KR20200032509A - Display Device and Driving Method Thereof - Google Patents

Abstract

A display device capable of improving the power efficiency of the present invention comprises: a sub-pixel including a light emitting element having a first electrode to which a first driving voltage is inputted and a second electrode to which a second driving voltage with potential lower than potential of the first driving voltage is inputted; a switching unit selectively inputting the second driving voltage and a third driving voltage with potential lower than the potential of the second driving voltage; and a sensing unit supplying a sensing data voltage to the first electrode to sense the driving voltage characteristics of the light emitting element when the third driving voltage is inputted into the second electrode.

Description

Display device and driving method thereof

The present invention relates to a display device and a driving method thereof.

The active matrix type organic light emitting display device includes self-emission organic light emitting diodes (hereinafter, referred to as "light emitting devices"), and has a fast response speed, high light emission efficiency, high brightness, and a wide viewing angle.

The organic light emitting display device arranges subpixels each including a light emitting element in a matrix form and adjusts the luminance of the subpixels according to the gradation of image data. Each of the sub-pixels includes a driving thin film transistor (TFT) that controls a driving current input to the light emitting device according to its gate-source voltage (Vgs). The light emission amount of the light emitting element is proportional to the driving current, and the display gray level (luminance) is adjusted by the light emission amount.

The organic light emitting display device has a deterioration characteristic in which the threshold voltage (operation point voltage) of the light emitting element increases and the light emission efficiency decreases as the driving time elapses. The degree of deterioration of the light emitting device may vary for each subpixel. The variation in deterioration of the light emitting device between sub-pixels causes a variation in luminance and deterioration of image quality.

In order to compensate for the deterioration of the light emitting device, a number of compensation methods for modulating input image data by sensing the deterioration of the light emitting device are known. The deterioration sensing method of a light emitting device according to the prior art, charges the sensing data voltage in a capacitor to drive the light emitting device, detects the voltage remaining in the capacitor after a certain time, extracts the voltage discharged by the light emitting device, and extracts the voltage discharged by the light emitting device. The operating voltage characteristic Vf is sensed.

However, the deterioration sensing method of the light emitting device according to the related art requires a sufficiently high voltage for sensing data voltage, thereby increasing power consumption.

The problem to be solved by the present invention is to provide a display device and a driving method for improving power efficiency by reducing power consumed during deterioration sensing of a light emitting device.

A display device according to an exemplary embodiment of the present invention includes: a light emitting device having a first electrode to which a first driving voltage is input and a second electrode to which a second driving voltage at a lower potential than the first driving voltage is input; A switching unit selectively inputting the second driving voltage and a third driving voltage having a potential lower than that of the second driving voltage to the second electrode; And a sensing unit configured to detect a driving voltage characteristic of the light emitting device by supplying a sensing data voltage to the first electrode when the third driving voltage is input to the second electrode.

When the normal mode selection signal to which the image data voltage is supplied is input to the light emitting element, the switching unit operates to input the second driving voltage to the second electrode, and when the sensing mode selection signal to which the sensing data voltage is supplied is input. The third driving voltage may be input to the second electrode.

The switching unit may include: a first TFT connected to a source electrode and a drain electrode to supply lines of the second electrode and the third supply voltage and turned on according to the sensing mode selection signal input to the gate electrode; And a second TFT connected to a supply line of the second electrode and the second driving voltage and turned on according to the normal mode selection signal input to the gate electrode.

The first driving voltage is a high potential driving voltage (EVDD); The second driving voltage includes a low potential driving voltage (EVSS); And the third driving voltage may include a gate low voltage (VGL).

When the sensing data voltage is supplied, it is connected in parallel with the light emitting device to charge the sensing data voltage, and when the supply of the sensing data voltage is stopped, a sensing capacitor further supplying the charged sensing data voltage to the light emitting device can do.

The sensing unit may sense a voltage other than the voltage discharged by the light emitting device from the sensing data voltage charged in the sensing capacitor.

The switching unit outputs a mode selection signal to select the second driving voltage or the third driving voltage, and outputs an image data voltage supplied to the light emitting device based on the driving voltage characteristic of the light emitting device received from the sensing unit. It may include a timing controller to compensate.

The mode selection signal may include a normal mode selection signal to which the image data voltage is supplied to the light emitting element and a sensing mode selection signal to which the sensing data voltage is supplied.

A display device according to another embodiment of the present invention, a light emitting device having an anode electrode and a cathode electrode, connects a data line to which an image data voltage is supplied to the anode electrode in a normal mode, and senses a data voltage to the anode electrode in a sensing mode. A sub-pixel including a switching TFT that connects the supplied sensing line; A first wiring supplying a gate low voltage (VGL) to the cathode electrode; A second wiring supplying a low potential driving voltage (EVSS) to the cathode electrode; A first switch selectively connecting the second wiring to the cathode electrode in the sensing mode; And a second switch connecting the second wiring to the cathode electrode in the normal mode.

