KR20200077929A - Electroluminescent Display Device - Google Patents

Abstract

An electroluminescent display device of the present invention includes: a data voltage line to which a data voltage is supplied; a reference voltage line to which a reference voltage is supplied; a driving element including a first electrode connected to a first node, a gate connected to a second node, and a second electrode connected to a third node which is connected to a light emitting element and supplying current to the light emitting element; a first switch connecting the second node and the data voltage line in response to a first scan signal; a second switch connecting the third node and the reference voltage line in response to a second scan signal; and a third switch for inputting a driving setting signal having a voltage of a first level for initializing the driving element to the second node, and a drive setting signal having a voltage of a second level for writing black data to the driving element in response to a third scan signal. Therefore, the number of TFTs included in the pixel can be reduced while ensuring the same performance as a conventional pixel.

Description

Electroluminescent display device

The present invention relates to an electroluminescent display device.

The electroluminescent display device is roughly classified into an inorganic light emitting display device and an organic light emitting display device according to the material of the light emitting layer. Among them, an active matrix type organic light emitting display device includes an organic light emitting diode (hereinafter referred to as “OLED”) that emits light by itself.

The organic light emitting display device arranges pixels including OLEDs in a matrix form and adjusts the luminance of the pixels according to the gradation of image data. Each of the pixels basically includes a driving thin film transistor (TFT) that controls the driving current flowing through the OLED according to the voltage between the gate and the source, and one or more switch TFTs for programming the voltage between the gate and sort of the driving TFT.

Organic light emitting display devices are advantageous in thinning, low power consumption, fast response speed, high luminous efficiency, high brightness, and wide viewing angles, which have been applied to various fields.

Accordingly, research is being conducted to improve performance and lifetime while maintaining the advantages of the organic light emitting display device.

The present invention provides an electroluminescent display device capable of securing a pixel design area and improving the lifespan of a display device by ensuring that the number of TFTs included in the pixel is reduced while ensuring the same performance as that of a conventional pixel. .

An electroluminescent display device according to another embodiment of the present invention includes a data voltage line to which a data voltage is supplied; A reference voltage line to which a reference voltage is supplied; A driving element for supplying current to the light emitting element, including a first electrode connected to a first node, a gate connected to a second node, and a second electrode connected to a third node connected to a light emitting element; A first switch connecting the second node and the data voltage line in response to a first scan signal; A second switch connecting the third node and the reference voltage line in response to a second scan signal; And a third switch inputting a drive setting signal having a first level voltage for initializing the drive element to the second node and a second level voltage for writing black data to the drive element in response to a third scan signal. ;.

A capacitor connected to one end of the second node and the other end to the third node may be further included.

And a gate driver for generating the first scan signal, the second scan signal, and the third scan signal and supplying them to the corresponding scan line, and generating the drive setting signal and outputting the drive setting signal to a drive line to which the third switch is connected. Can.

The third switch may include: a gate electrode receiving the third scan signal; A first electrode receiving the driving setting signal; And a second electrode connected to the second node.

The driving element may block a current supplied to the light emitting element when a drive setting signal having the second level voltage is input to the gate connected to the second node.

One frame period includes: an initialization period for initializing the voltage between the gate sources of the driving element; A sensing period for sensing the threshold voltage of the driving element in the capacitor; A data writing period for writing the data voltage to the gate of the driving element; A light emitting period in which the sensed threshold voltage and the data voltage are reflected in the gate source potential of the driving element to supply current to the light emitting element; And a black voltage writing period in which the black voltage is written to the gate of the driving element to turn off the driving element.

In the data writing period, the first scan signal is input at an on-level, and in the initialization period, the second scan signal is input at an on-level, and in the initialization period, the sensing period, and the black voltage writing period, the third The scan signal can be input at an on level.

The driving setting signal may be input as the first level voltage in the initialization period and the sensing period, and may be input as the second level voltage in the data writing period, the light emitting period, and the black voltage writing period.

