KR100442492B1 - Driving circuit of organic electroluminescence device and driving method thereof - Google Patents

Abstract

The present invention relates to a driving circuit and a driving method of an active-matrix type organic light emitting display device, comprising: a gate driver unit for outputting a control signal to sequentially select lines of a light emitting array unit; A driving circuit of an organic light emitting element, comprising: a current driver unit for supplying image data to a line of a light emitting array unit selected by the gate driver unit to selectively drive organic light emitting elements of a selected line, wherein the current driver unit emits light A minimum gray level determination unit determining whether information applied to a specific organic light emitting diode of the array unit is a minimum gray level; Provides a driving circuit and a method of driving the organic light emitting device comprising a switching unit for supplying and blocking a reference voltage or reference current to the specific organic light emitting device by receiving a control signal according to the determination of the minimum gray level determination unit. As a result, the organic light emitting diode displays the predetermined gray level and immediately displays the minimum gray level, thereby not only expressing the accurate gray level but also coping with a fast response speed.

Description

Driving circuit of organic light emitting diode and its driving method {DRIVING CIRCUIT OF ORGANIC ELECTROLUMINESCENCE DEVICE AND DRIVING METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving circuit and method for an active-matrix type organic light emitting display device, and particularly to display on a screen when image data supplied from a current driver IC has a minimum gray level. The present invention relates to a driving circuit and a driving method of an organic light emitting device capable of shortening the time required.

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

First, FIG. 1 is a block diagram illustrating a driving circuit of a general active-matrix type organic light emitting display device. As shown in FIG. 1, a gate driver unit outputting a control signal to sequentially select lines of the light emitting array unit 10. 20; The current driver unit 30 is configured to supply image data to a line of the light emitting array unit 10 selected by the gate driver unit 20 to selectively drive the organic light emitting elements of the selected line.

FIG. 2 is an exemplary view showing a driving circuit for a unit organic light emitting diode. As shown in FIG. 2, first and second PMOS having a source connected to a power supply voltage VDD and a gate connected to each other in common. Transistors PM1 and PM2; A first capacitor C1 connected to a common gate of the power supply voltage VDD and the first and second PMOS transistors PM1 and PM2; An organic light emitting diode 11 connected between the drain of the first PMOS transistor PM1 and the ground VSS; A source is connected to the common gates of the first and second PMOS transistors PM1 and PM2 and a drain is connected to the drain of the second PMOS transistor PM2 to control the gate driver 20. A third PMOS transistor PM3 that is electrically controlled by receiving a signal at the gate; A fourth PMOS transistor (PM4) whose source is connected to the drain connection points of the second and third PMOS transistors (PM2, PM3) and is electrically controlled by receiving a control signal of the gate driver (20); The first NMOS transistor NM1 is connected between the drain of the fourth PMOS transistor PM4 and the ground VSS and is electrically controlled by receiving an analog voltage according to image data from the current driver 30. It is composed.

Hereinafter, the operation of the driving circuit of the conventional organic light emitting display device will be described in detail.

First, as shown in FIG. 1, when the corresponding line of the light emitting array unit 10 is selected by the control signal of the gate driver unit 20, as shown in FIG. A low potential signal is applied to the gates of the third and fourth PMOS transistors PM3 and PM4 so that the third and fourth PMOS transistors PM3 and PM4 are turned on.

As shown in FIG. 1, an analog voltage corresponding to image data is applied to the gate of the first NMOS transistor NM1 by the current driver unit 30 as shown in FIG. The degree of conduction of NM1) is controlled.

At this time, the analog voltage applied to the gate of the first NMOS transistor NM1 is output an appropriate voltage value from the current driver unit 30 according to the gray level of the individual organic light emitting diode 11, for example, the gray level. When implemented with 8-bit digital data, the current driver unit 30 converts digital values between the maximum gray level of '11111111' and the minimum gray level of '00000000' to an analog voltage value through a digital / analog converter. The degree of conduction of the first NMOS transistor NM1 is controlled by applying it to the gate of the first NMOS transistor NM1.

