KR20150041484A - Organic light emitting display device - Google Patents

Abstract

The present invention is to provide an organic light emitting display device which can effectively control overcurrent flowing through a display panel. The organic light emitting display device according to the present invention comprises: a display panel composed of a plurality of pixels including an organic light emitting device emitting light by current corresponding to data voltage; and a panel driving unit predicting a panel current value flowing through the display panel by analyzing current horizontal line data of a current frame which is inputted per horizontal period, calculating a brightness gain value for the current horizontal period to control the predicted panel current value to be below an overcurrent limit value, and modulating the current horizontal line data in accordance with the calculated brightness gain value and displaying the modulated data in the display panel.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light-

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display capable of effectively controlling an overcurrent flowing in a display panel.

2. Description of the Related Art In recent years, the importance of flat panel display devices has been increasing with the development of multimedia. In response to this, various flat panel display devices such as a liquid crystal display, a plasma display, and an organic light emitting display have been put to practical use. Among such flat panel display devices, organic light emitting display devices are attracting attention as a next generation flat panel display device because they have a high response speed, low power consumption, and self-luminescence, so that there is no problem in viewing angle.

A general organic light emitting display device displays a predetermined image by applying a data voltage to each pixel and controlling a current flowing from the driving voltage line to the organic light emitting element according to a data current corresponding to the data voltage. To this end, each pixel includes an organic light emitting diode, a switching transistor, a driving transistor, and at least one capacitor.

The organic light emitting element emits light in proportion to the amount of current supplied from the driving transistor. The switching transistor is switched according to a scan signal to supply a data voltage supplied from the data line to the driving transistor. The driving transistor is switched according to a data voltage supplied from the switching transistor to generate a data current based on the data voltage and supplies the data current to the organic light emitting element. The capacitor holds the data voltage supplied to the driving transistor for one frame.

The conventional OLED display displays a predetermined image on a display panel according to a data addressing method of updating data of a current frame to data of a previous frame displayed on a display panel.

However, in the conventional OLED display device, as shown in Fig. 1, there is a problem that an overcurrent flows instantaneously on the display panel at the time when the images of the adjacent front and rear frames Fn-1 and Fn are switched.

1, the image of the (n-1) th frame Fn-1 is divided into black data to be displayed on the upper area of the display panel and white data to be displayed on the lower area of the display panel. Assuming that the image of the n-th frame Fn has white data to be displayed in the upper area of the display panel and black data to be displayed in the lower area of the display panel, The overcurrent flows to the display panel in a part of the horizontal period of the n-th frame Fn in which the white data of the first frame Fn-1 and the white data of the n-th frame Fn are simultaneously displayed on the display panel.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an organic light emitting display device capable of effectively controlling an overcurrent flowing in a display panel.

In addition to the technical aspects of the present invention, other features and advantages of the present invention will be described below, or may be apparent to those skilled in the art from the description and the description.

According to an aspect of the present invention, there is provided an organic light emitting diode display comprising: a display panel including a plurality of pixels including an organic light emitting diode emitting light by a current corresponding to a data voltage; And the current horizontal line data of the current frame input every horizontal period to predict the panel current value flowing in the display panel and to calculate a luminance gain value of the current horizontal period for controlling the predicted panel current value to be equal to or less than the overcurrent limit value And a panel driver for modulating the current horizontal line data according to the calculated luminance gain value and displaying the modulated current horizontal line data on a display panel.

According to the solution of the above problem, the present invention can accurately predict and effectively suppress the occurrence of an overcurrent momentarily flowing in the display panel by controlling the current flowing through the display panel in each horizontal period.

1 is a diagram for explaining an overcurrent flowing in a display panel according to a frame image in a general organic light emitting display device.
2 is a view for explaining an organic light emitting display according to an embodiment of the present invention.
FIG. 3 is a view for explaining a timing controller according to an embodiment of the present invention shown in FIG. 2. Referring to FIG.
4 is a graph showing currents flowing through a display panel according to a frame image in the present invention and a conventional organic light emitting diode display.

The meaning of the terms described herein should be understood as follows.