The first level voltage may be set to a voltage level higher than the reference voltage and lower than the turn-on voltage of the light emitting device, and the second level voltage may be set to a voltage level less than the threshold voltage of the light emitting device.

The electroluminescent display device according to another embodiment of the present invention includes a plurality of data voltage lines to which a data voltage is supplied, a reference voltage line to which a reference voltage is supplied, a scan line to which a scan signal is supplied, and a drive line to which a drive setting signal is supplied. A display panel having pixels connected to each of the pixels, wherein each pixel disposed in the n (n is a natural number) pixel row includes a cathode electrode connected to an input terminal of a low potential driving voltage and an anode electrode connected to a third node. Light-emitting element having a; A driving TFT including a drain electrode connected to a first node to which a high potential driving voltage is input, a gate electrode dedicated to a second node, and a drain electrode connected to the third node to control the driving current applied to the light emitting device. ; A first switch connected between the second node and the data voltage line; A second switch connected between the third node and the reference voltage line; A capacitor having one end connected to the first node and the other end connected to the second node; And a third switch connected to the second node to control the input of a drive setting signal having a first level voltage for initializing the drive element and a second level voltage for writing black data to the drive element. can do.

According to the present invention, the gate electrode of the driving TFT may be initialized or black data may be input using the driving setting signal Vset input to the gate electrode of the driving TFT. Adjusting the input time of the black data can control the emission time to control the emission duty. As a result, since the duty driving is possible even without the light emitting TFT, the design area required when applying the light emitting TFT can be saved and the life of the display device can be extended by removing the stress of the substrate due to the signal applied for driving the light emitting TFT.

1 is a control block diagram of an electroluminescent display device according to an exemplary embodiment of the present invention.
2 is a circuit diagram of a pixel included in the electroluminescent display of FIG. 1.
3 is a driving waveform diagram of the pixel of FIG. 2.
4A and 4B are equivalent circuits and driving waveform diagrams of pixels corresponding to an initialization period t1.
5A and 5B are equivalent circuits and driving waveform diagrams of pixels corresponding to the first sensing period (Sensing) t2.
6A and 6B are equivalent circuits and driving waveform diagrams of pixels corresponding to the second sensing period (Sensing) t3.
7A and 7B are equivalent circuits and driving waveform diagrams of pixels corresponding to data image data writing period t4.
8A and 8B are equivalent circuits and driving waveform diagrams of pixels corresponding to the emission period t5.
9 to 10 are equivalent circuits and driving waveform diagrams of pixels corresponding to the black data writing periods Black (t6 and t7).

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains. It is provided to completely inform the person having the scope of the invention, and the present invention 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 invention are exemplary, and the present invention is not limited to the illustrated matters. The same reference numerals refer to the same components throughout the specification. In addition, in the description of the present invention, when it is determined that detailed descriptions of related known technologies may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted. 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 interpreting 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 the 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.

In the description of the embodiments, the first, second, etc. are 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 invention.

The same reference numerals refer to the same components throughout the specification.

Each of the features of the various embodiments of the present invention may be partially or wholly combined with or combined with each other, technically various interlocking and driving may be possible, and each of the embodiments may be independently implemented with respect to each other or may be implemented together in an association relationship. It might be.

In the electroluminescent display device of the present invention, the pixel circuit may include one or more of an n-channel transistor and a p-channel transistor. Transistors may be implemented with an oxide semiconductor thin film transistor (TFT), an LTPS TFT including a low temperature polysilicon (LTPS). Further, each of the transistors can be implemented with a p-channel TFT or an n-channel TFT. In the embodiment, the transistors of the pixel circuit are mainly described as an example implemented with a p-channel TFT, but the present invention is not limited thereto.

