KR102167142B1 - Organic light emitting display - Google Patents

Abstract

The present invention relates to an organic light-emitting display device capable of sensing a threshold voltage of a transistor excluding a body effect component, and the organic light-emitting display device according to the present invention generates first sensing data by sensing a signal flowing through a driving transistor. And sensing a signal flowing through a sensing transistor including a body terminal connected to the source terminal of the driving transistor at least twice to generate second sensing data, and first and second sensing data based on the first and second sensing data 2 Generate pixel data to which the compensation value is applied.

Description

Organic light emitting display device {ORGANIC LIGHT EMITTING DISPLAY}

The present invention relates to an organic light-emitting display device, and more particularly, to an organic light-emitting display device capable of sensing a threshold voltage of a transistor excluding a body effect component.

A video display device that embodies a variety of information on a screen is a core technology in the information and communication era, and is developing in a direction of thinner, lighter, portable, and high-performance. Accordingly, as a flat panel display device capable of reducing the weight and volume, which is a disadvantage of a cathode ray tube (CRT), an organic light emitting display device that displays an image by controlling the amount of light emitted from an organic light emitting layer is in the spotlight.

In the organic light emitting diode display, a plurality of pixels are arranged in a matrix to display an image. Here, each pixel includes a light-emitting element and a pixel driving circuit including a plurality of transistors that independently drive the light-emitting element.

Conventional transistors are generally composed of three terminals having source, gate, and drain terminals, but recently, a transistor composed of four terminals further having a body terminal has been proposed. However, a body effect phenomenon occurs in which the threshold voltage of the transistor varies according to the voltage applied to the body terminal. In addition, a body effect phenomenon occurs in which the threshold voltage of the transistor is fluctuated by a thickness difference between the body terminal of the transistor and the buffer layer positioned between the active layer. In this case, in an external compensation structure in which the threshold voltage of the transistor is sensed and the threshold voltage of the transistor is compensated based on the sensed value, since the body effect component is included in the sensing value, accurate sensing is difficult.

The present invention is to solve the above problem, and the present invention is to provide an organic light emitting diode display capable of sensing a threshold voltage of a transistor excluding a body effect component.

In order to achieve the above object, the organic light emitting diode display according to the present invention generates first sensing data by sensing a signal flowing through a driving transistor, and through a sensing transistor including a body terminal connected to a source terminal of the driving transistor. The flowing signal is sensed at least twice to generate second sensing data, and pixel data to which first and second compensation values based on the first and second sensing data are applied is generated.

In the organic light emitting diode display according to the present invention, in a structure in which the body terminal of the sensing transistor is connected to the source terminal of the driving transistor, the threshold voltage of the sensing transistor is changed through at least two sensing modes in which the level of the high potential voltage VDD is different. By extracting the variable body effect component, the pure threshold voltage of the sensing transistor Tr_Se from which the body effect component has been removed can be accurately generated. Accordingly, in the present invention, an error in the sensing value of the sensing transistor due to the body effect component can be improved, compensation for degradation and detection of defects caused by the sensing transistor are possible through accurate sensing of the threshold voltage of the sensing transistor. This is improved.

1 is a block diagram illustrating an organic light emitting display device according to the present invention.
FIG. 2 is a diagram for describing a pixel driving circuit of the light emitting display panel shown in FIG. 1.
3 is a cross-sectional view illustrating each of a sensing transistor, a driving transistor, and a switching transistor shown in FIG. 2.
FIG. 4 is a block diagram illustrating in detail the data driver shown in FIG. 1.
FIG. 5 is a graph showing a relationship between a voltage Vbs between a body-source terminal of the sensing transistor illustrated in FIG. 2 and a variation of a threshold voltage due to a body effect component.
6 is a block diagram illustrating a timing controller illustrated in FIG. 1.
7 is a flowchart illustrating an external compensation method of an organic light emitting diode display according to the present invention.
8 is a driving waveform diagram in a sensing mode of an organic light emitting diode display according to the present invention.
9A and 9B are diagrams illustrating a threshold voltage map and a histogram of a threshold voltage magnitude of a sensing transistor sensed according to the prior art and according to the present invention.

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

1 is a block diagram illustrating an organic light emitting display device according to the present invention.