The deterioration compensation method of a display device according to an exemplary embodiment of the present invention includes a deterioration compensation method of a display device including a light emitting device having a first electrode to which a first driving voltage is input and a second electrode to which a second driving voltage is input. The method of claim 1, further comprising: connecting a third driving voltage having a lower potential to the second electrode in the sensing mode; Supplying a sensing data voltage to the first electrode; Emitting the light emitting element with the sensing data voltage; And detecting a driving voltage characteristic of the light emitting device by sensing a voltage other than the voltage discharged by the light emitting device from the sensing data voltage.

Connecting the second driving voltage to the second electrode in the normal mode; Supplying an image data voltage to the first electrode; And emitting the light emitting device using the image data voltage.

When the normal mode selection signal is input, the second driving voltage is input to the second electrode, and when the sensing mode selection signal is input, a switching unit operable to input the third driving voltage to the second electrode is included. You can.

In the embodiments of the present invention, when the light-emitting element is normally driven and sensing-driven, the sensing data voltage input for sensing the degradation of the light-emitting element is significantly reduced compared to the conventional one by connecting power sources having different potentials to the cathode electrode of the light-emitting element. Even when low, the operating voltage characteristic Vf of the light emitting device can be sensed. As such, as the data voltage for sensing decreases, power consumed during deterioration sensing may be reduced, and as a result, power efficiency of the display device may be improved.

1 is a schematic block diagram of a display device according to an exemplary embodiment of the present invention.
FIG. 2 is a schematic block diagram of a pixel array of the display device of FIG. 1.
3 is a block diagram showing a configuration for detecting deterioration characteristics of a light emitting device in a display device according to an exemplary embodiment of the present invention.
FIG. 4 is a view showing the equivalent circuit of FIG. 3 centering on the operation of the switching unit in the sensing mode.
5A to 5C are diagrams for explaining a method of sensing degradation characteristics of a light emitting device using the equivalent circuit of FIG. 4.
FIG. 6 is a view showing the equivalent circuit of FIG. 3 centering on the operation of the switching unit in the normal mode.
7 is a view showing in detail a wiring connection between a data drive IC and a pixel array of a display device according to an embodiment of the present invention.
8 is a view showing an equivalent circuit of a circuit for sensing the deterioration characteristics of the light emitting element of the display device of FIG. 7.
9A to 9C are diagrams for explaining a method of sensing a deterioration characteristic of a light emitting device using the equivalent circuit of FIG. 7.
10 is a view showing an equivalent circuit of the light emitting device of the display device of FIG. 7 in the normal mode.
FIG. 11 is a signal waveform diagram illustrating a method of driving the display device of FIG. 7.

Advantages and features of the present specification, and a method of achieving them will be apparent with reference to embodiments described below in detail together with the accompanying drawings. However, the present specification is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the embodiments allow the disclosure of the present specification to be complete, and common knowledge in the art to which this specification belongs It is provided to fully inform the person having the scope of the invention, and this specification is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for describing the embodiments of the present specification are exemplary, and the present specification is not limited to the illustrated matters. The same reference numerals refer to the same components throughout the specification. When 'include', 'have', 'consist of', etc. mentioned in this specification are used, other parts may be added unless '~ only' is used. When a component is expressed as a singular number, the plural number is included unless otherwise specified.

In analyzing the components, it is interpreted as including the error range even if there is no explicit description.

In the case of the description of the positional relationship, for example, when the positional relationship of two parts is described as '~ on', '~ on top', '~ on the bottom', '~ next to', etc., 'right' Alternatively, one or more other parts may be located between the two parts unless 'direct' is used.

The first, second, etc. may be used to describe various components, but these components are not limited by these terms. These terms are only used to distinguish one component from another component. Accordingly, the first component mentioned below may be the second component within the technical spirit of the present specification.

Throughout the specification, the same reference numerals refer to substantially the same components.

In the present specification, the pixel circuit and the gate driver formed on the substrate of the display panel may be implemented as a TFT of an n-type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) structure, but are not limited thereto and may be implemented as a TFT of a p-type MOSFET structure. have. TFT is a three-electrode element including a gate, a source, and a drain. The source is an electrode that supplies a carrier to the transistor. In the TFT, carriers begin to flow from the source. The drain is an electrode through which the carrier exits from the TFT. That is, the carrier flow in the MOSFET flows from the source to the drain. In the case of an n-type TFT (NMOS), since the carrier is electron, the source voltage has a voltage lower than the drain voltage so that electrons can flow from the source to the drain. In the n-type TFT, since electrons flow from the source to the drain, the direction of the current flows from the drain to the source. In contrast, in the case of the p-type TFT (PMOS), the source voltage is higher than the drain voltage so that holes can flow from the source to the drain because the carrier is a hole. In the p-type TFT, current flows from the source to the drain because holes flow from the source to the drain. It should be noted that the source and drain of the MOSFET are not fixed. For example, the source and drain of the MOSFET can be changed according to the applied voltage. Therefore, in the description of the embodiment of the present specification, any one of the source and the drain is described as the first electrode, and the other of the source and the drain is described as the second electrode.

Hereinafter, embodiments of the present specification will be described in detail with reference to the accompanying drawings. In the following embodiments, the display device will be mainly described with an organic light emitting display device including an organic light emitting material. However, it should be noted that the technical spirit of the present specification is not limited to the organic light emitting display device, and can be applied to an inorganic light emitting display device including an inorganic light emitting material.

