KR102380766B1 - Electroluminescent Display Device And Driving Method Of The Same - Google Patents

Abstract

An electroluminescent display device according to an embodiment of the present invention includes: a display panel provided with a plurality of horizontal display lines, each of which includes a plurality of pixels; a panel driving circuit for charging the data voltage to the pixels; a sensing unit configured to sense a pixel current flowing through the pixels in units of horizontal display lines according to the data voltage charged to the pixels and output sensed data; and a timing controller that calculates a charging rate of the data voltage based on the sensed data and adjusts one horizontal charging period for each horizontal display line according to the charging rate of the data voltage.

Description

Electroluminescent Display Device And Driving Method Of The Same

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

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, the active matrix type organic light emitting display device includes an organic light emitting diode (hereinafter referred to as "OLED"), which is a representative electroluminescent diode that emits light by itself, and has a response speed It has the advantages of fast speed, luminous efficiency, luminance and viewing angle.

OLED, which is a self-luminous device, includes an anode electrode and a cathode electrode, and an organic compound layer formed therebetween. The organic light emitting display device arranges pixels each including an OLED and a driving TFT (Thin Film Transistor) in a matrix form, and controls the luminance of an image implemented in the pixels by the size of the data voltage. The driving TFT controls the driving current flowing through the OLED according to the voltage applied between its gate electrode and the source electrode (hereinafter, referred to as “gate-source voltage”). The amount of light emitted and the luminance of the OLED are determined according to the driving current.

In the electroluminescent display, the data voltage charging characteristic of pixels is greatly affected by the RC delay of the data voltage. When the screen size of the electroluminescent display device increases and the resolution increases, the resistance and capacitance of the display panel increase, thereby increasing the RC delay of the data voltage supplied through the data line. In the large-screen electroluminescent display, the data voltage charging rate of pixels positioned in a portion having a large RC delay is relatively small. The data voltage output from the source drive IC (Integrated Circuit) is supplied to the pixel through the data line as the target voltage, but the voltage actually charged does not reach the target voltage within one horizontal charging period due to the RC delay.

One horizontal charging period is a time allocated for charging of pixels arranged in one horizontal display line, and is determined according to the vertical resolution of the display panel and one frame period. When a display panel having UHD resolution (3840*2160) is driven at a frame frequency of 120 Hz, one horizontal charging period is approximately 3.8 μs (8.33 ms/2160).

In the conventional electroluminescent display device, since one horizontal charging period is set to be the same at all positions of the display panel, it is not possible to solve the difference in the charging rate of the data voltage due to the RC delay.

Accordingly, it is an object of the present invention to provide an electroluminescent display device and a driving method thereof that can improve a data voltage charging rate variation between pixels.

In order to achieve the above object, an electroluminescent display device according to an embodiment of the present invention includes a display panel provided with a plurality of horizontal display lines, each horizontal display line including a plurality of pixels; a panel driving circuit for charging the data voltage to the pixels; a sensing unit configured to sense a pixel current flowing through the pixels in units of horizontal display lines according to the data voltage charged to the pixels and output sensed data; and a timing controller that calculates a charging rate of the data voltage based on the sensed data and adjusts one horizontal charging period for each horizontal display line according to the charging rate of the data voltage.

Further, according to an embodiment of the present invention, there is provided a method of driving an electroluminescent display device including a plurality of horizontal display lines and a plurality of pixels in each horizontal display line, the method comprising: charging the pixels with a data voltage; outputting sensed data by sensing a pixel current flowing through the pixels in units of horizontal display lines according to the data voltage charged in the pixels; and calculating a charging rate of the data voltage based on the sensed data, and adjusting the one horizontal charging period for each horizontal display line according to the charging rate of the data voltage.

As described above, the present invention generates timing control signals for controlling the operation timing of the panel driving circuit with reference to preset weights for each position based on the RC delay, thereby controlling one horizontal charging period in units of horizontal display lines. It is possible to improve the data voltage charge rate deviation between pixels.

Furthermore, the present invention calculates the charging rate of the data voltage in units of the horizontal display line based on the sensed data according to the data voltage and updates the weight for each position in the compensation table, thereby providing one horizontal charging period for each horizontal display line according to the load characteristics of the panel. It can be adaptively adjusted to change. Accordingly, according to the present invention, it is possible to more effectively improve the data voltage charge rate deviation between pixels by actively responding to changes in the load characteristics of the panel.

