Light-emitting display device and driving method thereof

Abstract

A light-emitting display device and a driving method thereof. The present invention provides a light-emitting display device, comprising: a display panel, the display panel comprising M sub-pixels (M is an integer equal to or greater than 2) sharing a single sensing line; and a circuit for sensing an element included in at least one sub-pixel of the M sub-pixels through the sensing line. A first sub-pixel of the M sub-pixels may be defined as a sensing sub-pixel, a second sub-pixel may be defined as a non-sensing sub-pixel, and the second sub-pixel may have an initialization period for applying an initialization voltage for a longer time than a data writing period for applying a sensing voltage to the first sub-pixel.

Description

[0001] This application is a divisional application of the original invention patent application with application number 202010771786.2 (application date: August 4, 2020, invention name: light-emitting display device and driving method thereof). Technical Field

[0002] The present invention relates to a light emitting display device and a driving method thereof. Background Art

[0003] With the development of information technology, the market for display devices, which are connecting media between users and information, is expanding. Therefore, display devices such as light emitting displays (LEDs), quantum dot displays (QDDs), and liquid crystal displays (LCDs) are increasingly being used.

[0004] The above-mentioned display device includes: a display panel including sub-pixels, a driver outputting a driving signal for driving the display panel, and a power supply generating power to be supplied to the display panel or the driver.

[0005] When driving signals (eg, scan signals and data signals) are supplied to sub-pixels formed in a display panel, the above-described display device may display an image in a manner in which selected sub-pixels transmit light or directly emit light.

[0006] Among the above display devices, the light-emitting display device has many advantages such as electrical and optical characteristics of high response speed, high brightness and wide viewing angle, and mechanical characteristics implemented in a flexible form. However, the light-emitting display device requires improvement in compensation circuit configuration, and thus consistent research related thereto is required. Summary of the invention

[0007] The purpose of the present invention which substantially eliminates the above-mentioned problems is to converge the voltages around the sensing nodes to almost the same initialization voltage even when the sensing nodes are initialized using a voltage lower than the threshold voltage of the OLED, reduce the probability of generating sensing deviations based on almost the same initialization voltage, and improve the sensing accuracy and compensation accuracy (compensation for image sticking) to realize a screen with high display quality.

[0008] To achieve the object, the present invention provides a light-emitting display device, the light-emitting display device comprising: a display panel including M sub-pixels (M is an integer equal to or greater than 2) sharing a single sensing line; and a circuit for sensing an element included in at least one sub-pixel of the M sub-pixels through the sensing line. A first sub-pixel of the M sub-pixels may be defined as a sensing sub-pixel, a second sub-pixel may be defined as a non-sensing sub-pixel, and the second sub-pixel may have an initialization period for applying an initialization voltage for a longer time than a data writing period for applying a sensing voltage to the first sub-pixel.

[0009] The initialization period of the second sub-pixel may occur continuously.

[0010] The initialization period of the second sub-pixel may be longer than a sensing period for sensing the first sub-pixel.

[0011] A data writing period of the first sub-pixel and a sensing period of the first sub-pixel may alternate.

[0012] Unlike the initialization period of the second subpixel, the data writing period of the first subpixel and the sensing period of the first subpixel are alternately repeated K times (K is an integer equal to or greater than 2) and do not occur continuously.

[0013] During the first time, the initialization period of the second sub-pixel can occur continuously, wherein the first time is defined as (A) a time longer than the data writing period, (B) a time longer than the sensing period, (C) a time longer than the boost period existing between the data writing period and the sensing period, (D) a time required for at least two of the data writing period, the boost period and the sensing period, or (E) a time corresponding to the sum of the data writing period and the sensing period.

[0014] The sensing voltage may be set to a voltage level at which the organic light emitting diode OLED included in the first sub-pixel emits light, and the initialization voltage may be set to a voltage level at which the OLED included in the second sub-pixel does not emit light, a resistance value of the first sub-pixel may be lower than a resistance value of the second sub-pixel, and a resistance value of the second sub-pixel may be higher than a resistance value of the first sub-pixel.

[0015] One period in which K repeated sensing is performed is included in one row of the display panel, and the periods in all rows of the display panel may not overlap so that the sensing lines are not repeatedly selected.

[0016] In another aspect, the present invention provides a method for driving a light-emitting display device, the method comprising the following steps: applying an initialization voltage for initializing an OLED included in a non-sensing sub-pixel among M sub-pixels in an initialization period; applying a sensing voltage for sensing an OLED included in a sensing sub-pixel among M sub-pixels in a data writing period; floating an anode of the OLED included in the sensing sub-pixel in a boost period; and sensing the OLED included in the sensing sub-pixel in a sensing period. The initialization period may be longer than the data writing period.