The OLED display illustrated in FIG. 1 includes a power supply unit 110, a data driver 104, a panel driver including a scan driver 106 and a timing controller 108, and a light emitting display panel 102.

The light emitting display panel 102 includes a plurality of pixels P arranged in a matrix form.

As shown in FIG. 2, each of the pixels P includes a light emitting element OLED and a pixel driving circuit including a plurality of transistors that drive the light emitting element OLED. The pixel driving circuit includes a driving transistor Tr_D, a switching transistor Tr_Sw, a sensing transistor Tr_Se, and a storage capacitor Cst.

The switching transistor Tr_Sw has a gate terminal G connected to the scan line SL of each pixel, a source terminal S connected to the data line DL, and a first terminal of the storage capacitor Cst. A drain terminal (D) is connected to one node (n1), and a body terminal (B) is connected to a second node (n2). Accordingly, the switching transistor Tr_Sw supplies the data voltage Vdata from the data line DL to the first node n1 in response to the first gate voltage from the scan line SL of each pixel.

The sensing transistor Tr_Se has a gate terminal G connected to the sensing control line SSL of each pixel, a drain terminal D connected to the second node n2, and a source terminal ( S) is connected, and the body terminal B is connected to the second node n2. Accordingly, the sensing transistor Tr_Se supplies the precharging voltage from the reference line RL to the second node n2 during the initialization period in response to the second gate voltage from the sensing control line SSL, and the sensing period During the saturation operation, the voltage of the second node n2 is supplied to the reference line RL.

In the driving transistor Tr_D, a gate terminal G is connected to a first node n1, a drain terminal D is connected to a high potential voltage source VDD, and a source terminal is connected to the anode electrode of the light emitting element OLED. S) is connected, and the body terminal B is connected to the second node n2. Accordingly, the driving transistor Tr_D adjusts the amount of current flowing through the light emitting device OLED according to its own drain-gate voltage, that is, a voltage applied between the high potential voltage source VDD and the first node n1.

Each of the switching transistor Tr_Sw, the sensing transistor Tr_Se, and the driving transistor Tr_D includes a body terminal B connected to the second node n2. The body terminal B is formed of an opaque conductive material on the first buffer layer BUF1 formed on the substrate 101 as shown in FIG. 3. In addition, the body terminal B is formed to overlap the active layer ACT of each transistor Tr_Sw, Tr_Se, Tr_D with the second buffer layer BUF2 interposed therebetween, so that external light is incident on the active layer ACT. Prevent it. The body terminal B is formed at the same time as the active layer ACT and the second buffer layer BUF2 by using a halftone mask or a diffraction mask to reduce a mask. Accordingly, the body terminals B of each of the switching transistor Tr_Sw, the sensing transistor Tr_Se, and the driving transistor Tr_D are formed to be integrated on the first buffer layer BUF1.

The storage capacitor Cst has a first terminal connected to the first node n1 and a second terminal connected to the second node n2. The storage capacitor Cst charges a voltage difference between voltages supplied to each of the first and second nodes n1 and n2 and supplies the voltage as the driving voltage Vgs of the driving transistor Tr_D.

The light emitting device OLED emits light according to a driving current supplied through the driving transistor Tr_D. To this end, the light emitting element OLED is an anode electrode connected to the second node n2, which is a source terminal of the driving transistor Tr_D, and a cathode electrode connected to a low potential voltage source VSS lower than the high potential voltage source VDD. And an organic light-emitting layer formed between the anode electrode and the cathode electrode.

The panel driving unit includes a timing control unit 108, a power supply unit 110, a data driving unit 104, and a scan driving unit 106.

The power supply unit 110 supplies high potential voltages VDD1 and VDD2 of different levels to the drain terminal of the driving transistor Tr_D during at least two sensing periods of the sensing transistor Tr_Se.

The scan driver 106 applies a high or low first gate voltage to the scan line SL formed on the light emitting display panel 102 in response to a scan control signal from the timing controller 108 and sensing control lines ( SSL) is supplied with a high or low second gate voltage. In this case, when sensing the sensing transistor Tr_Se, the scan driver 106 applies a first gate voltage to the scan line SL so that the switching transistor (Tr_Sw) performs linear operation, and the sensing transistor Tr_se saturates. The second gate voltage to enable the voltage is supplied to the sensing control line SSL.

