KR102548134B1 - Organic light emitting display panel, organic light emitting display device and method for driving the organic light emitting display device - Google Patents

Abstract

The present embodiments relate to an organic light emitting display device and a driving method of the organic light emitting display device, and a sensing target and sensing set for each panel and each subpixel in a section for sensing the mobility of a driving transistor in a subpixel of the organic light emitting display device. Sensing is determined based on the sensing target and sensing time by sensing the mobility of the driving transistor using the sensing data voltage determined according to time and variably adjusting the sensing target and sensing time according to the deterioration of the driving transistor. Inaccurate sensing and erroneous compensation for mobility are prevented by preventing the data voltage from exceeding the maximum output voltage of the data driver, and screen defects due to the continuous increase of the data voltage for sensing are prevented.

Description

Organic light emitting display panel, organic light emitting display device, and driving method of organic light emitting display device

The present embodiments relate to an organic light emitting display panel, an organic light emitting display device, and a method of driving the organic light emitting display device.

An organic light emitting display device that has recently been in the limelight as a display device uses organic light emitting diodes (OLEDs) that emit light by itself, and thus has advantages of fast response speed, high contrast ratio, luminous efficiency, luminance, and viewing angle.

Such an organic light emitting display device includes an organic light emitting display panel including a plurality of subpixels in which a plurality of gate lines and a plurality of data lines are disposed and disposed in an area where the gate lines and the data lines intersect, and driving the plurality of gate lines. It includes a gate driver for supplying data voltages to a plurality of data lines, a timing controller for controlling driving of the gate driver and data driver, and the like, and the subpixel includes an organic light emitting diode (OLED) and an organic light emitting diode (OLED). and a driving transistor that drives the OLED).

In such an organic light emitting display device, circuit elements such as organic light emitting diodes (OLEDs) and driving transistors in each subpixel each have unique characteristic values (eg, threshold voltage, mobility, etc.). In addition, each driving transistor is degraded according to driving time, so that a unique characteristic value of the driving transistor may change.

The luminance characteristics of the corresponding sub-pixel may be changed according to the change in the characteristic value, and when the characteristic value or characteristic value change between circuit elements is different, the luminance deviation between the sub-pixels is caused to deteriorate the luminance uniformity of the organic light emitting display panel. exist.

In order to solve this problem, a technology for sensing and compensating for a characteristic value of a circuit element in each subpixel is being developed.

For example, in order to sense and compensate for the mobility of the driving transistor, the mobility of the driving transistor is sensed during a blank time during which image data is not output during the driving period of the organic light emitting display device. The sensing of the mobility of the driving transistor may be performed by determining a data voltage for sensing according to a predetermined sensing target and sensing time and sensing a current capability based on the determined data voltage for sensing, that is, a voltage rise per time.

At this time, when the current capability (mobility) decreases due to the degradation of the driving transistor, the sensing data voltage is increased in order to satisfy a predetermined sensing target and sensing time.

However, when the increased data voltage for sensing exceeds the maximum output voltage of the data driver, the current capability (mobility) of the driving transistor is sensed low because the data voltage for sensing cannot be applied beyond the maximum output voltage. Accordingly, continuous compensation for the mobility is performed.

That is, inaccurate sensing and erroneous compensation may continue to occur due to the decrease in current capability (mobility) of the driving transistor and the limit of the output voltage of the data driver, resulting in screen defects of the organic light emitting display panel.

An object of the present embodiments is to provide an organic light emitting display device capable of accurately sensing the mobility of a driving transistor within a subpixel of the organic light emitting display device and accurately compensating for a mobility deviation.

An object of the present embodiments is to provide an organic light emitting display device capable of accurately sensing the mobility of a driving transistor even when current capability (mobility) is reduced due to degradation of the driving transistor.

An object of the present embodiments is an organic light emitting display that prevents screen defects due to an increase in the sensing data voltage by preventing the sensing data voltage applied to measure the mobility of the driving transistor from exceeding the maximum output voltage of the data driver. to provide the device.

An organic light emitting display panel in which a plurality of gate lines, a plurality of data lines, and a plurality of subpixels are disposed, a gate driver driving the plurality of gate lines, and data voltages supplying data voltages to the plurality of data lines. The driver includes a driver, and each of the plurality of subpixels includes an organic light emitting diode, a driving transistor for driving the organic light emitting diode, a sensing transistor connected between a first node of the driving transistor and a reference voltage line, and a second node of the driving transistor. and a switching transistor connected between the data line and a storage capacitor connected between the first node and the second node, wherein the data driver detects and senses the sensing target set for each subpixel in a section for measuring the characteristic value of the driving transistor. A sensing data voltage regulator configured to apply the sensing data voltage determined according to time to the second node of the driving transistor and adjust at least one of a sensing target and a sensing time set for each subpixel according to the sensing data voltage. It is possible to provide an organic light emitting display device that does.

In such an organic light emitting display device, the sensing data voltage controller may decrease a sensing target set for the subpixel or increase a sensing time set for the subpixel when the sensing data voltage for the subpixel exceeds a preset voltage. , at least one of the sensing target and the sensing time set in the subpixel may be adjusted so that the sensing data voltage for the subpixel is maintained below a preset voltage.

In such an organic light emitting display device, the sensing target may be set in proportion to the size of the light emitting area of the subpixel, the sensing time may be set in inverse proportion to the size of the light emitting area of the subpixel, and the sensing target may be a driving transistor included in the subpixel. It is set in proportion to the size of and the sensing time may be set in inverse proportion to the size of the driving transistor included in the subpixel.

