition, in the organic light emitting diode display according to the present invention, since the threshold voltage sensing time of the driving transistor Tdr is sufficient, luminance uniformity can be improved even when applied to a high-speed driving / high resolution / large area panel panel. .

FIG. 6 is a view referred to compare a current deviation according to mobility correction of a driving transistor in a conventional organic light emitting diode display and an organic light emitting diode display according to an embodiment of the present invention, and FIG. In the organic light emitting diode display according to an example, the drawings are referred to for comparing the correction capability according to the data voltage.

When Δμ (%) is -10 to 10 in the organic light emitting diode display, as shown in FIG. 6, the error (%) in the conventional organic light emitting diode display according to the mobility deviation Δμ is determined by the present invention. The deviation is larger than the error (%) in the organic light emitting diode display device.

For example, the error (%) in the conventional organic light emitting diode display according to the mobility deviation (Δμ) is about -8 to 7.5, and in the organic light emitting diode display of the present invention according to the mobility deviation (Δμ) Error (%) of about -5 to 5.

Therefore, in the organic light emitting diode display device of the present invention, it can be seen that the deviation of error (%) is reduced and the mobility deviation is corrected.

As a result, in the organic light emitting diode display device of the present invention, luminance unevenness caused by difference in transistor characteristics can be improved.

In the case of Δμ (%) of -10 to 10 in the organic light emitting diode display, as shown in FIG. 7, the error (%) according to the data voltage (gray level) depends on the gray level (Low_gray, Middle_gray, High_gray). Different.

For example, Error (%) is about -6 to 5 in the case of the middle gray level (Middle_gray), and Error (%) is about -4 to 5 in the case of the high gray level (High_gray).

In other words, in the organic light emitting diode display of the present invention, the amount of current flowing to the light emitting diode is changed according to the data voltage, and the voltage change ΔV is also changed at the first node. You have the ability.

Accordingly, the organic light emitting diode display according to the present invention has different mobility correction capability according to the data voltage, and as a result, the luminance variation can be corrected by correcting the mobility variation according to the data voltage. .

The embodiments of the present invention as described above are merely illustrative, and those skilled in the art can make modifications without departing from the gist of the present invention. Accordingly, the protection scope of the present invention includes modifications of the present invention within the scope of the appended claims and equivalents thereof.

100: organic light emitting diode display 110: display panel
120: source driver 130: scan driver
140: timing controller
Tdr: driving transistor Del: light emitting diode

Claims (10)

A first transistor connected to the second node, the sensing wiring and the drain electrode of the driving transistor;
A second transistor connected to the data line, the scan line and the first node;
A third transistor connected to the first node, the sensing wiring, and a reference voltage wiring;
A fourth transistor connected to the drain electrode of the driving transistor, the emission control wiring, and the anode electrode of the light emitting diode;
A first capacitor coupled between the first node and the second node;
And a second capacitor connected between the first node and the anode electrode of the light emitting diode.
The method of claim 1,
And a reference voltage transmitted through the reference voltage line is greater than a data voltage transmitted through the data line.
The method of claim 1,
And the reference voltage transmitted through the reference voltage wiring is a high reference voltage or a low reference voltage.
The method of claim 3,
The third transistor,
And turn on the first signal according to the sensing signal supplied through the sensing wiring to initialize the first node to a high reference voltage.
A driving method of an organic light emitting diode display device comprising first to fourth transistors, first and second capacitors, a driving transistor, and a light emitting diode,
Initializing a first node, one end of the first capacitor, to a high reference voltage while the first transistor and the third transistor are turned on by a sensing signal;
Sensing a threshold voltage of the driving transistor while the first transistor and the third transistor are turned on and a low reference voltage is transmitted through a reference voltage wiring;
Applying a data voltage to the first node while the second transistor is turned on by a scan signal;
The light emitting diode emits light while the fourth transistor is turned on by a light emitting control signal
Method of driving an organic light emitting diode display device comprising a.
The method of claim 5,
In the sensing of the threshold voltage of the driving transistor,
And a voltage applied to the second node is increased.
The method according to claim 6,
And a sensing time for sensing the threshold voltage of the driving transistor is longer than one horizontal period.
The method of claim 5,
In the step of applying a data voltage to the first node,
And a voltage applied to the second node is reduced by boosting the first capacitor.
The method of claim 5,
In the step of emitting the light emitting diode,
A method of driving an organic light emitting diode display device, characterized in that the voltage change of the first node caused by boosting of the first capacitor and the second capacitor is reflected to the second node to increase the voltage applied to the second node. .
10. The method of claim 9,
The method of driving an organic light emitting diode display device, wherein the voltage change amount of the first node varies according to the data voltage.

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