KR102363842B1 - Orgainc light emitting diode display device and sensing method thereof - Google Patents

Abstract

The present invention provides an OLED display device capable of improving compensation performance by minimizing a leakage current of a sub-pixel during a sensing period, and a sensing method thereof.
The OLED display device according to an embodiment sequentially senses a plurality of subpixels sharing a reference line in a sensing mode while sequentially sensing each of the plurality of subpixels through a reference line sharing driving characteristics. Each sensing mode period for each of the plurality of subpixels sharing the reference line includes a first initialization period, a driving and sensing period, and a second initialization period. In the first initialization period, the plurality of sub-pixels are initialized by receiving the first reference voltage supplied from the data driver through the reference line. In the driving and sensing period, any one of the plurality of sub-pixels is driven by receiving the sensing data voltage supplied to the corresponding data line from the data driver, and is sensed through the reference line. In the second initialization period, the plurality of sub-pixels are initialized by receiving a second reference voltage greater than the first reference voltage from the data driver through the reference line.

Description

Organic light emitting diode display and sensing method thereof

The present invention relates to an organic light emitting diode display capable of improving compensation performance by minimizing a leakage current of a subpixel during a sensing period, and a sensing method thereof.

Recently, as a display device that displays an image using digital data, a liquid crystal display (LCD) using liquid crystal, an OLED display using an organic light emitting diode (OLED), and electrophoretic particles are used. An electrophoretic display (EPD), etc. used is a representative example.

Among them, the OLED display is a self-luminous device that emits light from an organic light emitting layer by recombination of electrons and holes, and is expected as a next-generation display device because of its high luminance, low driving voltage, and ultra-thin film formation.

In the OLED display device, each sub-pixel includes an OLED element and a pixel circuit independently driving the OLED element. The pixel circuit controls the brightness of the OLED device by controlling the current Ids at which a driving thin film transistor (hereinafter, TFT) drives the OLED device according to the driving voltage Vgs corresponding to the data signal.

In OLED display devices, the characteristics of each sub-pixel are non-uniform due to the threshold voltage (Vth) and mobility of the driving TFT that vary depending on process deviation, driving environment, driving time, etc. Therefore, a luminance non-uniformity phenomenon may occur.

To solve this problem, the OLED display device senses the characteristic value of each sub-pixel, determines and stores a compensation value for compensating for characteristic deviation of each sub-pixel based on the sensing result, and stores each sub-pixel using the stored compensation value. An external compensation technique that compensates the data to be supplied to the pixel is mainly used.

The OLED display supplies a reference voltage to the driving TFT of each sub-pixel through a reference line disposed in a pixel array, and senses a characteristic of each sub-pixel through the reference line. Each reference line may be shared by subpixels of a plurality of columns. In the sensing period of each horizontal line, a plurality of subpixels sharing each reference line may be sequentially sensed through the shared reference line.

However, when any one of the plurality of subpixels sharing the reference line is sensed in the sensing period of each horizontal line, leakage current may occur in the remaining subpixels that are not sensed. The generated leakage current flows into the shared reference line and may be included as an error component in the sensing signal of the sub-pixel, and since it also affects the compensation value detected from the sensing signal, the compensation value for each sub-pixel may be distorted. .

As a result, when each sub-pixel is driven using the compensation value distorted by the leakage current of another sub-pixel, the degree of compensation of each sub-pixel is reduced or excessive, resulting in image quality defects such as horizontal and vertical lines on the low-grayscale screen. .

The present invention provides an OLED display device capable of improving compensation performance by minimizing a leakage current of a sub-pixel during a sensing period, and a sensing method thereof.

An OLED display device according to an exemplary embodiment includes a display panel and a data driver. The display panel includes a plurality of subpixels that are individually connected to the plurality of data lines and share a reference line disposed between the plurality of data lines. The data driver sequentially drives the plurality of subpixels sharing the reference line in the sensing mode, and sequentially senses the plurality of subpixels through the reference line sharing driving characteristics of each of the subpixels.

Each sensing mode period for each of the plurality of subpixels sharing the reference line includes a first initialization period, a driving and sensing period, and a second initialization period. In the first initialization period, the plurality of sub-pixels are initialized by receiving the first reference voltage supplied from the data driver through the reference line. In the driving and sensing period, any one of the plurality of sub-pixels is driven by receiving the sensing data voltage supplied to the corresponding data line from the data driver, and is sensed through the reference line. In the second initialization period, the plurality of sub-pixels are initialized by receiving a second reference voltage greater than the first reference voltage from the data driver through the reference line.

