KR20030096878A - Driving Circuit and Method for Organic Electro-Luminescent Displays - Google Patents

Abstract

PURPOSE: A driving circuit of an electroluminescence display device and a method for the same are provided to reduce the consumption energy required for charging the capacitor of the data line to a predetermined voltage by supplying the charge to the data line and recovering the supplied charge. CONSTITUTION: A driving circuit of an electroluminescence(EL) display device includes at least one external capacitors, at least one voltage sources(110), a plurality of data line switches and at least one voltage source switches. The external capacitors are arranged at the outside of the EL display panel for storing the charges supplied to the plurality of data lines and the charges recovered from the plurality of data lines. The voltage sources(110) adjust the voltage of the external capacitor. The plurality of data line switches are arranged between the external capacitor and the plurality of the data lines for supplying the charges to the plurality of the data lines and for recovering the charges of the data lines. And, the voltage source switches are connected between the data line switches and the external capacitors for keeping the voltage of the external capacitor constant.

Description

Driving Circuit and Method for Driving Organic Electroluminescent Display {Driving Circuit and Method for Organic Electro-Luminescent Displays}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive matrix organic electroluminescent display device, and more particularly, to reduce power consumption of a simple matrix organic electroluminescent display device using an energy regeneration (recycling) circuit composed of at least one capacitor and a plurality of switches. The present invention relates to a driving circuit and a driving method of an organic electroluminescent display device.

In general, an organic electroluminescent display device is a display device for electrically exciting a fluorescent organic compound to emit light, and is capable of displaying an image of N> M organic light emitting cells by voltage driving or current driving.

Hereinafter, an organic light emitting diode according to the related art will be described with reference to the accompanying drawings.

1 is a view for explaining the basic structure of a general organic electroluminescent device.

A general organic electroluminescent device has a structure of an anode (ITO), organic thin film layers, and a cathode (Metal), as shown in FIG.

In this case, the organic thin film layers formed between the anode and the cathode have a good balance between electrons and holes to improve the light emitting efficiency, such as an emitting layer (EML), an electron transport layer (ETL) and a hole transport layer (HTL). It has a multi-layer structure including), and also includes a separate electron injection layer (EIL) and a hole injection layer (HIL).

As such a method of driving the organic light emitting cell, there are a simple matrix method and an active matrix method using a thin film transistor (TFT).

The simple matrix method is to form the anode and the cathode to be orthogonal and to select and drive the cathode and anode lines, and the active driving method is to integrate a thin film transistor (TFT) and a capacitor in each pixel to maintain the voltage by the capacitor capacity It is a driving method.

FIG. 2 is a circuit diagram of a simple matrix organic electroluminescent display device for driving a simple matrix organic electroluminescent device according to the prior art, and FIG. 3 is a view illustrating a driving waveform of the simple matrix organic electroluminescent display device shown in FIG. 2.

Referring to FIG. 2, each pixel 100 may be represented as one diode and one capacitor, and each scan line S1, S2, S3 ... S _M and the data lines D1, D2, D3 ... The pixel is located at the intersection of D _N ), and each pixel emits light by the current applied to each of the diodes.

Each pixel's diode has a threshold voltage, and for the pixel to emit light, the voltage between the cathode and anode of the pixel's diode must be above the threshold voltage, which means that the voltage between the scan line and the data line to which each pixel is connected is thresholded. It is explaining that the voltage should be higher.

Therefore, the scan line driven when driving each pixel is connected to a low voltage. In this case, the data driver increases the voltage of the data line by applying current or voltage to the data line, and emits light when the threshold voltage is higher than the threshold voltage.

At this time, since the scan line which is not driven is connected to a high voltage, the voltage between the scan line and the data line is lower than the threshold voltage even when the voltage of the data line rises, thereby preventing light emission.

In addition, a pulse width modulation (PWM) method is generally used for expressing a gray scale, which is a method of expressing the gray scale by adjusting the emission time of each pixel. The gray level can be expressed by supplying a certain amount of current as time to express.

Each data line can be represented by a single capacitor whose size is equal to the size of the capacitor of one pixel multiplied by the total number of lines. Therefore, when driving by supplying current or voltage in the data driver, first, the diode of each pixel is turned on when the capacitor of the data line is charged and the voltage of the data line becomes higher than or equal to the threshold voltage. Flows to emit light.

