KR20020051701A - Organic Elecroluminescence Device and Drive Method for the same - Google Patents

Abstract

PURPOSE: An organic electro-luminescent display device and a method for driving the same are provided to improve image quality by compensating for gray levels according to errors. CONSTITUTION: A multitude of scan lines(S) are used for receiving scan signals. A multitude of data lines(D) are used for receiving data signals. The scan lines(S) and the data lines(D) cross each other. A pixel portion(100) is defined by the scan lines(S) and the data lines(D). A compensating pixel portion(200) is composed of compensating pixels formed in each data line(D). A gate drive IC(300) and a data drive IC(400) apply the scan signal and the data signals to the scan lines(S) and the data lines(D) in order to drive a panel including the pixel portion(100) and the compensating pixel portion(200). A data correction portion(500) stores an error value between a reference signal of the pixel portion(100) and a digital conversion signal of the compensating pixel portion(200) and corrects the data signal applied to the data drive IC(400). A timing controller(600) controls a point of applying time of the data signal.

Description

Organic electroluminescent display device and driving method thereof {Organic Elecroluminescence Device and Drive Method for the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent display device and a method of driving the same, and more particularly, to an organic electroluminescent display device and a method of driving the same, which improve luminance due to a characteristic difference (particularly, an error in threshold voltage or mobility) of a transistor of a driving unit of a panel. It is about.

FIG. 1 illustrates one pixel of an active matrix type organic electroluminescent panel according to the prior art, wherein each pixel 103 is formed of an organic light emitting device (OLED) 102 and two TFTs. A driver 101 for supplying a current for driving 102 is formed.

That is, as shown in FIG. 1, a scan line (S) for selecting a pixel to be driven, a data line (D: Data Line) for applying a voltage to the pixel according to a controlled amount, and Switch _P1, which is an active element that controls the flow of data in accordance with a signal, a power line (P) for supplying power, and a voltage supplied by the voltage and the power line according to a voltage applied to the data line. A driving unit 101 including a capacitor _Cs that accumulates a charge corresponding to a voltage difference, a transistor _PO for receiving a voltage from the charge accumulated in the capacitor _Cs and allowing a current to flow, and a current flowing through the driving transistor _PO OLED (organic light emitting device: 102) that emits light by.

The organic electroluminescent panel includes a plurality of pixels as described above, and each pixel includes an OLED 102 which is a light emitting unit and a driving unit 101 which drives the OLED 102. However, when a data signal having the same luminance is to be displayed, the desired luminance can be obtained due to a characteristic difference of the driving transistor in the design due to a characteristic difference (especially, a threshold voltage or mobility error) of the driving transistor of the driving unit 101. none.

That is, when the gray level signal corresponding to the data signal is applied to the data line, the driving current flowing through the driving transistor of the driving unit 101 has a value different from the design reference current value. Problems arise due to light emission at different luminance depending on the difference (particularly, error of threshold voltage or mobility). When the TFT is used as a driving transistor when the organic electroluminescent panel is driven, streaks are generated on the screen due to a difference in characteristics of the TFT (particularly, an error in threshold voltage or mobility). In order to solve this problem, it is difficult to secure and adjust the uniformity of the transistor characteristics (particularly the threshold voltage) of the TFT in order to solve these problems, and the difference in the characteristics of the transistors of the TFT (particularly, the threshold voltage or mobility error) during the manufacturing process of the panel is difficult. ) Will occur.

Therefore, the present invention has been made to solve the above problems, and compared with the signal corresponding to the intensity of the light emitted in the normal driving compared to the reference signal in the accurate gray level driving of the organic electroluminescent display device, the error The present invention provides a high-quality organic electroluminescent display device and a driving method thereof by compensating gray levels to prevent luminance degradation and unevenness due to characteristic differences (especially, threshold voltage or mobility error) of driving transistors formed in each pixel. There is this.

1 is a view showing one pixel of an organic electroluminescent panel of an active matrix type according to the prior art

2A and 2B illustrate an organic electroluminescent display device of an active matrix type according to the present invention.