As described above, the third and fourth PMOS transistors PM3 and PM4 are connected to each other according to the degree of conduction of the first NMOS transistor NM1 by the analog voltage value of the current driver unit 30. A constant current flows through the first path leading to the power supply voltage VDD, the second and fourth PMOS transistors PM2 and PM4, the first NMOS transistor NM1, and the ground VSS. The current value flowing through the same flows in the second path leading to the power supply voltage VDD, the first PMOS transistor PM1, the organic light emitting diode 11, and the ground VSS according to the principle of the current mirror. The light emission of the electroluminescent element 11 is controlled.

For example, when displaying the maximum gray level, the current driver 30 converts the digital value of '11111111' into an analog voltage value and applies it to the gate of the first NMOS transistor NM1. The conduction degree of the MOS transistor NM1 becomes maximum so that the maximum current value flows through the first path, and this maximum current value flows in the second path according to the principle of the current mirror, and thus the organic light emitting element 11 The maximum gray level is displayed.

On the other hand, when displaying the minimum gray level, the current driver 30 converts the digital value of '00000000' into an analog voltage value and applies it to the gate of the first NMOS transistor NM1. Since the MOS transistor NM1 is blocked and no current flows in the floating path, the current does not flow in the second path according to the current mirror principle. The level is displayed.

In this case, the gate driver 20 outputs a control signal to sequentially select the first line to the last line of the light emitting array unit 10 in which the organic light emitting diodes 11 are arranged in an array to form one image frame. Display on the screen.

Therefore, when the first line is selected when the organic light emitting diode 11 is assumed to be a unit organic light emitting diode of the first line of the light emitting array unit 10, the third and fourth gate lines are selected by the gate driver 20. The PMOS transistors PM3 and PM4 are turned on, and an analog voltage value suitable for the unit organic electroluminescent element is applied to the gate of the first NMOS transistor NM1 by the current driver unit 30 so that the first NMOS transistor ( By controlling the conduction of NM1), a predetermined current flows in the first path, and the same current flows in the second path according to the current mirror principle, so that an appropriate gray level is displayed from the organic light emitting element 11.

As described above, when the display of the first line is terminated by the gate driver 20, the next line is sequentially selected. At this time, as the third and fourth PMOS transistors PM3 and PM4 of the first line are blocked, the last line is selected. The gray level of the organic light emitting diode 11 is maintained by the first capacitor C1 until a line is selected and one image frame is displayed on the screen.

However, the driving circuit of the conventional organic electroluminescent device as described above, in which any organic electroluminescent device displays the maximum gray level in one image frame and the organic electroluminescent device displays the minimum gray level in the next image frame. In this case, since the first NMOS transistor NM1 is blocked and is in a floating state, the voltage value charged in the first capacitor C1 gradually decreases from the maximum gray level to change to the minimum gray level, thereby representing an accurate gray level. Not only was there a problem that was difficult to cope with fast response speed.

Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to shorten the display time on the screen when the image data supplied from the current driver integrated circuit is at the minimum gray level. The present invention provides a driving circuit and a driving method of an organic light emitting display device.

1 is a block diagram showing a driving circuit of a general organic light emitting display device.

FIG. 2 is an exemplary view showing a driving circuit for a unit organic light emitting display device in FIG.

Figure 3 is a block diagram showing an embodiment of the present invention.

4 is a detailed illustration of a driving circuit of a unit organic light emitting display device in FIG. 3;

FIG. 5 is a detailed illustration of the minimum gray level determining unit and switching unit in FIG. 4; FIG.

6 is a flowchart illustrating a method of driving an organic light emitting display device according to the present invention.

7 is an exemplary view briefly showing a driving principle for a driving device of an organic light emitting display device according to an embodiment of the present invention.

Figure 8 is a block diagram showing another embodiment of the present invention.

FIG. 9 is a detailed illustration of a driving circuit of a unit organic light emitting display device in FIG. 8; FIG.

FIG. 10 is a detailed illustration of a minimum gray level determining unit and a switching unit in FIG. 9; FIG.

11 is a flowchart illustrating a method of driving an organic light emitting display device according to the present invention.