1 and 2 are diagrams illustrating an electroluminescent display device according to an embodiment of the present invention.
3 is a diagram illustrating an example of a pixel array provided in a display panel.
4 is a diagram illustrating an exemplary configuration of a pixel.
5 and 6 are diagrams illustrating an example of a sensing unit connected to pixels.
7 is a diagram illustrating an example of a weight curve for each position according to an RC delay preset in a compensation table.
FIG. 8 is a view showing one horizontal charging period for each position of the display panel according to the weight curve for each position of FIG. 7 .
9 is a diagram illustrating an example of timing control signals for determining one horizontal charging period for each position of FIG. 8 .
10 is a diagram illustrating a method of driving an electroluminescent display device according to an embodiment of the present invention.
11A and 11B are diagrams for explaining a sensing method for measuring a pixel current according to a data voltage.
12 is a diagram for explaining another sensing method for measuring a pixel current according to a data voltage.
13 is a diagram illustrating an example in which one horizontal charging period is varied in units of a horizontal display line according to a change in sensed data.

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. However, the present invention is not limited to the embodiments disclosed below, but will be embodied in various different forms, and only these 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 fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are illustrative and the present invention is not limited to the illustrated matters. Like reference numerals refer to 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 gist of the present invention, the detailed description thereof will be omitted. When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, cases including the plural are included unless otherwise explicitly stated.

In interpreting the components, it is construed 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 of two parts is described as 'on', 'on', 'on', 'next to', etc., 'right' Alternatively, one or more other parts may be positioned between two parts unless 'directly' is used.

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

Like reference numerals refer to substantially identical elements throughout.

Features of various embodiments of the present invention may be partially or wholly combined or combined with each other, technically various interlocking and driving are possible, and each embodiment may be implemented independently of each other or may be implemented together in a related relationship. there is.

In the present invention, the pixel circuit and the gate driver formed on the substrate of the display panel may be implemented as TFTs having an n-type or p-type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) structure. A TFT 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 TFT, carriers start flowing from the source. The drain is an electrode through which carriers exit the TFT. That is, the flow of carriers in the MOSFET flows from the source to the drain. In the case of an n-type TFT (NMOS), the source voltage is lower than the drain voltage so that electrons can flow from the source to the drain because carriers are electrons. In an 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 the case of a p-type TFT (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-type TFT, since holes flow from the source to the drain, the current flows 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 may be changed according to the applied voltage.

Hereinafter, the gate-on voltage is the voltage of the gate signal at which the TFT can be turned on. The gate off voltage is a voltage at which the TFT can be turned off. In NMOS, the gate-on voltage is the gate high voltage, and the gate-off voltage is the gate low voltage. In a PMOS, a gate-on voltage is a gate-low voltage, and a gate-off voltage is a gate-high voltage.

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. However, it should be noted that 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 to 9 are views illustrating an electroluminescent display device according to an embodiment of the present invention.

1 to 9 , the electroluminescent display device of the present invention includes a display panel 10 , a drive integrated circuit (IC) 20 , a timing controller 30 , and a host system.

A screen that reproduces an input image in the display panel 10 includes a plurality of pixels P connected to signal lines. Each of the pixels P may be any one of a red (R) pixel, a green (G) pixel, a blue (B) pixel, and a white (W) pixel for color implementation. Each of the pixels P may be implemented with various pixel circuits.

The signal lines may include data lines 140 for supplying an analog data voltage Vdata to the pixels P and gate lines 160 for supplying a gate signal to the pixels P. The signal wirings may further include sensing lines 150 used to sense the filling rate characteristic of the pixels P.

The pixels P of the display panel 10 are arranged in a matrix form to constitute a pixel array. Each pixel P may be connected to any one of the data lines 140 , to any one of the sensing lines 150 , and to any one of the gate lines 160 . Each pixel P may be configured to receive a high potential power voltage and a low potential power voltage from the power generator.

The pixel array includes a plurality of horizontal display lines L1 to L4 as shown in FIG. 3 . In each of the horizontal display lines L1 , L2 , L3 , and L4 , horizontally adjacent pixels P may be connected to the same gate line 160 . In each of the horizontal display lines L1, L2, L3, and L4, horizontally adjacent pixels P are respectively connected to different data lines 140, and M (M is a positive integer greater than or equal to 2) in units of M (M is a positive integer greater than or equal to 2). by being connected to different sensing lines 150 , the aperture ratio of the display panel 10 may be increased.

Each of the pixels P constituting the pixel array may include an OLED, a driving TFT (DT), a storage capacitor (Cst), a first switch TFT (ST1), and a second switch TFT (ST2) as shown in FIG. 4 . can The pixel configuration of FIG. 4 is only an example, and the technical spirit of the present invention is not limited to the pixel structure. The data voltage Vdata of FIG. 4 may be an image data voltage or a sensing data voltage.

