KR20080093750A - Organic elcetroluminescence display and diriving method thereof - Google Patents

Abstract

An organic electro-luminescence display device and a driving method thereof are provided to extend a lifetime of a portable electronic apparatus having the OELD(Organic Electro-Luminescent Display) device. An organic electro-luminescence display device includes a battery(140), a pixel unit(100), a data driving unit(110), a scan driving unit(120), and a power supply(130). The battery stores predetermined electrical power and outputs a predetermined voltage. The pixel unit displays an image having a data line, a scan line, and first and second source lines. The data driving unit is connected to the data line and delivers the data signal to the data line. The scan driving unit is connected to the scan line and delivers scan signals to the scan line. The power supply receives the predetermined voltage from the battery and selectively generates one of first to fourth voltages according to a control signal. The power supply delivers the generated voltage to the first and second source lines.

Description

Organic electroluminescent display and driving method thereof {ORGANIC ELCETROLUMINESCENCE DISPLAY AND DIRIVING METHOD THEREOF}

1 is a structural diagram illustrating a concept of an organic light emitting display device according to an exemplary embodiment of the present invention.

2 is a structural diagram illustrating a concept of an organic light emitting display device according to an exemplary embodiment of the present invention.

3 is a circuit diagram illustrating a first power supply unit of the power supply unit illustrated in FIGS. 1 and 2.

4 is a circuit diagram illustrating a second power supply unit of the power supply unit illustrated in FIGS. 1 and 2.

5 is a graph illustrating a relationship between a current and a voltage flowing in a pixel in the organic light emitting display device illustrated in FIGS. 1 and 2.

FIG. 6 is a graph illustrating a relationship between voltage and luminance transferred from a pixel in the organic light emitting display device illustrated in FIGS. 1 and 2.

FIG. 7 is a circuit diagram illustrating an example of a pixel employed in the organic light emitting display device illustrated in FIG. 1.

FIG. 8 is a circuit diagram illustrating an example of a pixel employed in the organic light emitting display shown in FIG. 2.

The present invention relates to an organic light emitting display device and a driving method thereof, and more particularly, to an organic light emitting display device and a driving method thereof to reduce power consumption to reduce power consumption.

Recently, various flat panel displays having a smaller weight and volume than the cathode ray tube have been developed, and a liquid crystal display and an organic light emitting display have attracted attention.

A liquid crystal display device displays an image by blocking or transmitting light emitted from a backlight by a liquid crystal, and an organic light emitting display device displays an image by using a plurality of organic light emitting diodes (OLEDs). The organic light emitting diode includes an anode electrode, a cathode electrode, and an organic light emitting layer which is disposed therebetween and emits light by a combination of electrons and holes.

The liquid crystal display adjusts the arrangement of the liquid crystals by the voltage applied to the liquid crystal, and the light emitted by the backlight is transmitted or blocked by the arrangement of the liquid crystals to represent an image. The voltage applied to the liquid crystal is transferred to the liquid crystal by the data signal and maintained by the capacitor to maintain the image for a predetermined time. On the other hand, the organic light emitting display device is a self-luminous device that displays an image by adjusting an amount of current flowing through the organic light emitting diode by a data signal.

Therefore, in the case of the liquid crystal display, when the operation of the power supply unit is stopped, the backlight is turned off and no data signal is generated. However, natural light is transmitted or blocked by the liquid crystal, and the voltage generated by the data signal transmitted before the power supply is stopped in the liquid crystal is maintained by the capacitor so that the image can be represented by the natural light. Therefore, power consumption can be reduced. In addition, by using the case where the image is represented by the natural light, power consumption of the liquid crystal display may be reduced by applying to the sleep mode or the standby mode when the user does not use the liquid crystal display for a while.