12 is an exemplary view briefly showing a driving principle for a driving apparatus of an organic light emitting display device according to another embodiment of the present invention.

** Explanation of symbols for main parts of drawings **

100: light emitting array portion 200: gate driver portion

300: current driver 310: current driver

320: minimum gray level determination unit 330: switching unit

101: organic light emitting element C11: first capacitor

PM11 to PM14: first to fourth PMOS transistors

NM11: First NMOS Transistor

First, an embodiment of a driving circuit of an organic light emitting device for achieving the object of the present invention as described above includes a gate driver unit for outputting a control signal to sequentially select the lines of the light emitting array unit; A driving circuit of an organic light emitting element, comprising: a current driver unit for supplying image data to a line of a light emitting array unit selected by the gate driver unit to selectively drive organic light emitting elements of a selected line, wherein the current driver unit emits light A minimum gray level determination unit determining whether information applied to a specific organic light emitting diode of the array unit is a minimum gray level; And a switching unit for supplying and blocking a reference voltage to the specific organic light emitting diode by receiving a control signal according to the determination of the minimum gray level determination unit.

In addition, another embodiment of the driving circuit of the organic light emitting device for achieving the object of the present invention as described above includes a gate driver unit for outputting a control signal to sequentially select the lines of the light emitting array unit; A driving circuit of an organic light emitting element, comprising: a current driver unit for supplying image data to a line of a light emitting array unit selected by the gate driver unit to selectively drive organic light emitting elements of a selected line, wherein the current driver unit emits light A minimum gray level determination unit determining whether information applied to a specific organic light emitting diode of the array unit is a minimum gray level; And a switching unit configured to receive a control signal according to the determination of the minimum gray level determination unit and supply and cut off a reference current to the specific organic light emitting diode.

In addition, an embodiment of a method of driving an organic light emitting device for achieving the object of the present invention as described above is the image data supplied to the organic light emitting elements of the light emitting array unit selected by the gate driver and the current driver unit. A first step of reading; A second step of determining whether the image data is a minimum gray level; If the image data is not the minimum gray level, the current is supplied to the organic light emitting diode by driving the current driver unit to emit light. If the image data is the minimum gray level, the current supplied from the current driver unit And a third step of supplying a reference voltage to the organic light emitting diode.

In addition, another embodiment of a method of driving an organic light emitting device for achieving the object of the present invention as described above is the image data supplied to the organic light emitting elements of the light emitting array unit selected by the gate driver and the current driver unit. A first step of reading; A second step of determining whether the image data is a minimum gray level; If the image data is not the minimum gray level, the current is supplied to the organic light emitting diode by driving the current driver unit to emit light. If the image data is the minimum gray level, the current supplied by the current driver unit And a third step of supplying a reference current to the organic light emitting diode.

The driving circuit and driving method of the organic light emitting diode according to the present invention as described above will be described in more detail with reference to the accompanying drawings.

First, Figure 3 is a block diagram showing an embodiment of the present invention, as shown in the gate driver 200 for outputting a control signal to sequentially select the lines of the light emitting array unit 100; A current driver 300 for supplying image data R G B DATA to a line of the light emitting array unit 100 selected by the gate driver 200 to selectively drive the organic light emitting elements of the selected line; The image data RGB data is supplied from the inside of the current driver 300 to supply the image data RGB data to the line of the light emitting array unit 100 selected by the gate driver 200. A current driver 310 for selectively driving the organic light emitting diodes; Minimum gray provided in the current driver 300 to determine whether image data RGB data applied from the current driver 310 to a specific organic light emitting diode of the light emitting array unit 100 is a minimum gray level. A level determining unit 320; A switching unit provided inside the current driver 300 to supply and cut a reference voltage Vref to the specific organic light emitting diode by receiving a control signal according to the determination of the minimum gray level determination unit 320 ( 330).

The reference voltage Vref may be supplied through a voltage driver (not shown).

