KR102171042B1 - Organic light emitting diode display device and method thereof - Google Patents

Abstract

The present invention relates to an organic light emitting diode display capable of improving the display quality of an image by setting a precharge voltage to be variable in consideration of a panel characteristic of a display panel, and a driving method thereof.

Description

Organic light emitting diode display and its driving method {ORGANIC LIGHT EMITTING DIODE DISPLAY DEVICE AND METHOD THEREOF}

The present invention relates to an organic light emitting diode display and a driving method thereof.

The present invention relates to a panel driving circuit, and in detail, since the panel is driven by using an active precharge voltage, energy loss that may occur during the precharge operation is reduced, and a precharge operation by reflecting a change in characteristics of the display panel It relates to a panel driving circuit capable of performing.

In recent years, in the field of flat panel displays, rapid development has been made. As for flat panel displays, LCD (Liquid Crystal Display) is the lead, and PDP (Plasma Display Panel), FED (Field Emission Display), EL (Electroluminescent), etc. are representative.

Currently, LCDs are widely used as video display devices for TVs, computers, or mobile communication terminals. These LCDs are not only heavy, but also thick and have a slow response speed because they require a backlight.

Accordingly, an organic EL display device (or OLED (Organic Light Emitting Diode)) is attracting attention as a next-generation video display device replacing LCD.

The organic EL device (OLED) contains an extremely thin organic layer of 0.1㎛ or less, so when a current is passed through the organic layer, electrons and holes recombine near the interface between the electron transport layer and the hole transport layer. This light emission has an extremely fast response time of several hundred ns or less.

As described above, the organic EL device (OLED) is composed of a two-pole structure of an anode electrode (anode) and a cathode electrode (cathode), and is driven by current due to the difference in voltage-current characteristics of the individual organic EL devices (OLED) constituting the panel. Will do.

A display means using such an organic EL device (OLED), that is, a driving method for an organic EL display device is largely divided into a passive matrix method and an active matrix method. It is a method of driving by applying a current to the selected cathode line and anode line, and the active matrix method integrates a thin film transistor (TFT) and a capacitor (Cst) in each pixel to maintain the voltage by the capacitor capacity. to be.

In the recent display panel market, the demand for various display panels using OLED as well as LCD is gradually increasing, and the trend of display panels becoming larger and higher resolution in accordance with the needs of users continues. In order to drive a large, high-resolution display panel that responds to the user's demand, the driving capability of the panel must be increased. In addition, the number of channels is increased to drive large and high-resolution panels, and in order to achieve high-resolution and large-sized display panels, the number of data that can be processed by the panel driving circuit must be increased. As the driving capability required in the display driving circuit needs to be increased, the power consumed in the panel driving circuit increases due to the increased driving capability.

However, as the power consumption increases, the temperature inside the chip in which the panel driving circuit is implemented increases. The increase in temperature inside the chip degrades the performance of the panel driving circuit and causes an error in an output signal.

Meanwhile, as a means for suppressing an increase in temperature inside the chip as described above, the panel driving circuit may include a precharge means and a charge sharing means. The precharge operation may reduce a burden on driving the panel driving circuit by pre-charging by applying a predetermined voltage to the channel line before transmitting the output voltage according to the data signal from the panel driving circuit.

However, in general, since a voltage applied to a channel line (hereinafter, a precharge voltage) when performing a precharge operation uses a fixed voltage of a constant size, there is a problem that excessive energy consumption is caused in the entire circuit. In addition, due to the fixed pre-charge voltage (Vpre-c), the change in the characteristics of the display panel could not be reflected, and accordingly, it was impossible to optimize the heat generation characteristics of the driver IC. If an inappropriate precharge voltage Vpre-c is applied to the data voltage Vdata, a screen abnormality may occur when the display panel is driven. However, in the conventional case, since the means for improving the above-described problem was not provided, there was a defect in the precharge operation.