However, since the organic light emitting display device displays an image by using light emitted from the organic light emitting diode, when the current does not flow through the organic light emitting diode, the image cannot be represented, and thus power is continuously consumed to represent the image. Even in the mode or the standby mode, the operation of the power supply unit continues, so there is a problem that power consumption continues to occur. In particular, when the battery is powered by a battery such as a mobile phone or a PDA, it is very important to reduce the power consumption and to extend the use time.However, the standby mode or the sleep mode cannot be specified separately. When not in use, there is no difference in power consumption, so there is a risk of not using for a long time.

The present invention was created in order to solve the above problems of the prior art, an object of the present invention is to reduce the power consumption when not in use to increase the use time of the mobile phone or PDA using a battery, etc. An electroluminescent display and its driving method are provided.

A first aspect of the present invention for achieving the above object is a pixel portion including a battery, a data line, a scan line, a first power line and a second power line for storing a constant power and outputting a predetermined voltage and displaying an image. A data driver connected to the data line to transmit a data signal, a scan driver connected to the scan line to transmit a scan signal, and a first voltage and a second voltage selectively received by a control signal by receiving a predetermined voltage from the battery; The present invention also provides an organic light emitting display device including a power supply unit configured to generate a third voltage and a fourth voltage and transmit the third voltage and the fourth voltage to the first power line and the second power line.

A second aspect of the present invention for achieving the above object, includes a battery, a data line, a scanning line, a light emission control line, a first power line and a second power line for storing a constant power supply and outputting a predetermined voltage to display an image A pixel unit to be displayed, a data driver connected to the data line to transmit a data signal, a scan driver connected to the scan line and the light emission control line to transmit a scan signal and a light emission control signal, and receive and control a predetermined voltage from the battery The present invention provides an organic light emitting display device including a power supply unit configured to selectively generate a first voltage and a second voltage or a third voltage and a fourth voltage according to a signal and transmit the first and second voltages to the first and second power lines. .

A third aspect of the present invention for achieving the above object is a driving method of an organic light emitting display device which is operated by receiving a data signal, a scan signal, a first power source, and a second power source. Determining, generating the first power by boosting the voltage output from the battery when operating in the normal mode, generating the second power by stepping down the voltage output from the battery, and operating in the standby mode. The method may further include generating the first power by bypassing a voltage output from a battery and generating the second power by bypassing a ground voltage.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a structural diagram illustrating a concept of an organic light emitting display device according to an exemplary embodiment of the present invention. Referring to FIG. 1, the organic light emitting display device includes a pixel unit 100, a data driver 110, a scan driver 120, a power supply 130, and a battery 140.

The pixel unit 100 includes an organic light emitting diode (not shown) in which a plurality of pixels 101 are arranged and emit light in response to the flow of current to each pixel 101. And n scan lines S1, S2, ... Sn-1, Sn formed in the row direction and transmitting the scan signal, and m data lines D1, D2, forming the column direction and transmitting the data signal. ... Dm-1, Dm) are arranged. In addition, the first power source ELVDD and the second power source ELVSS are received from the power supply unit 130 and driven. Accordingly, the pixel unit 101 emits light by the scan signal, the data signal, the first power ELVDD, and the second power source ELVSS to display an image.

The data driver 110 is a means for applying a data signal to the pixel unit 100. The data driver 110 receives video data having red, blue, and green components to generate a data signal. The data driver 110 applies the data signal generated by being connected to the data lines D1, D2,... Dm-1, Dm of the pixel unit 100 to the pixel unit 100.

The scan driver 120 is a means for applying a scan signal to the pixel unit 100, and the scan driver 120 is connected to the scan lines S1, S2,... To a specific line. The data signal output from the data driver 110 is transferred to the pixel 101 to which the scan signal is transmitted.

In addition, a data signal input from the data driver 110 is applied to a specific row of the pixel unit 100 to which the scan signal is transmitted, so that a current corresponding to the data signal flows in each pixel.

