KR20050068478A - Organic electroluminescent device and driving method thereof - Google Patents

Abstract

An organic light emitting display device according to the present invention comprises: an organic light emitting panel including a signal line to which a data signal is input, and a scan line crossing the signal line to define a pixel region; And a current amplifier connected to one end of the signal line to supply an amplified current, amplified by the input current, to the signal line before the data signal is input.

Description

Organic Electroluminescent Device And Driving Method Thereof}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device (OELD), and more particularly to a method of driving an organic electroluminescent device (OELD).

One of the new flat panel displays, the organic light emitting display device is self-luminous, and thus has a better viewing angle and contrast ratio than a liquid crystal display device. In addition, since it is possible to drive DC low voltage, fast response speed, and all solid, it is strong against external shock, wide use temperature range, and especially inexpensive in terms of manufacturing cost. Such an organic light emitting diode is also referred to as an organic light emitting diode (OLED).

The organic electroluminescent device is a deposition and encapsulation equipment because the process is very simple, unlike a liquid crystal display device or a plasma display panel (PDP).

In particular, in the active matrix method, a voltage controlling a current applied to a pixel is charged in a storage capacitor (C _ST ), and the gate is applied by applying a voltage until the next frame signal is applied. Drive continuously for one screen regardless of the number of wires.

Therefore, in the active matrix system, since the same luminance is displayed even when a low current is applied, low power consumption, high definition, and large size can be obtained.

Hereinafter, the basic structure and operation characteristics of the active matrix organic electroluminescent device will be described in detail with reference to the accompanying drawings.

1 is a circuit diagram showing the configuration of one pixel region of a general active matrix organic electroluminescent device.

As shown, a scan line is formed in a first direction, a signal line and a power line are formed in a second direction crossing the first direction and spaced apart from each other by a predetermined distance. In this example, one pixel region is defined.

The scanning line and the intersection of the signal line has the addressing element switching thin film transistor (addressing element); and is formed with a (T _S Switching TFT), it is connected to the switching thin film transistor (T _S) of storage capacitor (C _ST) is formed And a driving thin film transistor T _D , which is a current source element, is connected to a connection portion and a power line of the switching thin film transistor T _S and the storage capacitor C _ST to form the driving thin film transistor T A first electrode is connected to T _D ), and the first electrode is connected to the second electrode through an electroluminescent diode (D _EL ) of a constant current driving method.

The switching thin film transistor T _S controls the gate voltage of the driving thin film transistor T _D , and the storage capacitor C _ST stores a voltage applied to the driving thin film transistor T _D.

Hereinafter, the driving principle of the active matrix organic light emitting display device will be described.

In the active matrix method, when the gate signal is applied to the gate of the selected switching thin film transistor, the switching thin film transistor is turned on, and the data signal passes through the switching thin film transistor to be applied to the driving thin film transistor and the storage capacitor. When the transistor is turned on, current from the power supply line is applied to the organic light emitting layer through the gate of the driving thin film transistor to emit light.

At this time, the degree of opening and closing of the driving thin film transistor is changed according to the magnitude of the data signal, so that gray scale display can be performed by adjusting the amount of current flowing through the driving thin film transistor.

In the non-selection period, the data signal charged in the storage capacitor is continuously applied to the driving thin film transistor, so that the organic light emitting diode can emit light continuously until the next screen signal is applied.

The driving circuit of the organic light emitting display device will be described with reference to the drawings.

2 is a block diagram showing the configuration of a conventional organic light emitting display device.

As shown in FIG. 2, an organic light emitting diode including an organic light emitting diode (D _EL of FIG. 1) and a thin film transistor (T _S , T _D of FIG. 1) formed in a plurality of pixel regions arranged in a matrix form. The panel 10 is driven by an external signal driver 20 having a variety of integrated circuits (IC), a scan driver 30, and a controller 40.

That is, the organic light emitting panel 10 is connected through the signal driver 20 and the first connection line 22 disposed on one side, and the scan driver 30 and the second connection line 32 disposed on the other side. Connected through.

Shown not Although, the first connecting line 22 has the switching TFT is connected to the signal line, a second connection line 32 of the organic electroluminescence panel 10 is connected to a source electrode of the (T _S in FIG. 1) is a switching thin film transistor It is connected to the scan line of the organic electroluminescence panel 10, which is connected to the gate electrode of (T _S in Fig. 1).

The controller 40 is connected to the signal driver 20 through the third connection line 42, and the signal driver 20 is connected to the scan driver 30 through the fourth connection line 24.

The driving of the organic light emitting diode will be briefly described. When the controller 40 generates various signals required for display and transmits the signals to the signal driver 20, the signal driver 20 may transmit some of the received signals to the first connection line. The transmission is transmitted to the organic light emitting panel 10 through the 22 and another part is transferred to the scan driver 30 through the fourth connection line 24.

The scan driver 30 sequentially transmits a signal to the second connection line 32 using the received signal. Each of the second connection lines 32 is connected to the gate electrode of the switching thin film transistor ( _TS ) of FIG. 1. because when a signal is transmitted to the second connecting line 32, the switching thin film transistor (T _S in FIG. 1) is oN. At this time, the signal driver 20 transmits the data signal to be displayed to the first connection line 22 to drive the organic light emitting diode (D _EL of FIG. 1) to implement an image.

On the other hand, the organic light emitting display device includes one switching thin film transistor (T _S of FIG. 1) and one driving thin film transistor (T _D of FIG. 1) in one pixel area. While there is an advantage of being simple and easy to manufacture, the thin film transistor is a voltage driving method for driving the thin film transistor by a voltage output from an external driving circuit including the signal driver 20, the scan driver 30, and the controller 40. There is a problem of uniformity due to a change in the threshold voltage (Vth) of the.

