KR20020018269A - Driving circuit and method of an organic electro luminescence display device - Google Patents

Abstract

PURPOSE: The circuit and method for driving organic electroluminescence display device are provided to prevent a driving velocity of the organic electroluminescence devices from getting slow by increasing a capacitance of the capacitor connected to the organic electroluminescence devices. CONSTITUTION: An organic electroluminescence display panel(10) is provided with a plurality of scan lines(S1-Sm) and a plurality of data lines(D1-Dn) aligned in a matrix form, and a plurality of organic electroluminescence devices(EL) disposed between each of the plurality of the scan lines and data lines. A scan line driving unit applies a selective voltage to the plurality of scan lines in turn. A data driving unit applies data corresponding to the selected scan line by the scan line driving unit to the plurality of the data lines. The scan line driving unit applies a first selective voltage during an initial predetermined period applied by the selective voltage and applies a second selective voltage higher than the first selective voltage during the rest period.

Description

Driving circuit and method of organic electroluminescent display device

The present invention relates to an organic electroluminescence (EL) display device, and more particularly, to a driving circuit and a method of an organic electroluminescent display device capable of improving an initial driving speed of the organic electroluminescent display device.

The organic electroluminescent display device is a self-luminous display device which electrically excites fluorescent organic compounds to emit light, and can be driven at a low voltage and has advantages such as thinness.

Such organic electroluminescent display devices are emerging for use in small portable electronic devices, such as small devices such as pagers, cellular phones, cell phones, two-way radios, data banks, and the like. Organic electroluminescent display devices can generate sufficient light for a display under various ambient environments. Furthermore, organic electroluminescent display devices can be manufactured relatively inexpensively and can be manufactured in a variety of sizes, from very small to large.

When the organic electroluminescent display is initially driven, an initial current is charged in a capacitor connected to the organic electroluminescent elements. However, as the number of organic ELs in the organic electroluminescent display panel increases, the capacitance of the capacitors connected to the organic electroluminescent elements also increases, and more current is required for initial charging. Because the charging time of the capacitor depends not only on the capacitance of the capacitor, but also on the resistance coupling the current source to the capacitor, and the driving speed decreases as the capacitance of the capacitor increases.

Therefore, the conventional organic electroluminescent display device has a problem in that when a large number of organic electroluminescent elements are disposed in a panel, the driving speed is slowed by increasing the capacitance of a capacitor connected to the organic electroluminescent elements.

This problem becomes more serious as a high resistance material such as indium-tin-oxide (ITO) is used as the conductive transparent layer.

1 is a circuit diagram of an embodiment of a conventional organic electroluminescent display device, which includes a precharge circuit 40 ', a current source 22', a data output circuit 10 ', a scan line driving circuit Q3, and an ITO resistor Rnito. ), An organic EL 11 ', and a capacitor 12'.

The operation of the circuit shown in FIG. 1 will now be described.

The precharge circuit 40 'inputs a negative pulse signal applied to the input terminal 23' to differentiate by the capacitor 45 'and the resistor 47', and transmits the differentiated signal to the operational amplifier 46 '. Amplify by The transistor Q1 constituting the current source 22 'initially flows a large amount in response to the output signal of the precharge circuit 40', and then flows a current i1 that gradually decreases.

In addition, when the negative pulse signal is applied through the input terminal 23 ', the transistor Q2 constituting the driving circuit 10' is turned on to flow the current i1. At this time, a large amount of current i1 flows initially by the transistor Q1 and then gradually decreases current i1.

When a selection signal is applied to the scan line, a large amount of current is initially supplied to the capacitor 12 'to quickly charge, thereby supplying a large amount of current id through the organic EL 11', thereby increasing the charging time. As a result, the problem of slowing the driving speed of the organic EL 11 'can be improved.