FIG. 4 is a detailed illustration of the driving circuit of the unit organic light emitting diode according to the exemplary embodiment of the present invention as described above. As shown in FIG. 4, a source is connected to a power supply voltage VDD, and a gate is connected. First and second PMOS transistors PM11 and PM12 connected in common; A first capacitor C11 connected to a common gate of the power supply voltage VDD and the first and second PMOS transistors PM11 and PM12; An organic light emitting diode 101 connected between the drain of the first PMOS transistor PM11 and a ground VSS; A source is connected to the common gates of the first and second PMOS transistors PM11 and PM12 and a drain is connected to the drain of the second PMOS transistor PM12 to control the control signal of the gate driver 200. A third PMOS transistor PM13 applied to the gate to be electrically controlled; A fourth PMOS transistor PM14 having a source connected to the drain connection points of the second and third PMOS transistors PM12 and PM13 and electrically connected and controlled by a control signal of the gate driver 200; The analog voltage of the gray level is connected between the drain of the fourth PMOS transistor PM14 and the ground VSS and is provided in the current driver 310 of the current driver unit 300 according to the image data RGB SIGNAL. A first NMOS transistor NM11 controlled to be electrically connected to the gate; A minimum gray level determination unit 320 provided inside the current driver 300 to determine a minimum gray level by receiving a digital value of a gray level according to the image data RGB SIGNAL from the current driver 310; ; It is provided inside the current driver 300 to receive a control signal according to the determination of the minimum gray level determination unit 320 to supply a reference voltage (Vref) to the drain of the first NMOS transistor (NM11) and It is composed of a switching unit 330 to block.

Hereinafter, the operation of the driving circuit of the organic light emitting display device according to the embodiment of the present invention as described above will be described in detail.

First, as shown in FIG. 3, when the corresponding line of the light emitting array unit 100 is selected by the control signal of the gate driver unit 200, as shown in FIG. 4, the driving circuit of the unit organic electroluminescent element is formed. A low potential signal is applied to the gates of the third and fourth PMOS transistors PM13 and PM14 to conduct the third and fourth PMOS transistors PM13 and PM14.

As shown in FIG. 3, the analog voltage according to the image data RGB SIGNAL is applied to the gate of the first NMOS transistor NM11 shown in FIG. 4 by the current driver 300, and the first NMOS The degree of conduction of the transistor NM11 is controlled.

At this time, the analog voltage applied to the gate of the first NMOS transistor NM11 is output an appropriate voltage value from the current driver 300 according to the gray level of the individual organic light emitting diode 101, for example, the gray level. When implemented with 8-bit digital data, the current driver 300 converts the digital values between the maximum gray level of '11111111' and the minimum gray level of '00000000' to an analog voltage value through a digital / analog converter. The degree of conduction of the first NMOS transistor NM11 is controlled by applying it to the gate of the first NMOS transistor NM11.

As described above, the power is supplied according to the degree of conduction of the first NMOS transistor NM11 by the analog voltage value of the current driver unit 300 while the third and fourth PMOS transistors PM13 and PM14 are connected. A constant current flows through the first path leading to the voltage VDD, the second and fourth PMOS transistors PM12 and PM14, the first NMOS transistor NM11, and the ground VSS. The current value flowing through the same flows in the second path leading to the power supply voltage VDD, the first PMOS transistor PM11, the organic light emitting diode 101, and the ground VSS according to the principle of the current mirror. The light emission of the light emitting element 101 is controlled.

For example, when displaying the maximum gray level, the current driver 300 converts the digital value of '11111111' into an analog voltage value and applies it to the gate of the first NMOS transistor NM11. The conduction degree of the MOS transistor NM11 is maximized so that the maximum current value flows through the first path, and this maximum current value flows in the second path according to the principle of the current mirror, so that the organic light emitting element 101 The maximum gray level is displayed.

On the other hand, when displaying the minimum gray level, the current driver 300 converts the digital value of '00000000' into an analog voltage value and applies it to the gate of the first NMOS transistor NM11. Since the MOS transistor NM11 is blocked and no current flows in the floating path, the current does not flow in the second path according to the current mirror principle, so that the minimum gray level is displayed from the organic light emitting diode 101. do.

In this case, the gate driver 200 outputs a control signal to sequentially select the first line to the last line of the light emitting array unit 100 in which the organic light emitting diodes 101 are arranged in an array to form one image frame. Display on the screen.