[0017] The initialization period may occur continuously, and unlike the initialization period, the data writing period and the sensing period may be alternately repeated K times (K is an integer greater than 2) and occur discontinuously.

[0018] Even when a sensing node is initialized with a voltage lower than the threshold voltage of the OLED, the present invention has the effect of converging the voltages around the sensing node to almost the same initialization voltage. In addition, the present invention has the following effects: based on the conditions for sufficient initialization of non-sensing sub-pixels, the probability of sensing deviation generation is reduced, and the sensing accuracy and compensation accuracy (compensation for image sticking) are improved to achieve a screen with high display quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a block diagram schematically showing an organic light emitting display device according to an embodiment of the present invention, and Figure 2 It is schematically shown Figure 1 The configuration diagram of the sub-pixel SP is shown in FIG.

[0020] Figure 3 is an equivalent circuit diagram showing a sub-pixel including a compensation circuit according to an embodiment of the present invention, Figure 4 and Figure 5 It shows that it can be based on Figure 3 A pixel is realized by a sub-pixel.

[0021] Figure 6 are first schematic diagrams respectively illustrating main blocks of an organic light emitting display device according to an embodiment of the present invention, Figure 7 and Figure 8 2 are second schematic diagrams respectively illustrating main blocks of an organic light emitting display device according to an embodiment of the present invention.

[0022] Fig. 9 is a diagram for describing a method of driving an organic light emitting display device according to an embodiment of the present invention, Fig.10 Is used to describe Fig. 9 A diagram showing the difference between the initialization period, the data writing period and the sensing period of Fig.11 and Fig.12 It is a diagram for describing the effects of the embodiment of the present invention.

[0023] Fig.13 is a schematic diagram for helping to understand the sensing and initialization method according to an embodiment of the present invention, Fig.14 Shows Fig.13 The driving waveform of the sub-pixel, and Fig.15 and Fig.16 Simulation results are shown, through which the effect increase according to the initialization period according to the embodiment of the present invention can be confirmed.

[0024] Fig.17 is a diagram for describing an application of a method of driving an organic light emitting display device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

[0026] The light emitting display device according to the present invention may be implemented in the form of a TV receiver, a video player, a personal computer (PC), a home theater, an in-vehicle electronic device, a smart phone, etc., but the present invention is not limited thereto.

[0027] In addition, the light emitting display device to be described below is applicable not only to an organic light emitting display device based on an organic light emitting diode, but also to an inorganic light emitting display device based on an inorganic light emitting diode. However, the following description will be given based on the organic light emitting display device.

[0028] In addition, the organic light emitting display device described below performs an image display operation and an external compensation operation. The external compensation operation can be performed in units of sub-pixels or pixels. The external compensation operation can be performed in a vertical blanking period during the image display operation, a power-on sequence period before the image display starts, or a power-off sequence period after the image display ends.

[0029] The vertical blanking period is a period during which data signals for image display are not written, and is provided between vertical activation periods during which data signals corresponding to one frame are written. The power-on sequence period refers to the period from when the device is powered on to when an image is displayed. The power-off sequence period refers to the period from when image display ends to when the device is powered off.

[0030] When the source node potential of the driving transistor is saturated (i.e., when the current Ids of the driving TFT becomes zero), the external compensation can be used to sense the source voltage to compensate for the threshold voltage deviation of the driving transistor. In addition, the external compensation can be used to sense the value of the linear state before the source node of the driving transistor reaches the saturation state to compensate for the mobility deviation of the driving transistor.

[0031] In addition, external compensation can be used to sense the current flowing through the sensing node located between the source of the driving transistor and the anode of the organic light emitting diode so as to compensate for the threshold voltage deviation of the driving transistor. In addition, external compensation can be used to sense the charge accumulated in the parasitic capacitor of the organic light emitting diode so as to compensate for the degradation of the organic light emitting diode. As described above, external compensation can be used to sense the voltage charged in the line or electrode, the current flowing through the node, the charge accumulated in the parasitic capacitor, etc., and compensate for the degradation of the element included in the sub-pixel based on the sensing result.

[0032] In addition, although the sub-pixel described in the following description includes an n-type thin film transistor (TFT), the sub-pixel may include a p-type TFT or include both an n-type TFT and a p-type TFT. A TFT is a three-electrode element including a gate, a source, and a drain. The source is an electrode that provides carriers to the transistor. Carriers flow out from the source in the TFT. The drain is an electrode that emits carriers in the TFT. That is, carriers flow from the source to the drain in the TFT.

