KR100510654B1 - apparatus and method for driving of organic electroluminescence panel - Google Patents

Abstract

The present invention reduces the time taken to charge a column electrode line to VCC and increases the time for supplying current to the organic EL element, thereby driving and driving the organic EL panel to increase the emission time of the organic EL element. A scan electrode driver for outputting a signal for sequentially selecting scan electrode lines of an organic EL display, and a column electrode driver for supplying or charging a constant current to the column electrode lines or discharging the charged charges. And an organic EL panel unit which emits light according to signals output from the scan electrode driver and the column electrode driver, and an external switch unit which binds all the scan electrode lines and all the column electrode lines into one.

Description

Apparatus and method for driving of organic electroluminescence panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL display device, and more particularly, to a driving device and a driving method for low power consumption in a passive matrix organic EL panel.

Recently, in the field of flat panel display, rapid progress has been made.

In particular, flat-panel displays, which started to emerge as the leading liquid crystal displays (LCDs), have surpassed the Cathode Ray Tube (CRT), which has been the most used in the display field for decades, and recently, the plasma display panel (PDP) and the visual fluorescence (VFD). Many developments are being made such as display (FED), field emission display (FED), light emitting diode (LED), and electroluminescence (EL).

Such display devices are not only good in visibility and color, but also have a simple manufacturing process, thereby expanding their applications in many areas.

Recently, the organic EL display device has been attracting attention as a flat panel display device having less space occupancy due to the increase in size of the display device. The reason is that the organic EL display device has low voltage driving, high luminous efficiency, fast response speed, and wide viewing angle. With its advantages, it is attracting attention as the next generation flat panel display technology that can display high quality video.

The organic EL display device can be divided into a passive matrix and an active matrix according to the driving method. The biggest difference between the two driving methods is that there is a difference in the emission time of the organic EL device.

That is, the passive matrix organic EL display is a driving method that emits light only for a selected time period, whereas the active matrix organic EL display is a driving method that keeps emitting light in addition to the selected time.

In addition, since the passive matrix organic EL display emits light with high luminance instantaneously, it has a disadvantage in that a relatively high voltage is applied compared to the active matrix organic EL display, and thus power consumption is large.

1 is a diagram showing a passive matrix organic EL display having M column electrode lines and N scan electrode lines according to the prior art.

Referring to the configuration of FIG. 1, the scan electrode driver 10 for outputting a signal for sequentially selecting the scan electrode line 40 of the organic EL display, and the current source 21 for supplying a constant current to the column electrode line 50. ) And a light source according to the signal output from the scan electrode driver 10 and the column electrode driver 20. The column electrode driver 20 includes a sink 22 configured to discharge charges charged in the column electrode line. It consists of the organic electroluminescent panel part 30 which emits light.

2 is a diagram illustrating an internal equivalent circuit of an organic EL unit pixel according to the prior art.

As shown in FIG. 2, the organic EL unit pixel may be electrically represented by a diode (D), a resistor (R), and a capacitor (C), and the resistor (R) and the diode (D) are connected in series. An anode voltage is applied to the other end of the resistor R, and a cathode voltage is applied to the other end of the diode D.

The diode D and the capacitor C are connected in parallel.

The organic EL element that emits light from the organic EL panel portion 30 shown in FIG. 1 electrically operates like the diode D shown in FIG. 2 and has a current from the anode to the cathode when the anode voltage is higher than or equal to the threshold voltage. Flows, and the organic EL element emits light.

However, when the anode voltage is lower than the cathode voltage, the organic EL element does not emit light and simply acts as a capacitor.

Therefore, when the FIG. 2 is applied to the organic EL panel unit 30 shown in FIG. 1, the column electrode line 50 in the organic EL display panel has a capacitor C and a resistor R having a very large value with the organic EL element. You can see that it consists of.

The driving of the passive matrix organic EL display shown in FIG. 1 is as follows.

First, when the first scan electrode line S_1 is selected (the GND voltage 12 is selected), the current source 21 of the column electrode driver 20 receives a certain amount of current through the column electrode line 50 according to a predetermined luminance. It supplies to organic electroluminescent element.

At this time, the current supplied from the column electrode driver 20 first charges the parasitic capacitor present in the column electrode line to the VCC voltage, and then supplies a certain amount of current to the organic EL element after the parasitic capacitor is charged. Will emit light.

