KR20040093504A - Active current source, display device having the same, and apparatus for driving thereof - Google Patents

Abstract

PURPOSE: An active current source, a display device provided with the same and a driving apparatus for the same are provided to charge the parasitic capacitor formed on the load by adding the capacitor to the current source. CONSTITUTION: An active current source for supplying the bias current to the load includes a current mirror(110) and a current controller(120). The current mirror(110) is connected to the power voltage to output the bias current proportional to the control signal in response to the apply of the predetermined control signal. And, the current controller(120) is charged to a predetermined level by receiving the input voltage and outputs the control signal to the current mirror(110) so as to control the output of the bias current based on the input voltage and the charge voltage in response to the variation of the input voltage.

Description

ACTIVE CURRENT SOURCE, DISPLAY DEVICE HAVING THE SAME, AND APPARATUS FOR DRIVING THEREOF}

The present invention relates to an active current source, a display device having the same, and a driving device thereof, and more particularly, to an active current source having a pre-charging function, an organic light emitting display device having the same, and a driving device thereof.

The most commonly used display device is a cathode ray tube (CRT), and the ratio of liquid crystal display devices (hereinafter referred to as LCDs) for computers is gradually increasing. However, CRTs are too heavy and bulky, LCDs are not bright, they cannot be seen from the side, and their efficiency is low.

As a result, many people are currently working to develop cheaper, more efficient, thinner, and lighter display devices, and one of the things that is attracting attention as such a next-generation display device is organic light emitting device (OLED). )to be.

These OLEDs use ElectroLuminescence (EL) which emits light when electricity is applied to specific organic materials or polymers, so that OLEDs can be made thinner, cheaper and easier to produce, and have a wider viewing angle than LCDs. It has the advantage of emitting bright light, and research on this is being heated hot all over the world.

The organic light emitting display device includes an active-matrix type organic light emitting display device and a passive-matrix type organic field according to the presence of a switching element provided in a unit cell. It is divided into a light emitting display device.

The driving waveform for driving the passive-matrix organic light emitting display device is largely divided into a pre-charging period and a display period. The pre-charging interval is needed to charge the parasitic capacitors of the unselected lines. The parasitic capacitors have a considerably large capacitance of several to several hundreds of kilowatts due to the characteristics of the organic EL device manufactured in a thin form.

In order to charge the parasitic capacitor, a parasitic capacitor is charged by using an external voltage. However, this requires not only a separate external power source for performing pre-charging but also requires external devices for generating the power source.

Accordingly, the present invention has been made in an effort to solve such a conventional problem, and an object of the present invention is to provide an active current source for precharging a parasitic capacitor of a load.

In addition, another object of the present invention is to provide a display device for pre-charging a parasitic capacitor of a panel having the active current source described above.

Further, another object of the present invention is to provide a driving device for a display device having the active current source described above.

1 is a circuit diagram illustrating an active current source according to an embodiment of the present invention.

FIG. 2 is a waveform diagram illustrating the bias current of FIG. 1 described above.

3 is a circuit diagram illustrating an active current source according to another embodiment of the present invention.

4 is a diagram for describing an organic light emitting display device according to an embodiment of the present invention.

FIG. 5 is a diagram for explaining the data driver of FIG. 4.

6 is a diagram for describing an organic light emitting display device according to another exemplary embodiment of the present invention.

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

110, 210: current mirror 120, 220: current control unit

122, 222: switching section 124: pull-down section

224: pull-up unit 310, 410: timing control unit

320, 420: data driver 322: shift register

324: latch 326: digital-to-analog converter

328: unit current source 330, 430: scan driver

340, 450: organic light emitting panel 440: power supply

An active current source according to one aspect for realizing the object of the present invention, in the active current source for supplying a bias current to the load, one end is connected to the power supply voltage, and a constant control signal is applied to the control signal A current mirror for outputting a proportional bias current; And a current controller configured to receive an input voltage and charge the battery at a predetermined level, and output the control signal to the current mirror to control the output of the bias current based on the input voltage and the charging voltage as the input voltage is changed. Is done.