[0033] In the case of an n-type TFT, the carriers are electrons, so the source voltage is lower than the drain voltage so that electrons can flow from the source to the drain. Since electrons flow from the source to the drain in an n-type TFT, current flows from the drain to the source. On the other hand, in the case of a p-type TFT, the carriers are holes, so the source voltage is higher than the drain voltage so that holes can flow from the source to the drain. Since holes flow from the source to the drain in a p-type TFT, current flows from the source to the drain. However, the source and drain of a TFT may change depending on the applied voltage. In the following description, one of the source and drain is referred to as a first electrode, and the other is referred to as a second electrode.

[0034] Figure 1 is a block diagram schematically showing an organic light emitting display device according to an embodiment of the present invention, Figure 2 It is schematically shown Figure 1 The configuration diagram of the sub-pixels shown in .

[0035] like Figure 1 and Figure 2 As shown, the organic light emitting display device according to an embodiment of the present invention includes an image provider 110, a timing controller 120, a scan driver 130, a data driver 140, a display panel 150, a power supply 180, and the like.

[0036] The image provider 110 (or a host system) outputs various driving signals together with an image data signal provided externally or an image data signal stored in an internal memory. The image provider 110 may provide the data signal and the various driving signals to the timing controller 120.

[0037] The timing controller 120 outputs a gate timing control signal GDC for controlling the operation timing of the scan driver 130 , a data timing control signal DDC for controlling the operation timing of the data driver 140 , and various synchronization signals (a vertical synchronization signal and a horizontal synchronization signal).

[0038] The timing controller 120 provides the data signal DATA provided from the image provider 110 together with the data timing control signal DDC to the data driver 140. The timing controller 120 may be configured in the form of an integrated circuit (IC) and mounted on a printed circuit board, but the present invention is not limited thereto.

[0039] The scan driver 130 outputs a scan signal (or a scan voltage) in response to a gate timing control signal GDC provided from the timing controller 120. The scan driver 130 provides the scan signal to the sub-pixels included in the display panel 150 through the scan lines GL1 to GLm. The scan driver 130 is configured in the form of an IC or is directly formed on the display panel 150 in the form of an in-panel gate, but the present invention is not limited thereto.

[0040] The data driver 140 samples and latches the data signal DATA in response to the data timing control signal DDC provided from the timing controller 120, converts the data signal DATA in a digital form into a data voltage in an analog form based on a gamma reference voltage, and outputs the data voltage.

[0041] The data driver 140 supplies data voltages to sub-pixels included in the display panel 150 through the data lines DL1 to DLn. The data driver 140 may be configured in the form of an IC and mounted on the display panel 150 or a printed circuit board, but the present invention is not limited thereto.

[0042] The power supply 180 generates and outputs a first power EVDD having a high potential and a second power EVSS having a low potential based on an external input voltage provided from the outside. The power supply 180 may generate and output a voltage required to drive the scan driver 130 (e.g., a scan high voltage or a scan low voltage) or a voltage required to drive the data driver 140 (e.g., a drain voltage or a half-drain voltage) as well as the first power EVDD and the second power EVSS.

[0043] The display panel 150 displays an image in response to a driving signal including a scan signal and a data voltage provided from drivers including a scan driver 130 and a data driver 140 and first and second powers EVDD and EVSS provided from a power source 180. Subpixels of the display panel 150 directly emit light.

[0044] The display panel 150 may be formed based on a rigid or flexible substrate such as a glass, silicon or polyimide substrate. Sub-pixels emitting light may be composed of red pixels, green pixels and blue pixels or red pixels, green pixels, blue pixels and white pixels.

[0045] For example, a single sub-pixel SP includes a pixel circuit PC including a switching transistor SW, a driving transistor, a storage capacitor, an organic light emitting diode, etc. The sub-pixel SP used in the organic light emitting display device directly emits light and thus has a complex circuit configuration. In addition, a compensation circuit for compensating for degradation of an organic light emitting diode that emits light and a driving transistor that supplies a driving current to the organic light emitting diode may be configured in various ways. Therefore, the pixel circuit PC included in the sub-pixel SP is shown in the form of a block.

[0046] Although the timing controller 120 , the scan driver 130 , and the data driver 140 are described above as separate components, one or more of the timing controller 120 , the scan driver 130 , and the data driver 140 may be integrated into a single IC depending on the implementation of the organic light emitting display device.

[0047] Figure 3 is an equivalent circuit diagram showing a sub-pixel including a compensation circuit according to an embodiment of the present invention, Figure 4 and Figure 5 It shows that it can be based on Figure 3 A pixel is realized by a sub-pixel.