When the organic EL emits light for a predetermined time, all of the charges charged in the column electrode line are discharged through the sink 22 of the column electrode driver 20.

Next, when the second scan electrode line S_2 is selected (the GND voltage 12 is selected), the current source 21 of the column electrode driver 20 transmits a certain amount of current through the column electrode line according to a predetermined luminance. To feed.

The current supplied from the column electrode driver 20 is charged with the parasitic capacitor present in the column electrode line up to the VCC voltage, and when the parasitic capacitor is charged, the current is supplied to the organic EL device. It will emit light.

Next, when the third scan electrode line is selected, the same charge is received after the current is supplied from the column electrode driver 20 as in the case where the first and second scan electrode lines are selected, and the charged charge is sinked in the column electrode driver 20. All are discharged through the unit 22, and the organic EL display device is similarly driven even when the Nth scan electrode line is selected.

As can be seen from the above description, since the passive matrix organic EL display device continuously charges and discharges periodically to the parasitic capacitor present in the column electrode line 50 every time the scan electrode line 40 is selected. The disadvantage is that the power consumption is very large.

Accordingly, an object of the present invention is to provide a driving device and a driving method of a passive matrix organic EL panel with low power consumption.

Another object of the present invention is to reduce the time taken to charge the column electrode line to VCC and increase the time for supplying current to the organic EL element, thereby increasing the luminous efficiency of the organic EL element.

A feature of the driving apparatus of the organic EL panel according to the present invention for achieving the above object is a scan electrode driver for outputting a signal for sequentially selecting the scan electrode line of the organic EL display, and supplying a constant current to the column electrode line A column electrode driver for charging or discharging the charged charges, an organic EL panel unit for emitting light in accordance with signals output from the scan electrode driver and the column electrode driver, all the scan electrode lines and all the column electrode lines It is configured to include an external switch unit tying the one.

In this case, the scan electrode driver is a ground (GND) power supply for selecting the scan electrode line is switched and driven for each scan electrode line, and the VCC power supply is switched to the non-driven scan electrode line other than the GND power supply to apply a predetermined voltage And a switch unit electrically connected to the external switch unit so as to bind all the scan electrode lines into one.

The column electrode driver includes a current source for supplying a constant current to the organic EL pixel for each column electrode line, a sink unit for discharging the charge charged to the column electrode line through the current source, and all the column electrode lines as one. It is preferably configured to include a switch unit electrically connected to the external switch unit for binding.

The external switch unit may include a switch for simultaneously tying all the scan electrode lines and all the column electrode lines, and a voltage source for supplying VCC power to the scan electrode lines when all the scan electrode lines are bundled together. desirable.

A characteristic of the method for driving the organic EL panel according to the present invention for achieving the above object is that the electric potential is not present in all the column electrode lines and all the scan electrode lines by electrically shorting all the column electrode lines and all the scan electrode lines with each other. Maintaining a non-floating state, keeping all of the electrically connected column electrode lines and all of the scan electrode lines open only the column electrode lines, thereby maintaining the column electrode lines floating; Disconnecting the column electrode line from all the connected scan electrode lines and then connecting VCC power to maintain the voltages of all the scan electrode lines at VCC, all the scan electrode lines and the floating column electrode lines Maintaining a voltage VCC in all the column electrode lines and all the scan electrode lines by Selecting a corresponding scan electrode line to be lighted, applying a voltage to a corresponding column electrode line to emit an organic EL element, and after the organic EL element emits light for a predetermined time, grounds the column electrode line to ground And discharging the charge charged in the electrode line, and repeating the process until all the scan electrode lines are selected.

In this case, maintaining the voltages of all the column electrode lines and all the scan electrode lines at VCC may cause all the scan electrode lines to float, and then apply the VCC voltage to all the column electrode lines to float them. It can be replaced by raising the voltage of the scanned scan line to VCC, which has another feature.

Another feature of the method for driving an organic EL panel according to the present invention for achieving the above object is that all column electrode lines or scans in a state in which all column electrode lines and all scan electrode lines are short-circuited in the above-mentioned feature of the invention. It is to apply VCC power to the scan electrode line and the column electrode line at the same time without floating the electrode line.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

A preferred embodiment of the driving apparatus and driving method of an organic EL panel according to the present invention will be described with reference to the accompanying drawings.