In order to solve the above problems, the present invention is to provide a current-driven organic light emitting display device and a method of driving the thin film transistor of each pixel region by the current output from the driving circuit.

In particular, the organic light emitting diode of the current driving method according to the present invention includes four thin film transistors in one pixel area, and further includes a precharge part and a current amplifier part to increase the driving current source. The time for charging and discharging the thin film transistor in the pixel region can be shortened.

In order to achieve the above object, the present invention provides an organic light emitting panel including a signal line to which a data signal is input, and a scanning line crossing the signal line to define a pixel region; An organic light emitting display device, comprising: a current amplifier connected to one end of the signal line and supplying an amplified current amplified to an input current to the signal line before the data signal is input.

The organic light emitting diode may further include a precharge unit connected to the other end of the signal line to supply a precharge current to the signal line, and output a data signal and an input current of the current amplifier. It may further include.

The precharge unit includes first and second precharge transistors each including a gate electrode, a source electrode, and a drain electrode, wherein the source electrode of the first precharge transistor is connected to a high voltage source VDD, and the first precharge transistor is connected to the first precharge transistor. The gate electrode of the charge transistor is connected to the drain electrode of the first precharge transistor, the drain electrode of the first precharge transistor is connected to the source electrode of the second precharge transistor, and the gate of the second precharge transistor. A precharge signal is turned on for a predetermined time before the data signal is input, and a drain electrode of the second precharge transistor is connected to the signal line.

The organic light emitting panel includes first and second switching thin film transistors connected to the signal line and the scan line, first and second driving thin film transistors, storage capacitors, and the second driving thin film transistor connected to the second switching thin film transistor. The display device may further include a power line for supplying power and an organic light emitting diode that receives the power through the second driving thin film transistor.

The current amplifier includes first and second switches connected in parallel to the signal line, a current amplifier connected to the first switch, and a current source connected to the current amplifier and the second switch. The second switch is opened and closed according to the precharge signal, and the second switch is opened and closed according to the anti-precharge signal having a polarity opposite to that of the precharge signal.

When the precharge signal is turned on, the amplification current is equal to the precharge current or the sum of the precharge current and the pixel current flowing through the first switching thin film transistor.

The current amplifier includes first to fourth amplifying transistors including a gate electrode, a source electrode, and a drain electrode, respectively, and source electrodes of the first and second amplifying transistors are connected to a high voltage source (VDD). A drain electrode of the first amplifying transistor is connected to the gate electrodes of the first and second amplifying transistors and the current source, and a source electrode of the third amplifying transistor is connected to the drain electrode of the second amplifying transistor and the third and fourth amplifying transistors. The drain electrode of the third and fourth amplifying transistors is connected to a low voltage source VSS, and the source electrode of the fourth amplifying transistor is connected to the first switch.

The first to fourth amplification such that a current flowing through the second and third amplifying transistors is greater than a current flowing through the first amplifying transistor, and a current flowing through the fourth amplifying transistor is greater than a current flowing through the second and third amplifying transistors. The W / L ratio of the transistor can be designed.

The current amplifier includes a current amplifier connected to the signal line, and a current source connected to the current amplifier.

The current amplifier includes first to fifth amplifying transistors including a gate electrode, a source electrode, and a drain electrode and a first switch, respectively, and source electrodes of the first and second amplifying transistors are connected to a high voltage source (VDD), The drain electrode of the first amplifying transistor is connected to the gate electrodes of the first and second amplifying transistors and the current source, and the drain electrode of the third amplifying transistor is the drain electrode of the second amplifying transistor and the third to fifth amplification transistors. A gate electrode of the transistor, a source electrode of the third to fifth amplifying transistors is connected to a low voltage source VSS, and both ends of the first switch are respectively connected to drain electrodes of the fourth and fifth amplifying transistors, The drain electrode of the fifth amplifying transistor is connected to the signal line.

The first switch is opened and closed according to the precharge signal, and when the precharge signal is turned on, the amplification current is equal to the sum of the precharge current and the pixel current flowing through the first switching thin film transistor.

The current flowing through the second and third amplifying transistors is greater than the current flowing through the first amplifying transistor, and the current flowing through the fourth amplifying transistor is greater than the current flowing through the second and third amplifying transistors. The W / L ratio of the first to fifth amplifying transistors may be designed such that the current flowing is equal to the precharge current, and the current flowing through the fifth amplifying transistor is equal to the pixel current. .

The precharge unit includes first and second precharge transistors, each of which includes a gate electrode, a source electrode, and a drain electrode, and a source electrode of the first precharge transistor is connected to a low voltage source VSS. The gate electrode of the first precharge transistor is connected to the drain electrode of the first precharge transistor, the drain electrode of the first precharge transistor is connected to the drain electrode of the second precharge transistor, and the second precharge transistor A precharge signal is turned on for a predetermined time before the data signal is input, and a source electrode of the second precharge transistor is connected to the signal line.

The organic light emitting panel includes first and second switching thin film transistors connected to the signal line and the scan line, first and second driving thin film transistors, storage capacitors, and the second driving thin film transistor connected to the second switching thin film transistor. The display device may further include a power line for supplying power and an organic light emitting diode that receives the power through the second driving thin film transistor.

The current amplifier includes first and second switches connected in parallel to the signal line, a current amplifier connected to the first switch, and a current source connected to the current amplifier and the second switch.

The first switch is opened and closed according to the precharge signal, and the second switch is opened and closed according to a half precharge signal having a polarity opposite to that of the precharge signal.

When the precharge signal is turned on, the amplification current is equal to the precharge current or the sum of the precharge current and the pixel current flowing through the first switching thin film transistor.

