KR102433958B1 - Electroluminescence display and driving method thereof - Google Patents

Abstract

The present invention relates to an electroluminescent display device and a driving method thereof, in which data lines and gate lines cross, a plurality of pixels are disposed, and a reference voltage is supplied to the pixels through a sensing line. , a data driver supplying a data voltage of pixel data to the data lines, and a gate driver supplying a gate signal to the gate lines. A pulse smaller than a pulse width of the gate signal is added to at least one of the black grayscale data voltage and the reference voltage.

Description

ELECTROLUMINESCENCE DISPLAY AND DRIVING METHOD THEREOF

The present invention relates to an electroluminescent display having a driving element for driving pixels.

The electroluminescent display is roughly divided into an inorganic light emitting display and an organic light emitting display according to the material of the light emitting layer. An active matrix type organic light emitting diode display includes an organic light emitting diode (hereinafter, referred to as "OLED") that emits light by itself, and has a fast response speed and high luminous efficiency, luminance, and viewing angle. There are advantages.

Pixels of the organic light emitting diode display include an OLED and a driving element that drives the OLED by supplying a current to the OLED according to a gate-source voltage. An OLED of an organic light emitting display device includes an anode and a cathode, and an organic compound layer formed between the electrodes. 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 current flows in the OLED, holes passing through the hole transport layer (HTL) and electrons passing through the electron transport layer (ETL) move to the light emitting layer (EML) to form excitons, and as a result, the light emitting layer (EML) generates visible light. .

The driving device may be implemented as a transistor having a metal oxide semiconductor field effect transistor (MOSFET) structure. Although the driving device should have uniform electrical characteristics among all pixels, there may be differences between pixels due to process variations and device characteristics variations and may change with the lapse of display driving time. In order to compensate for the deviation in the electrical characteristics of the driving element, an internal compensation method and an external compensation method may be applied to the electroluminescent display device. The internal compensation method samples the gate-source voltage (Vgs) of the driving device that varies according to the electrical characteristics of the driving device, and compensates the data voltage by the gate-source voltage. The external compensation method compensates for variations in electrical characteristics of the driving device between pixels by sensing a voltage of a pixel that changes according to the electrical characteristics of the driving device, and modulating input image data in an external circuit based on the sensed voltage.

In an organic light emitting diode display, when black gray data is written into a pixel and the pixel is driven in black gray for a long time, the gate-source voltage Vgs of the driving element is applied as a DC voltage having a DC voltage and a negative voltage. . In this case, a hole trap may be generated in a transistor used as a driving element, and an afterimage may be induced on the screen.

Accordingly, the present invention provides an electroluminescent display device capable of preventing an afterimage by AC driving Vgs of a driving element and a driving method thereof.

The electroluminescent display device of the present invention includes a display panel in which data lines and gate lines are crossed, a plurality of pixels are disposed, a reference voltage is supplied to the pixels through a sensing line, and a data voltage of pixel data is applied to the data lines. and a data driver for supplying a data to the , and a gate driver for supplying a gate signal to the gate line.

A pulse smaller than a pulse width of the gate signal is added to at least one of the black grayscale data voltage and the reference voltage.

The driving method of the electroluminescent display includes supplying a data voltage of pixel data to the data line to supply the data voltage to a gate of a driving element of a pixel, and supplying the reference voltage to the sensing line to control the driving element. supplying the reference voltage to a source, and supplying a gate signal to the gate line.

According to the present invention, the Vgs of each driving element of the pixels is generated as an AC voltage by adding a pulse to at least one of the data voltage and the reference voltage of the black grayscale. As a result, according to the present invention, an afterimage can be prevented or alleviated by compensating for a negative gate bias of the driving device.

