KR20070122254A - Apparatus and method for driving organic electro luminescence display - Google Patents

Abstract

A driving apparatus of an organic electro-luminescence display device is provided to improve uniformity of a display screen and to reduce a luminance difference by supplying previously an electric charge difference to a data electrode line. A scan electrode line driving unit(10,11) applies sequentially scan pulses to a plurality of scan electrode lines. An electric potential difference generation unit(12) generates an electric potential difference corresponding to an electric potential difference generated from one scan electrode line of the scan electrode lines by using electric charges discharged from organic electro-luminescence cells, external current, and an external voltage. A power supply unit(14,15) supplies the voltage or the current to the electric potential difference generation unit. A data electrode line driving unit(16) supplies the predetermined current to data electrode lines in order to generate the light from the electro-luminescence cells.

Description

Apparatus and Method for Driving Organic Electro Luminescence Display

1 is a view showing a structure according to an embodiment of a conventional passive matrix organic light emitting device.

2 is a view showing a structure according to another embodiment of a general passive matrix organic light emitting device.

3A and 3B are views illustrating a structure of a passive matrix organic light emitting device according to an embodiment of the present invention.

4 is a view showing the structure of a passive matrix organic light emitting device according to another embodiment of the present invention.

5 and 6 illustrate a method of driving the passive matrix organic light emitting device shown in FIG. 3.

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

10, 11: scan electrode line driver 12: potential difference generator

14, 15: power supply unit 16: data electrode line driver

18: EL cell 20: panel

22: resistance heat 23: discharge switch

28: first switch 34: second switch

36: current source 38: third switch

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting device, and more particularly, to a driving device and a method of driving an organic light emitting device that can improve image quality by reducing a comb pattern and cross-talk effects.

Recently, various flat panel displays have been developed to reduce weight and volume, which are disadvantages of cathode ray tubes. Such flat panel displays include Liquid Crystal Display, Field Emission Display, Plasma Display Panel, and Electro-Luminescence. ) Display devices. Among these, an electroluminescent display device is a self-luminous device that emits a fluorescent material by recombination of electrons and holes, and is classified into an inorganic light emitting device and an organic light emitting device according to its material and structure. Compared to the passive light emitting device requiring a separate light source such as a liquid crystal display, such an electro-luminescence display device has a fast response speed at the same level as a cathode ray tube, and has a low DC driving voltage and an ultra thin film. It has the advantage of being portable.

FIG. 1 illustrates a passive matrix organic light emitting diode (PMOLED) of the organic light emitting diode, and the organic light emitting diode includes an intersection portion between scan electrode lines S1 -Sn and data electrode lines D1 -Dm. EL cells 2 arranged every time are provided. Each of the EL cells 2 is selected when a scan pulse is applied to the scan electrode lines S1 to Sn, which are cathodes, to generate light corresponding to a pixel signal, that is, a current signal, supplied to the data electrode line, which is a cathode. Each of the EL cells 2 is formed at each intersection of the data electrode line and the scan electrode line S1 to Sn and is equivalently represented by a diode.

Each of the EL cells 2 is supplied with the scan pulse of the negative polarity generated from the scan electrode line driver 4 to the scan electrode lines S1 to Sn, and at the same time according to the data signal generated from the data electrode line driver 6. A positive current is applied to the data electrode line to emit light when a forward voltage is applied. In this case, the reverse direction voltage is applied to the EL cells 2 included in the scan electrode lines S1 to Sn that are not selected, so that they do not emit light. In other words, the EL cells 2 that emit light are charged with the forward charge while the EL cells 2 that do not emit the light are charged with the reverse charge.

However, in the passive organic light emitting device as illustrated in FIG. 1A, since resistive components exist in the data electrode lines and the scan electrode lines S1 to Sn, the luminance difference in one scan electrode line is illustrated as shown in FIG. 1B. Is generated and displayed on the panel 8, the screen becomes uneven. That is, EL disposed on one scan electrode line S1 to Sn by a resistance component present in the scan electrode lines S1 to Sn and a current flowing through the scan electrode line in one scan electrode line S1 to Sn. The potential difference is generated between the cells 2, so that the EL cells 2 far from the scan electrode line driver 4 are darker than the EL cells 2 having a shorter distance.