If the current driven during the current driving is small compared to the size of the capacitor of the data line, the time taken to charge the capacitor of the data line is long, so that the actual time of emitting light is shortened compared to the desired time of light emission. A pre-charging driving method is used to reduce the charging time of the capacitor.

In general, there are two pre-charging driving methods. The first pre-charging driving method is a method in which the voltage of each data line is precharged close to the threshold voltage of the pixel and the driving current is applied to the data line. In this case, the driving current is a current to be applied to the pixel in order for the pixel to emit light of a desired brightness.

In order to accurately display gray scales when driving a simple matrix organic electroluminescent display using the PWM method, the pixel to be driven should emit light in proportion to the magnitude of the driving current applied at the same time as the driving current is applied. Even though the voltage of the data line is charged to the threshold voltage by using the charging driving method, it takes time to charge the voltage of the data line to a voltage for emitting light of a desired size, making accurate gradation expression difficult, especially in low gradation expression. There is a difficulty.

The second method of pre-charging is to drive the voltage of the data line to reach the desired voltage quickly. This is done by applying a large current to the data line at the start of the drive to quickly charge the capacitors of the data line. As a result, the voltage of the data line rises quickly, and when the desired voltage is reached, the voltage is driven as a driving current.

Referring to FIG. 3, each scan line is sequentially driven by a row driving circuit, and at the same time, the column driving circuit writes a voltage / current to each data line, and each data line is opened every time the writing of the voltage / current is completed. It will be connected to the lowest voltage of the drive circuit.

In the prior art, when the voltage drive is performed, the analog output buffer of the column driving circuit charges the data line quickly so that the above pre-charging is not required, but the column driving circuit is complicated. It may be difficult to express accurate gradation due to error or non-uniformity of IV characteristics of the organic electroluminescent device.

As described above, various methods for accurately expressing gradation are currently proposed and studied, but in general, there is a lack of technology regarding a low power consumption driving circuit and method for a simple matrix organic electroluminescent display. It is a very fatal disadvantage in operating portable electronic devices.

2 and 3, there is no energy recovery circuit or a driving method for energy saving in the simple matrix organic electroluminescent display device and the driving method thereof according to the prior art.

The present invention has been made to solve the problems of the prior art, a simple matrix organic material that can reduce power consumption by using a thermal drive energy recovery (recycling) circuit consisting of at least one capacitor and voltage source and a plurality of switches. It is an object of the present invention to provide a driving circuit and a driving method of an electroluminescent display.

The driving circuit of the present invention of the simple matrix organic electroluminescent display device for achieving the above object is connected to a column driving circuit and transmits a plurality of data voltages / currents for displaying an image signal according to the operation of the column driving circuit. An organic electric field consisting of a data line, a plurality of scan lines connected to a row driving circuit and orthogonal to the plurality of data lines, and an organic electroluminescent element configured in each of the plurality of pixels defined by the plurality of data lines and the scan lines An organic electroluminescent display device having a light emitting panel, comprising: an organic electroluminescent display device configured to be external to the organic electroluminescent panel and configured to store charges supplied to the plurality of data lines and charges recovered from the plurality of data lines. Capacitors, and write down for adjusting the voltage of the external capacitor A plurality of data line switches configured between at least one voltage source, the external capacitor and the plurality of data lines, respectively, for supplying charge of the external capacitor to each of the plurality of data lines or recovering charges of the data lines; One side is connected between the data line switch and the external capacitor, the tile side is configured to include at least one voltage source switch to maintain a constant voltage of the external capacitor.

Preferably, the external capacitor is composed of one or three, the voltage source is composed of one or three according to the number of the external capacitor, the external capacitor and the voltage source to charge the charge of the capacitor constituting the pixel. An energy regeneration circuit for discharging is constituted.

The voltage source is configured between the external capacitor and the data line.

Preferably, when the organic electroluminescent display is a mono-chrome organic electroluminescent display, the external capacitor and the voltage source are each configured as one, and when the organic electroluminescent display is a color organic electroluminescent display. There are three external capacitors and three voltage sources.