The OLED is a light emitting device that emits light according to the pixel current input from the driving TFT DT, that is, the source-drain current Ids. The OLED includes an anode electrode, a cathode electrode, and an organic compound layer positioned between the anode electrode and the cathode electrode. The anode electrode is connected to the first node N1 which is the gate electrode of the driving TFT DT. The cathode electrode is connected to the input terminal of the low potential driving voltage VSS. The brightness of the image displayed on the pixel P is determined according to the amount of light emitted by the OLED.

The driving TFT DT is a driving element that controls the pixel current input to the OLED according to the gate-source voltage Vgs. The driving TFT DT includes a gate electrode connected to the first node N1 , a drain electrode connected to the input terminal of the high potential driving voltage VDD, and a source electrode connected to the second node N2 .

The storage capacitor Cst is connected between the first node N1 and the second node N2 . The storage capacitor Cst maintains the gate-source voltage Vgs of the driving TFT DT for a predetermined time.

The first switch TFT ST1 applies the data voltage Vdata on the data line 140 to the first node N1 in response to the gate signal SCAN. The first switch TFT ST1 includes a gate electrode connected to the gate line 160 , a drain electrode connected to the data line 140 , and a source electrode connected to the first node N1 .

The second switch TFT ST2 turns on/off the current flow between the second node N2 and the sensing line 150 in response to the gate signal SCAN. The second switch TFT ST2 includes a gate electrode connected to the gate line 160 , a drain electrode connected to the sensing line 150 , and a source electrode connected to the second node N2 . When the second switch TFT ST2 is turned on, the second node N2 and the sensing unit 22 are electrically connected.

The pixel array is connected to the gate driver 15 through gate lines 160 , to the data driver 23 through data lines 140 , and the sensing unit 22 through sensing lines 150 . is connected to

The gate driver 15 and the data driver 23 constitute a panel driving circuit. The panel driving circuit charges the data voltage Vdata to the pixels P during one horizontal charging period. To this end, the panel driving circuit sequentially supplies gate signals to each of the horizontal display lines L1 , L2 , L3 and L4 through the gate lines 160 , and through the data lines 140 , each horizontal display line ( The data voltage Vdata is sequentially supplied to L1, L2, L3, and L4.

The gate driver 15 generates a gate signal and supplies it to the gate lines 160 . The gate driver 15 may generate the gate signal differently when writing the image data V-DATA to the display panel 10 and when sensing the filling rate characteristic of the pixels P. The gate driver 15 may be embedded in the display panel 10 according to a gate driver in panel (GIP) method as shown in FIG. 2 .

The data driver 23 may be built in the drive IC 20 . The data driver 23 includes a digital-to-analog converter (DAC) to generate a data voltage Vdata, and supplies the data voltage Vdata to the data lines 140 .

The data voltage Vdata may include an image data voltage and a sensing data voltage. The image data voltage corresponds to the image data V-DATA and is a voltage capable of turning on the driving TFT of the pixel P. The voltage level of the image data voltage varies according to the gradation value of the image data V-DATA. The image data voltage is sequentially written to the horizontal display lines L1 to L4 through the data lines 140 during real-time driving. The OLED included in the pixels P is emitted by the pixel current according to the image data voltage to display an image. The sensing data voltage is for sensing the charging rate characteristic of the pixels P and is a specific voltage capable of turning on the driving TFT of the pixel P.

The data voltage for sensing is a voltage independent of image display and is preset to a specific level. The sensing data voltage is applied to the horizontal display lines L1 to L4 through the data lines 140 within the power-on period before the real-time driving or within the power-off period after the real-time driving. are written sequentially in The pixel current according to the data voltage for sensing is not applied to the OLED included in the pixels P but is applied to the sensing unit 22 .

The drive IC 20 further includes a sensing unit 22 . The sensing unit 22 senses the pixel current flowing in the pixels P of each of the horizontal display lines L1 to L4 through the sensing lines 150 in the power-on period or the power-off period in units of the horizontal display line. Outputs sensing data (S-DATA). In this case, the sensing unit 22 senses the total pixel current of the pixels P positioned in one horizontal display line.

Meanwhile, the sensing unit 22 may further sense the electrical characteristics of the pixels P using a power-on period, a power-off period, or a vertical blank period during real-time driving. The electrical characteristics of the pixels P may include an operating point voltage of an OLED included in the pixels P, a threshold voltage of the driving TFT, electron mobility of the driving TFT, and the like. The sensing unit 22 senses the electrical characteristics of the pixels P in units of pixels. The image data V-DATA is not written during the vertical blank period. The vertical blank period is located between vertical active periods in which the image data V-DATA is written.