In addition, a display device according to one aspect for realizing the above object of the present invention includes a data driver for outputting a bias current corresponding to image data provided from the outside; A scan driver to output a scan signal based on a timing signal provided from the outside; And an organic light emitting panel that emits light according to the bias current as the scan signal is provided, wherein the bias current is overshooted as the image data is varied for gray scale display, and the overshoot bias The current is characterized by pre-charging the parasitic capacitor of the organic electroluminescent panel.

In addition, a driving apparatus of a display device according to another aspect of the present invention is to provide a data line for transmitting a data signal, a scan line for transmitting a scan signal, and the data line and a scan line. A drive device for a display device comprising an organic EL cell arranged in an area surrounded by a shift device, comprising: a shift register for sequentially shifting image data supplied from outside in synchronization with a shift clock; A latch for storing the shifted image data; A digital analog converting unit converting the analog gray voltage corresponding to the stored image data; And an active current source configured to charge a predetermined level as the converted analog gray voltage is applied, and output a bias current generated to the data line based on the input voltage and the charging voltage as the input voltage is changed. .

In addition, a driving device of a display device according to another aspect for realizing the above object of the present invention is a driving device of a display device which inputs a gray level display signal to drive a data line, wherein the gray level display signal A reference current generator configured to input a reference current to generate a reference current including an initial pre-charging current corresponding to the gradation variation; And a parasitic capacitor of a pixel connected between the reference current generator and the data line, generating a drive current mirrored by the reference current, and connected to the data line by an initial pre-charging component of the drive current. It comprises a charging current mirror.

According to such an active current source, a display device having the same, and a driving device thereof, by adding a capacitor to a current source for outputting a bias current, parasitic capacitors provided in the output load can be pre-charged in the pre-charging section before the display section. .

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention.

FIG. 1 is a circuit diagram for explaining an active current source according to an embodiment of the present invention. In particular, FIG.

Referring to FIG. 1, an active current source according to an embodiment of the present invention includes a current mirror 110 and a current controller 120 for adjusting a bias current I ′ output from the current mirror 110. do.

The current mirror 110 has one end connected to the first power supply voltage VDD, and outputs a bias current I 'proportional to the control signal as a constant control signal is applied from the current control unit 120.

The current controller 120 includes a switching unit 122 and a pull-down unit 124. The current control unit 120 is provided with a reference level Vref of a predetermined level to charge a predetermined level, and as the reference voltage Vref is changed, the reference voltage ( The control signal is output to the current mirror 110 to control the output of the bias current I 'based on Vref) and the charging voltage.

In detail, the switching unit 122 includes an operational amplifier 122A having a first polarity terminal (+) connected to the reference voltage Vref, and a second polarity terminal (−) connected to the pull-down unit 124; A gate is connected to an output terminal of the operational amplifier 122A, a drain is connected to the current mirror 110, and a source is formed of a P-type transistor Q13 connected to the pull-down unit 124. Vref) on / off switching.

One end of the pull-down unit 124 is connected to the switching unit 122, and the other end is composed of a resistor (R11) and a capacitor (C11) connected in parallel to the resistor (R11), The control signal is provided to the current mirror 110 to control the output of the bias current I 'in response to a switching operation.

Next, the operation will be described by taking an example of the active current source including the PMOS implemented in the data driving device of the display device, preferably the data driving device of the organic light emitting display device. The operation in the case where a constant current is applied to the pixel to show a constant gray scale is as follows.

One end of the resistor R11 connected to the second polarity terminal (−) of the operational amplifier 122A is connected to the second power supply voltage VSS, and the other end thereof is always fixed to the reference voltage Vref. The voltage is fixed by the difference between the reference voltage Vref and the second power supply voltage VSS. In addition, due to the difference between the fixed reference voltage Vref and the second power supply voltage VSS, the capacitor C11 connected in parallel to the resistor R11 is always open. As a result, the bias current I 'applied to the pixel is not affected at all.