That is, the conventional method of driving the organic electroluminescent display device shown in FIG. 1 controls the amount of current flowing through the current source 22 'by the precharge circuit 40', and initially to the organic EL 11 '. By flowing a large amount of current through the connected capacitor 12 ', it is possible to improve the problem that the driving speed becomes slow even if the capacitance of the capacitor 12' is increased.

However, the driving circuit of the conventional organic electroluminescent display device shown in FIG. 1 has a problem in that its configuration is complicated by providing a precharge circuit in each of the output circuits for generating the scan line selection signal.

SUMMARY OF THE INVENTION An object of the present invention is to provide a driving circuit of an organic electroluminescent display device having a simple circuit configuration and improving the problem of slow initial driving speed as the number of organic electroluminescent elements constituting the organic electroluminescent display panel increases. .

Another object of the present invention is to provide a method of driving an organic electroluminescent display device for achieving the above object.

A first aspect of the driving circuit of the organic electroluminescent display device of the present invention for achieving the above object is a plurality of scan lines and a plurality of data lines arranged in a matrix form and the plurality of scan lines and the plurality of An organic electroluminescent display panel having a plurality of organic electroluminescent elements disposed between each of the data lines, scan line driving means for sequentially applying a selection voltage to the plurality of scan lines, and the scan line driving means. Data driving means for applying data corresponding to the scan line selected by the to the plurality of data lines, wherein the scan line driving means applies a first selection voltage during an initial predetermined period during which the selection voltage is applied; And applying a second selection voltage higher than the first selection voltage for the remaining period. And that is characterized.

A second aspect of the driving circuit of the organic electroluminescent display device of the present invention for achieving the above object is a plurality of scan lines and a plurality of data lines arranged in a matrix form and the plurality of scan lines and the plurality of An organic electroluminescent display panel having a plurality of organic electroluminescent elements disposed between each of the data lines, scan line driving means for sequentially applying a selection voltage to the plurality of scan lines, and the scan line driving means. Data driving means for applying data corresponding to the scan line selected by the plurality of data lines to the plurality of data lines, wherein the data driving means responds to the data during an initial predetermined period during which the selection voltage is applied. Flow a first current through the data lines, and A first current smaller than the first current flows.

A first aspect of the method of driving the organic electroluminescent display device of the present invention for achieving the above another object is a plurality of scan lines and a plurality of data lines arranged in a matrix form and the plurality of scan lines and the plurality of A method of driving an organic electroluminescent display device having an organic electroluminescent display panel having a plurality of organic electroluminescent elements disposed between each of the data lines, the method comprising: an initial predetermined period during which a selection signal is applied to the scan line; The first step of applying a voltage lower than the selected voltage during the period, and applying the selection voltage for the remaining period of the selection signal is applied to the scan line, the data corresponding to the selected scan line in the period of the selection signal is applied A second step of applying to the plurality of data lines, and the plurality of And a third step of sequentially performing the first and second steps on each of the three scan lines.

A second aspect of the method of driving the organic electroluminescent display device of the present invention for achieving the above another object is a plurality of scan lines and a plurality of data lines arranged in a matrix form and the plurality of scan lines and the plurality of A method of driving an organic electroluminescent display device having an organic electroluminescent display panel having a plurality of organic electroluminescent elements disposed between each of the data lines, the method comprising: applying a selection signal to the scan line to perform a corresponding scan In a first step of selecting a line, a first current flows through the plurality of data lines in response to the data during an initial predetermined period when the selection signal is applied when data of the corresponding scan line is applied, and the selection signal In response to the data for the remaining period of time And a third step of flowing a second current smaller than the first current through the second lines, and a third step of sequentially performing the first and second steps with respect to each of the plurality of scan lines. do.

1 is a circuit diagram of an embodiment of a conventional organic electroluminescent display device.

2 is a block diagram showing the configuration of a general organic electroluminescent display device.

FIG. 3 is an operation timing diagram for describing a method of driving the organic electroluminescent display panel shown in FIG. 2.