The sensing unit 22 may be implemented as a voltage sensing type sensing unit or a current sensing type sensing unit.

The voltage sensing type sensing unit includes a sample and hold circuit (SH), first and second switches (SW1, SW2), and an analog-to-digital converter (ADC) as shown in FIG. 5, and includes a pixel current ( Ids) can be sensed. When the first switch SW1 is turned on, the initialization voltage Vpre is applied to the source electrode of the driving TFT DT. When the second switch SW2 is turned on, the pixel current Ids of the driving TFT charged in the sensing line 150 is applied to the sample and hold circuit SH. The analog-to-digital converter ADC converts the sensing voltage sampled by the sample and hold circuit SH into a digital signal and outputs sensing data S-DATA.

The current sensing type sensing unit further includes a current integrator at the front end of the sample and hold circuit SH as shown in FIG. 6 to directly sense the pixel current Ids of the driving TFT flowing through the sensing line 150 . The current integrator generates a sensing voltage by integrating the pixel current Ids of the driving TFT introduced through the sensing line 150 . The current integrator is an amplifier including an inverting input terminal (-) receiving the pixel current of the driving TFT (DT) from the sensing line 150, a non-inverting input terminal (+) receiving an initialization voltage (Vpre), and an output terminal ( AMP), an integrating capacitor Cfb connected between an inverting input terminal (-) and an output terminal of the amplifier AMP, and a first switch SW1 connected to both ends of the integrating capacitor Cfb. The current integrator is connected to an analog-to-digital converter (ADC) through a sample and hold circuit (SH). The sample and hold circuit SH samples the voltage output from the amplifier AMP and supplies it to the analog-to-digital converter ADC. The analog-to-digital converter ADC converts the sensing voltage sampled by the sample and hold circuit SH into a digital signal and outputs sensing data S-DATA.

The timing controller 30 generates timing control signals for controlling the operation timing of the panel driving circuit with reference to a weight for each position preset based on the RC delay in order to improve the data voltage charging rate deviation between the pixels P. , one horizontal charging period 1HC may be set differently for each position of the display panel 10 . Here, one horizontal charging period 1HC is a time allotted for charging the pixels arranged in one horizontal display line, and is determined according to the vertical resolution of the display panel and one frame period.

The timing controller 30 includes a compensation unit 32 , a compensation table 34 , and a control signal generator 36 .

In the compensation table 34, a weight for each position according to the RC delay is preset as shown in FIGS. 7 and 8 . The RC delay increases as the distance from the drive IC 20 on the display panel 10 increases. The RC delay value according to the location can be known in advance through a plurality of measurements before product shipment, and thus can be easily used to set the weight for each location. The weight for each position is preset to the minimum value X1 in the first area BL1 of the display panel 10 , and has a minimum value proportional to the RC delay in the second area BL2 where the RC delay is greater than the first area BL1 . It may be preset to increase between (X1) and an intermediate value (X2). In addition, the weight for each position may be preset to increase between the intermediate value X2 and the maximum value X3 in proportion to the RC delay in the third region BL3 in which the RC delay is greater than the second region BL2.

As an example, when the reference horizontal charging period determined according to the vertical resolution of the display panel 10 and one frame period is “Hr”, the minimum value X1 may be set to 095*Hr, and the maximum value X3 may be set to 1.3*Hr, and the intermediate value X2 may be set to any value between 095*Hr and 1.3*Hr.

The control signal generating unit 36 generates timing control signals according to the weights for each position set in the compensation table 34 to control the operation timing of the panel driving circuit, so as to The charging period (1HC) can be set differently. For example, one horizontal charging period 1HC corresponding to the horizontal display line La of the first region BL1 becomes “H1” by the timing control signals, and the horizontal display line Lb of the second region BL2 becomes “H1”. One horizontal charging period 1HC corresponding to 'H2' may be "H2", and one horizontal charging period 1HC corresponding to the horizontal display line Lc of the third area BL3 may be "H3". Here, "H2" is longer than "H1" and "H3" is longer than "H2" so that the filling factor deviation according to the RC delay is improved. Through this, the variation in the charge rate of the data voltage Vdata due to the RC delay may be alleviated.