In the following description, when it is determined that a detailed description of known functions or configurations related to the present specification may unnecessarily obscure the subject matter of the present specification, the detailed description is omitted.

1 is a schematic block diagram of a display device according to an exemplary embodiment of the present invention, and FIG. 2 is a schematic block diagram of a pixel array of the display device of FIG. 1.

Referring to FIG. 1, the display device includes a timing controller 110, a gate driver 130, a data driver 120, and a display panel 100.

A plurality of data lines 14 and gate lines 15 are crossed on the display panel 100, and subpixels SP are arranged in a matrix form for each crossing area. The subpixel SP may include a light emitting device, for example, OLED. A high potential driving voltage EVDD and a low potential driving voltage EVSS for driving the light emitting device OLED are supplied to the display panel 100. In addition, the sensing data voltage VREF and the gate line voltage VGL are supplied to the display device according to an exemplary embodiment of the present invention.

The timing control unit 110 receives digital image data DATA along with driving signals including a data enable signal DE or a vertical synchronization signal, a horizontal synchronization signal, and a clock signal from the image processing unit. The timing controller 110 is a gate timing control signal GDC for controlling the operation timing of the gate driver 130 based on the driving signal and a data timing control signal DDC for controlling the operation timing of the data driver 120. Output

The gate driver 130 outputs a scan signal in response to the gate timing control signal GDC supplied from the timing controller 110. The gate driver 130 outputs a scan signal including the gate high voltage VGH and the gate low voltage VGL through the gate lines 15.

The data driver 120 may be driven in a normal mode for supplying and displaying the image data voltage Vdata to the subpixel SP under the control of the timing controller 110 and a sensing mode for obtaining the sensing voltage Vsen. You can. In the normal mode, the data driver 120 converts the digital image data DATA into a voltage signal form based on the gamma reference voltage in response to the data timing control signal DDC supplied from the timing controller 110. The data driver 120 outputs the image data voltage Vdata in analog format through the data line 14. In the sensing mode, the data driver 120 senses the driving characteristic Vf of the light emitting element OLED included in the display panel 100 and feeds back the sensing data SD to the timing controller 110.

In the display device according to the exemplary embodiment of the present invention, the cathode electrode (-) of the light emitting element (OLED) is connected to the low potential driving voltage (EVSS) in the normal mode, and the cathode electrode (-) of the light emitting element (OLED) is sensed in the sensing mode. ) Is connected to the supply terminal of the gate low voltage VGL having a lower potential than the low potential driving voltage EVSS. The data driver 120 provides the driving characteristic Vf of the light-emitting element OLED sensed in the sensing mode to the timing controller 110 as sensing data SD, and thus, the timing controller 110 provides the sensing data SD Based on), the digital image data DATA may be compensated and output to the data driver 120.

Referring to FIG. 2, a plurality of data lines 14 and gate lines 15 are intersected on the display panel 100, and subpixels SP are disposed in a matrix form for each intersection area.

Subpixels SP As shown in FIG. 2, horizontally neighboring R subpixels for red display, G subpixels for green display, and B subpixels for blue display may be implemented. Here, it is possible to further include a W subpixel for white display, and the arrangement method of each pixel may also be variously changed.

Each sub-pixel SP is supplied with a supply terminal of a high potential driving voltage (EVDD) and a low potential driving voltage (EVSS) that supplies driving power to the cathode electrode (-) and the anode electrode (+) of the light emitting device (OLED). The stages are connected.

The data line 14 includes a first data line 14a through which the image data voltage Vdata is input in the normal mode and a reference data signal in the sensing mode, and a second data line 14b through which the sensing voltage is output. .

The gate line 15 includes a first gate line 15a through which a first scan signal Scan1 controlling an input of an image data voltage Vdata is input, and a second scan signal Scan2 controlling an output of a sensing voltage. The second gate line 15b is input.

In addition, the display panel 100 according to an exemplary embodiment of the present invention includes an SEL signal line SEL through which an SEL signal for controlling the sensing mode selection is input, and a cathode electrode of the light emitting device OLED when driving in the sensing mode (- ) Includes a VGL line that supplies a gate low voltage (VGL).

3 is a block diagram showing a configuration for detecting deterioration data of a light emitting device (OLED) in a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 3, in the display device according to an exemplary embodiment of the present invention, a first electrode (+) to which a first driving voltage (EVDD) is input and a second electrode (-) to which a second driving voltage (EVSS) is inputted The subpixel SP including the light emitting device OLED, the third driving voltage VGL having a lower potential than the second driving voltage EVSS and the second driving voltage EVSS, are connected to the second electrode (-). When the third driving voltage VGL is input to the selectively input switching unit 200 and the second electrode (-), the sensing data voltage VREF is supplied to the first electrode + and the sensing data voltage VREF is supplied. It includes a sensing unit (SU) for sensing the driving voltage characteristic (Vf) of the light emitting device (OLED), and an ADC that outputs the sensing result of the sensing unit (SU) as digital sensing data (SD). In the following description, the first driving voltage is EVDD, the second driving voltage is EVSS, and the third driving voltage is VGL, and the first electrode (+) of the light emitting element (OLED) is an anode electrode, and the second electrode (-) is It is called a cathode electrode.