Fig. 3 shows a passive matrix organic EL display device and drive driver according to the present invention.

Referring to the configuration of FIG. 3, the scan electrode driver 10 for outputting a signal for sequentially selecting the scan electrode line 40 of the organic EL display and the column electrode line 50 are supplied with a constant current or charged. A column electrode driver 20 for discharging charged charges, an organic EL panel unit 30 for emitting light in accordance with signals output from the scan electrode driver 10 and the column electrode driver 20, and all of the above It consists of an external switch unit 60 that binds the scan electrode line 40 and all the column electrode lines 50 into one.

In this case, the scan electrode driver 10 is a circuit that sequentially generates a scan signal to each scan electrode line, and is switched for each scan electrode line to switch the ground (GND) power source 12 to select the scan electrode line, and the switching. And the VCC power supply 11 which does not select a scan electrode line. The selection of the GND power supply 12 and the VCC power supply 11 is selected through a switch, and further includes a switch 13 connected to the external switch unit 60 to tie all the scan electrode lines into one. It is.

The column electrode driver 20 includes a current source 21 for supplying a constant current to the organic EL pixel for each column electrode line, a sink 22 for discharging charges charged in the column electrode line, and all columns. The switch 23 is connected to the external switch unit 60 to bind the electrode line.

In addition, the external switch unit 60 is a switch capable of tying all the scan electrode lines 40 and all the column electrode lines 50 at the same time, and all the scan electrode lines 40 and / or all the column electrode lines are bundled into one. It is composed of a voltage source for supplying the VCC power to the scan electrode line.

The operation of the driving circuit and driving method of the organic EL panel according to the present invention configured as described above will be described in detail with reference to the accompanying drawings.

First, a driving method of a passive matrix organic EL display device according to the present invention will be described.

The driving method according to the present invention is largely divided into three stages.

The first step shorts all column electrode lines and all scan electrode lines from each other so that all column electrode lines and all scan electrode lines are subjected to the same voltage.

That is, since the potential difference does not exist in the column electrode line and the scan electrode line, there is no potential difference between the anode electrode and the cathode electrode of the organic EL element.

The second step is to open all the switches of the column electrode line so that all the column electrode lines are floating. Connect VCC power to all scan electrode lines.

Then, the voltages of all the scan electrode lines are changed to VCC, and since the terminals of the column electrode lines are floating, the voltages of the column electrode lines are also changed to VCC.

The third step is to select the corresponding scan electrode line to emit light, and apply a voltage to the corresponding column electrode line to emit the organic EL element.

The driving method of the three stages, which is the driving method of the passive matrix organic EL display device according to the present invention, will be described in detail with reference to the accompanying drawings.

4 to 7 illustrate a method of driving the first scan electrode line in the driving method according to the present invention, and FIGS. 8 to 11 illustrate a method of driving the second scan electrode line in the driving method according to the present invention. have.

FIG. 4 is a circuit diagram of a scan electrode line and a column electrode line by shorting all scan electrode lines and all column electrode lines which are the first step of the drive method according to the present invention in the step of driving the first scan electrode line in the driving method according to the present invention. The state which keeps the voltage of the same is shown.

Referring to FIG. 4, the scan electrode driver 10 has a short circuited switch 13 that binds all the scan electrode lines 40 to one, and the column electrode driver 20 also includes a switch that binds all the column electrode lines 50 to one. 23) is short-circuited.

All of the scan electrode lines 40 and all the column electrode lines 50 are short-circuited through the external switch unit 60.

As a result, the cathode electrode voltage and the anode electrode voltage of the organic EL element are in the same state, so that there is no potential difference between the anode electrode and the cathode electrode of the organic EL element.

5 is a state in which the voltages of all the scan electrode lines and the voltages of all the column electrode lines which are the second stage of the driving method according to the present invention and the voltages of all the column electrode lines in the driving method according to the present invention are maintained at VCC. Indicates.

Referring to FIG. 5, the switch 22 in the column electrode driver 20 which binds all the column electrode lines 50 together is opened to maintain the column electrode lines 50 in a floating state.

Subsequently, in the state where all of the scan electrode lines 40 are shorted, the external switch unit 60 disconnects the column electrode driving unit 20, and connects the shorted scan electrode lines 13 to the short circuited scan electrode lines 13 with VCC power.