The timing control signals are the gate shift clock GSC synchronized with the gate signal SCAN applied to the pixels P as shown in FIGS. 2 and 9 and the source output enable that determines the output timing of the data voltage Vdata. It may include a signal SOE. The gate shift clock GSC may be supplied to the gate driver 15 after being boosted to a gate on/off voltage level by the level shifter 31 . The level shifter 31 may be mounted on a source printed circuit board (S-PCB) together with the timing controller 30 .

The width of the low period of the source output enable signal SOE and the pulse width of the gate shift clock GSC are determined according to the weights for each position set in the compensation table 34 . One horizontal charging period in each horizontal display line is determined by the width of the low period of the source output enable signal SOE and the pulse width of the gate shift clock GSC. Therefore, if the width of the low period of the source output enable signal SOE and the pulse width of the gate shift clock GSC are changed according to the weights for each position, one horizontal charging period in each horizontal display line may be changed accordingly. can

For example, in synchronization with the driving timing of the horizontal display line La, the source output enable signal SOE is generated to have the width LP1 of the first row period, and the gate shift clock GSC has the first pulse width ( PW1), one horizontal charging period 1HC corresponding to the horizontal display line La becomes “H1”. In addition, in synchronization with the driving timing of the horizontal display line Lb, the source output enable signal SOE is generated to have the width LP2 of the second row period, and the gate shift clock GSC has the second pulse width PW2 , one horizontal charging period 1HC corresponding to the horizontal display line Lb becomes “H2”. Also, in synchronization with the driving timing of the horizontal display line Lc, the source output enable signal SOE is generated to have the width LP3 of the third row period, and the gate shift clock GSC has the third pulse width PW3 , one horizontal charging period 1HC corresponding to the horizontal display line Lc becomes “H3”.

Here, “LP1” and “PW1” are substantially identical to “H1”, “LP2” and “PW2” are substantially identical to “H2”, and “LP3” and “PW3” are substantially identical to “H3” can be the same.

The compensator 32 may receive the image data V-DATA from the host system 40 and supply it to the data driver 23 . The compensator 32 compensates the image data V-DATA based on the sensing result of the electrical characteristics of the pixels P input from the sensing unit 22 and supplies it to the data driving unit 23 , so that the pixel It is also possible to compensate for the electrical characteristic deviation between the (P).

On the other hand, the RC delay value according to the position is not fixed to the value obtained when the weight for each position is set in the initial state, but changes according to the panel temperature, the driving time, and the like, the use environment. Therefore, if the weights for each location are not updated in consideration of the load characteristics of the panel according to the usage environment, the filling rate deviation cannot be accurately compensated.

Accordingly, the present invention calculates the charging rate of the data voltage Vdata in units of horizontal display lines based on the sensed data S-DATA according to the data voltage Vdata, and then updates the weights for each position in the compensation table 34 by updating the weight. , one horizontal charging period (1HC) for each horizontal display line can be adaptively adjusted according to a change in the load characteristics of the panel. Accordingly, according to the present invention, it is possible to effectively improve the data voltage charge rate deviation between the pixels P by actively responding to the change in the load characteristics of the panel. This will be described in detail with reference to FIGS. 10 to 13 .

10 to 12 are diagrams illustrating a method of driving an electroluminescent display device according to an embodiment of the present invention.

Referring to FIG. 10 , in the present invention, a data voltage Vdata is charged to the pixels P using a panel driving circuit, and a pixel current according to a charging rate of the data voltage Vdata is sampled in units of a horizontal display line and sensed. Data (S-DATA) is output (S1). To this end, the present invention may utilize the double sampling method illustrated in FIGS. 11A and 11B or the single sampling method illustrated in FIG. 12 . According to the single sampling method of FIG. 12 , there is an advantage in that the time required for sensing is short.

Referring to FIG. 10 , in the present invention, the charging rate of the data voltage Vdata is calculated for each horizontal display line based on the sensed data S-DATA ( S2 ). According to the double sampling method of FIGS. 11A and 11B , the charging rate of the data voltage Vdata is calculated based on the difference between the sensed data obtained in the second sampling process. According to the double sampling method of FIGS. 11A and 11B , since the load deviation of the sensing line is offset by the correlated double sampling operation, the accuracy of sensing and compensation is improved. According to the single sampling method of FIG. 12 , a charging rate of the data voltage Vdata is calculated based on a difference between the sensed data obtained in the first sampling process and a preset reference value. According to the single sampling method of FIG. 12 , the time required for sensing is reduced.