[0048] like Figure 3 As shown in FIG. 1 , a sub-pixel including a compensation circuit according to an embodiment of the present invention includes a switching transistor SW, a sensing transistor ST, a driving transistor DT, a capacitor CST, and an organic light emitting diode OLED.

[0049] The switching transistor SW includes a gate connected to the first A scan line GL1a, a first electrode connected to the first data line DL1, and a second electrode connected to the gate of the driving transistor DT. The driving transistor DT includes a gate connected to the capacitor CST, a first electrode connected to the first power line EVDD, and a second electrode connected to the anode of the organic light emitting diode OLED.

[0050] The capacitor CST includes a first electrode connected to the gate electrode of the driving transistor DT and a second electrode connected to the anode electrode of the organic light emitting diode OLED. The organic light emitting diode OLED includes an anode electrode connected to the second electrode of the driving transistor DT and a cathode electrode connected to the second power line EVSS.

[0051] The sensing transistor ST includes a gate connected to the first B scan line GL1b, a first electrode connected to the first sensing line VREF1, and a second electrode connected to the anode of the organic light emitting diode OLED as a sensing node. The sensing transistor ST is a compensation circuit added to sense the degradation or threshold of the driving transistor DT and the organic light emitting diode OLED. The sensing transistor ST obtains a sensing value through a sensing node defined between the driving transistor DT and the organic light emitting diode OLED. The sensing value obtained by the sensing transistor ST is transmitted to an external compensation circuit provided outside the sub-pixel through the first sensing line VREF1.

[0052] The first A scan line GL1a connected to the gate of the switching transistor SW and the first B scan line GL1b connected to the gate of the sensing transistor ST may be separated as shown or may be commonly connected. The number of scan lines may be reduced to prevent the aperture ratio from being reduced due to adding a compensation circuit according to the gate common connection structure.

[0053] like Figure 4 and Figure 5 As shown, the first to fourth sub-pixels SP1 to SP4 including the compensation circuit according to the embodiment of the present invention may be defined as constituting pixels. Here, the first to fourth sub-pixels SP1 to SP4 may be arranged in the order of sub-pixels emitting red light, green light, blue light, and white light, but the present invention is not limited thereto.

[0054] As in Figure 4 As shown in the first example of FIG. 1 , the first to fourth subpixels SP1 to SP4 including the compensation circuit may be connected such that they share the first sensing line VREF1 and are connected to the first to fourth data lines DL1 to DL4 , respectively.

[0055] As in Figure 5 As shown in the second example of , the first to fourth sub-pixels SP1 to SP4 including the compensation circuit may be connected in such a manner that the first to fourth sub-pixels SP1 to SP4 share the first sensing line VREF1 and the two sub-pixels are commonly connected to a single data line. For example, the first sub-pixel SP1 and the second sub-pixel SP2 may share the first data line DL1, and the third sub-pixel SP3 and the fourth sub-pixel SP4 may share the second data line DL2.

[0056] However, Figure 4 and Figure 5 Only two examples are shown, and the present invention is applicable to display panels with different sub-pixel structures that are not shown and described. That is, the present invention is applicable to display panels based on an external compensation circuit in which M (M is equal to or greater than 2) sub-pixels share a single sensing line. In addition, the present invention is applicable to a structure in which a compensation circuit exists in a sub-pixel or a structure in which a compensation circuit does not exist in a sub-pixel.

[0057] Figure 6 are first exemplary diagrams respectively illustrating main blocks of an organic light emitting display device according to an embodiment of the present invention, and Figure 7 and Figure 8 2 are second exemplary diagrams respectively illustrating main blocks of an organic light emitting display device according to an embodiment of the present invention.

[0058] like Figure 6 As shown in , an organic light emitting display device according to an embodiment of the present invention includes a circuit that supplies a data voltage to a sub-pixel, senses an element included in the sub-pixel, and generates a compensation value based on a sensing value obtained through the sensing.

[0059] The data drivers 140a and 140b are circuits for performing driving operations such as providing data voltages to subpixels and sensing operations of elements included in the subpixels, and may include a first circuit 140a and a second circuit 140b. However, an external compensation circuit such as the second circuit 140b may be configured as a separate device.

[0060] The first circuit 140a outputs a data voltage Vdata for operating a sub-pixel and may include a data voltage output unit DAC. The data voltage output unit DAC converts a digital data signal provided from a timing controller into an analog voltage and outputs the analog voltage. An output terminal of the data voltage output unit DAC is connected to a first data line DL1. The data voltage output unit DAC may output a voltage required for a compensation operation (e.g., a sensing voltage, a black voltage, etc.) and a data voltage Vdata required for image representation.