The subpixel SP may include a light emitting device (OLED), a driving thin film transistor (DT), a storage capacitor (Cst), a first switch TFT (ST1), and a second switch TFT (ST2). .

The light emitting element OLED includes an anode electrode (+) connected to the source node Ns of the driving TFT DT, a cathode electrode (+) connected to the input terminal of the low potential driving voltage EVSS, and an anode electrode (+). ) And an organic compound layer positioned between the cathode electrode (-).

The driving TFT DT controls the amount of current input to the light emitting device OLED according to the gate-source voltage Vgs. The driving TFT DT includes a gate electrode connected to the gate node Ng, a drain electrode connected to the input terminal of the high potential driving voltage EVDD, and a source electrode connected to the source node Ns. The storage capacitor Cst is connected between the gate node Ng and the source node Ns. The first switch TFT ST1 applies the image data voltage Vdata on the data line 14a to the gate node Ng in response to the scan control signal SCAN. The first switch TFT ST1 includes a gate electrode connected to the first gate line 15a, a drain electrode connected to the data line 14A, and a source electrode connected to the gate node Ng. The second switch TFT ST2 switches the current flow between the source node Ns and the sensing line 14b in response to the sensing control signal SEN. The second switch TFT ST2 includes a gate electrode connected to the second gate line 15B, a drain electrode connected to the sensing line 14B, and a source electrode connected to the source node Ns. The 3T (Transistor) 1C (Capacitor) structure including the switching transistor SW, the driving transistor DR, the capacitor Cst, the organic light emitting diode OLED, and the sensing transistor ST for the abnormal subpixel SP Although the sub-pixel has been described as an example, when the compensation circuit CC is added, it may be composed of 3T2C, 4T2C, 5T1C, 6T2C, and the like.

The switching unit 200 according to the selection signal SEL for selecting a normal mode in which the image data voltage Vdata is supplied to the light emitting element OLED and a sensing mode in which the sensing data voltage VREF is supplied, the OLED ) Is switched so that EVSS or VGL is connected to the cathode electrode (-). The switching unit 200 is connected to the power line for inputting VGL to the first switch (SW1) and the cathode electrode (-) to which the source and drain are connected to the power line for inputting EVSS to the cathode electrode (-) of the light emitting element (OLED). A second switch SW2 connected to a source and a drain may be included. The first switch SW1 and the second switch SW2 may each have a gate electrode connected to a signal line to which the selection signal SEL is input. An inverter that inverts the input signal is interposed in the signal line to which the selection signal SEL is input, and input signals opposite to each other are input to the first switch SW1 and the second switch SW2. That is, when the high signal H is input to the second switch SW2, the low signal L is input to the first switch SW1, and the low signal L is input to the second switch SW2. A high signal H is input to the switch SW1. Therefore, when the first switch SW1 is turned on, the second switch SW2 is turned off, and when the first switch SW1 is turned off, the second switch SW2 is turned on, so that the cathode electrode of the light emitting element OLED ), EVSS or VGL may be selectively connected.

The sensing unit SU may be connected to the sensing line 14b of the sub-pixel SP to supply the data voltage VREF and sense the characteristic voltage Vf according to the driving of the light emitting device OLED.

In order to sense the light emission characteristic voltage Vf of the light emitting element OLED, a sensing capacitor Csen in which a voltage according to the driving characteristic of the light emitting element OLED is stored may be connected to the sensing line 14b of the subpixel SP. have. The sensing capacitor Csen is connected in parallel with the light emitting device OLED when the sensing data voltage VREF is supplied to charge the sensing data voltage VREF, and when the supply of the sensing data voltage is stopped, the charged sensing data voltage emits light. It can be supplied to the device (OLED).

The sensing capacitor Csen and the light emitting element OLED are connected in parallel, one end of which is connected to VGL, and the other end of which the sensing data voltage VREF is applied. Here, since VGL has a lower negative potential than EVSS, when one end of the sensing capacitor Csen is connected to VGL, it is possible to charge the sensing data voltage VREF even with a relatively low potential voltage. For example, in the case of a conventional display device, the sensing capacitor Csen and the light emitting element OLED are connected to the EVSS, and the EVSS is usually set to 0V. Therefore, it is possible to detect the deterioration characteristics of the light emitting device OLED only when the sensing data voltage VREF is inputted at about 8V. On the other hand, since the present invention charges the sensing data voltage VREF after connecting to VGL, which is a negative potential voltage lower than EVSS 0 V, even if a sensing data voltage VREF lower than 8 V is applied, the degradation characteristics of the light emitting device OLED are detected. can do.

In the sensing mode, the sensing data voltage VREF is supplied to the sub-pixel SP, and the sensing data voltage VREF is charged in the sensing capacitor Csen. Thereafter, when supply of the sensing data voltage VREF is stopped, the charging sensing data voltage VREF is supplied to the sensing capacitor Csen and discharged. Thereafter, the sensing unit SU detects the voltage discharged by the light emitting device OLED by detecting the remaining voltage of the sensing capacitor Csen to detect the driving voltage characteristic Vf of the light emitting device OLED. have.