In the display mode, the data driver 104 converts digital compensation data DATA' into an analog data voltage using a control signal and a gamma voltage from the timing controller 108 and converts the changed analog data voltage to a data line. Supply to (DL).

In addition, the data driver 104 converts the analog sensing value sensed through the reference line RL in the sensing mode into digital sensing data SData and supplies it to the timing controller 108. To this end, the data driver 104 includes first and second sensing units 112 and 114 as shown in FIG. 4.

The first sensing unit 112 senses the threshold voltage of the driving transistor Tr_D through a sensing value Vsd supplied through the reference line RL in the sensing mode of the driving transistor Tr_D, and senses the sensed driving transistor. The threshold voltage of (Tr_D) is generated as first sensing data SData1, which is a digital signal, and is supplied to the timing controller 108.

The second sensing unit 114 senses through a difference between the first and second sensing values Vse1 and Vse2 supplied through the reference line RL in the first and second sensing modes of the sensing transistor Tr_Se. The body effect component in which the threshold voltage of the sensing transistor Tr_Se varies according to the voltage between the body terminal and the source terminal of the transistor Tr_Se is extracted, and the body effect component is removed from the sensing transistor Tr_Se. The pure threshold voltage is sensed, and the sensed threshold voltage of the sensing transistor Tr_Se is generated as second sensing data SData2, which is a digital signal, and supplied to the timing controller 108.

Specifically, the first and second sensing values Vse1 and Vse2 of the sensing transistor Tr_Se sensed through the reference line RL are supplied to the second sensing unit 114.

At this time, the first sensing value Vse1 of the sensing transistor Tr_Se is the driving transistor Tr_D and the switching transistor by supplying the high potential voltage VDD1 of the first level to the drain terminal D of the driving transistor Tr_D. It is generated by the linear operation of (Tr_Sw) and the saturation operation of the sensing transistor Tr_Se.

In addition, the second sensing value Vse2 of the sensing transistor Tr_Se is obtained by supplying a high potential voltage VDD2 of a second level different from the first level to the drain terminal D of the driving transistor Tr_D to the driving transistor Tr_D. ) And the switching transistor Tr_Sw linearly operate, and the sensing transistor Tr_se saturates.

Here, the first and second sensing values Vse1 and Vse2 of the sensing transistor Tr_Se are as in Equation 1 below. In Equation 1, Vgh is the second gate voltage in the high state supplied to the gate terminal G of the sensing transistor Tr_Se, Vth is the pure threshold voltage of the sensing transistor Tr_Se, and ΔVth1@BE is the sensing transistor. In the first sensing mode of (Tr_Se), the variation of the threshold voltage of the sensing transistor Tr_Se by the body effect, ΔVth2@BE is the sensing transistor by the body effect in the second sensing mode of the sensing transistor Tr_Se ( It means the variation of the threshold voltage of Tr_Se).

[Equation 1]

At this time, in the first and second sensing modes, the threshold voltage variation (ΔVth1@BE, ΔVth2@BE) of the sensing transistor Tr_Se due to the body effect is the sensing transistor Tr_Se as shown in FIG. 5 and Equation 2 The body-source voltage (Vbs) supplied between the body terminal (B) and the source terminal (S) of form a reduction function relationship. That is, when a positive voltage is applied to the body terminal B, the threshold voltage of the sensing transistor Tr_Se due to the body effect is shifted in the negative direction.

[Equation 2]

5 and Equation 2, Y is the threshold voltage variation (ΔVth@BE) of the sensing transistor Tr_Se due to the body effect, a is the slope, and X is the body between the body of the sensing transistor Tr_Se and the source terminal. -Source voltage (Vbs), b denotes the initial threshold voltage (Vth) of the sensing transistor (Tr_Se) when the body-source voltage (Vbs) of the sensing transistor (Tr_Se) is 0V. Here, b is defined as 0 for convenience in calculation, and the slope a is equal to Equation 3.