In the first initialization period, the plurality of sub-pixels receive a data initialization voltage from each data line and receive a first reference supply from the reference line to initialize the driving TFT. In the second initialization period, the plurality of sub-pixels receive a data initialization voltage from each data line and receive a second reference voltage from the reference line to apply a reverse bias to the driving TFF.

The second initialization period includes first to third periods. In the first period, when the first and second switching TFTs of the plurality of subpixels are turned on, the data initialization voltage supplied through the corresponding data line is applied to the gate node of the driving TFT of the plurality of subpixels. In the second period, the first and second switching TFTs of the plurality of subpixels are turned off. In the third period, the second switching TFT of the plurality of subpixels is turned on, and a second reference voltage supplied through the reference line is applied to the source node of the driving TFT of the plurality of subpixels.

In the pixel array, the sensing period of each horizontal line sequentially drives a plurality of subpixels sharing a reference line in a sensing mode, while sequentially sensing a plurality of subpixels that are sensed through a reference line sharing driving characteristics of each of the plurality of subpixels. A sensing mode period for each of the sub-pixels is included, and each sensing mode period includes the above-described first initialization period, driving and sensing period, and second initialization period.

In one embodiment, when sequentially sensing a plurality of sub-pixels sharing each reference line during the sensing period of each horizontal line, all driving TFTs of the corresponding horizontal line are reverse-biased whenever sensing of each sub-pixel is completed. By initialization, the leakage current of the driving TFT can be minimized, and as a result, the error component of the sensing signal can be minimized.

As a result, according to an exemplary embodiment, by detecting a more accurate compensation value from a sensing signal having a minimized error component and accurately compensating for driving characteristics of each sub-pixel, compensation performance can be improved, and image quality defects such as horizontal lines and vertical lines can be prevented. there is.

1 is a block diagram schematically showing the configuration of an OLED display device according to an embodiment of the present invention.
FIG. 2 is an equivalent circuit diagram illustrating the configuration of the subpixel shown in FIG. 1 .
3 is a diagram schematically illustrating a sensing device for four sub-pixels sharing a reference line according to an embodiment of the present invention.
FIG. 4 is a driving waveform diagram illustrating a sensing mode period of any one subpixel among the subpixels shown in FIG. 3 , according to an exemplary embodiment.
5 is a driving waveform diagram illustrating a sensing mode period of one sub-pixel according to the prior art.

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

1 is a block diagram schematically showing the configuration of an OLED display device according to an embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram illustrating the configuration of one sub-pixel shown in FIG. 1 .

Referring to FIG. 1 , an OLED display device according to an embodiment includes a display panel 100 , a gate driver 200 , a data driver 300 , a timing controller 400 , a memory 500 , a power supply unit 600 , and the like. include

In the memory 500 , compensation information for each subpixel may be stored along with various control information to be used by the timing controller 400 , and may be updated through a sensing mode. That is, compensation information for each sub-pixel stored in the memory 500 may be determined according to a result of sensing the characteristics of each sub-pixel before product shipment and stored in the memory 500 , and after product shipment, The update may be performed using a sensing result of each subpixel obtained through a real-time sensing operation during the driving process. For example, the compensation information of each sub-pixel includes a mobility compensation value of each sub-pixel for compensating for a mobility deviation of the driving TFT between sub-pixels, a Vth compensation value of each sub-pixel for compensating for Vth of the driving TFT, etc. may include

The timing controller 400 receives image data and timing control signals from an external system. The system may be any one of a computer, a TV system, a set-top box, a system of a portable terminal such as a tablet or a mobile phone. The timing control signals may include a dot clock, a data enable signal, a vertical synchronization signal, a horizontal synchronization signal, and the like. The system may instruct the timing controller 400 to instruct the sensing mode so that the OLED display device operates in the sensing mode, and when the sensing operation is completed in the OLED display device, a sensing completion signal may be supplied from the timing controller 400 .