The present invention was conceived to solve the conventional problem, and the problem to be solved by the present invention is to compensate in real time by sensing the characteristic change of the driving transistor included in each pixel outside the pixel, and the compensation value for the characteristic change An object of the present invention is to provide an organic light emitting display device capable of varying a precharge voltage according to an applied data output voltage and a driving method thereof.

In order to solve the above problems, the organic light emitting diode display of the present invention includes: a display panel including a plurality of pixels having driving transistors for emitting light emitting elements according to a data output voltage; A panel characteristic sensing unit for generating sensing data by sensing a characteristic of a driving transistor including at least one of a threshold voltage and a mobility of the driving transistor; A panel characteristic value storage unit for storing the sensed panel characteristic value; A comparison unit comparing the previous panel characteristic value stored in the panel characteristic value storage unit with the panel characteristic of the current frame; A precharge voltage calculator that calculates a precharge voltage according to the sensed panel characteristic value; A precharge voltage value storage unit for storing the calculated precharge voltage; A control unit for selecting a precharge voltage according to the comparison result of the comparison unit; And a data voltage generator reflecting the selected precharge voltage.

In order to achieve the above-described technical problem, a driving method of an organic light emitting diode display device according to another aspect of the present invention senses a characteristic of a driving transistor including at least one of a threshold voltage and a mobility of the driving transistor. Sensing and storing panel characteristics; Sensing the panel characteristic and comparing it with a previously stored panel characteristic value of a previous frame; Calculating and storing an appropriate precharge power according to the sensed panel characteristics; Selecting a precharge voltage of the current frame and a precharge voltage of a previous frame stored in advance according to the comparison result; Generating a data voltage by reflecting the selected precharge voltage; And applying the data voltage to the panel.

The organic light emitting diode display and its driving method according to the present invention have the effect of improving heat generation by optimizing the heat generation of the driver IC by varying the output level of the precharge voltage according to the change in the characteristics of the display panel, and also changing the characteristics of the display panel. There is an effect of improving image quality by preventing screen abnormalities such as noise that may occur when a fixed precharge voltage is applied that does not take into account.

1 is a diagram schematically illustrating an organic light emitting display device according to an exemplary embodiment of the present invention.
2 is a diagram illustrating a configuration of an organic light emitting diode display according to the present invention.
3 is a circuit diagram illustrating the pixel structure shown in FIG. 2.
4 is a waveform diagram illustrating a driving waveform in a first or second sensing section as an example.
5 is a graph showing a voltage change of a data voltage according to a conventional precharge operation.
6 is a graph showing a voltage change of a data voltage according to a precharge operation according to an embodiment of the present invention.
7 is a block diagram schematically showing the configuration of a timing controller according to the first embodiment of the present invention.
8 is a block diagram schematically showing the configuration of a timing controller according to a second embodiment of the present invention.
9 is a diagram for adjusting a luminance value according to an image in the image analysis unit of the present invention.

Hereinafter, specific details for carrying out the present invention will be described with reference to the accompanying drawings.

1 is a block diagram schematically showing the configuration of a panel driving unit 2 according to an embodiment of the present invention. The OLED display shown in FIG. 1 includes a timing controller 1, a panel driver 2, and a display panel 3. A key technical feature of the present invention is achieved through the timing controller 1, which is a conceptual name that does not refer to a specific device, but collectively refers to a functional part for performing the operation of the present invention. Therefore, even if there are representations of blocks for performing other functions in the drawings or detailed description of the invention, these are not all integrated in the timing controller 1 in the present invention.

In addition, FIG. 2 is a block diagram of an OLED display device according to an exemplary embodiment, and FIG. 3 is a circuit diagram illustrating a pixel structure illustrated in FIG. 2.

Here, the panel driver 2 is further divided into a data driver 21, a gate driver 22, and a driving voltage supply unit 23. In the OLED display shown in FIG. 1, in order to increase the charging efficiency of the data voltage Vdata applied to the plurality of pixels P of the display panel 3, the precharge voltage Vpre-c is applied to the data line DL. After supplying to, the data voltage Vdata is supplied to the data line DL. In particular, the embodiment compensates the data voltage Vdata according to a change in panel characteristics such as a threshold voltage Vth or mobility, and compensates for the precharge voltage Vpre− according to the degree to which the data voltage Vdata is compensated. The charging efficiency of the data voltage (Vdata) is maximized by varying and supplying c).