[Equation 3]

Substituting the slope a generated through Equation 3 into Equation 2, a threshold voltage variation (ΔVth@BE) of the sensing transistor Tr_Se due to the body effect can be generated, and the body-source voltage of the sensing transistor It is possible to extract a trend line (eg, a reduction function in FIG. 5) of the threshold voltage variation (ΔVth@BE) of the sensing transistor Tr_Se by the body effect of the corresponding body effect. By substituting the threshold voltage variation (ΔVth@BE) of the sensing transistor Tr_Se due to the body effect into Equation 1, a pure threshold voltage of the sensing transistor Tr_Se may be generated.

In this way, a pure threshold voltage of the sensing transistor Tr_Se in which the body effect component is filtered may be generated through Equations 1 to 3 above.

For example, in the first sensing mode, a first gate voltage Vgh1 in a high state of 24V is applied to the gate terminal G of the switching transistor Tr_Sw, a data voltage of 16V is applied to the data line DL, and the driving transistor A high potential voltage of 12V is applied to the drain terminal (D) of (Tr_D), a second gate voltage (Vgh2) in a high state of 6V is applied to the gate terminal (G) of the sensing transistor (Tr_Se), and 0V to the reference line (RL). Supply the reference voltage of.

In this case, the driving transistor Tr_D and the switching transistor Tr_Sw operate linearly, and the sensing transistor Tr_Se performs a saturation operation. Accordingly, in the first sensing mode, the body terminal B of the sensing transistor Tr_Se has an equal potential with the drain terminal D of the driving transistor Tr_D, so that 12V, which is the high potential voltage VDD1 of the first level, is supplied. And, since the source terminal S of the sensing transistor Tr_Se is connected to the reference line RL, 0V is supplied. Accordingly, in the first sensing mode, the first body-source voltage Vbs1 of the sensing transistor Tr_Se is 12V, and the first sensing value of the sensing transistor Tr_Se, that is, the voltage of the third node n3, is 11.46V. Is sensed.

In the second sensing mode, the first gate voltage Vgh1 in the high state of 24V is applied to the gate terminal G of the switching transistor Tr_Sw, the data voltage of 16V is applied to the data line DL, and the driving transistor Tr_D A high potential voltage of 8V is supplied to the drain terminal D of ), a second gate voltage Vgh2 in a high state of 6V is supplied to the gate electrode of the sensing transistor Tr_Se, and a reference voltage of 0V is supplied to the reference line RL. do. In this case, the driving transistor Tr_D and the switching transistor Tr_Sw operate linearly, and the sensing transistor Tr_Se performs a saturation operation. The body terminal of the sensing transistor Tr_Se has an equipotential with the drain terminal D of the driving transistor Tr_D, so that 8V, which is the high potential voltage VDD2 of the second level, is supplied, and the source terminal of the sensing transistor Tr_Se ( Since S) is connected to the reference line RL, 0V is supplied. Accordingly, in the second sensing mode, the second body-source voltage Vbs2 of the sensing transistor Tr_Se is 8V, and the first sensing value of the sensing transistor Tr_Se, that is, the voltage of the third node n3, is 9.74V. Is sensed.

Using these values, the slope a described in Equation 3 is calculated as in Equation 4.

[Equation 4]

Therefore, when the slope a is substituted into Equation 2, the threshold of the sensing transistor Tr_Se by the body effect in the first sensing mode in which the high potential voltage (= first body-source voltage, Vbs) of the first level is 12V Voltage fluctuation (Y=△Vth1@BE) is -0.43×12V, and in the second sensing mode in which the high potential voltage of the second level is 8V, the threshold voltage fluctuation of the sensing transistor (Tr_Se) due to the body effect (Y=△ Vth2@BE) is -0.43×8V.

By substituting the threshold voltage variation into Equation 1, the pure threshold voltage Vth of the sensing transistor Tr_Se can be obtained during the first and second sensing periods as shown in Equation 5.