The timing controller 400 generates data control signals and gate control signals for controlling driving timings of the data driver 300 and the gate driver 200, respectively, using the timing control signals, and generates the data driver 300 and the gate driver ( 200) is supplied.

The timing controller 400 compensates data to be supplied to each subpixel SP using compensation information (compensation data) stored in the memory 500 , and supplies the compensated data to the data driver 300 .

The timing controller 400 may further perform various image processing for compensating for deterioration of the OLED device and reducing power consumption. For example, the timing controller 400 may use a result of the accumulation of image data or calculate the degree of deterioration of the pixel array using sensing information of each sub-pixel SP, and adjust the image luminance using the result of the calculation. . The timing controller 400 may calculate an average picture level (hereinafter, referred to as APL) through frame-by-frame image analysis and adjust image luminance to reduce power consumption by using the APL. In addition, the timing controller 400 calculates a total current predicted value through frame-by-frame image analysis, and calculates an automatic current limit (ACL) that limits the current so that the total current predicted value does not exceed a predetermined reference value, and sets the ACL. image brightness can be adjusted to further reduce power consumption.

In the sensing mode, the timing controller 400 controls the OLED display device to operate in the sensing mode, and through the data driver 300 , the characteristics (Vth of the driving TFT, mobility) of each sub-pixel of the display panel 100 . , Vth of OLED, etc.) and using the sensing result, compensation information for each sub-pixel stored in the memory 500 may be updated.

For example, the timing controller 400 detects the amount of change in the mobility of the driving TFT sensitive to the driving environment such as temperature and light by using information sensed in a linear section in which the source voltage is increased by driving the driving TFT in each sub-pixel. It is calculated, and the mobility compensation value of each subpixel stored in the memory 500 may be updated using the calculation result. Since the sensing mode for updating the mobility compensation value operates in the fast mode, which takes a relatively short time, the sensing mode (ON RF) mainly allocated to the power-on period and the vertical blank period of each frame during the display period It may be performed in at least one of the sensing modes (RT) assigned to .

In addition, the timing controller 400 senses the Vth of the driving TFT using information sensed in a section in which the driving TFT is driven in each sub-pixel and the source voltage reaches the saturation state, and stores the Vth of the driving TFT in the memory 500 using the sensing result. The stored Vth compensation value of each sub-pixel may be updated. The Vth compensation value can compensate for the Vth deviation of the driving TFT between sub-pixels and also compensate for the shifted Vth due to deterioration due to electrical stress as the driving time elapses. Since the sensing mode for updating the Vth compensation value operates in a slow mode that takes a longer sensing time than the aforementioned fast mode, it may be mainly performed in the sensing mode OFF RS allocated to the power-off period.

The data driver 300 converts the data supplied from the timing controller 400 into an analog data signal by using the data control signal supplied from the timing controller 400 in each of the display mode and the sensing mode, and converts the data signal to the display panel ( 100) is supplied. The data driver 300 converts digital data into analog data voltages using the gamma voltage set supplied from the gamma voltage generator.

The data driver 300 drives each subpixel by supplying a data voltage for sensing to a data line in a sensing mode under the control of the timing controller 400 , and the characteristics of the driven subpixel SP (Vth of the driving TFT, Mobility, Vth of OLED, etc.) is sensed as a voltage through the reference line REF, and the pixel current is converted into sensing information (sensed data) of each sensed sub-pixel SP and provided to the timing controller 400 .

The data driver 300 is composed of at least one data driving IC and is mounted on a circuit film such as a tape carrier package (TCP), a chip on film (COF), a flexible print circuit (FPC), etc., and the TAB on the display panel 100 . It may be attached using a tape automatic bonding method or may be mounted on a non-display area of the display panel 100 using a chip on glass (COG) method.

The gate driver 200 drives a plurality of gate lines of the display panel 100 using a gate control signal supplied from the timing controller 400 . The gate driver 200 supplies a gate-on voltage pulse to the corresponding gate line in the corresponding driving period of each gate line using the gate control signal, and supplies the gate-off voltage in the remaining period.

The gate driver 200 may include at least one gate driving IC and may be mounted on a circuit film and attached to the display panel 100 in a TAB method, or may be mounted on a non-display area of the panel 10 in a COG method. Alternatively, the gate driver 200 may be formed in the non-display area of the TFT substrate together with the TFT array formed in the pixel array of the panel 10 to be formed in a GIP (Gate In Panel) type built into the panel 10 . there is.