According to another aspect of the present invention for achieving the above object, a plurality of data lines connected to a column driving circuit and carrying a data voltage / current for representing an image signal, and a plurality of data lines connected to a row driving circuit An organic electroluminescent display device comprising: an organic electroluminescent panel comprising a plurality of scan lines configured to be orthogonal to a data line of and an organic electroluminescent element configured at each of the plurality of data lines and a plurality of pixels defined by the scan lines. A first step of increasing a voltage of the data line to a first set voltage as a charge is supplied from an external capacitor to the plurality of data lines to charge a capacitor constituting a pixel connected to the data line; The secondary voltage is applied to a plurality of data lines raised to the first set voltage in the furnace. A second step of emitting light by the light emitting element constituting the pixel according to writing the set voltage; a third step of recovering the charge of the capacitor constituting the pixel to the external capacitor; The fourth step of discharging all the charges and simultaneously setting the voltage of the external capacitor to the set voltage through the voltage source.

Preferably, at least one data line switch is configured between each of the data lines and the external capacitor. In the first step, the respective data line switches are short-circuited, and in the second step, the respective data lines. A switch is in an open state, and in the third step, each of the data line switches is short-circuited, and a voltage source switch in which one side is connected between the external capacitor and the data line and the other side is connected to the voltage source is short-circuited in the fourth step. Is in.

Preferably, in the third step, the charge charge of the capacitor constituting the pixel is recovered to the external capacitor, thereby saving energy required to charge / discharge the capacitor connected to each data line.

The voltage rising width of the data line, which rises as charge is supplied to the capacitor in the first step, and when the light emitting device emits light as the column driving circuit writes a voltage / current in the second step. The voltage rise of the data line is made to have the same rise.

Preferably, the primary set voltage is a pre-charge voltage, and the secondary set voltage is greater than or equal to a threshold voltage.

Preferably, in the case where the electroluminescent element constituting the pixel is a color electroluminescent element, after the first step, a second level of a second level is different in a plurality of data lines raised to the first set voltage in the column driving circuit. Write the voltage / current with the set voltage.

Preferably, when the electroluminescent element constituting the pixel is a color electroluminescent element, the external capacitor supplies different levels of charges to the plurality of data lines by using at least three external capacitors, thereby providing each of the data lines. The voltages of the voltages are increased to the first set voltages of different levels and the second set voltages of different levels are applied to the plurality of data lines that are raised to the first set voltages of the respective different levels in the column driving circuit. Write the voltage / current so that

And when the organic electroluminescent device is a color organic electroluminescent display, the data line is operated by operating the data line switch between the one external capacitor and the data line of the pixel, including one external capacitor when driving the data line. The power supply and recovery of the data line can be reduced by supplying and retrieving charges between them.

Preferably, when the organic electroluminescent device is a color organic electroluminescent display, the data line is driven by manipulating data line switches between the three external capacitors and the data lines of the pixel, including three external capacitors when driving the data line. By supplying and retrieving charges between lines, power consumption when driving the data lines is reduced.

Preferably, the voltage source for maintaining a constant voltage on the external capacitor is used to adjust the voltage of the external capacitor by using one or three.

Preferably, the voltage of the voltage source is a threshold voltage of each pixel, and pulse code modulation driving is performed by a current driving method.

Preferably, a large current is written to the data line to pre-charge and a drive current is written to drive pulse code modulation.

Preferably, pulse code modulation driving is performed by writing a voltage to a data line using an analog buffer of the column driving circuit.

Preferably, the low power consumption is realized by reducing the fluctuation range of the data line voltage by lowering only the voltage below the threshold voltage without completely discharging the capacitor constituting each pixel connected to the data 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.

1 is a view for explaining the basic structure of a general organic electroluminescent device

2 is a circuit diagram of a simple matrix organic electroluminescent display device for driving a simple matrix organic electroluminescent device according to the related art.

FIG. 3 is a view illustrating driving waveforms of the simple matrix organic electroluminescent display of FIG. 2.

4 is a circuit diagram of a simple matrix organic electroluminescent display including an energy recycling (recycling) circuit according to a first embodiment of the present invention.

FIG. 5 is a view illustrating driving waveforms of the simple matrix organic electroluminescent display of FIG. 4.

6 is a circuit diagram of a simple matrix organic electroluminescent display including an energy regeneration (recycling) circuit according to a second embodiment of the present invention.

FIG. 7 illustrates driving waveforms of the simple matrix organic electroluminescent display of FIG. 6.