The current amplifier includes a current amplifier connected to the signal line, and a current source connected to the current amplifier.

The current amplifier includes first to fifth amplifying transistors including a gate electrode, a source electrode, and a drain electrode and a first switch, respectively, and source electrodes of the first and second amplifying transistors are connected to a low voltage source (VSS), The drain electrode of the first amplifying transistor is connected to the gate electrodes of the first and second amplifying transistors and the current source, and the drain electrode of the third amplifying transistor is the drain electrode of the second amplifying transistor and the third to fifth amplification transistors. A gate electrode of the transistor, a source electrode of the third to fifth amplifying transistors is connected to a high voltage source VDD, and both ends of the first switch are respectively connected to drain electrodes of the fourth and fifth amplifying transistors, The drain electrode of the fifth amplifying transistor is connected to the signal line.

The first switch is opened and closed according to the precharge signal, and when the precharge signal is turned on, the amplification current is equal to the sum of the precharge current and the pixel current flowing through the first switching thin film transistor.

The current flowing through the second and third amplifying transistors is greater than the current flowing through the first amplifying transistor, and the current flowing through the fourth amplifying transistor is greater than the current flowing through the second and third amplifying transistors. The W / L ratio of the first to fifth amplifying transistors is designed such that the current flowing is equal to the precharge current and the current flowing through the fifth amplifying transistor is equal to the pixel current.

The current amplifier and the precharge unit may be built in the organic field panel.

On the other hand, to achieve the above object, the present invention comprises the steps of inputting a gate signal by selecting a scanning line of the organic light emitting panel; Inputting a data signal to a signal line defining a pixel area crossing the scan line; A method of driving an organic light emitting display device comprising the step of inputting an amplifying current to the signal line before the data signal is input such that the signal line has a potential close to the data signal.

The amplifying current may be input by a precharge unit and a current amplifier connected to the signal line, and the precharge unit and the current amplifier may be embedded in the organic light emitting panel.

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

3 is a block diagram showing the configuration of an organic light emitting display device according to a first embodiment of the present invention.

As shown in FIG. 3, the organic light emitting display device according to the first exemplary embodiment of the present invention includes an organic light emitting panel 110, a precharge unit 150, a current amplifier 160, and a signal driver. The driver circuit unit 180 includes a driver 120, a scan driver 130, and a controller 140.

In the organic light emitting panel 110, a plurality of pixel regions P defined by the signal line 125 and the scan line 135 are arranged in a matrix form, and although not shown, two switchings are provided in each pixel region P. A thin film transistor, two driving thin film transistors, and an organic light emitting diode connected thereto are formed.

The precharge unit 150 and the current amplifier 160 are connected to the organic light emitting panel 110 through the first connection line 152 and the second connection line 162, respectively, and the first connection line 152 and the second connection line 162. The connection line 162 is connected to the signal line 125 and the scan line 135 of the organic light emitting panel 110, respectively.

The signal driver 120 is connected to the precharge unit 150 through the third connection line 122, and the scan driver 130 is connected to the organic light emitting panel 110 through the fourth connection line 132.

The controller 140 is connected to the signal driver 120 through the fifth connection line 142, and the signal driver 120 is connected to the scan driver 130 through the sixth connection line.

Referring to the driving of the organic light emitting diode, when the controller 140 generates various signals necessary for the display and transmits them to the signal driver 120, the signal driver 120 transmits some of the received signals to the third connection line 122. Transfer to the precharge unit 150 through a) and another part to the scan driver 130 through the sixth connection line (124).

The scan driver 130 sequentially transmits a signal to the second connection line 132 by using the received signal, each of the second connection lines 132 of the switching thin film transistor (not shown) of the organic light emitting panel 110. The switching thin film transistor (not shown) is turned on when a signal is transmitted to the second connection line 132 because it is connected to the gate electrode. At this time, the signal driver 120 transmits the data signal to be displayed to the source electrode of the switching thin film transistor (not shown) to drive the organic light emitting diode (not shown).

Unlike the related art, in the organic light emitting display device according to the present invention, the precharge unit 150 and the current amplifier unit during the precharge period before the time when the data signal starts to be input to the switching thin film transistor (not shown). The 160 amplifies the current value of the predetermined signal output from the driving circuit unit 180 and inputs it to the signal line 125 of the organic light emitting panel 110 so that the signal line 125 has a value near a desired voltage.

Since the signal line 125 has a value near a desired voltage before the data signal is input to the signal line 125, the data signal output from the signal driver 120 after the precharge section is driven through the signal line 125. The time transmitted to the thin film transistor (not shown) can be shortened.

On the other hand, even when the precharge unit is not used and only the current amplifier is used, the time that the data signal is transmitted to the driving thin film transistor by flowing the amplified current through the signal line before the data signal is input so that the signal line has a value near a desired voltage. Can be shortened.

4 is a timing diagram illustrating driving signals of an organic light emitting display device according to a second exemplary embodiment of the present invention.

As shown in FIG. 4, the N gate clock (GCLKN) and the (N + 1) gate clock (GCLKN + 1) are respectively provided in the Nth scan line and the (N + 1) th scan line of the organic light emitting panel 110 (in FIG. ), The gate signal is sequentially input, and accordingly, the switching thin film transistor connected to the Nth scan line and the switching thin film transistor connected to the (N + 1) th scan line are sequentially turned on.

First, when the Nth scan line is selected, the data signal VIDEO is input to the switching thin film transistor through the signal line 125 of FIG. 3 during the first period t1 according to the data clock DCLK.