The word " first, "" second," and the like, used to distinguish one element from another, are to be understood to include plural representations unless the context clearly dictates otherwise. The scope of the right should not be limited by these terms.

It should be understood that the terms "comprises" or "having" does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It should be understood that the term "at least one" includes all possible combinations from one or more related items. For example, the meaning of "at least one of the first item, the second item and the third item" means not only the first item, the second item or the third item, but also the second item and the second item among the first item, Means any combination of items that can be presented from more than one.

Hereinafter, preferred embodiments of the organic light emitting display according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a view for explaining an organic light emitting display according to an embodiment of the present invention.

Referring to FIG. 2, the OLED display includes a display panel 100 and a panel driver 200.

The display panel 100 emits light of a predetermined voltage Vdata through the light emitted from each pixel P by the OLED of each pixel P according to the data voltage Vdata supplied from the panel driver 200. [ Color image is displayed. To this end, the display panel 100 is formed so as to intersect with each other, and n (where n is a natural number) data lines DL and m (where m is a natural number) gate lines GL defining n pixel regions, n A plurality of driving voltage lines PL1 formed in parallel to the data lines DL and connected to each pixel P and a cathode voltage line PL2 connected to each pixel P.

The n data lines DL and the m gate lines GL are formed to cross each other at regular intervals. Here, each of the m gate lines GL forms m horizontal lines of the display panel 100.

The plurality of driving voltage lines PL1 are formed adjacent to each of the n data lines DL and are supplied with a driving voltage ELVDD from a power supply unit (not shown). The cathode voltage line PL2 is supplied with a cathode voltage ELVSS having a low potential level or a ground (or ground) voltage level lower than the driving voltage ELVDD.

Each of the plurality of pixels P has a data current corresponding to a data voltage Vdata supplied from a connected data line DL in response to a gate signal GS supplied from a connected gate line GL. To emit a predetermined monochromatic light. Each of the plurality of pixels P may be formed of any one of red, green, blue, and white. Accordingly, a unit pixel for displaying one color image may be composed of adjacent red pixels, green pixels, and blue pixels, or may be composed of adjacent red pixels, green pixels, blue pixels, and white pixels. To this end, each of the plurality of pixels P includes an organic light emitting diode (OLED) and a pixel circuit (PC).

The organic light emitting diode OLED is connected between the pixel circuit PC and the cathode voltage line PL2 and emits a predetermined monochromatic light by emitting light in proportion to a data current supplied from the pixel circuit PC. The organic light emitting diode OLED includes an anode electrode (or a pixel electrode) connected to the pixel circuit PC, a cathode electrode (or a reflective electrode) connected to the cathode voltage line PL2, and an anode electrode And an organic layer formed between the cathode electrodes. Here, the organic layer may have a structure of a hole transporting layer / an organic light emitting layer / an electron transporting layer or a structure of a hole injecting layer / a hole transporting layer / an organic light emitting layer / an electron transporting layer / an electron injecting layer. Further, the organic layer may further include a functional layer for improving the luminous efficiency and / or lifetime of the organic light emitting layer.

The pixel circuit PC receives a data voltage Vdata supplied from the panel driver 200 to the data line DL in response to a gate signal GS supplied from the panel driver 200 to the gate line GL And controls the current flowing from the corresponding driving voltage line PL1 to the organic light emitting diode OLED. The pixel circuit PC includes a driving transistor (not shown) for controlling a current flowing from the driving voltage line PL1 to the organic light emitting diode OLED based on the data voltage Vdata, A storage capacitor (not shown) connected between the gate electrode and the source electrode of the driving transistor for maintaining the gate-source voltage of the driving transistor for one frame Not shown). The pixel circuit PC is not limited to two transistors and one capacitor. The pixel circuit PC may have an internal compensation structure for compensating the threshold voltage / mobility variation of the driving transistor within the pixel P, A compensation circuit corresponding to an external compensation structure for sensing a change in threshold voltage / mobility and compensating data from the outside of the display panel 100 through data correction.