8 is a circuit diagram of a simple matrix organic electroluminescent display device including an energy regeneration (recycling) circuit according to a third embodiment of the present invention.

9 illustrates driving waveforms of the simple matrix organic electroluminescent display of FIG. 8.

10 is a view showing a drive waveform during current driving using an energy regeneration (recycling) drive circuit according to the present invention.

FIG. 11 is a view showing driving waveforms during pre-charging current driving using an energy regeneration (recycling) driving circuit according to the present invention; FIG.

12 is a view for explaining driving waveforms at the time of voltage driving using the energy regeneration (recycling) driving circuit according to the present invention;

FIG. 13 is a view illustrating driving waveforms for explaining a low power consumption driving method of a simple matrix organic electroluminescent display according to the present invention.

＊ Description of symbols for main parts of the drawings ＊

100: pixel 110: voltage source

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

The present invention is to reduce the power consumption when driving a simple matrix organic electroluminescent display device, at least one capacitor (one or three), a plurality of switches and also at least one voltage source (one or three) This system reduces the power consumption used to raise the voltage of the data line by constructing a thermal drive energy regeneration (recycling) circuit, and uses the power consumption of the row drive device as a row driving energy regeneration (recycling) circuit using a plurality of switches. To reduce power consumption.

Hereinafter, exemplary embodiments of a driving circuit and a driving method of a simple matrix organic electroluminescent display device according to the present invention will be described with reference to the accompanying drawings.

FIG. 4 is a circuit diagram of a simple matrix organic electroluminescent display device including an energy regeneration (recycling) circuit according to a first embodiment of the present invention, and FIG. 5 is a driving waveform of the simple matrix organic electroluminescent display device shown in FIG. Drawing.

In the first embodiment of the present invention, energy recycling (recycling) consisting of a mono-chrome simple matrix electroluminescent display, a plurality of switches, one voltage source (Vcom) 110 and one external capacitor (Cext) ) Consists of a circuit.

Referring to FIG. 5, S1 and S2 are driving voltage waveforms of a first row and a second row, respectively, and D1 is a driving voltage waveform of a first data line.

In the first step (1) of the driving waveform of the data line, a switch (data line switch) connected to each data line is short-circuited and at the same time, electric charge is supplied from the external capacitor Cext to the capacitor connected to each data line. The voltage on the line rises.

Next, in the second step (2) and the third step (3), the voltage of the data line is increased by writing the voltage / current to the data line in the column driving circuit, and the current is applied to the diode of the turned-on pixel 100. It flows and emits light. At this time, the data line switch (referred to as a switch for convenience of description) is in an open state.

Subsequently, in the fourth step (4), the switch connected to each data line is short-circuited again so that the charge in the capacitor of the data line is recovered to the external capacitor Cext and the voltage of the data line is lowered.

In the fifth step (5), the voltage of the data line is connected to the lowest voltage of the column driving circuit, and at the same time, the voltage source switch (referred to as a switch for convenience of description) that is connected to the voltage source is short-circuited so that the voltage of the external capacitor (Cext) It is adjusted to be equal to the voltage of this voltage source. At this time, by adjusting the voltage of the voltage source in the fifth step (5), the voltage of the external capacitor (Cext) is changed, the magnitude of the voltage may be a threshold voltage or other voltage depending on the driving method.

At this time, when the charge is supplied from the external capacitor to the data line in the first step (1), the capacitance of the external capacitor (Cext) is very large compared to the size of the capacitor of the data line. Charge close to voltage.

In addition, the charge that the external capacitor Cext supplied to the capacitor connected to each data line in the first step (1) is recovered in the fourth step (4), thereby reducing the energy required to charge / discharge each data line. do.

In order to obtain the optimal energy saving effect, the optimum energy saving is achieved when the voltage rise of the data line in the first step (1) is the same as the rise of the data line in the second step (2) and the third step (3). The effect can be obtained.

FIG. 6 is a circuit diagram of a simple matrix organic electroluminescent display device including an energy regeneration (recycling) circuit according to a second embodiment of the present invention. FIG. 7 is a driving waveform of the simple matrix organic electroluminescent display device shown in FIG. 6. Drawing.

In a simple matrix organic electroluminescent display according to a second embodiment of the present invention, an energy regeneration consisting of a color simple matrix organic electroluminescent display, a plurality of switches, one voltage source (Vth) and one external capacitor (Cext) It comprises a (recycling) circuit.