The power supply unit 600 generates and outputs various driving voltages (EVDD, EVSS, etc.) necessary for the timing controller 400 , the gate driver 200 , the data driver 300 , the display panel 100 , and the like by using the input voltage. . For example, the power supply unit 600 includes driving voltages EVDD and EVSS and reference voltages VpreR and VpreS supplied to the display panel 100 through the data driver 300 , the data driver 300 , and the timing controller 400 . ), the driving voltage of the digital circuit supplied to the data driver 300 , the driving voltage of the analog circuit supplied to the data driver 300 , the gate-on voltage (gate high voltage) and the gate-off voltage (gate low voltage) used in the gate driver 200 , etc. can be created and supplied.

The display panel 100 displays an image through a pixel array in which sub-pixels SP are arranged in a matrix form. The basic pixel is at least three sub-pixels (W/R/G, B/W/ R, G/B/W, R/G/B, or W/R/G/B).

Referring to FIG. 2 , each subpixel SP is an OLED connected between a high potential driving voltage (first driving voltage; hereinafter EVDD) line PL and a low potential driving voltage (second driving voltage; hereinafter EVSS) line. A pixel circuit including at least first and second switching TFTs ST1 and ST2, a driving TFT DT, and a storage capacitor Cst for independently driving the device and the OLED device is provided. Meanwhile, various configurations may be applied to the pixel circuit.

The switching TFTs ST1 and ST2 and the driving TFT DT may be an amorphous silicon (a-Si) TFT, a poly-Si TFT, an oxide TFT, or an organic TFT. there is.

The OLED device includes an anode connected to the source node N2 of the driving TFT DT, a cathode connected to the low potential power supply EVSS, and an organic light emitting layer between the anode and the cathode. The anode is independent for each subpixel, but the cathode may be a common electrode shared by all subpixels. In an OLED device, when a driving current is supplied from the driving TFT (DT), electrons from the cathode are injected into the organic light emitting layer, and holes from the anode are injected into the organic light emitting layer. By emitting light, light having a brightness proportional to the current value of the driving current is generated.

The first switching TFT ST1 is driven by the first gate signal SCAN supplied from the gate driver 200 to the first gate line GLn1 and supplied from the data driver 300 to the data line DL. The data voltage Vdata is supplied to the gate node N1 of the driving TFT DT.

The second switching TFT ST2 is driven by the second gate signal SENSE supplied from the gate driver 200 to the second gate line GLn2 and supplied from the data driver 300 to the reference line REF. The reference voltage VpreR is supplied to the source node N2 of the driving TFT DT.

The storage capacitor C connected between the gate node N1 and the source node N2 of the driving TFT DT is connected to the gate node (C) through the first and second switching TFTs ST1 and ST2 turned on during the scan period. The difference voltage between the data voltage Vdata and the reference voltage VpreR respectively supplied to N1) and the source node N2 is charged to the driving voltage Vgs of the driving TFT DT. During the light emission period in which the first and second switching TFTs ST1 and ST2 are turned off, the storage capacitor C maintains the driving voltage Vgs so that the driving TFT DT operates at a driving current Ids determined by the driving voltage Vgs. ) can be continuously supplied to the OLED device.

The driving TFT DT controls the current supplied from the EVDD line PL according to the driving voltage Vgs supplied from the capacitor C, and supplies a driving current proportional to the driving voltage Vgs to the OLED element. light the device.

In the sensing mode, the first switching TFT ST1 drives the driving TFT DT by supplying the sensing data voltage Vdata supplied from the data driver 300 through the data line DL to the driving TFT DT. and the second switching TFT ST2 outputs a pixel current representing the driving characteristics of the driving TFT DT to the reference line REF. Accordingly, a voltage corresponding to the pixel current of the sub-pixel SP is charged in the line capacitor of the reference line REF. The data driver 300 may sense a voltage representing a driving characteristic of each subpixel by sampling a voltage on the reference line REF at a desired sampling time.