In the present invention, a predetermined section before the first section t1 is set as a precharge section t2, wherein the precharge section 150 of FIG. 3 and the current amplifier 160 are configured according to the precharge signal ENA_PRE. In operation, the amplified current is input to the signal line 125 of FIG. 3.

Therefore, during the precharge period t2 before the first section t1 to which the data signal VIDEO is input, the signal line 125 of FIG. 3 already has a value near a desired voltage with a high current, and the data signal VIDEO. The time taken for the data signal VIDEO to turn on / off the driving thin film transistor as desired in the initial period of the first section t1 is reduced, which can display a desired screen at an appropriate time. Means.

5A, 5B, and 5C are circuit diagrams of a pixel region, a precharge unit, and a current amplifier of an organic light emitting panel connected to one signal line of the organic light emitting diode according to the third embodiment of the present invention, respectively, and FIG. Detailed circuit diagram of the current amplifier of 5c.

As shown in FIG. 5A, in the pixel area P defined by the signal line 125 and the scan line 135, the first and second switching thin film transistors T _S1 and T _S2 , and the first and second driving thin film transistors ( T _D1 , T _D2 ), a storage capacitor C _ST , and an organic light emitting diode D _EL are disposed.

In more detail, the first and second switching thin film transistors T _S1 and T _S2 are connected in series with the signal line 125, and the gate electrodes of the first and second switching thin film transistors T _S1 and T _S2 are respectively the scan line 135. ) A gate electrode of the first and the second driving thin film transistor (T _D1, T _D2) is connected to one electrode of the storage capacitor (C _ST), another electrode of the storage capacitor (C _ST) is connected to the power line (145). The second driving thin film transistor T _{D2 is} connected to the organic light emitting diode D _EL to control an electric current supply from the power line 145 to implement an image.

The first and second switching thin film transistors T _S1 and T _S2 and the first and second driving thin film transistors T _D1 and T _D2 both use P-type transistors.

Referring to the operation of each device, when the scan line 135 is selected and the first and second switching thin film transistors T _S1 and T _S2 are turned on, a data signal is input to the signal line 125 so that the first and second driving thin film transistors are operated. The gate electrode of (T _D1 , T _D2 ) and one electrode of the storage capacitor C _ST are charged. Since the amount of the ON current varies depending on the charged data signal, the second driving thin film transistor T _D2 may control the amount of current supplied from the power line 145.

The precharge part of FIG. 5B is connected to the first end 125a of the signal line 125, and the current amplifier of FIG. 5C is connected to the second end 125b of the signal line 125.

The precharge unit of FIG. 5B includes first and second precharge transistors T _P1 and T _P2 of P type connected in series with the high voltage source VDD. The precharge signal ENA_PRE is input to the gate electrode of the second precharge transistor T _P2 to supply the precharge current I _PRE to the signal line 125 of FIG. 5A during the precharge period t2 of FIG. 4. . Here, the first and second precharge transistors T _P1 and T _P2 may have a large W / L ratio so that a high current flows several to several tens of times larger than the current output from the integrated circuit of the driving circuit unit.

The current amplifier of FIG. 5C includes a current amplifier 165, first and second switches S ₁ and S ₂ , and a current source 185.

The first switch S ₁ is opened and closed according to the precharge signal ENA_PRE, and the second switch S2 is opened and closed according to the half precharge signal ENA_PRE_BAR having a polarity opposite to that of the precharge signal ENA_PRE. Therefore, the amplification current I _CA flows through the current amplifier 165 in the precharge section (t2 in FIG. 4), and in the first section (t1 in FIG. 4) through which the data signal (VIDEO in FIG. 4) is input. It flows without passing through the current amplifier 165.

The current amplifier 165 amplifies the input current I _IN to output the output current I _OUT , and is connected to an external high voltage source VDD.

The current source 185 serves as an integrated circuit IC of the driving circuit unit 180 of FIG. 3 to supply current to the current amplifier unit.

When the precharge signal ENA_PRE is turned on, the amplifying current I _CA flowing through the current amplifier becomes a high current several to several tens of times larger than the current output from the integrated circuit of the driving circuit unit, and the first switching thin film transistor of the pixel region ( The relationship between the pixel current I _PIX flowing through T _S1 of FIG. 5A and the precharge current I _{PRE of the} precharge part is (I _PRE + I _PIX = I _CA ) or (I _PRE = I _CA ).

FIG. 5D is a circuit diagram illustrating an example of the current amplifier of FIG. 5C.

As shown in FIG. 5D, the current amplifier may include first to fourth amplifying transistors T _CA1 , T _CA2 , T _CA3 , and T _CA4 .

The first and second amplifying transistors T _CA1 and T _CA2 are P type, and the third and fourth amplifying transistors T _CA3 and T _CA4 are N type.

The first and second amplifying transistors T _CA1 and T _CA2 are connected in parallel to the high voltage source VDD with gate electrodes connected to each other. The third amplifying transistor T _CA3 is connected in series to the second amplifying transistor T _CA2 , and the gate electrodes of the third and fourth amplifying transistors T _CA3 and T _CA4 are connected to each other.

Since the current amplifier amplifies the input current I _IN to output the output current I _OUT , the current I ₁ flowing through the second amplifying transistor T _CA2 is the input current I _IN and the output current I _OUT. ) And the W / L ratios of the first to fourth amplifying transistors T _CA1 , T _CA2 , T _CA3 , T _CA4 are set to have a relationship between (I _IN ≦ I ₁ ≦ I _OUT ).

As described above, in the organic light emitting diode according to the third exemplary embodiment of the present invention, the integrated circuit of the driving circuit part is connected to the signal line for a predetermined period (pre-charging period; t2) before the data signal is input using the precharge part and the current amplifier. A high current flows several to several tens of times larger than the current output from, making the potential of the signal line near the desired voltage. Accordingly, the time for charging the data signal can be shortened.