Referring to FIG. 7, S1 and S2 are driving voltage waveforms of a first row and a second row, respectively, and D1 and D2 are driving voltage waveforms of a first data line and a second data line, respectively.

In the first step (1) of the driving waveform of the data line as shown in FIG. 7, the switch connected to each data line is short-circuited and the charge is supplied from the external capacitor Cext to the capacitor of each data line. Will increase the voltage.

Subsequently, in the second step (2) and the third step (3), the column driving circuit writes a voltage / current suitable for each red pixel, green pixel, and blue pixel in the data line. The voltage of the data line rises and a current flows in the diode of the turned-on pixel to emit light. In other words, when the color of the diode, which is a light emitting device, is different, the voltage / current corresponding thereto is appropriately written in each data line.

In the fourth step (4), the switch connected to each data line is short-circuited again so that the charge in the capacitor of the data line is recovered to the external capacitor Cext and the voltage of the data line is lowered. In (5), the voltage of the data line is connected to the lowest voltage of the column driving circuit, and the switch connected to the voltage source Vth is shorted to adjust the voltage of the external capacitor Cext.

At this time, when the large-capacity external capacitor Cext in the first step (1) recovers the charges supplied to the capacitors of the respective data lines in the fourth step (4), the second step (2) and the third step (3). Since the rising width of the rising data line voltage varies depending on the type of each pixel (red, green, blue), the rising width of the data line voltage in the first step (1) and the second step (2) and the third step ( Since the rising widths of the data line voltages in 3) cannot be equal, the energy saving effect is lower than in the case of FIGS. 4 and 5 which describe the first embodiment of the present invention.

In addition, by charging the red, green, and blue data lines at the same time in one external capacitor Cext, it is impossible to charge them with different threshold voltages. It is not used in the pre-charging drive method.

FIG. 8 is a circuit diagram of a simple matrix organic electroluminescent display device including an energy regeneration (recycling) circuit according to a third embodiment of the present invention. FIG. 9 is a driving waveform of the simple matrix organic electroluminescent display device shown in FIG. 8. Drawing.

In the simple matrix organic electroluminescent display device according to the third embodiment of the present invention, a color simple matrix organic electroluminescent display device, a plurality of switches, at least one or more preferably three voltage sources (Vred, Vgreen, Vblue) and three And an energy regeneration (recycling) circuit composed of external capacitors (Cred, Cgreen, Cblue).

Each voltage source (Vred, Vgreen, Vblue) and external capacitors (Cred, Cgreen, Cblue) have a data line of a red pixel, a data line of a green pixel, and a blue pixel of an organic electroluminescent display. It is connected to each data line.

FIG. 9 illustrates the driving method and waveforms of FIG. 8. When the driving method is described with reference to the driving waveform of FIG. 9, S1 and S2 are driving voltage waveforms of a first row and a second row, respectively. And D2 are driving voltage waveforms of the first data line and the second data line, respectively.

In the driving waveform of the data line, the first step (1) is a short circuit of the switch connected to each data line and at the same time the red line of the red pixel data line from each of the three external capacitors (Cred, Cgreen, Cblue) The charge is supplied to the capacitor, the capacitor of the data line of the green pixel, and the data line capacitor of the blue pixel, respectively, so that the voltage of the data line of the red pixel, the voltage of the data line of the green pixel, and The voltage of the data line of the blue pixel rises differently.

Next, the second and third steps (2) and (3) write a voltage / current to the data line for each red pixel, green pixel and blue pixel in the column driving circuit. As a result, the voltage of the data line increases and a current flows through the diode of the turned-on pixel to emit light.

In the fourth step (4), the switch connected to each data line is short-circuited again so that the charges in the capacitors of each data line are recovered to each of three external capacitors (Cred, Cgreen, and Cblue). The voltage will drop.

Next, in the fifth step 5, the voltage of the data line is connected to the lowest voltage of the column driving circuit, and at the same time, the switch connected to the voltage source is shorted to adjust the voltage of the external capacitors Cred, Cgreen, and Cblue.