Before the sensing mode operation of the sub-pixel, the source node N2 of the driving TFT DT is initialized to the first reference voltage VpreS through the second switching TFT ST2, and after the sensing operation, the second reference voltage (VpreR) is initialized. In this case, the gate node N1 of the driving TFT DT may be initialized to a data initialization voltage through the first switching TFT ST1. The second reference voltage VpreR is a reference voltage used in the display mode and is higher than the first reference voltage VpreS. The data initialization voltage may be, for example, a black data voltage. Accordingly, whenever sensing of each sub-pixel is completed, a reverse bias is applied to the driving TFT DT of each sub-pixel by the second reference voltage VpreR greater than the first reference voltage VpreS, thereby causing leakage of the driving TFT. current can be minimized. At this time, a reverse bias is applied by the second reference voltage VpreR to the driving TFT DT of the subpixel that is not sensed among the subpixels that share the reference line REF on the same horizontal line, so that the subpixel that is not sensed Leakage current can be minimized.

During the sensing period of each horizontal line in the pixel array, a plurality of subpixels sharing the reference line may be sequentially driven and sensed. A sensed subpixel among subpixels sharing a reference line is driven by applying a sensed data voltage through a data line, while data lines of the remaining subpixels that are not sensed may be floated in a state of a previously supplied data initialization voltage. . Due to this, in subpixels that are not sensed, the gate voltage of the driving TFT DT connected to the floating data line is unstable, so that the driving TFT DT is lightly driven, thereby generating a leakage current. Such leakage current may flow into the shared reference line as an error component and distort a sensing signal of a sub-pixel to be sensed next.

To prevent this, an embodiment of the present invention initializes all driving TFTs of the subpixels of the corresponding horizontal line to a reverse bias using the second reference voltage VpreR whenever sensing of each subpixel is completed. It is possible to minimize the leakage current and minimize the error component of the sensing signal.

3 is a diagram illustrating a sensing device for four sub-pixels sharing a reference line according to an embodiment of the present invention.

Referring to FIG. 3 , in the display panel 100 , first to fourth subpixels SP1 , SP2 , and SP3 sharing an m-th (m is a natural number) reference line REFm in an n-th (n is a natural number) horizontal line. , SP4) are representatively shown. The data driver 300 is representative of the reference supply unit 310 and the sensing unit 320 connected to the reference line REFm.

The reference supply unit 310 includes first and second switches SPRE and RPRE connected in parallel with the reference line REFm. The first switch SPRE is switched by the first control signal to supply the first reference voltage VpreS to the reference line REFm. The second switch RPRE is switched by the second control signal to supply the second reference voltage VpreR to the reference line REFm. The first and second control signals may be supplied from the timing controller 400 ( FIG. 1 ).

The sensing unit 320 is connected to the reference line REFm through the sampling switch SAM. The sampling switch SAM is switched by the sampling control signal to sample the sensing voltage of each sub-pixel SP charged on the reference line REFm and supply it to the sensing unit 320 . The sensing unit 320 converts the supplied sensing voltage of each sub-pixel SP into sensing data and supplies it to the timing controller 400 . The sampling control signal may be supplied from the timing controller 400 ( FIG. 1 ).

In the display panel 100 , the first to fourth subpixels SP1 , SP2 , SP3 , and SP4 are individually connected to the first to fourth data lines DL1 , DL2 , DL3 and DL4 , and one reference line ( REFm) in common. The first and second gate lines GLn1 and GLn2 of the n-th horizontal line are commonly connected to the first to fourth subpixels SP1 , SP2 , SP3 , and SP4 .

Each of the first to fourth sub-pixels SP1, SP2, SP3, and SP4 includes the first and second switching TFTs ST1 and ST2, the driving TFT DT, the storage capacitor Cst, as described above with reference to FIG. 2 , respectively. An OLED device is provided. The first to fourth subpixels SP1 , SP2 , SP3 , and SP4 may be subpixels of different colors, ie, an R subpixel, a W subpixel, a B subpixel, and a G subpixel.

The first switching TFTs ST1 of the first to fourth subpixels SP1 , SP2 , SP3 , and SP4 are commonly connected to the first gate line GLn1 and the first gate signal SCAN supplied from the gate driver 200 . ), the switching operation is controlled simultaneously. The second switching TFTs ST2 of the first to fourth subpixels SP1 , SP2 , SP3 , and SP4 are commonly connected to the second gate line GLn2 and the second gate signal SENSE supplied from the gate driver 200 . ), the switching operation is controlled simultaneously.