The panel driver 200 calculates the panel current value flowing through the display panel 100 for each horizontal period based on the current horizontal line data Idata input in units of horizontal periods and outputs the calculated panel current value to the overcurrent limiting value And modulates the input data Idata according to the calculated current gain value and displays the modulated input data Idata on the display panel 100. [ That is, the panel driver 200 predicts the panel current value flowing through the display panel 100 for each current horizontal period based on the current horizontal line data Idata, and outputs the current horizontal line data Thereby effectively preventing the occurrence of an overcurrent momentarily flowing in the display panel 100, thereby preventing a problem caused by an overcurrent. The panel driver 200 includes a timing controller 210, a gate driver 220, and a data driver 230.

The timing controller 210 receives a timing synchronization signal TSS such as a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, and a main clock input from outside, that is, from a system body (not shown) or a graphic card (not shown) A gate control signal GCS for controlling the gate driver 220 and a data control signal DCS for controlling the data driver 230 are generated. The timing controller 210 analyzes the current horizontal line data Idata in response to the horizontal synchronizing signal of the input timing synchronizing signal TSS and the main clock and outputs the panel current value flowing through the display panel 100 Calculates a luminance gain value for controlling the calculated panel current value to be equal to or less than the overcurrent limit value, modulates the input data (Idata) according to the calculated luminance gain value to generate modulation data (Mdata) And supplies the generated data (Mdata) to the data driver 230 through a predetermined data interface method. Here, in the case where the unit pixel is composed of red, green, and blue pixels, the timing controller 210 according to an exemplary embodiment of the present invention may control the brightness of the unit pixel based on three-color input data of red, green, The gain value is calculated, and the three-color input data is modulated in accordance with the calculated luminance gain value. The timing controller 210 according to another embodiment may be configured such that when the unit pixel is composed of red, green, blue, and white pixels, the three-color input data of red, green, The pixel is converted into four-color input data of red, green, blue, and white, the luminance gain value is calculated based on the four-color input data, and the four-color input data is modulated in accordance with the calculated luminance gain value. In this case, the timing controller 210 may convert the three-color input data into the four-color input data according to the conversion method disclosed in Korean Patent Laid-Open Publication No. 10-2013-0060476 or No. 10-2013-0030598.

The gate driver 220 generates a gate signal GS for data addressing in response to a gate control signal GCS supplied from the timing controller 210 and sequentially supplies the gate signal GS to m gate lines GL. The gate driver 220 may be a shift register that sequentially outputs the gate signal GS according to the gate control signal GCS.

The data driver 230 receives the data control signal DCS supplied from the timing controller 210 and the modulation data Mdata corresponding to one horizontal line and outputs a plurality of different data Ds from the reference gamma voltage generator Of the reference gamma voltage. The data driver 230 samples the modulated data Mdata input in units of one horizontal line according to the data control signal DCS and outputs the sampled data based on the plurality of reference gamma voltages to an analog data voltage (Vdata) and supplies it to the data line DL of the corresponding pixel P.

The organic light emitting display according to an embodiment of the present invention predicts the panel current value flowing through the display panel 100 for each current horizontal period based on the current horizontal line data Idata, It is possible to accurately predict and suppress the occurrence of an overcurrent momentarily flowing in the display panel 100 by modulating the current horizontal line data Idata.

FIG. 3 is a view for explaining a timing controller according to an embodiment of the present invention shown in FIG. 2. Referring to FIG.

Referring to FIG. 3, the timing controller 210 according to the embodiment of the present invention includes a control signal generator 211 and an overcurrent controller 213.

The control signal generation unit 211 generates a control signal for controlling the gate driving unit 220 and the data driving unit 230 based on a timing synchronization signal TSS such as a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, And generates a gate control signal (GCS) and a data control signal (DCS) for controlling the driving timing, respectively.

The overcurrent controller 213 receives the panel current value I _F (Fn, k) flowing in the display panel 100 for each current horizontal period based on the current horizontal line data Idata (Fn, k) of the current frame Fn, k), and calculates the luminance gain value G _L (Fn, k) based on the predicted panel current value I _F (Fn, k), and calculates the luminance gain value G _L (Fn, k) by modulating the current horizontal line data Idata (Fn, k) in accordance with the current horizontal line data Idata (k, k). The overcurrent control unit 213 includes a line current calculation unit 213a, a storage unit 213b, a panel current calculation unit 213c, a gain calculation unit 213d, and a data modulation unit 213e. do.