In another embodiment, a reference voltage is applied to a first node of a driving transistor disposed in a subpixel of an organic light emitting display panel, and a sensing target and sensing time set for each subpixel are applied to a second node of the driving transistor. The step of applying the determined sensing data voltage, the step of floating the first node of the driving transistor, and the first node of the driving transistor at the sensing time set for each subpixel while the voltage of the first node of the driving transistor rises. A method of driving an organic light emitting display device may be provided, which may include measuring a voltage of and adjusting at least one of a sensing target and a sensing time set for each subpixel according to a data voltage for sensing.

In another embodiment, a plurality of gate lines disposed in one direction, a plurality of data lines disposed to cross the gate lines, disposed in an area where the gate lines and the data lines intersect, an organic light emitting diode, and an organic light emitting diode A driving transistor for driving, a sensing transistor connected between the first node of the driving transistor and the reference voltage line, a switching transistor connected between the second node of the driving transistor and the data line, and connected between the first node and the second node. In a section including a plurality of subpixels including storage capacitors and measuring the characteristic values of the driving transistor, the sensing data voltage determined according to the sensing target and sensing time set for each subpixel is transmitted through the data line to the second driving transistor. An organic light emitting display panel applied to a node may be provided.

According to the present embodiments, the mobility of the driving transistor is sensed using the sensing data voltage determined according to the sensing target set for each sub-pixel of the organic light emitting display and the sensing time, so that the sensing data voltage is obtained according to the characteristic value of the sub-pixel. prevent increasing

According to the present embodiments, by variably adjusting the sensing target and the sensing time set for each subpixel, an increase in the data voltage for sensing due to the degradation of the driving transistor is prevented, and screen defects due to the increase in the data voltage for sensing are prevented. prevent this from happening.

According to the present exemplary embodiments, the entire sensing time for sensing the mobility of the driving transistor can be reduced by setting an optimized sensing time for each subpixel.

1 is a diagram showing a schematic configuration of an organic light emitting display device according to the present embodiments.
2 is a diagram illustrating an example of a sub-pixel structure of an organic light emitting display device according to the present embodiments.
3 is a diagram illustrating an example of a configuration for adjusting a subpixel structure, a compensation circuit, and a sensing data voltage of an organic light emitting display device according to the present embodiments.
4 is a diagram for explaining a process of sensing a mobility of a driving transistor in a subpixel of an organic light emitting display device according to the present embodiments.
5 to 7 are diagrams illustrating examples of determining a data voltage for sensing according to a sensing target and a sensing time in an organic light emitting display device according to the present embodiments.
8 to 10 are diagrams illustrating examples of variablely setting a sensing target and a sensing time for each subpixel in an organic light emitting display device according to the present embodiments.
11 is a diagram illustrating an example of a data voltage for sensing determined according to a variable sensing target and sensing time in an organic light emitting display device according to the present embodiments.
12 and 13 are diagrams showing examples of sensing targets and sensing times set differently according to organic light emitting display panels and data voltages for sensing determined according to the organic light emitting display device according to the present embodiments.
14 is a flowchart illustrating a process of a method of driving an organic light emitting display device according to example embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention are described in detail below with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, sequence, order, or number of the corresponding component is not limited by the term. When an element is described as being “connected,” “coupled to,” or “connected” to another element, that element is or may be directly connected to that other element, but intervenes between each element. It will be understood that may be "interposed", or each component may be "connected", "coupled" or "connected" through other components.

1 shows a schematic configuration of an organic light emitting display device 100 according to the present embodiments.

Referring to FIG. 1 , in an organic light emitting display device 100 according to the present embodiments, a plurality of gate lines GL and a plurality of data lines DL are disposed, and the gate lines GL and data lines DL An organic light emitting display panel 110 including a plurality of subpixels (SP) disposed in the crossing area, a gate driver 120 driving a plurality of gate lines (GL), and a plurality of data lines (DL). It includes a data driver 130 for supplying a data voltage, and a timing controller 140 (T-CON) for controlling the gate driver 120 and the data driver 130.

The gate driver 120 sequentially drives the plurality of gate lines GL by sequentially supplying scan signals to the plurality of gate lines GL.

The gate driver 120 sequentially supplies scan signals of an on voltage or an off voltage to the plurality of gate lines GL under the control of the timing controller 140 to generate the plurality of gate lines GL. run sequentially.

The gate driver 120 may be located on only one side or both sides of the organic light emitting display panel 110 according to a driving method.

In addition, the gate driver 120 may include one or more gate driver integrated circuits.

Each gate driver integrated circuit is connected to a bonding pad of the organic light emitting display panel 110 by a tape automated bonding (TAB) method or a chip on glass (COG) method, or It can be implemented as a GIP (Gate In Panel) type and directly disposed on the organic light emitting display panel 110 . In addition, it may be integrated and disposed on the organic light emitting display panel 110, or may be implemented in a chip on film (COF) method mounted on a film connected to the organic light emitting display panel 110.

The data driver 130 drives the plurality of data lines DL by supplying data voltages to the plurality of data lines DL.

When a specific gate line GL is opened, the data driver 130 converts the image data received from the timing controller 140 into analog data voltages and supplies them to the plurality of data lines DL, thereby providing a plurality of data lines DL. ) to drive

The data driver 130 may include at least one source driver integrated circuit to drive a plurality of data lines DL.