On the other hand, the operation in the case of changing the current to change the gradation expressed in the pixel is as follows. That is, the reference voltage Vref is changed to a voltage corresponding to a current required to represent a gray level that is changed from the reference voltage before the change. Accordingly, the capacitor C11 connected in parallel to the resistor R11 outputs a constant bias current I 'such as the following Equation 1 while switching from the open state to the closed state.

Here, dV (t) is the difference voltage between the reference voltage before change and the changed reference voltage.

At the same time, resistor R11 and capacitor C11 operate as RC filters. Here, the time constant t of the RC filter satisfies a conditional expression of t = RC. In this case, it is preferable to design an over shoot as shown in FIG. 2 in which the current response of the RC filter 124 is appropriately adjusted by adjusting the capacitance of the capacitor C11.

FIG. 2 is a waveform diagram illustrating the bias current of FIG. 1 described above.

As shown in Fig. 2, the response characteristic of the ideal bias current I output from a conventional active current source has a stepped wave shape. Specifically, a low-level bias current is output in response to the n-th frame, and a high-level bias current is output in response to the n + 1th frame, thereby having a stepped wave shape.

However, the response characteristic of the bias current I 'output from the active current source according to the present invention has a stepped wave shape in which the overshoot is reflected by the RC filter. Specifically, the RC filter outputs a low-level bias current in response to the n-th frame, and rises to a high level in response to the n + 1-th frame and outputs a high-level bias current overshooted to a certain level. do.

That is, the pre-charging function required for driving may be performed by using the amount of current flowing into the organic light emitting display panel during the overshoot during the current response of the RC filter. Here, the amount of overshoot current can be adjusted by changing the capacitance of the capacitor C11 provided in the RC filter 124 of the active current source.

Accordingly, the active current source according to the present invention can perform not only an operation as a current source necessary for driving the organic light emitting display device, but also a pre-charging function required for driving the passive-matrix type organic light emitting display device. .

For example, when the active current source is employed as a driving device of a display device which inputs a gray scale display signal to drive a data line, it is as follows.

The current control unit 120 is a kind of reference current generation unit that inputs the gray level display signal to generate a reference current including an initial pre-charging current corresponding to the gray level variation.

A current mirror 110 is connected between the current control unit 120 and the data line, generates a drive current mirrored by the reference current, and is connected to each of the data lines by an initial pre-charging component of the drive current. The parasitic capacitor of the pixel is pre-charged.

FIG. 3 is a circuit diagram illustrating an active current source according to another embodiment of the present invention, and particularly illustrates an active current source consisting of NMOS.

Referring to FIG. 3, an active current source according to another embodiment of the present invention includes a current mirror 210 and a current controller 220 for adjusting a bias current I ′ output from the current mirror 210. do.

One end of the current mirror 210 is connected to a second power supply voltage VSS having a lower level than the first power supply voltage VDD, and is mirrored in proportion to the control signal as a predetermined control signal is applied from the current control unit 220. The bias current I 'is outputted.

The current controller 220 includes a switching unit 222 and a pull-up unit 224, and receives the input voltage to charge a predetermined level, and as the input voltage is varied, the bias current (based on the input voltage and the charging voltage) The control signal is output to the current mirror 210 so as to control the output of I ').

In detail, the switching unit 222 may include an operational amplifier 222A having a first polarity terminal (+) connected to the reference voltage Vref, and a second polarity terminal (−) connected to the pull-up unit 224. A gate is connected to an output terminal of the operational amplifier 222A, a drain is connected to the current mirror 210, and a source is formed of an N-type transistor Q23 connected to the pull-up unit 224. Vref) on / off switching.

The pull-up unit 224 has one end connected to the switching unit 222, the other end is composed of a resistor (R21) and the capacitor (C21) connected in parallel to the resistor (R21), The control signal is provided to the current mirror 210 to control the output of the bias current I 'in response to a switching operation.