Accordingly, when the first line is selected when the organic light emitting diode 101 is assumed to be a unit organic light emitting diode of the first line of the light emitting array unit 100, the third and fourth gate lines are selected by the gate driver 200. The PMOS transistors PM13 and PM14 are turned on, and an analog voltage value suitable for the unit organic light emitting diode is applied to the gate of the first NMOS transistor NM11 by the current driver unit 300 so that the first NMOS transistor ( By controlling the conduction of NM11, a predetermined current flows in the first path, and the same current flows in the second path according to the current mirror principle, so that an appropriate gray level is displayed from the organic light emitting element 101.

As described above, when the display of the first line is terminated by the gate driver 200, the next line is sequentially selected. At this time, as the third and fourth PMOS transistors PM13 and PM14 of the first line are blocked, the last line is selected. The gray level of the corresponding organic light emitting display device 101 is maintained by the first capacitor C11 until a line is selected and one image frame is displayed on the screen.

On the other hand, the minimum gray level determination unit 320 is provided in the current driver unit 300 as shown in the detailed circuit diagram of Figure 5 to the gray level of the unit organic electroluminescent device from the current driver 310 By combining the digital values through the NOA gate NOR401, for example, only when a digital value having a minimum gray level of '00000000' is input, a logical high potential is selectively output to determine whether the minimum gray level is present. In this case, the NOA gate NOR401 may include an inverter for inverting the digital value of the gray level for the unit organic light emitting diode from the current driver 310 as needed; The same output value can also be obtained by designing the output value of the inverter with an AND gate that is AND-combined.

As shown in the detailed circuit diagram of FIG. 5, the switching unit 330 is provided inside the current driver unit 300 so that a reference voltage when the output of the NOA gate NOR401 is applied with a logical high potential. (Vref) is selectively supplied to the first path.

On the other hand, the driving method of the organic light emitting display device according to the present invention is as shown in the flow chart of FIG.

First, as shown in the first step S11, image data supplied to the organic electroluminescent elements of the light emitting array section selected by the gate driver section and the current driver section are read.

Then, as shown in the second step S12, it is determined whether the image data is the minimum gray level.

As shown in the third step S13, when the image data is not at the minimum gray level, the current is supplied to the organic light emitting diode by driving the current driver to emit light, and the image data is at least gray. In the case of the level, the current supplied by the current driver unit is cut off, and a reference voltage is supplied to the organic light emitting diode.

Therefore, when an organic light emitting diode displays a predetermined gray level in one image frame and the organic light emitting diode displays a minimum gray level in the next image frame, a reference voltage Vref is applied to the first path. So that the organic light emitting display displays the predetermined gray level and then immediately displays the minimum gray level.

7 is an exemplary view briefly showing a driving principle of a driving apparatus of an organic light emitting display device according to an embodiment of the present invention.

Referring to FIG. 7, when the organic light emitting diode 101 displays a predetermined gray level, the current driver 310 is connected to the driving circuit of the organic light emitting diode by the switching unit 330. The fourth PMOS transistors PM13 and PM14 are turned on, and the analog voltage according to the image data RGB SIGNAL is applied to the gate of the first NMOS transistor NM11 so that the first NMOS transistor NM11 is turned on. By controlling, the current flowing through the organic light emitting element 101 is controlled to display a predetermined gray level.

However, when the organic light emitting diode 101 displays the minimum gray level, the first NMOS transistor NM11 is cut off, and the voltage driver 340 is driven by the switching unit 330 to drive the organic light emitting diode. The first and second PMOS transistors PM11 and PM12 are turned off as they are connected to and supply the reference voltage Vref, so that current flowing through the organic light emitting element 101 is cut off to display the minimum gray level. do.