[Equation 5]

Vth=Vgh-Vse1-(△Vth1@BE)=6-11.46-(-0.43×12)=-0.3V

Vth=Vgh-Vse2-(△Vth2@BE)=6-9.74-(-0.43×8)=-0.3V

In this way, the second sensing unit 114 uses the difference between the first and second sensing values Vse1 and Vse2 generated through at least two sensing modes in which the level of the high potential voltage VDD is different. It is possible to extract a trend line (eg, the reduction function of FIG. 5) of the threshold voltage variation (ΔVth@BE) of the sensing transistor Tr_Se with respect to the voltage between the body-source terminal of. Through this trend line, the second sensing unit 114 generates a pure threshold voltage of the sensing transistor Tr_Se from which the body effect component has been removed, and converts the generated threshold voltage of the sensing transistor to the second sensing data SData2 which is a digital signal. It is generated and supplied to the timing control unit 108.

The timing control unit 108 includes a control signal generation unit 126, a compensation unit 122, and a memory 124 as shown in FIG. 6.

The control signal generator 126 generates a gate control signal and a data control signal for controlling driving timings of the gate driver 106 and the data driver 104 based on a synchronization signal input from the outside. The generated gate control signal is supplied to the gate driver 106 and the data control signal is supplied to the data driver 104.

The memory 124 includes first and second compensation values for compensating the threshold voltages of the driving transistor Tr_D and the sensing transistor Tr_Se based on the first and second sensing data SData from the data driver 104 (φ,θ) is stored. Here, the first compensation value φ is a value obtained by compensating for a deviation of the data voltage for a change in the first sensing data SData1 by sensing the threshold voltage of the driving transistor Tr_D through a pre-simulation process. The second compensation value θ is a value obtained by compensating for a deviation of the data voltage for a change in the second sensing data SData2 by sensing the threshold voltage of the sensing transistor Tr_Se through a pre-simulation process.

The first and second compensation values φ and θ stored in the memory 124 are updated by sensing the characteristics of each sub-pixel again through a sensing mode every desired driving time after product shipment. For example, the sensing mode is executed every at least one desired driving time including a boot time at power-on, an end time at power-off, a blanking period of each frame, and the first and second compensation values φ ,θ) can be updated.

The compensation unit 122 compensates the pixel data DATA using the first and second compensation values φ and θ stored in the memory 124 to generate digital compensation data DATA′, and then digitally compensates the pixel data DATA. The data DATA' is supplied to the data driver 104.

7 is a flowchart illustrating an external compensation method of an organic light emitting diode display according to the present invention.

First, first sensing data SData1 is generated by sensing a threshold voltage of the driving transistor Tr_D of each of the pixels (step S1), and characteristics of the driving transistor Tr_D corresponding to the first sensing data SData1 Is stored in the memory (step S2), and the memory calculates and stores the first compensation value φ of the driving transistor Tr_D based on the stored sensing data (step S3).

The second sensing data SData2 is generated by sensing a signal flowing through the sensing transistor Tr_Se of each of the pixels at least twice (step S4), and a sensing transistor Tr_Se corresponding to the second sensing data SData2 ) In a memory (step S5), and the memory calculates and stores the second compensation value θ of the sensing transistor Tr_Se corresponding to the sensed value based on the stored sensing value (step S6).

Then, the compensation unit adds the first compensation value φ of the driving transistor Tr_D stored in the memory and the second compensation value θ of the sensing transistor Tr_Se to the pixel data DATA to obtain compensation data DATA′. ) Is generated (step S7).

8 is a driving waveform diagram in a sensing mode of an organic light emitting diode display according to the present invention.

As shown in FIG. 8, in the organic light emitting diode display according to the present invention, an initialization period T1 in a sensing mode, a sensing period T2 of the driving transistor Tr_D, and a sensing period T3 of at least two times of the sensing transistor Tr_Se. ,T4). Here, the initialization period T1 shown in FIG. 8, the sensing period T2 of the driving transistor Tr_D, and the first and second sensing periods T3 and T4 of the sensing transistor Tr_Se shown in FIG. It will be described in detail in conjunction with the driving circuit.

First, in the initialization period T1, a first gate voltage Vgh1 in a high state is supplied to the scan line SL, and a second gate voltage Vgh2 in a high state is supplied to the sensing control line SSL. A data voltage Vdata corresponding to a set voltage level for sensing the threshold voltage of the driving transistor Tr_D is supplied to the line DL, and a precharging voltage Vpre is supplied to the reference line RL.