The display panel 3 includes a plurality of gate lines GL and a plurality of data lines DL. The gate line GL and the data line DL cross each other to define a pixel area. A plurality of pixels P connected to the gate line GL and the data line DL are provided in each pixel area.

Each of the plurality of pixels P receives a precharge voltage Vpre-c and a data voltage Vdata provided from the data line DL in response to a scan pulse Scan provided from the gate line GL, and receives the data voltage. Generates light corresponding to (Vdata).

To this end, each of the plurality of pixels P may include an OLED and a pixel driving circuit PC for driving the OLED, as shown in FIG. 3.

The display panel 3 receives the data voltage Vdata. The data voltage Vdata is a plurality of gate line groups (G1 to Gm) crossing each other, a plurality of data lines (D1 to Dn), and a plurality of sensing lines (M1 to Mm) parallel to the plurality of data lines (D1 to Dn). ) Is formed in a pixel area defined by.

First, each of the data voltages Vdata includes a pixel driving circuit PC and an organic light emitting diode OLED. In this case, each of the data voltages Vdata may be any one of a red pixel, a green pixel, a blue pixel, and a white pixel. One unit pixel displaying one image may include adjacent red pixels, green pixels, and blue pixels, or adjacent red pixels, green pixels, blue pixels, and white pixels.

In an embodiment, the pixel driving circuit PC may include a first switching transistor ST1, a second switching transistor ST2, a driving transistor DT, and a capacitor Cst. Here, the transistors ST1, ST2, and DT are N-type thin film transistors TFT and may be a-Si TFT, poly-Si TFT, oxide TFT, organic TFT, or the like. The first switching transistor ST1 includes a gate electrode connected to the first gate line Gla, a first electrode connected to an adjacent data line Di, and a first node n1 that is a gate electrode of the driving transistor DT. And a second electrode connected to. The first switching transistor ST1 applies the data voltage Vdata supplied to the data line Di according to the gate-on voltage level supplied to the first gate line GLA to the first node n1, that is, the driving transistor ( DT) to the gate electrode.

The second switching transistor ST2 includes a gate electrode connected to the second gate line GLb, a first electrode connected to an adjacent sensing line Mi, and a second node n2 that is a source electrode of the driving transistor DT. And a second electrode connected to. The second switching transistor ST2 applies a second reference voltage Vref (or precharging voltage Vpre) supplied to the sensing line Mi according to the gate-on voltage level supplied to the second gate line GLb. It is supplied to the node n2, that is, the drain electrode of the driving transistor DT.

The capacitor Cst includes a gate electrode and a source electrode of the driving transistor DT, that is, first and second electrodes connected between the first and second nodes n1 and n2. The capacitor Cst charges a voltage difference between the voltages supplied to each of the first and second nodes n1 and n2, and then switches the driving transistor DT according to the charged voltage.

The driving transistor DT includes a gate electrode commonly connected to the second electrode of the first switching transistor ST1 and the first electrode of the capacitor Cst, and the first electrode and the capacitor Cst of the second switching transistor ST2. And a source electrode commonly connected to the second electrode and the organic light emitting diode OLED, and a drain electrode connected to the first power line VDD. The driving transistor DT is turned on by the voltage of the capacitor Cst to control the amount of current flowing from the first power line VDD to the organic light emitting diode OLED.

In the above-described embodiment, it has been described that the pixel circuit PC includes three transistors and one capacitor, but the number of transistors and capacitors constituting the pixel circuit PC may be variously modified.

The organic light emitting diode OLED emits monochromatic light having a luminance corresponding to the data current Ioled by emitting light by the data current Ioled supplied from the pixel driving circuit PC, that is, the driving transistor DT. To this end, the organic light emitting diode OLED is formed on an anode electrode (not shown) connected to the second node n2 of the pixel driving circuit PC, an organic layer (not shown) formed on the anode electrode, and an organic layer. It includes a cathode electrode (not shown) to which the cathode power VSS is supplied.