To improve this, as shown in FIG. 2A, the scan electrode line driver 4 is disposed on both sides of the panel 8, and the scan electrode lines S1 to Sn are connected to either of the scan electrode line driver 4 on both sides. There has been presented an alternatingly connected driving device, which has the advantage that the display screen is located in the center of the panel 8, but the odd-numbered scan electrode lines S1, S3, ..., Sn-1 ) And the even-numbered scan electrode lines (S2, S4, ..., Sn) are connected in different directions, so as shown in FIG. 2B, the light and dark portions in one scan electrode line (S1 to Sn) There is a problem that a comb-tooth effect occurs, which is a phenomenon appearing alternately for each line.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and generates a potential difference to be generated on the scan electrode line by using the charge stored in the EL cell and an external power supply, and then supplies the data difference to the data electrode line in advance to improve the uniformity of the display screen. It is a technical object of the present invention to provide a driving apparatus and a driving method of an organic light emitting element.

An organic light emitting device driving apparatus according to an aspect of the present invention for achieving the above object is a scan electrode line driver for sequentially applying a scan signal to a plurality of scan electrode lines, the charge discharged from the EL cell and from the outside A potential difference generator for generating a potential difference corresponding to a potential difference generated on any one of the plurality of scan electrode lines by using the supplied current or voltage, and supplying the generated potential difference to the data electrode line; And a data electrode line driver for supplying a predetermined current to the plurality of data electrode lines to emit light of the EL cells.

In this case, the plurality of data electrode lines may be arranged to intersect the resistance column in order to supply the potential difference generated by the potential difference generator to the data electrode line.

According to another aspect of the present invention, there is provided a method of driving an organic light emitting device, by applying a current or voltage to a potential difference generator and simultaneously discharging electric charges stored in the EL cell to the potential difference generator. Generating a potential difference corresponding to a potential difference to be generated on any one of the plurality of scan electrode lines, and supplying the potential difference generated by the potential difference generator to each data electrode line connected to the potential difference generator; And causing the EL cells to emit light by applying a driving current corresponding to a predetermined data signal to the data electrode line.

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

3A illustrates a driving device of an organic light emitting diode according to an exemplary embodiment of the present invention. As shown, the driving device of the organic light emitting diode includes the scan electrode line drivers 10 and 11, the potential difference generator 12, the power supply units 14 and 15, the data electrode line driver 16, and a plurality of EL cells ( A panel 20 consisting of 18).

The scan electrode line drivers 10 and 11 select the scan electrode lines S1 to Sn to display data by sequentially applying negative scan signals to the plurality of scan electrode lines S1 to Sn. In order to be located at the center of the panel 20, the scan electrode line driving units 10 and 11 are composed of two. Odd-numbered scan electrode lines S1, S3,..., Sn-1 are connected to the first scan electrode line driver 10, and even-numbered scan electrode lines S2 are connected to the second scan electrode line driver 11. S4, ..., Sn) are connected. Of course, even-numbered scan electrode lines S2, S4, ..., Sn are connected to the first scan electrode line driver 10, and odd-numbered scan electrode lines S1, S3 are connected to the second scan electrode line driver 11, of course. It is obvious that it is possible to connect, ..., Sn-1).

The potential difference generator 12 is for generating a potential difference equal to the potential difference generated on the scan electrode lines S1 to Sn by using the discharged electric charge and the current or voltage supplied from the power supply units 14 and 15. It is provided in the data electrode line driver 14. The potential difference generator 12 is composed of a resistor string 22 and a discharge switch 23, the resistor string 22 being equivalent to resistors existing in any one of the scan electrode lines S1 -Sn. It consists of a plurality of resistors 21 connected in series with each other, and the discharge switch 23 discharges the electric charges stored in the EL cells 18 into the resistance column 22.

The power supply units 14 and 15 supply a voltage or a current to the potential difference generating unit. The power supply units 14 and 15 may include a first power supply unit 14 and a second power supply unit 15 to supply a current or voltage to the resistor string 22. Apply alternately. The first power supply unit 14 includes a first current source 24 for supplying a current to the resistor row, a first voltage source 26 for supplying a voltage to the resistor row 22, the first current source 24, and a first current source 24. A first switch 28 for selectively connecting one voltage source 26 to the resistor string 22, and the second power supply 15 supplies a second current source 30 for supplying current to the resistor string 22. ), A second voltage source 32 for supplying a voltage to the resistor row, and a second switch 34 for selectively connecting the second current source 30 and the second voltage source 32 to the resistor row 22.