Before sensing the display panel 100 , all sub-pixels may be initialized with black data by driving the pixel array through the gate driver 200 and the data driver 300 . In the sensing mode of the display panel 100 , the pixel array may be sensed line sequentially.

During the sensing period of the n-th horizontal line, the first to fourth sub-pixels SP1 , SP2 , SP3 , and SP4 are sequentially driven and sequentially sensed through the shared reference line REFm. In other words, the sensing period of the n-th horizontal line includes the sensing mode period of the first subpixel SP1 , the sensing mode period of the second subpixel SP2 , the sensing mode period of the third subpixel SP3 , and the fourth It is time-divided into the sensing mode period of the sub-pixel SP4.

When any one of the first to fourth subpixels SP1 , SP2 , SP3 , and SP4 operates in the sensing mode, the remaining subpixels are turned off. That is, the driving TFT DT of any one of the first to fourth sub-pixels SP1, SP2, SP3, and SP4 receives the sensing data voltage Vdata through the corresponding data line to be driven in the sensing mode. At this time, since the data lines of the remaining sub-pixels are floated and have the previously supplied data initialization voltage (black data voltage), the driving TFTs DT of the remaining sub-pixels are turned off.

FIG. 4 is a diagram illustrating driving waveforms for a sensing mode period of any one of the first to fourth subpixels SP1, SP2, SP3, and SP4 shown in FIG. 3 .

The sensing mode period of any one subpixel shown in FIG. 4 includes a first initialization period 410 , a driving and sensing period 420 , and a second initialization period 430 . Hereinafter, for convenience, the first subpixel SP1 ) for the sensing mode period will be described as an example.

3 and 4 , in the initialization period 410 , the first switch SPRE of the data driver 300 is turned on to supply the first reference voltage VpreS to the reference line REFm. In this case, all of the data lines DL1 to DL4 hold the previous data initialization voltage Vini. In the initialization period 410 , the first and second switching TFTs ST1 and ST2 of the subpixels SP1 , SP2 , SP3 , and SP4 are all turned on by the first and second gate signals SCAN and SENSE. -on, the gate node N1 and the source node N2 of the driving TFT DT are initialized to the data initialization voltage Vini and the first reference voltage VpreS, respectively. A black data voltage may be used as the data initialization voltage Vini. In the first initialization period 410 , the second switch RPRE and the sampling switch SAM of the data driver 300 maintain their previous off states.

In the driving and sensing period 420 following the first initialization period 410 , the sensing data voltage Vdata is supplied from the data driver 300 to any one data line DL1 , and the data driver 300 1 The switch SPRE is turned off so that the reference line REFm is floated. In the driving and sensing period 420 , the first and second switching TFTs ST1 and ST2 maintain a turned-on state by the first and second gate signals SCAN and SENSE. The first switching TFT ST1 of any one sub-pixel SP1 supplies the sensing data voltage Vdata supplied through the corresponding data line DL1 to the gate node N1 of the driving TFT DT for the driving TFT (DT) is driven. The remaining sub-pixels SP2 , SP3 , and SP4 are turned off by the data initialization voltage of the data lines DL2 , DL3 , and DL4 . Since the current representing the driving characteristics of the driving TFT DT of the driven sub-pixel SP1 is supplied to the reference line REFm via the second switching TFT ST2, as the driving time elapses, the reference line REFm is charged. voltage is gradually increased. Subsequently, when the gate-source voltage of the driving TFT DT becomes Vth and becomes saturated, the voltage of the reference line REF maintains a constant saturation state. Next, in the sampling period 422 , the sampling switch SAM of the data driver 300 is turned on to sample and output the voltage charged in the reference line REFm. The sensing unit 320 converts the sensing voltage supplied from the sampling switch SAM into sensing data and supplies it to the timing controller 400 .

In the second initialization period 430 following the driving and sensing period 420 , before the first and second switching TFTs ST1 and ST2 are turned off by the first and second gate signals SCAN and SENSE In the first period 4322 , the data initialization voltage Vini is supplied from the data driver 300 to the corresponding data line DL1 . Accordingly, in the subpixel SP1 operated in the sensing mode, the driving TFT DT is turned off while the gate node N1 is first initialized to the data initialization voltage Vini. At this time, the driving TFT DT of the remaining sub-pixels SP2 , SP3 , and SP4 is in an off state.

