KR20110046113A - Organic electroluminescent device - Google Patents

Abstract

PURPOSE: An organic electroluminescent device is provided to control luminance according to watching conditions by periodically supplying a data signal displaying a back at frame unit. CONSTITUTION: In an organic electroluminescent device, a timing controller(110) output image data and black data to a driving IC(160). The driving IC(170) receives the image data and black data from a timing controller. A look up table(130) sets an address set value related to luminance information. A black data insertion time controller(140) controls the output of the black data according to the address set value through a mux. The timing controller applies luminance to a decoder.

Description

Organic electroluminescent device

The present invention relates to an organic electroluminescent device, and more particularly, to an organic electroluminescent device capable of controlling external luminance.

In recent years, as the society enters the full-scale information age, the field of flat panel display devices that process and display large amounts of information has been rapidly developed. In recent years, the flat panel having excellent performance of thinning, light weight, and low power consumption has recently been developed. As a display device, a liquid crystal display device or an organic light emitting device has been developed to replace a conventional cathode ray tube (CRT).

Among the flat panel display devices, an active matrix liquid crystal display device including an array substrate having a thin film transistor, which is a switching element capable of controlling voltage on / off, for each pixel, realizes resolution and video. Because of its ability, it is attracting the most attention, and recently, it has high brightness and low operating voltage characteristics, and because it emits light by itself, it has a high contrast ratio, an ultra thin display, and a response time. An organic light emitting device that is easy to implement a moving picture of about microseconds, has no limitation of viewing angle, is stable even at low temperatures, and is driven at a low voltage of DC 5 to 15V, thus making it easy to manufacture and design a driving circuit.

The organic light emitting diode having such characteristics is largely divided into a passive matrix type and an active matrix type. In the passive matrix method, since the scan lines and the signal lines cross each other to form a device in a matrix form, each pixel Since the scan lines are sequentially driven over time in order to drive, the instantaneous luminance must be equal to the average luminance multiplied by the number of lines in order to represent the required average luminance.

However, in the active matrix method, a thin film transistor, which is a switching element that turns a pixel on or off, is positioned for each pixel, and the first electrode connected to the thin film transistor is a pixel. The second electrode, which is turned on / off in units and faces the first electrode, is formed on the entire surface to become a common electrode.

In the active matrix method, the voltage applied to the pixel is charged in the storage capacitor, and the power is applied until the next frame signal is applied, thereby continuously driving for one screen regardless of the number of scan lines. do. Therefore, since low luminance, high definition, and large size can be obtained even when a low current is applied, an active matrix type organic light emitting diode is mainly used in recent years.

However, since the conventional organic light emitting device is a device using self-emission of the organic light emitting layer, unlike the liquid crystal display device which can control the overall brightness by controlling the amount of light incident on the liquid crystal display panel by adjusting the voltage applied to the lamp. The luminance of the entire display area cannot be adjusted from the outside.

In particular, as mobile devices such as mobile phones and PDAs are widely used in recent years, video calls through the mobile phones have been conducted in various places, and video viewing through the PDA has been made. However, in the case of a portable device having an organic light emitting device, there is no external brightness control device even though the brightness is required due to a change in the surrounding environment, and thus it is used while being fixed to one brightness that has been adjusted in manufacturing the product. Accordingly, the user may see a relatively dark screen when the brightness is relatively high, and when the surrounding environment is dark, the user may view a screen that is too bright, causing a problem such as increasing eyestrain.

The present invention has been made to solve the above problems, and an object thereof is to provide an organic light emitting device having a means for adjusting external luminance and a driving method thereof.

The organic light emitting device according to an embodiment of the present invention for achieving the above object is an organic light emitting device including an organic light emitting device panel having an external brightness control device, a system, a timing controller and a driving IC. The system may be connected to the external luminance controller to transmit the luminance information adjusted by the external luminance controller to the timing controller, wherein the timing controller reflects the received luminance information received by the system. By reducing the time ratio of the video signal of the image displayed in the display area of the organic light emitting device panel and increasing the time ratio of applying the black data indicating the black state instead of the video signal, by the black data for one frame time Luminance adjustment by adjusting the ratio of displaying images It characterized.

In this case, the timing controller may include a decoder, a lookup table, a black data insertion time controller, and a mux.