FIG. 3 is a diagram showing in detail an organic electroluminescent panel of an active matrix type and a data compensator for calibrating the panel as shown in FIG.

100: pixel portion 200: compensation pixel portion

300: Gate Drive IC

400: Data Drive IC

101, 201: driver 102, 202: OLED

500: Data compensation 501: Reference memory

502: photodetector 503: ADC

504: comparator 505: LUT

600: Timing Controller

A feature of the organic electroluminescent display device according to the present invention for achieving the above object is a plurality of scan lines that are sequentially applied with a scan signal, and a plurality of scan lines that are intersected with the scan line and a data line for applying a data signal A pixel portion composed of pixels defined by; A compensation pixel unit in which one compensation pixel is formed per data line; A gate drive IC and a data drive IC applying the scan signal and the data signal to the scan line and the data line, respectively; Comparing the reference signal of the light emitted from the pixel unit and the digital conversion signal of the light emitted from the compensation pixel unit to store the error value of the two signals, the data signal applied to the data drive IC by the error value It is configured to include a data correction unit for correcting, and located one per data line.

In order to achieve the above object, the organic electroluminescent display device driving method according to the present invention is characterized in that a plurality of scan lines to which scan signals are sequentially applied, and a plurality of scan lines intersecting the scan lines and to which data signals are applied. A driving method of an organic electroluminescent display device having a pixel portion composed of pixels defined by a line, the method comprising: detecting the intensity of each light from a compensation pixel by applying a data signal per data line, and converting a digitally converted signal and a reference signal Correcting the data signal by comparison; And applying the data signal corrected in the correcting step to the data line.

According to an aspect of the present invention, the data compensator is formed per data line on one side of the compensating pixel unit and the compensating pixel unit in the organic electroluminescent display device, and the data compensating unit is performed before the normal driving of the panel consisting of the pixel unit and the compensating pixel unit. The data signal is corrected using an error value between the reference signal corresponding to all gray level signals applied to the data line and the digitally converted signal of the light emitted from the compensation pixel unit, and the desired luminance or gray color is obtained when the panel is normally driven. Non-uniform brightness due to the characteristic difference (especially, threshold voltage or mobility error) of the transistor driving the panel during panel manufacturing by applying the compensated data signal to the data line using the information stored in the data compensator to obtain the level Can be displayed to optimize the brightness.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Referring to the accompanying drawings, a preferred embodiment of an organic electroluminescent display device and a driving method thereof according to the present invention will be described.

2A and 2B illustrate an active matrix organic electroluminescent display device according to the present invention.

As shown in Fig. 2A, a plurality of scan lines S are sequentially applied to scan signals, and a plurality of scan lines S are arranged to intersect the scan lines S, and are defined by data lines D to which data signals are applied. To drive a panel consisting of a pixel unit 100, a compensation pixel unit 200 having one compensation pixel 203 formed therein for each data line D, and the pixel unit 100 and the compensation pixel unit 200. A gate drive IC 300 and a data drive IC 400 applying the scan signal and the data signal to the scan line and the data line, and a reference signal of the light emitted from the pixel unit 100 and the compensation pixel unit. Comparing the digital conversion signal of the light emitted from the 200 to store the error value of the two signals, correct the data signal applied to the data drive IC 400 by the error value, one per data line Located The data compensator 500 is configured to be included.

And a timing controller 600 for controlling an application timing of the data signal applied to the data drive IC 400, wherein the data drive IC 400 converts the data signal applied to the data drive IC 400 into an analog signal. DAC (digital-to-analog conversion, not shown) applied to the data line by converting to a.

As shown in FIG. 2B, each data compensator 500 includes a reference memory 501 for storing a reference signal of light emitted from the pixel unit 100, and a compensation pixel unit 300. A photo detector 502 for detecting the light L to emit light, an ADC 503 for digitally converting the detected light, and a comparison between the digitally converted signal and a reference signal stored in the reference memory 501. A data signal applied to the data drive IC 400 during initial driving of a panel including the comparator 504 and the pixel unit 100 and the compensation pixel unit 200 is stored and digitally converted from the comparator with a reference signal. And a LUT (look-up-table) 505 for receiving and storing an error value of the signal, correcting the data signal by the error value, and outputting a corrected data signal sig. In addition, a readout unit (not shown) for reading out the detected light between the photodetector 502 and the ADC 503 may be further included.