Subsequently, in a second period 434 of the second initialization period 430 , the first and second switching TFTs ST1 and ST2 are all turned off by the first and second gate signals SCAN and SENSE to form subpixels. At (SP1, SP2, SP3, SP4), the gate node N1 and the source node N2 of the driving TFT DT are floated.

Next, in a third period 436 of the second initialization period 430 , the second switch RPRE of the data driver 300 is turned on to initialize the reference line REFm with the second reference voltage VpreR. At the same time, the second switching TFT ST2 is turned on by the second gate signal SENSE. Accordingly, the source node N2 of the driving TFT DT is initialized to the second reference voltage VpreR in all of the subpixels SP1 , SP2 , SP3 , and SP4 . At this time, the floating gate node N1 of the driving TFT DT falls from the previous data initialization voltage Vini by the second reference voltage VpreR supplied to the source node N2 (Vini-VpreR). . Accordingly, a reverse bias is applied to all of the driving TFTs DT of the subpixels SP1 , SP2 , SP3 , and SP4 to minimize leakage current. When the second switch RPRE is turned off in the data driver 300 after the third period 436 , the reference line REFm is floated and the second reference voltage VpreR is applied until the next sub-pixel operates in the sensing mode. will hold

The driving waveforms for the sensing mode periods 410 , 420 , and 430 of one subpixel illustrated in FIG. 4 described above are equally applied when sensing the second to fourth subpixels SP2 , SP3 , and SP4 , respectively.

FIG. 5 is a driving waveform diagram of the prior art in contrast to the driving waveform of the embodiment shown in FIG. 4 .

When the second initialization period 430 is omitted from the sensing mode periods 410 , 420 , 430 of one subpixel shown in FIG. 4 according to an embodiment, the same as the driving waveform of the prior art shown in FIG. 5 . In a subsequent period 530 of the driving and sensing period 520 for the subpixel, a leakage current may be generated from another subpixel to vary the voltage of the reference line REFm, which is an error component when sensing the next subpixel. can be included as

To prevent this, in an embodiment, when a plurality of subpixels sharing each reference line are sequentially sensed during a sensing period of each horizontal line, whenever sensing of each subpixel is completed, the second reference voltage VpreR ) to initialize all the driving TFTs of the corresponding horizontal line to reverse bias, the leakage current of the driving TFT can be minimized, and as a result, the error component of the sensing signal can be minimized.

As a result, according to an exemplary embodiment, by detecting a more accurate compensation value from a sensing signal having a minimized error component and accurately compensating for driving characteristics of each sub-pixel, compensation performance can be improved, and image quality defects such as horizontal lines and vertical lines can be prevented. there is.

In the above, it has been shown and described as a specific embodiment to illustrate the technical idea of the present invention, but the present invention is not limited to the same configuration and operation as the specific embodiment as described above, and various modifications do not depart from the technical spirit of the present invention. It can be implemented within the scope. Accordingly, such modifications should be considered to fall within the scope of the present invention, and the scope of the present invention should be determined by the following claims.

100: display panel 200: gate driver
300: data driver 400: timing controller
500: memory 600: power unit
310: reference supply 320: sensing unit

Claims (9)