The data voltage Vdata from the data line DL through the switching transistor Tr_Sw turned on in response to the first gate voltage Vgh1 in the high state is the first node n1, that is, the gate of the driving transistor Tr_D. It is supplied to the terminal (G). In addition, the precharging voltage Vpre from the reference line RL through the sensing transistor Tr_Se turned on in response to the second gate voltage Vgh2 in the high state is the second node n2, that is, the driving transistor Tr_D ) Is supplied to the source terminal (S).

Accordingly, during the initialization period, the source electrode and the reference line RL of the driving transistor Tr_D are initialized to the precharging voltage. In this case, a difference voltage between the data voltage Vdata and the precharging voltage Vpre is stored in the storage capacitor Cst.

Then, in the first period t21 of the sensing period T2 of the driving transistor Tr_D, the first gate voltage supplied to the switching transistor Tr_Sw through the scan line SL maintains a high state (Vgh1). , The second gate voltage supplied to the sensing transistor Tr_Se through the sensing control line SSL maintains a high state (Vgh2).

The data voltage Vdata is supplied to the first node, that is, the gate electrode G of the driving transistor Tr_D, through the switching transistor Tr_Sw that maintains the turned-on state in response to the first gate voltage Vgh1 in the high state. . At this time, the reference line RL is in a floating state.

Accordingly, the driving transistor Tr_D performs a saturation operation (Vgs-Vth<Vds) by the data voltage supplied to the gate electrode, and the sensing transistor Tr_Se performs a linear operation (Vgs-Vth>Vds). The difference voltage (Vdata-Vth) between the data voltage supplied to the gate electrode of the driving transistor Tr_D and the threshold voltage of the driving transistor Tr_D is in the floating reference line RL by the driving transistor Tr_D in saturation operation. Is charged.

Then, in the second period t22 of the sensing period T2 of the driving transistor Tr_D, the first gate voltage supplied to the switching transistor Tr_Sw through the scan line SL maintains a high state Vgh1. , The second gate voltage Vgl2 in the low state is supplied to the sensing control line SSL, and the reference line RL is connected to the first sensing unit 112. Accordingly, the first sensing unit 112 senses the voltage (=Vdata-Vth) of the reference line RL to extract the threshold voltage of the driving transistor Tr_D, and calculates the extracted threshold voltage of the driving transistor Tr_D. Converted to analog digital to generate first sensing data SData1.

Then, in the first period t31 of the first sensing period T3 of the sensing transistor Tr_D, the first gate voltage supplied to the switching transistor Tr_Sw through the scan line SL is in a high state Vgh1. And the second gate voltage supplied to the sensing transistor Tr_Se through the sensing control line SSL maintains a high state (Vgh2).

The data voltage Vdata is supplied to the first node, that is, the gate electrode of the driving transistor Tr_D, through the switching transistor Tr_Sw maintaining the turned-on state in response to the first gate voltage Vgh1 in the high state. At this time, the high potential voltage VDD1 of the first level is supplied to the drain terminal of the driving transistor Tr_D, and the reference voltage of 0V is supplied to the reference line RL.

Accordingly, the driving transistor Tr_D performs a linear operation (Vgs-Vth>Vds) by the data voltage supplied to the gate terminal and the high potential voltage of the first level supplied to the drain terminal, and the sensing transistor Tr_Se is Saturation operation (Vgs-Vth<Vds) by the second gate voltage of the high state supplied to the terminal, the high potential voltage of the first level supplied to the drain terminal, and the reference voltage of 0V supplied to the reference line RL Is done. The reference line RL connected to the sensing transistor Tr_D in saturation operation has a difference voltage Vgh- between the second gate voltage Vgh in the high state and the threshold voltage of the sensing transistor supplied to the gate electrode of the sensing transistor Tr_D. Vth) as well as the threshold voltage fluctuation component (ΔVth@BE) caused by the body effect is charged (=Vgh-(Vth+ΔVth1@BE)).

Then, in the second period t32 of the first sensing period T3 of the sensing transistor Tr_Se, the first gate voltage supplied to the switching transistor Tr_Sw through the scan line SL enters a high state (Vgh1). And the second gate voltage Vgl2 in a low state is supplied to the sensing control line SSL, and the reference line RL is connected to the first sensing unit 112. Accordingly, the first sensing unit 112 senses and stores a first sensing value that is the voltage (=Vgh-(Vth+ΔVth1@BE)) of the reference line RL.