When the driving circuit is operated in this manner, the voltage of the scan electrode line is increased to VCC, and since the column electrode line is floating, the voltage is also raised to VCC so that there is no potential difference at both ends.

6 and 7 illustrate the first scan electrode line S-1 which is the third step of the driving method according to the present invention and the corresponding column in the step of driving the first scan electrode line in the driving method according to the present invention. The state in which the organic EL element is made to emit light by applying a voltage to the electrode line is shown.

Referring to FIG. 6, a switch shorted to the VCC voltage is opened in the external switch unit 60, and the first scan electrode line S_1 to be selected is switched to the GND voltage 12 to be selected, and the rest of the scan is performed. The electrode lines S_2, S_3,..., S_N are switched to the VCC voltage 11 and are selected.

As shown in FIG. 7, when the first scan electrode line S_1 is selected, a corresponding current source 21 of the column electrode driver 20 is switched and selected to supply a predetermined amount of current to the corresponding column electrode line. The organic EL device is made to emit light.

FIG. 7 shows that current is supplied to C_1, C_2, and C_M-2 column electrode lines among the M column electrode lines, and the organic EL elements of the first line corresponding thereto emit light.

Next, the scan electrode driver and the column electrode driver are operated at the time of driving the second scan electrode line through the driving method of FIGS. 8 to 11.

FIG. 8 is a circuit diagram of a scan electrode line and a column electrode line by shorting all scan electrode lines and all column electrode lines which are the first step of the drive method according to the present invention in the step of driving the second scan electrode line in the driving method according to the present invention. The state which keeps the voltage of the same is shown.

Referring to FIG. 8, the scan electrode driver 10 short-circuits the switch 13 which binds all the scan electrode lines 40 to one, and the column electrode driver 20 also includes the switch that binds all the column electrode lines 50 to one. 23) is short-circuited.

All of the scan electrode lines 40 and all the column electrode lines 50 are short-circuited through the external switch unit 60.

At this time, since the voltage of all the scan electrode lines except the one scan electrode line selected when the previous scan electrode line (the first scan electrode line) is driven is VCC, the scan electrode line and the column electrode line are connected through the external switch unit 60. If the short circuit occurs, the voltage at both ends becomes (1-1 / N) VCC. Where N is the number of scan lines.

As a result, the cathode electrode voltage and the anode electrode voltage of the organic EL element are in the same state at (1-1 / N) VCC, so that there is no potential difference between the anode electrode and the cathode electrode of the organic EL element.

9 is a state in which the voltages of all the scan electrode lines and the voltages of all the column electrode lines which are the second stage of the driving method according to the present invention and the voltages of all the column electrode lines in the driving method according to the present invention are maintained at VCC. Indicates.

Referring to FIG. 9, the switch 23 in the column electrode driver 20 which binds all the column electrode lines 50 together is opened to keep the column electrode lines 50 floating.

Subsequently, in the state in which the scan electrode lines 50 are all shorted, the external switch unit 60 disconnects the column electrode lines 50 and connects the shorted scan electrode lines 40 with VCC power.

At this time, if the scan electrode lines 40 are all connected to the VCC power supply in a short circuit state, the voltage of the scan electrode lines is changed from 1/2 VCC to VCC. In this case, the column electrode lines 50 are all floating. Therefore, it is also raised from 1/2 VCC to VCC so that there is no potential difference at both ends.

10 and 11 illustrate a second scan electrode line S-2 which is a third step of the driving method according to the present invention in the step of driving the second scan electrode line in the driving method according to the present invention, and the corresponding column. The state in which the organic EL element is made to emit light by applying a voltage to the electrode line is shown.

Referring to FIG. 10, a switch shorted to the VCC voltage is opened in the external switch unit 60, and the second scan electrode line S_2 to be selected is switched to the GND voltage 22 to be selected, and the rest of the scan is performed. The electrode lines S_1, S_3, S_4,..., S_N are switched to the VCC voltage 11 and are selected.

As shown in FIG. 11, when the second scan electrode line S_2 is selected, a corresponding current source 21 of the column electrode driver 20 is switched and selected to supply a predetermined amount of current to the corresponding column electrode line. The organic EL element emits light.