The line current calculation unit 213a calculates the current horizontal line data Idata (F n, k (k)) consisting of input data to be displayed on each pixel P included in the current horizontal line of the display panel 100, ) To generate a current horizontal line current value I _H (Fn, k).

For example, the line current calculation unit 213a may calculate the current value of the current horizontal line data Idata (Fn, k) by summing the current values flowing through the pixels P included in the current horizontal line according to the gray- The line current value I _H (Fn, k) can be generated. In this case, the line current calculation unit 213a calculates the line current value of the pixel P by using a look-up table to which a current value flowing through the pixel P acquired through a preliminary experiment based on the gray- The line current value I _H (Fn, k) can be generated.

As another example, the line current calculation unit 213a sums and averages the gray level values of the current horizontal line data (Idata (Fn, k)) to calculate a current horizontal line current value I _H (Fn, k)). In this case, the line current calculation unit 213a calculates the line current value of the current horizontal line current (i, j) using a look-up table to which the line current value acquired through the preliminary experiment based on the average gray- Value (I _H (Fn, k)).

The storage unit 213b stores the current horizontal line current value I _H (Fn, k) output from the line current calculation unit 213a for each current horizontal period. The storage unit 213b stores the k-th to (m-1) th horizontal line current values generated in the previous frame Fn-1 by the line current calculation unit 213a and the The first to k-th horizontal line current values are stored. Here, the kth horizontal line current value of the current frame Fn is the current horizontal line current value of the current horizontal period of the current frame Fn.

The panel current calculation unit 213c calculates a panel current value I _H (Fn, k) from the current horizontal line current value I _H (Fn, k) output from the line current calculation unit 213a for each current horizontal period, The panel current value I _F (Fn, k) flowing through the display panel 100 is predicted by the current horizontal line data Idata (Fn, k) using the previous horizontal line current values, The panel current value I _F (Fn, k) is supplied to the gain calculator 213d and stored in the internal register. For example, the panel current calculation unit 213c calculates horizontal line data Idata (Fn, k) corresponding to the kth horizontal line Fn, k of the current frame Fn through the calculation process of Equation (1) (k)) is supplied to the display panel 100, the panel current value I _F (Fn, k) flowing through the display panel 100 can be calculated.

In Equation 1, I _F is the panel current, I _H is a horizontal line, current value, Fn is the current frame, Fn-1 is the previous frame, i is a horizontal line, k is the current horizontal line, k-1 is the current level J is the next horizontal line of the current horizontal line, and M is the total number of horizontal lines, respectively. _{And, I F (Fn, k-} 1) is a panel current calculation section panel current value of a previous horizontal period of the current frame stored in the internal register of _{(213c), I H (Fn} , k) is a line in the current horizontal period The current horizontal line current value of the current frame calculated by the current calculation unit 213a and I _H (Fn-1, k) are the current horizontal line current values of the previous frame stored in the storage unit 213b, respectively .

The panel current calculation unit 213c calculates the panel current value I _H (Fn, k) from the current horizontal line current value I _H (Fn, k) output from the line current calculation unit 213a, (Fn-1, k)) and the subtraction result (I _H (Fn, k) - I _H (Fn-1, k)) from the current horizontal line current value I _H by the panel current (I _F (Fn, k-1)), the addition operation (+) of the previous horizontal period of the current frame stored in the storage unit (213b), the adding operation result (I _F (Fn, k- 1) + {I _H (Fn, k) - I _H (Fn-1, k)}) of the current horizontal line data Idata (Fn, k) (I _F (Fn, k)).