In this case, the organic layer may be formed to have a structure of a hole transport layer/organic emission layer/electron transport layer or a hole injection layer/hole transport layer/organic emission layer/electron transport layer/electron injection layer. Furthermore, the organic layer may further include a functional layer for improving the luminous efficiency and/or lifespan of the organic emission layer. In addition, the cathode electrode may be formed individually on each of the plurality of pixels P, or may be formed to be commonly connected to the plurality of pixels P.

Each of the plurality of gate line groups G1 to Gm is formed in parallel along the first direction of the display panel 110, for example, in the horizontal direction. In this case, each of the plurality of gate line groups G1 to Gm includes first and second gate lines GLa and GLb adjacent to each other. Different first and second gate signals GSa and GSb are individually supplied from the panel driver 2 to the first and second gate lines GLa and GLb of each of the gate line groups G1 to Gm. .

Each of the plurality of data lines D1 to Dn is formed in parallel along the second direction of the display panel 110, for example, a vertical direction to cross each of the plurality of gate line groups G1 to Gm. The data voltage Vdata is individually supplied to each of the data lines D1 to Dn through the panel driver 2.

In one embodiment, the data voltage Vdata supplied to each pixel P through the plurality of data lines D1 to Dn is data in which the characteristic of the driving transistor DT included in the pixel P is compensated. It can be a voltage. In this case, the characteristic of the driving transistor DT includes at least one of a threshold voltage Vth of the driving transistor DT and a mobility of the driving transistor DT.

Each of the plurality of sensing lines M1 to Mn is formed in parallel with each of the plurality of data lines D1 to Dn. The reference voltage Vref is supplied from the panel driver 2 to each of the sensing lines M1 to Mn. At this time, the reference voltage Vref is supplied to each sensing line M1 to Mn during the data charging period of each pixel P, and the precharging voltage Vpre is the threshold of the driving transistor DT of each pixel P. The sensing lines M1 to Mn are supplied to the sensing lines M1 to Mn during some of the first sensing periods for sensing at least one of the voltage Vth and the mobility, or during some of the second sensing periods.

Driving power having a first voltage level is supplied from the driving voltage supply unit 23 to the first power line VDD, and a second voltage level lower than the first voltage level from the driving voltage supply unit 23 is supplied to the second power line VSS. A driving power supply having a voltage level is supplied.

The data driver 21 is connected to a plurality of data lines D1 to Dn and operates under the control of the timing controller 20. Specifically, the data driver 21 may drive each pixel P in the data charging period and the light emission period during the first or second display period. In addition, the data driver 122 may drive each pixel P during the first or second sensing period in an initialization period, a sensing voltage charging period, and a voltage sensing period.

During the first or second display period, the data driver 21 supplies the reference voltage Vref to the sensing lines M1 to Mn for each data charging period of each pixel P and is simultaneously supplied from the timing controller 126. The input image DATA is converted into a data voltage Vdata and supplied to the data lines D1 to Dn.

During the first or second display period, the data driver 21 supplies the precharging voltage Vpre to the sensing lines M1 to Mn for each sensing period and at the same time, the sensing data DATA supplied from the timing controller 20 Is converted into a sensing data voltage Vdata and supplied to the corresponding data lines D1 to Dn. Thereafter, the data driver 21 applies a voltage corresponding to the current flowing through the driving transistor DT of each pixel P by the precharging voltage Vpre and the sensing data voltage Vdata, respectively, from the sensing lines M1 to Mn. Each sensing line (M1 to Mn) is floated to be charged in ). Thereafter, the data driver 122 senses the voltage charged in each of the sensing lines M1 to Mn, and applies the sensed voltage to the threshold voltage Vth and mobility of the driving transistor DT of each pixel P. ) Is converted into sensing data Dsen corresponding to) and provided to the timing controller 21.