In addition, the look-up table provides an address setting value related to all luminance information that can be changed by the external luminance adjusting device, and the address setting value includes black data per frame in the display area of the organic light emitting diode panel. It is a feature of determining the time ratio to be displayed.

In addition, the luminance information applied to the system is applied to the decoder is changed into a digital value, the luminance information changed into a digital value is black data insertion time control unit in the state that the address setting value corresponding to the luminance information is provided by the look-up table And the black data insertion time controller controls the output time of the black data to be input to the display area of the organic light emitting display panel according to the address set value selected through the lookup table. do.

The organic light emitting device according to the present invention has an advantage that luminance can be adjusted according to an image viewing environment from the outside by periodically applying a data signal displaying black on a frame basis.

In addition, by inserting black data, an afterimage due to hysteresis loss of the driving thin film transistor is improved, and motion blur is improved.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

1 is a circuit diagram of one pixel area of an organic light emitting diode according to an exemplary embodiment of the present invention.

As illustrated, one pixel area of an organic light emitting diode according to an exemplary embodiment of the present invention includes a switching thin film transistor STr, a driving thin film transistor DTr, a storage capacitor StgC, and an organic field. The light emitting diode E is provided.

In more detail, the gate line GL extends on the boundary of the pixel region in the first direction, and the data on the boundary of the pixel region P in the second direction crossing the first direction. The wiring DL is formed, and the power supply wiring PL is spaced apart from the gate wiring data or the data wiring DL to apply the power supply voltage Vdd. In the drawing, the power line PL is formed to be spaced apart from the data line DL.

 In addition, a switching thin film transistor STr is formed at a portion where the data line DL intersects the gate line GL, and is electrically connected to the switching thin film transistor STr and the power line PL to be driven. The thin film transistor DTr is formed.

In addition, the pixel region P is electrically connected to the organic light emitting diode E, the driving thin film transistor DTr, and the ground G. In addition, a storage capacitor StgC is formed between the gate electrode and the source electrode of the driving thin film transistor DTr.

On the other hand, when driving the organic light emitting device according to the present invention having the above-described configuration, when a gate voltage having a value greater than the threshold voltage of the switching thin film transistor (STr) is applied through the gate line (GL) The switching thin film transistor STr is in an on state, and when an image data signal voltage is applied through the data line DL, the switching thin film transistor STr is transferred to a gate electrode of the driving thin film transistor DTr to transmit the driving thin film. The transistor DTr is turned on and light is output through the organic light emitting diode E.

On the other hand, when the driving thin film transistor DTr is in an on state, the level of the current flowing from the power supply line PL to the organic light emitting diode E is determined, and thus the organic light emitting diode E It is possible to implement gray scale. In this case, the storage capacitor StgC serves to maintain a constant gate voltage of the driving thin film transistor DTr when the switching thin film transistor STr is turned off, thereby switching the switching thin film transistor STr. Even if is turned off, the level of the current flowing through the organic light emitting diode E can be kept constant until the next frame.

In the organic light emitting diode which performs such driving, a characteristic of the present invention is to swing the Vdd voltage applied to the power supply line PL, which implements the gray scale level of the organic light emitting diode E, periodically. In other words, a portion that displays black instead of a full color image occurs within a display area during one frame so that the luminance can be adjusted.

At this time, the time for implementing the full color image and the time for displaying the black state in the one frame by the external brightness control is changed, so that the user substantially looking at the image feels that the overall brightness of the image has changed.

That is, the external brightness control device of the organic light emitting device is characterized in that the brightness is controlled by changing the insertion time ratio of the black data when the user increases or decreases the brightness for convenience.

2 is an external luminance control block diagram using black data insertion of an organic light emitting diode according to the present invention, and FIG. 3 illustrates a scanning method of image data and black data for one frame in the organic light emitting diode according to the present invention. It is a schematic diagram.

As illustrated, when the organic light emitting device 190 according to the present invention receives luminance information having a luminance specific value into the system 100 by a switch operation of an external luminance adjusting device (not shown), the luminance information is An interface, for example, is applied to the timing controller 110 through a pulse width modulator (PWM), and the signal low voltage finally passed through a plurality of steps inside the timing controller 110 is applied to the driving IC 170. The driving IC 170 may change the luminance of an image implemented in the display area of the organic light emitting diode.