1 is a block diagram showing an electroluminescent display device according to an embodiment of the present invention.
2 and 3 are circuit diagrams illustrating a pixel circuit and a sensing path.
4 is a waveform diagram showing a gate signal and a data voltage of a black grayscale.
5 is a diagram illustrating an example in which an additional pulse is applied to a data voltage of a black grayscale.
6 to 8 are waveform diagrams illustrating examples in which an additional pulse is applied to a reference voltage.
9 is a view showing an additional pulse generating apparatus according to the first embodiment of the present invention.
FIG. 10 is a circuit diagram showing the pulse generator shown in FIG. 9 .
11 is a view showing an additional pulse generating apparatus according to a second embodiment of the present invention.
12 is a circuit diagram illustrating a switching circuit in the drive IC shown in FIG. 11 .

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. The present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only the embodiments allow the disclosure of the present invention to be complete, and those of ordinary skill in the art to which the present invention pertains It is provided to fully understand the scope of the invention, and the invention is only defined by the scope of the claims.

Since the shape, size, ratio, angle, number, etc. disclosed in the drawings for explaining the embodiment of the present invention are exemplary, the present invention is not limited to the matters shown in the drawings. Like reference numerals refer to substantially like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

When "includes", "includes", "having", "consisting of", etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, it may be interpreted as the plural unless otherwise explicitly stated.

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

In the case of a description of the positional relationship, for example, when the positional relationship between the two components is described as 'on One or more other elements may be interposed between those elements in which 'directly' or 'directly' are not used.

The first, second, etc. may be used to distinguish the components, but the functions or structures of these components are not limited to the ordinal number or component name attached to the front of the component.

The following embodiments can be partially or wholly combined or combined with each other, and technically various interlocking and driving are possible. Each of the embodiments may be implemented independently of each other or may be implemented together in a related relationship.

In the electroluminescent display device of the present invention, the pixel circuit includes a driving element and a switch element. The driving device and the switch device may be implemented by at least one of an n-channel transistor (NMOS) and a p-channel transistor (PMOS). On the display panel, the transistor may be implemented as a thin film transistor (TFT). The transistor may be implemented as an oxide transistor having an oxide semiconductor pattern or an LTPS transistor having a low temperature poly-silicon (LTPS) semiconductor pattern. A transistor is a three-electrode device including a gate, a source, and a drain. 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 carriers exit the transistor. In a transistor, the flow of carriers flows from source to drain. In the case of an n-channel transistor (NMOS), since carriers are electrons, the source voltage has a voltage lower than the drain voltage so that electrons can flow from the source to the drain. In an n-channel transistor (NMOS), the direction of current flows from the drain to the source. In the case of a p-channel transistor (PMOS), since carriers are holes, the source voltage is higher than the drain voltage so that holes can flow from the source to the drain. In a p-channel transistor (PMOS), 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 an applied voltage. Accordingly, the invention is not limited by 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.

A gate signal of a transistor used as a switch element 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 turned-off in response to the gate-off voltage. In the case of an n-channel transistor (NMOS), 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 the p-channel transistor PMOS, the gate-on voltage may be the gate low voltage Vgl, and the gate-off voltage may be the gate high voltage Vgh.

Although the field emission display device of the present invention is mainly described with respect to an organic light emitting diode display to which an external compensation circuit is applied, the present invention is not limited thereto.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, the electroluminescent display will be mainly described with respect to the organic light emitting display including the organic light emitting material. The technical spirit of the present invention is not limited to an organic light emitting display device, and may be applied to an inorganic light emitting display device including an inorganic light emitting material.

1 is a block diagram showing an electroluminescent display device according to an embodiment of the present invention. 2 and 3 are circuit diagrams illustrating a pixel circuit and a sensing path.

1 to 3 , an electroluminescent display device according to an embodiment of the present invention includes a display panel 100 and a display panel driving circuit.

The screen of the display panel 100 includes an active area AA for displaying an input image. A pixel array is disposed in the active area AA. The pixel array includes a plurality of data lines 102 , a plurality of gate lines 104 intersecting the data lines 102 , and pixels arranged in a matrix form.