4 is a waveform diagram illustrating an example of a driving waveform in a first or second sensing section. An operation of one pixel P shown in FIG. 7 will be described in connection with FIG. 4 with FIGS. 6 and 7 as follows.

First, the panel driver 2 controls the driving timings of the data driver 21 and the gate driver 22, respectively, to set the pixel P to an initialization period (t1), a sensing voltage charging period (t2), and a voltage sensing. It is driven in the period t3.

In the initialization period t1, the gate driver 22 supplies the first and second gate signals GSa and GSb of the gate-on voltage level to the first and second gate lines GSa and GSb, and the data driver 22 The sensing data voltage Vdata converted from the sensing data DATA by 122 is supplied to the data line Di and the precharging voltage Vpre is supplied to the sensing line Mi. Accordingly, each of the first and second switching transistors ST1 and ST2 of each pixel P is turned on by the first and second gate signals GSa and GSb of the gate-on voltage level, and thus the first node ( The data voltage Vdata is supplied to n1), and the voltage of the second node n2 is initialized to a precharging voltage Vpre, so that the difference between the data voltage Vdata and the precharging voltage Vpre is applied to the capacitor Cst. (Vdata-Vpre) is charged.

Subsequently, in the sensing voltage charging period t2, the first and second gate signals GSa and GSb of the gate-on voltage level are supplied to the first and second gate lines GSa and GSb according to the gate driver 22. When the data driver 21 is driven, the sensing data voltage Vdata is continuously supplied to the data line Di and the sensing line Mi is floated. Accordingly, in the sensing voltage charging period t2, the driving transistor DT is turned on by the sensing data voltage Vdata, and a voltage corresponding to the current flowing through the turned-on driving transistor DT is floating. Is charged to the sensing line (Mi) of In this case, a voltage corresponding to the threshold voltage Vth, which is one of the characteristics of the driving transistor DT, is charged in the sensing line Mi.

Subsequently, in the voltage sensing period t3, the gate driver 22 supplies the first gate signal GSa of the gate-off voltage level to the first gate line GSa and the second gate signal of the gate-on voltage level. (GSb) is supplied to the second gate line GSb, and the floating sensing line Mi is connected to the data driver 122 again. Accordingly, during the voltage sensing period t3, the data driver 122 senses the voltage charged in the connected sensing line Mi, and corresponds to the sensed voltage, that is, the threshold voltage Vth of the driving transistor DT. The resulting voltage is converted into sensing data Dsen and provided to the timing controller 1.

On the other hand, the timing controller 1 senses the threshold voltage Vth of the driving transistor DT of each pixel P in the first or second sensing period, and then detects the threshold voltage Vth of the driving transistor DT of each pixel P. Sensing can be performed again to sense the mobility. In this case, the timing controller 1 performs the same sensing process as described above, but the first switching transistor ST1 of each pixel P is turned on only during the initialization period t1 and the sensing data voltage Vdata Each of the data driver 21 and the gate driver 22 is controlled so that) is supplied only during the initialization period t1.

Accordingly, when sensing is re-performed, in the sensing voltage charging period t2, the voltage of the capacitor Cst increases as the gate-source voltage of the driving transistor DT increases due to the turn-off of the first switching transistor ST1. As a result, the gate-source voltage of the driving transistor DT is maintained so that a voltage corresponding to the current flowing through the driving transistor DT, that is, a voltage corresponding to the mobility of the driving transistor DT, is transferred to the floating sensing line Mi. Is charged. And, when the sensing is re-performed, the data driver 21 senses a voltage charged in the sensing line Mi, that is, a voltage corresponding to the mobility of the driving transistor DT, and converts the sensed voltage to sensing data Dsen. It is converted and provided to the timing controller 1.