Referring to FIG. 10 , in the present invention, one horizontal charging period 1HC is adjusted for each horizontal display line according to the charging rate of the data voltage Vdata (S3). To this end, according to the present invention, the weight of each position of the compensation table 34 may be updated according to the charging rate of the data voltage Vdata for each horizontal display line. Further, according to the present invention, by controlling the operation timing of the panel driving circuit by adjusting the timing control signals SOE and GSC according to the updated weights for each position, one horizontal charging period (1HC) for each horizontal display line of the display panel 10 ( 1HC ) ) can be adjusted.

The double sampling method will be further described with reference to FIGS. 11A and 11B .

The double sampling method is a method to find out the change in the load characteristic of each horizontal display line through two sensing operations. In the first sensing operation, the sensing data voltage (Vdata) is charged to the pixels (P) for a sufficiently long time (Hx) for the charging rate to be 100%, that is, longer than the reference horizontal charging period (Hr). and sensing the first pixel current according to the sensing data voltage Vdata in units of horizontal display lines to obtain first sensing data. In the second sensing operation, the sensing data voltage Vdata is charged to the pixels P for a period of time Hy close to the reference horizontal charging period Hr, and the second pixel current according to the sensing data voltage Vdata is is sensed in units of horizontal display lines to obtain second sensed data.

Specifically, referring to FIGS. 11A and 11B , the panel driving circuit applies the first sensing gate signal SCAN_A to the on level during the first charging time Hx during the first sensing operation to apply the first sensing gate signal SCAN_A to the pixels of each horizontal display line. The sensing data voltage Vdata is charged to the P. Then, during the second sensing operation, the panel driving circuit applies the second sensing gate signal SCAN_B to the on level during the second charging time Hy, and applies the sensing data voltage ( Vdata) is charged. Here, the first charging time (Hx) is set longer than the reference horizontal charging period (Hr) determined according to the vertical resolution of the display panel and one frame period, and the second charging time (Hy) is the reference horizontal charging period (Hr) can be set to In addition, the first sensing gate signal SCAN_A and the second sensing gate signal SCAN_B are signals arbitrarily applied for a sensing operation, and are equally applied to all horizontal display lines irrespective of weights for each position. The sensing gate signals SCAN_A and SCAN_B are distinguished from the gate signal SCAN of FIG. 9 , that is, an image gate signal whose pulse width is changed according to a weight for each position to determine one horizontal charging period.

11A and 11B , the sensing unit 22 turns on the first switch SW1 within the first charging time Hx during the first sensing operation to turn on the second node N2 of the pixels P After initializing , the first pixel current Ipix1 flowing through the pixels P of each horizontal display line by turning on the second switch SW2 immediately after the end of the first charging time Hx in units of the horizontal display line The sampling is performed to output the first sensed data. Then, during the second sensing operation, the sensing unit 22 initializes the second node N2 of the pixels P by turning on the first switch SW1 within the second charging period Hy, and then the second Immediately after the end of the charging period Hy, the second switch SW2 is turned on to sense the second pixel current Ipix2 flowing through the pixels P of each horizontal display line in units of the horizontal display line to receive second sensed data print out

11A and 11B , the timing controller 30 calculates a charging rate of the data voltage Vdata in units of horizontal display lines based on a difference between the first sensed data and the second sensed data.

11A and 11B , the timing controller 30 calculates the charging rate of the data voltage Vdata for each horizontal display line, and updates the weight for each location according to the charging rate of the data voltage Vdata for each horizontal display line. In other words, the timing controller 30 corrects the minimum value X1, the intermediate value X2, and the maximum value X3 of the compensation table 34 according to the charging rate of the data voltage Vdata for each horizontal display line, The weight for each position can be modified for each horizontal display line. Here, the intermediate value X2 may be set to a plurality of different values. Then, the timing controller 30 changes the timing control signals for controlling the operation timing of the panel driving circuit according to the updated weight for each position.

In this way, the timing controller 30 controls the horizontal display lines of the reduced change width and the increased change width of one horizontal charging period (1HC) compared to the reference horizontal charging period (Hr) determined according to the vertical resolution of the display panel 10 and one frame period. One horizontal charging period 1HC corresponding to each horizontal display line may be adjusted by correcting the minimum value X1 , the median value X2 , and the maximum value X3 so that the total sum becomes “0”. Since one frame period does not change and is fixed, the total sum of the reduced change width and the increased change width of one horizontal charging period 1HC compared to the reference horizontal charging period Hr becomes “0”.

A single sampling method will be further described with reference to FIG. 12 as follows.

The single sampling method is a method to find out the change in the load characteristic of each horizontal display line through one sensing operation. During the sensing operation, the sensing data voltage Vdata is charged to the pixels P for a period close to the reference horizontal charging period Hr, and the pixel current according to the sensing data voltage Vdata is sensed in units of horizontal display lines. to obtain sensing data.