The LUT 505 is a reference signal of a full-gray level signal for each data line D during initial driving of the panel, an error value of a signal detected and digitally converted by the reference signal and the photodetector, The data signal compensated by the reference signal and the error value is stored and output.

In the active matrix organic electroluminescent display device configured as described above, the compensation pixel unit 200, which is connected to the pixel unit 100 and consists of one compensation pixel per data line D, is further manufactured and the data line ( D) The data signal is applied to detect the intensity of each light from the compensation pixel unit 200, and the digital signal is compared with the reference signal to correct the data signal, and the corrected data signal is converted into the data line (D). ) Is applied.

Looking at the correction of the data signal in detail, during the initial driving of the panel, the full-gray level signal of the data signal applied per data line D is sequentially applied, and the correct gray level signal is applied to the pixel unit 100. The data signal is corrected by the error value of the two signals by comparing the reference signal which is a value at the time of application and the digitally converted signal of the full-gray level signal.

That is, when the organic electroluminescent panel is first turned on, the entire digital video signal is input from the LUT 505 by an initialization operation, and an analog signal is applied to the pixel unit 100 by a digital to analog conversion (not shown). To drive the pixel. In this case, the light detector 502 detects the light emitted from the compensation pixel unit 200 including the compensation pixels formed for each data line and converts the light into a digital signal. The digital signal is compared with the reference signal stored in the reference memory 501 by the comparator 503 to output a value (correction value) that falls within the error range and stored in the LUT 505 again.

Thereafter, the video signal is directly applied to the data drive IC 400 through the timing controller 600 without the flow of the data signal of the corrected gray signal converted by the LUT 505.

FIG. 3 is a diagram illustrating in detail an organic electroluminescent panel of an active matrix type and a data compensator for calibrating the panel as shown in FIG. 2A.

As shown in Fig. 3, each pixel 103 is located at the intersection of a plurality of data lines D: D1, D2, ..., and scan lines S: S1, S2, ..., and Compensation pixel 203 located at the lower end of the data lines (D1, D2, ...), and the data correction unit 500 located at one side of the compensation pixel (203).

The pixel 103 is composed of an organic light emitting device (OLED) 102 and a driver 101 supplying a current for driving the OLED 102.

That is, as shown in FIG. 3, a plurality of scan lines S1, S2, ... are sequentially applied to the scan signals, and a plurality of data lines D1 are arranged to intersect the scan lines and apply data signals. A pixel unit 100 including a plurality of pixels 103 defined by D2, ..., a compensation pixel unit 200 including a compensation pixel 203 formed one per data line, and the pixel unit Comparing the reference signal of the light emitted from the OLED 102 of 100 (the signal stored in the reference memory of FIG. 2) with the digital conversion signal of the light emitted from the OLED 202 of the compensation pixel unit 200, And a data compensator 500 for storing error values of two signals and correcting a data signal applied to the data drive IC based on the error values.

The pixel portion 100 is composed of a plurality of pixels 103, the pixel 103 is composed of an organic EL layer formed between a pixel electrode and a metal electrode (not shown), and the scan And a driving unit 101 which is turned on by the line and receives the data signal by the data line and emits the organic EL layer by flowing a predetermined current in accordance with the data signal.

That is, the OLED 102 is one of the organic EL devices, and the organic EL device includes a hole injection layer, a hole transport layer, an emitting layer, and an electron transport layer. It is laminated and formed. A pixel electrode is formed below the hole injection layer and a metal electrode is formed above the electron transport layer.

The compensation pixel unit 200 also includes a plurality of compensation pixels 203, and the compensation pixel 203 includes an OLED 202 composed of an organic EL layer formed between a pixel electrode and a metal electrode (not shown). And a driving unit 201 which is turned on by the scan line and receives a data signal by the data line, and emits the organic EL layer by flowing a predetermined current according to the data signal.