By this configuration, the present invention, the sensing capacitor (Csen) and the light emitting device (OLED) is conventionally connected to the EVSS, the sensing data voltage (VREF) must have a sufficiently high voltage to deteriorate the characteristics of the light emitting device (OLED) On the other hand, the sensing data voltage (VREF) is charged after connecting the sensing capacitor (Csen) and the light emitting device (OLED) to VGL, which is a lower potential voltage than EVSS, so that the sensing data voltage (VREF) is relatively low. Even if applied, it is possible to detect the deterioration characteristics of the light emitting device (OLED).

FIG. 4 is a view showing the equivalent circuit of FIG. 3 centering on the operation of the switching unit in the sensing mode.

Referring to FIG. 4, the supply line of the sensing data voltage VREF is connected to the anode electrode + of the light emitting element OLED and the sensing capacitor Csen. Accordingly, the sensing data voltage VREF is charged to the anode electrode of the light emitting device OLED and the sensing capacitor Csen connected in parallel with the light emitting device OLED.

The first switch SW1 is connected to the power line inputting the EVSS to the cathode electrode (-) of the light emitting element OLED, and the second switch SW2 is connected to the power line inputting the VGL to the cathode electrode (-). . The first switch SW1 and the second switch SW2 are respectively connected to a gate electrode to a signal line to which the selection signal SEL is input. An inverter that inverts the input signal is interposed in the signal line to which the selection signal SEL is input, and input signals opposite to each other are input to the first switch SW1 and the second switch SW2. Therefore, when the first switch SW1 is turned on, the second switch SW2 is turned off, and when the first switch SW1 is turned off, the second switch SW2 is turned on to turn on the cathode electrode of the light emitting element OLED (-). EVSS or VGL can be selectively connected.

5A to 5C are diagrams for explaining a method of sensing degradation characteristics of a light emitting device (OLED) using the equivalent circuit of FIG. 4.

Referring to FIG. 5A, when the sensing mode is entered, a high signal (high), which is a sensing mode selection signal, is input to the mode selection signal SEL. The second switch SW2 is turned on by a high signal, and the first switch SW1 is turned off by receiving a low signal that is an inverted signal of the high signal high.

When the second switch SW2 is turned on, the VGL voltage is supplied to one end of the sensing capacitor Csen connected in parallel with the cathode electrode (-) of the light emitting element OLED and the light emitting element OLED.

The sensing data voltage VREF is applied to the anode electrode + and the sensing capacitor Csen of the light emitting device OLED so that the sensing data voltage VREF is charged to the sensing capacitor Csen. Here, since VGL has a lower negative potential than EVSS, it is possible to charge the sensing capacitor Csen by applying the sensing data voltage VREF having a lower potential than the conventional one.

Referring to FIG. 5B, when the supply of the sensing data voltage VREF is stopped, the sensing capacitor Csen and the light emitting device OLED are connected in series so that the sensing data voltage VREF charged in the sensing capacitor Csen is a light emitting device. (OLED). Accordingly, the voltage charged in the sensing capacitor Csen is discharged due to the light emission of the light emitting element OLED.

Referring to FIG. 5C, when the light emitting device OLED is turned off, the magnitude of the voltage remaining in the sensing capacitor Csen is sensed through the sensing line. By detecting the remaining voltage of the sensing capacitor Csen, it is possible to detect the voltage discharged by the light emitting device OLED to detect the driving voltage characteristic Vf of the light emitting device OLED.

FIG. 6 is a view showing the equivalent circuit of FIG. 3 centering on the operation of the switching unit in the normal mode.

Referring to FIG. 6, in the normal mode, the mode selection signal SEL receives a low signal, which is a normal mode selection signal. The second switch SW2 is turned off by a low signal, and the first switch SW1 is turned on by receiving a high signal high that is an inverted signal of the low signal low.

When the first switch SW1 is turned on, EVSS power is supplied to the cathode electrode (−) of the light emitting element (OLED).

The image data voltage Vdata is applied to the anode electrode + of the light emitting element OLED, and the light emitting element OLED emits light according to the image data voltage Vdata.

A method of driving a display device according to an exemplary embodiment of the present invention will be described with reference to FIGS. 7 to 11.

7 is a diagram showing in detail a wiring connection between a data drive IC (DIC and a pixel array) of a display device according to an embodiment of the present invention, and FIG. 8 is a deterioration of the light emitting device (OLED) of the display device of FIG. 7 in a sensing mode. It is a diagram showing an equivalent circuit of a circuit for sensing characteristics.

Referring to FIG. 7, the data driver 120 may include one or more data drive ICs (DICs). In this embodiment, a case in which three data drive ICs (DIC # 1 to DIC # 3) are configured will be exemplified. Each data drive IC (DIC # 1 to DIC # 3) converts digital image data (DATA) input from the timing controller 110 (refer to FIG. 1) into image data voltage (Vdata) in a positive / negative analog format. It outputs to the data line 14 (refer FIG. 1).