On the other hand, even when the precharge unit is not used and only the current amplifier is used, the time that the data signal is transmitted to the driving thin film transistor by flowing the amplified current through the signal line before the data signal is input so that the signal line has a value near a desired voltage. Can be shortened.

FIG. 6A is a circuit diagram of a current amplifier connected to one signal line of an organic light emitting diode according to a fourth embodiment of the present invention, and FIG. 6B is a detailed circuit diagram of the current amplifier of FIG. 6A.

The pixel region and the precharge unit of the organic light emitting panel connected to one signal line of the organic light emitting device according to the fourth embodiment of the present invention, the organic field according to the third embodiment of the present invention shown in Figures 5a and 5b The pixel region and the precharge unit of the organic light emitting panel connected to one signal line of the light emitting device may be applied.

The current amplifier of FIG. 6A includes a current amplifier 265 and a current source 285.

The current amplifier 265 amplifies the input current I _IN according to the precharge signal ENA_PRE to output the output current I _OUT , and is connected to an external high voltage source VDD.

The current source 285 serves as an integrated circuit IC of the driving circuit unit 180 of FIG. 3 to supply current to the current amplifier unit.

When the precharge signal ENA_PRE is turned on, the amplifying current I _CA flowing through the current amplifier becomes a high current several to several tens of times larger than the current output from the integrated circuit of the driving circuit unit, and the first switching thin film transistor of the pixel region ( It has a relationship between the pixel current I _PIX flowing through T _S1 of FIG. 5A and the precharge current I _{PRE of the} precharge part and (I _PRE + I _PIX = I _CA ).

6B is a circuit diagram illustrating an example of the current amplifier of FIG. 6A.

As shown in FIG. 6B, the current amplifier may include first to fifth amplifying transistors T _CA1 , T _CA2 , T _CA3 , T _CA4 , and T _CA5 .

Here, the first and second amplifying transistors T _CA1 and T _CA2 are P type, and the third to fifth amplifying transistors T _CA3 , T _CA4 and T _CA5 are N type.

The first and second amplifying transistors T _CA1 and T _CA2 are connected in parallel to the high voltage source VDD with gate electrodes connected to each other. The third amplifying transistor T _CA3 is connected in series to the second amplifying transistor T _CA2 , and the gate electrodes of the third to fifth amplifying transistors T _CA3 , T _CA4 , and T _CA5 are connected to each other.

The first switch S ₁ is disposed between the fourth and fifth amplifying transistors T _CA4 and T _CA5 to open and close according to the precharge signal ENA_PRE.

The current amplifier amplifies the input current (I _IN ) and outputs the output current (I _OUT ). The current (I ₁ ) flowing through the input current (I _IN ), the second amplifying transistor (T _CA2 ), and the fourth amplifying transistor ( The current I ₂ flowing through T _CA4 , the output current I _OUT , the pixel current I _PIX flowing through the first switching thin film transistor T _{S1 in} FIG. 5A, and the precharge current I _{PRE of the} precharge part W / L ratio of the first to fifth amplifying transistors T _CA1 , T _CA2 , T _CA3 , T _CA4 , T _CA5 so as to have a relationship of (I _IN ≤ I ₁ ≤ I ₂ = I _PRE , I _OUT = I _PIX ) By designing it is possible.

As described above, in the organic light emitting diode according to the fourth exemplary embodiment of the present invention, the integrated circuit of the driving circuit part is connected to the signal line for a predetermined period (pre-charging period; t2) before the data signal is input using the precharge part and the current amplifier. A high current flows several to several tens of times larger than the current output from, making the potential of the signal line near the desired voltage. Accordingly, the time for charging the data signal can be shortened.

On the other hand, even when the precharge unit is not used and only the current amplifier is used, the time that the data signal is transmitted to the driving thin film transistor by flowing the amplified current through the signal line before the data signal is input so that the signal line has a value near a desired voltage. Can be shortened.

7A, 7B, and 7C are circuit diagrams of a pixel region, a precharge unit, and a current amplifier of an organic light emitting panel connected to one signal line of an organic light emitting diode according to a fifth embodiment of the present invention, respectively.

As shown in FIG. 7A, in the pixel area P defined by the signal line 325 and the scan line 335, first and second switching thin film transistors T _S1 and T _S2 , and first and second driving thin film transistors ( T _D1 , T _D2 ), a storage capacitor C _ST , and an organic light emitting diode D _EL are disposed.

Here, the first and second switching thin film transistors T _S1 and T _S2 are P-type, and the first and second driving thin film transistors T _D1 and T _D2 and the storage capacitor C _ST are N-type.

In more detail, the first and second switching thin film transistors T _S1 and T _S2 are connected in series with the signal line 325, and the gate electrodes of the first and second switching thin film transistors T _S1 and T _S2 are respectively the scan line 335. ) A gate electrode of the first and the second driving thin film transistor (T _D1, T _D2) is connected to one electrode of the storage capacitor (C _ST), another electrode of the storage capacitor (C _ST) is connected to the power line 345. The second driving thin film transistor T _{D2 is} connected to the organic light emitting diode D _EL to control the supply of current from the power line 345 to implement an image.

Referring to the operation of each device, when the scan line 335 is selected and the first and second switching thin film transistors T _S1 and T _S2 are turned on, a data signal is input to the signal line 325 so that the first and second driving thin film transistors are turned on. The gate electrode of (T _D1 , T _D2 ) and one electrode of the storage capacitor C _ST are charged. Since the amount of the ON current varies according to the charged data signal, the second driving thin film transistor T _D2 may control the amount of current supplied from the power line 345.