Each of the pixels may be divided into a red sub-pixel, a green sub-pixel, and a blue sub-pixel to implement color. Each of the pixels may further include a white sub-pixel. Each of the sub-pixels 101 includes a pixel circuit as shown in FIGS. 2 and 3 .

Touch sensors may be disposed on the display panel 100 . The touch input may be sensed using separate touch sensors or may be sensed through pixels. The touch sensors are in-cell type touch sensors disposed on the screen of the display panel 100 or embedded in a pixel array as an on-cell type or an add-on type. can be implemented as

The display panel driving circuits 110 , 112 , and 120 include a data driving unit 110 and a gate driving unit 120 . A demultiplexer 112 disposed between the data driver 110 and the data lines 102 may be disposed.

The display panel driving circuits 110 , 112 , and 120 write input image data into pixels of the display panel 100 under the control of a timing controller (TCON) 130 during the display driving period and input the data on the screen. display the image. The display panel driving circuit may further include a touch sensor driver for driving the touch sensors. The touch sensor driver is omitted from FIG. 1 . In a mobile device or a wearable device, the display panel driving circuit, the timing controller 130 , and the power circuit may be integrated into one integrated circuit.

As shown in FIG. 2 , the data driving unit 110 gamma-maizes digital data of an input image received from the timing controller 130 in every frame period using a digital-to-analog converter (hereinafter, referred to as DAC). The data voltage Vdata is output by converting it into a compensation voltage. The data voltage Vdata is applied to the pixels through the demultiplexer 112 and the data line 102 . The demultiplexer 112 is disposed between the data driver 110 and the data lines 102 using a plurality of switch elements to distribute the data voltage output from the data driver 110 to the data lines 102 . Since one channel of the data driver 110 is connected to a plurality of data lines by the demultiplexer 112 , the number of data lines 102 may be reduced.

The gate driver 120 may be implemented as a gate in panel (GIP) circuit that is directly formed on a bezel region of the display panel 100 together with a transistor array in the active region. The gate driver 120 outputs a gate signal to the gate lines 104 under the control of the timing controller 130 . The gate driver 120 may sequentially supply the gate signals to the gate lines 104 by shifting the gate signals using a shift register. The gate signal may be divided into a scan signal SCAN and a sensing signal SENSE, as shown in FIGS. 4 and 5 . The gate driver 120 supplies the scan signal SCAN to the first gate line 1041 and the sensing signal SENSE to the second gate line 1042 under the control of the timing controller 130 . The gate driver 120 sequentially supplies the scan signal SCAN to the pixel lines by shifting the scan signal SCAN and the sensing signal SENSE as shown in FIGS. 4 and 5 . . The pixel line includes pixels arranged along the gate line direction and connected to the same gate line. Pixels of one pixel line share a gate line to which a scan signal is applied, and are simultaneously addressed according to a scan signal from the gate line to receive a data voltage of pixel data.

The scan signal SCAN and the sensing signal SENSE swing between the gate high voltage Vgh and the gate low voltage Vgl. The scan signal SCAN selects pixels to which the data voltage is applied in synchronization with the data voltage. The sensing signal SENSE is synchronized with the scan signal SCAN. The sensing signal SECSE selects pixels in which electrical characteristics of the driving elements DT formed in the pixels are sensed in the external compensation method. Electrical characteristics of the driving device include mobility (μ) and a threshold voltage (Vth).

In the external compensation method, the threshold voltage Vth or mobility μ of the driving element may be sensed by connecting the pixel circuit to the sensing line 103 using the sensing signal SENSE. The sensing method is divided into before product shipment and after product shipment. After the threshold voltage of the driving element DT is sensed in each of the sub-pixels through a sensing path connected to the pixels before product shipment, the threshold voltage deviation in all sub-pixels is compensated based on the sensing result. In addition, the mobility of the driving element DT is sensed in each of the sub-pixels to compensate for the mobility deviation.