[0061] The second circuit 140b is a circuit for sensing an element included in a sub-pixel, and may include a sensing circuit SEN for acquiring a sensing value and a sensing value converter CON for converting the sensing value. The sensing circuit SEN may sense the characteristics of the element included in the sub-pixel through the first sensing line VREF1. The sensing value converter CON may sample the analog sensing value output from the sensing circuit SEN, convert the sampled analog sensing value into a digital sensing value, and output the digital sensing value.

[0062] For example, the sensing circuit SEN may sense a voltage charged in a line capacitor (a parasitic capacitor formed along the first sensing line) of the first sensing line VREF1, and sense and compensate for characteristics of an element included in a sub-pixel based on the sensed voltage. As another example, the sensing circuit SEN may sense a current flowing through a sensing node connected to the first sensing line VREF1, and sense and compensate for characteristics of an element included in a sub-pixel based on the sensed current. As another example, the sensing circuit SEN may sense a charge accumulated in a parasitic capacitor of an organic light emitting diode through the first sensing line VREF1, and sense and compensate for characteristics of an element included in a sub-pixel based on the sensed charge.

[0063] The compensation circuit 160 is a circuit for performing image analysis and generating a compensation value based on a sensed value, and may include an image analyzer 165 and a compensation value generator 167. The image analyzer 165 may be used to analyze a data signal input from the outside and a sensed value output from the sensed value converter CON. The compensation value generator 167 may be used to determine the degree of degradation of the sensed element, and generate a compensation value required for compensation in response to the analysis result output from the image analyzer 165.

[0064] like Figure 7 and Figure 8 As shown, when the first circuit 140a and the second circuit 140b are included in the data driver 140, the compensation circuit 160 may be included in the timing controller 120. Therefore, the timing controller 120 may provide the compensated data signal CDATA obtained by compensating the data signal DATA based on the compensation value to the data driver 140. In addition, the timing controller 120 may provide the data driver 140 with a control signal CNT for controlling the first circuit 140a and the second circuit 140b.

[0065] The method of driving an organic light emitting display device to be described below involves sensing charges accumulated in a parasitic capacitor of an OLED and compensating for degradation of the OLED based on the sensed charges. The parasitic capacitance of the OLED tends to reduce its capacitance as the OLED degrades.

[0066] Therefore, by sensing the charge accumulated in the parasitic capacitor of the OLED, the change in the parasitic capacitor of the OLED (capacitance change) can be detected based on the principle of charge balance. In addition, the degradation or threshold value of the OLED can be compensated based on the change in the parasitic capacitor of the OLED (capacitance change) (voltage compensation, gain compensation, gamma compensation, etc.).

[0067] The operation of sensing charges accumulated in the parasitic capacitor of the OLED may be performed as follows, but the present invention is not limited thereto.

[0068] First, the driving transistor DT is turned off, an initialization voltage is applied to the OLED through the first sensing line VREF1, and then the OLED is turned on (emitted light) in the initialization period. The initialization period is followed by a data writing period for generating a sensing voltage in the OLED through the first data line DL1. The data writing period is followed by a boost period for setting an operating point voltage of the OLED while floating the anode of the OLED. The boost period is followed by a sensing period in which the first sensing line VREF1 and the anode of the OLED are electrically connected (forming a discharge path) to sense the charge accumulated in the parasitic capacitor of the OLED.

[0069] Fig. 9 is a diagram for describing a method of driving an organic light emitting display device according to an embodiment of the present invention, Fig.10 Is used to describe Fig. 9 A diagram showing the difference between an initialization period, a data writing period, and a sensing period of Fig.11 and Fig.12 It is a diagram for describing the effects of the embodiment of the present invention.

[0070] like Figure 6 and Fig. 9 As shown, the method of driving an organic light emitting display device according to an embodiment of the present invention includes an initialization period, a data writing period, and a sensing period. Although not shown, there may be a boosting period between the data writing period and the sensing period.

[0071] The initialization period refers to a period during which an initialization voltage is written (charged) to a non-sensing sub-pixel (one or more sub-pixels that are not included in the sub-pixel to be sensed and are selected at the first time). The data writing period refers to a period during which a sensing voltage is written (charged) to a sensing sub-pixel (a sub-pixel included in the sub-pixel to be sensed and selected at the first time or the second time). The sensing period refers to a period during which charges accumulated in a sensing sub-pixel (one or more sub-pixels included in the sub-pixel to be sensed and selected at the second time or the third time) are sensed.