On the other hand, when the current horizontal line data Idata (Fn, k) corresponding to the current horizontal line Fn, k of the current frame Fn is updated in the current horizontal line Fn, k by data addressing, The current variation I _H (Fn, k) - I (Fn, k) of the current horizontal line current value I _H (Fn, k) and the current horizontal line current value I _{H H} (Fn-1, k)). Accordingly, the panel current calculation unit 213c calculates the panel current value I _H (Fn, k) and the current horizontal line current value I _H (Fn-1) of the previous frame, k) of the previous horizontal period of the current frame to the panel current value I _F (Fn, k-1) of the previous horizontal period of the current frame by adding the current variation amount I _H (Fn, k) - I _H (Fn- It is possible to predict the panel current value I _F (Fn, k) of the current horizontal period flowing to the display panel 100 by the current horizontal line data Idata (Fn, k).

The panel current value of each horizontal line of the current frame predicted for each horizontal period by the panel current calculation unit 213c is stored in the internal register so that the panel current value of the previous horizontal period of the current frame Used as a value.

The gain calculator 213d calculates the gain of the panel current based on the panel current value I _F (Fn, k) of the current horizontal period outputted from the panel current calculator 213c and the set overcurrent limit value I _Lim The luminance gain value G _L (Fn, k) of the current horizontal period is generated. Specifically, the gain calculation unit 213d compares the panel current value I _F (Fn, k) of the current horizontal period generated in the panel current calculation unit 213c with the overcurrent limit value I _LiM The panel current value I _F (k) of the current horizontal period is determined through data modulation of the current horizontal line data Idata (Fn, k) if it is predicted that an overcurrent will occur in the corresponding horizontal period, (Fn, k)) is less than or equal to the overcurrent limit value (I _LiM ). For example, the gain calculator 213d may generate the current gain value G _C (Fn, k) of the current horizontal period through an operation of Equation (2).

In the above Equation 2, G _C is a current gain value, I _Lim is an overcurrent limiting value, I _F is a panel current value, I _H is a horizontal line current value, Fn is a current frame, Fn- Horizontal line, and k-1 represent the previous horizontal line of the current horizontal line, respectively. In Equation (2), the denominator represents the amount of line current flowing by the data of the current horizontal line according to the data addressing, and the numerator represents the maximum amount of current of the current horizontal line which is allowed to prevent the overcurrent from being generated.

The gain calculator 213d calculates the panel current value I _F (i) of the previous horizontal period of the current frame supplied from the internal register of the panel current calculator 213c at the overcurrent limit value I _LiM according to Equation (2) Fn, k-1)), and outputs the result of subtraction (I _LiM - I _F (Fn, k-1)) and the storage unit (now horizontal line current values in the previous frame supplied from the 213b) (I _H (Fn-1, k)), the addition operation (+), and the addition operation Results (I _LiM - Division operations to _{I F (Fn, k-1} ) + I H (Fn-1, k)) for the line current calculation section (213a) in the current horizontal line current value (I _H (Fn, k supplied from a)) ( /) So that the division result ((I _LiM - I _F is generated (Fn, k-1) + I H (Fn-1, k)) / I H (Fn, k)) for the current horizontal period, the current gain value (G _C (Fn, k) of a). The current gain value G _C (Fn, k) of the current horizontal period generated through the calculation of Equation (2) can be generated with a constant of 1 or less (G _C (Fn, k) 1).

The current gain value G _C (Fn, k) is a current control variable for controlling the current change amount generated when the data of the current horizontal line is updated to the maximum allowable current change amount. If the relationship between the current and the luminance of the display panel 100 based on the light emission characteristic of each pixel P is linear, the gain calculator 213d calculates the current gain value G _C (Fn, k) (G _L (Fn, k)) for controlling the luminance of the display panel 100 without the correction of the luminance gain G _L (Fn, k). On the other hand, when the relationship between the current and the luminance of the display panel 100 is nonlinear, the gain calculation unit 213d calculates a modeling function based on a nonlinear relationship between the current and the luminance, as shown in the following equation (3) (f) a current gain value by using the _{(G C (Fn, k)} ) to a luminance gain value is converted to _{(G L (Fn, k)} ). In this case, the gain calculating section (213d) is modeled current gain value based on a function _{(f) (G C (Fn} , k)) luminance gain value according to _{(G L (Fn, k)} ) gain look which is assigned Up table to generate a luminance gain value (G _L (Fn, k)).