Transistors are three-electrode devices, including gates, sources, and drains. The source is an electrode that supplies a carrier to the transistor. In the transistor, carriers begin to flow from the source. The drain is an electrode through which a carrier is driven out of the transistor. In the transistor, the carrier flows from source to drain. In the case of an n-channel transistor, 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 n-channel transistors, the direction of current flows from drain to source. In the case of the p-channel transistor (PMOS), since the carrier is a hole, the source voltage is higher than the drain voltage so that holes can flow from the source to the drain. In the p-channel transistor, 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 transistor are not fixed. For example, the source and drain may be changed according to the applied voltage. Therefore, the invention is not limited due to the source and drain of the transistor. In the following description, the source and drain of the transistor will be referred to as first and second electrodes.

The gate signal swings between a gate on voltage and a gate off voltage. The gate-on voltage is set to a voltage higher than the threshold voltage of the transistor, and the gate-off voltage is set to a voltage lower than the threshold voltage of the transistor. The transistor is turned on in response to the gate on voltage, while it is turned off in response to the gate off voltage. In the case of an n-channel transistor, the gate-on voltage may be a gate high voltage (VGH), and the gate-off voltage may be a gate low voltage (VGL). In the case of a p-channel transistor, the gate-on voltage may be a gate low voltage (VGL), and the gate-off voltage may be a gate high voltage (VGH).

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following embodiments, the electroluminescent display device is mainly described, but is not limited to, an organic light emitting display device including an organic 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 view showing an electroluminescent display device according to an embodiment of the present invention.

Referring to FIG. 1, an organic light emitting display device according to an exemplary embodiment of the present invention includes a display panel 10 on which pixels PXL are formed, a data driver 12 for driving data lines DL, and a gate It includes a gate driver 13 for driving the lines GL, and a timing controller 11 for controlling each of the drivers 12 and 13.

A plurality of data lines 14 and a plurality of gate lines 15 are crossed on the display panel 10, and pixels PXL are arranged in a matrix form. The pixels PXL may include a light emitting device (OLED). The self-luminous device, OLED, includes an anode electrode and a cathode electrode, and an organic compound layer formed therebetween. The pixels PXL may include a light emitting device (OLED). The self-luminous device, OLED, includes an anode electrode and a cathode electrode, and an organic compound layer formed therebetween. The organic compound layer includes a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (Electron Injection Layer, EIL). When a power voltage is applied to the anode electrode and the cathode electrode, holes passing through the hole transport layer (HTL) and electrons passing through the electron transport layer (ETL) are moved to the emission layer (EML) to form excitons, and as a result, the emission layer (EML) Visible light is generated. Each of the pixels PXL may be any one of a red pixel, a green pixel, a blue pixel, and a white pixel. The red pixel, the green pixel, the blue pixel, and the white pixel may constitute one unit pixel for color realization. The color implemented in the unit pixel may be determined according to the emission ratio of the red pixel, the green pixel, the blue pixel, and the white pixel. Meanwhile, the white pixel may be omitted from the unit pixel. These pixels PXL may be commonly supplied with high potential and low potential driving voltages EVDD and EVSS and a reference voltage Vref.

The timing controller 11 rearranges digital video data (RGB) input from the outside according to the resolution of the display panel 10 and supplies it to the data driver 12. In addition, the timing controller 11 is based on timing signals such as a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), a dot clock signal (DCLK), and a data enable signal (DE) of the data driver 12 The data control signal DDC for controlling the operation timing and the gate control signal GDC for controlling the operation timing of the gate driver 13 are generated.

The data driver 12 converts digital video data RGB input from the timing controller 11 into an analog image data voltage Data based on the data control signal DDC. The data driver 12 may further include a power generator. The power generator may generate a reference voltage REF and supply it to the reference power line. The reference voltage REF may be set to a voltage range sufficiently lower than the operating point voltage of the OLED to prevent unnecessary emission of the OLED during the sensing period and the data writing period.

The gate driver 13 may generate a scan signal SCAN and a drive set signal Vset based on the gate control signal GDC. The gate driver 13 generates scan signals SCAN and driving set signals Vset in a row sequential manner to drive at least one gate line GL connected to each pixel row and supplies them to the gate lines GL. Can.

The scan signal SCAN is a signal for turning on/off a switch included in a pixel in a display panel and has a gate high voltage (VGH) and a gate low voltage (VGL). In general, VGH can be set to about 10V and VGL to -6V.