[0072] Because a plurality of sub-pixels share a sensing line, an initialization voltage is written to a non-sensing sub-pixel instead of a sensing sub-pixel to initialize the non-sensing sub-pixel, so as to minimize the influence of the non-sensing sub-pixel on the sensing sub-pixel when the sensing sub-pixel is sensed. In addition, when the initialization period increases, for a period of repeated sensing, an additional initialization period can be deleted (initialization is not performed each time, and a long initialization period is inserted before repeated sensing).

[0073] The initialization period continues (continuously / consistently) for n first times so as to provide sufficient initialization time for the non-sensing sub-pixels. Here, the first time may be defined as a time longer than the data writing period, a time longer than the sensing period, a time longer than the boosting period existing between the data writing period and the sensing period, a time taken to perform at least two of data writing, boosting, and sensing, or a time corresponding to the sum of the data writing period and the sensing period.

[0074] However, the data writing period and the sensing period are repeated alternately K times (K is an integer equal to or greater than 2) so as to provide the sensing subpixel with repeated sensing K times. Unlike the initialization period that occurs continuously, the data writing period and the sensing period are repeated alternately and occur discontinuously. K may be 16, 32, 64, etc. When the number of repeated sensing times K increases, the sensing accuracy can be improved.

[0075] like Fig. 9 and Fig.10 As shown, the initialization period occurs (lasts) longer than the data writing period and / or the sensing period. The initialization period may last longer than a data writing period or a sensing period. The duration of the initialization period may be longer than the sum of a data writing period and a sensing period.

[0076] Fig.10 A bar graph comparing the durations of an initialization period, a data writing period, and a sensing period is shown.

[0077] like Fig.11 and Fig.12 As shown, the non-sensing voltage of the OLED (OLED non-sensing voltage) belongs to a voltage level (eg, 4.5 V) in a range where the OLED does not emit light, and the resistance value R can be significantly higher than Fig.12 On the other hand, the sensing voltage of the OLED (OLED sensing voltage) belongs to the voltage level of the range of OLED light emission (for example, 10.5V), and the resistance value R can be significantly lower than Fig.12 The resistance value of (A).

[0078] Therefore, when the initialization period becomes long, the charging condition can be met even when the OLED included in the non-sensing sub-pixel is charged with a voltage lower than the threshold voltage of the OLED (e.g., 4.5V). That is, when initialization is performed using a voltage lower than the threshold voltage of the OLED, if a longer initialization time is allocated, the problem that the initialization voltage is not correctly applied to the OLED can be solved. In addition, when the non-sensing sub-pixel is not initialized for a sufficient time (e.g., at least 3ms) (in the case of insufficient initialization time), the problem of degradation of sensing accuracy or compensation accuracy due to sensing deviation during repeated sensing (caused by the charge difference in the parasitic capacitor) can be solved to improve display quality.

[0079] In addition, a period in which repeated sensing occurs K times after a long initialization period may be included in one row. In addition, the period in which repeated sensing occurs K times does not overlap in all rows of the display panel (i.e., the sensing line is not repeatedly selected). Here, the first row (row 1) includes specific sub-pixels (e.g., four sub-pixels including red sub-pixels, green sub-pixels, blue sub-pixels, and white sub-pixels) arranged in one horizontal line defined on the display panel.

[0080] For example, if a sensing operation is performed on a first pixel in a first row (row 1) for a first time, a sensing operation is performed on a second pixel in a second row (row 2) for a second time different from the first time, and the operation can be performed sequentially until the Nth pixel in the Nth row (row n) which is the last row.

[0081] In the above example, the second pixel of the second row (row 2) after the first pixel of the first row (row 1) is mentioned. Here, the first pixel of the first row (row 1) and the second pixel of the second row (row 2) may be vertically adjacent pixels or pixels away from each other. Although the sensing operation is performed sequentially from the first row (row 1) to the Nth row (row n) in the above example, the sensing operation may be performed in the reverse order or a random sensing operation may be performed.

[0082] Fig.13 is an exemplary diagram for helping to understand the sensing and initialization method according to an embodiment of the present invention, Fig.14 Shows Fig.13 The driving waveform of the sub-pixel, and Fig.15 and Fig.16 Simulation results are shown, through which the effect of increasing the initialization period according to the embodiment of the present invention can be determined.

[0083] like Fig.13 and Fig.14As shown, the first sub-pixel SP1 may be defined as a sensing sub-pixel, and the second sub-pixel SP2 to the fourth sub-pixel SP4 may be defined as non-sensing sub-pixels. A total of four sub-pixels including the first sub-pixel SP1 to the fourth sub-pixel SP4 may be connected to the first sensing line VREF1. In addition, the first sub-pixel SP1 to the fourth sub-pixel SP4 may include a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel.