Each data drive IC DIC # 1 to DIC # 3 has sensing units SU1 and SU2 for detecting the driving voltage characteristic Vf of the light emitting element OLED from the subpixels SP connected to the data line 14 , SU3). Subpixels SP receiving the analog image data voltage Vdata of the same color may be connected to one data line. For example, R subpixels for red display are connected to the first data drive IC (DIC # 1), G subpixels for green display are connected to the second data drive IC (DIC # 2), and the third data drive IC ( B subpixels for blue display may be connected to DIC # 3).

The display panel 100 receiving the image data voltage Vdata from the data drive ICs DIC # 1 to DIC # 3 selects the image data voltage Vdata or the sensing data voltage VREF for each subpixel SP. It includes multiplexers (M1, M2, M3) for input. On / off operation of the multiplexers M1, M2, and M3 may be controlled according to the multiplexer control signals D_Mux, S_Mux, and REF_CTRL input from the timing controller 110.

The first multiplexer M1 operates on / off according to the D_Mux signal to convert the image data voltage Vdata from the data drive ICs DIC # 1 to DIC # 3 into data lines connected to each subpixel SP during turn-on operation. To deliver.

The second multiplexer M2 operates on / off according to the S_Mux signal to supply the sensing data voltage VREF to each subpixel SP, and detects the driving voltage characteristic Vf detected by each subpixel SP To the sensing units SU1, SU2, and SU3.

The third multiplexer M3 operates on / off according to the REF_CTRL signal to connect the sensing data control line VREF to control the size of the sensing data voltage VREF supplied to the data line during the turn-on operation.

8 is a view showing an equivalent circuit of a circuit for sensing the deterioration characteristics of the light emitting device (OLED) of the display device of FIG. 7 in the sensing mode.

Referring to FIG. 8, the subpixel may have a 6T1C structure. Since the sub-pixel is not driven in the sensing mode, detailed description of the sub-pixel structure and driving method is omitted.

The first switch (SW1) with source and drain connected to the power line inputting EVSS as the cathode electrode (-) of the light emitting element (OLE) and the source and drain connected to the power line inputting VGL with the cathode electrode (-). It may include two switches (SW2). The first switch SW1 and the second switch SW2 may each have a gate electrode connected to a signal line to which the selection signal SEL is input. An inverter that inverts the input signal is interposed in the signal line to which the selection signal SEL is input, and input signals opposite to each other are input to the first switch SW1 and the second switch SW2.

In order to sense the light emission characteristic voltage Vf of the light emitting element OLED, a sensing capacitor Csen in which a voltage according to the driving characteristic of the light emitting element OLED is stored may be connected to the sensing line 14b of the subpixel SP. have. When the sensing data voltage VREF is supplied, the sensing capacitor Csen is connected in parallel with the light emitting device OLED to charge the sensing data voltage, and when the supply of the sensing data voltage is stopped, the charged sensing data voltage is charged to the light emitting device OLED. ).

When the sensing data voltage is supplied, the sensing capacitor Csen is connected in parallel with the light emitting device OLED to charge the sensing data voltage. When the sensing data voltage is stopped, the charged sensing data voltage is supplied to the light emitting device OLED. You can. The sensing capacitor Csen and the light emitting element OLED are connected in parallel, one end of which is connected to VGL, and the other end of which the sensing data voltage VREF is applied. Since VGL has a lower negative potential than EVSS, which is usually 0V, when one end of the sensing capacitor Csen is connected to VGL, it is possible to charge the sensing data voltage VREF even with a relatively low potential voltage. In the case of the conventional display device, the sensing capacitor Csen and the light emitting element OLED are connected to the EVSS, and the EVSS is usually set to 0V. Therefore, it is possible to detect the deterioration characteristics of the light emitting device OLED only when the sensing data voltage VREF is inputted at about 8V. On the other hand, since the present invention charges the sensing data voltage VREF after connecting to VGL, which is a negative potential voltage lower than EVSS 0 V, even if a sensing data voltage VREF lower than 8 V is applied, the degradation characteristics of the light emitting device OLED are detected. can do.

The sensing unit SU includes an SCS switch and a PRE switch that controls the input of the sensing data voltage VREF for sensing, and a SEN switch that detects and outputs the remaining voltage of the sensing capacitor Csen of each subpixel SP. Includes. The sensing unit SU senses the voltage remaining in the sensing capacitor Csen of each subpixel SP and outputs it to the ADC. The ADC converts the output of the sensing unit SU into digital and feeds back the sensing data SD to the timing controller 110.

9A to 9C are diagrams for specifying a circuit operation for sensing deterioration characteristics of a light emitting device (OLED), FIG. 10 is a diagram showing a circuit operation in a normal mode, and FIG. 11 is a sensing mode and a normal mode It is a signal waveform diagram. In this embodiment, the case where the first switch SW1, the second switch SW2, the first multiplexer M1 and the second multiplexer M2 are PMOS TFTs having active low characteristics is illustrated.

9A to 9C show a sensing mode driving process, and correspond to sections ①, ②, and ③ in the waveform diagram of FIG. 11, respectively.

9A and 11, the selection signal SEL is input low during the sensing mode driving period (①, ②, ③). Accordingly, the first switch SW1 is turned off and the second switch SW2 is turned on. When the second switch SW2 is turned on, the VGL voltage is supplied to one end of the sensing capacitor Csen connected in parallel with the cathode electrode (-) of the light emitting element OLED and the light emitting element OLED.