The power supply unit 130 generates a first voltage and a second voltage or a third voltage and a fourth voltage according to the control signal, and transmits the generated first and second voltages to the pixel unit 100. The control signal may be output from a controller (not shown) controlling the operation of each unit or from the data driver 110. The power supply unit 130 selectively outputs the first voltage or the third voltage to be used as the first power source ELVDD, and selectively outputs the second voltage or the fourth voltage to the second power source ELVSS. It includes a second power supply to be used as.

The first voltage and the third voltage output from the first power supply unit use the voltage output from the battery. The first voltage is formed by boosting the voltage output from the battery. The third voltage bypasses the voltage output from the battery. Form. The control signal outputs one of the first voltage and the third voltage.

The second power supply unit outputs a second voltage and a fourth voltage, and the second voltage is formed by stepping down the voltage output from the battery, and the fourth voltage is formed by bypassing the ground voltage. The control signal outputs one of the second voltage and the fourth voltage.

The battery 140 is a means for outputting a predetermined voltage to the outside for a predetermined time after being connected to the outside to charge a predetermined power source, and is widely used in portable devices such as mobile phones and PDAs.

2 is a structural diagram illustrating a concept of an organic light emitting display device according to an exemplary embodiment of the present invention. Referring to FIG. 2, the organic light emitting display device includes a pixel unit 200, a data driver 210, a scan driver 220, a power supply 230, and a battery 240.

The pixel unit 200 includes an organic light emitting diode (not shown) in which a plurality of pixels 201 are arranged and emit light in response to the flow of current in each pixel 201. And n scan lines S1, S2, ... Sn-1, Sn that are formed in a row direction and transmit scan signals, and n light emission control signal lines E1, E2, ... En that transfer emission control signals. -1, En), m data lines D1, D2, ..., Dm-1, Dm, which are formed in the column direction and transmit data signals, are arranged. In addition, the first power source ELVDD and the second power source ELVSS are received from the power supply unit 230 and driven. Accordingly, the pixel unit 201 displays an image by emitting light from the organic light emitting diode by the scan signal, the data signal, the first power source ELVDD, and the second power source ELVSS.

The data driver 210 is a means for applying a data signal to the pixel unit 200. The data driver 210 receives video data having red, blue, and green components to generate a data signal. The data driver 210 applies a data signal generated by being connected to the data lines D1, D2,... Dm-1, Dm of the pixel unit 200 to the pixel unit 200.

The scan driver 220 is a means for applying a scan signal and a light emission control signal to the pixel unit 200. The scan driver 220 is a scan line S1, S2, ... Sn-1, Sn and a light emission signal line E1. , E2, ... En-1, En) to transmit a scan signal and a light emission control signal to a specific row of the pixel unit 200. The data signal output from the data driver 210 is transmitted to the pixel 201 to which the scan signal is transmitted, and the pixel 201 to which the emission control signal is transmitted emits light according to the emission control signal.

In addition, a data signal input from the data driver 210 is applied to a specific row of the pixel unit 200 to which the scan signal is transmitted to generate a current corresponding to the data signal, and the current generated by the emission control signal is an organic light emitting diode. Is transmitted to the pixel to emit light.

In addition, the scan driver 220 may be divided into a scan driver circuit for generating a scan signal and a light emitting driver circuit for generating a light emission control signal, and the scan driver circuit and the light emitting driver circuit may be included in one component part. It may be separated into separate components.

The power supply 230 generates a first voltage and a second voltage or a third voltage and a fourth voltage by the control signal, and transmits the generated first voltage and the second voltage to the pixel unit 200. The control signal may be output from the controller or output from the data driver. The power supply unit 230 selectively outputs the first voltage or the third voltage to be used as the first power source ELVDD, and selectively outputs the second voltage or the fourth voltage to the second power source ELVSS. It includes a second power supply to be used as.