In the present embodiment, the switching operation of the first and second switches 28 and 34 is determined according to the driving of the scan electrode lines S1 to Sn. Specifically, first, as shown in FIG. 3A, when the first scan electrode line driver 10 is driven to apply a scan pulse to the odd-numbered scan electrode lines S1, S3,..., Sn-1. The first switch 28 connects the first voltage source 26 and the resistor row 22, and the second switch 34 connects the second current source 34 to the resistor row 22, as shown in FIG. 3B. As described above, when the second scan electrode line driver 11 is driven to apply a scan pulse to the even-numbered scan electrode lines S2, S4, ..., Sn, the second switch 34 generates a second voltage source. The 32 and the resistor string 22 are connected, and the first switch 28 connects the first current source 26 to the resistor string 22.

As a modified embodiment, the first switch when the first scan electrode line driver 10 is driven to apply a scan pulse to the odd-numbered scan electrode lines S1, S3, ..., Sn-1. 28 connects the first voltage source 26 and the resistor row 22, and the second switch 34 connects the second current source 30 to the resistor row 22, and the second scan electrode line driver 11. ) Is driven so that the second switch 34 connects the second voltage source 32 and the resistor string 22 when a scan pulse is applied to the even-numbered scan electrode lines S2, S4, ..., Sn. In addition, the first switch 28 may connect the first current source 24 to the resistor row 22.

As another embodiment in which the above embodiment is modified, referring to FIG. 4, the first scan electrode line driver 10 is driven to scan pulses on odd-numbered scan electrode lines S1, S3,..., Sn-1. Is applied or scan pulses are applied to the even-numbered scan electrode lines S2, S4, ..., Sn, the first switch 28 connects the first voltage source 26 to the resistor string 22 and The second switch 34 may connect the second voltage source 32 to the resistor row 22. In this case, the voltage level of the first voltage source 26 and the voltage level of the second voltage source 32 are preferably different.

Referring again to FIG. 3A, the data electrode line driver 16 emits light to the EL cells 18 by supplying a predetermined current to the data electrode lines D1 to Dm. The data electrode line driver 16 emits a predetermined data signal to the data electrode line driver 16. And a third switch 38 for selectively connecting the current source 36 to supply a current corresponding thereto, and the current source 36 and the data electrode lines D1 to Dm.

The driving method of the organic light emitting diode according to the embodiment of the present invention described above will be described in detail.

As shown in FIG. 5, first, the plurality of discharge switches 23 are all turned on to discharge charges previously applied to the EL cells 18 through the resistor string 22, and at the same time, the power supply unit 14, The first and second switches 28 and 34 provided in the 15 connect the current sources 24 and 30 or the voltage sources 26 and 32 to the resistor rows 22 so that the resistor rows 22 of the potential difference generator 12 can be used. ) Similar to the potential generated when the scan electrode line is actually driven. That is, in the present invention, the resistor constituting the resistor row 22 by artificially supplying the resistor row 22 with current or voltage and discharging the electric charges stored in the EL cell 18 through the resistor row 22. It will generate a potential difference between the (21).

In this case, the first and second switches 28 and 34 connected to both ends of the resistance string 22 are first or second to generate a potential difference between the resistors 21 constituting the resistance string 22 of the potential difference generator 12. Switching is performed in correspondence with driving timings of the second scan electrode line drivers 10 and 11. Specifically, as illustrated in FIG. 3A, odd-numbered scan electrode lines S1, S3,..., And Sn-1 are connected to the first scan electrode line driver 10, and the second scan electrode line driver is connected to the first scan electrode line driver 10. When even-numbered scan electrode lines S2, S4,..., Sn are connected to 11, when the first scan electrode line driver 10 is driven, the first switch 28 may include a first current source ( 24 and the resistor row 22 are connected, and the second switch 34 connects the second voltage source 32 and the resistor row 22. As shown in FIG. 3B, the second scan electrode line driver 11 is illustrated. ) Is driven, the second switch 34 connects the second current source 30 and the resistor string 22, and the first switch 28 connects the first voltage source 26 and the resistor string 22.

Next, as shown in FIG. 6, the first switch, the second switch, and the discharge switches 28, 34, and 23 are all turned off, and the third switch 38 is turned on to correspond to a predetermined data signal. Is applied to the data electrode lines D1 to Dm to cause the EL cells 18 to emit light. By repeating this process for each scan electrode line (S1 ~ Sn) it is to improve the comb pattern and cross-talk effect generated in the scan electrode line (S1 ~ Sn).