On the other hand, the present invention is the brightness gain value (G _L (Fn, k)), the panel current flowing in each horizontal display period for each panel 100 using (I _F (Fn, k)), a pre-set the overcurrent limiting Value (I _LiM ). However, in an image in which the panel current value I _F (Fn, k) is formed in the vicinity of the overcurrent limit value I _LiM , a slight overcurrent may occur due to a change in the contents of the previous and next frames. Even in such a case, it is possible to suppress the fine overcurrent through the current control according to the luminance gain value (G _L (Fn, k)). However, since the flicker is generated due to the luminance change due to the current control, Securing an allowable margin may be advantageous in terms of image quality. Accordingly, the present invention further sets an overcurrent allowable margin value Im that can tolerate minute instantaneous overcurrents, and sets the overcurrent allowable margin value Im and the panel current value I _F (Fn, k) By adjusting the rate of change of the luminance gain value (G _L (Fn, k)) by generating the luminance gain value (G _L (Fn, k)) by comparing the overcurrent limit value (I _LiM ) It is possible to prevent deterioration of image quality by adjusting the luminance change. To this end, the gain calculation unit 213d compares the overcurrent allowable margin value Im with the panel current value I _F (Fn, k) and the overcurrent limit value I _LiM , (G ' _L (Fn, k)) to the data modulation section 213e.

For example, when the panel current value I _F (Fn, k) is equal to or smaller than the overcurrent limit value I _LiM (I _F (Fn, k) ≤I _LiM ), the gain calculator 213d ) Can generate a final luminance gain value G ' _L (Fn, k) having a value of a constant 1 as shown in the following equation (4) and supply it to the data modulation section 213e.

As another example, when the panel current value I _F (Fn, k) is equal to or greater than the overcurrent limit value I _LiM and less than the overcurrent margin value Im (I _LiM ≤I _F (Fn, k) < Im), and the gain calculator 213d calculates the current gain value G _L (Fn, k) of the current horizontal line of the current frame and the current gain value It can be calculated by a weighted average of _{(G L (Fn, k-} 1)) generating a final luminance gain value _{(G 'L (Fn, k} )) in the current horizontal line to supply a data modulation unit (213e).

As another example, when the panel current value I _F (Fn, k) is equal to or larger than the overcurrent margin margin Im (Im I _F (Fn, k)), the gain calculation unit 213d ) Generates the final luminance gain value G ' _L (Fn, k) without correction as the luminance gain value G _L (Fn, k) of the current horizontal line as shown in Equation (6) And supplies it to the modulation section 213e.

The data modulator 213e according to the embodiment calculates the current horizontal line data Idata (Fn, k) according to the luminance gain value G _L (Fn, k) of the current horizontal period supplied from the gain calculator 213d. and generates the modulated data Mdata (Fn, k) of the current horizontal line by modulating the modulated data Mdata (k, k) .

The data modulating unit 213e according to another embodiment modulates the current horizontal line data Idata (k) according to the final luminance gain value G ' _L (Fn, k) of the current horizontal period supplied from the gain calculator 213d. And generates the modulated data Mdata (Fn, k) of the current horizontal line by modulating the modulated data Mdata (Fn, k) 230).

The timing controller 210 according to the embodiment of the present invention estimates the panel current value flowing through the display panel 100 for each current horizontal period based on the current horizontal line data Idata and outputs the luminance gain value G _L And corrects the occurrence of an overcurrent momentarily flowing in the display panel 100 by modulating the current horizontal line data Idata according to the luminance gain value G _L (Fn, k) can do.

4 is a graph showing currents flowing through a display panel according to a frame image in the present invention and a conventional organic light emitting diode display.

In FIG. 4, the graph A shows the current waveform of the present invention, and the graph B shows the conventional current waveform. 4, the present invention modulates the current horizontal line data Idata on the basis of the luminance gain value G _L (Fn, k) generated for each horizontal period so that the adjacent front and rear frames Fn-1 , Fn are switched, the current flowing through the display panel 100 is controlled to be equal to or lower than the overcurrent limit value I _Lim or the overcurrent allowable margin value Im.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. Will be clear to those who have knowledge of. Therefore, the scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention.