The precharge part of FIG. 7B is connected to the first end 325a of the signal line 325, and the current amplifier of FIG. 7C is connected to the second end 325b of the signal line 325.

The precharge unit of FIG. 7B includes first and second precharge transistors T _P1 and T _P2 connected in series to the low voltage source VSS.

Here, the first precharge transistor T _P1 is of N type, while the second precharge transistor T _P2 is of P type.

The precharge signal ENA_PRE is input to the gate electrode of the second precharge transistor T _P2 to supply the precharge current I _PRE to the signal line 325 of FIG. 7A during the precharge section t2 of FIG. 4A. . Here, the first and second precharge transistors T _P1 and T _P2 may have a large W / L ratio so that a high current flows several to several tens of times larger than the current output from the integrated circuit of the driving circuit unit.

The current amplifier of FIG. 7C includes a current amplifier 365, first and second switches S ₁ and S ₂ , and a current source 385.

The first switch S ₁ is opened and closed according to the precharge signal ENA_PRE, and the second switch S2 is opened and closed according to the half precharge signal ENA_PRE_BAR having a polarity opposite to that of the precharge signal ENA_PRE. Therefore, the amplification current I _CA flows through the current amplifier 365 in the precharge section (t2 in FIG. 4), and in the first section (t1 in FIG. 4) through which the data signal (VIDEO in FIG. 4) is input. Flow without passing through the current amplifier (365).

The current amplifier 365 amplifies the input current I _IN and outputs the output current I _OUT .

The current source 385 serves as an integrated circuit IC of the driving circuit unit 180 of FIG. 3 to supply current to the current amplifier unit.

The amplification current I _CA flowing through the current amplifier is in the opposite direction to that of the third embodiment, and when the precharge signal ENA_PRE is turned on, a high current several to tens of times larger than the current output from the integrated circuit of the driving circuit unit. The pixel current I _PIX flowing through the first switching thin film transistor T _S1 in the pixel region and the precharge current I _PRE and (I _PRE + I _PIX = I _CA ) of the _precharge unit or ( I _PRE = I _CA ).

As described above, in the organic light emitting diode according to the fifth exemplary embodiment of the present invention, the integrated circuit of the driving circuit part is connected to the signal line for a predetermined period (precharge period; t2) before the data signal is input using the precharge part and the current amplifier. A high current flows several to several tens of times larger than the current output from, making the potential of the signal line near the desired voltage. Accordingly, the time for charging the data signal can be shortened.

On the other hand, even when the precharge unit is not used and only the current amplifier is used, the time that the data signal is transmitted to the driving thin film transistor by flowing the amplified current through the signal line before the data signal is input so that the signal line has a value near a desired voltage. Can be shortened.

FIG. 8A is a circuit diagram of a current amplifier connected to one signal line of an organic light emitting diode according to a sixth embodiment of the present invention, and FIG. 8B is a detailed circuit diagram of the current amplifier of FIG. 8A.

The pixel region and the precharge unit of the organic light emitting panel connected to one signal line of the organic light emitting device according to the sixth embodiment of the present invention, the organic field according to the fifth embodiment of the present invention shown in Figures 7a and 7b The pixel region and the precharge unit of the organic light emitting panel connected to one signal line of the light emitting device may be applied.

The current amplifier of FIG. 8A includes a current amplifier 465 and a current source 485.

The current amplifier 465 amplifies the input current I _IN according to the precharge signal ENA_PRE and outputs the output current I _OUT .

The current source 485 serves to supply current to the current amplifier as an integrated circuit IC of the driving circuit unit 180 of FIG. 3.

When the precharge signal ENA_PRE is turned on, the amplifying current I _CA flowing through the current amplifier becomes a high current several to several tens of times larger than the current output from the integrated circuit of the driving circuit unit, and the first switching thin film transistor of the pixel region ( It has a relationship between the pixel current I _PIX flowing through T _S1 of FIG. 7A and the precharge current I _{PRE of the} precharge part and (I _PRE + I _PIX = I _CA ).

8B is a circuit diagram illustrating an example of the current amplifier of FIG. 8A.

As shown in FIG. 8B, the current amplifier may include first to fifth amplifying transistors T _CA1 , T _CA2 , T _CA3 , T _CA4 , and T _CA5 .

Here, the first and second amplification transistors T _CA1 and T _CA2 are N type, and the third to fifth amplification transistors T _CA3 , T _CA4 and T _CA5 are P type.

The first and second amplifying transistors T _CA1 and T _CA2 are connected in parallel to the low voltage source VSS2 with gate electrodes connected to each other. The third amplifying transistor T _CA3 is connected in series to the second amplifying transistor T _CA2 , and the gate electrodes of the third to fifth amplifying transistors T _CA3 , T _CA4 , and T _CA5 are connected to each other.

The first switch S ₁ is disposed between the fourth and fifth amplifying transistors T _CA4 and T _CA5 to open and close according to the precharge signal ENA_PRE.

The current amplifier amplifies the input current (I _IN ) and outputs the output current (I _OUT ). The current (I ₁ ) flowing through the input current (I _IN ), the second amplifying transistor (T _CA2 ), and the fourth amplifying transistor ( The current I ₂ flowing through T _CA4 , the output current I _OUT , the pixel current I _PIX flowing through the first switching thin film transistor (T _{S1 in} FIG. 7A), and the precharge current I _{PRE of the} precharge part are W / I of the first to fifth amplifying transistors T _CA1 , T _CA2 , T _CA3 , T _CA4 , T _CA5 to have a relationship of (I _IN ?? I ₁ ?? I ₂ = I _PRE , I _OUT = I _PIX ) By designing the L ratio, current amplification is possible.