Then, in the first and second periods t41 and t42 of the second sensing period T4 of the sensing transistor Tr_D, the first and second periods of the first sensing period T3 of the sensing transistor Tr_D ( In contrast to t31 and t32, the same voltage is supplied to the drain terminal of the driving transistor Tr_D, except that the high potential voltage VDD2 of the second level is supplied. Accordingly, the second sensing unit 114 senses the second sensing value Vse2 that is the voltage (=Vgh-(Vth+ΔVth2@BE)) of the reference line RL. Then, the second sensing unit 114 extracts the threshold voltage of the sensing transistor Tr_D through the difference between the first and second sensing values Vse1 and Vse2, and calculates the extracted threshold voltage of the sensing transistor Tr_Se. Converted to analog digital to generate second sensing data SData2.

Meanwhile, in the present invention, a case in which the same pixel is used for sensing of the driving transistor and sensing of the sensing transistor has been described with reference to FIG. 8. In addition, sensing of the driving transistor and sensing of the sensing transistor may be performed using different pixels. In addition, in the present invention, sensing the sensing transistor twice has been described using FIG. 8 as an example, but accuracy may be improved by increasing the number of sensing times of the sensing transistor to three or more times.

9A and 9B are diagrams illustrating a threshold voltage map and a histogram of a threshold voltage magnitude of a sensing transistor sensed according to the prior art and according to the present invention.

As shown in FIG. 9A, the average value of the threshold voltage of the sensing transistor is different according to the level of the conventional high potential voltage. That is, it can be seen that the threshold voltage is fluctuated by the body effect component according to the body-source voltage Vbs supplied to the sensing transistor Tr_Se, and the image quality is not uniform and a level difference occurs due to the thickness difference of the buffer layer.

On the other hand, in the present invention, as shown in FIG. 9B, the high potential voltage is variable (that is, the high potential voltage VDD is set to 8V in the first sensing period, and the high potential voltage VDD is set to 10V in the second sensing period. , 12V and 14V respectively) to generate a number of sensing values. Then, the body effect component (ΔVth@BE) is detected by comparing the sensing values, and the pure threshold voltage of the actual sensing transistor can be accurately sensed by excluding the body effect component. Through such accurate sensing, it is possible to compensate for deterioration and to detect defects caused by the sensing transistor, thereby improving reliability.

The above description is only illustrative of the present invention, and various modifications may be made without departing from the technical spirit of the present invention by those of ordinary skill in the technical field to which the present invention belongs. Therefore, the embodiments disclosed in the specification of the present invention do not limit the present invention. The scope of the present invention should be interpreted by the following claims, and all technologies within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

102: light-emitting display panel 104: data driver
106: scan driving unit 108: timing control unit

Claims (5)

A light-emitting display panel including a plurality of pixels having a light-emitting element, a driving transistor connected to the light-emitting element, and a sensing transistor including a body terminal connected to a source terminal of the driving transistor;
A first sensing unit that senses a signal flowing through the driving transistor to generate first sensing data;
A second sensing unit for generating second sensing data by sensing a signal flowing through the sensing transistor at least twice;
And a compensation unit for generating pixel data to which first and second compensation values based on the first and second sensing data are applied. The method of claim 1,
When the sensing transistor is in a sensing mode, the sensing transistor saturates and the driving transistor performs a linear operation. The method of claim 2,
When the sensing transistor senses at least twice, the high potential voltage supplied to the drain terminal of the driving transistor is varied. The method of claim 3,
The second sensing unit
For extracting a fluctuation component of the threshold voltage of the sensing transistor according to the voltage between the body terminal and the source terminal of the sensing transistor through a difference between the sensed first and second sensing values by sensing the signal flowing through the sensing transistor at least twice. An organic light-emitting display device comprising: The method of claim 4,
The driving transistor has a body terminal connected to the source terminal of the driving transistor,
Body terminals of each of the sensing transistor and the driving transistor are overlapped with an active layer and a buffer layer of each of the sensing transistor and the driving transistor therebetween,
The organic light emitting diode display device, wherein body terminals of each of the sensing transistor and the driving transistor are integrated.

Images