Each source driver integrated circuit is connected to a bonding pad of the organic light emitting display panel 110 by a tape automated bonding (TAB) method or a chip on glass (COG) method, or It may be directly disposed on the organic light emitting display panel 110 or may be integrated and disposed on the organic light emitting display panel 110 .

In addition, each source driver integrated circuit may be implemented in a Chip On Film (COF) method. In this case, one end of each source driver integrated circuit is bonded to at least one source printed circuit board, and the other end is bonded to the organic light emitting display panel 110 .

The timing controller 140 controls the driving of the gate driver 120 and the data driver 130 by supplying various control signals to the gate driver 120 and the data driver 130 .

The timing controller 140 starts scanning according to the timing implemented in each frame, converts externally input image data according to the data signal format used by the data driver 130, and outputs the converted image data. and controls data driving at an appropriate time according to the scan.

The timing controller 140 includes various timing signals including a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), an input data enable (DE) signal, and a clock signal (CLK) together with input image data. are received from outside (e.g. host system).

The timing controller 140 converts the input image data input from the outside to suit the data signal format used by the data driver 130 and outputs the converted image data, as well as the gate driver 120 and the data driver 130. ), receive timing signals such as the vertical sync signal (Vsync), the horizontal sync signal (Hsync), the input data enable signal (DE), and the clock signal (CLK), and generate various control signals to generate gate drivers (120) and the data driver (130).

For example, the timing controller 140 may include a gate start pulse (GSP), a gate shift clock (GSC), and a gate output enable signal (GOE) to control the gate driver 120 . : Gate Output Enable) and various gate control signals (GCS: Gate Control Signal) are output.

Here, the gate start pulse GSP controls the operation start timing of one or more gate driver integrated circuits constituting the gate driver 120 . The gate shift clock (GSC) is a clock signal commonly input to one or more gate driver integrated circuits and controls shift timing of scan signals (gate pulses). The gate output enable signal GOE specifies timing information of one or more gate driver integrated circuits.

In addition, the timing controller 140, in order to control the data driver 130, a source start pulse (SSP: Source Start Pulse), a source sampling clock (SSC: Source Sampling Clock), a source output enable signal (SOE: Source It outputs various data control signals (DCS: Data Control Signal) including Output Enable) and the like.

Here, the source start pulse SSP controls data sampling start timing of one or more source driver integrated circuits constituting the data driver 130 . The source sampling clock (SSC) is a clock signal that controls sampling timing of data in each source driver integrated circuit. The source output enable signal SOE controls output timing of the data driver 130 .

The timing controller 140 is a source printed circuit board bonded with a source driver integrated circuit and a control printed circuit connected through a connection medium such as a flexible flat cable (FFC) or a flexible printed circuit (FPC). It may be disposed on a board (Control Printed Circuit Board).

On such a control printed circuit board, a power controller (not shown) supplies various voltages or currents to the organic light emitting display panel 110, the gate driver 120, and the data driver 130 or controls various voltages or currents to be supplied. more can be placed. Such a power controller is also referred to as a power management integrated circuit.

Each subpixel SP disposed on the organic light emitting display panel 110 may include a circuit element such as a transistor.

For example, in the organic light emitting display panel 110, each subpixel SP is composed of an organic light emitting diode (OLED) and a circuit element such as a driving transistor (DRT) for driving the organic light emitting diode (OLED). It can be.

The type and number of circuit elements constituting each sub-pixel SP may be variously determined according to a provided function and a design method.

2 illustrates an example of a sub-pixel (SP) structure of the organic light emitting display device 100 according to the present embodiments.

Referring to FIG. 2 , in the organic light emitting display device 100 according to the present embodiments, each subpixel SP includes an organic light emitting diode OLED and a driving transistor DRT for driving the organic light emitting diode OLED. ) and a sensing transistor (SENT: Sensing Transistor) electrically connected between the first node (N1) of the driving transistor (DRT) and a reference voltage line (RVL) supplying a reference voltage (Vref: Reference Voltage). ), a switching transistor (SWT) electrically connected between the second node N2 of the driving transistor DRT and the data line DL supplying the data voltage Vdata, and the driving transistor DRT It is configured to include a storage capacitor (Cstg: Storage Capacitor) electrically connected between the first node N1 and the second node N2 of the .

An organic light emitting diode (OLED) may include a first electrode (eg, an anode electrode or a cathode electrode), an organic layer, and a second electrode (eg, a cathode electrode or an anode electrode).

The driving transistor DRT drives the organic light emitting diode OLED by supplying a driving current to the organic light emitting diode OLED.

The first node N1 of the driving transistor DRT may be electrically connected to the first electrode of the organic light emitting diode OLED, and may be a source node or a drain node. The second node N2 of the driving transistor DRT may be electrically connected to a source node or a drain node of the switching transistor SWT and may be a gate node. The third node N3 of the driving transistor DRT may be electrically connected to a driving voltage line (DVL) that supplies the driving voltage EVDD, and may be a drain node or a source node.

The sensing transistor SENT may be turned on by a gate signal to apply the reference voltage Vref to the first node N1 of the driving transistor DRT.

Also, when the sensing transistor SENT is turned on, it may be used as a voltage sensing path for the first node N1 of the driving transistor DRT.

When turned on by the gate signal, the switching transistor SWT transfers the data voltage Vdata supplied through the data line DL to the second node N2 of the driving transistor DRT.

In this case, the sensing transistor SENT and the switching transistor SWT may be connected to different gate lines GL to be separately controlled on-off or connected to the same gate line GL to be controlled.