[0084] The scan signal SCAN may be applied as a scan high voltage during the initialization period, as a scan low voltage during the boost period, and as a scan high voltage during the sensing period. The data voltage Data applied to the first data line DL1 may be applied as a voltage (e.g., 0.5V) of a black sensing level during the initialization period, the boost period, and the sensing period. The reference voltage Ref (e.g., 4.5V) applied to the first sensing line VREF1 may be maintained under the same conditions. Therefore, the source voltage DT-Vs of the driving transistor DT increases (2V→4.5V), and the voltage Voled of the anode of the OLED also increases (2V→4.5V).

[0085] The first sub-pixel SP1 corresponds to a sensing sub-pixel and has a lower resistance value than the non-sensing sub-pixel (lower resistance value in the equivalent circuit of the OLED) because a voltage level within the range in which the OLED emits light is applied to the first sub-pixel SP1. Therefore, the first sub-pixel SP1 can apply the sensing voltage of the OLED in a relatively short time (shorter time than the time of applying the initialization voltage of the non-sensing sub-pixel).

[0086] On the other hand, because a voltage level within a range in which the OLED does not emit light is applied to the second to fourth sub-pixels SP2 to SP4, the second to fourth sub-pixels SP2 to SP4 correspond to non-sensing sub-pixels and have a higher resistance value than the sensing sub-pixels (a higher resistance value in the equivalent circuit of the OLED). Therefore, the second to fourth sub-pixels SP2 to SP4 can apply the initialization voltage of the OLED for a relatively long time (a time longer than the time for applying the sensing voltage of the sensing sub-pixels). That is, the second to fourth sub-pixels SP2 to SP4 corresponding to the non-sensing sub-pixels have an initialization period for applying the initialization voltage for a time longer than the time of the first sub-pixel SP1 corresponding to the sensing sub-pixel.

[0087] like Fig.15As shown in , when a short initialization period is set, the voltages VOLED and Vs of the sensing nodes between the source of the driving transistor and the anode of the OLED and the voltage Vout when sensed by the sensing nodes do not converge to the initialization voltage (e.g., 4.5V) and may include a voltage lower or higher than the initialization voltage.

[0088] However, when a long initialization period is set as in the embodiment, Fig.16 As shown, voltages VOLED and Vs of a sensing node between a source of the driving transistor and an anode of the OLED and a voltage Vout when sensed through the sensing node converge at an initialization voltage (eg, 4.5 V) and may include almost the same voltage.

[0089] If you can Fig.15 As determined in the simulation results of , when the initialization period is set to be longer than the boost period or the sensing period as in the embodiment, initialization can be performed using the same voltage regardless of the voltage between the source of the driving transistor and the anode of the OLED.

[0090] Fig.17 is a diagram for describing an application of a method of driving an organic light emitting display device according to an embodiment of the present invention.

[0091] like Fig.17 As shown in , the method of driving an organic light emitting display device according to an embodiment of the present invention can be applied to a TV receiver. The TV receiver can be turned off according to the user's remote control operation. After the TV receiver is turned off, an operation of compensating for the threshold voltage of the driving transistor and an operation of compensating for the effectiveness (degradation) of the OLED can be performed, which will be briefly described below.

[0092] First, when the TV receiver is turned off (S110), it can be determined whether the operation time of the TV receiver has exceeded time XX (XX refers to the first reference time set in the TV receiver) (S120). When the operation time of the TV receiver does not exceed the first reference time (No), unnecessary compensation operation can be skipped and the process can end (S160).

[0093] However, it is determined that the operation time of the TV receiver has exceeded the first reference time (Yes), and a first compensation operation (OFFRS) for compensating the threshold voltage of the driving transistor (TFT Vth compensation) (compensating the threshold voltage of the thin film transistor) may be performed (OFF RS is a compensation operation performed after turning off the display device) (S130). In order to compensate for the threshold voltage deviation of the driving transistor in response to the first compensation operation (OFF RS), a current flowing through a sensing node between the source of the driving transistor and the anode of the OLED may be detected.

[0094] Then, it can be determined whether the operation time of the TV receiver has exceeded time YYYY (YYYY refers to a second reference time set in the TV receiver that is longer than the first reference time) (S140). When the operation time of the TV receiver does not exceed the second reference time (No), unnecessary compensation operations can be skipped and the process can end (S160).

[0095] However, if it is determined that the operation time of the TV receiver has exceeded the second reference time (yes), a second compensation operation (isJB) for compensating for the efficiency (deterioration) of the OLED may be performed (S150). In order to compensate for the degradation of the efficiency of the OLED in response to the second compensation operation (isJB), the charge accumulated in the parasitic capacitor of the OLED may be sensed, and the degradation of the element included in the sub-pixel may be compensated based on the sensed charge.