After product shipment, the sensing method may be performed in a power ON sequence, a vertical blank period (VB), and a power OFF sequence. In the power-off sequence, the display panel driving circuit and the sensing path are further driven for a preset delay time after receiving the power-off signal to sense the threshold voltage Vth of the driving device in each of the sub-pixels.

The timing controller 130 receives pixel data (digital data) of an input image and a timing signal synchronized therewith from a host system (not shown). The timing controller 130 transmits the pixel data of the input image to the data driver 110 . The timing controller 130 generates a control signal for controlling the operation timing of the display panel driving circuits 110 , 112 , and 120 based on the timing signal received from the host system.

The voltage level of the gate timing control signal output from the timing controller 130 may be converted into a gate-on voltage and a gate-off voltage through a level shifter (not shown) and supplied to the gate driver 120 . The gate timing control signal includes a start pulse, a shift clock, etc. input to the shift register of the gate driver 120 . The level shifter converts a low level voltage of the gate timing control signal into a gate low voltage Vgl, and converts a high level voltage of the gate timing control signal into a gate high voltage Vg. .

The timing controller 130 may generate additional pulse data synchronized with pixel data of a black gray scale by analyzing the input image.

The host system may be any one of a television (Television) system, a set-top box, a navigation system, a personal computer (PC), a home theater system, a mobile device, and a wearable device.

The sensing path may include a sensing line 103, an analog-to-digital converter (hereinafter referred to as “ADC”), and a sensing switch circuit as shown in FIG. 2 . The sensing switch circuit may include first and second switch elements M1 and M2. The sensing path may sense an electrical characteristic of the driving device by sensing the source voltage Vs of the driving device DT. The first switch element M1 initializes the source voltage of the driving element DT to the reference voltage Vref by supplying a predetermined reference voltage Vref to the sensing line 103 . The second switch element M2 is turned on after the first switch element M1 is turned off to supply the source voltage of the driving element DT to the ADC. The ADC converts the analog sensing voltage into digital sensing data and transmits it to the compensator 131 . The source voltage of the driving element DT may represent a threshold voltage or mobility of the driving element DT according to a sensing method. A method of sensing the threshold voltage of the driving element DT through the sensing path or a method of sensing the mobility of the driving element DT through the sensing path may use a known sensing method. The ADC may be integrated in an integrated circuit (IC) of the data driver 110 together with the DAC.

The compensation unit 131 stores compensation values for compensating for the threshold voltage Vth and the mobility μ of the driving element in each of the sub-pixels. The compensator 131 selects a preset compensation value according to the digital sensing data received through the ADC and compensates the pixel data by adding or multiplying the compensation value to the pixel data (digital data) of the input image. The compensated pixel data is transmitted to the data driver 110 , converted into a data voltage Vdata by the DAC of the data driver 110 , and supplied to the data line 102 . The driving element DT of the pixel circuit is driven by the data voltage Vdata supplied through the data line 102 to generate a current. A current flowing through the driving element DT to the OLED, which is the light emitting element, is determined according to the gate-source voltage Vgs of the driving element DT. The compensator 131 may be implemented as an arithmetic circuit in the timing controller 130 .

2 and 3 , the pixel circuit includes an OLED, a driving device DT connected to the OLED, a plurality of switch devices S1 and S2 , and a plurality of capacitors Cst. The driving element DT and the switch elements S1 and S2 are illustrated as n-channel transistors in FIG. 3 , but are not limited thereto.

OLED is a light emitting device including an organic compound layer formed between an anode and a cathode. The organic compound layer may include, but is not limited to, a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL). The anode of the OLED is connected to the driving element DT through the second node n2, and the cathode of the OLED is connected to the VSS electrode to which the low potential power voltage VSS is applied.