The driving set signal Vset is generated in a voltage range different from the scan signal SCAN. The driving set signal Vset has a first level voltage for initializing the gate electrode during initialization and sensing of the driving TFT DT and a second level voltage for writing a black voltage to the gate electrode of the driving TFT DT.

The first level voltage may be set to a voltage level higher than the reference voltage Ref and lower than the OLED turn-on voltage. In the following description, the first level voltage of the driving setting signal Vset is referred to as an initialization voltage V _ini . The second level voltage is set to a voltage level capable of writing black gradation data to the gate electrode of the driving TFT DT. That is, it may be set to a voltage level capable of turning off the driving TFT DT so as to stop light emission of the OLED. Accordingly, the second level voltage may be set to a voltage level smaller than the threshold voltage Vth of the driving TFT DT. When the driving set signal Vset having the second level voltage is input to the driving TFT DT, the driving TFT DT may turn off to stop the emission of the OLED. In the following description, the second level voltage of the driving setting signal Vset is referred to as a black voltage V _Black .

The driving set signal Vset has an initialization voltage V _ini in the initialization and sensing periods, and a black voltage V _Black in other periods. Since the emission of the OLED is stopped when the driving set signal Vset is input as the black voltage V _Black , duty driving to adjust the emission period of the OLED may be performed using the driving set signal Vset.

2 is a circuit diagram showing pixels of a display device according to a first exemplary embodiment of the present invention, and FIG. 3 is a waveform diagram showing driving waveforms of the pixels illustrated in FIG. 2.

Referring to FIGS. 2 and 3, one pixel is disposed in a region where data lines DL arranged in a vertical direction and gate lines GL arranged in a horizontal direction intersect.

The data line DL may include a data voltage line 210 to which an analog data voltage Data is supplied and a reference voltage line 212 to which a reference voltage Ref is supplied. The gate line GL includes scan lines 201 to 203 to which the first to third scan signals SCAN1 to 3 are supplied, and a drive line 200 to which the drive setting signal Vset is supplied.

The pixel PXL according to an exemplary embodiment of the present specification includes an OLED, a plurality of thin film transistors (TFTs) T1 to T3, and a capacitor Cst. The TFTs T1 to T3 and DT may be implemented as an n-type MOSFET, a p-type MOSFET, a complementary metal semiconductor (CMOS) TFT, or the like. This embodiment exemplifies a case implemented with an n type TFT, and when implemented with a P type, the waveforms of the first to third scan signals SCAN1-3 in FIG. 3 may be inverted.

Each pixel has a data voltage at the gate of the driving transistor DR according to the first scan signal SCAN1 and the driving transistor DR input to the anode electrode of the OLED according to the voltage difference between the light emitting device OLED and the gate and the source. The first switch T1 inputting (Data), the second switch T2 inputting the reference voltage Ref to the second electrode of the driving transistor DR according to the second scan signal SCAN2, the third scan And a second switch T2 for inputting the driving set signal Vset to the gate electrode of the driving transistor DR according to the signal SCAN3.

The anode electrode of the OLED is connected to the third node (n3), and the cathode electrode of the OLED is connected to the EVSS electrode to which the low potential power voltage (EVSS) is applied. An organic compound layer is provided between the anode electrode and the cathode electrode.

The driving TFT (DT) adjusts the driving current applied to the OLED according to the voltage between the gate and the source. The driving TFT DT includes a first electrode connected to the first node n1, a second electrode connected to the third node n3, and a gate electrode connected to the second node n2. The high potential driving voltage EVDD is connected to the first node n1. The anode electrode of the OLED and the second electrode of the second switch are connected to the third node n3. The second electrode of the first switch T1 and the second electrode of the third switch T3 are connected to the second node n2. The light emitting element OLED emits light with a current Ids flowing according to the gate-source voltage Vgs of the driving element DT. Accordingly, the current path of the light emitting element OLED may be controlled by the first and third switch elements T1 and T3 connected to the gate electrode of the driving TFT DT.