Unlike the case of FIGS. 6 and 7 illustrating the second embodiment of the present invention, a red pixel data line, a green pixel data line, and a blue pixel data line each have three large capacitances. Driven by external capacitors (Cred, Cgreen, Cblue) having a, the rising width of the data line voltage in the first step (1) and the voltage rising width of the data line in the second step (2) and the third step (3) Since it can be the same, it is possible to obtain an optimal energy saving effect. In addition, a pre-charging driving method may be used in which the voltage of the data line is charged to a threshold voltage and then driven as a driving current.

Fig. 10 is a view showing drive waveforms during current driving using an energy regeneration (recycling) drive circuit according to the present invention.

10 illustrates a case in which a voltage of a data line is increased to a predetermined voltage in an energy regeneration circuit when driving a simple matrix organic electroluminescent display device according to the present invention, and a current is driven when a data line is driven in a column driving circuit. Applicable to the first and third embodiments of the present invention, S1 and S2 show the drive waveforms of the first scan line and the second scan line, and I _D1 represents the first data of the column drive circuit. The output current waveform is shown, with D1 representing the voltage of the first data line.

At this time, in the voltage waveform of the data line of D1, in the first step (1), the voltage of the data line is charged up to a constant voltage in the energy regeneration (recycling) circuit, and in the second step (2), the column drive circuit is connected to the data line. The data line is charged by the current waveform of I _D1 to be written, and the pixel connected to the first scan line and the first data line emits light to perform PWM driving. In the third step (3), the data line is charged. The charge of is recovered to the external capacitor, and in the fourth step (4), the charge of the data line is discharged and the external capacitor and the voltage source are connected to make the voltage of the capacitor a constant voltage. When the driving method of FIG. 10 is used, the voltage of the voltage source is made the threshold voltage of the pixel (one method of precharging), thereby minimizing the time taken for the diode to turn on.

FIG. 11 is a view showing driving waveforms during pre-charging current driving using an energy regeneration (recycling) driving circuit according to the present invention.

11 is a view illustrating a method of driving a simple matrix organic electroluminescent display device according to the present invention, increasing a voltage of a data line to a constant voltage in an energy regeneration circuit and pre-loading a large current when driving a data line in a column driving circuit. The waveform in the case of charging and PWM current driving is shown and can be applied to the first, second and third embodiments of the present invention.

Where S1 and S2 show the drive waveforms of the first scan line and the second scan line, I _D1 shows the first data output current waveform of the column drive circuit, and D1 shows the voltage of the first data line. .

In the voltage waveform of the data line of D1, in the first step (1), the voltage of the data line is charged to a constant voltage in an energy regeneration (recycling) circuit.

In the second step (2), the data line is rapidly charged by the large current waveform of I _D1 which is written to the data line in the column driving circuit, and the pixel connected to the first scan line and the first data line is It emits light and is driven by applying a PWM method.

Subsequently, in the third step (3), the pixel connected to the first scan line and the first data line emits light by the driving current waveform of I _D1 which is written to the data line in the column driving circuit.

In the fourth step (4), the charge of the data line is recovered to the external capacitor. In the fifth step (5), the charge of the data line is discharged and at the same time, the external capacitor and the voltage source are connected to convert the voltage of the capacitor into a constant voltage. Make.

At this time, when the driving method of FIG. 10 is used, the voltage of the voltage source is adjusted to a voltage corresponding to 1/2 of the voltage of the data line in the third step (3), so that the power consumption when driving with the driving circuit and the driving method is adjusted. Can be minimized.

12 is a view for explaining driving waveforms at the time of voltage driving using the energy regeneration (recycling) driving circuit according to the present invention.

12 is a diagram illustrating an example of increasing a voltage of a data line to a constant voltage in an energy regeneration circuit when driving a simple matrix organic electroluminescence display device according to the present invention, and using an analog buffer (OP−) when driving a data line in a column driving circuit. The waveform when driving with a voltage using AMP) is shown and can be applied to the first, second and third embodiments of the present invention.

Here, S1 and S2 show driving waveforms of the first scan line and the second scan line, and D1 shows the voltage of the first data line.

In the voltage waveform of the data line of D1, in the first step (1), the voltage of the data line is charged up to a constant voltage in the energy regeneration (recycling) circuit, and in the second step (2) by the analog buffer of the column drive circuit. The data line is charged so that the pixel connected to the first scan line and the first data line emits light, thereby driving by applying a PWM method.