Specifically, referring to FIG. 12 , the panel driving circuit applies the sensing gate signal SCAN_C to the on level during the reference horizontal charging period Hr during the sensing operation to the pixels P of each horizontal display line for sensing. The data voltage Vdata is charged. Here, the sensing gate signal SCAN_C is a signal arbitrarily applied for a sensing operation, and is equally applied to all horizontal display lines irrespective of weights for each position. The sensing gate signal SCAN_C is distinguished from the gate signal SCAN of FIG. 9 , that is, the image gate signal for determining one horizontal charging period by changing a pulse width according to a weight for each position.

Referring to FIG. 12 , the sensing unit 22 initializes the second node N2 of the pixels P by turning on the first switch SW1 within the reference horizontal charging period Hr during the sensing operation, Immediately after the end of the reference horizontal charging period Hr, the second switch SW2 is turned on to sample the pixel current Ipix flowing through the pixels P of each horizontal display line in units of the horizontal display line to output sensing data do.

Referring to FIG. 12 , the timing controller 30 calculates a charging rate of the data voltage Vdata in units of horizontal display lines based on a difference between the sensed data and a preset reference value.

Referring to FIG. 12 , the timing controller 30 calculates the charging rate of the data voltage Vdata for each horizontal display line and updates the weight for each location according to the charging rate of the data voltage Vdata for each horizontal display line. In other words, the timing controller 30 corrects the minimum value X1, the intermediate value X2, and the maximum value X3 of the compensation table 34 according to the charging rate of the data voltage Vdata for each horizontal display line, The weight for each position can be modified for each horizontal display line. Here, the intermediate value X2 may be set to a plurality of different values. Then, the timing controller 30 changes the timing control signals for controlling the operation timing of the panel driving circuit according to the updated weight for each position.

In this way, the timing controller 30 controls the horizontal display lines of the reduced change width and the increased change width of one horizontal charging period (1HC) compared to the reference horizontal charging period (Hr) determined according to the vertical resolution of the display panel 10 and one frame period. One horizontal charging period 1HC corresponding to each horizontal display line may be adjusted by correcting the minimum value X1 , the median value X2 , and the maximum value X3 so that the total sum becomes “0”. Since one frame period does not change and is fixed, the total sum of the reduced change width and the increased change width of one horizontal charging period 1HC compared to the reference horizontal charging period Hr becomes “0”.

13 is a diagram illustrating an example in which one horizontal charging period is varied in units of a horizontal display line according to a change in sensed data.

Referring to FIG. 13 , the present invention senses a pixel current according to a data voltage Vdata, and calculates a charging rate of the data voltage Vdata for each horizontal display line based on the sensed data. The change in the sensed data before and after sensing means that the load characteristics of the display panel are changed according to the usage environment. Accordingly, when the charging rate of the data voltage Vdata for each horizontal display line is calculated, the load characteristic change for each horizontal display line can be found out.

The present invention adjusts one horizontal charging period for each horizontal display line by updating and correcting weights for each position in the compensation table according to a change in load characteristics for each horizontal display line.

For example, according to a change in the charging rate of the data voltage Vdata for each horizontal display line, the weight for each position of the horizontal display line La may be maintained as g1 (g1<1), and the weight for each position of the horizontal display line Lb may be set to g2( may be reduced from g2=1) to g2' (g2'<1), and the weight for each position of the horizontal display line Lc may be increased from g3(g3>1) to g3'(g3'>1), The weight for each position of the display line Ld may be increased from g4 (g4>1) to g4' (g4'>1).

Accordingly, one horizontal charging period 1HC of the horizontal display line La remains the same before and after sensing, one horizontal charging period 1HC of the horizontal display line Lb is further reduced after sensing than before sensing, and the horizontal display lines Lc One horizontal charging period 1HC of each of , Ld may be increased more after sensing than before sensing.

As described above, the present invention generates timing control signals for controlling the operation timing of the panel driving circuit with reference to preset weights for each position based on the RC delay, thereby controlling one horizontal charging period in units of horizontal display lines. It is possible to improve the data voltage charge rate deviation between pixels.

Furthermore, the present invention calculates the charging rate of the data voltage in units of the horizontal display line based on the sensed data according to the data voltage and updates the weight for each position in the compensation table, thereby providing one horizontal charging period for each horizontal display line according to the load characteristics of the panel. It can be adaptively adjusted to change. Accordingly, according to the present invention, it is possible to more effectively improve the data voltage charge rate deviation between pixels by actively responding to changes in the load characteristics of the panel.