The capacitor Cst is connected between the second node n2 and the first node n1. The capacitor Cst is charged with the image data voltage Data compensated by the threshold voltage Vth of the driving element DT to maintain the voltage between the gate and source of the driving TFT DT when the OLED emits light.

The first switch T1 includes a gate electrode to which the first scan signal Scan1 is input, a first electrode connected to the second node n2, and a second electrode connected to the data voltage line 210. The first switch T1 is turned on by the gate-on voltage of the first scan signal Scan1 to connect the data voltage line 210 to which the data voltage Data is input and the second node n2.

The second switch T2 includes a gate electrode to which the second scan signal Scan2 is input, a first electrode connected to the reference voltage line 212 and a second electrode connected to the third node n3. The second switch T2 is turned on by the gate-on voltage of the second scan signal Scan2 to connect the reference voltage line 212 to which the reference voltage Vref is input and the third node n3.

The third switch T3 includes a gate electrode to which the third scan signal Scan3 is input, a first electrode to which the driving setting signal Vset is input, and a second electrode to which the second node N2 is connected. The third switch T3 is turned on by the gate-on voltage of the third scan signal Scan3 and inputs the driving set signal Vset input through the driving line 200 to the second node N2.

3 is a waveform diagram showing a driving waveform of the pixel illustrated in FIG. 2 .

As shown in FIG. 3, one frame period is an initialization period (t1), a sensing period (Sensing) (t2, t3), an image data writing period (Writing) (t4), an emission period (Emission) (t5), The black voltage writing periods Black (t6, t7) may be included.

The first scan signal Scan1 is input at an on level in the image data writing period t4 to turn on the first switch T1.

The second scan signal Scan2 is input at an on level in the initialization period t1 to turn on the second switch T2.

The third scan signal Scan3 is input at an on level in the initialization period (t1) and the first sensing period (Sensing) (t2), and then switched to an off level, and thereafter, the black voltage writing period (Black) ( t6) is input again.

When the switches T1 to T3 are n-type TFTs, the first to third scan signals Scan 1, Scan 2, and Scan 3 are gate high voltages VGH that are voltages higher than the threshold voltages of the switches T1 to T3. ) And the gate low voltage VGL lower than the threshold voltages of the switch elements S1 to S3.

The driving set signal Vset is generated at a voltage level different from the first to third scan signals Scan 1, Scan 2, and Scan 3. The driving setting signal Vset is input as an initialization voltage V _ini having an initialization voltage level in an initialization period (t1) and a first sensing period (Sensing) (t2). It is input as a black voltage (V _BLACK ) having a corresponding level. The initialization voltage V _ini may be set to a voltage level higher than the reference voltage Ref and lower than the OLED turn-on voltage. The black voltage V _BLACK may be set to a voltage sufficient to turn off the driving TFT DT, for example, a voltage lower than the threshold voltage Vth of the driving TFT DT.

Upon receiving the driving signal, the pixel of FIG. 2 may perform an initialization operation, a sensing operation, a data writing operation, an emission operation, and a black voltage writing operation. When the black voltage write operation is performed, emission of the OLED is stopped, so that the emission time can be controlled using the driving set signal Vset.

Hereinafter, a driving operation of a pixel according to an exemplary embodiment of the present invention will be described step by step with reference to FIGS. 4 to 9.

4A shows an equivalent circuit of a pixel corresponding to an initialization period (Initial) t1, and FIG. 4B shows a period corresponding to the initialization period (Initial) t1 and the gate-source voltage of the driving TFT DT It is a graph showing. The initializing period (Initial) t1 is a period for initializing the gate voltage Vg of the driving TFT DT.

4A and 4B, during the initialization period (Initial) t1, the first scan signal Scan1 is input at an off level, the second scan signal Scan2 is input at an on level, and the third scan signal is (Scan3) is input at the on level. The driving set signal Vset is input as the initialization voltage V _ini .