Next, an operation will be described using an active current source including the NMOS as an example implemented in a data driving device of a display device, preferably a data driving device of an organic light emitting display device. The operation in the case where a constant current is applied to the pixel to show a constant gray scale is as follows.

One end of the resistor R21 connected to the second polarity terminal (−) of the operational amplifier 222A is connected to the first power supply voltage VDD, and the other end thereof is always fixed to the reference voltage Vref. The voltage is fixed by the difference between the first power supply voltage VDD and the reference voltage Vref. In addition, due to the difference between the fixed first power supply voltage VDD and the reference voltage Vref, the capacitor C21 connected in parallel to the resistor R21 is always open. As a result, the bias current I 'applied to the pixel is not affected at all.

On the other hand, the operation in the case of changing the current to change the gradation expressed in the pixel is as follows. That is, the reference voltage Vref is changed to a voltage corresponding to a current required to represent a gray level that is changed from the reference voltage before the change. Accordingly, the capacitor C21 connected in parallel to the resistor R21 outputs a constant current as shown in Equation 1 while switching from the open state to the closed state.

At the same time, resistor R21 and capacitor C21 operate as RC filters. Here, the time constant t of the RC filter satisfies a conditional expression of t = RC. In this case, it is preferable to design the current response of the RC filter 224 to have an over shoot as shown in FIG. 2 by appropriately adjusting the capacitance of the capacitor C21.

FIG. 4 is a diagram for describing an organic light emitting display device according to an embodiment of the present invention. In particular, FIG. 4 illustrates a passive matrix matrix organic light emitting display device.

Referring to FIG. 4, an organic light emitting display device according to an exemplary embodiment of the present invention includes a timing controller 310, a data driver 320 that receives an image signal and outputs a data signal, and receives a timing signal to scan. A scan driver 330 for outputting a signal and an organic light emitting panel 340 for emitting light by adjusting the amount of current corresponding to the data signal as the scan signal is provided.

The timing controller 310 receives the first image signals R, G, and B and control signals Vsync and Hsync for controlling the output thereof from an external graphic controller (not shown). Generate the signals TS1 and TS2, output the generated first timing signal TS1 to the data driver 320 together with the second image signals R ′, G ′, and B ′ and generate the generated second timings. The signal TS2 is output to the scan driver 330. The second image signals R ′, G ′, and B ′ may be the same as the first image signals R, G, and B, but are converted to be suitable for display on the organic light emitting panel 340. to be.

The data driver 320 receives the second image signals R ', G', and B 'and the first timing signal TS1 from the timing controller 310 to receive the data signals D1, D2, D3, ..., Dm-1 and Dm) are output to the organic light emitting panel 340.

The scan driver 330 receives the second timing signal TS2 from the timing controller 310 and sequentially receives a plurality of scan signals S1, S2,..., Sn-1, and Sn. 340).

The organic light emitting panel 340 has m data lines DL extending in a vertical direction and arranged in a horizontal direction to transmit data signals, and n scan lines extending in a horizontal direction and arranged in a vertical direction to transfer scan signals. SL and the pixel electrode PE.

In more detail, the pixel electrode PE is formed of an organic EL element EL that performs a kind of diode operation, and is formed in a predetermined region lattice arranged between the data line DL and the scan line SL, and the scan As the scan signal via the line SL is applied, the light emits light in response to the mirrored current input through the data line DL. The organic EL element EL pre-charges a parasitic capacitor CP connected in parallel.

FIG. 5 is a diagram for explaining the data driver of FIG. 4.

4 and 5, the data driver according to the present invention includes a shift register 322, a latch 324, a digital-to-analog converter (DAC) 326, and a unit current source 328.

The shift register 322 stores the image data R ', G', and B 'transmitted from the timing controller 310 while being sequentially shifted in synchronization with the shift clock. At this time, if all data is stored in a certain shift register, a predetermined carry out signal is sent to an adjacent next shift register, and the next shift register operates like the arbitrary shift register.