Those skilled in the art from the above description will be able to see that various changes and modifications are possible 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.

10: display panel 15: gate driver
22: sensing unit 23: data driving unit
30: timing controller 32: compensation unit
34: compensation table 36: control signal generator

Claims (15)

a display panel including a plurality of horizontal display lines, each of which includes a plurality of pixels;
a panel driving circuit for charging the data voltage to the pixels;
a sensing unit configured to sense a pixel current flowing through the pixels according to the data voltage charged to the pixels in units of horizontal display lines and output sensed data; and
and a timing controller calculating a charging rate of the data voltage based on the sensed data and adjusting one horizontal charging period for each horizontal display line according to the charging rate of the data voltage. The method of claim 1,
The timing controller is
Timing for updating the weight for each position according to the charging rate of the data voltage calculated based on the sensed data to adjust the one horizontal charging period for each horizontal display line, and controlling the operation timing of the panel driving circuit An electroluminescent display for changing control signals. 3. The method of claim 2,
The timing controller is
a compensation table in which the weight for each position according to the RC delay is set in advance;
a compensator for calculating a charging rate of the data voltage for each horizontal display line based on the sensed data and updating the weight for each position according to a charging rate of the data voltage for each horizontal display line; and
and a control signal generator configured to change the timing control signals according to the updated weight for each position. 4. The method of claim 3,
The weight for each location is
In the first area of the display panel, it is preset to a minimum value,
In a second region in which the RC delay is larger than the first region, the RC delay is preset to increase between the minimum value and the intermediate value in proportion to the RC delay,
An electroluminescence display preset to increase between the intermediate value and the maximum value in proportion to the RC delay in a third region in which the RC delay is greater than the second region. 5. The method of claim 4,
The compensator corrects the minimum value, the intermediate value, and the maximum value according to a charging rate of the data voltage for each horizontal display line. 6. The method of claim 5,
The compensation unit,
In the horizontal display lines, the minimum value and the maximum value are calculated so that the total sum of the reduced change width and the increased change width between one horizontal charger is “0” compared to the reference horizontal charging period determined according to the vertical resolution of the display panel and one frame period. By modification, an electroluminescent display device that adjusts one horizontal charging period corresponding to each horizontal display line. 3. The method of claim 2,
The timing control signals are
An electroluminescence display comprising: a gate shift clock synchronized with a gate signal applied to the pixels; and a source output enable signal for determining an output timing of the data voltage. The method of claim 1,
The panel driving circuit comprises:
After charging the data voltage to the pixels of each horizontal display line during a first charging time, charging the data voltage to the pixels of each of the horizontal display lines during a second charging time;
The first charging time is set longer than a reference horizontal charging period determined according to a vertical resolution of the display panel and one frame period, and the second charging time is set as the reference horizontal charging period. 9. The method of claim 8,
The sensing unit,
sampling a first pixel current flowing through the pixels of each horizontal display line during the first charging time in units of horizontal display lines and outputting first sensing data;
The electroluminescent display device outputs second sensing data by sampling a second pixel current flowing through pixels of each horizontal display line in units of horizontal display lines during the second charging time. 10. The method of claim 9,
The timing controller is
An electroluminescent display device for calculating a charging rate of the data voltage in units of the horizontal display line based on a difference between the first sensed data and the second sensed data. The method of claim 1,
The panel driving circuit comprises:
An electroluminescent display device for charging the data voltage to pixels of each horizontal display line during a reference horizontal charging period determined according to the vertical resolution of the display panel and one frame period. 12. The method of claim 11,
The sensing unit,
The electroluminescent display device outputs first sensing data by sampling pixel currents flowing through the pixels of each horizontal display line in units of horizontal display lines during the reference horizontal charging period. 13. The method of claim 12,
The timing controller is
An electroluminescent display device for calculating a charging rate of the data voltage in units of the horizontal display line based on a difference between the first sensed data and a preset reference value. In the driving method of an electroluminescent display device including a plurality of horizontal display lines and a plurality of pixels in each horizontal display line, the method comprising:
charging a data voltage to the pixels;
outputting sensed data by sensing a pixel current flowing through the pixels in units of horizontal display lines according to the data voltage charged in the pixels; and
and calculating a charging rate of the data voltage based on the sensed data and adjusting one horizontal charging period for each horizontal display line according to the charging rate of the data voltage. 15. The method of claim 14,
The step of adjusting the one horizontal charging period for each horizontal display line comprises:
updating a weight for each location according to a charging rate of the data voltage calculated based on the sensed data; and
and changing timing control signals for charging the data voltage.

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