The first voltage and the third voltage output from the first power supply unit use the voltage output from the battery. The first voltage is formed by boosting the voltage output from the battery. The third voltage bypasses the voltage output from the battery. Form. The control signal outputs one of the first voltage and the third voltage.

The second power supply unit outputs a second voltage and a fourth voltage, and the second voltage is formed by stepping down the voltage output from the battery, and the fourth voltage is formed by bypassing the ground voltage. The control signal outputs one of the second voltage and the fourth voltage.

The battery 140 is a means for outputting a predetermined voltage to the outside for a predetermined time after being connected to the outside to charge a predetermined power source, and is widely used in portable devices such as mobile phones and PDAs.

3 is a circuit diagram illustrating a first power supply unit of the power supply unit illustrated in FIGS. 1 and 2. Referring to FIG. 3, a boost circuit boosts and outputs a voltage Vin input from a battery.

The boost circuit receives the voltage Vin from the battery and charges the electromotive force generated in the coil L3 by the reflux diode D3 by the capacitor C3 to step up the voltage Vin delivered from the battery to output the output Vout. )do. At this time, when the switching transistor Tsw3 is turned off by the control signal, the voltage output from the battery is output to the output terminal through the reflux diode D3, and the voltage output from the battery is transmitted to the output terminal. The voltage of the first power supply is transmitted to the first power supply line so that the voltage of the first power supply is lower than the driving state.

4 is a circuit diagram illustrating a second power supply unit of the power supply unit illustrated in FIGS. 1 and 2. Referring to FIG. 4, the buck boost circuit inverts and outputs the voltage Vin output from the battery.

The buck-boost circuit boosts or step-downs the voltage Vin output from the battery by the electromotive force of the coil L4 and inverts it to be transmitted through the second power line of the pixel unit to generate a second power source of the pixel unit. When the switching transistor Tsw4 is turned off by the control signal, the ground voltage is transmitted to the output terminal through the coil L4 and the freewheeling diode D4, and the output terminal outputs the ground voltage. Therefore, when it is determined that the control signal is the standby mode or the sleep mode, the voltage of the second power supply becomes the ground voltage.

FIG. 5 is a graph illustrating a relationship between current and voltage flowing in a pixel in the organic light emitting display device shown in FIGS. 1 and 2, and FIG. 6 is a pixel diagram illustrating a pixel transfer in the organic light emitting display device shown in FIGS. 1 and 2. This graph shows the relationship between voltage and luminance. Referring to FIGS. 5 and 6, when the voltage output from the battery has a voltage between 3.2 and 4.2 V, current may flow through the pixel to represent an image. If the voltage output from the battery is 3.2V, the image may be represented using only red color.

FIG. 7 is a circuit diagram illustrating an example of a pixel employed in the organic light emitting display device illustrated in FIG. 1. Referring to FIG. 7, the pixel includes a first transistor M71, a second transistor M72, a third transistor M73, a capacitor C7st, and an organic light emitting diode OLED.

The first transistor M71 has a source connected to the first power source ELVDD, a drain connected to a source of the third transistor M73, and a gate connected to the first node P. The second transistor M72 has a source connected to the data line Dm, a drain connected to the first node P, and a gate connected to the scan line Sn. The third transistor M73 has a source connected to the drain of the first transistor M71, a drain connected to the anode electrode of the organic light emitting diode OLED, and a gate connected to the emission control line En. In the capacitor C7st, the first electrode is connected to the first power source and the second electrode is connected to the first node P. The organic light emitting diode OLED is positioned between the anode electrode and the cathode electrode, and includes an emission layer emitting light when current flows from the anode electrode to the cathode electrode, and the anode electrode is a third transistor. It is connected to the drain of M73 and the cathode is connected to the second power source ELVSS.