8 is a block diagram showing another embodiment of the present invention, as shown therein, a gate driver 500 for outputting a control signal to sequentially select lines of the light emitting array unit 400; A current driver 600 for supplying image data R G B DATA to a line of the light emitting array unit 400 selected by the gate driver 500 to selectively drive the organic light emitting elements of the selected line; The image data RGB data is supplied inside the current driver 600 to supply the image data RGB data to the line of the light emitting array unit 400 selected by the gate driver 500 to supply the image data RGB data. A current driver 610 for selectively driving the organic light emitting diodes; Minimum gray provided inside the current driver 600 to determine whether image data RGB data applied from the current driver 610 to a specific organic light emitting diode of the light emitting array unit 400 is a minimum gray level. A level determining unit 620; A switching unit provided inside the current driver 600 to supply and block a reference current Iref to the specific organic light emitting diode by receiving a control signal according to the determination of the minimum gray level determination unit 620 ( 630).

The reference current Iref may be supplied through a current source (not shown).

9 is a detailed illustration of a driving circuit of a unit organic light emitting diode according to another embodiment of the present invention as described above. As shown in FIG. 9, a source is connected to a power supply voltage VDD and a gate is connected. First and second PMOS transistors PM21 and PM22 connected in common; A first capacitor C21 connected to a common gate of the power supply voltage VDD and the first and second PMOS transistors PM21 and PM22; An organic light emitting diode 401 connected between the drain of the first PMOS transistor PM21 and a ground VSS; A source is connected to the common gates of the first and second PMOS transistors PM21 and PM22 and a drain is connected to the drain of the second PMOS transistor PM22 to control the control signal of the gate driver 500. A third PMOS transistor PM23 applied to the gate to be electrically controlled; A fourth PMOS transistor (PM24) whose source is connected to the drain connection points of the second and third PMOS transistors (PM22 and PM23) and electrically controlled by receiving a control signal of the gate driver (500); The analog voltage of the gray level is connected between the drain of the fourth PMOS transistor PM24 and the ground VSS and is provided in the current driver 610 of the current driver unit 600 according to the image data RGB SIGNAL. A first NMOS transistor NM21 controlled to be electrically connected to the gate; A minimum gray level determination unit 620 provided inside the current driver 600 to determine whether the gray level is the minimum gray level by receiving a digital value of the gray level according to the image data RGB signal from the current driver 610; ; The reference current Iref is supplied to the drain of the first NMOS transistor NM21 in response to a control signal according to the determination of the minimum gray level determination unit 620 provided in the current driver 600. It is composed of a switching unit 630 for blocking.

Hereinafter, the operation of the driving circuit of the organic light emitting display device according to the embodiment of the present invention as described above will be described in detail.

First, as shown in FIG. 8, when the corresponding line of the light emitting array unit 400 is selected by the control signal of the gate driver unit 500, the driving circuit of the unit organic electroluminescent element as shown in FIG. A low potential signal is applied to the gates of the third and fourth PMOS transistors PM23 and PM24 to conduct the third and fourth PMOS transistors PM23 and PM24.

As shown in FIG. 8, an analog voltage corresponding to the image data RGB SIGNAL is applied to the gate of the first NMOS transistor NM21 shown in FIG. 9 by the current driver 600, and the first NMOS The degree of conduction of the transistor NM21 is controlled.

At this time, the analog voltage applied to the gate of the first NMOS transistor NM21 is output an appropriate voltage value from the current driver 600 according to the gray level of the individual organic light emitting diode 401, for example, the gray level. When implemented with 8-bit digital data, the current driver 600 converts digital values between the maximum gray level of '11111111' and the minimum gray level of '00000000' into analog voltage values through a digital / analog converter. The degree of conduction of the first NMOS transistor NM21 is controlled by applying it to the gate of the first NMOS transistor NM21.

As described above, when the third and fourth PMOS transistors PM23 and PM24 are connected, the power is supplied according to the degree of conduction of the first NMOS transistor NM21 by the analog voltage value of the current driver 600. A constant current flows through the first path leading to the voltage VDD, the second and fourth PMOS transistors PM22 and PM24, the first NMOS transistor NM21, and the ground VSS. The current value flowing through the same flows in the second path leading to the power supply voltage VDD, the first PMOS transistor PM21, the organic light emitting diode 401, and the ground VSS according to the principle of the current mirror. The light emission of the light emitting element 401 is controlled.