100: display panel 200:
210: timing control unit 211: control signal generation unit
213: Overcurrent control unit 213a: Line current calculation unit
213b: storage unit 213c: panel current calculation unit
213d: gain calculation unit 213e: data modulation unit
220: Gate driver 230: Data driver

Claims (11)

A display panel made up of a plurality of pixels including an organic light emitting element emitting light by a current corresponding to a data voltage; And
The current horizontal line data of the current frame inputted every horizontal period is analyzed to predict the panel current value flowing in the display panel and the luminance gain value of the current horizontal period for controlling the predicted panel current value to be equal to or lower than the overcurrent limit value is calculated And a panel driver for modulating the current horizontal line data according to the calculated luminance gain value and displaying the modulated current horizontal line data on a display panel. The method according to claim 1,
Wherein the panel-
A timing controller for calculating the panel current value and the luminance gain value for each of the horizontal periods and for generating the modulation data by modulating the current horizontal line data according to the luminance gain value;
A gate driver for sequentially supplying gate signals to a plurality of gate lines under the control of the timing controller; And
And a data driver for converting the modulation data input from the timing controller into a data voltage and supplying the data voltage to the data line. 3. The method of claim 2,
Wherein the overcurrent control unit comprises:
A line current calculation unit for analyzing current horizontal line data of a current frame inputted every horizontal period to generate a current horizontal line current value;
A storage unit for storing the current horizontal line current value;
A panel current calculation unit for predicting the panel current value using the current horizontal line current value and the previous horizontal line current values stored in the storage unit;
A gain calculator for generating a luminance gain value of a current horizontal period based on the panel current value and the overcurrent limiting value; And
And a data modulator for modulating the current horizontal line data according to the luminance gain value to generate the modulated data. The method of claim 3,
Wherein the panel current calculation unit subtracts a current horizontal line current value of a previous frame stored in the storage unit from a current horizontal line current value output from the line current calculation unit, (+) The panel current value of the previous horizontal period to generate the panel current value. The method of claim 3,
Wherein the gain calculator subtracts the panel current value of the previous horizontal period of the current frame from the overcurrent limit value and adds the result of the subtraction operation to the current horizontal line current value of the previous frame, Generates a current gain value by dividing the result of the addition operation by the current horizontal line current value,
Wherein the current gain value is converted into the luminance gain value based on a current-luminance characteristic set in accordance with a linear or nonlinear relationship between current and luminance of the display panel. 6. The method of claim 5,
Wherein the gain calculator generates the current gain value as the luminance gain value based on the current-luminance characteristic set in accordance with the linear relationship between the current and the luminance of the display panel. 6. The method of claim 5,
The gain calculator may convert the current gain value using a modeling function according to a nonlinear relationship between the current and the luminance based on the current-luminance characteristic set according to the nonlinear relationship between the current and the luminance of the display panel, And generates a luminance gain value. 8. The method according to any one of claims 5 to 7,
Wherein the gain calculator compares the overcurrent allowable margin value with the panel current value of the current horizontal period and the overcurrent limit value and supplies the luminance gain value to the data modulator without correction or correction according to the comparison result. Emitting display device. 9. The method of claim 8,
Wherein the gain calculator corrects the luminance gain value to a constant 1 and supplies the luminance gain value to the data modulation unit when the panel current value is equal to or less than the overcurrent limit value. 9. The method of claim 8,
Wherein the gain calculator calculates a gain of the current horizontal line through a weighted average calculation of the luminance gain value of the current horizontal line and the luminance gain value of the previous horizontal line when the panel current value is equal to or greater than the overcurrent limit value and less than the overcurrent allowable margin value, And corrects the luminance gain value and supplies the corrected luminance gain value to the data modulation unit. 9. The method of claim 8,
Wherein the gain calculator supplies the luminance gain value to the data modulator without correction when the panel current value is equal to or greater than the overcurrent allowable margin value.

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