The storage capacitor Cstg is electrically connected between the first node N1 and the second node N2 of the driving transistor DRT to generate a data voltage Vdata corresponding to the image signal voltage or a voltage corresponding thereto. It can be maintained for one frame time.

Meanwhile, in the case of the organic light emitting display device 100 according to the present exemplary embodiments, as the driving time of each subpixel SP is increased, circuit elements such as an organic light emitting diode (OLED) and a driving transistor (DRT) Degradation may proceed.

Accordingly, inherent characteristic values (eg, threshold voltage, mobility, etc.) of circuit elements such as organic light emitting diodes (OLEDs) and driving transistors (DRTs) may change.

Such a change in the characteristic value of a circuit element causes a change in the luminance of the corresponding sub-pixel (SP), and the difference in the change in the characteristic value between the circuit elements due to the difference in the degree of deterioration between the circuit elements causes a luminance deviation between the sub-pixels (SP) and an organic light emitting display. This may cause deterioration in luminance uniformity of the panel 110 .

Here, the characteristic value of the circuit element includes the threshold voltage or mobility of the driving transistor DRT, and may also include the threshold voltage of the organic light emitting diode OLED.

The organic light emitting display device 100 according to the present embodiments includes a sensing function for sensing a characteristic value variation between subpixels SP or a characteristic value deviation between subpixels SP and a sensing result to detect subpixel SPs. A compensation function for compensating for the characteristic value of may be provided.

3 illustrates an example of a sub-pixel (SP) structure and a compensation circuit of the organic light emitting display device 100 according to the present embodiments.

Referring to FIG. 3 , the organic light emitting display device 100 according to the present embodiments includes a sensing unit 310, a compensating unit 320, a memory 330, a sensing unit 310, a compensating unit 320, a memory 330, It may include a data voltage regulator 340 for sensing, a reference voltage switch SPRE, and a sampling switch SAMP.

The sensing unit 310 senses a voltage for sensing a characteristic value or change thereof of the subpixel SP, converts the sensed voltage into a digital value, and outputs sensing data including the converted sensing value. Here, the characteristic value of the subpixel (SP) means the threshold voltage and mobility of the driving transistor (DRT) or the threshold voltage of the organic light emitting diode (OLED), and the sensing data may be in the LVDS (Low Voltage Differential Signaling) data format. can

The sensing unit 310 may be implemented by including at least one analog to digital converter (ADC). Each analog-to-digital converter (ADC) may be included inside the source driver integrated circuit, and may be disposed outside the source driver integrated circuit in some cases.

The compensating unit 320 performs a compensation process of compensating for characteristic value deviations between the sub-pixels SP by recognizing the characteristic values or changes thereof of the sub-pixels SP using the sensing data output by the sensing unit 310 .

The compensating unit 320 may be included inside the timing controller 140 or may be disposed outside the timing controller 140 in some cases.

The memory 330 stores sensing data output by the sensing unit 310 and may store a compensation value calculated by the compensating unit 320 based on the sensing data.

The sensing data voltage controller 340 adjusts the sensing data voltage applied to the second node N2 of the driving transistor DRT in a period of sensing the characteristic value of the driving transistor DRT.

When the mobility of the driving transistor DRT is sensed, a data voltage for sensing is determined according to a preset sensing target and sensing time.

The mobility of the driving transistor DRT is sensed according to the determined sensing data voltage, and whether to compensate for the mobility is determined according to whether or not the sensed value reaches a preset sensing target at a preset sensing time.

The sensing data voltage controller 340 may set a sensing target and sensing time, which are the basis for determining the sensing data voltage for sensing the mobility of the driving transistor DRT, by varying the setting, and may set the subpixel SP. A data voltage for sensing may be determined using a sensing target and a sensing time set differently for each type.

The data voltage regulator 340 for sensing may be included inside the timing controller 140 or may be disposed outside the timing controller 140 in some cases.

The reference voltage switch SPRE controls whether or not to supply the reference voltage Vref to the reference voltage line RVL, and the sampling switch SAMP controls the reference voltage for sensing the characteristic value of the subpixel SP. A connection between the voltage line RVL and the sensing unit 310 is controlled.

When the reference voltage switch SPRE is turned on, the reference voltage Vref is supplied to the reference voltage line RVL. The reference voltage Vref supplied to the reference voltage line RVL may be applied to the first node N1 of the driving transistor DRT through the turned-on sensing transistor SENT.

On the other hand, when the voltage of the first node N1 of the driving transistor DRT becomes a voltage state reflecting the characteristic value of the subpixel SP, a reference that may be equipotential with the first node N1 of the driving transistor DRT. The voltage of the voltage line RVL may also be in a voltage state reflecting the characteristic value of the subpixel SP. At this time, a voltage reflecting the characteristic value of the subpixel SP may be charged in the line capacitor formed on the reference voltage line RVL.

That is, when the sensing transistor SENT is turned on, the voltage of the first node N1 of the driving transistor DRT is the voltage of the reference voltage line RVL and the line formed on the reference voltage line RVL. The voltages charged in the capacitors may be the same.

When the voltage of the first node N1 of the driving transistor DRT becomes a voltage state reflecting the characteristic value of the subpixel SP, the sampling switch SAMP is turned on, and the sensing unit 310 and the reference voltage line (RVL) can be connected.

Accordingly, the sensing unit 310 senses the voltage of the reference voltage line RVL, which is a voltage state reflecting the characteristic value of the subpixel SP. Here, the reference voltage line RVL may also be referred to as a "sensing line SL".