The driving device DT drives the OLED by controlling the current of the OLED according to the gate-source voltage Vgs. The driving element DT is an OLED through a gate connected to the first node n1 , a first electrode (or drain) connected to the VDD line 105 to which the pixel driving voltage VDD is supplied, and a second node n2 . a second electrode (or source) connected to the anode of The first capacitor Cst is connected between the gate and the source of the driving device DT through the first and second nodes n1 and n2 .

The first switch element S1 is turned on according to the gate-on voltage Vgh of the scan signal SCAN, and connects the data line 102 to the first node n1 to connect the data voltage Vdata. ) is supplied to the gate of the driving element DT. The first switch element S1 has a gate connected to the first gate line 1041 to which the scan signal SCAN is applied, a first electrode connected to the data line 102 , and a second electrode connected to the first node n1 . includes

The second switch element S2 is turned on according to the gate-on voltage Vgh of the sensing signal SENSE, and supplies the sensing line 103 to the second node n2 to supply the reference voltage Vref. ) is supplied to the second node n2. The voltage difference between the reference voltage Vref and the low-potential power supply voltage VSS is lower than the threshold voltage of the OLED. Therefore, when the reference voltage Vref is applied to the anode of the OLED, the OLED does not emit light because no current flows through the OLED. The second switch element S2 includes a gate connected to the second gate line 1042 to which the sensing signal SENSE is applied, a first electrode connected to the sensing line 103 to which the reference voltage Vref is applied, and a second node. and a second electrode connected to (n2).

The voltage applied to the pixel may be VDD = 24V, VSS = 0V, Vref = 2V, Vdata = 1V, Vgh = 25V, and Vgl = -7V, but is not limited thereto.

As shown in FIGS. 4 and 5 , when the black data voltage Data(Black) is applied to the gate of the driving element DT for a long time to the pixel, the driving element DT is deteriorated due to DC gate bias stress. An afterimage may be generated on the screen. In order to improve the afterimage problem, in the present invention, Vgs of the driving element DT is driven by alternating current (AC). To this end, according to the present invention, an additional pulse 51 is added to the data voltage Data(Black) of the black grayscale as shown in FIG. 5 or added to the reference voltage Vref as shown in FIGS. 6 to 8 . A pulse 61 may be added. In the present invention, the additional pulse 51 may be added to the data voltage Data(Black) of the black grayscale, and the additional pulse 61 may be added to the reference voltage Vref.

Therefore, according to the present invention, an afterimage can be prevented by compensating for a negative gate bias by generating Vgs of the driving device as an AC voltage.

The additional pulse 51 added to the data voltage Data(Black) of the black gray scale is applied to the gate of the driving device DT through the data line 102 to generate the Vgs of the driving device DT as an AC voltage. . The additional pulse 61 added to the reference voltage Vref is supplied to the sensing line 103 and applied to the source of the driving element DT to generate Vgs of the driving element DT as an AC voltage. In order not to increase the luminance of the black grayscale, the voltage of the additional pulses 51 and 61 may be set so that the anode voltage of the OLED, which rises when the driving element DT is sensed, does not exceed the turn-on voltage of the OLED. . The anode voltage of the OLED is equal to the source voltage Vs of the driving element DT. It is preferable that the Vgs AC driving of the driving device be completed before the gate signals SCAN and SENSE are inverted to the gate-off voltage VGL. This is because the data voltage of the pixel data must be charged in the pixel before the gate signals SCAN and SENSE are inverted to the gate-off voltage VGL.

4 is a waveform diagram showing the gate signals SCAN and SENSE and the data voltage Data(Black) of the black grayscale. FIG. 5 is a diagram illustrating an example in which a compensation data voltage is added to a data voltage Data(Black) of a black gray scale in order to AC drive Vgs of the driving element DT. 4 and 5, “SCAN(N-1)” and “SCAN(N-1)” are gate signals applied to pixels of an N-1th pixel line (N is a natural number). “SCAN(N)” and “SCAN(N)” are gate signals applied to pixels of the N-th pixel line addressed following the N-1th pixel line. 4 and 5 , the data voltage Data(Black) of the black grayscale is the data voltage of the lowest grayscale in which the OLED does not emit light. In 8-bit data, the data of the black gradation is 00000000 ₂ .