4 shows the configuration of an organic electroluminescent display device according to an embodiment of the present invention.

FIG. 5 is an operation timing diagram for describing a method of driving the organic light emitting display device illustrated in FIG. 4.

6 shows a configuration of an organic electroluminescent display device of another embodiment of the present invention.

FIG. 7 is an operation timing diagram for describing a method of driving the organic electroluminescent display device illustrated in FIG. 6.

Hereinafter, a driving circuit and a method of a general organic electroluminescent display device will be described before explaining the driving circuit and method of the organic electroluminescent display device of the present invention with reference to the accompanying drawings.

FIG. 2 is a block diagram showing the structure of a general organic electroluminescent display device, and is composed of an organic electroluminescent display panel 10, a data output circuit 12, and a scan line selection signal output circuit 14. As shown in FIG.

The organic electroluminescent display panel 10 includes organic electrons connected in parallel between each of the m scan lines S1, S2,..., Sm and the n data lines D1, D2..., Dn. It consists of a light emitting element EL and a capacitor C. The data output circuit 12 is connected to each of the n data lines D1, D2,..., Dn, and a PMOS transistor P1 and an NMOS transistor connected in series between the data line select voltage SS and the ground voltage. It consists of the inverter I1 comprised by N1). The scan line select signal output circuit 14 is connected to each of the m scan lines S1, S2, ..., Sm, and a PMOS transistor P2 and an NMOS connected in series between the unselected voltage CN and the ground voltage. It consists of an inverter I2 comprised of the transistor N2.

The block diagram shown in FIG. 2 shows an output circuit when the data line non-selection voltage and the scan line select voltage are set to the ground voltage.

In general, a data driving circuit for driving a data line and a scan line driving circuit for driving a scan line are configured by a shift register, a latch, a level shifter, and an output circuit dependently coupled. Only the configuration of the output circuit is shown except for the configuration of the shift register, the latch, and the level shifter.

The operations of the data output circuit and the scan line selection signal output circuit shown in FIG. 2 will be described below.

The data output circuit 12 outputs n data d1, d2, ..., dn to n data lines D1, D2, ..., Dn. The scan signal output circuit 14 outputs m scan signals s1, s2, ..., sm to m scan lines S1, S2, ..., Sm. The organic electroluminescent display panel 10 selects organic light emitting elements connected to the scan line in response to a ground voltage applied to the scan line.

FIG. 3 is an operation timing diagram for describing a method of driving the organic electroluminescent display panel shown in FIG. 2.

The scan line selection signal output circuit 14 sequentially applies a selection signal to m scan lines S1, S2, ..., Sm. The data output circuit 12 outputs data of the corresponding scan line to the n data lines D1, D2, ..., Dn.

That is, m scan lines S1, S2,..., Sm are sequentially selected and data is output to the corresponding scan line.

However, in the conventional organic electron emission display panel as described above, as the number of organic ELs increases, the capacitance of the capacitor C connected to the organic ELs increases, so that the initial charging time of the capacitor C also slows down. do.

Therefore, the emission speed of the organic electroluminescent devices is slowed down, and the problem becomes more serious as a resistive material such as indium tin oxide is used.

FIG. 4 shows the structure of an organic electroluminescent display device according to an embodiment of the present invention. The structure of the organic electroluminescent display panel 10 and the scan line selection signal output circuit 14 are the same as those shown in FIG. The PMOS transistor P3 is added to the inverter I1 constituting the data output circuit 12.

That is, a PMOS transistor P3 having a drain connected to the source of the PMOS transistor P1 constituting the inverter I1, a source to which the selection voltage SS is applied, and a gate to which the control signal CI is applied is added. It is.

The data output circuit 12 shown in Fig. 4 is applied to the n data lines D1, D2, ..., Dn for a predetermined time initially when the selection voltage is applied to the corresponding scan line. In order to increase the amount of current, the voltage level of the control signal CI is reduced. As a result, a large amount of current flows through the capacitor C connected to the organic ELs at the initial stage when the selection voltage is applied to the corresponding scan line, thereby increasing the capacitance of the capacitor C, thereby reducing the driving speed. Can be.