In the operation of the pixel, when the scan signal is turned low and the second transistor M72 is turned on, the data signal transmitted through the data line Dm is transferred to the first node P so that the second of the capacitor C7st is transferred. The data signal is transmitted to the electrode. At this time, the voltage of the first power source ELVDD is transferred to the first electrode of the capacitor C7st. When the scan signal becomes high and the second transistor M72 is turned off, the first node P and the data line Dm are in a floating state, and the voltage of the first node P is a capacitor. The voltage of the data signal is maintained by (Cst). In addition, the voltage of the first node P is transmitted to the gate of the first transistor M71 so that the current flows in response to the voltage of the first node P from the source to the drain electrode. . At this time, when the third transistor M73 is turned off by the light emission control signal and the third transistor M73 is turned off by the light emission control signal, the current transmitted to the organic light emitting diode OLED is cut off, When the light emitting diode OLED does not emit light and the third transistor M73 is turned on by the light emission control signal, a current flows to the organic light emitting diode OLED so that the light emitting diode OLED emits light. .

FIG. 8 is a circuit diagram illustrating an example of a pixel employed in the organic light emitting display device illustrated in FIG. 2. Referring to FIG. 8, a pixel includes a first transistor M81, a second transistor M82, a third transistor M83, a fourth transistor M84, a fifth transistor M85, and a sixth transistor M86. ), A first capacitor Cst, a second capacitor C82, and an organic light emitting diode OLED.

In the first transistor M81, a source is connected to the first node P1, a gate is connected to the second node P2, and a drain is connected to the third node P3 so that a current corresponding to the voltage of the gate is first. It flows from the node P1 to the 3rd node P3.

The second transistor M82 has a source connected to a data line, a gate connected to a first scan line Sn, and a drain connected to a first node P1 to a scan signal transmitted through the first scan line Sn. The on / off operation is performed to transfer the data signal flowing through the data line to the first node P1.

The third transistor M83 has a source connected to the second node P2, a gate connected to the first scan line Sn, and a drain connected to the third node P3 and transferred through the first scan line Sn. When the on-off operation is performed by the scan signal, the potential of the second node P2 and the third node P3 is equal to each other so that the first transistor M81 is diode-connected corresponding to the scan signal. The data signal transmitted to the first node P1 may be transmitted to the second node P2 through the first transistor M81 and the third transistor M83.

The fourth transistor M84 has a source and a gate connected to the second scan line Sn-1, and a drain connected to the second node P2 to pass the first capacitor C8st through the second scan line Sn-1. Initialization is performed by the transmitted scan signal to prevent the data signal of the current frame transmitted to the second node P2 from being distorted by the data signal of the previous frame.

The fifth transistor M85 has a source connected to the first power supply ELVDD, a gate connected to the emission control line En, and a drain connected to the first node P1, and transferred through the emission control line En. The first power source ELVDD may be transmitted to the first node P1 by the emission control signal.

The sixth transistor M86 has a source connected to a third node P3, a gate connected to an emission control line En, and a drain connected to an organic light emitting diode OLED, and transferred through the emission control line En. The flow of current flowing from the first node P1 to the third node P3 is controlled by the first transistor M81 by the light emission control signal.

The first capacitor M81 is connected to the first electrode of the first power source ELVDD and the second electrode of the first capacitor M81 is connected to the drain of the fourth transistor M84 through the second node P2. Keep the voltage at The voltage of the second node P2 becomes the voltage of the data signal transmitted by the data signal.

In the second capacitor C82, the first electrode is connected to the gate of the first transistor M81, and the second electrode is connected to the gate of the second transistor M82 so that the voltage of the gate of the first transistor M81 and the second electrode are connected to each other. The difference in the voltage of the gate of the transistor M82 is stored.

The organic light emitting diode OLED is connected to the drain of the sixth transistor M86 and flows from the first node P1 to the third node P3 when the sixth transistor M86 is turned on by the emission control signal. It receives current and emits light.

According to the organic light emitting display device and the driving method thereof according to the present invention, power consumption can be reduced, and the use time of a mobile phone, PDA, etc. employing the organic light emitting display device can be further increased.