In the third step (3), the charge of the data line is recovered to an external capacitor.

Subsequently, in the fourth step 4, the charge of the data line is discharged and an external capacitor and a voltage source are connected to make the voltage of the capacitor a constant voltage.

In this case, when the driving method of FIG. 10 is used, the power consumption during driving can be minimized by matching the voltage of the voltage source to a voltage corresponding to 1/2 of the data line voltage in the second step (2).

FIG. 13 is a view illustrating a driving waveform for explaining a low power consumption driving method of a simple matrix organic electroluminescent display according to the present invention.

FIG. 13 illustrates a method of driving low power consumption of a simple matrix organic electroluminescent display device, wherein a voltage of a data line is driven at a predetermined voltage or more when driving a data line. Since the organic electroluminescent pixel has a threshold voltage, if the voltage between the driving data line and the scanning line is lowered below the threshold voltage, the pixel does not emit light. Therefore, the data line is not discharged completely. When writing the voltage / current from the driving circuit, an energy saving effect due to the reduction in the voltage fluctuation range can be obtained.

In this case, S1 and S2 show driving waveforms of the first scan line and the second scan line, and D1 shows the voltage of the first data line. In the voltage waveform of the data line of D1, in the first step (1), the data line is charged by a voltage / current written to the data line in the column driving circuit and is connected to the first scan line and the first data line. The pixel emits light and is driven by the PWM method. In the second step (2), the voltage of the data line is lowered below the threshold voltage of the pixel in the column driving circuit. Therefore, since the voltage width at which the data line is to be charged during driving is reduced, low power consumption is possible, which is applied to the current driving, the pre-charging current driving, and the voltage driving mentioned in FIGS. 10 to 12 to reduce power consumption. can do.

The energy regeneration circuit used in the present invention is composed of one or three external capacitors, a plurality of switches, and one or three voltage sources, and charges the data line capacitors to a constant voltage by supplying and recovering the data lines. To reduce the energy consumed.

In other words, the energy saving effect of charging the capacitor of the data line is determined by the voltage of the voltage charged by the energy regeneration circuit and the rise of the data line voltage by the data driving circuit. When the voltage is equal to the voltage charged by the circuit, the optimal energy is saved.

In addition, the energy regeneration circuit used in the present invention can be implemented by adding a switch and a capacitor without significantly changing the structure of the existing data driver.

As described above, the organic electroluminescent display driving circuit and the driving method according to the present invention can reduce power consumption, and in particular, by reducing power consumption of the thermal driving circuit (40% or more), The usable time of the battery used further increases. In addition, as described above, the driving circuit according to the present invention can be simply implemented without large changes in the structure of the existing data driver.

If a portable electronic device having enhanced portability and functionality by applying the technology of the present invention is widely spread, personal information may be more convenient since information exchange and communication between people become more smooth.

Claims (18)