For example, when displaying the maximum gray level, the current driver 600 converts the digital value of '11111111' into an analog voltage value and applies it to the gate of the first NMOS transistor NM21. The conduction of the MOS transistor NM21 is maximized so that the maximum current value flows through the first path, and the maximum current value flows in the second path according to the principle of the current mirror, and thus the organic light emitting element 401 The maximum gray level is displayed.

On the other hand, when displaying the minimum gray level, the current driver 600 converts the digital value of '00000000' into an analog voltage value and applies it to the gate of the first NMOS transistor NM21. Since the MOS transistor NM21 is blocked and no current flows in the floating path, the current does not flow in the second path according to the current mirror principle, so that the minimum gray level is displayed from the organic light emitting diode 401. do.

In this case, the gate driver 500 outputs a control signal so that the organic light emitting diodes 401 may sequentially select from the first line to the last line of the light emitting array unit 400 arranged in an array to form one image frame. Display on the screen.

Therefore, when the first line is selected when the organic light emitting diode 401 is assumed to be a unit organic light emitting diode of the first line of the light emitting array unit 400, the third and fourth gates are selected by the gate driver 500. The PMOS transistors PM23 and PM24 are turned on, and an analog voltage value suitable for the unit organic light emitting diode is applied to the gate of the first NMOS transistor NM21 by the current driver unit 600 so that the first NMOS transistor ( By controlling the conduction of NM21, a predetermined current flows in the first path, and the same current flows in the second path according to the current mirror principle, so that an appropriate gray level is displayed from the organic light emitting element 401.

As described above, when the display of the first line is terminated by the gate driver 500, the next line is sequentially selected. At this time, as the third and fourth PMOS transistors PM23 and PM24 of the first line are blocked, the last line is selected. The line is selected to maintain the displayed gray level of the organic light emitting display device 401 by the first capacitor C21 until one image frame is displayed on the screen.

On the other hand, the minimum gray level determination unit 620 is provided inside the current driver 600 as shown in the detailed circuit diagram of FIG. 10 to determine the gray level of the unit organic electroluminescent device from the current driver 610. By combining the digital values through the NOA gate NOR501, for example, only when a digital value having a minimum gray level of '00000000' is input, the logical high potential is selectively output to determine whether the minimum gray level is present. At this time, the NOA gate N501 includes an inverter for inverting the digital value of the gray level for the unit organic light emitting diode from the current driver 610 as necessary; The same output value can also be obtained by designing the output value of the inverter with an AND gate that is AND-combined.

As shown in the detailed circuit diagram of FIG. 10, the switching unit 630 is provided in the current driver unit 600 so that the reference current when the output of the NOA gate NOR501 is applied with a logical high potential. (Iref) is selectively supplied to the first path.

On the other hand, the driving method of the organic light emitting device according to the present invention is as shown in the flow chart of FIG.

First, as shown in the first step S21, image data supplied to the organic electroluminescent elements of the light emitting array section selected by the gate driver section and the current driver section are read.

Then, as shown in the second step S22, it is determined whether the image data is the minimum gray level.

As shown in the third step S23, when the image data is not at the minimum gray level, current is supplied to the organic light emitting diode by driving the current driver to emit light, and the image data is at least gray. In the case of the level, the current supplied by the current driver unit is cut off, and the reference current is supplied to the organic light emitting diode.

Therefore, when an organic light emitting diode displays a predetermined gray level in one image frame and the organic light emitting diode displays a minimum gray level in the next image frame, a reference current Iref is applied to the first path. So that the organic light emitting display displays the predetermined gray level and then immediately displays the minimum gray level.

12 is an exemplary view briefly showing a driving principle of a driving apparatus of an organic light emitting display device according to another embodiment of the present invention.

Referring to FIG. 12, when the organic light emitting diode 401 displays a predetermined gray level, the current driver 610 is connected to the driving circuit of the organic light emitting diode by the switching unit 630. The fourth PMOS transistors PM23 and PM24 are turned on, and the analog voltage according to the image data RGB SIGNAL is applied to the gate of the first NMOS transistor NM21 to conduct the first NMOS transistor NM21. By controlling, the current flowing through the organic light emitting element 401 is controlled to display a predetermined gray level.