[0096] When the user turns on the TV receiver during the first compensation operation (OFF RS) (S130) or the second compensation operation (isJB) (S150), the compensation operation including the sensing operation may be stopped.

[0097] As described above, even when a voltage lower than the threshold voltage of the OLED is used to initialize the sensing node, the present invention can converge the voltages around the sensing node at almost the same initialization voltage. In addition, the present invention can reduce the probability of sensing deviation generation based on the condition of sufficient initialization of the non-sensing sub-pixel, and improve the sensing accuracy and compensation accuracy (compensation image sticking) to achieve a screen with high display quality.

Claims

1. A light-emitting display device, comprising: A display panel comprising M sub-pixels sharing a single sensing line, wherein M is an integer equal to or greater than 2; and a circuit configured to sense one or more elements included in at least one sub-pixel among the M sub-pixels through the sensing line, wherein the M sub-pixels have an initialization period for applying an initialization voltage for a longer time than a data writing period for applying a sensing voltage, During the initialization period, the initialization voltage is applied to the M sub-pixels through the sensing line, and during the data writing period, the sensing voltage is written into the sub-pixel to be sensed among the M sub-pixels.

2. The light emitting display device according to claim 1, wherein: The initialization period occurs continuously.

3. The light emitting display device according to claim 1, wherein: The initialization period occurs continuously.

4. The light emitting display device according to claim 1, wherein: The initialization voltage is continuously applied to the M sub-pixels during the initialization period.

5. The light emitting display device according to claim 2, wherein: The initialization period is longer than a sensing period for sensing at least one of the M sub-pixels.

6. The light emitting display device according to claim 5, wherein: The data writing period and the sensing period are alternated.

7. The light emitting display device according to claim 6, wherein: The data writing period and the sensing period are alternately repeated K times, where K is an integer equal to or greater than 2.

8. The light emitting display device according to claim 7, wherein: A period for performing K repeated sensing is applied to one sensing line of the display panel, where K is an integer equal to or greater than 2, and the periods for performing sensing in all sensing lines of the display panel do not overlap, so that the sensing lines are not repeatedly selected for sensing.

9. The light emitting display device according to claim 7, wherein: performing a first sensing operation on a first sensing line within a first time, performing K repeated sensings in the first sensing operation, wherein K is an integer equal to or greater than 2, and Wherein, a second sensing operation for the second sensing line is performed in a second time different from the first time.

10. The light emitting display device according to claim 2, wherein: During the first time, the initialization period occurs continuously, and Wherein, the first time is defined as a time longer than a boost period existing between the data writing period and the sensing period, a time for at least two of the data writing period, the boost period and the sensing period, or a time corresponding to the sum of the data writing period and the sensing period.

11. The light emitting display device according to claim 1, wherein: The sensing voltage is set to a voltage level at which the organic light emitting diode OLED emits light, and the initialization voltage is set to a voltage level at which the OLED does not emit light.

12. A method for driving a light-emitting display device, the method comprising the following steps: applying an initialization voltage for initializing an organic light emitting diode OLED included in at least one sub-pixel among the M sub-pixels in an initialization period, wherein M is an integer equal to or greater than 2; applying a sensing voltage for sensing an OLED included in a sub-pixel to be sensed among the M sub-pixels in a data writing period; floating an anode of the OLED included in the sub-pixel during a boost period; and sensing the OLED included in the sub-pixel during a sensing period, wherein the initialization period is longer than the data writing period, and During the initialization period, the initialization voltage is applied to the M sub-pixels through the sensing line, and during the data writing period, the sensing voltage is written into the sub-pixel to be sensed among the M sub-pixels.

13. The method according to claim 12, wherein: The initialization period occurs continuously.

14. The method according to claim 12, wherein: The initialization period occurs continuously.

15. The method according to claim 12, wherein: The initialization period is longer than a sensing period for sensing at least one of the M sub-pixels.

16. The method according to claim 12, wherein: The data writing period and the sensing period are alternated.

17. The method according to claim 16, wherein: The data writing period and the sensing period are alternately repeated K times, where K is an integer equal to or greater than 2.

18. The method according to claim 12, wherein: During the first time, the initialization period occurs continuously, and Wherein, the first time is defined as a time longer than a boost period existing between the data writing period and the sensing period, a time for at least two of the data writing period, the boost period and the sensing period, or a time corresponding to the sum of the data writing period and the sensing period.

19. The method according to claim 12, further comprising: An initialization voltage is continuously applied to the M sub-pixels during the initialization period.

20. The method according to claim 12, wherein: The M sub-pixels are connected to the same sensing line.

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