In addition, the driving units 101 and 201 may include a first transistor P1 which is an active element that turns on the pixel and controls the flow of data by a power P for supplying power and a scan signal applied to the scan line. And a capacitor _Cs that accumulates a charge equal to the voltage difference of the data signal applied to the data line and the voltage supplied by the power, and a voltage by the charge accumulated in the capacitor _Cs. The transistor includes a flowing transistor _PO, and the driving unit may be configured with another type of circuit by adding an active element.

The data compensator 500 is as shown in Fig. 2B, and the detailed operation description is as described above.

Organic electroluminescent display device and driving method according to the present invention as described above has the following advantages.

In the conventional organic electroluminescent display device, a data compensation unit is formed on one side of the compensation pixel unit and the compensation pixel unit, and the reference signal corresponding to all gray level signals applied to the data line through the data correction unit at the time of initial driving of the panel. Since the data signal is corrected using the error value of the digitally converted signal of the light emitted from the compensation pixel unit, when the panel is driven later, the corrected data signal is applied to improve the brightness and the image quality of the organic light emitting panel. There is.

In addition, since there is no need to increase the number of transistors in the driver for controlling and driving the organic EL layer to have the desired luminance in each pixel, characteristic differences caused by the retention of a large number of transistors (particularly, Image quality can be improved while removing spots caused by errors) and improving aperture ratio.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (7)

A pixel unit including a plurality of scan lines to which scan signals are sequentially applied and pixels arranged in a plurality of scan lines crossing the scan lines and defined by data lines to apply a data signal; A compensation pixel unit in which one compensation pixel is formed per data line; Comparing the reference signal of the light emitted from the pixel unit and the digital conversion signal of the light emitted from the compensation pixel unit to store the error value of the two signals, to correct the data signal by the error value, the data line An organic electroluminescent display device comprising a data compensator located one per view. The method of claim 1, wherein the pixel Organic EL layer; And a driving unit which is turned on by the scan line and receives a data signal by the data line and emits the organic EL layers by flowing a predetermined current according to the data signal. The method of claim 2, wherein the driving unit Power to supply power; A first transistor to turn on the pixel by a scan signal applied to the scan line; A capacitor_Cs that accumulates a charge equal to a voltage difference supplied by the voltage of the data signal applied to the data line and the power; And a transistor _PO configured to receive the voltage due to the charge accumulated in the capacitor _Cs and to flow the predetermined current. The method of claim 1, wherein each of the data correction A reference memory for storing a reference signal of light emitted from the pixel portion; A photo detector detecting the light emitted from the compensation pixel unit; An ADC for digitally converting the detected light; A comparator for comparing the digitally converted signal with a reference signal stored in the reference memory; And a look-up-table (LUT) for storing data signals applied to the data lines during initial driving, storing error values of two signals of a comparator, and correcting the data signals by the error values. An organic electroluminescent display device, characterized in that. The method of claim 4, wherein the LUT is The reference signal of the full-gray level signal, the error value of the signal detected by the reference signal and the photodetector and digitally converted for each data line during initial driving, and the data compensated by the reference signal and the error value An organic electroluminescent display device characterized by storing and outputting a signal. A method of driving an organic electroluminescent display device having a plurality of scan lines to which scan signals are sequentially applied, and a pixel portion composed of a plurality of pixels intersecting the scan lines and defined by data lines to which data signals are applied. , Applying a data signal per data line to detect the intensity of each light from a compensation pixel, and correcting the data signal by comparing a digitally converted signal with a reference signal; And applying the data signal corrected in the correcting step to the data line. The method of claim 6, wherein the correcting step Sequentially applying a full-gray level signal of a data signal applied per data line during initial driving; And comparing the reference signal, which is a value when the correct gray level signal is applied to the pixel part, with the digitally converted signal of the full-gray level signal, and correcting the data signal by an error value of the two signals. A method of driving an organic electroluminescent display device.