A plurality of data lines connected to a column driving circuit and transferring data voltages / currents for displaying an image signal according to an operation of the column driving circuit, and a plurality of data lines connected to the row driving circuit and orthogonal to the plurality of data lines An organic electroluminescent display device having an organic electroluminescent panel comprising a scanning line and an organic electroluminescent element constituted by each of the plurality of data lines and the plurality of pixels defined by the scanning lines. At least one external capacitor configured outside the organic electroluminescent panel and configured to store charges supplied to the plurality of data lines and charges recovered from the plurality of data lines; At least one voltage source for adjusting the voltage of the external capacitor; A plurality of data line switches respectively configured between the external capacitor and the plurality of data lines to supply charge of the external capacitor to each of the plurality of data lines or to recover charges of the data lines; One side is connected between the data line switch and an external capacitor, and the tile side is connected to the voltage source and comprises at least one voltage source switch for maintaining a constant voltage of the external capacitor, characterized in that the organic light emitting display device Driving circuit. The capacitor of claim 1, wherein the external capacitor is one or three, and the voltage source is configured by one or three according to the number of the external capacitors, wherein the external capacitor and the voltage source constitute the pixel. A drive circuit for an organic electroluminescent display device comprising an energy regeneration circuit for charging and discharging electric charges. The driving circuit of claim 1, wherein the voltage source is configured between the external capacitor and the data line. The display device of claim 1, wherein when the organic electroluminescent display is a monochrome organic electroluminescent display, the external capacitor and the voltage source are configured as one, and the organic electroluminescent display is a color organic electroluminescent display. In the case of the driving circuit of the organic electroluminescent display device, characterized in that the external capacitor and the voltage source is composed of three. A plurality of data lines connected to a column driving circuit and transferring data voltage / current for representing an image signal, a plurality of scanning lines connected to a row driving circuit and configured to be orthogonal to the plurality of data lines, and the plurality of data lines An organic electroluminescent display device comprising an organic electroluminescent panel composed of organic electroluminescent elements formed in each of a plurality of pixels defined by and scanning lines, A first step of raising a voltage of the data line to a first set voltage as a charge is supplied from an external capacitor to the plurality of data lines to charge a capacitor constituting a pixel connected to the data line; A second step of causing the light emitting element of the pixel to emit light by writing a voltage / current to the plurality of data lines raised to the first set voltage in the column driving circuit so as to be a second set voltage; A third step of recovering the charge of the capacitors constituting the pixel to the external capacitor; And discharging all the charges of the capacitors constituting the pixel, and simultaneously adjusting the voltage of the external capacitor to the set voltage through a voltage source. 6. The method of claim 5, wherein at least one data line switch is configured between each data line and the external capacitor, wherein each of the data line switches is short-circuited in the first step, and each of the data line switches is shorted in the second step. The data line switch is in an open state, and in the third step, each of the data line switches is in a short state, And a voltage source switch of which one side is connected between the external capacitor and the data line and the other side is connected to the voltage source is in a short circuit state in the fourth step. The organic electric field of claim 5, wherein in the third step, charge charge of the capacitor constituting the pixel is recovered to the external capacitor, thereby saving energy required to charge / discharge the capacitor connected to each data line. A method of driving a light emitting display device. 6. The light emitting device of claim 5, wherein the voltage rise of the data line rises as charge is supplied to the capacitor in the first step, and the light emitting device emits light as the thermal drive circuit writes a voltage / current in the second step. The method of driving an organic light emitting display device, wherein the voltage rise of the data line has the same rise. The method of claim 5, wherein the primary set voltage is a pre-charge voltage, and the secondary set voltage is equal to or greater than a threshold voltage. The electroluminescent device constituting the pixel is a color electroluminescent device. After the first step, And writing a voltage / current to a plurality of data lines raised to the first set voltage in the column driving circuit at a second set voltage of different levels. The electroluminescent device constituting the pixel is a color electroluminescent device. The external capacitor supplies different levels of charge to the plurality of data lines by using at least three external capacitors to raise the voltage of each data line to a first set voltage of different levels, An organic electroluminescence display for writing a voltage / current to a plurality of data lines raised to the first set voltages of the different levels in the column driving circuits so as to be the second set voltages of the different levels Method of driving the device. 7. The method of claim 6, wherein when the organic electroluminescent element is a color organic electroluminescent display, the data line switch is operated between the one external capacitor and the data line of the pixel, including one external capacitor when driving the data line. The driving method of the organic electroluminescent display device according to the present invention is to reduce power consumption when driving the data lines by supplying and recovering charges between the data lines. The method of claim 6, wherein when the organic electroluminescent device is a color organic electroluminescent display device, three external capacitors are included in the data line driving operation to manipulate data line switches between the three external capacitors and the data lines of the pixel. The driving method of the organic light emitting display device according to claim 1, wherein the power consumption during driving of the data line is reduced by supplying and recovering charges between the data lines. The method of claim 5, wherein one or three voltage sources for maintaining a constant voltage in the external capacitor are used to adjust the voltage of the external capacitor to be constant. 6. The driving method of an organic electroluminescence display device according to claim 5, wherein the voltage of the voltage source is a threshold voltage of each pixel, and pulse code modulation driving is performed by a current driving method. 6. The method of claim 5, wherein a large current is written into the data line, pre-charged, and a driving current is written to perform pulse code modulation driving. 6. The method of claim 5, wherein a pulse code modulation drive is performed by writing a voltage to a data line using an analog buffer of the column driving circuit. The organic field of claim 5, wherein the organic electric field is realized by reducing the variation of the data line voltage by lowering only the voltage below the threshold voltage and not completely discharging the capacitor constituting each pixel connected to the data line. A method of driving a light emitting display device.