However, when the organic light emitting diode 401 displays the minimum gray level, the first NMOS transistor NM21 is cut off and the current source 640 is switched by the switching unit 630 to the driving circuit of the organic light emitting diode. As the first and second PMOS transistors PM21 and PM22 are turned off as they are connected to supply the reference current Iref, the current flowing through the organic light emitting diode 401 is cut off to display the minimum gray level. .

As described above, the driving circuit and the driving method of the organic light emitting display device according to the present invention show that any organic light emitting display device displays a predetermined gray level in one image frame, and then the organic light emitting display device has minimum In the case of displaying the gray level, by selectively supplying a reference voltage or a reference current, the organic light emitting display device displays a predetermined gray level and then immediately displays the minimum gray level. It is effective to cope with the response speed.

Claims (10)

A gate driver unit outputting a control signal to sequentially select lines of the light emitting array unit; A driving circuit of an organic light emitting display device, comprising: a current driver supplying image data to a line of a light emitting array section selected by the gate driver section to selectively drive organic light emitting display elements of a selected line; A minimum gray level determination unit configured to determine whether image data applied to a specific organic light emitting element of the light emitting array unit is a minimum gray level; And a switching unit which is provided in the current driver unit and receives a control signal according to the determination of the minimum gray level determination unit to supply and cut off a reference voltage to the specific organic light emitting element. Driving circuit. The method of claim 1, wherein the minimum gray level determination unit comprises a noah gate that receives a digital value of a gray level for a specific organic light emitting device from the current driver unit and combines it with a noah to output the control signal to the switching unit. A drive circuit for an organic light emitting display device. The display apparatus of claim 1, wherein the minimum gray level determiner comprises: an inverter configured to receive a digital value of a gray level for a specific organic light emitting diode from the current driver; And an AND gate configured to AND-combine the outputs of the inverter and output the control signal to the switching unit. The driving circuit of an organic light emitting display device according to claim 1, further comprising a voltage driver for supplying the reference voltage. A gate driver unit outputting a control signal to sequentially select lines of the light emitting array unit; A driving circuit of an organic light emitting display device, comprising: a current driver supplying image data to a line of a light emitting array section selected by the gate driver section to selectively drive organic light emitting display elements of a selected line; A minimum gray level determination unit configured to determine whether image data applied to a specific organic light emitting element of the light emitting array unit is a minimum gray level; And a switching unit which is provided in the current driver unit and supplies a control current according to the determination of the minimum gray level determination unit to supply and cut off a reference current to the specific organic light emitting device. Driving circuit. 6. The method of claim 5, wherein the minimum gray level determination unit comprises a noah gate that receives a digital value of a gray level for a specific organic light emitting device from the current driver unit and combines it by a noah to output a control signal to the switching unit. A drive circuit for an organic light emitting display device. The display apparatus of claim 5, wherein the minimum gray level determiner comprises: an inverter configured to receive a digital value of a gray level for a specific organic light emitting diode from the current driver; And an AND gate configured to AND-combine the outputs of the inverter and output the control signal to the switching unit. 6. The driving circuit of an organic light emitting device according to claim 5, further comprising a current source for supplying the reference current. A first step of reading image data supplied to the organic electroluminescent elements of the light emitting array section selected by the gate driver section and the current driver section; A second step of determining whether the image data is a minimum gray level; If the image data is not the minimum gray level, the current is supplied to the organic light emitting diode by driving the current driver unit to emit light. If the image data is the minimum gray level, the current supplied by the current driver unit Blocking and supplying a reference voltage to the organic light emitting diode. A first step of reading image data supplied to the organic electroluminescent elements of the light emitting array section selected by the gate driver section and the current driver section; A second step of determining whether the image data is a minimum gray level; If the image data is not the minimum gray level, the current is supplied to the organic light emitting diode by driving the current driver unit to emit light. If the image data is the minimum gray level, the current supplied by the current driver unit Blocking and supplying a reference current to the organic light emitting diode.