That is, the sensing unit 310 senses the voltage of the first node N1 of the driving transistor DRT.

In the case of sensing the threshold voltage of the driving transistor DRT, the voltage sensed by the sensing unit 310 may be a voltage value including the threshold voltage Vth or a change in the threshold voltage ΔVth of the driving transistor DRT.

Also, the voltage sensed by the sensing unit 310 may be a voltage value for sensing the mobility of the driving transistor DRT in the case of sensing the mobility of the driving transistor DRT.

4 is a diagram for explaining a method of sensing the mobility of the driving transistor DRT of the organic light emitting display device 100 according to the present embodiments.

Referring to FIG. 4 , when the driving transistor DRT is driven for sensing the mobility, the first node N1 and the second node N2 of the driving transistor DRT generate a reference voltage Vref and a sensing data voltage ( Vdata) is initialized.

Then, when the reference voltage switch SPRE is turned off, the first node N1 of the driving transistor DRT is floated. At this time, the switching transistor SWT is turned off, so that the second node N2 of the driving transistor DRT may also float.

Accordingly, the voltage of the first node N1 of the driving transistor DRT starts to rise.

During a certain period of time, the voltage increase ΔV of the first node N1 of the driving transistor DRT is a voltage rising rate and varies depending on the current capability of the driving transistor DRT, that is, the mobility.

That is, as the current capability (mobility) of the driving transistor DRT increases, the voltage at the first node N1 of the driving transistor DRT rises more steeply, so that the voltage at the first node N1 of the driving transistor DRT increases for a certain period of time. ) has a large voltage rise (ΔV).

After the voltage of the first node N1 of the driving transistor DRT rises for a predetermined period of time, the sensing unit 310 senses the increased voltage of the first node N1 of the driving transistor DRT. .

A rate of change per time, that is, a slope, of the voltage rise ΔV according to the voltage Vsen sensed by the sensing unit 310 may be mobility.

The sensing unit 310 converts the voltage Vsen sensed according to the aforementioned threshold voltage or mobility sensing drive into a digital value, and generates and outputs sensing data including the converted sensing value. Sensing data output from the sensing unit 310 may be stored in the memory 330 or provided to the compensating unit 320 .

The compensation unit 320 determines the characteristic value or characteristic value change of the driving transistor DRT in the corresponding subpixel SP based on the sensing data provided by the sensing unit 310 or the sensing data stored in the memory 330, and the characteristic value deviation. Performs a process that compensates for

The characteristic value compensation process may include a threshold voltage compensation process for compensating the threshold voltage of the driving transistor DRT and a mobility compensation process for compensating for the mobility of the driving transistor DRT.

The threshold voltage compensation process may include processing of calculating a compensation value for compensating for the threshold voltage or threshold voltage deviation, storing the calculated compensation value in the memory 330, or changing corresponding image data with the calculated compensation value. there is.

The mobility compensation process may include processing of calculating a compensation value for compensating for mobility or mobility deviation, storing the calculated compensation value in the memory 330, or changing corresponding image data with the calculated compensation value. can

The compensator 320 may change image data through threshold voltage compensation processing or mobility compensation processing and supply the changed data to a corresponding source driver integrated circuit in the data driver 130 .

Accordingly, the corresponding source driver integrated circuit converts the data changed in the compensation unit 320 into a data voltage through a digital to analog converter (DAC) and supplies it to the corresponding subpixel SP, so that the subpixel ( The compensation for the characteristic value of SP) can be made.

As the characteristic value of the sub-pixels SP is compensated, the luminance deviation between the sub-pixels SP is reduced or prevented, thereby increasing the luminance uniformity of the organic light emitting display panel 110 and improving image quality.

5 to 7 show that a sensing data voltage for sensing the mobility of the driving transistor DRT is determined in the organic light emitting display device 100 according to the present embodiments, and the driving transistor ( It shows an example of sensing the mobility of DRT).

Referring to FIG. 5 , in order to sense the mobility of the driving transistor DRT, a sensing data voltage is determined according to a preset sensing target and sensing time, and the mobility of the driving transistor DRT is determined using the determined sensing data voltage. senses

That is, the data voltage for sensing is determined so that the sensed value reaches a preset sensing target at a preset sensing time.

When the data voltage for sensing is determined, the reference voltage Vref is applied to the first node N1 of the driving transistor DRT and the data voltage for sensing is applied to the second node N2 of the driving transistor DRT. The first node N1 and the second node N2 are respectively initialized.

After the first node N1 and the second node N2 are initialized, the reference voltage switch SPRE is turned off to float the first node N1.

As the first node N1 floats, the voltage of the first node N1 rises, and as shown in FIG. 5 , the voltage of the first node N1 rises.

The sampling switch SAMP is turned on according to a preset sensing time so that the sensing unit 310 can sense the voltage of the first node N1 of the driving transistor DRT.

The sensing unit 310 converts the sensed voltage value of the first node N1 into a digital value and outputs the converted sensing value to the memory 330 or the compensation unit 320 .

The compensation unit 320 calculates a compensation value for compensating for the mobility deviation based on the sensing value output by the sensing unit 310 .

At this time, when the mobility of the driving transistor DRT is measured to be low, a compensation value for the mobility is applied to increase the data voltage for sensing, and the increased data voltage for sensing exceeds the maximum output voltage of the data driver 130. I can.