While preferred embodiments of the present invention have been described using specific terms, such descriptions are for illustrative purposes only and it is understood that various changes and modifications may be made without departing from the spirit and scope of the following claims. You must lose.

Claims (23)

A battery for storing a constant power and outputting a predetermined voltage; A pixel portion including a data line, a scanning line, a first power line, and a second power line to display an image; A data driver connected to the data line to transmit a data signal; A scan driver connected to the scan line to transmit a scan signal; And A power supply unit receiving a predetermined voltage from the battery and selectively generating a first voltage and a second voltage or a third voltage and a fourth voltage according to a control signal and transferring the first voltage and the second voltage to the first power line and the second power line; An organic light emitting display device. The method of claim 1, And a control unit, wherein the control signal is output from the control unit. The method of claim 1, And the control signal is outputted from the data driver. The method of claim 1, And the third voltage is an output voltage of a battery. The method of claim 1, And said fourth voltage is a ground voltage. The method of claim 1, The voltage driving unit includes a first power supply unit for outputting a first voltage or a third voltage and a second power supply unit for outputting the second voltage or the fourth voltage. The method of claim 1, And the pixel portion is in a sleep mode or a standby mode when the third voltage and the fourth voltage are transferred to the first power line and the second power line. The method of claim 6, The first power supply unit includes a boost circuit. The method of claim 6, And the second power supply unit includes a buck-boost circuit. The method of claim 8, The boost circuit includes an input unit configured to receive the battery voltage and the ground voltage, a voltage change unit for boosting the battery voltage to generate the first voltage, and a switch for bypassing the battery voltage to the control signal. Display. The method of claim 9, The buck-boost circuit includes an input unit for receiving the battery voltage and the ground voltage, and a voltage changer for dropping the battery voltage to generate the second voltage, and a switch for bypassing the ground voltage by the control signal. An organic light emitting display device. A battery for storing a constant power and outputting a predetermined voltage; A pixel unit including a data line, a scanning line, a light emission control line, a first power line and a second power line and displaying an image; A data driver connected to the data line to transmit a data signal; A scan driver connected to the scan line and the light emission control line to transmit a scan signal and a light emission control signal; A power supply unit receiving a predetermined voltage from the battery and selectively generating a first voltage and a second voltage or a third voltage and a fourth voltage according to a control signal and transferring the first voltage and the second voltage to the first power line and the second power line; An organic light emitting display device. The method of claim 12, And a control unit, wherein the control signal is output from the control unit. The method of claim 12, And the control signal is outputted from the data driver. The method of claim 12, And the third voltage is an output voltage of a battery. The method of claim 12, And said fourth voltage is a ground voltage. The method of claim 12, The voltage driving unit includes a first power supply unit for outputting a first voltage or a third voltage and a second power supply unit for outputting the second voltage or the fourth voltage. The method of claim 12, And the pixel unit is in a sleep mode or a standby mode when the third and fourth voltages are output from the voltage driver. The method of claim 17, The first power supply unit includes a boost circuit for boosting and outputting a battery voltage. The method of claim 17, The second power supply unit includes a buck boost circuit for inverting and outputting a battery voltage. The method of claim 19, The boost circuit includes a switching transistor operated by a control signal, and the battery voltage is output by the operation of the switching transistor. The method of claim 19, And the boost circuit includes a switching transistor operated by a control signal, and blocks the battery voltage and outputs a ground voltage by the operation of the switching transistor. A driving method of an organic light emitting display device operating by receiving a data signal, a scanning signal, a first power source, and a second power source, Determining whether the standby mode and the normal mode are operated; Generating a first power by boosting a voltage output from a battery when operating in the normal mode, and generating the second power by stepping down a voltage output from the battery; And And generating the first power by bypassing the voltage output from the battery when the battery is operated in the standby mode, and generating the second power by bypassing the ground voltage.

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