5 is a graph showing a voltage change of a data voltage Vdata according to a conventional precharge operation. In the illustrated section A, a precharge section in which a precharge voltage Vpre-c fixed at a constant voltage level is supplied in advance before being transmitted to an output voltage according to a data signal is indicated. Thereafter, an operation for providing a voltage according to the data signal to the panel in the illustrated section B is performed. As an example, for the data voltage Vdata, which is currently in the 0V voltage level, if the preset precharge voltage Vpre-c is 6V and the voltage level of the data signal for implementing the gradation of the panel is 14V, section A A precharge operation is performed at, and a voltage change is performed to a voltage level of 6V, and a voltage change of the remaining 8V is performed to make 14V, which is the voltage level of the final data signal, in section B.

On the other hand, FIG. 6 is a graph showing a voltage change of a data voltage Vdata according to a precharge operation according to an embodiment of the present invention. The steps of applying the precharge voltage Vpre-c and the residual data voltage Vdata, respectively, in the illustrated section A and section B are the same. However, in the step of applying the pre-charge voltage (Vpre-c) voltage, the pre-charge voltage (Vpre-c) is not a pre-fixed value, but is free as the data output voltage (Voutput) varies according to the compensation value. The charge voltage Vpre-c also shows a variable range C that can be variable.

7 is a block diagram schematically showing the configuration of a timing controller according to the first embodiment of the present invention.
In the timing controller 1 of FIG. 7, the panel characteristic sensing unit 10 senses the panel characteristic, that is, the threshold voltage Vth and the mobility of the driving transistor DT, and the panel characteristic sensing unit (10) transmits the panel characteristic information sensed from the panel characteristic sensing unit 10 to the comparison unit 14, and the comparison unit 14 compares the previous panel characteristic value stored in the panel characteristic value storage unit 11 Determine whether they are the same or have changed. Accordingly, the precharge voltage calculation unit 12 for determining the variable amount of the precharge voltage Vpre-c and the comparison unit 14 among the previous precharge voltage values stored in the precharge voltage value storage unit 13. When there is a change in the panel characteristic value received from the precharge voltage calculation unit 12, the precharge voltage Vre-c of the current frame calculated by the data output voltage generation unit 16 is transferred to the data output voltage generation unit 16, and the comparison unit ( When there is no change in the panel characteristic value received from 14), the previous precharge voltage value stored in the precharge voltage value storage unit 13 is transferred to the data output voltage generator 16.

8 is a block diagram schematically showing the configuration of the timing controller 1 according to the second embodiment of the present invention.

Referring to the block diagram of FIG. 8, an image analysis unit 17 has been added to the block diagram of FIG. 7. The image analysis unit 17 further has a technical feature that reflects the change in luminance of the image information to the generation of the precharge voltage Vpre-c. The image analysis unit 17 analyzes image information to be applied to the display panel 3 in the current frame, and affects when the precharge voltage Vpre-c is varied according to Gamma information of the corresponding frame.

9 is a graph illustrating acquisition of Gamma information according to a Max luminance value of a corresponding frame using the image analysis unit 17 of FIG. 8.

This may be obtained by utilizing known technologies such as a peak luminance control (PLC) technology and an adaptive peak luminance (APL) technology known in the art, and a separate algorithm for this may be used.

A method of varying the precharge voltage Vpre-c in consideration of image analysis information will be briefly described with reference to FIGS. 8 and 9.

The image analysis unit 17 analyzes image information of the current frame and acquires Gamma information according to the Max luminance value of the frame. Based on this Gamma information, it is possible to set the variable range of the maximum voltage or minimum voltage of the data voltage (Vdata) by utilizing the conventionally known technologies such as PLC (Peak Luminance Control) technology and APL (Adaptive Peak Luminance) technology. According to the variation of (Vdata), the precharge voltage (Vpre-C) may be varied at the same rate.

Therefore, by setting the precharge voltage Vpre-c in consideration of the amount of change in luminance for the image information, the most optimized precharge voltage Vpre-c can be applied. This can optimize the heat generation of the driver IC, thereby improving heat generation, and improving image quality by preventing screen abnormalities such as noise.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention. It will be obvious to those who have the knowledge of.