The first switch T1 is turned off in response to the first scan signal Scan1 input at the off level. The second switch T2 is turned on in response to the second scan signal Scan2 input at the on level, and the third switch T3 is turned on in response to the third scan signal Scan3 input at the on level. .

The second switch T2 is turned on by the second scan signal Scan2 input to the on level to connect the reference voltage line 212 and the third node n3 to which the reference voltage Ref is supplied. Accordingly, a reference voltage Ref is input to the third node n3.

The third switch T3 is turned on by the third scan signal Scan3 input at the on level to input the initialization voltage V _ini to the second node n2.

Accordingly, an initialization voltage V _ini is input to the gate of the driving TFT DT connected to the second node n2, and a reference voltage Ref is applied to the source electrode of the driving TFT DT connected to the third node n3. This input is used to initialize the gate-source voltage of the driving TFT DT. Here, the reference voltage Ref input to the source electrode of the driving TFT DT is a voltage lower than the voltage for driving the OLED, and the OLED is not driven.

5A shows an equivalent circuit of a pixel corresponding to the first sensing period (Sensing) t2, and FIG. 5B is a gate corresponding to the first sensing period (Sensing) t2 and the gate of the driving TFT (DT) -It is a graph showing the voltage between sources. The first sensing period (Sensing) t2 and the second sensing period (t3) are for sensing the threshold voltage of the TFT (DT) of the driving TFT (DT).

5A and 5B, in the first sensing period (Sensing) t2, the first scan signal Scan1 and the second scan signal Scan2 are input at an off level, and the third scan signal Scan3 is It is entered on-level. The driving set signal Vset is input as the initialization voltage V _ini .

The first switch T1 and the second switch T2 are turned off in response to the first scan signal Scan1 and the second scan signal Scan2 input at the off level.

In response to the third scan signal Scan3 input at the on level, the third switch T3 is turned on. The third switch T3 is turned on by the third scan signal Scan3 input at the on level to input the initialization voltage V _ini to the second node.

The initialization voltage V _ini is input to the gate of the driving TFT DT connected to the second node n2, and a current path is formed between the drain and the source of the driving TFT DT. As a result, the voltage of the source electrode of the driving TFT DT connected to the third node n3 gradually increases, and the voltage of “Vini-Vth” is applied, so that Vth can be sensed. Here, the “Vini-Vth” voltage input to the source electrode of the driving TFT DT is a voltage lower than the voltage for driving the OLED, and the OLED is not driven.

FIG. 6A shows an equivalent circuit of a pixel corresponding to the second sensing period (Sensing) t3, and FIG. 6B shows a period corresponding to the second sensing period (Sensing) t3 and a gate of the driving TFT (DT) -It is a graph showing the voltage between sources.

6A and 6B, in the second sensing period (Sensing) t3, the first scan signal Scan1, the second scan signal Scan2, and the third scan signal Scan3 are all input at an off level. . The driving set signal Vset is input as a black voltage VBLACK.

The first switch T1, the second switch T2, and the third switch T3 in response to the first scan signal Scan1, the second scan signal Scan2, and the third scan signal Scan3 input at an off level ) Are all off.

Since the second node n2 is floating by the turn-off of the third scan signal Scan3, the potential of the second node n2 rises to “Vini+x”. Here, "x" is a value that compensates Vth of the driving TFT (DT) by using the floating time. The voltage of "Vini-Vth+x" is applied to the source electrode of the driving TFT DT connected to the third node n3. The "Vini-Vth+x" voltage is lower than the voltage for driving the OLED, and the OLED is not driven.

Fig. 7A shows an equivalent circuit of a pixel corresponding to the data writing period (Writing) t4, and Fig. 7B is a gate-source of the driving TFT (DT) and the period corresponding to the data writing period (Triting) t4 It is a graph showing the voltage of the liver. The data writing period t4 is a period for inputting the image data voltage Data to the gate of the driving TFT DT.