The digital-to-analog converter 326 receives a data signal stored in the shift register 322 via the latch 324 and converts the data signal into an analog gray level voltage corresponding thereto. That is, the digital-analog converter 326 receives the gray voltage output from the gray voltage generator (not shown) and the data signal output from the shift register 322 to correspond to the data signal stored in the shift register 322. Outputs the analog gradation voltage value. In particular, the digital-analog converter 326 converts image data input from the latch 324 to an analog voltage based on a plurality of gamma reference voltages applied from the outside.

The unit current source 328 applies an analog gray scale voltage output from the digital-analog converter 326 to the data line DL electrically connected to the data driver 320 in line units. Here, the unit current source may be an active current source made of the PMOS shown in FIG. 1 or an active current source made of the NMOS shown in FIG.

In the above, the image data is applied to the unit current source via the shift register, the latch, and the digital-to-analog converter, but various modifications can be made by those skilled in the art. For example, image data may be applied to a unit current source via shift registers, data registers, data latches, and digital-to-analog converters.

Meanwhile, the active-matrix organic light emitting display device is divided into a current mirror type and a current source type according to the structure of unit pixels included in the active-matrix panel.

The current mirror type organic light emitting display device is a method in which a data driver outputs a bias current and emits light in a unit pixel by using a driving current generated by mirroring the bias current.

The current source organic light emitting display device is a method in which a data driver outputs a bias voltage and emits light in a unit pixel by using a driving current according to the bias voltage. In view of this, the active current source according to the present invention will be applied to the current mirror type active-matrix type organic light emitting display device.

Next, the current mirror type active-matrix type organic light emitting display device will be described with reference to the accompanying drawings.

FIG. 6 is a view for explaining an organic light emitting display device according to another embodiment of the present invention. In particular, FIG. 6 illustrates an active-matrix type organic light emitting display device.

Referring to FIG. 6, an organic light emitting display device according to another exemplary embodiment of the present invention includes a timing controller 410, a data driver 420 that receives an image signal and outputs a data signal, and receives a timing signal to receive a scan signal. A scan driver 430 for outputting, a power supply unit 440 for providing a power voltage, and an organic light emitting panel 450 that emits light by adjusting an amount of current corresponding to the data signal as the scan signal is provided It includes.

The timing controller 410 receives the first image signals R, G, and B and control signals Vsync and Hsync controlling the output thereof from an external graphic controller (not shown). Generate the signals TS1 and TS2, output the generated first timing signal TS1 to the data driver 420 together with the second image signals R ′, G ′, and B ′ and generate the generated second timings. The signal TS2 is output to the scan driver 430, and the power voltage control signal 412 is output to the power supply 440.

The data driver 420 receives the second image signals R ', G', and B 'and the first timing signal TS1 from the timing controller 410, and receives the data signals D1, D2, D3, ..., Dm-1, Dm) is output to the organic light emitting panel 450. The data driver 420 is as described with reference to FIG. 5, and the unit current source 328 of FIG. 5 may be an active current source including a PMOS shown in FIG. 1, or an active current source including an NMOS shown in FIG. 3. It may be.

The scan driver 430 receives the second timing signal TS2 from the timing controller 420 and sequentially receives a plurality of scan signals S1, S2,..., Sn-1, and Sn. To 450).

The power supply unit 440 receives the power supply voltage control signal 412 and provides the first power supply voltage VDD to the power supply line VL provided in the organic light emitting panel 450.

The organic light emitting panel 450 includes m data lines DL for transmitting a data signal, m power lines VL for transmitting a first power voltage VDD, and n scan lines SL for transmitting a scan signal. ), A switching element QS and a pixel electrode PE formed between the data line DL and the scan line SL.

In more detail, the switching element QS has a first end connected to the data line DL and a second end connected to the scan line SL to output an output of the data signal in response to the scan signal. On / off control.