FIG. 5 is an operation timing diagram for describing a method of driving the organic light emitting display device illustrated in FIG. 4.

When the selection voltage CS of the ground voltage level is sequentially applied to the m scan lines S1, S2,..., Sm, corresponding scan lines are sequentially selected. The PMOS transistor P3 of the data output circuit 12 is lowered by lowering the voltage level of the control signal CI during the initial period T2 of the period T1 when the selection voltage CS is applied to the corresponding scan line. A large amount of current flows through it. A small amount of current flows through the PMOS transistor P3 of the data output circuit 12 by increasing the voltage level of the control signal CI during the remaining period T3 of the period T1 to which the selection voltage CS is applied. Let it flow

Accordingly, the n data lines D1, D2, ..., Dn are adjusted by adjusting the voltage level of the control signal CI applied to the gate of the PMOS transistor P3 constituting the data output circuit 12. Control the amount of current flowing through it.

As shown in Fig. 5, when the control signal CI of the low voltage level is applied during the period T2, the amount of current flowing through the PMOS transistor P3 is increased to the scan line to which the selection voltage CS is applied. A large amount of current i2 flows instantaneously through the capacitor C of the connected organic ELs. Accordingly, the problem that the driving speed is slowed down by increasing the capacitance of the capacitor C by flowing a large amount of current i2 through the capacitor C connected to the organic ELs at the beginning of the selection period T1 is solved. Can be.

FIG. 6 shows a configuration of an organic electroluminescent display device according to another embodiment of the present invention, wherein the organic electroluminescent display panel 10, the data output circuit 12, and the scan line selection signal output circuit 14 shown in FIG. It is configured in the same way as, and is configured such that the selection voltage CS is applied to the source of the NMOS transistor 14 of the scan line selection signal output circuit 14 only.

That is, the variable selection voltage CS is applied to the source of the NMOS transistor N2 of the inverter I2 constituting the scan line selection signal output circuit 14, not the ground voltage.

The scan line selection signal output circuit 14 shown in Fig. 6 lowers the voltage level of the selection voltage CS during an initial predetermined time when the selection voltage is applied to the scan line. In this way, the capacitor connected to the organic ELs from the n data lines D1, D2, ..., Dn by lowering the voltage level of the cathode of the organic ELs during the initial predetermined time when the selection voltage is applied to the corresponding scan line. A large amount of current flows in (C). Therefore, the problem that the driving speed becomes slow by increasing the capacitance of the capacitor C can be solved.

FIG. 7 is an operation timing diagram for describing a method of driving the organic electroluminescent display device illustrated in FIG. 6.

When the selection voltage CS is sequentially applied to the m scan lines S1, S2,..., Sm, the corresponding scan lines are sequentially selected. At this time, during the initial period T2 of the period T1 in which the selection voltage is applied to the corresponding scan line, the level of the selection voltage CS is lowered to m scan lines S1, S2,..., Sm. As the level of the applied voltage is lowered, a large voltage difference is generated in the capacitors C of the organic ELs, so that a large amount of current flows. The voltage of the voltage applied to the m scan lines S1, S2,..., Sm is increased by increasing the level of the selection voltage CS during the remaining period T3 of the period T1 to which the selection voltage is applied. The level goes up.

That is, in the period T2 within the period T1, a voltage lower than the ground voltage level is applied to the scan line, and in the period T3, the selection voltage CS is applied to the scan line by applying the ground voltage to the scan line. In the initial period T2 of the period T1, a large amount of current i2 flows through the capacitor C connected to the organic ELs. Therefore, the problem that the driving speed is slowed by increasing the capacitance of the capacitor C of the organic ELs is solved by charging a large amount of current i2 to the capacitor C connected to the organic ELs in the initial period T2. Can be.