During the first ① section of the sensing mode, the PRE switch of the sensing unit SU is turned on so that the sensing data voltage VREF is supplied to the data line. On the other hand, the SEN switch of the sensing unit SU remains off.

During the sensing mode driving period (①, ②, ③), the S_Mux signal is input low, and the second multiplexer M2 remains turned on. When the second multiplexer M2 is turned on, the sensing data voltage VREF is supplied to each sub-pixel SP.

On the other hand, the D_Mux signal is input high and the first multiplexer M1 maintains a turn-off state. When the first multiplexer M1 is turned off, the supply of the image data voltage Vdata is cut off.

By the above operation, in the first section ① of the sensing mode, the VGL voltage is supplied to one end of the sensing capacitor Csen connected in parallel with the cathode electrode (-) of the light emitting element OLED and the light emitting element OLED. The sensing data voltage VREF is applied to the anode electrode + and the sensing capacitor Csen of the light emitting device OLED so that the sensing data voltage VREF is charged to the sensing capacitor Csen. In the waveform diagram of FIG. 11, Vx represents a voltage change of the sensing capacitor Csen. Here, since VGL has a lower negative potential than EVSS, it is possible to charge the sensing capacitor Csen by applying the sensing data voltage VREF having a lower potential than the conventional one.

9B and 11, in the section ② of the sensing mode, the PRE switch of the sensing unit SU is turned off to stop supply of the sensing data voltage VREF. The SEN switch of the sensing unit SU also remains off.

When the supply of the sensing data voltage VREF is stopped in section ② of the sensing mode, the sensing capacitor Csen and the light emitting device OLED are connected in series so that the sensing data voltage VREF charged in the sensing capacitor Csen is a light emitting device. (OLED). Accordingly, the voltage Vx charged in the sensing capacitor Csen is discharged due to the light emission of the light emitting element OLED.

9C and 11, the SEN switch of the sensing unit SU is turned on in section ③ of the sensing mode.

Section ③ of the sensing mode may start when the light emitting device (OLED) is off. When the SEN switch of the sensing unit SU is turned on after the light emitting device OLED is turned off, the voltage remaining in the sensing capacitor Csen is input to the sensing unit SU. The sensing unit SU senses the voltage remaining in the sensing capacitor Csen and outputs it to the ADC. The ADC converts the output of the sensing unit SU into digital and feeds back the sensing data SD to the timing controller 110.

The timing controller 110 detects the voltage discharged by the light emitting device OLED according to the sensing data voltage VREF and the remaining voltage of the sensing capacitor Csen to detect the driving voltage characteristic Vf of the light emitting device OLED. You can.

10 and 11, the selection signal SEL is input high during the normal mode driving period. Accordingly, the first switch SW1 is turned on and the second switch SW2 is turned off.

When the first switch SW1 is turned on, EVSS power is supplied to the cathode electrode (−) of the light emitting element (OLED).

During the normal mode driving period, the PRE switch and the SEN switch of the sensing unit SU remain off.

The D_Mux signal is input low, and the first multiplexer M1 maintains a turn-on state. When the first multiplexer M1 is turned on, the image data voltage Vdata is input to the subpixel SP, and the light emitting device OLED emits light according to the image data voltage Vdata.

During the normal mode driving period, the S_Mux signal is input high, and the second multiplexer M2 remains turned off.

As described above, the present invention performs a sensing operation by connecting EVSS when driving in normal mode and connecting VGL in sensing mode. Thus, in the past, the sensing capacitor Csen and the light emitting device OLED are connected to EVSS having 0V, so that the sensing data voltage VREF must have a sufficiently high voltage to detect deterioration characteristics of the light emitting device OLED. On the other hand, since the sensing capacitor (Csen) and the light emitting device (OLED) are connected to VGL, which is a lower negative potential voltage than EVSS, the sensing data voltage (VREF) is charged, so even if a relatively low sensing data voltage (VREF) is applied, OLED) can be detected. In other words, when sensing the degradation characteristics of the light emitting device (OLED), since sensing is possible with a significantly lower sensing data voltage (VREF) than before, the sensing mode is freely and easily driven for voltage specifications limited to each component of the display device. It is possible to reduce power consumption during the sensing mode driving period.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the technical configuration of the present invention described above is in other specific forms without changing the technical concept or essential features of the present invention by those skilled in the art to which the present invention pertains. It will be understood that it can be practiced. Therefore, the embodiments described above are to be understood in all respects as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the claims below, rather than the detailed description. In addition, all modifications or variations derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

100: display panel 110: timing control
120: data driver 130: scan driver
200: switching unit

Claims (20)