In order to generate Vgs of the driving element DT as an AC voltage, as shown in FIG. 5 , the additional pulse 51 added to the data voltage Data(Black) of the black gray scale is applied to the gate signals SCAN and SENSE. It can be generated with a pulse width smaller than a pulse. The additional pulse 51 may be added to the data voltage Data(Black) of the black grayscale when the gate signals SCAN and SENSE are maintained at the gate-on voltage Vgh. After a predetermined holding period elapses after the falling edge of the additional pulse 51 , the falling edges of the gate signals SCAN and SENSE are generated. The additional pulse 51 may be applied to the black grayscale data voltage Data(Black), and the additional pulse 61 may be applied to the reference voltage Vref.

6 to 8 are waveform diagrams illustrating examples in which an additional pulse is applied to a reference voltage.

Referring to FIG. 6 , an additional pulse 61 of a voltage lower than a reference voltage Vref is supplied to the sensing line 103 . The additional pulse 61 may be applied to the source of the driving element DT when the gate signals SCAN and SENSE are maintained at the gate-on voltage Vgh. The additional pulse 61 added to the reference voltage Vref causes a change in the source voltage Vs of the driving element DT so that Vgs of the driving element DT is generated as an AC voltage.

Referring to FIG. 7 , the additional pulse 61 may be added to the reference voltage Vref regardless of the pattern of the input image. The additional pulse 61 may be applied to the source of the driving element DT in the pulse period of the source output enable signal (SOE) in every horizontal period regardless of the gray level of the pixel data. A pulse of a source output enable signal (SOE) may be generated as a high logic voltage (High=H). In FIG. 7 , “Black” is a black gradation voltage, and “White” is a white gradation voltage. The data voltage of the white gradation is the data voltage of the highest gradation at which the OLED emits light with the highest luminance. In 8-bit data, the data of the height gray scale is 11111111 ₂ .

A pulse period of the source output enable signal SOE is a period between the N-1 th pixel data and the N th pixel data. A pulse period of the source output enable signal SOE usually corresponds to a horizontal blank interval. The data driver 110 may restore the source output enable signal SOE by decoding information of the source output enable signal SOE in the data packet received from the timing controller 130 . The data driver 110 outputs the data voltage Vdata of the pixel data in the low logic period (low=L) of the supported source output enable signal SOE. One horizontal period is the time at which data is written to the pixels of one pixel line.

The additional pulse voltage of the reference voltage Vref may affect the voltage of the pixel to change the data voltage charged in the pixel. To prevent this, the pulse timing of the gate signals SCAN and SENSE needs to be set to be different from the timing of the additional pulse 61 . In FIG. 7 , “Gate off” indicates the off timing of the gate signal, that is, a falling edge. The additional pulse 61 is generated when the gate-off voltage period of the gate signals SCAN and SENSE, that is, the voltage of the gate signals SCAN and SENSE is Vgl. The switch elements T1 and T2 of the pixel circuit are turned on according to the gate-on voltage Vgh of the gate signals SCAN and SENSE, while the gate-off voltage of the gate signals SCAN and SENSE is turned on. It is turned off according to Vgl).

Referring to FIG. 8 , the additional pulse 61 may be supplied to a pixel in which black grayscale pixel data is written based on the grayscale analysis result of the input image. On the other hand, the additional pulse 61 is not supplied to the pixel in which the pixel data of the white gradation is written. The additional pulse 61 may be applied to the source of the driving element DT in the horizontal blank period following the data voltage of the black grayscale.

9 is a view showing an additional pulse generating apparatus according to the first embodiment of the present invention. FIG. 10 is a circuit diagram showing the pulse generator shown in FIG. 9 .

9 and 10 , the additional pulse generator includes a timing controller 130 and a pulse generator 132 .