6 and 7 show examples in which the data voltage for sensing determined according to the preset sensing target and sensing time exceeds the maximum output voltage of the data driver 130 .

Referring to FIG. 6 , when the data voltage for sensing increases by the compensation value for the mobility and exceeds the maximum output voltage of the data driver 130, the data driver 130 may output the determined data voltage for sensing. Therefore, the maximum voltage that the data driver 130 can output is output.

Since the data driver 130 outputs a voltage lower than the determined sensing data voltage, the voltage of the first node N1 of the driving transistor DRT in the period where the mobility of the driving transistor DRT is sensed is determined by the preset sensing data voltage. It is impossible to reach the preset sensing target in time.

That is, since a voltage lower than the determined sensing data voltage is applied, the current capability (mobility) is measured to be low because the voltage rise slope is smaller than when the determined sensing data voltage is applied.

Therefore, as shown in FIG. 7, compensation for the mobility is additionally performed, and the data voltage for sensing increases, but the data driver 130 outputs a maximum output voltage lower than the increased data voltage for sensing. Differences in values occur again.

As a result, if the data voltage for sensing exceeds the maximum output voltage of the data driver 130, the preset sensing target is not satisfied when the mobility of the driving transistor DRT is sensed, so that inaccurate mobility compensation is continuously performed. This causes screen defects such as irregular stains to occur.

In the present embodiments, the sensing target and sensing time, which are standards for determining the data voltage for sensing in the period of sensing the mobility of the driving transistor (DRT), are set for each panel and each subpixel (SP), and are variably adjusted. Provided is a mobility sensing and compensation method that solves the above-described problem by providing

8 to 10 are diagrams illustrating examples in which sensing targets and sensing times are differently set for each sub-pixel (SP) in the organic light emitting display device 100 according to the present embodiments.

8 to 10 illustrate a case in which four sub-pixels (SP) composed of red (R), green (G), blue (B), and white (W) are arranged in one pixel (P: Pixel) as an example. Although described, the present embodiments are not limited thereto.

FIG. 8 shows an example in which sensing targets are set differently for each subpixel SP. Referring to FIG. 8 , when the mobility of the driving transistor DRT of the red (R) subpixel SP is sensed, the first case is sensed. A data voltage for sensing is determined based on one sensing target and a first sensing time.

When the mobility of the driving transistor DRT of the white (W) subpixel SP is sensed, the sensing target is set low to determine the sensing data voltage based on the second sensing target and the first sensing time.

When one pixel (P) is composed of red (R), green (G), blue (B), and white (W) subpixels (SP), white (W) has the highest efficiency, so white (W) The light emitting area of can be designed to be the smallest. Also, since the light emitting area of white (W) is the smallest, the size of the driving transistor DRT disposed in the white (W) subpixel SP may be the smallest.

Therefore, even in the case of the sub-pixel SP having a small size of the driving transistor DRT, if the sensing data voltage is determined with the same sensing target and sensing time, the sensing data voltage becomes high and exceeds the maximum output voltage of the data driver 130. can do.

Therefore, by setting the sensing target low, the data voltage for sensing can be determined low, and the data voltage for sensing can be prevented from exceeding the maximum output voltage of the data driver 130 .

9 shows an example in which the sensing time is set differently for each subpixel SP. Referring to FIG. 9, in the case of the red (R) subpixel SP, the mobility of the driving transistor DRT is sensed. Determines the data voltage for sensing according to the first sensing target and the first sensing time.

In the case of the white (W) subpixel SP, a data voltage for sensing is determined according to the first sensing target and the second sensing time, and the mobility of the driving transistor DRT is sensed using the determined data voltage for sensing. .

That is, by increasing the sensing time, which is the time required to reach the sensing target, in the case of the white (W) subpixel SP having a small size of the driving transistor DRT, the driving transistor DRT uses a low data voltage for sensing. ) to sense the mobility.

10 illustrates an example in which sensing targets and sensing times are differently set for each sub-pixel (SP).

Referring to FIG. 10 , in the case of the red (R) subpixel SP, the mobility of the driving transistor DRT is sensed using a sensing data voltage determined according to a first sensing target and a first sensing time.

In the case of the white (W) subpixel SP, a data voltage for sensing is determined based on a second sensing target lower than the first sensing target and a second sensing time longer than the first sensing time, and the determined sensing data voltage is used to sense the mobility of the driving transistor DRT.

That is, when the size of the driving transistor DRT is small, the sensing target is set to be low and the sensing time is set to be long so that the mobility of the driving transistor DRT can be sensed using a low sensing data voltage.

Accordingly, the maximum output voltage of the data driver 130 is not exceeded even if the data voltage for sensing increases due to the compensation of the mobility.

11 illustrates an example of a data voltage for sensing determined according to a sensing target set for each subpixel SP and a sensing time, and red even in the case of a white (W) subpixel SP having a small driving transistor DRT. (R) It can be seen that the level is determined to be the same as the sensing data voltage of the subpixel SP.

In the case of the subpixel SP having a small size of the driving transistor DRT, the sensing target is lowered and the sensing time is set longer so that the mobility of the driving transistor DRT can be sensed with a low sensing data voltage.

The fact that the data voltage for sensing can be lowered by adjusting the sensing target and the sensing time can be clearly expressed from Equations 1 and 2 below.

Equation 1 represents the amount of charge charged in the capacitor C connected to the reference voltage line RVL during the sensing time Δt in the period of sensing the mobility of the driving transistor DRT.