A display panel comprising: a display panel including a plurality of subpixels that are individually connected to a plurality of data lines and share a reference line disposed between the plurality of data lines;
a data driver that sequentially senses driving characteristics of each of the plurality of subpixels through the reference line while sequentially driving the plurality of subpixels sharing the reference line in a sensing mode;
Each sensing mode period for each of the plurality of subpixels includes a first initialization period, a driving and sensing period, and a second initialization period,
In the first initialization period, the plurality of sub-pixels are initialized by receiving a first reference voltage supplied from the data driver through the reference line;
In the driving and sensing period, any one of the plurality of sub-pixels is driven by receiving a sensing data voltage supplied to a corresponding data line from the data driver and sensed through the reference line;
In the second initialization period, the plurality of sub-pixels are initialized by receiving a second reference voltage greater than the first reference voltage from the data driver through the reference line;
The second initialization period is
a first period in which the data initialization voltage supplied through the data line is supplied to the gate node of the driving TFT of the plurality of sub-pixels;
a second period of disconnecting the data line connected to the gate node of the driving TFT of the plurality of sub-pixels and the reference line connected to the source node of the driving TFT;
and a third period of applying the second reference voltage supplied through the reference line to a source node of a driving TFT of the plurality of subpixels. The method according to claim 1,
Each of the plurality of sub-pixels is
A driving TFT for driving the OLED element;
a first switching TFT controlled by a first gate line shared by the plurality of subpixels and connecting a gate node of the driving TFT to a corresponding data line;
a second switching TFT controlled by a second gate line shared by the plurality of subpixels and connecting a source node of the driving TFT to the reference line;
A gate driver driving the first and second gate lines,
driving the first and second gate lines simultaneously in the first initialization period and the driving and sensing period;
An OLED display for driving the second gate line in the second initialization period. 3. The method according to claim 2,
In the first initialization period, the plurality of subpixels receive a data initialization voltage from each data line and receive the first reference voltage from the reference line to initialize the driving TFT;
In the second initialization period, the plurality of sub-pixels receive the data initialization voltage from each data line and receive the second reference voltage from the reference line to apply a reverse bias to the driving TFT. . 4. The method according to claim 3,
In the driving and sensing period,
any one of the plurality of subpixels is driven by receiving the sensing data voltage from the corresponding data line, and the remaining subpixels are turned off by receiving the data initialization voltage from the corresponding data line;
The reference line is an OLED display for charging a signal output from the driven sub-pixel in a floating state. 5. The method according to claim 4,
The data driver
a first switch for supplying the first reference voltage to the reference line;
a second switch for supplying the second reference voltage to the reference line;
and a sensing unit that samples the voltage charged in the reference line, converts it into sensed data, and outputs the same. 6. The method of claim 5,
The second initialization period is
In the first period, when the first and second switching TFTs of the plurality of subpixels are turned on, the data initialization voltage supplied through the corresponding data line is applied to the gate node of the driving TFTs of the plurality of subpixels become,
turning off the first and second switching TFTs of the plurality of subpixels in the second period;
In the third period, the second switching TFTs of the plurality of subpixels are turned on, and the second reference voltage supplied from the data driver through the reference line is applied to the source node of the driving TFTs of the plurality of subpixels. OLED display device to apply. During the sensing period of each horizontal line in the pixel array, a plurality of subpixels sharing a reference line are sequentially driven in a sensing mode, and driving characteristics of each of the plurality of subpixels are sequentially sensed through the shared reference line. a sensing mode period for each of the plurality of subpixels;
Each sensing mode period for each of the plurality of subpixels is
a first initialization period in which the plurality of sub-pixels are initialized by receiving a first reference voltage supplied through the reference line;
a driving and sensing period in which any one of the plurality of subpixels is driven by receiving a sensing data voltage supplied to a corresponding data line and sensed through the reference line;
a second initialization period in which the plurality of sub-pixels are initialized by receiving a second reference voltage greater than the first reference voltage through the reference line;
The second initialization period is
a first period in which the data initialization voltage supplied through the data line is supplied to the gate node of the driving TFT of the plurality of sub-pixels;
a second period of disconnecting the data line connected to the gate node of the driving TFT of the plurality of sub-pixels and the reference line connected to the source node of the driving TFT;
and a third period of applying the second reference voltage supplied through the reference line to a source node of a driving TFT of the plurality of subpixels. 8. The method of claim 7,
In the first initialization period, the plurality of sub-pixels receive a data initialization voltage from each data line and receive the first reference voltage from the reference line to initialize the driving TFT;
In the driving and sensing period, sub-pixels other than the driven sub-pixel among the plurality of sub-pixels receive the data initialization voltage from a corresponding data line and are turned off;
In the second initialization period, the plurality of sub-pixels receive the data initialization voltage from each data line and receive the second reference voltage from the reference line to apply a reverse bias to the driving TFT. of sensing method. 9. The method of claim 8,
The second initialization period is
the data initialization voltage is applied to the gate node of the driving TFT in a turn-on state of the first and second switching TFTs of the plurality of subpixels in the first period;
turning off the first and second switching TFTs of the plurality of subpixels in the second period;
OLED display for turning on the second switching TFT of the plurality of subpixels in the third period and applying the second reference voltage supplied through the reference line to a source node of the driving TFT of the plurality of subpixels The sensing method of the device.

Images