The pixel electrode PE includes a current mirror and an organic EL element, and is formed in a predetermined region arranged in a lattice between the data line DL and the scan line SL. The self-emission light is generated in response to a current mirrored from the first power supply voltage VDD by the voltage output through the third stage. In detail, the current mirror has a common gate and a drain is connected between the gate and the drain of the first and second P-type transistors Q31 and Q32 and the first P-type transistor Q31 respectively connected to the power supply line VL. It is composed of the capacitor (C) connected, the voltage is provided through the third stage of the source switching element (QS) of the first P-type transistor (Q31), the mirroring through the source of the second P-type transistor (Q32) One current is provided to the organic EL element EL.

In addition, one end of the organic EL element EL is connected to the source of the second P-type transistor Q32, the other end thereof is connected to the second power supply voltage, and emits light in response to the mirrored current. The second power supply voltage is a voltage having a lower level than the power supply voltage applied to the power supply line, and is preferably a ground potential.

A parasitic capacitor CP connected in parallel with the organic EL element EL is precharged by a voltage mirrored by an input bias current via the switching element QS. That is, the second image signals R ', G', and B 'corresponding to the current frame are converted for the gray level conversion so that the bias current passing through the switching element QS is overshooted so that the mirroring is performed. The parasitic capacitor CP is precharged because the current is also overshooted.

The power line VL may be formed in parallel with the data line DL or may be formed in parallel with the scan line SL. In addition, the first power supply voltage VDD supplied to the power supply line VL is a kind of bias voltage. When the current mirror of the organic light emitting panel 450 is formed of a P type transistor, the organic EL element EL is applied. It is preferable that the voltage is at a higher level than the common voltage (second power supply voltage or ground) connected thereto, and when the current mirror is composed of N type transistors, the common voltage connected to the organic EL element EL (or It is desirable to have a lower level of voltage than ground).

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

As described above, according to the active current source according to the present invention, by adding a capacitor to the current source, the parasitic capacitor formed in the load can be charged. In particular, in the case of the organic light emitting display device, the parasitic capacitor formed in every pixel of the organic light emitting panel can be pre-charged in the pre-charging section disposed before the display section, so that the application of a separate pre-charging voltage can be omitted. have.

Claims (21)