7A and 7B, during the data writing period (Writing) t4, the first scan signal Scan1 is input at an on level, and the second scan signal Scan2 and the third scan signal Scan3 are turned off. Level is entered. The driving set signal Vset is input as a black voltage V _BLACK . The driving set signal Vset is set to a voltage level for writing black data to the gate electrode of the driving TFT DT in a period other than the initialization period.

The first switch T1 is turned on in response to the first scan signal Scan1 input at the on level. The second switch T2 and the third switch T3 are turned off in response to the second scan signal Scan2 and the third scan signal Scan3 input at the off level.

The first switch T1 is turned on by the first scan signal Scan1 input at the on level to connect the data line 210 and the second node n2 to which the image data voltage Data for image display is supplied. do. Accordingly, the image data voltage Data is written to the gate electrode of the driving TFT DT through the second node n2.

The voltage of “Vini-Vth+x+α” sensed in the previous sensing period is applied to the third node n3 to which the source electrode of the driving TFT DT is connected. "α" is a value that varies depending on the mobility characteristics of the driving TFT (DT), and the image data voltage (Data) is applied to the gate electrode of the driving TFT (DT) without fixing the source node to a DC voltage. As input, the voltage of the source electrode is increased by the high potential driving voltage (EVDD). Since the “Vini-Vth+x+α” voltage applied to the third node n3 is a voltage lower than the voltage for driving the OLED, the OLED is not driven in the data writing period t4.

FIG. 8A shows an equivalent circuit of a pixel corresponding to an emission period (t5), and FIG. 8B shows a period corresponding to the emission period (t5) and the gate-source of the driving TFT (DT) It is a graph showing the voltage of the liver.

8A and 8B, in the emission period E5, the first scan signal Scan1, the second scan signal Scan2, and the third scan signal Scan3 are all input at an off level.

The first switch T1, the second switch T2, and the third switch T3 in response to the first scan signal Scan1, the second scan signal Scan2, and the third scan signal Scan3 input at an off level ) Are all off.

In the emission period (t5), the capacitor Cst is charged with the image data voltage Data compensated by the threshold voltage Vth of the driving element DT, and when the OLED emits light, the gate-source of the driving TFT (DT) Maintain the voltage across. The driving TFT DT emits the OLED by adjusting the driving current applied to the OLED according to the voltage between the gate and the source. The voltage of the gate electrode Vg of the driving TFT DT is “Data-{Vini-Vth+x+α}+VOLED”, and the voltage of the source electrode Vs can be expressed as “VOLED”.

9A shows an equivalent circuit of a pixel corresponding to the black voltage writing period (Black) t6, and FIG. 9B is a gate corresponding to the black voltage writing period (Black) t6 and the gate of the driving TFT (DT) -It is a graph showing the voltage between sources.

9A and 9B, in the black voltage writing period Black (t6), the first scan signal Scan1 and the second scan signal Scan2 are input at an off level, and the third scan signal Scan3 is It is entered on-level. The driving set signal Vset is input as a black voltage V _Black . The black voltage V _Black may be set to a voltage level capable of turning off the driving TFT DT, that is, a voltage level smaller than the threshold voltage Vth of the driving TFT DT, for example, a voltage of about 0.5V. .

The first switch T1 and the second switch T2 are turned off in response to the first scan signal Scan1 and the second scan signal Scan2 input at the off level.

In response to the third scan signal Scan3 input at the on level, the third switch T3 is turned on. The third switch T3 is turned on by the third scan signal Scan3 input at the on level to input the black voltage V _Black to the second node.

A black voltage V _Black is input to the gate of the driving TFT DT connected to the second node n2, and the driving TFT DT is turned off. The black voltage V _Black is input to the gate of the driving TFT DT, and the voltage at the source terminal becomes Vg-Vth. As the driving TFT DT is turned off, the current path to the OLED is cut off, so that the emission of the OLED is stopped.

As described above, when the driving set signal Vset is input as the black voltage V _Black , the emission period of the OLED, that is, the emission period (Emission) can be adjusted.