ΔV is a voltage to be sensed, which means a sensing target, and i, which means a sensing current, is a criterion for determining a data voltage for sensing.

Since C is a fixed value, the sensing current (i) is proportional to the sensing target (ΔV) and inversely proportional to the sensing time (Δt), and the data voltage for sensing is also proportional to the sensing target (ΔV) and inversely proportional to the sensing time (Δt). will do

That is, if the sensing target is reduced and the sensing time is increased, the sensing data voltage can be set low.

In the present embodiments, the sensing target and the sensing time are set in consideration of the characteristics of each subpixel (SP), so that the driving transistor (DRT) moves with the sensing data voltage that does not exceed the maximum output voltage of the data driver 130. to enable sensing.

Meanwhile, the present embodiments are characterized in that a sensing target and sensing time are set for each subpixel (SP), and the set sensing target and sensing time may be variably adjusted.

The sensing data voltage regulator 340 determines the sensing data voltage according to the sensing target and sensing time set for each sub-pixel SP and senses the mobility of the driving transistor DRT according to the determined sensing data voltage. make it possible

At this time, the sensing target and sensing time are set differently for each sub-pixel (SP) in consideration of the luminous efficiency of the sub-pixel (SP), the size of the driving transistor (DRT), and the driving transistor (DRT) moves with a low sensing data voltage. Even if the degree is sensed, the data voltage for sensing may gradually increase by applying a compensation value according to deterioration of circuit elements in the subpixel SP.

Accordingly, since the data voltage for sensing increases and may exceed the maximum output voltage of the data driver 130, the data voltage for sensing controller 340 compares the data voltage for sensing with a predetermined voltage and performs sensing according to the comparison result. By adjusting the target or the sensing time, the data voltage for sensing does not exceed the maximum output voltage of the data driver 130 even if the deterioration of the circuit element progresses.

Here, the preset voltage may be set to a voltage lower than the maximum output voltage of the data driver 130, for example, to a voltage corresponding to 80% of the maximum output voltage.

When the data voltage for sensing exceeds a preset voltage, the sensing data voltage controller 340 adjusts the sensing target or the sensing time so that the sensing data voltage is maintained lower than the preset voltage.

For example, if the data voltage for sensing exceeds 80% of the maximum output voltage of the data driver 130, the sensing data voltage can be maintained at 80% or less of the maximum output voltage of the data driver 130. The sensing target and sensing time may be reset by decreasing the target and increasing the sensing time.

The sensing data voltage controller 340 variably adjusts the sensing target and sensing time set for each sub-pixel (SP) as the sensing data voltage increases, thereby sensing data determined according to the sensing target and sensing time. Make sure that the voltage does not exceed the maximum output voltage of the data driver 130.

Therefore, the data voltage for sensing increases by the mobility compensation of the driving transistor DRT and exceeds the maximum output voltage of the data driver 130, thereby preventing accurate mobility sensing and incorrect mobility compensation being performed. Prevent screen defects due to exceeding the maximum output voltage of the data voltage for sensing.

12 and 13 are examples in which sensing targets and sensing times are set differently according to the organic light emitting display panel 110 in the organic light emitting display device 100 according to the present embodiments, and sensing determined according to the set sensing targets and sensing times. It shows an example of the data voltage for use.

Referring to FIG. 12 , in the organic light emitting display device 100 according to the present embodiments, the sensing target and sensing time, which are standards for determining the sensing data voltage for sensing the mobility of the driving transistor DRT, are selected for organic light emission. It can be set differently according to the display panel 110 .

Current capability (mobility) may be different for each organic light emitting display panel 110, and even when the current capability is lower than that of panel 1, as in panel 2 shown in FIG. When the data voltage is determined, the data voltage for sensing of panel 2 is initially set high.

If compensation for the mobility of the driving transistor DRT is performed while the initial sensing data voltage is set high, the sensing data voltage may exceed the maximum output voltage of the data driver 130 as described above. .

Therefore, by setting the sensing target and sensing time differently according to the current capability of the panel, as shown in FIG. 13, the mobility of the driving transistor DRT can be sensed with the same sensing data voltage.

In addition, based on the sensing target and sensing time set for each organic light emitting display panel 110, a sensing target and sensing time are set for each sub-pixel SP in the organic light emitting display panel 110, and the deterioration of the driving transistor DRT ( Degradation), the sensing target and sensing time are variably adjusted to prevent inaccurate mobility sensing and erroneous compensation due to an increase in data voltage for sensing.

14 illustrates a process of a driving method of the organic light emitting display device 100 according to the present embodiments.

Referring to FIG. 14 , in order to sense the mobility of the driving transistor DRT, the reference voltage Vref is applied to the first node N1 of the driving transistor DRT (S1400).

A data voltage for sensing is determined based on the sensing target and the sensing time set according to the driving transistor DRT or the subpixel SP in which the driving transistor DRT is disposed (S1410).

It is checked whether the determined data voltage for sensing exceeds the preset voltage (S1420), and if it exceeds the preset voltage, the sensing target and sensing time are adjusted so that the data voltage for sensing does not exceed the preset voltage (S1430). .

At this time, the data voltage for sensing can be adjusted low by setting a low sensing target or long sensing time.

A data voltage for sensing determined not to exceed a predetermined voltage is applied to the second node N2 of the driving transistor DRT (S1440), and the first node N1 is floated (S1450).

The voltage of the first node N1 of the driving transistor DRT is sensed according to the set sensing time (S1460), and the mobility is measured based on the sensed voltage value (S1470) to obtain a compensation value to compensate for the mobility deviation. It is calculated (S1480).