The timing controller 130 generates a pulse according to the additional pulse timing. The pulse generator 132 switches the high potential voltage VH and the low potential voltage VL according to a pulse from the timing controller 130 to output a reference voltage Vref of an AC voltage to which an additional pulse is added. The high potential voltage VH is a DC voltage generated at a voltage level of the reference voltage Vref. The low potential voltage VL is a DC voltage generated at the voltage level of the additional pulse 61 .

The pulse generator 132 may be implemented as an inverter circuit in which an n-channel transistor T1 and a p-channel transistor T2 are combined as shown in FIG. 10 . The pulse Vin output from the timing controller 130 is applied to the gates of the n-channel transistor T2 and the p-channel transistor T1 . The p-channel transistor T1 is turned on according to the voltage of the low logic section L of the pulse Vin to output the high potential voltage VH. The n-channel transistor T2 is turned on according to the high logic voltage of the pulse Vin to output the low potential voltage VH. In FIG. 10, “Vout” denotes a reference voltage of an AC voltage output from the inverter circuit. The reference voltage of the AC voltage is applied to the source of the driving element DT through the sensing line 103 .

11 is a view showing an additional pulse generating apparatus according to a second embodiment of the present invention. 12 is a circuit diagram illustrating a switching circuit in the drive IC 140 shown in FIG. 11 . The drive integrated circuit (IC) 140 includes a data driver 110 and sensing switch circuits M1 and M2.

11 and 12 , the additional pulse generator includes a timing controller 130 and a drive IC 140 .

The timing controller 130 generates a pulse according to the additional pulse timing. The drive IC 140 is supplied with the reference voltage Vref and the low potential voltage VL. The drive IC 140 switches the reference voltage Vref and the low potential voltage VL according to the pulse from the timing controller 130 to output the reference voltage Vref of the AC voltage to which the additional pulse is added.

As shown in FIG. 12 , the switch circuit of the drive IC 140 switches the reference voltage Vref and the low potential voltage VL according to the selection signal SEL from the timing controller 130 to obtain the reference voltage of the AC voltage. voltage can be output. The reference voltage of the AC voltage is applied to the source of the driving element DT through the sensing line 103 . In FIG. 12 , SAM is a sampling signal that controls the switch element M2 shown in FIG. 2 .

Those skilled in the art from the above description will be able to see that various changes and modifications can be made without departing from the technical spirit of the present invention. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

100: display panel 110: data driver
120: gate driver 130: timing controller
131: compensation unit 132: pulse generator
140: drive IC DT: driving element of the pixel circuit
S1, S2: switch element of pixel circuit SCAN, SENSE: gate signal
Cst: the capacitor in the pixel circuit

Claims (13)