That is, the driving circuit and the method of the organic electroluminescent display device of the present invention increase the amount of current flowing through the data lines in the initial stage when the selection voltage is applied to the scan line, or is applied to the scan line in the initial stage when the selection voltage is applied. By lowering the voltage level, a large amount of current is charged to the capacitors connected to the organic ELs.

Therefore, the problem that the driving speed of the organic ELs is lowered as the capacitance of the capacitor connected to the organic ELs is increased can be improved.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Accordingly, the driving circuit and method of the organic electroluminescent display device of the present invention can solve the problem that the driving speed of the organic electroluminescent devices is slowed down by the capacitance of the capacitor connected to the organic electroluminescent devices.

In addition, the driving circuit of the organic electroluminescent display device of the present invention can improve the driving speed of the organic electroluminescent elements with a simple circuit configuration.

Claims (6)

An organic electroluminescent display having a plurality of scan lines and a plurality of data lines arranged in a matrix and a plurality of organic electroluminescent elements disposed between each of the plurality of scan lines and the plurality of data lines. panel; Scan line driving means for sequentially applying a selection voltage to the plurality of scan lines; And Data driving means for applying data corresponding to the scan line selected by the scan line driving means to the plurality of data lines, The scan line driving means And applying a first selection voltage during an initial predetermined period during which the selection voltage is applied, and applying a second selection voltage higher than the first selection voltage for the remaining period. The method of claim 1, wherein the scan line driving means Each of the plurality of scan lines A pull-up transistor for applying a non-selection voltage to the scan line in response to a scan signal; And And a pull-down transistor configured to apply a selection voltage to the scan line in response to the scan signal. An organic electroluminescent display having a plurality of scan lines and a plurality of data lines arranged in a matrix and a plurality of organic electroluminescent elements disposed between each of the plurality of scan lines and the plurality of data lines. panel; Scan line driving means for sequentially applying a selection voltage to the plurality of scan lines; And Data driving means for applying data corresponding to the scan line selected by the scan line driving means to the plurality of data lines, The data driving means An organic electron flowing through the plurality of data lines in response to the data during an initial predetermined period during which the selection voltage is applied, and flowing a first current smaller than the first current for the remaining period of time; Driving circuit of a light emitting display device. The method of claim 3, wherein the data driving means Each of the plurality of data lines A control current source for flowing a first current for the initial predetermined period in response to a control signal and for flowing a second current for the remaining period; A first pull-up transistor configured to output a current flowing through the control current source to the data line in response to input data; And And a second pull-down transistor configured to output a data non-selection voltage to the data line in response to the input data. An organic electroluminescent display having a plurality of scan lines and a plurality of data lines arranged in a matrix and a plurality of organic electroluminescent elements disposed between each of the plurality of scan lines and the plurality of data lines. In the method of driving an organic electroluminescent display device provided with a panel, Applying a voltage lower than a selection voltage during an initial predetermined period during which a selection signal is applied to the scan line, and applying the selection voltage for the remaining period during which the selection signal is applied to the scan line; A second step of applying data corresponding to the selected scan line to the plurality of data lines while the selection signal is applied; And And a third step of sequentially performing the first and second steps with respect to each of the plurality of scan lines. An organic electroluminescent display having a plurality of scan lines and a plurality of data lines arranged in a matrix and a plurality of organic electroluminescent elements disposed between each of the plurality of scan lines and the plurality of data lines. In the method of driving an organic electroluminescent display device provided with a panel, Selecting a corresponding scan line by applying a selection signal to the scan line; When the data of the corresponding scan line is applied, a first current flows to the plurality of data lines in response to the data for an initial predetermined period during which the selection signal is applied, and the data for the remaining period during which the selection signal is applied. A second step of flowing a second current smaller than the first current through the plurality of data lines in response to the second data line; And And a third step of sequentially performing the first and second steps with respect to each of the plurality of scan lines.