As described above, the present invention allows the gate electrode of the driving TFT to be initialized or black data to be input by using the driving setting signal Vset input to the gate electrode of the driving TFT. Adjusting the input time of the black data can control the emission time to control the emission duty. As a result, since the duty driving is possible even without the light emitting TFT, the design area required when applying the light emitting TFT can be saved and the life of the display device can be extended by removing the stress of the substrate due to the signal applied for driving the light emitting TFT.

Through the above description, those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical idea of the present specification. Therefore, the technical scope of the present specification is not limited to the contents described in the detailed description of the specification, but should be determined by the scope of the claims.

10: display panel 11: timing controller
12: data driver 13: gate driver

Claims (10)

A data voltage line to which the data voltage is supplied;
A reference voltage line to which a reference voltage is supplied;
A driving element for supplying current to the light emitting element, including a first electrode connected to a first node, a gate connected to a second node, and a second electrode connected to a third node connected to a light emitting element;
A first switch connecting the second node and the data voltage line in response to a first scan signal;
A second switch connecting the third node and the reference voltage line in response to a second scan signal; And
A third controlling the input of a drive setting signal having a first level voltage for initializing the drive element to the second node and a second level voltage for writing black data to the drive element in response to a third scan signal switch;
An electroluminescent display device comprising a. According to claim 1,
An electroluminescent display device further comprising a capacitor connected to one end of the second node and the other end of the third node. According to claim 1,
And a gate driver for generating the first scan signal, the second scan signal and the third scan signal and supplying the scan signal to the corresponding scan line, and generating the drive setting signal and outputting the drive setting signal to the drive line to which the third switch is connected. Electroluminescent display device. According to claim 3,
The third switch,
A gate electrode receiving the third scan signal;
A first electrode receiving the driving setting signal; And
An electroluminescent display device comprising a second electrode connected to the second node. According to claim 1,
The driving element,
An electroluminescent display device that blocks current supplied to the light emitting device when a drive setting signal having the second level voltage is input to the gate connected to the second node. According to claim 2,
1 frame period,
An initialization period for initializing a voltage between gate sources of the driving element;
A sensing period for sensing the threshold voltage of the driving element in the capacitor;
A data writing period for writing the data voltage to the gate of the driving element;
A light emitting period in which the sensed threshold voltage and the data voltage are reflected in the gate source potential of the driving element to supply current to the light emitting element; And
A black voltage writing period in which the black voltage is written to the gate of the driving element to turn off the driving element;
An electroluminescent display device comprising a. The method of claim 6,
In the data writing period, the first scan signal is input at an on level,
In the initialization period, the second scan signal is input at an on level,
An electroluminescent display device in which the third scan signal is input at an on level during the initialization period, the sensing period, and the black voltage writing period. The method of claim 6,
The driving setting signal is input to the first level voltage in the initialization period and the sensing period, and the electroluminescence display device is input to the second level voltage in the data writing period, the light emitting period and the black voltage writing period. The method of claim 8,
The first level voltage is set to a voltage level higher than the reference voltage and lower than the turn-on voltage of the light emitting element,
The second level voltage is set to a voltage level smaller than the threshold voltage of the light emitting device. A data voltage line to which a data voltage is supplied, a reference voltage line to which a reference voltage is supplied, a scan line to which a scan signal is supplied, and a driving panel to which a drive setting signal is supplied are provided with a display panel in which a plurality of pixels are connected,
Among the pixels, each pixel arranged in the n (n is a natural number) pixel row,
A light emitting device having a cathode electrode connected to an input terminal of a low potential driving voltage and an anode electrode connected to a third node;
A driving TFT including a drain electrode connected to a first node to which a high potential driving voltage is input, a gate electrode dedicated to a second node, and a drain electrode connected to the third node to control the driving current applied to the light emitting device. ;
A first switch connected between the second node and the data voltage line;
A second switch connected between the third node and the reference voltage line;
A capacitor having one end connected to the first node and the other end connected to the second node; And
A third switch connected to the second node to control the input of a drive setting signal having a first level voltage for initializing the drive element and a second level voltage for writing black data to the drive element;
An electroluminescent display device comprising a.

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