FIG. 11 shows that currents are supplied to C_1, C_2, C_3, C_M-2, CM-1, and C_M column electrode lines among the M column electrode lines, and the organic EL elements of the second line corresponding thereto emit light. have.

12A and 12B show voltage waveforms of column electrode lines of an organic EL display according to a conventional driving method and voltage waveforms of column electrode lines of an organic EL display according to the present invention.

As shown in FIG. 12 (a), the conventional driving method requires a pre-charge driving circuit to raise the voltage of the column electrode line to VCC instantaneously, but as shown in FIG. According to the driving method according to the present invention, no pre-charge driving circuit is required.

As described above, the driving method according to the present invention has a merit of increasing the voltage faster than the pre-charging method because the driving method increases the voltage in a floating state. In addition, since the column electrode line is floating, no power consumption is required to charge the voltage of the column electrode line to VCC.

This is because there is no potential difference between the anode electrode and the cathode electrode in the short circuit process, and there is no potential difference between the anode electrode and the cathode electrode even when the voltage is increased to VCC after the floating state.

Therefore, when the driving method according to the present invention is applied to the passive matrix organic EL display, the power consumed to charge the voltage of the column electrode line to VCC is reduced, and the organic EL is also charged faster than the conventional driving method. The time for supplying the current increases. Accordingly, there is an advantage that the power consumption can be reduced by increasing the luminous efficiency of the organic EL device.

The driving method according to the present invention described above is a driving method in which the column electrode line is maintained in a floating state and the column electrode line is raised to VCC while charging the scan electrode line with VCC.

On the contrary, as shown in FIG. 13, after shorting the column electrode line 50 and the scan electrode line 40, the scan electrode line is floated, and the column electrode line is charged with the VCC voltage. At the same time, in the case of using the driving method of raising the scan electrode line to VCC, the above-described effects of the present invention can be enjoyed.

In the driving method described above, the VCC power supply is applied to a non-floating electrode line after shorting all scan electrode lines and all column electrode lines, then floating one of the scan electrode lines and column electrode lines. Is applied to charge the remaining electrode lines to VCC.

In another embodiment, after short-circuiting all the scan electrode lines 40 and all the column electrode lines 50, driving to make the voltages the same at both ends by simultaneously applying VCC power without floating the scan electrode lines and the column electrode lines. Even in the case of the method, it is possible to enjoy the same effects of the present invention described above.

14 to 16 are views illustrating a method of driving the first scan electrode line in the driving method according to the present invention.

As shown in FIG. 14, the first step of the present invention shorts all column electrode lines 50 and all scan electrode lines 40.

As shown in FIG. 15, in the second step of the present invention, all column electrode lines 50 and all scan electrode lines 40 are short-circuited at the same time through the external switch unit 60 to the column electrode lines and the scan electrode lines. The VCC power is applied to charge the organic EL element up to the VCC voltage.

Next, as shown in FIG. 16, the organic EL device emits light by supplying current from the current source 21 of the column electrode driver 20 to the corresponding column electrode line.

The driving apparatus and driving method of the organic EL panel according to the present invention as described above have the following effects.

First, the power consumed to charge the column electrode line can be reduced.

Second, compared with the conventional pre-charge method, the time taken to charge the column electrode line to VCC can be shortened. Therefore, the organic EL device can be supplied with more current to the organic EL device than the conventional driving method. The power consumption of the organic EL display can be reduced by increasing the luminous efficiency of the device.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

1 is a diagram showing a passive matrix organic EL display device and a driver driver according to the prior art;

2 is a diagram showing an internal equivalent circuit of unit pixels of an organic EL display according to the prior art;

Fig. 3 shows a passive matrix organic EL display device and drive driver according to the present invention.

4 to 7 are views illustrating a method of driving the first scan electrode line in the driving method according to the present invention.

8 to 11 are views illustrating a method of driving a second scan electrode line in a driving method according to the present invention.

12 (a) and (b) are diagrams showing a driving waveform diagram according to a conventional driving scheme and a driving waveform diagram according to the present invention.

Fig. 13 shows another embodiment of a passive matrix organic EL display device and drive driver according to the present invention;

14 to 16 illustrate a method of driving the first scan electrode line in the driving method according to the present invention.