According to the present embodiments, in sensing the mobility of the driving transistor DRT, the sensing target and sensing time, which are standards for determining the data voltage for sensing, are set differently in consideration of the characteristics of each panel or subpixel, The data voltage for sensing is prevented from exceeding the maximum output voltage of the data driver 120 by the mobility compensation value.

In addition, by variably adjusting the sensing target and the sensing time, the data voltage for sensing can be maintained below a certain voltage, and the data voltage for sensing does not exceed the maximum output voltage of the data driver 130 so that the driving transistor ( The mobility of the DRT) is accurately sensed and erroneous compensation is not performed.

In addition, since the data voltage for sensing does not exceed the maximum output voltage of the data driver 130, screen defects such as irregular stains caused by this are prevented from occurring.

The above description is merely illustrative of the technical idea of the present invention, and various modifications and variations will be possible to those skilled in the art without departing from the essential characteristics of the present invention. Since the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to explain, the scope of the technical idea of the present invention is not limited by these embodiments.

100: organic light emitting display device 110: organic light emitting display panel
120: gate driver 130: data driver
140: timing controller 310: sensing unit
320: compensation unit 330: memory
340: data voltage regulator for sensing

Claims (16)

an organic light emitting display panel on which a plurality of gate lines, a plurality of data lines, and a plurality of subpixels are disposed;
a gate driver driving the plurality of gate lines; and
a data driver supplying data voltages to the plurality of data lines;
Each of the plurality of subpixels,
An organic light emitting diode, a driving transistor for driving the organic light emitting diode, a sensing transistor connected between a first node of the driving transistor and a reference voltage line, and a switching transistor connected between a second node of the driving transistor and the data line. and a storage capacitor connected between the first node and the second node,
The data driver,
In a section where one of the characteristic values including the threshold voltage and mobility of the driving transistor is measured, a sensing data voltage determined according to the sensing target and sensing time set for each subpixel is applied to the second node of the driving transistor. do,
Thereafter, the first node and the second node are floated.
According to claim 1,
and a sensing data voltage controller configured to adjust at least one of a sensing target and a sensing time set for each subpixel according to the sensing data voltage.
According to claim 2,
The data voltage regulator for sensing,
and reducing a sensing target set for the sub-pixel when a data voltage for sensing of the sub-pixel exceeds a predetermined voltage.
According to claim 2,
The data voltage regulator for sensing,
An organic light emitting display device that increases a sensing time set for the subpixel when a data voltage for sensing of the subpixel exceeds a preset voltage.
According to claim 2,
The data voltage regulator for sensing,
An organic light emitting display device that adjusts at least one of a sensing target and a sensing time set for the subpixel to maintain a sensing data voltage for the subpixel below a preset voltage.
According to claim 5,
The predetermined voltage is a voltage lower than the maximum output voltage of the data driver.
According to claim 1,
The sensing target is set in proportion to the size of the light emitting area of the subpixel, and the sensing time is set in inverse proportion to the size of the light emitting area of the subpixel.
According to claim 1,
The sensing target is set in proportion to a size of a driving transistor included in the subpixel, and the sensing time is set in inverse proportion to a size of a driving transistor included in the subpixel.
According to claim 1,
The sensing target and sensing time set for each subpixel are set based on the sensing target and sensing time set according to the organic light emitting display panel.
According to claim 1,
The sensing data voltage applied to the second node of the driving transistor is determined in proportion to the set sensing target and in inverse proportion to the set sensing time.
According to claim 1,
A sensing unit configured to measure the voltage of the first node of the driving transistor at a sensing time set for each sub-pixel while the voltage of the first node of the driving transistor rises in the period of measuring the characteristic value of the driving transistor. organic light emitting display device.
applying a reference voltage to a first node of a driving transistor disposed in a subpixel of the organic light emitting display panel;
applying a sensing data voltage determined according to a sensing target and a sensing time set for each subpixel to a second node of the driving transistor;
floating a first node and a second node of the driving transistor; and
Measuring the voltage of the first node to sense one of the characteristic values including the threshold voltage and mobility of the driving transistor at a sensing time set for each subpixel while the voltage of the first node of the driving transistor is rising step
A method of driving an organic light emitting display device comprising:
According to claim 12,
and adjusting at least one of a sensing target and a sensing time set for each subpixel according to the sensing data voltage.
According to claim 13,
The step of adjusting at least one of the sensing target and the sensing time,
A method of driving an organic light emitting display device in which a sensing target set for the subpixel is reduced or a sensing time is increased when the sensing data voltage exceeds a predetermined voltage.
According to claim 14,
The predetermined voltage is a voltage lower than a maximum output voltage of a data driver outputting the sensing data voltage.
a plurality of gate lines disposed in one direction;
a plurality of data lines disposed to cross the gate line; and
an organic light emitting diode disposed in a region where the gate line and the data line intersect, a driving transistor driving the organic light emitting diode, and a sensing transistor connected between a first node of the driving transistor and a reference voltage line; a plurality of subpixels including a switching transistor connected between a second node of a driving transistor and the data line, and a storage capacitor connected between the first node and the second node;
In a period in which one of the characteristic values including the threshold voltage and mobility of the driving transistor is measured, the sensing data voltage determined according to the sensing target and sensing time set for each subpixel is transmitted through the data line to the driving transistor. 2 is authorized to the node,
After that, the first node and the second node are floating organic light emitting display panel.

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