As described above, in the organic light emitting diode according to the sixth exemplary embodiment of the present invention, the integrated circuit of the driving circuit part is connected to the signal line for a predetermined period (precharge period; t2) before the data signal is input using the precharge part and the current amplifier. A high current flows several to several tens of times larger than the current output from, making the potential of the signal line near the desired voltage. Accordingly, the time for charging the data signal can be shortened.

On the other hand, even when the precharge unit is not used and only the current amplifier is used, the time that the data signal is transmitted to the driving thin film transistor by flowing the amplified current through the signal line before the data signal is input so that the signal line has a value near a desired voltage. Can be shortened.

In the organic light emitting display device according to the first to sixth embodiments of the present invention, the precharge unit and the current amplifier may be configured as an external circuit independent of the organic light emitting panel, or the pixel area of the organic light emitting panel The switching thin film transistors and the driving thin film transistors formed in the organic light emitting panel may be incorporated.

The organic light emitting display device and its driving method according to the present invention are not limited to the above embodiments, and various changes and modifications are made by those skilled in the art without departing from the spirit of the present invention. It is evident that this is possible, and it is apparent from the appended claims that these changes and variations fall within the invention.

As described above, according to the organic light emitting diode according to the present invention and the driving method thereof, four thin film transistors are provided in one pixel region, and a precharge part and a current amplifier part which can enlarge a driving current source are further provided. By including the signal, the time for charging and discharging the signal to the thin film transistor in the pixel region can be shortened.

In addition, the current driving method prevents the uniformity problem caused by the change of the threshold voltage (Vth) of the thin film transistor.

1 is a circuit diagram showing the configuration of one pixel region of a general active matrix organic electroluminescent device.

2 is a block diagram showing the configuration of a conventional organic light emitting display device.

3 is a block diagram showing the configuration of an organic light emitting display device according to a first embodiment of the present invention;

4 is a timing diagram showing a drive signal of an organic light emitting display device according to a second embodiment of the present invention;

5A is a circuit diagram of a pixel area of an organic light emitting panel connected to one signal line of an organic light emitting display device according to a third embodiment of the present invention;

5B is a circuit diagram of a precharge unit connected to one signal line of the organic light emitting display device according to the third embodiment of the present invention.

5C is a circuit diagram of a current amplifier connected to one signal line of an organic light emitting display device according to a third embodiment of the present invention;

5D is a detailed circuit diagram of the current amplifier of FIG. 5C.

6A is a circuit diagram of a current amplifier connected to one signal line of an organic light emitting display device according to a fourth embodiment of the present invention;

6B is a detailed circuit diagram of the current amplifier of FIG. 6A.

7A is a circuit diagram of a pixel area of an organic light emitting panel connected to one signal line of an organic light emitting display device according to a fifth embodiment of the present invention;

7B is a circuit diagram of a precharge unit connected to one signal line of the organic light emitting display device according to the fifth embodiment of the present invention.

7C is a circuit diagram of a current amplifier connected to one signal line of an organic light emitting display device according to a fifth embodiment of the present invention;

8A is a circuit diagram of a current amplifier connected to one signal line of an organic light emitting display device according to a sixth embodiment of the present invention;

FIG. 8B is a detailed circuit diagram of the current amplifier of FIG. 8A. FIG.

<Description of the symbols for the main parts of the drawings>

110: organic light emitting panel 120: signal driver

130: scan driver 140: control unit

150: precharge unit 160: current amplifier

180: drive circuit

Claims (29)