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. For example, in the above-described embodiment, since the scan electrode line driver is composed of two, the power supply is described as being composed of two. However, as a modified embodiment, when the scan electrode line driver is implemented by one, the power supply is also one. The power supply unit is disposed on the side of the resistance column where voltage is applied to the scan electrode line. In this case, the switch connecting the voltage source or the current source with the resistor string is connected to the voltage source or the current source during the period for generating the potential difference in the resistor string, and is turned off in other sections.

Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

As described above, according to the present invention, the potential difference to be generated in the actual scan electrode line is generated by using the charge stored in the EL cell and the external power source, and then applied to the data electrode line to generate the potential difference. The luminance difference can be reduced.

In addition, according to the present invention, it is possible to remove the comb pattern by reducing the luminance difference generated on one scan electrode line, thereby improving the uniformity of the display screen.

Claims (9)

An apparatus for driving an organic light emitting device, comprising: a panel comprising a plurality of scan electrode lines, a plurality of data electrode lines, and EL cells disposed at intersections of the plurality of scan electrode lines and data electrode lines; A scan electrode line driver sequentially applying scan signals to the plurality of scan electrode lines; A potential difference corresponding to a potential difference generated on any one of the plurality of scan electrode lines is generated by using a charge discharged from the EL cell and a current or voltage supplied from the outside, and the generated potential difference is converted into the data electrode line. A potential difference generator for supplying the power to the potential generator; A power supply unit supplying a voltage or a current to the potential difference generator; And A data electrode line driver supplying a predetermined current to the plurality of data electrode lines to emit light of the EL cells; Driving device for an organic light emitting device comprising a. The method of claim 1, wherein the potential difference generator A resistor string comprising a plurality of resistors connected in series as equivalents of the resistors present in any one of the plurality of scan electrode lines; And A plurality of discharge switches connected to the resistance row so that the charge stored in the EL cell can be discharged to the resistance row when it is turned on; Driving device for an organic light emitting device comprising a. The driving device of claim 2, wherein each of the data electrode lines is disposed to intersect the resistance column in order to supply the potential difference generated by the potential difference generator to the data electrode line. The driving device of claim 2, wherein the power supply unit includes a first power supply unit and a second power supply unit and is disposed at both ends of the resistance string. The method of claim 4, wherein the first power supply unit, A first current source for supplying current to the resistance heat; A first voltage source supplying a voltage to the resistance column; And A first switch for selectively connecting the first current source and the first voltage source to the resistor string; Includes, the second power supply unit, A second current source for supplying current to the resistance heat; A second voltage source supplying a voltage to the resistance column; And A second switch for selectively connecting the second current source and the second voltage source to the resistor string; Driving device for an organic light emitting device comprising a. The method of claim 5, wherein the first switch and the second switch connect the first current source to the resistor string when the voltage is applied from the left side in the direction in which the voltage is applied to the scan electrode line. A switch connects a second voltage source to the resistor string, and when a voltage is applied on the right side, the first switch connects the first voltage source to the resistor string and the second switch connects a second current source to the resistor string. Driving device of organic light emitting element. The method of claim 5, wherein the first and second switches connect the first voltage source to the resistor string when the voltage is applied from the left side in the direction in which the voltage is applied to the scan electrode line. A switch connects a second current source to the resistor string, and when a voltage is applied on the right side, the first switch connects the first current source to the resistor string and the second switch connects a second voltage source to the resistor string. Driving device of organic light emitting element. The method of claim 1, wherein the data electrode line driver, A current source for applying a predetermined current to the data electrode line; And A third switch selectively connecting the current source and the data electrode line to emit light of the EL cells; Driving device for an organic light-emitting device further comprises. A driving method of an organic light emitting device including a plurality of scan electrode lines and a plurality of data electrode lines, and an EL cell disposed at an intersection point of the plurality of scan electrode lines and a data electrode line. A potential difference corresponding to a potential difference to be generated on any one of the plurality of scan electrode lines is discharged by applying a current or voltage to the potential difference generator and discharging the electric charges previously stored in the EL cell to the potential difference generator. Generating; Supplying a potential difference generated by the potential difference generator to the data electrode line connected to the potential difference generator; And Emitting light of the EL cells by applying a driving current corresponding to a predetermined data signal to the data electrode line; Method of driving an organic light emitting device comprising a.

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