In an active current source that supplies a bias current to a load, A current mirror having one end connected to a power supply voltage and outputting a bias current proportional to the control signal when a constant control signal is applied; And A current controller configured to receive an input voltage and charge a predetermined level, and output a control signal to the current mirror to control the output of the bias current based on the input voltage and the charging voltage as the input voltage is changed. Current source. The active current source of claim 1, wherein the bias current is overshooted as the input voltage varies, and the overshoot biased current pre-charges a parasitic capacitor of the load. The method of claim 1, wherein the current control unit, Switching means for switching on / off based on a variable reference voltage; And And pull-down means for providing said control signal to said current mirror for controlling the output of said bias current in response to a switching operation of said switching means. The method of claim 3, wherein the switching means An operational amplifier having a first polarity terminal connected to the reference voltage and a second polarity terminal connected to the pull-down means; And And a p-type transistor having a gate connected to the output terminal of the operational amplifier, a drain connected to the current mirror, and a source connected to the pull-down means. The method of claim 3, wherein the pull-down means, A resistor having one end connected to the switching means and the other end grounded; And An active current source, characterized in that the RC filter consisting of a capacitor connected in parallel to the resistor. The method of claim 1, wherein the current control unit, Pull-up means for outputting the control signal to control the output of the bias current; And And switching means for providing an output of said control signal on the basis of a variable reference voltage. The method of claim 6, wherein the switching means, An operational amplifier having a first polarity terminal connected to the reference voltage and a second polarity terminal connected to the pull-up means; And And an N-type transistor having a gate connected to the output terminal of the operational amplifier, a drain connected to the current mirror, and a source connected to the pull-down means. The method of claim 6, wherein the pull-up means, A resistor having one end connected to the switching means and the other end connected to a power supply voltage; And An active current source, characterized in that the RC filter consisting of a capacitor connected in parallel to the resistor. A data driver which outputs a bias current corresponding to image data provided from the outside; A scan driver to output a scan signal based on a timing signal provided from the outside; And An organic electroluminescent panel which emits light according to the bias current as the scan signal is provided, And the bias current is overshooted as the image data varies for gray scale display, and the overshoot bias current pre-charges a parasitic capacitor of the organic light emitting panel. The method of claim 9, wherein the data driver, A shift register which sequentially shifts the image data in synchronization with a shift clock; A latch for storing the shifted image data; A digital analog converting unit converting the analog gray voltage corresponding to the stored image data; And An active current source for charging a predetermined level as the converted analog gray voltage is applied and outputting the bias current generated based on the input voltage and the charging voltage to a data line of the organic light emitting panel as the input voltage is changed. Display device comprising a. The method of claim 9, wherein the organic light emitting panel A scan line transferring the scan signal; A data line carrying the bias current; And One end is connected to the data line, the other end comprises an organic light emitting device connected to the scan line, And the bias current pre-charges a parasitic capacitor connected in parallel to the organic light emitting diode. The display device of claim 9, further comprising a power supply voltage supply unit configured to receive a power supply voltage control signal and output a power supply voltage to the organic light emitting panel. The method of claim 12, wherein the organic light emitting panel, A scan line transferring a scan signal; A data line carrying a data signal; A switching device having a first end connected to the data line and a second end connected to the scan line, the switching element configured to turn on / off an output of the data signal in response to the scan signal; And And a pixel electrode formed in a predetermined region lattice arranged between the scan line and the data line and emitting light in response to a current mirrored by a bias current output through the third end of the switching element. The method of claim 13, wherein the pixel electrode, A current mirror having a first end connected to a first power supply voltage and outputting the mirrored current through a third end as the bias current is applied through a second end; And An organic EL element having one end connected to a third end of the current mirror, the other end connected to a second power supply voltage, and emitting light in response to the mirrored current; And the organic EL element pre-charges parasitic capacitors connected in parallel. A drive device for a display device comprising a data line for transmitting a data signal, a scan line for transmitting a scan signal, and an organic EL cell arranged in an area surrounded by the data line and the scan line, A shift register which sequentially shifts image data provided from the outside in synchronization with a shift clock; A latch for storing the shifted image data; A digital analog converting unit converting the analog gray voltage corresponding to the stored image data; And A display device including an active current source configured to charge a predetermined level as the converted analog gray voltage is applied, and output a bias current generated to the data line based on the input voltage and the charging voltage as the input voltage is changed Drive. 16. The display of claim 15, wherein the bias current is overshooted as the analog gradation voltage is varied for gradation display, wherein the overshoot biased current pre-charges a parasitic capacitor of the organic EL cell. Drive of the device. The method of claim 15, wherein the active current source, A current mirror having one end connected to a power supply voltage and outputting a bias current proportional to the control signal when a constant control signal is applied; And And a current controller configured to receive the analog gray voltage and charge a predetermined level, and to control the output of the bias current based on the analog gray voltage and the charging voltage as the analog gray voltage is changed. The method of claim 17, wherein the current control unit, Switching means for switching on / off based on a variable analog gray voltage; And And pull-down means for providing the control signal to the current mirror to control the output of the bias current in response to a switching operation of the switching means. The method of claim 15, wherein the current control unit, Pull-up means for outputting the control signal to control the output of the bias current; And And switching means for providing an output of the control signal based on a variable analog gray voltage. The method of claim 19, wherein the switching means, An operational amplifier having a first polarity terminal connected to the reference voltage and a second polarity terminal connected to the pull-up means; And And an N-type transistor having a gate connected to an output terminal of the operational amplifier, a drain connected to the current mirror, and a source connected to the pull-down means. A driving device of a display device for inputting a gray scale display signal to drive a data line, A reference current generator for inputting the gray level display signal to generate a reference current including an initial pre-charging current corresponding to the gray level variation; And A parasitic capacitor of a pixel connected between the reference current generator and the data line, generating a drive current mirrored by the reference current, and connected to the data line by an initial pre-charging component of the drive current. A drive device for a display device including a current mirror.