An organic light emitting panel including a signal line to which a data signal is input, and a scanning line crossing the signal line to define a pixel area; A current amplifier connected to one end of the signal line to supply an amplified current amplified of the input current to the signal line before the data signal is input; Organic electroluminescent device comprising a. The method of claim 1, And a precharge unit connected to the other end of the signal line to supply a precharge current to the signal line. The method of claim 2, And a driving circuit unit for outputting the data signal and the input current of the current amplifier. The method of claim 3, wherein The precharge unit includes first and second precharge transistors each including a gate electrode, a source electrode, and a drain electrode, wherein the source electrode of the first precharge transistor is connected to a high voltage source VDD, and the first precharge transistor is connected to the first precharge transistor. The gate electrode of the charge transistor is connected to the drain electrode of the first precharge transistor, the drain electrode of the first precharge transistor is connected to the source electrode of the second precharge transistor, and the gate of the second precharge transistor. The precharge signal is turned on for a predetermined time before the data signal is input, and the drain electrode of the second precharge transistor is connected to the signal line. The method of claim 4, wherein The organic light emitting panel includes first and second switching thin film transistors connected to the signal line and the scan line, first and second driving thin film transistors, storage capacitors, and the second driving thin film transistor connected to the second switching thin film transistor. And an organic light emitting diode that receives the power through the power line for supplying power and the second driving thin film transistor. The method of claim 5, And the current amplifier includes first and second switches connected in parallel to the signal line, a current amplifier connected to the first switch, and a current source connected to the current amplifier and the second switch. The method of claim 6, And the first switch is opened and closed according to the precharge signal, and the second switch is opened and closed according to a half precharge signal having a polarity opposite to that of the precharge signal. The method of claim 7, wherein And when the precharge signal is turned on, the amplifying current is equal to the precharge current or the sum of the precharge current and the pixel current flowing through the first switching thin film transistor. The method of claim 8, The current amplifier includes first to fourth amplifying transistors including a gate electrode, a source electrode, and a drain electrode, respectively, and source electrodes of the first and second amplifying transistors are connected to a high voltage source (VDD), and the first amplification transistor. A drain electrode of the transistor is connected to the gate electrodes of the first and second amplifying transistors and the current source, and a source electrode of the third amplifying transistor is the drain electrode of the second amplifying transistor and the gate electrode of the third and fourth amplifying transistors. And a drain electrode of the third and fourth amplifying transistors is connected to a low voltage source (VSS), and a source electrode of the fourth amplifying transistor is connected to the first switch. The method of claim 9, The first to fourth amplification such that a current flowing through the second and third amplifying transistors is greater than a current flowing through the first amplifying transistor, and a current flowing through the fourth amplifying transistor is greater than a current flowing through the second and third amplifying transistors. An organic light emitting device in which the W / L ratio of a transistor is designed. The method of claim 5, And the current amplifier comprises a current amplifier connected to the signal line, and a current source connected to the current amplifier. The method of claim 11, The current amplifier includes first to fifth amplifying transistors including a gate electrode, a source electrode, and a drain electrode and a first switch, respectively, and source electrodes of the first and second amplifying transistors are connected to a high voltage source (VDD), The drain electrode of the first amplifying transistor is connected to the gate electrodes of the first and second amplifying transistors and the current source, and the drain electrode of the third amplifying transistor is the drain electrode of the second amplifying transistor and the third to fifth amplification transistors. A gate electrode of the transistor, a source electrode of the third to fifth amplifying transistors is connected to a low voltage source VSS, and both ends of the first switch are respectively connected to drain electrodes of the fourth and fifth amplifying transistors, The drain electrode of the fifth amplifying transistor is connected to the signal line. The method of claim 12, The first switch is an organic light emitting device that is opened and closed in accordance with the precharge signal. The method of claim 13, And when the precharge signal is turned on, the amplification current is equal to the sum of the precharge current and the pixel current flowing through the first switching thin film transistor. The method of claim 14, The current flowing through the second and third amplifying transistors is greater than the current flowing through the first amplifying transistor, and the current flowing through the fourth amplifying transistor is greater than the current flowing through the second and third amplifying transistors. And the W / L ratio of the first to fifth amplifying transistors is designed such that the current flowing is equal to the precharge current and the current flowing through the fifth amplifying transistor is equal to the pixel current. The method of claim 3, wherein The precharge unit includes first and second precharge transistors each including a gate electrode, a source electrode, and a drain electrode, wherein the source electrode of the first precharge transistor is connected to a low voltage source VSS, and the first precharge transistor is connected to the first precharge transistor. The gate electrode of the charge transistor is connected to the drain electrode of the first precharge transistor, the drain electrode of the first precharge transistor is connected to the drain electrode of the second precharge transistor, and the gate of the second precharge transistor. The precharge signal is turned on for a predetermined time before the data signal is input, and the source electrode of the second precharge transistor is connected to the signal line. The method of claim 16, The organic light emitting panel includes first and second switching thin film transistors connected to the signal line and the scan line, first and second driving thin film transistors, storage capacitors, and the second driving thin film transistor connected to the second switching thin film transistor. And an organic light emitting diode that receives the power through the power line for supplying power and the second driving thin film transistor. The method of claim 17, And the current amplifier includes first and second switches connected in parallel to the signal line, a current amplifier connected to the first switch, and a current source connected to the current amplifier and the second switch. The method of claim 18, And the first switch is opened and closed according to the precharge signal, and the second switch is opened and closed according to a half precharge signal having a polarity opposite to that of the precharge signal. The method of claim 19, And when the precharge signal is turned on, the amplifying current is equal to the precharge current or the sum of the precharge current and the pixel current flowing through the first switching thin film transistor. The method of claim 17, And the current amplifier comprises a current amplifier connected to the signal line, and a current source connected to the current amplifier. The method of claim 21, The current amplifier includes first to fifth amplifying transistors including a gate electrode, a source electrode, and a drain electrode and a first switch, respectively, and source electrodes of the first and second amplifying transistors are connected to a low voltage source (VSS), The drain electrode of the first amplifying transistor is connected to the gate electrodes of the first and second amplifying transistors and the current source, and the drain electrode of the third amplifying transistor is the drain electrode of the second amplifying transistor and the third to fifth amplification transistors. A gate electrode of the transistor, a source electrode of the third to fifth amplifying transistors is connected to a high voltage source VDD, and both ends of the first switch are respectively connected to drain electrodes of the fourth and fifth amplifying transistors, The drain electrode of the fifth amplifying transistor is connected to the signal line. The method of claim 22, The first switch is an organic light emitting device that is opened and closed in accordance with the precharge signal. The method of claim 23, And when the precharge signal is turned on, the amplification current is equal to the sum of the precharge current and the pixel current flowing through the first switching thin film transistor. The method of claim 24, The current flowing through the second and third amplifying transistors is greater than the current flowing through the first amplifying transistor, and the current flowing through the fourth amplifying transistor is greater than the current flowing through the second and third amplifying transistors. And the W / L ratio of the first to fifth amplifying transistors is designed such that the current flowing is equal to the precharge current and the current flowing through the fifth amplifying transistor is equal to the pixel current. The method according to any one of claims 10, 15, 20, 25, The current amplifier and the precharge unit is an organic light emitting device built in the organic field panel. Selecting a scanning line of the organic light emitting panel to input a gate signal; Inputting a data signal to a signal line defining a pixel area crossing the scan line; Inputting an amplifying current to the signal line before the data signal is input such that the signal line has a potential close to the data signal Method of driving an organic light emitting device comprising a. The method of claim 27, And the amplifying current is input by a precharge unit and a current amplifier connected to the signal line. The method of claim 28, The precharge unit and the current amplifier unit is a method of driving an organic light emitting device built in the organic light emitting panel.