A light emitting device having a first electrode to which a first driving voltage is input and a second electrode to which a second driving voltage having a potential lower than that of the first driving voltage is input;
A switching unit selectively inputting the second driving voltage and a third driving voltage having a potential lower than that of the second driving voltage to the second electrode; And
A sensing unit configured to detect a driving voltage characteristic of the light emitting device by supplying a sensing data voltage to the first electrode when the third driving voltage is input to the second electrode;
Display device comprising a. According to claim 1,
The switching unit,
When the normal mode selection signal to which the image data voltage is supplied is input to the light emitting element, the second driving voltage is input to the second electrode,
A display device operable to input the third driving voltage to the second electrode when a sensing mode selection signal to which the sensing data voltage is supplied is input. According to claim 2,
The switching unit,
A first TFT connected to a supply line of the second electrode and the third supply voltage and turned on according to the sensing mode selection signal input to a gate electrode; And
A second TFT connected to a supply line of the second electrode and the second driving voltage and turned on according to the normal mode selection signal input to a gate electrode;
Display device comprising a. According to claim 1,
The first driving voltage is a high potential driving voltage (EVDD);
The second driving voltage includes a low potential driving voltage (EVSS); And
The third driving voltage may include a gate low voltage (VGL);
Display device comprising a. According to claim 1,
When the sensing data voltage is supplied, it is connected to the light emitting device in parallel to charge the sensing data voltage, and when the supply of the sensing data voltage is stopped, a sensing capacitor further supplying the charged sensing data voltage to the light emitting device Display device. According to claim 4,
The sensing unit,
A display device that detects a voltage other than the voltage discharged by the light emitting element from the sensing data voltage charged in the sensing capacitor. According to claim 1,
The switching unit outputs a mode selection signal to select the second driving voltage or the third driving voltage, and outputs an image data voltage supplied to the light emitting device based on the driving voltage characteristic of the light emitting device received from the sensing unit. A display device comprising a timing controller to compensate. The method of claim 7,
The mode selection signal,
A display device comprising a normal mode selection signal to which the image data voltage is supplied to the light emitting element and a sensing mode selection signal to which the sensing data voltage is supplied. A light emitting device having an anode electrode and a cathode electrode, a switch TFT that connects a data line to which the image data voltage is supplied to the anode electrode in normal mode and a sensing line to which a sensing data voltage is supplied to the anode electrode in sensing mode. A subpixel;
A first wiring supplying a gate low voltage (VGL) to the cathode electrode;
A second wiring supplying a low potential driving voltage (EVSS) to the cathode electrode;
A first switch selectively connecting the first wiring to the cathode electrode in the sensing mode;
A second switch connecting the second wiring to the cathode electrode in the normal mode;
Display device comprising a. The method of claim 9,
The first switch includes a first TFT connected to a source electrode and a drain electrode to the cathode electrode and the first wiring and turned on according to the sensing mode selection signal input to the gate electrode,
The second switch includes a second TFT connected to a source electrode and a drain electrode to the cathode electrode and the second wiring and turned on according to the normal mode selection signal input to the gate electrode. The method of claim 9,
And a switch TFT connecting a power line supplying the image data voltage to the anode electrode in the normal mode. The method of claim 9,
One end is connected to the gate low voltage (VGL) and the other end is connected to the sensing line, the display device including a sensing capacitor connected in parallel with the light emitting element in the sensing mode. The method of claim 12,
The sensing capacitor,
In the sensing mode, the power is charged as much as the difference between the gate low voltage (VGL) and the sensing data voltage, and when the sensing data voltage is not supplied, charged power is input to the anode electrode of the light emitting device connected to the sensing line. Display device. In the driving method of a display device including a light emitting element having a first electrode to which the first driving voltage is input and a second electrode to which the second driving voltage is input,
Connecting a third driving voltage lower than the second driving voltage to the second electrode in the sensing mode;
Supplying a sensing data voltage to the first electrode;
Emitting the light emitting element with the sensing data voltage; And
Sensing a driving voltage characteristic of the light emitting device by sensing a voltage other than the voltage discharged by the light emitting device from the sensing data voltage;
Method of driving a display device comprising a. The method of claim 14,
Connecting the second driving voltage to the second electrode in the normal mode;
Supplying an image data voltage to the first electrode; And
Emitting the light emitting element with the image data voltage
Method of driving a display device comprising a. The method of claim 15,
When the normal mode selection signal is input, the second driving voltage is input to the second electrode, and when the sensing mode selection signal is input, a switching unit operable to input the third driving voltage to the second electrode. How to drive the display device. The method of claim 14,
One end is connected to the third driving voltage and the other end is connected to the sensing line and includes a sensing capacitor connected in parallel to the light emitting device in the sensing mode,
The step of supplying the sensing data voltage to the first electrode,
And supplying the sensing data voltage to the light emitting element and the sensing capacitor through the sensing line. The method of claim 17,
The step of emitting the light emitting device with the sensing data voltage,
When the supply of the sensing data voltage is stopped, the sensing capacitor is connected to the first electrode of the light emitting device in series, so that the sensing data voltage charged in the sensing capacitor is input to the light emitting device. Driving method. The method of claim 18,
In the sensing data voltage, detecting the remaining voltage excluding the voltage discharged by the light emitting device to detect driving voltage characteristics of the light emitting device,
And detecting a driving voltage characteristic of the light emitting device based on a voltage other than the voltage discharged by the light emitting device from the sensing data voltage charged in the sensing capacitor. The method of claim 19,
And compensating for the image data voltage based on the driving voltage characteristic of the light emitting element.

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