* Explanation of symbols for main parts of the drawings

10 scan electrode driver 11 VCC power supply

12: GND power supply 13, 23: switch

20: column electrode driver 21: current source

22: sink portion 30: organic EL panel portion

40: scan electrode line 50: column electrode line

60: external switch unit

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Claims (9)

A scan electrode driver for outputting a signal for sequentially selecting scan electrode lines of the organic EL display; A column electrode driver for supplying or charging a constant current to the column electrode lines or discharging the charged electric charges; An organic EL panel unit emitting light in accordance with signals output from the scan electrode driver and the column electrode driver; And an external switch unit for tying all the scan electrode lines and all the column electrode lines into one. The method of claim 1, wherein the scan electrode driver A ground (GND) power source for selecting a scan electrode line switched and driven for each scan electrode line; A VCC power supply which is switched to a non-driven scan electrode line other than the GND power supply to apply a predetermined voltage; And a switch unit electrically connected to the external switch unit to bind all the scan electrode lines into one. The method of claim 1, wherein the column electrode driver A current source for supplying a constant current to the organic EL pixel for each column electrode line; A sink unit capable of discharging the charge charged in the column electrode line through the current source; And a switch unit electrically connected to the external switch unit to bind all the column electrode lines into one. The method of claim 1, wherein the external switch unit A switch that can bundle all the scan electrode lines and all the column electrode lines at the same time; And a voltage source for supplying VCC power to the scan electrode lines when all of the scan electrode lines are grouped together. Electrically shorting all column electrode lines and all scan electrode lines with each other so that there is no potential difference in all column electrode lines and all scan electrode lines; Maintaining only the column electrode lines in a floating state by opening all of the column electrode lines and all of the electrically connected column electrode lines and all scan electrode lines; Disconnecting the column electrode lines from all the electrically connected scan electrode lines and then connecting VCC power to maintain the voltages of all the scan electrode lines at VCC; Connecting all the scan electrode lines and the column electrode lines in the floating state to maintain a voltage VCC at all the column electrode lines and all the scan electrode lines; Selecting the corresponding scan electrode line to emit light, and applying a voltage to the corresponding column electrode line to emit light of the organic EL element; And repeating the above process until all of the scan electrode lines are selected. The method of claim 5, And all of the column electrode lines maintained in the floating state to all of the scan electrode lines, and all of the scan electrode lines connecting the VCC power source to all of the column electrode lines. Electrically shorting all column electrode lines and all scan electrode lines with each other so that there is no potential difference in all column electrode lines and all scan electrode lines; Simultaneously connecting the VCC power supply to all the electrically connected column electrode lines and the scan electrode lines to maintain the voltages of all the column electrode lines and all the scan electrode lines at VCC; Selecting the corresponding scan electrode line to emit light, and applying a voltage to the corresponding column electrode line to emit light of the organic EL element; And repeating the above process until all of the scan electrode lines are selected. Electrically shorting all column electrode lines and all scan electrode lines with each other so that there is no potential difference in all column electrode lines and all scan electrode lines;  Maintaining only the column electrode lines in a floating state by opening all of the column electrode lines and all of the electrically connected column electrode lines and all scan electrode lines; Disconnecting the column electrode lines from all the electrically connected scan electrode lines and then connecting VCC power to maintain the voltages of all the scan electrode lines at VCC; Connecting all the scan electrode lines and the column electrode lines in the floating state to maintain a voltage VCC at all the column electrode lines and all the scan electrode lines; Selecting the corresponding scan electrode line to emit light, and applying a voltage to the corresponding column electrode line to emit light of the organic EL element; Discharging the charges charged in the column electrode line by grounding the column electrode line to ground after the organic EL element emits light for a predetermined time; And repeating the above process until all of the scan electrode lines are selected. Electrically shorting all column electrode lines and all scan electrode lines with each other so that there is no potential difference in all column electrode lines and all scan electrode lines; Simultaneously connecting the VCC power supply to all the electrically connected column electrode lines and the scan electrode lines to maintain the voltages of all the column electrode lines and all the scan electrode lines at VCC; Selecting the corresponding scan electrode line to emit light, and applying a voltage to the corresponding column electrode line to emit light of the organic EL element; Discharging the charges charged in the column electrode line by grounding the column electrode line to ground after the organic EL element emits light for a predetermined time; And repeating the above process until all of the scan electrode lines are selected.