In this case, the timing controller 110 includes a decoder 120, a lookup table 130, and a black data insertion time controller 140.

In more specific driving operation, when luminance information is input to the system 110 by a switch operation of an external luminance adjusting device (not shown), the luminance information is transmitted through an interface, for example, a pulse width modulator (PWM). It is applied to the decoder 120 of 110, and is converted into a digital signal at the decoder 120.

Thereafter, the luminance information changed by the decoder 120 into the digital signal is inserted into the black data in a state where the address setting value corresponding to the changed luminance information is provided by the lookup table 130 having the address setting value according to the luminance change value. It is input to the time controller 140.

Meanwhile, the lookup table 220 provides an address setting value related to all luminance information that can be changed, wherein the address setting value is black data per frame in the display area of the organic light emitting device panel 170. It is information to determine the time ratio for displaying. For example, when the organic light emitting diode is driven at 60 Hz, one frame becomes 8.35 msec, and the lookup table has information such as how long to display black data instead of image data. . For example, when the user adjusts the brightness to the highest value, the black data has an insertion time of 0 and displays all of the frame time as pure image data only, and when the user adjusts the brightness to the lowest value for 1/2 frame time. Is characterized in that it has a value previously input to display a full color image by image data and to display a black image by black data for the remaining half frame time.

The black data insertion time controller 140 controls the output of the black data to be input to the display area through the mux 150 according to the address setting value selected through the lookup table 130.

Meanwhile, all the steps for adjusting the luminance are performed in the timing controller 110, and the timing controller 110 performs image data and black data based on the signal information output through the black data insertion time controller 140. Although not shown in the drawing, the image data and the black data insertion time information inputted from the black data insertion time control unit 140 and the black data through the black data through the black circuit are not adjusted. A plurality of control signals for input to the display area of the panel 170 are output.

The driving IC 170 receives the image data and the black data output from the timing controller 110, and adjusts the display time of the image data and the black data according to the control signal and outputs them to the display area.

The organic light emitting device of the present invention having such a configuration adjusts the time ratio of one frame of black data inserted into the display area of the organic light emitting device panel 170 according to the brightness change value controlled from the outside by the user. It is characterized by being able to have a suitable brightness for the scene used.

 The organic light emitting device according to the present invention includes an external luminance adjusting device, and when the user controls the luminance by operating the external luminance adjusting device, the black data is inserted with a specific time ratio per frame so that the black data may be inserted. The overall luminance of the display area may vary according to the time ratio, and the motion blur phenomenon may be reduced by the black data input.

1 is a circuit diagram of one pixel of an organic light emitting device according to the present invention;

2 is an external luminance control block diagram using black data insertion of the organic light emitting device according to the present invention.

3 is a diagram illustrating a scanning method of image data and black data for one frame in the organic light emitting device according to the present invention.

<Explanation of symbols for main parts of the drawings>

100: system 110: timing controller

120: decoder 130: lookup table

140: black data insertion time control unit

150: mux 160: drive IC

170: organic light emitting device panel 190: organic light emitting device

Claims (4)

In an organic light emitting device comprising an organic light emitting device panel having an external brightness control device, a system, a timing controller and a driving IC, The system is connected to the external brightness control device to transfer the brightness information adjusted by the external brightness control device to the timing controller, The timing controller reflects the received luminance information received by the system to reduce the time ratio of the image signal of the image displayed on the display area of the organic light emitting diode panel per frame, and indicates black data instead of the image signal. The luminance of the organic light emitting device is characterized by increasing the time ratio is applied, by adjusting the ratio of displaying the image by the black data for one frame time. The method of claim 1, The timing controller includes a decoder, a lookup table, a black data insertion time controller, and a mux. The method of claim 2, The look-up table provides an address setting value related to all luminance information that can be changed by the external luminance adjusting device, wherein the address setting value displays black data per frame in the display area of the organic light emitting diode panel. An organic light emitting device, characterized in that the information determines the time ratio. The method of claim 3, wherein The luminance information applied to the system is applied to the decoder to be converted into a digital value, and the luminance information changed into the digital value is inputted to the black data insertion time controller in a state where an address setting value corresponding to the luminance information is provided by the lookup table. And the black data insertion time controller controls the output time of the black data to be input to the display area of the organic light emitting display panel according to the address set value selected through the lookup table. EL device.

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