1: timing controller 2: panel drive
3: display panel 10: panel characteristic sensing unit
11: panel characteristic value storage unit 12: precharge voltage calculation unit
13: pre-charge??value storage unit 14: comparison unit
15: control unit 16: data voltage generation unit
21: data driver 23: gate driver
24: driving voltage generator

Claims (9)

A display panel having a plurality of pixels;
A pixel driving circuit including a driving transistor inside the pixel to drive the pixel;
A timing controller controlling driving of the display panel; And
A panel driver receiving a control signal from the timing controller and applying it to the display panel,
The timing controller senses at least one of a threshold voltage or mobility of the driving transistor to find a compensation value, and accordingly varies a precharge voltage,
The timing controller is
A panel characteristic sensing unit for sensing panel characteristics;
A panel characteristic value storage unit for storing the sensed panel characteristic;
A precharge voltage calculator configured to set a precharge voltage in consideration of a change in the panel characteristic;
A precharge voltage storage unit for storing the set precharge voltage;
A comparison unit comparing the panel characteristics of a current frame and a previous frame;
A control unit for selecting the precharge voltage according to the comparison result of the comparison unit; And
And a data voltage generator configured to generate a data voltage by reflecting the selected precharge voltage.
delete The method of claim 1,
The panel characteristic sensing unit senses at least one of a threshold voltage or mobility of a driving transistor in a pixel, and stores the same in the panel characteristic value storage unit,
The comparison unit compares the panel characteristics of the current frame sensed by the panel characteristic sensing unit and the panel characteristics of the previous frame stored in the panel characteristic value storage unit and transmits the comparison to the control unit,
The precharge voltage calculator calculates a precharge voltage according to the panel characteristic value sensed by the panel characteristic sensing unit, and stores it in a precharge voltage value storage unit,
The control unit selects between a precharge voltage of a current frame and a precharge voltage of a previous frame stored in a precharge voltage value storage unit according to a result of the comparison unit,
The data voltage generator generates a data voltage by reflecting a precharge voltage value selected by the control unit.
The method of claim 1 or 3,
The timing controller further comprises an image analysis unit for transferring image analysis information to the precharge voltage calculation unit.
The method of claim 4,
The image analysis unit analyzes the image information of the current frame, obtains gamma information according to the maximum luminance value of the frame, and transmits it to the precharge voltage calculator,
The data voltage generator further considers the image information to vary the maximum voltage or the minimum voltage of the data voltage Vdata,
The precharge voltage calculation unit is characterized in that the data voltage generation unit further considering the image information changes the precharge voltage Vpre-C at the same rate as the maximum voltage or the minimum voltage of the data voltage Vdata is varied. Organic LED display
Sensing and storing a panel characteristic of an organic light emitting diode display;
Sensing the panel characteristic and comparing it with a previously stored panel characteristic value of a previous frame;
Calculating and storing a precharge voltage according to the sensed panel characteristics;
Selecting a precharge voltage of a current frame and a precharge voltage of a previous frame stored in advance according to a comparison result of the sensed panel characteristic and the stored panel characteristic value;
Generating a data voltage by reflecting the selected precharge voltage; And
A driving method of an organic light emitting diode display comprising applying the data voltage to a panel
The method of claim 6,
Analyzing image data of a current frame to obtain gamma information according to a maximum luminance value of the frame;
Varying a maximum voltage or a minimum voltage of the data voltage Vdata according to the obtained gamma information;
The method of driving an organic light emitting diode display further comprising: varying the precharge voltage Vpre-C at the same ratio as the maximum voltage or the minimum voltage of the data voltage Vdata is varied.

A display panel having pixels;
A pixel driving circuit disposed inside the pixel and including a driving transistor;
A timing controller controlling driving of the display panel; And
Panel driver receiving a control signal from the timing controller and applying it to the display panel
Including,
The timing controller,
Select the precharge voltage of the current frame and the precharge voltage of the previous frame stored in advance according to the result of comparing the sensed panel characteristic and the panel characteristic value of the previous frame stored in advance,
An organic light emitting diode display that generates a data voltage by reflecting the selected precharge voltage
The method of claim 8,
The panel characteristic is at least one of a threshold voltage and a mobility of the driving transistor.

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