a display panel in which data lines and gate lines cross, a plurality of pixels are disposed, and a reference voltage is supplied to the pixels through a sensing line;
a data driver supplying a data voltage of pixel data to the data lines; and
and a gate driver supplying a gate signal to the gate line;
a pulse smaller than the pulse width of the gate signal is added to at least one of the black grayscale data voltage and the reference voltage,
the pixels are
light emitting element; and
A driving device for driving the light emitting device,
An electroluminescent display device in which a gate-source voltage of the driving element is generated as an AC voltage by the pulse. The method of claim 1,
The pixels are
Further comprising a plurality of switch elements turned off according to the gate-off voltage of the gate signal,
An electroluminescent display device in which the pulse added to the reference voltage is generated in a gate-off voltage section between successive pulses of the gate signal. The method of claim 1,
The pulse applied to the reference voltage is supplied to the sensing line in every horizontal period irrespective of the gray level of the pixel data. 4. The method of claim 3,
The pulse applied to the reference voltage is supplied to a pixel in which black grayscale pixel data is written through the sensing line. 5. The method according to claim 3 or 4,
The pulse applied to the reference voltage is supplied to the sensing line in a gate-off voltage period between successive pulses of the gate signal. The method of claim 1,
Each of the pixels includes a plurality of sub-pixels having different colors,
Each of the sub-pixels is
the light emitting device;
the driving element;
a first switch element turned on according to a first gate signal to supply the data voltage to a gate of the driving element;
a capacitor for charging a gate-source voltage of the driving element; and
a second switch element turned on according to a second gate signal to connect the sensing line to the source of the driving element;
The pulse added to the black grayscale data voltage is applied to a gate of the driving element. The method of claim 1,
Each of the pixels includes a plurality of sub-pixels having different colors,
Each of the sub-pixels is
the light emitting device;
the driving element;
a first switch element turned on according to a first gate signal to supply the data voltage to a gate of the driving element;
a capacitor for charging a gate-source voltage of the driving element; and
a second switch element turned on according to a second gate signal to connect the sensing line to the source of the driving element;
An electroluminescent display device in which a pulse added to the reference voltage is applied to a source of the driving element. The method of claim 1,
Each of the pixels includes a plurality of sub-pixels having different colors,
Each of the sub-pixels is
the light emitting device;
the driving element;
a first switch element turned on according to a first gate signal to supply the data voltage to a gate of the driving element;
a capacitor for charging a gate-source voltage of the driving element; and
a second switch element turned on according to a second gate signal to connect the sensing line to the source of the driving element;
A pulse added to the data voltage of the black gray is applied to the gate of the driving device,
An electroluminescent display device in which a pulse added to the reference voltage is applied to a source of the driving element. In the driving method of an electroluminescent display including a display panel in which data lines and gate lines are crossed, a plurality of pixels are disposed, and a reference voltage is supplied to the pixels through a sensing line, the method comprising:
supplying a data voltage of pixel data to the data line to supply the data voltage to a gate of a driving element of a pixel;
supplying the reference voltage to a source of the driving element by supplying the reference voltage to the sensing line; and
supplying a gate signal to the gate line;
At least one of the black grayscale data voltage and the reference voltage includes a pulse smaller than a pulse width of the gate signal,
A method of driving an electroluminescence display in which a gate-source voltage of the driving element is generated as an AC voltage by the pulse. 10. The method of claim 9,
A pulse added to the data voltage of the black gray is applied to the gate of the driving device,
A method of driving an electroluminescent display device in which a pulse added to at least one of the reference voltages is applied to a source of the driving element. The method of claim 1,
The pixels are
Further comprising a plurality of switch elements turned on in response to the gate-on voltage of the gate signal,
An electroluminescent display device in which a pulse added to at least one of the black grayscale data voltage and the reference voltage is generated within a gate-on voltage section of the gate signal. a display panel in which data lines and gate lines cross, a plurality of pixels are disposed, and a reference voltage is supplied to the pixels through a sensing line;
a data driver supplying a data voltage of pixel data to the data lines; and
and a gate driver supplying a gate signal to the gate line;
A pulse smaller than the pulse width of the gate signal is added to the reference voltage,
the pixels are
light emitting element;
a driving element for driving the light emitting element; and
a plurality of switch elements turned on in response to the gate-on voltage of the gate signal and turned off according to the off voltage of the gate signal;
The electroluminescent display device in which the pulse added to the reference voltage is generated in a gate-off voltage period between successive pulses of the gate signal. a display panel in which data lines and gate lines cross, a plurality of pixels are disposed, and a reference voltage is supplied to the pixels through a sensing line;
a data driver supplying a data voltage of pixel data to the data lines; and
and a gate driver supplying a gate signal to the gate line;
A pulse smaller than the pulse width of the gate signal is added to the reference voltage,
the pixels are
light emitting element;
a driving element for driving the light emitting element; and
a plurality of switch elements turned on in response to the gate-on voltage of the gate signal and turned off according to the off voltage of the gate signal;
An electroluminescent display device in which a pulse added to the reference voltage is generated within a gate-on voltage section of the gate signal.

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